Friction stir spot welding device and joint structure

Abstract

To provide a friction stir point welding device which can determine tool wear state from a welding point of an object to be welded (surface of a part to be welded), and a joint structure.SOLUTION: A friction stir point welding device comprises: a pin member (11) formed into a columnar shape; a shoulder member (12) which is formed into a cylindrical shape, and through which the pin member (11) is inserted; a rotation driver (57) which rotates the pin member (11) and the shoulder member (12) around an axis line (Xr) coincident with an axis of the pin member (11); and an advancement / retraction driver (53) which performs advancement / retraction of the pin member (11) and the shoulder member (12) respectively along the axis line (Xr). A tip (120) of the shoulder member (12) is tapered.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a friction stir spot welding apparatus and a joint structure. [Background technology]

[0002] In transportation equipment such as automobiles, railway vehicles, and aircraft, resistance spot welding or riveting has been used to join metal materials. However, in recent years, a method of joining metal materials using frictional heat (friction stir spot joining) has been attracting attention (see, for example, Patent Document 1).

[0003] In the friction stir spot welding method disclosed in Patent Document 1, a substantially cylindrical pin member and a substantially cylindrical shoulder member having a hollow for inserting the pin member are used to join the workpieces, and a tool driving unit that operates (drives) the pin member and shoulder member (tool) is controlled as described below.

[0004] That is, when the cross-sectional area of ​​the tip surface of the pin member is Ap, the cross-sectional area of ​​the tip surface of the shoulder member is As, the press-in depth when the pin member is pressed into the surface of the workpiece is Pp, and the press-in depth when the shoulder member is pressed into the surface of the workpiece is Ps, the tool driving unit is controlled so as to reduce the absolute value of the tool mean position Tx, which is defined as Ap·Pp+As·Ps=Tx.

[0005] This makes it possible to achieve good joining quality with suitable precision according to the joining conditions, and also to prevent or suppress the occurrence of internal void defects. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-196682 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the inventors have found that in the friction stir spot welding method disclosed in Patent Document 1, the surfaces of the workpieces are smoothed, so the wear condition of the tool cannot be determined from the surfaces of the workpieces after welding is completed. For this reason, it is necessary to periodically remove the tool from the device and inspect the wear condition of the tool.

[0008] An object of the present invention is to provide a friction stir spot welding apparatus and a joint structure that can determine the wear state of a tool from the welding point (surface of the part to be welded) of the workpieces. [Means for solving the problem]

[0009] In order to solve the above problems, the friction stir spot welding device of the present invention is a friction stir spot welding device that joins materials to be welded by softening them with frictional heat, and the friction stir spot welding device comprises a cylindrical pin member, a cylindrical shoulder member through which the pin member is inserted, a rotation driver that rotates the pin member and the shoulder member around an axis that coincides with the axis of the pin member, and an advance / retract driver that moves the pin member and the shoulder member back and forth along the axis, respectively, and the tip of the shoulder member is formed in a tapered shape.

[0010] As a result, if there is no wear on the tip of the shoulder member, when the workpieces are friction stir spot welded, the shape of the tip is imprinted (transferred) onto the surface of the workpieces. On the other hand, if there is wear on the tip of the shoulder member, the shape of the tip is not imprinted onto the surface of the workpieces, and the surface becomes flat.

[0011] Therefore, after the friction stir spot welding is completed, it is possible to determine whether or not the tip of the shoulder member is worn by inspecting (visually checking) the surface of the part to be welded.

[0012] Furthermore, the joint structure according to the present invention is a joint structure formed by friction stir spot welding of a workpiece comprising a first member and a second member at a joint portion, wherein the first member is made of a material having a lower melting point than the second member, the first member and the second member are arranged in this order, a circular recess is formed on the surface of the joint portion, and the bottom surface of the recess is formed to be inclined, curved, curved, or bent.

[0013] This makes it possible to determine whether or not the tip of the shoulder member is worn by inspecting (visually checking) the surface of the part to be welded after the friction stir spot welding is completed.

[0014] The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. [Effects of the Invention]

[0015] According to the friction stir spot welding apparatus and joint structure of the present invention, the wear state of the tool can be determined from the welding spot (surface of the part to be welded) of the workpiece. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a friction stir spot welding apparatus according to the first embodiment. [Figure 2] FIG. 2 is an enlarged schematic view of a main part of the friction stir spot welding apparatus shown in FIG. [Figure 3] FIG. 3 is a block diagram schematically showing a control configuration of the friction stir spot welding apparatus shown in FIG. [Figure 4] FIG. 4 is a flowchart showing an example of the operation of the friction stir spot welding apparatus according to the first embodiment. [Figure 5A] FIG. 5A is a process diagram schematically illustrating an example of each step of friction stir spot welding using the friction stir spot welding apparatus shown in FIG. [Figure 5B]FIG. 5B is a process diagram schematically illustrating an example of each step of friction stir spot welding using the friction stir spot welding apparatus shown in FIG. [Figure 6] FIG. 6 is an enlarged schematic view of a main part of a friction stir spot welding apparatus according to Modification 1 of the first embodiment. [Figure 7] FIG. 7 is a schematic diagram showing a schematic configuration of a main part of a friction stir spot welding apparatus according to the second embodiment. [Figure 8A] FIG. 8A is a schematic diagram showing the general configuration of the pin member, shoulder member, and tip portion of the clamp member of the friction stir spot welding apparatus. [Figure 8B] FIG. 8B is an exploded view of the shear force acting on the transfer portion of the workpiece. [Figure 9] FIG. 9 is a schematic diagram showing a schematic configuration of a main part of a friction stir spot welding apparatus according to the third embodiment. [Figure 10] FIG. 10 is a graph showing the results of the tensile shear test and the cross tension test of the workpieces friction stir spot welded under the above welding conditions using the friction stir spot welding apparatuses of Test Examples 1 and 2 and the Comparative Example. [Figure 11] FIG. 11 is a cross-sectional photograph of workpieces friction stir spot welded using the friction stir spot welding apparatus of Test Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant explanations will be omitted. Also, in all the drawings, only the components necessary for explaining the present invention are illustrated, and other components may be omitted. Furthermore, the present invention is not limited to the following embodiments.

[0018] (Embodiment 1) An example of the friction stir spot welding apparatus according to the first embodiment will be described in detail below with reference to the drawings.

[0019] [Configuration of friction stir spot welding equipment] Fig. 1 is a schematic diagram showing a schematic configuration of a friction stir spot welding apparatus according to the present embodiment 1. In Fig. 1, the up-down direction in the drawing represents the up-down direction in the friction stir spot welding apparatus.

[0020] As shown in FIG. 1, the friction stir spot welding apparatus 50 according to the first embodiment includes a pin member 11, a shoulder member 12, a tool fixture 52, an advance / retreat driver 53, a clamp member 13, a backing support portion 55, a backing member 56, and a rotation driver 57.

[0021] The pin member 11, shoulder member 12, tool fixture 52, advance / retreat driver 53, clamp member 13, and rotation driver 57 are provided at the upper end of a backing support part 55 consisting of a C-type gun (C-type frame). A backing member 56 is provided at the lower end of the backing support part 55. The pin member 11, shoulder member 12, and clamp member 13, and the backing member 56 are attached to the backing support part 55 in positions facing each other. An article to be welded 60 is placed between the pin member 11, shoulder member 12, and clamp member 13, and the backing member 56.

[0022] The pin member 11, shoulder member 12, and clamp member 13 are fixed to a tool fixture 52 composed of a rotary tool fixture 521 and a clamp fixture 522. Specifically, the pin member 11 and shoulder member 12 are fixed to the rotary tool fixture 521, and the clamp member 13 is fixed to the clamp fixture 522 via a clamp driver 41. The rotary tool fixture 521 is supported by the clamp fixture 522 via a rotation driver 57. The clamp driver 41 is formed of a spring.

