JP5532888B2 - Friction stir welding method - Google Patents

Description

  The present invention relates to a friction stir welding method for metal hollow materials, particularly pipe materials.

  In recent years, friction stir welding has been developed and put to practical use as a new joining method that replaces welding and brazing as a joining method for metallic members to be joined. Friction stir welding is solid-phase bonding, and the members to be bonded can be bonded at a lower temperature than welding (melting bonding) or brazing (liquid-solid reaction bonding). There are advantages such as less bonding failure due to

  In this friction stir welding, a cylindrical joining tool called a tool is pressed against a member to be joined while rotating at a high speed, and the joining member is joined by plastic flow using the frictional heat between the joining tool and the member to be joined. It is a joining method. The joining tool includes a cylindrical rotor having a large outer diameter, and a projection having a small outer diameter called a probe formed on the tip surface of the rotor. The rotor and the protrusion are coaxial. When performing the joining, the joining tool is pressed along the joining member with the tip surface of a rotor called a shoulder against the joining member, and is moved along the abutting surface. The member to be joined is softened by frictional heat between the joining tool and the member to be joined, and is agitated and joined by the probe.

  By the way, the friction stir welding is a joining method in which a joining tool is pressed against a member to be joined with a large force (hereinafter referred to as “tool load”). For example, in the case of a so-called 6000 series aluminum alloy (Al-Mg-Si series alloy), the tool load is about 3 kN to about 10 kN.

  Because of this tool load, friction stir welding deforms the butt when joining a hollow member to be joined, so that good joining cannot be obtained or the dimensional accuracy of the joined product cannot be obtained. There is a problem.

  Therefore, a friction stir welding method is known in which a hollow portion of a member to be joined is filled with a core to prevent deformation of the butt portion due to a tool load (see, for example, Patent Document 1).

  In addition, a friction stir welding method is known in which a rib for closing an opening of a hollow member to be joined is provided to suppress deformation of a butt portion due to a tool load (see, for example, Patent Document 2).

  Furthermore, the sleeve that has a hole into which the welding tool can be inserted is covered with the butt portion of the cylindrical member to be joined, and the sleeve is rotated following the movement of the welding tool to suppress the deformation of the butt portion due to the tool load. Stir welding methods are known (see, for example, Patent Document 3).

JP-A-10-76375 JP 2000-681 A JP 2001-191183 A

  In the friction stir welding method described in Patent Document 1, since the core is packed in the hollow portion of the member to be joined, an increase in the weight of the joined product is inevitable.

  Moreover, since the friction stir welding method described in Patent Document 2 has a rib that closes the opening of a hollow member to be joined, the moldability of the member to be joined is impaired. For example, when casting a curved tubular member to be joined, it may be difficult to remove the core.

  Furthermore, since the friction stir welding method described in Patent Document 3 rotates the sleeve that suppresses deformation of the member to be joined, there is no degree of freedom in the cross-sectional shape in the direction perpendicular to the axis of the member to be joined (need to be circular). .) That is, this method cannot join a member to be joined having a polygonal cross-sectional shape in the direction perpendicular to the axis.

  Accordingly, the present invention proposes a friction stir welding method that can suppress deformation due to a tool load without impairing the moldability of a hollow member to be joined and that has good joining strength and joining quality.

In order to solve the above-mentioned problem, the friction stir welding method according to the present invention includes at least one flat first face plate formed in a closed cross-section hollow shape and a protruding piece formed at an inner end portion of the first face plate. A first metal member to be bonded, at least one flat plate-like second face plate formed in a closed cross-sectional hollow shape, and a recess that is disposed in the hollow portion so as to face the second face plate and into which the protruding piece can be inserted. A step of preparing a second metal member to be joined having an inner projecting piece to form the end face of the first face plate and the end face of the second face plate facing each other in the recess. A step of fitting a projecting piece to abut the end face of the first face plate and the end face of the second face plate to form a joining scheduled portion, and performing friction stir welding along the joining scheduled portion, the first joined member and the second A step of joining to a member to be joined, That.

  ADVANTAGE OF THE INVENTION According to this invention, the deformation | transformation by a tool load can be suppressed without impairing the moldability of a hollow to-be-joined member, and the friction stir welding method with favorable joining strength and joining quality can be provided.

