JP2011101891A - Joining method - Google Patents

Abstract

The present invention proposes a joining method that can make use of the advantages of friction stir welding and compensate for the disadvantages.
A butt process S1 in which a plurality of metal members to be joined are abutted to form a butt part, a welding process S2 in which welding is performed along a part of the butt part, and a friction along the other part of the butt part. And a friction stir welding step S3 for stirring.
[Selection] Figure 1

Description

  The present invention relates to a joining method combining welding and friction stir welding.

  Conventionally, various welding methods are known as methods for joining metal members to be joined. In the welding, the welded portion of the member to be joined is heated, and the member to be joined or the member to be joined and the filler material are fused to form a molten metal, which is solidified to join the members to be joined.

  On the other hand, 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 is an advantage that there is little bonding failure due to (for example, see Patent Document 1).

JP 2006-312198 A

  Welding can produce weld defects such as poor penetration, cracks, pores, poor fusion, and slag entrainment. Among these welding defects, the pores are those in which bubbles due to gas generated due to a decrease in solubility with a decrease in temperature of the molten metal or a rapid decrease in solubility due to chemical reaction or crystallization of the solid phase remain until the end of bonding. In general, weld defects are likely to occur at the beginning and end of welding.

  On the other hand, the friction stir welding is performed by applying a large tool load to a member to be joined from a welding tool called a tool. Due to this, the friction stir welding can join the butt portion of the member to be joined having a complicated shape such as a curved surface shape or a square shape (a simple corner portion or a step portion where the corner portions are continuously connected). It has the problem of being difficult.

  In addition, in friction stir welding, a portion where the joining strength cannot be sufficiently obtained (a portion where stirring is insufficient) occurs at the joining end.

  Therefore, the present invention proposes a joining method capable of removing welding defects generated at the weld end portion of welding and making use of the advantages of friction stir welding while making up for the disadvantages.

  In order to solve the above-described problems, a joining method according to the present invention includes a butting process in which a plurality of metal members to be joined are butted to form a butting part, and a welding process in which welding is performed along a part of the butting part. And a friction stir welding step in which friction stir is performed along the other part of the abutting portion.

  ADVANTAGE OF THE INVENTION According to this invention, while the welding defect which generate | occur | produces in the joining edge part of welding can be removed, the joining method which can make up for the fault can be provided, utilizing the advantage of friction stir welding.

The flowchart which showed the joining method which concerns on embodiment of this invention. Schematic which showed the friction stir welding process among the joining methods which concern on embodiment of this invention. Schematic which showed an example of the structure joined by the joining method which concerns on embodiment of this invention. Schematic which showed an example of the structure joined by the joining method which concerns on embodiment of this invention. Sectional drawing which showed an example of the start end part of the junction part welded in the welding process among the joining methods which concern on embodiment of this invention. Sectional drawing which showed the overlap part joined by the friction stir welding after the welding process with the joining method which concerns on embodiment of this invention. The figure which showed an example of the joining strength of the structure joined by the joining method which concerns on embodiment of this invention. The schematic sectional drawing which showed the other example of the structure joined by the joining method which concerns on embodiment of this invention.

  Hereinafter, embodiments of a bonding method according to the present invention will be described with reference to FIGS. 1 to 8.

  FIG. 1 is a flowchart illustrating a bonding method according to an embodiment of the present invention.

  As shown in FIG. 1, the joining method according to the present embodiment includes a butting process S1, a welding process S2 that is performed after the butting process S1, and a friction stir welding process S3 that is performed at least after the butting process S1. . In addition, the joining method which concerns on this embodiment performs friction stir welding process S3 after welding process S2.

  The butting step S1 is a step of forming a butting portion in a plurality of members to be joined that are joined by the joining method according to the present embodiment. The member to be joined is a metal member including, for example, an aluminum alloy and may be any member that can be joined by friction stir welding and welding. The abutting portion includes an abutting surface (or a “joining surface”) that abuts the surfaces formed on the respective members to be joined, and is a region that is joined in the welding step S2 and the friction stir welding step S3.

  The welding step S2 is a step of moving the heat source along a part of the abutting portion and performing the main joining of the members to be joined by welding. The welding method performed in the welding step S2 includes arc welding using an arc as a heat source (including gas shield arc welding including TIG welding and MIG welding, self-shielded arc welding, etc.), gas welding, laser welding, electron beam welding, and the like. Known welding methods can be used.

