Friction stir welding method and friction stir welding apparatus

Abstract

To provide a friction stir joining method and a friction stir joining device that suppress deformation of a hollow material, and can obtain a friction stir joining part, in friction stir joining of overlapping a plate material composed of a metal material, and the hollow material which is composed of the same kind as or different kind of a material from the plate material and has a closed cross section having an outer surface where the plate material is overlapped and an inner surface that is a surface opposite to the outer surface.SOLUTION: A friction stir joining method includes: an overlapping step of overlapping a plate material 30, and a hollow material 20; and a friction stir joining step of forming a friction stir joining part 31 between the plate material 30 and the hollow material 20 using a rotated joining tool 40. The friction stir joining step provides a deformation suppression mechanism 50 for suppressing deformation of the hollow material 20 in at least a partial region corresponding to a region where the friction stir joining part 31 is formed out of an inner surface 23.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a friction stir welding method and a friction stir welding apparatus, and more particularly, to a friction stir welding method and a friction stir welding apparatus for friction stir welding a plate material and a hollow material.

Background Art

[0002] In vehicle equipment such as automobiles, weight reduction is required for fuel efficiency improvement, CO2 reduction effect, and steering performance improvement. Therefore, the use of hollow materials made of aluminum or steel extruded materials is being considered, and joining of the hollow materials and other members is necessary. As a joining method of metals or non-metals such as metals and resins using such hollow materials, a friction stir welding method (Friction Stir Welding: FSW) is known. This joining method is a means of plastically flowing a part of the base materials to be joined by pushing a stirring pin made of a high-strength material such as steel into the joining part of a soft material such as aluminum while rotating the stirring pin. Since the friction stir welding method is suitable for soft base materials, it has been widely used industrially for joining aluminum materials. Recently, however, the development of high-strength stirring pins has advanced, and it has become possible to use them for joining steel materials as well. Recently, not only joining of the same kind of metals but also friction stir welding methods between dissimilar metals such as aluminum and iron shown in Patent Document 1, or friction stir welding methods between metals and non-metals such as metals and resins shown in Patent Document 2 have been attracting attention.

[0003] Patent Document 3 describes a friction stir welding method for hollow materials, in which the circumferential surfaces of the circumferential walls of the hollow materials are brought into contact with each other, and pressure is applied from inside the hollow materials to the contacting circumferential walls of each hollow material in the direction of contact, while the circumferential surfaces are joined by butt joint. Patent Document 4 describes a joining method in which a hollow aluminum profile, in which a front plate and a back plate are connected by a plurality of connecting plates, is butted against the front plates and back plates, a connecting part is provided at the butt joint to connect the front plate and the back plate, and the butt joint is joined by friction stir welding. Furthermore, Patent Document 5 describes a method for manufacturing a profile by friction stir welding in which a pair of arms extending from each of a pair of H-shaped members toward the opposing H-shaped member are butted together, and a fluid-containing body that receives the pressing force of the rotating tool is placed on the back surface of the workpiece, which is pressed while frictional heat is applied by a rotating tool. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-120056 [Patent Document 2] Japanese Patent Publication No. 2012-170975 [Patent Document 3] Patent No. 3844835 [Patent Document 4] Patent No. 4839054 [Patent Document 5] Japanese Patent Publication No. 2008-207255 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, the technologies described in Patent Documents 3 and 4 relate to butt welding in which hollow materials equipped with connecting members capable of receiving the pressing force of a rotary tool are butted together near the connecting members, and friction stir welding is performed while the pressing force of the rotary tool is received by the connecting members. They do not mention overlap welding in which other members are overlapped and friction stir-welded in the region corresponding to the void of the hollow material. Similarly, Patent Document 5 also relates to butt welding, in which the butt joint is friction stir-welded while receiving the pressing force of a rotating tool through a fluid-containing body placed on the back side of the butt joint. However, the fluid-containing body must be precisely positioned to match the location of the butt joint, which presents problems from the standpoint of work efficiency.

