JP2020032426A - Junction structure - Google Patents

Abstract

To provide a junction structure capable of suppressing separation of a junction caused by stress concentration.SOLUTION: A junction structure 1 includes a first metallic component 2 including a first joint area 2d, a second metallic component 3 including a second joint area 3d facing the first joint area 2d in a first direction, a junction 5 formed by friction stir welding of the first joint area 2d and the second joint area 3d, and an unjoined part 6 formed on an end of the junction 5. The unjoined part 6 is provided with a stress relief recess 8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bonding structure, and more particularly to a bonding structure including a first metal member including a first bonding surface and a second metal member including a second bonding surface facing the first bonding surface.

  2. Description of the Related Art Conventionally, a joint structure including a first metal member including a first joint surface and a second metal member including a second joint surface facing the first joint surface is known (for example, see Patent Document 1).

  Patent Literature 1 discloses a joining structure including a plate (hereinafter, a first plate) including an end surface (hereinafter, a first end) and a plate (hereinafter, a second plate) including an end (hereinafter, a second end). Is disclosed. Here, in the above-described joining structure, the abutting surfaces in a state where the first end face and the second end face abut each other are friction stir welded using a rotary tool (welding tool). The joining tool includes a small-diameter portion that is inserted into the butting surface from above to below, and a large-diameter portion that rotates the small-diameter portion.

  In the joining structure of Patent Document 1, the first plate and the second plate are fixed to the bed in a state where the first end surface of the first plate and the second end surface of the second plate abut against each other. In this joining structure, the small-diameter portion of the joining tool is inserted into a butt surface between the first end face and the second end face. And in a joining structure, a joining tool is moved along a horizontal direction. At this time, the joining tool is moved along the horizontal direction with the lower end of the small-diameter portion disposed above the lower end of the butting surface so that the first plate and the second plate do not join to the bed. You.

  Thus, in the joint structure of Patent Document 1, in the abutting surface between the first plate material and the second plate material, a portion slightly above the lower end of the abutting surface becomes an unjoined portion, and the upper end portion of the unjoined portion. The portion above is the joint. Here, the unjoined portion has a notch shape extending downward from the joined portion.

Japanese Patent No. 4723081

  However, in the joining structure of Patent Document 1, when a load is applied to the joining portion, stress concentration occurs in the not-joined portion having the notch shape. For this reason, there is a problem that a joint portion between the first plate material and the second plate material including the abutting surface may be separated due to a concentration of stress generated in an unjoined portion.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a bonding structure capable of suppressing separation of a bonding portion due to stress concentration. To provide.

  In order to achieve the above object, a bonding structure according to one aspect of the present invention includes a first metal member including a first bonding surface and a second metal member including a second bonding surface opposed to the first bonding surface in a first direction. A metal member, a joining portion in which the first joining surface and the second joining surface are friction stir joined, and an unjoined portion formed at an end of the joined portion, wherein the unjoined portion has a stress relief recess. Is provided.

  In the joint structure according to one aspect of the present invention, as described above, the non-joined portion is provided with the stress relief concave portion. This makes it possible to alleviate a sudden increase in stress occurring in the unjoined portion, as compared with the case where the unjoined portion has a notched shape, thereby reducing the stress concentration occurring in the unjoined portion when a load is applied to the joined structure. Can be suppressed. As a result, it is possible to prevent the joint between the first metal member and the second metal member from being separated due to the concentration of stress generated in the unjoined portion.

  In the joint structure according to the one aspect, preferably, the stress relief recess extends in a third direction orthogonal to the first direction and a second direction in which the joined portion and the unjoined portion are adjacent to each other. It is formed in a groove shape.

  With this configuration, by providing the groove-shaped stress relief recess extending in the third direction in the unjoined portion, the concentration of stress generated in the unjoined portion when a load is applied to the joined structure is suppressed over a wider range. can do. As a result, it is possible to more reliably prevent the joint between the first metal member and the second metal member from being separated due to the concentration of stress generated in the unjoined portion.

