Apparatus and method for joining metal members

Abstract

To provide a metallic component joining device which can easily achieve joining of metallic components with a sufficient strength.SOLUTION: A metallic component joining device for joining two metallic components 11, 12 includes: a pressing component 16 which applies pressing force to the first metallic component 11 of the two metallic components; and a receiver component 17 which directly supports the second metallic component 12 of the two metallic components; and a drive control device which so drives the pressing component and the receiver component as to close to each other. The receiver component 16 has a recess 172 on an outer periphery of a surface facing the pressing component.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for joining metal members (particularly two metal members), a method for joining, and a joined body. [Background technology]

[0002] Conventionally, in the fields of automobiles, railway vehicles, aircraft, etc., a so-called friction stir spot welding (FSSW) method 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 from the side to generate frictional heat, and the first metal member and the second metal member are plastically flowed (or melted and solidified) by this frictional heat, thereby joining the first metal member and the second metal member.

[0003] In a joining apparatus using such a friction stir spot joining method, a receiving member having a flat surface facing the rotary tool is used, and the second metal member is directly supported by this flat surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-283317 A Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors of the present invention found that when the metal members are joined by the conventional device, sufficient joining strength is not obtained. In detail, when a receiving member having a flat surface on the rotating tool side (i.e., a supporting surface of the second metal member) is used, 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 mark 520, and the remaining thickness Tz of the first metal member 511 is reduced, so that a sufficiently large joining strength is not obtained. Therefore, when the amount of penetration of the pressing member 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 substantially horizontal direction Q, so that a sufficiently large joining strength is 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 having no 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 by 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 by 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 by a larger rotation tool penetration amount than that in the joining of FIG. 6C.

[0006] On the other hand, as shown in Fig. 9, a technique has been disclosed in which a recess 518 is provided in the center of the surface of a 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 a rotary tool 516 (Patent Document 1). However, when such a receiving member 517 is used, the presence of the recess 518 causes the portions of the first metal member 511 and the second metal member 512 directly below the rotary tool 516 to drop 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).

[0007] An object of the present invention is to provide an apparatus and method for joining metal members, which can easily achieve joining of metal members with sufficient strength. [Means for solving the problem]

[0008] 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 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. A joining device for metal members, comprising: 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.

[0009] The present invention also provides A method for joining metal members by a thermocompression joining method, comprising the steps of: 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.

[0010] 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. Effect of the Invention

[0011] According to the joining apparatus and joining method of the present invention, joining of metal members can be easily achieved with sufficient strength. [Brief description of the drawings]

[0012] [Figure 1] 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. [Figure 2A] 3 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. FIG. [Figure 2B] 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. [Figure 3A] 1 is a schematic cross-sectional view of a pressing member (particularly a rotation tool) and a receiving member according to a first embodiment used in a joining apparatus of the present invention. [Figure 3B] FIG. 4 is a schematic cross-sectional view of a receiving member according to a second embodiment used in the joining device of the present invention. [Figure 3C] 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. [Figure 3D] FIG. 11 is a schematic cross-sectional view of a receiving member according to a fourth embodiment used in the joining device of the present invention. [Figure 3E] FIG. 11 is a schematic cross-sectional view of a receiving member according to a fifth embodiment used in the joining device of the present invention. [Figure 4A] 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. [Figure 4B] 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. [Figure 5A] 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. [Figure 5B] 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 shown in FIG. 5A in the bonding apparatus and bonding method of the present invention. FIG. [Figure 6A] 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 an indentation. [Figure 6B] 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. [Figure 6C] 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. [Figure 6D] 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. [Figure 7] FIG. 2 is a schematic diagram for explaining a method for measuring a bonding strength in the examples. [Figure 8] 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. [Figure 9] FIG. 1 is a schematic cross-sectional view for explaining a conventional apparatus for joining metal members. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The joining device and joining method of the present invention are respectively a joining device and a joining method for joining two metal members. In detail, the joining device and joining method of the present invention adopt 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) with each other at their interface, thereby joining the first metal member and the second metal member. The heat and pressure are preferably applied locally. The thermo-compression joining method adopted 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 by the pressing member, and more preferably, a friction stir spot joining method is adopted.

