Friction Stir Welding Tool, Friction Stir Welding Apparatus, and Friction Stir Welding Method

Abstract

The present invention provides a friction stir welding tool, a friction stir welding apparatus, and a friction stir welding method. The friction stir welding tool includes: a shoulder having a shoulder surface that contacts a workpiece; and a probe that protrudes from the shoulder and is rotatable about a first axis. On the outer peripheral surface of the probe, a spiral groove portion and a chamfered portion are alternately formed in the circumferential direction of the probe. When the rotation direction of the probe is defined as a first rotation direction, the spiral groove portion has a plurality of grooves that approach the shoulder surface as they face the first rotation direction. An inclined surface is formed on a part of the end surface of the tip portion of the probe, and the inclined surface is connected to the chamfered portion and approaches the shoulder surface as it faces the first rotation direction.

Description

Technical Field

[0001] The present invention relates to a friction stir welding tool, a friction stir welding apparatus, and a friction stir welding method. Background Art

[0002] Friction Stir Welding is known to the public. In friction stir welding, two workpieces as joining objects are joined to each other by rotating a tool relative to the two workpieces. More specifically, the joining object portions of the two workpieces are softened by the frictional heat generated by the rotation of the tool. The softened material flows around the tool by the rotation of the tool. The two workpieces are joined by solidifying the material flowing around the tool.

[0003] As related art, Patent Document 1 discloses a friction stir welding apparatus for lap welding. The friction stir welding apparatus described in Patent Document 1 includes: a rotor having a shoulder; and a probe portion protruding from the shoulder and arranged concentrically with the axis of the rotor. On the circumferential surface of the probe portion, a spiral groove portion is formed from the front end portion of the probe portion toward the shoulder. Further, the groove of the spiral groove portion is formed such that the depth of the groove gradually decreases from the front end portion of the probe portion toward the shoulder.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-92971 Summary of the Invention

[0005] An object of the present invention is to provide a friction stir welding tool, a friction stir welding apparatus, and a friction stir welding method that can guide the softened material from the chamfered portion to the inclined surface and can guide the softened material guided to the inclined surface downward.

[0006] The friction stir welding tool in some embodiments includes: a shoulder having a shoulder surface in contact with a workpiece; and a probe protruding from the shoulder and rotatable about a first axis. On the outer circumferential surface of the probe, a spiral groove portion and a chamfered portion are alternately formed in the circumferential direction of the probe. When the rotation direction of the probe is defined as a first rotation direction, the spiral groove portion has a plurality of grooves approaching the shoulder surface as it goes toward the first rotation direction. An inclined surface is formed on a part of the end surface of the front end portion of the probe, and the inclined surface is connected to the chamfered portion and approaches the shoulder surface as it goes toward the first rotation direction.

[0007] In some embodiments, a friction stir welding apparatus includes: a friction stir welding tool; a workpiece support member that supports a workpiece; a tool holding member that holds the friction stir welding tool; a first driving device that relatively moves the tool holding member with respect to the workpiece support member; a second driving device that drives a probe of the friction stir welding tool to rotate about a first axis; and a control device that controls the first driving device and the second driving device. The friction stir welding tool includes: a shoulder having a shoulder surface that contacts the workpiece; and the probe that protrudes from the shoulder and is rotatable about the first axis. On an outer peripheral surface of the probe, a spiral groove portion and a chamfered portion are alternately formed in a circumferential direction of the probe. When a rotation direction of the probe is defined as a first rotation direction, the spiral groove portion has a plurality of grooves that approach the shoulder surface as it goes toward the first rotation direction. An inclined surface is formed on a part of an end surface of a tip portion of the probe, the inclined surface is connected to the chamfered portion, and approaches the shoulder surface as it goes toward the first rotation direction.

[0008] In some embodiments, a friction stir welding method includes: a step of preparing workpieces including a first workpiece and a second workpiece; a step of inserting a probe of the friction stir welding tool into the workpiece by relatively moving the friction stir welding tool with respect to the workpiece; a step of bringing a shoulder of the friction stir welding tool into contact with an upper surface of the workpiece by relatively moving the friction stir welding tool with respect to the workpiece; and a step of friction stir welding the first workpiece and the second workpiece by rotating the probe inserted into the workpiece about the first axis toward a first rotation direction. The step of friction stir welding the first workpiece and the second workpiece includes: forming softened material from the workpiece by using frictional heat generated by relative rotation between the probe and the workpiece; causing the softened material to flow downward by the plurality of grooves of the spiral groove portion formed on the outer peripheral surface of the probe; causing the softened material to flow about the first axis toward the first rotation direction by the chamfered portion formed on the outer peripheral surface of the probe; guiding the softened material from the chamfered portion to an inclined surface formed on a part of an end surface of a tip portion of the probe; and causing the inclined surface to cause the softened material to flow downward.

[0009] The present invention can provide a friction stir welding tool, a friction stir welding apparatus, and a friction stir welding method that can guide softened material from a chamfered portion to an inclined surface and can guide the softened material guided to the inclined surface downward. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic perspective view schematically showing a friction stir welding tool according to a first embodiment.

[0011] Figure 2It is a schematic perspective view showing a part of the friction stir welding tool in the first embodiment.

[0012] Figure 3 It is a schematic side view showing the state of friction stir welding using the friction stir welding tool in the first embodiment.

[0013] Figure 4 It is a schematic cross-sectional view showing the state of friction stir welding using the friction stir welding tool in the comparative example.

[0014] Figure 5 It is a schematic perspective view showing the state of the friction stir welding tool in the first embodiment being held by the tool holding member.

[0015] Figure 6 It is a schematic bottom view showing the friction stir welding tool in the first embodiment.

[0016] Figure 7 It is a schematic perspective view showing a part of the friction stir welding tool in the first embodiment.

[0017] Figure 8 It is a schematic side view showing a part of the friction stir welding tool in the first embodiment.

[0018] Figure 9 It is a schematic perspective view showing a part of the friction stir welding tool in the first embodiment.

[0019] Figure 10 It is a schematic perspective view showing a part of the friction stir welding tool in the first embodiment.

[0020] Figure 11 It is a schematic side view showing a part of the friction stir welding tool in the first embodiment.

[0021] Figure 12 It is a schematic side view showing a part of the friction stir welding tool in the first embodiment.

[0022] Figure 13 It is a schematic bottom view showing a part of the friction stir welding tool in the first embodiment.

[0023] Figure 14 It is a schematic bottom view showing a part of the friction stir welding tool in the first embodiment.

[0024] Figure 15 It is a schematic bottom view showing a part of the friction stir welding tool in the first modified example of the first embodiment.

[0025] Figure 16 is a schematic perspective view showing a part of a friction stir welding tool in a second modification of the first embodiment.

[0026] Figure 17 is a schematic side view showing a part of a friction stir welding tool in a second modification of the first embodiment.

[0027] Figure 18 is a schematic perspective view showing a part of a friction stir welding tool in a third modification of the first embodiment.

[0028] Figure 19 is a schematic side view showing a part of a friction stir welding tool in a third modification of the first embodiment.

[0029] Figure 20 is a schematic perspective view showing a part of a friction stir welding tool in a fourth modification of the first embodiment.

[0030] Figure 21 is a schematic side view showing a part of a friction stir welding tool in a fourth modification of the first embodiment.

[0031] Figure 22 is a schematic perspective view showing a part of a friction stir welding tool in a fifth modification of the first embodiment.

[0032] Figure 23 is a schematic side view showing a part of a friction stir welding tool in a fifth modification of the first embodiment.

[0033] Figure 24 is a schematic side view showing a state of friction stir welding using the friction stir welding tool in the first embodiment.

[0034] Figure 25 is a schematic view showing a friction stir welding apparatus in the second embodiment.

[0035] Figure 26 is a flowchart showing an example of a friction stir welding method in the embodiment.

[0036] Figure 27 is a flowchart showing an example of a plurality of sub-steps included in the joining process. Detailed Embodiments

[0037] Hereinafter, the friction stir welding tool 1, the friction stir welding apparatus 100, and the friction stir welding method in the embodiment will be described with reference to the drawings. In addition, in the following description of the embodiment, parts and components having the same function are denoted by the same reference numerals, and repeated description of the parts and components denoted by the same reference numerals is omitted.

[0038] (Definition of directions)

[0039] In this specification, the direction from the tip 31 of the probe 3 toward the base end 32 of the probe 3 is defined as the first direction DR1 (see Figure 2 etc.). In this specification, the direction opposite to the first direction DR1 is defined as the second direction DR2. Further, in this specification, the first direction DR1 is defined as "upward" and the second direction DR2 is defined as "downward".

[0040] (First embodiment)

[0041] Refer to Figures 1 to 24 , and the friction stir welding tool 1A in the first embodiment will be described. Figure 1 is a schematic perspective view schematically showing the friction stir welding tool 1A in the first embodiment. Figure 2 is a schematic perspective view schematically showing a part of the friction stir welding tool 1A in the first embodiment. Figure 3 is a schematic side view schematically showing the state of friction stir welding using the friction stir welding tool 1A in the first embodiment. In addition, in Figure 3 , in order to understand the positional relationship between the probe 3 and the workpiece W, the probe 3 inserted into the workpiece W is shown by a dashed line. Figure 4 is a schematic cross-sectional view schematically showing the state of friction stir welding using the friction stir welding tool in the comparative example. Figure 5 is a schematic perspective view schematically showing the state in which the friction stir welding tool 1A in the first embodiment is held by the tool holding member 103. Figure 6 is a schematic bottom view schematically showing the friction stir welding tool 1A in the first embodiment. Figure 7 is a schematic perspective view schematically showing a part of the friction stir welding tool 1A in the first embodiment. Figure 8 is a schematic side view schematically showing a part of the friction stir welding tool 1A in the first embodiment. Figure 9 and Figure 10 are schematic perspective views schematically showing a part of the friction stir welding tool 1A in the first embodiment. Figure 11 and Figure 12 are schematic side views schematically showing a part of the friction stir welding tool 1A in the first embodiment. Figure 13 andFigure 14 is a schematic bottom view showing a part of the friction stir welding tool 1A in the first embodiment. Figure 15 is a schematic bottom view showing a part of the friction stir welding tool 1A in the first modification of the first embodiment. Figure 16 is a schematic perspective view showing a part of the friction stir welding tool 1A in the second modification of the first embodiment. Figure 17 is a schematic side view showing a part of the friction stir welding tool 1A in the second modification of the first embodiment. Figure 18 is a schematic perspective view showing a part of the friction stir welding tool 1A in the third modification of the first embodiment. Figure 19 is a schematic side view showing a part of the friction stir welding tool 1A in the third modification of the first embodiment. Figure 20 is a schematic perspective view showing a part of the friction stir welding tool 1A in the fourth modification of the first embodiment. Figure 21 is a schematic side view showing a part of the friction stir welding tool 1A in the fourth modification of the first embodiment. Figure 22 is a schematic perspective view showing a part of the friction stir welding tool 1A in the fifth modification of the first embodiment. Figure 23 is a schematic side view showing a part of the friction stir welding tool 1A in the fifth modification of the first embodiment. Figure 24 is a schematic side view showing the state of friction stir welding using the friction stir welding tool 1A in the first embodiment. In addition, in [[ID=5 order to understand the positional relationship between the probe 3 and the workpiece W, the probe 3 inserted into the workpiece W is shown by a dashed line.

