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[technology application] Application of robots in body welding production line

according to statistics, more than half of the industrial robots produced by domestic manufacturers in recent years are provided to the automotive industry. At present, industrial robot technology has been widely used in manufacturing industry in the world, and has been extended from traditional manufacturing to other manufacturing industries. However, the automotive industry is still the main application field of industrial robots Absrtact]: This paper mainly analyzes the role of robots in the body welding production line and the main problems existing in its application. Through the analysis of the application of industrial robots at home and abroad, it is known that industrial robots play an important role in the development of automobile industry, especially in the production of body welding; At present, there are still many problems in the application of robots in body welding production. It is expected that industrial robots will play an increasingly prominent role in the automotive industry, and the problems existing in their application will be gradually solved

[Key words]: industrial robot; Welding robot; Welding production line

1 introduction

according to the statistical data of China Automobile Industry Association, since 2000, the average annual growth rate of China's automobile production and sales has exceeded 20%, far higher than the global average growth rate; Moreover, the proportion of annual production in the global automobile production continues to rise. In 2009, China's automobile production and sales exceeded that of the United States, becoming the first country in the global automobile industry; According to the forecast, China's automobile consumption market will still grow at a relatively fast rate

the growth of the automotive market has put forward higher requirements for automotive production technology, and will continue to participate in relevant discussions, giving birth to the in-depth and extensive application of industrial robots in the automotive manufacturing industry. According to statistics, in recent years, more than half of the industrial robots produced by domestic manufacturers are provided to the automotive industry. At present, industrial robot technology has been widely used in manufacturing industry in the world, and has been extended from traditional manufacturing to other manufacturing industries. However, the automotive industry is still the main application field of industrial robots. It is understood that 60% of the industrial robots in the United States are used in automobile production, 37% of the total industrial robots used in the automobile industry in the world, and about 24% of the industrial robots used in auto parts

using industrial robot technology in the production of automobile industry can not only save manpower, reduce costs, improve equipment utilization, improve product quality and output, but also ensure workers' safety, improve working conditions, reduce labor intensity, reduce personnel risks, and improve work efficiency

2 the role of robots in the body welding production line

industrial robots are widely used in the four major production processes of stamping, welding, painting and final assembly in automobile production. The specific applications in the automobile body welding production line mainly include: spot welding, arc welding, transportation, assembly, detection, etc. Industrial robots have become the main automation tools with flexible manufacturing systems and computer integrated manufacturing systems. In developed countries, complete sets of equipment for industrial robot automation production lines have become the mainstream and future development direction of automation equipment

2.1 workpiece welding

workpiece welding is the largest application field of industrial robots at present. As the automobile manufacturing industry puts forward higher and higher requirements for the welding accuracy and speed of many components, ordinary workers are not competent for this job; In addition, sparks and smoke during welding cause harm to human body. Therefore, the complete automation of welding process has become an important research topic, among which the most important is to apply welding robots. Now in industrial production, all kinds of welding processes and processes can be implemented by industrial robots, instead of using workers to work in the actual harsh welding environment. Robots are most widely used in the process of spot welding and arc welding, and their application in other welding processes is still in the initial or exploratory stage

2.2 workpiece clamping

in the field of automobile manufacturing, robots are widely used not only in the welding process, but also in workpiece clamping and positioning. In the welding workshop that realizes the welding production of automobile body, in order to realize the high-quality welding of the body workpiece, it is necessary to accurately control the welding process. On the one hand, it is required that the welding robot accurately control the posture and motion trajectory of the welding tongs, on the other hand, it is required that all kinds of fixtures clamp and position the workpiece to be welded. There are many kinds of fixtures, and most of the special fixtures can only be used to realize the positioning of non moving workpieces, but can not realize the positioning of moving workpieces. This can be achieved only by using the clamping robot (a robot that combines industrial robots with small fixtures and has the function of positioning and moving workpieces)

2.3 workpiece handling

in the automobile body welding production workshop, the handling and transfer of materials before welding is a very cumbersome task, most of which are completed by special forklifts, but the work of special forklifts is mainly to carry a large number of workpieces from the storage workshop to both sides of the welding production line, The transfer of workpieces from both sides of the production line to the welding fixture on the production line and the transfer of workpieces on the sequential position fixture need to be completed by the flexible industrial robot, which not only improves the production efficiency, but also reduces the labor intensity of workers. In the body welding workshop with a low degree of automation, this work should be completed manually

