We’ve got just the proposed solution for you! Our article proposes the use of Fireworks Automation production lines to revolutionize the way fireworks are made. Here are the two major problems in the fireworks industry that our proposed solution addresses:

• Low production efficiency: With the current production mode, fireworks manufacturers struggle to keep up with large orders during festivals and holidays.
• Safety concerns: The production process of fireworks involves gunpowder and can be dangerous, especially when workers are not highly skilled and engage in illegal practices.

Our automated production line solves these problems by streamlining the production process and reducing the need for manual labor.

Here’s what you can expect from our article:

• A detailed plan for the automated production line, including the importance of weighing accuracy and mixing homogeneity.
• In-depth data analysis of how to improve weighing accuracy through changes to mechanical agencies.
• Strategies for avoiding errors in the production process, including stepper motors.
• Comprehensive research on mixing evenness, including the algorithm of mixing uniformity and the selection of appropriate mixers.
• Information on the control system (machine learning) used in the automated production line.
• Kinematical simulation of the mixed weighing mechanism to demonstrate its reliability.

The proposed solution is a game-changer for the fireworks industry, with the potential to reduce accidents and improve production efficiency significantly. Join us in creating social value using automated production lines in fireworks manufacturing!

Abstract

At present, there are two major problems in the fireworks industry; firstly, the production mode of the fireworks industry leads to low production efficiency. At every festival and New Year, in the face of large orders, they can only look and sigh; Secondly, the production process of fireworks almost did not complete production iterative process without gunpowder. Especially when worker quality is not very high, an illegal operation is regular, but it can largely increase the probability of catastrophic accidents. Because of this situation, this article puts forward the idea of automated production lines for fireworks. We hope it will change the fireworks industry status.

After understanding the fireworks industry background, this paper has established the overall plan for the automated production line. The overall plan, it has defined the status and significance of mine. This paper mainly revolves around two points, one is weighing accuracy, and the other one is mixing homogeneity. The two problems carry a long history. The current study is in common with previous research and also has its own unique place in the industry.

In the research of weighing precision, firstly, we analyzed how to improve weighing accuracy by changing mechanical agencies. We mainly study this area by changing the lead of the stockscrew, the height of the thread, and the diameter of the stockscrew. The second problem is how to avoid some errors. Taking the error of the whereabouts, for example, it can avoid the error when we choose the stepper motor. In mixing evenness research, first of all, we should understand the algorithm of mixing uniformity, know the mixing effect and applications of all kinds of mixers, select the suitable type of mixer, and then study and design them to catch the characteristics of the industry. Due to fewer control points, the control system (machine learning) can compete with the PLC of the FX2N series. This paper studies (case studies) the stepper motor control with PLC and then draws electrical control schematic figure and ladder diagram. Finally, the design of the mixed weighing mechanism has carried on the kinematical simulation; it fully displays its function, and at the same time, it also verified the reliability of this plan. The design and research of this paper are challenges for previous fireworks industry production modes. Through the research, the fireworks automatic production line can significantly reduce the accident rate, improve production efficiency and create social value.

Keywords: fireworks, automatic, production line, feeder, mixer

Chapter 1: Introduction

1.1 Problem Statement

When it comes to the fireworks production that we will study, its main component is gunpowder, mainly used for burning or exploding. As one of China’s Four Great Inventions, gunpowder is still something that the Chinese people take great pride in today. Gunpowder has brought a lot of glory to our country, but it has also caused many disastrous accidents in production. The emergence of fireworks and firecrackers is purely for visual enjoyment, and the intention is good. However, many accidents have also occurred in production. This type of production related to gunpowder can be described as a double-edged sword, bringing benefits while also posing safety hazards.

Everything is flammable and explosive material in the production process of fireworks, from raw materials to finished products. In this process, slight negligence from the operator can cause a fire or explosion. An accident could cause a fire or, in more serious cases, injuries or fatalities to the producers. Moreover, if a worker who lacks skilled operation performs an incorrect operation and violates the operating emergency procedures, such as scratching, colliding, dragging, using excessive force, and not using specialized manufacturing tools, the probability of an accident dramatically increases. The accident rate caused by the above reasons accounts for nearly 90% of accident statistics.

Therefore, the two main problems the fireworks industry faces are that gunpowder, as an indispensable item in production, makes the production process full of explosive material danger, and the traditional production methods and techniques result in extremely low labor productivity.

5 Major Problems with Fireworks Industry and Proposed Solution:

1.   Low production efficiency due to traditional production methods.

2.   Safety concerns due to reliance on gunpowder in the production process.

3.   Introduction of automated production lines as a solution.

4.   Focus on weighing accuracy and mixing homogeneity in production.

5.   Study of mechanical agencies and control systems (machine learning) to improve production processes.

1.1.1 Accidents Caused by Gunpowder Itself

Accidents caused by gunpowder itself can mainly be divided into the following categories:

1.   Improper use of potassium chlorate in the production of firecrackers is a significant cause of accidents

Statistics show that approximately 8 out of 9 fireworks explosions yearly are caused by the improper use of potassium chlorate. Although the country and provinces strictly prohibit the use of potassium chlorate in the production of fireworks and firecrackers each year, some enterprises still take risks driven by interests.

1.   Violation of regulations and procedures is the direct cause of accidents

There have been 11 consecutive fireworks accidents, and the common factor in these accidents is the existence of illegal operations to varying degrees. Illegal operations in the medicine workshop caused four accidents, and three were caused by illegal operations in the mixing workshop. Statistics show that accidents caused by illegal operations in these two workshops alone account for 64% of the total accidents. It is worth mentioning that a burning and explosion accident occurred at the Zhushajing Fireworks Factory in Yangjiaotang Town, Qiyang County. The main cause of the incidentt was the shortage of factory buildings, which led to the illegal storage of fireworks and two operators crushing lumps of potassium chlorate in the raw material warehouse. It seriously violated operating regulations.

1.   Hiring unqualified employees increases safety hazards

Currently, the problem of difficulty in recruiting workers is becoming increasingly prominent in society, and this is also the case in fireworks production enterprises. Especially in some non-main producing areas, this problem is severe, such as Shaoyang, Hengyang, Changde, Chenzhou, and Yongzhou. Some fireworks production enterprises have to hire elderly people, disabled people, women with lower education levels, or even child labor, which seriously violates labor employment regulations. Even in non-main producing areas, it is common to blindly hire unqualified special operation personnel who have been dismissed from the main producing areas. Often these people also call themselves “masters.” Still, they do not seriously follow labor safety technical regulations in their work and bring their bad habits of violating regulations into non-main producing areas, which can be said to be playing with their own lives.

1.   Relaxing safety management due to the use of “safe” drugs

Although the measures of banning the use of potassium chlorate and using “safe” drugs instead have greatly reduced the occurrence of fireworks accidents, fireworks, and firecrackers still have the basic characteristics of being flammable and explosive, so production operations must not be taken lightly. Once, an explosion occurred in the medicine room of Huashao Firecracker Factory in Ningxiang County. The medicine and pancake workers were killed on the spot, and the drugs used were prepared with “safe” oxidants. The so-called “safe” is relative. If it is believed that using “safe” drugs can be arbitrary in production operations, then it is entirely wrong. Vigilance must still be maintained during this process.

1.   Environmental factors increase the pressure of safety production

In recent decades fireworks export enterprises have to ship their products before specific dates due to various special reasons. The effective production time of fireworks and firecrackershas been reduced by half or even more. As a result, fireworks manufacturers will extend the working hours of laborers and arrange production tasks beyond their capacity. In addition, factors such as market price fluctuations, market demand fluctuations, and hasty supply times have prompted production enterprises to rush their goods, which has greatly increased the pressure on fireworks safety production, especially in May and June, when this phenomenon may become more serious.

Marx once said, “Production is subject to certain natural laws, and accidents occur as a punishment for violating these laws.” Therefore, if we want to produce by hand, we must take care of various matters in accordance with the characteristics of gunpowder. Suppose this type of production will have many inconveniences, seriously affecting production efficiency. Fortunately, we can take the initiative. If we change our thinking, the situation will be different. To achieve the goal of safety production, in addition to manual production, it can also be achieved by reducing direct contact between workers and drugs, that is, by minimizing the participation of people at the construction display site. A more reliable method is to study the full mechanical automation of each link in producing fireworks.

The relevant departments of the state fireworks industry have stated that they are actively improving the mechanization level of fireworks and firecracker production, making great efforts to improve the quality and safety level of fireworks and firecrackers, and fully realizing the industrialization of the fireworks industry. In addition, the article “Promoting the Upgrading of the Fireworks Industry” [13] pointed out that industrialization based on factory production in the fireworks industry is an crucial role of industry upgrading. However, due to current conditions, the mechanization level of China’s fireworks and firecracker industry still needs to improve, and the development of mechanization in the fireworks and firecracker industry is currently only a direction. The traditional fireworks industry is a typical labor-intensive industry characterized by manual operations, many workers, low production efficiency, and a high risk of safety hazards. Nowadays, with the development of machinery additive manufacturing in the fireworks and firecracker industry, individual-shaped technical equipment is already developed for important production processes, such as tying machines, fuse machines, and equipment for remote electronic control. To a certain extent, this improves production conditions, making production safer. It is of great significance to the operators who perform dangerous operations. As a result, the number of operators performing dangerous operations will relatively decrease, and people and drugs can be effectively isolated, ensuring safe production. According to insiders, the additive manufacturing equipment for fuse machines, tying machines, and automatic loading machines has been designed and manufactured successfully. It has been put into production by manufacturers and will be promoted nationwide, making the mechanization of the fireworks industry just around the corner. However, in the future, the process of promoting the mechanization of fireworks manufacturing production needs to be continued, and a sustainable development strategy should be implemented in China’s fireworks industry. In some highly industrialized production enterprises, these various machines that have emerged have brought tremendous power to the production of enterprises.

1.1.2 The Current State of Extremely Low Labor Productivity

Researching the production process is to improve the efficiency of fireworks production. China’s fireworks production and manufacturing machinery are still at the lower end, with various types of machinery of different levels, low production, and manufacturing precision. Although China is the birthplace of fireworks machinery manufacturing, once advanced and high-end fireworks production equipment is needed, it has to be imported from developed countries such as Japan. Moreover, the factorization process of fireworks manufacturing enterprises is slow, and the mechanization process is even slower.

As is well known, China has a large population, and the demand for fireworks and firecrackers during festivals is enormous, making supply unable to meet demand. With China’s accession to the WTO [14] in 2005, the market has fully opened, and opportunities and challenges have arisen in various industries [15]. It has provided a broader space and better opportunities for fireworks production enterprises to sell their products. In other words, fireworks have welcomed international market demand, and the challenge [16] we face is how to improve production efficiency, which is an urgent problem to be solved.

Fireworks have conquered the world with gorgeous visual effects [17] and ever-changing artistic beauty. Especially in the 2008 Beijing Olympic Games opening ceremony directed by Zhang Yimou, the artistic beauty of fireworks was brought to full play, and fireworks were pushed to various countries in the world. From then on, lighting fireworks during major festivals and events has become the first choice of countries worldwide, with a trend of becoming increasingly popular. It has activated the demand for our national specialty worldwide, raising the fame of China’s fireworks globally. With modern society’s rapid development and progress, the atmosphere created by lighting fireworks has become a high-level artistic enjoyment of human cultural life.

Although the fireworks industry [19] occupies a stable position in social demand, there needs to be a unified national standard. Looking back to the late 1980s, when firecrackers had been a folk custom in China for over a thousand years, they had only become an economic industry for a few decades. As the safety management of firecracker enterprises relied on simple experience, industry standards were also in a state of vacuum. A senior expert in the fireworks industry once frankly stated, “There were almost no fireworks industry standards in the 1980s.” The “Liuyang Fireworks Development Report” also confirmed this person’s experience. At that time, the Ministry of Light Industry and the Ministry of Agriculture promulgated the “Provisional Regulations on Safety Production Management of Fireworks and Firecrackers” in 1979, and China promulgated the “Provisional Measures for Safety Production Management of Fireworks and Firecrackers” in 1988.

This state continued for more than a decade. However, due to technological advancements, it was discovered that the use of fireworks products could lead to environmental hazards [20]. The survival of the fireworks industry became a hotly debated topic throughout the country, and the implementation of policies such as institutional (national institute) reforms subsequently led to a delay in the development of national standards for the fireworks industry. Data provided (data collection) by the National Fireworks Standards Committee shows that within the 14 years since its establishment in 1989, the committee has organized the formulation of 14 standards. However, as the fireworks industry transitioned from an experiential era to a regulatory era, the significance of the aforementioned standards for the industry’s development cannot be underestimated. To better ensure the personal safety of practitioners and to better manage fireworks production, the country has implemented the “Labor Safety Technical Regulations,” “Factory Design Safety Standards” [21], and the public safety standard “Firework Display Safety Regulations.” In addition, industry standards such as “Safety and Quality Implementation” and “Counting and Sampling Inspection Rules” have been introduced. It has provided good standards for the fireworks industry and has broken the historical predicament of traditional industries having no standards to rely on. However, for those managing the production, manufacturing, and sales of fireworks for many years, there was a high demand for fireworks, and various large-scale and large-sized fireworks enterprises were established. As a result, there was a shortage of personnel and a phenomenon of low cultural knowledge among enterprise owners and practitioners, with a relatively weak sense of standardization and quality awareness. After the mechanism was straightened out, some standards did not meet the current development status of the fireworks industry, and the National Fireworks Standards Committee increased its efforts in formulating industry standards. Between 2003 and 2008, 43 national standards were proposed for approval, with 22 being approved and released by the government. In 2009, the standards for the fireworks industry were further refined to include pellet types, friction types, smoke types, rotating fireworks types, and basic terminology for fireworks and firecrackers. At the same time, the standard for fireworks and firecrackers was determined to be six subsystems: comprehensive basic standards, design standards, manufacturing standards, usage standards, product standards, and firing standards. The president of a fireworks manufacturer stated that the “small, decentralized, small-scale, frequent, and diligent transportation” experience in China is a perfect example, and its significance is that the fireworks industry in the Liuyang region launched industrial innovations such as factory and mechanization in fireworks manufacturing, pushing it to a new height. Subsequently, Liuyang attracted the attention of the country and even the world, becoming a demonstration zone for the international fireworks industry.