[0042] As ​ illustrated, the friction stir welding tool 1A in the first embodiment includes a shoulder 2 and a probe 3.

[0043] ​ In the example described, the shoulder 2 has a shoulder surface 21 that contacts the workpiece (in other words, the joining target member). The workpiece as the joining target member includes a first workpiece and a second workpiece joined to the first workpiece. ​ In the example described, the first workpiece W1 is placed on the second workpiece W2. In this case, the shoulder surface 21 of the shoulder 2 is arranged to contact the first workpiece W1 (more specifically, the upper surface of the first workpiece W1).

[0044] The probe 3 is inserted into the workpiece W when performing friction stir joining. The probe 3 protrudes from the shoulder 2 and can rotate around the first axis AX. By rotating the probe 3 around the first axis AX in a state where the probe 3 is in contact with the workpiece W, softened material is formed from the workpiece W. More specifically, by rotating the probe 3 around the first axis AX, frictional heat is generated between the probe 3 and the workpiece W, and the frictional heat is used to soften the material constituting the workpiece W. As a result, the material constituting the workpiece W becomes softened material in the vicinity of the probe 3. In addition, the softened material formed from the workpiece W by rotating the probe 3 around the first axis AX plastically flows by the friction between the probe 3 and the softened material. Hereinafter, "plastic flow" will be simply referred to as "flow".

[0045] ​ In the described example, on the outer peripheral surface 33s of the probe 3, spiral groove portions 34 and chamfered portions 35 are alternately formed in the circumferential direction DR3 of the probe 3.

[0046] ​ In the described example, when the probe 3 rotates around the first axis AX, the spiral groove portion 34 causes the softened material M to flow in the vertical direction. More specifically, when the probe 3 rotates around the first axis AX in the first rotation direction R1, the spiral groove portion 34 causes the softened material M formed from the workpiece W to flow downward.

[0047] The spiral groove portion 34 has a plurality of grooves V that approach the shoulder surface 21 as it faces the first rotation direction R1 (in other words, a plurality of grooves V that face the first direction DR1 as it faces the first rotation direction R1). When the probe 3 rotates around the first axis AX in the first rotation direction R1, the plurality of grooves V cause the softened material M formed from the workpiece W to flow downward.

[0048] In addition, ​ In the described example, when the probe 3 rotates around the first axis AX, the chamfered portion 35 causes the softened material M to flow in the direction along the circumferential direction of the probe 3. More specifically, when the probe 3 rotates around the first axis AX in the first rotation direction R1, the chamfered portion 35 causes the softened material M formed from the workpiece W to flow in the first rotation direction R1.

[0049] ​In the described example, the probe 3 is in contact with both the first workpiece W1 and the second workpiece W2. In this case, by rotating the probe 3 about the first axis AX, the chamfered portion 35 causes the first softened material M1 formed from the first workpiece W1 and the second softened material M2 formed from the second workpiece W2 to flow in the circumferential direction of the probe 3, respectively. Thus, the first softened material M1 and the second softened material M2 are effectively friction stir welded, and the first workpiece W1 and the second workpiece W2 are firmly joined. In addition, the frictional heat generated by the relative movement between the probe 3 and the workpiece W also reaches a region slightly away from the probe 3. Therefore, the probe 3 can also be rotated about the first axis AX in a state where the probe 3 is only in contact with the first workpiece W1. In other words, the second workpiece W2 only needs to be located at a position where the frictional heat generated by the relative movement between the probe 3 and the first workpiece W1 reaches, and the probe 3 does not necessarily have to be in contact with the second workpiece W2.

[0050] ​ In the described example, an inclined surface 37 connected to the chamfered portion 35 is formed on a part of the end surface 310 of the tip portion 31 of the probe 3 (in other words, the end surface 310 on the second direction DR2 side of the tip portion 31 of the probe 3). The inclined surface 37 is an inclined surface that approaches the shoulder surface 21 as it faces the first rotation direction R1 (in other words, an inclined surface that faces the first direction DR1 as it faces the first rotation direction R1).

[0051] ​ In the described example, when the probe 3 rotates about the first axis AX in the first rotation direction R1, the softened material M formed from the workpiece W is guided from the chamfered portion 35 to the inclined surface 37 (see ​ and ​ for the arrow AR1). In addition, when the probe 3 rotates about the first axis AX in the first rotation direction R1, the inclined surface 37 guides the softened material M guided from the chamfered portion 35 to the inclined surface 37 downward (see ​ for the arrow AR2). Thereby, the formation of the hook portion F (see ​ ) generated by the upward movement of the softened material M around the tip portion 31 of the probe 3 is prevented or suppressed.

[0052] In the ​In the described example, it is assumed that the first material constituting the first workpiece W1 is softer than the second material constituting the second workpiece W2. In this case, when the probe 3 rotates around the first axis AX, in the region around the tip portion 31 of the probe 3, the second material constituting the second workpiece W2 moves toward the softer first material side. Further, by the second material constituting the second workpiece W2 moving toward the first material side, the second material forms an upward hook portion F around the tip portion 31 of the probe 3. In the case where such a hook portion F is formed, in the region around the tip portion 31 of the probe 3, the mixing of the first material and the second material is insufficient, and defects (i.e., unbonded portions) are likely to occur at the boundary between the first workpiece W1 and the second workpiece W2.

[0053] In the friction stir welding tool 1A of the first embodiment, the probe 3 has a spiral groove portion 34 and a chamfered portion 35. Therefore, by rotating the probe 3 around the first axis AX, the spiral groove portion 34 and the chamfered portion 35 can effectively cause the softened material M formed from the workpiece W to flow in the vertical direction and in the direction along the circumference of the probe 3. By means of this flow, the first material constituting the first workpiece W1 and the second material constituting the second workpiece W2 are well stirred, and the first workpiece W1 and the second workpiece W2 are firmly joined.

[0054] Further, in the friction stir welding tool 1A of the first embodiment, an inclined surface 37 connected to the chamfered portion 35 is formed on a part of the end surface 310 of the tip portion 31 of the probe 3. By the inclined surface 37 being connected to the chamfered portion 35, when the probe 3 rotates around the first axis AX, the softened material M is smoothly guided from the chamfered portion 35 to the inclined surface 37. Further, by rotating the probe 3 around the first axis AX, the inclined surface 37 guides the softened material M guided to the inclined surface 37 from the chamfered portion 35 downward. By the inclined surface 37 guiding the softened material M downward, the first material constituting the first workpiece W1 and the second material constituting the second workpiece W2 are well stirred in the region near the tip portion 31 of the probe 3. Thus, the first workpiece W1 and the second workpiece W2 are firmly joined.

[0055] Further, in the case where the first workpiece W1 and the second workpiece W2 are overlapped and joined by the friction stir welding tool 1A, the above-described hook portion F is not easily formed around the tip portion 31 of the probe 3. As a result, defects (i.e., unbonded portions) are not easily generated at the boundary between the first workpiece W1 and the second workpiece W2.

[0056] (Optional additional structure)

[0057] Next, with reference to ​ , an optional additional structure that can be adopted in the first embodiment will be described.

[0058] (Base end portion 5)

[0059] ​ In the described example, the friction stir welding tool 1A has a base end portion 5 and a front end portion where the probe 3 is disposed. The base end portion 5 of the friction stir welding tool 1A is held by a tool holding member 103 of the friction stir welding apparatus (refer to ​ if necessary).

[0060] ​ In the described example, the base end portion 5 has an outer peripheral surface 50t, and the outer peripheral surface 50t includes a first surface 51t having an arcuate shape and a second surface 52t having a planar shape. The second surface 52t functions as a surface to be pressed by the front end of a fixing member such as a fixing screw. In addition, the structure of the base end portion 5 can also be adopted in the first to fifth modification examples described later.

[0061] (Chamfered portion 35)

[0062] ​ In the described example, the chamfered portion 35 includes a first chamfered portion 35-1 formed on the outer peripheral surface 33s of the probe 3 and a second chamfered portion 35-2 formed on the outer peripheral surface 33s of the probe 3. Additionally, the chamfered portion 35 may also include a third chamfered portion 35-3 formed on the outer peripheral surface 33s of the probe 3, and may further include other chamfered portions formed on the outer peripheral surface 33s of the probe 3. In other words, the number of chamfered portions 35 formed on the outer peripheral surface 33s of the probe 3 can be two, three, or four or more.

[0063] ​ In the described example, the first chamfered portion 35-1 extends from the front end portion 31 of the probe 3 toward the shoulder surface 21 of the shoulder 2. The first chamfered portion 35-1 constitutes the first side surface of the probe 3.

[0064] ​ In the described example, the first chamfered portion 35-1 (in other words, the first side surface of the probe 3) is an inclined surface inclined with respect to the first axis AX. More specifically, the first chamfered portion 35-1 is an inclined surface that approaches the first axis AX as it goes from the base end portion 32 to the front end portion 31 of the probe 3. ​ In the described example, the first chamfered portion 35-1 is a planar chamfered portion, but the first chamfered portion 35-1 can also be a concave chamfered portion or a convex chamfered portion.

[0065] ​ (or ​In the described example, the angle α1 formed between the first chamfered portion 35-1 and a line parallel to the first axis AX (more specifically, the angle α1 formed between the line connecting the center E1 of the upper side of the first chamfered portion 35-1 and the center E2 of the lower side of the first chamfered portion 35-1 and a line parallel to the first axis AX) is greater than 0 degrees and 45 degrees or less.

[0066] Alternatively, as ​ (or ​ ) illustrates, the first chamfered portion 35-1 (in other words, the first side surface of the probe 3) may also be parallel to the first axis AX.

[0067] ​ In the described example, the second chamfered portion 35-2 extends from the front end portion 31 of the probe 3 toward the shoulder surface 21 of the shoulder 2. The second chamfered portion 35-2 constitutes the second side surface of the probe 3.

[0068] ​ In the described example, the second chamfered portion 35-2 (in other words, the second side surface of the probe 3) is an inclined surface inclined with respect to the first axis AX. More specifically, the second chamfered portion 35-2 is an inclined surface that approaches the first axis AX as it goes from the base end portion 32 of the probe 3 toward the front end portion 31. ​ In the described example, the second chamfered portion 35-2 is a planar chamfered portion, but the second chamfered portion 35-2 may also be a concave chamfered portion or a convex chamfered portion.

[0069] ​ In the described example, the angle α2 formed between the second chamfered portion 35-2 and a line parallel to the first axis AX (more specifically, the angle α2 formed between the line connecting the center of the upper side of the second chamfered portion 35-2 and the center of the lower side of the second chamfered portion 35-2 and a line parallel to the first axis AX) is greater than 0 degrees and 45 degrees or less.

[0070] Alternatively, as ​ (or ​ ) illustrates, the second chamfered portion 35-2 (in other words, the second side surface of the probe 3) may also be parallel to the first axis AX.

[0071] In addition, it is preferable that the angle α1 formed between the first chamfered portion 35-1 and a line parallel to the first axis AX is the same as the angle α2 formed between the second chamfered portion 35-2 and a line parallel to the first axis AX. However, the angle α1 may also be different from the angle α2.

