Friction stir welding jig, machine tool, and method for processing workpiece

Abstract

This friction stir welding jig comprises: a backing member that receives pressing force from a friction stir welding tool via a first workpiece serving as an object to be welded and supports the first workpiece; a holding member that holds the first workpiece; and at least one nozzle that is disposed on the backing member and discharges a coolant toward the first workpiece.

Description

Friction Stir Welding Tool, Machine Tool, and Workpiece Processing Method 【0001】 The present invention relates to a friction stir welding tool, a machine tool, and a workpiece processing method. 【0002】 A friction stir welding device provided with a cooling means is known. 【0003】 As a related technique, Patent Document 1 discloses a friction welding method. In the friction welding method described in Patent Document 1, a metal rod made of a material harder than the material of the workpiece is inserted into the welded portion of the workpiece. Support means detachably provided on the back surface of the welded portion of the workpiece supports the load by the metal rod. FIG. 6 of Patent Document 1 shows a state where friction welding is performed in a water tank. 【0004】 Japanese Patent Application Laid-Open No. 2000-153377 【0005】 An object of the present invention is to provide a friction stir welding tool, a machine tool, and a workpiece processing method that enable friction stir welding while efficiently cooling a workpiece as a joining object. 【0006】 Embodiments of the present invention relate to the following friction stir welding tool, machine tool, and workpiece processing method. 【0007】(1) A friction stir welding jig comprising: a backing member that receives pressing force from a friction stir welding tool via a first workpiece as an object to be joined and supports the first workpiece; a holding member that holds the first workpiece; and at least one nozzle disposed on the backing member for discharging coolant toward the first workpiece. (2) A machine tool comprising: a friction stir welding jig on which a first workpiece as an object to be joined is fixed and which comprises at least one nozzle for discharging coolant toward the first workpiece; a support device for supporting the friction stir welding jig; a machining head comprising a spindle and a support body that rotatably supports the spindle around a first axis; a rotational drive device for rotating the spindle around the first axis; a moving device for moving the machining head relative to the support device; and a supply device for supplying the coolant to the at least one nozzle, wherein the friction stir welding jig comprises: a backing member that receives pressing force from a friction stir welding tool via a first workpiece and supports the first workpiece; a holding member that holds the first workpiece; and the at least one nozzle disposed on the backing member. (3) A workpiece processing method comprising the steps of: attaching the first workpiece to a friction stir welding jig so that the first workpiece as the object to be joined is held by a holding member of the friction stir welding jig; joining the first workpiece and the second workpiece by friction stir while the backing member of the friction stir welding jig is receiving pressing force from a friction stir welding tool via the first workpiece; and discharging a cooling liquid to the first workpiece from at least one nozzle arranged on the backing member during the execution of the friction stir. 【0008】 The present invention provides a friction stir welding jig, a machine tool, and a workpiece processing method that enable friction stir welding while efficiently cooling the workpiece to be joined. 【0009】Figure 1 is a schematic perspective view showing a friction stir welding jig in the first embodiment. Figure 2 is a schematic perspective view showing the friction stir welding jig with the first workpiece attached. Figure 3 is a schematic perspective view showing the friction stir welding jig with the first and second workpieces supported. Figure 4 is a schematic cross-sectional view showing the welding mode being performed. Figure 5 is a schematic diagram showing a machine tool in the first embodiment. Figure 6 is a schematic perspective view showing a friction stir welding jig in the first embodiment. Figure 7 is a schematic cross-sectional view showing the friction stir welding jig in a first modified example of the first embodiment with the first and second workpieces supported. Figure 8 is a schematic perspective view showing a friction stir welding jig in the first embodiment. Figure 9 is a schematic cross-sectional view showing the welding mode being performed. Figure 10 is a schematic cross-sectional view showing the welding mode being performed. Figure 11 is a schematic perspective view showing a friction stir welding jig in a second modification of the first embodiment. Figure 12 is a schematic perspective view showing the first workpiece and the second workpiece supported by the friction stir welding jig in a second modification of the first embodiment. Figure 13 is a schematic perspective view showing the welding mode being performed. Figure 14 is a schematic perspective view showing the welding mode being performed. Figure 15 is a schematic perspective view showing the welding mode being performed. Figure 16 is a schematic perspective view showing the welding mode being performed. Figure 17 is a schematic perspective view showing an example of the first workpiece. Figure 18 is a schematic perspective view showing the lid being attached to the case. Figure 19 is a schematic perspective view showing the cover being placed on the case. Figure 20 is a schematic cross-sectional view showing the cover being placed on the case. Figure 21 is a schematic cross-sectional view showing the first workpiece supported by the backing member. Figure 22 is a schematic cross-sectional view illustrating a modified example of a supply channel formed inside the backing member. Figure 23 is a schematic cross-sectional view illustrating how the height of the first end of the first support column can be adjusted. Figure 24 is a schematic cross-sectional view illustrating how the height of the second end of the second support column can be adjusted.Figure 25 is a schematic perspective view showing a friction stir welding jig in a second modification of the first embodiment. Figure 26 is a schematic front view showing a part of the machine tool in the first embodiment. Figure 27 is a schematic front view showing a part of the machine tool in the first embodiment. Figure 28 is a schematic perspective view showing the machine tool in the first embodiment. Figure 29 is a schematic perspective view showing the machine tool in the first embodiment. Figure 30 is a schematic perspective view showing the cutting mode being executed. Figure 31 is a schematic diagram showing how the control device can control multiple control target devices. Figure 32 is a schematic front view showing a part of the machine tool in the first embodiment. Figure 33 is a schematic front view showing a part of the machine tool in the first embodiment. Figure 34 is a diagram for explaining the first path. Figure 35 is a schematic perspective view showing a friction stir welding jig in the second embodiment. Figure 36 is a schematic perspective view showing the first and second workpieces supported by a friction stir welding jig. Figure 37 is a schematic front view showing a part of a machine tool in the second embodiment. Figure 38 is a schematic cross-sectional view showing the welding mode being performed. Figure 39 is a schematic perspective view showing an example of the first workpiece. Figure 40 is a schematic perspective view showing the second and third workpieces positioned on the first workpiece. Figure 41 is a flowchart showing an example of a workpiece processing method in the embodiment. Figure 42 is a schematic cross-sectional view showing an example where a backing member contacts the first and second workpieces, respectively. 【0010】 The friction stir welding jig 4, machine tool 1, and workpiece processing method in the embodiment will be described below with reference to the drawings. In the following description of the embodiment, parts and components having the same function will be denoted by the same reference numeral, and repeated descriptions of parts and components denoted by the same reference numeral will be omitted. 【0011】(Definition of Terms) In this specification, the direction in which the object to be joined W (more specifically, the first workpiece W1 as the object to be joined) is pressed by the friction stir welding tool T1 is defined as the first direction DR1. The direction opposite to the first direction DR1 is defined as the second direction DR2. 【0012】 The first direction DR1 may be downward (more specifically, vertically downward) or lateral (more specifically, horizontal). For example, if machine tool 1 is a vertical machining center, the first direction DR1 is downward (more specifically, vertically downward). For example, if machine tool 1 is a horizontal machining center, the first direction DR1 is lateral (more specifically, horizontal). 【0013】(First Embodiment) The friction stir welding jig 4A and the machine tool 1A in the first embodiment will be described with reference to Figures 1 to 34. Figure 1 is a schematic perspective view showing the friction stir welding jig 4A in the first embodiment. Figure 2 is a schematic perspective view showing the state in which the first workpiece W1 is attached to the friction stir welding jig 4A. Figure 3 is a schematic perspective view showing the state in which the first workpiece W1 and the second workpiece W2 are supported by the friction stir welding jig 4A. Figure 4 is a schematic cross-sectional view showing the state in which the welding mode M1 is being executed. Figure 5 is a schematic diagram showing the machine tool 1A in the first embodiment. Figure 6 is a schematic perspective view showing the friction stir welding jig 4A in the first embodiment. Figure 7 is a schematic cross-sectional view showing the state in which the first workpiece W1 and the second workpiece W2 are supported by the friction stir welding jig 4A in a first modified example of the first embodiment. Figure 8 is a schematic perspective view showing the friction stir welding jig 4A in the first embodiment. Figures 9 and 10 are schematic cross-sectional views showing the welding mode M1 being executed. Figure 11 is a schematic perspective view showing the friction stir welding jig 4A in a second modification of the first embodiment. Figure 12 is a schematic perspective view showing the first workpiece W1 and the second workpiece W2 supported by the friction stir welding jig 4A in the second modification of the first embodiment. Figures 13 to 16 are schematic perspective views showing the welding mode M1 being executed. Figure 17 is a schematic perspective view showing an example of the first workpiece W1. Figure 18 is a schematic perspective view showing the lid CB being attached to the case 7. Figure 19 is a schematic perspective view showing the cover 8 being placed on the case 7. Figure 20 is a schematic cross-sectional view showing the cover 8 being placed on the case 7. Figure 21 is a schematic cross-sectional view showing the state in which the first workpiece W1 is supported by the backing member 40. Figure 22 is a schematic cross-sectional view showing a modified example of the supply channel 44 formed inside the backing member 40. Figure 23 is a schematic cross-sectional view showing how the height of the first end 42a-1 of the first support column 42-1 can be adjusted. Figure 24 is a schematic cross-sectional view showing how the height of the second end 42a-2 of the second support column 42-2 can be adjusted.Figure 25 is a schematic perspective view showing a friction stir welding jig 4A in a second modification of the first embodiment. Figures 26 and 27 are schematic front views showing a part of the machine tool 1A in the first embodiment. Figures 28 and 29 are schematic perspective views showing the machine tool 1A in the first embodiment. Figure 30 is a schematic perspective view showing the cutting mode M2 ​​being executed. Figure 31 is a schematic diagram showing how the control device 3 can control multiple control target devices. Figures 32 and 33 are schematic front views showing a part of the machine tool 1A in the first embodiment. Figure 34 is a diagram for explaining the first path PA. 【0014】 As illustrated in Figure 1, the friction stir welding jig 4A in the first embodiment comprises a backing member 40, a holding member 50, and at least one nozzle 61. 【0015】 The backing member 40 supports the object to be joined W (more specifically, the first workpiece W1 as the object to be joined). In the example shown in Figure 2, the backing member 40 is shown supporting the first workpiece W1 as the object to be joined. Figure 3 shows the second workpiece W2 placed on top of the first workpiece W1. 【0016】 As illustrated in Figure 4, the backing member 40 receives pressing force from the friction stir welding tool T1 via the object to be joined W (more specifically, the first workpiece W1 as the object to be joined). In other words, when the object to be joined W is frictionally stirred by the friction stir welding tool T1, the backing member 40 supports the object to be joined W (more specifically, the first workpiece W1 as the object to be joined) against the pressing force that the object to be joined W receives from the friction stir welding tool T1. 【0017】 As illustrated in Figures 2 and 3, the holding member 50 holds the object to be joined W (more specifically, the first workpiece W1 as the object to be joined). 【0018】As illustrated in Figure 4, at least one nozzle 61 is positioned on the backing member 40. At least one nozzle 61 discharges a coolant L1 toward the object to be joined W (more specifically, the first workpiece W1 as the object to be joined). 【0019】 The friction stir welding jig 4A in the first embodiment includes a backing member 40 that supports the first workpiece W1 as the object to be joined. The backing member 40 prevents the first workpiece W1 from bending due to the pressing force from the friction stir welding tool T1. 【0020】 The friction stir welding jig 4A in the first embodiment includes a holding member 50 for holding the first workpiece W1. The holding member 50 prevents the first workpiece W1 from shifting position during friction stir welding. 【0021】 In the friction stir welding jig 4A of the first embodiment, at least one nozzle 61 is arranged on the backing member 40. Therefore, when friction stir welding is performed, the first workpiece W1 is efficiently cooled by the coolant L1 released from at least one nozzle 61. Furthermore, since at least one nozzle 61 is arranged on the backing member 40 that supports the first workpiece W1, there is no need to provide a structure to support the at least one nozzle 61 separately from the backing member 40. In addition, compared to the case where the objects to be joined are cooled in a water tank (see Figure 6 of Patent Document 1), the preparation of the friction stir welding jig 4A is easier. Also, the preparation time before friction stirring is performed is shorter. 【0022】 In the example shown in Figure 4, since at least one nozzle 61 is positioned on the backing member 40, once the position of the first workpiece W1 relative to the friction stir welding jig 4A is determined (more specifically, once the first workpiece W1 is held by the holding member 50), the position of at least one nozzle 61 relative to the first workpiece W1 is determined. Therefore, setting the position of at least one nozzle 61 relative to the first workpiece W1 is easy. 【0023】As illustrated in Figure 5, the machine tool 1A in the first embodiment includes a friction stir welding jig 4A, a support device 11, a machining head 15, a rotary drive device 16, a moving device 17, and a supply device 12. 