What Is Robot Welding?

Welding robots are industrial robots engaged in welding (including cutting and spraying). According to the definition of the International Standards Organization (ISO) industrial robot as a standard welding robot, an industrial robot is a multi-purpose, reprogrammable automatic control manipulator (Manipulator) with three or more programmable axes for The field of industrial automation. In order to adapt to different uses, the mechanical interface of the last axis of the robot is usually a connecting flange, which can be used for different tools or end effectors. Welding robots are equipped with welding clamps or welding (cutting) guns on the final shaft flanges of industrial robots to enable them to perform welding, cutting or thermal spraying.

Welding robot mainly includes two parts: robot and welding equipment. The robot is composed of a robot body and a control cabinet (hardware and software). For welding equipment, taking arc welding and spot welding as examples, the welding power source (including its

Spot welding does not place high demands on the welding robot. Because spot welding only requires point position control, as for the trajectory of the welding tongs between points, there is no strict requirement, which is why the robot can only be used for spot welding at the earliest. The spot welding robot must not only have sufficient load capacity, but also must be fast when shifting from point to point, the movement must be stable, and the positioning must be accurate to reduce the time of shifting.

Because the designed welding robot works in a quasi-planar and narrow space environment, in order to ensure that the robot can track the automatic welding of the weld according to the deviation information of the arc sensor, the designed robot should be compact, flexible and stable. In view of the narrow space characteristics, a small mobile welding robot was developed in this paper. Based on the movement characteristics of each structure of the robot, a modular design method was used to divide the robot mechanism into a wheeled mobile platform, a torch adjustment mechanism and an arc sensor. Among them, the wheeled mobile platform, due to its large inertia and slow response, mainly performs coarse tracking of the weld, the welding torch adjustment mechanism is responsible for accurate tracking of the weld, and the arc sensor completes the real-time identification of the weld deviation. In addition, the robot controller and motor driver are integrated on the robot mobile platform to make it smaller. At the same time, in order to reduce the impact of dust on moving parts in harsh welding environments, a fully enclosed structure is adopted to improve its system reliability ^[1]

Because the welding equipment of the spot welding robot uses integrated welding tongs, and the welding transformer is installed behind the welding tongs, the transformer must be miniaturized as much as possible. For small-capacity transformers, 50Hz power frequency AC can be used, and for larger-capacity transformers, inverter technology has begun to use 50Hz power frequency AC to 600-700Hz AC, reducing the size of the transformer. After the voltage change, it can be directly welded with 600-700Hz AC power, or it can be re-rectified and welded with DC power. Welding parameters are determined by

I. Daily inspection and maintenance

1. Wire feeding mechanism. Including whether the wire feeding force distance is normal, whether the wire feeding catheter is damaged, and whether there is an abnormal alarm. 2. Whether the gas flow is normal. 3. Whether the welding torch safety protection system is normal. (It is forbidden to close the welding torch for safety protection work) 4. Whether the water circulation system works normally. 5. Test TCP (it is recommended to prepare a test program to run after each shift)

2. Weekly inspection and maintenance

1. Scrub the robot axes. 2. Check the accuracy of TCP. 3. Check the residue oil level. 4. Check whether the zero position of each axis of the robot is accurate. 5. Clean the filter behind the welder water tank. 6. Clean the filter at the compressed air inlet. 7. Clean up the impurities at the nozzle of the welding gun to avoid blocking the water circulation. 8. Clean the wire feeding mechanism, including wire feeding wheel, wire pressing wheel and wire guide tube. 9. Check the hose bundle and guide wire hose for damage and breaks. (It is recommended to remove the entire hose bundle and clean it with compressed air.) 10. Check whether the welding torch safety protection system is normal and the external emergency stop button is normal.

3. Monthly inspection and maintenance

1. Lubricate each axis of the robot. One to six shafts are added with white lubricant. Oil number 86E006. 2. Add red butter on the RP positioner and RTS rail. Oil number: 86K007 3. The blue filling nozzle on the RP positioner is filled with gray conductive grease. Oil number: 86K004 4. Lubricate the needle roller bearings of the wire feed wheel. (Small amount of butter is enough) 5. Clean the gun cleaning device and fill the air motor with lubricating oil. (Ordinary oil can be used) 6. Clean the control cabinet and welding machine with compressed air. 7. Check the cooling water level of the water tank of the welding machine, and replenish the cooling liquid in time (purified water plus a little industrial alcohol). 8. Complete all the items of 1-8, and perform all the items of the weekly inspection.