Method to Eliminate Weld Defects at 360 Degree Circular Weld Overlap

摘要

Shaft/gear laser welds in E-drive units are 360 degree circular welds which welding starts and finishes at the same position (overlap weld). Welding pore, cavities and cracks at the overlap are exceedingly difficult to eliminate. Welding suppliers recommend not to check or allow large defects such as weld cavity up to a few of millimeters. Overlap defects cause quality issues and lower weld strength. The method in this invention can eliminate cracks and can control overlap cavity below 0.5 mm. Welding starts at location A. Welding energy is increased to 100 at location B and continues to location C (clockwise). Welding energy is reduced from 100 at C to 0 at D to finish welding. Fatigue test results show no significant difference between the weld overlap area and the weld 180 degree from the overlap position.