[0006] On the other hand, in the case of overlap welding, where another member is overlapped and friction stir-welded onto the outer surface of a hollow material having a void, when attempting to overlap welding by friction stir welding by overlapping another metal joining member onto the outer surface of a hollow metal material having an internal void and pressing the joining member against it while rotating the joining tool, the outer surface of the hollow material deforms toward the inner surface due to the pressing force of the joining tool. As a result, sufficient frictional force to soften the joining member and the hollow material cannot be obtained, leading to a decrease in the joint strength or even failure to join the joint, resulting in the problem of not being able to obtain a good friction stir-welded joint.

[0007] The present invention has been made in view of the aforementioned problems, and its object is to provide a friction stir welding method and friction stir welding apparatus that can suppress deformation of the hollow material and obtain a good friction stir weld when friction stir welding a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface. [Means for solving the problem]

[0008] Therefore, the above objective of the present invention is achieved by the configuration of the friction stir welding method described below [1].

[0009] [1] A friction stir welding method for joining a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface, A superimposing step of superimposing the aforementioned plate material and the aforementioned hollow material, The process includes a friction stir welding step of forming a friction stir joint between the plate material and the hollow material using a rotating joining tool, A friction stir welding method comprising providing a deformation suppression mechanism for suppressing deformation of the hollow material in at least a portion of the inner surface corresponding to the region where the friction stir weld is formed, during the friction stir welding step.

[0010] Furthermore, the above objective of the present invention is achieved by the configuration of the friction stir welding apparatus described in [2] below.

[0011] [2] A superimposing mechanism for superimposing a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface, A friction stir welding mechanism that uses a rotating joining tool to form a friction stir joint between the plate material and the hollow material, A friction stir welding apparatus comprising a deformation suppression mechanism for suppressing deformation of the hollow material in at least a portion of the inner surface corresponding to the region in which the friction stir joint is formed when the friction stir joint is formed. [Effects of the Invention]

[0012] According to the friction stir welding method and friction stir welding apparatus of the present invention, when friction stir welding a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate material and having an outer surface on which the plate material is superimposed and an inner surface which is the surface opposite to the outer surface, it is possible to obtain a good friction stir joint by suppressing the deformation of the hollow material with a deformation suppression mechanism for suppressing the deformation of the hollow material. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is an explanatory diagram showing a friction stir welding method between a hollow material and a plate material according to the first embodiment of the present invention. [Figure 2]FIG. 2 is an explanatory view showing a friction stir welding method for a hollow material and a plate material according to a second embodiment of the present invention. [Figure 3] FIG. 3 is an explanatory view showing a friction stir welding method for a hollow material and a plate material according to a third embodiment of the present invention. [Figure 4] FIG. 4 is an explanatory view showing a friction stir welding method for a hollow material and a plate material according to a fourth embodiment of the present invention. [Figure 5] FIG. 5 is an explanatory view showing a friction stir welding method for a hollow material and a plate material according to a fifth embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, each embodiment of a friction stir welding method for a hollow material according to the present invention and a friction stir welding apparatus that enables overlap welding by the friction stir welding method will be described in detail based on the drawings.

[0015] (First Embodiment) FIG. 1 is an explanatory view showing a friction stir welding method for a hollow material according to a first embodiment of the present invention. The friction stir welding method according to the present embodiment is, for example, a method of joining a plate material 30 made of a metal material such as aluminum, aluminum alloy, magnesium, magnesium alloy, titanium, titanium alloy, copper, copper alloy, iron, steel, etc., and a hollow material 20 made of the same or different material as the plate material 30 and having a void portion 21 inside by friction stir welding. In the present invention, as long as friction stir welding is possible with the plate material 30 made of a metal material, the material of the hollow material 20 may be the same as or different from the plate material.

[0016] Examples of the material of the hollow material 20 in the case of being the same as the plate material 30 include, for example, when the plate material 30 is aluminum, aluminum or an aluminum alloy as the hollow material 20. That is, the "same kind" as used here includes not only completely the same material but also metal materials having a common main component.

