Friction stir welding method, automobile part manufacturing method, machine tool, and program

Abstract

A first workpiece has a recess defined by a plurality of surfaces including a first surface whose height gradually decreases in a first direction and a second surface whose height gradually increases in the first direction, and a second workpiece is friction stir welded together. The friction stir welding method includes: when the depth direction of the recess is defined as the second direction, moving the friction stir welding tool in the first direction while moving the friction stir welding tool in the second direction so as to follow changes in the height of the first surface; and when the direction opposite to the second direction is defined as the third direction, moving the friction stir welding tool in the first direction while moving the friction stir welding tool in the third direction so as to follow changes in the height of the second surface. In the friction stir welding method, the position of the friction stir welding tool is controlled so as to suppress fluctuations in the axial loads that the friction stir welding tool receives from the first workpiece and the second workpiece.

Description

Technical Field

[0001] The present invention relates to a friction stir welding method, a method for manufacturing automotive parts, a machine tool, and a program.

Background Art

[0002] A friction stir welding method is known.

[0003] As a related technique, Patent Document 1 discloses a friction stir welding method. The friction stir welding method described in Patent Document 1 is executed using a joining device including a support and a probe configured to be able to advance and retreat in the axial direction with respect to the support. In the friction stir welding method described in Patent Document 1, the protruding amount of the probe with respect to the support is configured to change according to the depth of the changing joining site.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a friction stir welding method, a method for manufacturing automotive parts, a machine tool, and a program capable of smoothly friction stir welding a first workpiece having a recess and a second workpiece overlapping the first workpiece. Another optional object of the present invention is to provide a technique for manufacturing automotive parts such as a battery case, an inverter case, or a motor case by friction stir welding a first workpiece having a recess and a second workpiece.

Means for Solving the Problems

[0006] A friction stir welding method in some embodiments comprises the steps of: preparing a first workpiece having a recess defined by a plurality of surfaces including a first surface whose height gradually decreases in a first direction and a second surface whose height gradually increases in the first direction; preparing a second workpiece; overlapping the first workpiece and the second workpiece such that a first region is formed where the first workpiece and the second workpiece are in contact; a second region in which the gap between the first surface and the second workpiece gradually increases from zero in the first direction; and a third region in which the gap between the second surface and the second workpiece gradually decreases to zero in the first direction; and friction stir welding the first workpiece and the second workpiece using a friction stir welding tool. The step of friction stir welding the first workpiece and the second workpiece includes moving the friction stir welding tool in a first direction such that the probe of the friction stir welding tool crosses at least a portion of the first region; when the depth direction of the recess is defined as the second direction, moving the friction stir welding tool in a second direction so as to follow the change in height of the first surface while moving the friction stir welding tool in a second direction so as to follow the change in height of the first surface while moving the friction stir welding tool in a third direction so as to follow the change in height of the second surface while moving the friction stir welding tool in a first direction so as to follow the change in height of the second surface while moving the friction stir welding tool in a third direction so as to follow the change in height of the second surface while moving the friction stir welding tool in a first direction so as to to follow the change in height of the second surface while moving the friction stir welding tool in a first direction so as to to follow the change in axial load received by the friction stir welding tool from the first workpiece and the second workpiece as the probe moves in the first direction across each of the second and third regions.

[0007] A method for manufacturing an automobile part in some embodiments comprises the steps of: preparing a first part having a recess defined by a plurality of surfaces including a first surface whose height gradually decreases in a first direction and a second surface whose height gradually increases in the first direction; preparing a second part; overlapping the first part and the second part such that a first region is formed in which the first part and the second part are in contact; a second region in which the gap between the first surface and the second part gradually increases from zero in the first direction; and a third region in which the gap between the second surface and the second part gradually decreases to zero in the first direction; and friction stir welding the first part and the second part using a friction stir welding tool. The step of friction stir welding the first part and the second part includes moving the friction stir welding tool in a first direction such that the probe of the friction stir welding tool crosses at least a portion of the first region; when the depth direction of the recess is defined as the second direction, moving the friction stir welding tool in a second direction so as to follow the change in height of the first surface while moving the friction stir welding tool in a second direction so as to cross the second region, while defining the direction opposite to the second direction as the third direction; and when the friction stir welding tool is moved in a third direction so as to follow the change in height of the second surface while moving the friction stir welding tool in a third direction so as to cross the third region, while defining the direction opposite to the second direction. The position of the friction stir welding tool is controlled so that fluctuations in the axial loads that the friction stir welding tool receives from the first part and the second part are suppressed as the probe moves in the first direction across each of the second and third regions.

[0008] In some embodiments, the machine tool comprises a work support member for supporting a first workpiece and a second workpiece; a machining head that rotatably supports a probe of a friction stir welding tool around a rotation axis; a rotary drive device for rotating the probe around the rotation axis; a moving device for moving the machining head relative to the work support member; and a control device for controlling the rotary drive device and the moving device. The control device is capable of executing a friction stir welding mode in which the first workpiece and the second workpiece are friction stir-welded together while the second workpiece is superimposed on the first workpiece which has a recess defined by a plurality of surfaces including a first surface whose height gradually decreases in a first direction and a second surface whose height gradually increases in a first direction. The friction stir welding mode includes moving the friction stir welding tool in a first direction such that the probe crosses at least a portion of a first region in which the first workpiece and the second workpiece are in contact; moving the friction stir welding tool in a second direction in a manner that follows changes in the height of the first surface, while moving the friction stir welding tool in a manner that follows changes in the height of the first surface, while moving the friction stir welding tool in a manner that follows changes in the height of the second the probe crosses a second region in which the gap between the second surface and the second workpiece is in contact. As the probe moves in the first direction across each of the second and third regions, the control device controls the position of the friction stir welding tool so as to suppress fluctuations in the axial loads that the friction stir welding tool receives from the first and second workpieces.

[0009] In some embodiments, the program is a program for causing a machine tool to execute a friction stir welding method comprising the steps of: preparing a first workpiece having a recess defined by a plurality of surfaces including a first surface whose height gradually decreases in a first direction and a second surface whose height gradually increases in the first direction; and friction stir welding the first workpiece and the second workpiece using a friction stir welding tool while the first workpiece and the second workpiece are superimposed on each other. The step of preparing the first workpiece includes forming the recess using a cutting tool. The step of friction stir welding the first workpiece and the second workpiece includes: moving the friction stir welding tool in a first direction such that the probe of the friction stir welding tool crosses at least a portion of a first region in which the first workpiece and the second workpiece are in contact; moving the friction stir welding tool in a second direction in a way that follows the change in height of the first surface, while moving the friction stir welding tool in a way that follows the change in height of the first surface, while moving the friction stir welding tool in a way that follows the change in height of the first surface, while moving the friction stir welding tool in a way that follows the change in height of the second crosses a third region in a way that crosses a third region in a way that the gap between the second surface and the second workpiece is gradually reduced to zero in the first direction, while defining the direction opposite to the second direction. The step of friction stir welding the first workpiece and the second workpiece includes controlling the position of the friction stir welding tool such that fluctuations in the axial loads received by the friction stir welding tool from the first workpiece and the second workpiece are suppressed as the probe moves in the first direction across each of the second and third regions. [Effects of the Invention]

[0010] The present invention provides a friction stir welding method, a method for manufacturing automotive parts, a machine tool, and a program that enable smooth friction stir welding of a first workpiece having a recess and a second workpiece overlapping the first workpiece. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating an example of the first workpiece. [Figure 2] Figure 2 is a schematic cross-sectional view illustrating another example of the first workpiece. [Figure 3] Figure 3 is a schematic cross-sectional view illustrating an example of the second workpiece. [Figure 4] Figure 4 is a schematic cross-sectional view illustrating the state in which the first workpiece and the second workpiece are superimposed. [Figure 5] Figure 5 is a schematic cross-sectional view illustrating how the probe moves in the first direction across at least a portion of the first region. [Figure 6] Figure 6 is a schematic cross-sectional view illustrating the movement of the probe across the second region in the first direction. [Figure 7] Figure 7 is a schematic cross-sectional view illustrating the movement of the probe across the fourth region in the first direction. [Figure 8] Figure 8 is a schematic cross-sectional view illustrating the movement of the probe across the third region in the first direction. [Figure 9] Figure 9 is a schematic cross-sectional view illustrating how the probe moves in the first direction across at least a portion of the fifth region. [Figure 10] Figure 10 is a schematic cross-sectional view illustrating an example of a joined article formed by friction stir welding. [Figure 11] Figure 11 is a flowchart showing a friction stir welding method in an embodiment. [Figure 12] Figure 12 is a schematic perspective view illustrating how the plate is superimposed on the case body. [Figure 13] Figure 13 is a schematic perspective view illustrating an example of an automobile part formed by friction stir welding. [Figure 14] Figure 14 is a schematic perspective view illustrating how the plate is superimposed on the case body. [Figure 15]FIG. 15 is a schematic perspective view schematically showing another example of an automotive part formed by friction stir welding. [Figure 16] FIG. 16 is a schematic perspective view schematically showing yet another example of an automotive part formed by friction stir welding. [Figure 17] FIG. 17 is a diagram schematically showing a machine tool in the first embodiment. [Figure 18] FIG. 18 is a diagram schematically showing a machine tool in the first modification of the first embodiment. [Figure 19] FIG. 19 is a diagram schematically showing a machine tool in the second modification of the first embodiment. [Figure 20] FIG. 20 is a diagram schematically showing a machine tool in the third modification of the first embodiment. [Figure 21] FIG. 21 is a schematic cross-sectional view schematically showing an example of a first workpiece including a welded portion. [Figure 22] FIG. 22 is a schematic cross-sectional view schematically showing a state in which a recess is formed by cutting the welded portion and a portion adjacent to the welded portion. [Figure 23] FIG. 23 is a diagram schematically showing a state in which a first surface whose height gradually decreases in a first direction is formed by cutting a first step portion. [Figure 24] FIG. 24 is a diagram schematically showing a state in which a second surface whose height gradually increases in a first direction is formed by cutting a second step portion. [Figure 25] FIG. 25 is a schematic cross-sectional view schematically showing a friction stir welding method in a first comparative example. [Figure 26] FIG. 26 is a schematic cross-sectional view schematically showing a friction stir welding method in a second comparative example. [Figure 27] FIG. 27 is a schematic cross-sectional view schematically showing a state in which a first surface is directly formed by cutting the welded portion and a portion adjacent to the welded portion. [Figure 28] FIG. 28 is a schematic cross-sectional view schematically showing a state in which a recess including a first surface and a second surface is directly formed by cutting the welded portion and a portion adjacent to the welded portion. [Figure 29] Figure 29 is a schematic perspective view illustrating how the recess extends along the fourth direction. [Figure 30] Figure 30 is a schematic perspective view showing the first and second workpieces superimposed on each other, with the fourth-direction end of the recess open. [Figure 31] Figure 31 is a schematic perspective view illustrating an example of a probe moving along a curved path. [Figure 32] Figure 32 is a schematic diagram showing a machine tool in a fourth modified example of the first embodiment. [Figure 33] Figure 33 is a schematic diagram illustrating how a controlled device can be controlled by a control device. [Figure 34] Figure 34 is a schematic cross-sectional view illustrating the first movement path across the recess. [Figure 35] Figure 35 is a schematic diagram showing a machine tool in the second embodiment. [Figure 36] Figure 36 is a schematic perspective view showing a portion of the machine tool in the second embodiment. [Figure 37] Figure 37 is a schematic diagram showing a machine tool in the second embodiment. [Figure 38] Figure 38 is a schematic diagram showing an example of a storage medium on which a program is recorded. [Figure 39] Figure 39 is a schematic diagram showing a machine tool in a modified example of the embodiment. [Figure 40] Figure 40 is a schematic diagram showing a machine tool in another modified embodiment. [Modes for carrying out the invention]

[0012] The friction stir welding method, the method for manufacturing automobile parts, the machine tool 1, and the program in the embodiment will be described below with reference to the drawings. In the following description of the embodiment, parts and components having the same function will be denoted by the same reference numeral, and repeated descriptions of parts and components denoted by the same reference numeral will be omitted.