[0023] The pin member 11, the shoulder member 12, and the clamp member 13 are driven to move up and down by a moving-back driver 53 made up of a pin driver 531 and a shoulder driver 532.

[0024] The pin member 11 is formed in a cylindrical shape, and although not shown in detail in Fig. 1, is supported by a rotary tool fixture 521. The pin member 11 is configured to be rotated by a rotation driver 57 around an axis Xr (rotation axis) that coincides with the axis of the pin member 11, and to be movable back and forth by a pin driver 531 in the direction of arrow P1, i.e., along the axis Xr direction (the up-down direction in Fig. 1).

[0025] It should be noted that pin driver 531 may be configured, for example, as a linear actuator. The linear actuator may be configured, for example, as a servo motor and rack and pinion, a servo motor and ball screw, or an air cylinder.

[0026] The shoulder member 12 is formed in a hollow cylindrical shape and is supported by a rotary tool fixture 521. The pin member 11 is inserted into the hollow of the shoulder member 12. In other words, the shoulder member 12 is disposed so as to surround the outer peripheral surface of the pin member 11.

[0027] The shoulder member 12 is configured to be rotated by a rotation driver 57 around the same axis Xr as the pin member 11, and to be movable by a shoulder driver 532 in the direction of arrow P2, that is, along the axis Xr.

[0028] It should be noted that shoulder driver 532 may be configured, for example, by a linear actuator, which may be configured, for example, by a servo motor and rack and pinion, a servo motor and ball screw, or an air cylinder.

[0029] In this manner, in this embodiment, the pin member 11 and the shoulder member 12 (rotary tool) are both supported by the same rotary tool fixture 521, and both are rotated integrally around the axis Xr by the rotation driver 57. Furthermore, the pin member 11 and the shoulder member 12 are configured to be movable back and forth along the axis Xr by the pin driver 531 and the shoulder driver 532, respectively.

[0030] In the present embodiment 1, the pin member 11 can move forward and backward independently, and can also move forward and backward in conjunction with the forward and backward movement of the shoulder member 12; however, the pin member 11 and the shoulder member 12 may be configured to be able to move forward and backward independently of each other.

[0031] The clamp member 13, like the shoulder member 12, is formed in a hollow cylindrical shape and is provided so that its axis coincides with the axis Xr. The shoulder member 12 is inserted into the hollow of the clamp member 13.

[0032] That is, a cylindrical shoulder member 12 is disposed so as to surround the outer peripheral surface of the pin member 11, and a cylindrical clamp member 13 is disposed so as to surround the outer peripheral surface of the shoulder member 12. In other words, the clamp member 13, shoulder member 12, and pin member 11 each have a coaxial nested structure.

[0033] Furthermore, the clamp member 13 is configured to press the article 60 from one side (front surface). As described above, in the present embodiment 1, the clamp member 13 is supported by the clamp fixing device 522 via the clamp driver 41. The clamp driver 41 is configured to bias the clamp member 13 toward the backing member 56. The clamp member 13 (including the clamp driver 41 and the clamp fixing device 522) is configured to be able to advance and retreat in the direction of arrow P3 (the same direction as arrows P1 and P2) by the shoulder driver 532.

[0034] In the first embodiment, the clamp driver 41 is configured with a spring, but is not limited to this. The clamp driver 41 may be configured to apply a biasing force or pressure to the clamp member 13, and for example, a mechanism using gas pressure, hydraulic pressure, a servo motor, or the like may be suitably used.

[0035] The pin member 11, shoulder member 12, and clamp member 13 have a tip surface 11a, a tip surface 12a, and a tip surface 13a, respectively. The tip surface 11a of the pin member 11 and the tip surface 12a of the shoulder member 12 are configured to coincide when viewed horizontally.

[0036] In addition, as the pin member 11, shoulder member 12, and clamp member 13 move forward and backward by the forward and backward driver 53, the tip surface 11a, tip surface 12a, and tip surface 13a each come into contact with the surface of the workpiece 60 (the part to be joined of the workpiece 60) and press the workpiece 60.

[0037] The tip portion 120 of the shoulder member 12 is formed in a tapered shape. The shape of the tip portion 120 of the shoulder member 12 will now be described in detail with reference to FIG.

[0038] FIG. 2 is an enlarged schematic view of a main part of the friction stir spot welding apparatus shown in FIG.

[0039] 2, in the present embodiment 1, the tip portion 120 is formed so that the outer peripheral surface 12b and the inner peripheral surface 12c of the shoulder member 12 are inclined with respect to the axis Xr. In other words, the cross section of the tip portion 120 in the direction of the axis Xr is formed to be substantially V-shaped (substantially U-shaped) when viewed horizontally.

[0040] The tip portion 120 refers to a portion (region) from the tip surface 12a of the shoulder member 12 to a predetermined height h. The height h may be, for example, 0.05 mm or more, or 5% or more of the thickness dimension of the first member 61, from the viewpoint of imprinting (transferring) the shape of the tip portion 120 onto the surface of the article 60. The height h may be, for example, 0.5 mm or less, or 50% or less of the thickness dimension of the first member 61, from the viewpoint of suppressing breakage of the tip portion 120 of the shoulder member 12.

[0041] The distal end portion 120 may be formed so that the radial cross-sectional area decreases toward the distal end. Furthermore, the shapes of the outer peripheral surface 12b and the inner peripheral surface 12c of the distal end portion 120 may be any shape as long as the area of ​​the distal end 12d (distal end surface 12a) of the distal end portion 120 is smaller than the radial cross-sectional area of ​​the base end 12e of the distal end portion 120.

[0042] 1, in the present embodiment 1, the backing member 56 is configured to support the flat plate-shaped article 60 by using a flat surface (support surface 56a) so as to come into contact with the back surface of the article 60. The configuration of the backing member 56 is not particularly limited as long as it can appropriately support the article 60 so that friction stir welding can be performed. The backing member 56 may be configured such that, for example, backing members 56 having a plurality of types of shapes are separately prepared and can be detached from the backing support part 55 and replaced depending on the type of article 60.

[0043] The article to be bonded 60 has two plate-shaped members, a first member 61 and a second member 62. The first member 61 is disposed so as to face the pin member 11 and the shoulder member 12, and is made of a material having a lower melting point than the second member 62.

[0044] The article to be bonded 60 may have a third member disposed between the first member 61 and the second member 62. The third member may be, for example, a metal material (e.g., aluminum, aluminum alloy, magnesium alloy, etc.) or a sealant material. The sealant material may be a sealing material or an adhesive. The sealant material may be, for example, synthetic rubber such as polysulfide synthetic rubber, natural rubber, silicone rubber, or fluororubber, or synthetic resin such as tetrafluoroethylene rubber resin, etc.

[0045] At least one material selected from the group consisting of metal materials (e.g., aluminum, aluminum alloys, magnesium alloys, etc.), thermoplastics (e.g., polyamides, etc.), and fiber-reinforced plastics (e.g., carbon fiber-reinforced plastics, etc.) may be used for the first member 61. As the aluminum alloy, various aluminum alloys may be used, and for example, an Al-Mg-Si alloy (A6061) or an Al-Si-Mg alloy (AC4C) may be used.

[0046] Furthermore, the second member 62 may be made of a metal material (for example, steel, titanium, etc.). As the steel, various types of steel may be used, and mild steel or high-tensile steel may be used. Furthermore, an oxide film may be formed on the surface of the steel, or a plating layer (for example, zinc plating) may be formed. The steel plate on which zinc plating is formed may be a hot-dip galvanized steel plate (GI steel plate), a galvannealed hot-dip galvanized steel plate (GA steel plate), a Galvalume steel plate (registered trademark), or an aluminum-silicon plated hot-stamp steel plate. Furthermore, the thickness of the plating layer may be 2 μm to 50 μm.