[0014] As described in detail below, the friction stir spot joining method involves overlapping a first metal member and a second metal member, and pressing a rotating tool acting as a pressing member against the first metal 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.

[0015] The joining apparatus and joining method of the present invention, which employs the 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 for the purpose of 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.

[0016] In this specification, the term "cross-sectional view" refers to the shape when viewed 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 when cut along a plane parallel to the axial Y direction of the receiving member 17 and passing through the axis Y. The term "planar view" refers to the shape when an object is viewed from above or below along the axial Y direction of the receiving member 17, and includes plan views (top and bottom views).

[0017] [Metal component 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.

[0018] 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 an arrow A1 and moves downward as indicated by an 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 a pressing region P (a region 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, so that 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.

[0019] FIG. 2A is an enlarged view of a 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 portion (or tip side) (lower end portion 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 having a smaller diameter than the shoulder portion 16b, which is provided on the central axis X of the rotary tool 16 and protrudes outward (downward in FIG. 2A) from the circular tip surface 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 against it. More specifically, the rotating tool 16 has, at its tip side (particularly the tip side on the receiving member 17 side), a shoulder portion 16b including a circular tip surface of the rotating tool, and a cylindrical pin portion 16 having a smaller diameter than the shoulder portion and protruding outward from the circular tip surface of the rotating tool.

[0020] 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, PCBN (cubic boron nitride), or the like. 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 set to preferably 8 to 15 mm, more preferably 8 to 12 mm (particularly 10 mm). The diameter D2 of the pin portion 16a is usually set to 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 set to 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 set to 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 set to 1.20×T1 (mm) or more and 0.95×(T1+T2) (mm) or less, even more preferably set to 1.30×T1 (mm) or more and 0.95×(T1+T2) (mm).

[0021] A rotating tool 16' shown in FIG. 2B may be used. FIG. 2B is an enlarged view of the tip of another example of the 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 recessed in a mortar shape (conical shape). In FIG. 2B, the depth of the recess becomes deeper from the outer periphery of the shoulder portion 16b to the pin portion 16a. 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 bonding, and thus heat conduction in the surface direction (for example, the horizontal plane direction) is promoted, and further improvement in bonding strength can be achieved. The inclination angle θ of the inclined surface 16c is usually 15° or less, preferably 1 to 15°, and more preferably 5 to 15°.

[0022] As shown in FIG. 1 and FIG. 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 an 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. Incidentally, it is not always necessary to move the receiving member 17 in the direction of the arrow A3, and a method can also be adopted in which the rotating tool 16 is moved in the direction of the arrow A2 after the workpiece 10 is placed on the receiving member 17. Fig. 3A is a schematic cross-sectional view of a pressing member (particularly the rotating tool) and a receiving member according to a first embodiment used in the joining apparatus of the present invention.

[0023] 3A, the receiving member 17 has a recess 172 on the outer periphery of a surface portion 171 facing the pressing member (particularly, a rotating tool) 16. The surface portion of the receiving member 17 facing the pressing member 16 refers to a portion (or a region thereof) 171 facing the pressing member 16 on a surface 170 (upper surface) of the receiving member 17 facing the pressing member 16. In detail, the facing surface portion 171 refers to a portion (or a region thereof) 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, a flat surface) of the receiving member 17 that supports the workpiece 10 if the recess 172 is not formed.

[0024] The receiving member 17 has a recess on the outer periphery of such opposing surface portion 171. More specifically, as shown in Fig. 3A, the receiving member 17 has the recess 172 such that the outer periphery (particularly the contour line) 1711 of the opposing surface portion 171 is disposed within the range of the region of the recess 172 in a plan view. The inside (or inner periphery side) of the recess 172 on the opposing surface 170 of the receiving member 17 is particularly referred to as an inner periphery portion 173.

