Manufacturing method for joined body

Abstract

To provide a manufacturing method for a joined body that can suppress occurrence of burr and occurrence of defect of a joined part and reduce loads that are applied to a rotary tool and a joining device.SOLUTION: A manufacturing method for a joined body includes a first friction stir joining step of performing friction stirring to a first joint range extending from one end side of a route for joining to a first point provided on the middle of the route for joining, and a second friction stir joining step of performing friction stirring to a second joint range extending from a second point provided on a plasticized region belonging to the first joint range. The second friction stir joining step comprises: an inserting step of inserting a stirring pin into a member to be joined, while rotating a rotary tool F in a direction same as a forming direction of a screw groove; a changing step of changing a rotating direction of the rotary tool F so that tool is rotated in the opposite direction of the forming direction of the screw groove; and a joining step of joining the member to be joined, while rotating the rotary tool F in the opposite direction of the forming direction of the screw groove, in this order, at a starting position SP22 for friction stirring.SELECTED DRAWING: Figure 23

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a joined body.

Background Art

[0002] A method for manufacturing a joined body is known in which friction stir welding of a member to be joined is performed using a rotary tool having a stirring pin formed with spiral grooves. Normally, when the spiral grooves are formed in a left-handed (left screw) direction from the base end to the tip end, the rotary tool is rotated clockwise to insert the stirring pin into the member to be joined, and friction stir welding is performed. On the other hand, when the spiral grooves are formed in a right-handed (right screw) direction from the base end to the tip end, the rotary tool is rotated counterclockwise to insert the stirring pin into the member to be joined, and friction stir welding is performed. That is, the rotary tool is rotated in the direction opposite to the formation direction of the spiral grooves (hereinafter, this mode is referred to as "forward rotation"), and the stirring pin is inserted into the member to be joined to perform friction stir welding (Patent Document 1).

[0003] By performing friction stir welding in forward rotation, the material of the plastically fluidized member to be joined can be guided to the tip side of the stirring pin. As a result, by increasing the plastic flow around the tip portion, joining in the deep portion of the joined portion can be stably performed, and a sound joined portion can be formed. In addition, the amount of metal overflowing outside the member to be joined can be reduced.

[0004] Conventionally, friction stir welding has also been performed by rotating the rotary tool in the same direction as the formation direction of the spiral grooves (hereinafter, this mode is referred to as "reverse rotation") and inserting the stirring pin into the member to be joined (Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] When performing friction stir welding by rotating forward (the direction of formation of the spiral groove is opposite to the rotation direction of the rotating tool) as described in Patent Document 1, plastic flow of the workpiece occurs due to contact between the stirring pin and the workpiece, and as the stirring pin is inserted, the material of the workpiece that has been plasticized according to the volume of the stirring pin overflows outside the workpiece. When the plasticized material of the workpiece that has overflowed in this way solidifies, there is a problem that a large amount of burrs are generated on the surface of the workpiece after joining.

[0007] Also, when performing friction stir welding by rotating forward, since friction stirring is performed by pressing the plasticized material of the workpiece toward the tip side of the stirring pin, there is a risk that the load on the joining device that rotates the rotating tool will increase. In addition, when the hardness of the workpiece is relatively high, the rotating tool may be damaged. Further, when the stirring pin is inserted by rotating forward in a state where two workpieces are overlapped and friction stir welding is performed, convection of the plasticized material of the workpiece occurs, and the oxide film of the workpiece existing on the overlapping surface (overlapping portion) may be lifted up, resulting in defects in the joined portion.

[0008] On the other hand, when performing friction stir welding by rotating backward (the direction of formation of the spiral groove is the same as the rotation direction of the rotating tool) as described in Patent Document 2, it is said that excessive upward convection and interface entrainment occurring in the plasticized region can be suppressed. However, in this case, the material may be insufficient at the position on the tip side of the stirring pin, and defects may occur inside.

[0009] From such a viewpoint, an object of the present invention is to provide a method for manufacturing a joined body that suppresses the generation of burrs and defects in the joined portion and reduces the load applied to the rotating tool and the joining device.

Means for Solving the Problems

[0010] (1) A method for manufacturing a joined body by friction stir welding of joined members to a joining path between them using a rotary tool having a stirring pin with a spiral groove, comprising: a first friction stir welding step of performing friction stir welding on a first joining range from one end side of the joining path to a first point provided up to the middle of the joining path; and a second friction stir welding step of performing friction stir welding on a second joining range from a second point provided within a plasticized region belonging to the first joining range formed by the first friction stir welding step to the other end side of the joining path. In the first friction stir welding step, the start position of the friction stir welding for the first joining range is set at one end side of the joining path of the joined members, and the end position of the first joining range is set as the first point provided in the middle of the joining path. In the second friction stir welding step, the start position of the friction stir welding for the second joining range is set at a point at the end of the plasticized region belonging to the first joining range, the end position of the friction stir welding for the second joining range is set at the other end side of the joining path opposite to the one end side, and friction stir welding is performed from the start position for the second joining range toward one end side of the joining path up to a turning-back position set in the plasticized region belonging to the first joining range, then turned back from the turning-back position and friction stir welding of the plasticized region is performed toward the other end side of the joining path, and then friction stir welding of the remaining joining path is performed from the start position for the second joining range again through to the end position for the second joining range. In the second friction stir welding step, at the start position of the friction stir welding for the second joining range, an insertion step of inserting the stirring pin into the joined members with the rotary tool rotated in the same direction as the formation direction of the spiral groove, a changing step of changing the rotation direction of the rotary tool to rotate in the opposite direction to the formation direction of the spiral groove, and a joining step of joining the joined members with the rotary tool rotated in the opposite direction to the formation direction of the spiral groove are provided in sequence. A method for manufacturing a joined body, characterized by the above. (2) The method for manufacturing a joined body according to (1), wherein in the second friction stir welding step, the start position of the friction stir welding for the second joining range is the position of the punched hole formed by the first friction stir welding step. (3) In the first friction stir welding process, the relationship between the insertion depth H11 of the rotating tool at the steady state part when performing friction stir welding on the first welding range and the insertion depth H12 of the rotating tool near the end position in the first friction stir welding process is H11 × 0.6 ≦ H12 < H11. The method for manufacturing a joined body according to (1) above. (4) In the first friction stir welding process, the relationship between the insertion depth H12 of the rotating tool near the end position and the insertion depth H21 of the rotating tool when inserting the stirring pin at the start position in the second friction stir welding process is H12 < H21 ≦ H12 × 1.7. The method for manufacturing a joined body according to (1) above. (5) In the second friction stir welding process, the relationship between the insertion depth H21 of the rotating tool when inserting the stirring pin at the start position and the insertion depth H22 of the rotating tool at the steady state part when performing friction stir welding on the second welding range in the second friction stir welding process is H22 < H21 ≦ H22 × 1.4. The method for manufacturing a joined body according to (1) above. (6) The rotational speed of the rotating tool in the insertion process is equal to or higher than the rotational speed of the rotating tool in the joining process. The method for manufacturing a joined body according to (1) above. (7) The relationship between the rotational speed N1 of the rotating tool in the insertion process and the rotational speed N2 of the rotating tool in the joining process is N2 ≦ N1 ≦ N2 × 5. The method for manufacturing a joined body according to (6) above. (8) Further comprising a pulling-up process of pulling up the rotating tool in the surface direction of the member to be joined after the insertion process, and performing the changing process after the pulling-up process. The method for manufacturing a joined body according to (1) above. (9) The relationship between the insertion depth H1 of the rotating tool in the insertion process and the pulling-up amount H2 in the pulling-up process is H1 × 0.01 ≦ H2 ≦ H1 × 0.5. The method for manufacturing a joined body according to (8) above. (10) Further comprising a pushing-in process of pushing the rotating tool in the depth direction of the member to be joined after the changing process, and performing the joining process after the pushing-in process. The method for manufacturing a joined body according to (1) above. (11) The method for manufacturing the joined body according to (10) above, wherein the relationship between the insertion depth H1 of the rotary tool in the insertion step and the insertion amount H3 in the pressing step is H1 × 0.01 ≤ H3 ≤ H1 × 0.5. (12) The method for manufacturing the joined body according to (10) above, wherein the relationship between the insertion depth H1 of the rotary tool in the insertion step and the insertion depth H4 at the start of joining in the joining step is H1 × 1.01 ≤ H4 ≤ H1 × 1.5. (13) The rotary tool has a flat or mortar-shaped lower end surface and further has a shoulder portion having a columnar or bolster shape. The stirring pin hangs down from the lower end surface of the shoulder portion. While bringing the shoulder portion into contact with the joined member and inserting the stirring pin into the joined member, friction stir joining is performed on the joined member, according to the method for manufacturing the joined body described in (1) above. (14) The method for manufacturing the joined body according to (13) above, wherein the relationship between the insertion depth H1 of the rotary tool in the insertion step and the length L1 of the stirring pin is L1 × 0.5 ≤ H1 ≤ L1. (15) The rotary tool has a base portion having a columnar or bolster shape. The stirring pin hangs down from the lower end surface of the base portion. While separating the base portion from the joined member and inserting only the stirring pin into the joined member, friction stir joining is performed on the joined member, according to the method for manufacturing the joined body described in (1) above. (16) The rotary tool has a base portion having a columnar or bolster shape. The stirring pin has a proximal-side pin continuous with the base portion and a distal-side pin continuous with the proximal-side pin. The taper angle of the proximal-side pin is larger than the taper angle of the distal-side pin. A stepped pin step portion is formed on the outer peripheral surface of the proximal-side pin. While bringing the outer peripheral surface of the proximal-side pin into contact with the surface of the joined member, friction stir joining is performed on the joined member, according to the method for manufacturing the joined body described in (1) above. (17) The method for manufacturing the joined body according to (1) above, further comprising a pilot hole forming step of forming a pilot hole in the joined member before the insertion step, and inserting the stirring pin into the pilot hole in the insertion step. (18) The joined member consists of a first joined member and a second joined member having a lower hardness than the first joined member, and at least one end surface of either the first joined member or the second joined member is butted to form a butted portion, or the back surface of the second joined member is overlapped on the surface of the first joined member to form an overlapping portion. In the insertion step, a stirring pin is inserted from the surface of the first joined member, and in the joining step, friction stir joining of the butted portion or the overlapping portion is performed. The method for manufacturing the joined body according to (1). (19) The joined member consists of a first joined member and a second joined member, and at least one end surface of either the first joined member or the second joined member is butted to form a butted portion, or the back surface of the second joined member is overlapped on the surface of the first joined member to form an overlapping portion. In the insertion step, a stirring pin is inserted toward the butted portion or the overlapping portion. The method for manufacturing the joined body according to (1).

Effect of the Invention

[0011] According to the method for manufacturing the joined body of the present invention, the generation of burrs and the generation of defects in the joined portion can be suppressed, and the load applied to the rotary tool and the joining device can be reduced.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] Embodiments of the present invention will be described with reference to the drawings as appropriate. The present invention is not limited to only the following embodiments. Also, the constituent elements in the embodiments and modification examples can be partially or wholly combined as appropriate.

[0014] [1. First Embodiment] [1-1. Members to be Joined and Joined Body] As shown in FIG. 1, a liquid-cooling jacket (joined body) 1 according to the first embodiment of the present invention is composed of a jacket body (first member to be joined) 2 and a sealing body (second member to be joined) 3. The liquid-cooling jacket 1 is a device that circulates a fluid inside to cool a heat-generating body to be arranged. The jacket body 2 and the sealing body 3 are integrated by friction stir welding. In the following description, the "surface" means the surface on the opposite side of the "back surface".

[0015] The jacket body (first member to be joined) 2 is mainly composed of a bottom portion 10 and a peripheral wall portion 11. The jacket body 2 is not particularly limited as long as it is a metal capable of friction stirring, but in this embodiment, it is mainly formed containing a first aluminum alloy. As the first aluminum alloy, for example, an aluminum alloy casting material such as JISH5302 ADC12 (Al - Si - Cu system) is used.

[0016] The bottom portion 10 is a plate-like member having a rectangular shape. The peripheral wall portion 11 is a wall portion rising in a rectangular frame shape from the peripheral edge portion of the bottom portion 10. A recess 13 that is open upward is formed by the bottom portion 10 and the peripheral wall portion 11. A peripheral wall step portion 12 is formed on the inner peripheral edge of the peripheral wall portion 11. The peripheral wall step portion 12 is composed of a step bottom surface 12a and a step side surface (side surface) 12b that rises vertically from the step bottom surface 12a.

[0017] Note that although the jacket body 2 of this embodiment is integrally formed, for example, the peripheral wall portion 11 may be divided and joined with a sealing member to be integrated.

[0018] The sealing body (second member to be joined) 3 is a plate-like member that seals the opening of the jacket body 2. The sealing body 3 is not particularly limited as long as it is a metal capable of friction stirring, but in this embodiment, it is mainly formed of a second aluminum alloy. The second aluminum alloy is a material with a lower hardness than the first aluminum alloy. The second aluminum alloy is formed of, for example, aluminum alloy rolled materials such as JIS A1050, A1070, A1100, and A6063.

[0019] [1-2. Manufacturing method] Next, a manufacturing method of the liquid-cooled jacket according to this embodiment (manufacturing method of the joined body, joining method of the members to be joined) (hereinafter, may be referred to as "this method") will be described. In the manufacturing method of the liquid-cooled jacket according to this embodiment, a preparation step, a butting step, an insertion step, a pulling-up step, a changing step, a pushing step, and a joining step are performed.

[0020] In this method, as shown in FIG. 2, with the sealing body 3 placed on the jacket body 2 and the side surfaces butted against each other, friction stir joining of the jacket body 2 and the sealing body 3 is performed. As shown in FIG. 3, in this method, at the end surface 11a of the peripheral wall portion 11, a start position SP1 and an end position EP1 are set, and on the surface 3a of the sealing body 3, an intermediate position S1 and an intermediate position E1 are set. As shown in FIG. 3, the movement route R1 through which the rotation axis C of the rotary tool F (see FIG. 4) of this embodiment passes passes through the start position SP1, the intermediate position S1, the intermediate position E1, and the end position EP1. The movement route R1 is a route sandwiched between the start position SP1 which is the starting point and the end position EP1 which is the end point, and includes an insertion section, a main section, and a detachment section. In this method, at the start position SP1, the insertion step, the pulling-up step, the changing step, and the pushing step are performed. Also, in this method, the joining step is performed in the insertion section, the main section, and the detachment section.

[0021] The insertion section is the section from the start position SP1 set at the end surface 11a of the peripheral wall portion 11 to the intermediate position S1 set on the surface 3a of the sealing body 3. In the insertion section, the rotary tool F inserted at the start position SP1 is gradually pushed in while being moved toward the intermediate position S1.

[0022] This section is the section from the intermediate position S1, along the first butting portion J1 for one round, passing through the intermediate position S1, to the intermediate position E1 set on the surface 3a of the sealing body 3. Although details will be described later, in this section, the movement route R1 is set slightly inside (on the side of the sealing body 3) than the first butting portion J1. In this section, the rotary tool F is moved at a substantially constant depth.

[0023] The detachment section is the section from the intermediate position E1 to the end position EP1 set on the end face 11a of the peripheral wall portion 11. In the detachment section, while moving the rotary tool F described later, it is gradually pulled up, and the rotary tool F is separated from the sealing body 3 at the end position EP1.

[0024] The displacement amount P1 from the first butting portion J1 to the movement route R1 may be set as appropriate, but preferably 0.1 (mm) < P1, more preferably 0.2 (mm) < P1, preferably P1 < 0.5 (mm), and more preferably P1 < 0.4 (mm). The displacement amount P1 is the distance from the first butting portion J1 to the movement route R1. That is, the displacement amount P1 means how much the movement route R1 is offset on the same plane with respect to the first butting portion J1.