[0047] In the first embodiment, the article 60 is configured with a plate-shaped first member 61 and a plate-shaped second member 62, but the present invention is not limited to this and the shape of the article 60 (first member 61 and second member 62) is arbitrary, and may be, for example, a rectangular parallelepiped or formed in an arc shape. The shape of the third member is also arbitrary, and may be, for example, a plate-shaped, rectangular parallelepiped or formed in an arc shape.

[0048] Furthermore, the specific configurations of the pin member 11, shoulder member 12, tool fixture 52, advance / retreat driver 53, clamp member 13, backing support 55, and rotation driver 57 in the present embodiment 1 are not limited to those described above, and configurations widely known in the field of friction stir welding can be suitably used. For example, the pin driver 531 and the shoulder driver 532 may be configured with a motor, gear mechanism, or the like known in the field of friction stir welding.

[0049] In the first embodiment, the backing support portion 55 is configured as a C-type gun, but is not limited to this. The backing support portion 55 may be configured in any manner as long as it can support the pin member 11, the shoulder member 12, and the clamp member 13 so that they can move back and forth, and can support the backing member 56 in a position facing the pin member 11, the shoulder member 12, and the clamp member 13.

[0050] Furthermore, in the first embodiment, a configuration including the clamp member 13 is employed, but the present invention is not limited to this, and a configuration not including the clamp member 13 may also be employed. In this case, for example, the clamp member 13 may be configured to be detachable from the backing support portion 55 as necessary.

[0051] Furthermore, the friction stir spot welding apparatus 50 according to the first embodiment is configured to be disposed in a friction stir spot welding robot apparatus (not shown). Specifically, the backing support part 55 is attached to the tip of the arm of the robot apparatus.

[0052] For this reason, the backing support unit 55 can also be considered to be included in the friction stir spot welding robot device. The specific configuration of the friction stir spot welding robot device, including the backing support unit 55 and the arm, is not particularly limited, and a configuration known in the field of friction stir welding, such as an articulated robot, can be suitably used.

[0053] The friction stir spot welding apparatus 50 (including the backing support part 55) is not limited to applications in friction stir spot welding robot devices, but can also be suitably applied to known processing equipment such as NC machine tools, large C-frames, and auto riveters.

[0054] Furthermore, the friction stir spot welding apparatus 50 according to the first embodiment may be configured such that two or more pairs of robots position the backing member 56 directly opposite the portions of the friction stir spot welding apparatus 50 other than the backing member 56. Furthermore, the friction stir spot welding apparatus 50 may adopt a configuration in which the workpieces 60 are handheld, or may adopt a configuration in which the robots are used as positioners for the workpieces 60, as long as it is possible to stably perform friction stir spot welding on the workpieces 60.

[0055] [Control configuration of friction stir spot welding equipment] Next, the control configuration of the friction stir spot welding apparatus 50 according to the first embodiment will be specifically described with reference to FIG.

[0056] FIG. 3 is a block diagram schematically showing a control configuration of the friction stir spot welding apparatus shown in FIG.

[0057] As shown in FIG. 3, the friction stir spot welding apparatus 50 includes a controller 51, a memory 31, an input device 32, and a position detector 33.

[0058] The controller 51 is composed of a microprocessor, a CPU, etc., and is configured to control each member (each device) that constitutes the friction stir spot welding apparatus 50. Specifically, the controller 51 reads out and executes software such as a basic program stored in a memory, thereby controlling the pin driver 531 and shoulder driver 532 that constitute the advance / retreat driver 53, and the rotation driver 57.

[0059] This makes it possible to switch between advancing and retreating movement of the pin member 11 and the shoulder member 12, and to control the tip positions, movement speed, movement direction, etc. of the pin member 11 and the shoulder member 12 during advancing and retreating movement. Also, it is possible to control the pressing force with which the pin member 11, shoulder member 12, and clamp member 13 press the article 60. Furthermore, it is possible to control the rotation speed of the pin member 11 and the shoulder member 12.

[0060] The controller 51 may be configured as a single controller 51 that performs centralized control, or may be configured as a plurality of controllers 51 that cooperate with each other to perform distributed control. The controller 51 may also be configured as a microcomputer, or may be configured as an MPU, a PLC (Programmable Logic Controller), a logic circuit, etc.

[0061] The memory 31 stores the basic program and various data in a readable manner, and is configured as a storage device such as a known memory or a hard disk. The memory 31 does not need to be a single device, and may be configured as multiple storage devices (for example, a random access memory and a hard disk drive). When the controller 51 or the like is configured as a microcomputer, at least a part of the memory 31 may be configured as an internal memory of the microcomputer, or may be configured as an independent memory.

[0062] It goes without saying that data may be stored in the memory 31 and may be readable from a device other than the controller 51, and data may be written from the controller 51 or the like.

[0063] The input device 32 allows various parameters related to the control of friction stir spot welding or other data to be input to the controller 51, and is configured with a known input device such as a keyboard, a touch panel, a group of button switches, etc. In the present embodiment 1, at least the welding conditions of the workpieces 60, for example, data such as the thickness and material of the workpieces 60, can be input by the input device 32.

[0064] The position detector 33 is configured to detect position information of the tip (tip surface 12a) of the shoulder member 12 and output the detected position information to the controller 51. As the position detector 33, for example, a displacement sensor, an LVDT, an encoder, etc. may be used.

[0065] [Operation of friction stir spot welding equipment (operation method)] Next, the operation of the friction stir spot welding apparatus 50 according to the first embodiment will be specifically described with reference to Fig. 4, Fig. 5A, and Fig. 5B. Note that Fig. 5A and Fig. 5B show an example in which a first member 61 and a second member 62 are used as the workpiece 60, and these are overlapped and connected by spot welding.

[0066] Fig. 4 is a flowchart showing an example of the operation of the friction stir spot welding apparatus according to Embodiment 1. Fig. 5A and Fig. 5B are process diagrams schematically showing an example of each step of friction stir spot welding by the friction stir spot welding apparatus shown in Fig. 1.

[0067] 5A and 5B, a portion of the friction stir spot welding apparatus is omitted, the arrow r indicates the rotation direction of the pin member 11 and the shoulder member 12, and the block arrow F indicates the direction of the force applied to the first member 61 and the second member 62. A force is also applied to the first member 61 and the second member 62 from the backing member 56, but for convenience of explanation, this is not shown in FIGS. 5A and 5B. Furthermore, the shoulder member 12 is hatched to clearly distinguish it from the pin member 11 and the clamp member 13.

[0068] First, the worker (operator) places the article 60 on the support surface 56a of the backing member 56. Next, the worker operates the input device 32 to input a command to execute welding of the article 60 to the controller 51. Note that the robot may place the article 60 on the support surface 56a of the backing member 56.

[0069] Then, as shown in FIG. 4, the controller 51 drives the rotation driver 57 to rotate the pin member 11 and the shoulder member 12 at a predetermined first rotation speed (e.g., 200 to 3000 rpm) that has been set in advance (step S101; see step (1) in FIG. 5A).

[0070] Next, the controller 51 drives the forward / backward driver 53 (shoulder driver 532) to rotate the pin member 11 and the shoulder member 12, and moves the pin member 11, the shoulder member 12, and the clamp member 13 toward the workpiece 60, and brings the tip surface 11a of the pin member 11, the tip surface 12a of the shoulder member 12, and the tip surface 13a of the clamp member 13 (not shown in Figures 5A and 5B) into contact with the surface 60c of the workpiece 60 (the part to be welded Wa of the workpiece 60) (step S102; see process (2) in Figure 5A).

[0071] At this time, the controller 51 controls the forward / backward driver 53 (shoulder driver 532) so that the pin member 11, the shoulder member 12, and the clamp member 13 press the workpiece 60 with a predetermined pressing force (for example, a predetermined value within the range of 3 kN to 15 kN).