As companies within the industry collectively awaken to the business competition of “first-class enterprises setting standards, second-class enterprises producing products, and third-class enterprises making sales” in pursuit of maximizing profits, starting in 2006, Liuyang Fireworks began to develop their own local standards. In 2007, the development of 14 major categories of standards was completed and then rose to become a local standard in Hunan Province.

A fireworks expert in the southern region stated that the raw material system is slightly lagging behind the fireworks product quality system. For example, potassium nitrate and military nitrate are used in large quantities in the fireworks industry, but previously there were only industry standards and no industry standards for materials used in fireworks and firecrackers. For example, single-base powder belongs to retired materials from the military industry. It is also used in large quantities for making gunpowder locally, but there is no national standard, and accidents also occur during use, processing, and transportation. It exists in the fireworks industry nationwide. On the one hand, this is due to some enterprises being influenced by economic interests, and on the other hand, as the fireworks industry develops, the subdivision has become an inevitable trend in product quality, safety management, factory construction, brand packaging, auxiliary materials, mechanization, and other aspects. It is easy to see that fireworks products must continue to be standardized, whether from production and processing engineering technology or marketing channels.

According to statistics from the Economic Information (database management) Office of the Hunan Provincial Government, the market share of the world’s fireworks industry is 76% to 84% held by mainland China. This huge data integration shows our country’s ability and the challenges we face. Chinese fireworks companies that expand their export fireworks factories and improve the production equipment and engineering technology content of fireworks enterprises will further improve production efficiency. Taking Xingtong Fireworks Co., Ltd. in Yangquan City as an example, based on the company’s intuitive understanding of exporting fireworks to Ottawa, Canada, for many years, the company’s current annual production capacity cannot meet 15% to 18% of Ottawa’s annual demand. Not to mention considering orders for fireworks from American customers like Shengli Company. If production can be automated and production efficiency can be improved, their products can be sold directly to the world’s largest economy, the United States. In this way, the company can participate in economic globalization, enhance its market analysis and forecasting capabilities, and improve its ability to operate in international markets. Therefore, fireworks automation production lines are equivalent to enhancing the competitiveness of fireworks factories, significantly improving their market advantages, and expanding their market share year by year, with broad marketing prospects and significant economic benefits.

In summary, mechanization in fireworks production is an inevitable trend and essential operations for social development. As researchers, we need to seize the opportunity and push China’s fireworks industry into an early and steady stage of healthy development.

1.2 The Current Situation of Fireworks Production Line

Nowadays, various processes in producing and manufacturing fireworks products widely use fireworks machinery and equipment. However, during the process of popularizing fireworks machinery and equipment, many unexpected difficulties have arisen.

1.   The technological content of fireworks machinery needs to be improved. Nowadays, a large part of fireworks machinery equipment commonly has problems such as large size, heavy weight, high noise during production, difficult assembly, rough production, and imprecise power transmission, which often result in equipment failure during the production of fireworks products. For example, take the tying machine as an example. It often encounters many malfunctions during the discharge process due to uneven transport of some firecrackers, such as equipment jamming, less or more tying knots, decreased burst rate of firecrackers, or even machine jamming without discharging due to improper transmission or temperature rise caused by friction, which can cause combustion accidents.

2.   The fireworks machinery market is not standardized. For the market, the production machinery and equipment for fireworks products are a sunrise industry, a blank slate regarding production, manufacturing, management, and other aspects. No one has ever touched it before. For such a high demand for this equipment, mainly due to the blank space in this field, the purchase and application of fireworks product production machinery and equipment by fireworks manufacturers are not comparable, resulting in some inappropriate transmission mechanisms produced by such machinery manufacturers, which have low output efficiency and low-quality products flowing into the marketing channels of fireworks products. There is no guarantee for after-sales service; even worse, it inconveniences the fireworks manufacturers and always gives them the illusion that many manufacturers feel impractical and even unsuitable. In addition, there is a situation where there are as many as 7,000 fireworks product production and manufacturing companies nationwide, but only a hundred or so suppliers of various fireworks product machinery and equipment, and the supply-demand relationship is extremely unbalanced, resulting in the market price of equipment being several times higher than the cost price and value of the machinery and equipment. Taking a tying and packaging machine as an example, the cost of the equipment is probably only around 4,000 yuan, but the price on the market is over 10,000 yuan, which makes it impossible for some consumers to purchase. In summary, the current situation is that equipment prices are high. Still, the quality could be better, and this abnormal market seriously hinders the correct use and widespread popularization of mechanized fireworks production.

3.   Imbalanced production of raw materials. In the production process of fireworks and firecrackers, there are many processes that still have no mechanical substitutes, such as the production of various types of medicines and the loading of gunpowder in fireworks and firecrackers, as well as the A2-level production processes of loading gunpowder and assembling balls for gift firework products. Workers involved in these processes have to handle exposed gunpowder directly, and there are often violations of regulations and a high accident rate in these processes. Some processes are tedious and do have mechanical substitutes for manual labor. Still, the degree of mechanization is low, and because of the tediousness of the process, malfunctions frequently occur, seriously hindering production efficiency. In short, equipment manufacturers should have a comprehensive understanding of the processes involved in fireworks to develop machinery that is truly suitable for the fireworks production industry so that it can be applied to the areas where machinery is needed.

4.   The overall degree of mechanization is not high. The production of fireworks is a continuous process, and each process is complementary. The current fireworks machinery and equipment have been developed for certain special types of work processes, which saves labor and interrupts the process’s continuity. The paper-cutting machine only has the function of cutting paper, and the winding machine [30] only has the function of winding. This lack of continuity in the production process can only partially utilize the high efficiency of machinery to generate production. Now, machinery and equipment have been developed to integrate the two processes of knotting and packaging firecrackers, which gives us hope for improving the overall degree of mechanization, and takes a step towards achieving mechanized production of fireworks in the future.

5.   The market development needs to be more reasonable. Except for Tibet, fireworks and firecracker production enterprises exist in all provinces and cities throughout the country, especially in the Pingxiang-Liuyang-Huining industrial cluster, where they have their own complete systems for production, research and development, and sales. China’s fireworks machinery and equipment manufacturing companies are in the Pingxiang-Liuyang-Huining main industrial area. These areas have a high application rate for machinery in the fireworks industry, which has become an inevitable trend.

In contrast, other provinces and cities do not have such convenient conditions, and most production and manufacturing companies in the fireworks industry still use old engineering technology. In areas such as Guizhou, Anhui, Sichuan, Shaanxi, Inner Mongolia, and Henan, many machines are only winding machines, and knotting and packaging machines are extremely rare. In industrial clusters for fireworks production, such as Xiang and Gan, there are also significant differences in the popularity of machinery and equipment. In regions such as Guangfeng in Gan and Yongzhou in Xiang, mechanization of fireworks production and manufacturing is still only a concept for some companies.

According to the current situation and existing problems in China’s fireworks production and manufacturing machinery and equipment, the following arrangements should be made:

1.   Strengthen management. Regulatory departments should comprehensively strengthen the quality, brand, sales market, sales price, use, after-sales service, and commitment of fireworks machinery. Manufacturers should be aware that mechanization does not mean completely safe production. They should remain vigilant, strictly control the production process, and produce sound fireworks machinery and equipment to achieve true safe production and improve product quality.

2.   Focus on key areas. High-risk manufacturing processes are important links in accidents. To prevent accidents, it is necessary to focus on these key areas and conduct corresponding research and development of mechanical equipment. In addition, if labor-intensive processes are targeted, it can reduce the manufacturer’s labor burden and prevent more people from being injured or killed in accidents, and these processes should also be strengthened in research and development.

3.   Strengthen research and development. Technological backwardness is the root cause of enterprise development lag or elimination in today’s era. Therefore, China’s fireworks industry is facing unprecedented challenges. The labor-intensive production mode is too weak in the face of mechanization. Only by continuously improving equipment performance can the national industry prosper. The government will strongly assist groups or organizations (national institute) that make outstanding contributions in taxes and profits, and various rewards will be given to outstanding individuals in research and development. In terms of management, those who perform well and operate in a regular manner should be commended, and those who perform poorly and operate irregularly should be criticized to guide production in the right direction. Encourage and guide researchers to fully understand the various processes of fireworks production (search) and discuss with the workers to develop effective fireworks production machinery and equipment in international conference.

4.   Breakthrough tradition. The fireworks industry is a traditional national industry in China. While preserving tradition, search breakthroughs and breaking through the previous production concepts is necessary. Comprehensive reforms should be carried out while promoting the mechanization of production, and new manufacturing processes advanced materials should also be sought. High-quality machinery and emerging manufacturing processes are the hope of this industry.

5.   Standardize the market. The entire country has made corresponding regulatory decisions for the popularization and application of mechanized production of fireworks products. A licensing system has been implemented for the marketing of fireworks production machinery, especially for the production machinery equipment for particularly dangerous production processes, which is strictly regulated. If the quality and safety of fireworks production machinery equipment and quality indicators do not meet relevant regulations and bypass relevant departments, they will absolutely be prevented from entering marketing channels.

6.   Improve standards. In order to standardize the production and application of fireworks machinery equipment, China has enacted relevant provisions in national standards such as the “Safety Specifications for the Design of Fireworks and Firecracker Factories” and the “Technical Regulations for Occupational Safety of Fireworks and Firecrackers.” These provisions timely supplement and modify issues such as quality and safety indicators during the production of fireworks machinery equipment, safety factors during the application, application environment, manufacturing process risk level, operating procedures, and personnel high throughput.

1.3 Fireworks Automatic Production Line

In the 1980s, machinery for the production of fireworks products emerged, and the fusing machine and winding machine were the two types of fireworks production equipment that were successfully developed and promoted. In the 1990s, various specialized machinery for each production process was successfully designed and promoted, including the insertion machine, fully automatic binding machine, paper separating machine, slurry drawing machine, fully automatic winding machine, tube cutting machine, and bottom-cutting machine. For the fireworks industry, these were milestones.

Black powder’s production and manufacturing process is usually divided into single-component and multi-component processing. Regardless of the component processing method, the processes include crushing, rolling, slicing, and polishing. In the production and manufacturing of sparklers, there will be single-component ingredient crushing and granulation processes. In the production and manufacturing of fuses, there will be fuse-making, slurry-making, and painting. In producing and manufacturing fireworks, there will be processes such as paper cutting and shell pressing. In the production and manufacturing of firecrackers, there will be processes such as paper separation, tube tearing, tube cutting, bottom pressing, fuse insertion, whip knotting, and packaging. In these processes, fireworks machinery equipment has been widely used.

The production and manufacturing of fireworks products have always been a typical labor-intensive industry. There are 12 processes and 72 procedures in this industry. If production is solely done by manual labor, there will be problems such as high labor intensity, poor production environment, low work efficiency, and poor quality. Moreover, most of the procedures in the production and manufacturing process of fireworks products are inseparable from gunpowder, which results in a low safety factor and increases the factors of explosion and combustion. Therefore, the contradiction of human resources demand has been resolved after the introduction of mechanical equipment in the production and manufacturing of fireworks products. Work efficiency and production capacity have been greatly improved, and the quality and efficiency of products have also been improved. The area and construction area (construction industry) of the fireworks manufacturers’ premises have been greatly reduced, and the production cycle of fireworks products has also significantly been shortened.

Fireworks machinery equipment, with its irreplaceability, has changed China’s traditional production and manufacturing mode of fireworks for thousands of years and has been welcomed by manufacturers of fireworks products. Especially when using fireworks machinery equipment to shorten and reduce the time and radio frequency of contact between workers and gunpowder and reduce the chance of human error, manufacturers will appreciate the resulting reduction in accident and casualty rates, ultimately achieving the goal of ensuring the safety of workers’ lives and ensuring safe production for manufacturers.

