Resistance spot welding method

Patent metadata

Field	Value
Publication number	US-2016236294-A1
Application number	US-201415024164-A
Country	US
Kind code	A1
Filing date	Sep 12, 2014
Priority date	Oct 4, 2013
Publication date	Aug 18, 2016
Grant date	—

Abstract

Proposed is a resistance spot welding method to join parts to be welded which are a plurality of overlapping metal sheets, including: dividing a current pattern into two or more steps for welding; before actual welding, performing test welding; and subsequently, as actual welding, performing adaptive control welding, in which the two or more steps for welding include a step of securing a current path between the sheets directly below the electrodes and a subsequent step of forming a nugget having a predetermined diameter, and a welding interval time is provided between these steps. This method thus yields a good nugget without causing splashing even under special welding conditions.

First claim

1 . A resistance spot welding method to join parts to be welded by squeezing and pressing the parts between a pair of electrodes and passing current, the parts 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 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, wherein the two or more steps for welding comprise a step of securing a current path between the sheets directly below the electrodes and a subsequent step of forming a nugget having a predetermined diameter, and a welding interval time is provided between the step of securing a current path between the sheets directly below the electrodes and the subsequent step of forming a nugget having a predetermined diameter.

2 . The method according to claim 1 , wherein the welding interval time is one cycle or more and ten cycles or less.

Assignees

• Jfe Steel Corp

Inventors

• Sawanishi Chikaumi
• Okita Yasuaki
• Ikeda Rinsei

Classifications

• B23K11/115

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

• B23K2101/185

  Tailored blanks · CPC title

• B23K11/24 Primary

  Electric supply or control circuits therefor · CPC title

• B23K2101/34

  Coated articles {; Surface treated articles} · CPC title

• B23K2103/04

  Steel {or steel} alloys · CPC title