Method for manufacturing welded body

Abstract

The present invention is characterized by including: a first friction stir welding step in which friction stirring is performed in a first welding range that extends from one end side of a welding path to a first point disposed along the welding path; and a second friction stir welding step in which friction stirring is performed from a second point disposed within a region of plasticization included in the first welding range to a second welding range. The invention is also characterized in that the first friction stir welding step comprises, in sequence: an insertion step in which, at a start position (SP21), in a state in which a rotating tool (F) has been made to rotate in the same direction as a direction of formation of a helical groove, a stirring pin is inserted into a member to be welded; an alteration step in which the direction of rotation of the rotating tool (F) is altered so as to rotate in the direction opposite the direction of formation of the helical groove; and a welding step in which, in a state in which the rotating tool (F) has been made to rotate in the direction opposite the direction of formation of the helical groove, the member to be welded is welded.

Description

Manufacturing method of the bonded body

[0001] The present invention relates to a method for producing a bonded body.

[0002] A method for producing a welded body by friction stir welding workpieces using a rotary tool having a stirring pin with a spiral groove formed thereon is known. Typically, when the spiral groove is formed counterclockwise (left-handed thread) from the base end to the tip, the rotary tool is rotated clockwise to insert the stirring pin into the workpieces, and friction stir welding is performed. On the other hand, when the spiral groove is formed clockwise (right-handed thread) from the base end to the tip, the rotary tool is rotated counterclockwise to insert the stirring pin into the workpieces, and friction stir welding is performed. That is, the rotary tool is rotated in the direction opposite to the direction in which the spiral groove is formed (hereinafter, this mode will be referred to as "forward rotation"), and the stirring pin is inserted into the workpieces, and friction stir welding is performed (Patent Document 1).

[0003] By performing friction stir welding with forward rotation, the plastically flowed material of the workpieces can be guided toward the tip of the stirring pin. This increases the plastic flow around the tip, allowing for stable welding in the deeper parts of the weld and forming a sound weld. It also reduces the amount of metal spilling outside the workpieces.

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

[0005] Japanese Patent Laid-Open No. 10-249551 Japanese Patent Laid-Open No. 2002-035962

[0006] When friction stir welding is performed by forward rotation (the direction of forming the spiral groove is opposite to the direction of rotation of the rotary tool) as described in Patent Document 1, contact between the stirring pin and the workpieces causes plastic flow of the workpieces, and as the stirring pin is inserted, the plastically fluidized material of the workpieces overflows outside the workpieces in accordance with the volume of the stirring pin. This overflowing plastically fluidized material of the workpieces solidifies, causing the problem of numerous burrs on the surfaces of the workpieces after welding.

[0007] Furthermore, when friction stir welding is performed with forward rotation, the plastically flowed material of the workpieces is pressed toward the tip of the stirring pin to perform friction stirring, which may increase the load on the welding device that rotates the rotary tool. Furthermore, if the workpieces are relatively hard, the rotary tool may be damaged. Furthermore, when friction stir welding is performed by inserting the stirring pin with forward rotation while two workpieces are overlapped, convection occurs in the plastically flowed material of the workpieces, which may cause the oxide film of the workpieces present at the overlapping surface (overlapped portion) to be lifted up, resulting in defects in the weld.

[0008] On the other hand, when friction stir welding is performed by reverse rotation (the direction of forming the spiral groove is the same as the direction of rotation of the rotating tool) as described in Patent Document 2, it is said that excessive upward convection and entrainment of the interface that occur in the plastic flow region can be suppressed. However, in this case, there may be a shortage of material at the tip side of the stir pin, which may cause internal defects.

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

[0010] (1) A method for manufacturing a welded body by friction stir welding a welding path between workpieces using a rotary tool having a stirring pin on which a spiral groove is formed, the method comprising: a first friction stir welding process in which friction stir welding is performed in a first welding range from one end of the welding path to a first point provided midway along the welding path; and a second friction stir welding process in which friction stir welding is performed in a second welding range from a second point provided in a plasticized region belonging to the first welding range generated by the first friction stir welding process to the other end of the welding path, wherein in the first friction stir welding process, a start position of friction stir welding for the first welding range is set on one end side of the welding paths between the workpieces, and an end position of the first welding range is set as the first point provided midway along the welding path; and in the second friction stir welding process, a start position of friction stir welding for the second welding range is set at a point at the end of the plasticized region belonging to the first welding range, and an end position of friction stir welding for the second welding range is set opposite to the one end side. a second welding range for the first workpiece to be joined, the second welding range being set at the other end of the pair of welding paths, and friction stirring is performed from the start position for the second welding range toward one end of the welding path to a turn-back position set in the plasticized region belonging to the first welding range, and the first friction stir welding process turns back from the turn-back position toward the other end of the welding path to perform friction stirring in the plasticized region, and then friction stirring is performed on the remaining welding path through the start position for the second welding range to an end position for the second welding range, and the first friction stir welding process sequentially comprises an insertion process of inserting the stirring pin into the workpieces while rotating the rotary tool in the same direction as the formation direction of the spiral groove, a change process of changing the rotation direction of the rotary tool so that the rotating tool is rotated in the opposite direction to the formation direction of the spiral groove, and a welding process of joining the workpieces while rotating the rotary tool in the opposite direction to the formation direction of the spiral groove. (2) The method for manufacturing a joined body according to (1), wherein in the second friction stir welding process, a starting position of friction stir welding for the second joining area is the position of a blowhole formed by the first friction stir welding process.(3) The method for manufacturing a welded body according to (1), wherein in the first friction stir welding step, a relationship between an insertion depth H11 of the rotary tool in a steady portion when friction stir welding is performed on the first welding area and an insertion depth H12 of the rotary tool near the end position in the first friction stir welding step satisfies H11 × 0.6 ≦ H12 < H11. (4) The method for manufacturing a welded body according to (1), wherein a relationship between an insertion depth H12 of the rotary tool near the end position in the first friction stir welding step and an insertion depth H21 of the rotary tool when inserting the stir pin to the start position in the second friction stir welding step satisfies H12 < H21 ≦ H12 × 1.7. (5) The method for manufacturing a welded body according to (1), wherein in the second friction stir welding process, a relationship between an insertion depth H21 of the rotary tool when inserting a stirring pin into the start position and an insertion depth H22 of the rotary tool in a steady portion when performing friction stir welding on the second welding area in the second friction stir welding process satisfies H22 < H21 ≦ H22 × 1.4. (6) The method for manufacturing a welded body according to (1), wherein a rotation speed of the rotary tool in the inserting process is equal to or greater than a rotation speed of the rotary tool in the welding process. (7) The method for manufacturing a welded body according to (6), wherein a relationship between a rotation speed N1 of the rotary tool in the inserting process and a rotation speed N2 of the rotary tool in the welding process satisfies N2 ≦ N1 ≦ N2 × 5. (8) The method for manufacturing a welded body according to (1), further comprising a pulling-up process of pulling up the rotary tool toward surfaces of the workpieces after the inserting process, and wherein the changing process is performed after the pulling-up process. (9) The method for manufacturing a joined body according to (8), wherein the relationship between an insertion depth H1 of the rotary tool in the inserting step and a pull-up amount H2 in the pulling-up step is H1 x 0.01 ≦ H2 ≦ H1 x 0.5. (10) The method for manufacturing a joined body according to (1), further comprising, after the changing step, a pushing step of pushing the rotary tool in a depth direction of the workpieces, and performing the joining step after the pushing step. (11) The method for manufacturing a joined body according to (10), wherein the relationship between an insertion depth H1 of the rotary tool in the inserting step and an insertion amount H3 in the pushing step is H1 x 0.01 ≦ H3 ≦ H1 x 0.5.(12) The method for manufacturing a welded body according to (10), wherein the relationship between an insertion depth H1 of the rotary tool in the inserting step and an insertion depth H4 at the start of welding in the welding step is H1 × 1.01 ≦ H4 ≦ H1 × 1.5. (13) The method for manufacturing a welded body according to (1), wherein the rotary tool has a flat or cone-shaped lower end surface and further has a columnar or frustum-shaped shoulder portion, the stirring pin hangs down from the lower end surface of the shoulder portion, and friction stir welding of the workpieces is performed with the shoulder portion in contact with the welded workpieces and the stirring pin inserted into the welded workpieces. (14) The method for manufacturing a welded body according to (13), wherein the relationship between an insertion depth H1 of the rotary tool in the inserting step and a length L1 of the stirring pin is L1 × 0.5 ≦ H1 ≦ L1. (15) The method for manufacturing a welded body according to (1), wherein the rotary tool has a columnar or frustrum-shaped base, the stirring pin hangs down from a lower end surface of the base, the base is separated from the workpieces, and friction stir welding of the workpieces is performed with only the stirring pin inserted into the workpieces. (16) The method for manufacturing a welded body according to (1), wherein the rotary tool has a columnar or frustrum-shaped base, the stirring pin has a base pin continuous with the base and a tip pin continuous with the base pin, a taper angle of the base pin is larger than the taper angle of the tip pin, a stepped pin step portion is formed on an outer peripheral surface of the base pin, and friction stir welding of the workpieces is performed with the outer peripheral surface of the base pin in contact with the surfaces of the workpieces. (17) The method for manufacturing a joined body according to (1), further comprising a pilot hole forming step of forming a pilot hole in the members to be joined before the inserting step, and inserting the stirring pin into the pilot hole in the inserting step.(18) The method for manufacturing a joined body according to (1), wherein the members to be joined comprise a first member to be joined and a second member to be joined that has a lower hardness than the first member to be joined, wherein end surfaces of at least one of the first member to be joined and the second member to be joined are butted together to form a butt joint, or wherein the back surface of the second member to be joined is superposed on the front surface of the first member to be joined to form an overlapping portion, and wherein the inserting step inserts a stirring pin from the front surface of the first member to be joined, and wherein the joining step performs friction stir welding of the butt joint or the overlapping portion. (19) The method for manufacturing a joined body according to (1), wherein the members to be joined comprise a first member to be joined and a second member to be joined, wherein end surfaces of at least one of the first member to be joined and the second member to be joined are butted together to form a butt joint, or wherein the back surface of the second member to be joined is superposed on the front surface of the first member to be joined to form an overlapping portion, and wherein the inserting step inserts a stirring pin toward the butt joint or the overlapping portion.

[0011] According to the method for manufacturing a joined body of the present invention, it is possible to suppress the occurrence of burrs and defects in the joined portion, and also to reduce the load applied to the rotary tool and the joining device.

[0012] FIG. 1 is an exploded perspective view showing a bonded body according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a butting step in the method for manufacturing a bonded body according to the first embodiment. FIG. 3 is a plan view showing the butting step in the method for manufacturing a bonded body according to the first embodiment. FIG. 4 is a side view showing a rotary tool used in the method for manufacturing a bonded body according to the first embodiment. FIG. 5 is a cross-sectional view showing an inserting step in the method for manufacturing a bonded body according to the first embodiment. FIG. 6 is a cross-sectional view showing a pulling-up step in the method for manufacturing a bonded body according to the first embodiment. FIG. 7 is a cross-sectional view showing a modified step of the method for manufacturing a bonded body according to the first embodiment. FIG. 8 is a cross-sectional view showing a pushing-in step in the method for manufacturing a bonded body according to the first embodiment. FIG. 9 is a cross-sectional view showing a joining step in the method for manufacturing a bonded body according to the first embodiment. FIG. 10 is a cross-sectional view showing a pilot hole forming step in a first modified example of the first embodiment. FIG. 11 is a cross-sectional view showing an inserting step in a second modified example of the first embodiment. FIG. 12 is a cross-sectional view showing a joining step in a second modified example of the first embodiment. FIG. 13 is a cross-sectional view showing an inserting step in a third modified example of the first embodiment. FIG. 14 is an enlarged view showing a rotary tool according to the third modified example of the first embodiment. FIG. 15 is a cross-sectional view showing a joining step in a third modified example of the first embodiment. FIG. 16 is a cross-sectional view showing a joining step in a third modified example of the first embodiment. FIG. 17 is a cross-sectional view showing a butting step in a fourth modified example of the first embodiment. FIG. 18 is a cross-sectional view showing an inserting step in a fourth modified example of the first embodiment. FIG. 19 is an exploded perspective view showing a bonded body according to FIG. 10 is a cross-sectional view showing an insertion step according to the second embodiment. FIG. 11 is a cross-sectional view showing an insertion step according to a first modified example of the second embodiment. FIG. 12 is a plan view showing an insertion section of a first friction stir welding step of the manufacturing method for a welded body according to the third embodiment. FIG. 13 is a plan view showing a removal section of a first friction stir welding step of the manufacturing method for a welded body according to the third embodiment. FIG. 14 is a side cross-sectional view showing a removal section of a first friction stir welding step of the manufacturing method for a welded body according to the third embodiment. FIG. 15 is a side cross-sectional view showing a return section of a second friction stir welding step of the manufacturing method for a welded body according to the third embodiment. FIG. 16 is a side cross-sectional view showing a return section (start position) of a second friction stir welding step of the manufacturing method for a welded body according to the third embodiment. FIG. 17 is a side cross-sectional view showing a return section (return position) of a second friction stir welding step of the manufacturing method for a welded body according to the third embodiment. FIG. 18 is a plan view showing a return section of a second friction stir welding step of the manufacturing method for a welded body according to the third embodiment.38 . FIG. 40 is a side cross-sectional view showing a main section of the second friction stir welding step of the manufacturing method for a welded body according to the third embodiment. FIG. 41 is a plan view showing a removal section of the second friction stir welding step of the manufacturing method for a welded body according to the third embodiment. FIG. 42 is a plan view showing a state before welding in the first friction stir welding step of the manufacturing method for a welded body according to the fifth embodiment. FIG. 43 is a plan view showing a removal section of the first friction stir welding step of the manufacturing method for a welded body according to the fifth embodiment. FIG. 44 is a plan view showing a turn-back section of the second friction stir welding step of the manufacturing method for a welded body according to the fifth embodiment. FIG. 45 is a plan view showing a removal section of the second friction stir welding step of the manufacturing method for a welded body according to the fifth embodiment. FIG. 46 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. 47 is a table showing the moving speed, insertion depth, pull-up amount / insertion amount, evaluation, and alloy type in Test 1 and Test 2. FIG. 48 is a plan view showing the friction stir welding state of Test Example 11. FIG. 49 is a cross-sectional view taken along line XXXIX-XXXIX of FIG. 38 . FIG. 49 is a cross-sectional view taken along line XLI-XLI of FIG. 40 . FIG. 41 is a plan view showing the friction stir welding state of Comparative Test Example 12. 50. An enlarged plan view at the start position of FIG. 42. A cross-sectional view taken along line XLIV-XLIV of FIG. 42. A plan view showing the friction stirring state of Comparative Test Example 13. An enlarged plan view at the start position of FIG. 45. A cross-sectional view taken along line XLVII-XLVII of FIG. 45. A plan view showing the friction stirring state of Test Example 21. An enlarged plan view at the start position of FIG. 48. A plan view showing the friction stirring state of Test Example 22. An enlarged plan view at the start position of FIG. 50. A cross-sectional view taken along line LII-LII of FIG. 50. A plan view showing the friction stirring state of Comparative Test Example 21. An enlarged plan view at the start position of FIG. 53. A plan view showing the friction stirring state of Comparative Test Example 22. An enlarged plan view at the start position of FIG. 55. A cross-sectional view taken along line LVII-LVII of FIG. 55.

