Patent ID: 7420137

Claim:
Method of open or closed-loop control of a welding tong movement by a welding tong drive, comprising at least one primary and one secondary drive device, wherein the primary drive device moves at least two welding tong limbs with welding electrodes from essentially opposite sides towards a welding object and presses the at least two welding tong limbs with a predetermined compressive force onto the welding object, and wherein the secondary drive device during its actuation varies a spatial orientation of the welding tongs, the method comprising the following steps: a) approach of the welding tongs to a predetermined spatial point relative to the welding object; b) holding of the welding tongs in a fixed spatial orientation during the approach; c) after the holding step and before an actuation step, and after termination of the approach towards the welding object, acquiring an applied holding current for the secondary drive device; d) actuation of the secondary drive device up to contacting of the welding object with at least one welding tong limb and acquisition of the contacting, wherein in the actuation step the holding current is varied by a predetermined contacting current level for the actuation of the secondary drive device for establishing contact, and e) after acquisition of the contacting, closure of the welding tong limbs by the primary drive device with build-up of a predetermined compressive force for welding.