Process monitoring is indispensable

Capacitor discharge machines (CD machines) are predominantly used in series production, in which many hundreds of parts are welded per shift. No process for the online testing of the welded connections (similar to the previously applied ultrasonic test methods for resistance spot welding) is known and non-destructive testing is rarely used. Therefore, cyclically produced parts are withdrawn from the production process and subjected to destructive testing in accordance with the QA specifications. In order to ensure that these random samples are representative of the connections welded in the interim period, effective process monitoring is essential.

The machines in the PrimKoM product range and the PrimKoS current sources are equipped with the PrimusKE welding control, which offers numerous measuring channels through which to measure the relevant process variables with a scanning frequency of 20 kHz.

The current measurement input 1 (terminal 1X3) is intended for the connection of a Rogowski belt (with 150 mV/kA), which is installed as standard; an associated integrator is integrated in the control. Also intended as standard is the measurement of the electrode voltage 2 (terminal 1X13). Depending on the customer’s wishes, it is possible to connect two incremental transducers 3 and/or up to four freely definable analogue measuring signals 4 (0 to 10 V or 4 to 20 mA). The two connections for the proportional valves 5 (PV1 and PV2) are equipped with an analogue input, via which the actual signal (insofar as the proportional valve has a feedback) is also recorded.