  In the bonding structure according to the one aspect, the corner of the inner bottom of the stress relief concave portion is preferably formed in a rounded shape.

  According to this structure, when a load is applied to the first metal member and the second metal member due to the rounded corners of the inner bottom of the stress relief recess, a sharp increase in stress applied to the unjoined portion is achieved. Can be further alleviated. Thereby, the concentration of stress generated in the unjoined portion can be further suppressed.

  In the bonding structure according to the one aspect, the stress relief concave portion is preferably disposed at a position shifted in a first direction from a boundary surface between the first bonding surface and the second bonding surface.

  According to this structure, by shifting the stress relief recesses in the first direction, a portion where stress concentration occurs in the direction in which the stress relief recesses are displaced is smaller than when the stress relief recesses are arranged on the boundary surface. Can be shifted. Accordingly, when a load is applied to the first metal member and the second metal member, even if a crack occurs along the boundary surface at the joint, no stress concentration occurs along the boundary surface. It is possible to make it difficult for the along crack to progress to a portion other than the joint.

  In the joint structure according to the one aspect, the stress relief concave portion is preferably provided on an inner surface of the box-shaped joint structure.

  According to this structure, the box-shaped joint structure is formed by simply performing friction stir welding on the outer surface of the joint structure opposite to the inner surface of the box-shaped joint structure provided with the stress relief concave portion. Can be formed, so that a box-shaped joint structure can be easily formed.

  In the present application, the following configuration is also conceivable in the joint structure according to the above aspect.

(Appendix 1)
That is, in the bonding structure according to the above one aspect, the unbonded portion is provided with a concave stepped portion provided so as to be depressed to one side in the first direction from the end of the first bonding surface, and the unbonded portion is formed from the end of the second bonding surface. A convex relief portion provided so as to protrude to one side in one direction, and the stress relief concave portion is formed between the concave convex portion and the convex convex portion.

  According to this structure, since the first metal member and the second metal member can be aligned only by adjusting the convex step to the concave step, the assembly of the joint structure can be facilitated. it can.

FIG. 4 is a perspective view showing a state where the first metal member and the second metal member of the bonding structure according to the first embodiment are friction stir welded. It is a perspective view of the 1st metal member of the joining structure by a 1st embodiment. FIG. 3 is a perspective view of a second metal member of the joint structure according to the first embodiment. FIG. 4 is a schematic diagram illustrating a method of joining a first metal member and a second metal member using a rotating tool in the joining structure according to the first embodiment. It is a perspective view of the box-shaped joining structure formed by the joining structure by 1st Embodiment. It is the elements on larger scale which showed the Z section of FIG. It is the elements on larger scale which showed the part equivalent to Z part of FIG. 5 of the joining structure by 2nd Embodiment. It is the elements on larger scale which showed the part equivalent to the Z part of FIG. 5 of the joining structure by the 1st modification. It is a front view of the box-shaped joining structure formed by the joining structure by the 2nd modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
First, the configuration of the joint structure 1 according to the first embodiment will be described with reference to FIGS. As shown in FIG. 1, the joining structure 1 is configured to join portions where metal members are joined by friction stir welding.

  Specifically, the joining structure 1 is configured such that the first metal member 2 including the first joining surface 2d faces the first joining surface 2d in the X direction (an example of the “first direction” in the claims). And a second metal member 3 including two joining surfaces 3d. The first metal member 2 and the second metal member 3 are joined using a rotating tool 4. The joining structure 1 includes a joining portion 5 in which the first joining surface 2d and the second joining surface 3d are friction stir joined, and an unjoined portion 6 formed at an end of the joining portion 5. The joining portion 5 and the unjoined portion 6 are formed by joining using the rotating tool 4.