【0024】 A friction stir welding jig 4A has a workpiece W to be joined (more specifically, a first workpiece W1 as the workpiece to be joined) fixed to it. The friction stir welding jig 4A includes (1) a backing member 40 that receives pressing force from the friction stir welding tool T1 via the first workpiece W1 as the workpiece to be joined and supports the first workpiece W1, (2) a holding member 50 that holds the first workpiece W1, and (3) at least one nozzle 61 positioned on the backing member 40 that discharges a cooling liquid L1 toward the first workpiece. 【0025】 The support device 11 supports the friction stir welding jig 4A. The support device 11 may also include a table 111 on which the friction stir welding jig 4A is attached. 【0026】 The machining head 15 comprises a spindle 151 and a support 153 that rotatably supports the spindle 151 around a first axis AX1. The spindle 151 is capable of holding a friction stir welding tool T1. 【0027】 The rotary drive device 16 rotates the spindle 151 around the first axis AX1. The rotary drive device 16 may include a motor 16m that rotates the spindle 151 around the first axis AX1. In the example shown in Figure 5, the machining head 15 is equipped with the above-mentioned motor 16m. 【0028】 The moving device 17 moves the machining head 15 relative to the support device 11. The moving device 17 may include a machining head moving device 171 for moving the machining head 15. Alternatively or additionally, the moving device 17 may include a table moving device 178 for moving the table 111. 【0029】 The supply device 12 supplies coolant L1 to at least one nozzle 61. The at least one nozzle 61 discharges the coolant L1 toward the first workpiece W1 when the friction stir welding tool T1 frictionally stirs the first workpiece W1. 【0030】The machine tool 1A in the first embodiment provides the same effects as the friction stir welding jig 4A in the first embodiment. 【0031】 (Optional Additional Configurations) Next, with reference to Figures 1 to 34, optional additional configurations that can be adopted in the friction stir welding jig 4A and the machine tool 1A in the first embodiment will be described. 【0032】 (Nozzle 61) In the example shown in Figure 4, at least one nozzle 61 sprays coolant L1 toward the object to be joined W (more specifically, the first workpiece W1 as the object to be joined). 【0033】 In the example shown in Figure 4, at least one nozzle 61 includes a spray nozzle SN that diffuses the cooling liquid L1 toward the object to be joined W (more specifically, the first workpiece W1 as the object to be joined). When a spray nozzle SN is used, the first workpiece W1 can be cooled over a wide area. Therefore, the number of nozzles 61 required to cool the first workpiece W1 is reduced. In addition, it is not necessary to move at least one nozzle 61 in accordance with the position where frictional stirring occurs. 【0034】 As illustrated in Figure 6, the spray nozzle SN may be configured to diffuse the coolant L1 in a fan shape. Alternatively, the spray nozzle SN may be configured to diffuse the coolant L1 in a cone shape. 【0035】 In the example shown in Figure 1, the backing member 40 has a first support column 42-1. The backing member 40 may also have a second support column 42-2. 【0036】 In the example shown in Figure 4, at least one nozzle 61 includes a first nozzle 61a positioned on the backing member 40 (more specifically, the first support column 42-1). The first nozzle 61a may also be a first spray nozzle SN1 that diffuses the coolant L1 toward the object to be joined W (more specifically, the first workpiece W1 as the object to be joined). 【0037】In the example shown in Figure 1, at least one nozzle 61 includes a second nozzle 61b. The second nozzle 61b may be a second spray nozzle that diffuses the coolant L1 toward the object to be joined (more specifically, the first workpiece W1 as the object to be joined). 【0038】 In the example shown in Figure 1, the second nozzle 61b is located on the first support column 42-1. Alternatively, or additionally, the friction stir welding jig 4A may also include a nozzle 61d located on the second support column 42-2 (more specifically, on the side of the second support column 42-2) (see Figure 7). The nozzle 61d located on the second support column 42-2 discharges the coolant L1 toward the first workpiece W1. 【0039】 In the example shown in Figure 1, at least one nozzle 61 (for example, a spray nozzle SN) is attached to the side surface 43 of the backing member 40. 【0040】 The lateral region of the backing member 40 is usually dead space. If at least one nozzle 61 is attached to the side surface 43 of the backing member 40, at least one nozzle 61 can be placed in the aforementioned dead space. 【0041】 In the example shown in Figure 1, the friction stir welding jig 4A is positioned on the backing member 40 and includes at least two nozzles (61a, 61b) that discharge a coolant L1 toward the first workpiece W1. As illustrated in Figure 1, the friction stir welding jig 4A may also include a first nozzle 61a positioned on the first side surface of the backing member 40 (more specifically, the first side surface 43a of the first support column 42-1). The friction stir welding jig 4A may also include a second nozzle 61b positioned on the second side surface of the backing member 40 (more specifically, the second side surface 43b of the first support column 42-1). 【0042】As illustrated in FIG. 1, the friction stir welding jig 4A may be disposed on the backing member 40 and include at least three nozzles (61a, 61b, 61c) that discharge the coolant L1 toward the first workpiece W1. As illustrated in FIG. 1, the friction stir welding jig 4A may include a third nozzle 61c disposed on the third side surface of the backing member 40 (more specifically, the third side surface 43c of the first support column 42-1). In the example shown in FIG. 1, the third side surface 43c is the surface opposite to the second side surface 43b. 【0043】 In the example shown in FIG. 10, a supply flow path 44 for supplying the coolant L1 to at least one nozzle 61 is formed inside the backing member 40. 【0044】 Even when a cavity is provided in the backing member 40, the cavity is usually not utilized as a flow path. When the supply flow path 44 is formed inside the backing member 40, the internal region of the backing member is utilized as the supply flow path 44. Further, when the supply flow path 44 is formed inside the backing member 40, the side region of the backing member 40 is simplified. For example, instead of disposing a hose for supplying the coolant L1 in the side region of the backing member 40, the supply flow path 44 may be formed inside the backing member 40. 【0045】 As illustrated in FIG. 10, assume a case where heat generated by friction stir is transmitted from the first workpiece W1 to the backing member 40. In this case, when the coolant L1 flows through the supply flow path 44 inside the backing member 40, an increase in the temperature of the backing member 40 is suppressed. When an increase in the temperature of the backing member 40 is suppressed, an increase in the temperature of the region G of the first workpiece W1 that contacts the backing member 40 is also suppressed. 【0046】 (Coolant L1) The coolant L1 is, for example, a water-soluble coolant liquid. The main component of the water-soluble coolant liquid is, for example, water. The water-soluble coolant liquid may contain a water-soluble oil agent (for example, a water-soluble cutting oil agent or a water-soluble grinding oil agent) and / or a surfactant. 【0047】The coolant L1 may be a liquid having the same components as the cutting fluid applied to the workpiece (for example, the first workpiece W1 or other workpieces) when the workpiece (for example, the first workpiece W1 or other workpieces) is being machined. 【0048】 In the example shown in FIG. 10, the nozzle 61 discharges the coolant L1 from the backing member 40 to the first workpiece W1. Additionally, as illustrated in FIG. 11, the machine tool 1A may include a nozzle 62 that discharges the coolant to the first workpiece W1 from a member other than the backing member. 【0049】 In this specification, the plurality of nozzles arranged in the backing member 40 are defined as the first group of nozzles 61, and the plurality of nozzles arranged in members other than the backing member 40 are defined as the second group of nozzles 62. In the example shown in FIG. 11, the friction stir welding jig 4 includes the first group of nozzles 61 arranged in the backing member 40 and the second group of nozzles 62 arranged in a member other than the backing member 40 (for example, the base 64). 【0050】 As illustrated in FIG. 13, the second group of nozzles 62 discharges the coolant L1 to the outer surface of the first workpiece W1. The second group of nozzles 62 may discharge the coolant L1 to the outer side surface Wt of the first workpiece W1. Alternatively, or additionally, the second group of nozzles 62 may discharge the coolant L1 to the second workpiece W2. 【0051】 (The first workpiece W1 and the second workpiece W2) In the example shown in FIG. 3, the friction stir welding jig 4A supports the first workpiece W1 and the second workpiece W2 joined to the first workpiece W1 by friction stir welding. In the example shown in FIG. 9, the friction stir welding jig 4A supports the second workpiece W2 via the first workpiece W1. More specifically, the backing member 40 supports the first workpiece W1, and the first workpiece W1 supports the second workpiece W2. 【0052】 In the example shown in FIG. 9, the first workpiece W1 has an end wall 73 supported by the backing member 40. 【0053】In the example shown in Figure 9, the first workpiece W1, which is the object to be joined, is case 7. The first workpiece W1 (more specifically, case 7) is joined to the second workpiece W2 by friction stir. 【0054】 In the example shown in Figure 9, the second workpiece W2 is the cover 8. In the example shown in Figure 9, the case 7 is the first object to be joined, and the cover 8 is the second object to be joined. The first object to be joined (e.g., the case 7) and the second object to be joined (e.g., the cover 8) are joined by friction stir. 【0055】 In the example shown in Figure 17, the case 7 has a side wall 71 and an end wall 73. The case 7 also has a recess 74 defined by the side wall 71 and the end wall 73. In the example shown in Figure 17, the end wall 73 is a bottom wall 730 that defines the bottom of the recess 74. In the example shown in Figure 17, the side wall 71 and the end wall 73 are formed by integral molding. Alternatively, the end wall 73 may be attached to the side wall 71. In the example shown in Figure 17, the case 7 has a box shape. 【0056】 In the example shown in Figure 17, the side wall 71 includes a first side wall 71-1 and a second side wall 71-2. The second side wall 71-2 is positioned opposite the first side wall 71-1. 【0057】 The side wall 71 may include a first side wall 71-1, a second side wall 71-2, a third side wall 71-3, and a fourth side wall 71-4. In the example shown in Figure 17, the third side wall 71-3 connects the first side wall 71-1 and the second side wall 71-2. In the example shown in Figure 17, the fourth side wall 71-4 connects the first side wall 71-1 and the second side wall 71-2. The fourth side wall 71-4 is positioned opposite the third side wall 71-3. 【0058】 The side wall 71 may have a projection (for example, a flange 72) held by the retaining member 50. In the example shown in Figure 9, the first side wall 71-1 has a first protruding edge 72-1 held by the first retaining member 51a. The second side wall 71-2 has a second protruding edge 72-2 held by the second retaining member 51b. In the example shown in Figure 17, each of the first protruding edge 72-1 and the second protruding edge 72-2 constitutes a part of the flange 72. 【0059】 In the example shown in Figure 9, the first direction DR1 coincides with the direction from the end wall 73 toward the internal space SP of the recess 74. 【0060】 In the example shown in Figure 9, the end wall 73 is a wall located at the end of the side wall 71 on the second direction DR2 side. In the example shown in Figure 9, the end wall 73 is connected to the end of the first side wall 71-1 on the second direction DR2 side, and also connected to the end of the second side wall 71-2 on the second direction DR2 side. 【0061】 In the example shown in Figure 17, the case 7 has a recess 74 capable of receiving an object to be cooled. The object to be cooled received in the recess 74 is, for example, an electrical device that generates heat when an electric current flows through it. The case 7 may also be an automotive part (for example, an electric vehicle part) that is mounted in an automobile with the electrical device housed inside. The electrical device that generates heat when an electric current flows through it is housed in the recess 74, for example, in contact with the end wall 73. 【0062】 The object to be cooled (more specifically, electrical equipment) received in the recess 74 is, for example, an inverter (more specifically, a device having a circuit that converts direct current to alternating current), a converter (more specifically, an AC-DC converter that converts alternating current to direct current, or a DC-DC converter that converts a direct current voltage to another direct current voltage), a battery, a charger for charging a battery, a control unit such as an engine control unit, or a circuit board on which multiple electronic components are arranged. 【0063】 Case 7 is, for example, a cast part. The side wall 71, end wall 73, and recess 74 may be formed by casting. Alternatively, the side wall 71, end wall 73, and recess 74 may be formed by cutting the block with a cutting tool. 【0064】 The case 7 may have a mounting portion 75 to which a cover CB (see Figure 18) that covers the recess 74 can be attached. In the example shown in Figure 17, the mounting portion 75 has a hole 75h into which a bolt is inserted. The mounting portion 75 may be formed by casting. The outer shape of the mounting portion 75 may be formed by casting, and the hole 75h of the mounting portion 75 may be formed by machining (more specifically, drilling). 【0065】 As illustrated in Figure 18, the lid CB is fixed to the case 7 after the object to be cooled is placed in the recess 74. The lid may be fixed to the case 7 by inserting bolts into the holes 75h (see Figure 17). Alternatively, the lid may be fixed to the case 7 by friction stir welding. 【0066】 As illustrated in Figure 19, case 7 may have a groove 73v formed on the outer surface 73t of the end wall 73. In the examples shown in Figures 17 and 19, the groove 73v is located on the opposite side of the recess 74 with respect to the end wall 73. More specifically, the groove 73v is formed on the outer surface 73t of the end wall 73, and the inner surface 73n of the end wall 73 defines the bottom surface of the recess 74. 【0067】 The groove 73v of the end wall 73 may be formed by casting. Alternatively, the groove 73v may be formed by cutting the end wall 73 with a cutting tool. As illustrated in Figure 19, the groove 73v may be subdivided by at least one projection 73p. 【0068】 Case 7 may include a first port 79a connected to the groove 73v. Case 7 may also include a first port 79a connected to the groove 73v and a second port 79b connected to the groove 73v. If there is a possibility that coolant L1 may enter the groove 73v from the first port 79a, the first port 79a may be covered with a lid during friction stir welding. If there is a possibility that coolant L1 may enter the groove 73v from the second port 79b, the second port 79b may be covered with a lid during friction stir welding. 【0069】 Case 7 is, for example, made of metal. The main component of the material of Case 7 is, for example, aluminum. In other words, Case 7 is made of aluminum or an aluminum alloy. 【0070】 In the example shown in Figure 19, the cover 8 covers at least a portion of the outer surface 73t of the end wall 73 of the case 7. In the example shown in Figure 19, the cover 8 covers the groove 73v of the end wall 73. 