GB1104555A - Welding timers - Google Patents

Abstract

1,104,555. Resistance welding systems. SIEMENS-SCHUCKERTWERKE A.G. 21 April, 1966 [28 April, 1965], No. 17602/66. Heading H2H. A timing and sequencing arrangement for a resistance welder comprises a plurality of bi-stable trigger stages 1-3 each having complementary outputs Al, Al, a triggering input S1 and a cancelling input L1 each supplied from AND circuits 15 etc. one input of which is derived from a unit 7 providing three 180 degrees long pulses displaced by 72 degrees, 325 degrees and 355 degrees per mains cycle to prevent spurious operation of the arrangement. Stage 1 is triggered through AND gate 15 when a switch 10 is momentarily closed, and the pulse generator 7 supplies a 325 degrees pulse. The inlet valve for actuation of the electrodes is then opened. Triggering of stage 1 also resets a counter 5 by an output signal A1. At a time set by a switch 214 an input signal on stage 2 together with an Al signal from stage 1 and an A3 from stage 3 triggers this stage which increases the electrode pressure. At the triggering of stage 2 counter 5 is reset by the OR gate 81 and device 82. The next count commences with the end of the next 355 degrees pulse and at the next 355 degrees pulse which triggers stage 3 it resets counter 5 which operates from the end of this pulse. After expiry of the count set by unit 224 all inputs at present at AND 222 and stage 2 its reset leaving stages 1 and 3 which initiates welding current flow of the duration of which is set by a switch 14, after which stage 1 in counter 5 is reset. A further period is set by switch 215 at the end of which time stage 1 is reset through AND 213. A change over switch 151 provides one shot or a series of operatons. The AND/OR gates may be of dynamic type.