  As described above, the direction in which the first bonding surface 2d and the second bonding surface 3d face each other is defined as the X direction, and the direction in which the bonding portion 5 and the unbonded portion 6 are adjacent to each other is defined as the Y direction. A direction orthogonal to the X direction and the Y direction is defined as a Z direction (an example of a “third direction” in the claims). One side in the X direction is defined as an X1 direction, and the other side is defined as an X2 direction. Similarly, one side in the Y direction is defined as a Y1 direction, and the other side is defined as a Y2 direction. One side in the Z direction is the Z1 direction, and the other side is the Z2 direction.

  The first metal member 2 shown in FIG. 2 is formed of a metal member such as aluminum, copper, or titanium. Further, the first metal member 2 is formed in a three-dimensional shape in which a concave portion is formed in a polyhedron (a rectangular body). That is, the first metal member 2 includes the first member main body 2a and the first concave portion 2c formed by depressing a plane on the X1 direction side (hereinafter, the first plane 2b) of the first member main body 2a in the X1 direction side. In. Here, the portion other than the first concave portion 2c in the first plane 2b is the above-described first joint surface 2d.

  The first recess 2 c has a groove 21 and a step 22. The first recess 2c is formed in a step shape by the groove 21 and the step 22. The step 22 is formed continuously from the end of the groove 21 on the X2 direction side.

  The groove 21 is formed by recessing the first plane 2b in the X1 direction by a first predetermined distance D1. That is, the groove portion 21 is formed in a concave shape depressed in the X1 direction side. The groove 21 is formed in a rectangular shape when viewed from the Z1 direction side.

  The step portion 22 is formed in a C-shape when viewed from the X2 direction side. The step portion 22 recesses the first plane 2b in the X1 direction by the second predetermined distance D2. That is, the step part 22 is formed in a concave shape depressed in the X1 direction side. One side of the direction orthogonal to the X direction is defined as a longitudinal direction, and the other side is defined as a short direction. In the longitudinal direction, the step 22 has a third predetermined distance D3. In the short direction, the inner surface 23 of the step 22 is disposed at a position shifted by a fourth predetermined distance D4 from the inner surface 24 of the groove 21. Hereinafter, the step portion 22 will be described in more detail.

  The step portion 22 includes a first step portion 22a formed on the inner surface 24a on the Y1 direction side of the groove portion 21, a second step portion 22b formed on an inner surface 24b on the Y2 direction side of the groove portion 21, and a groove portion. 21 has a third step-like portion 22c formed on the inner side surface 24c on the Z2 direction side. The first stepped portion 22a, the second stepped portion 22b, and the third stepped portion 22c are each formed in substantially the same shape.

  Specifically, the first stepped portion 22a has a second predetermined distance D2 in the X direction, a third predetermined distance D3 in the Z direction (longitudinal direction), and a fourth predetermined distance D3 in the Y direction (short direction). It has a predetermined distance D4. The second step portion 22b has a length of the second predetermined distance D2 in the X direction, has a third predetermined distance D3 in the Z direction (longitudinal direction), and has a fourth predetermined distance D3 in the Y direction (short direction). It has a distance D4. The third step portion 22c has a length of a second predetermined distance D2 in the X direction, has a third predetermined distance D3 in the Y direction (longitudinal direction), and has a fourth predetermined distance in the Z direction (short direction). It has a distance D4.

  The second metal member 3 shown in FIG. 3 is formed of a metal member such as aluminum, copper, or titanium. Further, the second metal member 3 is formed in a three-dimensional shape in which a concave portion is formed in a polyhedron (a rectangular body). That is, the second metal member 3 includes the second member main body 3a and the second concave portion 3c formed by depressing the plane on the X1 direction side (hereinafter, the second plane 3b) of the second member main body 3a in the X2 direction side. In. Here, the portion other than the second concave portion 3c in the second plane 3b is the above-described second joint surface 3d.