[0072] ​ In the described example, the third chamfered portion 35-3 extends from the front end portion 31 of the probe 3 toward the shoulder surface 21 of the shoulder 2. The third chamfered portion 35-3 constitutes the third side surface of the probe 3.​ In the described example, the third chamfered portion 35-3 is an inclined surface that is inclined with respect to the first axis AX. More specifically, the third chamfered portion 35-3 is an inclined surface that approaches the first axis AX as it goes from the base end portion of the probe 3 toward the front end portion 31. Alternatively, the third chamfered portion 35-3 (in other words, the third side surface of the probe 3) may also be parallel to the first axis AX.

[0073] ​ In the described example, the upper edge of the first chamfered portion 35-1 (or, the upper edge of the second chamfered portion 35-2) is connected to the shoulder surface 21, and the lower edge of the first chamfered portion 35-1 (or, the lower edge of the second chamfered portion 35-2) is connected to the end surface 310 of the probe 3. Alternatively, the upper edge of the first chamfered portion 35-1 (or, the upper edge of the second chamfered portion 35-2) may also be arranged at a position separated from the shoulder surface 21.

[0074] (Spiral groove portion 34)

[0075] ​ In the described example, the spiral groove portion 34 includes a first spiral groove portion 34-1 formed on the outer peripheral surface 33s of the probe 3, and a second spiral groove portion 34-2 formed on the outer peripheral surface 33s of the probe 3. Additionally, the spiral groove portion 34 may also include a third spiral groove portion 34-3 formed on the outer peripheral surface 33s of the probe 3, and may further include other spiral groove portions formed on the outer peripheral surface 33s of the probe 3. In other words, the number of spiral groove portions 34 formed on the outer peripheral surface 33s of the probe 3 may be two, may be three, or may be four or more. ​ In the described example, the number of spiral groove portions 34 formed on the outer peripheral surface 33s of the probe 3 (for example, three) is equal to the number of chamfered portions 35 formed on the outer peripheral surface 33s of the probe 3 (for example, three). ​ In the described example, when observed in the direction along the first direction DR1, a closed region RE (more specifically, a substantially triangular closed region RE) that surrounds the first axis AX (or, the central surface 38 described later) is formed by the plurality of spiral groove portions 34 and the plurality of chamfered portions 35.

[0076] ​In the described example, the first helical groove portion 34-1 includes a plurality of first grooves V1 that approach the shoulder surface 21 as they face the first rotation direction R1, and the second helical groove portion 34-2 includes a plurality of second grooves V2 that approach the shoulder surface 21 as they face the first rotation direction R1. In addition, the third helical groove portion 34-3 includes a plurality of third grooves V3 that approach the shoulder surface 21 as they face the first rotation direction R1. In this case, when the probe 3 rotates around the first axis AX in the first rotation direction R1, the plurality of first grooves V1, the plurality of second grooves V2, and the plurality of third grooves V3 will guide downward from the softened material formed by the workpiece W through the rotation of the probe 3.

[0077] ​ In the described example, the plurality of first grooves V1 disposed in the first helical groove portion 34-1, the plurality of second grooves V2 disposed in the second helical groove portion 34-2, and the plurality of third grooves V3 disposed in the third helical groove portion 34-3 cooperate to function as a helical groove. ​ In the described example, the plurality of second grooves V2 are separated from the plurality of first grooves V1 by the second chamfered portion 35-2. In addition, the plurality of third grooves V3 are separated from the plurality of first grooves V1 by the first chamfered portion 35-1.

[0078] ​ In the described example, in the direction along the circumferential direction DR3 of the probe 3, the first helical groove portion 34-1 is disposed between the first chamfered portion 35-1 and the second chamfered portion 35-2. In the direction along the circumferential direction DR3 of the probe 3, the second helical groove portion 34-2 is disposed between the second chamfered portion 35-2 and the third chamfered portion 35-3. In addition, in the direction along the circumferential direction DR3 of the probe 3, the third helical groove portion 34-3 is disposed between the third chamfered portion 35-3 and the first chamfered portion 35-1.

[0079] (The end face 310 of the front end portion 31 of the probe 3)

[0080] ​ In the described example, the end face 310 of the front end portion 31 of the probe 3 includes: a central surface 38; and at least one inclined surface 37 that is disposed at a position farther from the first axis AX than the central surface 38. ​ In the described example, the plurality of inclined surfaces (37-1, 37-2, 37-3) are respectively disposed at positions farther from the first axis AX than the outer edge portion of the central surface 38. In addition, in ​ In order to easily grasp the end face 310 of the front end portion 31 of the probe 3, a shadow formed by dots is added to the end face 310.

[0081] ​In the described example, when observed in the direction along the first direction DR1, the end face 310 of the tip portion 31 of the probe 3 is surrounded by a closed region RE (more specifically, a substantially triangular closed region RE), and the closed region RE is formed by a plurality of spiral groove portions 34 and a plurality of chamfered portions 35.

[0082] (Central plane 38)

[0083] ​ In the described example, the end face 310 of the tip portion 31 of the probe 3 includes a central plane 38 through which the first axis AX passes. ​ In the described example, the central plane 38 is a plane. Alternatively, the central plane 38 may also be a curved surface (for example, a convex curved surface or a concave curved surface). ​ In the described example, the central plane 38 is disposed on the side closer to the second direction DR2 (in other words, the side away from the shoulder face 21) than the plurality of inclined planes 37 respectively.

[0084] The central plane 38 inhibits the upward flow of the softening material M (refer to ​ ) when necessary. More specifically, when the probe 3 rotates about the first axis AX in the first rotation direction R1, the central plane 38 inhibits the softening material M flowing downward by means of the inclined plane 37 from flowing upward subsequently.

[0085] (Inclined plane 37)

[0086] ​ In the described example, the inclined plane 37 includes a first inclined plane 37-1 and a second inclined plane 37-2. Additionally, the inclined plane 37 may also include a third inclined plane 37-3, and may also include other inclined planes. In other words, the number of inclined planes formed on the end face 310 of the tip portion 31 of the probe 3 may be two, three, or four or more.

[0087] ​ In the described example, the number of inclined planes 37 formed on the end face 310 of the tip portion 31 of the probe 3 (for example, three) is equal to the number of spiral groove portions 34 formed on the outer peripheral surface 33s of the probe 3 (for example, three).

[0088] ​ In the described example, the inclined plane 37 is inclined in a manner approaching the shoulder face 21 as it faces the first rotation direction R1 (in other words, the inclined plane 37 is a face facing the first direction DR1 as it faces the first rotation direction R1). In this case, when the probe 3 rotates about the first axis AX in the first rotation direction R1, the inclined plane 37 guides the softening material formed from the workpiece downward (refer to arrow AR2).

[0089] More specifically, a first inclined surface 37-1 formed on an end surface 310 of a front end portion 31 of the probe 3 is inclined so as to approach the shoulder surface 21 as it faces the first rotation direction R1, and a second inclined surface 37-2 formed on the end surface 310 of the front end portion 31 of the probe 3 is inclined so as to approach the shoulder surface 21 as it faces the first rotation direction R1. In addition, a third inclined surface 37-3 formed on the end surface 310 of the front end portion 31 of the probe 3 is inclined so as to approach the shoulder surface 21 as it faces the first rotation direction R1.

[0090] ​ In the described example, the first inclined surface 37-1, the second inclined surface 37-2, and the third inclined surface 37-3 are respectively planar inclined surfaces. Alternatively, the first inclined surface 37-1, the second inclined surface 37-2, and the third inclined surface 37-3 may respectively also be concave inclined surfaces or convex inclined surfaces.

[0091] ​ In the described example, the inclined surface 37 is connected to an outer edge portion 38u of the central surface 38 by means of a stepped surface 39. More specifically, the first inclined surface 37-1 is connected to a first outer edge portion 38u-1 of the central surface 38 by means of a first stepped surface 39-1, and the second inclined surface 37-2 is connected to a second outer edge portion 38u-2 of the central surface 38 by means of a second stepped surface 39-2. In addition, the third inclined surface 37-3 is connected to a third outer edge portion 38u-3 of the central surface 38 by means of a third stepped surface 39-3.

[0092] The stepped surface 39 causes the softening material M (refer to ​ if necessary) to flow in a direction along the circumferential direction of the probe 3. More specifically, when the probe 3 rotates about the first axis AX in the first rotation direction R1, the stepped surface 39 causes the softening material M to flow in the first rotation direction R1. By rotating in the first rotation direction R1 through the stepped surface 39, at least a part of the amount of movement of the softening material M imparted from the chamfered portion 35 in the first rotation direction R1 is maintained.

[0093] In addition, the stepped surface 39 may be omitted. In this case, the inclined surface 37 and the central surface 38 are smoothly connected without being connected by a step.

[0094] ​In the described example, when observed in the direction along the first axis AX (in other words, the extending direction of the inclined surface 37 (i.e., the long side direction of the inclined surface 37) is in the circumferential direction around the first axis AX. Further, when observed in the direction along the first axis AX, the width direction of the inclined surface 37 is in the radial direction radiating from the first axis AX. More specifically, when observed in the direction along the first axis AX, the extending direction of the first inclined surface 37-1 is in the circumferential direction around the first axis AX, and the width direction of the first inclined surface 37-1 is in the radial direction radiating from the first axis AX. Further, when observed in the direction along the first axis AX, the extending direction of the second inclined surface 37-2 is in the circumferential direction around the first axis AX, and the width direction of the second inclined surface 37-2 is in the radial direction radiating from the first axis AX. Further, when observed in the direction along the first axis AX, the extending direction of the third inclined surface 37-3 is in the circumferential direction around the first axis AX, and the width direction of the third inclined surface 37-3 is in the radial direction radiating from the first axis AX.

[0095] ​ In the described example, when observed in the direction along the first axis AX (more specifically, when observed in the direction along the first direction DR1), the first inclined surface 37-1, the second inclined surface 37-2, and the third inclined surface 37-3 each have a shape surrounded by a substantially arc-shaped outer edge and a substantially linear inner edge. Alternatively, when observed in the direction along the first axis AX, each inclined surface 37 may have other shapes.

[0096] ​ In the described example, in the direction along the circumferential direction DR3 of the probe 3, the first inclined surface 37-1 is disposed between the first chamfered portion 35-1 and the second chamfered portion 35-2. More specifically, the first end portion 37a-1 of the first inclined surface 37-1 is connected to the first chamfered portion 35-1, and the second end portion 37b-1 of the first inclined surface 37-1 is connected to the second chamfered portion 35-2.

[0097] ​In the described example, in a state where the probe 3 is inserted into the workpiece, it is assumed that the probe 3 rotates around the first axis AX in the first rotation direction R1. In this case, when the probe 3 rotates around the first axis AX, the softened material formed from the workpiece W is guided from the first chamfered portion 35-1 to the first inclined surface 37-1 (refer to arrow AR1), and the first inclined surface 37-1 guides the softened material guided from the first chamfered portion 35-1 to the first inclined surface 37-1 downward (refer to arrow AR2). In addition, the first inclined surface 37-1 guides a part of the softened material guided from the first chamfered portion 35-1 to the first inclined surface 37-1 to the second chamfered portion 35-2 (refer to arrow AR3). Therefore, it is possible to prevent the ability of the first inclined surface 37-1 (more specifically, the ability to guide the softened material downward) from being impaired due to the retention of the softened material near the first inclined surface 37-1.