[0025] The recess 172 is formed in an annular (particularly circular) 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 dug groove that may also be called a "donut-shaped groove."

[0026] 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, the remaining thickness Tz of the first metal member can be secured relatively large, and it is considered that 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 maintaining 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 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 by the bonding apparatus and bonding method of the present invention with a larger rotary tool penetration amount than that in Fig. 5A.

[0027] When the receiving member 17 does not have the recess 172 on the outer periphery of the opposing surface portion 171 (see FIG. 3A), a sufficiently large joining strength cannot be obtained. Specifically, when the receiving member does not have a recess on the outer periphery of the opposing surface portion, as shown in FIG. 6A, in the vicinity of the indentation mark 520, the movement (or plastic flow) of the second metal member 512 toward the first metal member 511 occurs, and the remaining thickness Tz of the first metal member 511 decreases, so that a sufficiently large joining strength cannot be obtained. Therefore, when the penetration amount 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 although the decrease in the remaining thickness Tz of the first metal member 511 can be suppressed, the joining between the first metal member and the second metal member in the substantially horizontal direction Q is not sufficiently performed, and as a result, a sufficiently large joining strength cannot be obtained. On the other hand, when the penetration amount of the pressing member 16 is increased, as shown in FIGS. 6C and 6D, the movement (or plastic flow) of the second metal member 512 toward the first metal member 511 further occurs, and the remaining thickness Tz of the first metal member 511 further decreases, so that a sufficiently large joining strength cannot be obtained. Even when the receiving member has a recess in the opposing surface portion, as shown in FIG. 9, when the recess 518 is formed not on the outer periphery but on the inner peripheral side (or inner peripheral portion or central portion) of the opposing surface portion, due to the presence of the recess 518, the portion directly below the rotary tool 516 in the first metal member 511 and the second metal member 512 as a whole drops. For this reason, the remaining thickness Tz of the first metal member 511 also decreases, and a sufficiently large joining strength cannot be obtained.

[0028] The inner peripheral dimension (or inner diameter dimension) E1 (see FIG. 3A) of the recess 172 in the cross-sectional view is equal to or greater than D2 (mm) and equal to or less than D1 (mm) (particularly greater than D2 and less than D1) with respect to the diameter D1 (mm) of the shoulder portion 16b and the diameter D2 (mm) of the pin portion 16a (D2 < D1). 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 still more preferably 1.15 × D2 (mm) or more and 1.35 × D2 (mm) or less.

[0029] The peripheral dimension (or outer diameter dimension) E2 of the recess 172 in a cross-sectional view is greater than diameter D1 (mm) of the shoulder portion 16b (for example, 1.05×D1 (mm) or more and 2.00×D1 (mm) or less), and from the viewpoint of further improving the bonding 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.

[0030] The width dimension w of the recess 172 in a cross-sectional view is not particularly limited as long as movement (or plastic flow) of the second metal member 12 into the recess 172 occurs, and may be, for example, 0.10×D1 (mm) or more (particularly 0.10×D1 (mm) or more and 2.00×D1 (mm) or less) relative to the diameter D1 (mm) of the shoulder portion 16b, and from the viewpoint of further improving the bonding strength, is preferably 0.20×D1 (mm) or more and 1.00×D1 (mm) or less, more preferably 0.30×D1 (mm) or more and 0.70×D1 (mm) or less, and even more preferably 0.40×D1 (mm) or more and 0.60×D1 (mm) or less.

[0031] The depth dimension k of the recess 172 in a cross-sectional view is not particularly limited as long as movement (or plastic flow) of the second metal member 12 into the recess 172 occurs, and may be, for example, 0.10×T2 (mm) or more (particularly 0.10×T2 (mm) or more and 2.00×T2 (mm) or less) relative to the thickness T2 of the second metal member, and from the viewpoint of further improving the bonding strength, is preferably 0.20×T2 (mm) or more and 1.00×T2 (mm) or less, more preferably 0.30×T2 (mm) or more and 0.70×T2 (mm) or less, and even more preferably 0.40×T2 (mm) or more and 0.60×T2 (mm) or less.

