China's development of industrial robots was later in the United States and Japan, starting in the 1970s. In the early days, it was a spontaneous study of universities and research institutes. By the mid-1980s, no industrial robot was available nationwide. In foreign countries, industrial robots have become a very mature industrial product and have been widely used in the automotive industry. In view of the domestic and international situation at the time, the national “seventh five-year†research plan included the development of industrial robots in the plan, and the industrial robots were tackled, especially the application as an important part of the assessment, so that the robot technology and users were closely integrated. Get up, so that Chinese robots are aiming at the practical direction in the initial stage.
At the same time, in 1986, the development of robots was included in the national "863" high-tech plan. On the occasion of the fifth anniversary of the implementation of the national "863" plan, Comrade Deng Xiaoping put forward the goal of "developing high technology and realizing industrialization." Under the impetus of the development of the domestic market and the technical reserve of robot technology research, the 863 subject expert group adjusted and extended the main direction in a timely manner, and made industrial robots and application engineering one of the research and development priorities. The development policy of driving key technologies and basic research will be included in the national “Eighth Five-Year Plan†and “Ninth Five-Year Planâ€. After more than ten years of continuous efforts, with the organization and support of the country, China's welding robot research has made significant progress in basic technology, control technology, key components, etc., and has entered the stage of use, forming spot welding, The arc welding robot series can realize small batch production.
Application status of welding robots in China
The application of welding robots in China is mainly concentrated in several major industries such as automobiles, motorcycles, construction machinery and railway locomotives. The car is the largest user of the welding robot and the earliest user. As early as the end of the 1970s, the Cartesian coordinate manipulator developed by Shanghai Electric Welder Factory and Shanghai Electric Tool Research Institute was successfully applied to the welding of Shanghai brand car chassis. "FAW" is the earliest company to introduce welding robots in China. Since 1984, it has introduced three spot welding robots from KUKA for the welding of the body of the "Red Flag" sedan and the welding of the "Jiefang" body cap. In 1986, the welding robot was successfully applied to the welding of the front wall assembly. In 1988, the total welding line of the robot body was developed.
In the late 1980s and early 1990s, Volkswagen AG established a joint venture car factory with Shanghai and FAW to produce cars. Although it is a second-hand equipment from abroad, its welding automation and equipment level make us realize the huge gap with foreign countries. Subsequently, Erqi introduced welding robots in trucks and light vehicles. It can be said that since the 1990s, the introduction of technology and the introduction of production equipment and process equipment have enabled China's automobile manufacturing level to be improved from the original workshop-style production to large-scale production, and at the same time, foreign welding robots have entered China in large numbers. As the rapid development of infrastructure construction in China has driven the prosperity of the construction machinery industry, the construction machinery industry has also become one of the industries that cited welding robots earlier. In recent years, due to the rapid development of China's economy, the large demand for energy, and the energy-related manufacturing industry have also begun to seek automated welding technology, welding robots have gradually emerged. Due to the increasing demand for freight, passenger and urban subways in China, and the demand for train speed increase, the demand for robots has been growing steadily. According to statistics in 2001, there are 1040 welding robots in various types in the country, and welding robots in automobile manufacturing and auto parts manufacturing enterprises account for 76% of all welding robots. In the automotive industry, the ratio of spot welding robots to arc welding robots is 3:2. Most other industries are mainly arc welding robots, mainly distributed in construction machinery (10%), motorcycles (6%), and railway vehicles (4). %), boiler (1%) and other industries. Welding robots are also mainly distributed in several major automobile manufacturers in China. It can be seen from Figure 1 that the distribution of welding robots in China is not uniform and not extensive enough.
In the 21st century, due to the continuous influx of foreign auto giants and the rapid development of the auto industry, the number of robotic installations in China's auto industry has increased rapidly. In 2002, 2003 and 2004, the number of nearly 1,000 units increased every year. It is estimated that the number of installations of welding robots in China is currently around 4,000. The proportion of welding robots in the automotive industry will further increase.
At present, the robots used in China are mainly divided into Japanese, European and domestic. Japanese companies mainly include Yaskawa, OTC, Panasonic, FANUC, Fujitsu, Kawasaki and other companies. The European system mainly includes Germany's KUKA, CLOOS, Sweden's ABB, Italy's COMAU and Austria's IGM. Domestic robots are mainly products of Shenyang Xinsong Robotics Co., Ltd.
At present, although there are already series of welding robots with independent intellectual property rights in China, they cannot be mass-produced and form scale. There are several main reasons:
There is no advantage in domestic robot prices. In the past 10 years, the price of imported robots has been greatly reduced, from $70,000 to $30,000 to $30,000, making it difficult for ordinary industrial robots made in China to compete with them. In particular, in the early stage of developing robots in China, there was no simultaneous development of the corresponding parts and components industry, such as servo motors, reducers, etc., which required the import, which made it difficult to reduce the price, so the cost of robot production could not be reduced. The level of welding equipment in China still exists very much abroad. The big gap, this also indirectly affects the development of domestic robots. For the car's largest user, the car body-in-white manufacturer, almost all of the equipment has been imported from abroad, and domestic robots can hardly find a stage for performance.
