×

Inverter seam resistance welding electric power supply apparatus

  • US 5,866,866 A
  • Filed: 09/19/1996
  • Issued: 02/02/1999
  • Est. Priority Date: 09/20/1995
  • Status: Expired due to Fees
First Claim
Patent Images

1. An inverter-type resistance welding electric power supply apparatus for supplying a welding current, through a welding transformer and a pair of seam welding electrodes, to a pair of workpieces in which the welding electrodes are contacted with and moved relative to the workpieces so that a seam-welded portion is formed in the workpieces, wherein the welding transformer includes a primary circuit with a primary coil and a secondary circuit, said power supply apparatus comprising:

  • a rectifier means for rectifying a commercial AC voltage into a DC voltage;

    an inverter means for converting said DC voltage into a pulse-shaped voltage having a predetermined high frequency, and for supplying said pulse-shaped high frequency voltage to the primary coil of the welding transformer to supply the welding current;

    a monitor time interval preselecting means for subdividing a seam weld time of a seam weld operation into a plurality of preselected time intervals such that each of said plurality of preselected time intervals consists of a plurality of inverter switching cycles, and for preselecting each of said plurality of preselected time intervals as a respective current monitor time interval;

    a current measuring means for measuring a value of a current flowing in the primary or secondary circuit of the welding transformer during each current monitor time interval;

    a first determining means for comparing the current value measured by said current measuring means for each current monitor time interval with a preselected monitoring value to determine, for each current monitor time interval, whether a resulting weld corresponding to the respective current monitor time interval is conforming or defective;

    a second determining means for determining that a resulting seam weld is defective when said first determining means has successively determined that a defective weld has occurred for a predetermined number of successive current monitor time intervals.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×