The flowchart which showed the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially an example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially an example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially the other example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially the other example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially the other example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially the other example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially the other example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially the other example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Schematic which showed the friction stir welding process of the friction stir welding method which concerns on embodiment of this invention. The perspective view which showed an example of the structure joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially an example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Sectional drawing which showed partially an example of the to-be-joined member joined by the friction stir welding method which concerns on embodiment of this invention. Schematic which showed the mode of the strength test of the structure joined by the friction stir welding method which concerns on embodiment of this invention. The figure which showed an example of the joining strength of the structure joined by the friction stir welding method which concerns on embodiment of this invention.

  Hereinafter, an embodiment of a friction stir welding method according to the present invention will be described with reference to FIGS.

  FIG. 1 is a flowchart showing a friction stir welding method according to an embodiment of the present invention.

  As shown in FIG. 1, the friction stir welding method according to the present embodiment includes a preparation step S1, a butting step S2, and a friction stir welding step S3.

  The preparation step S1 is a step of preparing a pair of members to be joined to be joined by the friction stir welding method according to the present embodiment.

  The butting step S2 is a step of butting a pair of members to be joined to be joined by the friction stir welding method according to the present embodiment to form a joining scheduled portion. Each member to be joined is a metal hollow member containing, for example, an aluminum alloy, and may be any member that can be joined by friction stir welding. The part to be joined is constituted by a joint part in which each member to be joined comes into contact with each other. Specifically, the joining planned portion is a butt joint and a lap joint constituted by a pair of members to be joined, and is a region joined in the friction stir welding step S3.

  The friction stir welding step S3 is a step of obtaining a structure in which the joining tool is moved along the planned joining portion and the members to be joined are finally joined by friction stirring.

  Note that the friction stir welding method according to the present embodiment is a non-planar shape such as a curved portion, a corner portion, a stepped portion, or the like, which is difficult to join by friction stir welding among the joint portions where the members to be joined contact each other. The parts can be joined by welding. As a welding method, a known welding method such as arc welding using an arc as a heat source (including gas shielded arc welding including TIG welding and MIG welding, self-shielded arc welding, etc.), gas welding, laser welding, and electron beam welding is used. It is possible.

  Next, the to-be-joined member prepared in preparation process S1 is demonstrated.

  2 and 3 are cross-sectional views partially showing an example of members to be joined that are joined by the friction stir welding method according to the embodiment of the present invention. 2 is a view showing a cross section in the longitudinal axis direction of the member to be joined, and FIG. 3 is a view showing a cross section in the direction perpendicular to the longitudinal axis of the member to be joined.

  As shown in FIGS. 2 and 3, the member 3 (first member to be joined) and the member 4 (second member to be joined) joined by friction stir welding according to the present embodiment are made of metal. It is a hollow member. Specifically, the member 3 and the member 4 to be joined may be straight pipes or curved pipes.

  The member 3 to be joined includes at least one flat face plate 5 (first face plate) and a protruding piece 7 formed at the inner end of the face plate 5.

  The protruding piece 7 extends substantially parallel to the face plate 5. Further, the protruding piece 7 is formed integrally with the face plate 5. Note that the protruding piece 7 may be formed of another member that is integrally fixed to the face plate 5.

  On the other hand, the member 4 to be joined has at least one flat face plate 8 (second face plate) and a recess 12 which is disposed in the hollow portion 10 so as to face the face plate 8 and into which the protruding piece 7 can be fitted together. And a protruding piece support piece 14 to be formed.

  The protruding piece support piece 14 is a pair of cylindrical column-shaped or rectangular column-shaped protrusions such as a quadrangular column protruding from the inner surface of the face plate 16 adjacent to the face plate 8 to face each other. Further, the protruding piece support piece 14 extends substantially parallel to the face plate 8. The protruding piece support piece 14 is formed integrally with the face plate 16. The protruding piece support piece 14 may be formed of a separate member that is integrally fixed to the face plate 16.

  More specifically, the member to be joined 3 is a tube having a square cross section, and is formed of four flat face plates 5a and 5b, face plates 19a and 19b surrounding the hollow portion 17, and protrusions formed at the inner end of the face plate 5a. A piece 7a and a protruding piece 7b formed at the inner end of the face plate 5b are provided. The face plate 5a and the face plate 5b are arranged to face each other. The face plate 19a and the face plate 19b are also arranged to face each other.

  On the other hand, the member 4 to be joined is a tube having a square cross section corresponding to the member 3 to be joined, and is opposed to the four flat face plates 8a and 8b, the face plates 16a and 16b surrounding the hollow portion 10, and the face plate 8a. And a projecting piece support piece 14a that forms a recess 12a into which the projecting piece 7a can be fitted together with the face plate 8a and a face plate 8b. And a protruding piece support piece 14b that forms a recess 12b into which can be inserted.

