Industrial robot car spraying simulation design based on Robot Studio

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Summary

In recent years, as the popularity of automobiles increases, consumers have increasingly higher requirements for the appearance and performance of automobiles. Major automobile manufacturers have transformed traditional paint production lines to improve production efficiency and save production costs. The emergence of spray robots and their use play a decisive role in the automotive painting production line. This article uses the Robot Studio offline simulation software independently developed by ABB to simulate the paint production line, and conducts an in-depth discussion on its repeated positioning accuracy, color cleaning and other aspects.
First, the function, history, and process flow of the coating production line are described, and its development process, characteristics, research background, and research significance are briefly introduced. This article analyzes the hardware composition, color changing and cleaning mechanism of the spray painting robot coloring system, analyzes the problems and influencing factors caused by it, and designs the preprocessing software. The paint film problems that are easily produced by robots during the spraying process were studied, the causes were analyzed, and solutions were proposed. The influence of various process parameters such as electrostatic voltage and molding air was analyzed.
Secondly, the posture repeatability and posture accuracy of the robot are analyzed, and the Jacobian matrix is ​​proposed to express the relationship between the angular velocity and speed of each joint axis of the robot; this paper analyzes the development status of offline programming technology, and analyzes the development of offline programs. The functions of each module and interface are explained in detail, and the overall design idea of ​​offline programming is given.
Finally, based on the Robot Studio simulation software, the layout of the painting line workstation was realized through the Robot Studio simulation software, and the workpiece coordinate system, tool coordinate system, offline conveying system module, and spray model profiling module were established.

Key words

Robot Studio; car painting; offline programming; model simulation

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1 Introduction

1.1 Research background and significance

Science and technology are the primary productive forces of mankind. The development of science and technology has promoted the rapid development of society and greatly improved people's quality of life. Automobile body painting is a key technology in the automobile industry. It directly affects the appearance, waterproofing, body quality and corrosion resistance of the automobile.
Coating is a surface treatment technology that can cover and effectively protect the surface of the coated workpiece, decorate it and extend the service life of the workpiece. Paints are widely used in civilian and military fields. Spray painting is divided into manual spray painting and automatic spray painting. In the automotive painting industry, long-term exposure to a poor coating environment has caused great harm to the health of workers. In order to solve this problem, automatic spraying gradually replaced manual spraying in many cases. Automatic spray painting mainly includes automatic spray machines, spray painting robots, etc. This paper uses an electrostatic spray painting robot. The advent of this robot has greatly improved the health hazards to manual spray painting workers and also greatly improved the efficiency of spray painting. and quality.
There are many types of industrial robots, such as jet robots. Currently, there are KUKA, FANUC, KAWASAKI, ABB, YASKAWA, etc. in the world [1]. Among industrial robots, the positioning accuracy of spray gun robots is not high, but many parameters must be designed based on the characteristics of the workpiece and the external environment, such as spray gun speed, paint flow, electrostatic voltage, rotary cup speed, molding air pressure, etc. The dimensions of these values ​​are not static. For example, in the variable spraying process, due to changes in the shape, curvature and other factors of the workpiece, they need to be adjusted in real time to achieve the requirements of the spraying process and make the thickness of the coating uniform. On the basis of the spray painting process, an important technology must also be introduced, namely the TCP track planning of the engine. The TCP operating route will directly affect the vehicle's painting quality and production efficiency. In the early days of robot painting, manual teaching methods were mostly used. The instructions were displayed on the construction site to mark key parts, and then the spraying route was drawn. However, this method has great risks. Construction workers have to be at the spraying operation site, and their life safety is also at risk. will be affected. At the same time, the effect of manual teaching is also relatively poor. This is why offline programming technology appears. Technicians do not have to go to the site in person every day like before. They only need to draw a 3D environment similar to the site on the spray painting simulation software, and then write code to simulate it. After the simulation is completed , input the code into the simulator to control the movement of the jet robot. This method can not only greatly improve the efficiency of debugging, but also ensure the normal operation of the pipeline. The spraying robot in the picture below is an IRB5500 manufactured by ABB.

