Thermal Analysis of Capacitor Discharge Welding and its Correlation With Observed Stress Wave Emission (SWE)

Abstract

A theoretical approach to thermal analysis of capacitor discharge welding is presented. The weld current is divided into three segments (premelting, melting, and postmelting) and each is analyzed with a one dimensional heat conduction model. From this analysis, normalized parameter values are plotted to provide an estimate of the thermal time constant of welding and the extent of melting. The predicted weld zone depth of penetration was experimentally verified with metallographic data. Similarly, using signal frequency discrimination techniques, it was found that Stress Wave Emission (SWE) techniques could be adapted to measure the parameters of the above three pulse segments (tm , te , tc ) accurately and in real time. Theoretical and experimental metallographic and SWE results are in good agreement.