  The second recess 3 c has a groove 31 and a step 32. That is, the second concave portion 3c is formed in a step shape by the groove portion 31 and the step portion 32. The step 32 is formed continuously from the end of the groove 31 on the X1 direction side.

  The groove 31 is formed by recessing the second plane 3b in the X2 direction by the first predetermined distance D1. That is, the groove portion 31 is formed in a concave shape depressed in the X2 direction side. The groove 31 is formed in a rectangular shape when viewed from the Z1 direction side.

  The step portion 32 is formed in a C-shape when viewed from the X1 direction side. The step 32 depresses the second plane 3b in the X2 direction by the second predetermined distance D2. That is, the step portion 32 is formed in a concave shape depressed in the X2 direction. One side of the direction orthogonal to the X direction is defined as a longitudinal direction, and the other side is defined as a short direction. In the longitudinal direction, the step 32 has a third predetermined distance D3. In the lateral direction, the inner surface 33 of the step portion 32 is arranged at a position shifted by a fourth predetermined distance D4 from the inner surface 34 of the groove portion 31. Hereinafter, the step portion 32 will be described in more detail.

  The step portion 32 includes a fourth step portion 32a formed on the Y1 side inner surface 34a of the groove portion 31, a fifth step portion 32b formed on the Y2 direction side inner surface 34b of the groove portion 31, and a groove portion. And a sixth step-like portion 32c formed on the inner side surface 34c of the Z31 in the Z2 direction. The fourth step portion 32a, the fifth step portion 32b, and the sixth step portion 32c are each formed in substantially the same shape.

  Specifically, the fourth stepped portion 32a has the second predetermined distance D2 in the X direction, has the third predetermined distance D3 in the Z direction (longitudinal direction), and has the fourth predetermined distance D3 in the Y direction (short direction). It has a predetermined distance D4. The fifth step portion 32b has a length of the second predetermined distance D2 in the X direction, has a third predetermined distance D3 in the Z direction (longitudinal direction), and has a fourth predetermined distance in the Y direction (short direction). It has a distance D4. The sixth step portion 32c has a length of a second predetermined distance D2 in the X direction, a third predetermined distance D3 in the Y direction (longitudinal direction), and a fourth predetermined distance D3 in the Z direction (short direction). It has a distance D4.

  Note that the first metal member 2 and the second metal member 3 may be the same type of metal or different types of metal.

  Next, the rotation tool 4 will be described with reference to FIG. FIG. 1 shows a state in which the first joining surface 2d of the first metal member 2 and the second joining surface 3d of the second metal member 3 are friction stir welded using the rotary tool 4.

  The rotating tool 4 supplies frictional heat to an abutting portion P where the first joining surface 2d of the first metal member 2 and the second joining surface 3d of the second metal member 3 abut, so that the first metal member 2 and the The second metal member 3 is configured to be softened and joined. Specifically, the rotating tool 4 includes a tool main body 41, a rotary motor driving unit 42, a pressing mechanism (not shown), and a probe 43. Here, a rotary motor drive unit 42 is provided on one side of the tool main body 41. A probe 43 is provided on the other side of the tool body 41.

  The tool main body 41 is formed in a cylindrical shape. The rotary motor drive unit 42 is configured to rotate the tool body 41 and the probe 43 integrally. The pressurizing mechanism is configured to move the rotary motor drive unit, the tool body 41, and the probe 43 toward the butting portion P while integrally rotating the tool body 41 and the probe 43 by the rotary motor drive unit. Have been.

  The probe 43 is arranged on one end of the tool main body 41 and on a coaxial center line of the tool main body 41. The probe 43 protrudes from the tool main body 41 to the side opposite to the rotary motor drive unit 42. The probe 43 has a smaller diameter than the tool body 41. The probe 43 is configured to be rotatable integrally with the tool main body 41 by the rotary motor drive unit 42.

