Process and apparatus for producing an electric arc current and apparatus for stud welding

• Main Authors: SCHEFFLER, HEIKO GERHARD, SCHMIDT, WOLFGANG, SCHMITT, KLAUS GISBERT
• Format: Patent
• Language: English; French; German
• Published: 23.05.2007
• Subjects: CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; PERFORMING OPERATIONS; SOLDERING OR UNSOLDERING; TRANSPORTING; WELDING; WORKING BY LASER BEAM

A method for producing an electric arc current (I s) for short period arc welding of bolts to a workpiece involves: (a) feeding a supply DC potential to an AC converter (30) with four controllable switching elements (S1)-(S4) arranged in an H-bridging circuit with two parallel longitudinal branches and a transverse branch (43) (in which the arc zone (32) is located); and (b) controlling diagonally located switching elements (S1, S4) and (S2, S3), so that in a first or second type of operation, a positive or negative arc current respectively flows through the transverse branch. Independent claims are included for: (1) a variant of the method, involving: (a') producing a supply AC potential at the secondary side (provided with a central tap point) of a transformer (TWT1); (b') DC-converting the supply AC potential to give a supply DC potential; (c') feeding the supply DC potential to an AC converter with two controllable switching elements(connected in series in a longitudinal branch connected to the DC supply potential), such that an arc zone is located in a branch connected between a recorder between the two switching elements and the central tap point of the secondary side of the transformer; and (d') controlling the two switching elements so that in a first or second type of operation a positive or negative arc current respectively flows; (2) a partial circuit for a machine for short period arc welding, where the partial circuit is for carrying out a process as above; and (3) a short period arc welding plant with a welding head and a control unit, where the control unit includes a partial circuit as above.