[0013] The following describes embodiments of the present invention with reference to the accompanying drawings. The present invention is not limited to the following embodiments. Furthermore, some or all of the components in the embodiments and modifications can be combined as appropriate.

[0014] [1. First embodiment] [1-1. Members to be joined and joined body] As shown in FIG. 1, a liquid-cooled jacket (joined body) 1 according to a 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-cooled jacket 1 is a device that cools a heat-generating body placed inside by circulating a fluid therein. The jacket body 2 and the sealing body 3 are integrated by friction stir welding. In the following description, the term "front surface" refers to the surface opposite to the "rear surface."

[0015] The jacket body (first member to be welded) 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 that can be friction-stirred, but in this embodiment, it is formed to mainly contain a first aluminum alloy. The first aluminum alloy is, for example, an aluminum alloy casting material such as JIS H5302 ADC12 (Al-Si-Cu system).

[0016] The bottom 10 is a rectangular plate-like member. The peripheral wall 11 is a wall rising in the shape of a rectangular frame from the peripheral edge of the bottom 10. The bottom 10 and the peripheral wall 11 form a recess 13 that opens upward. A peripheral wall step 12 is formed on the inner peripheral edge of the peripheral wall 11. The peripheral wall step 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] Although the jacket body 2 in this embodiment is integrally formed, for example, the peripheral wall portion 11 may be divided into separate portions which are joined together with a sealing member to form an integrated structure.

[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 that can be friction-stirred, but in this embodiment, it is formed to mainly contain a second aluminum alloy. The second aluminum alloy is a material that is lower in hardness than the first aluminum alloy. The second aluminum alloy is formed from an aluminum alloy wrought material such as JIS A1050, A1070, A1100, or A6063.

[0019] [1-2. Manufacturing Method] Next, a method for manufacturing a liquid cooling jacket according to this embodiment (a method for manufacturing a joined body, a method for joining members to be joined) (hereinafter, sometimes referred to as "this method") will be described. The method for manufacturing a liquid cooling jacket according to this embodiment includes a preparation step, a butting step, an insertion step, a pulling-up step, a changing step, a pushing-in step, and a joining step.

[0020] In this method, as shown in FIG. 2 , the jacket body 2 and the sealing body 3 are placed on the jacket body 2 with their sides butted against each other, and friction stir welding is performed between them. As shown in FIG. 3 , in this method, a start position SP1 and an end position EP1 are set on the end surface 11a of the peripheral wall portion 11, and an intermediate position S1 and an intermediate position E1 are set on the surface 3a of the sealing body 3. As shown in FIG. 3 , a movement route R1 along which the rotation axis C of the rotary tool F (see FIG. 4 ) of this embodiment 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 removal section. In this method, the insertion process, the pulling-up process, the change process, and the pushing-in process are performed at the start position SP1. In this method, the welding process is performed in the insertion section, the main section, and the removal section.

[0021] The insertion section is a section from a start position SP1 set on the end surface 11a of the peripheral wall portion 11 to an 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, going around the first butt joint J1, passing the intermediate position S1, to an intermediate position E1 set on the surface 3a of the sealing body 3. As will be described in detail later, in this section, the movement route R1 is set slightly inward (toward the sealing body 3) from the first butt joint J1. In this section, the rotary tool F moves at a roughly constant depth.

[0023] The removal section is a section from the intermediate position E1 to an end position EP1 set on the end surface 11 a of the peripheral wall portion 11. In the removal section, the rotary tool F, which will be described later, is moved and 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 butt portion J1 to the movement route R1 may be set as appropriate, but is preferably 0.1 (mm) < P1, more preferably 0.2 (mm) < P1, and more preferably P1 < 0.5 (mm), and more preferably P1 < 0.4 (mm). The displacement amount P1 is the distance from the first butt portion J1 to the movement route R1. In other words, the displacement amount P1 indicates how much the movement route R1 is displaced on the same plane with respect to the first butt portion J1.

[0025] <Rotary Tool> The rotary tool F used in manufacturing the welded body will now 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, for example, from tool steel. The shoulder portion F1 is connected to the output shaft of a welding machine (not shown) and has a columnar or truncated shape. The stirring pin F2 hangs down from the lower end surface F1a of the shoulder portion F1. The stirring pin F2 has a truncated conical shape, with the diameter decreasing from the lower end surface F1a of the shoulder portion F1 as the base end toward the tip. The lower end surface F1a may be flat or may have a cone shape concave upward (away from the stirring pin F2). The tip of the stirring pin F2 is flat. A spiral groove is formed on the outer circumferential surface of the stirring pin F2 throughout its height. 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 welding depth of the workpieces. In this embodiment, the stirring pin is inserted to a depth of 15 mm, which is the height dimension of the step side surface 12b, with the aim of welding the entire first butt joint J1 (described later) and reaching the second butt joint J2. For this reason, an example will be described in which the length L1 of the stirring pin F2 is 15 mm.

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

[0027] <Preparation Step> The preparation step is a step of preparing the jacket body 2 and the sealing body 3. There are no particular limitations on the manufacturing methods of the jacket body 2 and the sealing body 3, but the jacket body 2 is molded by, for example, die casting, and the sealing body 3 is molded by, for example, extrusion molding.

[0028] <Butting Process> As shown in FIG. 2 , the butting process is a process in which the sealing body 3 is placed on the jacket main body 2 and their side surfaces are butted together. In the butting process, the side surface 3c of the sealing body 3 and the step side surface (side surface) 12b of the peripheral wall step portion 12 are butted together to form a first butt joint J1. As shown in FIG. 3 , the first butt joint 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 face 11a of the jacket main body 2. Furthermore, the step bottom surface 12a of the peripheral wall step portion 12 and the back surface 3b of the sealing body 3 are butted (overlapped) together to form a second butt joint J2. In this embodiment, the thickness of the sealing body 3 is the same as the height dimension of the step side surface 12b. The thickness of the sealing body 3 may be set to be greater than the height dimension of the step side surface 12b. This prevents a shortage of metal at the joint. After the butting step, the jacket body 2 and the sealing body 3 are fixed with a jig (not shown) so that the 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 workpieces (here, the jacket body 2). In the insertion process, the rotary tool F is rotated (reversely) in the same direction as the formation direction of the spiral groove provided on the stirring pin F2. In this embodiment, since the spiral groove is left-handed, the rotary tool F is rotated left-handed. In the insertion process, the rotary tool F is pushed in until it reaches a predetermined insertion depth H1. The insertion depth H1 is the distance from the end surface 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 equal to or less than the length L1 of the stirring pin F2. In the insertion process, the insertion depth H1 may be set within a range in which only the stirring pin F2 contacts the peripheral wall portion 11 and the shoulder portion F1 does not contact the peripheral wall portion 11. The insertion process frictionally stirs the material of the sealing body 3, forming a plasticized region W1. The position of the tip of the inserted stirring pin F2 is defined as a first virtual reference plane D1.

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

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

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

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

[0034] <Pulling-up process> As shown in Fig. 6 , the pulling-up process is a process of pulling up the rotary tool F toward the surface of the workpieces to be welded (here, the jacket body 2) after the insertion process. That is, the rotary tool F is pulled up while maintaining the rotation direction (reverse rotation) of the insertion process. In the pulling-up process, the position of the tip of the rotary tool F after it has been pulled up is defined as a second imaginary reference surface D2. A pulling-up amount H2 by which the rotary tool F is pulled up in the pulling-up process is the distance from the first imaginary reference surface D1 to the second imaginary reference surface D2. In the pulling-up process, the rotary tool F may be pulled up only slightly from the first imaginary reference surface D1, or may be pulled up so as to be spaced above the end surface 11a of the peripheral wall portion 11.

[0035] The pulling-up amount H2 in the pulling-up process may be set appropriately depending on the length L1 of the stirring pin F2 and the workpieces to be joined, but is preferably 0.1 mm or more, more preferably 0.3 mm or more, even more preferably 0.5 mm or more, and is preferably 7.5 mm or less, more preferably 3 mm or less, even more preferably 2 mm or less.

[0036] The pulling amount H2 in the pulling step 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, even more preferably H1×0.1≦H2, preferably H2≦H1×0.5, more preferably H2≦H1×0.3, and even more preferably H2≦H1×0.2.

[0037] <Changing Process> The changing process is a process of changing the rotation direction of the rotary tool F, as shown in Fig. 7 . In this embodiment, since the rotary tool F was rotated in the reverse direction in the inserting process, the rotation direction is changed from reverse rotation to forward rotation. In other words, in this embodiment, the rotation direction of the rotary tool F is changed from left rotation to right rotation. The changing process may be performed in a state where the stirring pin F2 is in contact with the peripheral wall portion 11, or the rotation direction may be changed in a state where the stirring pin F2 is separated from the peripheral wall portion 11 as in this embodiment.

[0038] In the changing step, the rotation speed of the rotary tool F after changing the rotation direction can be set appropriately depending on the workpieces to be welded. The rotation speed of the rotary tool F after changing the rotation direction can be set to the same rotation speed as the rotation speed of the rotary tool F set in the welding step.

[0039] <Pushing Process> As shown in FIG. 8 , the pushing process is a process of pushing the rotary tool F in the depth direction of the workpieces (here, the jacket body 2) after the changing process. That is, the rotary tool F is pushed while maintaining the rotation direction (forward rotation) after the changing process. In the pushing process, the position of the tip of the rotary tool F after being pushed is set to a third imaginary reference surface D3. The insertion amount H3 by which the rotary tool F is pushed in the pushing process is the distance from the first imaginary reference surface D1 to the third imaginary reference surface D3 (the insertion amount after the stirring pin F2 abuts against the peripheral wall portion 11 again). In the pushing process, it is sufficient for the rotary tool F to only slightly contact 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 positioned deeper than the first imaginary reference surface D1.

[0040] In the pushing-in process, the rotary tool F is pushed in until it reaches a predetermined insertion depth H4. The insertion depth H4 is the distance from the end surface 11a of the peripheral wall portion 11 to the tip of the stirring pin F2. The insertion depth H1 in the inserting process, and the insertion amount H3 and insertion depth H4 in the pushing-in process have a relationship of H1 + H3 = H4. The insertion depth H4 in the pushing-in process is the insertion depth of the rotary tool F when friction stir welding is started in the joining process.

[0041] The insertion amount H3 in the pushing step may be set appropriately depending on the length L1 of the stirring pin F2 and the workpieces, but is preferably 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more, and is preferably 7.5 mm or less, more preferably 3 mm or less, and even 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 in the pushing process and the insertion depth H1 is preferably H1 x 0.01 ≦ H3, more preferably H1 x 0.05 ≦ H3, even more preferably H1 x 0.1 ≦ H3, preferably H3 ≦ H1 x 0.5, more preferably H3 ≦ H1 x 0.3, even more preferably H3 ≦ H1 x 0.2.

[0043] Furthermore, the insertion depth H4 in the pushing process may be set appropriately depending on the length L1 of the stirring pin F2 and the workpieces to be joined, but is preferably 8 mm or more, more preferably 9 mm or more, even more preferably 10 mm or more, and is preferably 15 mm or less, more preferably 13.5 mm or less, even more preferably 12 mm or less.

[0044] The relationship between the insertion depth H4 in the pushing process and the insertion depth H1 is preferably H1 x 1.01 ≦ H4, more preferably H1 x 1.05 ≦ H4, even more preferably H1 x 1.1 ≦ H4, preferably H4 ≦ H1 x 1.5, more preferably H4 ≦ H1 x 1.3, even more preferably H4 ≦ H1 x 1.2.

[0045] The rotation speed of the rotary tool F in the pushing step can be set appropriately depending on the workpieces to be joined. The rotation speed of the rotary tool F in the pushing step can be set to the same rotation speed as the rotation speed of the rotary tool F set in the joining step.