  The to-be-joined member 3 and the to-be-joined member 4 have the protruding piece 7 fitted into the recess 12 in the butting step S2, and the end surface 21 of the face plate 5 and the end surface 22 of the face plate 8 are butted together. The abutting surface between the end face 21 of the face plate 5 and the end face 22 of the face plate 8 is a joint joining portion 23 to be joined in the friction stir welding step S3.

  With such a structure, the member to be bonded 3 and the member to be bonded 4 have the protruding pieces 7 supported at both ends on the inner surface side of the face plate 8, so that the planned bonding portion 23 has high rigidity. The inner surfaces of the face plate 5 a and the face plate 8 are surfaces on the hollow portion side of the members 3 and 4 to be joined, and the outer surfaces of the face plate 5 and the face plate 8 are the faces of the members 3 and 4 to be joined. The outer surface.

  The face plate 8 includes a thick portion 24 at an inner end corresponding to the vicinity of the opening of the hollow portion 10. The thick part 24 is provided as a reinforcement when the softest part in the friction stir welding occurs around the stirring part. The plate thickness tc of the thick portion 24 has a thickness not more than twice the plate thickness t2 of the general portion of the face plate 8.

  The plate thickness te of the protruding piece 7 is preferably configured to be thicker than the thinner one of the plate thickness t1 of the face plate 5 or the plate thickness t2 of the face plate 8. The width W of the protruding piece 7 is preferably configured to be wider than the feed amount L of the welding tool 26 in the friction stir welding step S3. By configuring in this way, the protruding piece 7 reliably improves the rigidity of the joining planned portion 23 with respect to the tool load.

  The member to be bonded 3 and the member to be bonded 4 configured in this manner greatly reduce the deformation of the face plate 5 and the face plate 8 due to the tool load.

  4 and 5 are cross-sectional views partially showing another example of members to be joined that are joined by the friction stir welding method according to the embodiment of the present invention. 4 is a diagram showing a cross section in the longitudinal axis direction of the member to be joined, and FIG. 5 is a diagram showing a cross section in the direction perpendicular to the longitudinal axis of the member to be joined.

  As shown in FIGS. 4 and 5, the member 3 to be joined and the member 4A (second member to be joined) joined by the friction stir welding according to the present embodiment are metal hollow members.

  In addition, about the to-be-joined member 4A, the same code | symbol is attached | subjected to the same structure as the to-be-joined member 4, and the overlapping description is abbreviate | omitted.

  On the other hand, the member to be joined 4A has at least one flat face plate 8 (second face plate) and a recess 12A that is disposed in the hollow portion 10 so as to face the face plate 8 and into which the protruding piece 7 can be fitted together with the face plate 8. 14 A of protruding piece support pieces to form.

  More specifically, the member to be joined 4A is a tube having a rectangular cross section corresponding to the member to be joined 3, and includes four flat face plates 8a and 8b, face plates 16a and 16b, and face plate 8a surrounding the hollow portion 10. A projecting piece support piece 14Aa that forms a recess 12Aa into which the projecting piece 7 can be fitted together with the face plate 8a and is arranged in the hollow portion 10 so as to face each other, and is arranged in the hollow portion 10 so as to face the face plate 8b and projects together with the face plate 8b. And a protruding piece support piece 14Ab that forms a recess 12Ab into which the piece 7b can be inserted.

  The protruding piece support piece 14A is formed so as to protrude from the inner surface of the face plate 8, and has an L-shaped cross section whose tip is directed in the opening direction of the bonded member 4A. The L-shaped tip portion of the protruding piece support piece 14 </ b> A extends substantially parallel to the face plate 8. Further, the protruding piece support piece 14 </ b> A is formed integrally with the face plate 8. Note that the protruding piece support piece 14 </ b> A may be formed of another member that is integrally fixed to the face plate 8.

  The member 3 to be joined and the member 4A to be joined thus configured greatly reduce deformation of the face plate 5 and the face plate 8 due to the tool load.

  6 and 7 are cross-sectional views partially showing another example of the members to be joined that are joined by the friction stir welding method according to the embodiment of the present invention. 6 is a view showing a cross section in the longitudinal axis direction of the member to be joined, and FIG. 7 is a view showing a cross section in the direction perpendicular to the longitudinal axis of the member to be joined.

