The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 04, 2000
Filed:
Sep. 10, 1997
Ren Mukai, Chiba-ken, JP;
Masaaki Fujisawa, Chiba-ken, JP;
Miyachi Technos Corporation, Chiba-Ken, JP;
Abstract
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.