2.4 weld joint detection

in order to ensure the overall welding quality of the body, it is necessary to inspect the welds of some important parts on the body during the welding process or after the completion of the whole welding work, which is also called weld detection. The complexity of weld position and shape puts forward requirements for the adaptability of testing tools. In the welding production line with a high degree of automation, flexible robots can be used to replace workers to carry special detection devices for weld detection. General mechanical devices are difficult to perform this task like robots

3 role of welding robot

welding robot is an advanced welding equipment developed on the basis of industrial robot, which has independent body, many degrees of freedom of action, flexible program change, high degree of automation and high degree of flexibility. It is an industrial robot engaged in welding (including cutting and spraying). It has multiple functions, high repetition accuracy, high welding quality, large grasping weight, fast movement speed Stable and reliable action

the demand of the automotive industry for product manufacturing in batches, high efficiency and product quality consistency makes the production mode of welding robots widely used in the production and manufacturing process of vehicles that can not meet the quality requirements of the market. The most prominent is the application of welding robots in the production of automotive welding. It can be said that robots are the key to realize the flexibility of automotive welding production lines

at present, typical welding robot systems include welding robot workstation, welding robot production line and special welding machine. Judging from the welding development trend of the automobile industry, the welding production line will develop towards automation and flexible production system. The welding production line is composed of welding equipment, fixture, transmission system and automatic control. In terms of the relationship between the whole and part functions, the overall flexibility of the production line is determined by the flexibility of each component, and the flexibility of welding equipment is the key to determine the flexibility of the welding production line. Due to the high adaptability and many advantages of welding robots to product requirements, the production mode of welding robots has become the best choice for the flexibility of welding equipment. Whether to use welding robot is one of the important symbols of the flexibility of the welding production line

4 the focus problem in the application of welding robots

although welding robots have been widely used in automobile manufacturing, not only the quality of automobile welding has been greatly improved, but also the labor production efficiency of enterprises has been effectively improved. However, at present, there are still many problems to be solved in the application of welding robots in automobile manufacturing. The following is a discussion on several aspects

4.1 teaching problem of welding robot

for teaching and reproducing welding robot, if the welding position shifts during welding, the work of the robot and even the whole production line must be stopped, and the reproduction operation after robot teaching must be carried out. This work now takes up a lot of production time. Such problems need to be further studied and solved

4.2 weld seam tracking problem of welding robot

at present, when the teaching and reproducing arc welding robot used in production is carrying out arc welding, most of the cases are unable to carry out real-time dynamic tracking feedback on the weld, while the actual weld must be slightly different from the sample weld used in teaching, so the weld quality is difficult to be guaranteed. Such problems need to be further studied and solved

4.3 welding robot out of position correction problem

at present, the shaft out of position correction process of most robot products used in the market takes a long time. For the streamlined automatic production line, the economic loss caused by its shutdown is huge. Such problems need to be further studied and solved

4.4 electrical failure of welding robot

the mechanical reliability of the welding robot body is quite high, and the probability of mechanical failure of the body is very small. In contrast, the electrical failure rate of the robot's electrical control system is very high. The most prone parts to failure are the circuit and components of the driver. In addition, the failure frequency of the connector is also quite high. At present, the integration degree of robot control circuit in the world is getting higher and higher, and the continuous progress of control technology has greatly reduced the failure rate of the control part. However, for the welding operations in automobile manufacturing with harsh environment, great operation intensity and large voltage fluctuation, further research and solution are needed

4.5 safe use of welding robots

there are a large number of welding robots on the automobile body welding production line. Sometimes there are multiple welding robots on a welding station. In order to save time and improve efficiency, multiple robots on the same station work in parallel and run at the same time. Accidents of robot to robot collision, robot to other equipment or obstacles due to signal exchange errors occur from time to time. After analysis, it is found that the current robot control system uses external i/o signals to exchange each other's working states when processing signal exchange, and the signal detection is only measured in the form of a point, that is, in a certain motion program line, confirm the existence of a certain exchange signal to determine whether the robot continues the following work, rather than continuously detect other obstacles or robot states in a moving area. In this way, Once the detection process is over and the robot's motion trajectory is wrong or the signal exchange is abnormal, the collision occurs. Such problems need to be further studied and solved

4.6 circuit configuration

at present, welding robots and other automatic equipment are widely used in the automobile body welding production lines of all automobile manufacturers that know and clarify the main development goals, and the automatic and flexible body welding production is realized through off-line programming. But the problem is that hoses and cables fall everywhere at the production site, which is easy to be hooked by staff or equipment entering the site, resulting in failure or accident. From the perspective of integration, this is because the circuit configuration and modeling are not well done. At present, the more feasible solution is to