1.4 Technological Development of Automated Production Lines

Today, many manufacturers of fireworks still use traditional techniques for production. However, from the overall trend of industry development, the existing production capacity is insufficient due to the high demand for fireworks worldwide. Some domestic manufacturers are seeking various methods to improve production efficiency. Some have thought of using labor-intensive methods, but labor-intensive means using many people to participate in production at the same time. It would lead to a high casualty rate in an accident. Therefore, the frequent accidents have forced them to abandon this idea. After a long period of exploration, experienced personnel in production have concluded that automated production is more feasible than other methods. Automated production avoids contact between humans and production and greatly improves labor productivity. For example, a manufacturer called Jinlilai in the Liling area exports fireworks. The company independently developed and put into practice many replacement machines for traditional techniques. Compared with the old production methods, the mechanization of production and processing reduced the occupation of land, the employment of staff, and the investment in fixed assets. At the same time, labor productivity was greatly improved, and the production capacity increased nearly fivefold, according to reliable data collection (data driven). It is conceivable that the influence of this manufacturer in the market has been rapidly improved. The production of the company’s fireworks products has gradually moved towards mechanization. For example, Jiangxi Angel Fireworks Technology Development Co., Ltd. is now developing an automated production line for fireworks and has achieved initial results by producing a prototype with a simple structure and function. A single production line is estimated to have an annual output (high throughput) value of 100 million yuan. The project is a joint effort of two fireworks manufacturers in Shanghai and Pingxiang. The main work is to develop new fireworks products and new automated production machinery for fireworks. This cooperative project has played a positive role in promoting the development of the fireworks industry towards safety, specialization, scale, and standardization. Nowadays, in the field of fireworks machinery research (search) and development, black powder automatic stirring machines and fuse machines have already appeared on the market.

With the development of technology, fireworks machinery is constantly being designed and innovated. It is believed that more advanced fireworks production systems will appear to effectively ensure the safety and reliability of fireworks production in the near future. Manufacturers will strictly use fireworks production machinery with high safety and reliability assurance to produce fireworks and firecrackers, and production efficiency will also increase dramatically. There will also be significant cost savings in manpower, and the incidence of various accidents will be greatly reduced. In the end, the safety performance of fireworks production lines is all about how to ensure that gunpowder is not ignited. Once this technical difficulty is overcome, production with zero risk will no longer be a problem.

Currently, there are a few fireworks manufacturers in the industry that have adopted a mechanized production method. The equipment they use mainly includes paper processing machines such as paper cutters, automatic winding machines, paper separators, and tube cutters; electromechanical detonators, pulverizers or grinders, powder collectors, ball mills, and milling machines for making gunpowder; cutting machines, eye-drilling machines, automatic lead-inserting machines, envelope-sealing machines, and automatic whip-knitting machines for producing firecrackers; oil presses and ball-shaped granulators for making sparklers; fuse-making machines for making fuses; drying equipment for fireworks, sparklers, and other items; special equipment such as boilers; and various instruments and meters used for testing.

Now, fully automated mixing machines have emerged (as shown in Figure 1.1). The remote control is used to achieve human-machine isolation in the mixing process, so even in the event of danger, people will have sufficient time to take evasive action. In addition, only six kilograms of material are mixed at a time, which reduces the risk of serious explosions. The use of pneumatic power avoids the generation of sparks and largely avoids explosions. The drawback of this equipment is that the quality of the materials cannot be accurately guaranteed, and it is a single device that requires human assistance when connecting with other equipment. Moreover, the pouring process is inconvenient, the movements are too large, and sparks can easily be generated.

Figure 1.1: Automatic Mixer

The fully automatic straight-tube rolling machine (as shown in Figure 1.2) is a widely used single unit in the fireworks machinery used in the rolling tube process for manufacturing fireworks and firecracker paper tubes. The machine uses a straight pipe to roll paper into a tube and is controlled by an intelligent electrical control system (machine learning ) . It automatically performs a series of production processes such as cutting paper, applying glue, rolling paper tubes, separating paper tubes, and feeding materials. It can be widely used in the production of paper tube rolling for many fireworks products such as fireworks shells, combination pot flowers, spray flowers, cold light fireworks, etc. The maximum length of the paper tube in this machine roll is customized according to the customer’s wishes. The thickness of the produced paper tube wall, inner and outer diameter, and the length of the cut paper tube can be adjusted at will. The operation procedure is very simple and convenient to use. It can be operated quickly even without professional personnel present, making it very suitable for the fireworks industry operators’ needs.

Figure 1.2: A fully automatic straight tube rolling machine

The loading machine utilized (as shown in Figure 1.3) is also an advanced production equipment that has emerged in the fireworks production industry in recent years. On July 15, 2011, the Hunan Provincial Administration of Work Safety organized relevant experts to conduct a safety assessment of the loading machine. Through on-site (display site) inspections by participants, observation of operation demonstrations, and review of the technical materials submitted by the company, as well as analysis of the development and trial use, the following evaluation opinions were obtained:

1.   The technical materials submitted by the development unit are complete, and the safety technical parameters are complete, which can guide the firecracker loading machine’s installation, use, and maintenance.

2.   The equipment performance is stable and meets various requirements within the construction industry.

3.   The equipment uses a remote control to separate people and drugs, improving the safety of mixing and loading processes.

Figure 1.3: Loading Machine

The expert group unanimously agrees that the fireworks loading machinery equipment produced by Youwen Machinery Factory in Liling City greatly improves the safety of the fireworks production process compared to manual mixing and loading. It is conducive to the safe production of fireworks products and has a promotional value.

In addition, some equipment has been digitized, but the purpose of these devices is only one: to combine the production efficiency and safety of fireworks. Although these devices are currently available, they have yet to be organically combined, and they are only some scattered devices. The connection between devices still requires human participation. However, this brings convenience to our research on production lines. The research focuses on changing some devices’ unreasonable designs, such as power sources and mixing methods, etc.

There is also the design of automation for the connection between devices to replace the human participation link. Finally, the selection of the motion method, some motion methods will produce pressure, impact, or friction, which can cause accidents. Therefore, motion methods that can avoid these should be chosen.

The advancement of technology, changes in production and processing operation models, and improvements in some processes perfectly reflect the progress of science and technology benefiting people. Setting off fireworks is beautiful, but behind it is the sweat of all fireworks producers. However, the continuous improvement of the mechanization level in the fireworks industry can greatly shorten the research and development cycle of new fireworks products, allowing better fireworks creativity to be displayed to the world.

1.5 Main Content of the Thesis

Regarding the firework production line we aim to study, the first step is to understand that it is a fully automated production system. Therefore, its design comprises two main parts: control and mechanical systems. Additionally, the design must take into account the firework’s design environment. The design principles of the system are based on traditional production processes and safety and reliability standards. Based on these requirements, this paper considers the sensitivity of fireworks to pressure, friction and sparks. It researches and discusses the mechanical and electrical control system (machine learning) design of the firework production line.

In terms of mechanical design, the paper introduces innovations to the parts that have had problems in the past and simulate the mechanism’s movement of the system. Based on the simulation results, the paper conducts further optimization analysis and proposes improvement plans. The main focus of the electrical control system (machine learning) is on the design of the control system (machine learning) . The paper studies (case studies) and analyzes the selection of sensors and the programming of the control program to connect the various parts of the production process in an orderly manner, as well as to restore traditional production processes as much as possible while fully improving production efficiency without affecting normal production.

Chapter 2: Overall Structural Design

2.1 Principles of Overall Scheme Design

In design, many things must be avoided, and these conditions must not be violated. Otherwise, the product design will fail. This design aims to prevent accidents and must follow the necessary design principles.

2.1.1 Explosion Prevention

Explosion prevention measures must be taken in the design, and all mechanical components used must be explosion-proof. The main explosion prevention measures [34] include:

1.   Selecting appropriate explosion-proof instruments and electrical equipment;

2.   Using appropriate ventilation methods;

3.   Preventing or minimizing the possibility of flammable. explosive materials leakage;

4.   Not using or minimizing the use of electrical components that easily produce sparks;

5.   Adopting methods such as nitrogen filling to maintain an inert atmosphere.

2.1.2 Electrostatic Prevention

All possible electrostatic-generating mechanisms or components should be avoided or cannot be used. If used, the generation of electrostatics should be minimized to the greatest extent possible by adjusting the electrostatic charge of two contacting objects to be equal or close, reducing the contact area and pressure between the two objects, lowering the environment temperature, avoiding frequent contact, and slowly separating them. Powder and fluid can generate electrostatics during transfer or transportation due to friction. Therefore, measures such as reducing the flow rate and bending the delivery pipeline should be taken for this situation. In addition, measures should be taken in the following aspects [35]:

1.   Grounding;

2.   Overlapping (or cross-connecting);

3.   Shielding;

4.   For insulators that are almost impossible to adjust the amount of electrostatic charge, antistatic agents should be used to increase conductivity, making the electrostatic on the surface easy to dissipate;

5.   Using spraying, watering, and other methods to increase environmental humidity and suppress electrostatic generation;

6.   Using electrostatic eliminators for electrostatic neutralization.

2.1.3 Sparks Prevention

The above two (referring to the previous paragraphs) can also generate sparks, and in addition, there are sparks generated by impacts during the processing and production of certain metal mechanisms. To avoid these sparks, other materials can be used for the mechanisms, such as engineering plastics, as well as mechanisms or components that generate electric and magnetic fields, such as motors, springs, relays, etc.

In summary, although these are all common sense, there are still omissions in the production process. It is precisely because of these inadvertent omissions that irreparable losses are caused, and even the cost of lives.

2.1.4 Requirements for Automated Production Lines

In addition to avoiding these fatal aspects, there are general principles for designing automated production lines. The automated production lines for fireworks should meet many requirements, mainly involving the following indicators [36]:

1.   Improved quality;

2.   Increased production;

3.   Shorter time to replace molds to adapt to production changes;

4.   Monitoring of the production process;

5.   Operator safety.

To meet the above requirements and adapt to the development of social technology, automated production systems generally add the following functions [37]:

1.   Collecting and managing product and machine parameters. The addition of this task can improve work efficiency and also provide convenience for equipment maintenance;

2.   Selecting suitable production data driven and saving it to provide data for coherent production processes and automatically processing data mining, and adjusting data driven.

Automated production systems can exist independently as a system in the current society because it is a comprehensive technology based on mechanical technology, computer technology (artificial intelligence), sensing technology, drive technology, interface technology, etc. It is based on the needs of production processes and reorganizes these existing comprehensive technologies rationally and effectively, forming the optimal production and manufacturing system. However, although automated production systems are derived from assembly lines [38], the production concept of the assembly line could have developed better due to the influence of production technology at that time. Therefore, the current automated production system is equal to the assembly line regarding technology or function. The main feature of the automated production line is the advanced automation electrical control system (machine learning for materials development) , which has a relatively high degree of automation in production and a more compact rhythm due to the participation of PLC.

From the perspective of overall functionality, we divide the automated production system into five parts: the main body, signal reception and detection, signal processing, functional components execution, and interface section. Functionally, any automated production system includes four major functions: operation, automatic control, signal detection, and electromechanical drive. Motors, air pumps, and other devices can power the production line, allowing it to operate. With the help of microcomputers Hi,

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Thank You. , single-chip microcontrollers, PLCs, or other electronic components, control functions can be easily implemented in automated production lines. In the working process, the signal detection function relies on sensors installed in specific locations to receive and detect signals. Then, electronic devices memorize, transmit, calculate, process, and amplify the signals through corresponding interface circuits, which are then transmitted to the executing mechanism to complete the designed tasks. Different sensors can collect different information from the production line, such as position, temperature, pressure, and speed, and then process these signals to achieve control functions. Starters, such as motors, cylinders, solenoid valves, mechanical arms, or robots, mainly complete the driving function. There are also some issues to be addressed in other aspects of the design, such as the accuracy of weighing, the problem of quality loss during transportation, the issue of multiple air cylinders pushing a surface that cannot maintain its level, and the fact that the cylinder will become shorter over time during the process of dumping fireworks. However, these issues are all very specialized and detailed and will be addressed in other members’ papers.

2.2 Composition of Fireworks Automated Production Line

The fireworks automated production line consists mainly of weighing, mixing, granulation, drying, and stacking. By coordinating these processes, the core product of fireworks, the fireworks shell, is produced. In this production process, fireworks shells and powder are flammable and explosive materials, so extra attention must be paid to these conditions during production.

2.2.1 Ingredients Mixing Process

Figure 2.1: Batching structure diagram

The weighing process is the first and most important step in the entire system, and its function is to weigh various ingredients according to a certain weight and ensure accuracy. In this process, the design should also follow the design principles mentioned earlier and take explosion-proof measures.

The basic process of this system is as follows (as shown in Figure 2.1):

1.   After the material is added to the hopper, start the system.

2.   After the system automatically detects no faults, the stepper motor starts to operate. With the operation of the stepper motor, the material passes through the feeder from the hopper and is delivered to the pallet.

3.   When the weight of the material reaches a certain value, the stepper motor stops working.

4.   At the same time, the cylinder that pushes the electronic scale pallet starts to work, lifting the pallet. When the pallet is at a certain angle with the horizontal plane, the cylinder stops moving, and the material begins to slide from the pallet into the guide pipe, entering the mixing process. In addition, the cylinder retracts to its original position after the material has completely fallen.

5.   When the material completely falls into the mixer through the pipeline, the mixer starts to operate. When the mixer runs to the point of complete mixing (this needs to be timed and experimented with to obtain an accurate time), the mixer cylinder starts to operate, driving the unloading valve to open and sending the evenly mixed material to the next process.

Characteristics of the weighing and mixing process:

1.   Conveyance of various ingredients. A screw drive is used to transport various ingredients.

2.   Weighing of ingredients. Electronic scales are used as weighing sensors, in combination with stepping motors and screw feeders, for high-precision automatic weighing.

3.   Mechanical stirring type mixer. In an automated production line, there needs to be more external freedom conducive to ingredient filling. The mechanical stirring type mixer only has internal motion, providing a premise for automation.

