More practical articles than welding robot user manual, summary of years of practical experience

Welding Defect Analysis and Treatment Method of Welding Robot

Argon-rich mixed gas shielded welding is used in robot welding. The welding defects in the welding process generally include welding deviation, undercut, porosity, etc. The specific analysis is as follows:

(1)Weld deviation may be due to the incorrect position of the weld or a problem with the gun search. At this time, it is necessary to consider whether the TCP (welding gun center point position) is accurate and adjust it. If this happens frequently, check the zero position of each axis of the robot and correct it again.

(2)The undercut may be caused by improper selection of welding parameters, wrong angle of welding gun or wrong position of welding gun. The welding parameters can be changed by adjusting the power, the posture of welding gun and the relative position of welding gun and workpiece.

(3)The pores may be poorly protected by gas, the primer of the workpiece is too thick, or the protective gas is not dry enough, and can be treated with corresponding adjustments.

(4)Too much spatter may be caused by improper selection of welding parameters, gas composition or too long extension length of welding wire. The welding parameters can be changed by adjusting the power, the gas ratio meter can be adjusted to adjust the ratio of mixed gas, and the relative position of welding torch and workpiece can be adjusted.

(5)A crater is formed after cooling at the end of the weld. When programming, the submerged crater function is added in the work step, which can be filled.

Common Faults and Solutions of Welding Robot

(1)The occurrence of the collision gun may be due to the deviation of the workpiece assembly or the TCP of the welding gun is inaccurate. The assembly condition can be checked or the TCP of the welding gun can be corrected.

(2)Arc fault, can not start the arc may be due to the welding wire does not touch the workpiece or process parameters are too small, can manually feed the wire, adjust the distance between the welding torch and the weld, or properly adjust the process parameters.

(3)If there is any fault in the cooling water or protective gas supply, check the cooling water or protective gas pipeline.

How to ensure the quality of the workpiece

As a teaching-reproducing robot, the assembly quality and accuracy of the workpiece must be better consistency.

The application of welding robots should strictly control the preparation quality of parts and improve the assembly accuracy of weldments. Part surface quality, groove size and assembly accuracy will affect the weld tracking effect. The following aspects can be used to improve the quality of parts preparation and the accuracy of weldment assembly.

(1)The preparation of welding robot special welding process, the size of the parts, weld groove, assembly size for strict process regulations. General parts and groove size tolerances are controlled within ± 0.8mm, assembly size errors are controlled within ± 1.5mm, and the probability of welding defects such as pores and undercuts in welds can be greatly reduced.

(2)High precision assembly tooling is used to improve the assembly accuracy of weldments.

(3)Welds shall be cleaned and free of oil stain, rust, welding slag, cutting slag and other sundries, and weldable primer is allowed. Otherwise, it will affect the success rate of arc. Tack welding is changed from electrode welding to gas shielded welding, and at the same time, the spot welding part is polished to avoid residual slag shell or pores due to tack welding, thus avoiding arc instability and even spatter.

Requirements of welding robot for welding wire

The robot can choose barreled or coiled welding wire as required. In order to reduce the frequency of replacing the welding wire, the robot should use barrel welding wire, but due to the use of barrel welding wire, the wire feeding hose is very long, the resistance is large, and the quality requirements for the stiffness of the welding wire are high. When the welding wire with poor quality of copper plating is used, the copper plating on the surface of the welding wire will reduce the internal volume of the conduit due to friction and fall off, and the resistance will increase during high-speed wire feeding. The welding wire cannot be smoothly sent out, resulting in jitter, unstable arc and affecting weld quality. In severe cases, there will be a stuck phenomenon, causing the robot to stop, so the welding wire conduit should be cleaned in time.

Programming Skills Summary

(1)Choose a reasonable welding sequence. In order to reduce the welding deformation, welding torch travel path length to develop the welding sequence.

(2)The space transition of welding gun requires short, smooth and safe moving trajectory.

(3)Optimization of welding parameters. In order to obtain the best welding parameters, the working test piece is made for welding test and process evaluation.

(4)Reasonable displacement machine position, welding torch attitude, welding torch relative to the position of the joint. After the workpiece is fixed on the displacement machine, if the welding seam is not the ideal position and angle, it is required to continuously adjust the displacement machine during programming, so that the welding seam reaches the horizontal position one by one according to the welding sequence. At the same time, the position of each axis of the robot should be continuously adjusted to reasonably determine the position, angle and welding wire extension length of the welding torch relative to the joint. After the position of the workpiece is determined, the position of the welding torch relative to the joint is observed by the programmer's eyes, which is difficult. This requires programmers to be good at summing up and accumulating experience.

(5)Timely insert gun cleaning procedures. After a certain length of welding program is written, the gun cleaning program should be inserted in time to prevent welding spatter from blocking the welding nozzle and conductive nozzle, ensure the cleanliness of the welding gun, improve the life of the nozzle, ensure reliable arc ignition and reduce welding spatter.

(6)The preparation of the program generally can not be in place in one step, to constantly check and modify the program in the process of robot welding, adjust the welding parameters and welding torch posture, etc., will form a good program.

Operation cost and management analysis

The price of imported robot accessories is higher, and efforts should be made to reduce the cost of use in all aspects. Lubricants can find low-cost alternatives with the same performance and utility in China. The welding process to strengthen maintenance, improve the service life of consumable parts such as nozzles, conductive nozzles, etc. In addition, preventive maintenance of the robot system can effectively improve the service life of the components.

High-quality managers, technicians and operators are necessary for robots to give full play to their efficiency. The quality of the use of an enterprise welding robot lies largely in people, so it is necessary to ensure a stable work team.