JP7615873B2 - Apparatus and method for joining metal members - Google Patents

Description

The present invention relates to a joining device, joining method, and joined body for joining metal members (especially two metal members).

In the fields of automobiles, railway vehicles, aircraft, and the like, a method known as friction stir spot welding (FSSW) has been proposed as a method for joining metal members to each other from the viewpoint of improving productivity. The friction stir spot welding method is a method in which a first metal member and a second metal member are overlapped between a rotating tool and a receiving member, and while rotating the rotating tool, the first metal member is pressed against the first metal member to generate frictional heat, which causes the first metal member and the second metal member to plastically flow (or melt and solidify) relative to each other, thereby joining the first metal member and the second metal member.

In a joining device that uses this type of friction stir spot joining method, a receiving member is used that has a flat surface facing the rotating tool, and this flat surface directly supports the second metal member.

JP 2007-283317 A

The inventors of the present invention found that when joining metal members using a conventional device, sufficient joining strength was not obtained. In detail, when a receiving member with a flat surface on the rotating tool side (i.e., the support surface of the second metal member) was used, as shown in FIG. 6A, the second metal member 512 moved (or plastically flowed) toward the first metal member 511 in the vicinity of the indentation 520, and the remaining thickness Tz of the first metal member 511 was reduced, so that a sufficiently large joining strength was not obtained. Therefore, when the amount of penetration of the pressing member was reduced, as shown in FIG. 6B, the movement (or plastic flow) of the second metal member 512 toward the first metal member 511 was suppressed, and the reduction in the remaining thickness Tz of the first metal member 511 was suppressed, but the joining between the first metal member and the second metal member in the approximately horizontal direction Q was not performed sufficiently, so that a sufficiently large joining strength was not obtained. On the other hand, when the penetration amount of the pressing member 16 is increased, as shown in FIG. 6C and FIG. 6D, the second metal member 512 moves (or plastically flows) toward the first metal member 511 more, and the remaining thickness Tz of the first metal member 511 is further reduced, so that a sufficiently large joint strength cannot be obtained. FIG. 6A to FIG. 6D are schematic cross-sectional views of an example of a joint obtained by a conventional joining device and joining method (a joining device and joining method using a receiving member without a recess), and are enlarged views of the vicinity of the indentation mark. In particular, FIG. 6B is an enlarged view of the vicinity of the indentation mark in a joint obtained with a smaller rotation tool penetration amount than that in the joining of FIG. 6A. FIG. 6C is an enlarged view of the vicinity of the indentation mark in a joint obtained with a larger rotation tool penetration amount than that in the joining of FIG. 6A. FIG. 6D is an enlarged view of the vicinity of the indentation mark in a joint obtained with a larger rotation tool penetration amount than that in the joining of FIG. 6C.

On the other hand, as shown in FIG. 9, a technique is disclosed in which a recess 518 is provided in the center of the surface of the receiving member 517 facing the rotary tool (i.e., the supporting surface of the second metal member) for the purpose of joining metal members 511 and 512 of various thicknesses without replacing the rotary tool 516 (Patent Document 1). However, when such a receiving member 517 is used, the portions of the first metal member 511 and the second metal member 512 directly below the rotary tool 516 are lowered due to the presence of the recess 518 during joining, so that the remaining thickness Tz of the first metal member 511 is also reduced, and a sufficiently large joining strength cannot be obtained. FIG. 9 is a schematic cross-sectional view for explaining a joining device for metal members in the prior art (a joining device using a receiving member having a recess in the center).

The present invention aims to provide a metal member joining device and method that can easily achieve joining of metal members with sufficient strength.

The present invention relates to
A metal member joining device for joining two metal members, comprising:
a pressing member that applies a pressing force to a first metal member of the two metal members;
A joining device for metal members, comprising: a receiving member that directly supports a second metal member of the two metal members; and a drive control device that drives the pressing member and the receiving member to approach each other,
The present invention relates to an apparatus for joining metal members, wherein the receiving member has a recess on an outer periphery of a surface portion facing the pressing member.

The present invention also provides
A method for joining metal members by a thermocompression joining method, comprising: overlapping a first metal member and a second metal member between a pressing member and a receiving member; applying pressure to the second metal member by pressing the first metal member from the side of the pressing member; and applying heat to the first metal member and the second metal member to cause mutual plastic flow at an interface between the first metal member and the second metal member,
The receiving member has a recess on an outer periphery of a surface portion facing the pressing member,
The present invention relates to a method for joining metal members, in which the pressing member and the receiving member are brought close to each other, and a part of the second metal member is plastically flowed into the recess.

The present invention also provides
A bonded body in which a first metal member and a second metal member have an indentation from the first metal member side in an overlapping portion between the first metal member and the second metal member and are bonded at their interface around the indentation,
The present invention relates to a joined body of metal members, in which the second metal member has a protruding portion caused by plastic flow of the second metal member on the surface opposite to the first metal member.

The joining device and joining method of the present invention make it possible to easily achieve joining of metal members with sufficient strength.

1 is a schematic diagram showing an example of a part of a friction stir spot welding apparatus as one embodiment of an apparatus for welding metal members according to the present invention. FIG. 1 is an enlarged view of a tip portion of an example of a pressing member (particularly a rotation tool) used in the joining apparatus of the present invention. 13 is an enlarged view of a tip portion of another example of a pressing member (particularly a rotation tool) used in the joining apparatus of the present invention. FIG. 1 is a schematic cross-sectional view of a pressing member (particularly a rotary tool) and a receiving member according to a first embodiment used in a joining apparatus of the present invention. 10 is a schematic cross-sectional view of a receiving member according to a second embodiment used in the joining device of the present invention. FIG. 11 is a schematic cross-sectional view of a receiving member according to a third embodiment used in the joining device of the present invention. FIG. 13 is a schematic cross-sectional view of a receiving member according to a fourth embodiment used in the joining device of the present invention. FIG. 13 is a schematic cross-sectional view of a receiving member according to a fifth embodiment used in the joining device of the present invention. FIG. 4 is a schematic cross-sectional view for explaining an example of a thrust stirring step and a stirring maintaining step in the joining apparatus and joining method of the present invention. FIG. FIG. 11 is a schematic cross-sectional view for explaining another example of the thrust stirring step and the stirring maintaining step in the joining apparatus and the joining method of the present invention. 1 is a schematic cross-sectional view of an example of a bonded body obtained by the bonding apparatus and bonding method of the present invention. FIG. 5B is a schematic cross-sectional view of an example of a bonded body obtained with a larger rotary tool penetration amount than that in the bonding of FIG. 5A in the bonding apparatus and bonding method of the present invention. FIG. 1 is a schematic cross-sectional view of an example of a bonded body obtained by a bonding apparatus and a bonding method of the prior art (a bonding apparatus and a bonding method using a receiving member having no recess), and is an enlarged view of the vicinity of the indentation. FIG. 11 is a schematic cross-sectional view of another example of a joined body obtained by a joining apparatus and joining method of the prior art (a joining apparatus and joining method using a receiving member having no recess), and is an enlarged view of the vicinity of the indentation. FIG. 11 is a schematic cross-sectional view of another example of a joined body obtained by a joining apparatus and joining method of the prior art (a joining apparatus and joining method using a receiving member having no recess), and is an enlarged view of the vicinity of the indentation. FIG. 11 is a schematic cross-sectional view of another example of a joined body obtained by a joining apparatus and joining method of the prior art (a joining apparatus and joining method using a receiving member having no recess), and is an enlarged view of the vicinity of the indentation. FIG. 2 is a schematic diagram for explaining a method for measuring a bonding strength in the examples. 1 is a graph showing the relationship between the joining strength (maximum tensile shear load) and the tool insertion depth of the joined bodies obtained in the examples and comparative examples. FIG. 1 is a schematic cross-sectional view for explaining a conventional apparatus for joining metal members.

The joining device and joining method of the present invention are respectively a joining device and a joining method for joining two metal members. More specifically, the joining device and joining method of the present invention employ a thermo-compression joining method in which a first metal member and a second metal member are overlapped, and pressure is applied to the second metal member by pressing from the first metal member side with a pressing member, and heat is applied to cause the first metal member and the second metal member to plastically flow (or melt and solidify) at their interface to join the first metal member and the second metal member. The heat and pressure are preferably applied locally. The thermo-compression joining method employed in the present invention is a method in which heat is applied by the pressing member or another means while pressure is applied by the pressing member. Preferably, the method is a method in which heat and pressure are applied locally from the first metal member side with the pressing member, and more preferably, a friction stir spot joining method is employed.