Figure 1-1 IRB5500 spray robot

1.2 Research status at home and abroad

Dating back to 1966, Niels Nielsen, Charles Rosen and others at the Stanford Research Institute in the United States had already begun researching artificial intelligence robots, and successfully built the world's first robot, Shakey, in 1972. Shakey can complete real-time control under various complex situations, but because computers at that time were still in the state of DOS system, that's how Shakey's name came about [2]. It was not until 1999 that Probotics successfully developed a mobile robot "Cye". This product has two-wheel differential control and can transport drinks, letters and other daily items in a trailer indoors. It also functions as a traction vacuum cleaner [ 3].
The Japanese HONDA company released a toy robot called ASIMO in 2000. ASIMO is an intelligent robot that combines visual sensors and ultrasonic sensors. It can not only run and walk, but can also go up and down stairs, and can also pour people cups. It can drink tea and play football. For more than ten years after the advent of ASIMO, this robot has been the most advanced humanoid robot in the world [4]. In 2006, the JSPS team at the University of Tokyo in Japan designed a cooking robot that can communicate with people. Users can prepare ingredients and make dishes according to its prompts. However, this kind of human-computer interactive robot is only a preliminary experiment and has not yet been fully formed. South Korea's Yujin Robotics launched an intelligent robot in 2008. It can sing at home, do housework, move around the house to avoid obstacles, and can also check whether the door is locked when no one is around. This is a very Powerful product. In 2010, a Japanese restaurant in the Thai capital used service robots to serve food to customers. This service robot can provide customers with menus on the touch screen, dance rhythmically, and move to the table to pick up empty plates for guests [5]. In 2015, "Pepper", a humanoid robot jointly developed by Japan's SoftBank (SoftBank) and France's Aldebaran Robotics, relies on its huge data collection capabilities and computing power to not only allow users to enjoy more social experiences in social life At the same time, it can also provide intelligent guidance and puzzle-solving services in hospitals, cafes and other places. It is a revolutionary product that promotes the introduction of intelligent service robots to the public and even their popularization [6].
Today, there is already a fairly complete robot system in the world. Developed countries such as Japan, South Korea, and Russia have achieved very good results in the research and development of service robots. Japan is also a global leader in the research and development of service robots. Both government policies and leading domestic companies attach great importance to service. Research and development of robots. Between 2006 and 2010, Japan invested US$10 million annually in the research and development of service robots. As of today, Japan is the most technologically advanced in the world in developing human-intelligent robots that can recognize human emotions through technologies such as facial recognition and language recognition. However, the flexibility of limbs during exercise has not been well addressed. In terms of robotics technology, South Korea ranks second in Asia after Japan. The Korean government attaches great importance to the development of the robotics industry. In order to occupy a larger proportion in the field of robotics, South Korea has formulated the "Top Ten Industries of the Future" and "2022 "Robot Development Strategy" [7], Korean robot technology can imitate most of human actions and can walk on two legs in terms of flexibility, but the balance of the body needs to be improved. The United States is the home of robots, and its technology is second to none in the world. American military robots occupy 60% of the world's market. The "U.S. Service Robot Technology Roadmap" of the United States elaborates on the development status and development strategic layout of service robots. American service robots use two-wheel differential transmission to make mobile traffic smoother, and have multiple functions such as memory and positioning navigation [8].
Compared with foreign countries, the development of robot technology in our country is relatively lagging behind, and there is a certain gap with the world's advanced level. In 1995, Tsinghua University developed a nursing robot with a 7-degree-of-freedom manipulator, which can provide a variety of nursing services such as medicine and water delivery to paralyzed patients. Shanghai Jiao Tong University launched the Jiaolong intelligent wheelchair and Jiaolong guide robot in 2010. These two robots will welcome tourists from all over the world during the World Expo. Jiaolong intelligent wheelchair is equipped with multiple sensors such as gyroscope, lidar, and vision, which has high autonomous position accuracy and high reliability. In 2015, Harbin Institute of Technology Robot Company independently developed a welcome robot named "Will". It has multiple functions such as face recognition, automatic navigation, obstacle avoidance, voice interaction, safety monitoring, etc., and can be customized by users. APP provides customer service and welcome guests. It is suitable for banks, business halls, airports and other places with large flow of people [9]. "Anbot" was jointly developed by Wanwei Intelligent Robot Technology Co., Ltd. and the Intelligent Science Research Institute of the National University of Defense Technology. It attracted the attention of many audiences at the Shanghai International Service Robot Technology and Application Expo. Anbot integrates advanced technologies such as system positioning, intelligent path planning, and image analysis. It can replace security personnel's patrolling, monitoring, and identification, and will automatically return after completing the task. In recent years, as the government has paid more and more attention to the research and development of service robots, as an important direction for industrial transformation and upgrading, the country has issued many development plans for intelligent service robots, such as the "Service Robot Technology Development" issued by the Ministry of Science and Technology. The "Twelfth Five-Year Plan" [10] proposed to achieve breakthroughs in the field of service robots and launch new products with market prospects.
After the deep learning model was proposed in 2006, artificial intelligence entered its third stage of rapid development. With the continuous development of artificial intelligence technology, the market size of service robots is rapidly expanding. Since 2014, the market size of service robots has grown at an annual rate of 21.9% and will reach US$9.46 billion in 2019, and is expected to exceed US$13 billion in 2021. According to 1 FR data, the global market size of home service robots is 4.2 billion US dollars, medical service robots are 2.58 billion US dollars, official robots are 2.68 billion US dollars, and home service robots are 44% [11].