[0046] <Joining Process> As shown in FIG. 9 , the joining process is a process of joining workpieces (here, the jacket body 2 and the sealing body 3) while rotating the rotary tool F in the direction opposite to the formation direction of the spiral groove. That is, in the joining process, friction stir welding is performed while rotating in the forward direction. In the joining process, the workpieces are joined by moving the rotary tool F while rotating in the direction opposite to the formation direction of the spiral groove. After the rotary tool F is pressed to a predetermined insertion depth H4 in the aforementioned pressing process, the rotary tool F is moved to an intermediate position S1 and gradually pressed deeper until it reaches a predetermined insertion depth H5. Upon reaching the intermediate position S1, the rotation axis C of the rotary tool F is moved along the first butt joint J1 while overlapping with the movement route R1. Although the movement route R1 may be set at the same position as the first butt joint J1, in this embodiment, it is set slightly inward (toward the sealing body 3) of the first butt joint J1. The movement route R1 and the first butt joint J1 are generally parallel to each other.

[0047] An insertion depth H5 of the rotary tool F is the distance from the end surface 11 a of the peripheral wall portion 11 to the tip of the stirring pin F2. The insertion depth H5 may be set appropriately within a range that allows friction stir welding of the first butt portion J1, but in this embodiment, the insertion depth H5 is set so that the tip of the stirring pin F2 is deeper than the step bottom surface 12 a.

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

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

[0050] [1-3. Effects] According to the manufacturing method of the joined body according to the present embodiment described above, in the insertion step, the stirring pin F2 is inserted into the workpieces (here, the jacket body 2) while the rotary tool F is rotated (reverse rotation) in the same direction as the formation direction of the spiral groove. As the stirring pin F2 is inserted into the workpieces, the spiral groove acts on the workpieces like a drill bit, scraping away material from the workpieces. In other words, in the insertion step of this embodiment, the stirring pin F2 penetrates the workpieces without causing plastic flow, as occurs in the case of forward rotation. This makes it easier for the rotary tool F to penetrate the workpieces than in the case of forward rotation. As a result, the workpieces are actively ejected from the workpieces as the stirring pin F2 is inserted, thereby reducing the load on the rotary tool F and the welding device during insertion. Furthermore, the reduced load also reduces wear on the spiral groove of the stirring pin F2, thereby reducing damage to the stirring pin F2.

[0051] In addition, in the past, a pilot hole was drilled at the start position SP1 of the stirring pin F2 to reduce the press-fit resistance, but in this case, the number of steps required to form the pilot hole increased, which was a problem, as it required time. Furthermore, for example, when forming the pilot hole and performing friction stir welding using a machining center, it was also a problem that it required time to change the tools used for each process. However, according to this embodiment, the press-fit resistance can be reduced without drilling a pilot hole, allowing the stirring pin F2 to be inserted smoothly, thereby improving productivity.

[0052] In this embodiment, after inserting the stirring pin F2, the rotation direction of the rotary tool F is switched to the opposite direction to the formation direction of the spiral groove, and friction stir welding is performed with the rotary tool F rotating in the opposite direction to the formation direction of the spiral groove (forward rotation). This causes downward plastic flow during friction stir welding, which makes it possible to replenish material toward the tip side of the stirring pin F2 and makes it less likely for defects to occur inside.

[0053] Furthermore, in the insertion step of this embodiment, it is presumed that the material of the workpieces that has been removed is expelled to the outside of the workpieces as the spiral groove rotates, similar to chips generated by cutting with a drill. As a result, the material that has been plastically fluidized and flowed out is less likely to remain as burrs on the surface of the workpieces (here, the end face 11a of the peripheral wall 11) after friction stir welding, which reduces the burden of post-processing such as cutting to remove burrs and improves productivity.

[0054] Furthermore, although the rotational speed of the rotary tool F in the insertion step of this embodiment may be set as appropriate, it is preferable that the rotational speed of the rotary tool F be equal to or greater than the rotational speed of the rotary tool F in the joining step. By setting the rotational speed in the insertion step equal to or greater than the rotational speed in the joining step, the workpieces are cut by the spiral groove when the stirring pin F2 is inserted, and chips of the workpieces cut off as the rotary tool F rotates are easily blown out from the surfaces of the workpieces, making it easier to prevent burrs and chips from remaining on the surfaces of the workpieces after joining. In particular, even when the size of the rotary tool F is relatively small, chips of the workpieces are easily blown out. Furthermore, if the rotational speed during insertion is low, the oxide film is likely to be rolled up. However, by setting the rotational speed in the insertion step equal to or greater than the rotational speed in the joining step, this roll-up can be prevented.

[0055] Furthermore, as in this embodiment, the relationship between the rotation speed N1 of the rotary tool F in the insertion step and the rotation speed N2 of the rotary tool F in the joining step is preferably N2≦N1≦N2×5. By setting the rotation speed N1 to N2 or more, the cutting effect of the spiral groove of the stirring pin F2 on the workpieces can be improved. Furthermore, by setting the rotation speed N1 to N2×5 or less, the load on the rotary tool F and the joining device can be reduced.

[0056] Furthermore, as in the present embodiment, it is preferable to further include a pulling-up step of pulling up the rotary tool F toward the surfaces of the workpieces after the insertion step, and to perform the 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 workpieces is reduced (substantially eliminated), thereby suppressing the load on the rotary tool F and the welding device that occurs when changing the rotation direction.

[0057] Furthermore, as in this embodiment, the relationship between the insertion depth H1 of the rotary tool F in the insertion step and the pull-up amount H2 in the pull-up step is preferably H1×0.01≦H2≦H1×0.5. By setting the pull-up amount H2 to H1×0.01 or more, the contact resistance with the workpieces can be reduced. By setting the pull-up amount H2 to H1×0.5 or less, it is possible to prevent the temperature of the workpieces from decreasing due to excessive separation between the rotary tool F and the workpieces, and the subsequent joining can be performed appropriately.

[0058] Furthermore, as in this embodiment, it is preferable to further include a pushing step in which the rotating tool F is pushed in the depth direction of the workpieces after the changing step, and to perform the joining step after the pushing step. By pushing the stirring pin F2 after changing the rotation direction, the metal structure formed during the reverse rotation in the insertion step can be changed to a structure consisting of downward plastic flow material caused by forward rotation. Furthermore, by pushing the stirring pin F2, the rotating tool (stirring pin F2 (+shoulder portion F1)) F comes into new contact with the workpieces, which can increase heat generation. Therefore, the subsequent joining can be performed efficiently.

[0059] Furthermore, as in this embodiment, the relationship between the insertion depth H1 of the rotary tool in the insertion step and the insertion amount H3 in the plunge step is preferably H1 × 0.01 ≦ H3 ≦ H1 × 0.5. By setting the insertion amount H3 to H1 × 0.01 or more, a structure consisting of downward plastic flow due to forward rotation is generated, and heat generation is increased by contact between the rotary tool F and new workpieces, allowing for favorable friction stir welding. Furthermore, by setting the insertion amount H3 to H1 × 0.5 or less, the load on the rotary tool F and the welding device can be reduced.

[0060] Furthermore, as in this embodiment, the relationship between the insertion depth H1 of the rotary tool in the insertion step and the insertion depth H4 at the start of welding in the welding step is preferably H1 × 1.01 ≦ H4 ≦ H1 × 1.5. By setting the insertion depth H4 to H1 × 0.01 or more, a structure consisting of downward plastic flow due to forward rotation is generated, and heat generation is increased by contact between the rotary tool F and new workpieces, allowing for favorable friction stir welding. Furthermore, by setting the insertion depth H4 to H1 × 1.5 or less, the load on the rotary tool F and the welding device can be reduced.

[0061] Furthermore, when the rotary tool F of this embodiment has a shoulder portion F1, contact with the shoulder portion F1 allows chips to be effectively removed, and the heat generation efficiency by the shoulder portion F1 during welding is improved. Generally, when a rotary tool with a shoulder portion is used, the contact area with the workpieces increases, which tends to increase the load on the welding device. However, this embodiment includes the insertion process, the pull-up process, the change process, and the push-in process, and the workpieces are actively ejected to the outside in advance during these processes (insertion). This reduces the load on the rotary tool F and the welding device when the shoulder portion comes into contact with the workpieces to perform friction stir welding.

[0062] Furthermore, as in this embodiment, the relationship between the insertion depth H1 of the rotary tool F and the length L1 of the stirring pin F2 in the insertion step is preferably L1 × 0.5 ≦ H1 ≦ L1. By setting the insertion depth H1 to L1 × 0.5 or more, the spiral groove of the stirring pin F2 can scrape away material, thereby more effectively reducing the load on the rotary tool F and the welding device. Furthermore, by setting the insertion depth H1 to H1 ≦ L1, it is possible to prevent the shoulder portion F1 and the workpieces from coming into contact with each other too much during the insertion step, which would increase contact resistance.

[0063] In this embodiment, the liquid-cooled jacket (joined body) 1 is composed of a jacket body (first welded member) 2 and a sealing body 3 (second welded member) having a lower hardness than the jacket body 2. This increases the strength of the liquid-cooled jacket (joined body). In this embodiment, the travel route R1 is set inside the first butt joint J1, and friction stir welding is performed with the travel route R1 and the rotation axis C of the rotary tool F overlapping each other. This minimizes the contamination of the relatively hard material of the jacket body 2 with the sealing body 3, preventing a decrease in the strength of the weld. This also eliminates imbalances due to material resistance during friction stir welding, allowing for well-balanced friction stirring and favorable welding. From the perspective of reducing the load on the rotary tool F and the welding device during insertion, it is desirable to insert the stirring pin into the second welded member, which has a lower hardness than the first welded member. In this embodiment, by sequentially performing the insertion process, the change process, and the welding process, the load on the rotary tool F and the welding device during insertion can be reduced, even when the stirring pin is inserted into the first welded member, which has a higher hardness.

[0064] Furthermore, in the joining process, by setting the insertion depth so that the tip of the stirring pin F2 reaches the step bottom surface 12a, not only the first butt joint J1 but also the second butt joint J2 can be reliably friction stir welded.

[0065] Furthermore, if the start position SP1 is set on the first butt joint J1, the oxide film may be rolled up, but in the joining process of this embodiment, the start position SP1 is set on the end surface 11a of the peripheral wall portion 11. This makes it possible to prevent the oxide film from remaining in the plasticized region W1, particularly at the insertion position.

[0066] [1-4. Other] The manufacturing method of the joined body according to this embodiment has been described above, but appropriate design changes are possible within the scope of the present invention. For example, the above embodiment illustrates a case in which the side surface 3c of the sealing body 3 and the step side surface 12b of the peripheral wall step portion 12 are butted together to form the first butt joint J1, i.e., a case in which both end surfaces of the first and second joined members are butted together. It is sufficient that at least one end surface of the first and second joined members is butted against the other to form the butt joint.

[0067] In the above embodiment, the inserting step, the pulling step, the changing step, and the pushing step are performed without moving the rotary tool F from the start position SP1, but each step may be performed while moving the rotary tool F in the traveling direction. That is, the inserting step, the pulling step, the changing step, and the pushing step may be performed while moving the rotary tool F from the start position SP1 in the insertion section.

[0068] The pulling-up step may also be omitted. That is, after the insertion step is completed, the rotation 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 workpieces). In particular, when the rotary tool F is relatively small, the contact resistance is small, so the pulling-up step may be omitted.

[0069] In addition, the pushing step may be omitted. In addition, although the case where the rotary tool F is gradually pushed in while being moved in the insertion section has been described as an example, the rotary tool F may be inserted to a predetermined insertion depth H5 at the start position SP1, and then moved while maintaining the insertion depth H5.

[0070] In addition, in the joining process, 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. In addition, although the joined body is exemplified as a rectangular parallelepiped liquid cooling jacket in this embodiment, it may have other shapes, and it is sufficient that at least two members are joined together.

[0071] The step side surface 12b may also be inclined outward relative to the step 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 is thin. This minimizes the intrusion of the relatively hard material of the jacket body 2 into the sealing body 3, thereby preventing a decrease in joining strength. It also eliminates imbalances due to material resistance during friction stirring. In this case, the thickness of the sealing body 3 may be greater than the height of the step side surface 12b. This makes it possible to compensate for a lack of material at the joining portion.

[0072] 2. First Modification of First Embodiment Next, a first modification of the first embodiment will be described. The method for manufacturing a bonded body according to this modification differs from the first embodiment in that it includes a pilot hole forming step.

[0073] In this modified example, a pilot hole forming step is performed before the insertion step, as shown in Fig. 10. In the pilot hole forming step, a cutting tool such as a rotary tool or an end mill is used to form a pilot hole Q at a start position SP1 set on the end surface 11a of the peripheral wall portion 11. In this modified example, the pilot hole Q has a hollow portion with a truncated shape, but it may also have a conical, cylindrical, or prismatic shape.

[0074] By performing the pilot hole forming step, it is possible to reduce the press-fit resistance caused by the rotary tool F during the insertion step. This also reduces damage and wear to the rotary tool F. In particular, when the jacket body (first member to be joined) 2 is formed from a relatively hard material such as an aluminum alloy casting material, the effect of reducing the press-fit resistance is significant. Note that when the start position SP1 is set on the surface 3a of the sealing body 3, the pilot hole Q may be formed on the surface 3a. Furthermore, the pilot hole Q may be formed in advance during the molding stage of the jacket body 2.

