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Welding robot promotes the development of welding automation

Source of the article:admin popularity:Time of publication:2021-1-3

In recent years, Chinese industry is undergoing a "robot" revolution, especially in the field of arc welding. After 2005, robots have increased at an average rate of 130% per year. This paper introduces the advantages of welding robot in automation production, the development of welding robot system, the problems and solutions of welding robot automation application, and the application example of welding robot in industry.
1. Advantages of welding robot in automatic production
Robots have been used in welding field since its birth. According to statistics, by the end of 2007, the total number of welding robots in service in the world has reached 40 million. As an advanced welding equipment, welding robot has been widely used, and it is an important symbol of the welding industry entering the automation era in China.
With the progress of science and technology, people have higher and higher requirements for welding quality. Automation production requires reducing manpower, improving product consistency, improving product quality, more suitable for mass production, reducing production cost and improving production efficiency. However, it is difficult to maintain the stability and consistency of welding work for a long time because of the influence of objective and subjective factors such as technical level, fatigue degree, responsibility, physiological limit and so on. Moreover, due to the poor working conditions of welding, the number of people willing to do manual welding is decreasing, and skilled technical workers are in short supply. It can be said that welding robot largely meets the requirements of welding automation. The advantages of automatic production can be summarized as follows:
(1) Stability and improvement of welding quality to ensure its uniformity. Welding parameters such as welding current, voltage, welding speed and dry elongation have decisive effect on welding results. When robot welding is adopted, the welding parameters of each weld are constant, and the quality of welding is less affected by human factors, which reduces the requirements of workers' operation technology, so the welding quality is stable. When manual welding, welding speed and dry elongation are all changing, so it is difficult to achieve the homogeneity of quality.
(2) Improved working conditions. Robot welding is used, workers only need to load and unload the workpiece, away from welding arc, bright fog and splash. For spot welding, workers do not need to carry heavy hand welding tongs, so that workers can be free from high-intensity manual labor.
(3) Improve labor productivity. The robot can be produced continuously for 24 hours. With the application of high speed and high efficiency welding technology, robot welding is adopted, and the efficiency is improved more obviously.
(4) Product cycle is clear, easy to control product output. The production rhythm of robot is the same, so the production plan is very clear.
(5) Shorten the cycle of product transformation and replacement, and reduce the corresponding equipment investment. It can realize the welding automation of small batch products. The difference between robot and special machine is that it can adapt to the production of different workpiece by modifying the program.
2. Development of welding robot system
The development of electronic technology, computer technology, numerical control and robot technology provides favorable conditions for welding process automation, and has penetrated into various fields of welding. Strictly speaking, welding robot is a welding robot system or workstation, including robot body, robot control cabinet, welding machine system, wire feeding unit, positioner, fixture and other parts. There are three types of typical welding robot system: welding robot workstation, welding robot production line and welding machine. Welding robot workstation is generally suitable for medium and small batch production. The welding seam of the welder can be short and many, and the shape is complex; the welding robot production line is especially suitable for the use of many products and few quantity in each batch; the welding machine is suitable for large batch and slow modification products, and it is also suitable for the workpiece with small number of welds and long weld and regular shape . Which type of automatic welding production form should be selected according to the actual situation of the enterprise.
In recent years, the technology of arc welding inverter has become mature. Most of the special arc welding inverter for robot is IGBT arc welding inverter controlled by single chip microcomputer. It is equipped with fine waveform control and fuzzy control technology. The working frequency is 20-50khz, which can reach 220khz. The welding system has excellent dynamic characteristics, and is suitable for robot automation and intelligent welding. The development of arc welding power is moving towards the digital direction. The development direction of welding power supply for welding robot is to adopt the full digital welding machine. The welding power supply is characterized by stable welding parameters, little influence by network voltage fluctuation, temperature rise, aging of components and other factors, high repeatability, stable welding quality and good forming. In addition, DSP has fast response speed. The output of inverter power can be precisely controlled according to the command of the main control system (given value), so that it can output a variety of current waveforms and arc voltage The function of high speed and stable adjustment can meet the requirements of various welding methods for power supply.
Cao Lezhong mentioned the transformation of the positioner in the article "the technical transformation of welding robot of romat76aw". The welding range of single robot in the direction of length is only 6800mm, which can not complete the welding of bogie side beam of SS9 electric locomotive. The positioner is used for rotating displacement of welding parts. The model of the positioner is wpr25000n, the head frame is fixed, the tail frame can move along the guide rail, bearing 2.5t, and can be rotated to any angle. The guide rail of the positioner is lengthened by 1.6m, which requires good rail docking. After the guide rail is lengthened, the distance between the head frame and tail frame of the positioner is 9. the eighth axis (rotating shaft of the positioner) drive motor (formerly DC servo motor) of the positioner is updated, 3M. The driving mode is AC servo drive, which ensures the workpiece moves smoothly and without channeling during the process of displacement, thus improving the welding performance of the weld in the ship position.