【0071】In the example shown in Figure 19, the cover 8 has a flat shape. Alternatively, the cover 8 may have a recess or a protrusion. 【0072】 Cover 8 is, for example, made of metal. The main component of the material of cover 8 is, for example, aluminum. In other words, cover 8 is made of aluminum or an aluminum alloy. 【0073】 As illustrated in Figure 20, the end wall 73 of the case 7 may have a stepped portion 731 that is positioned opposite the outer edge 81 of the cover 8. In this case, the stepped portion 731 of the end wall 73 and the outer edge 81 of the cover 8 may be configured to butt-join by friction stirring. 【0074】 In the example shown in Figure 20, the case 7 is supported by the backing member 40 when the case 7 is inverted. Some of the multiple support columns 42 may support the end wall 73 of the case 7 near the side wall 71. 【0075】 (Backing member 40) In the example shown in Figure 9, the backing member 40 has a first support column 42-1 that supports the object to be joined W (more specifically, the first workpiece W1 as the object to be joined). The backing member 40 may have a plurality of support columns 42, including the first support column 42-1 and the second support column 42-2. Each of the plurality of support columns 42 receives a pressing force from the friction stir welding tool T1 via the object to be joined (more specifically, the first workpiece W1 as the object to be joined). In other words, when the first workpiece W1 is frictionally stirred by the friction stir welding tool T1, each of the plurality of support columns 42 supports the first workpiece W1 against the pressing force that the first workpiece W1 receives from the friction stir welding tool T1. 【0076】 In the example shown in Figure 8, the number of support columns 42 on the backing member 40 is nine. Alternatively, the number of support columns 42 on the backing member 40 may be one, two, three, four, five, six, seven, eight, or ten or more. In the example shown in Figure 8, when viewed in the direction along the first direction DR1 (more specifically, in a plan view), the first support column 42-1 is surrounded by multiple other support columns 42. 【0077】In the example shown in Figure 9, the backing member 40 has a first support 42-1 and a second support 42-2. In the example shown in Figure 9, the first support 42-1 extends along the second direction DR2, and the second support 42-2 extends along the second direction DR2. In the example shown in Figure 1, the backing member 40 has a third support 42-3 and a fourth support 42-4. In the example shown in Figure 1, the third support 42-3 extends along the second direction DR2, and the fourth support 42-4 extends along the second direction DR2. In the example shown in Figure 1, the backing member 40 has a fifth support 42-5 and a sixth support 42-6. In the example shown in Figure 1, the fifth support 42-5 extends along the second direction DR2, and the sixth support 42-6 extends along the second direction DR2. 【0078】 In the example shown in Figure 21, the first support column 42-1 has a first end 42a-1 that contacts the first workpiece W1 (for example, the inner surface 73n of the end wall 73). In the example shown in Figure 21, the second support column 42-2 has a second end 42a-2 that contacts the first workpiece W1 (for example, the inner surface 73n of the end wall 73). 【0079】 In the example shown in Figure 21, the position of the first end 42a-1 is different from the position of the second end 42a-2 in the direction along the first direction DR1. More specifically, the second end 42a-2 is located closer to the first direction DR1 (more specifically, lower) than the first end 42a-1. In the example shown in Figure 21, the first direction DR1 is downward. In the example shown in Figure 21, the height of the second end 42a-2 is lower than the height of the first end 42a-1. 【0080】 When the position of the first end 42a-1 differs from the position of the second end 42a-2 in the direction along the first direction DR1 (more specifically, when the height of the first end 42a-1 differs from the height of the second end 42a-2), the multiple support columns 42, including the first support column 42-1 and the second support column 42-2, can suitably support the first workpiece W1 having a relatively complex shape. 【0081】In the example shown in Figure 21, a first supply channel 44-1 for supplying coolant L1 to the first nozzle 61a is formed inside the first support column 42-1. As illustrated in Figure 21, a second supply channel 44-2 for supplying coolant L1 to the second nozzle 61b (see Figure 8) may be formed inside the first support column 42-1. As illustrated in Figure 7, a third supply channel 44-3 for supplying coolant L1 to other nozzles 61d may be formed inside the second support column 42-2. 【0082】 As illustrated in Figure 22, a portion of the first supply channel 44-1 that supplies coolant L1 to the first nozzle 61a and a portion of the second supply channel 44-2 that supplies coolant L1 to the second nozzle 61b may be shared. 【0083】 In the example shown in Figure 21, the friction stir welding jig 4A includes a base 64 that supports the backing member 40. In the example shown in Figure 21, the base 64 supports a plurality of support columns 42, including a first support column 42-1 and a second support column 42-2. The base 64 can be attached to the support device 11 of the machine tool 1A. The base 64 can also be removed from the support device 11 of the machine tool 1A. 【0084】 In the example shown in Figure 21, the backing member 40 has a support end 40e that contacts the first workpiece W1 (for example, the inner surface of the case 7). In the example shown in Figure 23, the relative position of the support end 40e with respect to the base 64 is adjustable in a first direction DR1. It is also adjustable in a second direction DR2. When the relative position of the support end 40e with respect to the base 64 is adjustable in both the first and second directions DR1 and DR2, the position of the support end 40e can be finely adjusted to accommodate manufacturing tolerances of the first workpiece W1. Alternatively, the relative position of the support end 40e with respect to the base 64 may be adjusted when the object supported by the friction stir welding jig 4A is switched from the first workpiece W1 to another workpiece that differs in shape from the first workpiece W1. In other words, the relative position of the support end 40e with respect to the base 64 may be adjustable so that the backing member 40 can be used for multiple types of workpieces. 【0085】In the example shown in Figure 23, the relative position of the first end 42a-1 of the first support column 42-1 with respect to the base 64 can be adjusted in the first direction DR1 (and the second direction DR2). In the example shown in Figure 24, the relative position of the second end 42a-2 of the second support column 42-2 with respect to the base 64 can be adjusted in the first direction DR1 (and the second direction DR2). 【0086】 As illustrated in Figure 23, the first support column 42-1 may be extendable or retractable. More specifically, the first support column 42-1 may include a first portion 421-1 fixed to the base 64 and a second portion 421-2 that is relatively movable relative to the first portion 421-1 in a second direction DR2 (for example, upward). In the example shown in Figure 23, the first end 42a-1 described above is located on the second portion 421-2. The first nozzle 61a described above is also located on the second portion 421-2. 【0087】 When the first support column 42-1 extends, the position of the first end 42a-1 of the first support column 42-1 is adjusted to move away from the base 64 (in other words, in the second direction DR2). When the first support column 42-1 retracts, the position of the first end 42a-1 of the first support column 42-1 is adjusted to move closer to the base 64 (in other words, in the first direction DR1). 【0088】 The first support column 42-1 may include a first spring 64-1 that biases the second portion 421-2 in a second direction DR2 (e.g., upward). Alternatively, or additionally, the first support column 42-1 may include a fluid pressure cylinder (e.g., an air cylinder or a hydraulic cylinder) that moves the second portion 421-2 in the second direction DR2 (e.g., upward). 【0089】 In the example shown in Figure 23, when the second portion 421-2 is pressed by the first workpiece W1 (for example, case 7), the first spring 64-1 compresses. As a result, the height of the second portion 421-2 is automatically adjusted to correspond to the shape of the first workpiece W1 or to any manufacturing tolerances of the first workpiece W1. 【0090】As illustrated in Figure 22, the first support column 42-1 may include a first fixing member 65-1 for fixing the relative position of the second portion 421-2 with respect to the first portion 421-1. In this case, after the height of the second portion 421-2 has been adjusted, the height of the second portion 421-2 can be fixed using the first fixing member 65-1. 【0091】 In the example shown in Figure 9, when the first workpiece W1 is held by the holding member 50, the first fixing member 65-1 is positioned on the first direction DR1 side of the first workpiece W1. In this case, the operator can easily access the first fixing member 65-1 while the first workpiece W1 is held by the holding member 50. In the example shown in Figure 9, the first fixing member 65-1 is positioned between the lower base 641 and the upper base 646 in the direction along the first direction DR1. 【0092】 As illustrated in Figure 24, the second support column 42-2 may be extendable or retractable. More specifically, the second support column 42-2 may include a third portion 421-3 fixed to the base 64 and a fourth portion 421-4 that is relatively movable relative to the third portion 421-3 in a second direction DR2 (e.g., upward). In the example shown in Figure 24, the second end 42a-2 described above is located on the fourth portion 421-4. 【0093】 When the second support column 42-2 extends, the position of the second end 42a-2 of the second support column 42-2 is adjusted to move away from the base 64 (in other words, in the second direction DR2). When the second support column 42-2 retracts, the position of the second end 42a-2 of the second support column 42-2 is adjusted to move closer to the base 64 (in other words, in the first direction DR1). 【0094】 The second support column 42-2 may include a second spring 64-2 that biases the fourth portion 421-4 in a second direction DR2 (e.g., upward). Alternatively, or additionally, the second support column 42-2 may include a fluid pressure cylinder (e.g., an air cylinder or a hydraulic cylinder) that moves the fourth portion 421-4 in the second direction DR2 (e.g., upward). 【0095】As illustrated in Figure 22, the second support column 42-2 may include a second fixing member 65-2 for fixing the relative position of the fourth portion 421-4 with respect to the third portion 421-3. In this case, after the height of the fourth portion 421-4 has been adjusted, the height of the fourth portion 421-4 can be fixed using the second fixing member 65-2. 【0096】 In the example shown in Figure 9, when the first workpiece W1 is held by the holding member 50, the second fixing member 65-2 is positioned on the first direction DR1 side of the first workpiece W1. In this case, the operator can easily access the second fixing member 65-2 while the first workpiece W1 is held by the holding member 50. In the example shown in Figure 9, the second fixing member 65-2 is positioned between the lower base 641 and the upper base 646 in the direction along the first direction DR1. 【0097】 If the multiple support columns 42 include a third support column 42-3 and a fourth support column 42-4, each of the third support column 42-3 and the fourth support column 42-4 may be retractable. If the multiple support columns 42 include a fifth support column 42-5 and a sixth support column 42-6, each of the fifth support column 42-5 and the sixth support column 42-6 may be retractable. 【0098】 In the example shown in Figure 4, the backing member 40 supports the end wall of the first workpiece W1 (for example, the end wall 73 of the case 7). In the example shown in Figure 4, the end wall of the first workpiece W1 can be frictionally stirred while it is supported by the backing member 40. More specifically, the end wall 73 of the case 7 and the cover 8 can be frictionally stirred while the end wall 73 of the case 7 is supported by the backing member 40. 【0099】 (Base 64) In the example shown in Figure 25, the base 64 includes a lower base 641 and an upper base 646. The base 64 also includes a plurality of connecting posts 647 that connect the lower base 641 and the upper base 646. In the example shown in Figure 25, the lower base 641 is positioned on the first direction DR1 side of the upper base 646. The upper base 646 may have a through hole 646h (see Figure 8) through which the backing member 40 passes. 【0100】 In the example shown in Figure 25, the lower base 641 supports the backing member 40. In the example shown in Figure 25, the retaining member 50 is positioned on the upper base 646. 【0101】 In the example shown in Figure 26, the base 64 (more specifically, the lower base 641) is attached to the support device 11 (more specifically, the table 111). In the example shown in Figure 26, the machine tool 1A includes a fixing member F for fixing the base 64 (more specifically, the lower base 641) to the support device 11 (more specifically, the table 111). The fixing member F is, for example, a bolt F1. In the example shown in Figure 25, the base 64 (more specifically, the lower base 641) includes a mounting hole 64h. The base 64 may be fixed to the table 111 by a bolt F1 inserted into the mounting hole 64h. 【0102】 As illustrated in Figure 25, the second group of nozzles 62 may be supported on the base 64 (more specifically, the upper base 646). 【0103】 (Holding member 50) In the example shown in Figure 4, the holding member 50 holds the side wall of the first workpiece W1 (for example, the side wall 71 of the case 7). In the example shown in Figure 4, with the side wall 71 of the first workpiece W1 held by the holding member 50, the end wall 73 of the first workpiece W1 can be frictionally stirred. More specifically, with the side wall 71 of the case 7 held by the holding member 50, the end wall 73 of the case 7 and the cover 8 can be frictionally stirred. 【0104】 In the example shown in Figure 9, the holding member 50 includes a first holding member 51a that holds a first portion of the first workpiece W1 (more specifically, the first side wall 71-1 of the case 7) and a second holding member 51b that holds a second portion of the first workpiece W1 (more specifically, the second side wall 71-2 of the case 7). 【0105】 In the example shown in Figure 9, the backing member 40 is positioned to cross the space SP1 between the first retaining member 51a and the second retaining member 51b. 【0106】In the example shown in Figure 9, the support end 40e of the backing member 40 is located on the second direction DR2 side (more specifically, above) the retaining member 50. More specifically, the first end 42a-1 of the first support column 42-1 is located on the second direction DR2 side (more specifically, above) the first retaining member 51a and the second retaining member 51b. Also, the second end 42a-2 of the second support column 42-2 is located on the second direction DR2 side (more specifically, above) the first retaining member 51a and the second retaining member 51b. 【0107】 In the example shown in Figure 9, the first retaining member 51a has a first movable portion 513a that is repositionable relative to the first fixed portion 511a (for example, a portion of the upper base 646). As the first movable portion 513a moves toward the first fixed portion 511a, the first portion of the first workpiece W1 (more specifically, the first side wall 71-1 of the case 7) is held between the first fixed portion 511a and the first movable portion 513a. The first movable portion 513a may be screwed onto a first threaded member SB1. In this case, the first movable portion 513a moves toward the first fixed portion 511a as the first threaded member SB1 rotates relative to the first movable portion 513a. Alternatively, the first retaining member 51a may include a fluid pressure cylinder (for example, an air cylinder or a hydraulic cylinder) that moves the first movable portion 513a toward the first fixed portion 511a. 