Figure 1-2 Global service robot sales and growth rate from 2014 to 2021

2 Overview and definition of relevant basics

2.1 Overview of coating production line

2.1.1 Definition and functions of coating

Definition: Coating is to apply a coating on the surface of a workpiece and form a thin film after drying.
Function: Protection: Applying a layer of corrosion-resistant, wear-resistant, and water-resistant coating on the surface of the workpiece can protect the workpiece and extend its working life.
Decorative effect: Paint can give the workpiece luster, color, three-dimensionality, smoothness, etc., making it aesthetically pleasing.
Special function: The coating can adjust the conduction characteristics of electricity, heat and other energy, resist bacterial absorption, and control the reflection, dispersion and absorption of sound waves.
At present, domestic coating production lines are divided into three stages: manual, semi-manual and automated, which mainly include: pretreatment, electrophoresis, paint, drying and three waste treatment [12].

2.1.2 Development History of Automobile Painting Production Line

At the beginning of the founding of New China, my country's coating technology was the earliest to develop. At that time, we had close ties with the Soviet Union. Many Soviet coating projects were invested and constructed in our country. In the early 1960s, bicycle production in Shanghai and Tianjin had formed two production lines, one was a mechanized production line and the other was an automatic production line. During this period, the main task of my country's coatings industry was anti-corrosion. However, with the rapid development of our country's economy and the rapid development of foreign coating technologies, advanced coating technologies are continuously adopted in China. Among them, electrophoresis and electrostatic spraying technologies have been widely used in the automated coating industry. In the 1980s, due to the introduction of new painting equipment, various spraying methods emerged in endlessly. Currently, electrostatic cup spraying technology has developed very maturely [13], and many automobile bodies are painted using robots.

