Friction stir spot welding device and friction stir spot welding method

Patent metadata

Field	Value
Publication number	US-10201873-B2
Application number	US-201515521388-A
Country	US
Kind code	B2
Filing date	Oct 22, 2015
Priority date	Oct 23, 2014
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

A friction stir spot welding device includes a pin member, a shoulder member, a rotation driving unit, a tool driving unit, a position detector, and a controller, wherein the controller sets as reference position of the tip end surface of the pin member or shoulder member at a time point when the pin member tip end surface or shoulder member contacts an obverse surface of an object and controls the tool driving unit reducing a pressing force to the object by the pin member and pressing force to the object by the shoulder member in a next welding process, and/ or controls the rotation driving unit reducing the pin member rotational speed and shoulder member rotational speed in the next welding process, in case where a first position is the position of the tip end surface of the pin member or the shoulder member is within a first region.

First claim

The invention claimed is:

1. A friction stir spot welding device which welds an object to be welded, by softening the object by friction heat and by stirring the object, the friction stir spot welding device comprising:
a pin member which has a solid cylinder shape, is rotatable around an axis of the pin member, and is advanceable and retractable along the axis of the pin member;
a shoulder member which has a tubular shape with a circular cross-section, is rotatable around an axis of the shoulder member, and is advanceable and retractable along the axis of shoulder member, the pin member being insertable into the shoulder member;
a rotation driving unit which rotates the pin member around the axis of the pin member and rotates the shoulder member around the axis of the shoulder member;
a tool driving unit which causes the pin member to be advanced and retracted along the axis of the pin member, and causes the shoulder member to be advanced and retracted along the axis of the shoulder member;
a position detector which detects an axial position of a tip end surface of the pin member or an axial position of a tip end surface of the shoulder member; and
a controller including a CPU and a memory, the processor being configured to read a program stored in the memory and execute the program so as to
set as a reference position the axial position of the tip end surface of the pin member or the axial position of the tip end surface of the shoulder member which is detected by the position detector at a time point when the tip end surface of the pin member or the tip end surface of the shoulder member contacts an obverse surface of the object, when a welding process for the object is initiated,
control the tool driving unit to make the tip end surface of the pin member and the tip end surface of the shoulder member coplanar with each other, when the welding process for the object ends,
control the tool driving unit to reduce a pressing force applied to the object by the pin member and a pressing force applied to the object by the shoulder member in a next welding process, and/ or control the rotation driving unit to reduce a rotational speed of the pin member and a rotational speed of the shoulder member in the next welding process, in a case where a first position which is the axial position of the tip end surface of the pin member or the axial position of the tip end surface of the shoulder member, which is detected by the position detector, is within a first region which is inward of the object relative to the reference position, when the welding process for the object ends.

2. The friction stir spot welding device according to claim 1 ,
wherein the controller controls the tool driving unit to reduce the pressing force applied to the object by the pin member and the pressing force applied to the object by the shoulder member in the next welding process, and/or controls the rotation driving unit to reduce the rotational speed of the pin member and the rotational speed of the shoulder member in the next welding process, in a case where the first position is within the first region when the welding process for the object ends, and a temperature of the pin member and a temperature of the shoulder member are equal to or higher than a predetermined temperature, when the next welding process is initiated.

3. The friction stir spot welding device according to claim 1 ,
wherein the controller controls the tool driving unit to reduce the pressing force applied to the object by the pin member and the pressing force applied to the object by the shoulder member in the next welding process, and/or controls the rotation driving unit to reduce the rotational speed of the pin member and the rotational speed of the shoulder member in the next welding process, in a case where the first position is within the first region when the welding process for the object ends, and a time that passes from when the welding process for the object has ended until the next welding process is initiated is within a predetermined time.

4. The friction stir spot welding device according to claim 1 ,
wherein the controller determines that a portion of the object adheres to the pin member and/or the shoulder member, causes a notification unit to output an alarm, and/or inhibits the next welding process from being performed, in a case where the first position is changed between a second region that is more distant from the object than the reference position is, and the first region or the reference position, every time the welding process for the object ends.

5. The friction stir spot welding device according to claim 1 ,
wherein the controller controls the tool driving unit so that an absolute value of a tool average position Tx defined in a formula Ap·Pp+As·Ps=Tx is reduced, in a case where a cross-sectional area of the tip end surface of the pin member is designated by Ap, a cross-sectional area of the tip end surface of the shoulder member is designated by As, a plunge depth of the pin member plunged into the obverse surface of the object is designated by Pp, and a plunge depth of the shoulder member plunged into the obverse surface of the object is designated by Ps.

6. The friction stir spot welding device according to claim 5 ,
wherein the controller controls the tool driving unit to realize that the tool average position Tx is equal to 0.

7. The friction stir spot welding device according to claim 5 ,
wherein the controller controls the tool driving unit to reduce the pressing force applied to the object by the pin member and the pressing force applied to the object by the shoulder member in the next welding process and/or controls the rotation driving unit to reduce the rotational speed of the pin member and the rotational speed of the shoulder member in the next welding process, in a case where a tool average position Tx 1 which is the tool average position Tx calculated based on the reference position and the first position is outside a preset proper range.

8. The friction stir spot welding device according to claim 7 ,
wherein the controller inhibits the next welding process from being performed, in a case where the tool average position Tx 1 is larger than a first threshold which is larger than the preset proper range.

9. The friction stir spot welding device according to claim 7 ,
wherein the controller determines that a portion of the object adheres to the pin member and/or the shoulder member, causes the notification unit to output an alarm, and/or inhibits the next welding process from being performed, in a case where the tool average position Tx 1 is changed between a minus value and a plus value or 0, every time the welding process for the object ends.

10. The friction stir spot welding device according to claim 1 , further comprising:
a clamp member which is advanceable and retractable along an axis of the clamp member; and
a clamp member driving unit which causes the clamp member to be advanced and retracted along the axis of the clamp member,
wherein the controller controls the tool driving unit and/or the clamp member driving unit to reduce the pressing force applied to the object by the pin member, the pressing force applied to the object by the shoulder member, and a pressing force applied to the object by the clamp member in the next welding process, in a case where the first position is within the first region.

11. A friction stir spot welding method which welds an object to be welded, by softening the object by friction heat and by stirring the object, the friction stir spot welding method comprising:
(A) setting as a reference position an axial position of a tip end surface of a pin member or an ax

Assignees

• Kawasaki Heavy Ind Ltd

Inventors

• Okada Hideki
• Fukada Shintaro

Classifications

• B23K20/123 Primary

  Controlling or monitoring the welding process · CPC title

• B23K20/1265 Primary

  Non-butt welded joints, e.g. overlap-joints, T-joints or spot welds · CPC title

• B23K2101/18

  Sheet panels · CPC title

• B23K20/24

  Preliminary treatment · CPC title

• B23K20/12

  the heat being generated by friction; Friction welding · CPC title