Friction stir welding tool and friction stir welding method

Abstract

The friction stir welding device is provided with a main body part and a stirring needle which protrudes in the axial direction from the center of one front end surface of the main body part, and friction stir welding is performed on the materials to be welded by generating friction heat by pressing the stirring needle against the materials to be welded while rotating the stirring needle. The front end surface of the main body part is provided with: an annular first surface which is connected with the root part of the stirring needle and extends towards the outer side in the radial direction; and a second surface which is connected to the outer peripheral edge of the first surface via the stepped portion and has a lower protruding height than the first surface. The main body part is provided with a cutting edge for cutting the surface of the joined member. In the cutting edge, the tip is disposed at a position in the radial direction of the outer peripheral edge of the first surface, and the protruding height at which the tip protrudes in the axial direction is equal to the protruding height of the outer peripheral edge of the first surface.

Description

TECHNICAL FIELD

[0001] The present application relates to a friction stir welding tool and a friction stir welding method. BACKGROUND

[0002] For example, as a joining method of joining a workpiece when a vehicle body is manufactured, there is a friction stir welding method (FSW: Friction Stir Welding) of joining a workpiece using friction heat. The friction stir welding method is a joining method of rotating a tool having a stir pin and moving the stir pin along a butted portion of the workpiece while pressing the stir pin against the butted portion. According to this, a high-strength joint in which deformation and strain of the workpiece are suppressed can be achieved without using a raw material other than the workpiece, by using heat input due to friction between the tool and the workpiece, plastic flow of the material, and stirring. When the friction stir welding is performed, burrs are generated by the material flowing to the outside of the tool since the tool is pressed against the workpiece. Therefore, in the next process of joining, the generated burrs are removed by cutting or grinding.

[0003] In Patent Literature 1, as a tool for the friction stir welding method, a friction stir welding tool is disclosed which is provided with a cutting edge assembled to a rotating member having a non-dissipative rotating stir pin, the cutting edge is rotated by the rotation of the rotating member and the non-dissipative rotating stir pin, and thereby the cutting edge performs cutting processing on the outside surface of the friction stir welding portion.

[0004] Further, in Patent Literature 2, a friction stir welding tool is shown which is provided with a burr removing tool which is screwed with a thread engraved on the outer periphery of a shaft portion in which a pin portion which is inserted into a workpiece member is provided, and a mounting nut which fixes the burr removing tool to the shaft portion by being screwed. In this friction stir welding tool, burrs generated on a weld portion of the workpiece member at the time of friction stir welding processing are removed by a cutting edge while the friction stir welding processing is performed.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent No. 3523983

[0008] Patent Literature 2: Japanese Patent No. 4774253 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] The tools described in Patent Documents 1 and 2 can remove burrs generated during friction stir welding using cutting edges. However, these tools use cutting edges attached to the outer periphery to cut the surfaces of the workpieces, resulting in a relatively wide weld bead, the remaining mark after welding. Furthermore, when the tool is tilted to achieve an advance angle during welding, the cutting edge digs deeper into the workpieces, leading to thinner walls.

[0011] Therefore, an object of the present invention is to provide a friction stir welding tool and a friction stir welding method that can satisfactorily join the welded materials and remove burrs while suppressing the width of the weld bead after joining.

[0012] Solutions to Problems

[0013] The present invention is constituted by the following structure.

[0014] (1) A friction stir welding tool comprising a columnar main body and a stirring needle projecting axially from the center of one front end surface of the main body, wherein the stirring needle is rotated and pressed against the abutting portions of mutually abutting workpieces to generate frictional heat, thereby friction stir welding the workpieces, wherein:

[0015] The front end surface of the main body has:

[0016] an annular first surface connected to the root of the stirring needle and extending radially outward; and

[0017] The second surface is connected to the outer peripheral edge of the first surface via a step portion and has a lower protrusion height than the first surface.

[0018] The main body is provided with a cutting edge for cutting the surface of the workpiece.

[0019] The cutting edge has a tip located at a radial position of the outer peripheral edge of the first surface, and a protruding height of the tip in the axial direction is equal to a protruding height of the outer peripheral edge of the first surface.