[0013] (First embodiment) Referring to Figures 1 to 34, the friction stir welding method, the method for manufacturing automobile parts, and the machine tool 1A in the first embodiment will be described. Figure 1 is a schematic cross-sectional view illustrating an example of the first workpiece 8. Figure 2 is a schematic cross-sectional view illustrating another example of the first workpiece 8. Figure 3 is a schematic cross-sectional view illustrating an example of the second workpiece 9. Figure 4 is a schematic cross-sectional view illustrating the state in which the first workpiece 8 and the second workpiece 9 are superimposed. Figure 5 is a schematic cross-sectional view illustrating how the probe 21 moves in the first direction DR1 across at least a part of the first region RG1. Figure 6 is a schematic cross-sectional view illustrating how the probe 21 moves in the first direction DR1 across the second region RG2. Figure 7 is a schematic cross-sectional view illustrating how the probe 21 moves in the first direction DR1 across the fourth region RG4. Figure 8 is a schematic cross-sectional view illustrating how the probe 21 moves in the first direction DR1 across the third region RG3. Figure 9 is a schematic cross-sectional view illustrating how the probe 21 moves in the first direction DR1 across at least a portion of the fifth region RG5. Figure 10 is a schematic cross-sectional view illustrating an example of a joined article D formed by friction stir welding. Figure 11 is a flowchart illustrating the friction stir welding method in an embodiment. Figure 12 is a schematic perspective view illustrating how the plate 9b is superimposed on the case body 8b. Figure 13 is a schematic perspective view illustrating an example of an automobile part formed by friction stir welding. Figure 14 is a schematic perspective view illustrating how the plate 9c is superimposed on the case body 8c. Figure 15 is a schematic perspective view illustrating another example of an automobile part formed by friction stir welding. Figure 16 is a schematic perspective view illustrating yet another example of an automobile part formed by friction stir welding. Figure 17 is a schematic diagram illustrating the machine tool 1A in the first embodiment. Figure 18 is a schematic diagram illustrating the machine tool 1A in a first modification of the first embodiment. Figure 19 is a schematic diagram showing a machine tool 1A in a second modified example of the first embodiment. Figure 20 is a schematic diagram showing a machine tool 1A in a third modified example of the first embodiment. Figure 21 is a schematic cross-sectional view showing an example of a first workpiece 8 including a welded portion 87.Figure 22 is a schematic cross-sectional view illustrating how a recess 85 is formed by cutting the welded portion 87 and the portion adjacent to the welded portion 87. Figure 23 is a schematic view illustrating how a first surface 82a, whose height gradually decreases in the first direction DR1, is formed by cutting the first stepped portion 84a. Figure 24 is a schematic view illustrating how a second surface 82b, whose height gradually increases in the first direction DR1, is formed by cutting the second stepped portion 84b. Figure 25 is a schematic cross-sectional view illustrating the friction stir welding method in the first comparative example. Figure 26 is a schematic cross-sectional view illustrating the friction stir welding method in the second comparative example. Figure 27 is a schematic cross-sectional view illustrating how the first surface 82a is directly formed by cutting the welded portion 87 and the portion adjacent to the welded portion 87. Figure 28 is a schematic cross-sectional view illustrating how a recess 81, including the first surface 82a and the second surface 82b, is directly formed by cutting the welded portion 87 and the portion adjacent to the welded portion 87. Figure 29 is a schematic perspective view illustrating how the recess 81 extends along the fourth direction DR4. Figure 30 is a schematic perspective view illustrating how the end 81e of the recess 81 on the fourth direction DR4 side is open when the first workpiece 8 and the second workpiece 9 are superimposed. Figure 31 is a schematic perspective view illustrating an example where the probe 21 moves along a curved path PA2. Note that in Figures 30 and 31, a portion of the second workpiece 9 is cut out to make it easier to understand the state of the recess 81 located below the second workpiece 9. Figure 32 is a schematic diagram illustrating a machine tool 1A in a fourth modified example of the first embodiment. Figure 33 is a schematic diagram illustrating how the controlled device can be controlled by the control device 7. Figure 34 is a schematic cross-sectional view illustrating the first movement path PA that crosses the recess 81.

[0014] As illustrated in Figure 1, in the first step ST1, the first workpiece 8 is prepared. The first step ST1 is the first preparation step. The first workpiece 8 prepared in the first preparation step has a recess 81. The recess 81 is defined by a plurality of surfaces 82, including a first surface 82a whose height gradually decreases in the first direction DR1 and a second surface 82b whose height gradually increases in the first direction DR1.

[0015] In this specification, "height" refers to the height relative to the deepest part of the recess 81. In other words, when the depth direction of the recess 81 is defined as the second direction DR2, and the direction opposite to the second direction DR2 is defined as the third direction DR3, "height" in this specification refers to the distance from the deepest part of the recess 81 along the third direction DR3. This "height" does not change depending on the orientation of the first workpiece 8.

[0016] In the example shown in Figure 1, the first surface 82a is a planar inclined surface PS1. Alternatively, as illustrated in Figure 2, the first surface 82a may be a curved inclined surface CS1 (for example, an arc-shaped inclined surface). In the example shown in Figure 1, the second surface 82b is a planar inclined surface PS2. Alternatively, as illustrated in Figure 2, the second surface 82b may be a curved inclined surface CS2 (for example, an arc-shaped inclined surface).

[0017] In the example shown in Figure 1, the third surface 82c is positioned between the first surface 82a and the second surface 82b. Alternatively, the third surface 82c may be omitted. If the third surface 82c is omitted, each of the first surface 82a and the second surface 82b may be a planar inclined surface or a curved inclined surface (for example, an arc-shaped inclined surface).

[0018] As illustrated in Figure 3, in the second step ST2, the second workpiece 9 is prepared. The second step ST2 is the second preparation step.

[0019] As illustrated in Figure 4, in the third step ST3, the first workpiece 8 and the second workpiece 9 are superimposed. The third step ST3 is a superimposing step. In the superimposing step, the first workpiece 8 and the second workpiece 9 are superimposed such that a first region RG1 is formed where the first workpiece 8 and the second workpiece 9 are in contact, a second region RG2 is formed where the gap G2 between the first surface 82a and the second workpiece 9 gradually increases from zero in the first direction DR1, and a third region RG3 is formed where the gap G3 between the second surface 82b and the second workpiece 9 gradually decreases to zero in the first direction DR1.

[0020] In this specification, "gradual increase" means a continuous and gradual increase. In this specification, "gradual increase" includes a substantial gradual increase. In other words, even if there is a slight deviation from a perfect gradual increase due to the surface roughness of the first workpiece 8 or the machining accuracy of the recess 81, it will still be considered a "gradual increase."

[0021] In this specification, "gradual reduction" means a continuous and gradual decrease. In this specification, "gradual reduction" includes substantial reduction. In other words, even if there is a slight deviation from a perfect reduction due to the surface roughness of the first workpiece 8 or the machining accuracy of the recess 81, it is still considered a "gradual reduction."

[0022] In the example shown in Figure 4, with the first workpiece 8 and the second workpiece 9 superimposed, the first region RG1, the second region RG2, the fourth region RG4, the third region RG3, and the fifth region RG5 are formed in this order along the first direction DR1. In the fourth region RG4, the first workpiece 8 and the second workpiece 9 are separated, while in the fifth region RG5, the first workpiece 8 and the second workpiece 9 are in contact. Note that if the third surface 82c of the first workpiece 8 is omitted, the fourth region RG4 is also omitted.

[0023] In the example shown in Figure 4, the second direction DR2 (in other words, the depth direction of the recess 81) coincides with the direction from the second workpiece 9 to the first workpiece 8. Also, the third direction DR3 coincides with the direction from the first workpiece 8 to the second workpiece 9.

[0024] As illustrated in Figures 5 to 9, in the fourth step ST4, the first workpiece 8 and the second workpiece 9 are friction stir welded. The fourth step ST4 is a joining process. The joining process is performed using a friction stir welding tool 2. The joining process produces a joined article D in which the first workpiece 8 and the second workpiece 9 are joined (see Figure 10).

[0025] As illustrated in Figure 5, the joining process (fourth step ST4) includes moving the friction stir welding tool 2 in the first direction DR1 such that the probe 21 of the friction stir welding tool 2 crosses at least a portion of the first region RG1 described above. As a result of this movement, the first workpiece 8 and the second workpiece 9 are friction stir-welded in the portion of the first region RG1 through which the probe 21 passes.

[0026] As illustrated in Figure 6, the joining process (fourth step ST4) includes moving the friction stir welding tool 2 in the first direction DR1 so that the probe 21 crosses the second region RG2, and gradually moving the friction stir welding tool 2 in the second direction DR2 to follow the change in height of the first surface 82a. Through this movement, the first workpiece 8 and the second workpiece 9 are friction stir-welded in the portion of the second region RG2 through which the probe 21 passes.

[0027] In the example shown in Figure 7, the joining process (fourth step ST4) includes moving the friction stir welding tool 2 in the first direction DR1 so that the probe 21 crosses the fourth region RG4 described above. This movement causes the first workpiece 8 and the second workpiece 9 to be friction stir-welded in the portion of the fourth region RG4 through which the probe 21 passes. If the third surface 82c of the first workpiece 8 is omitted, the step of the probe 21 crossing the fourth region RG4 is also omitted.

[0028] As illustrated in Figure 8, the joining process (fourth step ST4) includes moving the friction stir welding tool 2 in the first direction DR1 so that the probe 21 crosses the third region RG3, and gradually moving the friction stir welding tool 2 in the third direction DR3 to follow the change in height of the second surface 82b. Through this movement, the first workpiece 8 and the second workpiece 9 are friction stir-welded in the portion of the third region RG3 through which the probe 21 passes.

[0029] As illustrated in Figure 9, the joining process (fourth step ST4) includes moving the friction stir welding tool 2 in the first direction DR1 such that the probe 21 of the friction stir welding tool 2 crosses at least a portion of the fifth region RG5 described above. This movement causes the first workpiece 8 and the second workpiece 9 to be friction stir-welded in the portion of the fifth region RG5 through which the probe 21 passes.

[0030] In the examples shown in Figures 5 to 9, the probe 21, rotating around the rotation axis AX, traverses the first region RG1, the second region RG2, the fourth region RG4, the third region RG3, and the fifth region RG5 in that order, thereby friction stir welding the first workpiece 8 and the second workpiece 9. In this way, a joined article D is manufactured in which the first workpiece 8 and the second workpiece 9 are joined (see Figure 10).

[0031] In the examples shown in Figures 6 and 8, the position of the friction stir welding tool 2 is controlled such that fluctuations in the axial load F (in other words, the load in the direction along the rotation axis AX of the probe 21) received by the friction stir welding tool 2 from the first workpiece 8 and the second workpiece 9 are suppressed as the probe 21 moves in the first direction DR1 across the second region RG2 and the third region RG3, respectively.

[0032] In the friction stir welding method of the first embodiment, the first surface 82a is a surface whose height gradually decreases in the first direction DR1, and the second surface 82b is a surface whose height gradually increases in the first direction DR1. Therefore, compared to the case where each of the first surface 82a and the second surface 82b is a clearly stepped surface, defects (more specifically, voids) are less likely to occur in the joint between the first workpiece 8 and the second workpiece 9.

[0033] The friction stir welding method in the first embodiment includes moving the friction stir welding tool 2 in a first direction DR1 while moving the friction stir welding tool 2 to follow the changes in height of the first surface 82a and the second surface 82b, respectively. Therefore, compared to a case where the friction stir welding tool 2 does not follow the changes in height of the first surface 82a and the second surface 82b (for example, compared to a case where the friction stir welding tool 2 is moved entirely horizontally), defects (more specifically, voids) are less likely to occur in the joint between the first workpiece 8 and the second workpiece 9.