[0025] <Rotary tool> The rotary tool F used for manufacturing the joined body will be described. As shown in FIG. 4, the rotary tool F includes a shoulder portion F1 and a stirring pin F2. The rotary tool F is formed of, for example, tool steel. The shoulder portion F1 is a portion connected to the output shaft of a joining device (not shown) and has a columnar or platen shape. The stirring pin F2 hangs down from the lower end surface F1a of the shoulder portion F1. The stirring pin F2 has a frustum shape that tapers toward the tip side with the lower end surface F1a side of the shoulder portion F1 as the base end. The lower end surface F1a may be flat or may be a mortar shape that is concave upward (in the direction away from the stirring pin F2). The tip of the stirring pin F2 is flat. A spiral groove is formed on the outer peripheral surface of the stirring pin F2 over the entire height direction. The spiral groove may be either right-handed or left-handed, but in this embodiment, it is left-handed (counterclockwise when viewed from above). The length L1 of the stirring pin F2 can be designed according to the joining depth of the members to be joined. In this embodiment, for the purpose of joining the entire first butting portion J1 described later and joining up to the second butting portion J2, the stirring pin is inserted to a depth of 15 mm, which is the height dimension of the stepped side surface 12b. Therefore, the case where the length L1 of the stirring pin F2 is 15 mm will be exemplified and described.

[0026] When the rotary tool F is rotated clockwise when the spiral groove is left-handed, or when the rotary tool F is rotated counterclockwise when the spiral groove is right-handed, the plastic flow material softened by friction stirring is guided into the spiral groove and flows toward the tip side of the stirring pin F2. Thereby, it is possible to prevent the plastic flow material from overflowing to the outside during friction stir joining, and it is possible to suppress the generation of burrs. As described above, the case where the rotary tool F is rotated clockwise when the spiral groove is left-handed, or when the rotary tool F is rotated counterclockwise when the spiral groove is right-handed is defined as "forward rotation". On the other hand, the case where the rotary tool F is rotated counterclockwise when the spiral groove is left-handed, or when the rotary tool F is rotated clockwise when the spiral groove is right-handed is defined as "reverse rotation".

[0027] <Preparation process> The preparation process is a process of preparing the jacket body 2 and the sealing body 3. The jacket body 2 and the sealing body 3 are not particularly limited with respect to the manufacturing method. However, the jacket body 2 is formed by die casting, for example. The sealing body 3 is formed by extrusion molding, for example.

[0028] <Butting process> As shown in FIG. 2, the butting process is a process of placing the sealing body 3 on the jacket body 2 and butting the side surfaces against each other. By the butting process, the side surface 3c of the sealing body 3 and the stepped side surface (side surface) 12b of the peripheral wall stepped portion 12 are butted against each other to form the first butted portion J1. As shown in FIG. 3, the first butted portion J1 is formed in a rectangular shape in plan view along the periphery of the sealing body 3 and the inner edge of the end surface 11a of the jacket body 2. Further, the stepped bottom surface 12a of the peripheral wall stepped portion 12 and the back surface 3b of the sealing body 3 are butted against each other (overlapped) to form the second butted portion J2. In the present embodiment, the plate thickness of the sealing body 3 is the same as the height dimension of the stepped side surface 12b. The plate thickness of the sealing body 3 may be set to be larger than the height dimension of the stepped side surface 12b. Thereby, it is possible to prevent the shortage of the metal at the joint portion. After the butting process, the jacket body 2 and the sealing body 3 are fixed with a jig (not shown) so that their positions do not shift.

[0029] <Insertion process> As shown in Fig. 5, the insertion process is a process of inserting the rotary tool F into the member to be joined (here, the jacket body 2). In the insertion process, the rotary tool F is rotated (counter-rotated) in the same direction as the formation direction of the spiral groove provided in the stirring pin F2. In the present embodiment, since the spiral groove is left-handed, the rotary tool F is rotated counterclockwise. In the insertion process, the rotary tool F is pushed in until a predetermined insertion depth H1 is reached. The insertion depth H1 is the distance from the end face 11a of the peripheral wall portion 11 to the tip of the stirring pin F2. The insertion depth H1 can be appropriately set within a range not exceeding the length L1 of the stirring pin F2. In the insertion process, the insertion depth H1 may be set within a range where only the stirring pin F2 contacts the peripheral wall portion 11 and the shoulder portion F1 does not contact the peripheral wall portion 11. By the insertion process, the material of the sealing body 3 is frictionally stirred to form a plasticized region W1. Note that the position of the tip of the inserted stirring pin F2 is taken as the first virtual reference plane D1.

[0030] The insertion depth H1 of the stirring pin F2 in the insertion process may be appropriately set according to the length L1 of the stirring pin F2 and the member to be joined, but is preferably 7.5 mm or more, more preferably 9 mm or more, still more preferably 10.5 mm or more, and preferably 15 mm or less, more preferably 13.5 mm or less, still more preferably 12 mm or less.

[0031] In relation to the length L1 of the stirring pin F2, the insertion depth H1 of the stirring pin F2 in the insertion process is preferably L1×0.5≦H1, more preferably L1×0.6≦H1, still more preferably L1×0.7≦H1, and preferably H1≦L1, more preferably H1≦L1×0.9, still more preferably H1≦L1×0.8.

[0032] The rotational speed of the rotary tool F in the insertion process may be set as appropriate, but it is preferably set to be equal to or higher than the rotational speed in the joining process. The rotational speed of the rotary tool F in the insertion process is, for example, preferably 400 rpm or higher, more preferably 600 rpm or higher, still more preferably 800 rpm or higher, even more preferably 900 rpm or higher, particularly preferably 1000 rpm or higher, and preferably 5000 rpm or lower, more preferably 4000 rpm, and still more preferably 3000 rpm.

[0033] The rotational speed of the rotary tool F in the insertion process, for example, the relationship between the rotational speed N1 of the rotary tool F in the insertion process and the rotational speed N2 of the rotary tool F in the joining process is preferably N2≦N1, more preferably N2×1.1≦N1, still more preferably N2×1.5≦N1, and preferably N1≦N2×5, more preferably N1≦N2×4, still more preferably N1≦N2×3.

[0034] <Lifting process> As shown in FIG. 6, the lifting process is a process of lifting the rotary tool F in the surface direction of the member to be joined (here, the jacket body 2) after the insertion process. That is, the rotary tool F is lifted while maintaining the rotational direction (reverse rotation) in the insertion process. In the lifting process, the position of the tip of the rotary tool F after being lifted is set as the second virtual reference plane D2. The lifting amount H2 for lifting the rotary tool F in the lifting process is the distance from the first virtual reference plane D1 to the second virtual reference plane D2. In the lifting process, the rotary tool F may be lifted slightly from the first virtual reference plane D1, or may be lifted so as to be separated above the end surface 11a of the peripheral wall portion 11.

[0035] The lifting amount H2 in the lifting process may be appropriately set according to the length L1 of the stirring pin F2 and the member to be joined, but is preferably 0.1 mm or more, more preferably 0.3 mm or more, still more preferably 0.5 mm or more, and preferably 7.5 mm or less, more preferably 3 mm or less, still more preferably 2 mm or less.

[0036] The amount of lifting H2 in the lifting process may be set as appropriate, but the relationship with the insertion depth H1 is preferably H1×0.01≦H2, more preferably H1×0.05≦H2, still more preferably H1×0.1≦H2, and preferably H2≦H1×0.5, more preferably H2≦H1×0.3, still more preferably H2≦H1×0.2.

[0037] <Change process> As shown in FIG. 7, the change process is a process of changing the rotation direction of the rotary tool F. In the present embodiment, since it was rotated reversely in the insertion process, it is changed from reverse rotation to forward rotation. In other words, in the present embodiment, the rotation direction of the rotary tool F is changed from left rotation to right rotation. The change process may be performed with the stirring pin F2 in contact with the peripheral wall portion 11, or the rotation direction may be changed in a state separated from the peripheral wall portion 11 as in the present embodiment.

[0038] In the change process, the rotational speed of the rotary tool F after changing the rotation direction can be appropriately set according to the member to be joined. The rotational speed of the rotary tool F after changing the rotation direction can be set to the same rotational speed as the rotational speed of the rotary tool F set in the joining process.

[0039] <Pushing-in process> As shown in FIG. 8, the pushing-in process is a process of pushing the rotary tool F in the depth direction of the member to be joined (here, the jacket body 2) after the change process. That is, the rotary tool F is pushed in while maintaining the rotation direction (forward rotation) after the change process. In the pushing-in process, the position of the tip after pushing in the rotary tool F is set as the third virtual reference plane D3. The insertion amount H3 for pushing in the rotary tool F in the pushing-in process is the distance from the first virtual reference plane D1 to the third virtual reference plane D3 (the insertion amount after the stirring pin F2 contacts the peripheral wall portion 11 again). In the pushing-in process, the rotary tool F may be brought into slight contact with the peripheral wall portion 11. That is, it is preferable to set the insertion amount so that at least the tip side of the stirring pin F2 is deeper than the first virtual reference plane D1.

[0040] In the pressing process, the rotary tool F is pressed until a predetermined insertion depth H4 is reached. The insertion depth H4 is the distance from the end face 11a of the peripheral wall portion 11 to the tip of the stirring pin F2. The insertion depth H1 in the insertion process, the insertion amount H3 and the insertion depth H4 in the pressing process satisfy the relationship H1 + H3 = H4. The insertion depth H4 in the pressing process is the insertion depth of the rotary tool F when starting friction stir welding in the joining process.

[0041] Also, the insertion amount H3 in the pressing process may be appropriately set according to the length L1 of the stirring pin F2 and the members to be joined. Preferably, it is 0.1 mm or more, more preferably 0.3 mm or more, still more preferably 0.5 mm or more, and preferably 7.5 mm or less, more preferably 3 mm or less, still more preferably 1 mm or less. The insertion amount H3 may be, for example, about one-tenth of the length L1 of the stirring pin F2.

[0042] The relationship between the insertion amount H3 and the insertion depth H1 in the pressing process is preferably H1×0.01 ≤ H3, more preferably H1×0.05 ≤ H3, still more preferably H1×0.1 ≤ H3, and preferably H3 ≤ H1×0.5, more preferably H3 ≤ H1×0.3, still more preferably H3 ≤ H1×0.2.

[0043] Also, the insertion depth H4 in the pressing process may be appropriately set according to the length L1 of the stirring pin F2 and the members to be joined. Preferably, it is 8 mm or more, more preferably 9 mm or more, still more preferably 10 mm or more, and preferably 15 mm or less, more preferably 13.5 mm or less, still more preferably 12 mm or less.

[0044] The relationship between the insertion depth H4 and the insertion depth H1 in the pressing process is preferably H1×1.01 ≤ H4, more preferably H1×1.05 ≤ H4, still more preferably H1×1.1 ≤ H4, and preferably H4 ≤ H1×1.5, more preferably H4 ≤ H1×1.3, still more preferably H4 ≤ H1×1.2.

[0045] The rotational speed of the rotary tool F in the pressing-in process can be appropriately set according to the members to be joined. The rotational speed of the rotary tool F in the pressing-in process can be set to the same rotational speed as the rotational speed of the rotary tool F set in the joining process.

[0046] <Joining process> As shown in FIG. 9, the joining process is a process of joining the members to be joined (here, the jacket body 2 and the sealing body 3) with the rotary tool F rotated in the direction opposite to the direction of formation of the spiral groove. That is, in the joining process, friction stir joining is performed with the tool rotated in the forward rotation direction. In the joining process, the members to be joined are joined by moving the rotary tool F while rotating the rotary tool F in the direction opposite to the direction of formation of the spiral groove. After the rotary tool F is pushed in to a predetermined insertion depth H4 in the above-described pressing-in process, while moving the rotary tool F to the intermediate position S1, it is gradually pushed in deeper toward a position where a predetermined insertion depth H5 is reached. When the intermediate position S1 is reached, the rotary tool F is moved along the first butting portion J1 with the rotation axis C of the rotary tool F aligned with the movement route R1. The movement route R1 may be set at the same position as the first butting portion J1, but in the present embodiment, it is set slightly inside (on the side of the sealing body 3) of the first butting portion J1. The movement route R1 and the first butting portion J1 are substantially parallel.

[0047] The insertion depth H5 of the rotary tool F is the distance from the end face 11a of the peripheral wall portion 11 to the tip of the stirring pin F2. The insertion depth H5 may be appropriately set within a range in which the first butting portion J1 can be friction stir joined, but in the present embodiment, it is set such that the tip of the stirring pin F2 is deeper than the step bottom face 12a.

[0048] In the joining process, while maintaining the insertion depth H5, after rotating one full turn clockwise along the movement route R1 from the intermediate position S1 (see FIG. 3), it is moved to the intermediate position E1 while overlapping a part of the plasticized region W1. Then, while moving to the end position EP1, the rotary tool F is gradually pulled up. Finally, the rotary tool F is detached from the sealing body 3 at the end position EP1.

[0049] In addition, the insertion depth H5 in the joining process may be appropriately set according to the length L1 of the stirring pin F2 and the members to be joined. In this embodiment, it is preferably 15 mm or more, more preferably 16 mm or more, preferably 18 mm or less, and more preferably 17 mm or less.

[0050] [1-3. Operational effects] According to the method for manufacturing a joined body according to the present embodiment described above, in the insertion process, the stirring pin F2 is inserted into the member to be joined (here, the jacket body 2) with the rotary tool F rotated (reverse rotation) in the same direction as the formation direction of the spiral groove. When the stirring pin F2 is inserted into the member to be joined, the spiral groove acts on the member to be joined like the blade of a drill, and the spiral groove penetrates while scraping off the material of the member to be joined. That is, in the insertion process of this embodiment, the stirring pin F2 penetrates into the member to be joined without causing plastic flow as in the case of normal rotation. Therefore, the rotary tool F is more likely to penetrate into the member to be joined than in the case of normal rotation. As a result, when the stirring pin F2 is inserted, the member to be joined is actively discharged to the outside as the stirring pin is inserted, so that the load applied to the rotary tool F and the joining device during insertion can be reduced. In addition, the wear of the spiral groove of the stirring pin F2 can be reduced as the load is reduced, and the breakage of the stirring pin F2 can be reduced.

[0051] Conventionally, in order to reduce the press-fitting resistance, a pilot hole has been provided at the starting position SP1 of the stirring pin F2. However, in this case, the number of steps for forming the pilot hole increases, which takes time and has been a problem. Also, for example, when forming a pilot hole and performing friction stir joining using a machining center, it has been a problem that it takes time to exchange the tools used for each process. However, according to the present embodiment, the press-fitting resistance can be reduced without providing a pilot hole, and the stirring pin F2 can be inserted smoothly, improving productivity.

[0052] Further, in the present embodiment, after the stirring pin F2 is inserted, the rotation direction of the rotary tool F is switched to the direction opposite to the formation direction of the spiral groove, and friction stir welding is performed with the rotary tool F rotating (forward rotation) in the direction opposite to the formation direction of the spiral groove. Thereby, during friction stir welding, downward plastic flow can be caused to replenish the material toward the tip side of the stirring pin F2, and the occurrence of defects inside can be made less likely.

[0053] Also, in the insertion process of the present embodiment, it is presumed that the material of the joined member that has been shaved off is discharged to the outside of the joined member along with the rotation of the spiral groove, like the chips generated by cutting with a drill. As a result, it becomes less likely for the material that has undergone plastic fluidization to remain as burrs on the surface of the joined member (here, the end face 11a of the peripheral wall portion 11) after friction stir welding. Therefore, the burden of post-processing such as cutting for removing burrs can be reduced, and productivity can be improved.

[0054] Also, the rotational speed of the rotary tool F in the insertion process of the present embodiment may be set as appropriate, but it is preferable that the rotational speed of the rotary tool F is equal to or higher than the rotational speed of the rotary tool F in the joining process. By setting the rotational speed in the insertion process to be equal to or higher than the rotational speed in the joining process, the joined member is cut by the spiral groove when the stirring pin F2 is inserted, and the chips of the joined member cut along with the rotation of the rotary tool F are easily blown out from the surface of the joined member to the outside, making it easier to prevent burrs and chips from remaining on the surface of the joined member after joining. In particular, even when the size of the rotary tool F is relatively small, it becomes easier to blow out the chips of the joined member. Also, when the rotational speed at the time of insertion is low, the generation of the oxide film being rolled up is likely to occur, but by setting the rotational speed in the insertion process to be equal to or higher than the rotational speed in the joining process, the occurrence of such rolling up can be prevented.