[0020] (2) A friction stir welding method using the friction stir welding tool described in (1), wherein:

[0021] butting the mutually joined parts together,

[0022] The stirring needle is pressed against the butt joint of the workpiece while the main body is rotated, and the stirring needle is relatively moved along the butt joint.

[0023] The workpieces are frictionally stirred by the generated frictional heat, and the surfaces of the workpieces are cut by the cutting edge.

[0024] Effects of the Invention

[0025] According to the present invention, it is possible to satisfactorily join the joined materials and remove burrs while suppressing the width of the weld bead after joining. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a side view of the friction stir welding tool.

[0027] Figure 2 This is a three-dimensional diagram of the main parts of the friction stir welding tool.

[0028] Figure 3 It is a side view of the front end portion of the friction stir welding tool.

[0029] Figure 4 This is a plan view of the front end portion of the friction stir welding tool as viewed from the axial direction.

[0030] Figure 5 It is an explanatory diagram for explaining the welding procedure of workpieces using a friction stir welding tool.

[0031] Figure 6 It is a diagram showing a joining state of the welded materials by the friction stir welding tool and is a side view when the welded materials are cut in a direction perpendicular to the butting portion.

[0032] Figure 7 It is a diagram showing a joining state of workpieces by a friction stir welding tool and is a side view of the workpieces when they are cut along the direction of the butting portion.

[0033] Figure 8 It is a top view of the front end portion of the friction stir welding tool of the reference example.

[0034] Figure 9 It is a diagram showing a joining state of workpieces by a friction stir welding tool according to a reference example, and is a schematic side view when the workpieces are cut in a direction perpendicular to the butting portion.

[0035] Figure 10 It is a diagram showing a joining state of workpieces by the friction stir welding tool according to the embodiment, and is a schematic side view when the workpieces are cut in a direction perpendicular to the butting portion.

[0036] Figure 11 It is a plan view showing the front end portion of the friction surface of the friction stir welding tool according to the embodiment. DETAILED DESCRIPTION

[0037] The following describes an embodiment of the present invention in detail with reference to the accompanying drawings. The friction stir welding tool of this embodiment is a tool that friction stir welds the workpieces by rotating the stirring pin while pressing it against the abutting portions of the abutting workpieces, thereby generating frictional heat. A specific structural example is shown below. It should be noted that the present invention is not limited to the structure shown below and can be modified as appropriate.

[0038] Friction stir welding tool structure

[0039] Figure 1 1 is a side view of the friction stir welding tool 100 . Figure 2 1 is a perspective view of a main part of the friction stir welding tool 100 .

[0040] The friction stir welding tool 100 of this embodiment includes a main body 11, a stirring pin 13, and a cutting edge 33 provided on the main body 11. The main body 11 is formed into a columnar shape obtained by cutting off a part of a cylindrical shape using a mounting surface 31 described later. Figure 1 、 Figure 2 A stirring needle 13 is provided on the front end surface of the stirring needle 13 so as to protrude in the axial direction. The stirring needle 13 is in the shape of a cylinder coaxial with the outer circumference of the main body 11, and has a spiral protrusion 19 formed on the outer circumference. A shoulder 15 is provided at the root portion of the stirring needle 13. The front end surface constituting the shoulder 15 has a first surface 23 and a second surface 25. The first surface 23 and the second surface 25 are respectively arranged in a concentric circle shape with the main body 11 when viewed from above in the axial direction of the main body 11.

[0041] On the other side of the main body 11 ( Figure 1 、 Figure 2 A shank 17 is integrally provided with the main body 11 on one side (above the main body 11). The shank 17 is supported by a motor (not shown) for driving the friction stir welding tool 100 in the rotational direction Rt. It should be noted that, in place of the shank 17, the main body 11 may have a tapered inner circumferential surface for securing the tapered shaft, or a known tool securing mechanism may be employed.

[0042] In this specification, the needle 13 side along the axial direction of the main body 11 is sometimes referred to as the “front” and the handle 17 side is sometimes referred to as the “rear”.