[0098] ​ In the described example, in the direction along the circumferential direction DR3 of the probe 3, the second inclined surface 37-2 is disposed between the second chamfered portion 35-2 and the third chamfered portion 35-3. More specifically, the first end portion 37a-2 of the second inclined surface 37-2 is connected to the second chamfered portion 35-2, and the second end portion 37b-2 of the second inclined surface 37-2 is connected to the third chamfered portion 35-3. In addition, ​ In the described example, in the direction along the circumferential direction DR3 of the probe 3, the third inclined surface 37-3 is disposed between the third chamfered portion 35-3 and the first chamfered portion 35-1. More specifically, the first end portion 37a-3 of the third inclined surface 37-3 is connected to the third chamfered portion 35-3, and the second end portion 37b-3 of the third inclined surface 37-3 is connected to the first chamfered portion 35-1.

[0099] ​ In the described example, in a side view, the first chamfered portion 35-1, the first inclined surface 37-1, and the second chamfered portion 35-2 are arranged to form a substantially U shape. In other words, in a side view, a U-shaped portion P1 is formed by the first chamfered portion 35-1, the first inclined surface 37-1, and the second chamfered portion 35-2. The first chamfered portion 35-1 and the second chamfered portion 35-2 constitute two side portions of the U-shaped portion P1, and the first inclined surface 37-1 constitutes the bottom side of the U-shaped portion P1.

[0100] ​In the described example, in a side view, the first spiral groove portion 34-1 is disposed in the inner region of the U-shaped portion P1 formed by the first chamfer portion 35-1, the first inclined surface 37-1, and the second chamfer portion 35-2. In this case, the first inclined surface 37-1 forming the base of the U-shaped portion P1 can guide a part of the softened material formed from the workpiece from the first chamfer portion 35-1 toward the second chamfer portion 35-2, and the first spiral groove portion 34-1 disposed in the inner region of the U-shaped portion P1 can guide other parts of the softened material formed from the workpiece from the first chamfer portion 35-1 toward the second chamfer portion 35-2.

[0101] In addition, ​ In the described example, in a side view, the first spiral groove portion 34-1 is surrounded by the first chamfer portion 35-1, the first inclined surface 37-1, the second chamfer portion 35-2, and the shoulder 2. In this case, in a state where the upward movement of the softened material formed from the workpiece is restricted by the shoulder 2, the first spiral groove portion 34-1 and the first inclined surface 37-1 can smoothly guide the softened material from the first chamfer portion 35-1 toward the second chamfer portion 35-2.

[0102] In a side view, the second U-shaped portion may also be formed by the second chamfer portion 35-2, the second inclined surface 37-2, and the third chamfer portion 35-3. In addition, the second spiral groove portion 34-2 may be disposed in the inner region of the second U-shaped portion. Further, in a side view, the second spiral groove portion 34-2 may also be surrounded by the second chamfer portion 35-2, the second inclined surface 37-2, the third chamfer portion 35-3, and the shoulder 2.

[0103] In a side view, the third U-shaped portion may also be formed by the third chamfer portion 35-3, the third inclined surface 37-3, and the first chamfer portion 35-1. In addition, the third spiral groove portion 34-3 may be disposed in the inner region of the third U-shaped portion. Further, in a side view, the third spiral groove portion 34-3 may also be surrounded by the third chamfer portion 35-3, the third inclined surface 37-3, the first chamfer portion 35-1, and the shoulder 2.

[0104] ​ In the described example, the inclination angle of the inclined surface 37 with respect to the plane PL perpendicular to the first axis AX is 1 degree or more and 30 degrees or less. More specifically, the inclination angle β of the straight line connecting the upper end E3 and the lower end E4 of the first inclined surface 37-1 with respect to the plane PL perpendicular to the first axis AX is, for example, 1 degree or more and 30 degrees or less. When the inclination angle β is 1 degree or more and 30 degrees or less, the softened material formed from the workpiece is guided downward by the inclined surface 37 at an appropriate speed. However, in the embodiment, the above inclination angle β is not limited to 1 degree or more and 30 degrees or less.

[0105] ​In the described example, the inclination angle β of the first inclined surface 37-1 with respect to the surface PL perpendicular to the first axis AX is greater than the inclination angle of the first groove V1 of the first spiral groove portion 34-1 with respect to the surface PL perpendicular to the first axis AX. More specifically, in a side view, the angle formed between the first inclined surface 37-1 and the surface PL perpendicular to the first axis AX is greater than the angle formed between the extending direction of the first groove V1 of the first spiral groove portion 34-1 and the surface PL perpendicular to the first axis AX. Alternatively, the inclination angle β of the first inclined surface 37-1 with respect to the surface PL perpendicular to the first axis AX may also be smaller than the inclination angle of the first groove V1 of the first spiral groove portion 34-1 with respect to the surface PL perpendicular to the first axis AX. Further alternatively, the two inclination angles may also be equal to each other.

[0106] Preferably, the inclination angle of the second inclined surface 37-2 with respect to the surface PL perpendicular to the first axis AX is approximately equal to the inclination angle β of the first inclined surface 37-1 with respect to the surface PL perpendicular to the first axis AX. In addition, preferably, the inclination angle of the third inclined surface 37-3 with respect to the surface PL perpendicular to the first axis AX is approximately equal to the inclination angle β of the first inclined surface 37-1 with respect to the surface PL perpendicular to the first axis AX.

[0107] ​ In the described example, the height difference of the inclined surface 37 (for example, the first inclined surface 37-1) in the direction along the first axis AX is 0.1 mm or more and 5 mm or less (or 0.1 mm or more and 1 mm or less). More specifically, the interval H1 between the surface PL1 passing through the upper end E3 of the first inclined surface 37-1 and perpendicular to the first axis AX and the surface PL2 passing through the lower end E4 of the first inclined surface 37-1 and perpendicular to the first axis AX is 0.1 mm or more and 5 mm or less (or 0.1 mm or more and 1 mm or less). When the interval H is 0.1 mm or more and 5 mm or less, the softened material formed from the workpiece is guided downward by the inclined surface 37 at an appropriate speed. However, in the embodiment, the above interval H1 is not limited to 0.1 mm or more and 5 mm or less.

[0108] ​ In the described example, the central surface 38 (that is, the central surface 38 of the end face of the front end portion 31 of the probe 3) is located lower than the lower end E4 of the first inclined surface 37-1. The interval H2 between the surface PL2 passing through the lower end E4 of the first inclined surface 37-1 and perpendicular to the first axis AX and the surface PL3 passing through the lowermost end of the probe 3 and perpendicular to the first axis AX may also be smaller than the above interval H1.

[0109] ​In the described example, when observed in the direction along the first direction DR1, the outer side edge 37u of the inclined surface 37 overlaps with the spiral groove portion 34. More specifically, when observed in the direction along the first direction DR1, the first outer side edge 37u-1 of the first inclined surface 37-1 overlaps with the first spiral groove portion 34-1. When observed in the direction along the first direction DR1, the second outer side edge 37u-2 of the second inclined surface 37-2 overlaps with the second spiral groove portion 34-2. In addition, when observed in the direction along the first direction DR1, the third outer side edge 37u-3 of the third inclined surface 37-3 overlaps with the third spiral groove portion 34-3.

[0110] ​ In the described example, the distance between the inner side edge 37n of the inclined surface 37 and the first axis AX is smaller than the distance between the innermost edge of the spiral groove portion 34 and the first axis AX. Additionally, in ​ the innermost edge of the spiral groove portion 34 is represented by a dashed circle.

[0111] ​ In the described example, the distance L1 between the inner side edge 37n-1 of the first inclined surface 37-1 and the first axis AX is smaller than the distance L2 between the innermost edge of the first spiral groove portion 34-1 and the first axis AX. The distance L3 between the inner side edge 37n-2 of the second inclined surface 37-2 and the first axis AX is smaller than the distance L4 between the innermost edge of the second spiral groove portion 34-2 and the first axis AX. In addition, the distance L5 between the inner side edge 37n-3 of the third inclined surface 37-3 and the first axis AX is smaller than the distance L6 between the innermost edge of the third spiral groove portion 34-3 and the first axis AX.

[0112] When, when observed in the direction along the first direction DR1, the outer side edge 37u of the inclined surface 37 overlaps with the spiral groove portion 34, the combined size of the spiral groove portion 34 and the inclined surface 37 can be reduced when observed in the direction along the first direction DR1. Therefore, the size of the probe 3 does not become large. In addition, when the distance between the inner side edge 37n of the inclined surface 37 and the first axis AX is smaller than the distance between the innermost edge of the spiral groove portion 34 and the first axis AX, the area of the inclined surface 37 is sufficiently ensured. Therefore, the ability of the inclined surface 37 to guide the softening material downward is sufficiently ensured.

[0113] (Shape of the end face 310 of the probe 3)

[0114] ​ In the described example, the end face 310 of the front end portion 31 of the probe 3 has a central surface 38 and three inclined surfaces (37-1, 37-2, 37-3). ​In the described example, when observed in the direction along the first axis AX, the end face 310 of the tip portion 31 of the probe 3 has a substantially triangular shape. Additionally, in ​ in order to easily grasp the shape of the end face 310 of the tip portion 31 of the probe 3, a shadow formed by dots is added to this end face 310.

[0115] ​ In the described example, when observed in the direction along the first axis AX, the central face 38 has a substantially hexagonal shape. Further, when observed in the direction along the first axis AX, three sides of the substantially hexagonal shape define the boundaries (B1, B2, B3) between the central face 38 and the three inclined faces 37, and the other three sides of the substantially hexagonal shape define the boundaries (C1, C2, C3) between the central face 38 and the three chamfered portions 35.

[0116] Alternatively, in the first modification of the first embodiment, as ​ illustrated, when observed in the direction along the first axis AX, the end face 310 of the tip portion 31 of the probe 3 has a substantially quadrilateral shape, and the central face 38 has a substantially octagonal shape. Additionally, in ​ in order to easily grasp the shape of the end face 310 of the tip portion 31 of the probe 3, a shadow formed by dots is added to this end face 310.

[0117] ​ In the described example, when observed in the direction along the first axis AX, four sides of the central face 38 (in other words, four sides of the above-mentioned substantially octagonal shape) define the boundaries (B1, B2, B3, B4) between the central face 38 and the four inclined faces 37, and the other four sides of the central face 38 (in other words, the other four sides of the above-mentioned substantially octagonal shape) define the boundaries (C1, C2, C3, C4) between the central face 38 and the four chamfered portions 35.

[0118] Preferably, the total area of the plurality of inclined faces 37 ( ​ in the described example, the sum of the area of the first inclined face 37-1, the area of the second inclined face 37-2, and the area of the third inclined face 37-3) is more than 1 / 5 of the area of the central face 38. By having the total area of the plurality of inclined faces 37 be more than 1 / 5 of the area of the central face 38, the ability of the inclined faces 37 to guide the softened material downward is sufficiently ensured. Further, preferably, the total area of the plurality of inclined faces 37 is less than 2 / 3 of the area of the central face 38. By having the total area of the plurality of inclined faces 37 be less than 2 / 3 of the area of the central face 38, the downward flow of the softened material will not be excessive. However, the embodiment is not limited to the manner where the total area of the plurality of inclined faces 37 is more than 1 / 5 and less than 2 / 3 of the area of the central face 38.