As described in detail below, the friction stir spot joining method involves overlapping a first metal member and a second metal member, pressing the first metal member against a rotating tool acting as a pressing member while rotating, generating frictional heat, which causes the first metal member and the second metal member to plastically flow (or melt and solidify) relative to each other at their interface, thereby joining the first metal member and the second metal member.

The joining apparatus and joining method of the present invention, which employs a friction stir spot joining method, will be described in detail below with reference to the drawings. Please note that the various elements shown in the drawings are merely shown diagrammatically to aid in understanding the present invention, and that the dimensional ratios and appearances may differ from the actual objects. Note that the "vertical direction" used directly or indirectly in this specification corresponds to the direction corresponding to the vertical direction in the drawings. Also, unless otherwise specified, common symbols in these drawings indicate the same members, parts, dimensions, or areas.

In this specification, the term "cross-sectional view" refers to the shape of the object captured from a direction approximately perpendicular to the axial Y direction of the receiving member 17 described below, and includes cross-sectional views. In particular, the "cross-sectional view" may be based on the shape of the object captured along a plane parallel to the axial Y direction of the receiving member 17 and passing through said axis Y. The term "planar view" refers to the shape of the object captured from above or below along the axial Y direction of the receiving member 17, and includes plan views (top and bottom views).

[Metal member joining device using friction stir spot joining method]
The joining apparatus (friction stir spot joining apparatus) of the present invention will be specifically described with reference to the drawings.
Fig. 1 is a schematic diagram showing an example of a part of the friction stir spot welding apparatus of the present invention. The friction stir spot welding apparatus 1 shown in Fig. 1 is configured as an apparatus for friction stir spot welding a first metal member 11 and a second metal member 12, and includes a cylindrical rotating tool 16 as a pressing member that applies a pressing force to the first metal member.

The rotating tool 16 is a member that applies a pressing force to the first metal member 11 and generates heat by friction with the first metal member 11 due to its own rotation. More specifically, the rotating tool 16 rotates around the central axis X of the rotating tool 16 (see FIG. 2A) as indicated by arrow A1 and moves downward as indicated by arrow A2 by a driving source not shown, with respect to the workpiece 10 in which the first metal member 11 is placed on top and the second metal member 12 is placed on the bottom, as shown in the figure. At this time, the rotating tool 16 applies pressure to the pressing area P (the area to be pressed) on the surface of the first metal member 11. Frictional heat is generated by the pressing of the rotating tool 16, and this frictional heat is conducted to the second metal member 12, and the first metal member 11 and the second metal member 12 plastically flow (or melt and solidify) with each other at their interface. As a result, the first metal member and the second metal member are joined.

2A is an enlarged view of the tip of an example of the rotary tool 16. In FIG. 2A, the right half shows the appearance of the rotary tool 16, and the left half shows a cross section. As shown in FIG. 2A, the cylindrical rotary tool 16 has a pin portion 16a and a shoulder portion 16b supporting the pin portion at the tip (or tip side) (lower end or lower end side in FIG. 2A) that contacts the metal member. The shoulder portion 16b is a tip portion of the rotary tool 16 including the circular tip surface of the rotary tool 16. The pin portion 16a is a cylindrical portion with a smaller diameter than the shoulder portion 16b that protrudes outward (downward in FIG. 2A) from the circular tip surface of the rotary tool 16 on the central axis X of the rotary tool 16. The pin portion 16a can position the rotary tool 16 when the rotating rotary tool 16 is first brought into contact with the workpiece 10 and pressed. More specifically, the rotating tool 16 has a shoulder portion 16b including the circular tip surface of the rotating tool at the tip side (particularly the tip side on the receiving member 17 side), and a cylindrical pin portion 16 with a smaller diameter than the shoulder portion that protrudes outward from the circular tip surface of the rotating tool.

The material of the rotary tool 16 and the dimensions of each part are set mainly according to the type of metal of the first metal member 11 (or the first metal member 11 and the second metal member 12) pressed by the rotary tool 16. For example, when the first metal member 11 is made of aluminum or an aluminum alloy, the rotary tool 16 is made of tool steel (e.g., SKD61, etc.). Also, when the first metal member 11 is made of steel, the rotary tool 16 is made of silicon nitride or PCBN (cubic boron nitride sintered body). In these cases, the diameter D1 of the shoulder portion 16b is usually 5 to 20 mm, and from the viewpoint of further improving the joining strength, it is preferably set to 8 to 15 mm, more preferably 8 to 12 mm (especially 10 mm). The diameter D2 of the pin portion 16a is usually 0.2×D1 (mm) or more and 0.8×D1 (mm) or less with respect to the diameter D1 of the shoulder portion 16b, and is preferably set to 0.4×D1 (mm) or more and 0.6×D1 (mm) or less from the viewpoint of further improving the joining strength. The protruding length h of the pin portion 16a is usually 1.00×T1 (mm) or more and 0.95×(T1+T2) (mm) or less with respect to the thickness T1 of the first metal member 11 and the thickness T2 of the second metal member, and is preferably 1.10×T1 (mm) or more and 0.95×(T1+T2) (mm) or less from the viewpoint of further improving the joining strength, more preferably 1.20×T1 (mm) or more and 0.95×(T1+T2) (mm) or less, even more preferably 1.30×T1 (mm) or more and 0.95×(T1+T2) (mm).

A rotating tool 16' shown in FIG. 2B may be used. FIG. 2B is an enlarged view of the tip of another example of a rotating tool. In FIG. 2B, the rotating tool 16' is similar to the rotating tool 16 in FIG. 2A, except that the shoulder portion 16b has an inclined surface 16c that is indented in a mortar shape (cone shape). In FIG. 2B, the depth of the indentation becomes deeper as it approaches the pin portion 16a from the outer periphery of the shoulder portion 16b. As a result, the shoulder portion 16b of the rotating tool 16' comes into contact with the first metal member from the outer periphery during joining, which promotes heat conduction in the surface direction (e.g., horizontal plane direction), thereby achieving further improvement in joining strength. The inclination angle θ of the inclined surface 16c is usually 15° or less, preferably 1 to 15°, and more preferably 5 to 15°.

1 and 3A, a cylindrical receiving member 17 having the same diameter as the rotating tool 16 or a larger diameter than the rotating tool 16 is arranged coaxially with the rotating tool 16 below the rotating tool 16. For example, as shown in FIG. 3A, the rotating tool 16 and the receiving member 17 are installed so that the axis X of the rotating tool 16 and the axis Y of the receiving member 17 are arranged on the same straight line (for example, the same vertical line). The receiving member 17 is a member that directly supports the second metal member 12, and is moved upward as indicated by the arrow A3 with respect to the workpiece 10 by a driving source not shown in the figure. The upper end surface of the receiving member 17 abuts against the lower surface of the workpiece 10 (particularly the second metal member 12) at the latest by the time the rotating tool 16 starts pressing the workpiece 10 (particularly the first metal member 11). The receiving member 17 sandwiches the workpiece 10 between itself and the rotating tool 16, and supports the workpiece 10 from below against the pressing force during the pressing period by the rotating tool 16, that is, during friction stir spot welding. It should be noted that the receiving member 17 does not necessarily have to be moved in the direction of the arrow A3, and a method of moving the rotating tool 16 in the direction of the arrow A2 after the workpiece 10 is placed on the receiving member 17 can also be adopted. Figure 3A is a schematic cross-sectional view of a pressing member (particularly a rotating tool) and a receiving member according to a first embodiment used in the joining device of the present invention.

3A, the receiving member 17 has a recess 172 on the outer periphery of the surface portion 171 facing the pressing member (particularly the rotating tool) 16. The surface portion of the receiving member 17 facing the pressing member 16 refers to the portion (or area) 171 facing the pressing member 16 on the surface 170 (upper surface) of the receiving member 17 facing the pressing member 16. More specifically, the facing surface portion 171 refers to the portion (or area) of the facing surface 170 that overlaps with the pressing member 16 in a plan view. The facing surface 170 refers to the upper surface (particularly the flat surface) of the receiving member 17 that supports the workpiece 10 if the recess 172 is not formed.

The receiving member 17 has a recess on the outer periphery of such an opposing surface portion 171. In particular, as shown in FIG. 3A, the receiving member 17 has a recess 172 such that the outer periphery (particularly the outline) 1711 of the opposing surface portion 171 is located within the range of the recess 172 area in a plan view. The inside (or inner periphery) of the recess 172 on the opposing surface 170 of such a receiving member 17 is specifically referred to as the inner periphery 173.