[0072] As a result, the first member 61 and the second member 62 are sandwiched between the clamp member 13 and the backing member 56, and as the clamp driver 41 contracts, the clamp member 13 is urged toward the surface 60c of the workpiece 60, generating a clamping force.

[0073] In addition, in this state, neither the pin member 11 nor the shoulder member 12 moves back and forth, so that the surface 60c of the workpiece 60 is "preheated." As a result, the constituent material in the contact area of ​​the first member 61 generates heat due to friction and softens, and a plastic flow portion 60a is generated in the vicinity of the surface 60c of the workpiece 60.

[0074] Next, the controller 51 drives the advance / retract driver 53 so that the tip end surface 11a of the pin member 11 is retracted into the tip end surface 12a of the shoulder member 12 (step S103). At this time, the controller 51 may drive the advance / retract driver 53 (pin driver 531) so that the pin member 11 moves away from the article 60. The controller 51 may also drive the advance / retract driver 53 (shoulder driver 532) so that the shoulder member 12 is press-fit into the article 60.

[0075] As a result, the tip end of the shoulder member 12 is pressed into the portion to be welded of the article 60 in a rotated state.

[0076] Next, the controller 51 acquires position information of the distal end surface 12a (tip) of the shoulder member 12 from the position detector 33 (step S104). Next, the controller 51 determines whether the position information of the tip of the shoulder member 12 acquired in step S104 has reached a predetermined first position that has been set in advance (step S105).

[0077] Here, the first position can be set in advance by experiment or the like, and is any position within the second member 62. More specifically, the first position is any position within 0.3 mm or less from the abutment surface 62a of the second member 62 with the first member 61 (the surface of the second member 62 facing the tip surface 12a of the shoulder member 12).

[0078] Furthermore, the first position may be a position 0.008 mm or more from the contact surface 62a, or may be a position 0.01 mm or more from the contact surface 62a, from the viewpoint of removing the plating layer (plating film) or oxide film formed on the second member 62 and forming a new surface. Furthermore, from the viewpoint of suppressing wear (damage) of the shoulder member 12, the first position may be a position 0.25 mm or less from the contact surface 62a, or may be a position 0.20 mm or less from the contact surface 62a, or may be a position 0.10 mm or less from the contact surface 62a.

[0079] Furthermore, from the viewpoint of removing the plating layer (plating film) or oxide film formed on the second member 62 and forming a new surface, the first position may be a position that is 0.20 mm or less from the plating layer (plating film) or oxide film formed on the second member 62, or may be a position that is 0.10 mm or less from the plating layer (plating film) or oxide film formed on the second member 62.

[0080] As a result, the tip surface 12a of the shoulder member 12 reaches an arbitrary position (i.e., the first position) that is 0.3 mm or less from the contact surface 62a of the second member 62. Then, a new surface is formed in the portion of the second member 62 that is in contact with the shoulder member 12 and / or the portion of the second member 62 that is in contact with the plastic flow portion 60a.

[0081] The softened material of the plastic flow portion 60a is pushed aside by the shoulder member 12 and flows from directly below the shoulder member 12 to directly below the pin member 11, causing the pin member 11 to retreat and rise above the shoulder member 12 (see step (3) in Figure 5A).

[0082] If the controller 51 determines that the position information of the tip surface 12a of the shoulder member 12 acquired in step S104 has not reached the first position (No in step S105), the controller 51 returns to step S104 and repeats the processing of steps S104 and S105 until it determines that the position information of the tip surface 12a of the shoulder member 12 acquired in step S104 has reached the first position.

[0083] On the other hand, when the controller 51 determines that the position information of the distal end surface 12a of the shoulder member 12 acquired in step S104 has reached the first position (Yes in step S105), the controller 51 executes the process of step S106.

[0084] When the tip surface 12a of the shoulder member 12 reaches the first position, the controller 51 drives the advance / retract driver 53 (shoulder driver 532) so that the tip surface 12a is positioned at the first position. Specifically, the controller 51 drives the advance / retract driver 53 so as to stop the advancement of the shoulder member 12.

[0085] In step S106, the controller 51 measures the time t from when it is determined that the tip surface 12a of the shoulder member 12 has reached the first position. Then, the controller 51 determines whether the time t measured in step S106 has exceeded a predetermined first time period (step S107).

[0086] Here, the first time period can be set in advance through experiments or the like. From the viewpoint of sufficiently increasing the bonding strength of the bonded portions of the articles 60, the first time period may be, for example, longer than 0 seconds, or may be 0.5 seconds or more. Moreover, from the viewpoint of shortening the bonding time of the articles 60, the first time period may be shorter than 2 seconds.

[0087] If the controller 51 determines that the time t measured in step S106 has not elapsed the first time (No in step S107), it executes the processes of steps S106 and S107 until it determines that the time t measured in step S106 has elapsed the first time.

[0088] On the other hand, if the controller 51 determines that the time t measured in step S106 has exceeded the first time period (Yes in step S107), the controller 51 executes the process of step S108.

[0089] In step S108, the controller 51 drives the advance / retract driver 53 (pin driver 531) so that the pin member 11 moves toward the workpiece 60, and / or the controller 51 drives the advance / retract driver 53 (pin driver 531) so that the shoulder member 12 moves away from the workpiece 60.

[0090] Specifically, the controller 51 controls the advance / retract driver 53 to align the tip surface 11a of the pin member 11 and the tip surface 12a of the shoulder member 12 so that there is almost no step between them (to make them flush).

[0091] At this time, from the viewpoint of transferring the shape of the tip portion 120 to the surface (upper surface) 60c of the workpiece 60, the controller 51 may control the forward / backward driving device 53 so that the tip surface 11a of the pin member 11 and the tip surface 12a of the shoulder member 12 are positioned at a predetermined second position set in advance within the first member 61 of the workpiece 60.

[0092] In addition, the controller 51 may control the forward / backward driver 53 so that the tip surface 11a of the pin member 11 is positioned on the surface 60c of the workpiece 60 and the tip surface 12a of the shoulder member 12 is positioned at a second position within the first member 61 of the workpiece 60.

[0093] Here, the second position can be set in advance by experiments or the like. From the viewpoint of transferring the shape of the tip portion 120 to the surface (upper surface) 60c of the article 60, the second position may be, for example, a position lower (inward) by the height h dimension of the tip portion 120 from the surface 60c of the article 60. Furthermore, from the viewpoint of reducing the height of the irregularities on the surface 60c of the article 60, the second position may be, for example, a position lower (inward) by half the height h of the tip portion 120 from the surface 60c of the article 60.

[0094] Furthermore, the controller 51 may cause the tip of the rotated shoulder member 12, when it has reached the second position, to remain there for a predetermined second time period. Here, the second time period can be set in advance through experiments. From the viewpoint of transferring the shape of the tip portion 120 to the surface (upper surface) 60c of the workpiece 60, the second time period may be, for example, longer than 0 seconds or 0.5 seconds or more. Moreover, from the viewpoint of shortening the time required to bond the workpiece 60, the second time period may be shorter than 2 seconds.

[0095] As a result, the pin member 11 gradually advances toward the first member 61, and the shoulder member 12 retreats from the first member 61. At this time, the softened portion of the plastic flow portion 60a flows from directly below the pin member 11 to directly below the shoulder member 12 (the recess created by the press-fitting of the shoulder member 12).

[0096] Then, the tip surface 11a of the pin member 11 and the tip surface 12a of the shoulder member 12 move to the vicinity of the surface 60c of the article 60. As a result, the shape of the tip portion 120 is imprinted (transferred) onto the surface 60c of the article 60 (see step (4) in FIG. 5B).