  The friction stir welding step S3 is a step of moving the welding tool along the other part of the abutting portion and performing the main joining of the members to be joined by friction stirring.

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

  FIG. 2 is a schematic view showing a friction stir welding step in the joining method according to the embodiment of the present invention.

  As shown in FIG. 2, the friction stir welding step S <b> 3 is a step of joining the other part of the butt portion where a pair of the plates to be joined 11 and 12, which are a plurality of members to be joined, are joined using the welding tool 14. At this time, a welded portion 24 (details will be described later) is already formed in a part of the butted portion where the plates 11 and 12 are joined together in the welding step S2.

  The joining tool 14 includes, for example, a columnar rotating body 15 coupled to a driving unit of a rotation driving device (not shown), a columnar probe 16 integrally formed by protruding from the tip of the rotating body 15, Is provided. The end face of the rotating body 15 is called a shoulder 17. The probe 16 protrudes from the end face of the rotating body 15 to a length corresponding to the thickness of the abutting portion of the joined plates 11 and 12. In addition, the probe 16 is provided with a thread groove or the cross-sectional shape in the direction orthogonal to the rotation axis is formed in a non-circular shape (for example, an ellipse or a drum shape) in order to efficiently stir the joined plates 11 and 12. Or

  In the friction stir welding step S3, the welding tool 14 and the plate to be joined 11 are pressed against the abutting portions of the plates to be joined 11 and 12 while rotating the welding tool 14 at a high speed (solid arrow R in FIG. 2) by the rotation drive device. , 12 is used to soften the joint portions of the plates 11 and 12 to be joined, and the softened portions are agitated by the rotation of the joining tool 14 to join the plates 11 and 12 to be joined. After the joining portions of the plates to be joined 11 and 12 softened by the frictional heat are agitated so as to move backward in the joining direction of the joining tool 14 (solid arrow F in FIG. 2), friction occurs as the joining tool 14 moves. The plates to be joined 11 and 12 are joined by rapidly losing heat and cooling and hardening.

  3 and 4 are schematic views showing an example of a structure joined by the joining method according to the embodiment of the present invention.

  As shown in FIGS. 3 and 4, the joining plate members 22 and 22 </ b> A are structures obtained by joining the joined plates 11 and 12 by the joining method according to the embodiment of the present invention.

  Specifically, as shown in FIG. 3, the joining plate member 22 is joined with a weld joint portion 24 formed by the welding step S2 and a friction stir joint portion 25 formed by the friction stir joint step S3 adjacent to each other.

  On the other hand, as shown in FIG. 4, the joining plate member 22A performs the friction stir welding step S3 after the welding step S2, and overlaps the weld joint portion 24 by the welding step S2 and the friction stir joint portion 25 by the friction stir welding step S3. They are joined together. This overlapped portion is called an overlap portion 26.

  The overlap portion 26 is formed by superimposing the start end portion 25a of the friction stir welding portion 25 in the friction stir welding step S3 on the start end portion 24a of the weld joint portion 24 in the welding step S2. In addition, you may form the overlap part 26 in any of the start end part 24a and the termination | terminus part 24b of the welding junction part 24 by welding process S2.

  At this time, it is preferable that the range of the overlap portion 26 be equal to or larger than the bead width in the welding step S2. Thus, by superimposing the weld joint portion 24 and the friction stir joint portion 25 in both processes, the start end portion 24a (or the end portion 24b) of the weld joint portion 24 in which welding defects are likely to occur in the welding step S2 is friction stir joining step. It can stir and join by friction stir welding in S3.

  The joining plate materials 22 and 22A will be further described in detail.

  The joining plate materials 22 and 22A are structures obtained by joining the to-be-joined plates 11 and 12 which are plate materials having a plate thickness of 4 mm made of aluminum alloy (JIS H 4100: 6061-T6) by the joining method according to the present embodiment. .

  The welding conditions in the welding step S2 were as follows. A welding rod for aluminum (JIS Z 3232: A5356BY) was used as the filler material, the current value was about 130 A to 170 A, and the joining speed was about 100 mm / min.