The recess 172 is formed in a ring shape (particularly a circular ring shape) in a plan view on the opposing surface 170 of the receiving member 17 (see, for example, FIG. 1). Therefore, the recess 172 may have the form of a recessed groove that may also be called a "donut-shaped groove."

When the first metal member 11 and the second metal member 12 are joined by the mutual proximity of the pressing member 16 and the receiving member 17, a part of the second metal member 12 moves (or plastically flows) to the recess 172 as shown in FIG. 4A. Therefore, in the joined body obtained by joining, the movement (or plastic flow) of the second metal member toward the first metal member side is suppressed in the vicinity of the indentation 20 as shown in FIG. 5A and FIG. 5B. As a result, it is considered that the remaining thickness Tz of the first metal member can be secured relatively large, and therefore a sufficiently large joining strength can be obtained. The movement (or plastic flow) of the second metal member toward the first metal member side in the vicinity of the indentation 20 is also called "rolling up". "Plastic flow" refers to irreversible deformation (or irreversible flow) that occurs in a material (or substance) that has received a stress (or pressure) exceeding a certain limit. FIG. 4A is a schematic cross-sectional view for explaining an example of the indentation stirring process and the stirring maintenance process in the joining device and joining method of the present invention. FIG. 5A is a schematic cross-sectional view of an example of a bonded body obtained using the bonding apparatus and bonding method of the present invention. FIG. 5B is a schematic cross-sectional view of an example of a bonded body obtained using the bonding apparatus and bonding method of the present invention with a larger rotary tool penetration amount than that of the bonding shown in FIG. 5A.

If the receiving member 17 does not have a recess 172 on the outer periphery of the opposing surface portion 171 (see FIG. 3A), a sufficiently large joint strength cannot be obtained. In detail, if the receiving member does not have a recess on the outer periphery of the opposing surface portion, as shown in FIG. 6A, the second metal member 512 moves (or plastically flows) toward the first metal member 511 in the vicinity of the indentation 520, and the remaining thickness Tz of the first metal member 511 is reduced, so that a sufficiently large joint strength cannot be obtained. Therefore, if the amount of penetration of the pressing member 16 is reduced, as shown in FIG. 6B, the movement (or plastic flow) of the second metal member 512 toward the first metal member 511 is suppressed, and the reduction in the remaining thickness Tz of the first metal member 511 can be suppressed, but the first metal member and the second metal member are not sufficiently joined in the approximately horizontal direction Q, so that a sufficiently large joint strength cannot be obtained. On the other hand, when the penetration amount of the pressing member 16 is increased, as shown in Figures 6C and 6D, the second metal member 512 moves (or plastically flows) toward the first metal member 511 more, and the remaining thickness Tz of the first metal member 511 is further reduced, so that a sufficiently large joint strength cannot be obtained. Even if the receiving member has a recess on the opposing surface, if the recess 518 is formed on the inner periphery (or inner periphery or center) of the opposing surface rather than on the outer periphery, as shown in Figure 9, the presence of the recess 518 causes the first metal member 511 and the second metal member 512 to lower as a whole directly below the rotating tool 516. As a result, the remaining thickness Tz of the first metal member 511 is also reduced, and a sufficiently large joint strength cannot be obtained.

The inner peripheral dimension (or inner diameter dimension) E1 (see FIG. 3A) of the recess 172 in a cross-sectional view is D2 (mm) or more and D1 (mm) or less (particularly greater than D2 and less than D1), where D1 (mm) is the diameter of the shoulder portion 16b and D2 (mm) (D2<D1) of the pin portion 16a. From the viewpoint of further improving the joining strength, it is preferably 1.00×D2 (mm) or more and 1.50×D2 (mm) or less, more preferably 1.10×D2 (mm) or more and 1.40×D2 (mm) or less, and even more preferably 1.15×D2 (mm) or more and 1.35×D2 (mm) or less.

The outer peripheral dimension (or outer diameter dimension) E2 of the recess 172 in a cross-sectional view is greater than the diameter D1 (mm) of the shoulder portion 16b (e.g., 1.05×D1 (mm) or more and 2.00×D1 (mm) or less), and from the viewpoint of further improving the joining strength, is preferably 1.10×D1 (mm) or more and 1.40×D1 (mm) or less, more preferably 1.10×D1 (mm) or more and 1.20×D1 (mm) or less, and even more preferably 1.10×D1 (mm) or more and 1.15×D1 (mm) or less.

The width dimension w of the recess 172 in a cross-sectional view is not particularly limited as long as the second metal member 12 moves (or plastically flows) into the recess 172, and may be, for example, 0.10 x D1 (mm) or more (particularly 0.10 x D1 (mm) or more and 2.00 x D1 (mm) or less) relative to the diameter D1 (mm) of the shoulder portion 16b, and from the viewpoint of further improving the joining strength, is preferably 0.20 x D1 (mm) or more and 1.00 x D1 (mm) or less, more preferably 0.30 x D1 (mm) or more and 0.70 x D1 (mm) or less, and even more preferably 0.40 x D1 (mm) or more and 0.60 x D1 (mm) or less.

The depth dimension k of the recess 172 in the cross-sectional view is not particularly limited as long as the second metal member 12 moves (or plastically flows) into the recess 172, and may be, for example, 0.10 x T2 (mm) or more (particularly 0.10 x T2 (mm) or more and 2.00 x T2 (mm) or less) relative to the thickness T2 of the second metal member, and from the viewpoint of further improving the joining strength, is preferably 0.20 x T2 (mm) or more and 1.00 x T2 (mm) or less, more preferably 0.30 x T2 (mm) or more and 0.70 x T2 (mm) or less, and even more preferably 0.40 x T2 (mm) or more and 0.60 x T2 (mm) or less.

In cross-sectional view, the recess 172 has a substantially rectangular shape as shown in FIG. 3A, but is not limited thereto. For example, as shown in FIG. 3B, the recess 172 may have a sloping surface 1720 that is inclined in a cone shape in cross-sectional view. From the viewpoint of further improving the joining strength, the recess 172 preferably has a sloping surface 1720 that is inclined in a cone shape in cross-sectional view as shown in FIG. 3B. The inclination angle α of the sloping surface 1720 is usually 80° or less, preferably 1 to 45°, more preferably 10 to 45°, and even more preferably 20 to 40°. FIG. 3B is a schematic cross-sectional view of a receiving member according to a second embodiment used in the joining device of the present invention. The receiving member 17 shown in FIG. 3B is similar to the receiving member shown in FIG. 3A, except that the recess 172 has a sloping surface 1720.

The outer peripheral dimension (or outer diameter dimension) E3 of the receiving member 17 in a cross-sectional view is not particularly limited as long as it exceeds the outer peripheral dimension E2 of the recess 172. Specifically, the outer peripheral dimension E3 of the receiving member 17 in a cross-sectional view may be greater than E2 (mm) (e.g., 1.05 x E2 (mm) or more and 2.00 x E2 (mm) or less) relative to the outer peripheral dimension E2 of the recess 172, and may particularly be 1.10 x E2 (mm) or more and 1.40 x E2 (mm) or less.

As shown in FIG. 3C, the receiving member 17 may have a convex portion 1730 on the inner peripheral portion 173 arranged on the inner peripheral side of the concave portion 172 in a plan view. As a result, as shown in FIG. 4B, even with a relatively small penetration amount (d1+d2), the movement (or plastic flow) of the second metal member 12 toward the first metal member side can be suppressed. Therefore, the remaining thickness Tz of the first metal member 11 can be secured relatively large, and as a result, a sufficiently large joining strength can be obtained with good energy efficiency. FIG. 3C is a schematic cross-sectional view of a receiving member according to a third embodiment used in the joining device of the present invention. The receiving member 17 shown in FIG. 3C is similar to the receiving member shown in FIG. 3A, except that it has a convex portion 1730 on the inner peripheral portion 173.

The protrusion 1730 typically has a columnar shape such as a cylindrical shape, a triangular prism shape, or a square prism shape, or a truncated cone shape such as a truncated cone shape, a triangular pyramid shape, or a square pyramid shape. From the viewpoint of further improving energy efficiency and bonding strength, the protrusion 1730 preferably has a cylindrical shape or a truncated cone shape, and more preferably has a truncated cone shape.