  As shown in FIGS. 6 and 7, the member to be joined 3A (first member to be joined) and the member to be joined 4 to be joined by friction stir welding according to the present embodiment are metal hollow members.

  In addition, about the to-be-joined member 3A, the same code | symbol is attached | subjected to the same structure as the to-be-joined member 3, and the overlapping description is abbreviate | omitted.

  The joined member 3 </ b> A includes at least one flat face plate 5 (first face plate) and a protruding piece 7 </ b> A formed at the inner end of the face plate 5.

  The protruding piece 7 </ b> A extends substantially parallel to the face plate 5. Further, the projecting piece 7A includes a bulging portion 27 projecting toward the hollow portion 17 side. Further, the protruding piece 7 </ b> A is formed integrally with the face plate 5. The protruding piece 7 </ b> A may be formed of another member that is integrally fixed to the face plate 5.

  When the protruding piece 7 </ b> A is fitted into the recess 12, the bulging portion 27 is sandwiched by the protruding piece support piece 14 constituted by a pair of protrusions that protrude from the inner surface of the face plate 8 to face each other. As a result, the member 3A to be joined and the member 4 to be joined are reliably positioned in the direction orthogonal to the longitudinal axis, and the abutting surfaces may also be shifted by the joining tool 26 that moves the planned joining portion 23 during friction stir welding. Absent.

  8 and 9 are cross-sectional views partially showing another example of members to be joined that are joined by the friction stir welding method according to the embodiment of the present invention. 8 is a diagram showing a cross section in the longitudinal axis direction of the member to be joined, and FIG. 9 is a diagram showing a cross section in the direction perpendicular to the longitudinal axis of the member to be joined.

  As shown in FIGS. 8 and 9, the member 3B (first member to be joined) and the member 4B (second member to be joined) joined by friction stir welding according to the present embodiment are made of metal. It is a hollow member.

  In addition, about the to-be-joined member 3B and the to-be-joined member 4B, the same code | symbol is attached | subjected to the same structure as the to-be-joined member 3 and the to-be-joined member 4, and the overlapping description is abbreviate | omitted.

  The to-be-joined member 3B and the to-be-joined member 4B have the protruding piece 7 fitted in the recess 12 in the butting step S2, and the end surface 21 of the face plate 5 and the end surface 22 of the face plate 8 are butted together. At this time, a portion where the projecting piece 7 and the face plate 8 overlap is a planned joining portion 23B to be joined in the friction stir welding step S3.

  With such a structure, the member to be bonded 3B and the member to be bonded 4B have the protruding pieces 7 supported at both ends on the inner surface side of the face plate 8, and therefore, the planned bonding portion 23B has high rigidity.

  The member to be bonded 3B and the member to be bonded 4B configured in this manner greatly reduce the deformation of the face plate 5 and the face plate 8 due to the tool load.

  The members 3 and 4 to be joined, the members to be joined 3 and 4A, the members to be joined 3A and 4 and the members to be joined 3B and 4B are provided with the protruding pieces 7 on the face plates 19a and 19b, and the protruding pieces are also supported on the face plates 16a and 16b. A piece 14 can also be provided. In particular, the members to be joined 3 and 4A can improve the rigidity over substantially the entire width of each face plate, and can improve the joining strength and quality of friction stir welding.

  Next, the friction stir welding step S3 will be described in detail.

  FIG. 10 is a schematic view showing a friction stir welding step of the friction stir welding method according to the embodiment of the present invention.

  FIG. 11 is a perspective view showing an example of a structure joined by the friction stir welding method according to the embodiment of the present invention.

  As shown in FIGS. 10 and 11, the friction stir welding step S <b> 3 of the friction stir welding method is a step of obtaining a structure 28 in which the planned joining portions 23 of the members 3 and 4 are joined.

  In addition, in the friction stir welding step S3, the members to be joined 3, 4A, the members to be joined 3A, 4 and the members to be joined 23B of the members to be joined 3B and 4B are joined in addition to the members 3 and 4 to be joined. You can also.