[0055] Also, it is preferable that the relationship between the rotational speed N1 of the rotary tool F in the insertion step and the rotational speed N2 of the rotary tool F in the joining step is N2 ≦ N1 ≦ N2 × 5 as in the present embodiment. By setting the rotational speed N1 to be equal to or higher than N2, the cutting effect of the joined member by the spiral groove of the stirring pin F2 can be enhanced. Also, by setting the rotational speed N1 to be equal to or lower than N2 × 5, the load on the rotary tool F and the joining device can be reduced.

[0056] Also, as in the present embodiment, it is preferable to further include a pulling-up step of pulling up the rotary tool F in the direction of the surface of the joined member after the insertion step, and to perform a changing step during the pulling-up step. By pulling up the rotary tool F after the insertion step, the contact resistance between the rotary tool F and the joined member is reduced (substantially eliminated), so that the load on the rotary tool F and the joining device generated when changing the rotational direction can be suppressed.

[0057] Also, it is preferable that the relationship between the insertion depth H1 of the rotary tool F in the insertion step and the pulling-up amount H2 in the pulling-up step is H1 × 0.01 ≦ H2 ≦ H1 × 0.5 as in the present embodiment. By setting the pulling-up amount H2 to be equal to or higher than H1 × 0.01, the contact resistance with the joined member can be reduced. By setting the pulling-up amount H2 to be equal to or lower than H1 × 0.5, it is possible to prevent the temperature of the joined member from dropping due to the excessive separation of the rotary tool F and the joined member, and subsequent joining can be performed suitably.

[0058] Also, as in the present embodiment, it is preferable to further include a pushing-in step of pushing the rotary tool F in the depth direction of the joined member after the changing step, and to perform a joining step after the pushing-in step. By pushing in the stirring pin F2 after changing the rotational direction, the metal structure formed during the reverse rotation in the insertion step can be changed to a structure composed of a downward plastic flow material by the forward rotation. Also, by pushing in the stirring pin F2, heat generation can be increased because the rotary tool (stirring pin F2 (+ shoulder portion F1)) F newly comes into contact with the joined member. Therefore, subsequent joining can be performed suitably.

[0059] Further, as in the present embodiment, it is preferable that the relationship between the insertion depth H1 of the rotary tool in the insertion step and the insertion amount H3 in the pressing step is H1×0.01≦H3≦H1×0.5. By setting the insertion amount H3 to be H1×0.01 or more, a structure composed of downward plastic flow due to forward rotation is generated, and heat generation is increased by the contact between the rotary tool F and the new member to be joined, so that friction stir welding can be suitably performed. Also, by setting the insertion amount H3 to be H1×0.5 or less, the load applied to the rotary tool F and the joining device can be reduced.

[0060] Further, as in the present embodiment, it is preferable that the relationship between the insertion depth H1 of the rotary tool in the insertion step and the insertion depth H4 at the start of joining in the joining step is H1×1.01≦H4≦H1×1.5. By setting the insertion depth H4 to be H1×0.01 or more, a structure composed of downward plastic flow due to forward rotation is generated, and heat generation is increased by the contact between the rotary tool F and the new member to be joined, so that friction stir welding can be suitably performed. Also, by setting the insertion depth H4 to be H1×1.5 or less, the load applied to the rotary tool F and the joining device can be reduced.

[0061] Further, when having a shoulder portion F1 like the rotary tool F of the present embodiment, the chips can be suitably removed by the contact of the shoulder portion F1, and the heat generation efficiency by the shoulder portion F1 during joining is also improved. In general, when using a rotary tool provided with a shoulder portion, the contact area with the member to be joined becomes large, so the load acting on the joining device tends to increase. However, in the present embodiment, the insertion step, the pulling-up step, the changing step, and the pressing step are provided, and the member to be joined is actively discharged to the outside in advance during these steps (during insertion). Therefore, when performing friction stir welding with the shoulder portion in contact with the member to be joined, the load acting on the rotary tool F and the joining device can be reduced.

[0062] Also, as in the present embodiment, it is preferable that the relationship between the insertion depth H1 of the rotary tool F in the insertion step and the length L1 of the stirring pin F2 is L1×0.5≦H1≦L1. By setting the insertion depth H1 to be L1×0.5 or more, it becomes easier to obtain the effect of reducing the load applied to the rotary tool F and the joining device by scraping off the material by the spiral groove of the stirring pin F2. Also, by setting the insertion depth H1 to H1≦L1, it is possible to prevent the shoulder portion F1 and the member to be joined from coming into contact with each other frequently during the insertion step and increasing the contact resistance.

[0063] Also, in the present embodiment, it is composed of a jacket body (first member to be joined) 2 and a sealing body 3 (second member to be joined) having a lower hardness than the jacket body 2. Thereby, the strength of the liquid-cooled jacket (joined body) 1 can be increased. Also, in the present embodiment, a movement route R1 is set inside the first butting portion J1, and friction stir joining is performed with the movement route R1 and the rotation axis C of the rotary tool F overlapped. Thereby, it is possible to prevent the material of the relatively hard jacket body 2 from being mixed into the sealing body 3 side as much as possible, and it is possible to prevent the strength of the joined portion from decreasing. Also, since the imbalance due to the material resistance during friction stir joining is eliminated, it is possible to perform friction stirring in a well-balanced manner and join suitably. From the viewpoint of reducing the load applied to the rotary tool F and the joining device during insertion, it is desirable to insert the stirring pin into the second member to be joined having a lower hardness than the first member to be joined. In the present embodiment, by providing the insertion step, the change step, and the joining step in order, even when the stirring pin is inserted into the first member to be joined having a high hardness, the load applied to the rotary tool F and the joining device during insertion can be reduced.

[0064] Also, in the joining step, by setting the insertion depth so that the tip of the stirring pin F2 reaches the bottom surface 12a of the step, it is possible to surely perform friction stir joining not only on the first butting portion J1 but also on the second butting portion J2.

[0065] Also, if the starting position SP1 is provided on the first butting portion J1, the oxide film may be lifted up. However, in the joining process of this embodiment, the starting position SP1 is set on the end face 11a of the peripheral wall portion 11. Thereby, in particular, it is possible to prevent the oxide film from remaining in the plasticized region W1 at the insertion position.

[0066] [1-4. Others] Although the manufacturing method of the joined body according to this embodiment has been described above, design changes can be appropriately made within a range not contrary to the gist of the present invention. For example, in the above embodiment, the case where the side surface 3c of the sealing body 3 and the stepped side surface 12b of the peripheral wall stepped portion 12 are butted against each other to form the first butting portion J1, that is, the case where the end faces on both sides of the first joined member and the second joined member are joined together is exemplified. It is sufficient that a butting portion is formed by butting at least one of the end faces of the first joined member and the second joined member against the other.

[0067] Also, in the above embodiment, the insertion process, the pulling-up process, the changing process, and the pushing-in process were performed without moving the rotary tool F from the starting position SP1, but each process may be performed while moving in the advancing direction. That is, in the insertion section from the starting position SP1, the insertion process, the pulling-up process, the changing process, and the pushing-in process may be performed while moving the rotary tool F.

[0068] Also, the pulling-up process may be omitted. That is, after the insertion process is completed, the rotational direction of the rotary tool F may be changed while maintaining the height position of the rotary tool F (while remaining in contact with the joined member). In particular, when the rotary tool F is relatively small, since the contact resistance is small, the pulling-up process may be omitted.

[0069] Also, the pushing-in process may be omitted. Also, in the insertion section, the case where the rotary tool F is gradually pushed in while moving has been exemplified and described, but after inserting to a predetermined insertion depth H5 at the starting position SP1, the rotary tool F may be moved while maintaining the insertion depth H5.

[0070] Further, in the joining step, the start position SP1 and the end position EP1 may be set on the first butting portion J1 or on the surface 3a of the sealing body 3. Also, although the joined body is exemplified by a rectangular parallelepiped-shaped liquid cooling jacket in the present embodiment, it may have other shapes, as long as at least two members are joined.

[0071] Further, the stepped side surface 12b may be inclined outward with respect to the stepped bottom surface 12a. In this case, it is preferable to set the rotation axis C of the rotary tool F inside the side surface 3c of the sealing body 3 so that the contact between the stirring pin F2 and the peripheral wall portion 11 becomes thin. Thereby, since the material of the relatively hard jacket body 2 can be minimized from mixing into the sealing body 3 side, a decrease in the joining strength can be prevented. Also, the imbalance due to the material resistance during friction stirring can be eliminated. At this time, the plate thickness of the sealing body 3 may be made larger than the height dimension of the stepped side surface 12b. Thereby, the material shortage in the joined portion can be compensated.

[0072] [2. First Modification of the First Embodiment] Next, the first modification of the above-described first embodiment will be described. The method for manufacturing a joined body according to this modification is different from the above-described first embodiment in that it includes a counterbore forming step.

[0073] In this modification, as shown in FIG. 10, before the insertion step, a counterbore forming step is performed. In the counterbore forming step, a counterbore Q is formed at the start position SP1 set on the end face 11a of the peripheral wall portion 11 using a cutting tool such as a rotary tool or an end mill. The shape of the counterbore Q is a hollow portion having a push bench shape in this modification, but it may be a hollow portion having a conical shape, a cylindrical shape, or a prismatic shape.

[0074] By performing the lower hole forming step, the press-fitting resistance by the rotary tool F during the insertion step can be reduced. Further, this can also reduce the breakage and wear of the rotary tool F. In particular, when the jacket body (first joined member) 2 is formed of a relatively hard material such as an aluminum alloy casting material, the effect of reducing the press-fitting resistance becomes remarkable. When setting the start position SP1 on the surface 3a of the sealing body 3, a lower hole Q may be provided in the surface 3a. Further, the lower hole Q may be formed in advance at the molding stage of the jacket body 2.

[0075] [3. Second Modification of the First Embodiment] Next, a second modification of the above-described first embodiment will be described. The method for manufacturing the joined body according to this modification is different from the above-described first embodiment in that a rotary tool K is used, as shown in FIG. 11.

[0076] The rotary tool K includes a base portion K1 and a stirring pin K2. The base portion K1 is a portion connected to the output shaft of a joining device (not shown) and has a columnar or push bench shape. The stirring pin K2 has a frustoconical shape and hangs down from the lower end surface K1a of the base portion K1. The stirring pin K2 has a length that is at least twice the plate thickness of the sealing body 3. The tip of the stirring pin K2 is flat. A spiral groove is formed on the outer peripheral surface of the stirring pin K2 over the entire height direction. The spiral groove may be either right-handed or left-handed, but in this embodiment, it is left-handed (counterclockwise when viewed from above).

[0077] In the method for manufacturing the joined body of this modification, a preparation step, a butting step, an insertion step, a pulling-up step, a changing step, a pushing step, and a joining step are performed. The preparation step and the butting step are the same as those in the above-described first embodiment.

[0078] In the insertion step, as shown in FIG. 11, the rotary tool K is rotated counterclockwise (left rotation) to insert the stirring pin K2 into the end surface 11a of the peripheral wall portion 11. In the insertion step, only the stirring pin K2 is brought into contact with the peripheral wall portion 11. Other procedures of the insertion process are the same as those of the first embodiment described above. Also, the pulling-up process, the changing process, and the pushing-in process are the same as those of the first embodiment described above.

[0079] In the joining process, as shown in FIG. 12, while rotating the rotary tool K in the normal direction (clockwise), while superimposing the rotation axis C on the movement route R1, the rotary tool K is moved so as to be parallel to the first butting portion J1. In the joining process, only the stirring pin K2 is brought into contact with the members to be joined (here, the jacket body 2 and the sealing body 3), and friction stir welding is performed with the base end side of the stirring pin K2 exposed.

[0080] Even the rotary tool K of this modification can achieve substantially the same effects as those of the first embodiment described above. Further, in the joining process, since only the stirring pin K2 is brought into contact with the members to be joined and the base portion K1 is not brought into contact with the members to be joined, the load acting on the joining device can be reduced. Even when the rotary tool K is used, the stepped side surface 12b may be inclined outward.

[0081] [4. Third Modification of the First Embodiment] Next, a third modification of the first embodiment described above will be described. The method for manufacturing a joined body according to this modification is different from the first embodiment described above in that a rotary tool G is used, as shown in FIG. 13.

[0082] The rotary tool G is formed of, for example, tool steel, and is mainly composed of a base portion G1 and stirring pins (a base end side pin G2 and a tip end side pin G3). The base portion G1 has a columnar or trapezoidal shape and is a portion connected to the output shaft of the joining device.

[0083] The base end side pin G2 is continuous with the base portion G1 and tapers toward the tip. The base end side pin G2 has a frustum shape. The taper angle A of the base end side pin G2 may be set as appropriate, but is, for example, 135 to 160°. When the taper angle A is 135 to 160°, the surface roughness of the joint after friction stirring can be reduced.

[0084] The taper angle A is larger than the taper angle B of the tip-side pin G3 described later. As shown in FIG. 14, a stepped pin step portion G21 is formed over the entire height direction on the outer peripheral surface of the base-end side pin G2. The pin step portion G21 is formed in a spiral shape with a right-handed or left-handed twist. That is, the pin step portion G21 is spiral in plan view and stepped in side view. In this modification, the pin step portion G21 is set to be left-handed from the base-end side toward the tip-side.

[0085] As shown in FIG. 14, the pin step portion G21 is composed of a step bottom surface G21a and a step side surface G21b. The distance X1 (horizontal distance) between the vertices G21c, G21c of adjacent pin step portions G21 is appropriately set according to the step angle M1 and the height Y1 of the step side surface G21b described later.

[0086] The height Y1 of the step side surface F21b may be set as appropriate. For example, it is set to 0.1 to 0.4 mm. If the height Y1 is less than 0.1 mm, the joint surface roughness increases. On the other hand, if the height Y1 exceeds 0.4 mm, the joint surface roughness tends to increase, and the effective number of step portions (the number of pin step portions G21 in contact with the metal member to be joined) also decreases.

[0087] The step angle M1 formed by the step bottom surface G21a and the step side surface G21b may be set as appropriate. For example, it is set to 85 to 120°. The step bottom surface G21a is parallel to the horizontal plane (here, the plane perpendicular to the rotation axis C) in this embodiment. The step bottom surface G21a may be inclined within a range of -5° to 15° with respect to the horizontal plane from the rotation axis C toward the outer peripheral direction (minus is downward with respect to the horizontal plane, plus is upward with respect to the horizontal plane). The distance X1, the height Y1 of the step side surface G21b, the step angle M1, and the angle of the step bottom surface G21a with respect to the horizontal plane are appropriately set so that when friction stir welding is performed, the plastic flow material can escape to the outside without staying and adhering inside the pin step portion G21, and the plastic flow material can be pressed by the step bottom surface G21a to reduce the joint surface roughness.

[0088] As shown in Fig. 13, the tip-side pin G3 is continuously formed on the base-end side pin G2. The tip-side pin G3 has a frustum shape. The tip of the tip-side pin G3 is flat. The taper angle B of the tip-side pin G3 is smaller than the taper angle A of the base-end side pin G2. As shown in Fig. 14, a spiral groove G31 is engraved on the outer peripheral surface of the tip-side pin G3. The spiral groove G31 may be either right-handed or left-handed, but in this embodiment, it is engraved in a left-handed manner.

[0089] The spiral groove G31 is composed of a spiral bottom surface G31a and a spiral side surface G31b. Let the distance (horizontal distance) between the vertices G31c, G31c of adjacent spiral grooves G31 be the length X2. Let the height of the spiral side surface G31b be the height Y2. The spiral angle M2 formed by the spiral bottom surface G31a and the spiral side surface G31b is, for example, formed at 45 to 90°. The spiral groove G31 serves to increase the frictional heat by contacting the member to be joined and to guide the plastic flow material to the tip side. The spiral angle M2, the length X2, and the height Y2 may be set as appropriate. Note that the pin step portion G21 and the spiral groove G31 of the rotary tool G correspond to the "spiral groove of the stirring pin" in the claims.

[0090] In the method for manufacturing the joined body of this modification, a preparation step, a butting step, an insertion step, a pulling-up step, a changing step, a pushing step, and a joining step are performed. The preparation step and the butting step are the same as those in the above-described first embodiment.