[0043] Figure 3The figure is a side view showing the front end portion of the friction stir welding tool 100 using a partial cross-section. The first surface 23 of the main body 11 is an annular surface connected to the root of the stirring pin 13 and extending radially outward. In addition, the first surface 23 can be set to any shape in the axial cross-section of the main body 11, but in the present embodiment, it is set to a shape that tends to be radially inward and inclined toward the rear end of the stirring pin 13. That is, the first surface 23 is inclined in such a manner that the axial protrusion height becomes lower as it approaches the axis Ax of the center of the stirring pin, and a concave groove portion 23a is formed at the root portion on the rear side of the stirring pin 13.

[0044] The second surface 25 is connected to the outer periphery of the first surface 23 via a step 27, and its axial projection height is lower than that of the first surface 23. The step 27 connects the outer periphery of the first surface 23 to the inner periphery of the second surface 25, and allows the second surface 25 to project lower than the outer periphery of the first surface 23. The second surface 25 is provided so as to surround the outer periphery of the first surface 23 and is formed as a flat surface perpendicular to the axis Ax in cross-section. In addition to being a flat surface, the second surface 25 may also be a tapered or curved surface forming a concave groove, similar to the first surface 23.

[0045] In addition, the main body 11 has a mounting surface 31 provided with a cutting edge 33. The mounting surface 31 can be set to any shape. Figure 2 As shown, the flat, thinned surface is formed by radially thinning a portion of the cylindrical circumference of the main body 11. Specifically, the mounting surface 31 is formed by removing a portion of the circumference of the main body 11 and is a flat surface along the axis Ax. This allows the cutting edge 33 to be positioned closer to the axial center of the main body 11 in this embodiment.

[0046] Figure 4 This is a top view of the front end portion of the friction stir welding tool 100 as viewed from the axial direction. Figure 4 As shown, the mounting surface 31 is formed by a surface passing through a tangent line of the step portion 27 formed on the outer peripheral edge of the first surface 23. Therefore, a portion of the second surface 25 is cut off by the mounting surface 31.

[0047] The cutting edge 33 is plate-shaped as a whole, and the cutting edge 33 is fixed so that one surface thereof contacts the mounting surface 31. The tip 35 of the cutting edge 33 is arranged in front of the rotation direction Rt, and Figure 4 As shown in FIG, the second surface 25 is formed to extend radially with a width substantially equal to the radial width of the second surface 25. Figure 3As shown, the protruding height of the blade tip 35 in the axial direction is equal to the protruding height of the outer peripheral edge of the first surface 23. The "equal height" mentioned here means that the blade tip 35 is arranged at the same height or approximately the same height position as the outer peripheral edge of the first surface 23 in the axial direction. The height position may be offset within a range that does not affect the cutting of burrs described later.

[0048] like Figure 1 As shown in FIG. 1 and FIG. 2 , the cutting edge 33 has two fixing insertion holes 37, for example, formed by countersinking. Furthermore, threaded holes (not shown) are formed on the mounting surface 31 of the main body 11 at positions corresponding to the fixing insertion holes 37. The cutting edge 33 overlaps the mounting surface 31, and fastening members 39, such as bolts, are inserted into each fixing insertion hole 37 and screwed into the threaded holes formed in the mounting surface 31, thereby fastening the cutting edge 33 to the main body 11. This fastening method is merely an example; an appropriate mechanism for adjusting the position of the cutting edge 35 may also be provided.

[0049] Friction stir welding steps

[0050] Next, a description will be given of a procedure for friction stir welding in which the materials to be welded are joined together using the friction stir welding tool described above.

[0051] Figure 5 1 and 2 are explanatory diagrams illustrating the steps of joining the workpieces 41 and 43 using the friction stir welding tool 100. First, the two workpieces 41 and 43 are butted together to form a butted portion 45. Examples of the workpieces 41 and 43 to be joined include aluminum alloy plates.

[0052] Figure 6 1 is a diagram showing a state of joining of the welded materials 41 and 43 by the friction stir welding tool 100 , and is a side view when the welded materials 41 and 43 are cut in a direction perpendicular to the butting portion 45 . Figure 7 1 is a diagram showing a state of joining of the welded materials 41 and 43 by the friction stir welding tool 100 , and is a side view of the welded materials 41 and 43 when they are cut in a direction along the butting portion 45 .

[0053] Next, if Figure 6 as well as Figure 7 As shown, the main body 11 of the friction stir welding tool 100 is rotated and the pin 13 is pressed against the abutting portion 45 from one surface side of the welded materials 41 and 43 , thereby generating frictional heat.