【0108】 In the example shown in Figure 9, the second retaining member 51b has a second movable portion 513b that is repositionable relative to the second fixed portion 511b (for example, another portion of the upper base 646). As the second movable portion 513b moves toward the second fixed portion 511b, the second portion of the first workpiece W1 (more specifically, the second side wall 71-2 of the case 7) is clamped between the second fixed portion 511b and the second movable portion 513b. The second movable portion 513b may be screwed onto a second threaded member SB2. In this case, the second movable portion 513b moves toward the second fixed portion 511b as the second threaded member SB2 rotates relative to the second movable portion 513b. Alternatively, the second retaining member 51b may include a fluid pressure cylinder (for example, an air cylinder or a hydraulic cylinder) that moves the second movable portion 513b toward the second fixed portion 511b. 【0109】 In the example shown in Figure 8, the friction stir welding jig 4A is equipped with four or more holding members 50 arranged around the backing member 40 to hold the first workpiece W1. More specifically, ten holding members 50 are arranged around the backing member 40 to hold the first workpiece W1. The number of holding members 50 arranged around the backing member 40 may be four, five, six, seven, eight, nine, or eleven or more. 【0110】 In the example shown in Figure 8, the retaining members 50 (for example, the first retaining member 51a and the second retaining member 51b) are supported by the base 64 (more specifically, the upper base 646). 【0111】 (Anti-detachment member 67) In the example shown in Figure 13, the friction stir welding jig 4A includes an anti-detachment member 67 that prevents the second workpiece W2 (e.g., cover 8) from detaching from the first workpiece W1 (e.g., case 7). In the examples shown in Figures 12 and 13, the anti-detachment member 67 is repositionable between an extended position P1 that contacts the second workpiece W2 (e.g., cover 8) and a retracted position P2 that moves away from the second workpiece W2 (e.g., cover 8). 【0112】 The friction stir welding jig 4A may include an actuator 68 that moves the anti-detachment member 67 between the aforementioned extended position P1 and the aforementioned retracted position P2. The actuator 68 may move the anti-detachment member 67 from the aforementioned extended position P1 to the aforementioned retracted position P2 in response to receiving a first operation command from the control device 3. The actuator 68 may also move the anti-detachment member 67 from the aforementioned retracted position P2 to the aforementioned extended position P1 in response to receiving a second operation command from the control device 3. 【0113】As illustrated in Figure 12, the detachment prevention member 67 may include a first detachment prevention member 67-1 and a second detachment prevention member 67-2. The friction stir welding jig 4A may also include a first actuator 68-1 that moves the first detachment prevention member 67-1 between a first advanced position P1-1 that contacts the second workpiece W2 (e.g., cover 8) and a first retracted position P2-1 that moves away from the second workpiece W2 (e.g., cover 8). The friction stir welding jig 4A may also include a second actuator 68-2 that moves the second detachment prevention member 67-2 between a second advanced position P1-2 that contacts the second workpiece W2 (e.g., cover 8) and a second retracted position P2-2 that moves away from the second workpiece W2 (e.g., cover 8). 【0114】 In the example shown in Figure 12, the anti-detachment members 67 (for example, the first anti-detachment member 67-1 and the second anti-detachment member 67-2) are supported by the base 64 (more specifically, the upper base 646). 【0115】 (Machine tool 1A) In the example shown in Figure 26, machine tool 1A includes a friction stir welding jig 4A to which the object to be joined W (more specifically, the first workpiece W1 as the object to be joined) is fixed, a support device 11, a machining head 15, a rotary drive device 16, a moving device 17, and a supply device 12 (not shown in Figure 26). Since the friction stir welding jig 4A has already been described, a repeated explanation of the friction stir welding jig 4A will be omitted. 【0116】 The support device 11 supports the friction stir welding jig 4A. The support device 11 may also include a table 111 on which the friction stir welding jig 4A is attached. 【0117】 The machining head 15 comprises a spindle 151 and a support 153 that rotatably supports the spindle 151 around a first axis AX1. The spindle 151 is capable of holding a friction stir welding tool T1. 【0118】The rotary drive device 16 rotates the spindle 151 around the first axis AX1. The rotary drive device 16 may include a motor 16m that rotates the spindle 151 around the first axis AX1. In the example shown in Figure 26, the machining head 15 is equipped with the above-mentioned motor 16m. 【0119】 The moving device 17 moves the machining head 15 relative to the support device 11. The moving device 17 may include a machining head moving device 171 that moves the machining head 15. In the example shown in Figures 26 and 27, the machining head moving device 171 can move the machining head 15 in a direction substantially parallel to the vertical (Z direction). The machining head moving device 171 may also move the machining head 15 in a direction substantially parallel to the horizontal plane. 【0120】 The moving device 17 may include a table moving device 178 for moving the table 111. In the example shown in Figures 26 and 27, the table moving device 178 can move the table 111 in a direction substantially parallel to the horizontal plane. In the example shown in Figures 26 and 27, the table moving device 178 includes an X-axis moving device 178a for moving the table 111 in a direction along the X-axis substantially parallel to the horizontal plane. The table moving device 178 may include a Y-axis moving device 178b for moving the table 111 in a direction along the Y-axis perpendicular to both the vertical and the X-axis. 【0121】 A supply device 12 (not shown in Figure 26) supplies coolant L1 to at least one nozzle 61. At least one nozzle 61 discharges the coolant L1 toward the first workpiece W1 when the friction stir welding tool T1 frictionally stirs the first workpiece W1. 【0122】 (Wall 21 and Door 23) As illustrated in Figures 28 and 29, the machine tool 1A may include a wall 21 surrounding the machining area RG1 where friction stirring is performed. The wall 21 prevents the coolant L1 from splashing outside the machining area RG1 where friction stirring is performed. The wall 21 surrounds the friction stir joining jig 4. The wall 21 also surrounds the lower end portion 15g of the machining head 15 (see Figure 26). In the example shown in Figures 28 and 29, the wall 21 surrounds the table 111. 【0123】 As illustrated in Figures 28 and 29, the wall 21 may have an opening OP through which a first workpiece W1 (e.g., a case 7) and a second workpiece W2 (e.g., a cover 8) can pass. In the example shown in Figures 28 and 29, the machine tool 1A includes a door 23 that opens and closes the opening OP formed in the wall 21. The wall 21 and the door 23 surround the machining area RG1 and prevent the coolant L1 from splashing outside the machining area RG1. 【0124】 (Supplying device 12) In the example shown in Figure 29, the machine tool 1A includes a supplying device 12 that supplies coolant L1 to at least one nozzle 61. The supplying device 12 supplies coolant L1 to a first group of nozzles 61 located on the backing member 40. The supplying device 12 may also supply coolant L1 to a second group of nozzles 62 located on a member other than the backing member 40 (for example, the upper base 646). 【0125】 In the example shown in Figure 29, the supply device 12 includes a pump 121 that supplies the coolant L1 to at least one nozzle 61. The supply device 12 may also include a valve 123 positioned between at least one nozzle 61 and the pump 121. 【0126】 (Circulation of coolant L1) As illustrated in Figure 29, the machine tool 1A may be equipped with a circulation channel 13 for circulating the coolant L1 and a tank 141 for storing the coolant L1. 【0127】 The circulation channel 13 includes a channel 131 that supplies coolant L1 from the tank 141 to at least one nozzle 61. 【0128】 The circulation channel 13 includes a return channel 138 that returns the coolant L1 in the processing area RG1 where the friction agitation described above takes place back to the tank 141. When the processing area RG1 is surrounded by a wall 21, the coolant L1 can be recovered smoothly. 【0129】(Chiller 143) The machine tool 1A may be equipped with a chiller 143 for lowering the temperature of the coolant L1. In the example shown in Figure 29, the chiller 143 receives the coolant L1 from the tank 141 and lowers the temperature of the received coolant L1. The cooled coolant L1 is returned to the tank 141. 【0130】 (Cutting tool T2) As illustrated in Figure 30, the machine tool 1A may be capable of cutting at least one of the first workpiece W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8) using a cutting tool T2. More specifically, the spindle 151 may be capable of holding the cutting tool T2. 【0131】 For example, if burrs are generated from at least one of the first workpiece W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8) by the friction stir welding tool T1, these burrs may be removed using a cutting tool T2 (e.g., milling tool T2-1). 【0132】 The cutting tool T2 attached to the spindle 151 may be a drilling tool T2-2 (see Figure 26). After the first workpiece W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8) are friction stir-welded, holes may be formed in the first workpiece W1 (e.g., case 7) and / or the second workpiece W2 (e.g., cover 8) using the cutting tool T2 (e.g., drilling tool T2-2). For example, the hole 75h of the mounting portion 75 (see Figure 17) may be formed using the drilling tool T2-2. 【0133】 The cutting tool T2 attached to the spindle 151 may be a tap tool. After the first workpiece W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8) are friction stir-welded, a screw thread may be formed in the hole (e.g., the hole formed in the first workpiece W1) using the cutting tool T2 (e.g., a tap tool). 【0134】 After the first workpiece W1 (for example, case 7) and the second workpiece W2 (for example, cover 8) are friction stir-welded, the side wall 71 of case 7 or the inner surface of case 7 may be cut using a cutting tool T2. 【0135】 In the first embodiment, friction stirring is performed while the cooling liquid L1 is applied to the first workpiece W1. Therefore, distortion of the first workpiece W1 due to the heat generated by friction stirring is suppressed. As a result, the machine tool 1A can cut at least one of the first workpiece W1 and the second workpiece W2 with high precision following the friction stir welding of the first workpiece W1 and the second workpiece W2. 【0136】 (Tool changing device 19) As illustrated in Figures 26 and 27, the machine tool 1A may be equipped with a tool changing device 19. The tool changing device 19 can change the friction stir welding tool T1 held on the spindle 151 to a cutting tool T2 (for example, a milling tool T2-1, a drilling tool T2-2, a tapping tool, etc.). 【0137】 In the example shown in Figure 27, the tool changing device 19 includes a tool changing arm 191, an arm rotating device 194 for rotating the tool changing arm 191, and an arm moving device 196 for moving the tool changing arm 191 linearly. The arm rotating device 194 rotates the tool changing arm 191 around the second axis AX2. The arm moving device 196 moves the tool changing arm 191 in a direction parallel to the second axis AX2. 【0138】 In the example shown in Figure 27, the tool exchange arm 191 is capable of simultaneously gripping the friction stir welding tool T1 and the cutting tool T2. In the example shown in Figure 27, the tool exchange arm 191 has a first gripping portion 191a for gripping the friction stir welding tool T1 and a second gripping portion 191b for gripping the cutting tool T2. 【0139】 Alternatively, tool changes may be performed manually. Furthermore, if machine tool 1A is a machine capable of performing friction stirring only, tool changes are omitted. 【0140】(Control device 3) As illustrated in Figure 26, the machine tool 1A may include a control device 3 that controls the rotary drive device 16 and the moving device 17. Additionally, the control device 3 may control the supply device 12. Alternatively, or additionally, the control device 3 may control the tool changer 19. Alternatively, or additionally, the control device 3 may control the actuator 68 (more specifically, the first actuator 68-1 and the second actuator 68-2, etc.) that moves the anti-detachment member 67. 【0141】 In the example shown in Figure 31, the control device 3 comprises a hardware processor 30 (hereinafter simply referred to as "processor 30"), a memory 32, a communication circuit 34, an input device 36, and a display 37. The processor 30, the memory 32, the communication circuit 34, the input device 36, and the display 37 are connected to each other via a bus 38. In the example shown in Figure 31, the input device 36 includes a touch panel 36t on the display 37. In other words, the display 37 is a display with a touch panel 36t. The input device 36 may include buttons, switches, levers, pointing devices, and / or a keyboard. 【0142】 The memory 32 is a storage medium readable by the processor 30 of the control device 3. The memory 32 may be, for example, a non-volatile or volatile semiconductor memory such as RAM, ROM, or flash memory, or it may be a magnetic disk or other type of memory. 【0143】Memory 32 stores data DA and machining program PM. The processor 30 of the control device 3 executes the machining program PM stored in memory 32, thereby generating control commands. The communication circuit 34 then transmits these control commands to the controlled equipment (more specifically, the rotary drive device 16, the moving device 17, the supply device 12, the tool changer 19, the actuator 68, etc.). In this way, by the processor 30 executing the machining program PM, the control device 3 can control the controlled equipment (more specifically, the rotary drive device 16, the moving device 17, the supply device 12, the tool changer 19, the actuator 68, etc.). 【0144】 (Joining Mode M1) As illustrated in Figure 32, the control device 3 is capable of executing joining mode M1. Joining mode M1 is a mode in which a first workpiece W1 and a second workpiece W2 are friction stir joined using a friction stir joining tool T1. More specifically, joining mode M1 is a mode in which the rotating friction stir joining tool T1 is moved relative to the first workpiece W1 and the second workpiece W2 so that the first workpiece W1 and the second workpiece W2 are friction stir joined. The first workpiece W1 is, for example, the case 7 described above, and the second workpiece W2 is, for example, the cover 8 described above. 【0145】 When the joining mode M1 is executed, the control device 3 transmits a first rotation command R1 to the rotary drive device 16. Upon receiving the first rotation command R1, the rotary drive device 16 rotates the spindle 151 that holds the friction stir welding tool T1 around the first axis AX1. 【0146】 When the joining mode M1 is executed, the control device 3 transmits a first movement command S1 to the moving device 17. Upon receiving the first movement command S1, the moving device 17 moves the rotating friction stir welding tool T1 relative to the first workpiece W1 and the second workpiece W2 along the first path PA (see Figure 34) specified by the machining program PM. 