[0034] In the friction stir welding method of the first embodiment, the position of the friction stir welding tool 2 is controlled so as the probe 21 moves in the first direction DR1 across the second region RG2 and the third region RG3, respectively, that fluctuations in the axial load received by the friction stir welding tool 2 from the first workpiece 8 and the second workpiece 9 are suppressed. Therefore, the probe 21, which is moving in the first direction DR1 while also moving in the second direction DR2 or the third direction DR3, is prevented from being pressed against the first workpiece 8 and the second workpiece 9 with insufficient or excessive force. In this way, the generation of voids due to insufficient pressing force, or the generation of large burrs due to excessive pressing force, is suppressed.

[0035] (Optional additional configuration) Next, with reference to Figures 1 to 34, the friction stir welding method, the method for manufacturing automobile parts, and optional additional configurations that can be adopted in the machine tool 1A in the first embodiment will be described.

[0036] (Second direction DR2, and third direction DR3) In the examples shown in Figures 5 to 9, during the joining process (fourth step ST4), the second direction DR2 (in other words, the depth direction of the recess 81) coincides with the downward direction (more specifically, the vertically downward direction). The third direction DR3 coincides with the upward direction (more specifically, the vertically upward direction).

[0037] Alternatively, as illustrated in Figure 39, each of the second direction DR2 and the third direction DR3 may be parallel to the horizontal plane. Further alternatively, each of the second direction DR2 and the third direction DR3 may be inclined with respect to the vertical plane and the horizontal plane, respectively.

[0038] (Work 8 of the first work, and Work 9 of the second work) In the examples shown in Figures 1 and 2, the first workpiece 8 is a block 8a. In the example shown in Figure 3, the second workpiece 9 is a plate 9a. The thickness of the plate 9a may be, for example, 10 mm or less, or 5 mm or less. The shapes of the first workpiece 8 and the second workpiece 9 may be any shape, as long as they can be joined by overlapping using the friction stir welding tool 2. In other words, the first workpiece 8 is not limited to a block 8a, and the second workpiece 9 is not limited to a plate 9a. For example, the first workpiece 8 may be a case body or a frame.

[0039] As illustrated in Figure 4, after the overlapping step (third step ST3) and before the joining step (fourth step ST4), in the state where the first workpiece 8 and the second workpiece 9 are overlapped, the upper surface of the portion 91 of the second workpiece 9 facing the recess 81 of the first workpiece 8 may be a flat surface 91u. Furthermore, as illustrated in Figures 5 to 10, the step of friction stir welding the first workpiece 8 and the second workpiece 9 may include making the flat surface 91u a concave surface 91v (see Figure 10).

[0040] In the examples shown in Figures 5 to 10, the upper surface 8u of the first workpiece 8 and the lower surface 9s of the second workpiece 9 are friction stir welded. Alternatively, the upper surface 8u of the first workpiece 8 and the lower surface of the outer edge of the second workpiece 9 may be friction stir welded.

[0041] The joined article D is manufactured by friction stir welding the first workpiece 8 and the second workpiece 9. Therefore, the term "friction stir welding method" in this specification can be read as "method for manufacturing a joined article."

[0042] (Manufacturing methods for automotive parts) The article formed by friction stir welding the first workpiece 8 and the second workpiece 9 may be an automobile part (for example, an electric vehicle part). In this case, the terms “friction stir welding method,” “first workpiece,” and “second workpiece” in this specification shall be read as “manufacturing method for automobile parts,” “first part,” and “second part,” respectively.

[0043] As illustrated in Figure 12, the first workpiece 8 may be a case body 8b for housing a battery (more specifically, a frame for housing a battery). The second workpiece 9 may be a plate 9b (for example, a bottom plate or a top plate) that covers the opening OP of the case body 8b. The joined article D manufactured by performing the first to fourth steps ST4 described above may be a battery case D2 (see Figure 13) in which the case body 8b and the plate 9b are joined. The battery housed in the battery case D2 may be a lithium-ion battery or another type of battery. The battery case D2 may be a case with a battery already housed in it, or a case before the battery is housed in it.

[0044] Alternatively, as illustrated in Figure 14, the first workpiece 8 may be a case body 8c that houses an inverter (in other words, a DC / AC converter). The second workpiece 9 may be a plate 9c that covers the opening OP of the case body 8c. The joined article D manufactured by performing the first to fourth steps ST4 described above may be an inverter case D3 (see Figure 15) in which the case body 8c and the plate 9c are joined. The inverter case D3 may be a case with the inverter already housed inside, or a case before the inverter is housed inside.

[0045] Alternatively, as illustrated in Figure 16, the first workpiece 8 may be a case body 8d that houses the motor. The second workpiece 9 may be a plate 9d (e.g., an end plate) that covers the opening of the case body 8d. The joined article D manufactured by performing the first to fourth steps ST4 described above may be a motor case D4 in which the case body 8d and the plate 9d are joined. The inverter case D3 (or motor case D4) may be a case that houses both the inverter and the motor.

[0046] (Control of the position of friction stir welding tool 2) In the examples shown in Figures 6 and 8, the position of the friction stir welding tool 2 (more specifically, the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21) is controlled so as the probe 21 moves in the first direction DR1 across the second region RG2 and the third region RG3, respectively, that fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 are suppressed.

[0047] In the examples shown in Figures 6 and 8, the position of the friction stir welding tool 2 (more specifically, the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21) may be controlled so that the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 remains constant as the probe 21 moves in the first direction DR1 across the second region RG2 and the third region RG3, respectively.

[0048] In this specification, one aspect of maintaining a constant axial load F includes maintaining the axial load F at a predetermined value. In this case, if the axial load F falls below the predetermined value, the position of the friction stir welding tool 2 is corrected to a second direction DR2 in order to maintain the axial load F at the predetermined value. Furthermore, if the axial load F exceeds the predetermined value, the position of the friction stir welding tool 2 is corrected to a third direction DR3 in order to maintain the axial load F at the predetermined value.

[0049] Furthermore, in this specification, one aspect of maintaining a constant axial load F includes maintaining the axial load F within a predetermined range. In this case, if the axial load F falls below the lower limit of the predetermined range, the position of the friction stir welding tool 2 is corrected to a second direction DR2 in order to maintain the axial load F within the predetermined range. Also, if the axial load F exceeds the upper limit of the predetermined range, the position of the friction stir welding tool 2 is corrected to a third direction DR3 in order to maintain the axial load F within the predetermined range.

[0050] The above-described control (or position correction) may be performed by a control device correcting the position of the friction stir welding tool 2 based on signal data from a sensor that directly or indirectly measures the axial load F.

[0051] Alternatively, if the axial load F is a function of a specific control command value or a specific physical quantity, the above-described control (or position correction) may be performed by the control device correcting the position of the friction stir welding tool 2 based on the specific control command value or a specific physical quantity. For example, the axial load F is a function of the load on the motor that rotates the probe 21 around the rotation axis AX. Therefore, the above-described control (or position correction) may be performed by the control device correcting the position of the friction stir welding tool 2 based on the load on the motor that rotates the probe 21 around the rotation axis AX. The load on the motor that rotates the probe 21 around the rotation axis AX may be calculated or determined based on, for example, the drive current command value or the drive current value of the motor.

[0052] Furthermore, the maximum amount of correction (in other words, the correction limit) when the position of the friction stir welding tool 2 is corrected in the second direction DR2 in response to the axial load F received by the friction stir welding tool 2 from the first workpiece 8 and the second workpiece 9 may be, for example, 5 mm or less, 3 mm or less, or 2 mm or less. In other words, even when the position of the friction stir welding tool 2 is corrected in the second direction DR2 in response to the axial load F, the system may be configured so that the position of the friction stir welding tool 2 is not corrected by more than 5 mm in the second direction DR2.

[0053] By preventing the position of the friction stir welding tool 2 from being corrected by more than 5 mm in the second direction DR2, malfunction of the machine tool 1 is prevented in the event of defects in the shape of the recess 81, etc. In this case, even if the depth of the recess 81 exceeds 5 mm, the position of the friction stir welding tool 2 will not be corrected by more than 5 mm in the second direction DR2. In this embodiment, the maximum value of the correction amount (in other words, the correction limit value) is not limited to a value of 5 mm or less. Also, in this embodiment, a correction limit value may not be set.

[0054] The depth L1 of the recess 81 of the first workpiece 8 (see Figure 1) is, for example, 0.1 mm or more and 3 mm or less.

[0055] (First example of controlling the position of friction stir welding tool 2) A first example of controlling the position of the friction stir welding tool 2 will be described. In the example shown in Figure 17, the machine tool 1A has a sensor 12 and a control device 7. The sensor 12 detects the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9. The control device 7 receives signal data S1 indicating the axial load F from the sensor 12 and corrects the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 based on the signal data S1. The signal data S1 may be raw signal data or data obtained by processing the raw signal data.

[0056] In the example shown in Figure 6, the axial load F detected by the sensor 12 decreases as the probe 21 moves in the first direction DR1 across the second region RG2. The control device 7 corrects the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 to the second direction DR2 in response to the decrease in axial load F as the probe 21 moves across the second region RG2. In this way, fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 are suppressed.

[0057] In the example shown in Figure 8, the axial load F detected by the sensor 12 increases as the probe 21 moves in the first direction DR1 across the third region RG3. The control device 7 corrects the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 to the third direction DR3 in response to the increase in axial load F as the probe 21 moves across the third region RG3. In this way, fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 are suppressed.

[0058] In the examples shown in Figures 6 and 17, as the probe 21 moves across the second region RG2 in the first direction DR1, the control device 7 may, based on the signal data S1 received from the sensor 12, correct the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 to the second direction DR2 so that the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 remains constant.

[0059] In the examples shown in Figures 8 and 17, as the probe 21 moves across the third region RG3 in the first direction DR1, the control device 7 may, based on the signal data S1 received from the sensor 12, correct the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 to the third direction DR3 so that the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 remains constant.

[0060] In the examples shown in Figures 5, 7, 9, and 17, as the probe 21 moves in the first direction DR1 across the first region RG1, the fourth region RG4, and the fifth region RG5, the control device 7 may correct the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 based on the signal data S1 received from the sensor 12, so as to suppress the fluctuation of the axial load F (more specifically, so as to maintain the axial load F at a constant level).

[0061] In the example shown in Figure 17, a sensor 12a for detecting the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 is located in a probe holder HD that holds the probe 21 of the friction stir welding tool 2.

[0062] Alternatively, as illustrated in Figure 18, a sensor 12b for detecting the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 may be located on the rotating body 42 (in other words, the tool spindle) to which the probe holder HD is attached.

[0063] Alternatively, a detector that detects the load acting on the drive system may be used as the sensor 12 described above. In the example shown in Figure 19, the machine tool 1A includes a moving device 5 (for example, a first drive device 51b that moves the machining head 4 in a direction parallel to the vertical) that moves the machining head 4 which has the rotating body 42 (in other words, the tool spindle) described above. The machine tool 1A is also capable of detecting the load acting on the moving device 5 (for example, the first drive device 51b that moves the machining head 4 in a direction parallel to the vertical). In this case, a detector that detects the load acting on the moving device 5 (for example, the first drive device 51b) may be used as the sensor 12c that detects the axial load F described above.

[0064] (Second example of controlling the position of friction stir welding tool 2) In the example shown in Figure 20, the machine tool 1A has a motor 44m that rotates the probe 21 around the rotation axis AX. In the example shown in Figure 20, the friction stir welding method (more specifically, the fourth step ST4 described above) includes the control device 7 obtaining the load applied to the motor 44m that rotates the probe 21 around the rotation axis AX.