3. The problems and solutions of automatic application of welding robot
At present, the welding robot in application is still "teaching reproduction type", its welding path and process parameters are preset, and the consistency of working conditions is very strict, and the function of sensing feedback and real-time adjustment of external information is not available in the welding process. However, the change of environment and condition in the actual welding process is inevitable. For example, the welding workpiece processing and assembly errors cause the joint position, weld gap and size dispersion, the difference between teaching track and actual weld, thermal deformation, penetration and weld shape instability in the welding process, etc. all cause the fluctuation of welding quality and lead to the production of welding defects. In order to overcome the influence of various uncertain factors on the quality of precision welding, it is urgent to adopt information feedback and intelligent control to improve the adaptability or intelligence level of the welding robot, so that it can realize the initial welding position recognition and independent guidance, real-time weld deviation correction and tracking, dynamic feature information acquisition of welding pool, adaptive adjustment of process parameters and The real-time control of weld forming, that is, the autonomous intelligent control of welding process of robot is realized, which makes up for the shortage of welding robot in automatic welding.
Chen Shanben and others used artificial intelligence technology to simulate the function of welder observation, judgment and operation. The key technology of welding robot based on visual information sensor for initial welding position recognition and autonomous guidance, weld tracking, dynamic process of molten pool and intelligent control of weld forming were studied. Laiwr (autonomous intelligent welding in local environment) was developed The integrated system of local autonomous intelligent welding robot is connected. The key technology of the system is applied to the welding manufacture of important structural parts of space equipment. In order to realize the optimal management and coordination control of many hardware components and functional software of laiwr system, the autonomous control intelligent function of robot system can be realized.
With the development of robot research and the development of robot field, robot simulation system plays an important role in this field as a safe, reliable and flexible tool for robot design and research. The paper discusses the development of 6R robot simulation system based on the 6R welding robot. The process of the interaction between the simulation interface and the system graphics is given. The dynamic simulation of multi DOF and multi joint robot is realized, and the purpose of researching multi DOF and multi joint robot is achieved.
In this paper, the fuzzy expert control system is designed to solve the problems of high heat accumulation and various defects in constant parameter welding of aluminum alloy. The image of the molten pool and the corresponding image processing software are obtained by CCD to calculate the size of the melting width. Then the fuzzy controller controls the welding heat input. The expert system is responsible for the pulse parameter matching, so as to maintain the same width, which ensures the stability of welding quality and adapts to the requirements of automatic production.
Other measures include the modification of the peripheral structure of welding robot, welding process transformation, and so on. In the field construction of steel structure, the shape of structural parts is complex. Besides the conventional round and square workpieces, there are discontinuous, oval, gradual shape workpieces, thick wall and large workpieces. It is difficult to fundamentally solve the automatic welding on site, give full play to the utilization rate of welding robot and improve welding efficiency. By summarizing the field welding practice of bird nest and a large number of welding engineering practices, we developed rhc-2 and rhc-3 series flexible track welding robots. The straight guide, circular guide and flexible guide rail can be used to realize the full position welding of various complex surfaces. The function control procedures such as on-line weld track teaching, online all position welding parameter control, off-line welding parameter setting and so on are designed And develop an independent learning open expert system, which can adapt to the track tracking of irregular weld, and realize the automatic welding of multi-layer multi pass welding and full position welding.
4. Application of welding robot in industry
The main applications of arc welding robot industry are in the shipbuilding, automobile parts, motorcycles, bicycles, sheet metal and other industries. In addition, the application of arc welding robot is also expanding in the medium and thick plate industry which is rich in engineering machinery.
Welding automation is the key to the progress and upgrading of the shipbuilding industry. After more than ten years of hard and unremitting efforts, China Shipbuilding automatic welding technology has made great progress and fruitful results. As we all know, shipbuilding welding technology is the key technology of modern shipbuilding. In the hull construction, welding hours account for 30% - 40% of the total construction time of the ship, and welding cost accounts for 30% - 50% of the total cost of hull construction. The welding quality of ship is an important index to evaluate the ship quality. The welding efficiency directly affects the shipbuilding cycle and the cost of ship construction. Therefore, welding automation will be the key to the progress and upgrading of the shipbuilding industry, and it will become more and more obvious with the development of welding technology.

Keywords of this article:Welding,robot,promotes,the,dev