【0147】The first path PA may include the boundary PA1 between the first workpiece W1 and the second workpiece W2. In this case, the first workpiece W1 and the second workpiece W2 are butt-joined by friction stir. More specifically, the first path PA may include the boundary PA1-1 between the stepped portion 731 of the case 7 (see Figure 20) and the outer edge portion 81 of the cover 8 (see Figure 20). In this case, the stepped portion 731 of the case 7 and the outer edge portion 81 of the cover 8 are butt-joined by friction stir. 【0148】 As can be seen from Figures 19 and 34, the first path PA may include a path PA2 along the region where the first workpiece W1 and the second workpiece W2 are overlapped. In this case, the first workpiece W1 and the second workpiece W2 are joined by friction stir. If the first workpiece W1 is case 7 and the second workpiece W2 is cover 8, the case 7 and cover 8 are joined by friction stir. In the example shown in Figure 34, the first path PA includes a path PA2-1 passing through the central portion 83 of cover 8. In this case, case 7 and the central portion 83 of cover 8 are joined by friction stir. 【0149】 In the example shown in Figure 10, at least one of the multiple support columns 42 (for example, the first support column 42-1) is located vertically below the central portion 83 of the cover 8. More specifically, when the case 7 and the central portion 83 of the cover 8 are joined together, at least one of the multiple support columns 42 supports the end wall 73 of the case 7 vertically below the friction stir welding tool T1. 【0150】 In the example shown in Figure 34, the first path PA includes both the boundary PA1 between the first workpiece W1 and the second workpiece W2, and the path PA2-1 passing through the central portion 83 of the second workpiece W2. In this case, the first workpiece W1 and the second workpiece W2 are butt-joined by friction stir, and the central portion 83 of the first workpiece W1 and the second workpiece W2 are overlap-joined by friction stir. 【0151】As illustrated in Figure 10, joining mode M1 may include friction stir joining of the case 7 and the cover 8 such that a flow path 91 (for example, a refrigerant flow path through which refrigerant flows) is formed by the groove 73v formed in the end wall 73 of the case 7 and the cover 8. 【0152】 During the execution of bonding mode M1, at least one nozzle 61 (e.g., a first nozzle 61a and / or a second nozzle 61b) applies coolant L1 to the first workpiece W1 (e.g., the end wall 73 of the first workpiece W1). More specifically, at least one nozzle 61 (e.g., a first nozzle 61a and / or a second nozzle 61b) sprays coolant L1 onto the first workpiece W1 (e.g., the end wall 73 of the first workpiece W1). 【0153】 During the execution of bonding mode M1, at least one nozzle 61 may be configured to discharge the coolant L1 so that it reaches substantially the entire inner surface 73n of the end wall 73, excluding the portion of the inner surface 73n of the end wall 73 that is in contact with the backing member 40. As illustrated in Figure 13, during the execution of bonding mode M1, the second group of nozzles 62 may discharge the coolant L1 onto the outer surface of the first workpiece W1. 【0154】 As illustrated in Figure 32, when the bonding mode M1 is executed, the control device 3 may transmit a supply command U1 to the supply device 12. The supply device 12 (e.g., a pump 121 and / or a valve 123) that receives the supply command U1 supplies coolant L1 to at least one nozzle 61 (e.g., a first nozzle 61a and / or a second nozzle 61b). The at least one nozzle 61 (e.g., a first nozzle 61a and / or a second nozzle 61b) discharges the coolant L1 supplied by the supply device 12 onto the first workpiece W1 (e.g., the inner surface 73n of the end wall 73 of the first workpiece W1). 【0155】 Alternatively, the supply device 12 (e.g., a pump 121 and / or a valve 123) may be operated manually by an operator. More specifically, the machine tool 1A may be equipped with a manual switch for operating the supply device 12. 【0156】During the frictional stirring described above, the coolant L1 may be applied only to the first workpiece W1 (e.g., case 7) of the two workpieces W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8). If the coolant L1 does not reach the second workpiece W2, the coolant L1 will not enter the gap between the first workpiece W1 and the second workpiece W2. 【0157】 As illustrated in Figure 13, the execution of the joining mode M1 may be started when the aforementioned anti-detachment member 67 is in an advanced position P1 that contacts the second workpiece W2 (e.g., cover 8). More specifically, friction stirring of the first workpiece W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8) by the friction stir welding tool T1 may be started when the aforementioned anti-detachment member 67 is in an advanced position P1 that contacts the second workpiece W2 (e.g., cover 8). In this case, the second workpiece W2 is prevented from detaching from the first workpiece W1 when friction stirring is started. 【0158】 As illustrated in Figures 13 and 14, the joining mode M1 may include moving the anti-detachment member 67 from the aforementioned extended position P1 to the aforementioned retracted position P2 (in other words, the retracted position P2 away from the second workpiece W2). More specifically, when the joining mode M1 is executed, the control device 3 may transmit a first operation command A1 (see Figure 31) to the actuator 68 so that the anti-detachment member 67 moves from the aforementioned extended position P1 to the aforementioned retracted position P2. Upon receiving the first operation command A1, the actuator 68 moves the anti-detachment member 67 from the aforementioned extended position P1 to the aforementioned retracted position P2. 【0159】 As illustrated in Figures 14 and 16, the joining mode M1 may include moving the anti-detachment member 67 from the retracted position P2 to the extended position P1. More specifically, when the joining mode M1 is executed, the control device 3 may send a second operation command to the actuator 68 so that the anti-detachment member 67 moves from the retracted position P2 to the extended position P1. Upon receiving the second operation command, the actuator 68 moves the anti-detachment member 67 from the retracted position P2 to the extended position P1. 【0160】As illustrated in Figures 13 and 14, the control device 3 may transmit a first operation command A1 to the actuator 68 so that the anti-detachment member 67 moves from the aforementioned advanced position P1 to the aforementioned retracted position P2 in response to the friction stir welding tool T1 approaching the anti-detachment member 67. The control device 3 may determine whether or not the friction stir welding tool T1 is approaching the anti-detachment member 67 based on the machining program PM. Alternatively, the control device 3 may determine whether or not the friction stir welding tool T1 is approaching the anti-detachment member 67 based on a signal from a proximity sensor. 【0161】 As illustrated in Figures 13 and 14, the control device 3 may control the first actuator 68-1 so that, in response to the friction stir welding tool T1 approaching the first anti-detachment member 67-1, the first anti-detachment member 67-1 moves to the first retracted position P2-1 while the second anti-detachment member 67-2 is in the second advanced position P1-2. 【0162】 As illustrated in Figures 15 and 16, the control device 3 may control the second actuator 68-2 so that, in response to the friction stir welding tool T1 approaching the second anti-detachment member 67-2, the second anti-detachment member 67-2 moves to the second retracted position P2-2 while the first anti-detachment member 67-1 is in the first advanced position P1-1. 【0163】 In the example shown in Figure 10, joining mode M1 is performed with the friction stir welding tool T1 positioned above the backing member 40. If the machine tool 1A is a horizontal machining center, joining mode M1 may be performed with the height of the friction stir welding tool T1 being approximately the same as the height of the backing member 40. 【0164】(Cutting Mode M2) As illustrated in Figures 16 and 30, the control device 3 may selectively execute joining mode M1 and cutting mode M2. Cutting mode M2 ​​is a mode in which at least one of the first workpiece W1 and the second workpiece W2 is cut using a cutting tool T2. More specifically, cutting mode M2 ​​is a mode in which the rotating cutting tool T2 is moved relative to the first workpiece W1 and the second workpiece W2 so that at least one of the first workpiece W1 and the second workpiece W2 is cut. The first workpiece W1 is, for example, the case 7 described above, and the second workpiece W2 is, for example, the cover 8 described above. 【0165】 In the example shown in Figure 27, the spindle 151 is capable of selectively holding a friction stir welding tool T1 and a cutting tool T2. When welding mode M1 is performed, the spindle 151 holds the friction stir welding tool T1, and when cutting mode M2 ​​is performed, the spindle 151 holds the cutting tool T2. 【0166】 As illustrated in Figure 33, when the cutting mode M2 ​​is executed, the control device 3 transmits a second rotation command R2 to the rotary drive device 16. Upon receiving the second rotation command R2, the rotary drive device 16 rotates the spindle 151 that holds the cutting tool T2 around the first axis AX1. 【0167】 When cutting mode M2 ​​is executed, the control device 3 transmits a second movement command S2 to the moving device 17. Upon receiving the second movement command S2, the moving device 17 moves the rotating cutting tool T2 relative to the first workpiece W1 and the second workpiece W2 along the second path PB specified by the machining program PM. 【0168】 The second path PB may overlap with the first path PA described above. For example, a rotating cutting tool T2 (e.g., a milling tool T2-1) may move relative to the first workpiece W1 and the second workpiece W2 along the second path PB which overlaps with the first path PA described above, thereby removing burrs generated during friction stirring by the cutting tool T2 (e.g., a milling tool T2-1). 【0169】The second path PB may include a path parallel to the first direction DR1. For example, a rotating cutting tool T2 (e.g., a drilling tool T2-2) may move along the second path PB, thereby forming holes in the first workpiece W1 (e.g., a case 7) and / or the second workpiece W2 (e.g., a cover 8). Alternatively, or additionally, a rotating cutting tool T2 (e.g., a tapping tool) may move along the second path PB, thereby forming threads in the aforementioned holes (e.g., holes formed in the first workpiece W1). 【0170】 During the execution of cutting mode M2, cutting fluid may be applied to the cutting tool T2. The cutting fluid applied to the cutting tool T2 may be supplied from the tank 141 described above. The cutting fluid may be a liquid with the same components as the coolant L1 released from at least one nozzle 61 during the execution of friction agitation. Alternatively, cutting mode M2 ​​may be performed without applying cutting fluid to the cutting tool T2 (dry cutting). 【0171】 As illustrated in Figure 30, the cutting mode M2 ​​may be performed with the aforementioned anti-detachment member 67 in a retracted position P2 away from the second workpiece W2 (e.g., cover 8). More specifically, with the aforementioned anti-detachment member 67 in a retracted position P2 away from the second workpiece W2 (e.g., cover 8), at least one of the first workpiece W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8) may be cut by the cutting tool T2. 【0172】 If the machine tool 1A does not have the function of cutting a workpiece using a cutting tool, or if there is no need to cut the first workpiece W1 and the second workpiece W2, the above-described cutting mode M2 ​​is omitted. 【0173】 (Tool change mode M3) In the example shown in Figure 27, the control device 3 is capable of executing tool change mode M3. Tool change mode M3 is a mode in which the friction stir welding tool T1 held on the spindle 151 is replaced with a cutting tool T2. 【0174】More specifically, after the execution of the bonding mode M1 described above, the control device 3 transmits a tool change command C1 to the tool change device 19 so that the friction stir welding tool T1 held on the spindle 151 is replaced with a cutting tool T2. Upon receiving the tool change command C1, the tool change device 19 replaces the friction stir welding tool T1 held on the spindle 151 with a cutting tool T2. After the execution of the tool change mode M3, the cutting mode M2 ​​described above is executed. 【0175】 Alternatively, tool changes may be performed manually. More specifically, the operator may manually remove the friction stir welding tool T1 from the spindle 151 and manually attach the cutting tool T2 to the spindle 151. In this case, the tool change mode M3 described above is omitted. 【0176】 (Second Embodiment) The friction stir welding jig 4B and the machine tool 1B in the second embodiment will be described with reference to Figures 35 to 40. Figure 35 is a schematic perspective view showing the friction stir welding jig 4B in the second embodiment. Figure 36 is a schematic perspective view showing the first workpiece W1 and the second workpiece W2 supported by the friction stir welding jig 4B. Figure 37 is a schematic front view showing a part of the machine tool 1B in the second embodiment. Figure 38 is a schematic cross-sectional view showing the welding mode M1 being executed. Figure 39 is a schematic perspective view showing an example of the first workpiece W1. Figure 40 is a schematic perspective view showing the second workpiece W2 and the third workpiece W3 arranged on the first workpiece W1. 【0177】 The second embodiment will be described primarily in terms of its differences from the first embodiment. On the other hand, in the second embodiment, repetitive explanations of matters already explained in the first embodiment will be omitted. Therefore, it goes without saying that even if not explicitly explained in the second embodiment, matters already explained in the first embodiment can be applied to the second embodiment. 【0178】As illustrated in Figures 35 and 36, the friction stir welding jig 4B in the second embodiment includes (1) a backing member 40 that receives pressing force from a friction stir welding tool via the first workpiece W1 as the object to be joined and supports the first workpiece W1, (2) a holding member 50 that holds the first workpiece W1, and (3) at least one nozzle 61 disposed on the backing member 40 that discharges cooling liquid toward the first workpiece W1. 【0179】 As illustrated in Figure 37, the machine tool 1B in the second embodiment includes: (1) a friction stir welding jig 4B on which a first workpiece W1 as an object to be joined is fixed and which has at least one nozzle 61 for discharging a coolant L1 toward the first workpiece W1; (2) a support device 11 for supporting the friction stir welding jig 4B; (3) a machining head 15 comprising a spindle 151 and a support body 153 that supports the spindle 151 so as to be rotatable around a first axis AX1; (4) a rotary drive device 16 for rotating the spindle 151 around the first axis AX1; (5) a moving device 17 for moving the machining head 15 relative to the support device 11; and (6) a supply device 12 for supplying the coolant L1 to at least one nozzle 61. The friction stir welding jig 4B comprises (1) a backing member 40 that receives pressing force from the friction stir welding tool T1 via the first workpiece W1 and supports the first workpiece W1, (2) a holding member 50 that holds the first workpiece W1, and (3) at least one nozzle 61 positioned on the backing member 40. 【0180】 Therefore, the friction stir welding jig 4B and machine tool 1B in the second embodiment have the same effects as the friction stir welding jig 4A and machine tool 1A in the first embodiment. 