2.1.3 Process flow of automobile painting production line

The process flow of the coating production line includes pre-treatment, electrophoresis, intermediate coating and surface treatment. Preprocessing: Pretreatment is the primary step in the paint production line, including processes such as rust removal, degreasing, degreasing, degreasing and phosphating to remove various impurities (such as emulsion, sweat stains, grease) and dust on the surface of the workpiece. Among them, phosphating is the key. Rust removal, degreasing, and oil removal are the preliminary preparations for phosphating. Therefore, in production, in addition to the requirements for phosphating quality, the phosphating process should also be listed as the main process [14] .
Electrophoresis: refers to the movement of charged particles in opposite directions under the action of electric field force. Through electrophoresis, electrophoretic paint can be applied to some very hidden places on the surface of objects, such as the gaps in car door handles, which can enhance the anti-corrosion performance of the car. At the same time, the electrophoresis method can increase the utilization rate of paint to 94%, thus reducing the waste of paint resources.
Mid-coat: Mid-coat primer is a commonly used mid-coat primer, while mid-coat primer is a primer used between the primer and the primer. It is usually also called "secondary slurry" or "secondary primer." ". The intermediate coating can improve the adhesion between the primer and the topcoat, improve the plumpness and smoothness of the product, isolate and seal the underlying coating, avoid paint film defects caused by the penetration of the topcoat, and can fill small scratches and pinholes.
Topcoat: Also known as the final coat, it is the last layer in the painting process. It not only makes the car body beautiful, corrosion-resistant and waterproof, but also protects the primer, greatly improving The appearance of the car body [15].

Figure 2-1 Process flow of automobile painting production line

2.2 Development History of Industrial Robots

In the middle of the twentieth century, under the technical background of automation and computer technology, modern mechanical industrial robots have carried out a large amount of work. In 1962, the first industrial robot was born in the United States, which Japan had completed five to ten years earlier. Over the past half century or so, the United States has become one of the most technologically advanced and powerful countries in the world.
The development process of industrial robots is a winding and bumpy road. In the United States, Dai Vol first proposed the concept of industrial robots in 1954 and obtained a patent. The core technology of the present invention is to use servo technology to control the motion of the robotic arm, and technicians perform manual demonstrations, thereby recording and reproducing the motion of the robotic arm. In 1959, the first industrial robot was launched. Since then, Japan has made rapid innovations in robotics technology. At the end of the 20th century, with the continuous development of industrial robot technology, overall and high-level automation of enterprises has gradually taken shape. The first generation of industrial robots refers to robotic arms widely used in industrial production [16].
In 1982, the General Motors industry began to use vision systems, so perception robots became the representative of the second generation of robots. The system has external sensors and can be programmed offline. Autonomous robots are the most representative third-generation robots in the world. Its advantages are planning, perception, and decision-making abilities. In the 1990s, our country has entered a period of transformation, and industrial robots have made new breakthroughs in practical work. In the following years, a variety of industrial robots for spraying, welding, handling, stacking, etc. have been developed and completed. A lot of engineering.

2.3 Overview of paint rate

Paint coating rate, that is, paint utilization rate, refers to the ratio of the amount of paint on the surface of the object being coated to the total amount of paint sprayed by the nozzle during the coating period, or the actual measured film on the surface of the object being coated The ratio of thickness to the total thickness of paint sprayed. When calculating, it usually refers to the percentage of solid matter in the paint that is occupied by the object being painted or the effective part of the object. For the same car in the same environment, it is guaranteed that the average thickness, dry film thickness, effective spray area and coating film dosage are all fixed [17].

2.3.1 Factors affecting spraying method

Air spraying is a traditional spray painting process. It is the most basic and simplest. Its working principle is to spray pressure from the nozzle to generate a negative pressure near the nozzle, so that the paint film in the pipe is pumped out. Due to the rapid diffusion of gas, the paint film becomes mist-like. Therefore, among various spraying methods, air spraying has the lowest paint rate, usually between 30% and 60%, and it will also affect the surrounding areas. The environment produces pollution. Due to the air injection method, it will not only make the filter cotton in the spray room more clogged, but also increase production costs. The following table compares electrostatic spraying, high-pressure auxiliary gas spraying, high-pressure airless spraying, and air spraying [18].
Table 2-1 Comparison of four spraying methods.
High-pressure airless spray is the same as air spray. Compressed air is used as power, and the paint film is pressurized through a plunger pump to release the pressure on the nozzle and fog the coating. change. High-pressure auxiliary gas spray is a kind of high-pressure airless spray and air spray, while high-voltage electrostatic spray forms high-voltage static electricity between the spray gun and the workpiece to be painted, so that the charged paint is sucked to the surface of the workpiece. As can be seen from Table 2-1, due to the different principles of the oil injection process, the painting speed will vary greatly. Among these processes, the air spray process has the lowest painting efficiency, and the high-voltage electrostatic spray process can achieve 70% to 90% paint quality [19].
At present, the high-voltage electrostatic method has become the main technology in the coating industry, and its delivery efficiency is very high, mainly because it can help the coating overcome various resistances, such as air flow and air flow and thrust. At the same time, the use of high-voltage electrostatic spraying technology can save labor and painting costs, shorten operating time, and better absorb paint in the spray painting room and surrounding environment to the surface of the painted body, thus greatly reducing the need to remove paint residues. Cost-effective and uses high-voltage electrostatic spraying.