[0119] (the tip portion 31 of the probe 3)

[0120] ​ In the described example, the distal end portion 31 of the probe 3 has an inclined surface 37, a central surface 38 through which the first axis AX passes, and a stepped surface 39 connecting the inclined surface 37 and the central surface 38. The stepped surface 39 may be a surface parallel to the first axis AX or a surface inclined with respect to the first axis AX. In addition, the stepped surface 39 may be a flat surface or a curved surface (for example, a convex curved surface or a concave curved surface).

[0121] ​ In the described example, the distal end portion 31 of the probe 3 has a first inclined surface 37-1, a central surface 38 through which the first axis AX passes, and a first stepped surface 39-1 connecting the first inclined surface 37-1 and the central surface 38. ​ In the described example, the first stepped surface 39-1 is connected to the first inclined surface 37-1, the central surface 38, the first chamfered portion 35-1, and the second chamfered portion 35-2 respectively. In other words, a first boundary line D1 is disposed between the first stepped surface 39-1 and the first inclined surface 37-1, a second boundary line D2 is disposed between the first stepped surface 39-1 and the central surface 38, a third boundary line D3 is disposed between the first stepped surface 39-1 and the first chamfered portion 35-1, and a fourth boundary line D4 is disposed between the first stepped surface 39-1 and the second chamfered portion 35-2. ​ In the described example, the length of the third boundary line D3 is longer than the length of the fourth boundary line D4. In addition, ​ In the described example, the length of the first boundary line D1 is slightly longer than the length of the second boundary line D2.

[0122] ​ In the described example, the distal end portion 31 of the probe 3 has a second inclined surface 37-2 and a second stepped surface 39-2 connecting the second inclined surface 37-2 and the central surface 38. ​ In the described example, the second stepped surface 39-2 is connected to the second inclined surface 37-2, the central surface 38, the second chamfered portion 35-2, and the third chamfered portion 35-3 respectively. In other words, a fifth boundary line D5 is disposed between the second stepped surface 39-2 and the second inclined surface 37-2, a sixth boundary line D6 is disposed between the second stepped surface 39-2 and the central surface 38, a seventh boundary line D7 is disposed between the second stepped surface 39-2 and the second chamfered portion 35-2, and an eighth boundary line D8 is disposed between the second stepped surface 39-2 and the third chamfered portion 35-3. ​ In the described example, the length of the seventh boundary line D7 is longer than the length of the eighth boundary line D8. In addition, ​ In the described example, the length of the fifth boundary line D5 is slightly longer than the length of the sixth boundary line D6.

[0123] ​In the described example, the front end portion 31 of the probe 3 has a third inclined surface 37-3 and a third stepped surface 39-3 that connects the third inclined surface 37-3 and the central surface 38.

[0124] (Shoulder 2)

[0125] ​ In the described example, the shoulder 2 is disposed between the base end portion 5 of the friction stir welding tool 1A and the probe 3. ​ In the described example, the shoulder 2 has a shoulder surface 21 that contacts the workpiece. The shoulder surface 21 is the end surface on the second direction DR2 side of the shoulder 2. The shoulder surface 21 flattens the material (i.e., the material constituting the workpiece) softened by the rotation of the probe 3. ​ In the described example, the shoulder surface 21 is substantially perpendicular to the first axis AX. Alternatively, the shoulder surface 21 may be inclined with respect to the first axis AX.

[0126] ​ In the described example, the shoulder 2 can rotate integrally with the probe 3 about the first axis AX. The shoulder 2 may also be integrally formed with the probe 3. Alternatively, the shoulder 2 may be fixed to the probe 3. Further alternatively, the shoulder 2 may be a fixed shoulder that does not rotate about the first axis AX. In this case, the probe 3 rotates relative to the shoulder 2 about the first axis AX.

[0127] In the second modification of the first embodiment, as ​ illustrated, at least one spiral groove 23 is formed in the shoulder surface 21. ​ In the described example, the at least one spiral groove 23 is a groove that moves away from the first axis AX as it approaches the first rotation direction R1.

[0128] ​ In the described example, assume a case where the shoulder 2 rotates about the first axis AX in the first rotation direction R1 in a state where the workpiece contacts the shoulder surface 21. In this case, a part of the material (i.e., the material constituting the workpiece) softened by the rotation of the probe 3 and the shoulder 2 is guided along the at least one spiral groove 23 in a direction approaching the first axis AX. Thus, the at least one spiral groove 23 supplies the softened material formed from the workpiece toward the probe 3. The softened material supplied toward the probe 3 by the at least one spiral groove 23 flows downward by means of the spiral groove portion 34 of the probe 3 and flows in the first rotation direction R1 by means of the chamfered portion 35 of the probe 3. Further, at the front end portion 31 of the probe 3, the softened material is guided from the chamfered portion 35 to the inclined surface 37, and the inclined surface 37 guides the softened material downward.

[0129] As described above, by using at least one spiral groove 23, a spiral groove portion 34, a chamfered portion 35, and an inclined surface 37, a smooth flow of the softened material is formed, and the first material constituting the first workpiece W1 and the second material constituting the second workpiece W2 are smoothly stirred. As a result, the first workpiece W1 and the second workpiece W2 are firmly joined.

[0130] ​ In the described example, the number of spiral grooves 23 formed on the shoulder surface 21 is two. Alternatively, the number of spiral grooves 23 formed on the shoulder surface 21 may be one, or three or more. In addition, the structure of the spiral groove 23 may also be adopted in the above-described first modification example or each of the following modification examples.

[0131] (Overall shape of the probe 3)

[0132] ​ and 17 In the described example, the probe 3 has a pointed shape. More specifically, ​ and ​ In the described example, the overall shape of the probe 3 is a substantially truncated cone shape with the cut portion removed by the chamfered portion 35. In other words, the overall shape of the probe 3 is a substantially truncated cone shape and has a shape cut by a plurality of chamfered portions 35. ​ and ​ In the described example, the outer diameter of the probe 3 becomes smaller toward the front end. In addition, ​ and ​ In the described example, each chamfered portion 35 of the probe 3 is formed by a surface that approaches the first axis AX as it faces the front end (in other words, as it faces the second direction DR2).

[0133] Refer to ​ and ​ to describe the third modification example of the first embodiment. ​ and ​ In the described example, the probe 3 has a pointed shape. More specifically, ​ and ​ In the described example, the overall shape of the probe 3 is a substantially truncated cone shape with the cut portion removed by the chamfered portion 35. In other words, the overall shape of the probe 3 is a substantially truncated cone shape and has a shape cut by a plurality of chamfered portions 35. ​ and ​ In the described example, the outer diameter of the probe 3 becomes smaller toward the front end. In addition, ​ and ​ In the described example, each chamfered portion 35 of the probe 3 is formed by a surface substantially parallel to the first axis AX.

[0134] As ​As exemplified, when the probe 3 has a pointed shape, it is sufficient that the insertion resistance is small when the probe 3 is inserted into the workpiece W.

[0135] Refer to ​ and ​ to describe the fourth modification of the first embodiment. ​ and ​ In the example described, the overall shape of the probe 3 is a substantially cylindrical shape with the cut-away portion removed by the chamfered portion 35. In other words, the overall shape of the probe 3 is a substantially cylindrical shape with a shape removed by a plurality of chamfered portions 35. In addition, ​ and ​ In the example described, each chamfered portion 35 of the probe 3 is composed of a surface substantially parallel to the first axis AX.

[0136] Refer to ​ and ​ to describe the fifth modification of the first embodiment. ​ and ​ In the example described, the overall shape of the probe 3 is a substantially cylindrical shape with the cut-away portion removed by the chamfered portion 35. In other words, the overall shape of the probe 3 is a substantially cylindrical shape with a shape removed by a plurality of chamfered portions 35. In addition, ​ and ​ In the example described, each chamfered portion 35 of the probe 3 is composed of a surface that approaches the first axis AX as it goes toward the front end (in other words, as it goes toward the second direction DR2).

[0137] As ​ exemplified, compared with the case where the probe 3 has a pointed shape, when the thickness of the probe 3 is substantially fixed in the direction along the second direction DR2, the area stirred by the front end portion 31 of the probe 3 becomes larger. Therefore, when using ​ the probe 3 exemplified, friction stir welding is performed over a larger range, and the first workpiece W1 and the second workpiece W2 are joined more firmly.

[0138] (workpiece W)

[0139] ​ In the example described, the workpiece W is a workpiece in a state where the first workpiece W1 is stacked on the second workpiece W2. ​ In the example described, the lower surface WL of the first workpiece W1 contacts the upper surface WU disposed on the second workpiece W2.

[0140] According to the friction stir welding tool 1A in the first embodiment, the inclined surface 37 provided on the end surface 310 of the tip portion 31 of the probe 3 has the ability to guide the softened material downward. This ability is useful when friction stir welding the upper surface WU of the second workpiece W2 and the lower surface WL of the first workpiece W1. More specifically, the inclined surface 37 suppresses the local upward flow of the second material constituting the second workpiece W2 toward the first workpiece W1 around the tip portion 31 of the probe 3. In this way, the inclined surface 37 prevents or suppresses ​ the formation of the hook portion F exemplified. As a result, defects (i.e., non-bonded portions) are not likely to occur at the boundary between the first workpiece W1 and the second workpiece W2.

[0141] ​ In the example described, the first material constituting the first workpiece W1 may also be softer than the second material constituting the second workpiece W2 disposed below the first workpiece W1. When the first material constituting the first workpiece W1 is softer than the second material constituting the second workpiece W2, in the region around the tip portion 31 of the probe 3, the second material constituting the second workpiece W2 is likely to locally flow upward toward the first workpiece W1. However, in the first embodiment, since the inclined surface 37 suppresses the local flow of the second material in the direction toward the first material, the formation of the above-described hook portion F can be efficiently prevented or suppressed even when the first material is relatively softer.

[0142] The second material constituting the second workpiece W2 is arbitrary, but as an example of the second material, a metal material such as an aluminum alloy is exemplified. The second workpiece W2 may also be a casting made of an aluminum alloy. The first material constituting the first workpiece W1 is arbitrary, and as an example of the first material, a metal material softer than the second material is exemplified. The first material may also be pure aluminum softer than the aluminum alloy. The first workpiece W1 may also be a rolled member made of aluminum.

[0143] ​ In the example described, the workpiece W is in a state where the side surface of the first workpiece W1 and the side surface of the second workpiece W2 are in contact with each other. In this case, the side surface of the first workpiece W1 and the side surface of the second workpiece W2 are friction stir welded by the friction stir welding tool 1A.

[0144] ​ In the example described, the first workpiece W1 and the second workpiece W2 are placed on the workpiece support member 101. In addition, ​In the described example, with the distal end portion 31 of the probe 3 separated from the upper surface of the workpiece support member 101, the probe 3 rotates about the first axis AX in the first rotational direction R1. In this case, the distal end portion 31 of the probe 3 does not reach the region close to the workpiece support member 101 (in other words, the region slightly above the workpiece support member 101).