The width dimension E4 (cross-sectional view) of the convex portion 1730 is usually 0.40 x E1 (mm) or more and 1.00 x E1 (mm) or less relative to the inner circumference dimension E1 of the concave portion, and from the viewpoint of further improving energy efficiency and joint strength, it is preferably 0.60 x E1 (mm) or more and 1.00 x E1 (mm) or less, more preferably 0.70 x E1 (mm) or more and 0.90 x E1 (mm) or less, and even more preferably 0.75 x E1 (mm) or more and 0.95 x E1 (mm) or less.

The height dimension m (cross-sectional view) of the convex portion 1730 is 0.10 x T2 (mm) or more and 1.00 x T2 (mm) or less, relative to the thickness T2 of the second metal member, and from the viewpoint of further improving energy efficiency and joint strength, is preferably 0.20 x T2 (mm) or more and 0.90 x T2 (mm) or less, more preferably 0.30 x T2 (mm) or more and 0.70 x T2 (mm) or less, and even more preferably 0.40 x T2 (mm) or more and 0.60 x T2 (mm) or less.

The inclination angle β (see FIG. 3C) of the side surface of the convex portion 1730 in a cross-sectional view is typically 80° or less (particularly 0° or more and 80° or less), and from the viewpoint of further improving energy efficiency and bonding strength, is preferably 0 to 45°, more preferably 20 to 40°, and even more preferably 25 to 35°.

From the viewpoint of further improving energy efficiency and joining strength, it is preferable that the receiving member 17 has an inclined surface 1720 in the recess 172 and a convex portion 1730 on the inner periphery 173 as shown in FIG. 3D. FIG. 3D is a schematic cross-sectional view of a receiving member according to a fourth embodiment used in the joining device of the present invention. The receiving member 17 shown in FIG. 3D is similar to the receiving member shown in FIG. 3A, except that it has an inclined surface 1720 in the recess 172 and a convex portion 1730 on the inner periphery 173.

It is preferable that the receiving member 17 is configured so that the depth of the recess 172 can be variably set. For example, the receiving member 17 shown in FIG. 3A is preferably a split fitting type receiving member 17' composed of a first tubular member 17a (particularly the first cylindrical member), a second tubular member 17b (particularly the second cylindrical member) having an outer diameter equal to the inner diameter of the first tubular member 17a, and a third solid member (particularly the third columnar member) having an outer diameter equal to the inner diameter of the second tubular member 17b, as shown in FIG. 3E. The first tubular member 17a (particularly the first cylindrical member) fits with the second tubular member 17b (particularly the second cylindrical member) (particularly its outer peripheral surface) on its inner peripheral surface, and the second tubular member 17b (particularly the second cylindrical member) fits with the third solid member (particularly the third columnar member) (particularly its outer peripheral surface) on its inner peripheral surface. By using such a receiving member 17', the depth dimension of the recess 172 can be easily changed, so that it is possible to accommodate various materials and dimensions of the first metal member and the second metal member without frequently replacing the receiving member. FIG. 3E is a schematic cross-sectional view of a receiving member according to a fifth embodiment used in the joining device of the present invention. The receiving member 17' shown in FIG. 3E is similar to the receiving member shown in FIG. 3A, except that it is divided into a first cylindrical member 17a, a second cylindrical member 17b, and a third solid member 17c.

The friction stir spot welding apparatus 1 typically includes a drive control device (not shown) that drives the pressing member (particularly the rotating tool) 16 and the receiving member 17 to move closer to each other. The drive control device controls the drive (particularly the pressing drive and/or the rotation drive, preferably the pressing drive and the rotation drive) of the pressing member (particularly the rotating tool) and the drive (particularly the up-down drive for vertical movement) of the receiving member 17.

When the receiving member 17 does not have a convex portion on the inner circumference 173, the drive control device can control the penetration amount d1 of the pressing member (particularly the rotating tool) 16. In this case, the penetration amount d1 (mm) of the pressing member (particularly the rotating tool) 16 is not particularly limited as long as the second metal member 12 moves (or plastic flows) into the recess 172, and is usually 0.80 x T1 (mm) or more and 1.90 x T1 (mm) or less (particularly 1.10 x T1 (mm) or more and 1.90 x T1 (mm) or less) with respect to the thickness T1 of the first metal member, and from the viewpoint of further improving the joining strength, it is preferably 1.30 x T1 (mm) or more and 1.90 x T1 (mm) or less, more preferably 1.40 x T1 (mm) or more and 1.85 x T1 (mm) or less, and even more preferably 1.50 x T1 (mm) or more and 1.80 x T1 (mm) or less. In this case, the drive control device controls the rotation tool to satisfy d1<T1+T2 (especially d1<T1+T2-0.5) so that the rotation tool does not penetrate the joint.

When the receiving member 17 has a convex portion on the inner circumference 173, the drive control device can control the total penetration amount d1 of the pressing member (particularly the rotating tool) 16 and the penetration amount d2 of the receiving member 17 (particularly the convex portion 1730). In this case, the total penetration amount (mm) of the penetration amount d1 of the pressing member (particularly the rotating tool) 16 and the penetration amount d2 of the receiving member 17 (particularly the convex portion 1730) is not particularly limited as long as movement (or plastic flow) of the second metal member 12 into the concave portion 172 occurs, and is usually 0.80 x T1 (mm) or more and 1.90 x T1 (mm) or less (particularly 1.10 x T1 (mm) or more and 1.90 x T1 (mm) or less) relative to the thickness T1 of the first metal member, and from the viewpoint of further improving the joining strength, is preferably 1.10 x T1 (mm) or more and 1.70 x T1 (mm) or less, more preferably 1.20 x T1 (mm) or more and 1.50 x T1 (mm) or less, and even more preferably 1.30 x T1 (mm) or more and 1.50 x T1 (mm) or less. In this case, the drive control device controls the rotation tool to satisfy d1+d2<T1+T2 (especially d1+d2<T1+T2-0.5) so that the rotation tool does not penetrate the joint.

The drive control device may employ a pressure control method that controls the pressure force and pressure time applied to the metal member by the rotating tool and the rotation speed, as described in detail below, or may employ a position control method that controls the coordinate position of the rotating tool, the holding time at a specific position, and the rotation speed.

Although not shown in FIG. 1, the friction stir spot welding apparatus 1 may be equipped with jigs such as spacers and clamps to fix the workpiece 10 in advance and prevent the metal member 11 from lifting up when the rotating tool 16 is pressed.

In FIG. 1 and the like, each of the first metal member 11 and the second metal member 12 has an overall shape that is generally flat, but is not limited to this. Each of the first metal member 11 and the second metal member 12 may have any shape as long as at least the portions that overlap each other have a generally flat shape. Both sides of the portions of the first metal member 11 and the second metal member 12 that overlap each other are usually made up of flat surfaces.

There are no particular limitations on the metal constituting each of the first metal member 11 and the second metal member 12, and any metal can be used. Among them, the following metals and alloys used in the automotive field are preferably used:
aluminum;
Aluminum alloys such as 5000 series and 6000 series;
steel;
Magnesium and its alloys;
Titanium and its alloys.

The metals constituting the first metal member 11 and the second metal member 12 are each independently preferably aluminum or an aluminum alloy, more preferably an aluminum alloy, from the viewpoint of further improving the joining strength.

The thickness T1 (see FIG. 4A) of the first metal member 11 is usually 1 mm or more, and from the viewpoint of further improving the joining strength, is preferably 1.5 mm or more (particularly 1.5 to 10 mm), more preferably 1.8 to 5 mm, even more preferably 1.8 to 3 mm, and most preferably 1.9 to 2.5 mm. The thickness T1 of the first metal member 11 may be the thickness (thickness before joining process) of the substantially flat plate-shaped portion of the first metal member 11 that is to be overlapped with the second metal member 12.

The thickness T2 of the second metal member 12 (see FIG. 4A) is typically 0.50×T1 (mm) or more (particularly 0.90×T1 (mm) or more and 5.00×T1 (mm) or less) relative to the thickness T1 of the first metal member, and may be 1.00×T1 (mm) or more and 2.00×T1 (mm) or less. The thickness T2 of the second metal member 12 may be the thickness T2 (thickness before joining process) of the approximately flat plate-shaped portion of the second metal member 12 that is overlapped with the first metal member 11.