[0054] Then, the friction stir welding tool 100 is moved in a moving direction Y (see FIG. 1 ) along one direction of the butting portion 45 while the main body 11 is rotated. Figure 5 as well as Figure 7At this time, the friction stir welding tool 100 moves with an advance angle of an inclination angle θ toward the rear side of the moving direction Y relative to the vertical direction of the plate surface of the workpieces 41 and 43 (refer to Figure 7 That is, the friction stir welding tool 100 is tilted at an inclination angle θ toward the rear side in the welding direction with respect to the normal direction of the surfaces of the welded materials 41 and 43 facing the friction stir welding tool 100 .

[0055] In this way, when the rotating stirring pin 13 is pressed and pressed into the abutting portion 45 of the workpieces 41 and 43, and the rotating stirring pin 13 is moved in the moving direction Y along the abutting portion 45, the workpieces 41 and 43 are frictionally stirred by generating friction heat in the abutting portion 45 under the action of the stirring pin 13 of the friction stir welding tool 100 and the first surface 23 in contact with the workpieces 41 and 43. As a result, the workpieces 41 and 43 are joined to each other in the abutting portion 45.

[0056] At this time, in the friction stir welding tool 100, the plastic fluid of the workpieces 41 and 43 that plastically flows under the action of the stirring pin 13 is temporarily retained by the groove portion 23a of the first surface 23 and overflows to the outer periphery of the first surface 23. Moreover, in the second surface 25 on the outer periphery of the first surface 23, the space between the second surface 25 and the workpieces 41 and 43 is filled with the plastic fluid that overflows to the outer periphery of the first surface 23. Therefore, in the shoulder portion 15, even on the outer periphery of the first surface 23, the second surface 25 and the plastic fluid come into contact, generating frictional heat.

[0057] Thus, in the friction stir welding tool 100 , even if the first surface 23 having the groove portion 23 a has a small diameter, sufficient heat input is obtained by heat generation in the second surface 25 , and friction stir welding is performed well.

[0058] In addition, in the friction stir welding tool 100, when joining the workpieces 41 and 43, the surfaces of the workpieces 41 and 43 are cut by the tip 35 of the cutting edge 33 mounted on the mounting surface 31 of the main body 11. As a result, the burrs formed by the plastic flow produced by the friction stirring performed by the stirring needle 13 are removed as cutting chips. As a result, the joint body in which the workpieces 41 and 43 are joined to each other by the butt joint 45 is formed with a weld bead B (see FIG. 1 ) which is a mark formed by the removal of the burrs by the cutting edge 33. Figure 5 ).

[0059] Furthermore, the plastic fluid overflowing from the first surface 23 is flattened by the flat second surface 25, so the height of the plastic fluid in contact with the cutting edge 33 is constant. Therefore, the cutting depth of the cutting edge 33 is constant, enabling stable cutting.

[0060] Note that the friction stir joining tool 100 and the members to be joined 41, 43 can be configured to move relative to each other in addition to the configuration in which one is fixed and the other is moved.

[0061] <Comparison with Reference Example>

[0062] Here, the friction stir joining tool 200 of the reference example is described, and the friction stir joining tool 100 of the present embodiment is compared with the friction stir joining tool 200 of the reference example.

[0063] Figure 8 is a plan view of the front end portion of the friction stir joining tool 200 of the reference example. Figure 9 is a diagram showing the joining state of the members to be joined 41, 43 by the friction stir joining tool 200 of the reference example, and is a schematic side view when the members to be joined 41, 43 are cut in a direction orthogonal to the butting portion 45. Figure 10 is a diagram showing the joining state of the members to be joined 41, 43 by the friction stir joining tool 100 of the present embodiment, and is a schematic side view when the members to be joined 41, 43 are cut in a direction orthogonal to the butting portion 45. Figure 11 is a plan view of the front end portion of the friction stir joining tool 100 of the present embodiment.

