Resistance spot welding method

Patent metadata

Field	Value
Publication number	US-2016008913-A1
Application number	US-201414770592-A
Country	US
Kind code	A1
Filing date	Jan 24, 2014
Priority date	Mar 8, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

Proposed is a method of resistance spot welding to join a plurality of overlapping metal sheets, including: dividing a current pattern into two or more steps for welding; before actual welding, performing test welding to store, for each step as a target value, a time variation of an instantaneous amount of heat generated per unit volume and a cumulative amount of heat generated per unit volume; and subsequently, as actual welding, starting welding using, as a standard, a time variation curve of the instantaneous amount of heat generated per unit volume obtained by the test welding, and when a time variation amount of an instantaneous amount of heat generated deviates during any step from the time variation curve by a difference, performing adaptive control welding to control a current passage amount in order to compensate for the difference during a remaining welding time in the step.

First claim

1 . A method of resistance spot welding to join materials to be welded by squeezing the materials between a pair of electrodes and passing current while applying pressure, the materials being a plurality of overlapping metal sheets, the method comprising:
dividing a current pattern into two or more steps for welding; before actual welding, performing test welding to store, for each step as a target value, a time variation of an instantaneous amount of heat generated per unit volume and a cumulative amount of heat generated per unit volume that are calculated from an electrical property between electrodes when forming an appropriate nugget by passing current with constant current control; and subsequently, as actual welding, starting welding using, as a standard, a time variation curve of the instantaneous amount of heat generated per unit volume obtained by the test welding, and when a time variation amount of an instantaneous amount of heat generated per unit volume deviates during any step from the time variation curve by a difference, performing adaptive control welding to control a current passage amount in order to compensate for the difference during a remaining welding time in the step so as to match a cumulative amount of heat generated in the actual welding to the cumulative amount of heat generated that is determined in advance in the test welding.

2 . The method of claim 1 , wherein a timing for dividing into the two or more steps is a point in time at which a weld is formed between the materials to be welded.

Assignees

• Jfe Steel Corp

Inventors

• Okita Yasuaki
• Sawanishi Chikaumi
• Ikeda Rinsei
• Oi Kenji

Classifications

• B23K11/115 Primary

  by means of two electrodes placed opposite one another on both sides of the welded parts · CPC title

• B23K11/24 Primary

  Electric supply or control circuits therefor · CPC title