Method and device for monitoring and control of an operation of welding by resistance

摘要

A resistance welding controller for dynamically controlling both weld current and weld time in order to achieve a desired DELTA R value. The resistance across the weld electrodes is monitored by the controller during the heat-up phase of the weld and compared to target values for minimum resistance (Rmin) and rate of resistance change (dR/dt). If the observed values for Rmim and dR/dt bear a predetermined relationship to the target values, a dynamic correction is made in the percentage heat control setting. The weld is then continued at the revised weld current level until the desired DELTA R value is satisfied. If upon weld termination, the observed weld time is greater than the target weld time, an additional correction in weld current is made in preparation for the next weld. In addition, the controller is also adapted to detect newly dressed weld electrodes and automatically respond by reverting to the original weld schedule.