【0181】 (Optional Additional Configurations) Next, with reference to Figures 35 to 40, optional additional configurations that can be adopted in the friction stir welding jig 4B and the machine tool 1B in the second embodiment will be described. 【0182】 (First workpiece W1 and second workpiece W2) As illustrated in Figure 38, the first workpiece W1 has an end wall 73 supported by a backing member 40. 【0183】In the example shown in Figure 39, the first workpiece W1, which is the object to be joined, is a case 7. The first workpiece W1 (more specifically, the case 7) is joined to the second workpiece W2 by friction stir. The first workpiece W1 may be a workpiece other than a case. The first workpiece W1 is, for example, a cast part. The first workpiece W1 is made of metal. The main component of the material of the first workpiece W1 is, for example, aluminum. In other words, the first workpiece W1 is made of aluminum or an aluminum alloy. 【0184】 In the example shown in Figure 38, the second workpiece W2 is the cover 8. In the example shown in Figure 38, the case 7 is the first object to be joined, and the cover 8 is the second object to be joined. The first object to be joined (e.g., the case 7) and the second object to be joined (e.g., the cover 8) are joined by friction stir. The second workpiece W2 may be a workpiece other than the cover. The second workpiece W2 is made of metal. The main component of the material of the second workpiece W2 is, for example, aluminum. In other words, the second workpiece W2 is made of aluminum or an aluminum alloy. As illustrated in Figure 40, the objects to be joined may include a third workpiece W3 (e.g., a second cover 8-2) in addition to the first workpiece W1 and the second workpiece W2. 【0185】 In the example shown in Figure 39, case 7 has a recess 74 defined by a side wall 71 and an end wall 73. In the example shown in Figure 38, the first direction DR1 coincides with the direction from the end wall 73 toward the internal space SP of the recess 74. 【0186】 In the example shown in Figure 39, the case 7 has a recess 74 capable of receiving an object to be cooled. The object to be cooled received in the recess 74 is, for example, an electrical device that generates heat when an electric current flows through it. The case 7 may also be an automotive part (for example, an electric vehicle part) that is mounted in an automobile with the electrical device housed inside. The electrical device that generates heat when an electric current flows through it is housed in the recess 74, for example, in contact with the end wall 73. 【0187】The object to be cooled (more specifically, electrical equipment) received in the recess 74 is, for example, an inverter (more specifically, a device having a circuit that converts direct current to alternating current), a converter (more specifically, an AC-DC converter that converts alternating current to direct current, or a DC-DC converter that converts a direct current voltage to another direct current voltage), a battery, a charger for charging a battery, a control unit such as an engine control unit, or a circuit board on which multiple electronic components are arranged. 【0188】 As illustrated in Figure 40, the first workpiece W1 may have a protrusion 77 that is held by a holding member 50. The first workpiece W1 may also have a hole 77h into which a part of the holding member 50 is inserted. In the example shown in Figure 40, the hole 77h is formed in the protrusion 77. 【0189】 As illustrated in Figure 40, case 7 may have a groove 73v formed on the outer surface 73t of the end wall 73. The groove 73v of the end wall 73 may be formed by casting. Alternatively, the groove 73v may be formed by cutting the end wall 73 with a cutting tool. 【0190】 The case 7 may have a first port 79a connected to the groove 73v. The cover 8 may have a second port 89b connected to the groove 73v. The first port 79a, the groove 73v, and the second port 89b constitute a part of the refrigerant flow path through which the refrigerant that cools the object to be cooled (more specifically, electrical equipment) received in the recess 74 passes. 【0191】 In the example shown in Figure 38, the cover 8 covers at least a portion of the outer surface 73t of the end wall 73 of the case 7. In the example shown in Figure 38, the cover 8 covers the groove 73v of the end wall 73. 【0192】 (Friction stir welding jig 4B) In the example shown in Figure 38, the backing member 40 has a first support column 42-1 that contacts the first workpiece W1. The first support column 42-1 receives pressing force from the friction stir welding tool T1 via the first workpiece W1 and supports the first workpiece W1. 【0193】In the example shown in Figure 38, the backing member 40 has a second support column 42-2 that contacts the first workpiece W1. The second support column 42-2 receives pressing force from the friction stir welding tool T1 via the first workpiece W1 and supports the first workpiece W1. 【0194】 In the example shown in Figure 38, the base 64 attached to the support device 11 and the first support column 42-1 are integrally molded. The base 64, the first support column 42-1, and the second support column 42-2 may also be integrally molded. 【0195】 In the example shown in Figure 38, at least one nozzle 61 is a spray nozzle SN that diffuses the coolant L1 toward the first workpiece W1. The friction stir welding jig 4B may also include a first nozzle 61a and a second nozzle 61b, both positioned on the backing member 40. 【0196】 In the example shown in Figure 38, the first nozzle 61a is attached to the side surface 43 of the backing member 40 (more specifically, to the side surface of the first support column 42-1). The second nozzle 61b is attached to the side surface 43 of the backing member 40 (more specifically, to the side surface of the second support column 42-2). 【0197】 In the example shown in Figure 38, a supply channel 44 is formed inside the backing member 40 to supply coolant L1 to at least one nozzle 61. More specifically, in the example shown in Figure 38, a first supply channel 44-1 is formed inside the first support column 42-1 to supply coolant L1 to the first nozzle 61a. In addition, a second supply channel 44-2 is formed inside the second support column 42-2 to supply coolant L1 to the second nozzle 61b. 【0198】 In the example shown in Figure 35, the friction stir welding jig 4B includes a base 64 that is attached to the support device 11 of the machine tool, and the base 64 has a bottom wall 648 and a side wall 649. In the example shown in Figure 35, the first support column 42-1 is positioned inside the side wall 649. Also, the second support column 42-2 is positioned inside the side wall 649. 【0199】In the examples shown in Figures 35 and 36, the friction stir welding jig 4B includes a holding member 50 for holding the first workpiece W1, and the holding member 50 includes a bolt BT. 【0200】 In the examples shown in Figures 35 and 36, the first workpiece W1 is fixed to the friction stir welding jig 4B by inserting the bolt BT into both the hole 77h formed in the first workpiece W1 and the hole 649h formed in the friction stir welding jig 4B (more specifically, the hole 649h formed in the side wall 649). Alternatively, the holding member 50 may be a clamp-type holding member (see Figure 4). 【0201】 The friction stir welding jig 4B may also include a detachment prevention member 67 (see Figure 13) to prevent the second workpiece W2 from detaching from the first workpiece W1. 【0202】 (Workpiece Processing Method) The workpiece processing method in the embodiment will be described with reference to Figures 1 to 41. Figure 41 is a flowchart showing an example of the workpiece processing method in the embodiment. 【0203】 As illustrated in Figure 26 or Figure 37, in the first step ST1, the friction stir welding jig 4 is fixed to the support device 11 (for example, the table 111) of the machine tool 1. The first step ST1 is the fixing step. The machine tool 1 may be machine tool 1A in the first embodiment, machine tool 1B in the second embodiment, or any other machine tool. Since each component of the machine tool (1A, 1B) has been described in the first or second embodiment, a repetitive description of each component of the machine tool (1A, 1B) will be omitted. 【0204】 In the fixing process (first step ST1), the friction stir welding jig 4, which is fixed to the support device 11 (for example, the table 111), comprises a backing member 40 and a holding member 50. 【0205】In the fixing step (first step ST1), the friction stir welding jig 4 fixed to the support device 11 (for example, the table 111) may be the friction stir welding jig 4A in the first embodiment, the friction stir welding jig 4B in the second embodiment, or any other friction stir welding jig. Since each component of the friction stir welding jig (4A, 4B) has already been described in the first or second embodiment, a repeated explanation of each component of the friction stir welding jig (4A, 4B) will be omitted. 【0206】 The fixing step (first step ST1) may include fixing the friction stir welding jig 4 to the support device 11 via a fixing member F such as a bolt F1 (see Figure 26 or Figure 37). Alternatively, or additionally, the fixing step (first step ST1) may include fixing the friction stir welding jig 4 to the support device 11 via a chuck. 【0207】 If the friction stir welding jig 4 is already fixed to the support device 11 (for example, the table 111) of the machine tool 1, the first step ST1 is omitted. 【0208】 As illustrated in Figure 26 or Figure 37, in the second step ST2, the object to be joined W is attached to the friction stir welding jig 4. The second step ST2 is the attachment step. In the example shown in Figure 12, the attachment step (second step ST2) includes attaching the first workpiece W1, which is the object to be joined, to the friction stir welding jig 4. The first workpiece W1 attached to the friction stir welding jig 4 in the attachment step (second step ST2) may be a case 7 or another workpiece. 【0209】 The mounting step (second step ST2) includes mounting the first workpiece W1 to the friction stir welding jig 4 so that the first workpiece W1 is held by the holding member 50 of the friction stir welding jig 4. In the example shown in Figure 11 or Figure 35, the holding member 50 includes a first holding member 51a and a second holding member 51b. 【0210】The mounting step (second step ST2) may include attaching a first portion of the first workpiece W1 (for example, the first side wall 71-1 of the case 7) to the first holding member 51a, and attaching a second portion of the first workpiece W1 (for example, the second side wall 71-2 of the case 7) to the second holding member 51b. In the example shown in Figure 9, the first holding member 51a has a first movable portion 513a. In the example shown in Figure 9, the first portion of the first workpiece W1 is held between the first fixed portion 511a and the first movable portion 513a. In the example shown in Figure 9, the second holding member 51b has a second movable portion 513b. In the example shown in Figure 9, the second portion of the first workpiece W1 is held between the second fixed portion 511b and the second movable portion 513b. Each of the first fixed portion 511a and the second fixed portion 511b may be composed of a part of the upper base 646. 【0211】 Alternatively, as illustrated in Figure 36, the mounting step (second step ST2) may include attaching the first workpiece W1 to the friction stir welding jig 4 via bolts BT. 【0212】 In the example shown in Figure 23, the friction stir welding jig 4 includes a base 64. The workpiece processing method in the embodiment may include a step of adjusting the relative position of the support end 40e of the backing member 40 with respect to the base 64 in a direction parallel to the first direction DR1 (adjustment step). This adjustment step may be performed before the first workpiece W1 (e.g., case 7) is attached to the friction stir welding jig 4, or after the first workpiece W1 (e.g., case 7) is attached to the friction stir welding jig 4. 【0213】 By performing the adjustment process, the end wall 73 of the first workpiece W1 is suitably supported by the support end 40e of the backing member 40. 【0214】 As illustrated in Figure 23, if the backing member 40 includes a first support column 42-1, the adjustment step may include extending or shortening the first support column 42-1. As illustrated in Figure 24, if the backing member 40 includes a second support column 42-2, the adjustment step may include extending or shortening the second support column 42-2. 【0215】 If the relative position of the support end 40e of the backing member 40 with respect to the base 64 cannot be adjusted, or if it is not necessary to adjust the relative position of the support end 40e of the backing member 40 with respect to the base 64, the adjustment step is omitted. 【0216】 As illustrated in Figures 2 and 3, the workpiece processing method in the embodiment may include placing the second workpiece W2 on the first workpiece W1 after the first workpiece W1 has been attached to the friction stir welding jig 4. More specifically, the second workpiece W2 may be placed on the first workpiece W1 after the first workpiece W1 has been attached to the friction stir welding jig 4. 【0217】 Alternatively, the workpiece processing method in the embodiment may include attaching the first workpiece W1 to the friction stir welding jig 4 while the second workpiece W2 is placed on the first workpiece W1. 【0218】 In the example shown in Figure 19 or Figure 40, the first workpiece W1 is the case 7, and the second workpiece W2 is a cover 8 that covers a part of the case 7. The cover 8 may also cover a groove 73v formed on the outer surface 73t of the end wall 73 of the case 7. 【0219】 As illustrated in Figures 12 and 13, the workpiece processing method in the embodiment may include, after the execution of the second step ST2 (more specifically, after the first workpiece W1 and the second workpiece W2 are supported by the friction stir welding jig 4), changing the position of the anti-detachment member 67 from a retracted position P2 away from the second workpiece W2 (e.g., cover 8) to an advanced position P1 in contact with the second workpiece W2 (e.g., cover 8) (position change step). If the anti-detachment member 67 is not present, or if it is not necessary to use the anti-detachment member 67, the position change step is omitted. 【0220】 In the third step ST3, the first workpiece W1 (for example, case 7) and the second workpiece W2 (for example, cover 8) are joined by frictional stirring. The third step ST3 is a joining process. 【0221】As illustrated in Figure 10 or Figure 38, the joining process (third step ST3) is performed with the backing member 40 of the friction stir welding jig 4 receiving pressing force from the friction stir welding tool T1 via the first workpiece W1 (for example, case 7). 【0222】 More specifically, the joining process (third step ST3) includes rotating the friction stir welding tool T1 while the backing member 40 of the friction stir welding jig 4 is receiving a pressing force from the friction stir welding tool T1 via the first workpiece W1 (e.g., case 7). The joining process (third step ST3) may also include moving the friction stir welding tool T1 relative to the first workpiece W1 along the first path PA while the backing member 40 of the friction stir welding jig 4 is receiving a pressing force from the friction stir welding tool T1 via the first workpiece W1 (e.g., case 7). The first path PA has already been described in the first embodiment, so a repeated explanation of the first path PA will be omitted. 【0223】 As illustrated in Figure 10 or Figure 38, in the fourth step ST4, coolant L1 is discharged onto the first workpiece W1 (e.g., case 7) from at least one nozzle 61 located on the backing member 40. More specifically, coolant L1 is sprayed onto the first workpiece W1 (e.g., case 7) from at least one nozzle 61 located on the backing member 40. The fourth step ST4 is a cooling step. The coolant L1 is, for example, a water-soluble coolant. The main component of the water-soluble coolant is, for example, water. The water-soluble coolant may also contain a water-soluble lubricant (e.g., a water-soluble cutting fluid or a water-soluble grinding fluid) and / or a surfactant. 