[0097] In the processing of step S103 and / or step S108, the controller 51 calculates the area of ​​the tip surface of the pin member 11 as Ap, the area of ​​the tip surface of the shoulder member 12 as As, the press-fit depth of the pin member 11 as Pp, and the press-fit depth of the shoulder member 12 as Ps by using the following formula (I): Ap Pp + As Ps = Tx (I) It is preferable to control the advance / retract driver 53 so as to reduce the absolute value of the tool mean position Tx defined as follows, and it is more preferable to control the advance / retract driver 53 so that the tool mean position Tx becomes 0. Note that the specific control for reducing the absolute value of the tool mean position Tx is disclosed in detail in Japanese Patent Application Laid-Open No. 2012-196682, and therefore a description thereof will be omitted here.

[0098] Furthermore, in the processing of step S108, the controller 51 may control the advance / retract driver 53 so that the tip surface 11a of the pin member 11 is located at the first position. In this case, the controller 51 may control the advance / retract driver 53 so that the tip surface 11a of the pin member 11 and the tip surface 12a of the shoulder member 12 are flush with each other after the tip surface 11a of the pin member 11 is located at the first position.

[0099] Next, the controller 51 drives the advance / retreat driver 53 so as to move the pin member 11, the shoulder member 12, and the clamp member 13 away from the article 60 (step S109). Then, the controller 51 controls the rotation driver 57 to stop the rotation of the pin member 11 and the shoulder member 12 (step S110; see step (5) in FIG. 5B), and ends this program (the step of joining the article 60).

[0100] As a result, the rotation (and pressure) caused by the contact between the pin member 11 and the shoulder member 12 is no longer applied to the first member 61 and the second member 62, so that plastic flow stops in the plastic flow portion 60a and the newly formed surface of the second member 62 is joined.

[0101] The welded part Wa of the article 60 formed by the friction stir welding apparatus 50 according to the present embodiment 1 is an example of the joint structure according to the present embodiment 1. Specifically, the welded part Wa of the article 60 has an annular recess 60b formed therein.

[0102] In the first embodiment, the outer peripheral surface 12b and the inner peripheral surface 12c of the tip portion 120 of the shoulder member 12 are inclined, and therefore the inner wall of the recess 60b is formed to be curved (see step (5) in FIG. 5B). That is, the shape of the tip portion 120 of the shoulder member 12 is imprinted (transferred) onto the recess 60b.

[0103] Therefore, depending on the shape of the tip portion 120 of the shoulder member 12, the inner wall of the recess 60b can be formed to be inclined, curved, curved, or bent.

[0104] In the friction stir spot welding apparatus 50 according to the first embodiment configured as described above, the tip portion 120 of the shoulder member 12 is formed in a tapered shape.

[0105] As a result, if there is no wear on the tip 120 of the shoulder member 12, when the workpieces 60 are friction stir spot welded, the shape of the tip 120 is imprinted (transferred) onto the surface 60c of the workpieces 60 (the parts to be welded). On the other hand, if there is wear on the tip 120 of the shoulder member 12, the shape of the tip 120 is not imprinted onto the surface of the workpieces 60, and the surface 60c becomes flat.

[0106] Therefore, after the friction stir spot welding is completed, it is possible to determine whether or not the tip 120 of the shoulder member 12 is worn by inspecting (visually checking) the surface of the workpiece 60. Therefore, it is no longer necessary to periodically remove the tool (pin member 11, shoulder member 12, and clamp member 13) from the friction stir spot welding apparatus 50 and inspect the wear state of the tool.

[0107] Furthermore, in the friction stir spot welding apparatus 50 according to this embodiment 1, the tip portion 120 is formed in a tapered shape, so that the area of ​​the tip surface 12a of the shoulder member 12 is smaller than that of a conventional shoulder member 12 that does not have a tapered shape, and the surface pressure can be increased.

[0108] Therefore, in the friction stir spot welding apparatus 50 according to the first embodiment, the time required for the tip surface 12a of the shoulder member 12 to reach the first position can be reduced compared to conventional friction stir spot welding apparatuses.

[0109] Incidentally, when the second member 62 of the workpiece 60 has a plating layer such as a galvannealed steel sheet, when an oxide film is formed on the surface, or when a sealant material is disposed on the surface, in order to join the workpiece 60, it is necessary to remove impurities (e.g., zinc) that form the plating layer (plating film) or oxide film and form a new surface.

[0110] In the friction stir spot welding apparatus 50 according to this embodiment 1, the tip portion 120 is formed in a tapered shape, so that the flow of impurities can be promoted along the outer peripheral surface 12b and / or inner peripheral surface 12c of the tip portion 120 of the shoulder member 12.

[0111] Therefore, in the friction stir spot welding apparatus 50 according to this embodiment 1, compared to conventional friction stir spot welding apparatuses, the time for which the tip surface 12a of the shoulder member 12 is retained at the first position can be reduced to 2 seconds or less in order to join the workpiece 60 to a sufficient joining strength.

[0112] Therefore, with the friction stir spot welding apparatus 50 according to the first embodiment, the time required to weld the articles 60 can be shortened compared to conventional friction stir spot welding apparatuses.

[0113] The friction stir spot welding apparatus according to the first embodiment is a friction stir spot welding apparatus that joins the workpieces by softening them with frictional heat, and is equipped with a cylindrically formed pin member, a cylindrically formed shoulder member through which the pin member is inserted, a rotation driver that rotates the pin member and the shoulder member around an axis that coincides with the axis of the pin member, and an advance / retract driver that moves the pin member and the shoulder member back and forth along the axis, and the tip of the shoulder member is formed tapered.

[0114] Furthermore, the friction stir spot welding apparatus according to the first embodiment may be configured so that the tip surface of the shoulder member and the tip surface of the pin member coincide with each other when viewed from the horizontal direction.

[0115] In the friction stir spot welding apparatus according to the first embodiment, the outer peripheral surface of the tip end of the shoulder member may be configured to be inclined, curved, curved, or bent.

[0116] In addition, in the friction stir spot welding apparatus according to the first embodiment, the outer peripheral surface of the tip of the shoulder member may be configured to be inclined, and the tip of the shoulder member may be configured such that, when viewed from the horizontal direction, the angle formed between the tip surface of the shoulder member and the inclined surface of the shoulder member is 6° or more and less than 45°.

[0117] In the friction stir spot welding apparatus according to the first embodiment, the inner circumferential surface of the tip end of the shoulder member may be configured to be inclined, curved, curved, or bent.

[0118] In addition, in the friction stir spot welding apparatus according to the first embodiment, the inner peripheral surface of the tip of the shoulder member may be configured to be inclined, and the tip of the shoulder member may be configured such that, when viewed from the horizontal direction, the angle formed between the tip surface of the shoulder member and the inclined surface of the shoulder member is 6° or more and less than 45°.

[0119] Furthermore, in the friction stir spot welding apparatus according to the first embodiment, the workpiece comprises a first member and a second member, the first member is disposed so as to face the pin member and the shoulder member, and is made of a material having a lower melting point than the second member, and the friction stir spot welding apparatus further comprises a controller, and the controller operates the rotation driver and the advance / retract driver so that the pin member and the shoulder member press the workpiece portion to be welded in a rotated state (A), and causes the tip of the shoulder member in the rotated state to reach a predetermined first position set in advance within the second member, The method may also be configured to (B) operate the advance / retract driver and the rotation driver so that the rotated pin member retreats from the portion to be welded of the workpiece; after (B), (C) allow the tip of the rotated shoulder member, having reached the first position, to remain there for a predetermined first time period that is set in advance; and after (C), operate the rotation driver and the advance / retract driver so that the rotated shoulder member is pulled out from the portion to be welded of the workpiece and the rotated pin member advances towards the portion to be welded of the workpiece.

[0120] Furthermore, in the friction stir spot welding apparatus according to the first embodiment, when executing (D), the controller may operate the rotation driver and the advance / retract driver so that the tip of the shoulder member reaches a predetermined second position set in advance within the first member.

[0121] Furthermore, in the friction stir spot welding apparatus according to the first embodiment, in (D), the controller may cause the tip of the shoulder member in a rotated state to remain at the second position for a predetermined second time period that has been set in advance.