It is worth noting that various ingredients are mixed together in the mixing process. From the beginning, each ingredient is separate, then some parts have formed into explosive materials, and some have yet to form explosive materials until it becomes completely explosive materials. In the mixing process, the final result is the production of explosive materials, and there are already explosive materials present during the mixing process. Once explosive materials are present, measures must be taken to prevent explosions and strict adherence to the design principles to avoid major accidents. Based on the above analysis, some measures taken in the design are:

4. All parts that come into contact with explosives must use engineering plastics.

5. Explosion-proof electrical products should be selected when it is impossible to avoid using them.

6. If it is impossible to avoid using non-explosion-proof electrical products, insulation materials should be used to wrap them.

2.2.2 Granulation process

This process comes after the weighing and mixing process. It adds adhesive to the mixed gunpowder and rolls the powders into particles. This process is the shaping stage of the granules, and the powders used have already become finished gunpowder. Therefore, in the design of this process, strict adherence to the design principles mentioned earlier is necessary to prevent accidents that could cause harm to personnel.

The specific process of granulation work (as shown in Figure 2.2) is as follows: after the powder is weighed and mixed according to the ratio, it is conveyed to the feeding port by the conveyor belt. Then it enters the granulation disc through the feeding device. The main machine starts to work at the set speed, the corresponding spray system also starts at the same time, and the granulation process of the disc granulator begins. A camera remotely monitors the granulation process. After the granulation, the discharge cylinder and the lifting platform cylinder work together to pour the finished pellets into the remaining material recovery device. The device separates the pellets and the remaining powder, and the remaining material slides into the recycling bin while the pellets roll into the tray, ready for the next step.

Figure 2.2: Palletization Structure Diagram

Palletization Working Principle:

1.   Formation of Nucleus. The powdered material rotates centrifugally in the disk pelletizer and is wetted by the atomized slurry sprayed by the spray gun. Initially, a small amount of slurry is sprayed, and the interstitial spaces between the powder particles are not completely filled, and the air is in the continuous phase. The slurry’s surface tension connects the powder particles to form small particles. As the amount of slurry increases and completely fills the interstitial spaces between the particles, the capillary negative pressure and liquid bridging effect produced by the capillary effect cause the already formed small particles to aggregate further and produce a strong binding force, thereby forming a spherical nucleus.

2.   Increase in Particle Size. It is the process of adding drugs to the nucleus in a layered manner, causing the particle size to increase to the target range. After the nucleus is formed, the atomized slurry is sprayed, and powder is added to the layering process. The powder adheres to the nucleus, and the particle diameter does not increase. At the same time, the particles rotate with the disk at a certain speed, and the mutual friction between the particles gradually eliminates their surface roughness and forms a spherical shape. This is the main process of microsphere growth and the most critical step in pelletization.

3.   Polishing and Drying. After the powder supply and liquid spraying are completed, the disk continues to rotate. Under the action of centrifugal force and friction, the particle surface is further polished and dried, forming a microsphere with a smooth surface, high sphericity, and certain mechanical strength. The working principle of discharging: When pelletization is completed, the time relay sends a signal to the main engine, discharging cylinder, and support cylinder. The main engine stops, and the discharging and support cylinders start working at a set speed. They cooperate to pour the pellets into the recycling device. When they reach the specified position, the sensor is triggered, and the sensor sends a stop command to stop the discharging.

2.2.3 Palletizing Process

Palletizing is the process of placing items together, using the concept of integrated unitization, and stacking materials into a pile in a certain way. This is beneficial for achieving various logistics operations for the entire material.

Palletizing is a technology in logistics automation that has developed rapidly in present years. Firstly, with the increase in production scale and the improvement of production capacity, the efficiency of palletizing is constantly required to be improved, leading to the development of high-speed palletizing. Secondly, in the process of enterprise products flowing from the seller’s market to the buyer’s market, the production of enterprises is moving towards the development of multiple varieties and small batches. Enterprises will use flexible production to realize the production of multiple products on one line. Similarly, this requires palletizing to have the ability to handle multiple products. In addition, with the emergence of large-scale wholesale distribution centers, it is necessary to deliver according to the order for different users, which requires palletizing robots to have a wider range of palletizing and stronger mixed palletizing capabilities. In these environments, palletizing robots have been given good development opportunities. Nowadays, there are many varieties of palletizing machines on the market, and their degree of automation and flexibility is also very high.

Figure 2.3: Stacking Structure Diagram

A production batch of gunpowder weighs 5 kilograms. Due to the design requirements of the drying equipment, the 5 kilograms of gunpowder after granulation are placed in 4 trays, so a tray group consists of 4 trays, and a shelf holds 4 tray groups. The shelf enters the drying oven for drying, completing the entire additive manufacturing process. The working principle of the stacking component (as shown in Figure 2.3) is designed as follows:

The entire stacking component consists of 5 parts: conveyor 1, tray feeder, conveyor 2, stacker, conveyor 3, and conveyor 4. Each part performs the following tasks: Conveyor 1 places the tray group on it and supplies it to the tray feeder; the tray feeder receives the trays from conveyor 1 and then supplies them one by one to conveyor 2; conveyor 2 transports the trays provided by the tray feeder while the granules are being loaded onto the conveyor; conveyor 3 transports the shelves to the stacker; the stacker receives the shelves and stacks the trays from conveyor 2 layer by layer; conveyor 4 transports the stacked shelves to the drying oven for drying.

The design of the conveyor can be based on the requirements in the design manual, so the main work of principle design lies in the tray feeder and the stacker.

2.2.4 Drying Process

The drying and unloading system consists of two parts: the drying and unloading sections. The drying section is responsible for conveying the racks and drying the materials on the pallets placed on the racks. The unloading section also transports the racks and unloads the materials on the top into a collection box to complete the unloading process. The system structure (as shown in Figure 2.4) consists of the drying and unloading sections.

The specific working process is as follows: after the drug particles are made and placed into the tray, they are stacked in the rack through the stacking section, and then the rack is transported to the drying section. The control system (machine learning) controls the motor to make the conveyor belt operate and drive the rack to move. The drying machine system consists of three drying boxes. Drying box A is set at a temperature of 45℃, drying box B at 60℃, and drying box C at 45℃. The rack will be dried in each of the three drying boxes for 10 minutes, and the drying process of the drug particles will be completed.

Then, the rack enters the unloading section, and the cylinder of the unloading device tilts the rack to complete the unloading process. After unloading, the rack is transported to the stacking section for reloading.

Figure 2.4: Schematic diagram of the drying and unloading process

1.   Working principle of drying system: The drying process uses a combination of far-infrared and hot air to dry the fireworks particles. Far-infrared drying is the main method, and hot air drying is the auxiliary method. When the far-infrared electric heating plate in the drying chamber is energized, it starts to heat up, and the surface temperature of the far-infrared electric heating film increases. When it reaches a certain temperature, it emits far-infrared rays. The particles in the tray absorb the far-infrared rays, and the internal molecular motion of the particles intensifies. The temperature inside and outside the particles rises uniformly, starting the drying process. At the same time, the axial flow fan supplies air to the drying chamber, producing hot air to dry the particles. The inlet and outlet pipes form a circulating ventilation system through the action of the axial flow fan, which makes the particles heat up more uniformly and effectively collects the dust inside the drying chamber to prevent safety accidents and achieve the effect of recycling. The drying process uses a PID temperature control system (machine learning) to freely set the temperature and automatically adjust the function. By adjusting the power of the far-infrared electric heating plate, the temperature requirement between room temperature and 150℃ can be met. An emergency stop switch is installed on the drying chamber to ensure safety during operation.

2.   Issues to be considered in the design: (1) The first thing to consider in the drying process is safety, which is the primary guarantee in the design of the entire fireworks production line. Therefore, explosion-proof motors should be selected for the design, and all wires should not be exposed. They should be sealed to prevent contact with the powder and small particles. In addition, the external surface temperature of all parts in the system must not exceed 80℃. Finally, the system should be equipped with an alarm device. (2) The second issue is to ensure sealing. The heat loss should be minimized when drying the particles in the drying chamber. In addition to insulation materials, attention should be paid to sealing the front and rear “doors” when the shelf enters the drying chamber. Make sure that each part is in place and use the detection of sensors and a control system (machine learning & deep learning) to control each part to reach the specified position. (4) For the unloading part, it should ensure complete unloading. One way is to determine the maximum time of the unloading process through experiments and set the maximum time by the control system (machine learning & deep learning) . The second way is to capture images of the pallet with a camera and compare them to the pallet without pellets to ensure complete unloading.

2.3 Overall structure

Figure 2.5: Overall Schematic Diagram

This production line (as shown in Figure 2.5) is functionally divided into four parts: weighing and mixing, granulation, drying, and stacking, which complement each other to form an automated fireworks production line.

The workflow of this automated production line is shown in Figure 2.6. However, each step is controlled by the end of the next step. For instance, in the weighing and mixing process, not only does the stepping motor stop moving when the weight is exceeded, but also the unloading cylinder of the electronic scale tray cannot move until the mixing process is complete. Only when the mixing process is completely finished can cylinder A move to feed the ingredients into the mixer. Similarly, the next granulation process also controls the mixing process’s unloading. In other words, only when the granulation process is completed can cylinder B of the mixing process move to feed the well-mixed ingredients into the granulation process. In terms of composition, the production line can be divided into mechanical mechanisms, pneumatic systems, and control systems. The mechanical mechanisms include material storage, feeding, weighing, mixing, conveying, lifting, granulating, drying, etc. The pneumatic systems include cylinders, directional valves, air pumps, pressure limit valves, etc. The control system includes each part’s operating panel, self-checking system, and operating system.

2.4 Summary of this chapter

The fireworks automation production line can become a system because it is a comprehensive technology based on mechanical technology, computer technology Hi,

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Thank You. , sensing technology, drive technology, interface technology, and so on. From a system engineering perspective, it applies these comprehensive technologies, effectively organizes and integrates them according to production needs, and realizes the optimization of the overall equipment.

The innovation of the fireworks automation production line is that it integrates the processes of various fireworks production processes into one production line, changes the independence of each process in the previous production, and realizes automated production, which not only improves production efficiency but also improves product quality. As we all know, each link before had its own independent production process, and from one link to another, more manual operations were needed. Compared with humans, machines do not have emotional problems. If the program input is correct, there will be no operational errors. Therefore, through the description of the production process of each link above, while achieving their respective functions, each link has reduced personnel participation, reducing personnel casualties. It is also one of the purposes of the fireworks automation production line.

Chapter 3: Design and Theory of Ingredients Section

3.1 Composition of the Mechanical Structures of the Ingredients System

The overall schematic diagram of the ingredients section (as shown in Figure 3.1) can be broadly divided into two parts: weighing and mixing. These two parts are connected by a feeding mechanism, which reduces weight loss after weighing and strengthens the overall structure, making it more compact.

The weighing and mixing parts are supported and connected by a frame, and these two parts’ motors, cylinders, feeders, and mixers are all installed on this frame. The design of the frame structure is quite complex and has certain requirements in terms of load-bearing capacity.

Figure 3.1: Weighing and Mixing Overall Scheme Diagram

To make it clearer, the frame can be hidden, and then the system diagram is easy to understand. The overall diagram of the weighing and mixing process mainly works as follows:

1.   After the material is added to the hopper, the system is started.

2.   After the system automatically detects no faults, the stepper motor starts to operate. During the operation of the stepper motor, the material is transported from the hopper through the feeder to the pallet.

3.   When the weight of the material reaches a certain value, the stepper motor stops working.

4.   At the same time, the cylinder of the electronic scale starts to work, lifting the pallet. When the pallet is at a certain angle with the horizontal plane, the cylinder stops moving, and the material starts to slide from the pallet into the guide pipe and the mixing section. In addition, the cylinder retracts to its original position after the material is completely discharged.

5.   When the material completely falls into the mixing machine from the pipeline, the mixer starts to operate. When the mixer runs until the mixing is complete (this needs to be timed and experimented with), the mixer cylinder starts to operate, driving the discharge valve to open. The evenly mixed material is sent to the next section.

3.2 Research on Weighing Mechanisms

In this section, the types of ingredients can be added or reduced according to the needs of the company, with a maximum of six types of ingredients, including 1. Two types of high-density, small-volume ingredients; 2. Two types of low-density, large-volume ingredients; 3. Two types of high-density, large-volume ingredients.

The important components of the weighing mechanism include the material storage, conveying, and weighing mechanisms. The material storage mechanism is the hopper, the conveying mechanism mainly consists of a stepper motor and a feed screw, and the weighing mechanism mainly consists of an electronic scale, an electronic scale tray, and a discharge cylinder.

The compactness of the mechanism makes it difficult to express the working principle well in the diagram. Therefore, in this paper, weighing one type of ingredient is selected as a representative (as shown in Figure 3.2) for illustration.

Figure 3.2: Working principle diagram of the weighing process

The working process of the weighing process is as follows: the material is transported to the electronic scale tray 2 by the 1 feeder driven by 5 stepper motors. After the weight is measured, the 6 cylinders lift the electronic scale tray 2, and the weighted material slides from the electronic scale tray 2 to the 4 mixer inlet. This stage is completed. The same mechanism is used for other ingredients in the weighing process.

3.2.1 Design of the Hopper

As a storage mechanism, the hopper needs to have sufficient space to facilitate the manufacturer’s sufficient raw material supply during production and allow workers to have sufficient rest time for loading. On the other hand, the four walls of the hopper should have a certain inclination angle to facilitate the smooth sliding of the powder into the feeder.