[0064] As shown in Figure 8 , the friction stir joining tool 200 of the reference example includes a main body portion 55 having a stir pin 53 at the front end surface of the shoulder portion 51, and a cutting edge 59 having a blade tip 57 is provided on the outer periphery of the main body portion 55. In the friction stir joining tool 200 of the reference example, when joining the members to be joined 41, 43, the surface of the members to be joined 41, 43 is cut by the cutting edge 59 provided on the outer periphery of the main body portion 55, and burrs composed of a plastic flow generated by the action of friction stir by the stir pin 53 are cut.

[0065] The friction stir joining tool 200 of the reference example cuts the surface of the members to be joined 41, 43 by the cutting edge 59 provided on the outer periphery, and thus a weld bead B having a large machining width W is formed. Further, the cutting edge 59 is provided on the outer periphery of the main body portion 55, and thus the amount of penetration of the cutting edge 59 into the members to be joined 41, 43 increases in the case of performing friction stir joining with an advancing angle composed of the inclination angle θ. As a result, the wall thickness of the members to be joined 41, 43 is reduced due to the penetration of the cutting edge 59 into the members to be joined 41, 43.

[0066] In contrast, in the friction stir welding tool 100 of the present embodiment, the cutting edge 33 for removing burrs by cutting is provided in the area of ​​the second surface 25 and the blade tip 35 is arranged at a height position substantially the same as the outer diameter portion of the first surface 23. Therefore, even if friction stir welding is performed with an advance angle consisting of an inclination angle θ, the amount of biting of the cutting edge 33 into the workpieces 41, 43 can be suppressed. Thus, the thinning of the workpieces 41, 43 caused by the biting of the cutting edge 33 into the workpieces 41, 43 can be suppressed. In addition, in the present embodiment, the mounting surface 31 is a flat thinning surface formed by radially thinning a portion of the cylindrical circumferential surface of the main body 11. Therefore, the cutting edge 33 can be brought closer to the axial center side of the main body 11, thereby reducing the width of the processing mark (processing width W, refer to FIG. 1 ) along the docking portion 45 of the workpieces 41, 43. Figure 5 ).

[0067] In addition, if Figure 9 As shown, when friction stir welding is performed on workpieces 41 and 43 of different thicknesses to create a tailor-welded blank having portions of different thicknesses, the friction stir welding tool 200 is tilted in a direction perpendicular to the moving direction relative to the butting portion 45, and the stirring pin 53 is pressed in. Therefore, in this case, the cutting edge 59 bites more deeply into the workpiece 41 on the tilted side of the friction stir welding tool 200, and the wall thickness of the workpiece 41 becomes thinner.

[0068] In contrast, according to the friction stir welding tool 100 of this embodiment, Figure 10 As shown, even when the friction stir welding tool 100 is tilted toward the abutting portion 45 of the workpieces 41 and 43 having different plate thicknesses, that is, the stirring needle 13 is tilted and pressed toward the workpiece 41 on the thinner side in a plane perpendicular to the direction of relative movement of the friction stir welding tool 100 and the workpieces 41 and 43, the amount of bite of the cutting edge 33 into the workpiece 41 on the tilted side of the friction stir welding tool 100 can be suppressed. Therefore, the thinning of the workpiece 41 can be suppressed.

[0069] Here, the amount of heat input Q [W] to the friction stir portion during friction stir welding is expressed by the following formula (1).

[0070] [Formula 1]

[0071]

[0072] in,

[0073] μ: friction coefficient

[0074] P: Pressure at the friction stirring site [N / m 3 ]

[0075] N: Tool speed [S -1 ]

[0076] R: Shoulder radius [m]

[0077] As shown in the above formula (1), the heat input amount Q to the friction stir portion during friction stir welding is greatly affected by the radius R of the shoulder of the friction stir welding tool (tool). As the contact area with the workpieces increases, the heat input amount Q also increases.

[0078] In the friction stir welding tool 200 of the reference example, the surface Sb ( Figure 8 The oblique line portion in the figure) becomes the friction surface in contact with the workpieces 41 and 43. On the other hand, in the friction stir welding tool 100 of this embodiment, as shown in FIG. Figure 11 As shown, the surface Sa ( Figure 11 The oblique line portion in the figure) becomes the friction surface in contact with the joined parts 41 and 43.