[0091] In the insertion step, as shown in Fig. 13, the rotary tool G is rotated counterclockwise (left rotation) to insert the tip-side pin G3 into the end surface 11a of the peripheral wall portion 11. In the insertion step, only the tip-side pin G3 is brought into contact with the peripheral wall portion 11. Other procedures in the insertion step are the same as those in the above-described first embodiment. Also, the pulling-up step, the changing step, and the pushing step are the same as those in the above-described first embodiment.

[0092] In the joining step, as shown in FIG. 15, while rotating the rotary tool G in the right direction (clockwise), the rotary tool G is moved so as to be parallel to the first butting portion J1 while superimposing the rotation axis C on the movement route R1. In the joining step, while bringing the outer peripheral surface of the base end side pin G2 into contact with the surface 3a of the sealing body 3 and the end surface 11a of the peripheral wall portion 11, the insertion depth is set so that the tip of the tip end side pin G3 is positioned below the step bottom surface 12a.

[0093] Even the rotary tool G of this modified example can exhibit substantially the same effects as those of the above-described first embodiment. Further, in the joining step, since the plastic flow material can be pressed by the outer peripheral surface of the base end side pin G2, the step concave groove formed on the joining surface can be made smaller, and the bulging portion formed beside the step concave groove can be eliminated or made smaller. Further, since the stepped pin step portion G21 is shallow and has a wide outlet, the plastic flow material is easily released to the outside of the pin step portion G21 while the plastic flow material is pressed by the step bottom surface G21a. Therefore, even if the plastic flow material is pressed by the base end side pin G2, it is difficult for the plastic flow material to adhere to the outer peripheral surface of the base end side pin G2. Thus, the joining surface roughness can be reduced and the joining quality can be suitably stabilized.

[0094] Further, the rotary tool G of the present embodiment has a configuration including a base end side pin G2 and a tip end side pin G3 having a smaller taper angle than the taper angle A of the base end side pin G2. Thereby, it becomes easier to insert the rotary tool G into the jacket body 2 and the sealing body 3. Further, since the taper angle B of the tip end side pin G3 is small, the rotary tool G can be easily inserted to a deep position of the first butting portion J1. Even when the rotary tool G is used, the step side surface 12b may be inclined outward.

[0095] [5. Fourth Modified Example of the First Embodiment] Next, a fourth modified example of the above-described first embodiment will be described. The method for manufacturing a joined body according to this modified example is different from the above-described first embodiment in that, in the insertion step, a stirring pin is inserted toward the first butting portion J1.

[0096] In the manufacturing method of the joined body of this modification example (hereinafter, may be referred to as "this method"), a preparation step, a butting step, an insertion step, a pulling-up step, a changing step, a pushing step, and a joining step are performed. The preparation step and the butting step are the same as those in the above-described first embodiment.

[0097] In this method, as shown in FIG. 16, with the sealing body 3 placed on the jacket body 2 and the side surfaces butted against each other, friction stir joining of the jacket body 2 and the sealing body 3 is performed. In this method, at the end face 11a of the peripheral wall portion 11, an end position EP1 is set, and on the surface 3a of the sealing body 3, a start position SP2, an intermediate position S1, and an intermediate position E1 are set. In this method, the start position SP2 is set such that the plasticized region W2 (see FIG. 17) formed by inserting the stirring pin F2 at the start position SP2, which is the insertion position of the rotary tool F, has a positional relationship overlapping with the first butting portion J1. The movement route R2 through which the rotation axis C of the rotary tool F of this method passes passes through the start position SP2, the intermediate position S1, the intermediate position E1, and the end position EP1. The movement route R2 is a route sandwiched between the start position SP2, which is the starting point, and the end position EP1, which is the ending point, and includes an insertion section, a main section, and a detachment section. In this method, at the start position SP2, an insertion step, a pulling-up step, a changing step, and a pushing step are performed. Also, in this method, a joining step is performed in the insertion section, the main section, and the detachment section.

[0098] The insertion section is the section from the start position SP2 to the intermediate position S1. In the insertion section, the rotary tool F inserted at the start position SP2 is gradually pushed in while being moved toward the intermediate position S1.

[0099] In the main section, the movement route R2 is set slightly inside (on the side of the sealing body 3) of the first butting portion J1. Also, the movement route R2 and the first butting portion J1 are substantially parallel.

[0100] As shown in Fig. 17, the insertion step of this method is a step of inserting the rotary tool F into the members to be joined (jacket body 2 and sealing body 3). More specifically, the insertion step of this method is a step of inserting the rotary tool F toward the first butting portion J1 between the jacket body 2 and the sealing body 3. In the insertion step, the rotary tool F is rotated (counter-rotated) in the same direction as the formation direction of the spiral groove provided in the stirring pin F2, and the rotary tool F is inserted toward the first butting portion J1. The insertion depth H1 of the stirring pin F2 can be set in the same manner as in the first embodiment. By the insertion step, the materials of the jacket body 2 and the sealing body 3 are friction stir plasticized to form a plasticized region W2. At this time, the plasticized region W2 is formed in contact with the jacket body 2 and the sealing body 3 across the first butting portion J1.

[0101] Other procedures of the insertion step are the same as those of the first embodiment described above. Also, the pulling-up step, the changing step, the pushing-in step, and the joining step are the same as those of the first embodiment described above.

[0102] Here, when inserting the positively rotated stirring pin into the joined member, at the position where the stirring pin is inserted, a plasticized region is formed by the plastic flow of the joined member, and the joined member that has undergone plastic flow according to the volume of the inserted stirring pin is pushed downward. At this time, downward convection occurs in the inner part of the plasticized region located around the stirring pin, and upward convection occurs in the outer part of the plasticized region. Therefore, when inserting the positively rotated stirring pin toward the first butting portion J1 formed by the stepped side surface 12b of the jacket body 2 and the side surface 3c of the sealing body 3, the oxide film present at the interface near the position where the stirring pin is inserted may be entrained upward by the plastic flow, resulting in a decrease in the joining strength of the first butting portion J1. Further, when inserting the positively rotated stirring pin into the joined member, the amount of the joined member that undergoes plastic flow and convection increases according to the insertion amount of the stirring pin. Therefore, near the position where the stirring pin is inserted, due to the increase in the convection of the joined member that has undergone plastic flow with the insertion of the stirring pin, entrainment near the interface is likely to occur, resulting in a possible decrease in the joining strength of the first butting portion J1.

[0103] According to this method, in the insertion process, the stirring pin F2 is inserted toward the first butting portion J1 with the rotating tool F rotated (negatively rotated) in the same direction as the formation direction of the spiral groove. Thereby, upward convection occurs in the inner part of the plasticized region W2 located around the stirring pin, and downward convection occurs in the outer part of the plasticized region W2. Therefore, it becomes easier to prevent the oxide film present at the interface between the jacket body 2 and the sealing body 3 from being entrained upward near the start position SP2 of the first butting portion J1. Further, according to this method, when inserting the stirring pin F2, by actively discharging the joined member to the outside with the insertion of the stirring pin, the amount of the joined member that undergoes plastic flow and convection can be reduced. Thereby, it becomes easier to prevent the entrainment of the oxide film present at the interface between the jacket body 2 and the sealing body 3. Therefore, according to this method, a decrease in the joining strength at the first butting portion J1 between the jacket body 2 and the sealing body 3 can be suppressed.

[0104] [6. Second Embodiment] Next, a second embodiment of the present invention will be described. The method for manufacturing the joined body according to this embodiment is different from the above-described first embodiment in that the jacket body 2A and the sealing body 3A are used, as shown in FIG. 18.

[0105] The jacket body 2A is composed of a bottom portion 10 and a peripheral wall portion 11. A recess 13 is formed inside the jacket body 2A. The sealing body 3A covers the opening of the jacket body 2A and has the same size as the outer edge of the peripheral wall portion 11.

[0106] Next, a method for manufacturing the joined body according to this embodiment (hereinafter sometimes referred to as "this method") will be described. In the method for manufacturing the joined body according to this embodiment, a preparation step, a superposition step, an insertion step, a pulling-up step, a modification step, a pressing step, and a joining step are performed. Since the preparation step, the pulling-up step, the modification step, and the pressing step are the same as those in the above-described first embodiment, the description thereof will be omitted.

[0107] In this method, as shown in FIG. 19, friction stir joining of the jacket body 2A and the sealing body 3A is performed in a state where the sealing body 3A is placed on and superposed on the jacket body 2A. As shown in FIG. 20, in this method, on the surface 3a of the sealing body 3, a start position SP3, an intermediate position S3, an intermediate position E3, and an end position EP3 are set at positions corresponding to the overlapping portion J3. The movement route R3 through which the rotation axis C of the rotary tool F in this method passes passes through the start position SP3, the intermediate position S3, the intermediate position E3, and the end position EP3. The movement route R3 is rectangular in plan view so as to overlap the overlapping portion J3. The movement route R3 is a route sandwiched between the start position SP3 which is the starting point and the end position EP3 which is the ending point, and includes an insertion section, a main section, and a detachment section. In this method, at the start position SP3, the insertion step, the pulling-up step, the modification step, and the pressing step are performed. Also, in this method, the joining step is performed in the insertion section, the main section, and the detachment section.

[0108] The insertion section is the section from the start position SP3 to the middle position S3. In the insertion section, the rotary tool F inserted at the start position SP3 is gradually pushed in while being moved to the middle position S3.

[0109] This section is the section where the rotary tool F is moved along the overlapping portion J3 from the middle position S3 for one revolution and then passed through the middle position S3 to the middle position E3. At this time, as shown in Fig. 19, the insertion depth of the rotary tool F is maintained constant so that the stirring pin F2 reaches the end face 11a.

[0110] The detachment section is the section from the middle position E3 to the end position EP3. In the detachment section, the rotary tool F that has reached the middle position E3 is gradually pulled up while being moved toward the end position EP3. When the rotary tool F reaches the end position EP3, the rotary tool F is detached from the sealing body 3.

[0111] The overlapping process is the process of overlapping the jacket body 2A and the sealing body 3A as shown in Fig. 19. In the overlapping process, the end face 11a of the peripheral wall portion 11 and the back face 3b of the sealing body 3A are overlapped to form the overlapping portion J3. The overlapping portion J3 is formed in a rectangular frame shape in plan view along the outer periphery of the concave portion 13.

[0112] The insertion process is the process of inserting the rotary tool F into the member to be joined (sealing body 3A) as shown in Fig. 21. More specifically, it is the process of inserting the rotary tool F from the surface 3a of the sealing body 3A toward the overlapping portion J3 between the jacket body 2A and the sealing body 3A. In the insertion process, the rotary tool F is rotated (counter-rotated) in the same direction as the formation direction of the spiral groove provided in the stirring pin F2. In this embodiment, since the spiral groove is left-handed, the rotary tool F is rotated counterclockwise. In the insertion process of this embodiment, the insertion depth H1 is set within the range where only the stirring pin F2 contacts the sealing body 3A and the stirring pin F2 does not contact the peripheral wall portion 11. In the insertion process, the insertion depth H1 may be set within the range where only the stirring pin F2 contacts the surface 3a of the sealing body 3A and the shoulder portion F1 does not contact the surface 3a. By the insertion process, the material of the sealing body 3A is friction stir welded to form the plasticized region W3.

[0113] The joining step is a step of performing friction stir joining on the overlapping portion J3 using the rotary tool F. In the joining step, the insertion depth of the rotary tool F is set such that the shoulder portion F1 is slightly pushed into the surface 3a of the sealing body 3 while the stirring pin F2 reaches the end face 11a of the peripheral wall portion 11. The insertion depth of the rotary tool F in the joining step may be set as appropriate. For example, the overlapping portion J3 may be joined in a state where the stirring pin F2 does not reach the end face 11a.

[0114] Also according to the present embodiment described above, effects substantially equivalent to those of the first embodiment described above can be achieved. Further, according to the present embodiment, the overlapping portion J3 can also be joined.

[0115] In the present embodiment, the case of using the rotary tool F has been illustrated and described, but the rotary tools K and G may also be used. Further, in the present embodiment, the start position SP3 and the end position EP3 may be set at positions on the surface 3a of the sealing body 3A that do not correspond to the overlapping portion J3 (inside the overlapping portion J3).

[0116] [7. First Modification of the Second Embodiment] Next, the first modification of the second embodiment described above will be described. The method for manufacturing a joined body according to this modification differs from the second embodiment described above in that, in the insertion step, the insertion depth H1 of the stirring pin F2 is set such that the plasticized region W4 formed overlaps the overlapping portion J3.

[0117] In the method for manufacturing a joined body of this modification (hereinafter, sometimes referred to as "this method"), a preparation step, a stacking step, an insertion step, a pulling-up step, a changing step, a pushing-in step, and a joining step are performed. The preparation step and the stacking step are the same as those of the second embodiment described above.

[0118] The insertion step of this method is a step of inserting the rotary tool F into the members to be joined (jacket body 2A and sealing body 3A), as shown in Fig. 22. More specifically, the insertion step of this method is a step of inserting the rotary tool F from the surface 3a of the sealing body 3A toward the overlapping portion J3 between the jacket body 2A and the sealing body 3A. In the insertion step, the rotary tool F is rotated (counter-rotated) in the same direction as the formation direction of the spiral groove provided in the stirring pin F2, and the rotary tool F is inserted toward the overlapping portion J3. In the insertion step of this embodiment, the stirring pin F2 is brought into contact with the sealing body 3A, and the insertion depth H1 is set within the range where the stirring pin F2 is brought into contact with the end face 11a of the peripheral wall portion 11. In the insertion step, the insertion depth H1 may be set within the range where only the stirring pin F2 is brought into contact with the sealing body 3A and the jacket body 2A and the shoulder portion F1 does not contact the surface 3a of the sealing body 3A. By the insertion step, the materials of the jacket body 2A and the sealing body 3A are friction stir plasticized to form a plasticized region W4. At this time, the plasticized region W4 is formed in a shape that straddles the overlapping portion J3 and contacts the jacket body 2A and the sealing body 3A.

[0119] Other points of the insertion step are the same as those of the second embodiment described above. Also, the pulling-up step, the changing step, the pushing-in step, and the joining step are the same as those of the second embodiment described above.

[0120] Here, when a stirring pin rotated forward is inserted toward the overlapping portion J3 formed by the end face 11a of the jacket body 2A and the back face 3b of the sealing body 3, the interface near the position where the stirring pin is inserted may be drawn upward by plastic flow, resulting in a decrease in the joining strength of the overlapping portion J3. Also, depending on the insertion amount of the stirring pin, the amount of the members to be joined that undergo plastic flow and convection increases, so the convection of the members to be joined that have undergone plastic flow increases as the stirring pin is inserted, and the entrainment near the interface is likely to occur, resulting in a decrease in the joining strength of the overlapping portion J3.

[0121] According to this method, in the insertion step, the stirring pin F2 is inserted toward the overlapping portion J3 while rotating the rotary tool F in the same direction as the formation direction of the spiral groove (reverse rotation). This generates upward convection in the inner portion of the plasticized region W4 around the stirring pin, while downward convection in the outer portion of the plasticized region W4. Therefore, near the start position SP3 of the overlapping portion J3, it is easy to prevent the oxide film present at the interface between the jacket main body 2A and the sealing body 3A from being rolled upward. Furthermore, according to this method, by actively ejecting the workpieces to the outside as the stirring pin F2 is inserted, the amount of workpieces that are subjected to plastic flow and undergo convection can be reduced. This makes it easy to prevent the oxide film present at the interface between the jacket main body 2 and the sealing body 3 from being rolled in. Therefore, according to this method, it is possible to suppress a decrease in the joining strength at the overlapping portion J3 between the jacket main body 2 and the sealing body 3.

[0122] 8. Third Embodiment Next, a third embodiment of the present invention will be described. In the manufacturing method of a welded body according to this embodiment, a welded body is formed by joining the same jacket body (first welded member) 2 and sealing body (second welded member) 3 as in the first embodiment, as shown in Fig. 23. This embodiment differs from the first embodiment mainly in that the joining is performed in two separate steps, a first friction stir welding step and a second friction stir welding step, and that the friction stir welding is performed by folding back the rotary tool F.

