Patent attributes
The invention relates to a control device for spot welding with a welding electrode pincer (Z), the welding electrodes (E1, E2) of which are connect to a welding current generator (IS) and an electric motor drive (M), with a rotary transducer (RES), the signal of which is used by a control device (MP) to control the welding electrode pincer (Z). The closed state of said pincer holds the objects for welding (B1, B2) together, by means of a pre-set motor current (MAI), whereupon the welding current generator (IS) is activated. The control device (MP) comprises monitoring devices (const, max), to which the rotary transducer signals (RES) and/or a motor current measured signal (I(t)) are constantly supplied. Once a quasi-constant state is recognized, following a close signal for the welding electrode pincer (Z), a corresponding first state is recorded as the closed state and the welding current generator (IS) activated. Thereafter, as soon as the exceeding of a maximum value is reported, a further closed state is recorded, the welding current generator (IS) deactivated and a holding timer unit (CTT) activated, after the expiration (end) of which the on- and off-control of the welding electrode pincers is activated again.
