Friction stir welding tool and friction stir welding method

Patent metadata

Field	Value
Publication number	US-11986901-B2
Application number	US-202017291557-A
Country	US
Kind code	B2
Filing date	Mar 6, 2020
Priority date	Mar 8, 2019
Publication date	May 21, 2024
Grant date	May 21, 2024

Abstract

A friction stir welding tool (1) has a shoulder portion (2) and a probe portion (6) provided on a bottom surface of the shoulder portion (2). The probe portion (6) has a length of 5.5 mm or more. In the friction stir welding tool (1), a ceramic material whose main phase is silicon nitride or sialon is used as a base material.

First claim

What is claimed is:

1. A friction stir welding method characterized in that
plate members are friction stir welded by using a friction stir welding tool including
a shoulder portion, and
a probe portion provided on a bottom surface of the shoulder portion, the probe portion having a length of 5.5 mm or more, the probe portion decreasing in diameter continuously from the bottom surface toward a distal end of the probe portion, and grooving and/or chamfering is not performed on the probe portion such that the probe portion has a smooth surface,

wherein a ceramic material whose main phase is silicon nitride or sialon is used as a base material;
the shoulder portion of the friction stir welding tool is brought into contact with the plate members, while the probe portion of the friction stir welding tool is inserted into the plate members by an amount of 5.5 mm or more;
monitoring reaction forces applied from the plate members to the friction stir welding tool;
holding the position of the friction stir welding tool for a predetermined period of time after the probe portion has been inserted into the plate members; and
laterally moving the friction stir welding tool after the reaction forces applied from the plate members to the friction stir welding tool have decreased below a threshold value.

2. A friction stir welding method according to claim 1 , wherein the shoulder portion has a diameter of 20 mm or less.

3. A friction stir welding method according to claim 1 , wherein the length of the probe portion is 9.5 mm or more.

4. A friction stir welding method according to claim 1 , wherein the ceramic material contains a rare-earth element and aluminum.

5. A friction stir welding method according to claim 1 , wherein the plate members are steel plates.

6. A friction stir welding method according to claim 5 , wherein the steel plates contains carbon in an amount of 0.2 mass % or more.

7. A friction stir welding method according to claim 1 , wherein the method comprises disposing a backing plate on back surfaces of the plate members, the backing plate being lower in thermal conductivity than the plate members.

8. A friction stir welding method according to claim 1 , wherein the threshold value is 2 tons.

9. A friction stir welding method according to claim 1 , wherein the threshold value is about ⅔ of a maximum reaction force measured while holding the position of the friction stir welding tool.

10. A friction stir welding method according to claim 1 , wherein the plate members are steel plates containing carbon in an amount of 0.2 mass % or more; and
wherein the method comprises disposing a backing plate formed of silicon nitride on back surfaces of the plate members.

Assignees

• Ngk Spark Plug Co
• Univ Osaka
• Ntk Cutting Tools Co Ltd

Inventors

• Fujii Hidetoshi
• Morisada Yoshiaki
• Katsu Yusuke
• Takeuchi Hiroki

Classifications

• B23K20/1255 Primary

  Tools therefor, e.g. characterised by the shape of the probe · CPC title

• B23K2103/04

  Steel {or steel} alloys · CPC title

• B23K20/126

  Workpiece support, i.e. backing or clamping · CPC title

• B23K20/227

  with ferrous layer · CPC title

• B23K20/124

  at the beginning or at the end of a weld · CPC title