[0123] In this embodiment, friction stir welding of the joined members to the joining path is performed by a first friction stir welding process and a second friction stir welding process. In the first friction stir welding process, friction stirring is performed in a first joining range from one end side, which is the start position of the joining path by the first friction stir welding process and the second friction stir welding process, to a first point provided in the middle of the joining path. In the second friction stir welding process, friction stirring is performed in a second joining range from a second point provided in the plasticized region belonging to the first joining range generated by the first friction stir welding process to the other end side, which is the end position of the joining path by the first friction stir welding process and the second friction stir welding process. In the first friction stir welding process, the start position of the friction stirring with respect to the first joining range is set at one end side of the joining path of the joined members, and the end position of the first joining range is set as a first point provided in the middle of the joining path. In the second friction stir welding process, the start position of the friction stirring with respect to the second joining range is set at a point at the end of the plasticized region belonging to the first joining range, and the end position of the friction stirring with respect to the second joining range is set at the other end side opposite to one end side of the joining path. In the second friction stir welding process, friction stirring is performed from the start position with respect to the second joining range to a turning position set in the plasticized region belonging to the first joining range toward one end side of the joining path, and after turning back from the turning position, friction stirring of the plasticized region is performed toward the other end side of the joining path, and friction stirring of the remaining joining path is performed from the start position with respect to the second joining range again through to the end position with respect to the second joining range.

[0124] As shown in FIG. 23, in the first friction stir welding process, friction stir welding is performed from the start position SP21 via the intermediate position S21 to the end position EP21. In the second friction stir welding process, friction stir welding is performed from the start position SP22 (the same position as the end position EP21) to the turning position S22, then turning back, and then via the intermediate position E22 to the end position EP22. The joining path of the present embodiment means going around the sealing body 3 clockwise from the start position SP21 to the end position EP22. That is, the start position SP21 of the first friction stir welding process is set on one end side of the joining path by the first friction stir welding process and the second friction stir welding process. The end position EP22 of the second friction stir welding process is set on the other end side opposite to one end side of the joining path. The end position EP21 of the first friction stir welding process is set as the first point provided up to the middle of the joining path and also as the second point provided within the plasticized region belonging to the first joining range. The end position EP21 of the first friction stir welding process becomes the point at the end of the plasticized region belonging to the first joining range. The start position SP22 of the second friction stir welding process is set at the point at the end of the plasticized region belonging to the first joining range.

[0125] <The first friction stir welding process> In the first friction stir welding process, a preparation process, a butting process, an insertion process, a pulling-up process, a changing process, a pressing process, and a joining process are performed. In the first friction stir welding process, friction stir welding is performed from the start position SP21 via the intermediate positions S21 and E21 to the end position (the first point) EP21. The range from the start position SP21 to the end position EP21 is the first joining range. The start position SP21 is set on the end face 11a of the peripheral wall portion 11 on the left side in the width direction in FIG. 23. The intermediate position S21 is set on the surface 3a of the sealing body 3 in the vicinity of the start position SP21. The end position EP21 is set on the surface 3a of the sealing body 3 on the right side in the width direction in FIG. 23. The intermediate position E21 is set on the surface 3a of the sealing body 3 in the vicinity of the end position EP21.

[0126] The movement route R1 through which the rotation axis C of the rotary tool F (see FIG. 4) passes passes through the start position SP21, the intermediate positions S21 and E21, and the end position EP21. The movement route R1 is a route sandwiched between the start position SP21 which is the starting point and the end position EP21 which is the ending point, and includes an insertion section, a main section, and a detachment section. In this method, at the start position SP21, an insertion process, a pulling-up process, a changing process, and a pushing-in process are performed. Also, in this method, a joining process is performed in the insertion section, the main section, and the detachment section.

[0127] The insertion section is the section from the start position SP21 set on the end face 11a of the peripheral wall portion 11 to the intermediate position S21 set on the surface 3a of the sealing body 3. In the insertion section, the rotary tool F inserted at a predetermined depth at the start position SP21 is gradually pushed in while being moved toward the intermediate position S21.

[0128] The main section (steady section) is the section from the intermediate position S21 along the first butting portion J1 for about half a turn to the intermediate position E21 set on the surface 3a of the sealing body 3. In this main section, the movement route R1 is set slightly inside (on the side of the sealing body 3) than the first butting portion J1. In this main section, the rotary tool F is moved at a substantially constant depth.

[0129] The detachment section is the section from the intermediate position E21 to the end position EP1. In the detachment section, friction stir joining is performed by setting the insertion depth shallower than that in the main section, and the rotary tool F is separated from the sealing body 3 at the end position EP21.

[0130] The preparation process is the same as that of the first embodiment, so the description is omitted. In the butting process, the jacket body 2 and the sealing body 3 are butted against each other in the same manner as in the first embodiment to form the first butting portion J1 and the second butting portion J2. Also, one side of the jacket body 2 and the sealing body 3, that is, the lower side in FIG. 23 (the lower side of the drawing with respect to the virtual center line O1 parallel to the width direction) is clamped at three places by the clamp U1 to fix the jacket body 2 and the sealing body 3.

[0131] The insertion process is a process of inserting the rotary tool F into the member to be joined (here, the jacket body 2). In the insertion process, the rotary tool F is inserted into the starting position SP21 set on the end face 11a of the peripheral wall portion 11. Since the insertion process is the same as that of the first embodiment, the description thereof is omitted.

[0132] Since the pulling-up process, the changing process, and the pushing-in process are also the same as those of the first embodiment, the description thereof is omitted. The joining process is a process of joining the members to be joined (here, the jacket body 2 and the sealing body 3) with the rotary tool F rotated in the direction opposite to the forming direction of the spiral groove, as shown in FIG. 23. That is, in the joining process, friction stir joining is performed with the tool rotated forward.

[0133] After the rotary tool F is pushed in to a predetermined insertion depth H4 in the above-described pushing-in process, while moving the rotary tool F to the intermediate position S21, it is gradually pushed in deeper toward a position where a predetermined insertion depth (for example, the insertion depth H5) is reached. When the intermediate position S21 is reached, as shown in FIG. 24, the rotary tool F is moved along the first butting portion J1 with the rotation axis C of the rotary tool F aligned with the movement route R1. The movement route R1 and the first butting portion J1 are substantially parallel. A plasticized region W11 is formed in the movement locus of the rotary tool F.

[0134] When the rotary tool F reaches the intermediate position E21, it shifts to the detachment section. As shown in FIG. 25, In the detachment section, friction stir joining is performed with the insertion depth of the rotary tool F set shallower than that in this section. That is, after passing through the intermediate position E21, while moving the rotary tool F, it is slightly pulled up and moved a predetermined distance at the insertion depth H12. The insertion depth H12 of the rotary tool F in the detachment section is smaller than the insertion depth H11 of the rotary tool F in this section (steady section). The insertion depth refers to the distance from the surface of the member to be joined (here, the surface 3a of the sealing body 3) to the tip of the stirring pin F2.

[0135] The insertion depth H11 in this section and the insertion depth H12 in the separation section are set such that H11×0.6≦H12<H11. Preferably, they are set such that H11×0.65≦H12<H11×0.95, more preferably H11×0.7≦H12<H11×0.9, and even more preferably H11×0.75≦H12<H11×0.85. As an example, the insertion depth H11 in this section (steady part) of the first friction stir welding process is set to 0.75 mm, and the insertion depth H12 near the end position EP21 is set to 0.65 mm.

[0136] In the separation section, when the rotary tool F reaches the end position EP21, the rotary tool F is moved straight up to separate it from the surface 3a of the sealing body 3. A through hole 30 is formed in the surface 3a of the sealing body 3. After separating the rotary tool F, the clamp U1 is temporarily released, and as shown in FIG. 26, one side of the jacket body 2 and the sealing body 3 is clamped again. That is, the parts (three places above the virtual center line O1) performed in the first friction stir welding process are clamped again with the clamp U1.

[0137] <Second friction stir welding process> As shown in FIG. 26, when the first friction stir welding process is completed, the second friction stir welding process is performed. In the second friction stir welding process, a joining process is performed. In the second friction stir welding process (joining process), friction stir welding is performed from the start position (second point) SP22, turning back at the turning-back position S22, passing through the intermediate position E22, and reaching the end position EP22. The start position SP22 is in the middle of the joining path and is set within the plasticized region W11 belonging to the first joining range generated by the first friction stir welding process. Here, the start position SP22 is set at the end position EP21. The range from the start position SP22 to the turning-back position S22 and then to the end position EP22 is the second joining range.

[0138] The turning-back position S22 is set on the upstream side (start position SP21 side) of the intermediate position E21. That is, the turning-back position S22 is set such that the intermediate position E21 is located between the turning-back position S22 and the start position SP22.

[0139] The end position EP22 is set on the end face 11a of the peripheral wall portion 11 on the left side in the width direction and above the virtual center line O1 in Fig. 26. The intermediate position E22 is set on the surface 3a of the sealing body 3 in the vicinity of the end position EP22.

[0140] The movement route R1 through which the rotation axis C of the rotary tool F (see Fig. 4) passes passes through the start position SP22, the turning position S22, the intermediate position E22, and the end position EP22. The movement route R1 is a route sandwiched between the start position SP22 which is the starting point and the end position EP22 which is the end point (more specifically, the route from the turning position S22 to the end position EP22), and includes a turning section, this section, and a separation section. In this method, the joining process is performed in the turning section, this section, and the separation section.

[0141] In the joining process, the rotary tool F is inserted into the punched hole 30 (see Fig. 25) formed in the first friction stir joining process and pushed in to a predetermined depth. After pushing in the rotary tool F, it shifts to the turning section. The turning section is the section from the start position SP22 to the turning position S22, turning at the turning position S22, and returning to the start position SP22 again. In the turning section, the rotary tool F is moved while maintaining a predetermined depth toward the turning position S22. At this time, the rotary tool F is moved so that the plasticized region W12 formed in the second friction stir joining process overlaps with the plasticized region W11 formed in the first friction stir joining process. As shown in Fig. 27, from the start position SP22 to the turning position S22, the insertion depth H21 of the rotary tool F is set to be larger than the insertion depth H12 (see Fig. 25). That is, by the plasticized region W12 formed in the second friction stir joining process, it is desirable to insert and move the rotary tool F so that the entire plasticized region W11 formed in the first friction stir joining process in the depth direction is friction stir welded in the range from the start position SP22 to the turning position S22.

[0142] As shown in FIG. 28, when the rotary tool F reaches the folding position S22, the rotary tool F is folded back and moved toward the starting position SP22. As shown in FIGS. 29 and 30, the rotary tool F is moved while maintaining the insertion depth H21 between the starting position SP22 → the folding position S22 → the starting position SP22. The insertion depth H21 and the insertion depth H12 (see FIG. 25) are set such that H12 < H21 ≦ H12 × 1.7. Preferably, H12 × 1.1 < H21 ≦ H12 × 1.6, more preferably, H12 × 1.2 < H21 ≦ H12 × 1.5, and even more preferably, H12 × 1.3 < H21 ≦ H12 × 1.4. As an example, the insertion depth H12 near the end position EP21 of the first friction stir welding process is set to 0.65 mm, and the insertion depth H21 at the starting position SP22 of the second friction stir welding process is set to 0.95 mm.

[0143] As shown in FIG. 30, when the rotary tool F passes through the starting position SP22, friction stir welding of this section is performed at a constant insertion depth up to the intermediate position E22. The insertion depth H22 of the rotary tool F in this section (steady section) is set to be smaller than the insertion depth H21 (see FIG. 28). The insertion depth H22 and the insertion depth H21 are set such that H22 < H21 ≦ H22 × 1.4. Preferably, H22 × 1.05 < H21 ≦ H22 × 1.35, more preferably, H22 × 1.1 < H21 ≦ H22 × 1.3, and even more preferably, H22 × 1.15 < H21 ≦ H22 × 1.25. As an example, the insertion depth H21 in the folding section of the second friction stir welding process is set to 0.95 mm, and the insertion depth H22 in this section (steady section) is set to 0.75 mm.

[0144] As shown in FIG. 31, when the rotary tool F reaches the intermediate position E22, it shifts to the separation section. In the separation section, while moving the rotary tool F from the intermediate position E22 to the end position EP22, the rotary tool F is gradually pulled up, and the rotary tool F is detached from the jacket body 2 at the end position EP22. A joined body is formed by the above steps.

[0145] According to the method for manufacturing the joined body according to the present embodiment described above, the end position EP21 of the first joining range is also included in the second joining range, and the start position SP22 of the second joining range is included in the first joining range. Further, in the second friction stir joining step, friction stir is performed from the start position SP22 of the second joining range to the turning position S22 set in the plasticized region W11 belonging to the first joining range, and then turned at the turning position S22, and again passes through the start position SP22 for the second joining range and performs friction stir to the end position EP22 for the second joining range. In this way, in the second friction stir joining step, by moving the rotary tool F so as to pass on the movement locus in the first friction stir joining step, friction stir is performed again on the plasticized region W11 belonging to the first joining range. Even if an oxide film is caught at the end of the plasticized region W11 belonging to the first joining range or a joining defect or the like has occurred, in the second friction stir joining step, since the end of the plasticized region W11 is also friction stirred again, the oxide film remaining caught at the end is broken, and joining defects and the like are repaired. Therefore, the quality of friction stir joining is improved.

[0146] Also, in the case of a joining path that is so long that it cannot be friction stirred in one step, by performing friction stir separately, the oxide film is broken and joining defects and the like are repaired, so that high-quality friction stir can be performed for joining paths of various lengths.

[0147] Further, according to the present embodiment, in the insertion step, with the rotary tool F rotated (reverse rotation) in the same direction as the formation direction of the spiral groove, the stirring pin F2 is inserted into the workpiece (jacket body 2). Thus, when the stirring pin F2 is inserted into the workpiece, the spiral groove acts on the workpiece like the blade of a drill, and the spiral groove penetrates while shaving off the material of the workpiece. As a result, with the insertion of the stirring pin F2, the workpiece is actively discharged to the outside, and the load applied to the rotary tool F and the joining device (not shown) when inserting the rotary tool F for joining can be reduced. Also, to the extent that the load is reduced, the wear of the spiral groove of the stirring pin F2 is also reduced, and breakage of the stirring pin F2 can be reduced.

[0148] Moreover, according to the insertion process, even when a pilot hole is not provided in advance, the press-fitting resistance can be reduced and the insertion of the stirring pin F2 can be smoothly performed, thereby improving productivity. Also, in the insertion process, it is presumed that the material of the joined member that has been shaved off is discharged to the outside of the joined member as the spiral groove rotates, like the chips generated by cutting with a drill. As a result, it becomes difficult for the material that has undergone plastic fluidization and flowed out to remain as burrs on the surface of the joined member after friction stir welding. Therefore, the burden of post-treatment such as cutting for removing burrs is also reduced, and productivity can be improved.

[0149] Further, at the start position SP22 of the second friction stir welding process, by inserting the stirring pin F2 into the extraction hole 30 of the rotating tool formed by the first friction stir welding process, the extraction hole 30 of the rotating tool F in the first friction stir welding process functions as a pilot hole, reducing the press-fitting resistance and enabling the smooth insertion of the stirring pin F2, thereby improving productivity. Also, in the second friction stir welding process, by performing friction stirring through the start position SP22 with respect to the second joining range, the extraction hole 30 can be filled by the plasticized region W12 formed by friction stirring.

[0150] Further, in the present embodiment, in the first friction stir welding process, the relationship between the insertion depth H11 of the rotating tool F in this section (steady part) when performing friction stir welding on the first welding range and the insertion depth H12 of the rotating tool F near the end position EP21 in the first friction stir welding process is set to H11×0.6≦H12<H11. That is, in the steady part of the first friction stir welding process, welding is performed at the insertion depth H11, and after pulling up to the insertion depth H12 near the end position EP21 to perform welding, the rotating tool F is pulled out at the end position EP21. As a result, since the insertion depth H12 of the rotating tool F near the extraction hole 30 in the first friction stir welding process is smaller than the insertion depth H11 in this section (steady part) when performing friction stirring, the insertion depth required when inserting the rotating tool F in the second friction stir welding process is suppressed, so that the plasticized region W11 near the position of the extraction hole 30 formed in the first friction stir welding process can be easily friction stirred in the second friction stir welding process.