[0065] The load on motor 44m may be obtained by acquiring data indicating the drive current command value of motor 44m or data S2 indicating the drive current value of motor 44m. For example, when motor 44m rotates probe 21 around rotation axis AX at a constant rotational speed, the control device 7 can calculate or determine the load on motor 44m based on data indicating the drive current command value of motor 44m (if the motor is an AC induction motor, this drive current command value is, for example, the q-axis current command value) or data S2 indicating the drive current value of motor 44m. The drive current command value of motor 44m itself, or the drive current value of motor 44m itself, may be used as the load on motor 44m. Alternatively, the load on motor 44m may be the time average of the drive current command value of motor 44m, the time average of the drive current of motor 44m, the standardized value of the drive current command value of motor 44m (in other words, a value expressed as a ratio to a reference value), or the standardized value of the drive current of motor 44m (in other words, a value expressed as a ratio to a reference value).

[0066] In the examples shown in Figures 6 and 20, the control device 7 corrects the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 to the second direction DR2 in response to the decrease in the load on the motor 44m as the probe 21 crosses the second region RG2. In this way, fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 are suppressed.

[0067] In the examples shown in Figures 8 and 20, the control device 7 corrects the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 to the third direction DR3 in response to the increase in the load on the motor 44m as the probe 21 crosses the third region RG3. In this way, fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 are suppressed.

[0068] In the examples shown in Figures 6 and 20, when the probe 21 moves across the second region RG2 in the first direction DR1, the control device 7 may correct the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 to the second direction DR2 so that the drive current command value or the drive current value of the motor 44m acquired by the control device 7 is kept constant. By keeping the drive current command value or the drive current value of the motor 44m constant, the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 is kept constant.

[0069] In the examples shown in Figures 8 and 20, when the probe 21 moves in the first direction DR1 across the third region RG3, the control device 7 may correct the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 to the third direction DR3 so that the drive current command value or the drive current value of the motor 44m acquired by the control device 7 is kept constant. By keeping the drive current command value or the drive current value of the motor 44m constant, the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 is kept constant.

[0070] In the examples shown in Figures 5, 7, 9, and 20, the control device 7 may correct the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 so that the drive current command value or the drive current value of the motor 44m acquired by the control device 7 is kept constant when the probe 21 moves in the first direction DR1 across the first region RG1, the fourth region RG4, and the fifth region RG5, respectively.

[0071] (3rd page 82c) In the example shown in Figure 4, the multiple surfaces 82 defining the recess 81 of the first workpiece 8 include a first surface 82a and a second surface 82b, as well as a third surface 82c positioned between the first surface 82a and the second surface 82b. In the example shown in Figure 1, the third surface 82c is a surface with a constant height. In this specification, "constant" height includes substantially constant height. In other words, even if there is some variation in height due to the surface roughness of the first workpiece 8 or the machining accuracy of the recess 81, the height is considered "constant".

[0072] In the example shown in Figure 4, the overlapping step (third step ST3) includes forming a fourth region RG4 located between the second region RG2 and the third region RG3. In the example shown in Figure 4, in the fourth region RG4, the gap G4 between the third surface 82c and the second workpiece 9 is substantially constant along the first direction DR1.

[0073] In the examples shown in Figures 6 to 8, the joining step (fourth step ST4) includes moving the probe 21 so that it traverses the second region RG2, the fourth region RG4, and the third region RG3 in that order.

[0074] In the examples shown in Figures 6 to 8, the position of the friction stir welding tool 2 is controlled so that the change in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 is suppressed as the probe 21 moves in the first direction DR1 across the second region RG2, the fourth region RG4, and the third region RG3, respectively. If the height of the third surface 82c is constant along the first direction DR1, the position of the friction stir welding tool 2 in the direction along the rotation axis AX of the probe 21 is maintained at approximately a constant level as the probe 21 moves in the first direction DR1 across the fourth region RG4.

[0075] (Process for preparing Work 8) In the example shown in Figure 23, the step of preparing the first workpiece 8 (first step ST1) includes forming the first surface 82a by cutting the first step portion 84a (see Figure 22) between the first part 83 of the first workpiece 8 and the recess 85 of the first workpiece 8. In the example shown in Figure 24, the step of preparing the first workpiece 8 (first step ST1) includes forming the second surface 82b by cutting the second step portion 84b (see Figure 23) between the second part 86 of the first workpiece 8 and the recess 85 of the first workpiece 8.

[0076] As illustrated in Figure 25, consider a case where a first workpiece 8 and a second workpiece 9 are friction stir welded together with a first step portion 84a and a second step portion 84b present. In this case, voids are likely to form in the joint between the first workpiece 8 and the second workpiece 9 due to the presence of the step portions (84a, 84b). In the example shown in Figure 25, reducing the movement speed of the probe 21 in the first direction DR1 when the probe 21 crosses the recess 85 will suppress the formation of these voids. However, reducing the movement speed of the probe 21 will increase the processing time. Furthermore, reducing the movement speed of the probe 21 may cause the formation of large burrs.

[0077] In contrast, as illustrated in Figures 23 and 24, when the first stepped portion 84a and the second stepped portion 84b are cut, and then friction stir welding is performed as illustrated in Figures 5 to 9, the occurrence of voids in the joint portion between the first workpiece 8 and the second workpiece 9 can be prevented or suppressed without reducing the movement speed of the probe 21 in the first direction DR1.

[0078] In the example shown in Figure 22, the recess 85 having the first stepped portion 84a and the second stepped portion 84b is formed by cutting. However, the recess 85 may be formed by methods other than cutting. For example, the recess 85 may be formed by striking a part of the casting with a hammer or the like. Alternatively, the recess 85 may be formed by welding the notched portion of the first piece 88a of the first workpiece 8 to the notched portion of the second piece 88b of the first workpiece 8.

[0079] As illustrated in Figure 21, the first workpiece 8 may include a weld 87 (more specifically, the first workpiece 8 may be a workpiece in which a first piece 88a and a second piece 88b are welded at the weld 87). Also, as illustrated in Figure 22, the step of preparing the first workpiece 8 (first step ST1) may include forming a recess 85 by cutting the weld 87 and the portion adjacent to the weld 87.

[0080] As illustrated in Figure 26, consider a case where the first workpiece 8 and the second workpiece 9 are friction stir-welded with the weld portion 87 protruding from the surface of the first workpiece 8. In this case, voids are likely to form in the joint between the first workpiece 8 and the second workpiece 9 due to the presence of the protruding weld portion 87.

[0081] In contrast, when the welded portion 87 is cut as illustrated in Figure 22, and the first stepped portion 84a and the second stepped portion 84b are cut as illustrated in Figures 23 and 24, and then friction stir welding is performed as illustrated in Figures 5 to 9, the occurrence of voids in the joint portion between the first workpiece 8 and the second workpiece 9 can be prevented or suppressed without reducing the movement speed of the probe 21 in the first direction DR1.

[0082] In the examples shown in Figures 22 to 24, the welded portion 87 is cut, and then the first stepped portion 84a and the second stepped portion 84b are cut, thereby forming the first surface 82a and the second surface 82b described above.

[0083] As illustrated in Figures 22 to 24, or Figures 27 and 28, the first surface 82a and the second surface 82b described above may be formed by cutting the welded portion 87 and the portion adjacent to the welded portion 87. In the example shown in Figures 22 to 24, the first stepped portion 84a and the second stepped portion 84b are formed by cutting the welded portion 87 and the portion adjacent to the welded portion 87, and then the first surface 82a and the second surface 82b described above are formed by cutting the first stepped portion 84a and the second stepped portion 84b. Alternatively, as illustrated in Figures 27 and 28, the first surface 82a and the second surface 82b described above may be formed directly (in other words, without forming the stepped portion) by cutting the welded portion 87 and the portion adjacent to the welded portion 87.

[0084] (Recess 81) In the example shown in Figure 29, the recess 81 of the first workpiece 8 extends in the fourth direction DR4, which is perpendicular to the second direction DR2. The recess 81 may also be a linear recess extending in the fourth direction DR4. In the example shown in Figure 29, the weld 87 also extends in the fourth direction DR4. The weld 87 may also be a linear weld extending in the fourth direction DR4.

[0085] The fourth direction DR4 is defined as the opposite direction to the fifth direction DR5. In the example shown in Figure 29, the end 81e of the recess 81 on the fourth direction DR4 side is open. Also, the end 81f of the recess 81 on the fifth direction DR5 side is open.

[0086] In the overlapping process (third step ST3), the second workpiece 9 is placed on top of the first workpiece 8 such that the top surface of the first workpiece 8 and the bottom surface of the second workpiece 9 are in contact.

[0087] In the example shown in Figure 30, when the second workpiece 9 is placed on top of the first workpiece 8, the end 81e of the recess 81 on the fourth direction DR4 side is open. Alternatively, or additionally, when the second workpiece 9 is placed on top of the first workpiece 8, the end 81f of the recess 81 on the fifth direction DR5 side (see Figure 29) may also be open.

[0088] When the second workpiece 9 is placed on top of the first workpiece 8, if at least one of the end 81e of the recess 81 on the fourth direction DR4 side and the end 81f of the recess 81 on the fifth direction DR5 side is open, the open end (81e; 81f) functions as an air vent.

[0089] More specifically, as the probe 21 moves across the recess 81 in the first direction DR1, the material of the second workpiece 9 enters the space within the recess 81. At this time, in response to the entry of the material, at least a portion of the air present in the space within the recess 81 is discharged to the outside of the recess 81 through the open ends (81e; 81f). In this way, the first workpiece 8 and the second workpiece 9 are friction stir-welded while preventing the formation of voids at the joint between them.

[0090] (Probe 21's movement path) As shown by the dashed arrow in Figure 30, in the joining process (fourth step ST4), when the probe 21 crosses the recess 81, the probe 21 may move along the linear path PA1. In other words, the first direction DR1 described above may be the direction along the linear path PA1. The first direction DR1 may be perpendicular to the extending direction of the recess 81 (in other words, the fourth direction DR4), or it may be inclined with respect to the extending direction of the recess 81.

[0091] Alternatively, as shown by the dashed arrow in Figure 31, in the joining process (fourth step ST4), when the probe 21 crosses the recess 81, the probe 21 may move along the curved path PA2. In other words, the first direction DR1 described above may be the direction along the curved path PA2.

[0092] As illustrated in Figure 16, let's assume that the second workpiece 9 is disc-shaped, and the outer edges of the first workpiece 8 and the second workpiece 9 are friction stir-welded. In this case, the probe 21 may move along a circular path or an arc-shaped path PA3. In other words, the first direction DR1 described above may be a direction along a circular path or an arc-shaped path PA3.

[0093] (Speed ​​of movement of probe 21) The speed at which the probe 21 (see Figure 34) moves along the first direction DR1 when crossing at least a portion of the first region RG1 and at least a portion of the fifth region RG5 may be the same as the speed at which the probe 21 moves along the first direction DR1 when crossing the second region RG2 and the third region RG3, respectively. Also, the speed at which the probe 21 moves along the first direction DR1 when crossing the second region RG2 and the third region RG3, respectively, may be the same as the speed at which the probe 21 moves along the first direction DR1 when crossing the fourth region RG4. When the speed at which the probe 21 moves is constant, the generation of large burrs on the surface of the second workpiece 9 is prevented or suppressed.

[0094] (Machine tool 1A) As illustrated in Figures 17 to 20, the machine tool 1A in the first embodiment comprises a workpiece support member 3, a machining head 4, a rotary drive device 44, a moving device 5, and a control device 7.

[0095] The workpiece support member 3 supports the first workpiece 8 and the second workpiece 9. The workpiece support member 3 includes, for example, a table 31 on which the first workpiece 8 and the second workpiece 9 are fixed. In the example shown in Figures 17 to 20, the table 31 directly supports the first workpiece 8. The table 31 also supports the second workpiece 9 through the first workpiece 8.