[0032] 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 an inclined surface 1720 inclined in a cone shape in cross-sectional view. From the viewpoint of further improving the bonding strength, the recess 172 preferably has an inclined surface 1720 inclined in a cone shape in cross-sectional view as shown in FIG. 3B. The inclination angle α of the inclined surface 1720 is usually 80° or less, preferably 1 to 45°, more preferably 10 to 45°, and further preferably 20 to 40°. FIG. 3B is a schematic cross-sectional view of a receiving member according to a second embodiment used in the bonding 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 an inclined surface 1720.

[0033] The outer peripheral dimension (or outer diameter dimension) E3 of the receiving member 17 in the 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 the cross-sectional view may be greater than E2 (mm) (e.g., 1.05×E2 (mm) or more and 2.00×E2 (mm) or less) relative to the outer peripheral dimension E2 of the recess 172, and may particularly be 1.10×E2 (mm) or more and 1.40×E2 (mm) or less.

[0034] 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. This makes it possible to suppress the movement (or plastic flow) of the second metal member 12 toward the first metal member side even with a relatively small amount of penetration (d1+d2), as shown in FIG. 4B. This allows the remaining thickness Tz of the first metal member 11 to 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.

[0035] The protrusion 1730 usually 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.

[0036] The width dimension E4 (cross-sectional view) of the convex portion 1730 is typically 0.40×E1 (mm) or more and 1.00×E1 (mm) or less relative to the inner peripheral dimension E1 of the concave portion, and from the viewpoint of further improving energy efficiency and bonding strength, is preferably 0.60×E1 (mm) or more and 1.00×E1 (mm) or less, more preferably 0.70×E1 (mm) or more and 0.90×E1 (mm) or less, and even more preferably 0.75×E1 (mm) or more and 0.95×E1 (mm) or less.

[0037] The height dimension m (cross-sectional view) of the convex portion 1730 is 0.10×T2 (mm) or more and 1.00×T2 (mm) or less, relative to the thickness T2 of the second metal member, and from the viewpoint of further improving energy efficiency and bonding strength, is preferably 0.20×T2 (mm) or more and 0.90×T2 (mm) or less, more preferably 0.30×T2 (mm) or more and 0.70×T2 (mm) or less, and even more preferably 0.40×T2 (mm) or more and 0.60×T2 (mm) or less.

[0038] In cross-sectional view, the inclination angle β (see FIG. 3C) of the side surface of the convex portion 1730 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°.

[0039] From the viewpoint of further improving energy efficiency and bonding 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 bonding 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 the receiving member 17 has an inclined surface 1720 in the recess 172 and a convex portion 1730 on the inner periphery 173.

[0040] The receiving member 17 is preferably 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) at 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) at 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.

[0041] The friction stir spot welding device 1 generally includes a drive control device (not shown) that drives the pressing member (particularly the rotating tool) 16 and the receiving member 17 so as to be close to each other. The drive control device controls the driving of the pressing member (particularly the rotating tool) (particularly pressing drive and / or rotational drive, preferably pressing drive and rotational drive) and the driving of the receiving member 17 (particularly the vertical drive for vertical movement).

[0042] When the receiving member 17 does not have a convex portion on the inner peripheral portion 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 movement (or plastic flow) of the second metal member 12 into the recess 172 occurs. Usually, it is 0.80×T1 (mm) or more and 1.90×T1 (mm) or less (particularly 1.10×T1 (mm) or more and 1.90×T1 (mm) or less) with respect to the thickness T1 of the first metal member. From the viewpoint of further improving the joining strength, it is preferably 1.30×T1 (mm) or more and 1.90×T1 (mm) or less, more preferably 1.40×T1 (mm) or more and 1.85×T1 (mm) or less, and still more preferably 1.50×T1 (mm) or more and 1.80×T1 (mm) or less. In this case, the drive control device controls so as to satisfy d1<T1+T2 (particularly d1<T1+T2-0.5) so that the rotating tool does not penetrate the joined body.