  The welding tool 14 used in the friction stir welding step S3 has a shape with a diameter of the shoulder 17 of about 12 mm, a diameter of the probe 16 of about 5 mm, and a protruding length of the probe 16 of about 3.5 mm. Joining conditions of the friction stir welding step S3 are: the rotational speed of the joining tool 14 is about 1500 rpm, the joining speed of the joining tool 14 is about 300 mm / min, the advance angle of the joining tool 14 is about 3 °, and the insertion amount of the probe 16 to the member to be joined is about 3.7 mm, a waiting time of about 2 seconds from when the joining tool 14 is inserted into the member to be joined to when the joining tool 14 starts to move, and after the movement of the joining tool 14 is completed, the joining tool 14 is removed from the member to be joined. The waiting time until drawing was about 1 second.

  Further, in the joining plate material 22A, the joining end portion by the welding step S2 and the joining end portion by the friction stir welding step S3 were overlapped by about 20 mm. This is about 1.3 times the bead width of about 15 mm in the welding step S2.

  FIG. 5 is a cross-sectional view illustrating an example of a starting end portion of a joint portion welded in a welding process in the joining method according to the embodiment of the present invention.

  As shown in FIG. 5, the start end portion 24a of the weld joint portion 24 in the welding step S2 has pores 24c as welding defects. A weld defect does not necessarily occur, but generally tends to occur at the start end portion 24a or the end end portion 24b of the weld joint portion 24 in the welding step S2.

  FIG. 6 is a cross-sectional view showing an overlap portion joined by friction stir welding after the welding process by the joining method according to the embodiment of the present invention.

  As shown in FIG. 6, the overlap part 26 is agitated and joined by the joining tool 14 in the friction stir welding step S3. Thereby, the welding defect (for example, pore 24c in FIG. 5) generated in the start end portion 24a or the end end portion 24b of the weld joint portion 24 in the welding step S2 is crushed and disappears.

  Here, the strength of the joined portions of the joining plate materials 22 and 22A will be described.

  The test piece of the joining plate material 22 is obtained by cutting out a region (a region T1 sandwiched between two-dot chain lines in FIG. 3) including the joining end (here, the start end portion 24a) in the welded joint portion 24 by welding.

  On the other hand, the test piece of the joining plate material 22A is obtained by cutting out a region including the overlap portion 26 (a region T2 sandwiched between two-dot chain lines in FIG. 4) in the welded joint portion 24 by welding.

  Both test pieces have a width that is approximately twice the length of the overlap portion 26 in the joining direction. Moreover, the bonding strength to be evaluated is the tensile strength with respect to the normal direction of the abutting surface.

  FIG. 7 is a view showing an example of the bonding strength of the structures bonded by the bonding method according to the embodiment of the present invention.

  As shown in FIG. 7, the bonding plate material 22 </ b> A was improved in bonding strength by about 2.7 times compared to the bonding plate material 22.

  The test piece of the joining plate material 22 has only the weld joint portion 24 joined by the welding step S2. The weld joint portion 24 is not subjected to stirring by the joining tool 14. That is, the test piece of the joining plate material 22 has the start end portion 24a of the welded joint portion 24 remaining without being subjected to the friction stir welding. Therefore, it is considered that the test piece of the joining plate material 22 has substantially the same joining strength as the joining portion joined only by welding.

  On the other hand, the test piece of the joining plate material 22 </ b> A includes an overlap portion 26. That is, in the test piece of the joining plate material 22A, the start end portion 24a of the weld joining portion 24 is agitated and joined by the joining tool 14.

  FIG. 8 is a schematic cross-sectional view showing another example of a structure joined by the joining method according to the embodiment of the present invention.

  As shown in FIG. 8, the joining pipe 35 is a structure in which rounded round tube materials 27 and 28 that are joined members are joined by the joining method according to the embodiment of the present invention.

  The rounded round tube materials 27 and 28 have a substantially rectangular cross-sectional shape in the direction perpendicular to the longitudinal axis, and have a side portion 31 having a substantially planar surface and a rounded corner portion 32 having a rounded surface. It is a hollow tube.

  The joining pipe 35 joins the side portion 31 in the friction stir welding step S3 after joining the rounded corner portion 32 in the welding step S2, and welds the welded portion 24 in the welding step S2 and the friction stir joining portion in the friction stir joining step S3. 25 and are joined together.