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

[0076] The rotary tool K includes a base K1 and a stirring pin K2. The base K1 is connected to the output shaft of a welding machine (not shown) and has a columnar or truncated shape. The stirring pin K2 has a truncated cone shape and hangs down from the lower end surface K1a of the base K1. The stirring pin K2 has a length at least twice the 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] The manufacturing method of the bonded body of this modification includes a preparation step, a butting step, an insertion step, a lifting step, a changing step, a pushing step, and a bonding step. The preparation step and the butting step are the same as those of the first embodiment.

[0078] In the insertion step, as shown in Fig. 11, the rotary tool K is rotated in the reverse direction (left direction) 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 aspects of the insertion step are the same as those of the first embodiment. The pulling-up step, the changing step, and the pushing-in step are also the same as those of the first embodiment.

[0079] 12, the rotary tool K is rotated forward (right), the rotation axis C is aligned with the movement route R1, and the rotary tool K is moved so as to be parallel to the first butt portion J1. In the joining process, friction stir welding is performed with only the stirring pin K2 in contact with the workpieces (here, the jacket body 2 and the sealing body 3) and the base end side of the stirring pin K2 exposed.

[0080] The rotary tool K of this modified example can also achieve effects substantially equivalent to those of the first embodiment. Furthermore, since friction stir welding is performed in the welding process with only the stirring pin K2 in contact with the workpieces and the base K1 not in contact with the workpieces, the load acting on the welding device can be reduced. Note that, even when the rotary tool K is used, the step side surface 12b may be inclined outward.

[0081] 4. Third Modification of First Embodiment Next, a description will be given of a third modification of the first embodiment. The method for manufacturing a bonded structure according to this modification differs from the first embodiment in that a rotary tool G is used, as shown in FIG.

[0082] The rotary tool G is made of, for example, tool steel and is mainly composed of a base G1 and stirring pins (a base-side pin G2 and a tip-side pin G3). The base G1 has a columnar or pedestal-like shape and is connected to the output shaft of the welding device.

[0083] The base-side pin G2 is continuous with the base portion G1 and tapers toward the tip. The base-side pin G2 has a truncated cone shape. The taper angle A of the base-side pin G2 may be set appropriately, and is, for example, 135 to 160°. When the taper angle A is 135 to 160°, the roughness of the welded surface after friction stir welding can be reduced.

[0084] The taper angle A is larger than the taper angle B of the distal pin G3, which will be described later. As shown in FIG. 14 , a stepped pin step G21 is formed on the outer circumferential surface of the proximal pin G2 over the entire height direction. The pin step G21 is formed in a right-handed or left-handed spiral. In other words, the pin step G21 is spiral and has a stepped shape when viewed from the side. In this modified example, the pin step G21 is set to be left-handed from the proximal end side to the distal end side.

[0085] 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, which will be described later.

[0086] The height Y1 of the step side surface F21b may be set appropriately, for example, to 0.1 to 0.4 mm. If the height Y1 is less than 0.1 mm, the joining surface roughness increases. On the other hand, if the height Y1 exceeds 0.4 mm, the joining surface roughness tends to increase and the number of effective step portions (the number of pin step portions G21 in contact with the joined metal members) 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, between 85 and 120°. In this embodiment, the step bottom surface G21a is parallel to the horizontal plane (here, the plane perpendicular to the rotation axis C). The step bottom surface G21a may be inclined from the rotation axis C toward the outer periphery within a range of -5° to 15° with respect to the horizontal plane (negative angles indicate downward angles with respect to the horizontal plane, and positive angles indicate upward angles 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 set as appropriate so that, during friction stir welding, the plastic flow material can escape to the outside without remaining inside the pin step portion G21 and adhering, and the step bottom surface G21a can press the plastic flow material to reduce the joining surface roughness.

[0088] As shown in Figure 13, the tip side pin G3 is formed continuous with the base side pin G2. The tip side pin G3 has a truncated cone 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 side pin G2. As shown in Figure 14, a spiral groove G31 is engraved on the outer circumferential 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 left-handed.

[0089] The spiral groove G31 is composed of a spiral bottom surface G31a and a spiral side surface G31b. The distance (horizontal distance) between the apexes G31c, G31c of adjacent spiral grooves G31 is defined as length X2. The height of the spiral side surface G31b is defined as height Y2. The spiral angle M2 formed by the spiral bottom surface G31a and the spiral side surface G31b is, for example, 45 to 90°. The spiral groove G31 has the role of increasing frictional heat by contacting the workpieces and guiding the plastic flow material toward the tip. The spiral angle M2, length X2, and height Y2 may be set appropriately. The pin step portion G21 and spiral groove G31 of the rotary tool G correspond to the "spiral groove of the stirring pin" in the claims.

[0090] The manufacturing method of the bonded body of this modification includes a preparation step, a butting step, an insertion step, a lifting step, a changing step, a pushing step, and a bonding step. The preparation step and the butting step are the same as those of the first embodiment.

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

[0092] 15 , the rotary tool G is rotated clockwise (forward rotation) while the rotation axis C is aligned with the movement route R1 and the rotary tool G is moved so as to be parallel to the first butt portion J1. In the joining process, the outer peripheral surface of the base-side pin G2 is brought into contact with the surface 3 a of the sealing body 3 and the end face 11 a of the peripheral wall portion 11, and the insertion depth is set so that the tip of the tip-side pin G3 is positioned below the step bottom surface 12 a.

[0093] The rotary tool G of this modified example can achieve substantially the same effects as the first embodiment. Furthermore, during the joining process, the plastic flow material can be pressed down by the outer peripheral surface of the base-side pin G2, thereby reducing the size of the stepped groove formed on the joining surface and eliminating or reducing the bulge formed beside the stepped groove. Furthermore, the stepped pin step portion G21 is shallow and has a wide outlet, so the plastic flow material is easily released to the outside of the pin step portion G21 while being pressed down by the step bottom surface G21a. Therefore, even if the plastic flow material is pressed down by the base-side pin G2, the plastic flow material is less likely to adhere to the outer peripheral surface of the base-side pin G2. This reduces the joining surface roughness and favorably stabilizes the joining quality.

[0094] Furthermore, the rotary tool G of this embodiment is configured to include a base end pin G2 and a tip end pin G3 having a taper angle smaller than the taper angle A of the base end pin G2. This makes it easier to insert the rotary tool G into the jacket body 2 and the sealing body 3. Furthermore, because the taper angle B of the tip end pin G3 is small, the rotary tool G can be easily inserted deep into the first butt portion J1. Note that even when using the rotary tool G, the step side surface 12b may be inclined outward.

[0095] 5. Fourth Modification of First Embodiment Next, a description will be given of a fourth modification of the first embodiment. The manufacturing method of the joined body according to this modification differs from the first embodiment in that, in the insertion step, the stirring pin is inserted toward the first butt portion J1.

[0096] The manufacturing method of the bonded body of this modified example (hereinafter sometimes referred to as "this method") includes a preparation step, a butting step, an insertion step, a pulling-up step, a changing step, a pushing-in step, and a bonding step. The preparation step and the butting step are the same as those in the first embodiment.

[0097] In this method, as shown in FIG. 16 , the jacket body 2 and the sealing body 3 are placed on the jacket body 2 with their sides butted together, and friction stir welding is performed between them. In this method, an end position EP1 is set on the end surface 11a of the peripheral wall portion 11, and a start position SP2, an intermediate position S1, and an intermediate position E1 are set on the surface 3a of the sealing body 3. In this method, the start position SP2 is set so that a plasticized region W2 (see FIG. 17 ) formed by inserting a stirring pin F2 into the start position SP2, which is the insertion position of the rotary tool F, overlaps with the first butted portion J1. In this method, a movement route R2 along which the rotation axis C of the rotary tool F 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 end point, and includes an insertion section, a main section, and a removal section. In this method, the inserting step, the pulling up step, the changing step, and the pushing step are performed at the start position SP2. Also, in this method, the joining step is performed in the inserting section, the main section, and the removing section.

[0098] The insertion section is a 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 this section, the movement route R2 is set slightly inward (toward the sealing body 3) from the first butting portion J1. The movement route R2 and the first butting portion J1 are generally parallel to each other.

[0100] As shown in FIG. 17 , the insertion process of this method is a process of inserting a rotary tool F into the workpieces (the jacket body 2 and the sealing body 3). More specifically, the insertion process of this method is a process of inserting the rotary tool F toward the first butt joint J1 between the jacket body 2 and the sealing body 3. In the insertion process, the rotary tool F is rotated in the same direction as the formation direction of the spiral grooves provided on the stirring pin F2 (reverse rotation), and the rotary tool F is inserted toward the first butt joint J1. The insertion depth H1 of the stirring pin F2 can be set in the same manner as in the first embodiment. The insertion process frictionally stirs the materials of the jacket body 2 and the sealing body 3, forming a plasticized region W2. At this time, the plasticized region W2 is formed across the first butt joint J1 and in contact with the jacket body 2 and the sealing body 3.

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

[0102] When a forward-rotating stirring pin is inserted into the workpieces, a plasticized region is formed at the insertion position of the stirring pin due to plastic flow in the workpieces, and the workpieces subjected to plastic flow are pushed downward in proportion to the volume of the inserted stirring pin. At this time, downward convection occurs in the inner portion of the plasticized region around the stirring pin, while upward convection occurs in the outer portion of the plasticized region. Therefore, when a forward-rotating stirring pin is inserted toward the first butt joint 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 insertion position of the stirring pin is rolled upward by plastic flow, which can reduce the joint strength of the first butt joint J1. Furthermore, when a forward-rotating stirring pin is inserted into the workpieces, the amount of workpieces subjected to convection due to plastic flow increases depending on the insertion depth of the stirring pin. As a result, near the position where the stirring pin is inserted, the convection of the joined parts, which have undergone plastic flow as the stirring pin is inserted, increases, making it easier for entrapment to occur near the interface, which can sometimes result in a decrease in the joining strength of the first butt joint J1.

[0103] According to this method, in the insertion step, the stirring pin F2 is inserted toward the first butt joint J1 while rotating the rotary tool F in the same direction (reverse rotation) as the spiral groove formation direction. This generates upward convection in the inner portion of the plasticized region W2 around the stirring pin, while downward convection in the outer portion of the plasticized region W2. Therefore, near the start position SP2 of the first butt joint J1, it is easy to prevent the oxide film present at the interface between the jacket main body 2 and the sealing body 3 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 first butt joint J1 between the jacket main body 2 and the sealing body 3.

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

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

[0106] Next, a method for manufacturing a bonded body according to this embodiment (hereinafter sometimes referred to as "this method") will be described. The method for manufacturing a bonded body according to this embodiment includes a preparation step, a superposition step, an insertion step, a pulling-up step, a changing step, a pushing-in step, and a joining step. The preparation step, the pulling-up step, the changing step, and the pushing-in step are the same as those in the first embodiment, and therefore will not be described again.

[0107] In this method, as shown in FIG. 19 , the jacket body 2A and the sealing body 3A are placed on top of each other and friction stir welded together. As shown in FIG. 20 , in this method, a start position SP3, an intermediate position S3, an intermediate position E3, and an end position EP3 are set on the surface 3a of the sealing body 3 at positions corresponding to the overlapping portion J3. In this method, a movement route R3 along which the rotation axis C of the rotary tool F 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 with the overlapping portion J3. The movement route R3 is sandwiched between the start position SP3, which is the starting point, and the end position EP3, which is the end point, and includes an insertion section, a main section, and a removal section. In this method, the insertion process, the pulling-up process, the change process, and the push-in process are performed at the start position SP3. In this method, the welding process is performed in the insertion section, the main section, and the removal section.

[0108] The insertion section is a section from the start position SP3 to the intermediate 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 intermediate position S3.

[0109] In this section, the rotary tool F is moved from the intermediate position S3 around the overlapping portion J3, passes through the intermediate position S3, and reaches the intermediate position E3. At this time, as shown in FIG. 19, the insertion depth of the rotary tool F is kept constant so that the stirring pin F2 reaches the end surface 11a.

[0110] The removal section is a section from the intermediate position E3 to the end position EP3. In the removal section, the rotary tool F, which has reached the intermediate position E3, is gradually lifted up while being moved toward the end position EP3. When the rotary tool F reaches the end position EP3, the rotary tool F is removed from the sealing body 3.

[0111] 19, the overlapping step is a step of overlapping the jacket main body 2A and the sealing body 3A. In the overlapping step, the end surface 11a of the peripheral wall portion 11 and the back surface 3b of the sealing body 3A are overlapped to form an overlapping portion J3. The overlapping portion J3 is formed in a rectangular frame shape in plan view along the outer periphery of the recess 13.

[0112] As shown in FIG. 21 , the insertion process is a process of inserting a rotary tool F into the workpieces (sealed body 3A). More specifically, the insertion process is a process of inserting the rotary tool F from the surface 3a of the sealed body 3A toward the overlapping portion J3 between the jacket main body 2A and the sealed body 3A. In the insertion process, the rotary tool F is rotated in the same direction (reverse rotation) as the spiral groove formed on the stirring pin F2. In this embodiment, since the spiral groove is left-handed, the rotary tool F is rotated left-handed. In the insertion process of this embodiment, the stirring pin F2 is brought into contact only with the sealed body 3A, and the insertion depth H1 is set so that the stirring pin F2 does not contact the peripheral wall portion 11. In the insertion process, the insertion depth H1 may be set so that only the stirring pin F2 contacts the surface 3a of the sealed body 3A, and the shoulder portion F1 does not contact the surface 3a. The insertion process frictionally stirs the material of the sealed body 3A, forming a plasticized region W3.