In this design, the weight of the hopper’s ingredients is achieved according to the proportion of each part. The weight of the ingredients that each hopper can hold is calculated as follows:

Assuming that the total amount of mixing material is 5 kg and the density of the powder is (-3 3 0.9~1.2 10 kg/cm³), calculated according to (-3 3 1.0 10 kg/cm³), the total volume of the material used is 5 liters.

The working cycle is 10 minutes. Calculated based on 4-hour morning work, the total mass of required ingredients is:

M = 5kg x 4h x 6 = 120kg

It is known that the mass ratios of C, KNO3, and S in the chemical formula of each ingredient are 15%, 75%, and 10%, respectively. The required masses of each ingredient are:

Carbon Mc=15% x 120kg = 18kg

Potassium nitrate Mk=75% x 120kg = 90kg

Sulfur Ms=10% x 120kg = 12kg

It is known that the densities of Carbon, Potassium nitrate, and Sulfur are:

ρ_C = 0.4 g/cm³,

ρ_K = 2.109 g/cm³,

ρ_S = 2.0 g/cm³.

The volumes of each ingredient are:

Carbon V_C = Mc/ρ_C = 18kg/(0.4 g/cm³) = 45L

Potassium nitrate V_K = Mk/ρ_K = 90kg/(2.109 g/cm³) = 42.67L

Sulfur V_S = Ms/ρ_S = 12kg/(2.0 g/cm³) = 6L

Then, based on the volume occupied by each ingredient, the hoppers for each ingredient are designed. In this design, the hoppers are vertically designed on the front and back sides and sloping on both sides. Since the angle of powder sliding is between 35.70 and 64.300, the most reliable angle of 600 was chosen for the incline of both sides of the hopper, ensuring that the material can slide smoothly into the feeder. Because the amount of carbon and potassium nitrate used in the ingredients is similar, they are designed to be the same. Figure 3.3 shows the dimensions of the potassium nitrate hopper.

Figure 3.3: Design of Hopper

The hopper for sulfur is designed to be proportionally smaller. It is worth mentioning that powders will diffuse in the air, so if one of the ingredients is used to separate the other two ingredients, the probability of them mixing in the air will be reduced, and the effective volume of explosions will be minimized. From the volume analysis, it can be deduced that the amount of C and KNO3 is relatively large, and they will mix heavily when put together. On the other hand, sulfur requires less volume, and no matter which ingredient it is mixed with, the amount of mixing will not be significant. Therefore, sulfur separates the hoppers for ingredients C and KNO3 in the weighing system. The volume occupied by each ingredient’s tray and the weight to be weighed as follows:

Cabon,

Potassium nitrate,

Sulfur,

Figure 3.4: Design of tray

be increased to at least twice the required volume during its design (as shown in Figure 3.4). The tray floor is designed to be straight and smooth, mainly to facilitate the smooth sliding of the ingredients.

The design of the feeder (as shown in Figure 3.5) adopts a screw-feeding method. Certain pressure may be generated in this feeding method, which can have serious consequences for explosive materials (advanced materials). However, for ingredients, individual carbon, sulfur, and potassium nitrate will not explode on their own. They only become real explosives when mixed. Therefore, a certain amount of pressure is allowed in this part. No pressure should be generated during the mixing and subsequent processes.

Figure 3.5: Feeder Design

The feeder’s main operation principle is to take ingredients from inlet 1 of the hopper, transport them through the screw conveyor, and allow the transported ingredients to slide down to the next stage at outlet 2. The screw conveyor plays a critical role in this stage and can be considered the key component of the feeder.

Figure 3.6: Design of Worm Gear

The worm gear of the feeder has two functions. The first is to convey the ingredients from the hopper and achieve the feeding function. The second is to control the accuracy of the feeding weight through cooperation with the stepper motor. When a specific number of step angles are rotated, the volume of the conveyed material is constant because the worm gear threads are uniform. Therefore, the weight of the conveyed material is constant, which is the weighing accuracy of the weighing system. When other ingredients are transported, the accuracy can be determined in two ways: by limiting the number of step angles or by adjusting the cross-sectional area of the powder in the thread. It is easy to understand the control of the number of step angles. However, controlling the cross-section of the powder in the thread actually means that the same step angle of the stepper is used to feed different volumes of powder. The larger the cross-sectional area, the more powder is fed.

Furthermore, in the illustration of the feeding worm gear (as shown in Figure 3.6), the relevant information about the threads is also indicated on the right . The pitch of the thread is 34, and the rotation is clockwise. When feeding, pay attention to the direction of rotation, use the step angle correction method to complete automatic weighing, and weigh at every certain amount of step angles during the correction process until the specified weight is exceeded. The amount of each feeding is the weighing accuracy of the weighing process.

Figure 3.7: Cross-section of Material Removal

In this weighing process, high precision is not required. The following is the calculation of the cross-sectional dimensions of the carbon feeder worm gear (as shown in Figure 3.7).

Based on these dimensions, the cross-sectional area is calculated as follows:

S=(abh)/2 — (3.1)

Substituting the values, we obtain:

S1 = 29 + 23 * 23/2 = 598mm²

The centroid of the trapezoid is:

y = (3abh)/(a+b+sqrt(a^2 + (a+b)^2 + b^2)) — (3.2)

Substituting the values, we obtain:

yc = (32923)/(29+23+sqrt(29^2+(29+23)^2+23^2)) = 11.06mm

The formula gives the volume of material fed per revolution:

V1 = (2πS1hyc)/((d/2)-yc) — (3.3)

Substituting the values, we get:

S1 = 206428.5241 mm²

V1 = (2π 206428.5241 11.06 * 43)/((95/2)-11.06) = 0.20643 L

The remaining volume to be fed after nine revolutions are:

V2 = Vc – 9V1 = 0.02613 L – 9(0.20643 L) = 0.01713 L

The stepping angle of the stepper motor used in weighing is 0.9/1.8. Therefore, the feed volume per step during correction is:

Vb = (1.8/360) π d^2 * h = 0.001 L

where ‘d’ is the diameter of the carbon feeder worm gear, which is not given in the provided text.

The number of steps required for correction is as follows:

n = V2 / Vb = 0.01713 L / 0.001 L = 17.13 steps

We take n = 18 for correction. The formula gives the correction stepping mass:

Mb = Vb * ρc — (3.4)

Substituting the values, we get:

Mb = 0.001 L * 0.4 kg/cm³ = 0.4 g/cm³ = 0.4 g

We can take the accuracy as three stepping angles, which gives the mass:

Mj = 3 Mb = 3 0.4 g = 1.2 g

Therefore, we need to perform 6 corrections to achieve the desired weight.

Figure 3.8: Weight Control Curve

In summary, the weighing part adopts a “fast and then slow” control feeding method (as shown in Figure 3.8). After deducting the weight of the weighing device tray (tare weight), when the upper computer issues the batching command (computer science & artificial intelligence), a rapid feeding [40] is performed at the beginning of the feeding process. The feeder quickly rotates nine times to reach the value of rapid feeding (L1) and then makes slight corrections to the feeding. As long as the advance amount (L) of the batching weight exceeding the target value is detected, the feeding valve is fully closed.

In the weighing control, the feeder is set to three states: “fast,” “slow,” and “stop.” The “fast” state is mainly used for coarse-precision feeding. After the feeder rotates quickly, the “slow” action is performed. When it slightly exceeds the set value, the stepper motor stops rotating, and feeding stops.

In the selection of electronic scales, the following functions are required for the electronic scale (as shown in Table 3.1):

1.   Ability to set arbitrary weighing upper limit, mainly to adapt to different weight requirements for batching.

2.   Feedback signal when the weighing upper limit is reached. After reaching the batching weight requirement, this function is necessary for the next control.

3.   The weighing accuracy is less than the weight fed during slow feeding, and the weight fed during slow feeding can be measured.

4.   The tabletop scale is for the convenience of arranging the position of the electronic scale.

The working principle of the weighing device is as follows: the weighing object is placed on the weighing platform. Under gravity, the elastic body of the electromagnetic weighing sensor undergoes deformation, causing the balance circuit to lose balance and generate current. An equal and opposite current must be provided to restore the circuit’s balance. This signal is transmitted to the weighing device. Its internal microprocessor converts the signal from an analog to a digital quantity through amplification, filtering, and A/D conversion [41]. Then it sends this digital quantity through a circuit to the instrument panel for processing and display on the display screen.

1.   To ensure the weighing accuracy of the weighing device, its main technical indicators are as follows:

2.   Function to deduct tare weight and pre-tare weight.

3.   Ability to set upper and lower limits and detect weight pass/fail warnings. A buzzer will sound when the weighing value exceeds the set upper and lower limits.

4.   Automatic warning display when the cumulative value exceeds the display range.

5.   Optional RS232 computer high throughput port, which can transmit data to a computer (data mining & artificial intelligence).

The work panel can be set up, the maximum range can be reduced, and the division value can be increased according to actual requirements and the working environment.

Table 3.1: Provides detailed information on electronic scales

The selection of the unloading cylinder involves using a cylinder to unload the pallet. The following requirements must be met for the cylinder:

1.   First, there is a requirement for the pushing force, which must be greater than the load.

2.   The pushing stroke of the cylinder should be greater than the required distance.

Figure 3.9: CM2 Cylinder Outline

These two points play a decisive role in the selection of the unloading cylinder for the pallet. Therefore, the CM2 series cylinder was selected, and three unloading cylinders for driving the pallet were all selected from the CM2 series cylinder (as shown in Figure 3.9). Its technical parameters are shown in Table 3.2:

Table 3.2: Selected Cylinder Parameters

Table 3.2 (Continued)

When installing the cylinder, its angle concerning the vertical direction was determined (as shown in Figure 3.10).

Figure 3.10: Angle between the cylinder and the vertical direction.

3.3 Study of Mixer

3.3.1 Function of Mixer

Powder mixers [42] are mainly used in industrial production, such as pharmaceuticals, feed, and chemical industries, and their applications are pervasive. In this project, mixers are necessary equipment for the standardization and uniformity of ingredients in the production of gunpowder. In present years, as the refinement of mixing processes in the production of pharmaceuticals and other items has continuously improved, the requirements for mixing have become increasingly higher.

From the perspective of the function of powder mixing processes, mixing can promote the diffusion and penetration of two or more materials (advanced materials), achieving uniformity in density, concentration, temperature, and other aspects and ultimately achieving the purpose of mixing.

The primary purposes of mixing processes in industrial production are:

1.   To obtain a mixture of two or more ingredients;

2.   To promote physical and chemical changes, enhance heat exchange, and improve mass transfer rate;

3.   To promote chemical reaction processes, such as nitration and polymerization reactions

4.   To improve the performance of some drugs by mixing drugs with different proportions or mixing several different ingredients to form a more widely used drug. Among them, mixing completed in 1 and 4 is an independent unit operation, while mixing in 2 and 3 is an auxiliary operation. For the mixing used in the preparation of gunpowder, we only need to achieve the function of 1, which is to obtain a uniform mixture.

Figure 3.11: Mixing State

The state of various solid ingredients after mixing (as shown in Figure 3.11) can never be an ideal completely ordered mixing state but can only gradually approach this state. The final form of all mixed states is completely disordered and without any regularity. From a macro perspective, we usually refer to the state of a well-mixed mixture with good uniformity obtained in normal circumstances as a random complete state [43].

3.3.2 Study of Uniformity of Powder Mixing

The powder mixing process is a relatively complex random process. Evaluating and determining the uniformity of mixing has always been a problem that has plagued people. Nowadays, the most commonly used method is a statistical analysis to study the solid mixing state, which is the quantitative analysis of the mixing process that is commonly discussed in international conference. Sampling, testing, statistical and data analysis (data mining), and other steps are essential in this process, providing analytical data (data mining) to express the uniformity of the mixing process after completion. Uniformity of mixing is a statistical value in academia, generally represented by variance σ2 or standard deviation σ. Since the degree of mixing is the most important index to evaluate the mixer’s performance, the analysis and calculation process of the degree of mixing will be discussed below.

1.   Sampling

When the mixture reaches a certain degree of homogeneity, a small amount of material is taken from a certain position as a research sample. This action is called “sampling.” The sampling point should be representative, and the small amount of material obtained is called an “observation sample” or “point sample.” The location where the sampling is taken is called the “sampling point.” At the same time, in the same mixer, the mixture obtained from different sampling points at the same time is called the “sample” of that time. The number of point samples is the size of the sample. Usually, the selection of samples must also meet certain requirements. Of course, smaller samples are more favorable for detection. Still, they must first meet the required amount for detection and try to select points that can fully represent the surrounding mixture situation.

On the contrary, if the sample is too large, it wastes materials (advanced materials) and affects the analysis results. At the same time, there are certain requirements for the number of samples. The more samples are selected, the more comprehensive the representation of the mixture is, and the more reliable the quantitative analysis results can be guaranteed. There are also regulations for selecting the sample position: the material after mixing needs to be kept still during sampling, and the sampling point needs to be selected at different positions of the material as much as possible to make it spread throughout the entire mixture. However, in many cases, sampling during the movement flow of the mixture can produce more accurate analysis results than sampling when the material is at rest. Therefore, sampling can also be carried out at the discharge port of the mixer.

1.   Detection

Using professional identification methods to measure the amount of X in each sample (the most important item-tracer) obtained from the completed mixture. If there are 4 samples, 4 results will be detected: X1, X2, X3, X4.