[0096] The machining head 4 rotatably supports the probe 21 of the friction stir welding tool 2 around the rotation axis AX. The machining head 4 has a rotating body 42 and a frame 43 that rotatably supports the rotating body 42. In the examples shown in Figures 17 to 20, the rotating body 42 supports the probe 21 via a probe holder HD.

[0097] The rotary drive device 44 rotates the probe 21 around the rotation axis AX by rotating the rotating body 42 around the first axis AX1. In the examples shown in Figures 17 to 20, the first axis AX1, which is the rotation axis of the rotating body 42, and the rotation axis AX of the probe 21 are coaxial.

[0098] The moving device 5 moves the processing head 4 relative to the workpiece support member 3. The control device 7 controls the rotary drive device 44 and the moving device 5.

[0099] The control device 7 is capable of executing friction stir welding mode M1. Friction stir welding mode M1 is a mode in which the first workpiece 8 and the second workpiece 9 are friction stir-welded together while the second workpiece 9 is superimposed on the first workpiece 8, which has a recess 81 defined by a plurality of surfaces 82 including a first surface 82a whose height gradually decreases in the first direction DR1 and a second surface 82b whose height gradually increases in the first direction DR1.

[0100] As illustrated in Figure 5, the friction stir welding mode M1 includes moving the friction stir welding tool 2 in a first direction DR1 such that the probe 21 crosses at least a portion of the first region RG1 where the first workpiece 8 and the second workpiece 9 are in contact.

[0101] As illustrated in Figure 6, the friction stir welding mode M1 includes moving the friction stir welding tool 2 in the first direction DR1 so as to follow the change in height of the first surface 82a, while moving the friction stir welding tool 2 in the second direction DR2 so as to follow the change in height of the first surface 82a, while moving the friction stir welding tool 2 in the second direction DR2 so as to follow the change in height of the first surface 82a, while moving the probe 21 across the second region RG2 in the first direction DR1.

[0102] As illustrated in Figure 8, the friction stir welding mode M1 includes moving the friction stir welding tool 2 in the first direction DR1 so as to follow the change in height of the second surface 82b, while moving the friction stir welding tool 2 in the third direction DR3 so as to follow the change in height of the second surface 82b, while moving the friction stir welding tool 2 in the third direction DR3 so as to follow the change in height of the second surface 82b.

[0103] Additionally, as illustrated in Figure 7, the friction stir welding mode M1 may include moving the friction stir welding tool 2 in a first direction DR1 such that the probe 21 traverses a fourth region RG4 between a second region RG2 and a third region RG3.

[0104] Additionally, as illustrated in Figure 9, the friction stir welding mode M1 may include moving the friction stir welding tool 2 in the first direction DR1 such that the probe 21 crosses at least a portion of the fifth region RG5 located on the first direction DR1 side of the third region RG3.

[0105] As the probe 21 moves in the first direction DR1 across the second region RG2 and the third region RG3, the control device 7 controls the position of the friction stir welding tool 2 (more specifically, the position of the friction stir welding tool 2 in the direction along the rotation axis AX) so as to suppress fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9. The control device 7 may also control the position of the friction stir welding tool 2 (more specifically, the position of the friction stir welding tool 2 in the direction along the rotation axis AX) so as to maintain a constant axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9.

[0106] Additionally, as the probe 21 moves in the first direction DR1 across each of the first region RG1, the fourth region RG4, and the fifth region RG5, the control device 7 may control the position of the friction stir welding tool 2 (more specifically, the position of the friction stir welding tool 2 in the direction along the rotation axis AX) so as to suppress fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 (more specifically, so as to maintain a constant axial load F).

[0107] In the machine tool 1A of the first embodiment, the control device 7 is capable of executing friction stir welding mode M1. When friction stir welding mode M1 is executed, the friction stir welding tool 2 moves in a first direction DR1 while simultaneously moving in a second direction DR2 or a third direction DR3 to follow the changes in height of the first surface 82a and the second surface 82b, respectively. Therefore, compared to a case where the friction stir welding tool 2 is not made to follow the changes in height of the first surface 82a and the second surface 82b (for example, compared to a case where the friction stir welding tool 2 is moved entirely horizontally), defects (more specifically, voids) are less likely to occur in the joint between the first workpiece 8 and the second workpiece 9.

[0108] In the machine tool 1A of the first embodiment, the control device 7 controls the position of the friction stir welding tool 2 so as the probe 21 moves in the first direction DR1 across the second region RG2 and the third region RG3, the fluctuation of the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 is suppressed. Thus, the probe 21, which is moving in the first direction DR1 while also moving in the second direction DR2 or the third direction DR3, is prevented from being pressed against the first workpiece 8 and the second workpiece 9 with insufficient or excessive force. In this way, the generation of voids due to insufficient pressing force, or the generation of large burrs due to excessive pressing force, is suppressed.

[0109] (Optional additional configuration) Next, with reference to Figures 1 to 34, we will describe optional additional configurations that can be adopted in the machine tool 1A (or the friction stir welding method in the first embodiment) in the first embodiment.

[0110] (Friction stir welding tool 2) In the example shown in Figure 5, the friction stir welding tool 2 includes a probe 21 and a shoulder 23. The probe 21 is inserted into the second workpiece 9 during the welding process (the fourth step ST4 described above). During the welding process (the fourth step ST4 described above), the tip of the probe 21 may reach the first workpiece 8.

[0111] The shoulder 23 presses against the third-direction DR3 side (i.e., the top surface) of the second workpiece 9. In the example shown in Figure 5, the shoulder 23 is a rotating shoulder that rotates together with the probe 21 around the rotation axis AX of the probe 21. The shoulder 23 (more specifically, the rotating shoulder) and the probe 21 may be made of a single molded component. Alternatively, as illustrated in Figure 32, the shoulder 23 may be a fixed shoulder that does not rotate with the probe 21. In this case, the probe 21 rotates relative to the fixed shoulder around the rotation axis AX.

[0112] In the examples shown in Figures 6, 8, and 32, the shoulder 23 is configured to move together with the probe 21 in the second direction DR2 (or third direction DR3) as the probe 21 moves in the second direction DR2 (or third direction DR3). More specifically, during the execution of the bonding process (fourth step ST4), the probe 21 is substantially immobile relative to the shoulder 23 in a direction parallel to the second direction DR2.

[0113] In this case, as illustrated in Figure 6, when the probe 21 moves in the first direction DR1 across the second region RG2, both the probe 21 and the shoulder 23 move in the second direction DR2 to follow the change in height of the first surface 82a. Also, as illustrated in Figure 8, when the probe 21 moves in the first direction DR1 across the third region RG3, both the probe 21 and the shoulder 23 move in the third direction DR3 to follow the change in height of the second surface 82b.

[0114] (Probe holder HD) The probe holder HD holds the probe 21 of the friction stir welding tool 2. In the examples shown in Figures 17 to 20, the rotating body 42 of the machining head 4 supports the probe 21 via the probe holder HD. The rotating body 42 of the machining head 4 may support both the probe 21 and the shoulder 23 via the probe holder HD. Alternatively, as illustrated in Figure 32, the rotating body 42 of the machining head 4 may support the probe 21 via the probe holder HD, and the frame 43 of the machining head 4 may support the shoulder 23.

[0115] As illustrated in Figure 17, the probe holder HD may have a sensor 12a for detecting the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9.

[0116] In the example shown in Figure 17, the shoulder 23 is a rotating shoulder that rotates with the probe 21, and the axial load F detected by the sensor 12a is the sum of the load in the third direction DR3 that the probe 21 receives from the first workpiece 8 and the second workpiece 9, and the load in the third direction DR3 that the shoulder 23 receives from the second workpiece 9. If the shoulder 23 is a fixed shoulder that does not rotate with the probe 21, the axial load F detected by the sensor 12a may be the load in the third direction DR3 that the probe 21 receives from the first workpiece 8 and the second workpiece 9.

[0117] Sensor 12a transmits signal data S1 indicating the axial load F to the control device 7, either directly or indirectly via an arbitrary relay. This transmission may be wireless or wired. In the example shown in Figure 17, the control device 7 obtains signal data S1 indicating the axial load F from sensor 12a via data receiver 13 and communication interface 14.

[0118] (Processing head 4) As illustrated in Figure 18, the machining head 4 may have a sensor 12b that detects the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9.

[0119] In the example shown in Figure 18, the shoulder 23 is a rotating shoulder that rotates with the probe 21, and the axial load F detected by the sensor 12b is the sum of the load in the third direction DR3 that the probe 21 receives from the first workpiece 8 and the second workpiece 9, and the load in the third direction DR3 that the shoulder 23 receives from the second workpiece 9. If the shoulder 23 is a fixed shoulder that does not rotate with the probe 21, the axial load F detected by the sensor 12b may be the sum of the above loads, or it may be the load in the third direction DR3 that the probe 21 receives from the first workpiece 8 and the second workpiece 9.

[0120] Sensor 12b transmits signal data S1 indicating the axial load F to the control device 7, either directly or indirectly via an arbitrary relay. This transmission may be wireless or wired. In the example shown in Figure 18, the control device 7 obtains signal data S1 indicating the axial load F from sensor 12b via data receiver 13 and communication interface 14.

[0121] (Mobile device 5) The moving device 5 moves the machining head 4 relative to the workpiece support member 3. The moving device 5 includes a first moving device 51 for moving the machining head 4. Alternatively, or additionally, the moving device 5 may have a second moving device 58 for moving the workpiece support member 3.

[0122] The first moving device 51 includes a first moving body 51a that supports the machining head 4, and a first drive device 51b that moves the machining head 4 relative to the first moving body 51a. In the example shown in Figures 17 to 20 and 32, the first drive device 51b moves the machining head 4 in a direction parallel to the second direction DR2 (for example, the vertical direction). The first drive device 51b may include a Z-axis motor.

[0123] Additionally, the first moving device 51 may include a support 52a that supports the first moving body 51a, and a second drive device 52b that moves the first moving body 51a relative to the support 52a in a direction perpendicular to the second direction DR2. The second drive device 52b may be a device capable of moving the first moving body 51a two-dimensionally in a direction parallel to the horizontal plane (for example, the second drive device 52b may include an X-axis motor and a Y-axis motor).

[0124] As illustrated in Figure 19 or Figure 32, the first drive unit 51b may have a sensor 12c for detecting the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9.

[0125] In the example shown in Figure 19 or Figure 32, the axial load F detected by the sensor 12c is the sum of the loads in the third direction DR3 that the probe 21 receives from the first workpiece 8 and the second workpiece 9, and the loads in the third direction DR3 that the shoulder 23 receives from the second workpiece 9.

[0126] The sensor 12c transmits signal data S1 indicating the axial load F to the control device 7, either directly or indirectly via an arbitrary relay. This transmission may be wireless or wired. In the example shown in Figure 19 or Figure 32, the control device 7 obtains the signal data S1 indicating the axial load F from the sensor 12c via the data receiver 13 and the communication interface 14.

[0127] The first moving device 51 may be a device that moves the machining head 4 in three dimensions. For example, the first moving device 51 may move the machining head 4 in the direction along the X axis, in the direction along the Y axis, and in the direction along the Z axis. In the examples shown in Figures 17 to 20 and 32, the Z axis is an axis parallel to the vertical direction. Also, the Z axis is an axis parallel to the second direction DR2.

[0128] In the examples shown in Figures 17 to 20 and Figure 32, the second moving device 58 includes a third drive device 58b (for example, a table drive device) that moves the work support member 3, such as a table 31, relative to the base 30. In the examples shown in Figures 17 to 20 and Figure 32, the third drive device 58b moves the work support member 3 relative to the base 30 in a direction parallel to the horizontal plane (in other words, a direction parallel to the XY plane).