[0113] The joining process is a process of performing friction stir welding on the overlapping portion J3 using a rotary tool F. In this method, the insertion depth of the rotary tool F in the joining process is set so that the stirring pin F2 reaches the end face 11 a of the peripheral wall portion 11 while the shoulder portion F1 is slightly pressed into the surface 3 a of the sealing body 3. The insertion depth of the rotary tool F in the joining process may be set appropriately; for example, the overlapping portion J3 may be joined in a state in which the stirring pin F2 does not reach the end face 11 a.

[0114] The present embodiment described above can also achieve substantially the same effects as the first embodiment. Furthermore, according to the present embodiment, the overlapping portion J3 can also be joined.

[0115] Although the present embodiment has been described with reference to an example in which the rotary tool F is used, the rotary tools K and G may also be used. In addition, 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 (i.e., at positions inside the overlapping portion J3).

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

[0117] The manufacturing method of the bonded body of this modified example (hereinafter sometimes referred to as "this method") includes a preparation step, a superposition step, an insertion step, a lifting step, a changing step, a pushing step, and a bonding step. The preparation step and the superposition step are the same as those in the second embodiment.

[0118] As shown in FIG. 22 , the insertion process of this method is a process of inserting a rotary tool F into the workpieces (the jacket body 2A and the sealing body 3A). More specifically, the insertion process of this method is a 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 in the same direction as the formation direction of the spiral grooves provided on the stirring pin F2 (reverse rotation) to insert the rotary tool F toward the overlapping portion J3. In the insertion process of this embodiment, the insertion depth H1 is set so that the stirring pin F2 contacts the sealing body 3A and the end face 11a of the peripheral wall portion 11. In the insertion process, the insertion depth H1 may be set so that only the stirring pin F2 contacts 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. The insertion process frictionally stirs the materials of the jacket body 2A and the sealing body 3A to form the plasticized region W4. At this time, the plasticized region W4 is formed across the overlapping portion J3 and in contact with the jacket body 2A and the sealing body 3A.

[0119] Other aspects of the insertion process are the same as those of the second embodiment. The pulling-up process, the changing process, the pushing-in process, and the joining process are also the same as those of the second embodiment.

[0120] Here, when the stirring pin rotated forward is inserted toward the overlapping portion J3 formed by the end surface 11 a of the jacket body 2A and the back surface 3 b of the sealing body 3, the interface near the position where the stirring pin is inserted is rolled upward by plastic flow, which may reduce the joining strength of the overlapping portion J3. Furthermore, since the amount of joined material that is subjected to convection due to plastic flow increases depending on the insertion depth of the stirring pin, the convection of the joined material that is subjected to plastic flow as the stirring pin is inserted increases, and roll-up near the interface is more likely to occur, which may reduce 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 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 2A and the sealing body 3A 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 2A and the sealing body 3A.

[0122] 23 , the same jacket body (first welded member) 2 and sealing body (second welded member) 3 as in the first embodiment are welded to form a welded body. This embodiment differs from the first embodiment mainly in that the welding is performed in two separate steps, a first friction stir welding step and a second friction stir welding step, and that the rotary tool F is folded back to perform the friction stir welding.

[0123] In this embodiment, friction stir welding is performed on the weld path between the workpieces by a first friction stir welding process and a second friction stir welding process. In the first friction stir welding process, friction stir welding is performed in a first welding range from one end, which is the start position of the welding path by the first friction stir welding process and the second friction stir welding process, to a first point provided halfway along the welding path. In the second friction stir welding process, friction stir welding is performed in a second welding range from a second point provided in a plasticized region belonging to the first welding range generated by the first friction stir welding process, to the other end, which is the end position of the welding 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 friction stir welding for the first welding range is set at one end of the welding path between the workpieces, and the end position of the first welding range is set at a first point provided halfway along the welding path. In the second friction stir welding process, the start position of friction stir welding for the second welding range is set to a point at the end of the plasticized region belonging to the first welding range, and the end position of friction stir welding for the second welding range is set to the other end side opposite to the one end side of the welding path. In the second friction stir welding process, friction stir welding is performed from the start position for the second welding range toward one end side of the welding path to a turn back position set in the plasticized region belonging to the first welding range, friction stir welding is performed by turning back from the turn back position toward the other end side of the welding path in the plasticized region, and friction stir welding is performed on the remaining welding path again through the start position for the second welding range to the end position for the second welding range.

[0124] As shown in FIG. 23 , in the first friction stir welding process, friction stir welding is performed from a start position SP21 to an end position EP21 via an intermediate position S21. In the second friction stir welding process, friction stir welding is performed from a start position SP22 (the same position as the end position EP21) to a turnback position S22, via an intermediate position E22, and to an end position EP22. In this embodiment, the welding path refers to a clockwise rotation around the sealing body 3 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 at one end of the welding path formed 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 at the other end opposite to the one end of the welding path. The end position EP21 of the first friction stir welding process is set as a first point set midway along the welding path and as a second point set within the plasticized region belonging to the first welding range. The end position EP21 of the first friction stir welding process is a point at the end of the plasticized region belonging to the first welding area. The start position SP22 of the second friction stir welding process is set to a point at the end of the plasticized region belonging to the first welding area.

[0125] <First Friction Stir Welding Process> The first friction stir welding process includes a preparation process, a butting process, an insertion process, a pulling-up process, a changing process, a push-in process, and a welding process. In the first friction stir welding process, friction stir welding is performed from a start position SP21 to an end position (first point) EP21 via intermediate positions S21 and E21. The first welding range is from the start position SP21 to the end position EP21. The start position SP21 is set on the end surface 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 plug 3 near the start position SP21. The end position EP21 is set on the surface 3a of the plug 3 on the right side in the width direction in FIG. 23. The intermediate position E21 is set on the surface 3a of the plug 3 near the end position EP21.

[0126] The movement route R1 along which the rotation axis C of the rotation tool F (see FIG. 4) passes is a start position SP21, intermediate positions S21 and E21, and an 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 end point, and includes an insertion section, a main section, and a removal section. In this method, the insertion process, the pull-up process, the change process, and the push-in process are performed at the start position SP21. In addition, in this method, the joining process is performed in the insertion section, the main section, and the removal section.

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

[0128] This section (steady state section) is a section that extends approximately halfway around the first butt joint J1 from the intermediate position S21 to an intermediate position E21 set on the surface 3a of the sealing body 3. In this section, the movement route R1 is set slightly inward (toward the sealing body 3) from the first butt joint J1. In this section, the rotary tool F moves at a generally constant depth.

[0129] The separation section is a section from the intermediate position E21 to the end position EP1. In the separation section, the insertion depth is set shallower than in the main section, and friction stir welding is performed. At the end position EP21, the rotary tool F is separated from the sealing body 3.

[0130] The preparation process is the same as in the first embodiment, and therefore a description thereof will be omitted. In the butting process, the jacket body 2 and the sealing body 3 are butted together in the same manner as in the first embodiment, forming a first butted portion J1 and a second butted portion J2. In addition, one side of the jacket body 2 and the sealing body 3, i.e., the lower side in FIG. 23 (below the imaginary center line O1 parallel to the width direction in the drawing), is clamped at three locations with clamps 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 workpieces (here, the jacket body 2). In the insertion process, the rotary tool F is inserted into a start position SP21 set on the end surface 11a of the peripheral wall portion 11. The insertion process is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0132] The pulling-up process, the changing process, and the pushing-in process are also the same as those in the first embodiment, and therefore will not be described here. The joining process is a process in which the workpieces (here, the jacket body 2 and the sealing body 3) are joined together while the rotary tool F is rotated in the direction opposite to the direction in which the spiral groove is formed, as shown in Fig. 23. That is, in the joining process, friction stir welding is performed while the rotary tool F is rotated in the forward direction.

[0133] After the rotary tool F is pushed to a predetermined insertion depth H4 in the above-described pushing step, the rotary tool F is moved to an intermediate position S21 and gradually pushed deeper until it reaches a predetermined insertion depth (e.g., insertion depth H5). Once the intermediate position S21 is reached, as shown in FIG. 24, the rotary tool F is moved along the first butt joint J1 with the rotation axis C aligned with the movement route R1. The movement route R1 and the first butt joint J1 are generally parallel. A plasticized region W11 is formed along the movement trajectory of the rotary tool F.

[0134] When the rotary tool F reaches the intermediate position E21, it transitions to the withdrawal section. As shown in Figure 25, in the withdrawal section, the rotary tool F is inserted to a shallower depth than in the main section, and friction stir welding is performed. That is, after passing the intermediate position E21, the rotary tool F is moved and slightly pulled up, and then moved a predetermined distance at an insertion depth H12. The insertion depth H12 of the rotary tool F in the withdrawal section is smaller than the insertion depth H11 of the rotary tool F in the main section (steady section). The insertion depth refers to the distance from the surface of the workpieces (here, the surface 3a of the sealing body 3) to the tip of the stirring pin F2.

[0135] The insertion depth H11 in the main section and the insertion depth H12 in the withdrawal section are set so as to satisfy H11 x 0.6 ≦ H12 < H11. Preferably, they are set so as to satisfy H11 x 0.65 ≦ H12 < H11 x 0.95, more preferably H11 x 0.7 ≦ H12 < H11 x 0.9, and even more preferably H11 x 0.75 ≦ H12 < H11 x 0.85. As an example, the insertion depth H11 in the main section (steady portion) 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 removal section, when the rotating tool F reaches the end position EP21, the rotating tool F is moved straight up to be removed from the surface 3a of the sealing body 3. A draw hole 30 is formed in the surface 3a of the sealing body 3. After the rotating tool F is removed, the clamp U1 is temporarily released, and one side of the jacket body 2 and the sealing body 3 is clamped again, as shown in FIG. 26 . In other words, the portions that were welded in the first friction stir welding step (three locations above the imaginary center line O1) are clamped again with the clamp U1.

[0137] <Second Friction Stir Welding Process> As shown in Figure 26, after the first friction stir welding process is completed, the second friction stir welding process is performed. In the second friction stir welding process (welding process), friction stir welding is performed from a start position (second point) SP22, turning back at a turn back position S22, passing through an intermediate position E22, to an end position EP22. The start position SP22 is set midway along the welding path and within the plasticized region W11 belonging to the first welding range generated by the first friction stir welding process. Here, the start position SP22 is set at the end position EP21. The second welding range is from the start position SP22, turning back at the turn back position S22, to the end position EP22.

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

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

[0140] A movement route R1 along which a rotation axis C of a rotation tool F (see FIG. 4) passes a start position SP22, a turn-back position S22, an intermediate position E22, and an 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 turn-back position S22 to the end position EP22), and includes a turn-back section, a main section, and a departure section. In this method, the joining process is performed in the turn-back section, the main section, and the departure section.

[0141] In the welding process, the rotary tool F is inserted into the void 30 (see FIG. 25 ) formed in the first friction stir welding process and pushed to a predetermined depth. After the rotary tool F is pushed, the process proceeds to the turn-back section. The turn-back section is a section in which the rotary tool F is moved from the start position SP22 to the turn-back position S22, turns back at the turn-back position S22, and then returns to the start position SP22. In the turn-back section, the rotary tool F is moved toward the turn-back position S22 while maintaining the predetermined depth. At this time, the rotary tool F is moved so that the plasticized region W12 formed in the second friction stir welding process and the plasticized region W11 formed in the first friction stir welding process overlap. As shown in FIG. 27 , from the start position SP22 to the turn-back position S22, the insertion depth H21 of the rotary tool F is set to be greater than the insertion depth H12 (see FIG. 25 ). In other words, it is desirable to insert and move the rotary tool F so that the entire depthwise area of ​​the plasticized region W11 formed in the first friction stir welding process is friction-stirred by the plasticized region W12 formed in the second friction stir welding process, in the range from the start position SP22 to the turnaround position S22.

[0142] As shown in Figure 28, when the rotary tool F reaches the turning position S22, the rotary tool F turns back and moves toward the starting position SP22. As shown in Figures 29 and 30, the rotary tool F is moved while maintaining the insertion depth H21 between the starting position SP22, the turning position S22, and the starting position SP22. The insertion depth H21 and the insertion depth H12 (see Figure 25) are set so that H12 < H21 ≦ H12 × 1.7 is satisfied. 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 is satisfied. 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 near the start position SP22 of the second friction stir welding process is set to 0.95 mm.

[0143] As shown in FIG. 30 , after the rotary tool F passes the start position SP22, friction stir welding is performed in this section 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 depths H22 and H21 are set so that H22 < H21 ≦ H22 × 1.4 is satisfied. 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 is satisfied. As an example, the insertion depth H21 in the turn-back 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] 31 , when the rotating tool F reaches the intermediate position E22, the process moves to the detachment section. In the detachment section, the rotating tool F is gradually pulled up while being moved from the intermediate position E22 to the end position EP22, and at the end position EP22, the rotating tool F is detached from the jacket main body 2. Through the above steps, a joined body is formed.

[0145] According to the manufacturing method of the welded body according to the present embodiment described above, the end position EP21 of the first welding area is also included in the second welding area, and the start position SP22 of the second welding area is included in the first welding area. Furthermore, in the second friction stir welding process, friction stir welding is performed from the start position SP22 of the second welding area to the turn-back position S22 set in the plasticized region W11 belonging to the first welding area, then the tool turns back at the turn-back position S22 and friction stir welds again through the start position SP22 for the second welding area to the end position EP22 for the second welding area. In this way, in the second friction stir welding process, the rotary tool F is moved so as to pass along the movement trajectory in the first friction stir welding process, thereby again performing friction stir welding on the plasticized region W11 belonging to the first welding area. Even if an oxide film is caught in the end of the plasticized region W11 belonging to the first welding range or a welding defect or the like occurs, in the second friction stir welding process, the end of the plasticized region W11 is also friction stirred again, so the remaining oxide film caught in the end is broken and the welding defect or the like is repaired, thereby improving the quality of the friction stir welding.

