RESISTANCE SPOT WELDING METHOD

• US 20160144451A1
• Filed: 06/26/2014
• Published: 05/26/2016
• Est. Priority Date: 07/11/2013
• Status: Active Application

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel & Sumitomo Metal Corporation (Nippon Steel Corporation)
• Inventors: FUJIMOTO, Hiroki, DIKAWA, Hatsuhiko, YAMANAKA, Shintaro
• Granted Patent: US 10,265,797 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23K 11/115 by means of two electrodes placed opposite one another on both sides of the welded parts
• CPC Class Codes: B23K 11/16 taking account of the properties of the material to be welded
• CPC Class Codes: B23K 11/245 using a stepping counter in synchronism with the welding pulses electromagnetic counters G06M
• CPC Class Codes: B23K 2101/18 Sheet panels
• CPC Class Codes: B23K 2103/04 Steel or steel alloys

Abstract

A resistance spot welding method including: a pulsation process of clamping a sheet assembly of two or more overlapped steel sheets including at least one high tensile steel sheet using a pair of welding electrodes that are connected to a spot welding power source employing an inverter direct current method, and performing plural repetitions of current passing and current pass stopping, while pressing the steel sheets with the welding electrodes; and a continuous current pass process in which, after the pulsation process, current is passed continuously for a longer period of time than a maximum current pass time of the pulsation process, while pressing the steel sheets with the welding electrodes.

Claims

1. A resistance spot welding method comprising:

a pulsation process of clamping a sheet assembly of two or more overlapping steel sheets including at least one high-tensile steel sheet using a pair of welding electrodes that are connected to a spot welding power source employing an inverter direct current method, and performing a plurality of repetitions of current passing and current pass stopping, while pressing the steel sheets with the welding electrodes; and

a continuous current passing process in which, after the pulsation process, current is passed continuously for a longer period of time than a maximum current passing time of the pulsation process, while pressing the steel sheets with the welding electrodes.

2. The resistance spot welding method of claim 1, wherein, in the pulsation process, current passing times in the current passes are each from 10 milliseconds to 60 milliseconds.

3. The resistance spot welding method of claim 1, wherein, in the pulsation process, current pass stop times between adjacent current passes are each from 10 milliseconds to 60 milliseconds.

4. The resistance spot welding method of claim 1, wherein, in the pulsation process, a final current pass stop time between a final current pass and the continuous current passing process is from 10 milliseconds to 120 milliseconds.

5. The resistance spot welding method of claim 2, wherein, a current value of the current passes in the pulsation process is from 7.0 kA to 14.0 kA.

6. The resistance spot welding method of claim 2, wherein a current pass time in the continuous current passing process is from 100 milliseconds to 500 milliseconds.

7. The resistance spot welding method of claim 6, wherein the current value of a current pass in the continuous current passing process is from 5.0 kA to 12.0 kA.

8. The resistance spot welding method of claim 7, wherein a maximum current value in the continuous current passing process is a maximum current value in the pulsation process or lower.

9. The resistance spot welding method of claim 1, wherein the high-tensile steel sheet is a hot stamped steel sheet having a surface covered with a zinc-based skin or an aluminum-based skin.