[0145] The friction stir welding tool 1A in the first embodiment has an inclined surface 37 provided on the end face 310 of the distal end portion 31 of the probe 3. The inclined surface 37 allows the softened material to flow in the circumferential direction about the first axis AX and guides the softened material downward. Accordingly, in the region between the distal end portion 31 of the probe 3 and the workpiece support member 101, the first material constituting the first workpiece W1 and the second material constituting the second workpiece W2 are also effectively stirred. In other words, in the region slightly above the workpiece support member 101, poor joining between the first workpiece W1 and the second workpiece W2 does not occur either.

[0146] (Second Embodiment)

[0147] Refer to ​ , and describe the friction stir welding apparatus 100 in the second embodiment. ​ FIG. is a diagram schematically showing the friction stir welding apparatus 100 in the second embodiment.

[0148] The friction stir welding apparatus 100 includes: a friction stir welding tool 1, a workpiece support member 101, a tool holding member 103 that holds the friction stir welding tool 1, a first drive device 105 that relatively moves the tool holding member 103 with respect to the workpiece support member 101, a second drive device 107 that rotates the probe 3 (or the entire friction stir welding tool 1) about the first axis AX, and a control device 109.

[0149] The friction stir welding tool 1 held by the tool holding member 103 is the friction stir welding tool 1A described in the first embodiment. The friction stir welding tool 1A has a base end portion 5 (refer to ​ if necessary), a probe 3 disposed at the distal end portion, and a shoulder 2 disposed between the base end portion 5 and the probe 3. Regarding the friction stir welding tool 1A, since it has been described in the first embodiment (including each modification of the first embodiment), repeated description thereof is omitted.

[0150] The workpiece support member 101 supports the workpiece W as an object to be processed (more specifically, an object to be joined). The workpiece support member 101 is, for example, a support table for fixing the workpiece W. ​In the described example, the workpiece W in a state where the first workpiece W1 is stacked on the second workpiece W2 is supported by a workpiece support member 101 (support table). In this case, the first workpiece W1 and the second workpiece W2 are joined together by a friction stir joining tool 1. More specifically, ​ In the described example, the upper surface of the second workpiece W2 and the lower surface of the first workpiece W1 are joined by the friction stir joining tool 1.

[0151] Alternatively, it is also possible that, in a state where the side surface of the first workpiece W1 and the side surface of the second workpiece W2 are in contact with each other, the side surface of the first workpiece W1 and the side surface of the second workpiece W2 are joined by the friction stir joining tool 1 (refer to ​ if necessary).

[0152] ​ In the described example, the friction stir joining device 100 includes a base 102 and a drive device 105a (for example, a support table drive device) that relatively moves the workpiece support member 101 with respect to the base 102. The drive device 105a is one of the first drive devices 105 that relatively moves the tool holding member 103 with respect to the workpiece support member 101.

[0153] The tool holding member 103 holds the friction stir joining tool 1. Preferably, the tool holding member 103 can be attached to and detached from the frame 104 of the friction stir joining device 100.

[0154] ​ In the described example, the friction stir joining device 100 includes a second base 106 and a drive device 105b that relatively moves the tool holding member 103 with respect to the second base 106. The drive device 105b is one of the first drive devices 105 that relatively moves the tool holding member 103 with respect to the workpiece support member 101.

[0155] The first drive device 105 is a device that relatively moves the tool holding member 103 with respect to the workpiece support member 101. ​ In the described example, the first drive device 105 includes the drive device 105a that relatively moves the workpiece support member 101 with respect to the base 102 and the drive device 105b that relatively moves the tool holding member 103 with respect to the second base 106. Alternatively, the first drive device 105 may also include only one of the drive device 105a and the drive device 105b.

[0156] ​ In the described example, the drive device 105a is a device that moves the workpiece support member 101 in a direction along the horizontal plane (in other words, in a direction along the XY plane).

[0157] ​In the described example, the drive device 105b is a device that moves the tool holding member 103 three-dimensionally. In other words, the drive device 105b can move the tool holding member 103 in the direction along the X-axis, can move the tool holding member 103 in the direction along the Y-axis, and can move the tool holding member 103 in the direction along the Z-axis. ​ In the described example, the Z-axis is the direction along the vertical direction and is the direction parallel to the first direction DR1.

[0158] The second drive device 107 drives the probe 3 (or the entire friction stir welding tool 1) to rotate around the first axis AX.

[0159] The control device 109 controls the first drive device 105 and the second drive device 107. ​ In the described example, the control device 109 includes a first drive device control unit 109a that controls the first drive device 105 and a second drive device control unit 109b that controls the second drive device 107.

[0160] When the first drive device 105 receives a control signal from the control device 109 (more specifically, the first drive device control unit 109a), the first drive device 105 moves the workpiece support member 101 and / or the tool holding member 103. In other words, when the first drive device 105 receives a control signal from the control device 109, the first drive device 105 relatively moves the tool holding member 103 with respect to the workpiece support member 101.

[0161] When the second drive device 107 receives a control signal from the control device 109 (more specifically, the second drive device control unit 109b), the second drive device 107 rotates the probe 3 (or the entire friction stir welding tool 1) around the first axis AX.

[0162] ​ In the described example, the control device 109 includes a storage device 1091 (in other words, a memory) that stores programs and data. By the control device 109 executing the programs stored in the storage device 1091, the control device 109 functions as the above-described first drive device control unit 109a and / or second drive device control unit 109b.

[0163] ​ In the described example, the friction stir welding device 100 includes an input device 108 for inputting control parameters and the like to the control device 109.

[0164] The friction stir joining device 100 includes the friction stir joining tool 1A in the first embodiment. Therefore, the friction stir joining device 100 in the second embodiment can exhibit the same effects as the friction stir joining tool 1A in the first embodiment.

[0165] The friction stir joining device 100 in the second embodiment may also be a dedicated device specialized for friction stir joining. Alternatively, the friction stir joining device 100 in the second embodiment may also be constituted by a part of a compound processing machine capable of performing machining such as cutting.

[0166] (Friction Stir Joining Method)

[0167] Refer to ​ , and the friction stir joining method in the embodiment will be described. ​ is a flowchart showing an example of the friction stir joining method in the embodiment. ​ is a flowchart showing an example of the multiple sub-steps included in the joining process.

[0168] In the friction stir joining method of the embodiment, the friction stir joining tool 1 used may be the friction stir joining tool 1A in the first embodiment or other friction stir joining tools. In addition, the friction stir joining method in the embodiment may be performed using the friction stir joining device 100 in the second embodiment or other friction stir joining devices. Regarding each structural element of the friction stir joining tool 1 and each structural element of the friction stir joining device 100, since they have been separately described in the first embodiment and the second embodiment, the repeated description of each structural element of the friction stir joining tool 1 and each structural element of the friction stir joining device 100 is omitted.

[0169] In the first step ST1, a workpiece W including a first workpiece W1 and a second workpiece W2 is prepared. The first step ST1 is a preparation process. The first material constituting the first workpiece W1 is, for example, a material different from the second material constituting the second workpiece W2. The first material constituting the first workpiece W1 may also be softer than the second material constituting the second workpiece W2. Alternatively, the hardness of the first material constituting the first workpiece W1 may be approximately equal to the hardness of the second material constituting the second workpiece W2.

[0170] In the case of performing the overlapping joining (hereinafter simply referred to as "overlapping joining") of the first workpiece W1 and the second workpiece W2, in the preparation process, a workpiece W in a state where the first workpiece W1 is stacked on the second workpiece W2 (in other words, a workpiece W in a state where the lower surface of the first workpiece W1 contacts the upper surface of the second workpiece W2) is prepared (refer to ​)。In addition, the area of the lower surface of the first workpiece W1 may be equal to or different from the area of the upper surface of the second workpiece W2.

[0171] Alternatively, in the case of performing the butt joint (hereinafter simply referred to as "butt joint") between the first workpiece W1 and the second workpiece W2, in the preparation process, the workpiece W in a state where the side surface of the first workpiece W1 contacts the side surface of the second workpiece W2 is prepared.

[0172] In the second step ST2, the probe 3 of the friction stir welding tool 1 is inserted into the workpiece W. The second step ST2 is the insertion process. In the insertion process, the probe 3 is inserted into the workpiece W by relatively moving the friction stir welding tool 1 with respect to the workpiece W. The insertion process is performed while the probe 3 rotates around the first axis AX.

[0173] ​ In the described example (the example of performing the coincidence joint), the insertion process includes inserting the probe 3 into the first workpiece W1. ​ In the described example, after the insertion process is performed, the tip 31 of the probe 3 reaches the upper surface WU of the second workpiece W2 disposed below the first workpiece W1. In other words, after the insertion process is performed, at least a part of the end surface 310 of the tip 31 of the probe 3 crosses the boundary surface BP between the first workpiece W1 and the second workpiece W2 and enters the second workpiece W2.

[0174] ​ In the described example, after the insertion process is performed (or during the execution of the joining process described later), the upper end of the inclined surface 37 formed on the end surface 310 of the tip 31 of the probe 3 is located above the boundary surface BP between the first workpiece W1 and the second workpiece W2, and the lower end of the inclined surface 37 is located below the boundary surface BP between the first workpiece W1 and the second workpiece W2. In this case, when the probe 3 rotates around the first axis AX in the first rotation direction R1, the inclined surface 37 directly and effectively contributes to the mixing of the first softened material formed from the first workpiece W1 and the second softened material formed from the second workpiece W2.

[0175] In addition, after the insertion process is performed, the tip 31 of the probe 3 does not have to reach the upper surface WU of the second workpiece W2 disposed below the first workpiece W1. In other words, the positional relationship between the second workpiece W2 and the tip 31 of the probe 3 only needs to be set so that the frictional heat generated by the relative movement between the probe 3 and the first workpiece W1 can reach the second workpiece W2, and the tip 31 of the probe 3 does not have to reach the second workpiece W2.

[0176] ​In the described example (example of performing butt joint), the insertion process includes inserting the probe 3 into the boundary portion between the first workpiece W1 and the second workpiece W2.

[0177] In the third step ST3, the shoulder 2 of the friction stir welding tool 1 contacts the upper surface of the workpiece W. The third step ST3 is the contact process. In the contact process, the shoulder 2 is brought into contact with the upper surface of the workpiece W by the relative movement of the friction stir welding tool 1 relative to the workpiece W. The contact process is performed while the probe 3 is rotating about the first axis AX.

[0178] The contact process (third step ST3) and the insertion process (second step ST2) are continuously performed. More specifically, by the relative movement of the friction stir welding tool 1 relative to the workpiece W, the probe 3 is inserted into the workpiece W and the shoulder 2 is brought into contact with the upper surface of the workpiece W.

[0179] ​ In the described example (example of performing lap joint), the contact process includes bringing the shoulder surface 21 of the shoulder 2 into contact with the upper surface of the first workpiece W1.

[0180] ​ In the described example (example of performing butt joint), the contact process includes bringing the shoulder surface 21 of the shoulder 2 into contact with both the upper surface of the first workpiece W1 and the upper surface of the second workpiece W2.

[0181] In the fourth step ST4, the first workpiece W1 and the second workpiece W2 are friction stir welded. The fourth step ST4 is the welding process. As ​ or ​ illustrated, in the welding process, the first workpiece W1 and the second workpiece W2 are friction stir welded by rotating the probe 3 inserted into the workpiece W about the first axis AX in the first rotation direction R1. Further, in the welding process, the shoulder 2 in contact with the upper surface of the workpiece W rotates about the first axis AX in the first rotation direction R1. Alternatively, in the case where the shoulder 2 is a fixed shoulder, in the welding process, the shoulder 2 does not rotate about the first axis AX.