(Method of joining first metal member and second metal member)
Here, a method of joining the first metal member 2 and the second metal member 3 using the rotating tool 4 will be described with reference to FIG. FIG. 4 is a schematic view of a butt portion P (see FIG. 1) in a state where the first joint surface 2d of the first metal member 2 and the second joint surface 3d of the second metal member 3 are overlapped in the X direction. FIG.

  In the joining structure 1, by moving the rotary tool 4 along the moving direction, the butting portion P in which the first joining surface 2 d of the first metal member 2 and the second joining surface 3 d of the second metal member 3 abut against each other is formed. Joined. Here, the rotation tool 4 moves on a trajectory in which the rotation center axis of the probe 43 is along the abutting surface between the first joint surface 2d and the second joint surface 3d.

  Specifically, in the joining structure 1, the butting portion P on the Y1 direction side is joined by the rotating tool 4. That is, in the joining structure 1, the probe 43 of the rotary tool 4 is inserted into the butted portion P in the Y1 direction while the backup plate 9 is in contact with the end in the Y2 direction of the butted portion in the Y1 direction. Then, in the joining structure 1, the butting portion P extending in the Z direction on the Y1 direction side is joined by moving the rotary tool 4 in the first joining direction (Z2 direction) while rotating the probe 43. Here, a portion where the butted portions P on the Y1 direction side are joined is referred to as a first joined portion 7a.

  Next, in the joint structure 1, the butting portion P on the Z2 direction side is joined after the joining portion P on the Y1 direction side is joined. That is, in the joint structure 1, the probe 43 of the rotary tool 4 is inserted into the butting portion P in the Z2 direction while the backup plate 9 is in contact with the end in the Z1 direction of the butting portion P in the Z2 direction. Then, in the joining structure 1, the butting portion P extending in the Y direction on the Z2 direction side is joined by moving the rotary tool 4 in the second joining direction (Y2 direction) while rotating the probe 43. Here, the portion where the butted portions P on the Z2 direction side are joined is referred to as a second joined portion 7b.

  Next, in the joining structure 1, the joining portion P on the Y2 direction side is joined after the joining portion P on the Z2 direction side is joined. That is, in the joining structure 1, the probe 43 of the rotary tool 4 is inserted into the butting portion P in the Y2 direction while the backup plate 9 is in contact with the end in the Y1 direction of the butting portion P in the Y2 direction. Then, in the joining structure 1, the butt portion P extending in the Z direction on the Y2 direction side is joined by moving the rotary tool 4 in the third joining direction (Z1 direction) while rotating the probe 43. Here, the portion where the butted portions P on the Y2 direction side are joined is referred to as a third joined portion 7c.

(Joint structure)
In this way, as shown in FIG. 5, a box-shaped joining structure 7 in which the first metal member 2 and the second metal member 3 are friction stir welded is formed. That is, the joint structure 7 is formed by the joint structure 1 arranged at a substantially central portion in the X direction. Hereinafter, the joint structure 1 including the first joint portion 7a, the second joint portion 7b, and the third joint portion 7c in the joint structure 7 will be described. Note that the first joint portion 7a, the second joint portion 7b, and the third joint portion 7c have the same configuration as each other, and therefore only the first joint portion 7a will be described.

<Joint>
As described above, the joining portion 5 is a portion where the first joining surface 2d (see FIG. 2) and the second joining surface 3d (see FIG. 3) are friction stir welded. As shown in FIGS. 5 and 6, the joint portion 5 is formed in a substantially trapezoidal shape similar to the shape of the probe 43 in a side view when viewed from the Z1 direction. The joint 5 has a length substantially the same as the height of the probe 43 in the Y direction and a length substantially the same as the width of the probe 43 in the X direction. The length of the joint 5 in the Z direction is substantially the same as the length of each of the first metal member 2 and the second metal member 3 in the Z direction.