  The welding tool 26 used in the friction stir welding step S3 is formed integrally with, for example, a cylindrical rotary body 31 coupled to a drive unit of a rotary drive device (not shown), and protruding from the tip of the rotary body 31. And a cylindrical probe 32. The end face of the rotating body 31 is called a shoulder 33. The probe 32 has a length corresponding to the thickness of the portion to be joined 23 of the joined members 3 and 4 from the shoulder 33 of the rotating body 31 (that is, the face plate 5 of the joined member 3 or the face plate 8 of the joined member 4). Protruding. In addition, the probe 32 is provided with a thread groove or the like so as to efficiently stir the portion to be joined 23, or the cross-sectional shape in the direction perpendicular to the rotation axis is formed in a non-circular shape (for example, an ellipse or a drum shape). .

  In the friction stir welding step S3, the welding tool 26 is pressed against the planned joining portion 23 while rotating the welding tool 26 at a high speed (indicated by a solid arrow R in FIG. 10) by the rotation driving device, and the friction between the welding tool 26 and the members 3 and 4 to be joined is pressed. The joining portion 23 is softened by heat, and the softened portion is stirred and plastically flowed by the rotation of the joining tool 26 to manufacture the structure 28 in which the members 3 and 4 are integrated at the joining portion 34.

  Next, specific examples of the friction stir welding method will be described in detail.

  12 and 13 are cross-sectional views partially showing an example of members to be joined that are joined by the friction stir welding method according to the embodiment of the present invention. 12 is a diagram showing a cross section in the longitudinal axis direction of the member to be joined, and FIG. 13 is a diagram showing a cross section in the direction perpendicular to the longitudinal axis of the member to be joined.

  The joining pipe 35 as a structure is composed of the joined members 3 and 4 which are square pipes having a width of about 40 mm, a height of about 100 mm, and a plate thickness of about 4 mm made of an aluminum alloy (JIS H 5202: AC4CH-T6). It is the structure joined by the joining method concerning an embodiment.

  The member 3 to be joined includes a protruding piece 7 having a shape dimension of a plate thickness te = about 4 mm, a width W = about 24 mm, and a protruding distance L = about 16 mm from the abutting surface.

  The member 4 to be joined includes a protruding piece support piece 14 in which a round bar made of an aluminum alloy (JIS H 4100: 6061-T6) having a diameter R = about 8 mm is press-fitted into a hole drilled in the face plate 16. The protruding piece support piece 14 has a projecting amount S of about 10 mm from the inner surface of the face plate 16, a distance D of the recess 12 of about 4 mm, and a distance of about 12 mm from the butted surface to the center of the round bar.

  The welding tool 26 used in the friction stir welding step S3 has a shape in which the diameter of the shoulder 33 is about 12 mm, the diameter of the probe 32 is about 5 mm, and the protruding length of the probe 32 is about 3.5 mm. The joining conditions of the friction stir welding step S3 are: the rotational speed of the joining tool 26 is about 1500 rpm, the joining speed of the joining tool 26 is about 300 mm / min, the advance angle of the joining tool 26 is about 3 °, and the insertion amount of the probe 32 with respect to the member to be joined is about 3.7 mm, a waiting time of about 2 seconds from when the joining tool 26 is inserted into the member to be joined to when the joining tool 26 starts to move, and after the movement of the joining tool 26 is completed, the joining tool 26 is removed from the member to be joined. The waiting time until drawing was about 1 second, and the tool load was about 3 kN.

  The joining strength of this joining pipe 35 will be described. In order to evaluate the strength of the joining pipe 35, a comparative structure (not shown) in which the joined member not provided with the protruding piece support piece 14 and the joined member 3 were joined was manufactured. Since this comparative structure does not include the protruding piece support piece 14, the protruding piece 7 is inserted into the member 4 to be joined in a cantilever state.

  FIG. 14 is a schematic view showing a state of a strength test of a structure joined by the friction stir welding method according to the embodiment of the present invention.

  As shown in FIG. 14, in order to evaluate the joint strength of the joint pipe 35, a three-point bending test was performed on the joint pipe 35 and the comparative structure. The joint strength to be evaluated is the bending strength at break in the three-point bending test of the joint pipe 35 and the comparative structure.

  In addition, the load in the three-point bending test was applied in a direction in which a tensile force is generated in the joint portion 34 by friction stir welding.

  FIG. 15 is a diagram illustrating an example of the bonding strength of the structures bonded by the friction stir welding method according to the embodiment of the present invention.

  As shown in FIG. 15, the bonding strength of the bonding pipe 35 was about 1.4 times that of the comparative structure. From this result, it can be seen that the joining pipe 35 has sufficient rigidity at the joining portion by the friction stir welding, so that deformation due to the tool load in the friction stir welding is suppressed, and joining with high joining strength can be obtained.