[0182] ​ In the described example (example of performing lap joint), the welding process includes rotating the workpiece W in a state where the probe 3 is in contact with the lower surface WL of the first workpiece W1 and the upper surface WU of the second workpiece W2 about the first axis AX in the first rotation direction R1.

[0183] On the other hand, ​ In the described example (example of performing butt joint), the welding process includes rotating the workpiece W in a state where the probe 3 is in contact with the side surface of the first workpiece W1 and the side surface of the second workpiece W2 about the first axis AX in the first rotation direction R1.

[0184] Describe multiple sub-steps of the joining process.

[0185] In sub-step ST4-1, a softening material is formed from the workpiece. Sub-step ST4-1 is the softening material forming process. In the softening material forming process, the softening material is formed from the workpiece W by using the frictional heat generated by the relative rotation between the probe 3 and the workpiece W.

[0186] ​ In the described example (the example of performing coincidence joining), in sub-step ST4-1, the first softening material M1 is formed from the first workpiece W1 by using the frictional heat generated by the relative rotation between the probe 3 and the first workpiece W1.

[0187] ​ In the described example (the example of performing butt joint joining), in sub-step ST4-1, the first softening material M1 is formed from the first workpiece W1 by using the frictional heat generated by the relative rotation between the probe 3 and the first workpiece W1, and the second softening material M2 is formed from the second workpiece W2 by using the frictional heat generated by the relative rotation between the probe 3 and the second workpiece W2.

[0188] In sub-step ST4-2, by rotating the shoulder 2 around the first axis AX in the first rotation direction R1, at least one spiral groove 23 formed on the shoulder surface 21 of the shoulder 2 (refer to ​ ) guides the softening material formed from the workpiece W in a direction approaching the first axis AX.

[0189] ​ In the described example (the example of performing coincidence joining), in sub-step ST4-2, by rotating the shoulder 2 around the first axis AX in the first rotation direction R1, at least one spiral groove 23 formed on the shoulder surface 21 of the shoulder 2 (refer to ​ ) guides the first softening material formed from the first workpiece W1 in a direction approaching the first axis AX.

[0190] ​ In the described example (the example of performing butt joint joining), in sub-step ST4-2, by rotating the shoulder 2 around the first axis AX in the first rotation direction R1, at least one spiral groove 23 formed on the shoulder surface 21 of the shoulder 2 (refer to ​ ) guides the first softening material formed from the first workpiece W1 in a direction approaching the first axis AX, and the at least one spiral groove 23 guides the second softening material formed from the second workpiece W2 in a direction approaching the first axis AX.

[0191] In addition, in the case where the spiral groove 23 is not formed on the shoulder surface 21, or in the case where the shoulder 2 is a fixed shoulder that does not rotate around the first axis AX, the sub-step ST4-2 is omitted.

[0192] In sub-step ST4-3, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the plurality of grooves V of the spiral groove portion 34 formed on the outer peripheral surface 33s of the probe 3 cause the softened material formed from the workpiece W to flow downward.

[0193] ​ In the described example (the example of performing coincidence joining), in sub-step ST4-3, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the plurality of grooves V of the spiral groove portion 34 formed on the outer peripheral surface 33s of the probe 3 cause the first softened material M1 formed from the first workpiece W1 to flow downward.

[0194] ​ In the described example (the example of performing butt joint joining), in sub-step ST4-3, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the plurality of grooves V of the spiral groove portion 34 formed on the outer peripheral surface 33s of the probe 3 cause the first softened material M1 formed from the first workpiece W1 to flow downward, and the plurality of grooves V of the spiral groove portion 34 cause the second softened material M2 formed from the second workpiece W2 to flow downward.

[0195] In sub-step ST4-4, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the chamfered portion 35 formed on the outer peripheral surface 33s of the probe 3 causes the softened material formed from the workpiece W to flow around the first axis AX in the first rotation direction R1.

[0196] ​ In the described example (the example of performing coincidence joining), in sub-step ST4-4, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the chamfered portion 35 formed on the outer peripheral surface 33s of the probe 3 causes the first softened material formed from the first workpiece W1 to flow around the first axis AX in the first rotation direction R1.

[0197] ​ In the described example (the example of performing butt joint joining), in sub-step ST4-4, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the chamfered portion 35 formed on the outer peripheral surface 33s of the probe 3 causes the first softened material formed from the first workpiece W1 to flow around the first axis AX in the first rotation direction R1, and the chamfered portion 35 causes the second softened material formed from the second workpiece W2 to flow around the first axis AX in the first rotation direction R1.

[0198] In addition, ​In the described example (example of performing butt joint), the chamfered portion 35 causes the first softening material M1 and the second softening material M2 to flow around the first axis AX in the first rotation direction R1, so that the first softening material M1 and the second softening material M2 are mixed in the region around the probe 3. Thus, in the region around the probe 3, a mixed softening material formed by mixing the first softening material M1 and the second softening material M2 is formed.

[0199] In sub-step ST4-5, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the softening material formed from the workpiece W is guided from the chamfered portion 35 to the inclined surface 37 formed on a part of the end surface 310 of the front end portion 31 of the probe 3.

[0200] ​ In the described example (example of performing coincidence joint), in sub-step ST4-5, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the first softening material formed from the first workpiece W1 is guided from the chamfered portion 35 to the inclined surface 37 formed on a part of the end surface 310 of the front end portion 31 of the probe 3 (refer to ​ the arrow AR1 in

[0201] ​ In the described example (example of performing butt joint), in sub-step ST4-5, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the mixed softening material formed by mixing the first softening material M1 and the second softening material M2 is guided from the chamfered portion 35 to the above-mentioned inclined surface 37.

[0202] In sub-step ST4-6, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the inclined surface 37 formed on the end surface 310 of the front end portion 31 of the probe 3 causes the softening material formed from the workpiece W to flow downward.

[0203] ​ In the described example (example of performing coincidence joint), in sub-step ST4-6, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the inclined surface 37 formed on the end surface 310 of the front end portion 31 of the probe 3 causes the first softening material formed from the first workpiece W1 to flow downward (refer to ​ the arrow AR2 in

[0204] In addition, in sub-steps ST4-6, the above-mentioned inclined surface 37 can also guide a part of the first softened material formed from the first workpiece W1 from one chamfered portion (for example, the first chamfered portion 35-1) to another chamfered portion (for example, the second chamfered portion 35-2) (refer to ​ for the arrow AR3 in).

[0205] ​ In the example described (the example of performing butt joint), in sub-steps ST4-6, by rotating the probe 3 around the first axis AX in the first rotation direction R1, the inclined surface 37 formed on the end surface 310 of the front end portion 31 of the probe 3 causes the mixed softened material formed by mixing the first softened material M1 and the second softened material M2 to flow downward.

[0206] In addition, in sub-steps ST4-6, the above-mentioned inclined surface 37 can also guide a part of the mixed softened material formed by mixing the first softened material M1 and the second softened material M2 from one chamfered portion (for example, the first chamfered portion 35-1) to another chamfered portion (for example, the second chamfered portion 35-2) (refer to ​ for the arrow AR3 in).

[0207] By performing the above-mentioned sub-steps ST4-1 to sub-steps ST4-6, the first softened material formed from the first workpiece W1 and the second softened material formed from the second workpiece W2 are mixed, and the first workpiece W1 and the second workpiece W2 are friction stir joined.

[0208] ​ In the example described (the example of performing coincidence joint), the friction stir joining method includes mixing the first softened material M1 that flows downward by using the inclined surface 37 in sub-steps ST4-6 with the second softened material M2 formed from the second workpiece W2 below the end surface 310 of the front end portion 31 of the probe 3. Since the first softened material M1 flows downward by using the inclined surface 37 (refer to ​ for the arrow AR2 in), in the region below the end surface 310, the first softened material M1 and the second softened material M2 are well mixed. Therefore, the formation of the hook portion F shown in ​ is prevented or suppressed.

[0209] ​In the described example (an example of performing butt joint), the friction stir joining method includes causing a mixed softened material formed by mixing a first softened material M1 and a second softened material M2 to flow downward along the inclined surface 37. In this case, in the region between the inclined surface 37 and the workpiece support member 101, the first workpiece W1 and the second workpiece W2 are also well friction stirred. Therefore, in a region slightly above the workpiece support member 101, poor joining between the first workpiece W1 and the second workpiece W2 does not occur either.

[0210] In addition, the above-described sub-steps ST4-1 to ST4-6 are performed in a manner of being advanced simultaneously.

[0211] In the fifth step ST5, with the shoulder surface 21 of the shoulder 2 in contact with the upper surface of the workpiece W, the probe 3 moves along the movement path. The fifth step ST5 is a movement process. The movement process is performed with the probe 3 rotating around the first axis AX. In other words, the movement process (fifth step ST5) is performed simultaneously with the joining process (fourth step ST4).

[0212] ​ In the described example (an example of performing lap joint), in the movement process, with the shoulder surface 21 of the shoulder 2 in contact with the upper surface of the first workpiece W1, the probe 3 moves in a direction parallel to the boundary plane BP between the first workpiece W1 and the second workpiece W2.

[0213] ​ In the described example (an example of performing butt joint), in the movement process, with the shoulder surface 21 of the shoulder 2 in contact with both the upper surface of the first workpiece W1 and the upper surface of the second workpiece W2, the probe 3 moves along the boundary plane between the first workpiece W1 and the second workpiece W2.

[0214] By performing the movement process, a joining region between the first workpiece W1 and the second workpiece W2 is formed along the movement path of the friction stir joining tool 1.

[0215] In addition, the present invention is not limited to the above-described embodiments or modified examples, and it is obvious that each embodiment or modified example can be appropriately deformed or changed within the scope of the technical concept of the present invention. Furthermore, various techniques used in each embodiment or modified example can also be applied to other embodiments or modified examples as long as no technical contradiction occurs. Moreover, any additional structures in each embodiment or modified example can be appropriately omitted.

[0216] Description of Reference Numerals

[0217] 1. 1A friction stir welding tool, 2 shoulder, 3 probe, 5 base end portion of the friction stir welding tool, 21 shoulder surface, 23 spiral groove, 31 tip end portion of the probe, 32 base end portion of the probe, 33s outer peripheral surface, 34 spiral groove portion, 34-1 first spiral groove portion, 34-2 second spiral groove portion, 34-3 third spiral groove portion, 35 chamfered portion, 35-1 first chamfered portion, 35-2 second chamfered portion, 35-3 third chamfered portion, 37 inclined surface, 37-1 first inclined surface, 37-2 second inclined surface, 37-3 third inclined surface, 37a-1 first end portion of the first inclined surface, 37a-2 first end portion of the second inclined surface, 37a-3 first end portion of the third inclined surface, 37b-1 second end portion of the first inclined surface, 37b-2 second end portion of the second inclined surface, 37b-3 second end portion of the third inclined surface, 37n inner side edge, 37n-1 inner side edge of the first inclined surface, 37n-2 inner side edge of the second inclined surface, 37n-3 inner side edge of the third inclined surface, 37u outer side edge, 37u-1 first outer side edge, 37u-2 second outer side edge, 37u-3 third outer side edge, 38 central surface, 38u outer edge portion, 38u-1 first outer edge portion, 38u-2 second outer edge portion, 38u-3 third outer edge portion, 39 stepped surface, 39-1 first stepped surface, 39-2 second stepped surface, 39-3 third stepped surface, 50t outer peripheral surface, 51t first surface, 52t second surface, 100 friction stir welding apparatus, 101 workpiece support member, 102 base, 103 tool holding member, 104 frame, 105 first driving device, 105a driving device, 105b driving device, 106 second base, 107 second driving device, 108 input device, 109 control device, 109a first driving device control unit, 109b second driving device control unit, 310 end surface, 1091 storage device, F hook portion, V groove, V1 first groove, V2 second groove, V3 third groove, W workpiece, W1 first workpiece, W2 second workpiece, WL lower surface of the first workpiece, WU upper surface of the second workpiece.

