Switching control system for controlling an inverter of a spot resistance welding apparatus

• US 5,229,567 A
• Filed: 03/13/1992
• Issued: 07/20/1993
• Est. Priority Date: 11/17/1988
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Suzuki, Makoto, Saito, Hitoshi, Kobayashi, Nobuo, Takano, Fumitomo, Koga, Hidenori
• Primary Examiner(s): Shaw, Clifford C.
• Application Number:
  US07/850,881
• Time in Patent Office: 494 Days
• Field of Search: 219/108, 219/110, 307/96, 307/97, 363/17, 363/74
• US Class Current: 219/110
• CPC Class Codes: B23K 11/24 Electric supply or control circuits therefor

Abstract

A DC resistance welding apparatus includes a pair of welding electrodes for sandwiching workpieces to be welded therebetween and a circuit connected to the welding electrodes for supplying a welding current to said welding electrodes. The circuit includes a plurality of parallel-connected rectifying circuits each having a welding transformer and rectifying circuit. The circuit allows a large welding current to be supplied to workpieces, and makes the DC resistance welding apparatus small in size and light in weight.

Claims

1. A DC resistance welding apparatus comprising:

a pair of welding electrodes for sandwiching workpieces to be welded therebetween;

an inverter unit having semiconductors switchable into and out of operation for converting DC electric energy to AC electric energy;

means for converting the AC electric energy to DC electric energy and applying the DC electric energy to said welding electrodes;

a base driver for operating said semiconductors with switching currents higher than a continuous rating range; and

a timer circuit for measuring a conduction time of the semiconductors and cutting of said switching currents, thereby rendering said semiconductors non-conductive, when the measured conduction time exceeds a predetermined time.

2. A DC resistance welding apparatus according to claim 1, wherein said timer circuit comprises an oscillator for generating a pulsed signal having a frequency higher than the frequency of the AC electric energy, an AND gate having an input terminal supplied with said pulsed signal and an input terminal supplied with a signal corresponding to the AC electric energy, a presettable counter for counting a pulsed signal from said AND Gate and supplying a count signal to said base driver, and a setting unit for setting said presettable counter to a preset value corresponding to said predetermined time.