[0146] Furthermore, even in the case of a welding path that is too long to be friction stirred in a single process, by performing friction stirring in separate steps, the oxide film can be divided and welding defects, etc. can be repaired, making it possible to perform high-quality friction stirring on welding paths of various lengths.

[0147] Furthermore, according to this embodiment, in the insertion step, the stirring pin F2 is inserted into the workpieces (jacket body 2) while the rotary tool F is rotated (reverse rotation) in the same direction as the formation direction of the spiral groove. When the stirring pin F2 is inserted into the workpieces, the spiral groove acts on the workpieces like a drill bit, scraping away material from the workpieces as it penetrates. This actively ejects the workpieces to the outside as the stirring pin F2 is inserted, reducing the load on the rotary tool F and the welding device (not shown) when the rotary tool F is inserted to perform welding. Furthermore, the reduced load also reduces wear on the spiral groove of the stirring pin F2, reducing breakage of the stirring pin F2.

[0148] Furthermore, according to the insertion process, even if a pilot hole is not pre-drilled, the press-fit resistance can be reduced, allowing for smooth insertion of the stirring pin F2, thereby improving productivity. Furthermore, during the insertion process, it is presumed that the material of the workpieces that has been scraped off is expelled to the outside of the workpieces as the spiral groove rotates, similar to the chips generated by cutting with a drill. As a result, the material that has flowed out due to plastic flow is less likely to remain as burrs on the surfaces of the workpieces after friction stir welding. This reduces the burden of post-processing, such as cutting to remove burrs, thereby improving productivity.

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

[0150] In the present embodiment, the relationship between the insertion depth H11 of the rotary tool F in the main section (steady section) when performing friction stir welding on the first welding range in the first friction stir welding process and the insertion depth H12 of the rotary 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 section of the first friction stir welding process, welding is performed at the insertion depth H11, the rotary tool F is pulled up to the insertion depth H12 near the end position EP21, and then the rotary tool F is withdrawn at the end position EP21. As a result, the insertion depth H12 of the rotary tool F near the void 30 in the first friction stir welding process is smaller than the insertion depth H11 in the main section (steady section) when performing friction stir welding. This reduces the insertion depth required when inserting the rotary tool F in the second friction stir welding process, making it easier to friction stir weld the plasticized region W11 near the position of the void 30 formed in the first friction stir welding process in the second friction stir welding process.

[0151] Furthermore, by making the insertion depth H12 near the void 30 in the first friction stir welding process equal to or greater than a predetermined lower limit based on the insertion depth H11 in this section (steady-state portion), the depth and width of the joint near the void 30 can be secured, making it easier to increase the joint strength.

[0152] In this embodiment, the rotary tool F is inserted to an insertion depth H21 at the start position SP22 of the second friction stir welding process, and welding is performed at the insertion depth H21 until it passes the turn-back position S22 and the start position SP22. At this time, the insertion depth H21 of the rotary tool F when inserted in the second friction stir welding process is greater than the insertion depth H12 near the void 30 in the first friction stir welding process, which makes it easier to friction stir weld the plasticized region W11 near the void 30 formed in the first friction stir welding process in the second friction stir welding process.

[0153] Furthermore, 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 a predetermined upper limit value or less based on the insertion depth H12 near the extraction hole 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 an excessively large 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 main body 2 having a peripheral wall step portion 12 that has a step side surface 12b and a step bottom surface 12a and faces the recess 13, and the sealing body 3. In this case, a butt overlap portion is formed, which includes a first butt portion J1 formed by butting the step side surface 12b of the jacket main body 2 with the side surface 3c of the sealing body 3, and a second butt portion J2 (overlapping portion J2) formed by butting (overlapping) the step bottom surface 12a of the jacket main body 2 with the back surface 3b of the sealing body 3. If the insertion depth of the rotary tool F is too great when inserting the rotary tool F into the position of the first butt joint J1 to perform friction stir welding, buckling deformation may occur in the material of the portion of the peripheral wall step 12 that faces the recess 13 of the step bottom surface 12a. The occurrence of such defects can be suppressed 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 a predetermined upper limit value or less.

[0154] In this embodiment, the rotary tool F is inserted to an insertion depth H21 at the start position SP22, and welding is performed at the insertion depth H21 until it passes the turn-back position S22 and the start position SP22. Then, in the main section (steady-state portion), the rotary tool F is pulled up to the insertion depth H22 and then joined. In this manner, the insertion depth H21 of the rotary tool F when inserted in the second friction stir welding process is greater than the insertion depth H22 in the main section (steady-state portion) of the second friction stir welding process. This makes it easier to friction stir the plasticized region W11 near the blowout 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. Furthermore, by setting the insertion depth H21 of the rotary tool F when inserted in the second friction stir welding process to a predetermined upper limit value based on the insertion depth H22 in the main section (steady-state portion) of the second friction stir welding process, it is possible to suppress the occurrence of defects and tool damage caused by an excessively large insertion depth H21 near the start position S22 of the second friction stir welding process.

[0155] Furthermore, when the welding path in the welding process is a closed route as in this embodiment, there is a problem that the rotary tool F and the clamp U1 interfere with each other during the main welding process, making the work complicated. However, according to this embodiment, the clamping position and the friction stir welding position are separated in the first friction stir welding process and the second friction stir welding process, so that the friction stir welding work can be performed efficiently.

[0156] 9. Fourth Embodiment Next, a description will be given of a method for manufacturing a bonded body according to a fourth embodiment of the present invention. In the third embodiment, the inserting step, the pulling step, the changing step, and the pushing step are performed at a start position SP21. However, in this embodiment, the inserting step, the pulling step, the changing step, and the pushing step are performed at a start position SP22.

[0157] In this embodiment, as in 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 a start position SP21 to an end position EP21 via intermediate positions S21 and E21. When the rotary tool F is inserted at the start position SP21, the rotation direction and the like are set appropriately.

[0158] In the second friction stir welding, as shown in FIG. 29 , the rotary tool F is inserted into the start position SP22, moved from the start position SP22 to the turn-back position S22, turned back at the turn-back position S22, and friction stir welding is performed via the intermediate position E22 to the end position EP22. At the start position SP22, the insertion process, pulling-up process, change process, and thrust-in process described in the first embodiment are performed. In other words, in the second friction stir welding process, the insertion process, pulling-up process, change process, and thrust-in process are performed at the start position SP22 of the friction stir welding for the second welding range, and then the welding process is performed. Note that in this embodiment, the pulling-up process and thrust-in process may be omitted. Other aspects of this embodiment are generally the same as those of the third embodiment, and therefore description thereof will be omitted.

[0159] The present embodiment described above can also achieve effects substantially equivalent to those of the third embodiment. Furthermore, by inserting the stirring pin F2 into the position of the extraction hole 30 of the rotary tool F formed in the first friction stir welding process at the start position SP22 of the second friction stir welding process, the extraction hole 30 of the rotary tool F in the first friction stir welding process functions as a pilot hole, thereby reducing press-fit resistance and allowing the insertion of the stirring pin F2 to be performed smoothly, thereby improving productivity. Furthermore, in the second friction stir welding process, by performing friction stir welding through the start 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] Furthermore, even if the size and depth of the void 30 are small due to the rotary tool F and welding conditions in the first friction stir welding process, the insertion process in the second friction stir welding process can eject the welded parts at the position of the void 30 to the outside, thereby more reliably reducing the load on the rotary tool F and the welding device (not shown).

[0161] Furthermore, burrs may remain at the position of the extraction hole 30 of the rotary tool F formed by the first friction stir welding process. If burrs remain at the position of the extraction hole 30, these burrs become excess material and create resistance during insertion, which places a load on the rotary tool F and the welding device. In contrast, the insertion process in the second friction stir welding process of this embodiment makes it possible to remove burrs remaining at the end position EP21 of the first welding range as the rotary tool F rotates. Therefore, the burden of preprocessing such as cutting to remove burrs before the second friction stir welding process is reduced, thereby improving productivity.

[0162] 10. Fifth Embodiment Next, a fifth embodiment of the present invention will be described. In the manufacturing method of a welded body according to this embodiment, as shown in FIG. 32 , a jacket body 2A (omitted in FIG. 32 ) and a sealing body 3A, which are the same as those in the second embodiment, are welded to form a welded body. This embodiment differs from the first embodiment mainly in that the welding is performed in two separate steps, a first friction stir welding process and a second friction stir welding process, and that the rotary tool F is turned around to perform the friction stir welding. Also, in this embodiment, similar to the third embodiment, the first friction stir welding process and the second friction stir welding process are used to perform the friction stir welding of the welded members along the welding path. However, this embodiment differs from the third embodiment in that both the start position SP31 and the end position EP32 are set to the sealing body 3A. The correlation between the insertion depths (H11, H12, H21, H22) of the rotary tool F in this embodiment is the same as in the third embodiment, and will be described with reference to FIGS. 25 , 27 , 28 , and 30 as appropriate.

[0163] As shown in Figure 32, in the first friction stir welding process, friction stir welding is performed from a start position SP31 to an end position EP31 via intermediate positions S31 and E31. In the second friction stir welding process, friction stir welding is performed from a start position SP32 (the same position as the end position EP31) to a turnback position S32, via the intermediate position E32, and to an end position EP32. The welding path in this embodiment refers to a clockwise rotation around the sealing body 3A 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 at one end of the welding path formed 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 at the other end opposite to the one end of the welding path. The end position EP31 of the first friction stir welding process is set as a first point located midway along the welding path, and is set as a second point located within the plasticized region belonging to the first welding range. The end position EP31 of the first friction stir welding process is a point at the end of the plasticized region belonging to the first welding range. The start position SP32 of the second friction stir welding process is set as a point at the end of the plasticized region belonging to the first welding range.

[0164] <First Friction Stir Welding Process> The first friction stir welding process includes a preparation process, an overlapping process, an insertion process, a pulling-up process, a changing process, a push-in process, and a welding process. In this embodiment, as shown in FIG. 19 , the end surface 11a of the jacket main body 2A and the back surface 3b of the sealing body 3A are overlapped to form an overlapping portion J3. In the first friction stir welding process, friction stir welding is performed from a start position SP31 to an end position (first point) EP31 via intermediate positions S31 and E31. The first welding range is from the start position SP31 to the end position EP31. 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 with the overlapping portion J3. The intermediate position S31 is set on the surface 3a of the sealing body 3A near the start position SP31 while overlapping with the overlapping 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 with the overlapping portion J3. The intermediate position E31 is set on the surface 3a of the sealing body 3A near the end position EP31 while overlapping with the overlapping portion J3.

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

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

[0167] This section (steady state section) is a section from the intermediate position S31 to an intermediate position E31, approximately halfway around along the overlap section J3. In this section, the rotary tool F is moved at a substantially constant depth.

[0168] The removal section is a section from the intermediate position E31 to the end position EP31. In the removal section, the insertion depth is set shallower than in the main section, and friction stir welding is performed, and the rotary tool F is removed from the sealing body 3A at the end position EP31.

[0169] The preparation process is the same as in the second embodiment, and therefore a description thereof will be omitted. In the overlapping process, the jacket main body (members to be joined) 2A and the sealing body (members to be joined) 3A are overlapped in the same manner as in the second embodiment to form the overlapping portion J3. Furthermore, one side of the jacket main body 2A and the sealing body 3A, i.e., the lower side in FIG. 32 (below the imaginary center line O1 parallel to the width direction in the drawing), is clamped at three locations with clamps U1 to fix the jacket main body 2A and the sealing body 3A.

[0170] The insertion process is a process of inserting the rotary tool F into the workpieces (here, the sealed body 3A). In the insertion process, the rotary tool F is inserted into a start position SP31. The insertion process is the same as in the first embodiment, and therefore a description thereof will be omitted.

[0171] The pulling-up process, the changing process, and the pushing-in process are also the same as those in the first embodiment, and therefore will not be described here. The joining process is a process in which the workpieces (here, the jacket body 2A and the sealing body 3A) are joined while the rotary tool F is rotated in the direction opposite to the direction in which the spiral groove is formed. That is, in the joining process, friction stir welding is performed while the rotary tool F is rotated in the forward direction.

[0172] In the above-described pushing step, the rotary tool F is pushed to a predetermined insertion depth H4, and then the rotary tool F is moved to an intermediate position S31, gradually pushing inward until it reaches a predetermined insertion depth (e.g., insertion depth H5). When the intermediate position S31 is reached, the rotary tool F is moved along the overlap portion J3 with the rotation axis C of the rotary tool F overlapping the movement route R3, as shown in FIG. 33. A plasticized region W21 is formed along the movement trajectory of the rotary tool F.

[0173] When the rotary tool F reaches the intermediate position E31, it transitions to the withdrawal section. In the withdrawal section, the rotary tool F is inserted to a shallower depth than in the main section, and friction stir welding is performed. That is, after passing the intermediate position E31, the rotary tool F is moved and slightly pulled up, and moved a predetermined distance at an insertion depth H12 (see FIG. 25 ). The insertion depth H12 of the rotary tool F in the withdrawal section is smaller than the insertion depth H11 of the rotary tool F in the main section (steady section). The relationship between the insertion depth H11 in the main section and the insertion depth H12 in the withdrawal section is the same as that in the third embodiment.