【0224】 The cooling process (fourth step ST4) is performed during the bonding process (third step ST3). In other words, during the friction stirring described above, the cooling liquid L1 is discharged from at least one nozzle 61 located on the backing member 40 to the first workpiece W1 (for example, case 7). 【0225】The cooling process (fourth step ST4) may be started before the start of the bonding process (third step ST3). Alternatively, the cooling process (fourth step ST4) may be started simultaneously with the bonding process (third step ST3). The cooling process (fourth step ST4) may be started manually or based on a command from the control device 3. 【0226】 The cooling process (fourth step ST4) may be stopped after the completion of the joining process (third step ST3). Alternatively, the cooling process (fourth step ST4) may be stopped simultaneously with the completion of the joining process (third step ST3). The cooling process (fourth step ST4) may be stopped by manual operation or based on a command from the control device 3. 【0227】 During frictional stirring, the application of the cooling liquid L1 to the first workpiece W1 suppresses distortion of the first workpiece W1 caused by the heat generated by frictional stirring. 【0228】 As illustrated in Figure 7 or Figure 38, during the execution of the friction stirring described above, coolant L1 may be discharged from at least one nozzle 61 to substantially the entire inner surface 73n of the end wall 73 of the first workpiece W1, excluding the portion in contact with the backing member 40. In other words, coolant L1 may be discharged from at least one nozzle 61 so that it reaches substantially the entire inner surface 73n of the end wall 73, excluding the portion in contact with the backing member 40. 【0229】 When the coolant L1 reaches substantially the entire inner surface 73n of the end wall 73, excluding the portion in contact with the backing member 40, distortion of the first workpiece W1 due to heat generated by friction stirring is suppressed, regardless of the position where it is frictionally stirred by the friction stir welding tool T1. Therefore, it is not necessary to move at least one nozzle 61 in response to a change in the position where it is frictionally stirred by the friction stir welding tool T1. 【0230】During the friction agitation described above, the coolant L1 may be applied only to the first workpiece W1 (e.g., case 7) of the two workpieces W1 (e.g., cover 8). In other words, during the friction agitation described above, the coolant L1 may be applied to the first workpiece W1 (e.g., case 7) without reaching the second workpiece W2 (e.g., cover 8). If the coolant L1 does not reach the second workpiece W2, the coolant L1 will not enter the gap between the first workpiece W1 and the second workpiece W2. 【0231】 In the example shown in Figure 9 or Figure 38, at least one nozzle 61 discharges coolant L1 into a recess 74 of the case 7. Thus, the case 7 prevents the coolant L1 from reaching the second workpiece W2 (for example, the cover 8). 【0232】 Additionally, as illustrated in Figure 13, the cooling step (fourth step ST4) may include discharging a coolant L1 from the second group of nozzles 62 onto the outer surface of the first workpiece W1. When the coolant is applied to the outer surface of the first workpiece W1 in addition to the inner surface, thermal deformation of the first workpiece W1 due to frictional stirring is further prevented. 【0233】 As illustrated in Figures 13 and 14, the workpiece processing method in the embodiment may include a step of retracting the first detachment prevention member 67-1 so that it moves away from the second workpiece W2 (e.g., cover 8) during the execution of the joining step (third step ST3) (in other words, during the execution of the friction stir described above) (retraction step). The retraction step may include retracting the first detachment prevention member 67-1 so that it moves away from the second workpiece W2 (e.g., cover 8) in response to the friction stir joining tool T1 approaching the first detachment prevention member 67-1. 【0234】As illustrated in Figures 14 and 15, the workpiece processing method in the embodiment may include a step of advancing the first anti-detachment member 67-1 toward the second workpiece W2 (e.g., cover 8) so that the first anti-detachment member 67-1 comes into contact with the second workpiece W2 (e.g., cover 8) during the execution of the joining step (third step ST3) (in other words, during the execution of the friction stir described above) (advancing step). The advancing step may include advancing the first anti-detachment member 67-1 toward the second workpiece W2 (e.g., cover 8) in response to the friction stir joining tool T1 moving away from the first advancing position P1-1 described above. 【0235】 More specifically, the retraction step may include retracting the first anti-detachment member 67-1 so that the first anti-detachment member 67-1 moves away from the second workpiece W2 (e.g., cover 8) while the second anti-detachment member 67-2 is maintained in the above-mentioned second advance position P1-2, in response to the friction stir welding tool T1 approaching the first anti-detachment member 67-1 (see Figures 13 and 14). Alternatively, the retraction step may include retracting the second anti-detachment member 67-2 so that the second anti-detachment member 67-2 moves away from the second workpiece W2 (e.g., cover 8) while the first anti-detachment member 67-1 is maintained in the above-mentioned first advance position P1-1, in response to the friction stir welding tool T1 approaching the second anti-detachment member 67-2 (see Figures 15 and 16). 【0236】 The joining step (third step ST3) may include joining the case 7 and the cover 8 by friction stirring such that a flow path 91 (for example, a refrigerant flow path through which refrigerant flows) is formed by the groove 73v formed in the end wall 73 of the case 7 and the cover 8. 【0237】The workpiece processing method in the embodiment may include, after the joining process is performed (in other words, after the friction stir joining of the first workpiece W1 and the second workpiece W2 is completed), changing the position of the anti-detachment member 67 from an advanced position P1 that is in contact with the second workpiece W2 (e.g., cover 8) to a retracted position P2 that is away from the second workpiece W2 (e.g., cover 8) (second position change step). If the anti-detachment member 67 is not present, or if there is no need to use the anti-detachment member 67, the second position change step is omitted. 【0238】 The workpiece machining method in the embodiment may include a step of replacing the friction stir welding tool T1 held on the spindle 151 with a cutting tool T2. In the example shown in Figure 27, in the fifth step ST5, the friction stir welding tool T1 held on the spindle 151 is replaced with a cutting tool T2. The fifth step ST5 is a tool replacement step. 【0239】 The tool change step (fifth step ST5) includes removing the friction stir welding tool T1 from the spindle 151 and attaching the cutting tool T2 to the spindle 151. The replacement of the friction stir welding tool T1 held on the spindle 151 with the cutting tool T2 may be performed using a tool changer 19. Alternatively, the replacement of the friction stir welding tool T1 held on the spindle 151 with the cutting tool T2 may be performed manually. If tool change is not necessary, the fifth step ST5 is omitted. 【0240】 The workpiece machining method in the embodiment may include a step of cutting at least one of the first workpiece W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8). In the example shown in Figure 30, in the sixth step ST6, at least one of the first workpiece W1 (e.g., case 7) and the second workpiece W2 (e.g., cover 8) is cut by a cutting tool T2. The sixth step ST6 is a cutting step. 【0241】In the example shown in Figure 30, the cutting process (sixth step ST6) is performed after the joining process. In other words, the cutting process is performed after the joining of the first workpiece W1 and the second workpiece W2 is completed. In this case, after the joining process (third step ST3) and before the cutting process (sixth step ST6), the friction stir welding tool T1 held on the spindle 151 is replaced with the cutting tool T2. 【0242】 In the example shown in Figure 30, the cutting process (sixth step ST6) includes cutting a portion of the joint area JR between the end wall 73 of the case 7 and the cover 8. 【0243】 As illustrated in Figure 30, the cutting process (sixth step ST6) may include removing burrs generated during friction stirring using a cutting tool T2 (for example, a milling tool T2-1). 【0244】 Alternatively, or additionally, the cutting step (sixth step ST6) may include forming a hole (e.g., a hole 75h of the mounting portion 75) in the first workpiece W1 (e.g., case 7) and / or the second workpiece W2 (e.g., cover 8) using a cutting tool T2 (e.g., a drilling tool T2-2). Alternatively, or additionally, the cutting step (sixth step ST6) may include forming a screw thread in the aforementioned hole (e.g., a hole formed in the first workpiece W1) using a cutting tool T2 (e.g., a tapping tool). 【0245】 Alternatively, or additionally, the cutting process (sixth step ST6) may be performed before the joining process (third step ST3). Further alternatively, the cutting process (sixth step ST6) may be omitted. 【0246】 In the workpiece processing method of this embodiment, the first workpiece W1 is held by the holding member 50 of the friction stir welding jig 4. Therefore, displacement of the first workpiece W1 is prevented during friction stir welding. 【0247】 In the workpiece processing method of this embodiment, a cooling liquid L1 is applied to the first workpiece W1 while friction stirring is being performed. Therefore, distortion of the first workpiece W1 due to heat generated by friction stirring is suppressed. 【0248】 In the workpiece processing method of this embodiment, the coolant L1 is applied to the first workpiece W1 using at least one nozzle 61 arranged on the backing member 40. Therefore, it is not necessary to prepare the at least one nozzle 61 separately from the friction stir welding jig 4. 【0249】 Furthermore, since at least one nozzle 61 is positioned on the backing member 40, once the position of the first workpiece W1 relative to the friction stir welding jig 4A is determined (more specifically, once the first workpiece W1 is held by the holding member 50), the position of at least one nozzle 61 relative to the first workpiece W1 is determined. Therefore, setting the position of at least one nozzle 61 relative to the first workpiece W1 is easy. 【0250】 The present invention is not limited to the embodiments or modifications described above, and it is clear that each embodiment or modification can be appropriately modified or changed within the scope of the technical concept of the present invention. Furthermore, the various technologies used in each embodiment or modification can be applied to other embodiments or other modifications, as long as no technical inconsistencies arise. In addition, any optional additional configurations in each embodiment or modification can be omitted as appropriate. 【0251】 For example, in the examples shown in Figures 9 and 38, only the first workpiece W1 is in contact with the backing member 40. In other words, when the first workpiece W1 and the second workpiece W2 are frictionally stirred, the backing member 40 is configured to be in contact only with the first workpiece W1 of the two workpieces W2. Alternatively, as illustrated in Figure 42, when the first workpiece W1 and the second workpiece W2 are frictionally stirred, the backing member 40 may be configured to be in contact with each of the first workpiece W1 and the second workpiece W2. 【0252】1, 1A, 1B... Machine tool, 3... Control device, 4, 4A, 4B... Friction stir welding jig, 7... Case, 8... Cover, 8-2... Second cover, 11... Support device, 12... Supply device, 13... Circulation channel, 15... Machining head, 15g... Lower end, 16... Rotary drive device, 16m... Motor, 17... Moving device, 19... Tool changer, 21... Wall, 23... Door, 30... Processor, 32... Memory, 34... Communication circuit, 36... Input device, 36t... Touch panel, 37... Display, 38... Bus, 40... Backing member, 40e... Support end, 42... Support column, 42-1... First support column, 42-2... Second support column 42-3...Third support, 42-4...Fourth support, 42-5...Fifth support, 42-6...Sixth support, 42a-1...First end, 42a-2...Second end, 43...Side, 43a...First side, 43b...Second side, 43c...Third side, 44...Supply channel, 44-1...First supply channel, 44-2...Second supply channel, 44-3...Third supply channel, 50...Holding member, 51a...First holding member, 51b...Second holding member, 61...Nozzle, 61a...First nozzle, 61b...Second nozzle, 61c...Third nozzle, 61d...Nozzle, 62...Nozzle, 64...Base, 64-1...First spring, 64-2...Second spring Pulling, 64h...Mounting hole, 65-1...First fixing member, 65-2...Second fixing member, 67...Anti-detachment member, 67-1...First anti-detachment member, 67-2...Second anti-detachment member, 68...Actuator, 68-1...First actuator, 68-2...Second actuator, 71...Side wall, 71-1...First side wall, 71-2...Second side wall, 71-3...Third side wall, 71-4...Fourth side wall, 72...Flange, 72-1...First protruding edge, 72-2...Second protruding edge, 73...End wall, 73n...Inner surface, 73p...Protrusion, 73t...Outer surface, 73v...Groove, 74...Recess, 75...Mounting part, 75h...Hole, 77... Protruding part, 77h... Hole part, 79a... First port, 79b... Second port, 81... Outer edge part, 83... Central part, 89b... Second port, 91... Flow path, 111... Table, 121... Pump, 123... Valve, 131... Flow path, 138... Return flow path, 141... Tank, 143... Chiller, 151... Spindle, 153... Support, 171... Machining head moving device, 178... Table moving device, 178a... X-axis moving device, 178b... Y-axis moving device, 191... Tool changing arm, 191a... First gripping part, 191b... Second gripping part, 194... Arm rotation device, 196... Arm moving device,421-1...First part, 421-2...Second part, 421-3...Third part, 421-4...Fourth part, 511a...First fixed part, 511b...Second fixed part, 513a...First movable part, 513b...Second movable part, 641...Lower base, 646...Upper base, 646h...Through hole, 647...Connecting support, 648...Bottom wall, 649...Side wall, 649h...Hole, 730...Bottom wall, 731...Stepped part, A1...First operation command, AX1...First axis, AX2 ...Second axis, BT...Bolt, C1...Tool change command, CB...Cover, DA...Data, DR1...First direction, DR2...Second direction, F...Fixing member, F1...Bolt, G...Area of ​​the first workpiece in contact with the backing member, JR...Joining area, L1...Coolant, M1...Joining mode, M2...Cutting mode, M3...Tool change mode, OP...Opening, P1...Advance position, P1-1...First advance position, P1-2...Second advance position, P2...Retracted position, P2-1 ...First retraction position, P2-2...Second retraction position, PA...First path, PA1...Boundary between the first workpiece and the second workpiece, PA1-1...Boundary between the stepped part of the case and the outer edge of the cover, PA2...Path along the area where the first workpiece and the second workpiece overlap, PA2-1...Path passing through the central part of the cover, PB...Second path, PM...Machining program, R1...First rotation command, R2...Second rotation command, RG1...Machining area, S1...First movement command S2...Second movement command, SB1...First threaded member, SB2...Second threaded member, SN...Spray nozzle, SN1...First spray nozzle, SP...Internal space, SP1...Space between the first holding member and the second holding member, T1...Friction stir welding tool, T2...Cutting tool, T2-1...Milling tool, T2-2...Drilling tool, U1...Supply command, W...Object to be joined, W1...First workpiece, W2...Second workpiece, W3...Third workpiece, Wt...Outer side surface,