  That is, the joining pipe 35 is joined while forming the overlap portion 26 by performing the friction stir joining step S3 after the welding step S2 similarly to the joining plate material 22A. It has the overlap part 26 comprised by superimposing the friction stir welding part 25 by friction stir welding process S3 on the welding joint part 24 by welding joining process S2.

  The overlap portion 26 is formed by welding the side portion 31 in the vicinity of the rounded corner portion 32 so as to be continuous with the rounded corner portion 32 in the welding step S2 and joining the side portion 31 by friction stir welding.

  Therefore, according to the joining method according to the present embodiment, even if a welding defect occurs in the start end portion 24a (or the end portion 24b) of the weld joint portion 24, this portion is reliably joined by friction stir welding and the joint quality is obtained. Can be improved.

  Further, according to the joining method according to the present embodiment, when joining a member to be joined having a gap (for example, about 0.5 mm or more) or a step (for example, about 0.5 mm or more) on the abutting surface, A gap or a step can be joined by welding, and other portions can be joined by friction stir welding. According to the joining method according to the present embodiment, it is possible to reliably join a gap portion or a step portion that is difficult to join by friction stir welding and obtain a high joining strength.

  Furthermore, according to the joining method according to the present embodiment, a complicated shape portion (hereinafter, referred to as a portion having a curved surface shape and a portion having a corner shape (a simple corner portion or a stepped portion in which corner portions are continuously connected)). When joining a member to be joined having “non-planar shape portion”), the non-planar shape portion (the portion corresponding to the rounded corner portion 32 in the joining pipe 35) is joined by welding, and the other substantially planar portion. (Part corresponding to the side part 31 in the joining pipe 35) can be joined by friction stir welding. According to the joining method according to the present embodiment, a non-planar shape portion (a portion corresponding to the rounded corner portion 32 in the joining pipe 35) can be reliably joined to obtain a high joining strength.

  Furthermore, according to the joining method according to the present embodiment, for example, it is not possible to obtain a sufficient joining strength by a member to be joined having a thick part having many gas defects that are difficult to join by welding, or by joining by welding. These parts can be joined to the member to be joined having the stress concentration part by friction stir welding, and the joining strength can be improved.

  The structures to be joined by the joining method according to the embodiment are not limited to the joining plate materials 22 and 22A and the joining pipe 35, but are hollow extruded materials having a non-planar shape portion, square pipe materials, various frame materials, and press-molded products. Further, the present invention can also be applied to back-joining members to be joined such as cast products, forged products, and sintered products.

  Therefore, according to the joining method which concerns on this invention, while being able to remove the welding defect which generate | occur | produces in the joining edge part of welding, the weak point can be supplemented, utilizing the advantage of friction stir welding.

DESCRIPTION OF SYMBOLS 11, 12 Plate to be joined 14 Joining tool 15 Rotating body 16 Probe 17 Shoulder 21 Surface 22, 22A Joining plate material 24 Welding joining part 24a Starting end part 24b Ending part 24c Pore 25 Friction stir welding part 25b Ending part 25a Starting end part 26 Overlap part 27, 28 Rounded round pipe material 31 Side part 32 Rounded round part 35 Joint pipe

Claims (7)

A butting step of butting a plurality of metal members to be joined to form a butting portion;
A welding step of performing welding along a part of the abutting portion;
And a friction stir welding step in which friction stir is performed along the other part of the abutting portion. The joining method according to claim 1, wherein the friction stir welding step joins a substantially planar portion of the abutting portion. The joining method according to claim 1, wherein the welding step joins a non-planar shape portion of the abutting portion. The joining method according to any one of claims 1 to 3, wherein a joining end by the friction stir welding step and a joining end by the welding step are overlapped. The joining method according to claim 4, wherein a portion where the joining end by the friction stir welding step and the joining end by the welding step overlap is located at a substantially planar portion of the abutting portion. The joining method according to claim 4 or 5, wherein a range in which the joining end by the friction stir welding step and the joining end by the welding step are overlapped is equal to or larger than a bead width in the welding step. The joining method according to any one of claims 1 to 6, wherein the friction stir welding step is performed after the welding step.

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