[0129] (Rotating drive device 44) The rotary drive unit 44 rotates the probe 21 around the rotation axis AX. The rotary drive unit 44 may rotate both the probe 21 and the shoulder 23 around the rotation axis AX. Alternatively, the rotary drive unit 44 may rotate the probe 21 around the rotation axis AX independently of the shoulder 23. The rotary drive unit 44 includes, for example, a motor 44m. The motor 44m may be an AC induction motor, an AC synchronous motor, or a DC motor.

[0130] As illustrated in Figure 20, the rotary drive unit 44 may transmit data S2 indicating the drive current value of the motor 44m to the control device 7 directly or indirectly via an arbitrary relay. This transmission may be wireless or wired. In the example shown in Figure 20, the control device 7 obtains data S2 indicating the drive current value of the motor 44m from the rotary drive unit 44 via the data receiver 13 and the communication interface 14. Alternatively or additionally, the first control unit 71a controlling the mobile device 5 may obtain data indicating the drive current command value of the motor 44m from the second control unit 71b controlling the motor 44m.

[0131] (Control device 7) The control device 7 controls the rotary drive device 44 and the moving device 5. In the example shown in Figures 17 to 20 and 32, the control device 7 has a first control unit 71a that controls the moving device 5 and a second control unit 71b that controls the rotary drive device 44 (more specifically, the motor 44m).

[0132] When the rotary drive device 44 receives the first rotation command R1 from the control device 7 (more specifically, the second control unit 71b), the rotary drive device 44 rotates the probe 21 around the rotation axis AX.

[0133] When the moving device 5 receives a movement command C from the control device 7 (more specifically, the first control unit 71a), the moving device 5 moves the machining head 4 and / or the workpiece support member 3. For example, when the second drive device 52b receives a first movement command C1 from the control device 7 (more specifically, the first control unit 71a), it moves the machining head 4 in a direction perpendicular to the second direction DR2 (more specifically, a direction parallel to the horizontal plane). Also, when the first drive device 51b receives a second movement command C2 from the control device 7 (more specifically, the first control unit 71a), it moves the machining head 4 in a direction parallel to the second direction DR2 (more specifically, a direction parallel to the vertical direction). Also, when the third drive device 58b receives a movement command C4 from the control device 7 (more specifically, the first control unit 71a), it moves the workpiece support member 3 in a direction parallel to the horizontal plane.

[0134] An example of the control device 7 will be described in more detail with reference to Figure 33. In the example shown in Figure 33, the control device 7 comprises a hardware processor 70 (hereinafter simply referred to as "processor 70"), a memory 72, a communication circuit 74, and an input device 76 (for example, a touch panel display 762). The processor 70, the memory 72, the communication circuit 74, and the input device 76 are connected to each other via a bus 78.

[0135] The memory 72 is a storage medium readable by the processor 70 of the control device 7. The memory 72 may be, for example, a non-volatile or volatile semiconductor memory such as RAM, ROM, or flash memory, or it may be a magnetic disk or other type of memory.

[0136] Memory 72 stores data and program 722. In the example shown in Figure 33, the program 722 stored in memory 72 includes a first program 722a for friction stir welding.

[0137] The data required for friction stir welding performed using the friction stir welding tool 2 (for example, first path data 726a that defines the first movement path that the probe 21 should move along) may be input to the control device 7 via the input device 76, or it may be input to the control device 7 from another computer via the communication circuit 74. The data required for friction stir welding is stored in the memory 72.

[0138] The input device 76 is not limited to a touch panel display 762. For example, the control device 7 may include an input device 76 such as a button, switch, lever, pointing device, or keyboard, and a display that shows data or other information input to the input device 76. Furthermore, multiple computers may cooperate to function as the control device 7. Also, the memory 72 may be distributed across multiple locations. For example, part of the memory 72 may be included in cloud storage.

[0139] The processor 70 of the control device 7 executes the program 722 stored in the memory 72, thereby generating a control command. The communication circuit 74 then transmits this control command to the controlled equipment (more specifically, the rotary drive device 44, the moving device 5, etc.). In this way, by the processor 70 executing the program 722, the control device 7 can control the rotary drive device 44 and the moving device 5.

[0140] (Friction stir welding mode M1) As illustrated in Figure 34, the control device 7 is capable of performing a friction stir welding mode M1 in which the first workpiece 8 and the second workpiece 9 are friction stir welded together.

[0141] Friction stir welding mode M1 includes the control device 7 transmitting a first movement command C1 to the moving device 5 (more specifically, the second drive device 52b) so that the rotating probe 21 moves along a first movement path PA that crosses the recess 81 (see Figure 33). Friction stir welding mode M1 also includes the control device 7 transmitting a second movement command C2 to the moving device 5 (more specifically, the first drive device 51b) so that fluctuations in the axial load F are suppressed (more specifically, so that the axial load F is kept constant) as the probe 21 crosses the recess 81.

[0142] For example, the control device 7 executing the first program 722a generates a first rotation command R1 and generates the first movement command C1 based on the first path data 726a stored in the memory 72. The control device 7 also transmits the generated first rotation command R1 to the rotation drive device 44 and transmits the generated first movement command C1 to the movement device 5 (more specifically, the second drive device 52b). The rotation drive device 44, which receives the first rotation command R1, rotates the probe 21 around the rotation axis AX. The movement device 5 (more specifically, the second drive device 52b), which receives the first movement command C1, moves the rotating probe 21 along the first movement path PA that crosses the recess 81 (more specifically, the first movement path PA that completely crosses the recess 81). The first movement path PA that crosses the recess 81 may be a straight path or a curved path PA2 (see Figure 31).

[0143] Furthermore, the control device 7, which executes the first program 722a, generates a second movement command C2 in such a way that fluctuations in the axial load F described above are suppressed (more specifically, in such a way that the axial load F described above is kept constant).

[0144] For example, as the probe 21 moves along the first movement path PA, the control device 7 receives signal data indicating the axial load F from the sensor 12, or acquires data indicating the load of the motor 44m. The control device 7, which is executing the first program 722a, generates a second movement command C2 based on the signal data received from the sensor 12 or the data indicating the load of the motor 44m, so as to suppress fluctuations in the axial load F (more specifically, so as to maintain the axial load F at a constant level).

[0145] The control device 7 transmits the generated second movement command C2 to the movement device 5 (more specifically, the first drive device 51b). Upon receiving the second movement command C2, the movement device 5 (more specifically, the first drive device 51b) moves the rotating probe 21 in the second direction DR2 or the third direction DR3. In this way, when the probe 21 crosses the recess 81, the fluctuation of the axial load F described above is suppressed (more specifically, the axial load F described above is maintained at a constant level).

[0146] The control device 7 may transmit a first movement command C1 to the moving device 5 (more specifically, the second drive device 52b) so that the movement speed of the probe 21 moving along the first movement path PA is kept constant. By keeping the movement speed of the probe 21 constant, the generation of large burrs on the surface of the second workpiece 9 when the probe 21 crosses the recess 81 is prevented or suppressed.

[0147] (Second embodiment) Referring to Figures 1 to 37, the friction stir welding method, the method for manufacturing automobile parts, and the machine tool 1B in the second embodiment will be described. Figure 35 is a schematic diagram showing the machine tool 1B in the second embodiment. Figure 36 is a schematic perspective view showing a part of the machine tool 1B in the second embodiment. Figure 37 is a schematic diagram showing the machine tool 1B in the second embodiment.

[0148] In the second embodiment, the machine tool 1B differs from the first embodiment in that it is capable of cutting the first workpiece 8 such that the first surface 82a and the second surface 82b described above are formed. In other respects, the second embodiment is the same as the first embodiment.

[0149] The second embodiment will primarily describe the differences from the first embodiment. On the other hand, the second embodiment will omit repetitive explanations of matters already described in the first embodiment. Therefore, it goes without saying that even if not explicitly explained in the second embodiment, matters already described in the first embodiment can be applied to the second embodiment. Conversely, all matters described in the second embodiment are applicable to the first embodiment.

[0150] As illustrated in Figure 37, the machine tool 1B in the second embodiment includes a workpiece support member 3, a machining head 4, a rotary drive device 44, a moving device 5, and a control device 7. A friction stir welding tool 2 can be attached to the machining head 4.

[0151] Since the friction stir welding tool 2, workpiece support member 3, machining head 4, rotary drive device 44, moving device 5, and control device 7 have already been described in the first embodiment, a repeated explanation of these components will be omitted.

[0152] In the second embodiment, the machine tool 1B cuts the first workpiece 8 using the cutting tool 61 to form the first surface 82a and the second surface 82b described in the first embodiment (see Figures 23 and 24, or Figures 27 and 28).

[0153] The second embodiment provides the same effects as the first embodiment. Furthermore, in the second embodiment, the machine tool 1B is capable of performing both friction stir welding and cutting. Therefore, the process from forming the first surface 82a and the second surface 82b to joining the first workpiece 8 and the second workpiece 9 can be performed efficiently and in a short amount of time.

[0154] The friction stir welding method in the second embodiment comprises a first preparation step (first step ST1), a second preparation step (second step ST2), an overlapping step (third step ST3), and a joining step (fourth step ST4).

[0155] Since the first preparation step, the second preparation step, the overlapping step, and the joining step have already been described in the first embodiment, a repetitive explanation of these steps will be omitted.

[0156] (Optional additional configuration) Next, with reference to Figures 1 to 37, we will describe optional additional configurations that can be adopted in the second embodiment (or the first embodiment described above).

[0157] (Processing head 4) In the examples shown in Figures 35 and 37, the machining head 4 is selectively capable of holding a tool holder 62 (see Figure 35) for holding a cutting tool 61 and a probe holder HD (see Figure 37) for holding a probe 21. In other words, the machining head 4 functions as both part of a friction stir welding apparatus and part of a cutting apparatus.

[0158] Alternatively, the machine tool 1B may include a second machining head in addition to the machining head 4 that holds the probe holder HD, and a tool holder 62 that holds the cutting tool 61 may be attached to the second machining head.

[0159] (Probe holder HD) As illustrated in Figure 37, the probe holder HD may have a power receiving unit 18 that receives power from a power supply unit 48 supported by the machining head 4. Alternatively, the sensor 12a may be electrically connected to the power receiving unit 18. In this case, the sensor 12a operates using the power received from the power receiving unit 18.

[0160] (Tool changer 100) In the example shown in Figure 36, the machine tool 1B is equipped with a tool changer 100. The tool changer 100 can replace the tool holder 62 held by the machining head 4 (more specifically, the rotating body 42 of the machining head 4) with a probe holder HD that holds the probe 21. The tool changer 100 can also replace the probe holder HD held by the machining head 4 (more specifically, the rotating body 42 of the machining head 4) with a tool holder 62 that holds the cutting tool 61.

[0161] Figure 36 shows the state immediately after the tool changer 100 has replaced the tool holder 62 held on the machining head 4 with the probe holder HD that holds the probe 21.

[0162] In the example shown in Figure 36, the tool changer 100 includes a tool changer arm 101, an arm rotation device 104 for rotating the tool changer arm 101, and an arm moving device 106 for moving the tool changer arm 101 linearly. The arm rotation device 104 rotates the tool changer arm 101 around the second axis AX2. The arm moving device 106 moves the tool changer arm 101 in a direction parallel to the second axis AX2.

[0163] In the example shown in Figure 36, the tool change arm 101 is capable of simultaneously gripping the probe holder HD and the tool holder 62. In other words, the tool change arm 101 has a first gripping portion for gripping the probe holder HD and a second gripping portion for gripping the tool holder 62.

[0164] (Stocka 110) In the example shown in Figure 36, the machine tool 1B has a stocker 110 capable of storing a probe holder HD and a tool holder 62. The stocker 110 is capable of storing multiple holders, including the probe holder HD and the tool holder 62.

[0165] The stocker 110 may have a holder retrieval device 114 that moves the probe holder HD or tool holder 62 stored in the stocker 110 to a standby position P1 accessible by the tool changing device 100.