[0043] When the receiving member 17 has a convex portion on its inner peripheral portion 173, the drive control device can control the total penetration amount of the pressing member (particularly the rotary tool) 16, i.e., the penetration amount d1, and the penetration amount of the receiving member 17 (particularly the convex portion 1730), i.e., the penetration amount d2. In this case, the total penetration amount (mm) of the penetration amount d1 of the pressing member (particularly the rotary tool) 16 and the penetration amount d2 of the receiving member 17 (particularly the convex portion 1730) is not particularly limited as long as the movement (or plastic flow) of the second metal member 12 into the concave portion 172 occurs. Usually, it is 0.80×T1 (mm) or more and 1.90×T1 (mm) or less (particularly 1.10×T1 (mm) or more and 1.90×T1 (mm) or less) with respect to the thickness T1 of the first metal member. From the viewpoint of further improving the bonding strength, it is preferably 1.10×T1 (mm) or more and 1.70×T1 (mm) or less, more preferably 1.20×T1 (mm) or more and 1.50×T1 (mm) or less, and even more preferably 1.30×T1 (mm) or more and 1.50×T1 (mm) or less. In this case, the drive control device controls so as to satisfy d1 + d2 < T1 + T2 (particularly d1 + d2 < T1 + T2 - 0.5) so that the rotary tool does not penetrate the joined body.

[0044] As will be described in detail later, the drive control device may adopt a pressure control method for controlling the pressing force, pressing time, and rotational speed of the rotary tool against the metal member, or may adopt a position control method for controlling the coordinate position, holding time at a specific position, and rotational speed of the rotary tool.

[0045] Although not shown in FIG. 1, the friction stir spot welding device 1 may be provided with jigs such as spacers and clamps for fixing the workpiece 10 in advance and preventing the floating of the metal member 11 when the rotary tool 16 is pressed.

[0046] Each of the first metal member 11 and the second metal member 12 has a generally flat plate shape in Fig. 1 etc., but is not limited thereto. Each of the first metal member 11 and the second metal member 12 may have any shape as long as at least the overlapping portions have a generally flat plate shape. Both sides of the overlapping portions of the first metal member 11 and the second metal member 12 are usually made up of flat surfaces.

[0047] 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.

[0048] From the viewpoint of further improving the bonding strength, the metals constituting each of the first metal member 11 and the second metal member 12 are each independently preferably aluminum or an aluminum alloy, and more preferably an aluminum alloy.

[0049] 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 bonding 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 of a substantially flat plate-shaped portion of the first metal member 11 that is to be overlapped with the second metal member 12 (thickness before bonding process).

[0050] The thickness T2 (see FIG. 4A) of the second metal member 12 is usually 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 a substantially flat plate-shaped portion of the second metal member 12 that is overlapped with the first metal member 11.

[0051] [Method of joining metal members by friction stir spot joining method and joint] 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 Fig. 4A and Fig. 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.

[0052] As shown in Fig. 5A and Fig. 5B, the first metal member 11 and the second metal member 12 have an indentation 20 from the first metal member side at the overlapping portion between them, and are 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 to reach 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 joined body has a protuberance 121 caused by 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 raised portion 121 suppresses the movement (or plastic flow) of the second metal member toward the first metal member in the vicinity of indentation 20. As a result, a relatively large remaining thickness Tz of the first metal member can be ensured, which is believed to result in a sufficiently large joining strength.