[0151] Also, since the insertion depth H12 near the extraction hole 30 in the first friction stir welding process is equal to or greater than a predetermined lower limit value based on the insertion depth H11 in this section (steady part), the depth and width of the joint near the extraction hole 30 can be ensured, and it becomes easier to increase the joint strength.

[0152] Further, in the present embodiment, at the start position SP22 of the second friction stir welding process, it is inserted to the insertion depth H21, and welding is performed while maintaining the insertion depth H21 until passing through the turning-back position S22 and the start position SP22. At this time, since the insertion depth H21 of the rotating tool F when inserting the rotating tool F in the second friction stir welding process is larger than the insertion depth H12 near the extraction hole 30 in the first friction stir welding process, the plasticized region W11 near the extraction hole 30 formed in the first friction stir welding process can be easily friction stirred in the second friction stir welding process.

[0153] Also, when inserting the rotary tool F in the second friction stir welding process, the insertion depth H21 of the rotary tool F is set to be equal to or less than a predetermined upper limit value based on the insertion depth H12 near the counterbore 30 in the first friction stir welding process, thereby suppressing the occurrence of defects and breakage of the rotary tool F due to an excessive increase in the insertion depth near the insertion position in the second friction stir welding process. For example, as described with reference to FIG. 2, consider the case of performing friction stir welding between the jacket body 2 provided with the peripheral wall step portion 12 having the step side surface 12b and the step bottom surface 12a and facing the recess 13, and the sealing body 3. In this case, a butting and overlapping portion is formed, which includes a first butting portion J1 formed by butting the step side surface 12b of the jacket body 2 and the side surface 3c of the sealing body 3, and a second butting portion J2 (overlapping portion J2) formed by butting (overlapping) the step bottom surface 12a of the jacket body 2 and the back surface 3b of the sealing body 3. When performing friction stir welding by inserting the rotary tool F at the position of the first butting portion J1, if the insertion depth of the rotary tool F becomes too large, buckling deformation of the material of the portion of the peripheral wall step portion 12 facing the recess 13 of the step bottom surface 12a may occur. By adjusting the insertion depth H21 of the rotary tool F when inserting the rotary tool F in the second friction stir welding process to be equal to or less than a predetermined upper limit value, the occurrence of such defects can be suppressed.

[0154] Further, in the present embodiment, the insertion is performed up to the insertion depth H21 at the start position SP22, and joining is carried out while maintaining the insertion depth H21 until passing through the turning-back position S22 and the start position SP22. Then, in this section (steady section), the insertion is pulled up to the insertion depth H22 and joining is performed. In this way, since the insertion depth H21 of the rotary tool F when inserting the rotary tool F in the second friction stir welding process is larger than the insertion depth H22 of this section (steady section) of the second friction stir welding process, it becomes easier to friction stir the plasticized region W11 near the punched hole 30 formed in the first friction stir welding process at the insertion position of the rotary tool F in the second friction stir welding process. Also, since the insertion depth H21 of the rotary tool F when inserting the rotary tool F in the second friction stir welding process is equal to or less than a predetermined upper limit value based on the insertion depth H22 of this section (steady section) of the second friction stir welding process, generation of defects and breakage of the tool due to the insertion depth H21 becoming excessively large near the start position S22 of the second friction stir welding process can be suppressed.

[0155] Also, when the joining path of the joining process is a closed loop as in the present embodiment, there is a problem that the rotary tool F and the clamp U1 interfere with each other when performing this joining process, making the operation complicated. However, according to the present embodiment, by separately performing the clamping position and the friction stir welding position in the first friction stir welding process and the second friction stir welding process, the friction stir operation can be efficiently performed.

[0156] [9. Fourth Embodiment] Next, a method for manufacturing a joined body according to the fourth embodiment of the present invention will be described. In the above-described third embodiment, the insertion process, the pulling-up process, the changing process, and the pushing process are performed at the start position SP21, but this embodiment is different in that the insertion process, the pulling-up process, the changing process, and the pushing process are performed at the start position SP22.

[0157] Also in this embodiment, similar to the third embodiment, a first friction stir welding process and a second friction stir welding process are performed. In the first friction stir welding process, as shown in FIG. 23, friction stir welding is performed from the starting position SP21, via the intermediate positions S21 and E21, to the ending position EP21. When inserting the rotating tool F at the starting position SP21, the rotation direction and the like are set as appropriate.

[0158] In the second friction stir welding, as shown in FIG. 29, the rotating tool F is inserted at the starting position SP22, moved from the starting position SP22 to the turning position S22, turned at the turning position S22, and friction stir welding is performed from the intermediate position E22 to the ending position EP22 via the intermediate position E22. At the starting position SP22, the insertion process, the lifting process, the changing process, and the pressing process described in the first embodiment are performed. In other words, in the second friction stir welding process, after performing the insertion process, the lifting process, the changing process, and the pressing process at the starting position SP22 for the second welding range, the welding process is performed. Note that in this embodiment, the lifting process and the pressing process may be omitted. Other aspects of this embodiment are substantially the same as those of the third embodiment, and thus the description thereof is omitted.

[0159] Also in this embodiment described above, effects substantially equivalent to those of the third embodiment can be obtained. Further, at the starting position SP22 of the second friction stir welding process, by inserting the stirring pin F2 at the position of the extraction hole 30 of the rotating tool F formed by the first friction stir welding process, the extraction hole 30 of the rotating tool F in the first friction stir welding process functions as a pilot hole, thereby reducing the press-fitting resistance and enabling smooth insertion of the stirring pin F2, and improving productivity. Also, in the second friction stir welding process, by performing friction stir welding through the starting position SP22 for the second welding range, the extraction hole 30 can be filled with the plasticized region W12 formed by friction stir welding.

[0160] Also, even when the size and depth of the extraction hole 30 are small due to the rotation tool F and joining conditions in the first friction stir joining process, the load applied to the rotation tool F and the joining device (not shown) can be more reliably reduced by discharging the joined member at the position of the extraction hole 30 to the outside by the insertion process in the second friction stir joining process.

[0161] Moreover, burrs may remain at the position of the extraction hole 30 of the rotation tool F formed by the first friction stir joining process. If burrs remain at the position of the extraction hole 30, these burrs become extra material and cause resistance during insertion, resulting in a load being applied to the rotation tool F and the joining device. In contrast, by the insertion process in the second friction stir joining process of the present embodiment, the burrs remaining at the end position EP21 of the first joining range can be removed as the rotation tool F rotates. Therefore, the burden of pretreatment such as cutting for removing burrs can be reduced before the second friction stir joining process, improving productivity.

[0162] [10. Fifth Embodiment] Next, the fifth embodiment of the present invention will be described. In the method for manufacturing a joined body according to this embodiment, as shown in FIG. 32, the same jacket body 2A (omitted in FIG. 32) and sealing body 3A as in the second embodiment are joined to form a joined body. This embodiment mainly differs from the first embodiment in that the joining is performed in two steps, namely the first friction stir joining process and the second friction stir joining process, and the rotation tool F is folded back to perform friction stir joining. Also, in this embodiment as well, similar to the third embodiment, the friction stir joining of the joined members to the joining path is performed by the first friction stir joining process and the second friction stir joining process. However, this embodiment differs from the third embodiment in that both the start position SP31 and the end position EP32 are set on the sealing body 3A. Regarding the correlation of the insertion depths (H11, H12, H21, H22) of the rotation tool F in this embodiment, since it is the same as that in the third embodiment, FIGS. 25, 27, 28, and 30 will be appropriately referred to for the description.

[0163] As shown in FIG. 32, in the first friction stir welding process, friction stir welding is performed from the start position SP31 via the intermediate positions S31 and E31 to the end position EP31. In the second friction stir welding process, friction stir welding is performed from the start position SP32 (the same position as the end position EP31) to the turning position S32 for turning back, and via the intermediate position E32 to the end position EP32. The joining path of the present embodiment refers to going around the sealing body 3A clockwise from the start position SP31 to the end position EP32. That is, the start position SP31 of the first friction stir welding process is set on one end side of the joining path by the first friction stir welding process and the second friction stir welding process. The end position EP32 of the second friction stir welding process is set on the other end side opposite to one end side of the joining path. The end position EP31 of the first friction stir welding process is set as the first point provided up to the middle of the joining path and is also set as the second point provided within the plasticized region belonging to the first joining range. The end position EP31 of the first friction stir welding process becomes the point at the end of the plasticized region belonging to the first joining range. The start position SP32 of the second friction stir welding process is set at the point at the end of the plasticized region belonging to the first joining range.

[0164] <The first friction stir welding process> In the first friction stir welding process, a preparation process, a superposition process, an insertion process, a pulling-up process, a changing process, a pressing process, and a joining process are performed. In the present embodiment, as shown in FIG. 19, the end face 11a of the jacket body 2A and the back face 3b of the sealing body 3A are superposed to form a superposed portion J3. In the first friction stir welding process, friction stir welding is performed from the start position SP31 via the intermediate positions S31 and E31 to the end position (first point) EP31. The range from the start position SP31 to the end position EP31 is the first joining range. The start position SP31 is set on the surface 3a of the sealing body 3A on the left side in the width direction in FIG. 32 while overlapping the superposed portion J3. The intermediate position S31 is set on the surface 3a of the sealing body 3A in the vicinity of the start position SP31 while overlapping the superposed portion J3. The end position EP31 is set on the surface 3a of the sealing body 3A on the right side in the width direction in FIG. 32 while overlapping the superposed portion J3. The intermediate position E31 is set on the surface 3a of the sealing body 3A in the vicinity of the end position EP31 while overlapping the superposed portion J3.

[0165] The movement route R3 through which the rotation axis C of the rotary tool F (see FIG. 4) passes passes through the start position SP31, the intermediate positions S31 and E31, and the end position EP31. The movement route R3 is a route sandwiched between the start position SP31 which is the starting point and the EP31 which is the end point, and includes an insertion section, a main section, and a separation section. In this method, at the start position SP31, an insertion process, a pulling-up process, a changing process, and a pressing process are performed. Also, in this method, a joining process is performed in the insertion section, the main section, and the separation section.

[0166] The insertion section is the section from the start position SP31 to the intermediate position S31 set on the surface 3a of the sealing body 3A. In the insertion section, the rotary tool F inserted at a predetermined depth at the start position SP31 is gradually pushed in while being moved to the intermediate position S31.

[0167] The main section (steady part) is the section that approximately makes a half turn along the superposed portion J3 from the intermediate position S31 to the intermediate position E31. In the main section, the rotary tool F is moved at a substantially constant depth.

[0168] The separation section is the section from the intermediate position E31 to the end position EP31. In the separation section, friction stir welding is performed with the insertion depth set shallower than this section, and the rotary tool F is separated from the sealing body 3A at the end position EP31.

[0169] The preparation process is the same as that of the second embodiment, so the description is omitted. In the overlapping process, the jacket body (member to be joined) 2A and the sealing body (member to be joined) 3A are overlapped in the same manner as in the second embodiment to form an overlapping portion J3. Also, one side of the jacket body 2A and the sealing body 3A, that is, the lower side in FIG. 32 (below the virtual center line O1 parallel to the width direction in the drawing) is clamped at three locations by a clamp U1 to fix the jacket body 2A and the sealing body 3A.

[0170] The insertion process is a process of inserting the rotary tool F into the member to be joined (here, the sealing body 3A). In the insertion process, the rotary tool F is inserted into the starting position SP31. Since the insertion process is the same as that of the first embodiment, the description is omitted.

[0171] The lifting process, the changing process, and the pressing process are also the same as those of the first embodiment, so the description is omitted. The joining process is a process of joining the members to be joined (here, the jacket body 2 and the sealing body 3) with the rotary tool F rotated in the direction opposite to the direction of formation of the spiral groove. That is, in the joining process, friction stir welding is performed while rotating forward.

[0172] After the rotary tool F is pushed in to a predetermined insertion depth H4 in the above-described pressing process, while moving the rotary tool F to the intermediate position S31, it is gradually pushed in toward a deeper position until it reaches a predetermined insertion depth (for example, the insertion depth H5). When the intermediate position S31 is reached, as shown in FIG. 33, the rotation axis C of the rotary tool F is moved along the overlapping portion J3 in a state where it is overlapped with the movement route R3. A plasticized region W21 is formed in the movement locus of the rotary tool F.

[0173] When the rotary tool F reaches the intermediate position E31, it shifts to the detachment section. In the detachment section, the rotary tool F is set to a shallower insertion depth than in this section, and friction stir welding is performed. That is, after passing through the intermediate position E31, while moving the rotary tool F, it is slightly pulled up and moved a predetermined distance at the insertion depth H12 (see Fig. 25). The insertion depth H12 of the rotary tool F in the detachment section is smaller than the insertion depth H11 of the rotary tool F in this section (steady part). The relationship between the insertion depth H11 in this section and the insertion depth H12 in the detachment section is the same as that of the third implementation diameter.

[0174] In the detachment section, when the rotary tool F reaches the end position EP31, the rotary tool F is moved straight up and detached from the surface 3a of the sealing body 3A. A through hole 30 (see Fig. 25) is formed in the surface 3a of the sealing body 3A. After detaching the rotary tool F, the clamp U1 is temporarily released, and as shown in Fig. 34, one side of the jacket body 2A and the sealing body 3A is clamped again. That is, the parts (three places above the virtual center line O1) performed in the first friction stir welding process are clamped again with the clamp U1.

[0175] <Second Friction Stir Welding Process> As shown in Fig. 34, after the first friction stir welding process is completed, the second friction stir welding process is performed. In the second friction stir welding process, a joining process is performed. In the second friction stir welding process (joining process), friction stir welding is performed from the start position (second point) SP32, turning back at the turning-back position S32, passing through the intermediate position E32, and reaching the end position EP32. The start position SP32 is in the middle of the joining path and is set within the plasticized region W21 belonging to the first joining range generated by the first friction stir welding process. Here, the start position SP32 is set at the end position EP31. The range from the start position SP32 to the turning-back position S32 and then to the end position EP32 becomes the second joining range.

[0176] The turning-back position S32 is set upstream (on the start position SP31 side) of the intermediate position E31. That is, the turning-back position S32 is set so that the intermediate position E31 is located between the turning-back position S32 and the start position SP32.

[0177] The end position EP32 is set on the surface 3a of the sealing body 3A on the upper side of the virtual center line O1 in FIG. 35 and on the left side in the width direction. The intermediate position E32 is set on the surface 3a of the sealing body 3A in the vicinity of the end position EP32.

[0178] The movement route R3 through which the rotation axis C of the rotary tool F (see FIG. 4) passes passes through the start position SP32, the turning position S32, the intermediate position E32, and the end position EP32. The movement route R3 is a route sandwiched between the start position SP32 which is the starting point and the end position EP32 which is the end point (more specifically, the route from the turning position S32 to the end position EP32), and includes a turning section, this section, and a separation section. In this method, the joining process is performed in the turning section, this section, and the separation section.

[0179] In the joining process, the rotary tool F is inserted into the punched hole 30 (see FIG. 25) formed in the first friction stir joining process and pushed in to a predetermined depth. After pushing in the rotary tool F, it moves to the turning section. The turning section is a section that moves from the start position SP32 to the turning position S32, turns at the turning position S22, and returns to the start position SP32 again. In the turning section, the rotary tool F is moved while maintaining a predetermined depth toward the turning position S32. At this time, the rotary tool F is moved so that the plasticized region W22 formed in the second friction stir joining process and the plasticized region W21 formed in the first friction stir joining process overlap. From the start position SP32 to the turning position S32, the insertion depth H21 (see FIG. 28) of the rotary tool F is set to be larger than the insertion depth H12 (see FIG. 25). That is, by the plasticized region W22 formed in the second friction stir joining process, in the range from the start position SP32 to the turning position S32, it is desirable to insert and move the rotary tool F so that the whole in the depth direction of the plasticized region W21 formed in the first friction stir joining process is friction stirred.