[0174] In the removal section, when the rotating tool F reaches the end position EP31, the rotating tool F is moved straight up to remove it from the surface 3a of the sealing body 3A. A draw hole 30 (see FIG. 25) is formed in the surface 3a of the sealing body 3A. After the rotating tool F is removed, the clamp U1 is temporarily released, and one side of the jacket body 2A and the sealing body 3A is clamped again, as shown in FIG. 34. In other words, the portions that were welded in the first friction stir welding step (three locations above the imaginary center line O1) are clamped again with the clamp U1.

[0175] <Second Friction Stir Welding Process> As shown in Figure 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 (welding process), friction stir welding is performed from a start position (second point) SP32, turning back at a turn back position S32, passing through an intermediate position E32, to an end position EP32. The start position SP32 is set midway along the welding path and within the plasticized region W21 belonging to the first welding range generated by the first friction stir welding process. Here, the start position SP32 is set at the end position EP31. The second welding range is from the start position SP32, turning back at the turn back position S32, to the end position EP32.

[0176] The turn-back position S32 is set on the upstream side (start position SP31 side) of the intermediate position E31. In other words, the turn-back position S32 is set so that the intermediate position E31 is located between the turn-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 left side in the width direction above the imaginary center line O1 in Fig. 35. The intermediate position E32 is set on the surface 3a of the sealing body 3A near the end position EP32.

[0178] The movement route R3 along which the rotation axis C of the rotation tool F (see FIG. 4) passes is a start position SP32, a turn-back position S32, an intermediate position E32, and an 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 turn-back position S32 to the end position EP32), and includes a turn-back section, a main section, and a departure section. In this method, the joining process is performed in the turn-back section, the main section, and the departure section.

[0179] In the welding process, the rotary tool F is inserted into the void 30 (see FIG. 25 ) formed in the first friction stir welding process and pushed to a predetermined depth. After the rotary tool F is pushed in, the process proceeds to the turn-back section. The turn-back section is a section in which the rotary tool F is moved from the start position SP32 to the turn-back position S32, turns back at the turn-back position S32, and then returns to the start position SP32. In the turn-back section, the rotary tool F is moved toward the turn-back position S32 while maintaining the predetermined depth. At this time, the rotary tool F is moved so that the plasticized region W22 formed in the second friction stir welding process and the plasticized region W21 formed in the first friction stir welding process overlap. From the start position SP32 to the turn-back position S32, the insertion depth H21 (see FIG. 28 ) of the rotary tool F is set to be greater than the insertion depth H12 (see FIG. 25 ). In other words, it is desirable to insert and move the rotary tool F so that the entire depthwise area of ​​the plasticized region W21 formed in the first friction stir welding process is friction-stirred by the plasticized region W22 formed in the second friction stir welding process, in the range from the start position SP32 to the turnaround position S32.

[0180] When the rotary tool F reaches the turning position S32, the rotary tool F turns back and moves toward the starting position SP32. The rotary tool F is moved from the starting position SP32 to the turning position S32 and back to the starting position SP32 while maintaining the insertion depth H21 (see FIGS. 28 and 30). The relationship between the insertion depth H12 in the turning section and the insertion depth H21 in the removal section is the same as that in the third embodiment.

[0181] As shown in Fig. 35, after the rotary tool F passes the start position SP32, friction stir welding is performed in this section up to an intermediate position E32. The insertion depth H22 (see Fig. 30) of the rotary tool F in this section (steady section) 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 section) is the same as in the third embodiment.

[0182] 35 , when the rotary tool F reaches the intermediate position E32, the process moves to the removal section. In the removal section, the rotary tool F is gradually pulled up while moving from the intermediate position E32 to the end position EP32, and the rotary tool F is removed from the sealed body 3A at the end position EP32. A bonded body is formed by the above steps.

[0183] According to the manufacturing method of the welded body according to the present embodiment described above, the end position EP31 of the first welding area is also included in the second welding area, and the start position SP32 of the second welding area is included in the first welding area. Furthermore, in the second friction stir welding process, friction stir welding is performed from the start position SP32 of the second welding area to the turn-back position S32 set in the plasticized area W21 belonging to the first welding area, then the tool turns back at the turn-back position S32, and friction stir welding is performed again through the start position SP32 for the second welding area to the end position EP32 for the second welding area. In this way, in the second friction stir welding process, the rotary tool F is moved so as to pass along the movement trajectory in the first friction stir welding process, thereby again performing friction stir welding on the plasticized area W21 belonging to the first welding area. Even if an oxide film is caught in the edge of the plasticized region W21 belonging to the first welding area or a welding defect or the like occurs, in the second friction stir welding process, the edge of the plasticized region W21 is also friction stirred again, so the oxide film caught in the edge and remaining there is cut off, and the welding defect or the like is repaired, thereby improving the quality of the friction stir welding.

[0184] Furthermore, even in the case of a welding path that is too long to be friction stirred in a single process, by performing friction stirring in separate steps, the oxide film can be divided and welding defects, etc. can be repaired, making it possible to perform high-quality friction stirring on welding paths of various lengths.

[0185] Furthermore, according to this embodiment, in the insertion step, the stirring pin F2 is inserted into the workpieces (sealed body 3A) while rotating the rotary tool F in the same direction as the formation direction of the spiral groove (reverse rotation). When the stirring pin F2 is inserted into the workpieces, the spiral groove acts on the workpieces like a drill bit, scraping away material from the workpieces as it penetrates. This actively ejects the workpieces to the outside as the stirring pin F2 is inserted, reducing the load on the rotary tool F and the welding device (not shown) when the rotary tool F is inserted. Furthermore, the reduced load also reduces wear on the spiral groove of the stirring pin F2, reducing breakage of the stirring pin F2.

[0186] Furthermore, according to the insertion process, even if a pilot hole is not pre-drilled, the press-fit resistance can be reduced, allowing for smooth insertion of the stirring pin F2, thereby improving productivity. Furthermore, during the insertion process, it is presumed that the material of the workpieces that has been removed is expelled to the outside of the workpieces as the spiral groove rotates, similar to the chips generated by cutting with a drill. As a result, the material that has flowed out due to plastic flow is less likely to remain as burrs on the surfaces of the workpieces after friction stir welding, reducing the burden of post-processing such as cutting to remove burrs and improving productivity.

[0187] Furthermore, by inserting the stirring pin F2 into the extraction hole 30 of the rotary tool F formed in the first friction stir welding process at the start position SP32 of the second friction stir welding process, the extraction hole 30 of the rotary tool F in the first friction stir welding process functions as a pilot hole, thereby reducing press-fit resistance and allowing the stirring pin F2 to be inserted smoothly, thereby improving productivity. Furthermore, in the second friction stir welding process, by performing friction stir welding through the start position SP32 for the second welding range, the extraction hole 30 can be filled with the plasticized region W22 formed by friction stir welding.

[0188] In the present embodiment, the relationship between the insertion depth H11 of the rotary tool F in the main section (steady section) when friction stir welding the first welding range in the first friction stir welding process and the insertion depth H12 of the rotary tool F near the end position EP31 in the first friction stir welding process is set to be H11 × 0.6 ≦ H12 < H11. That is, in the steady section of the first friction stir welding process, welding is performed at the insertion depth H11, the rotary tool F is pulled up to the insertion depth H12 near the end position EP31, and then the rotary tool F is withdrawn at the end position EP31. As a result, the insertion depth H12 of the rotary tool F near the void 30 in the first friction stir welding process is smaller than the insertion depth H11 in the main section (steady section) when friction stir welding is performed. This reduces the insertion depth required when inserting the rotary tool F in the second friction stir welding process, making it easier to friction stir weld the plasticized region W21 near the position of the void 30 formed in the first friction stir welding process in the second friction stir welding process.

[0189] Furthermore, by making the insertion depth H12 near the void 30 in the first friction stir welding process equal to or greater than a predetermined lower limit based on the insertion depth H11 in this section (steady-state portion), the depth and width of the joint near the void 30 can be secured, making it easier to increase the joint strength.

[0190] In this embodiment, the rotary tool F is inserted to an insertion depth H21 at the start position SP32 of the second friction stir welding process, and welding is performed at the insertion depth H21 until the rotary tool F passes the turn-back position S32 and the start position SP32. At this time, the insertion depth H21 of the rotary tool F when inserted in the second friction stir welding process is greater than the insertion depth H12 near the void 30 in the first friction stir welding process, which makes it easier to friction stir weld the plasticized region W21 near the void 30 formed in the first friction stir welding process in the second friction stir welding process.

[0191] Furthermore, 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 a predetermined upper limit value or less based on the insertion depth H12 near the extraction hole 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 an excessively large 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 main body 2 having a peripheral wall step portion 12 that has a step side surface 12b and a step bottom surface 12a and faces the recess 13, and the sealing body 3. In this case, a butt overlap portion is formed, which includes a first butt portion J1 formed by butting the step side surface 12b of the jacket main body 2 with the side surface 3c of the sealing body 3, and a second butt portion J2 (overlapping portion J2) formed by butting (overlapping) the step bottom surface 12a of the jacket main body 2 with the back surface 3b of the sealing body 3. If the insertion depth of the rotary tool F is too great when inserting the rotary tool F into the position of the first butt joint J1 to perform friction stir welding, buckling deformation may occur in the material of the portion of the peripheral wall step 12 that faces the recess 13 of the step bottom surface 12a. The occurrence of such defects can be suppressed 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 a predetermined upper limit value or less.

[0192] In this embodiment, the rotary tool F is inserted to an insertion depth H21 at the start position SP32, and welding is performed at the insertion depth H21 until it passes the turn-back position S32 and the start position SP32, and then the rotary tool F is pulled up to an insertion depth H22 in the main section (steady section) and welding is performed. In this way, the insertion depth H21 of the rotary tool F when inserted in the second friction stir welding process is greater than the insertion depth H22 in the main section (steady section) of the second friction stir welding process, which makes it easier to friction stir weld the plasticized region W21 near the blowout 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. Furthermore, 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 a predetermined upper limit value based on the insertion depth H21 of the insertion depth H22 in this section (steady-state portion) of the second friction stir welding process, it is possible to suppress the occurrence of defects and damage to the tool caused by the insertion depth H21 being excessively large near the start position SP32 of the second friction stir welding process.

[0193] Furthermore, when the welding path in the welding process is a closed route as in this embodiment, there is a problem that the rotary tool F and the clamp U1 interfere with each other during the main welding process, making the work complicated. However, according to this embodiment, the clamping position and the friction stir welding position are separated in the first friction stir welding process and the second friction stir welding process, so that the friction stir welding work can be performed efficiently.

[0194] 11. Sixth Embodiment Next, a description will be given of a method for manufacturing a bonded body according to a sixth embodiment of the present invention. In the fifth embodiment, the inserting step, the pulling step, the changing step, and the pushing step are performed at a start position SP31. However, in this embodiment, the inserting step, the pulling step, the changing step, and the pushing step are performed at a start position SP32.

[0195] In this embodiment, as in 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 a start position SP31 to an end position EP31 via intermediate positions S31 and E31. When the rotary tool F is inserted at the start position SP31, the rotation direction and the like are set appropriately.

[0196] In the second friction stir welding, as shown in FIG. 34 , the rotary tool F is inserted at the start position SP32, turned back at the turn-back position S32, and friction stir welding is performed via the intermediate position E32 to the end position EP32. At the start position SP32, the insertion process, pulling-up process, change process, and thrust-in process described in the first embodiment are performed. In other words, in the second friction stir welding process, the insertion process, pulling-up process, change process, and thrust-in process are performed at the start position SP32 of the friction stir welding for the second welding range, and then the welding process is performed. Note that in this embodiment, the pulling-up process and thrust-in process may be omitted. Other aspects of this embodiment are generally the same as those of the fifth embodiment, so description thereof will be omitted.

[0197] The present embodiment described above also achieves substantially the same effects as the fifth embodiment. Furthermore, by inserting the stirring pin F2 into the position of the bleed hole 30 of the rotary tool F formed in the first friction stir welding process at the start position SP32 of the second friction stir welding process, the bleed hole 30 of the rotary tool F in the first friction stir welding process functions as a pilot hole, thereby reducing press-fit resistance and allowing the stirring pin F2 to be inserted smoothly, thereby improving productivity. Furthermore, in the second friction stir welding process, by performing friction stir welding through the start position SP32 for the second welding range, the bleed hole 30 can be filled with the plasticized region W22 formed by friction stir welding.

[0198] Furthermore, even if the size and depth of the void 30 are small due to the rotary tool F and welding conditions in the first friction stir welding process, the insertion process in the second friction stir welding process can eject the welded parts at the position of the void 30 to the outside, thereby more reliably reducing the load on the rotary tool F and the welding device (not shown).

[0199] Furthermore, burrs may remain at the position of the bleed hole 30 of the rotary tool F formed by the first friction stir welding process. If burrs remain at the position of the bleed hole 30, these burrs become excess material and create resistance during insertion, which places a load on the rotary tool F and the welding device. In contrast, the insertion process in the second friction stir welding process of this embodiment makes it possible to remove burrs remaining at the end position EP31 of the first welding range as the rotary tool F rotates. This reduces the burden of preprocessing such as cutting to remove burrs before the second friction stir welding process, thereby improving productivity.

[0200] [12. Other] Although the embodiments of the present invention have been described above, appropriate design modifications are possible. For example, the third embodiment and the fourth embodiment may be combined. In this case, the inserting 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 welding process and the start position SP22 of the second friction stir welding process.

[0201] The fifth embodiment and the sixth embodiment may be combined. In this case, the inserting step, the pulling up step, the changing step, and the pushing step are performed at both the start position SP31 of the first friction stir welding step and the start position SP32 of the second friction stir welding step.

[0202] Furthermore, the third to sixth embodiments can be combined with the first to fourth modified examples of the first embodiment, and the fifth and sixth embodiments can be combined with the first modified example of the second embodiment.