2.3.2 Factors affecting coatings

Solvent-based coatings generally have high electrical resistance and are almost insulating materials, so no special processing is required to apply electrostatic pressure in a rotary cup spray gun. The resistance of traditional high-voltage electrostatic plating can reach 4 M ohms. While applying high-voltage electrostatic field force to the coating, it can also effectively improve the coating rate. Compared with solvent-based coatings, water-based coatings have extremely low resistance, and leakage will occur on water-soluble coatings when positive charges generated by high-voltage generators are passed through the device [20].

Figure 2-2 The relationship between charging mode and coating rate of paint
Therefore, for water-soluble paint, high-voltage electrostatic spraying requires a special coating mechanical system and isolation. The coating speed is closely related to the development and update of internal charging technology, as shown in the figure below. When using water-soluble coatings for high-voltage electrostatic spraying, their conductive properties are currently the biggest problem, so special electrostatic spray control must be carried out. Using external charging technology, it is a traditional water-soluble coating, which can be achieved through its special external current.

3 Spraying robot color change cleaning and spraying parameter analysis

3.1 Color changing system of spray painting robot

3.1.1 Hardware composition of color changing system

The spraying system of a spraying robot generally includes a coloring system, a spray paint atomization system, a control system and a paint circulation system. The spray painting system is the key to the spray painting process. The color conversion system of the spray painting robot is composed of multiple components, ensuring that it is suitable for various coatings, such as water-based coatings, solvent coatings, single- and double-component coatings, etc. The color changing system includes: paint input pipe module, compressed air module, color changing valve module, and part of the external cleaning box. Usually, the color changing device is installed on the inside of the arm of the painting robot, next to the sprayer.
In Figure 3-1, the color conversion system is shown. A represents the paint input pipe assembly, B represents the compressed air assembly, C represents the paint pipe return assembly, D represents the micro valve assembly, and E represents the common part of the color mixing valve assembly. Among them, the microvalve component is the main component of the color mixing system, used to control the direction of the paint. Its function is similar to the switch function, including thimbles, springs, etc. When spraying, the micro valve must be closed, and after the paint enters pipeline A, it will flow from pipeline C to the circulation pipeline area. After the paint is sprayed once, the common pipe of the replacement valve group must be blown out with high-pressure gas and solvent.

3.1.2 Color changing principle of spray painting robot

In the color changing system, each component has its own role and function. The micro valve is opened by compressed air, and the spring can close it. There will be a display switch handle on the top of the valve to indicate when the valve is open. Each valve has its own paint pipe for back-coating. Usually, a compressed air module is placed above the palette, which can compress gas and purify solvents to a certain extent. There is a valve inside it that allows gas and solvent to flow alternately, allowing the solvent to mix with the gas. This ensures that utility pipes, paint pipes, etc. are cleaned during the color change cycle. This module can reduce the programming of changing colors.
Figure 3-1 Structure diagram of the color changing system
. At the same time, it is a separate module and does not need to be connected to external power or directly connected to the pipeline. When the spray robot processes the coated workpiece with a specific color, if the solenoid valve at B receives an opening signal, the two three-way valves will be opened, and the compressed air will flow in from port B. At this time, the spring will be compressed The air is compressed in the opposite direction, the micro valve D is opened, and the paint flows from the input component A into the common passage, and is then delivered to the gear pump through the regulator. The gear pump can move on the space volume generated between the pump body and the gear mesh, thereby realizing the transportation of paint. The paint entering the gear pump is atomized and moves toward the coated workpiece under the action of static pressure and the centrifugal force of the rotating cup. Under the control of the molding air, the spray amplitude of the paint is maintained at the required target value. .