[0122] Furthermore, in the friction stir spot welding apparatus according to the first embodiment, after (D), the controller may execute (E) which operates the rotation driver and the advance / retract driver so as to pull out the rotated pin member and the rotated shoulder member from the portion to be welded of the workpiece.

[0123] In the friction stir spot welding apparatus according to the first embodiment, the parts to be welded may further include a third member disposed between the first member and the second member.

[0124] In the friction stir spot welding apparatus according to the first embodiment, the first time period may be equal to or greater than 0 seconds and less than 2 seconds.

[0125] Furthermore, in the friction stir spot welding apparatus according to the first embodiment, the first position may be a position that is 0.3 mm or less from the main surface of the second member on the side facing the tip surface of the shoulder member.

[0126] Furthermore, the joint structure according to the first embodiment is a joint structure formed by friction stir spot welding at the joint portion of an object to be joined, the object comprising a first member and a second member, using a friction stir spot welding device, wherein the first member is made of a material having a lower melting point than the second member, the first member and the second member are arranged in this order, and a circular recess is formed on the surface of the joint portion, and the bottom surface of the recess is formed to be inclined, curved, curved or bent.

[0127] Furthermore, in the joint structure according to the first embodiment, the friction stir spot welding apparatus may include a pin member formed in a cylindrical shape and a shoulder member formed in a cylindrical shape and having the pin member inserted therein, and the joint structure may be formed by allowing the tip of the shoulder member in a rotated state to reach a predetermined first position within the second member and remaining there for a predetermined first time.

[0128] [Variation 1] Next, a modification of the friction stir spot welding apparatus 50 according to the first embodiment will be described.

[0129] Fig. 6 is an enlarged schematic diagram of a main part of a friction stir spot welding apparatus according to Modification 1 of Embodiment 1. Fig. 6(A) to (D) show embodiments in which the outer peripheral surface of the tip of the shoulder member is formed to be inclined, curved, curved, or bent. Fig. 6(E) to (H) show embodiments in which the inner peripheral surface of the tip of the shoulder member is formed to be inclined, curved, curved, or bent.

[0130] 6(A), in the friction stir spot welding apparatus 50 of Modification 1, the outer peripheral surface 12b of the tip portion 120 of the shoulder member 12 may be formed to be inclined. More specifically, the cross-sectional shape (cross-section along the axis Xr) of the outer peripheral surface 12b of the tip portion 120 may be formed to be inclined with respect to the axis Xr when viewed from the horizontal direction.

[0131] Furthermore, as shown in Fig. 6(B), in the friction stir spot welding apparatus 50 of Modification 1, the outer peripheral surface 12b of the tip portion 120 of the shoulder member 12 may be formed so as to be bent. More specifically, the cross-sectional shape of the outer peripheral surface 12b of the tip portion 120 may be formed so as to be bent when viewed from the horizontal direction. Note that, although Fig. 6(B) shows an embodiment with one bending point, an embodiment with multiple bending points may also be used.

[0132] 6(C), in the friction stir spot welding apparatus 50 of Modification 1, the outer peripheral surface 12b of the tip portion 120 of the shoulder member 12 may be formed to be curved (arcuate). More specifically, the cross-sectional shape of the outer peripheral surface 12b of the tip portion 120 may be formed to be curved when viewed in the horizontal direction.

[0133] 6(D), in the friction stir spot welding apparatus 50 of Modification 1, the outer peripheral surface 12b of the tip portion 120 of the shoulder member 12 may be formed in a curved shape. More specifically, the cross-sectional shape of the outer peripheral surface 12b of the tip portion 120 may be formed in a curved shape when viewed in the horizontal direction. Here, the curved curve is a curve of a function expressed by a higher-order function such as a quadratic function or a cubic function, an exponential function, a logarithmic function, or the like.

[0134] 6(E), in the friction stir spot welding apparatus 50 of Modification 1, the inner circumferential surface 12c of the tip portion 120 of the shoulder member 12 may be formed to be inclined. More specifically, the cross-sectional shape (cross-section along the axis Xr) of the inner circumferential surface 12c of the tip portion 120 may be formed to be inclined with respect to the axis Xr when viewed from the horizontal direction.

[0135] Furthermore, as shown in Fig. 6(F), in the friction stir spot welding apparatus 50 of Modification 1, the inner circumferential surface 12c of the tip portion 120 of the shoulder member 12 may be formed so as to be bent. More specifically, the cross-sectional shape of the inner circumferential surface 12c of the tip portion 120 may be formed so as to be bent when viewed from the horizontal direction. Note that, although Fig. 6(F) shows an embodiment with one bending point, an embodiment with multiple bending points may also be used.

[0136] 6(G), in the friction stir spot welding apparatus 50 of Modification 1, the inner circumferential surface 12c of the tip portion 120 of the shoulder member 12 may be formed to be curved (arcuate). More specifically, the cross-sectional shape of the inner circumferential surface 12c of the tip portion 120 may be formed to be curved when viewed in the horizontal direction.

[0137] 6(H), in the friction stir spot welding apparatus 50 of Modification 1, the inner circumferential surface 12c of the tip portion 120 of the shoulder member 12 may be formed in a curved shape. More specifically, the cross-sectional shape of the inner circumferential surface 12c of the tip portion 120 may be formed in a curved shape when viewed in the horizontal direction. Here, the curved curve is a curve of a function expressed by a higher-order function such as a quadratic function or a cubic function, an exponential function, a logarithmic function, or the like.

[0138] The friction stir spot welding apparatus 50 of the first modification thus configured also achieves the same effects as the friction stir spot welding apparatus 50 of the first embodiment.

[0139] (Embodiment 2) The friction stir spot welding apparatus of this embodiment 2 is configured in the friction stir spot welding apparatus of embodiment 1 (including modified examples) such that the tip surface of the shoulder member protrudes more than the tip surface of the pin member when viewed from the horizontal direction.

[0140] An example of the friction stir spot welding apparatus according to the second embodiment will be described in detail below with reference to the drawings.

[0141] [Configuration of friction stir spot welding equipment] FIG. 7 is a schematic diagram showing a schematic configuration of a main part of a friction stir spot welding apparatus according to the second embodiment.

[0142] As shown in Figure 7, the friction stir spot welding apparatus 50 of this embodiment 2 has the same basic configuration as the friction stir spot welding apparatus 50 of embodiment 1, but differs in that the tip surface 12a of the shoulder member 12 is configured to protrude more than the tip surface 11a of the pin member 11 when viewed from the horizontal direction.

[0143] In FIG. 7, the outer peripheral surface 12b and the inner peripheral surface 12c at the tip end 120 of the shoulder member 12 are formed so as to be inclined when viewed from the horizontal direction.

[0144] Furthermore, the outer peripheral surface 12b and the inner peripheral surface 12c of the tip portion 120 of the shoulder member 12 may be formed at the same inclination angle when viewed from the horizontal direction. Furthermore, the inclination angle α of the outer peripheral surface 12b of the tip portion 120 may be larger than the inclination angle β of the inner peripheral surface 12c of the tip portion 120. Furthermore, the inclination angle α of the outer peripheral surface 12b of the tip portion 120 may be smaller than the inclination angle β of the inner peripheral surface 12c of the tip portion 120.

[0145] Here, the inclination angle α of the outer peripheral surface 12b of the tip portion 120 and the inclination angle β of the inner peripheral surface 12c of the tip portion 120 will be described with reference to FIGS. 8A and 8B.

[0146] Fig. 8A is a schematic diagram showing the general configuration of the pin member, shoulder member, and tip portion of the clamp member of a friction stir spot welding apparatus, and Fig. 8B is an exploded view of the shear force acting on the transfer portion of the workpiece.