[Method of joining metal members by friction stir spot joining method and joined body]
The method for joining metal members of the present invention uses the above-mentioned apparatus for joining metal members of the present invention. More specifically, in the thermocompression joining method, for example, as shown in Figures 4A and 4B, the first metal member 11 and the second metal member 12 are overlapped between the pressing member 16 (16') and the receiving member 17, and pressure is applied to the second metal member 12 by pressing from the first metal member side by the pressing member 16 (16'), and heat is applied to the first metal member 11 and the second metal member 12 to plastically flow (or melt and solidify) at their interface, thereby joining them. At this time, the receiving member 17 has a recess 172 on the outer periphery of the surface portion facing the pressing member 16 (16'), so that when the pressing member 16 (16') and the receiving member 17 are brought close to each other, a part of the second metal member 12 plastically flows into the recess 172.

As shown in Figures 5A and 5B, the joint formed by the joining method of the present invention has an indentation 20 from the first metal member side in the overlapping portion of the first metal member 11 and the second metal member 12, and is joined at their interface around the indentation 20. The indentation 20 is an indentation made by a pressing member (particularly a rotating tool) 16, and is an indentation depression that penetrates the first metal member from the surface of the first metal member 11 and reaches the second metal member 12. The joining is achieved at the interface between the first metal member 11 and the second metal member 12 around the indentation 20, and more specifically, the first metal member 11 and the second metal member 12 are mutually plastically flowed (or melted and solidified) at their interface. Such a joint has a raised portion 121 due to the plastic flow of the second metal member 12 on the surface of the second metal member 12 opposite to the first metal member 11 side. The formation of the raised portion 121 suppresses the movement (or plastic flow) of the second metal member toward the first metal member in the vicinity of the indentation 20. As a result, the remaining thickness Tz of the first metal member can be secured relatively large, which is believed to result in a sufficiently large joint strength.

The residual thickness Tz (cross-sectional view) of the first metal member in the joined body is usually 0.50 x T1 (mm) or more and 1.25 x T1 (mm) or less (particularly 0.50 x T1 (mm) or more and 0.90 x T1 (mm) or less), where T1 (mm) is the thickness of the first metal member, and from the viewpoint of further improving the joining strength, it is preferably 0.60 x T1 (mm) or more and 0.90 x T1 (mm), and more preferably 0.65 x T1 (mm) or more and 0.85 x T1 (mm).

The residual thickness Tz of the first metal member 11 is the thickness of the first metal member 11 near the indentation 20 in the cross-sectional view of the joint. In the present invention, the residual thickness Tz of the first metal member 11 is the thickness of the first metal member 11 in the thickness direction (i.e., the axial direction X of the pressing member 16 or the axial direction Y of the receiving member 17) passing through the apex M (see Figures 5A and 5B) that defines the maximum height of the raised portion 121 in the cross-sectional view. In the present invention, the residual thickness Tz of the first metal member 11 is the average value of the thickness of the first metal member 11 in the cross-sectional view of any 10 sheets. Mutual plastic flow (or melting and solidification) occurs near the indentation 20 in the first metal member 11 and the second metal member 12, but the interface (or boundary) between them can be observed.

The raised portion 121 is formed in the joining method described below, when the pressing member (particularly the rotating tool) 16 and the receiving member 17 approach each other, causing a part of the second metal member to plastically flow into the recess 172 of the receiving member 17. Thus, the raised portion 121 is disposed at a position corresponding to the recess 172 of the receiving member 17. The dimensions D1 and D2 of the pressing member (particularly the rotating tool) 16 can be determined from the indentation marks 20 in the joined body, and the dimensions E1, E2 and w of the receiving member 17 can be determined from the spacing and dimensions of the indentation marks 20. Therefore, the arrangement of the raised portion 121 can be expressed by the same rules as the arrangement of the recess 172 of the receiving member 17.

The height n of the raised portion 121 is usually 0.10 x T2 (mm) or more and 0.90 x T2 (mm) or less, where T2 (mm) is the thickness of the second metal member 12, and from the viewpoint of further improving the joining strength, it is preferably 0.20 x T2 (mm) or more and 0.80 x T2 (mm) or less, and more preferably 0.40 x T2 (mm) or more and 0.60 x T2 (mm) or less.

A method for joining metal members by the friction stir spot joining method according to the present invention includes at least the following steps:
a first step of overlapping the first metal member 11 and the second metal member 12; and a second step of pressing the rotating tool 16 against the first metal member 11 while rotating the rotating tool 16 to generate frictional heat, which causes the first metal member 11 and the second metal member 12 to plastically flow (or melt and solidify) with each other at their interface, thereby joining the first metal member 11 and the second metal member 12:
It includes.

In the first step, as shown in FIG. 1, the first metal member 11 and the second metal member 12 are overlapped at the desired joining location.

In the second step, the drive of the rotating tool is controlled so that the first metal member 11 and the second metal member 12 plastically flow (or melt) relative to each other at their interface near the rotating tool. In the second step, as described above, a pressure control method is adopted that controls the pressure force, pressure time, and rotation speed of the rotating tool, or a position control method is adopted that controls the coordinate position of the rotating tool, the holding time at a specific position, and the rotation speed. Below, the second step that adopts the pressure control method is described as the first embodiment, and the second step that adopts the position control method is described as the second embodiment.

<First embodiment: Pressure control method>
In the second step of this embodiment, it is preferable to at least perform a pushing and stirring process C2 in which the rotating tool 16 is pushed in from the first metal member 11 side to a depth reaching the boundary surface between the first metal member 11 and the second metal member 12.

In the second step of this embodiment, it is preferable to perform a preheating step C1 before the pushing and stirring step, in which the tip of the rotating tool 16 is in contact with the surface of the first metal member 11 and the rotating tool 16 is rotated, but this is not necessarily required.

After the pushing-in stirring process, it is preferable to perform a stirring maintenance process C3 in which the rotating tool 16 continues to rotate at the position where the rotating tool 16 was inserted in the pushing-in stirring process, but this process does not necessarily have to be performed.

These steps in this embodiment are described in detail below.

(Preheating process C1)
The preheating step C1 is a step in which the rotating tool 16 and the receiving member 17 are brought close to each other, so that the tip portion of the rotating tool 16 (or the "pin portion 16a" or the "pin portion 16a and shoulder portion 16b") is brought into contact with the surface of the first metal member 11, and the rotating tool 16 is rotated at a predetermined rotation speed with a first pressing force for a first pressing time.

Specifically, in the preheating process C1, frictional heat is generated on the surface of the first metal member 11 by the pressing of the rotating tool 16. The frictional heat is transmitted to the inside of the first metal member 11, and the range of the pressing area P (the area pressed by the rotating tool 16) of the first metal member 11 and the area adjacent to the pressing area P are preheated. This makes it easier to press the rotating tool 16 into the metal member 11 in the next pressing and stirring process C2.

The first pressure and the first pressurizing time in the preheating step C1 are set from the viewpoint of ease of pressing the rotary tool 16 and ease of plastic flow of the second metal member 12, as well as from the viewpoint of productivity, and the values vary depending on, for example, the rotation speed of the rotary tool 16, the thickness and type of material of the first metal member 11 and the second metal member 12, etc. For example, when using the first metal member 11 and the second metal member 12 having a thickness of 1.5 mm or more and 3 mm or less and made of an aluminum alloy, the first pressure in the preheating step C1 is preferably 600 N or more and less than 1300 N. The first pressurizing time is preferably 0.5 seconds or more and 2.0 seconds or less. The rotation speed of the rotary tool is preferably 2000 rpm or more and 4000 rpm or less.

The amount of heat input in this process is determined by the magnitude of the first pressure, the length of time for which the first pressure is applied, and the rotation speed of the rotating tool.

(Intrusion stirring process C2)
In the thrust stirring process C2, the rotary tool 16 and the receiving member 17 are brought close to each other, so that the rotary tool 16 is thrust into the first metal member 11 and the second metal member 12, as shown in FIGS. 4A and 4B. When the thrust stirring process C2 is performed following the preheating process C1, the rotary tool 16 and the receiving member 17 are brought even closer to each other, so that the rotary tool 16 is thrust into the first metal member 11 and the second metal member 12, as shown in FIGS. 4A and 4B. This allows the rotary tool 16 to advance to a depth that reaches the boundary surface between the first metal member 11 and the second metal member 12. At this time, in detail, it is preferable to thrust the rotary tool 16 (particularly the pin portion) to a depth that reaches the boundary surface between the first metal member 11 and the second metal member 12, but does not reach the bottom surface of the second metal member 12, as shown in FIGS. 4A and 4B. This can promote the plastic flow of the second metal member 12 into the recess 172 of the receiving member 17.

