Miyachi Technos Corporation

Ren Mukai

Kyoji Moro

Masaaki Fujisawa

In odd-numbered current-supplying periods of a plurality of current-supplying periods constituting a gross current-supplying time, a control unit allows continuous switching actions of only a first set of switching elements at an inverter frequency, with a second set of switching elements remaining OFF. In even-numbered current-supplying periods, the control unit allows continuous switching actions of only the second set of switching elements at the inverter frequency, with the first set of switching elements ( ) remaining OFF. As a result of this, a secondary circuit of the power supply apparatus allows a secondary current i , namely a fusing current I having a substantially trapezoidal current waveform to flow in a positive direction in the odd-numbered current-supplying periods, and to flow in a negative direction in the even-numbered current-supplying periods.

Fusing processing method

An apparatus for controlling resistance welding defines a weld time for series welding as a plurality of (e.g., two) weld periods. In one embodiment, a control successively switches a bidirectional switch in a first polarity during the first weld period so that welding current flows through workpieces of different metals in one direction by passing through a series of welding points of the workpieces. In the second weld period, the control successively switches the bidirectional switch in the reversed polarity so that welding current flows through the workpieces in the other direction so as to compensate for Pertier effect on the welding points. A polarity changing technique is used to minimize welding energy loss in shifting weld periods for better weld quality. In another embodiment, thyristors are controlled such that they are fired in the second half cycle of the supply voltage at an angle smaller than the firing angle in the first half cycle.

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Chiba-ken, Japan

Ren Mukai