[0017] Furthermore, when the hollow material 20 is made of a different material from the plate material 30, for example, if the plate material 30 is aluminum, examples of materials for the hollow material 20 include metallic materials with different main components from aluminum, such as magnesium, magnesium alloys, titanium, titanium alloys, copper, copper alloys, iron, and steel. Also, examples of materials for the hollow material 20 include non-metallic materials such as polyethylene (PE), polypropylene (PP), ethylene-acrylic acid copolymer (EAA), polytetrafluoroethylene (PTFE), and composites in which fibers are mixed into these resins, such as carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP).

[0018] The hollow material 20 is formed in a tubular shape and has a void portion 21 which is a closed cross-section surrounded by a partition wall 24 with a substantially rectangular cross-section. The partition wall 24 has an outer surface 22 on its outside and an inner surface 23 on the opposite side (i.e., the inside) of the outer surface 22. In the region of the hollow material 20 corresponding to the void portion 21, the outer surface 22 of the hollow material 20 and the plate material 30 are joined by a friction stir joint 31.

[0019] In the friction stir welding method of this embodiment, the void portion 21 of the hollow material 20 is sealed by closing the openings at both ends in the longitudinal direction of the void portion 21 (i.e., the front and back sides of the paper in Figure 1) with a lid member (not shown). The lid member may be welded at the opening, or it may be sealed by a sealing member provided on the lid member.

[0020] Next, the plate material 30 is placed on the outer surface 22 of the region corresponding to the void 21 of the hollow material 20, and after being placed on a mounting table (not shown), the hollow material 20 and the plate material 30 are pressed together with a pair of clamps 45, which are a stacking mechanism, and fixed to the mounting table.

[0021] Then, a pressurized fluid P, consisting of a liquid such as water or oil, or a gas such as air, compressed from a pressurized fluid supply mechanism (not shown), is filled into the sealed void 21, and the pressing force of the pressurized fluid P presses the partition wall 24 from the inside out. In this embodiment, the pressurized fluid P constitutes the deformation suppression mechanism 50.

[0022] Next, the joining tool 40, which is a friction stir welding mechanism, is brought into contact with the plate material 30 while rotating. The joining tool 40 comprises a shoulder portion 41 and a joining pin 42 protruding from the tip of the shoulder portion 41. Then, by pressing the joining pin 42 against the plate material 30 while rotating it, the plate material 30 is softened by frictional heat and pressed in. Subsequently, while forming a friction stir joint portion 31 between the plate material 30 and the outer surface 22 of the hollow material 20, the joining pin 42 and the plate material 30 are moved relative to each other, and the plate material 30 and the hollow material 20 are friction stir welded in a point or linear manner.

[0023] During friction stir welding, a downward pressing force is applied to the outer surfaces 22 of the plate material 30 and the hollow material 20 by the pressing force of the joining tool 40, as shown in Figure 1. However, this pressing force is supported by the pressure of the pressurized fluid P filled in the void 21. Therefore, the outer surfaces 22 of the plate material 30 and the hollow material 20 do not bend due to the pressing force of the joining tool 40, and the deformation of the hollow material 20 is suppressed. As a result, the frictional force generated between the joining tool 40 and the plate material 30 can be made large enough to form the friction stir joint 31.

[0024] As a result, even when overlapping the plate material 30 on the outer surface 22 of the region corresponding to the void 21 and friction stir welding is performed, the pressing force of the joining tool 40 can be ensured to be large enough to form the friction stir joint 31, thereby ensuring sufficient joint strength at the joint. In other words, the pressurized fluid P filled in the void 21 acts as a deformation suppression mechanism 50 that suppresses the deformation of the hollow material 20, thereby suppressing the deformation of the outer surface 22 of the hollow material 20. Furthermore, because the deformation suppression mechanism 50 is a pressurized fluid P, the same magnitude of force acts on all parts within the void 21. As a result, there is no need to select a joining position between the plate material 30 and the hollow material 20, and joining can be performed at any position, improving work efficiency.