[0147] 8A, a portion where the shape of the outer peripheral surface 12b of the tip portion 120 of the shoulder member 12 is transferred to the portion to be joined Wa of the article to be joined 60 is defined as a transferred portion 601. Further, a protruding portion formed on the portion to be joined Wa of the article to be joined 60 by the inner peripheral surface 12c of the tip portion 120 of the shoulder member 12 and the tip portion of the pin member 11 is defined as a transferred portion 602.

[0148] The inclination angle α of the outer peripheral surface 12b of the tip portion 120 refers to the angle between the imaginary line C, which is a line perpendicular to the axis Xr, and the line connecting the base end (upper end) end A1 and the tip end (lower end) end A2 at which the outer peripheral surface 12b is inclined.

[0149] Similarly, the inclination angle β of the inner surface 12c of the tip portion 120 refers to the angle between the imaginary line C and the line connecting the base end (upper end) end B1 and the tip end (lower end) end B2 where the inner surface 12c is inclined.

[0150] Therefore, when the outer peripheral surface 12b and inner peripheral surface 12c of the tip portion 120 are curved, as shown in the modified example of embodiment 1, the line connecting the curved base end portion and the tip end portion, and the virtual line C, respectively, have an inclination angle α and an inclination angle β.

[0151] 8A, as the inclination angle α of the outer peripheral surface 12b increases, the angle θ1 of the inclined surface of the transfer portion 601 also increases. If the angle θ1 of the inclined surface of the transfer portion 601 increases, the base (area of ​​the base) of the transfer portion 601 decreases, and there is a risk that the transfer portion 601 will be damaged (torn).

[0152] Similarly, as the inclination angle β of the inner circumferential surface 12c increases, the angle θ2 of the inclined surface of the transfer portion 602 also increases. As the angle θ2 of the inclined surface of the transfer portion 602 increases, the base (area of ​​the base) of the transfer portion 602 decreases, and there is a risk that the transfer portion 602 will be damaged (pulled off).

[0153] In addition, when the tip of the pin member 11 and the tip of the shoulder member 12 are separated from the workpiece 60, shear forces F1 and F2 act on the inclined surface of the transfer portion 601 (contact surface with the outer peripheral surface 12b) and the inclined surface of the transfer portion 602 (contact surface with the inner peripheral surface 12c), respectively.

[0154] As shown in FIG. 8B(1), F1 sin θ1 acts as a force that rips off the transfer portion 601. Similarly, F2 sin θ2 acts as a force that rips off the transfer portion 602 (see FIG. 8B(2)). Here, when θ1=45°, F1 sin θ1=F1 cos θ1. Similarly, when θ2=45°, F2 sin θ2=F2 cos θ2. Furthermore, θ1=tilt angle α, and θ2=tilt angle β.

[0155] Therefore, when θ1<45°, i.e., when the tilt angle α<45°, it is possible to suppress tearing of the transfer part 601. Similarly, when θ2<45°, i.e., when the tilt angle β<45°, it is possible to suppress tearing of the transfer part 602.

[0156] Therefore, the inclination angle α of the outer peripheral surface 12b of the tip portion 120 is preferably less than 45°, and the inclination angle β of the inner peripheral surface 12c of the tip portion 120 is preferably less than 45°.

[0157] Furthermore, based on the results of Test Examples 1 and 2 described below, the inclination angle α may be 32° or less, 17° or less, 12° or less, or 6° or less. Similarly, the inclination angle β may be 32° or less, 17° or less, 12° or less, or 6° or less.

[0158] The friction stir spot welding apparatus 50 according to the second embodiment configured in this manner also achieves the same effects as the friction stir spot welding apparatus 50 according to the first embodiment. (Embodiment 3) The friction stir spot welding apparatus according to the third embodiment is a friction stir spot welding apparatus that joins the workpieces by softening them with frictional heat, and comprises a cylindrical pin member, a cylindrical shoulder member through which the pin member is inserted, a rotation driver that rotates the pin member and the shoulder member around an axis that coincides with the axis of the pin member, and an advance / retract driver that moves the pin member and the shoulder member back and forth along the axis, and a recess extending circumferentially is formed on the tip surface of the shoulder member.

[0159] An example of a friction stir spot welding apparatus according to the third embodiment will be described in detail below with reference to the drawings.

[0160] [Configuration of friction stir spot welding equipment] FIG. 9 is a schematic diagram showing a schematic configuration of a main part of a friction stir spot welding apparatus according to the third embodiment.

[0161] As shown in Figure 9, the friction stir spot welding apparatus 50 according to the third embodiment has the same basic configuration as the friction stir spot welding apparatus 50 according to the first embodiment, but differs in that a (annular) recess 20 extending circumferentially is formed on the tip surface 12a of the shoulder member 12.

[0162] The recess 20 may be formed so that the area of ​​the opening 20A is larger than the area of ​​the bottom surface 20B. At least one of the inner circumferential surface 20C and the outer circumferential surface 20D of the recess 20 may be formed so as to be parallel to the axis Xr. Furthermore, at least one of the inner circumferential surface 20C and the outer circumferential surface 20D of the recess 20 may be formed so as to be inclined, curved, curved, or bent.

[0163] Furthermore, the depth d of the recess 20 may be, for example, 0.05 mm or more, or 5% or more of the thickness dimension of the first member 61, from the viewpoint of imprinting (transferring) the shape of the tip portion 120 on the surface of the article 60. Furthermore, the depth d may be, for example, 0.5 mm or less, or 50% or less of the thickness dimension of the first member 61, from the viewpoint of suppressing damage to the tip portion 120 of the shoulder member 12.

[0164] The friction stir spot welding apparatus 50 according to the third embodiment configured in this manner also achieves the same effects as the friction stir spot welding apparatus 50 according to the first embodiment.

[0165] In the third embodiment, the recess 20 is formed in the tip surface 12a of the shoulder member 12, but the present invention is not limited to this. An annular recess 20 may be formed in the tip surface 11a of the pin member 11.

[0166] [Test example] Next, a joining test of an article 60 to be welded using the friction stir spot welding apparatus 50 according to the second embodiment and the friction stir spot welding method disclosed in the above Patent Document 1 will be described.

[0167] (Test Example 1) A welding test of the workpiece 60 was carried out using the friction stir spot welding apparatus 50 according to embodiment 2. In test example 1, the height of the tip portion 120 was set to 0.2 mm. The inclination angle α of the outer peripheral surface 12b of the tip portion 120 was set to 12°, and the inclination angle β of the inner peripheral surface 12c of the tip portion 120 was set to 32°.

[0168] (Test Example 2) A welding test of the workpiece 60 was carried out using the friction stir spot welding apparatus 50 according to embodiment 2. In test example 2, the height of the tip portion 120 was set to 0.1 mm. The inclination angle α of the outer peripheral surface 12b of the tip portion 120 was set to 6°, and the inclination angle β of the inner peripheral surface 12c of the tip portion 120 was set to 17°.

[0169] (Comparative Example) As a comparative example, a joining test of the workpiece 60 was carried out by the friction stir spot welding method disclosed in Patent Document 1. Specifically, as the friction stir spot welding device of the comparative example, a shoulder member 12 in which the inner and outer peripheral surfaces of the tip portion 120 are formed parallel to the axis Xr was used, and a joining test of the workpiece 60 was carried out.

[0170] (Joining conditions) The first member 61 is made of a 1 mm aluminum plate (A6061), and the second member 62 is made of a 1 mm aluminum plate (A6061). As the specimen, a 1.2 mm thick 980 MPa grade galvannealed steel sheet (GA) was used.

[0171] In Test Example 1, the first position, which is the target position of the shoulder member 12, was set to a position 0.3 mm below the contact surface (upper surface) of the second member 62 with the first member 61. In Test Example 2, the first position was set to a position 0.2 mm below the contact surface (upper surface) of the second member 62 with the first member 61. In the Comparative Example, the first position, which is the target position of the shoulder member 12, was set to a position 0.1 mm below the contact surface (upper surface) of the second member 62 with the first member 61.