[0053] The residual thickness Tz (cross-sectional view) of the first metal member in the joined body is typically 0.50×T1(mm) or more and 1.25×T1(mm) or less (particularly 0.50×T1(mm) or more and 0.90×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, is preferably 0.60×T1(mm) or more and 0.90×T1(mm), and more preferably 0.65×T1(mm) or more and 0.85×T1(mm).

[0054] The residual thickness Tz of the first metal member 11 is the thickness of the first metal member 11 in the vicinity of the indentation 20 in the cross-sectional view of the bonded body. 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 Figs. 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 ten sheets. Mutual plastic flow (or melting and solidification) occurs in the vicinity of 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.

[0055] The raised portion 121 is formed by the pressing member (particularly the rotating tool) 16 and the receiving member 17 approaching each other in a joining method described later, whereby a part of the second metal member plastically flows 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 interval and dimensions of the indentation marks 20. Thus, the arrangement of the raised portion 121 can be expressed by the same definition as the arrangement of the recess 172 of the receiving member 17.

[0056] The height n of the raised portion 121 is typically 0.10×T2(mm) or more and 0.90×T2(mm) or less, where T2 (mm) is the thickness of the second metal member 12, and from the viewpoint of further improving the bonding strength, is preferably 0.20×T2(mm) or more and 0.80×T2(mm) or less, and more preferably 0.40×T2(mm) or more and 0.60×T2(mm) or less.

[0057] The 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 a first metal member 11 and a 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, and causing the first metal member 11 and the second metal member 12 to plastically flow (or melt and solidify) with each other at their interface by the frictional heat, thereby joining the first metal member 11 and the second metal member 12: It includes.

[0058] In the first step, as shown in FIG. 1, a first metal member 11 and a second metal member 12 are overlapped at a desired joining portion.

[0059] In the second step, the driving of the rotating tool is controlled so that the first metal member 11 and the second metal member 12 plastically flow (or melt) with 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 pressing force, pressing 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. Hereinafter, the second step that adopts the pressure control method will be described as a first embodiment, and the second step that adopts the position control method will be described as a second embodiment.

[0060] <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.

[0061] In the second step of this embodiment, it is preferable to perform a preheating step C1 before the thrust stirring step, in which the rotating tool 16 is rotated with the tip of the rotating tool 16 in contact with the surface portion of the first metal member 11, but this is not necessarily required.

[0062] After the pushing stirring process, it is preferable to perform a stirring maintenance process C3 in which the rotational operation of the rotation tool 16 is continued at the position where the rotation tool 16 was inserted in the pushing stirring process, but this process does not necessarily have to be performed.

[0063] These steps in this embodiment will now be described in detail.

[0064] (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.

[0065] Specifically, in the preheating step C1, frictional heat is generated on the surface of the first metal member 11 by the pressing of the rotary tool 16. The frictional heat is transferred to the inside of the first metal member 11, and the range of the pressed region P (the region pressed by the rotary tool 16) of the first metal member 11 and the range adjacent to the pressed region P are preheated. This makes it easier to press the rotary tool 16 into the metal member 11 in the next pressing and stirring step C2.

[0066] 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 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. 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.

[0067] The amount of heat input in this step is determined by the magnitude of the first pressurizing force, the length of the first pressurizing time, and the rotation speed of the rotating tool.

[0068] (Push-in mixing 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 FIG. 4A and FIG. 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 FIG. 4A and FIG. 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 FIG. 4A and FIG. 4B. This can promote the plastic flow of the second metal member 12 into the recess 172 of the receiving member 17.

[0069] 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 above-mentioned penetration amount (d1) of the pressing member (particularly the rotating tool) 16 in the case where the receiving member 17 does not have a protrusion on the inner circumferential portion 173; and When the receiving member 17 has a convex portion on the inner circumference 173, the total penetration amount (d1+d2) 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) described above.

[0070] In the thrust stirring process C2, the rotary tool 16 is rotated at a predetermined rotation speed with a second pressure greater than the first pressure and for a second pressurizing time shorter than the first pressurizing time.