[0025] Furthermore, after friction stir welding the plate material 30 and the hollow material 20, the friction stir welding is completed by discharging the pressurized fluid P from within the void 21 and releasing the pressing force of the pressurized fluid P.

[0026] (Second Embodiment) Figure 2 is an explanatory diagram showing a friction stir welding method for hollow materials according to a second embodiment of the present invention. The friction stir welding method according to this embodiment is a method in which, instead of the pressurized fluid P that fills the void portion 21 described in the first embodiment, a metal backing plate 51 having a desired strength is used as a deformation suppression mechanism 50, and friction stir welding is performed with the backing plate 51 inserted into the void portion 21 of the hollow material 20. In addition, the same reference numerals or equivalent numerals are used to denote parts identical to those in the first embodiment, and the explanation is simplified or omitted. The same applies to subsequent embodiments.

[0027] The thickness of the backing plate 51 is preferably approximately the same as the height of the void 21, and there is virtually no gap within the void 21, and it is especially preferable that the backing plate 51 is inserted with virtually no gap in the vertical direction. In other words, it is preferable that the backing plate 51 is inserted so as to be in contact with the inner surface 23 of the hollow material 20 with virtually no gap. However, due to the need to insert and remove the backing plate 51 from the void 21 of the hollow material 20, it is preferable that the thickness of the backing plate 51 is slightly thinner than the height of the void 21.

[0028] This ensures that the pressing force from the joining tool 40 is reliably supported by the backing plate 51, preventing deformation of the outer surface 22 of the hollow material 20 and ensuring sufficient frictional heat necessary for friction stir welding. Furthermore, since the deformation suppression mechanism 50 is the backing plate 51, it is easier to prevent deformation of the outer surface 22 of the hollow material 20 more effectively than with the pressure fluid P described in the first embodiment.

[0029] After friction stir welding of the plate material 30 and the hollow material 20, the friction stir welding is completed by removing the backing plate 51 from the gap 21.

[0030] Other aspects not mentioned above are the same as those of the friction stir welding method in the first embodiment, and therefore will not be explained.

[0031] (Third embodiment) Figure 3 is an explanatory diagram showing a friction stir welding method for hollow materials according to a third embodiment of the present invention. The friction stir welding method according to this embodiment includes a deformation suppression mechanism 50 comprising a backing plate 51, a non-metallic tube 52, and a pressurized fluid P, wherein both the backing plate 51 and the non-metallic tube 52, which is positioned below the backing plate 51, are inserted into the gap 21.

[0032] In the friction stir welding method of this embodiment, the thickness of the backing plate 51 inserted into the void 21 of the hollow material 20 is considerably smaller than the vertical dimension of the void 21. A non-metallic tube 52 is also positioned below the backing plate 51 inserted into the void 21. The non-metallic tube 52 is an inflatable tube made of a non-metallic material such as rubber or cloth. During welding, a pressurized fluid P consisting of a liquid such as water or oil, or a gas such as air, is supplied into the non-metallic tube 52, inflating the non-metallic tube 52 and pushing up the backing plate 51, thereby bringing it into close contact with the inner surface 23 of the hollow material 20 without any gaps, and the backing plate 51 supports the pressing force from the welding tool 40. This prevents deformation of the outer surface 22 of the hollow material 20 due to the pressing force of the welding tool 40, and ensures that the frictional force between the welding tool 40 and the plate material 30 is large enough to form the friction stir joint 31.

[0033] The thickness of the backing plate 51 should be such that it does not deform under the pressing force of the joining tool 40. A thinner backing plate 51 is preferable as it is easier to handle. The backing plate 51 and the non-metallic tube 52 may be independent of each other, but the backing plate 51 may be integrally fixed to the non-metallic tube 52, which offers better handling.

