Robot welding arc welding characteristics

2020-05-06

The arc welding process is much more complex than the spot welding process, and the tool center point (TCP), that is, the motion trajectory of the welding wire end, the welding torch attitude, and the welding parameters all require precise control. Therefore, in addition to the general functions described earlier, the arc welding robot must also have some functions suitable for arc welding requirements. 　　Although in theory, a robot with 5 axes can be used for arc welding, for welds with complex shapes, robots with 5 axes will have difficulties. Therefore, unless the weld is relatively simple, a 6-axis robot should be used as much as possible. 　　In addition to the trajectory of the zigzag corner welding or small diameter circular weld welding mentioned in Figure 2 mentioned earlier, the arc welding robot should also have software functions of different swing styles for programming to be selected for swing welding, and the swing at the pause point in each cycle, the robot should also automatically stop moving forward to meet the process requirements. In addition, there should be contact positioning, automatic finding of the starting position of the weld, arc tracking and automatic re-ignition functions.

Welding robot composition structure

2020-05-06

Welding robots mainly include two parts: robots and welding equipment. The robot consists of the robot body and the control cabinet (hardware and software). Welding equipment, taking arc welding and spot welding as an example, is composed of welding power supply, (including its control system), wire feeder (arc welding), welding torch (pliers) and other parts. For intelligent robots, there should also be sensing systems, such as laser or camera sensors and their control devices. Figures 1a and b show the basic components of arc welding robots and spot welding robots.　　Welding robots produced in countries around the world are basically joint robots, and most of them have 6 axes. Among them, the 1, 2, and 3 axes can send the end tool to different spatial positions, while the 4, 5, and 6 axes solve the different requirements of the tool posture. There are two main forms of mechanical structure of the welding robot body: one is a parallelogram structure and the other is a side-mounted (pendulum) structure, as shown in Fig. 2a and b. The main advantage of the side-mounted (pendulum) structure is the large range of motion of the upper and lower arms, so that the robot's welding robot schematic diagram space can almost reach a sphere. Therefore, the robot can be hung upside down on the rack to save floor space and facilitate the flow of objects on the floor. However, this kind of side-mounted robot, 2 and 3 axes for cantilever structure, reduce the rigidity of the robot, generally suitable for robots with small loads, for arc welding, cutting or spraying. The upper arm of the parallelogram robot is driven by a tie rod. The tie rod forms the two sides of a parallelogram with the lower arm. Hence the name. The parallelogram robot developed early had a relatively small working space (limited to the front of the robot) and made it difficult to work upside down. However, the new parallelogram robot (parallel robot) developed since the late 80s has been able to expand the working space to the top, back and bottom of the robot without the stiffness problem of the measurement robot, so it has received widespread attention. This structure is suitable not only for light but also heavy robots. In recent years, spot welding robots (load 100~150kg) mostly use parallelogram structure robots.　　Each axis of the above two robots is for rotary motion, so the servo motor is driven by the cycloid pinwheel (RV) reducer (1~3 axis) and harmonic reducer (1~6 axis). Before the mid-80s, DC servo motors were used for electrically driven robots, and since the late 80s, countries have switched to AC servo motors. Since the AC motor has no carbon brush and good dynamic characteristics, the new robot not only has a low accident rate, but also greatly increases the maintenance-free time, and the speed of adding (decremating) is also fast. Some new light robots with loads below 16kg have a maximum movement speed of more than 3m/s at the center point of the tool (TCP), accurate positioning and low vibration. At the same time, the control cabinet of the robot also uses a 32-bit microcomputer and a new algorithm, so that it has the function of optimizing the path by itself, and the running trajectory is closer to the trajectory of teaching.

Precautions for welding

2020-05-06

Welding is a local rapid heating and cooling process, the welding area can not expand and contract freely due to the constraints of the surrounding workpiece body, and welding stress and deformation will occur in the weldment after cooling. Important products need to eliminate welding stress and correct welding deformation after welding. 　　Modern welding technology has been able to weld welds without internal and external defects and with mechanical properties equal to or even higher than the joined body. The mutual position of the welded body in space is called the welded joint, and the strength of the joint is not only affected by the quality of the weld, but also related to its geometry, size, force and working conditions. The basic forms of joints are butt, lap and T-joint

Features of welding robots

2020-05-06

Spot welding is not very demanding for welding robots. Because spot welding only requires point control, there are no strict requirements for the movement trajectory of welding tongs between points, which is why robots can only be used for spot welding at the earliest. The robot for spot welding must not only have sufficient load capacity, but also be fast when shifting between points, smooth in action, and accurate in positioning to reduce the time of shifting and improve work efficiency. How much load capacity a spot welding robot needs depends on the form of welding tongs used. For welding tongs separated from the transformer, a robot with a load of 30~45kg is sufficient. However, this welding tongs on the one hand due to