[0172] In addition, the time (first time) for which the tip surface 12a of the shoulder member 12 was held at the first position after it reached the first position was changed to 0, 1, 2, or 3 seconds, and the workpieces 60 were welded. In addition, the first rotation speed, which is the rotation speed of the pin member 11 and the shoulder member 12, was set to 2000 rpm.

[0173] Then, the articles 60 welded using the friction stir spot welding apparatuses of Test Examples 1 and 2 and Comparative Example were subjected to a tensile shear test (JIS Z 3136) and a cross tension test (JIS Z 3137).

[0174] (Test results) Fig. 10 is a graph showing the results of a tensile shear test and a cross tension test of workpieces friction stir spot welded under the above-mentioned welding conditions using the friction stir spot welding devices of Test Examples 1 and 2 and the Comparative Example. Fig. 11 is a cross-sectional photograph of workpieces friction stir spot welded using the friction stir spot welding device of Test Example 1.

[0175] As shown in Fig. 10, when friction stir spot welding was performed using the friction stir spot welding apparatus of the comparative example, sufficient joint strength could not be obtained when the first time was 0 seconds. Furthermore, with the friction stir spot welding apparatus of the comparative example, sufficient joint strength was obtained in the tensile shear test (TSS) when the first time was 1 second, but sufficient joint strength could not be obtained in the cross tension test (CTS) unless the first time was 2 seconds or more.

[0176] On the other hand, when friction stir spot welding was performed using the friction stir spot welding devices of Test Examples 1 and 2, sufficient joint strength was obtained even when the first time was 0 seconds.

[0177] These results show that with the friction stir spot welding apparatus 50 according to the first embodiment, the workpieces 60 can be welded with sufficient welding strength if the first time period is set to 0 seconds or more and less than 2 seconds.

[0178] Furthermore, as shown in Figure 11, when friction stir spot welding is performed using the friction stir spot welding device of Test Example 1, if there is no wear on the tip 120 of the shoulder member 12, it was shown that the shape of the tip 120 (tapered shape; transfer portion) is imprinted (transferred) on the surface 60c of the workpiece 60 (workpiece to be welded).

[0179] From the above description, many improvements and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function thereof may be substantially changed without departing from the present invention. Furthermore, various inventions may be formed by appropriate combinations of multiple components disclosed in the above embodiments. [Industrial Applicability]

[0180] The friction stir spot welding apparatus of the present invention is useful because it can determine the wear state of the tool from the welding spot (surface of the part to be welded) of the workpiece. [Explanation of symbols]

[0181] 11 Pin member 11a Tip surface 12 Shoulder member 12a Tip surface 12b Outer surface 12c Inner surface 12d tip 12e proximal end 13 Clamping member 13a Tip surface 20 recess 20A opening 20B Bottom 20C Inner surface 20D outer surface 31 Memory device 32 Input device 33 Position detector 41 Clamp driver 50 Friction stir spot welding equipment 51 Controller 52 Tool retainer 53 Advance / retreat driver 55 Backing support 56 Backing member 56a Support surface 57 Rotary drive 60 Object to be joined 60a Plastic flow section 60b recess 60c surface 61 First member 62 Second member 62a Contact surface 120 Tip 521 Rotary tool holder 522 Clamp Fixator 531 Pin Driver 532 Shoulder Actuator 601 Transcription unit 602 Script Department d deep h high Xr axis Wa joined part α Tilt angle β tilt angle θ1 angle θ2 angle

Claims

1. A friction stir spot joining apparatus that joins objects to be joined by softening them with frictional heat, The friction stir spot welding apparatus is a pin member formed in a cylindrical shape; a shoulder member formed in a cylindrical shape and having the pin member inserted therethrough; a rotation driver that rotates the pin member and the shoulder member around an axis that coincides with the axis of the pin member; an advance / retract driver that moves the pin member and the shoulder member back and forth along the axis, The tip of the shoulder member is formed in a tapered shape, A friction stir spot welding device, wherein the tip portion of the shoulder member has an inner peripheral surface and an outer peripheral surface, and the inner peripheral surface or the outer peripheral surface is a tapered surface whose axial inclination width is larger than its radial inclination width.

2. The friction stir spot welding device according to claim 1 , wherein the outer peripheral surface of the tip of the shoulder member is configured to be inclined, curved, curved, or bent.

3. 3. The friction stir spot welding device according to claim 1, wherein the inner peripheral surface of the tip of the shoulder member is configured to be inclined, curved, curved, or bent.

4. A friction stir spot joining apparatus that joins objects to be joined by softening them with frictional heat, The friction stir spot welding apparatus is a pin member formed in a cylindrical shape; a shoulder member formed in a cylindrical shape and having the pin member inserted therethrough; a rotation driver that rotates the pin member and the shoulder member around an axis that coincides with the axis of the pin member; an advance / retract driver that moves the pin member and the shoulder member back and forth along the axis; a controller; The tip of the shoulder member is formed in a tapered shape, the tip end portion of the shoulder member has an inner circumferential surface and an outer circumferential surface, and the inner circumferential surface or the outer circumferential surface is a tapered surface whose axial inclination width is larger than its radial inclination width, the object to be welded comprises a first member and a second member, the first member is disposed so as to face the pin member and the shoulder member, and is made of a material having a lower melting point than the second member, the controller operates the rotation driver and the advance / retract driver so that the pin member and the shoulder member press against the portion to be welded of the workpiece in a rotated state (A); (B) operating the advance / retreat driver and the rotation driver so that the tip of the shoulder member in the rotated state reaches a predetermined first position set in advance within the second member and the pin member in the rotated state retreats from the portion to be welded of the workpiece; After (B), (C) is performed in which the tip of the shoulder member in a rotated state reaches the first position and is held there for a predetermined first time period. After (C), (D) is performed by operating the rotation driver and the advance / retract driver so as to pull out the shoulder member in a rotated state from the portion to be welded of the workpiece, and to advance the pin member in a rotated state toward the portion to be welded of the workpiece.

5. The friction stir spot welding apparatus according to claim 4 , wherein the first time period is longer than 0 seconds and shorter than 2 seconds.

6. The friction stir spot welding apparatus according to claim 4 or 5, wherein the first position is a position that is 0.3 mm or less from a contact surface of the second member with the first member.

7. A friction stir spot welding device that joins objects to be welded by softening them with frictional heat, a pin member formed in a cylindrical shape; a shoulder member formed in a cylindrical shape and having the pin member inserted therethrough; a rotation driver that rotates the pin member and the shoulder member around an axis that coincides with the axis of the pin member; an advance / retract driver that moves the pin member and the shoulder member back and forth along the axis, The tip of the shoulder member is formed in a tapered shape, the tip end portion of the shoulder member has an inner circumferential surface and an outer circumferential surface, and the inner circumferential surface or the outer circumferential surface is a tapered surface whose axial inclination width is larger than its radial inclination width, the object to be welded comprises a first member and a second member, the first member is disposed so as to face the pin member and the shoulder member, and is made of a material having a lower melting point than the second member, (A) operating the rotation driver and the advance / retract driver so that the pin member and the shoulder member press against the portion to be welded of the workpiece while rotating; (B) operating the advance / retreat driver and the rotation driver so that the tip of the shoulder member in the rotated state reaches a predetermined first position set in advance within the second member and the pin member in the rotated state retreats from the portion to be welded of the workpiece; After (B), (C) is performed in which the tip of the shoulder member in a rotated state reaches the first position and is held there for a predetermined first time period. After (C), (D) operates the rotation driver and the advance / retract driver so as to pull out the shoulder member in the rotated state from the portion to be welded of the workpiece and to advance the pin member in the rotated state toward the portion to be welded of the workpiece, Friction stir spot welding method.

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