자동차용 강판의 AC 저항용접에서 날림 방지 알고리즘 개발에 관한 연구

Abstract

Resistance spot welding follows the tendency of simplification and lightness, but the prediction of heavy expulsion and real-time monitoring weld quality is difficult. There have been progressed studies on methods of weld assessment for expulsion reduction and reliability improvement. In general, the sampling method is the easiest way among those for estimating the strength of weld, but is difficult to assess the change of the weld quality in real time. In AC resistance welding, a lot of research on the quality monitoring system has been carried out in order to enhance the reliability of the quality of the weld. The important parameters of this monitoring method are welding current, welding voltage, dynamic resistance, displacement and heating value etc, and among these parameters the studies using dynamic resistance and displacement are especially worthy of notice. It is only mentioned for dynamic resistance in most macroscopic changes, despite microscopic changes per half cycle. In this study, Instantaneous Dynamic Resistance(IDR) and Instantaneous Heating Rate(IHR) are proposed to accurately observe heat generation during half cycle in single phase AC resistance welding and inverter AC resistance welding considering the sensor position to reduce inductance noise. This study analyzed the heating pattern per half cycle using IDR and IHR, and studied the welding quality evaluation algorithm to predict the electrode tip diameter and the splash by continuous weld.