1.   Statistical analysis

The data driven (data mining) by the above analysis methods are calculated through statistical methods to obtain a value representing the degree of homogeneity: the arithmetic mean, also known as the sample mean (x), variance (2σ), and standard deviation σ.

In the formula, “m” represents the number of samples taken, “xi” represents the parameter measured for a certain component in the i-th sample, such as mass, particle number, etc., and “x” represents the average concentration of a certain component, that is, the sample mean.

Before the 1940s, “σ” was used to define (evaluate) the uniformity of powder mixing, where a smaller value of “σ” indicated more uniform mixing. Unfortunately, this calculation method proved somewhat crude in some practical applications and had a sizeable random error in some cases. Its drawback was the failure to consider the effect of sample size.

N. Harnby, an authority on powder engineering and computer science in the UK, stated in his book “Mixing in the Process Industries”: “The practical value of the variance (2σ) obtained from a sample is not great unless there are extreme variance values as variables.” Therefore, another calculation method is commonly used, which is to use the mixing coefficient (M) to represent the mixing state.

M = Amount of mixing that has occurred / Potential mixing amount — (3.8)

The calculation methods for the coefficient of mixing commonly found in domestic and foreign literature currently consist of 10 formulas, which are listed below:

In the formula, 2σ0 represents the variance at the beginning of mixing, which is equal to x(1-x)2σ0;

2σγ represents the variance at complete mixing, which is given by the formula: (x-x)22σγ;

n represents the total number of particles in the sample.

At the beginning of mixing, M=0, indicating no mixing, while the mixing coefficient corresponding to the material at the ideal state of complete mixing should be M=1. Choosing M as a measure of the degree of mixing has its advantage, which is easy to compare. The closer M is to 1, the more uniform the mixing of the mixture. For instance, if M8 is chosen to represent the mixing condition, the fluctuation of the sample will be more sensitive. The above formula is applicable in intermittent mixing processes. In continuous mixing machines, m samples can be selected at the discharge port according to the environmental conditions of the mixing production, and the component values (Xi) of the mixture can be analyzed at a certain moment. Generally, the degree of mixing can be expressed as:

Xi represents the export concentration (or volume ratio) of a certain component;

X0 represents the input concentration (or volume ratio) of a certain component;

X represents the average export concentration of a certain component.

From the above, the degree of mixing (overall uniformity) in batch operation represents the concentration distribution of a certain component in the space of the mixer at any time. However, a continuous mixer represents the change in concentration of a certain component in the mixed material at the outlet with mixing time. In practical applications, mixing curves can also represent the mixing state of the mixer. According to the characteristic mixing curve (shown in Figure 3.12), the mixing speed under experimental conditions can be calculated, and the control mechanism of the mixing operation in the mixer can be determined.

Figure 3.12: Mixing characteristic curve

3.3.3 Mechanism of mixing

Based on the variation of the trajectories of powder particles during mixing inside the mixing machine, the mixing process can be further classified into three modes.

1.   Convective mixing

The reason for the large-scale reciprocating movement of solid particles is the motion of the rotating parts, such as the casing, impeller, or worm in the mixer, which causes the advanced materials to circulate in the mixing container. In other words, many material particles move from one place in the mixing container to another in groups or the opposite direction to the movement of the material in another place. Thus, the two groups of advanced materials are mixed through continuous convection and interpenetration.

1.   Shear mixing

When the material is mixed in the mixer, if the planes of motion of the material groups are parallel but in different directions during the movement of the internal stirring parts, a shear plane will be formed, and the materials will undergo frictional penetration with each other on this plane. It is the shear mixing process.

1.   Diffusion mixing

Diffusion mixing is a local mixing process that occurs when exchanging positions between adjacent material particle groups. The mixing speed is much lower than convective mixing, but it also has advantages, and it can achieve thorough mixing of materials and the ideal mixing state. Diffusion mixing, as the name implies, mainly involves the diffusion phenomenon of fluid molecules, so the mixing process is disorderly.

Regardless of the mixer type, the three mechanisms mentioned above always coexist in the mixing process. However, the extent to which they exist varies in different mixers. In addition, the physicochemical properties of all mixed materials will affect the mixing process to varying degrees. Due to the many factors that can affect mixing and the difficulty of controlling them, it is not wise to use mixing mechanisms as a breakthrough point in the study of mixing rates. Therefore, many issues in solid mixing operations still have to be solved with previous experience.

When a mixer is in operation, we often overlook the phenomenon of particle segregation. This phenomenon hinders the mixing rate and causes well-mixed materials to re-layer, seriously affecting the mixing effect. However, this phenomenon only occurs under specific conditions. It is closely related to the physicochemical properties of particles (particle size and distribution, shape, density, bulk density, aggregation, and flowability) and the type of mixer. The factors that cause segregation can be roughly divided into four types:

1.   When the density or particle size difference between two types of particles is too large;

2.   When the moisture content in the powder material exceeds a certain limit;

3.   When fine powders are taken away in the form of dust;

4.   When particles carry static charges.

The following four methods are the most effective in solving this phenomenon:

1.   Improve the batching method to minimize differences in physical properties;

2.   Increase the viscosity of the material so that the mixed material is not easily segregated;

3.   Improve the arrangement of the material layers during feeding, such that particles in the lower layer move upwards and particles in the upper layer move downwards;

4.   Ensure that the mixed material is in powder form, and equip the mixer with a crushing device or add a transverse mixing function.

3.3.4 Types of Mixers

Mixers can be divided into two categories based on their operation: batch mixers and continuous mixers. Batch mixers are easier to control in terms of mixing quality and are more widely used due to their versatility and elasticity. Depending on how a mixer blends materials, there are four types: container rotary mixers, mechanical stirrers, air-flow mixers, and a combination of these three types.

1.   Container Rotary Mixers

Container rotary mixers are characterized by the continuous rotation of the mixing chamber, which causes the materials inside to mix evenly. Common forms of this mixer include horizontal cylindrical, V-shaped, conical, and three-dimensional mixers. These mixers have a simple structure, a high final mixing degree, and are easy to clean but have a slow mixing speed. They are suitable for mixing powders with good fluidity and minimal differences in physical properties and for mixing powders that are subject to wear and tear. Three-dimensional motion mixers are a common mixer with the highest mixing accuracy among rotary container mixers. They possess good flowability and high loading capacity and can achieve optimal results when mixing particles and powders with different humidity, softness, and relative densities.

However, like everything else, rotary container mixers have two sides. They are only suitable for single feed and mixing, cannot be used for continuous production, and have higher manufacturing materials, processing, and assembly requirements. Also, these mixers cannot be made very large due to safety considerations and safe handling against high strain rates. These two shortcomings prevent them from being used in automated production lines.

1.   Mechanical Stirrer Mixers

The material storage tank of this type of mixer is fixed in place, and the mixing of the materials is achieved by the rotation of the agitator installed inside the tank. It can handle adhesive, highly cohesive powders, wet powders, and pasty materials and is also suitable for mixing production with large material differences. This type of mixer has many advantages, including high throughput and filling efficiency, small operating area (display site), small footprint, and easy operation. Because of these advantages, it is very suitable for use in automated production lines. It can also be designed as a closed type. It can be equipped with a jacket, making it suitable for operation under high temperatures and pressure and for operations such as chemical reactions, pellet manufacturing, drying, coating, and other composite processes.

However, everything has two sides, and the maintenance and cleaning of the machine are difficult, with a high failure rate. Part of the powder will solidify on the container and agitator, which are the drawbacks of this type of mixer.

A common type of mixer is the trough mixer, which is a device that achieves the mixing of materials by mechanical shearing. Its working principle is that when the screw rotates, the screw surface produces a thrust force that pushes the material in contact with it in the direction of the thrust force. Due to the viscosity of the material and the frictional force between the materials, the surrounding materials also rotate so that part of the material is pushed to the upper layer of the screw surface. The surrounding materials and falling materials are continuously replenished onto the screw surface, thus causing relative movement between the material on the screw surface and the surrounding material, achieving the purpose of mixing.

Trough mixers have the following advantages: simple structure and easy operation, and they are widely used. However, this mixer has a lower mixing intensity and longer mixing time. Also, if the densities of the materials used in mixing are significantly different, the material with higher density will easily fall to the bottom of the mixer. Therefore, it is suitable for mixing materials with similar densities.

1.   Airflow Type

The airflow type is an operating method that utilized the upward flow or jetting action of the airflow to achieve uniform mixing of the powder eventually. This type of mixer is suitable for mixing powders with good flowability and similar physical and chemical properties. During intermittent operation, the filling rate of this type of mixer can reach about 70%, and its mixing tank can also be used as a storage tank.

1.   Combined Type

The combined type mixer combines several mixers mentioned previously in terms of function and structure. For instance, a mechanical stirring mechanism and a turbulence plate can be added to a rotary container; mechanical stirring can be added to an airflow stirring mechanism, and so on. For instance, in a pulverizer, if two or more materials are pulverized at the same time, the pulverization process can also become a mixing process, so it is natural to convert the pulverizer into a mixer.

3.3.5 Selection of Mixers

Mixers are relatively simple low investment equipment, and most can be classified and selected based on the applied mixing mechanism. Generally, when selecting solid mixers, attention should be paid to the overall process objectives and various performance details of the equipment. The following is the selection of mixers for the fireworks automation production line.

For the fireworks automation production line we are studying, black powder is the main item being mixed. The main characteristics of the mixing process are:

1.   Black powder is a solid powder. Therefore, a solid powder mixer should be chosen when selecting a mixer.

2.   It is used for the assembly line, requiring a mixer with a high filling rate, small operating area, small space occupation, and easy operation.

3.   The particle size of black powder is a coarse powder with a size of 100-1000μm, which can also be used as a criterion for selecting a mixer.

4.   Safety is required. The materials in the mixing section must not produce static electricity, which is required for the materials.

Figure 3.13: Hybrid Mechanism Diagram

Based on this conclusion, we selected the fixed-container mechanical stirring vertical ribbon mixer (Figure 3.13) from numerous mechanical mixers. In this mixer, the upper cover is designed with a feeding pipe to conveniently feed ingredients into the mixer after the ingredients are weighed. The angle between the generatrix of the conical surface of the mixer and the horizontal plane is 60°.

Figure 3.14: Hybrid Schematic

The main working principle of the mixing process (as shown in Figure 3.14) is that after the various ingredients are weighed, they slide down the feeding channel and into the mixer. Inside the mixer, the mixing motor rotates and drives the auger of the agitator to rotate, thus mixing the various ingredients together. The internal movement of the ingredients during the mixing process is shown in the figure below. After mixing, the discharge valve opens, and the mixed powder slides down from the mixer to the next step.

The power source for the mixing process is the mixing motor. Based on calculations, the Y80M2-2 motor was chosen for the mixing process, and its performance parameters are explained in Table 3.3 as follows:

1.   Y represents an asynchronous motor;

2.   80 is the height of the center of the motor seat in millimeters (when the motor seat does not have a base, it is the same as when the motor seat has a base);

3.   M is the length code of the motor seat (S-short, M-medium, L-long);

4.   2 is the code for the length of the iron core after the letter;

5.   2 after the hyphen is the number of poles of the motor. It is a 2-pole motor with a synchronous speed of 3000rpm. A 4-pole motor has a synchronous speed of 1500rpm.

Table 3.3: Mixing Motor Parameters

3.4 Summary of this chapter

In this chapter, the work sequence of each process was elaborated in detail, and the Mechanism for implementing the corresponding processes was analyzed and designed, such as the feeding and unloading mechanisms. It also includes the analysis and design of parts, such as the worm gear and the weighing tray, and the selection of standard components, such as cylinders and electronic scales.

In the design of the weighing Mechanism, this chapter avoids many errors by selecting the stepper motor. It also sets up six weighing units, which can be configured for up to six types of ingredients. To speed up the efficiency, the control unit can simultaneously feed several units with the same ingredient. In addition, by referring to the research conclusions of predecessors on mixing, we chose a fixed-container mechanical stirring vertical ribbon mixer from among many mechanical mixers. In this mixer, a discharge pipe is designed on the top cover, facilitating the transfer of ingredients into the mixer after weighing. The cone angle of the mixer is 600 concerning the horizontal plane, which makes it easy for materials to slide down.

Chapter 4: Control Study of Weighing and Mixing System

With the continuous development and maturity of PLC technology in various fields, its application in industrial automation control has become increasingly widespread. In the past, many enterprises were greatly hindered in increasing industrial productivity due to the lack of automation equipment and the inability to make changes according to different production process requirements. With increasingly mature electronic technologies such as PLC, sensing technology, and interface technology, simply adding PLC communication technology based on universal instruments can complete the weighing and mixing process by transmitting the signal from the sensor to the PLC as a switch. The processing function of PLC expands the function and application scope of electronic scales. It greatly improves its performance in terms of cost-effectiveness, control flexibility, operational simplicity, and management automation.

For the convenience of expression, this chapter selects the main framework (as shown in Figure 4.1) to illustrate, which includes a feeding hopper and feeder for a selected ingredient, as well as a corresponding tray, electronic scale, and unloading cylinder. Below them is the mixer, with the main components, including the mixing screw and the unloading valve of the mixer, etc., which are explained in detail.