[0166] (Control device 7) The control device 7 controls the rotary drive device 44 and the moving device 5. Additionally, the control device 7 may control the tool changer 100 and / or the stocker 110.

[0167] In the example shown in Figure 35 or Figure 37, the control device 7 rotates the rotating body 42 holding the probe holder HD or tool holder 62 around the first axis AX1 by transmitting a rotation command R to the rotary drive device 44. More specifically, the control device 7 transmits a rotation command R to the rotary drive device 44, and the rotary drive device 44, upon receiving the rotation command R, rotates the rotating body 42 around the first axis AX1.

[0168] The control device 7 moves the machining head 4 relative to the workpiece support member 3 by transmitting a movement command C to the moving device 5. For example, the control device 7 moves the machining head 4 in a direction parallel to the second direction DR2 by transmitting a movement command C to the first drive device 51b. The control device 7 also moves the machining head 4 in a direction perpendicular to the second direction DR2 by transmitting a movement command C to the second drive device 52b. Furthermore, the control device 7 moves the workpiece support member 3 in a direction parallel to the horizontal plane by transmitting a movement command C to the third drive device 58b.

[0169] The control device 7 transmits a tool change command to the tool changer 100, thereby replacing the tool holder 62 (or probe holder HD) held on the machining head 4 with the probe holder HD (or tool holder 62). More specifically, the control device 7 transmits a first tool change command to the tool changer 100, and upon receiving the first tool change command, the tool changer 100 replaces the tool holder 62 held on the machining head 4 with the probe holder HD that holds the probe 21. The control device 7 also transmits a second tool change command to the tool changer 100, and upon receiving the second tool change command, the tool changer 100 replaces the probe holder HD held on the machining head 4 with the tool holder 62 that holds the cutting tool 61.

[0170] The control device 7 may move the probe holder HD or tool holder 62 stored in the stocker 110 to a standby position P1 accessible by the tool changer 100 by sending a retrieval command to the stocker 110. For example, the control device 7 sends a retrieval command to the stocker 110 and a first tool change command to the tool changer 100. Upon receiving the retrieval command, the stocker 110 moves the probe holder HD to the standby position P1. The tool changer 100, upon receiving the first tool change command, then exchanges the tool holder 62 held in the machining head 4 with the probe holder HD that has been moved to the standby position P1.

[0171] As illustrated in Figure 35, the control device 7 comprises a processor 70, a memory 72, a communication circuit 74, and an input device 76. The processor 70, memory 72, communication circuit 74, and input device 76 have already been described in the first embodiment, so a repetitive explanation of their configurations will be omitted.

[0172] Memory 72 stores data and programs 722. The programs 722 stored in memory 72 may include a first program 722a for friction stir welding, a second program 722b for cutting, and a third program 722c for tool changing.

[0173] The data necessary for the cutting process performed using the cutting tool 61 (for example, shape data of the first workpiece 8, second path data 726b defining the second movement path that the cutting tool 61 should move to form a recess 81 in the first workpiece 8, etc.) may be input to the control device 7 via the input device 76, or may be input to the control device 7 from another computer via the communication circuit 74. The data necessary for the cutting process is stored in the memory 72.

[0174] The data required for friction stir welding performed using the friction stir welding tool 2 (for example, first path data 726a that defines the first movement path that the probe 21 should move along) may be input to the control device 7 via the input device 76, or it may be input to the control device 7 from another computer via the communication circuit 74. The data required for friction stir welding is stored in the memory 72.

[0175] The processor 70 of the control device 7 executes a program 722 stored in the memory 72, thereby generating a control command. The communication circuit 74 then transmits this control command to the controlled equipment (more specifically, the rotary drive unit 44, the moving unit 5, the tool changer 100, the stocker 110, etc.). In this way, by the processor 70 executing the program 722, the control device 7 can control the rotary drive unit 44, the moving unit 5, the tool changer 100, and the stocker 110.

[0176] (Recess formation mode M2) In the example shown in Figure 35, the control device 7 is capable of executing recess formation mode M2. Recess formation mode M2 ​​is a mode in which the rotating cutting tool 61 is moved along a second movement path PB (see Figure 24 or 28 if necessary) so that a recess 81 is formed in the first workpiece 8. By executing recess formation mode M2, a recess 81 including the first surface 82a and the second surface 82b described above is formed in the first workpiece 8.

[0177] As illustrated in Figure 35, when the recess formation mode M2 ​​is executed, the control device 7 moves the rotating cutting tool 61 along the second movement path PB described above so that a recess 81 is formed in the first workpiece 8. More specifically, the control device 7 transmits a second rotation command R2 to the rotation drive device 44 and a third movement command C3 to the movement device 5 so that the cutting tool 61 moves along the second movement path PB.

[0178] For example, the control device 7 executing the second program 722b generates a second rotation command R2 and generates the third movement command C3 based on the second path data 726b stored in the memory 72. The control device 7 also transmits the generated second rotation command R2 to the rotary drive device 44 and the generated third movement command C3 to the movement device 5 (more specifically, the first drive device 51b and the second drive device 52b). The rotary drive device 44, receiving the second rotation command R2, rotates the cutting tool 61 around the rotation axis AX. The movement device 5 (more specifically, the first drive device 51b and the second drive device 52b), receiving the third movement command C3, moves the rotating cutting tool 61 along the second movement path PB. In this way, a recess 81 is formed in the first workpiece 8, defined by a plurality of surfaces 82 including the first surface 82a and the second surface 82b.

[0179] (Tool change mode M3) In the example shown in Figure 36, the control device 7 is capable of executing tool change mode M3. Tool change mode M3 is a mode in which the tool holder 62 held by the machining head 4 (i.e., the tool holder 62 that holds the cutting tool 61) is replaced with a probe holder HD that holds the probe 21.

[0180] More specifically, after the recess formation mode M2 ​​has been executed, the control device 7 sends a first tool change command to the tool changer 100 so that the tool holder 62, which is held in the machining head 4 and holds the cutting tool 61, is replaced with a probe holder HD that holds the probe 21.

[0181] For example, the control device 7, which executes the third program 722c, generates a first tool change command. The control device 7 also transmits the first tool change command to the tool change device 100. Upon receiving the first tool change command, the tool change device 100 replaces the tool holder 62 held in the machining head 4 with a probe holder HD that holds the probe 21.

[0182] (Friction stir welding mode M1) As illustrated in Figure 37, after the execution of the tool change mode M3, the control device 7 can execute the friction stir welding mode M1. The friction stir welding mode M1 involves moving the rotating probe 21 along a first movement path PA that crosses the recess 81 (more specifically, a first movement path PA that completely crosses the recess 81). Since the friction stir welding mode M1 has been described in the first embodiment, a repeated explanation of the friction stir welding mode M1 will be omitted.

[0183] (Friction stir welding method) The above-described first preparation step (first step ST1) may also include the control device 7 generating the above-described third movement command C3 based on the above-described second path data 726b stored in the memory 72. The above-described first preparation step (first step ST1) may also include the movement device 5, which receives the third movement command C3, moving the rotating cutting tool 61 along the above-described second movement path PB. As the rotating cutting tool 61 moves along the second movement path PB, a recess 81 is formed in the first workpiece 8, defined by a plurality of surfaces 82 including a first surface 82a and a second surface 82b.

[0184] The first preparation step (first step ST1) described above may include the tool changer 100, which receives a first tool change command from the control device 7, replacing the tool holder 62 held on the machining head 4 with a probe holder HD that holds the probe 21.

[0185] The joining process described above (fourth step ST4) may also include the control device 7 generating the first movement command C1 based on the first path data 726a stored in the memory 72. The joining process described above (fourth step ST4) may also include the movement device 5 (more specifically, the second drive device 52b) receiving the first movement command C1 moving the rotating probe 21 along the first movement path PA. As the rotating probe 21 moves along the first movement path PA, the first workpiece 8 and the second workpiece 9 are friction stir-welded.

[0186] Furthermore, the joining process described above (fourth step ST4) may also include the control device 7 moving the probe 21 in a second direction DR2, and then moving the probe 21 in a third direction DR3, so as the rotating probe 21 crosses the recess 81, fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 are suppressed (more specifically, so that the axial load F is kept constant).

[0187] More specifically, the joining process described above (fourth step ST4) may include: (1) the control device 7 generating a second movement command C2 based on signal data received from the sensor 12 or data indicating the load of the motor 44m so as to suppress fluctuations in the axial load F (more specifically, so as to maintain the axial load F at a constant level); (2) the control device 7 transmitting the second movement command C2 to the movement device 5 (more specifically, the first drive device 51b); and (3) the movement device 5 (more specifically, the first drive device 51b) receiving the second movement command C2 moving the probe 21 in the second direction DR2, and then moving the probe 21 in the third direction DR3.

[0188] (Program 722) In the embodiment, program 722 (more specifically, program 722 including the first program 722a, the second program 722b, and the third program 722c) is a program that causes the machine tool 1 (more specifically, the control device 7 of the machine tool 1) to execute the first preparation step (first step ST1) and the joining step (fourth step ST4) of the friction stir welding method described above.

[0189] More specifically, the program 722 in the embodiment is a program for causing a machine tool 1 (more specifically, a control device 7 of the machine tool 1) to execute a friction stir welding method comprising: (1) preparing a first workpiece 8 having a recess 81 defined by a plurality of surfaces 82 including a first surface 82a whose height gradually decreases in a first direction DR1 and a second surface 82b whose height gradually increases in a first direction DR1; and (2) friction stir welding the first workpiece 8 and the second workpiece 9 using a friction stir welding tool 2 while the first workpiece 8 and the second workpiece 9 are superimposed on each other.

[0190] As illustrated in Figures 23 and 24, or Figures 27 and 28, the step of preparing the first workpiece 8 (first step ST1) includes forming a recess 81 using a cutting tool 61. Details of the step of preparing the first workpiece 8 (first step ST1) have been described in the first embodiment or the second embodiment described above, so a detailed explanation of this step will be omitted.

[0191] The step of friction stir welding the first workpiece 8 and the second workpiece 9 (fourth step ST4) involves (1) moving the friction stir welding tool 2 in the first direction DR1 so that the probe 21 of the friction stir welding tool 2 crosses at least a portion of the first region RG1 where the first workpiece 8 and the second workpiece 9 are in contact (see Figure 5), and (2) moving the friction stir welding tool 2 in the first direction DR1 so that the probe 21 crosses the second region RG2 where the gap between the first surface 82a and the second workpiece 9 gradually increases from zero in the first direction DR1. (1) Moving the friction stir welding tool 2 in a second direction DR2 to follow the change in height of the first surface 82a (see Figure 6), and (3) Moving the friction stir welding tool 2 in a first direction DR1 to follow the change in height of the second surface 82b (see Figure 8), while moving the friction stir welding tool 2 in a third direction DR3 to follow the change in height of the second surface 82b, while moving the friction stir welding tool 2 in a third direction DR3 to follow the change in height of the second surface 82b, while moving the probe 21 across a third region RG3 in the first direction DR1 (see Figure 8).

[0192] Furthermore, the step of friction stir welding the first workpiece 8 and the second workpiece 9 (fourth step ST4) includes controlling the position of the friction stir welding tool 2 so as the probe 21 moves in the first direction DR1 across the second region RG2 and the third region RG3, fluctuations in the axial load F that the friction stir welding tool 2 receives from the first workpiece 8 and the second workpiece 9 are suppressed.

[0193] The details of the step (fourth step ST4) in which the first workpiece 8 and the second workpiece 9 are friction stir-bonded have already been described in the first embodiment or the second embodiment described above, so a detailed explanation of this step will be omitted.

[0194] The memory 72 in the embodiment may be a non-volatile storage medium on which the above-described program 722 (more specifically, program 722 including the first program 722a, the second program 722b, and the third program 722c) is recorded. The non-volatile storage medium on which the above-described program 722 is recorded may be a portable storage medium 72M, as illustrated in Figure 38.

