method and device for the control of punktschweissungen.

摘要

Ultrasonic transducers (28) spring biased (36) into seating engagement in a pair of opposed spot welding tips (24) transmit and receive ultrasonic waves and associated circuitry (16,18) measures the time of flight between the transducers which is a function of tip separation, workpiece temperature and weld nugget size which are indicators of the progress of a weld. The rate of change of flight time is measured and the weld current is adjusted early in the weld cycle to maintain a preset rate of weld growth. The weld current is terminated later in the cycle if the transit time rate falls below another preset value. Otherwise the weld current and termination time follow a standard schedule.