Figure 4.1: A simple schematic diagram of the Mechanism

The working principle of the weighing and mixing systems has been widely discussed, and their implementation methods are varied. This paper uses the Mitsubishi FX2N series PLC to control the systems. The electrical components used include a stepper motor, an electronic scale, a mixing motor, an electromagnetic reversing valve in the pneumatic systems, and limit switches for cylinders. These components are automatically controlled to achieve the automation of the entire systems.

The system’s working principle can be divided into two parts: the weighing process and the mixing process. However, these two parts do not operate independently, and the mixing part also restricts the weighing part. The working principle of the weighing-mixing system is as follows:

1.   Check whether the hopper has enough material to proceed to the next step. If insufficient material exists, an alarm will be triggered, and a request will be made to add material to the hopper.

2.   The stepper motor starts working.

3.   The material is fed by the worm gear driven by the stepper motor. The stepper motor quickly advances by nine steps and then stops working.

4.   The material falls onto the tray, and the electronic scale begins weighing. If the weight is less than the set weight, the process proceeds to step 5.

5.   The stepper motor continues to work, taking a specific number of step angles, i.e., jogging.

6.   The material falls onto the tray, and the electronic scale continues to weigh. If the weight is greater than the set value, the entire weighing process ends. If it is less than the set value, the stepper motor takes a specific number of step angles until it is greater than the set value, and then a signal 1 is issued.

7.   When signal 1 is received, the stepper motor stops working;

8.   When unloading cylinder A receives signal 1, it starts running data driven until the tray is pushed to a specific tilt angle, and the tray’s limit switch sends signal 2;

9.   When cylinder A receives signal 2, it starts a delay and then resets itself;

10.   When the mixing systems receives signal 1, it starts to mix with power;

11.   The start of the mixing motor restricts the movement of cylinder A;

12.   When the granulating systems sends a material request signal 3, the unloading valve of the mixer starts working;

13.   When unloading cylinder B drives the valve to its maximum opening, it triggers the valve limit switch and then resets after a delay of 30 seconds, and the unloading is completed; at the same time, the mixing motor stops working after a delay of 40 seconds and sends signal 4;

14.   The unloading cylinder A for weighing receives signal 4 and releases the lock;

15.   The entire system stops working.

In the entire weighing and mixing systems, the most important part is the coordination between the stepper motor and the electronic scale in the weighing process, as well as the power-on or power-off of the mixing systems, which affects the locking or unlocking of the unloading cylinder. The coordination between the stepper motor and the electronic scale is crucial because it ensures the accuracy of the entire weighing system, especially during the correction process, which can adapt to various high-precision weighing requirements. The importance of the power-on or power-off of the mixing system lies in the fact that if the mixing of this section has not been completed, no further ingredients can be added to the mixer, otherwise not only the accuracy of the weighing is lost, but also the entire system will become chaotic. The overall flow chart is shown in Figure 4.2, which better reflects the logical relationship between each step.

Figure 4.2: Overall Process Flowchart

In the control process, it is necessary to consider that when a beat’s mixing is not yet completed, the ingredients for the next beat cannot be sent into the mixer. Also, the mixed material in the mixer can only be sent into the granulator once the granulation is completed. These requirements can be well met through the use of a PLC.

4.2 System Architecture of the Weighing Mixing System

When studying the weighing mixing system as a whole, the control method is also studied as a whole. To facilitate a clear understanding of the system’s workflow and the relationships between the various functional components, a flowchart (as shown in Figure 4.3) is used to illustrate the process. On the other hand, this can also better arrange all the work steps logically.

Figure 4.3: Mixed Process Flow Chart

4.2.1 Overall Process Flow Chart

All functional components are in the set time sequence in the overall process flow chart. The system mainly consists of three parts. Although it is called an overall process flow chart, the weighing part is the most introduced in the above overall process flow chart. In the study of the weighing process, the PLC controls the fast and slow feed of the stepper motor.

The advantages of the weighing system are:

1.   The electronic scale inputs the switch quantity to the PLC when reaching the specified value. The electronic scale determines the weighing accuracy, and the stepper motor determines the feeding accuracy.

2.   The electronic scale is set to be greater than the standard value, which can compensate for some of the losses in the manufacturing process.

3.   By using a stepper motor, the feeding accuracy is improved; of course, this accuracy is within the range of the electronic scale accuracy.

Figure 4.4: Self-check Process Flowchart

Figure 4.3 shows the flowchart of the hybrid process. The advantages of the hybrid system are as follows:

1.   The mixing time is not set in the mixing process. This stage is between weighing and granulating, and the time saved in the weighing stage is used for mixing. Extending the mixing time can improve the effect of mixing various ingredients.

2.   The mixing motor starts and stops every beat to avoid long motor rotation time, which leads to a long friction time between the mixing screw and the material, causing a temperature rise. It can play a certain cooling role.

3. The mixing motor still rotates when the discharge valve is opened to help discharge the material.

4.2.3 Automatic Detection Flowchart

The self-inspection system (shown in Figure 4.4) is also called the startup fault diagnosis system. In these two links of the automated production line, indicator lights are used to indicate the cause of the fault and corresponding actions are taken based on the cause, such as filling the material hopper when the indicator light shows insufficient material, controlling the cylinder to return to its original position when the cylinder does not return, and checking the specific cause of the motor’s fuse failure and replacing it with a new one. It ensures that the components of the production line are not damaged and the production process runs smoothly (data driven).

The role of the flowchart is to clearly understand every action of the fireworks production line and the logical relationship between each action. The system’s flowchart is roughly divided into three parts: weighing, mixing, and automatic detection. With this understanding before controlling it, the workload can be simplified, and a rough understanding of the control part can be obtained for future use. There is a clear understanding of the contacts, electrical components, and pneumatic components in the production line, their locations, connection methods, and corresponding functions.

4.3 Electrical Control System

When designing a control system, drawing electrical schematics (as shown in Figure 4.5) is essential. In the diagram, basic functions such as start, protect, stop, and emergency stop are included in the design. The control section is divided into manual operation and automatic operation. In addition, the self-checking operation before operation and the prompt of each step of the self-checking operation, as well as the method and operation of each electrical device connected to the circuit, are included. In this circuit, the mixed motor and air pump are connected to a voltage of 220V, and the control circuit is 24V. The operation process follows the logic expressed in the flowchart. Before the operation, the circuit should be automatically checked. Various faults have their own alarm lights. Afterward, the system is set to manual and automatic modes for manual or automatic operation. In case of an emergency, press the emergency stop button.

Figure 4.5: Electrical Schematic Diagram

The electrical schematic diagram shows the contacts involved in controlling the cylinder movement. The cylinder is part of the pneumatic system, and its movement is controlled by controlling the directional valve, which is controlled by the on/off state of the contacts (as shown in Figure 4.6). The pneumatic schematic diagram includes the pneumatic control methods for the unloading cylinder of the tray and the cylinder that drives the unloading piston. When KM16 is powered, the unloading cylinder of the tray starts to move, pushing the tray to unload. When the tray reaches a certain position, the position switch is triggered, KM16 is turned off, and the cylinder and tray are reset together. When the granulation system sends a signal for feeding and the mixing is complete, KM20 is powered, and another cylinder moves to open the discharge valve. When it reaches a certain position, the position switch is triggered, and after a certain delay, the cylinder drives the closing of the discharge valve.

Figure 4.6: Pressure System Diagram

The electrical circuit part of the system includes the power supply unit, manual and automatic control circuits, and startup automatic detection circuits. The UPS power supply is selected to provide 24V DC and 220V AC to the PLC and stepper motor driver, respectively. The detection circuit utilized the working characteristics of the stepper motor’s three-phase six-beat stepping method, which means that at any time, two phases are in an energized state. Effective control can be achieved by constantly detecting the current flowing through the wiring of each phase. When the current exceeds 2/3 of the rated current, the stepper motor is in normal working condition. If it is lower than 2/3 of the rated current, the stepper motor is considered to be in an undercurrent operating state[44]. The electrical schematic diagram also connects the control circuit and the stepper motor. In this system, the stepper motor driver is controlled by a PLC, and then the stepper motor is controlled. This type of control is relatively stable.

4.4 Automatic Control

The core controller of the automatic control in this control system is Mitsubishi FX2N series PLC. The Mitsubishi FX series PLC is a super small programmable device with high speed, high performance, and the highest level of all aspects in the FX series. In addition to the independent use of 16-25 points for input and high throughput, it can also be used to connect multiple basic components, analog control, positioning control, and other special applications, making it a set of PLCs that can meet a wide range of diverse needs. Its features are a fixed and flexible system configuration, simple programming, various options, reliable high performance, high-speed operation, use in various special applications, simplified communication with external machines, and common external devices[45].

4.4.1 FX2N Series PLC

The FX2N series PLC (as shown in Figure 4.7) has the following characteristics [46]:

1.   Developed many functions to meet production requirements;

2.   Communication function. On the one hand, it can be connected to well-known public networks (CC-Link, Profibus Dp, and Device Net) worldwide, and on the other hand, it can solve your communication needs at the sensor network level;

3.   An auxiliary function that can act as a power supply. It has a built-in power supply that can provide 24V, 400mA DC power supply to power peripheral devices;

4.   Continuous scanning function. Define the operating cycle for the required continuous scanning time of the application;

5.   Input filter adjustment function;

6.   Annotation recording function;

7.   Online program editing;

8.   Remote maintenance.

Figure 4.7: Mitsubishi FX2N Series PLC

In areas with abrupt changes in current or voltage, the magnetic field will undergo drastic changes, which can affect the application of the PLC equipment and produce electromagnetic radiation on mechanical equipment. With the presence of interference sources, it is important to actively avoid them as changes in the magnetic field can cause current to be induced in the surrounding conductive components, which can easily generate electromagnetic waves that strongly interfere [47]. The specific sources of interference are as follows:

1.   Strong electric interference. With the rapid development of the power grid, it is everywhere and has a large coverage area. External electromagnetic waves will produce induced voltage if the power grid is affected. The opening and closing of knife switches, the startup, and shutdown of large industrial power generation equipment, harmonic waves generated by transmission equipment, transient impacts caused by short circuits in the power grid, etc., can all affect the stability of the power supply to varying degrees.

2.   Interference inside the cabinet. There may be some high-voltage electrical appliances and large inductive loads inside the electrical cabinet, and the disorderly arrangement of the wiring can also affect the PLC.

3.   A disorder in the grounding system causes interference. Grounding errors can lead to strong interference, affecting the PLC system.

4.   Interference from within the PLC system. Such interference mainly occurs between the internal components and circuits of the system. They are electrical appliances themselves and can cause interference by generating electromagnetic radiation with each other.

5.   Inverter interference. The use of inverters is a technological advancement, but there are also many interferences in their application. It generates harmonics during its startup and operation, which can cause interference. Moreover, it produces strong electromagnetic radiation during operation, which belongs to a serious interference source.

4.4.2 Controller

The importance of the controller in the control system is self-evident. It performs logical control, operation, and data processing (data mining) on various switch quantities and analog quantities of the entire system. After being processed by the microprocessor, it outputs various switch quantities and analog quantities to control the system’s proportional valves, solenoid valves, motors, etc., to achieve various system functions through data mining. The controller consists of a CPU module, memory, input/output module (I/O module), power module, communication interface module, and other parts. The CPU module stores user programs, checks the status of various components of the system, diagnoses syntax errors in user programs, receives input data (data mining), reads programs, and executes logical control, operation, and other functions according to the instructions. The memory comprises a system program storage area, a user program storage area, and a system RAM storage area (used to store some data (data mining) that changes frequently and does not need to be saved for a long time). The I/O module consists of various input/output modules, generally including switch quantity input modules, analog quantity input modules, switch quantity output modules, analog quantity output modules, pulse width modulation (PWM) output modules, data mining, data driven etc.

4.4.3 Control of Stepper Motor by Controller

The Mitsubishi PLC has a high-speed pulse counter and pulse generator, whose radio frequency can reach up to 10KHz, which can meet the requirements of the stepper motor (as shown in Figure 4.8). Two characteristics are required for the PLC in this application. Firstly, the PLC used in this application should preferably have real-time refresh technology so that the output signal frequency can reach several kilohertz or higher. The purpose is to enable high-speed pulse allocation and make full use of the speed response capability of the stepper motor to improve the overall system’s speed. Secondly, the output port of the PLC itself should use high-power transistors to meet the driving requirements of tens of volts pulse voltage and ampere pulse current for various phase windings of the stepper motor.

Figure 4.8: Stepper Motor Control Diagram

The selection of stepper motors (as shown in Table 4.1) is based on the principle of maintaining torque. Maintaining torque is similar to power, but there is a significant difference in essence. A Stepper motor is a digital electromagnetic actuator that converts pulse signals into angular displacement. When the stepper motor is directly connected to the PLC, the angular displacement of the stepper motor is proportional to the number of input pulses, its speed is proportional to the pulse frequency, and its rotation direction is related to the phase sequence allocated to the various phase windings of the stepper motor [48].

Table 4.1: Detailed Information on Stepper Motors

Due to the ability to be controlled directly by digital signals without requiring feedback for open-loop operation and with no accumulated positioning error, the stepper motor has high control accuracy, making it widely used in precision positioning control systems such as digital and computer control. The external pulse and direction control signals are used to control the driving power supply’s on-off state and the power supply sequence of each phase winding, respectively, to achieve control. Each pulse signal can rotate the stepper motor at a fixed angle, known as the step angle. The number of pulses determines the total rotation angle, the pulse frequency determines the rotation speed and the direction signal determines the rotation direction. Furthermore, by subdividing the control, the step angle of the stepper motor can be divided into m small steps to achieve higher precision control [49].

