GB450939A - Improvements in and relating to electric welding apparatus - Google Patents

Abstract

450,939. Control systems for resistance welding ; mechanical make- and-break switches ; fusible cut-outs. TARASSOFF, W., 24, Furmannyi, and KOROVKIN, W., 3, Lesnoij, both in Moscow. Jan. 24, 1935, No. 2396. [Class 38 (iv)] [See also Groups XXXVI and XXXVII] In an electric-resistance welding-machine the duration of flow of the welding current is controlled by a fusible wire in series in the circuit which breaks the circuit a predetermined time after commencement of current flow. The wire 2 is wound off a spool 1 on to the contact arms of a rotatable commutator 4 co-operating with contact studs 10, 12 connected in series in the primary circuit of the welding-transformer. The wire is clipped on each arm between a resilient strip 5, Fig. 5, and a member 6 and the contact arms are rotated by a manually operated ratchet mechanism so that two adjacent arms contact with the studs 10, 12 for each welding operation. The commutator 4 is immersed in oil and members 14, 15 are provided which cause opening of the strip 5 and member 6 on the contact arms 4 after the wire has been fused so that the wire ends are removed. Closure of a push button 23, Fig. 6, energizes an electromagnet 24 under the control of a rotating make-and-break switch 25, 28, 281 driven by a synchronous motor 29 and adjustable so that the electromagnet 24 is energized at a predetermined instant in the cycle and closes the primary circuit of the transformer 27 at this instant. A holding circuit 34, 35 for the electromagnet is completed and is not opened until the wire fuses. A black disc 48 having a diametrical white line across it is mounted on the shaft of the synchronous motor 29 and is illuminated by a pair of discharge tubes 33 energized from the A.C. supply so that the phase position of the adjustable brushes 28, of the make-and-break switch is indicated stroboscopically by a pointer 30 mounted on the brush 28 and co-operating with the disc 48. By this means the instant in the cycle at which the circuit of the transformer is completed may be adjusted and indicated.