| 摘要 |
PROCESS FOR RESISTANCE-WELDING AND ARRANGEMENT FOR CARRYING OUT THE PROCESS A process is described for resistance-welding with a welding current which pulsates in periodic halfwaves, in particular an alternating current, and which is generated from a primary alternating voltage (Up) of a welding transformer (16) and is regulated by pulse duration modulation thereof. The primary alternating voltage (Up) is chopped n times (n>1) in each half-wave during the pulse duration modulation. In each half-wave the welding current is regulated by performing n nominal-actual value comparisons of the current and by the pulse length modulation the duty ratio accordingly being influenced n times. In order to regulate the welding current, a regulator (18) is provided, having a store containing current nominal values for each chopping interval, corresponding to the welding current form, for comparing with each current actual value determined per chopping interval. In this way, not only can very short regulating times be obtained, because in each half-wave the welding current can be readjusted repeatedly, but the current form is freely selectable, because a large number of nominal values can be kept in readiness in the store for each halfwave of the current. For electric resistance-welding, in each halfwave of the welding current, a current course is selected which deviates from the sinusoidal form. AS a result, energy delivery to the material which is being welded can be accurately proportioned, which makes it possible to weld materials which have hitherto been problematical, such as very thin and or thinly tin-plated sheet metal, black plates, chromium-plated sheet metal etc, with very good welding quality and a high throughput. (Fig. 1)
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