3.1.3 Cleaning principle of spraying robot

At present, in the face of spray painting operations of various colors, a single color spray painting method can no longer meet the requirements. Therefore, most of the current spray painting robots adopt automatic color changing devices, which have two functions: automatic cleaning and cleaning. Usually, the replacement device is located close to the nozzle, which can shorten the color change time and increase work efficiency. Through the main system, a variety of color selections for the objects to be sprayed are realized, and automatic color adjustment is realized through the spray robot itself. After the spray robot completes painting, it sends the rotating cup into the cleaning box (also known as the gun washing box), and sprays solvent and air into the rotating cup sprayer to remove paint residue on its surface, thereby ensuring the internal and external parts of the rotating cup sprayer. Clean the surface to prevent paint residue from splashing onto the surface of the workpiece being painted. The cleaning box is shown in the picture below. It needs to be filled after cleaning. Generally speaking, when there are five cars of the same color or one car of different colors, the pipes must be cleaned and filled to prevent the paint from sticking in the pipes or turning into paint slag after drying and clogging the rotating cup. The outlet leads to "color cross-fertilization", "particles", etc. The cleaning of the entire spray robot consists of two main links: cleaning and crown circulation pipes, and cleaning and filling the rotating cup.
(1) Cleaning of the circulating pipe of the spraying robot
The cleaning of the circulating pipe of the spraying robot consists of three links: the gear pump of the color changing system, the common cavity, the cleaning of the common pipe between the color changer and the rotary cup. When cleaning circulating pipelines, open relevant valves, such as gear pump bypass valves and solvent valves, so that compressed air and cleaning solvents can circulate alternately in the pipelines to achieve the purpose of cleaning, and at the same time, it can also prevent the former paint from damaging the paint. Color causes pollution.
When the pipeline is cleaned, the cleaning solvent must be returned to the waste paint recovery tank through the drainage pipe. At this time, the micro valve (such as TPVD, TRIGDUMP) on the waste water discharge pipeline is open. The flow rate of the gear pump is constant. In order to speed up the flow of paint or solvent and speed up cleaning and filling, the bypass valve of the gear pump must be opened.
(2) Cleaning of the rotating cup of the spray robot
The nozzle is the core part of the rotating cup and an important target for cleaning the rotating cup. When cleaning the rotating cup, the cleaning solvent can directly clean the inside and outside without passing through public pipes. When cleaning, multiple micro valves (such as P1, TRIG EB, TRIG, etc.) must be opened, and the overshoot control of the regulator must be started during this cleaning period to ensure that the hydraulic regulator in the rotary cup nozzle is maintained in the fully open state . After cleaning, there is no need to pour it back and it can be discharged directly. After cleaning the rotating cup and pipes, they need to be blown clean with compressed air. During each cleaning, only the corresponding micro valve needs to be opened, other micro valves must be closed, and the cleaning and purification time settings must be adapted to the opening time of the micro valve. The usual time setting is within 0.2 seconds.
(3) The color filling of the spraying robot
plays a role in cleaning the circulation pipe and the rotating cup nozzle, and then injects the required paint into the valve main pipe of the spraying line and nozzle. The filling of the paint robot loop pipe is to apply the paint to be sprayed on the common channel E in the color mixing system and the common channel between the color mixing system and the rotary cup nozzle. When filling pipelines, it is necessary to open the corresponding valves. The filling of the rotating cup is to fill the nozzle with the paint to be applied. Grouting not only needs to remove dirt from the rotary cup and pipes during the painting process, but also must activate the trigger valve and adjust the override control and various color valves in the machine to minimize the amount of paint discharged from the nozzle. This allows for a spray of paint suitable for your next car. The filling process usually only takes place when the rotary cup sprayer is in the clean tank and the nozzle discharge valve is activated, thus creating a parallel discharge channel to the painting system.
(4) Spraying machine color change cleaning procedure
The cleaning of the spraying robot is to clean the spray system, use the paint to be colored next, and clean the oil pipe and rotating cup nozzle. Its structure is shown in the figure below. The color changes of each spray painting robot are composed of a grid. Each color change represents a different module and valve. The requirements for each color are also different. Therefore, depending on the actual situation, you can Choose the right color. The main working components of this color changing system are several pneumatic ultra-micro valves 9. By controlling the working sequence of the ultra-micro valves and then operating them together with the spraying robot, the required color change is achieved.
When the Trig is activated, the liquid in the container is delivered to the Versa Bell's syringe, allowing it to be sprayed and discharged. After starting the CE, the selected liquid valve will be opened. Once the pPE is activated, the paint to be applied flows to the trigger valve. The cleaning control system starts after starting pAIR and is usually used for cleaning and cleaning. After starting the pCC, the converter's outlet valve is activated, allowing gases and solvents to be discharged from the converter. After pSEAL is started, the controlled air flow drives the sealing valve, which includes the air valve. There is usually an airtight layer behind the rotary cup. When there is paint flowing through at high speed, this valve can prevent the gap after rotation from entering the paint.