The pressing of the rotary tool (particularly the pin portion) is performed by a drive control device. The depth that reaches the boundary surface with the second metal member 12 but does not reach the bottom surface of the second metal member 12 refers to the following penetration amount:
- the penetration amount (d1) of the above-mentioned pressing member (particularly the rotating tool) 16 when the receiving member 17 does not have a convex portion on the inner circumference 173; and - the total penetration amount (d1 + d2) of the penetration amount d1 of the above-mentioned pressing member (particularly the rotating tool) 16 and the penetration amount d2 of the receiving member 17 (particularly the convex portion 1730) when the receiving member 17 has a convex portion on the inner circumference 173.

In the pushing and mixing process C2, the rotating tool 16 is rotated at a predetermined rotation speed with a second pressure force greater than the first pressure force for a second pressure time shorter than the first pressure time.

In the pushing stirring process C2, the applied pressure is greater than that in the preheating process C1, and the rotating tool 16 is pushed into the first metal member 11 and the second metal member 12. That is, the rotating tool 16 penetrates deeply into the first metal member 11 and reaches the second metal member 12. Preferably, this pushing of the rotating tool 16 promotes the plastic flow of the second metal member 12 into the recess 172 of the receiving member 17. The pushing of the rotating tool 16 is performed so that the rotating tool 16 does not penetrate the first metal member 11 and the second metal member 12. When the rotating tool 16 penetrates the first metal member 11 and the second metal member 12, the joint is in a perforated state where the holes through which the rotating tool 16 passed are opened, resulting in poor joining.

The second pressure and the second pressurizing time in the pushing-in stirring process C2 are set from the viewpoint of avoiding the above-mentioned hole formation in the joint and from the viewpoint of bringing the rotating tool 16 as close as possible to the bottom surface of the second metal member 12, and the values vary depending on, for example, the rotation speed of the rotating tool 16, the thickness and the type of material of the first metal member 11 and the second metal member 12. For example, when using the first metal member 11 and the second metal member 12 having a thickness of 1.5 mm or more and 3 mm or less and made of an aluminum alloy, the second pressure in the pushing-in stirring process C2 is preferably 1300 N or more and less than 2200 N. The second pressurizing time is preferably 0.5 seconds or more and 10.0 seconds or less. The rotation speed of the rotating tool is preferably 2000 rpm or more and 4000 rpm or less.

The amount of heat input in this process is determined by the magnitude of the second pressure, the length of time for which the second pressure is applied, and the rotation speed of the rotating tool.

(Stirring maintenance step C3)
The stirring maintaining step C3 is a step of continuing the rotation operation of the rotating tool 16 at the position where the rotating tool 16 has advanced to the above-mentioned depth (this position is called the "reference position") by stopping the mutual approach of the rotating tool 16 and the receiving member 17, as also shown in Figures 4A and 4B. In the stirring maintaining step C3, the rotating tool 16 is rotated at a predetermined rotation speed with a third pressing force smaller than the first pressing force for a third pressing time longer than the first pressing time.

In the stirring maintenance process C3, the applied pressure is smaller than in the preheating process C1 (and of course smaller than in the pushing stirring process C2), so that the rotating tool 16 is maintained at approximately the reference position. Since the rotating operation of the rotating tool 16 continues at this reference position, a large amount of frictional heat is generated, and most of the generated frictional heat is transferred to the second metal member 12. This further promotes plastic flow into the recess 172 of the second metal member 12.

The third pressure force and the third pressurizing time in the stirring maintenance process C3 are set from the viewpoint of further promoting plastic flow into the recess 172 of the second metal member 12 and productivity, and the values vary depending on, for example, the rotation speed of the rotating tool 16, the thickness of the first metal member 11 and the second metal member 12, and the type of material. For example, when using the first metal member 11 and the second metal member 12 having a thickness of 1.5 mm or more and 3 mm or less and made of an aluminum alloy, the third pressure force in the stirring maintenance process C3 is preferably 100 N or more and less than 1200 N. The third pressurizing time is preferably 1.0 second or more and 10.0 seconds or less. The rotation speed of the rotating tool is preferably 2000 rpm or more and 4000 rpm or less.

The amount of heat input in this process is determined by the magnitude of the third pressure, the length of time for which the third pressure is applied, and the rotation speed of the rotating tool.

In this embodiment, after the stirring maintenance step C3 is performed, the pressing member 16 is usually separated from the joined body and left to cool. Cooling may also be forced from the outside.

<Second embodiment: position control method>
In the second step of this embodiment, it is also preferable to at least perform a pushing and stirring process C2 in which the rotating tool 16 is pushed into the first metal member 11 and the second metal member 12 to a depth reaching the boundary surface between the first metal member 11 and the second metal member 12.

In the second step of this embodiment, a preheating step C1 may be performed before the thrust stirring step, in which the rotating tool 16 is rotated with only the tip of the rotating tool 16 in contact with the surface of the metal member 11, but this is not necessary because a position control method is adopted.

After the pushing-in stirring process, it is preferable to perform a stirring maintenance process C3 in which the rotating tool 16 continues to rotate at the position where the rotating tool 16 was inserted in the pushing-in stirring process, but this process does not necessarily have to be performed.

These steps in this embodiment are described in detail below.

(Intrusion stirring process C2)
The thrust stirring step C2 of this embodiment is the same as the thrust stirring step C2 of the first embodiment, except that a position control method is adopted. More specifically, in the thrust stirring step C2 of this embodiment, as shown in Figures 4A and 4B, the rotary tool 16 is rotated at a predetermined rotation speed and advanced to a predetermined depth. In the thrust stirring step C2, the rotary tool 16 is advanced to a predetermined depth, thereby causing a part of the second metal member 12 to plastically flow into the recess 172 of the receiving member 17.

The specified depth is the same as the "depth that reaches the boundary surface between the first metal member 11 and the second metal member 12" in the pressure control type thrust mixing process C2, and preferably is the same as the "depth that reaches the boundary surface between the first metal member 11 and the second metal member 12, but does not reach the bottom surface of the second metal member 12."

In this embodiment, the rotary tool 16 is pressed in such a way that the rotary tool 16 does not penetrate the first metal member 11 and the second metal member 12. If the rotary tool 16 penetrates the first metal member 11 and the second metal member 12, the joint will have a hole where the rotary tool 16 passed through, resulting in poor joining.

When the rotating tool 16 has penetrated to a predetermined depth, the pushing movement of the rotating tool 16 is stopped.

The rotation speed of the rotating tool should preferably be between 2000 rpm and 4000 rpm.

The amount of heat input in this process is determined by the penetration time of the rotating tool and the rotation speed of the rotating tool, and the penetration time of the rotating tool is determined by the penetration amount and penetration speed of the rotating tool.

The entry speed of the rotating tool in this process is not particularly limited, but is preferably, for example, 10 to 100 mm/min, and more preferably, 20 to 50 mm/min.

(Stirring maintenance step C3)
The stirring maintenance step C3 of this embodiment is similar to the stirring maintenance step C3 of the first embodiment, except that pressure is not applied to the first metal member 11 and the second metal member 12 because a position control method is adopted. As shown in Figures 4A and 4B, without applying pressure to the first metal member 11 and the second metal member 12 by the rotating tool 16, the rotating operation of the rotating tool 16 is continued at the position where the rotating tool 16 entered in the thrust stirring step C2. As a result, a large amount of frictional heat is generated, and most of the generated frictional heat is transferred to the second metal member 12. Therefore, the plastic flow into the recess 172 of the second metal member 12 is further promoted.

In the stirring maintenance process C3, the rotating tool 16 is held in the above-mentioned predetermined position for a predetermined time and rotated at a predetermined rotation speed.

The holding time of the stirring maintenance process C3 is set from the viewpoint of further promoting the plastic flow into the recess 172 of the second metal member 12 and productivity, and the value varies depending on, for example, the rotation speed of the rotating tool 16, the thickness of the first metal member 11 and the second metal member 12, and the type of material. For example, when using the first metal member 11 and the second metal member 12 having a thickness of 1.5 mm to 3 mm and made of an aluminum alloy, the holding time in the stirring maintenance process C3 is preferably 0 seconds or more and less than 10.0 seconds. The rotation speed of the rotating tool is preferably 2000 rpm or more and 4000 rpm or less. A holding time of 0 seconds means that the stirring maintenance process C3 does not need to be performed in this embodiment. This is because the heat input can be adjusted only by the entry time of the rotating tool in the above-mentioned pushing stirring process C2. In particular, when the entry amount, entry speed, and rotation speed of the rotating tool in the above-mentioned pushing stirring process C2 are within the above-mentioned ranges, the holding time in this stirring maintenance process C3 is usually 0 seconds or more and less than 5.0 seconds.