<Stress relief recess>
As shown in FIGS. 5 and 6, the unjoined portion 6 of the first embodiment is provided with a stress relief recess 8. The stress relief concave portion 8 has a stress caused by a load applied to the joint structure 7 (for example, an object is hit, a compressive force is applied, a contraction force is applied) in the unjoined portion 6 (portion D in FIG. 6). It is configured to suppress the occurrence of concentration. Specifically, the stress relief recess 8 is formed adjacent to the joint 5 in the Y direction. Here, the center position in the X direction of the stress relief concave portion 8 is disposed at substantially the same position as the center position in the X direction of the joint 5. That is, the center position in the X direction of the stress relief concave portion 8 is disposed at substantially the same position in the X direction as the boundary surface B between the first joint surface 2d and the second joint surface 3d.

  As shown in FIG. 6, the stress relief recess 8 is formed in a C-shape when viewed from the Z1 direction. That is, the shape of the stress relief recess 8 when viewed from the Z1 direction is formed by combining the above-described first step-like portion 22a (see FIG. 2) and fourth step-like portion 32a (see FIG. 3). I have. Accordingly, the predetermined width A1 of the stress relief recess 8 extending in the X direction is a length obtained by adding the second predetermined distance D2 of the first step portion 22a and the second predetermined distance D2 of the fourth step portion 32a. That's it. The predetermined depth A2 of the stress relief recess 8 extending in the Y direction is substantially the same as the fourth predetermined distance D4 of the first step 22a and the fourth predetermined distance D4 of the second step 22b. That's it.

  Here, the predetermined width A1 of the stress relief concave portion 8 may be increased in length toward the Y1 direction side. Further, it is preferable that the predetermined width A1 of the stress relief concave portion 8 is not less than about 所 定 of the predetermined depth A2 and not more than the maximum width of the bonding portion 5 in the X direction. The predetermined depth A2 of the stress relief recess 8 is a depth necessary for preventing the backup plate 9 from being joined to the first metal member 2 or the second metal member 3 during friction stir welding by the rotary tool 4. . Further, the predetermined depth A2 of the stress relief recess 8 is preferably, for example, not more than about ８ of the length of the joint 5 in the Y direction.

  As shown in FIG. 5, the stress relief concave portion 8 is formed in a groove shape extending in the Z direction. The groove shape of the stress relief concave portion 8 extending in the Z direction is formed by combining the above-mentioned first step portion 22a (see FIG. 2) and fourth step portion 32a (see FIG. 3). The predetermined groove length A3 of the stress relief concave portion 8 extending in the Z direction is substantially the same as the third predetermined distance D3 of the first step portion 22a and the third predetermined distance D3 of the second step portion 22b. It is.

  Here, the predetermined groove length A3 of the stress relief recess 8 is smaller than the length of each of the first metal member 2 and the second metal member 3 in the Z direction. That is, the predetermined groove length A3 of the stress relief concave portion 8 is set such that the first metal member 2 and the second metal member 3 extend from the respective Z1 direction ends of the first metal member 2 and the second metal member 3. It is the length from the end of each Z2 direction side to the portion on the Z1 direction side.

  As shown in FIG. 5, such stress relief recesses 8 are formed on a plurality (three) of inner side surfaces 71 of the box-shaped joint structure 7 arranged in a direction orthogonal to the X direction. The plurality of (three) stress relief recesses 8 formed on each of the plurality of inner side surfaces 71 are respectively arranged at substantially the same position in the X direction.

<Storage space>
As shown in FIG. 5, the joint structure 7 has a storage space 72 for storing components used in a vehicle. The storage space 72 is formed by joining the first recess 2c (see FIG. 2) and the second recess 3c (see FIG. 3) when the first metal member 2 and the second metal member 3 are joined. ing. The storage space 72 has a length obtained by adding a first predetermined distance D1 of the groove 21 of the first metal member 2 and a first predetermined distance D1 of the groove 31 of the second metal member 3 in the X direction. The length of the storage space 72 in the Y direction is substantially equal to the length of the first metal member 2 in the Y direction minus the length of the joining portion 5 in the Y direction. The length of the storage space 72 in the Z direction is substantially equal to the length of the stress relief recess 8 in the Z direction.