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

[0204] Tests 1 and 2 were conducted to confirm the effects of the present invention. Tests 1 and 2 did not involve joining two members, but rather used a single member to confirm the state of friction stirring with a rotary tool F. Fig. 36 is a table showing the conditions of the shape, rotation direction, and tool rotation speed of the rotary tool in Tests 1 and 2. Fig. 37 is a table showing the movement speed, insertion depth, pull-up amount, insertion amount, evaluation, and alloy type in Tests 1 and 2.

[0205] [Test 1] In Test 1, a test material (A1050) was prepared, and friction stirring was performed at a predetermined distance using a 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 end 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 welding speed was 125 mm / min.

[0206] <Test Example 11> Figure 38 is a plan view showing the friction stir welding state of Test Example 11. Figure 39 is a cross-sectional view taken along line XXXIX-XXXIX in Figure 38. In Test Example 11, a rotary tool F equipped with a stirring pin F2 having a left-handed spiral groove was inserted at a start position SP11 while rotating counterclockwise, and then the rotary tool F was pulled up, the rotation direction was changed to clockwise, and the rotary tool F was pushed in, and then friction stir welding was performed. In Test Example 11, the rotation speed of the rotary tool F during insertion was 2000 rpm, the rotation speed of the rotary tool F during pulling up was 2000 rpm, the rotation speed of the rotary tool F during pushing in was 890 rpm, and the rotation speed of the rotary tool F during friction stir welding was 890 rpm. In addition, in Test Example 11, the insertion depth H1 during insertion was 15 mm, the pull-up amount H2 during pull-up was 1 mm, the insertion depth during pull-up (when the rotation direction was changed) was 14 mm, the insertion amount H3 during push-in was 0.5 mm, the insertion depth H4 after push-in was 15.5 mm, and the insertion depth H5 during friction stir welding was 15.5 mm. In Test Example 11, as shown in Figure 38, the number of burrs V11 at the start position SP11 was smaller than in Comparative Test Examples 11 and 12. Also, as shown in Figure 39, there were no tunnel-shaped defects in the plasticized region W11.

[0207] Comparative Test Example 11: Figure 40 is a plan view showing the friction stir welding state of Comparative Test Example 11. Figure 41 is a cross-sectional view taken along line XLI-XLI in Figure 40. In Comparative Test Example 11, a rotary tool F equipped with a stirring pin F2 having a left-handed spiral groove was inserted at a start position SP12 with clockwise rotation, then inserted to the depth required for friction stir welding, and friction stir welding was performed with clockwise rotation. The rotational speed of the rotary tool F during insertion was 890 rpm, and the rotational speed of the rotary tool F during friction stir welding was also 890 rpm. The insertion depth during insertion was 15.5 mm, and the insertion depth H5 during friction stir welding was 15.5 mm. As shown in Figures 40 and 41, in Comparative Test Example 11, no tunnel defects were found within the plasticized region W12. However, as shown in Figure 40, many burrs V12 were generated at the start position SP12.

[0208] Comparative Test Example 12 Figure 42 is a plan view showing the friction stir welding state of Comparative Test Example 12. Figure 43 is an enlarged plan view at the start position of Figure 42. Figure 44 is a cross-sectional view taken along line XLIV-XLIV of Figure 42. In Comparative Test Example 12, a rotary tool F equipped with a stirring pin F2 having a left-handed spiral groove was inserted at a start position SP13 with clockwise rotation, then the rotary tool F was pulled up and pushed in without changing the rotation direction, and friction stir welding was performed with the rotary tool F still rotating clockwise. In Comparative Test Example 12, the rotational speed of the rotary tool F during insertion, the rotational speed of the rotary tool F during pulling up, the rotational speed of the rotary tool F during pushing in, the rotational speed of the rotary tool F during friction stir welding, the insertion depth H1 during insertion, the pull-up amount H2 during pulling up, the insertion depth when pulled up, the insertion amount H3 during pushing in, the insertion depth H4 after pushing in, and the insertion depth H5 during friction stir welding were the same as those in Test Example 11. In Comparative Test Example 12, no tunnel defects were found in the plasticized region W13, as shown in Figure 44. However, many burrs V13 were found at the start position SP13, as shown in Figures 42 and 43.

[0209] Comparative Test Example 13 Figure 45 is a plan view showing the friction stir welding state of Comparative Test Example 13. Figure 46 is an enlarged plan view at the start position of Figure 45. Figure 47 is a cross-sectional view taken along line XLVII-XLVII of Figure 45. In Comparative Test Example 13, a rotary tool F equipped with a stirring pin F2 having a left-handed spiral groove was inserted at a start position SP14 with counterclockwise rotation, then the rotary tool F was pulled up and pushed in without changing the rotation direction, and friction stir welding was performed with the tool F rotated counterclockwise. In Comparative Test Example 13, the rotational speed of the rotary tool F during insertion, the rotational speed of the rotary tool F during pulling up, the rotational speed of the rotary tool F during pushing in, the rotational speed of the rotary tool F during friction stir welding, the insertion depth H1 during insertion, the pull-up amount H2 during pulling up, the insertion depth when pulled up, the insertion amount H3 during pushing in, the insertion depth H4 after pushing in, and the insertion depth H5 during friction stir welding were the same as in Test Example 1. In Comparative Test Example 13, as shown in Figures 45 and 46, the number of burrs V14 at the start position SP14 was smaller than in Comparative Test Examples 11 and 12. However, as shown in Figure 47, tunnel-shaped defects T14 occurred within the plasticized region W14.

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

[0211] <Test Example 21> Figure 48 is a plan view showing the friction stirring state of Test Example 21. Figure 49 is an enlarged plan view at the start position of Figure 48. In Test Example 21, a rotary tool F equipped with a stirring pin F2 with a left-handed spiral groove was inserted at start position SP15 while rotating counterclockwise, and then the rotary tool F was pulled up, the rotation direction was changed to clockwise, and the rotary tool F was pushed in, and then friction stirring was performed. The rotation speed of the rotary tool F when inserted was 2000 rpm, the rotation speed of the rotary tool F when pulled up was 2000 rpm, the rotation speed of the rotary tool F when pushed in was 400 rpm, and the rotation speed of the rotary tool F during friction stirring was 400 rpm. In addition, in Test Example 21, the insertion depth H1 during insertion was 15 mm, the pull-up amount H2 during pull-up was 1 mm, the insertion depth when changing the rotation direction was 14 mm, the insertion amount H3 during push-in was 0.5 mm, the insertion depth H4 after push-in was 15.5 mm, and the insertion depth H5 during friction stir welding was 15.5 mm. In Test Example 21, as shown in Figures 48 and 49, the burr V15 at the start position SP15 was smaller than in Comparative Test Examples 21 and 22.

[0212] <Test Example 22> Figure 50 is a plan view showing the friction stir welding state of Test Example 22. Figure 51 is an enlarged plan view at the start position of Figure 50. Figure 52 is a cross-sectional view taken along line LII-LII in Figure 50. In Test Example 22, a rotary tool F equipped with a stirring pin F2 with a left-handed spiral groove was inserted at the start position SP16 with a counterclockwise rotation, then the rotary tool F was pulled up, the rotation direction was changed to a clockwise rotation, and the rotary tool F was pushed in and friction stir welding was performed. Test Example 22 was performed in the same manner as Test Example 21, except that the rotational speed of the rotary tool F was changed to 400 rpm during insertion and 400 rpm during withdrawal. As shown in Figures 51 and 52, the number of burrs V16 at the start position SP16 was smaller than in Comparative Test Examples 21 and 22. Furthermore, as shown in Figure 52, no defects were found within the plasticized region W16.

[0213] <Comparative Test Example 21> Figure 53 is a plan view showing the friction stir welding state of Comparative Test Example 21. Figure 54 is an enlarged plan view of the start position of Figure 53. In Comparative Test Example 21, a rotary tool F equipped with a stirring pin F2 having a left-handed spiral groove was inserted at a start position SP17 with clockwise rotation, then inserted to a depth required for friction stir welding, and friction stir welding was performed with clockwise rotation. In Comparative Test Example 21, the rotation speed of the rotary tool F during insertion was 400 rpm, and the rotation speed of the rotary tool F during friction stir welding was 400 rpm. Also, in Comparative Test Example 21, the insertion depth during insertion was 15.5 mm, and the insertion depth H5 during friction stir welding was 15.5 mm. In Comparative Test Example 21, as shown in Figures 53 and 54, many burrs V17 were generated at the start position SP17.

[0214] Comparative Test Example 22 Figure 55 is a plan view showing the friction stir welding state of Comparative Test Example 22. Figure 56 is an enlarged plan view at the start position of Figure 55. Figure 57 is a cross-sectional view taken along line LVII-LVII of Figure 55. In Comparative Test Example 22, a rotary tool F equipped with a stirring pin F2 having a left-handed spiral groove was inserted at a start position SP18 with clockwise rotation, then the rotary tool F was pulled up and pushed in without changing the rotation direction, and friction stir welding was performed with the rotary tool F still rotating clockwise. In Comparative Test Example 22, the rotational speed of the rotary tool F during insertion, the rotational speed of the rotary tool F during pulling up, the rotational speed of the rotary tool F during pushing in, the rotational speed of the rotary tool F during friction stir welding, the insertion depth H1 during insertion, the pull-up amount H2 during pulling up, the insertion depth when pulled up, the insertion amount H3 during pushing in, the insertion depth H4 after pushing in, and the insertion depth H5 during friction stir welding were the same as those in Test Example 21. In Comparative Test Example 2, no tunnel defects were found in the plasticized region W18, as shown in Figure 57. However, many burrs V18 were found at the start position SP18, as shown in Figures 55 and 56.

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

[0216] Furthermore, it was found that a tunnel defect T14 occurs when the rotating tool F is rotated in the reverse direction (left-handed rotation when the spiral groove is left-handed, or right-handed rotation when the spiral groove is right-handed) during friction stir welding, as in Comparative Test Example 13. On the other hand, it was found that a good welding condition is achieved when the rotating tool F is inserted in the forward direction (right-handed rotation when the spiral groove is left-handed, or left-handed rotation when the spiral groove is right-handed) during friction stir welding, as in Test Examples 11, 21, and 22.

[0217] In other words, it was found that by using reverse rotation during insertion (insertion process) and forward rotation during friction stir welding (joining process) as in the present invention, it is possible to reduce burrs at the starting position and eliminate defects during friction stir welding.

[0218] DESCRIPTION OF SYMBOLS 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 pin G3 Tip end pin J1 First butt portion (butt portion) J2 Second butt portion (butt portion) J3 Overlapped portion 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 Start position EP1, EP3, EP21, EP22, EP31, EP32 End position W, W11, W12, W21, W22 Plasticization area

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 with a spiral groove, the method comprising: a first friction stir joining step of performing friction stirring in 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; a second friction stir joining step of performing friction stirring in 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 joining step to the other end side of the joining path; in the first friction stir joining step, the start position of 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 the first point provided in the middle of the joining path; in the second friction stir joining step, the start position of 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, the end position of friction stirring with respect to the second joining range is set at the other end side of the joining path opposite to the one end side, and friction stirring is performed from the start position with respect to 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 stirring of the plasticized region is performed toward the other end side of the joining path, and then friction stirring of the remaining joining path is performed from the start position with respect to the second joining range again through the start position with respect to the second joining range to the end position with respect to the second joining range; in the first friction stir joining step, at the start position of friction stirring with respect to the first 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; which are sequentially provided. A method for manufacturing a joined body, characterized in that.

2. The method for manufacturing a joined body according to claim 1, wherein in the second friction stir joining step, the start position of friction stirring with respect to the second joining range is the position of the punched 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 in the second friction stir welding process 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. Further comprising a pulling-up process of pulling up the rotating tool in the surface direction of the workpiece after the insertion process, and performing the changing process after the pulling-up process. 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 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 claim 8.

10. Further comprising a pushing-in process of pushing the rotating tool in the depth direction of the workpiece after the changing process, and performing the joining process after the pushing-in process. 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 pushing-in process is H1 × 0.01 ≦ H3 ≦ H1 × 0.

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

12. The manufacturing method of the 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 planar or mortar-shaped lower end surface and further has a shoulder portion presenting a columnar or trapezoidal shape. The stirring pin hangs down from the lower end surface of the shoulder portion. While bringing the shoulder portion into contact with the member to be joined, friction stir joining is performed on the member to be joined with the stirring pin inserted into the member to be joined. The manufacturing method of the joined body according to claim 1.

14. The manufacturing method of the 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 presenting a columnar or trapezoidal shape. The stirring pin hangs down from the lower end surface of the base. While separating the base from the member to be joined, friction stir joining is performed on the member to be joined with only the stirring pin inserted into the member to be joined. The manufacturing method of the joined body according to claim 1.

16. The rotary tool has a base presenting a columnar or trapezoidal shape. The stirring pin has a proximal-side pin continuous with the base 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. 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. The manufacturing method of the joined body according to claim 1.

17. The manufacturing method of the joined body according to claim 1, further comprising a pilot hole forming step of forming a pilot hole in the member to be joined before the insertion step, and inserting the stirring pin into the pilot hole in the insertion step.

18. The joined member includes a first joined member and a second joined member having a lower hardness than the first joined member, and at least one end face of either the first joined member or the second joined member is abutted 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, the 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 a joined body according to claim 1.

19. The joined member includes a first joined member and a second joined member. At least one end face of either the first joined member or the second joined member is abutted 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, the stirring pin is inserted toward the butted portion or the overlapping portion. The method for manufacturing a joined body according to claim 1.

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