The operation of a three-phase stepper motor follows a three-phase single-six-beat operation. The sequence for forward rotation is A→AB→B→BC→C→CA→A. It’s experimental wiring (as shown in Figure 4.9) involves connecting the stepper motor directly to the PLC.

Figure 4.9: Experimental connection of a stepper motor

Controlling a stepper motor involves controlling the pulses. The higher the frequency of the pulses, the faster the stepper motor rotates; the lower the frequency, the slower the stepper motor rotates. In the timing diagram of a normally functioning stepper motor (as shown in Figure 4.10), each phase is in one of two states at any time: either two phases are working, or one phase is working. It is also commonly referred to as a three-phase, single-six-step.

Figure 4.10: Timing diagram of experimental connection method

When controlling a stepper motor, the power supply to its various phase windings must be circularly allocated in a specific sequence. It controls the 24V DC power supply connected to the three-phase winding of the stepper motor, thereby controlling the on/off state of the winding in sequence to form a rotating magnetic field, which makes the stepper motor rotate. The stepper motor is an inductive load, so the DC resistance is very small. The coil needs to be connected with a current-limiting resistor to ensure that the pulse current is not too large, which can damage the stepper motor. When the power supply sequence for the various phase windings of the stepper motor is: A-AB-B-BC-C-CA-A, the stepper motor rotates forward when the winding is turned on and off in this order. After the program is compiled, the number of steps is set, and the stepper motor decreases the step number by one every time it takes a step. When this number reaches zero, the current pulse distribution is completed, and the system begins to detect the next pulse signal input.

However, in practical operation, the operation of the stepper motor often requires an electronic device to drive it. This device is commonly referred to as a stepper motor driver [50]. Its function is to amplify radio frequency of the pulse signal issued by the control system through an amplification circuit to a level that can drive the stepper motor. The control program of the PLC is also much simpler. The frequency of the pulse signal emitted determines the speed of the stepper motor. The higher the pulse signal frequency, the faster the stepper motor rotates, and vice versa. When controlling the stepper motor, it is important to master these two principles: first, controlling the frequency of the pulse signal to adjust the speed of the motor precisely, and second, controlling the number of pulses emitted to determine the position of the controlled system precisely.

The wiring between the three-phase driver and the stepper motor is relatively complex in practical applications, including the input of pulse signals, forward and reverse rotation, and release signals. The other two phases have similar connection methods. By drawing an electrical schematic diagram, draw the ladder diagram of the PLC (as shown in Figure 4.11). Its operating process is that when the automatic control button is pressed, X006 is connected and triggers the protection function of Y026, and the feed starts. X015 is the normally closed contact of fast forward, disconnected after the set 9 turns of fast forward, and the slow feed starts simultaneously. Each time, the slow feed delivers 3-step angles of ingredients until the set weight is reached. At this time, the electronic scale sends a signal to trigger the normally closed contact X014 to disconnect, and the feed stops. The normally open contact X014 of the control cylinder A is closed, and cylinder A pushes the ingredients on the tray into the mixer. Cylinder A pushes the tray to a certain position, triggers position sensor 1, and sends signal 1 to trigger Y020 to disconnect.

On the one hand, cylinder A returns to its original position, and on the other hand, the mixing motor starts to mix. X021 is the material signal of the pelletizing system. When the pelletizing system needs materials, X021 is closed, triggering the movement of cylinder B that drives the unloading piston to start unloading, and two delays start. T1 triggers Y020 to be in the normally open state again (that is, the mixing motor stops after the 40s), and T2 triggers Y022 30s later (that is, preparing for the next timing, and cylinder B returns to its original position after 30s).

Figure 4.11: Trapezoidal Diagram

4.5 Summary of this Chapter

This chapter mainly focuses on the control of symmetrical heavy-duty mixing systems. In the research process, the execution mechanisms and logical sequences of each action were studied. Flowcharts were drawn, and the system was controlled based on the flowcharts. An electrical control schematic diagram of the entire control system was drawn, and the local systems and components used were explained. Finally, a trapezoidal diagram was drawn to facilitate PLC control.

Chapter 5: Motion Simulation of Ingredient System

5.1 Local Mechanism Analysis of Ingredient System

Simulation analysis using Pro/Mechanism mainly involves two steps: 1. Assembling parts to create a mechanism; 2. Adding drivers and algorithms and conducting motion simulation analysis to obtain simulation results.

Using the assembly module in Pro/E software [51], the rotating guide rod mechanism was created by utilizing the previously simulated part entities and adding corresponding constraints. In the Pro/E system’s assembly mode, the system’s default position fixes the frame parts as the basis (as shown in Figure 5.1) and the screw conveyor and feeder (as shown in Figure 5.2), as well as the mixing screw and mixer (as shown in Figure 5.3), are connected using pin connections.

The cylinder’s piston rod and discharge piston are connected by a sliding rod connection method, and their range of motion is set (as shown in Figure 5.4). The tray is connected to the tray supported by a pin (as shown in Figure 5.5), and the range of rotation of the tray is set (as shown in Figure 5.6).

5.2 Overall Simulation of Weighing and Mixing Mechanism

After assembling the Mechanism, the Pro/Mechanism module of Pro/E software is used to observe, record, and analyze the displacement, velocity, acceleration, and other parameters of the relevant parts during the simulation movement.

In this design, the parts that move include: 1. the rotation of the worm in the feeder; 2. the translation of the tray driven by the cylinder; 3. the rotation of the pushed tray; 4. the rotation of the tray on its way back; 5. the translation of the cylinder on its way back; 6. the rotation of the screw in the mixer; 7. the opening translation of the discharge valve driven by the discharge cylinder; 8. the resetting translation of the discharge piston.

From the main interface of Pro/E, select the “Application” menu to enter the “Mechanism” submenu and access the Pro/Mechanism simulation environment. Click the cam button on the right toolbar to connect the bottom surface of the weighing tray and the top surface of the cylinder piston rod together structurally, and then lift them.

Figure 5.7: Connection between the Weighing Tray and Cylinder Piston Rod

After completing the cam connection, click the servo motor button in the right toolbar to bring up the “Servo Motor Definition” dialog box. On the “Type” tab, set the driving element to a rotating shaft and select the hinge and crank connecting shaft as the object of the motor’s action. On the “Profile” tab, set the rotation speed, A value, and initial value of the rotating shaft to a constant or set the translation speed, A value, and initial value of the sliding rod. Click the OK button to complete the addition of the driver (as shown in Figure 5.9), and then define the operating time for each motor (as shown in Table 5.1).

Table 5.1: Status of each servo motor

Click on the mechanism analysis button in the Pro/E main interface to open the “Analysis Definition” dialog box, set the “Type” to “Position,” and then define the operating time of the motor (as shown in Figure 5.8). To ensure the simulation’s authenticity, wait 5 seconds when unloading the tray, 5 seconds when importing ingredients into the mixer, and 5 seconds when unloading from the mixer. Then click the “Execute” button in the dialog box to see the Mechanism’s operation.

Figure 5.11: Modulus over time curve at a certain position at the tail end of the tray

After completing the definition of motion analysis, click the analysis measurement button on the Pro/E main interface. In the pop-up “measurement result” dialog box, select the new button and perform the corresponding settings in the “measurement definition” dialog box that appears immediately after to complete the measurement definition setting. In the “measurement result” dialog box, select both the newly created measurement definition and the corresponding mechanism motion analysis in the result set. Click the “draw graphs of the selected measurement for the selected result set” button, and the system will display the results in the “graphics tool” window. Select a point at the top of the cylinder piston rod and measure the x component at each time step (as shown in Figure 5.10), as well as the modulus of a point at the rear of the tray at each time step (as shown in Figure 5.11). Through the measurement of position over time, the approximate running status of the cylinder during operation, whether the maximum stroke is consistent with the design, etc., can be observed. It can also be seen when the tray’s selected position can be reached under the cylinder’s push, the highest time and position point that can be touched, and whether the expected position switch can be reasonably applied together. From the Pro/E main interface menu bar, select the “Insert” menu, click the “Trajectory Curve” command, and a “Trajectory Curve” dialog box will pop up. In the “Trajectory Curve” drop-down list, select the motion trajectory of the point as “Trajectory Curve,” and you can obtain the motion trajectory curve of a point on the weighing tray during the entire simulation process (as shown in Figure 5.12).

Figure 5.12: Motion trajectory curve of the rear end of the tray

After motion simulation and analysis, it can be concluded that the training model design of the weighing and mixing section meets the motion requirements and that the simulated motion meets the design requirements. The overall requirements of weighing and mixing can be achieved, and the results are basically consistent with the actual design requirements. It can be applied in practice while improving the overall understanding of self-designed objects, preparing for further optimization proposals, and providing a reference for future production.

5.3 Summary

Based on the examples listed above, it can be seen that creating a solid model for the rotating guide rod is the basis for conducting kinematic simulation analysis and optimized design. Using Pro/E three-dimensional solid modeling techniques can make the motion of the rotating guide rod, which is difficult to express in a two-dimensional state, intuitive, and easy to modify, achieving parameterized solid modeling and obtaining simulation animations. As an effective tool for analyzing mechanism motion, Pro/E can simulate the motion process of the Mechanism, analyze the motion of the Mechanism, inspect the assembly and design of parts, and assist designers in mechanism development and design, thereby achieving the purpose of reducing design cost and improving product quality for enterprises.

Chapter 6: Conclusion and Outlook

6.1 Achievements and Conclusions of the Thesis

The weighing and mixing part of the fireworks automatic production line has many advantages, such as a simple and compact structure, low cost, high operational reliability, and a flexible electrical control scheme coordinated with other functional parts. The fireworks automatic production line itself is an unprecedented innovation. Compared with the traditional production process that relies on independent manual operations for each part and manual connection between machines, it represents a qualitative leap. Its appearance marks a significant improvement in the production efficiency of fireworks, and unlike before, it requires minimal or no human involvement. Therefore, it has attracted widespread attention and is regarded as the future mainstay of fireworks production mode.

When studying the weighing and mixing part of the fireworks automatic production line, the weighing precision and mixing uniformity have always been the focus of research. In addition, the electrical control of these two processes during production was also studied. This paper focuses on these three research directions. The main work of this paper can be summarized as follows:

1.   Based on a detailed analysis of the weighing precision of the weighing Mechanism, this paper proposes a model with high weighing precision after balancing between theory and practicality. By studying the problem of mixing uniformity and considering the design requirements of the production line, a mechanical screw mixing model is established. The two models are compactly merged to establish a kinematic simulation model of the entire weighing and mixing system. On this basis, the mechanism motion simulation module Pro/Mechanism of the PRO/E software is applied to observe, record, and analyze the displacement, velocity, acceleration, and other parameters of the relevant parts during the simulation motion.

2.   After a thorough analysis of the control key feature of the symmetrically weighed mixing section, this paper deals with the control of the pneumatic system directional valve, motion control of various mechanical mechanisms, start-stop control of the hybrid electric motor, start-stop control of the air pump, and control of the stepper motor, among other things. The control section is divided into manual control, automatic control, and automatic startup detection. An electrical schematic diagram is drawn, and the control scheme is explained in detail. The automatic control system is completed using the Mitsubishi FX2N series PLC, and a ladder diagram is drawn using GX-explorer. After debugging, it operates normally.

Revolutionizing the Fireworks Industry: An Automated Production Line proposed Solution to Increase Efficiency and Safety. Learn how a new approach to fireworks manufacturing tackles the industry’s biggest challenges head-on with innovative proposed solutions that improve production speed and reduce accidents. This article presents a comprehensive plan for implementing an automated production line, addressing critical factors such as weighing precision and mixing homogeneity. Discover the groundbreaking research behind this new system and its impact on the future of fireworks manufacturing.

6.2 Future Research and Prospects

Overall, this article has made some progress in establishing weighing, mixing, and automatic control models. However, due to limitations in knowledge, practical experience, and time, many issues still need to be further researched. These can be mainly summarized in the following two points:

1.   In the modeling process of the weighing system, the weight of each step angle increment feeder is mainly calculated based on theory. Precision analysis and motion simulation are then carried out. These will cause the established model to deviate from the actual situation. Future research will focus on how to recognize the existence of various errors in practice and make compensations. The modeling process of the mixing system is mainly based on the three states of the mixing process. While studying the uniformity of mixing, several mixing models are studied. Based on the requirements of the automated production line, a more suitable mixer model is selected. However, since powders differ from fluids and can even have a viscosity in practice, it is a further issue to study whether the heat generated by friction with the mixer wall can cause an explosion.

2.   The design of the automated control system still lacks a more systematic design method. Automated control, from signal input, signal processing, signal reception, signal output, signal amplification, signal transmission to the power appliance, signal feedback, and then to the PLC control stepping motor driver to realize the control of the stepping motor, is a more complete and mature control system. However, there are various types of signals. The selection of input signals, the stability, sensitivity, and feasibility of various signals, and the suitable application environment for various signals all need to be studied.

As a major innovation in the fireworks industry, with the development of power electronics technology and control theory, the automation of fireworks production lines will also mature. In the near future, it will soon demonstrate its overwhelming advantages in fireworks production and manufacturing. It will conquer fireworks manufacturers, go abroad, and go to the world.

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