(Effect of First Embodiment)
In the first embodiment, the following effects can be obtained.

  In the first embodiment, as described above, the unbonded portion 6 is provided with the stress relief recess 8. This can reduce a sudden increase in the stress generated in the unjoined portion 6 as compared with the case where the unjoined portion 6 has the cutout shape, so that the unjoined portion 6 when a load is applied to the joined structure 1 can be reduced. The generated stress concentration can be suppressed. As a result, it is possible to prevent the joining portion 5 between the first metal member 2 and the second metal member 3 from separating due to the concentration of stress generated in the unjoined portion 6.

  Further, in the first embodiment, as described above, the stress relief recess 8 is formed in a groove shape extending in the Z direction. Thus, by providing the groove-shaped stress relief concave portion 8 extending in the Z direction in the unjoined portion 6, stress concentration occurring in the unjoined portion 6 when a load is applied to the joint structure 1 is suppressed over a wider range. be able to. As a result, it is possible to more reliably suppress the joint 5 between the first metal member 2 and the second metal member 3 from being separated due to the concentration of stress generated in the unjoined portion 6.

  In the first embodiment, the stress relief recess 8 is provided on the inner side surface 71 of the box-shaped joint structure 7 as described above. Thereby, the box-shaped joining structure is formed only by performing the friction stir welding on the outer surface of the joining structure 7 opposite to the inner side surface 71 of the box-shaped joining structure 7 in which the stress relief recess 8 is provided. 1 can be formed, so that the box-shaped joint structure 7 can be easily formed.

[Second embodiment]
The second embodiment will be described with reference to FIGS. In the second embodiment, an example will be described in which the shape of the stress relief recess 208 viewed from the Z1 direction is different from that of the first embodiment. In the drawings, the same components as those in the first embodiment are denoted by the same reference numerals.

<Stress relief recess>
Hereinafter, the joint structure 1 including the first joint portion 207a, the second joint portion 207b, and the third joint portion 207c in the joint structure 7 will be described. Note that the first joint portion 207a, the second joint portion 207b, and the third joint portion 207c have the same configuration as each other, and therefore only the first joint portion 207a will be described.

  As shown in FIG. 7, the stress relief recess 208 of the second embodiment is configured to curve toward the center in the X direction as it goes in the Y1 direction. Specifically, the corner of the inner bottom 273 of the stress relief recess 208 is formed in a rounded shape. That is, the stress relief recess 208 is formed in a substantially U shape when viewed from the Z1 direction. The other configuration of the second embodiment is the same as that of the first embodiment.

(Effect of Second Embodiment)
In the second embodiment, the following effects can be obtained.

  In the second embodiment, as described above, the corner of the inner bottom 273 of the stress relief recess 208 is formed in a rounded shape. Accordingly, when a load is applied to the first metal member 2 and the second metal member 3 due to the rounded corners of the inner bottom portion 273 of the stress relief concave portion 208, the stress applied to the unjoined portion 6 is sharp. The increase can be mitigated. As a result, it is possible to further suppress the concentration of stress generated in the unjoined portion 6. The other effects of the second embodiment are the same as those of the first embodiment.

[Modification]
The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and further includes all modifications (modifications) within the scope and meaning equivalent to the terms of the claims.

  For example, in the first and second embodiments, the example in which the first metal member 2 and the second metal member 3 have substantially the same shape has been described, but the present invention is not limited to this. In the present invention, the first metal member and the second metal member may have different shapes.

  In the first and second embodiments, the example in which the plurality (three) of the stress relief concave portions 8 (208) in the joint structure 7 are arranged at substantially the same position in the X direction has been described. The present invention is not limited to this. In the present invention, the plurality (three) of the stress relief concave portions in the joint structure may be arranged at different positions (shifted positions) in the X direction.