[0034] In the friction stir welding method of this embodiment, the backing plate 51 is pushed up by the expanding non-metallic tube 52 and comes into contact with the inner surface 23 of the hollow material 20, thereby improving the adhesion between the backing plate 51 and the inner surface 23. Furthermore, since the backing plate 51 can be made thinner and lighter compared to the case where the non-metallic tube 52 is not used, it becomes easier to install the backing plate 51 in the void 21.

[0035] Furthermore, after friction stir welding, the pressurized fluid P can be discharged from the non-metallic tube 52, allowing the backing plate 51 to be easily removed from the void 21, thereby improving work efficiency. In addition, the deformation of the non-metallic tube 52 allows for easy adaptation to even complex shapes in the void 21.

[0036] After friction stir welding the plate material 30 and the hollow material 20, the pressurized fluid P is discharged from the non-metallic tube 52 to release the pressing force of the pressurized fluid P, and the backing plate 51 and the non-metallic tube 52 are removed from the gap 21, thereby completing the friction stir welding.

[0037] Incidentally, the deformation suppression mechanism 50 described in the third embodiment included a backing plate 51, a non-metallic tube 52, and a pressurized fluid P. However, the deformation suppression mechanism 50 of the present invention does not necessarily require the use of both the backing plate 51 and the non-metallic tube 52. As long as the deformation suppression mechanism 50 can be constructed using only the non-metallic tube 52 and the pressurized fluid P, without using the backing plate 51, as long as it can suppress the bending of the outer surface 22 of the plate material 30 and the hollow material 20 by the pressing force of the joining tool 40.

[0038] Other aspects not mentioned above are the same as those of the friction stir welding method in the first embodiment, and therefore will not be explained.

[0039] (Fourth Embodiment) Figure 4 is an explanatory diagram showing a friction stir welding method for hollow materials according to the fourth embodiment of the present invention. The friction stir welding method according to this embodiment is a method that combines the welding method according to the first embodiment, in which deformation of the hollow material 20 is suppressed by filling a sealed void 21 with a pressurized fluid P consisting of a liquid such as water or oil, or a gas such as air, and the welding method according to the second embodiment, in which deformation of the hollow material 20 is suppressed by inserting a backing plate 51 into the void 21.

[0040] Specifically, a backing plate 51 having approximately the same thickness as the height of the void 21 and a width narrower than the width of the void 21 is inserted below the planned joining position within the void 21. As a result, the backing plate 51 comes into almost complete contact with the inner surface 23 of the hollow material 20. However, two voids 21 are formed on both sides of the backing plate 51 in the width direction (i.e., in the left-right direction of the paper in Figure 4).

[0041] Then, as described in the first embodiment, the openings at both longitudinal ends of the void 21 are closed with a lid member (not shown) to seal the void 21. Then, the void 21 is filled with a pressurized fluid P consisting of a liquid such as water or oil, or a gas such as air, compressed from a pressurized fluid supply mechanism (not shown). The inner surface 23 of the portion not in contact with the backing plate 51 is supported by the pressing force of the pressurized fluid P, and the portion below which is pressed by the joining tool 40 is supported by the inserted backing plate 51. This allows for more effective support of the inner surface 23 compared to the case where the inner surface 23 of the hollow material 20 is supported only by filling with pressurized fluid P. On the other hand, compared to the case where the inner surface 23 of the hollow material 20 is supported only by inserting the backing plate 51, the size of the backing plate 51 can be reduced, and the installation of the backing plate 51 into the void 21 becomes easier.

[0042] After friction stir welding the plate material 30 and the hollow material 20, the pressurized fluid P is discharged from the void 21 to release the pressing force of the pressurized fluid P, and the backing plate 51 is removed from the void 21, thereby completing the friction stir welding.

[0043] Other aspects not mentioned above are the same as those of the friction stir welding method in the first embodiment, and therefore will not be explained.