Claims

1. A friction stir welding jig comprising: a backing member that receives pressing force from a friction stir welding tool via a first workpiece as the object to be joined and supports the first workpiece; a holding member that holds the first workpiece; and at least one nozzle disposed on the backing member for discharging a cooling liquid toward the first workpiece.

2. The friction stir welding jig according to claim 1, wherein at least one nozzle includes a spray nozzle for diffusing the cooling liquid toward the first workpiece.

3. The friction stir welding jig according to claim 1 or 2, wherein at least one nozzle is attached to the side surface of the backing member.

4. The friction stir welding jig according to any one of claims 1 to 3, wherein a supply channel for supplying the coolant to the at least one nozzle is formed inside the backing member.

5. The friction stir welding jig according to any one of claims 1 to 4, wherein the backing member comprises a first support having a first end that contacts the first workpiece and a second support having a second end that contacts the first workpiece, and when the direction in which the first workpiece is pressed by the friction stir welding tool is defined as the first direction, the position of the first end is different from the position of the second end in the direction along the first direction.

6. A friction stir welding jig according to any one of claims 1 to 4, further comprising a base for supporting the backing member, wherein the backing member has a support end that contacts the first workpiece, and the relative position of the support end with respect to the base is adjustable in the first direction, when the direction in which the first workpiece is pressed by the friction stir welding tool is defined as the first direction.

7. The friction stir welding jig according to any one of claims 1 to 6, wherein the holding member holds the side wall of the first workpiece, and the backing member supports the end wall of the first workpiece.

8. The friction stir welding jig according to any one of claims 1 to 7, wherein the holding member includes a first holding member for holding a first portion of the first workpiece and a second holding member for holding a second portion of the first workpiece, and the backing member is arranged to cross the space between the first holding member and the second holding member.

9. The friction stir welding jig according to any one of claims 1 to 8, further comprising a detachment prevention member for preventing the second workpiece from detaching from the first workpiece, wherein the detachment prevention member is repositionable between an advanced position in contact with the second workpiece and a retracted position away from the second workpiece.

10. A machine tool comprising: a friction stir welding jig on which a first workpiece as an object to be joined is fixed and which has at least one nozzle for discharging a coolant toward the first workpiece; a support device for supporting the friction stir welding jig; a machining head comprising a spindle and a support body for rotatably supporting the spindle around a first axis; a rotation drive device for rotating the spindle around the first axis; a moving device for moving the machining head relative to the support device; and a supply device for supplying the coolant to the at least one nozzle, wherein the friction stir welding jig comprises a backing member that receives pressing force from a friction stir welding tool via the first workpiece and supports the first workpiece; a holding member that holds the first workpiece; and the at least one nozzle disposed on the backing member.

11. The machine tool according to claim 10, further comprising a wall surrounding the processing area in which friction stirring is performed.

12. The machine tool according to claim 10 or 11, comprising a rotary drive device and a control device for controlling the moving device, wherein the control device is capable of selectively performing a joining mode in which the first workpiece and the second workpiece are frictionally stir-bonded using the friction stir-bonding tool, and a cutting mode in which at least one of the first workpiece and the second workpiece is cut using a cutting tool.

13. A workpiece processing method comprising: attaching a first workpiece to a friction stir welding jig so that the first workpiece, as the object to be joined, is held by a holding member of the friction stir welding jig; joining the first workpiece and a second workpiece by friction stir while the backing member of the friction stir welding jig is receiving pressing force from a friction stir welding tool via the first workpiece; and discharging a cooling liquid to the first workpiece from at least one nozzle positioned on the backing member during the execution of the friction stir.

14. The workpiece processing method according to claim 13, wherein the first workpiece has an end wall supported by the backing member, and during the execution of friction stirring, the coolant is discharged from at least one nozzle toward substantially the entire inner surface of the end wall, excluding the portion of the inner surface of the end wall that is in contact with the backing member.

15. The workpiece processing method according to claim 13 or 14, wherein during the execution of friction stirring, the coolant is applied only to the first workpiece among the first and second workpieces.

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