[0071] 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, the 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 joined body is in a holed state where holes through which the rotating tool 16 passed are opened, and poor joining occurs.

[0072] The second pressure and the second pressurizing time in the thrust stirring process C2 are set from the viewpoint of avoiding the above-mentioned hole formation in the joint body and from the viewpoint of bringing the rotary 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 rotary 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 thrust 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 rotary tool is preferably 2000 rpm or more and 4000 rpm or less.

[0073] The amount of heat input in this step is determined by the magnitude of the second pressurizing force, the length of the second pressurizing time, and the rotation speed of the rotating tool.

[0074] (Stirring maintenance step C3) The stirring maintaining step C3 is a step of continuing the rotational 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 between 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.

[0075] In the stirring maintaining process C3, the applied pressure is smaller than that in the preheating process C1 (and, of course, smaller than that in the thrust stirring process C2), so that the rotating tool 16 is substantially maintained at the reference position. Since the rotational 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 the plastic flow of the second metal member 12 into the recess 172.

[0076] The third pressure and the third pressurizing time in the stirring maintaining step 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 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 third pressure in the stirring maintaining step 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.

[0077] The amount of heat input in this step is determined by the magnitude of the third pressurizing force, the length of the third pressurizing time, and the rotation speed of the rotating tool.

[0078] After the stirring maintaining step C3 in this embodiment 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.

[0079] <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 that reaches the boundary surface between the first metal member 11 and the second metal member 12.

[0080] 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 since a position control method is adopted.

[0081] After the pushing stirring process, it is preferable to perform a stirring maintenance process C3 in which the rotational operation of the rotation tool 16 is continued at the position where the rotation tool 16 was inserted in the pushing stirring process, but this process does not necessarily have to be performed.

[0082] These steps in this embodiment will now be described in detail.

[0083] (Push-in mixing process C2) The thrust stirring process C2 of this embodiment is the same as the thrust stirring process C2 of the first embodiment, except that a position control method is adopted. More specifically, in the thrust stirring process 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 process 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.

[0084] The specified depth is the same as the "depth reaching the boundary surface between the first metal member 11 and the second metal member 12" in the pressure control type pushing and mixing process C2, and preferably is the same as the "depth reaching the boundary surface between the first metal member 11 and the second metal member 12, but not reaching the bottom surface of the second metal member 12."

[0085] In this embodiment as well, 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 bonded body will have a hole where the rotary tool 16 passed through, resulting in a bond failure.

[0086] When the rotary tool 16 has advanced to a predetermined depth, the pushing movement of the rotary tool 16 is stopped.

[0087] The rotation speed of the rotating tool is preferably 2000 rpm or more and 4000 rpm or less.

[0088] The amount of heat input in this process is determined by the penetration time of the rotary tool and the rotation speed of the rotary tool, and the penetration time of the rotary tool is determined by the penetration amount and penetration speed of the rotary tool.

[0089] In this step, the approach speed of the rotary tool is not particularly limited, and is preferably, for example, 10 to 100 mm / min, and more preferably 20 to 50 mm / min.

[0090] (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 Figs. 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.

[0091] In the stirring maintaining step C3, the rotating tool 16 is rotated at a predetermined rotation speed while being held at the above-mentioned predetermined position for a predetermined time.

[0092] The holding time of the stirring maintaining step C3 is set from the viewpoint of the further promoted 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 or more and 3 mm or less and made of an aluminum alloy, the holding time in the stirring maintaining step 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. The holding time of 0 seconds means that the stirring maintaining step C3 does not need to be performed in this embodiment. This is because the heat input can be adjusted only by the intrusion time of the rotating tool in the above-mentioned thrust stirring step C2. In particular, when the intrusion amount, intrusion speed, and rotation speed of the rotating tool in the above-mentioned thrust stirring step C2 are within the above-mentioned ranges, the holding time in this stirring maintaining step C3 is usually 0 seconds or more and less than 5.0 seconds.