[0195] The present invention is not limited to the embodiments or modifications described above, and it is clear that each embodiment or modification can be appropriately modified or changed within the scope of the technical concept of the present invention. Furthermore, the various technologies used in each embodiment or modification can be applied to other embodiments or other modifications, as long as no technical inconsistencies arise. In addition, any optional additional configurations in each embodiment or modification can be omitted as appropriate.

[0196] For example, Figures 17 to 20 and 32 show an example where machine tool 1 is a vertical machining center. Alternatively, as illustrated in Figure 39, machine tool 1 in the embodiment may be a horizontal machining center. Further alternatively, as illustrated in Figure 40, machine tool 1 in the embodiment may be a lathe. [Explanation of symbols]

[0197] 1, 1A, 1B... Machine tool, 2... Friction stir welding tool, 3... Workpiece support member, 4... Machining head, 5... Moving device, 7... Control device, 8... First workpiece, 8a... Block, 8b, 8c, 8d... Case body, 8u... Top surface, 9... Second workpiece, 9a, 9b, 9c, 9d... Plate, 9s... Bottom surface, 12, 12a, 12b, 12c... Sensor, 13... Data receiver, 14... Communication interface, 18... Power receiving unit, 21... Probe, 23... Shoulder, 30... Base, 31... Table, 42... Rotating body, 43... Frame, 44... Rotary drive device, 44m... Motor, 48... Power supply unit, 51... 1. Moving device, 51a...First moving body, 51b...First drive device, 52a...Support, 52b...Second drive device, 58...Second moving device, 58b...Third drive device, 61...Cutting tool, 62...Tool holder, 70...Hardware processor, 71a...First control unit, 71b...Second control unit, 72...Memory, 72M...Storage medium, 74...Communication circuit, 76...Input device, 78...Bus, 81...Recess, 81e...End on the fourth direction side, 81f...End on the fifth direction side, 82...Surface, 82a...First surface, 82b...Second surface, 82c...Third surface, 83...First part, 84a...First stepped part, 84b...Second stepped part, 85...Concave 86...Second part, 87...Welded part, 88a...First piece, 88b...Second piece, 91...Part facing the recess, 91u...Flat surface, 91v...Concave surface, 100...Tool changer, 101...Tool changer arm, 104...Arm rotation device, 106...Arm movement device, 110...Stocker, 114...Holder removal device, 722...Program, 722a...First program, 722b...Second program, 722c...Third program, 726a...First path data, 726b...Second path data, 762...Display with touch panel, AX...Rotation axis, AX1...First axis, AX2...Second axis, C...Movement Command, C1...First movement command, C2...Second movement command, C3...Third movement command, C4...Movement command, CS1...Inclined surface, CS2...Inclined surface, D...Jointed item, D2...Battery case, D3...Inverter case, D4...Motor case, F...Axial load, G2, G3, G4...Gap, HD...Probe holder, OP...Opening, PA...First movement path, PA1...Straight path, PA2...Curved path, PA3...Arc-shaped path, PB...Second movement path, PS1...Inclined surface, PS2...Inclined surface, R...Rotation command, R1...First rotation command, R2...Second rotation command, RG1...First region, RG2...Second region,RG3...Third region, RG4...Fourth region, RG5...Fifth region, S1...Signal data, S2...Data indicating the motor drive current value.

Claims

1. preparing a first workpiece having a recess defined by a plurality of surfaces including a first surface whose height gradually decreases in a first direction and a second surface whose height gradually increases in the first direction; Preparing a second workpiece; A process of overlapping the first workpiece and the second workpiece so as to form a first region where the first workpiece and the second workpiece are in contact with each other, a second region where the gap between the first surface and the second workpiece gradually increases from zero in the first direction, and a third region where the gap between the second surface and the second workpiece gradually decreases to zero in the first direction; a step of friction stir welding the first workpiece and the second workpiece using a friction stir welding tool; Equipped with The step of friction stir welding the first workpiece and the second workpiece includes: moving the friction stir welding tool in the first direction such that a probe of the friction stir welding tool crosses at least a portion of the first region; When a depth direction of the recess is defined as a second direction, the friction stir welding tool is moved in the first direction so that the probe crosses the second region, and the friction stir welding tool is moved in the second direction so as to follow a change in height of the first surface; When a direction opposite to the second direction is defined as a third direction, the friction stir welding tool is moved in the first direction so that the probe crosses the third region, and the friction stir welding tool is moved in the third direction so as to follow a change in height of the second surface. Including, When the probe moves in the first direction across each of the second region and the third region, the position of the friction stir welding tool is controlled so that a variation in an axial load that the friction stir welding tool receives from the first workpiece and the second workpiece is suppressed. Friction stir welding method.

2. A position of the friction stir welding tool is controlled such that the axial load is maintained constant as the probe moves in the first direction across each of the second and third regions. The friction stir welding method according to claim 1 .

3. a sensor detecting the axial load; a controller receiving signal data from the sensor indicative of the axial load; Further comprising: In response to a decrease in the axial load when the probe crosses the second region, the control device corrects a position of the friction stir welding tool in the second direction; In response to an increase in the axial load when the probe crosses the third region, the control device corrects the position of the friction stir welding tool in the third direction. The friction stir welding method according to claim 1 or 2.

4. The control device further includes a step of acquiring a load applied to a motor that rotates the probe around a rotation axis, the control device corrects a position of the friction stir welding tool in the second direction in response to a decrease in the load when the probe crosses the second region; The control device corrects a position of the friction stir welding tool in the third direction in response to an increase in the load when the probe crosses the third region. The friction stir welding method according to claim 1 or 2.

5. the plurality of surfaces defining the recess include the first surface, the second surface, and a third surface that is disposed between the first surface and the second surface and has a constant height; The step of overlapping the first workpiece and the second workpiece includes forming a fourth region disposed between the second region and the third region, The step of friction stir welding the first workpiece and the second workpiece includes moving the probe so that the probe traverses the second region, the fourth region, and the third region in this order. The friction stir welding method according to claim 1 or 2.

6. The step of preparing a first workpiece includes: forming the first surface by cutting a first step portion between a first portion of the first workpiece and a recess in the first workpiece; forming the second surface by cutting a second step portion between a second portion of the first workpiece and the recess of the first workpiece; Includes The friction stir welding method according to claim 1 or 2.

7. The first workpiece includes a welded portion, The step of preparing the first workpiece includes forming the recess by cutting the welded portion and a portion adjacent to the welded portion. The friction stir welding method according to claim 6.

8. The first workpiece includes a welded portion, The step of preparing the first workpiece includes forming the first surface and the second surface by cutting the welded portion and a portion adjacent to the welded portion. The friction stir welding method according to claim 1 or 2.

9. the friction stir welding tool includes a shoulder that presses a surface of the second workpiece on the third direction side, As the probe moves in the first direction across the second region, both the probe and the shoulder move in the second direction to track changes in height of the first surface. The friction stir welding method according to claim 1 or 2.

10. providing a first component having a recess defined by a plurality of surfaces including a first surface having a decreasing height in a first direction and a second surface having a decreasing height in the first direction; Providing a second part; overlapping the first component and the second component so as to form a first region where the first component and the second component are in contact with each other, a second region where a gap between the first surface and the second component gradually increases from zero in the first direction, and a third region where a gap between the second surface and the second component gradually decreases to zero in the first direction; using a friction stir welding tool to friction stir weld the first component and the second component; Equipped with The step of friction stir welding the first component and the second component includes: moving the friction stir welding tool in the first direction such that a probe of the friction stir welding tool crosses at least a portion of the first region; When a depth direction of the recess is defined as a second direction, the friction stir welding tool is moved in the first direction so that the probe crosses the second region, and the friction stir welding tool is moved in the second direction so as to follow a change in height of the first surface; When a direction opposite to the second direction is defined as a third direction, the friction stir welding tool is moved in the first direction so that the probe crosses the third region, and the friction stir welding tool is moved in the third direction so as to follow a change in height of the second surface. Including, A position of the friction stir welding tool is controlled so that a variation in an axial load that the friction stir welding tool receives from the first part and the second part is suppressed when the probe moves in the first direction across each of the second region and the third region. Manufacturing methods for automotive parts.

11. the first component is a case body that houses a battery, an inverter, or a motor, The second part is a plate that covers the opening of the case body. The method for manufacturing an automobile part according to claim 10.

12. The recess extends in a fourth direction perpendicular to the second direction, When a direction opposite to the fourth direction is defined as a fifth direction, in a state in which the second component is overlapped with the first component, at least one of an end of the recess on the fourth direction side and an end of the recess on the fifth direction side is open. The method for manufacturing an automobile part according to claim 10 or 11.

13. a work support member that supports the first work and the second work; A processing head that supports a probe of a friction stir welding tool so as to be rotatable around a rotation axis; a rotation drive device that rotates the probe around the rotation axis; A moving device that moves the processing head relative to the work support member; a control device for controlling the rotation drive device and the moving device; Equipped with The control device is capable of executing a friction stir welding mode in which the first workpiece and the second workpiece are friction stir welded together in a state in which the second workpiece is superimposed on the first workpiece having a recess defined by a plurality of surfaces including a first surface whose height gradually decreases in a first direction and a second surface whose height gradually increases in the first direction, The friction stir welding mode is moving the friction stir welding tool in the first direction so that the probe crosses at least a part of a first region where the first workpiece and the second workpiece are in contact with each other; When a depth direction of the recess is defined as a second direction, the friction stir welding tool is moved in the first direction so that the probe crosses a second region in which a gap between the first surface and the second workpiece gradually increases from zero in the first direction, while moving the friction stir welding tool in the second direction so as to follow a change in height of the first surface; When a direction opposite to the second direction is defined as a third direction, the friction stir welding tool is moved in the first direction so that the probe crosses a third region in which a gap between the second surface and the second workpiece gradually decreases to zero in the first direction, while moving the friction stir welding tool in the third direction so as to follow a change in height of the second surface. Including, When the probe moves in the first direction across each of the second region and the third region, the control device controls a position of the friction stir welding tool so as to suppress a variation in an axial load that the friction stir welding tool receives from the first workpiece and the second workpiece. Machine tools.

14. the control device is capable of executing a recess forming mode in which the cutting tool in a rotating state is moved along a second movement path so as to form the recess in the first workpiece; The friction stir welding mode includes moving the probe in a rotating state along a first path of movement across the recess. The machine tool according to claim 13.

15. preparing a first workpiece having a recess defined by a plurality of surfaces including a first surface whose height gradually decreases in a first direction and a second surface whose height gradually increases in the first direction; a step of friction stir welding the first workpiece and the second workpiece in a state where the first workpiece and the second workpiece are overlapped with each other, using a friction stir welding tool; A program for causing a machine tool to execute a friction stir welding method comprising: The step of preparing the first workpiece includes forming the recess using a cutting tool; The step of friction stir welding the first workpiece and the second workpiece includes: moving the friction stir welding tool in the first direction so that a probe of the friction stir welding tool crosses at least a part of a first region where the first workpiece and the second workpiece are in contact with each other; When a depth direction of the recess is defined as a second direction, the friction stir welding tool is moved in the first direction so that the probe crosses a second region in which a gap between the first surface and the second workpiece gradually increases from zero in the first direction, while moving the friction stir welding tool in the second direction so as to follow a change in height of the first surface; When a direction opposite to the second direction is defined as a third direction, the friction stir welding tool is moved in the first direction so that the probe crosses a third region in which a gap between the second surface and the second workpiece gradually decreases to zero in the first direction, while moving the friction stir welding tool in the third direction so as to follow a change in height of the second surface. Including, The step of friction stir welding the first workpiece and the second workpiece includes: and controlling a position of the friction stir welding tool so that a variation in an axial load that the friction stir welding tool receives from the first workpiece and the second workpiece is suppressed when the probe moves in the first direction across each of the second region and the third region. program.

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