[0044] (Fifth embodiment) Figure 5 is an explanatory diagram showing a friction stir welding method for hollow materials according to the fifth embodiment of the present invention. The friction stir welding method according to this embodiment is a welding method that combines the welding method according to the third embodiment, which uses a backing plate 51, a non-metallic tube 52, and a pressurized fluid P as a deformation suppression mechanism 50, with the welding method according to the first embodiment, which further fills the void portion 21 with pressurized fluid P.

[0045] According to the friction stir welding method of this embodiment, the inner surface 23 of the void portion 21 can be effectively supported while taking advantage of the respective advantages described in each of the above embodiments, and a friction stir joint portion 31 with excellent bonding quality can be formed.

[0046] After friction stir welding the plate material 30 and the hollow material 20, the pressurized fluid P is discharged from the gap 21 to release the pressing force of the pressurized fluid P, and the pressurized fluid P is also discharged from the non-metallic tube 52 to release the pressing force of the pressurized fluid P, and the backing plate 51 and the non-metallic tube 52 are removed from the gap 21, thereby completing the friction stir welding.

[0047] Other aspects not mentioned above are the same as those of the friction stir welding method in the first embodiment, and therefore will not be explained.

[0048] It should be noted that the present invention is not limited to the embodiments described above, and can be modified, improved, etc., as appropriate. For example, the deformation suppression mechanism 50 only needs to be capable of supporting the inner surface 23 against the pressing force of the joining tool 40, and is not limited to the pressure fluid P, the backing plate 51, the non-metallic tube 52, or a combination thereof, but can also be other members or mechanisms that function as the deformation suppression mechanism 50.

[0049] As described above, the following matters are disclosed in this specification:

[0050] (1) A friction stir welding method for joining a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface, A superimposing step of superimposing the aforementioned plate material and the aforementioned hollow material, The process includes a friction stir welding step of forming a friction stir joint between the plate material and the hollow material using a rotating joining tool, A friction stir welding method comprising providing a deformation suppression mechanism for suppressing deformation of the hollow material in at least a portion of the inner surface corresponding to the region where the friction stir weld is formed, during the friction stir welding step. With this configuration, when friction stir welding is performed by overlapping a metal plate and a closed-section hollow material made of the same or different material as the plate, and having an outer surface on which the plates overlap and an inner surface on the opposite side of the outer surface, a deformation suppression mechanism for suppressing the deformation of the hollow material makes it possible to obtain a good friction stir joint.

[0051] (2) The friction stir welding method according to (1), wherein the deformation suppression mechanism is a mechanism that seals the void in the hollow material surrounded by the inner surface, fills the void with pressurized fluid, and presses the inner surface with the pressing force of the pressurized fluid. In this configuration, since the deformation suppression mechanism is a pressurized fluid, the same magnitude of force acts on all parts within the void. This eliminates the need to select a joint position between the plate material and the hollow material, allowing them to be joined at any position, thus improving work efficiency.

[0052] (3) The friction stir welding method according to (2), wherein the pressure fluid is water or air. With this configuration, inexpensive water or air can be used as the pressurized fluid.

[0053] (4) The friction stir welding method according to (2) or (3), wherein the pressing force of the pressurized fluid is released after the friction stir welding step. This configuration allows for the suppression of deformation of the hollow material during friction stir welding, while also enabling the discharge of the pressurized fluid that filled the void after the friction stir welding process.

[0054] (5) The friction stir welding method according to (1), wherein the deformation suppression mechanism is a mechanism that is inserted into the void in the hollow material surrounded by the inner surface and provides a backing plate for suppressing deformation of the hollow material. With this configuration, the deformation of the hollow material is suppressed by the backing plate inserted into the void, thereby forming a good friction stir joint.

[0055] (6) The friction stir welding method according to (5), wherein the backing plate is removed after the friction stir welding step. This configuration allows for the suppression of deformation of the hollow material during friction stir welding, while also enabling the removal of the backing plate inserted into the void after the friction stir welding process.