Claims

1. A friction stir welding tool, comprising: A shoulder having a shoulder surface that contacts a workpiece; And A probe protruding from the shoulder and rotatable about a first axis, On the outer peripheral surface of the probe, a helical groove portion and a chamfered portion are alternately formed in the circumferential direction of the probe, When the rotation direction of the probe is defined as a first rotation direction, the helical groove portion has a plurality of grooves that approach the shoulder surface as it goes toward the first rotation direction, On a part of the end surface of the front end portion of the probe, an inclined surface is formed, the inclined surface is connected to the chamfered portion, and approaches the shoulder surface as it goes toward the first rotation direction, The chamfered portion includes a first chamfered portion and a second chamfered portion, The inclined surface includes a first inclined surface, The front end portion of the probe has: A central plane through which the first axis passes; and A first stepped surface connecting the first inclined surface and the central plane, The first stepped surface is connected to the first inclined surface, the central plane, the first chamfered portion, and the second chamfered portion respectively.

2. The friction stir welding tool according to claim 1, wherein The end surface of the front end portion of the probe includes the central plane through which the first axis passes.

3. The friction stir welding tool according to claim 1, wherein The chamfered portion includes a first chamfered portion and a second chamfered portion, The inclined surface includes a first inclined surface, A first end portion of the first inclined surface is connected to the first chamfered portion, and a second end portion of the first inclined surface is connected to the second chamfered portion.

4. The friction stir welding tool according to claim 2, wherein The chamfered portion includes a first chamfered portion and a second chamfered portion, The inclined surface includes a first inclined surface, A first end portion of the first inclined surface is connected to the first chamfered portion, and a second end portion of the first inclined surface is connected to the second chamfered portion.

5. The friction stir welding tool according to claim 3, wherein The helical groove portion includes a first helical groove portion, When viewed in side view, the first helical groove portion is disposed in an inner region of a U-shaped portion formed by the first chamfered portion, the first inclined surface, and the second chamfered portion.

6. The friction stir welding tool according to claim 1, wherein The inclination angle of the inclined surface with respect to a plane perpendicular to the first axis is 1 degree or more and 30 degrees or less.

7. The friction stir welding tool according to claim 1, wherein When the direction from the front end portion of the probe toward the base end portion of the probe is defined as a first direction, When viewed in the direction along the first direction, the outer side edge of the inclined surface overlaps with the helical groove portion, The distance between the inner side edge of the inclined surface and the first axis is less than the distance between the innermost edge of the helical groove portion and the first axis.

8. The friction stir welding tool according to any one of claims 1 to 7, wherein At least one helical groove that moves away from the first axis as it goes toward the first rotation direction is formed on the shoulder surface.

9. The friction stir welding tool according to claim 2, wherein The end surface of the front end portion of the probe has the central plane and three of the inclined surfaces, When observed in the direction along the first axis, the end face of the front end portion of the probe has a substantially triangular shape. When observed in the direction along the first axis, the central face has a substantially hexagonal shape. When observed in the direction along the first axis, three sides of the substantially hexagonal shape define the boundary between the central face and the three inclined faces. When observed in the direction along the first axis, the other three sides of the substantially hexagonal shape define the boundary between the central face and the three chamfered portions.

10. A friction stir welding tool, comprising: a shoulder having a shoulder face that contacts a workpiece; a probe that projects from the shoulder and is rotatable about a first axis; and a stepped face that causes softened material to flow in a direction along the circumference of the probe, on the outer peripheral surface of the probe, a spiral groove portion and a chamfered portion are alternately formed in the circumferential direction of the probe, when the rotation direction of the probe is defined as a first rotation direction, the spiral groove portion has a plurality of grooves that approach the shoulder face as they face the first rotation direction, an inclined face is formed on a part of the end face of the front end portion of the probe, the inclined face is connected to the chamfered portion, and approaches the shoulder face as it faces the first rotation direction, the end face of the front end portion of the probe includes a central face through which the first axis passes, the inclined face is connected to the outer edge portion of the central face by means of the stepped face.

11. The friction stir welding tool according to claim 10, wherein the chamfered portion includes a first chamfered portion and a second chamfered portion, the inclined face includes a first inclined face, a first end portion of the first inclined face is connected to the first chamfered portion, and a second end portion of the first inclined face is connected to the second chamfered portion.

12. The friction stir welding tool according to claim 10 or 11, wherein at least one spiral groove that moves away from the first axis as it faces the first rotation direction is formed on the shoulder face.

13. The friction stir welding tool according to claim 10, wherein the end face of the front end portion of the probe has the central face and the three inclined faces, when observed in the direction along the first axis, the end face of the front end portion of the probe has a substantially triangular shape, when observed in the direction along the first axis, the central face has a substantially hexagonal shape, when observed in the direction along the first axis, three sides of the substantially hexagonal shape define the boundary between the central face and the three inclined faces, when observed in the direction along the first axis, the other three sides of the substantially hexagonal shape define the boundary between the central face and the three chamfered portions.

14. A friction stir welding apparatus, comprising: a friction stir welding tool; a workpiece support member that supports a workpiece; a tool holding member that holds the friction stir welding tool; a first driving device that relatively moves the tool holding member with respect to the workpiece support member; a second driving device that drives the probe of the friction stir welding tool to rotate about a first axis; and a control device that controls the first driving device and the second driving device, The friction stir welding tool includes: a shoulder having a shoulder surface that contacts the workpiece; the probe that projects from the shoulder and is rotatable about the first axis; and a stepped surface that causes the softened material to flow in a direction along the circumference of the probe, on the outer peripheral surface of the probe, a spiral groove portion and a chamfered portion are alternately formed in the circumferential direction of the probe, when the rotation direction of the probe is defined as the first rotation direction, the spiral groove portion has a plurality of grooves that approach the shoulder surface as it faces the first rotation direction, a slanted surface is formed on a part of the end surface of the front end portion of the probe, the slanted surface is connected to the chamfered portion, and approaches the shoulder surface as it faces the first rotation direction, the end surface of the front end portion of the probe includes a central surface through which the first axis passes, the slanted surface is connected to the outer edge portion of the central surface by means of the stepped surface.

15. A friction stir welding device, including: a friction stir welding tool; a workpiece support member that supports the workpiece; a tool holding member that holds the friction stir welding tool; a first driving device that relatively moves the tool holding member with respect to the workpiece support member; a second driving device that drives the probe of the friction stir welding tool to rotate about the first axis; and a control device that controls the first driving device and the second driving device, the friction stir welding tool includes: a shoulder having a shoulder surface that contacts the workpiece; and the probe that projects from the shoulder and is rotatable about the first axis, on the outer peripheral surface of the probe, a spiral groove portion and a chamfered portion are alternately formed in the circumferential direction of the probe, when the rotation direction of the probe is defined as the first rotation direction, the spiral groove portion has a plurality of grooves that approach the shoulder surface as it faces the first rotation direction, a slanted surface is formed on a part of the end surface of the front end portion of the probe, the slanted surface is connected to the chamfered portion, and approaches the shoulder surface as it faces the first rotation direction, the chamfered portion includes a first chamfered portion and a second chamfered portion, the slanted surface includes a first slanted surface, the front end portion of the probe has: a central surface through which the first axis passes; and a first stepped surface that connects the first slanted surface and the central surface, the first stepped surface is connected to the first slanted surface, the central surface, the first chamfered portion, and the second chamfered portion respectively.

16. A friction stir welding method using the friction stir welding device according to claim 14 or claim 15, including: a step of preparing the workpiece, the workpiece including a first workpiece and a second workpiece; a step of inserting the probe of the friction stir welding tool into the workpiece by relatively moving the friction stir welding tool with respect to the workpiece; a step of bringing the shoulder of the friction stir welding tool into contact with the upper surface of the workpiece by relatively moving the friction stir welding tool with respect to the workpiece; and a step of friction stir welding the first workpiece and the second workpiece by rotating the probe inserted into the workpiece about the first axis in the first rotation direction. The process of friction stir joining the first workpiece and the second workpiece includes: Using frictional heat generated by the relative rotation between the probe and the workpiece to form softened material from the workpiece; The multiple grooves of the spiral groove portion formed on the outer peripheral surface of the probe cause the softened material to flow downward; The chamfered portion formed on the outer peripheral surface of the probe causes the softened material to flow around the first axis in the first rotation direction; Guide the softened material from the chamfered portion to an inclined surface formed on a part of the end face of the front end portion of the probe; And The inclined surface causes the softened material to flow downward.

17. The friction stir joining method according to claim 16, wherein, The process of preparing the workpiece includes preparing the workpiece in a state where the lower surface of the first workpiece is in contact with the upper surface of the second workpiece, The process of friction stir joining the first workpiece and the second workpiece includes: Using frictional heat generated by the relative rotation between the probe and the first workpiece to form first softened material from the first workpiece; The multiple grooves of the spiral groove portion cause the first softened material to flow downward; The chamfered portion causes the first softened material to flow around the first axis in the first rotation direction; Guide the first softened material from the chamfered portion to the inclined surface; The inclined surface causes the first softened material to flow downward toward the second workpiece disposed below the first workpiece; And Mix the first softened material flowing downward by means of the inclined surface with second softened material formed from the second workpiece below the end face of the front end portion of the probe.

18. The friction stir joining method according to claim 17, wherein, After performing the process of inserting the probe of the friction stir joining tool into the workpiece, the upper end portion of the inclined surface is located above the boundary surface between the first workpiece and the second workpiece, and the lower end portion of the inclined surface is located below the boundary surface.

19. The friction stir joining method according to claim 16, wherein, The process of preparing the workpiece includes preparing the workpiece in a state where the side surface of the first workpiece is in contact with the side surface of the second workpiece, The process of friction stir joining the first workpiece and the second workpiece includes: Using frictional heat generated by the relative rotation between the probe and the first workpiece to form first softened material from the first workpiece, and using frictional heat generated by the relative rotation between the probe and the second workpiece to form second softened material from the second workpiece; The multiple grooves of the spiral groove portion cause the first softened material and the second softened material to flow downward; The chamfered portion causes the first softened material and the second softened material to flow around the first axis in the first rotation direction; In the area around the probe, form a mixed softened material formed by mixing the first softened material and the second softened material; Guide the mixed softened material from the chamfered portion to the inclined surface; and The inclined surface causes the mixed softened material to flow downward.

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