  In the first and second embodiments, the stress relief recess 8 (208) has a C-shape or a U-shape when viewed from the Z1 direction. However, the present invention is not limited to this. . In the present invention, the stress relief concave portion may have an arc shape when viewed from the Z1 direction.

  In the first and second embodiments, the stress relief recess 8 (208) is disposed at substantially the same position in the X direction as the boundary surface B between the first joint surface 2d and the second joint surface 3d. Although an example is shown, the present invention is not limited to this. In the present invention, as in the first modified example shown in FIG. 8, the stress relief recess 308 is disposed at a position shifted in the X direction from the boundary surface B between the first joint surface 2d and the second joint surface 3d. May be. Specifically, the unjoined portion 6 includes a concave step portion 381 provided so as to be depressed in the X1 direction from the end of the first joining surface 2d in the Y2 direction, and an end in the Y2 direction of the second joining surface 3d. And a convex step portion 382 provided so as to protrude from the portion in the X1 direction. The stress relief concave portion 308 is formed between the concave step portion 381 and the convex step portion 382. Thus, by shifting the stress relief recess 308 in the X direction, a portion where stress concentration occurs in the direction in which the stress relief recess 308 is shifted is shifted as compared with the case where the stress relief recess 308 is arranged on the boundary surface B. be able to. Thereby, when a load is applied to the first metal member 2 and the second metal member 3, even if a crack occurs along the boundary surface B at the joint portion 5, no stress concentration occurs along the boundary surface B. Therefore, it is possible to make it difficult for the cracks along the boundary surface B to propagate to portions other than the joint portion 5. Further, the positioning of the first metal member 2 and the second metal member 3 can be performed only by aligning the convex step portion 382 with the concave step portion 381, so that the joining structure 1 can be easily assembled. it can.

  Further, in the first and second embodiments, the example in which the joint structure 7 is formed by the joint structure 1 arranged at the substantially central portion in the X direction has been described, but the present invention is not limited to this. . In the present invention, as in the second modification shown in FIG. 9, the joint structure 407 may be formed by the joint structure 401 arranged at the end in the X1 direction (X2 direction) in the X direction.

  Further, in the first and second embodiments, the example in which the joint structure 7 has the storage space 72 for storing the components used in the vehicle is shown, but the present invention is not limited to this. . In the present invention, the joint structure may have a storage space for storing therein components other than components used for the vehicle.

DESCRIPTION OF SYMBOLS 1,401 Joining structure 2 1st metal member 2d 1st joining surface 3 2nd metal member 3d 2nd joining surface 5 Joining part 6 Unjoined part 7,407 Joining structure 8,208,308 Stress relief recess 71 Inner side surface 273 Inner bottom B Boundary surface

Claims (5)

A first metal member including a first joint surface;
A second metal member including a second bonding surface facing the first bonding surface in a first direction;
A joint in which the first joint surface and the second joint surface are friction stir welded,
And an unjoined portion formed at an end of the joined portion,
A joining structure, wherein a stress relief recess is provided in the unjoined portion.   The stress relief recess is formed in a groove shape extending in a third direction orthogonal to the first direction and a second direction in which the joined portion and the unjoined portion are adjacent to each other. Item 2. The bonding structure according to Item 1.   3. The joint structure according to claim 1, wherein a corner of an inner bottom of the stress relief recess is formed in a rounded shape. 4.   The said stress relief recessed part is arrange | positioned in the position shifted | deviated in the said 1st direction from the boundary surface of the said 1st joining surface and the said 2nd joining surface, The Claims any one of Claims 1-3. Joint structure.   The joint structure according to any one of claims 1 to 4, wherein the stress relief concave portion is provided on an inner surface of the box-shaped joint structure.

Images