[0093] 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.

[0094] In this embodiment as well, after the stirring maintaining 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. EXAMPLES

[0095] [Metal parts] As the first metal member and the second metal member, a flat plate-like member (length 100 mm × width 30 mm × thickness 2.0 mm (=T1=T2)) made of a 6000 series aluminum alloy was used.

[0096] [Rotate Tool] A rotary tool 16' (D1 = 10 mm, D2 = 5 mm (= 0.5 × D1), h = 2.8 mm (= 1.40 × T1), θ = 14°; made of tool steel) shown in FIG. 2B was used.

[0097] [Support material] 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 rotary tool was flat. Hereinafter, such a receiving member is referred to as a "flat receiving member."

[0098] [Example A1] (Position control method) A bonded body of a first metal member 11 and a second metal member 12 was produced by the following method using a rotary tool 16' shown in FIG. 2B and a receiving member 17 shown in FIG. 3B. 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.

[0099] Second step: First, as shown in Fig. 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 x T1) (pressing and stirring process C2: tool rotation speed 3000 rpm). d2 = 0 mm. Thereafter, the rotating tool 16' was separated from the first metal member 11 and the second metal member 12 and left 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 values ​​were calculated. Example A1: n = 0.9 mm, Tz = 1.7 mm

[0100] [Examples A2 to A3] In the thrust stirring process C2, the rotary tool 16' was thrust so that the penetration amount (d1) of the rotary 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

[0101] [Example B1] (Position control method) A bonded body of the first metal member and the second metal member was obtained by the same method as in Example A1, except that a rotating tool 16' shown in Fig. 2B and a 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

[0102] [Comparative Examples C1 to C5] (Position Control Method) A bonded 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' and the flat receiving member shown in Figure 2B were used, and the rotating tool 16' was pressed in so that the penetration amount (d1) of the rotating tool 16' was 2.50 mm, 2.65 mm, 2.80 mm, 3.00 mm, or 3.10 mm in the pressing 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

[0103] [Joining strength] 7, a joint consisting of a first metal member 11 and a 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 in Figure 8.

[0104] 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. [Industrial Applicability]

[0105] The joining apparatus and joining method according to the present invention are useful for joining metal members together in the fields of automobiles, railway vehicles, aircraft, home appliances, and the like. [Explanation of symbols]

[0106] 1: Friction stir spot welding device 10: Work 11: First metal member 12: Second metal member 121: Excitement 16: Rotation tool 17:17': Support member 170: Surface of receiving member facing pressing member 171: Opposing surface part 172: Recess 1720: Inclined surface of recess 173: Inner circumference 1730: Convex 100: Fixture for measuring bonding strength P: Pressed area (area to be pressed)

Claims

1. 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 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.

2. 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. 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.

4. 4. The apparatus for joining metal members according to claim 1, wherein the recess has an inclined surface that is inclined like a mortar in a cross-sectional view.

5. 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.

6. The metal member joining apparatus according to any one of claims 1 to 5, wherein the first metal member has a thickness T1 of 1.0 mm or more.

7. The apparatus for joining metal members 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.

8. 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.

9. 9. The apparatus for joining metal members according to claim 1, wherein the first metal member and the second metal member are each independently made of aluminum or an aluminum alloy.

10. 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.

11. 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.

12. 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.

13. 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.

14. In the joining device, 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×T2 (mm), where T2 is a thickness of the second metal member.

15. 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.

16. 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.

17. 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.

18. 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.

19. 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.

20. 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.

21. 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.

22. A method for joining metal members as described in any of claims 12 to 21, wherein the joining apparatus is a friction stir spot joining apparatus.

23. 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.

24. 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.

25. 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.

26. 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 together; The method for joining metal members according to claim 25, which is a friction stir spot joining method comprising the steps of:

27. 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.

28. 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.

29. 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.

30. 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 the total thrust d1 of the pressing member and the thrust d2 of the receiving member 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.

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