[0079] When the surface Sa, which serves as the friction surface, of the friction stir welding tool 100 of the present embodiment has the same diameter as the surface Sb, which serves as the friction surface, of the friction stir welding tool 200 of the reference example, the surface Sa is smaller than the surface Sb by the amount by which the mounting surface 31 is formed. However, the reduction in the surface Sa, which serves as the friction surface, is a small amount, such as that obtained by removing a portion of the peripheral surface of the main body 11. Therefore, the surface Sa, which serves as the friction surface, has a sufficient area as a friction surface to obtain the heat input required for satisfactory friction stirring.

[0080] It should be noted that the cutting edge 33 is preferably axially adjustable relative to the main body 11. In this case, the cutting edge 33 can be adjusted in position according to the material of the workpieces 41 and 43, and the rake angle and relief angle of the blade tip 35 can be adjusted.

[0081] Thus, the present invention is not limited to the above-mentioned embodiments, and the combination of the various structures of the embodiments, changes and applications made by those skilled in the art based on the description in the specification and well-known technologies are also intended by the present invention and included in the scope of protection requested.

[0082] As described above, the following matters are disclosed in this specification.

[0083] (1) A friction stir welding tool comprising a columnar main body and a stirring needle projecting axially from the center of one front end surface of the main body, wherein the stirring needle is rotated and pressed against the abutting portions of mutually abutting workpieces to generate frictional heat, thereby friction stir welding the workpieces, wherein:

[0084] The front end surface of the main body has:

[0085] an annular first surface connected to the root of the stirring needle and extending radially outward; and

[0086] The second surface is connected to the outer peripheral edge of the first surface via a step portion and has a lower protrusion height than the first surface.

[0087] The main body is provided with a cutting edge for cutting the surface of the workpiece.

[0088] The cutting edge has a tip located at a radial position of the outer peripheral edge of the first surface, and a protruding height of the tip in the axial direction is equal to a protruding height of the outer peripheral edge of the first surface.

[0089] According to the friction stir welding tool, when joining the workpieces, the tip of the cutting edge provided on the main body can be used to cut the surface of the workpieces. Thus, the burrs formed by the plastic fluid produced by the friction stirring performed by the stirring needle can be cut and removed. In addition, the cutting edge for removing the burrs is provided in the area of ​​the second surface and the tip of the cutting edge is arranged at a height position equal to the outer diameter portion of the first surface. Therefore, even if friction stir welding is performed with an advance angle, the amount of the cutting edge biting into the workpieces can be suppressed. Thus, the thinning of the workpieces caused by the biting of the cutting edge into the workpieces can be suppressed. Moreover, the surface including not only the first surface but also the second surface can become a friction surface in contact with the workpieces, so that the heat input amount for performing friction stirring well can be obtained.

[0090] (2) The friction stir welding tool according to (1), wherein:

[0091] The first surface forms a concave groove portion in which the protrusion height decreases as it approaches the base of the stirring pin.

[0092] In this friction stir welding tool, the overflowing plastic fluid, temporarily retained by the first surface having the groove, is flattened by the second surface, which is formed of a flat surface. This ensures a constant height of the plastic fluid in contact with the cutting edge. Consequently, the cutting edge maintains a constant penetration depth, enabling stable cutting.

[0093] (3) The friction stir welding tool according to (1), wherein

[0094] The main body has a shank on the axially opposite side of the front end surface.

[0095] This friction stir welding tool can be easily mounted on various machine tools.

[0096] (4) The friction stir welding tool according to (1), wherein

[0097] The main body has a shape having a thinned surface formed by thinning a portion of the cylindrical circumference in the radial direction.

[0098] The cutting edge is fixed to the thinning surface.

[0099] According to this friction stir welding tool, the cutting edge does not protrude significantly outward in the radial direction of the main body portion, and thus thinning of the welded materials during welding can be suppressed.

[0100] (5) A friction stir welding method using the friction stir welding tool described in any one of (1) to (4), wherein:

[0101] butting the mutually joined parts together,

[0102] The stirring needle is pressed against the butt joint of the workpiece while the main body is rotated, and the stirring needle is relatively moved along the butt joint.

[0103] The workpieces are frictionally stirred by the generated frictional heat, and the surfaces of the workpieces are cut by the cutting edge.