[0056] (7) The friction stir welding method according to (5) or (6), wherein the backing plate is inserted together with the backing plate into the void surrounded by the inner surface and is pressed by an expandable non-metallic tube containing a pressurized fluid. With this configuration, the expansion of the non-metallic tube presses the backing plate against the hollow material, thereby suppressing the deformation of the hollow material. In addition, the backing plate can be made thinner and lighter, making it easier to handle.

[0057] (8) The friction stir welding method according to (7), wherein after the friction stir welding step, the expansion of the non-metallic tube is released and the backing plate is removed. With this configuration, the backing plate can be easily removed from the gap by releasing the expansion of the non-metallic tube, improving work efficiency.

[0058] (9) The friction stir welding method according to (7) or (8), wherein the nonmetallic tube is formed of a flame-retardant material. This configuration suppresses the deterioration of the non-metallic tube due to frictional heat generated between the rotating joining tool and the plate material.

[0059] (10) The friction stir welding method according to (1), wherein the deformation suppression mechanism comprises both a mechanism that seals the void in the hollow material surrounded by the inner surface and fills the void with pressurized fluid, thereby pressing the inner surface with the pressing force of the pressurized fluid, and a mechanism that is inserted into the void in the hollow material surrounded by the inner surface and provides a backing plate for suppressing deformation of the hollow material. With this configuration, the deformation suppression mechanism formed by the pressurized fluid and backing plate can effectively prevent deformation of the void.

[0060] (11) The friction stir welding method according to (10), wherein after the friction stir welding step, the pressing force of the pressurized fluid is released and the backing plate is removed. This configuration allows for the suppression of deformation of the hollow material during friction stir welding, while also enabling the removal of the backing plate inserted into the void after the friction stir welding process.

[0061] (12) The friction stir welding method according to (10) or (11), wherein the backing plate is inserted together with the backing plate into the void surrounded by the inner surface and is pressed by an expandable non-metallic tube that contains the pressurized fluid inside. With this configuration, a deformation suppression mechanism can be formed by a non-metallic tube inserted into the gap together with the backing plate. Furthermore, by expanding the non-metallic tube, the backing plate can be brought into close contact with the inner surface of the gap.

[0062] (13) The friction stir welding method according to (12), wherein after the friction stir welding step, the expansion of the non-metallic tube is released and the backing plate is removed. With this configuration, the backing plate can be easily removed by discharging the pressurized fluid from the non-metallic tube.

[0063] (14) The friction stir welding method according to (12) or (13), wherein the nonmetallic tube is formed of a flame-retardant material. This configuration suppresses the deterioration of the non-metallic tube due to frictional heat generated between the rotating joining tool and the plate material.

[0064] (15) A superimposing mechanism for superimposing a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface, A friction stir welding mechanism that uses a rotating joining tool to form a friction stir joint between the plate material and the hollow material, A friction stir welding apparatus comprising a deformation suppression mechanism for suppressing deformation of the hollow material in at least a portion of the inner surface corresponding to the region in which the friction stir joint is formed when the friction stir joint is formed. With this configuration, when friction stir welding is performed by overlapping a metal plate and a closed-section hollow material made of the same or different material as the plate, and having an outer surface on which the plates overlap and an inner surface on the opposite side of the outer surface, a deformation suppression mechanism for suppressing the deformation of the hollow material makes it possible to obtain a good friction stir joint.

[0065] (16) The friction stir welding apparatus according to (15), wherein the deformation suppression mechanism is at least one of the following: a mechanism that seals the void in the hollow material surrounded by the inner surface, fills the void with pressurized fluid, and presses the inner surface with the pressing force of the pressurized fluid; and a mechanism that is inserted into the void in the hollow material surrounded by the inner surface and provides a backing plate for suppressing deformation of the hollow material. With this configuration, the deformation suppression mechanism that prevents deformation of the hollow material is composed of a pressurized fluid filled into the void or a backing plate inserted into the void, thereby effectively suppressing the deformation of the hollow material. [Explanation of symbols]