We should admit that domestic robots still have a certain gap with foreign companies in terms of control level and reliability. Foreign industrial robots are very mature industrial products. After more than 30 years of development, they are constantly improving and improving in actual production, while China is in a single-piece and small-batch production state.
Domestic robot manufacturers are in their early childhood and need government policy and funding support. The welding robot is a mechatronics high-tech product. It is not enough to rely solely on the company's own capabilities. It requires the government to give certain policies and financial support to robot manufacturers and enterprises using domestic robot systems to accelerate the development of domestic robots.
The significance of applying welding robot
The reason why welding robots can occupy more than 40% of the total industrial robots is related to the special industry of welding. Welding as an industrial "tailor" is a very important processing method in industrial production, and at the same time due to welding fumes, arcs, metal splashes. The existence of the welding environment is very bad, and the quality of the welding has a decisive influence on the quality of the product. In summary, the use of welding robots has the following main meanings:
(1) Stabilize and improve the quality of welding to ensure its uniformity. Welding parameters such as welding current, voltage, welding speed and weld dry elongation determine the welding results. When using robot welding, the welding parameters for each weld are constant, the weld quality is less affected by human factors, and the requirements for the worker's operating technology are reduced, so the welding quality is stable. In the case of manual welding, the welding speed and the dry elongation are all changed, so that it is difficult to achieve uniformity of quality.
(2) Improve the working conditions of workers. Robotic welding workers are only used to load and unload workpieces, away from welding arcs, smoke and splashes. For spot welding, workers no longer carry heavy manual welding tongs, freeing workers from high-intensity manual labor.
(3) Improve labor productivity. The robot is not fatigued and can be continuously produced 24 hours a day. In addition, with the application of high-speed and high-efficiency welding technology, robot welding is used, and the efficiency is more obvious.
(4) The product cycle is clear and it is easy to control the output of the product. The production cycle of the robot is fixed, so the production plan is very clear.
(5) It can shorten the cycle of product modification and reduce the corresponding equipment investment. It can realize welding automation of small batch products. The biggest difference between a robot and a special plane is that he can modify the program to adapt to the production of different workpieces.
China Welding Robot Application Engineering
The welding robot application technology is a fusion of robot technology, welding technology and system engineering technology. Whether the welding robot can be applied in actual production and exert its superior characteristics depends on the degree of integration of the above technologies. After nearly 10 years of hard work, China has accumulated rich experience in the design of robotic welding fixtures. The robot peripheral equipment has achieved standardization and has the capacity to produce more than 300 sets of welding robot workstations per year. It can be said that domestic system integrators have the ability to compete with foreign system integrators in the design and development of robotic workstations and simple soldering lines. In recent years, a large number of robotic welding systems have been provided for domestic auto parts and other enterprises. But another serious fact is that we do not have the ability to manufacture high-level robotic welding lines. The body welding lines of several major automobile factories in China are designed and manufactured by foreign robot system integrators.
As the largest user of welding robots, it is estimated that the annual output of China's automobiles will reach 10 million vehicles in the next 10 years. The current welding equipment can not meet the production requirements, the demand for welding equipment will increase greatly, and the welding production line requirements will be more automated. Flexible to meet the production requirements of multiple varieties and small batches, robots will be widely used in welding production lines. How to seize opportunities in China's robotic system integrators is an important issue to be solved at present, and on the other hand, it determines the fate of domestic welding robots.
(1) Implementing corporate alliances. Robotic system integrators and automobile manufacturers jointly digest and absorb foreign automotive welding lines.
(2) Establish your own welding equipment design standards and digital models to improve design level and efficiency.
(3) Strengthen the cultivation of talents. The robot welding production line is a complex system engineering involving mechanical, electrical, logistics transmission, computer, automobile design and manufacturing, robotics, welding technology and many other disciplines. However, there is no systematic training institution in this field in China.
(4) Strengthen cooperation with foreign companies and improve their design level through cooperative learning.
The latest application technology of welding robot
(1) TCP (tool center point tool center point) automatic zero calibration technology
The center point of the welding robot's tool is the end of the welding wire of the welding torch, so the zero accuracy of the TCP directly affects the stability of the welding quality. However, in actual production, unpredictable factors such as collision between the welding gun and the jig will inevitably lead to deviation of the TCP position. The usual practice is to manually perform robot TCP calibration, but generally the entire process takes 30 minutes to complete, affecting production efficiency. TCP automatic zero calibration is a new technology used in robot welding. Its hardware consists of a trapezoidal fixed support and a set of laser sensors. When the torch passes through the TCP holder in different postures, the laser sensor transmits the recorded data to the CPU for comparison and calculation with the initial set value. When the TCP deviates, the robot automatically runs the zero calibration program, automatically adjusts the angle of each axis, and restores the TCP zero in the least amount of time.