[0104] According to this friction stir welding method, when joining the workpieces, the surface of the workpieces can be cut using the tip of the cutting edge provided on the main body. As a result, burrs formed by the plastic fluid produced by the friction stirring performed by the stirring needle can be cut and removed. In addition, the cutting edge for removing the burrs is provided in the area of ​​the second surface and the tip is arranged at a height position equal to that of the outer diameter portion of the first surface, close to the center side of the main body. Therefore, the processing width of the weld bead, which is a processing mark along the butt joint of the workpieces, can be reduced. Moreover, by setting the surface including not only the first surface but also the second surface as the friction surface in contact with the workpieces, the heat input amount for performing friction stirring well can be obtained.

[0105] (6) The friction stir welding method according to (5), wherein:

[0106] When the friction stir welding tool and the workpieces are relatively moved along the abutting portion, the friction stir welding tool is tilted rearward in the welding direction with respect to the normal direction of the surface of the workpieces facing the friction stir welding tool.

[0107] According to this friction stir welding method, by tilting the friction stir welding tool from the normal direction of the workpieces toward the rear side in the welding direction, internal defects generated during friction stir welding can be suppressed, thereby suppressing a decrease in welding strength.

[0108] (7) The friction stir welding method according to (6), wherein:

[0109] When the thicknesses of the welded materials are different from each other, the friction stir welding tool is tilted toward the welded material having a thinner wall in a plane perpendicular to the direction of relative movement.

[0110] According to this friction stir welding method, when welding welded materials having different thicknesses, the amount of cutting edge engagement with the thinner welded material where the friction stir welding tool is tilted can be reduced, thereby suppressing thinning of the welded materials.

[0111] It should be noted that this application is based on Japanese patent application (Japanese Patent Application No. 2023-037670) filed on March 10, 2023, the contents of which are incorporated herein by reference.

[0112] Description of Reference Numerals

[0113] 11 Main body

[0114] 13 stirring needle

[0115] 17 handle

[0116] 23 Page 1

[0117] 23a groove portion

[0118] 25 Side 2

[0119] 33 cutting edges

[0120] 35 blade tip

[0121] 41, 43 Joined parts

[0122] 45 docking part

[0123] 100 Friction Stir Welding Tools.

Claims

1. A friction stir welding tool comprising a columnar main body and a stirring pin protruding axially from the center of one front end surface of the main body, wherein the stirring pin is rotated and pressed against the abutting portions of mutually abutting workpieces to generate frictional heat, thereby friction stir welding the workpieces, wherein: The front end surface of the main body has: an annular first surface connected to the root of the stirring needle and extending radially outward; and The second surface is connected to the outer peripheral edge of the first surface via a step portion and has a lower protrusion height than the first surface. The main body is provided with a cutting edge for cutting the surface of the workpiece. The cutting edge has a tip located at a radial position of the outer peripheral edge of the first surface, and a protruding height of the tip in the axial direction is equal to a protruding height of the outer peripheral edge of the first surface.

2. The friction stir welding tool according to claim 1, wherein: The first surface forms a concave groove portion in which the protrusion height decreases as it approaches the base of the stirring pin.

3. The friction stir welding tool according to claim 1, wherein The main body has a shank on the axially opposite side of the front end surface.

4. The friction stir welding tool according to claim 1, wherein The main body has a shape having a thinned surface formed by thinning a portion of the cylindrical circumference in the radial direction. The cutting edge is fixed to the thinning surface.

5. A friction stir welding method using the friction stir welding tool according to any one of claims 1 to 4, wherein: butting the mutually joined parts together, The stirring needle is pressed against the butt joint of the workpiece while the main body is rotated, and the stirring needle is relatively moved along the butt joint. The workpieces are frictionally stirred by the generated frictional heat, and the surfaces of the workpieces are cut by the cutting edge.

6. The friction stir welding method according to claim 5, wherein: When the friction stir welding tool and the workpiece are relatively moved along the butting portion, The friction stir welding tool is tilted toward the rear side in the welding direction with respect to the normal direction of the surface of the welded materials that faces the friction stir welding tool.

7. The friction stir welding method according to claim 6, wherein: When the thicknesses of the welded materials are different from each other, the friction stir welding tool is tilted toward the welded material having a thinner wall in a plane perpendicular to the direction of relative movement.

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