Research on Measurement of Thermal Expansion Electrode Displacement and Quality Control for Spot Welding

摘要

Resistance welding is one of important welding methods with extensive application in automobile industry. Constant current control is usually adopted to ensure the welding quality in production. This method is simple and low cost, but the influence on welding quality cannot be compensated completely that caused by shunt and electrode wear, etc. Therefore, welding quality control using electrode displacement of thermal expansion is proposed in this paper. Thermal expansion amount is detected by grating displacement sensor with quick dynamic response, high resolution and repeatability. The electrode displacement rate and peak value are taken as characteristics parameters in spot welding. The results of electrode displacement measurement and spot welding experiments indicate that the datum obtained from the grating displacement sensor are precise and high of repeatability, thus the influence caused by variable factors in spot welding can be compensated and the welding quality stability can be realized by the proposed method.