  In the friction stir welding according to the present embodiment configured as described above, the rigidity of the planned joining portion 23 is increased by the protruding piece 7 of the member 3 to be bonded and the protruding piece support piece 14 of the member 4 to be bonded, and the tool in the friction stir welding Since the deformation of the face plate 5 due to the load can be suppressed, sufficient bonding strength and bonding quality can be obtained at the bonded portion of the bonded structure.

  In the friction stir welding according to the present embodiment, the cores are packed in the hollow portions 10 and 17 of the members 3 and 4 to be joined, the members 3A and 4 to be joined, the members 3 and 4A to be joined, and the members 3B and 4B to be joined. Since there is no necessity and it does not have the rib which plugs the hollow parts 10 and 17, the joined structure can be reduced in weight.

  Furthermore, since the friction stir welding according to the present embodiment does not have ribs that block the hollow portions 10 and 17, the members 3 and 4, the members 3A and 4 to be joined, the members 3 and 4A, and the members 3B to be joined. 4B can be easily formed.

  Furthermore, in the friction stir welding according to the present embodiment, the members 3 and 4 to be joined, the members 3A and 4 to be joined, the members to be joined 3 and 4A, and the members to be joined 3B and 4B have a cross-sectional shape perpendicular to the axis. Can be easily joined.

  In addition, the structure joined by the friction stir welding method according to the embodiment is not limited to the joining pipe 35, and is a hollow extruded material, a square pipe material, various frame materials, a press-formed product, a cast product, a forged product, and a sintered product. The present invention can also be applied when joining members to be joined such as, and is particularly suitable for joining hollow members constituting a vehicle body frame of a motorcycle.

  Therefore, according to the friction stir welding method according to this embodiment, the moldability of the hollow members 3 and 4, the members 3 </ b> A and 4, the members 3 and 4 </ b> A, and the members 3 </ b> B and 4 </ b> B is impaired. Therefore, deformation due to the tool load can be suppressed, and the bonding strength and the bonding quality can be kept good.

3, 3A, 3B Joined member 4, 4A, 4B Joined member 5, 5a, 5b Face plate 7, 7a, 7b, 7A Protruding piece 8, 8a, 8b Face plate 10 Hollow portion 12, 12a, 12b, 12A Recess 14 , 14a, 14b, 14A Projection piece support pieces 16, 16a, 16b Face plate 17 Hollow part 19a, 19b Face plate 21 End face 22 End face 23, 23B Planned joining part 24 Thick part 26 Joining tool 27 Swelling part 28 Structure 31 Rotating body 32 Probe 33 Shoulder 34 Joint part 35 Joint pipe

Claims (9)

A first workpieces made of metal having a closed cross-sectional hollow shape formed at least one of a flat first surface plate and the first surface plate projecting pieces formed at the inner end of, formed in closed cross hollow And a second metal-to-be-joined member having at least one flat plate-like second face plate and an inner projecting piece which is disposed in the hollow portion so as to face the second face plate and forms a recess into which the projecting piece can be fitted. And a step of preparing
From the state in which the end face of the first face plate and the end face of the second face plate face each other, the projecting piece is fitted into the recess, and the end face of the first face plate and the end face of the second face plate are brought into contact with each other to form a joining portion. Comprising the steps of:
Friction stir welding method characterized by having the steps of bonding the first members to be joined and the second workpieces perform friction stir welding along the predetermined joining portion. The friction stir welding method according to claim 1, wherein the protruding piece extends substantially parallel to the first face plate. The friction stir welding method according to claim 1, wherein the inner protruding piece extends substantially parallel to the second face plate. The friction stir welding method according to any one of claims 1 to 3, wherein the inner protruding piece is provided on an inner surface of the second face plate. The second member to be joined has a polygonal closed cross section having a face plate adjacent to the second face plate,
The friction stir welding method according to any one of claims 1 to 3, wherein the inner protruding piece is provided on an inner surface of the face plate . 6. The friction stir welding method according to claim 5, wherein the inner protruding piece is formed integrally with the second member to be joined. 6. The friction stir welding method according to claim 5, wherein the inner projecting piece is formed of a separate member integrally fixed to the second member to be joined. The friction stir welding method according to any one of claims 1 to 7, wherein the friction stir welding is performed on a butt surface between an end face of the first face plate and an end face of the second face plate. The friction stir welding method according to any one of claims 1 to 7, wherein the friction stir welding is performed at a portion where the second face plate and the protruding piece overlap each other.

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