Welding method of driving track

Welding technology is an important prerequisite to ensure the running quality of railway passenger cars. Only by mastering the essence of welding technology can we ensure the welding quality in the actual welding process, and then promote the all-round development of China's railway passenger car manufacturing industry. Next, I will bring you the welding method of driving trajectory. Welcome to reading.

1, stainless steel and carbon steel car body manufacturing

At the initial stage of the general railway passenger car manufacturing, the steel structure material of the car body is mainly carbon steel, that is, the special weather-resistant steel for railway passenger cars. The welding process adopts covered electrode arc welding and conventional CO2 gas shielded welding. On this basis, some related welding technologies have been developed, such as laser welding and stud welding, which mostly play a role in small batch production. Influenced by the development of production technology, welding technology has made rapid development while manufacturing rail vehicles. Traditional electrode arc welding technology and CO2 gas shielded welding technology can no longer meet the requirements of railway passenger cars, and some brand-new welding technologies are gradually replacing them. However, when applying new technology, its scope and proportion reflect certain differences. From the perspective of stainless steel car body steel structure, the main pressure welding technologies used in bus manufacturing are spot welding technology and seam welding technology [1]; Fusion welding technology includes inert gas shielded welding, stud welding and laser welding. Generally speaking, brazing technology is rarely used for the welding of car body steel structure, and oxygen-acetylene flame welding is only carried out in a few positions and structures. It can be seen that the welding technology used in the manufacture of stainless steel structures can be summarized as follows: spot welding technology is the main welding technology, and seam welding technology can be used to weld some structures; In addition, in terms of fusion welding technology, there are mainly MAG welding technology and TIG welding technology, and on this basis, various welding technologies such as stud welding and laser welding have been developed. From the point of view of stainless steel structure manufacturing, the welding technologies mentioned above, such as MAG welding and TIG welding, have been widely used in manufacturing industry. Due to the structural characteristics of stainless steel, spot welding technology also occupies an irreplaceable position in the manufacture of railway passenger cars. According to the structural and material characteristics of the stainless steel car body, the spot welding device mainly embodies the characteristics of high rigidity of the electrode holder, high welding current and pressure, good quality and stability. In addition, when spot welding technology is applied in practice, the correct welding form must be used according to the welding content. General welding technology can be divided into single-sided double-point technology and double-sided single-point technology according to the electrode holder, and can be divided into portable spot welding machine, mobile spot welding machine and fixed spot welding machine according to the form. At the same time, MAG welding technology, mainly in the form of ordinary DC and pulsed DC, has been widely applied in these two welding fields. The welding power supply of MAG welding technology is mainly digital inverter power supply, which shows great advantages in droplet stability, welding appearance and efficiency.

2, aluminum alloy body manufacturing

There are mainly the following welding technologies for aluminum alloy car bodies: 1) Simple automatic welding. In the manufacture of rail vehicle body structure, the application of aluminum alloy materials first appeared in the 20th century. Because of the limited welding technology at that time, it lacked the support of advanced welding automation equipment. Therefore, at that time, more and more simple automatic welding equipment was developed to weld parts, such as automatic copying welding and automatic rail welding. Although the automatic welding technology developed at that time has been gradually replaced, the significance and ideas left by these welding technologies still support the development of modern welding technology. 2) Automatic welding by special plane. In the welding process of large parts of aluminum alloy car body, it is generally classified from the structural point of view, and the special plane can be divided into gantry plane, cantilever plane and suspension plane. According to the forms of seam tracking, it can be divided into mechanical tracking and laser tracking. As far as wire feeding angle is concerned, there are mainly two forms of single-wire and double-wire welding [2]. The biggest advantage of the special plane lies in its adjustment, operation and maintenance, but it also has some shortcomings: First, the locking mechanism of the special machine gun head is used too frequently, which leads to the decrease of the stability of the equipment. In addition, when welding, it does not show good performance when neutral, so human intervention must be carried out; Secondly, the gun of the special plane lacks stability, and the vibration when walking will lead to the disorder of weld surface texture. 3) Automatic welding of manipulator. When using this welding technology to weld aluminum alloy car body, gantry and cantilever welding technology are generally used to weld large parts, and laser tracking is used to track the weld. Robot welding large parts generally adopts double wires, and early equipment systems mostly adopt single wire welding. The biggest feature of this welding technology is the gun structure, which is very firm and has strong stability in the welding process, ensuring the consistency of welding state and welding quality. However, the robot's automatic welding wire replacement is slow, complicated and difficult to maintain, which also brings challenges to its practical application.

3, bogie frame welding

Generally speaking, the bogie frame of railway passenger cars is mainly made of low alloy steel. Influenced by the development of high-speed train technology in recent years, this material has been gradually improved, and has been widely used in high-speed trains and A-type subways since then. Bogie frame mainly includes traction beam, cross beam, side beam, brake suspension seat and other small parts. The shape of structural welding is influenced by structural complexity and welding performance of materials. Usually, the bogie frame has a certain number of welds and the thickness of the plate is relatively large. Except for some small pieces, most of them are thick plates over 8 mm For the welding of this part of materials, the multi-layer and multi-pass welding process is adopted [3]. At present, single wire (double wire MAG) welding is mostly used to weld the long weld on the outer side of the side beam. For some small arc and circular welds, the automatic welding process of small manipulator is adopted, and the other welds that cannot be welded by manipulator are manual MAG welding. Only the high-quality and high-grade welds that a few manipulators can't complete will be welded by manual TIG. In addition, a few welds with relatively large filling amount are welded by flux-cored covered electrode.