Figure 3-3 Color changing program diagram
When the painting robot changes colors, three different color methods need to be used: push out, clean, and fill. These three methods are available in the Color drop-down menu. Priming: This process is carried out before changing the paint and its purpose is to deliver the remaining paint to the rotating cup nozzle. Close the color change valve, open the clean air valve, and save paint by utilizing the remaining paint in the pipeline and the manifold coating of the replacement valve. Typically, layout programs will clear the map system before changing paint colors. Cleaning: In the sprayer, coating tube, color change valve main pipe and cleaning box, the cleaning solvent and the cleaning gas are exchanged alternately to prevent the subsequent coating from being contaminated by the previous coating. In order to keep the flow regulator of the rotary cup sprayer in a fully open state, the cover function of the regulator must also be turned on at the same time. Filling properties have been discussed before.

3.2 Design of grouping software before painting

Before changing the color, information such as the car body model, color to be painted, and paint type are stored in a carrier that works with the car body (see figure below). When the coated car body passes through the conveyor belt and is about to arrive at the paint room, it will first pass through a transition roller, and then the order of the vehicles is adjusted as needed to combine various colors and types of car bodies. In the paint industry, it is called " Grouping before lacquering”.
Pre-painting not only allows the recombination of car bodies of different colors, avoiding the frequent replacement of paint pipes, but also allows the slider to have a slower conveying speed before the car body reaches the spray booth. Since the running speed of the paint chain is usually very low, the conveyor chain in the paint shop is much faster than the conveyor speed of the paint chain. Therefore, the conveying speed is 6 meters/minute.

Figure 3-5 Pre-painting grouping configuration diagram
As can be seen from the above figure, the pre-painting of the system is done after the intermediate coating is completed, and then the color paint is applied. This system has a total of four painting processes, each of which The painting process will be based on different vehicle models and color requirements. Through four lanes, the same vehicles and colors can be classified. In this way, during automatic spraying, the frequent flushing of the nozzle can be reduced, thereby greatly improving the efficiency of spraying. work efficiency.

4 Offline programming technology and Robot Studio workstation simulation

4.1 Offline programming system

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Figure 4-1 Grouping configuration diagram before painting

4.2 Offline programming design solution

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4.2.1 Development platform

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4.2.2 Design plan

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4.2.3 Design plan

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4.3 Workstation layout design

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4.4 Creation of workpiece coordinate system and tool coordinate system

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4.4.1 Creation of workpiece coordinate system

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4.4.2 Creation of tool coordinate system

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4.5 Spray model profiling

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5 Summary

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Appendix (core code)