US 12,447,549 B2
Resistance spot welding method and weld member production method
Chikaumi Sawanishi, Tokyo (JP); Yasuaki Okita, Tokyo (JP); and Hiroshi Matsuda, Tokyo (JP)
Assigned to JFE STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/754,517
Filed by JFE STEEL CORPORATION, Tokyo (JP)
PCT Filed Oct. 6, 2020, PCT No. PCT/JP2020/037916
§ 371(c)(1), (2) Date Apr. 5, 2022,
PCT Pub. No. WO2021/070836, PCT Pub. Date Apr. 15, 2021.
Claims priority of application No. 2019-186405 (JP), filed on Oct. 9, 2019.
Prior Publication US 2023/0124228 A1, Apr. 20, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. B23K 11/11 (2006.01); B23K 11/25 (2006.01); B23K 103/04 (2006.01)
CPC B23K 11/115 (2013.01) [B23K 11/25 (2013.01); B23K 2103/04 (2018.08)] 8 Claims
OG exemplary drawing
 
1. A resistance spot welding method of squeezing, by a pair of electrodes, parts to be welded which are a plurality of overlapping metal sheets and passing a current while applying an electrode force to join the parts to be welded,
wherein main current passage includes two or more electrode force application steps including a first electrode force application step and a second electrode force application step following the first electrode force application step, and an electrode force F1 in the first electrode force application step and an electrode force F2 in the second electrode force application step in the main current passage satisfy a
relationship F1>F2, and an electrode force switching point Tf from the first electrode force application step to the second electrode force application step in the main current passage is set to satisfy the following Formulas (1) to (3):
in the case where TA≤0.8×T0,
TA≤Tf<T0  (1)
in the case where 0.8×T0<TA≤T0 or 0.9×R0≤RA≤R0,
0.9×T0<Tf<1.1×T0  (2)
in the case where RA<0.9×R0,
T0<Tf≤T0+2×(R0−RA)/R0×Tm  (3)
where T0 is a reference electrode force switching point from the first electrode force application step to the second electrode force application step, Tm is a total welding time in the main current passage, RA is a time integration value of a resistance between the electrodes from current passage start of the main current passage to the reference electrode force switching point T0, R0 is a time integration value of a resistance between the electrodes from current passage start to the reference electrode force switching point T0 in the case where current passage is performed under a same condition as the main current passage when the parts to be welded have no disturbance, and TA is a time at which a time integration value of a resistance between the electrodes in the main current passage reaches R0.