[0180] When the rotary tool F reaches the folding position S32, fold the rotary tool F and move it toward the starting position SP32. Move the rotary tool F while maintaining the insertion depth H21 between the starting position SP32 → the folding position S32 → the starting position SP32 (see Figs. 28 and 30). The relationship between the insertion depth H12 in the folding section and the insertion depth H21 in the withdrawal section is the same as that in the third embodiment diameter.

[0181] As shown in Fig. 35, when the rotary tool F passes through the starting position SP32, perform friction stir welding in this section up to the intermediate position E32. The insertion depth H22 of the rotary tool F in this section (steady part) (see Fig. 30) is set to be smaller than the insertion depth H21 (see Fig. 28). The relationship between the insertion depth H22 and the insertion depth H21 in this section (steady part) is the same as that in the third embodiment.

[0182] As shown in Fig. 35, when the rotary tool F reaches the intermediate position E32, shift to the withdrawal section. In the withdrawal section, gradually lift the rotary tool F while moving the rotary tool F from the intermediate position E32 to the end position EP32, and detach the rotary tool F from the sealing body 3A at the end position EP32. A joined body is formed by the above steps.

[0183] According to the method for manufacturing the joined body according to the present embodiment described above, the end position EP31 of the first joining range is also included in the second joining range, and the start position SP32 of the second joining range is included in the first joining range. Further, in the second friction stir joining process, friction stir is performed from the start position SP32 of the second joining range to the turning position S32 set in the plasticized region W21 belonging to the first joining range, and then turned back at the turning position S32, and again through the start position SP32 for the second joining range to the end position EP32 for the second joining range. Friction stir is performed up to. In this way, in the second friction stir joining process, by moving the rotary tool F so as to pass on the movement locus in the first friction stir joining process, friction stir is performed again on the plasticized region W21 belonging to the first joining range. Even if an oxide film is caught at the end of the plasticized region W21 belonging to the first joining range or a joining defect or the like occurs, in the second friction stir joining process, the end of the plasticized region W21 is also friction stirred again. Therefore, the oxide film remaining caught at the end is separated, and joining defects and the like are repaired. Therefore, the quality of friction stir joining is improved.

[0184] Further, even in the case of a joining path that is so long that it cannot be friction stirred in one process, by performing friction stir separately, the oxide film can be separated and joining defects and the like can be repaired, so that high-quality friction stir can be performed for joining paths of various lengths. Will be able to.

[0185] Further, according to the present embodiment, in the insertion step, the stirring pin F2 is inserted into the member to be joined (sealing body 3A) with the rotary tool F rotated (reverse rotation) in the same direction as the formation direction of the spiral groove. When the stirring pin F2 is inserted into the member to be joined, the spiral groove acts on the member to be joined like the blade of a drill, and the spiral groove penetrates while scraping off the material of the member to be joined. As a result, the member to be joined is actively discharged to the outside as the stirring pin F2 is inserted, and the load applied to the rotary tool F and the joining device (not shown) when the rotary tool F is inserted can be reduced. Further, the wear of the spiral groove of the stirring pin F2 can be reduced and the breakage of the stirring pin F2 can be reduced by the amount of reduction in the load.

[0186] Moreover, according to the insertion process, even when a pilot hole is not provided in advance, the press-fitting resistance can be reduced and the insertion of the stirring pin F2 can be smoothly performed, thereby improving productivity. Also, in the insertion process, it is presumed that the material of the joined member that has been shaved off is discharged to the outside of the joined member as the spiral groove rotates, like the chips generated by cutting with a drill. As a result, it becomes difficult for the material that has undergone plastic fluidization and flowed out to remain as burrs on the surface of the joined member after friction stir welding, so the burden of post-processing such as cutting for removing burrs is also reduced, improving productivity.

[0187] Moreover, at the start position SP32 of the second friction stir welding process, by inserting the stirring pin F2 into the extraction hole 30 of the rotating tool formed by the first friction stir welding process, the extraction hole 30 of the rotating tool F in the first friction stir welding process functions as a pilot hole, reducing the press-fitting resistance and enabling the smooth insertion of the stirring pin F2, thereby improving productivity. Also, in the second friction stir welding process, by performing friction stirring through the start position SP32 with respect to the second joining range, the extraction hole 30 can be filled by the plasticized region W22 formed by friction stirring.

[0188] Further, in the present embodiment, in the first friction stir welding process, the relationship between the insertion depth H11 of the rotating tool F in this section (steady state section) when performing friction stir welding on the first welding range and the insertion depth H12 of the rotating tool F near the end position EP31 in the first friction stir welding process is set to H11×0.6≦H12<H11. That is, in the steady state section of the first friction stir welding process, welding is performed at the insertion depth H11, and after pulling up to the insertion depth H12 near the end position EP31 and performing welding, the rotating tool F is withdrawn at the end position EP31. As a result, the insertion depth H12 of the rotating tool F near the extraction hole 30 in the first friction stir welding process is smaller than the insertion depth H11 in this section (steady state section) when performing friction stirring, so the insertion depth required when inserting the rotating tool F in the second friction stir welding process is suppressed, and the plasticized region W21 near the position of the extraction hole 30 formed in the first friction stir welding process is easily friction stirred in the second friction stir welding process.

[0189] Also, since the insertion depth H12 near the extraction hole 30 in the first friction stir welding process is equal to or greater than a predetermined lower limit value based on the insertion depth H11 in this section (steady state section), the depth and width of the joint near the extraction hole 30 can be ensured, and it becomes easier to increase the joint strength.

[0190] Further, in the present embodiment, at the start position SP32 of the second friction stir welding process, it is inserted to the insertion depth H21, and welding is performed while maintaining the insertion depth H21 until passing through the turning-back position S32 and the start position SP32. At this time, since the insertion depth H21 of the rotating tool F when inserting the rotating tool F in the second friction stir welding process is larger than the insertion depth H12 near the extraction hole 30 in the first friction stir welding process, the plasticized region W21 near the extraction hole 30 formed in the first friction stir welding process is easily friction stirred in the second friction stir welding process.

[0191] In addition, by setting the insertion depth H21 of the rotary tool F when inserting the rotary tool F in the second friction stir welding process to be equal to or less than a predetermined upper limit value based on the insertion depth H12 near the counterbore 30 in the first friction stir welding process, it is possible to suppress the occurrence of defects and damage to the rotary tool F due to the insertion depth becoming excessively large near the insertion position in the second friction stir welding process. For example, as described with reference to FIG. 2, consider the case of performing friction stir welding between a jacket body 2 provided with a peripheral wall step portion 12 having a step side surface 12b and a step bottom surface 12a and facing the recess 13, and a sealing body 3. In this case, a butting and overlapping portion is formed, which includes a first butting portion J1 formed by butting the step side surface 12b of the jacket body 2 and the side surface 3c of the sealing body 3, and a second butting portion J2 (overlapping portion J2) formed by butting (overlapping) the step bottom surface 12a of the jacket body 2 and the back surface 3b of the sealing body 3. When performing friction stir welding by inserting the rotary tool F at the position of the first butting portion J1, if the insertion depth of the rotary tool F becomes too large, buckling deformation of the material of the portion of the peripheral wall step portion 12 facing the recess 13 of the step bottom surface 12a may occur. By adjusting the insertion depth H21 of the rotary tool F when inserting the rotary tool F in the second friction stir welding process to be equal to or less than a predetermined upper limit value, the occurrence of such defects can be suppressed.

[0192] Also, in the present embodiment, it is inserted up to the insertion depth H21 at the start position SP32, and joining is performed while maintaining the insertion depth H21 until passing through the turning-back position S32 and the start position SP32. Then, in this section (steady section), it is pulled up to the insertion depth H22 and joining is performed. In this way, since the insertion depth H21 of the rotary tool F when inserting the rotary tool F in the second friction stir welding process is larger than the insertion depth H22 in this section (steady section) of the second friction stir welding process, the plasticized region W21 near the punched hole 30 formed in the first friction stir welding process is easily friction stirred at the insertion position of the rotary tool F in the second friction stir welding process. Also, since the insertion depth H21 of the rotary tool F when inserting the rotary tool F in the second friction stir welding process is equal to or less than a predetermined upper limit value based on the insertion depth H21 of the insertion depth H22 in this section (steady section) of the second friction stir welding process, generation of defects and breakage of the tool due to the insertion depth H21 becoming excessively large near the start position SP32 of the second friction stir welding process can be suppressed.

[0193] Also, when the joining path of the joining process is a closed loop as in the present embodiment, there is a problem that the rotary tool F and the clamp U1 interfere with each other when performing this joining process, making the work complicated. However, according to the present embodiment, by separately performing the clamping position and the friction stir welding position in the first friction stir welding process and the second friction stir welding process, the friction stir welding operation can be efficiently performed.

[0194] [11. Sixth Embodiment] Next, a method for manufacturing a joined body according to the sixth embodiment of the present invention will be described. In the above-described fifth embodiment, the insertion process, the pulling-up process, the changing process, and the pushing-in process are performed at the start position SP31, but this embodiment is different in that the insertion process, the pulling-up process, the changing process, and the pushing-in process are performed at the start position SP32.

[0195] Also in this embodiment, similar to the fifth embodiment, a first friction stir welding process and a second friction stir welding process are performed. In the first friction stir welding process, as shown in FIG. 32, friction stir welding is performed from the starting position SP31 via the intermediate positions S31 and E31 to the ending position EP31. When inserting the rotary tool F at the starting position SP31, the rotation direction and the like are set as appropriate.

[0196] In the second friction stir welding, as shown in FIG. 34, the rotary tool F is inserted at the starting position SP32, turned back at the turning-back position S32, and friction stir welding is performed via the intermediate position E32 to the ending position EP32. At the starting position SP32, the insertion process, the pulling-up process, the changing process, and the pushing-in process described in the first embodiment are performed. In other words, in the second friction stir welding process, at the starting position SP32 for the second welding range with respect to the friction stir welding, after performing the insertion process, the pulling-up process, the changing process, and the pushing-in process, the welding process is performed. Note that in this embodiment, the pulling-up process and the pushing-in process may be omitted. Regarding other points of this embodiment, since they are substantially the same as those of the fifth embodiment, the description is omitted.

[0197] Also in this embodiment described above, effects substantially equivalent to those of the fifth embodiment can be obtained. Further, at the starting position SP32 of the second friction stir welding process, by inserting the stirring pin F2 at the position of the through hole 30 of the rotary tool F formed by the first friction stir welding process, the through hole 30 of the rotary tool F in the first friction stir welding process functions as a pilot hole, so that the press-fitting resistance can be reduced and the insertion of the stirring pin F2 can be smoothly performed, and the productivity can be improved. Also, in the second friction stir welding process, by performing friction stir welding through the starting position SP32 for the second welding range, the through hole 30 can be filled with the plasticized region W22 formed by the friction stir welding.

[0198] Further, even when the size and depth of the extraction hole 30 are small due to the rotary tool F and joining conditions in the first friction stir joining process, the member to be joined at the position of the extraction hole 30 can be discharged to the outside by the insertion process in the second friction stir joining process, thereby reducing the load applied to the rotary tool F and the joining device (not shown) with higher certainty.

[0199] In addition, burrs may remain at the position of the extraction hole 30 of the rotary tool F formed by the first friction stir joining process. If burrs remain at the position of the extraction hole 30, these burrs become extra material and cause resistance during insertion, resulting in a load being applied to the rotary tool F and the joining device. On the other hand, by the insertion process in the second friction stir joining process of the present embodiment, as the rotary tool F rotates, the burrs remaining at the end position EP31 of the first joining range can be removed. Therefore, before the second friction stir joining process, the burden of pretreatment such as cutting for removing burrs can also be reduced, improving productivity.

[0200] [12. Others] Although the embodiments of the present invention have been described above, design changes can be made as appropriate. For example, the third embodiment and the fourth embodiment may be combined. In this case, the insertion process, the pulling-up process, the changing process, and the pushing-in process are performed at both the start position SP21 of the first friction stir joining process and the start position SP22 of the second friction stir joining process.

[0201] Also, the fifth embodiment and the sixth embodiment may be combined. In this case, the insertion process, the pulling-up process, the changing process, and the pushing-in process are performed at both the start position SP31 of the first friction stir joining process and the start position SP32 of the second friction stir joining process

[0202] In addition, in the third to sixth embodiments, the first to fourth modification examples of the first embodiment can be combined. Also, in the fifth and sixth embodiments, the first modification example of the second embodiment can be combined.

[0203] Regarding the relationship between the insertion depth H12 and the insertion depth H21, and the relationship between the insertion depth H21 and the insertion depth H22, it is sufficient that these relationships hold around the end positions EP21 and EP22 of the plasticized regions W11,21 belonging to at least the first joining range. These relationships may hold throughout the entire range, or may hold only in part.

Example

[0204] To confirm the effects of the present invention, Test 1 and Test 2 were conducted. Test 1 and Test 2 did not join two members, but rather confirmed the friction stir state by the rotary tool F using a single member. FIG. 36 is a table showing the conditions of the shape, rotation direction, and tool rotation speed of the rotary tool in Test 1 and Test 2. FIG. 37 is a table showing the moving speed, insertion depth, pulling-up amount / insertion amount, evaluation, and alloy type in Test 1 and Test 2.

[0205] [Test 1] In Test 1, a test piece (A1050) was prepared, and friction stirring was performed at a predetermined distance using the rotary tool F. The outer diameter of the shoulder portion F1 of the rotary tool F was 30 mm, the outer diameter of the base end of the stirring pin F2 was 14 mm, and the outer diameter of the tip of the stirring pin F2 was 9.2 mm. The length L1 of the stirring pin F2 was 15 mm, and the spiral groove was left-handed. The joining speed was 125 mm / min.

[0206] <Test Example 11> Fig. 38 is a plan view showing the friction stir state of Test Example 11. Fig. 39 is a sectional view taken along line XXXIX-XXXIX of Fig. 38. In Test Example 11, after inserting a rotary tool F having a left-handed stirring pin F2 with a spiral groove at the starting position SP11 in a left rotation, the rotary tool F was pulled up, the rotation direction was changed to a right rotation, and after pushing in the rotary tool F, friction stirring was performed. In Test Example 11, the rotational speed of the rotary tool F at the time of insertion was 2000 rpm, the rotational speed of the rotary tool F at the time of pulling up was 2000 rpm, the rotational speed of the rotary tool F at the time of pushing in was 890 rpm, and the rotational speed of the rotary tool F at the time of friction stir welding was 890 rpm. Also, in Test Example 11, the insertion depth H1 at the time of insertion was 15 mm, the pulling-up amount H2 at the time of pulling up was 1 mm, the insertion depth at the time of pulling up (when changing the rotation direction) was 14 mm, the insertion amount H3 at the time of pushing in was 0.5 mm, the insertion depth H4 after pushing in was 15.5 mm, and the insertion depth H5 at the time of friction stir welding was 15.5 mm. In Test Example 11, as shown in Fig. 38, the burr V11 at the starting position SP11 was less than that in Comparative Test Examples 11 and 12. Also, as shown in Fig. 39, there were no tunnel-shaped defects in the plasticized region W11.

[0207] <Comparative Test Example 11> Fig. 40 is a plan view showing the friction stir state of Comparative Test Example 11. Fig. 41 is a sectional view taken along line XLI-XLI of Fig. 40. In Comparative Test Example 11, after inserting a rotary tool F having a left-handed stirring pin F2 with a spiral groove at the starting position SP12 in a right rotation, it was inserted to the depth at which friction stir welding was to be performed, and friction stirring was performed as it was in a right rotation. The rotational speed of the rotary tool F at the time of insertion was 890 rpm, and the rotational speed of the rotary tool F at the time of friction stir welding was also 890 rpm. Also, the insertion depth at the time of insertion was 15.5 mm, and the insertion depth H5 at the time of friction stir welding was 15.5 mm. As shown in Figs. 40 and 41, in Comparative Test Example 11, there were no tunnel-shaped defects in the plasticized region W12. However, as shown in Fig. 40, a large amount of burr V12 occurred at the starting position SP12.