The amount of heat input in this process is determined by the length of the holding time and the rotation speed of the rotating tool.
In particular, the longer the holding time is within the above range, the more the plastic flow of the second metal member 12 is promoted.

In this embodiment, after the stirring maintenance step C3 is performed, the pressing member 16 is usually separated from the joined body and left to cool. Cooling may also be forced from the outside.

[Metal Members]
As the first metal member and the second metal member, a flat plate-like member (length 100 mm x width 30 mm x thickness 2.0 mm (=T1=T2)) made of a 6000 series aluminum alloy was used.

[Rotate Tool]
A rotary tool 16' shown in FIG. 2B (D1=10 mm, D2=5 mm (=0.5×D1), h=2.8 mm (=1.40×T1), θ=14°; made of tool steel) was used.

[Receiving member]
The following three types of receiving members were used.
(1) A receiving member 17 shown in FIG. 3B (E1=6.3 mm, E2=11.3 mm, E3=16.0 mm, w=2.5 mm, k=1.0 mm, α=30°; made of tool steel) was used.
(2) A receiving member 17 shown in FIG. 3D (E1 = 6.3 mm, E2 = 11.3 mm, E3 = 16.0 mm, E4 = 5.0 mm (= 0.79 × E1), w = 2.5 mm, k = m = 1.0 mm (= 0.50 × T2), α = β = 30°; made of tool steel) was used.
(3) A receiving member similar to receiving member 17 shown in Fig. 3A was used, except that it did not have recess 172. The surface (upper surface) of the receiving member facing the rotating tool was flat. Hereinafter, such a receiving member will be referred to as a "flat receiving member."

[Example A1] (Position control method)
Using a rotary tool 16' shown in FIG. 2B and a receiving member 17 shown in FIG. 3B, a bonded body of a first metal member 11 and a second metal member 12 was produced by the following method.
First step:
An end portion of the first metal member 11 and an end portion of the second metal member 12 were overlapped as shown in FIG.

Second step:
4A, the rotating tool 16' was pressed into the first metal member 11 and the second metal member 12 at a pressing speed of 30 mm/min so that the pressing amount (d1) of the rotating tool 16' was 3.15 mm (d1=1.58×T1) (pressing and stirring process C2: tool rotation speed 3000 rpm).
Thereafter, the rotary tool 16′ was separated from the first metal member 11 and the second metal member 12, and the assembly was allowed to cool, thereby obtaining a bonded body. The height n of the raised portion 121 and the remaining thickness Tz of the first metal member 11 in a cross-sectional view were each measured at any 10 points, and the average value was calculated.
Example A1: n = 0.9 mm, Tz = 1.7 mm

[Examples A2 to A3]
In the thrust stirring process C2, the thrust tool 16' was thrust so that the penetration amount (d1) of the thrust tool 16' was 3.35 mm (= 1.68 x T1) or 3.50 mm (= 1.75 x T1), but the same method as in Example A1 was used to obtain a bonded body of the first metal member and the second metal member. The height n of the raised portion 121 and the remaining thickness Tz of the first metal member 11 in a cross-sectional view were each measured at any 10 points, and the average value was calculated.
Example A2: n = 1.0 mm, Tz = 1.5 mm
Example A3: n = 1.0 mm, Tz = 1.3 mm

[Example B1] (Position control method)
A joint body of the first metal member and the second metal member was obtained by the same method as in Example A1, except that the rotating tool 16' shown in Fig. 2B and the receiving member 17 shown in Fig. 3D were used, and in the pushing and stirring process C2, the rotating tool 16' was pushed in so that the total penetration amount (d1 + d2) of the rotating tool 16' and the receiving member was 2.75 mm (= 1.38 × T1) as shown in Fig. 4B. The height n of the raised portion 121 and the remaining thickness Tz of the first metal member 11 in a cross-sectional view were each measured at any 10 points, and the average value was calculated.
Example B1: n = 0.5 mm, Tz = 1.5 mm

[Comparative Examples C1 to C5] (Position Control Method)
A joint body of the first metal member and the second metal member was obtained by the same method as in Example A1, except that the rotary tool 16' and the flat receiving member shown in Figure 2B were used, and the rotary tool 16' was pushed in so that the penetration amount (d1) of the rotary tool 16' was 2.50 mm, 2.65 mm, 2.80 mm, 3.00 mm, or 3.10 mm in the pushing and stirring process C2. The height n of the raised portion and the remaining thickness Tz of the first metal member 11 in a cross-sectional view were each measured at any 10 points, and the average value was calculated.
Comparative example C1; n=0mm, Tz=1.5mm
Comparative example C2; n=0mm, Tz=1.3mm
Comparative example C3; n=0mm, Tz=1.2mm
Comparative example C4; n=0mm, Tz=1.0mm
Comparative example C5; n=0mm, Tz=0.9mm

[Bonding strength]
As shown in Fig. 7, the joint of the first metal member 11 and the second metal member 12 was placed in a jig 100. The jig 100 was configured so that a downward force was applied to the upper end of the second metal member 12 by pulling the jig 100 downward. By fixing the jig 100 and pulling the first metal member 11 upward, a downward force was applied to the upper end of the second metal member 12, and the shear strength S (maximum tensile shear load) of the joint was measured without being affected by the base material strength of the second metal member 12.
The relationship between the measured value and the tool penetration amount is shown in the graph of FIG.

The joined bodies of Examples A1 to A3 and B1 obtained using the joining apparatus and joining method of the present invention exhibited significantly improved joining strength compared to the joined bodies of Comparative Examples C1 to C5 obtained using a planar receiving member having no recess.
The joint of Example B1, which has a recess and a protrusion on the inner periphery thereof, exhibited approximately the same joint strength with a smaller tool insertion depth than the joints of Examples A1 to A3, which have a recess but no protrusion on the inner periphery thereof. This is believed to be based on the following mechanism. The receiving member having a protrusion on the inner periphery promotes plastic flow into the recess of the second metal member. Therefore, approximately the same remaining thickness Tz is secured with a smaller tool insertion depth, and as a result, approximately the same joint strength is exhibited.

The joining device and joining method of the present invention are useful for joining metal components in fields such as automobiles, railway vehicles, aircraft, and home appliances.

1: Friction stir spot welding apparatus 10: Work 11: First metal member 12: Second metal member 121: Protuberance 16: Rotating tool 17: 17': Receiving member 170: Surface of receiving member facing pressing member 171: Facing surface 172: Recess 1720: Inclined surface of recess 173: Inner circumference 1730: Convex 100: Jig for measuring joining strength P: Pressing area (area to be pressed)

Claims (30)