[0066] 20 Hollow material 21 Cavity 22 Outer surface 23 Inner surface 24 Bulkhead 30 Board material 31 Friction stir welding 40. Joining Tools (Friction Stir Welding Mechanism) 41 Shoulder section 42 connecting pins 45. Clamp (overlapping mechanism) 50 Deformation suppression mechanism 51 Backing metal 52 Non-metallic tubes P Pressure fluid

Claims

1. A friction stir welding method for joining a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface, A superimposing step of superimposing the aforementioned plate material and the aforementioned hollow material, The process includes a friction stir welding step of forming a friction stir joint between the plate material and the hollow material using a rotating joining tool, In the friction stir welding process, a deformation suppression mechanism for suppressing deformation of the hollow material is provided in at least a portion of the inner surface corresponding to the region where the friction stir welding portion is formed. The deformation suppression mechanism is a mechanism that seals the void surrounded by the inner surface of the hollow material, fills the void with pressurized fluid, and presses the inner surface with the pressing force of the pressurized fluid, in a friction stir welding method.

2. The friction stir welding method according to claim 1, wherein the pressure fluid is water or air.

3. The friction stir welding method according to claim 1 or 2, wherein the pressing force of the pressurized fluid is released after the friction stir welding step.

4. A friction stir welding method for joining a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface, A superimposing step of superimposing the aforementioned plate material and the aforementioned hollow material, The process includes a friction stir welding step of forming a friction stir joint between the plate material and the hollow material using a rotating joining tool, In the friction stir welding process, a deformation suppression mechanism for suppressing deformation of the hollow material is provided in at least a portion of the inner surface corresponding to the region where the friction stir welding portion is formed. A friction stir welding method comprising: a mechanism for sealing the void in the hollow material surrounded by the inner surface and filling the void with pressurized fluid, thereby pressing the inner surface with the pressing force of the pressurized fluid; and a mechanism for providing a backing plate that is inserted into the void in the hollow material surrounded by the inner surface and for suppressing the deformation of the hollow material.

5. The friction stir welding method according to claim 4, wherein after the friction stir welding step, the pressing force of the pressurized fluid is released and the backing plate is removed.

6. The friction stir welding method according to claim 4 or 5, wherein the backing plate is inserted together with the backing plate into the void surrounded by the inner surface and is pressed by an expandable non-metallic tube that contains the pressurized fluid.

7. The friction stir welding method according to claim 6, wherein after the friction stir welding step, the expansion of the non-metallic tube is released and the backing plate is removed.

8. The friction stir welding method according to claim 6 or 7, wherein the non-metallic tube is formed of a flame-retardant material.

9. A superimposing mechanism for superimposing a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface, A friction stir welding mechanism that uses a rotating joining tool to form a friction stir joint between the plate material and the hollow material, The system includes a deformation suppression mechanism for suppressing deformation of the hollow material in at least a portion of the inner surface corresponding to the region where the friction stir joint is formed, during the formation of the friction stir joint. The deformation suppression mechanism is a mechanism that seals the void in the hollow material surrounded by the inner surface, fills the void with pressurized fluid, and presses the inner surface with the pressing force of the pressurized fluid, in a friction stir welding apparatus.

10. A superimposing mechanism for superimposing a plate made of a metal material and a hollow material with a closed cross-section made of the same or different material as the plate, and having an outer surface on which the plate is superimposed and an inner surface which is the surface opposite to the outer surface, A friction stir welding mechanism that uses a rotating joining tool to form a friction stir joint between the plate material and the hollow material, The system includes a deformation suppression mechanism for suppressing deformation of the hollow material in at least a portion of the inner surface corresponding to the region where the friction stir joint is formed, during the formation of the friction stir joint. A friction stir welding apparatus comprising: a mechanism for sealing the void in the hollow material surrounded by the inner surface and filling the void with pressurized fluid, thereby pressing the inner surface with the pressing force of the pressurized fluid; and a mechanism for providing a backing plate that is inserted into the void in the hollow material surrounded by the inner surface and for suppressing the deformation of the hollow material.

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