[0208] <Comparative Test Example 12> Figure 42 is a plan view showing the friction stir state of Comparative Test Example 12. Figure 43 is an enlarged plan view at the starting position of Figure 42. Figure 44 is a cross-sectional view taken along line XLIV-XLIV of Figure 42. In Comparative Test Example 12, after inserting a rotary tool F having a left-handed stirring pin F2 with a spiral groove at the starting position SP13 in a right rotation, the rotary tool F was pulled up, pushed in without changing the rotation direction, and then friction stir was performed in the right rotation as it was. In Comparative Test Example 12, the rotational speed of the rotary tool F at the time of insertion, the rotational speed of the rotary tool F at the time of pulling up, the rotational speed of the rotary tool F at the time of pushing in, the rotational speed of the rotary tool F at the time of friction stir joining, the insertion depth H1 at the time of insertion, the pulling-up amount H2 at the time of pulling up, the insertion depth at the time of pulling up, the insertion amount H3 at the time of pushing in, the insertion depth H4 after pushing in, and the insertion depth H5 at the time of friction stir joining were carried out in the same manner as in Test Example 11. In Comparative Test Example 12, as shown in Figure 44, there were no tunnel-shaped defects in the plasticized region W13. However, as shown in Figures 42 and 43, a large amount of burrs V13 occurred at the starting position SP13.

[0209] <Comparative Test Example 13> Figure 45 is a plan view showing the friction stir state of Comparative Test Example 13. Figure 46 is an enlarged plan view at the starting position of Figure 45. Figure 47 is a cross-sectional view taken along line XLVII-XLVII of Figure 45. In Comparative Test Example 13, after inserting a rotary tool F having a left-handed stirring pin F2 with a spiral groove at the starting position SP14 in a left rotation, the rotary tool F was pulled up, pushed in without changing the rotation direction, and then friction stir was performed in the left rotation as it was. In Comparative Test Example 13, the rotational speed of the rotary tool F at the time of insertion, the rotational speed of the rotary tool F at the time of pulling up, the rotational speed of the rotary tool F at the time of pushing in, the rotational speed of the rotary tool F at the time of friction stir joining, the insertion depth H1 at the time of insertion, the pulling-up amount H2 at the time of pulling up, the insertion depth at the time of pulling up, the insertion amount H3 at the time of pushing in, the insertion depth H4 after pushing in, and the insertion depth H5 at the time of friction stir joining were carried out in the same manner as in Test Example 1. In Comparative Test Example 13, as shown in Figures 45 and 46, the burrs V14 at the starting position SP14 were less than those in Comparative Test Examples 11 and 12. However, as shown in Figure 47, tunnel-shaped defects T14 occurred in the plasticized region W14.

[0210] [Test 2] In Test 2, a test material (A5052) was prepared, and friction stirring was performed at a predetermined distance using a rotary tool F. The dimensions of each part of the rotary tool F were the same as those in Test 1. The spiral groove of the stirring pin F2 was left-handed. The joining speed was 100 mm / min.

[0211] <Test Example 21> FIG. 48 is a plan view showing the friction stirring state of Test Example 21. FIG. 49 is an enlarged plan view at the starting position of FIG. 48. In Test Example 21, after inserting a rotary tool F provided with a stirring pin F2 having a left-handed spiral groove at the starting position SP15 in a counterclockwise rotation, the rotary tool F was pulled up, the rotation direction was changed to clockwise rotation, and after pushing in the rotary tool F, friction stirring was performed. The rotational speed of the rotary tool F at the time of insertion was 2000 rpm, the rotational speed of the rotary tool F at the time of pulling up was 2000 rpm, the rotational speed of the rotary tool F at the time of pushing in was 400 rpm, and the rotational speed of the rotary tool F at the time of friction stirring was 400 rpm. Also, in Test Example 21, the insertion depth H1 at the time of insertion was 15 mm, the pulling-up amount H2 at the time of pulling up was 1 mm, the insertion depth at the time of changing the rotation direction was 14 mm, the insertion amount H3 at the time of pushing in was 0.5 mm, the insertion depth H4 after pushing in was 15.5 mm, and the insertion depth H5 at the time of friction stir welding was 15.5 mm. In Test Example 21, as shown in FIGS. 48 and 49, the burr V15 at the starting position SP15 was less than those in Comparative Test Examples 21 and 22.

[0212] <Test Example 22> FIG. 50 is a plan view showing the friction stir state of Test Example 22. FIG. 51 is an enlarged plan view at the starting position of FIG. 50. FIG. 52 is a sectional view taken along line LII-LII of FIG. 50. In Test Example 22, after inserting a rotary tool F provided with a left-handed stirring pin F2 having a spiral groove at the starting position SP16 in a left rotation, the rotary tool F was pulled up, the rotation direction was changed to a right rotation, and after pushing in the rotary tool F, friction stirring was performed. In Test Example 22, it was carried out in the same manner as Test Example 21 except that the rotation speed of the rotary tool F at the time of insertion was changed to 400 rpm and the rotation speed of the rotary tool F at the time of pulling up was changed to 400 rpm. As shown in FIGS. 51 and 52, the burr V16 at the starting position SP16 was less than those in Comparative Test Examples 21 and 22. Further, as shown in FIG. 52, no defect was found in the plasticized region W16.

[0213] <Comparative Test Example 21> FIG. 53 is a plan view showing the friction stir state of Comparative Test Example 21. FIG. 54 is an enlarged plan view at the starting position of FIG. 53. In Comparative Test Example 21, after inserting a rotary tool F provided with a left-handed stirring pin F2 having a spiral groove at the starting position SP17 in a right rotation, it was inserted to the depth at which friction stir welding was performed, and friction stirring was performed as it was in a right rotation. In Comparative Test Example 21, the rotation speed of the rotary tool F at the time of insertion was 400 rpm, and the rotation speed of the rotary tool F at the time of friction stir welding was 400 rpm. Further, in Comparative Test Example 21, the insertion depth at the time of insertion was 15.5 mm, and the insertion depth H5 at the time of friction stir welding was 15.5 mm. In Comparative Test Example 21, as shown in FIGS. 53 and 54, a large amount of burr V17 was generated at the starting position SP17.

[0214] <Comparative Test Example 22> FIG. 55 is a plan view showing the friction stir state of Comparative Test Example 22. FIG. 56 is an enlarged plan view at the starting position of FIG. 55. FIG. 57 is a sectional view taken along line LVII-LVII of FIG. 55. In Comparative Test Example 22, after inserting the rotary tool F provided with the left-handed stirring pin F2 in the spiral groove at the starting position SP18 in the right rotation, the rotary tool F was pulled up, and after pushing in the rotary tool F without changing the rotation direction, friction stirring was performed as it was in the right rotation. In Comparative Test Example 22, the rotational speed of the rotary tool F at the time of insertion, the rotational speed of the rotary tool F at the time of pulling up, the rotational speed of the rotary tool F at the time of pushing in, the rotational speed of the rotary tool F at the time of friction stir joining, the insertion depth H1 at the time of insertion, the pulling-up amount H2 at the time of pulling up, the insertion depth at the time of pulling up, the insertion amount H3 at the time of pushing in, the insertion depth H4 after pushing in, and the insertion depth H5 at the time of friction stir joining were carried out in the same manner as in Test Example 21. In Comparative Test Example 2, as shown in FIG. 57, there were no tunnel-shaped defects in the plasticized region W18. However, as shown in FIGS. 55 and 56, a large amount of burrs V18 occurred at the starting position SP18.

[0215] As described above, as in Comparative Test Examples 11, 12, 21, and 22, when the rotary tool F is inserted in the forward rotation (left-handed spiral groove with right rotation or right-handed spiral groove with left rotation) at the starting positions SP12, SP13, SP17, and SP18, it was found that a large amount of burrs V12, V13, V17, and V18 were generated at the starting positions SP12, SP13, SP17, and SP18, respectively. On the other hand, as in Test Examples 11, 21, and 22, when the rotary tool F is inserted in the reverse rotation (left-handed spiral groove with left rotation or right-handed spiral groove with right rotation) at the starting positions SP11, SP15, and SP16 and then friction stirring is performed in the forward rotation, it was found that the burrs V11, V15, and V16 were reduced at the starting positions SP11, SP15, and SP16, respectively.

[0216] Also, as in Comparative Test Example 13, when the rotary tool F is rotated in the reverse direction (left-handed spiral groove with left rotation or right-handed spiral groove with right rotation) during friction stir joining, it was found that tunnel-shaped defects T14 occurred. On the other hand, as in Test Examples 11, 21, and 22, it was found that when the rotary tool F was inserted in the forward rotation (the spiral groove is left-handed and rotates to the right or right-handed and rotates to the left) during friction stir welding, the joining condition was good.

[0217] That is, as in the present invention, by rotating in the reverse direction during insertion (insertion process) and rotating in the forward direction during friction stir welding (joining process), it was found that burrs at the starting position can be reduced and defects during friction stir welding can be eliminated.

Explanation of Reference Numerals

[0218] 1 Liquid cooling jacket (joined body) 2 Jacket body (first member to be joined) 3 Sealing body (second member to be joined) F Rotary tool F2 Stirring pin G Rotary tool G1 Base G2 Base end side pin G3 Tip end side pin J1 First butting part (butting part) J2 Second butting part (butting part) J3 Overlapping part H1, H4, H5, H11, H12, H21, H22 Insertion depth H2 Pull-up amount H3 Insertion amount K Rotary tool K1 Base K2 Stirring pin N1, N2 Rotation speed L1 Length of stirring pin R1, R2, R3 Movement route U1 Clamp SP1, SP2, SP3, SP21, SP22, SP31, SP32 Starting position EP1, EP3, EP21, EP22, EP31, EP32 Ending position W, W11, W12, W21, W22 Plasticized region

Claims

1. A method for manufacturing a joined body by friction stir joining between joined members into a joining path using a rotary tool having a stirring pin formed with a spiral groove, comprising: a first friction stir joining step of performing friction stir from one end side of the joining path to a first joining range up to a first point provided midway in the joining path; a second friction stir joining step of performing friction stir from a second point provided within a plasticized region belonging to the first joining range generated by the first friction stir joining step to a second joining range up to the other end side of the joining path; In the first friction stir joining step, the start position of the friction stir for the first joining range is set at one end side of the joining path of the joined members, and the end position of the first joining range is set as the first point provided midway in the joining path; In the second friction stir joining step, the start position of the friction stir for the second joining range is set at a point at the end of the plasticized region belonging to the first joining range, the end position of the friction stir for the second joining range is set at the other end side of the joining path opposite to the one end side, and friction stir is performed from the start position for the second joining range to a turning-back position set in the plasticized region belonging to the first joining range toward one end side of the joining path, and after turning back from the turning-back position, friction stir is performed in the plasticized region toward the other end side of the joining path, and then friction stir is performed on the remaining joining path from the start position for the second joining range through the end position for the second joining range; In the second friction stir joining step, at the start position of the friction stir for the second joining range, an insertion step of inserting the stirring pin into the joined member with the rotary tool rotated in the same direction as the formation direction of the spiral groove; a changing step of changing the rotation direction of the rotary tool to rotate in the direction opposite to the formation direction of the spiral groove; a joining step of joining the joined members with the rotary tool rotated in the direction opposite to the formation direction of the spiral groove, sequentially provided; A method for manufacturing a joined body, characterized by the above.

2. The method for manufacturing a joined body according to claim 1, wherein in the second friction stir joining step, the start position of the friction stir for the second joining range is the position of the through hole formed by the first friction stir joining step.

3. In the first friction stir welding process, the relationship between the insertion depth H11 of the rotating tool at the steady state portion when performing friction stir welding on the first welding range and the insertion depth H12 of the rotating tool near the end position in the first friction stir welding process is H11×0.6≦H12<H11. The method for manufacturing a joined body according to claim 1.

4. In the first friction stir welding process, the relationship between the insertion depth H12 of the rotating tool near the end position and the insertion depth H21 of the rotating tool when inserting the stirring pin at the start position in the second friction stir welding process is H12<H21≦H12×1.

7. The method for manufacturing a joined body according to claim 1.

5. In the second friction stir welding process, the relationship between the insertion depth H21 of the rotating tool when inserting the stirring pin at the start position and the insertion depth H22 of the rotating tool at the steady state portion when performing friction stir welding on the second welding range is H22<H21≦H22×1.

4. The method for manufacturing a joined body according to claim 1.

6. The rotational speed of the rotating tool in the insertion process is equal to or higher than the rotational speed of the rotating tool in the joining process. The method for manufacturing a joined body according to claim 1.

7. The relationship between the rotational speed N1 of the rotating tool in the insertion process and the rotational speed N2 of the rotating tool in the joining process is N2≦N1≦N2×5. The method for manufacturing a joined body according to claim 6.

8. After the insertion process, a lifting process of lifting the rotating tool toward the surface direction of the workpiece is further provided. After the lifting process, the changing process is performed. The method for manufacturing a joined body according to claim 1.

9. The relationship between the insertion depth H1 of the rotating tool in the insertion process and the lifting amount H2 in the lifting process is H1×0.01≦H2≦H1×0.

5. The method for manufacturing a joined body according to claim 8.

10. After the changing process, a pressing process of pressing the rotating tool toward the depth direction of the workpiece is further provided. After the pressing process, the joining process is performed. The method for manufacturing a joined body according to claim 1.

11. The relationship between the insertion depth H1 of the rotating tool in the insertion process and the insertion amount H3 in the pressing process is H1×0.01≦H3≦H1×0.

5. The method for manufacturing a joined body according to claim 10.

12. The method for manufacturing a joined body according to claim 10, wherein the relationship between the insertion depth H1 of the rotary tool in the insertion step and the insertion depth H4 when starting joining in the joining step is H1×1.01≦H4≦H1×1.

5.

13. The rotary tool is provided with a lower end surface that is planar or mortar-shaped, and further has a shoulder portion that is columnar or trapezoidal. The stirring pin hangs down from the lower end surface of the shoulder portion. The method for manufacturing a joined body according to claim 1, wherein the shoulder portion is brought into contact with the member to be joined, and friction stir joining is performed on the member to be joined with the stirring pin inserted into the member to be joined.

14. The method for manufacturing a joined body according to claim 13, wherein the relationship between the insertion depth H1 of the rotary tool in the insertion step and the length L1 of the stirring pin is L1×0.5≦H1≦L1.

15. The rotary tool has a base portion that is columnar or trapezoidal. The stirring pin hangs down from the lower end surface of the base portion. The method for manufacturing a joined body according to claim 1, wherein the base portion is separated from the member to be joined, and friction stir joining is performed on the member to be joined with only the stirring pin inserted into the member to be joined.

16. The rotary tool has a base portion that is columnar or trapezoidal. The stirring pin has a proximal-side pin continuous with the base portion and a distal-side pin continuous with the proximal-side pin. The taper angle of the proximal-side pin is larger than the taper angle of the distal-side pin, and a stepped pin step portion is formed on the outer peripheral surface of the proximal-side pin. The method for manufacturing a joined body according to claim 1, wherein friction stir joining is performed on the member to be joined with the outer peripheral surface of the proximal-side pin in contact with the surface of the member to be joined.

17. The method further includes a pilot hole forming step of forming a pilot hole in the member to be joined before the insertion step. The method for manufacturing a joined body according to claim 1, wherein in the insertion step, the stirring pin is inserted into the pilot hole.

18. The member to be joined is composed of a first member to be joined and a second member to be joined having a lower hardness than the first member to be joined. At least one end surface of the first member to be joined and the second member to be joined is butted to form a butted portion, or the back surface of the second member to be joined is overlapped on the surface of the first member to be joined to form an overlapping portion. In the insertion step, a stirring pin is inserted from the surface of the first member to be joined, The method for manufacturing a joined body according to claim 1, wherein in the joining step, friction stir joining of the butting portion or the overlapping portion is performed.

19. The members to be joined include a first member to be joined and a second member to be joined, An end face of at least one of the first member to be joined and the second member to be joined is butted to form a butting portion, or the back surface of the second member to be joined is overlapped on the surface of the first member to be joined to form an overlapping portion, The method for manufacturing a joined body according to claim 1, wherein in the insertion step, a stirring pin is inserted toward the butting portion or the overlapping portion.

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