Improvements in resistance welding systems

Abstract

Abstract 548,618. Supply systems for resistance welding. SVENSKA AKTIEBOLAGET GASACCUMULATOR. Oct. 21, 1941, No. 13517. Convention date, Oct. 11, 1940. [Class 38 (iv)] Thermionic control, charging and discharging condensers. A transformer supplying a resistance welder is energized alternately in opposite directions by the charging and discharging or by successive discharges of a condenser ; saturation effects are thereby eliminated. Grid controlled rectifiers are employed to control the charging and discharging of the condenser. A condenser 21 may be charged through the balanced winding sections 18, 24 of a welding transformer by the synchronously timed ignition of a grid controlled gaseous valve 27 and discharged through the same windings, with added turns to replace the inductance of the transformer 15, by a valve 34 ignited during the following, or a later, half cycle of the supply current; reversed charging of the condenser by welding transformer flux is checked by a rectifier valve 40 in shunt to the condenser. Opposite half-cycles may be arranged to charge an auxiliary condenser assisting the charging impulse of the main condenser. The circuits include a manual switch 65 and a timer 62 to determine the number of shots in a weld. The conductors 16, 32 may be energized from a rectifier, and the motor 78 need not then be synchronized. Several modifications are described. The commulator controlling the grid potentials may, with a suitable valve arrangement, connect two condensers in turn during a single charging or discharging impulse and so prolong the welding current. By a bridge connector of controlled valves a single condenser may be charged successively to opposite polarities and discharged through a single winding or through balanced windings on the welding transformer. The commutator segments may be replaced by photo-electric cell apparatus operated by apertured discs.

Inventors

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