(2) Double wire welding technology
In recent years, due to the rapid development of China's automobile, container, rolling stock, construction machinery and other industries, there is an increasing demand for high-speed welding and high-fusion efficiency welding. Double wire welding is a high-speed and high-efficiency welding method developed in recent years. When welding thin plates, the welding speed can be significantly improved, reaching 3~6m/min, and the welding efficiency can be improved when welding thick plates. In addition to high speed and high efficiency, twin wire welding has other process features: low heat input when welding efficiency increases, small heat affected zone, small welding deformation, low welding porosity.
Due to the very high welding speed, it is especially suitable for robot welding, so it can be said that the application of robots has also promoted the development of this advanced welding technology.
At present, there are two main ways of double wire welding: one is the Twin arc method, and the other is the Tandem method. The basic components of the welding equipment are similar, consisting of two welding power supplies, two wire feeders and a common cable for sending twin wires. In order to prevent mutual interference of two arcs in the same phase, pulse MIG/pulse MAG welding is often used, and two arcs are alternately burned. In this way, a coordinated controller is required to ensure that the output current waveforms of the two power supplies are 180° out of phase. When the welding parameters are set to the optimum, the pulsed arc can obtain a short-circuit-free, almost spatter-free transition process, truly "one pulse transitions one droplet", each droplet is almost exactly the same size, its size is Determined by the arc power. The main manufacturers of the Twin arc method are SKS, Benzel and Nimark in Germany and Miller in the United States. Manufacturers of the Tandem method include Cloos from Germany, Fronius from Austria, and Lincoln from the United States. According to the German company Cloos, when welding 2~3mm thin plates by Tandem method, the welding speed can reach 6m/min. When welding thick plates of 8mm or more, the welding efficiency can reach 24Kg/h.
(3) Laser/arc hybrid welding technology
The laser/arc hybrid welding technology is a combination of laser welding and gas shielded welding, and two welding heat sources simultaneously act on one weld pool. The research of this technology first appeared in the late 1970s, but due to the expensive price of lasers, its application in the industry has been limited. With the improvement of the performance of lasers and arc welding equipment, as well as the continuous reduction of laser prices, and in order to meet the urgent needs of production, laser/arc hybrid welding technology has become one of the most important research topics in the field of welding in recent years.
Laser/arc hybrid welding technology is available in a variety of combinations including laser/TIG, laser/MAG and laser/MAG. The reason why laser/arc hybrid welding technology is favored is that it has its own short heat source and has a "synergy effect" of 1+1>2 or more. Compared with laser welding, the requirements for assembly clearance are reduced, thus reducing the cost of preparation of the workpiece before welding; and because the filler wire eliminates the inherent defects in laser welding, the weld is more dense. Compared with arc welding, the stability and power density of the arc are improved, the welding speed and the weld penetration are increased, the heat affected zone is reduced, the deformation of the workpiece is reduced, and the defects of melting failure at the time of arcing are eliminated. In this regard, it is particularly suitable for the welding of aluminum and its alloys.
Laser/arc hybrid welding technology is a major development in laser welding. Welding the same thickness of material can reduce the laser power by about half, thus greatly reducing the investment cost of the enterprise. The development of this technology will play an important role in promoting the popularization of laser welding. effect.
(4) Application of servo welding tongs technology in automotive welding process
Servo robotic welding tongs are a new type of welding tongs that use servo motors instead of compressed air as a power source. It has the following advantages:
1 Improve the surface quality of the body The servo welding tongs use a servo motor. The speed of the electrode can be accurately adjusted to a low speed at high speed before touching the workpiece. Thus, the soft contact of the electrode to the workpiece can be formed, and the impact of the electrode can be reduced. The resulting indentation, which also reduces the amount of wear on the surface of the rear body, improves the quality of the body. Moreover, the application of servo control technology can digitally control and manage the welding parameters, which can ensure the optimal welding parameter data and ensure the welding quality.
2 Improve the working environment Because the electrodes are in soft contact with the workpiece, the impact noise can be reduced, and the exhaust noise caused by the use of the pneumatic welding tongs will not occur. Improve the working environment on site.
3 High production efficiency The servo opening action of the servo welding tongs is automatically controlled by the robot. Compared with pneumatic welding tongs, the servo welding tongs can be controlled to the shortest speed, shorten the production cycle and improve production efficiency.
At present, from the perspective of investment, the purchase of servo welding tongs equipment is relatively high, so servo welding tongs cannot be widely used. However, considering the advantages of the servo welding tongs, such as the soft contact of the servo welding tongs, the impact on the workpiece can be reduced, so that the number of welding clamp clamping mechanisms can be relatively reduced, the cost of the clamp can be reduced, and the overall production line can be reduced. The investment amount, servo welding tongs still have a wide application space. Therefore, with the development, servo welding tongs will be more and more applied to the production line.
The research, development and application of industrial robot technology have strongly promoted the advancement of industrial technology in the world. In particular, welding robots play an extremely important role in high-quality and efficient welding production. With the fiercer international competition after China's accession to the WTO, the demand for industrial robots will become larger and larger. China's industrial robot industry will face new development opportunities and challenges from abroad. We must seize this opportunity and meet the challenges. China is struggling to be among the top powers of robots.
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