A metal member joining device for joining two metal members, comprising:
a pressing member that applies a pressing force to a first metal member of the two metal members;
a receiving member that directly supports a second metal member of the two metal members; and a drive control device that drives the pressing member and the receiving member to approach each other,
The receiving member has a recess on an outer periphery of a surface portion facing the pressing member,
the receiving member has a protrusion on an inner periphery that is disposed on an inner periphery side of the recess in a plan view,
A width dimension E4 of the convex portion is equal to or greater than 0.40×E1 (mm) and equal to or less than 1.00×E1 (mm) with respect to an inner periphery dimension E1 of the concave portion,
A metal member joining device , wherein a height dimension m of the convex portion is equal to or greater than 0.10 x T2 (mm) and equal to or less than 1.00 x T2 (mm), where T2 is a thickness of the second metal member . the pressing member is a rotary tool that generates heat by friction with a metal member caused by its own rotation,
the rotary tool has, at a tip side thereof, a shoulder portion including a circular tip surface of the rotary tool, and a cylindrical pin portion protruding outward from the circular tip surface of the rotary tool and having a smaller diameter than the shoulder portion;
an inner peripheral dimension E1 of the recess is equal to or greater than D2 (mm) and equal to or less than D1 (mm), where D1 (mm) is a diameter of the shoulder portion and D2 (mm) is a diameter of the pin portion;
2. The apparatus for joining metal members according to claim 1, wherein an outer circumferential dimension E2 of the recess is greater than a diameter D1 (mm) of the shoulder portion. 3. The metal member joining apparatus according to claim 1, wherein a depth dimension k of the recess is equal to or greater than 0.10 x T2 (mm), where T2 is a thickness of the second metal member. The metal member joining device according to any one of claims 1 to 3, wherein the recess has an inclined surface that is inclined in a cone shape in cross section. The metal member joining device according to any one of claims 1 to 4, wherein the protruding length h of the pin portion is 1.00 x T1 (mm) or more and 0.95 x (T1 + T2) (mm) or less with respect to the thickness T1 of the first metal member. The metal member joining device according to any one of claims 1 to 5, wherein the thickness T1 of the first metal member is 1.0 mm or more. The metal member joining device according to any one of claims 1 to 6, wherein the drive control device controls the drive of the pressing member and the receiving member so that the penetration amount d1 of the pressing member is 0.80 x T1 (mm) or more and 1.90 x T1 (mm) or less with respect to the thickness T1 of the first metal member. The joining device for metal members according to any one of claims 1 to 7, wherein the drive control device controls the drive of the pressing member and the receiving member so that the total penetration amount d1 of the pressing member and the penetration amount d2 of the receiving member is 0.80 x T1 (mm) or more and 1.90 x T1 (mm) or less with respect to the thickness T1 of the first metal member. The metal member joining apparatus according to any one of claims 1 to 8 , wherein the first metal member and the second metal member are each independently made of aluminum or an aluminum alloy. The joining apparatus for metal members according to any one of claims 1 to 9 , wherein the joining apparatus is a friction stir spot joining apparatus. A method for joining metal members by a thermocompression joining method, comprising: overlapping a first metal member and a second metal member between a pressing member and a receiving member; applying pressure to the second metal member by pressing the first metal member from the side of the pressing member; and applying heat to the first metal member and the second metal member to cause mutual plastic flow at an interface between the first metal member and the second metal member,
The receiving member has a recess on an outer periphery of a surface portion facing the pressing member,
the pressing member and the receiving member are brought close to each other, and a part of the second metal member is plastically flowed into the recess ;
The thermocompression bonding method comprises:
A first step of overlapping a first metal member and a second metal member; and
A second step of pressing the rotating tool against the first metal member while rotating the rotating tool as a pressing member to generate frictional heat, and causing the first metal member and the second metal member to plastically flow relative to each other at their interface by the frictional heat, thereby joining the first metal member and the second metal member.
A friction stir spot joining method comprising:
the receiving member has a protrusion on an inner periphery that is disposed on an inner periphery side of the recess in a plan view,
The second step is
a thrust stirring step of thrusting the rotary tool from the first metal member side to a depth reaching a boundary surface between the first metal member and the second metal member,
In the thrust stirring process, the rotating tool is thrust into the first metal member and the second metal member until the total thrust of the thrust member d1 and the thrust member d2 becomes 1.10 x T1 (mm) or more and 1.90 x T1 (mm) or less, where T1 is the thickness of the first metal member . A metal member joining device for joining two metal members, comprising:
a pressing member that applies a pressing force to a first metal member of the two metal members;
a support member that directly supports the second metal member of the two metal members; and
A drive control device that drives the pressing member and the receiving member to approach each other.
Including,
The method for joining metal members according to claim 11 , wherein the receiving member has a recess on an outer periphery of a surface portion facing the pressing member. In the joining device,
the pressing member is a rotary tool that generates heat by friction with a metal member caused by its own rotation,
the rotary tool has, at a tip side thereof, a shoulder portion including a circular tip surface of the rotary tool, and a cylindrical pin portion protruding outward from the circular tip surface of the rotary tool and having a smaller diameter than the shoulder portion;
an inner peripheral dimension E1 of the recess is equal to or greater than D2 (mm) and equal to or less than D1 (mm), where D1 (mm) is a diameter of the shoulder portion and D2 (mm) is a diameter of the pin portion;
The method for joining metal members according to claim 12 , wherein a peripheral dimension E2 of the recess is greater than a diameter D1 (mm) of the shoulder portion. In the joining device,
14. The method for joining metal members according to claim 12 or 13, wherein a depth dimension k of the recess is equal to or greater than 0.10 x T2 (mm), where T2 is a thickness of the second metal member. In the joining device,
The method for joining metal members according to any one of claims 12 to 14, wherein the recess has an inclined surface that is inclined into a cone shape in cross section. In the joining device,
The method for joining metal members according to any one of claims 12 to 15, wherein the protruding length h of the pin portion is 1.00 x T1 (mm) or more and 0.95 x (T1 + T2) (mm) or less with respect to the thickness T1 of the first metal member. In the joining device,
The method for joining metal members according to any one of claims 12 to 16, wherein the thickness T1 of the first metal member is 1.0 mm or more. In the joining device,
The method for joining metal members according to any one of claims 12 to 17, wherein the drive control device controls the drive of the pressing member and the receiving member so that a penetration amount d1 of the pressing member is 0.80 x T1 (mm) or more and 1.90 x T1 (mm) or less with respect to a thickness T1 of the first metal member. In the joining device,
the receiving member has a protrusion on an inner periphery that is disposed on an inner periphery side of the recess in a plan view,
A width dimension E4 of the convex portion is equal to or greater than 0.40×E1 (mm) and equal to or less than 1.00×E1 (mm) with respect to an inner periphery dimension E1 of the concave portion,
A method for joining metal members according to any one of claims 12 to 18, wherein the height dimension m of the convex portion is 0.10 x T2 (mm) or more and 1.00 x T2 (mm) or less with respect to the thickness T2 of the second metal member. In the joining device,
20. The method for joining metal members according to claim 19, wherein the drive control device controls the drive of the pressing member and the receiving member so that a total penetration amount d1 of the pressing member and a penetration amount d2 of the receiving member is equal to or greater than 0.80 × T1 (mm) and equal to or less than 1.90 × T1 (mm) relative to a thickness T1 of the first metal member. In the joining device,
The method for joining metal members according to any one of claims 12 to 20, wherein the first metal member and the second metal member are each independently made of aluminum or an aluminum alloy. The method for joining metal members according to any one of claims 12 to 21, wherein the joining apparatus is a friction stir spot joining apparatus. A pressure control method is adopted in the second step;
The method for joining metal members according to any one of claims 12 to 22, further comprising controlling the pressure, pressure time and rotation speed of the rotary tool applied to the first metal member. A position control method is adopted in the second step;
The method for joining metal members according to any one of claims 12 to 22 , wherein a coordinate position of the rotating tool, a holding time at a specific position, and a rotation speed are controlled. A method for joining metal members by a thermocompression joining method, comprising: overlapping a first metal member and a second metal member between a pressing member and a receiving member; applying pressure to the second metal member by pressing the first metal member from the side of the pressing member; and applying heat to the first metal member and the second metal member to cause mutual plastic flow at an interface between the first metal member and the second metal member,
The receiving member has a recess on an outer periphery of a surface portion facing the pressing member,
the pressing member and the receiving member are brought close to each other, and a part of the second metal member is plastically flowed into the recess ;
A method for joining metal members, comprising using the apparatus for joining metal members according to any one of claims 1 to 10 . The thermocompression bonding method comprises:
26. The method for joining metal members according to claim 25, which is a friction stir spot joining method comprising: a first step of overlapping the first metal member and the second metal member; and a second step of pressing the first metal member against the rotating tool as a pressing member while rotating the rotating tool to generate frictional heat, and causing the first metal member and the second metal member to plastically flow relative to each other at an interface between them due to the frictional heat, thereby joining the first metal member and the second metal member. A pressure control method is adopted in the second step;
The method for joining metal members according to claim 26 , further comprising controlling a pressure, a pressure time and a rotation speed of the rotary tool applied to the first metal member. A position control method is adopted in the second step;
The method for joining metal members according to claim 26 , further comprising controlling a coordinate position of the rotating tool, a holding time at a specific position, and a rotation speed of the rotating tool. The second step is
a thrust stirring step of thrusting the rotary tool from the first metal member side to a depth reaching a boundary surface between the first metal member and the second metal member,
The method for joining metal members according to any one of claims 26 to 28, wherein in the thrust stirring process, the rotating tool is thrust into the first metal member and the second metal member until a thrust d1 of the pressing member becomes 1.10 x T1 (mm) or more and 1.90 x T1 (mm) or less , where T1 is a thickness of the first metal member. the receiving member has a protrusion on an inner periphery that is disposed on an inner periphery side of the recess in a plan view,
The second step is
a thrust stirring step of thrusting the rotary tool from the first metal member side to a depth reaching a boundary surface between the first metal member and the second metal member,
The method for joining metal members according to any one of claims 26 to 28, wherein in the thrust stirring process, the rotating tool is thrust into the first metal member and the second metal member until a total thrust of the thrust member d1 and the thrust member d2 becomes equal to or greater than 1.10 x T1 (mm) and equal to or less than 1.90 x T1 (mm), where T1 is the thickness of the first metal member.

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