JP2002059289A - Method for repairing friction-stir welded part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a method for repairing a friction-stir welded part in manufacturing a structure such as a rolling stock by friction-stir welding an aluminum alloy. SOLUTION: A weld bead 50 is formed by performing the friction stir welding of hollow-extruded first member 20 and second member 30 along a welding part 40 with a base metal of A6N01 as aluminum alloy. When the weld bead 50 is defective, the bead including the defects is removed by grinding to form a repair area. The repair bead is formed by the TIG welding in the repair area. A welding rod of the TIG welding is formed of the same material as the base metal to realize the uniform composition of the bead. When the hair line working is performed in the friction-stir welded part, a surface of excellent appearance in which a boundary with the member and a trace of the defects are less remarkable can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repair method in friction stir welding.

[0002]

2. Description of the Related Art In a friction stir welding method, a round bar (referred to as a rotary tool) inserted into a joint is moved along a joining line while rotating, so that the joint is heated, softened, and plastically flows.
This is a solid-phase bonding method. The rotary tool has a small diameter portion inserted into the joint and a large diameter portion located outside. The small diameter part and the large diameter part are coaxial. The boundary between the small diameter portion and the large diameter portion is slightly inserted into the joint. The rotary tool is tilted backward with respect to the direction of joining.

When performing friction stir welding, a convex portion is formed on the surface on the side where the rotary tool is inserted. For this reason, the plate thickness is reduced at the joint.

In order to prevent this, a projection protruding toward the rotary tool is provided at the end of the member to be welded, and friction stir welding is performed including this. Further, a third plate is arranged in place of the convex portion and friction stir welding is performed. Further, in joining the hollow members, a support plate orthogonal to the face plate of the hollow members is provided integrally to prevent the face plate from being bent by the force of friction stir welding.

This is disclosed in Japanese Patent Application Laid-Open No. 9-309164 (E
P0797043A2).

FIG. 9 shows a railway vehicle 10 by friction stir welding.
The technique of joining the side structures of FIG. The structural members of the side structure
For example, strip-shaped extruded members (members) 20 and 30 manufactured by extruding an aluminum alloy material (A6N01 material) are joined together at their side edges, and subjected to friction stir welding along the joining line 40 to join. A bead 50 is formed.

Next, the joint bead 50 is inspected, and if there is no defect, the defect is repaired, and if a defect is found, the defect is repaired, and then a hairline processing or the like is performed to form a beautiful surface.

FIG. 4 shows a first member 20 and a second member 30.
Shows a state in which the friction stir welding is performed along the joining line 40 of FIG. This joining bead 50 is
For example, inspection is performed by ultrasonic inspection or the like, and a defect 60 shown in FIG.
Is assumed to have been discovered.

In FIGS. 1 to 7 (except for FIG. 3), the lines at the ends of the projections are not shown.

FIGS. 6 and 7 show a conventional repair process for this defect.

The first member 20 and the second member 30 are formed by extrusion using an A6N01 material which is an aluminum alloy material as a base material. A joining bead 50 formed by subjecting the members 20 and 30 to friction stir welding is also made of A6
The N01 material is a component.

In order to remove the defect of the bead 50, a process including a defective portion is performed using a tool such as a grinder,
The repair area 70 is formed.

Next, MIG welding is performed, and the repair bead 80
To form For the MIG welding, a welding wire suitable for the MIG welding is used. As the material of this welding wire, a material of A5356 standard is used.

FIG. 8 shows a state in which a hairline processing 52 is applied to the joint including the repaired bead.

The hairline processing section 52 includes members 20 and 30
It has a highly homogeneous surface with respect to the surface of the vehicle, and can be used as a side structure of a vehicle without painting.

[0016]

When the joint bead repaired by MIG welding of the above-mentioned joint bead by friction stir welding is subjected to hairline processing, the surface of the repaired portion 82 has a different appearance from the surrounding surface. Is shown.

The appearance of the repaired portion is aesthetically problematic when the joining member is used as a vehicle side structure without painting.

The present invention provides a method for repairing a friction stir welded part that solves the above-mentioned problems.

[0019]

A method for repairing a joint formed by friction stir welding according to the present invention comprises the steps of: removing a defect contained in a weld bead by grinding to form a repair area; Forming a repair bead by TIG welding using a welding rod of the same material as the base material of the member in the repair area.

The method may further include a step of applying a hairline process to a joint including the repair bead and the joint bead.

[0021]

1 and 2 show a method for repairing friction stir welding according to the present invention.

The first of the extruded profiles constituting the side structure of the vehicle
The joining portion 40 between the member 20 and the second member 30 is subjected to friction stir welding to form a joining bead 50.

FIG. 10 is a sectional view taken along line AA of FIG. In the figure, a convex portion 22 of a first member 20 and a second convex portion 32
Bead 5 by friction stir welding
0 is formed.

When the projections 22 and 32 of the members 20 and 30 are used as the outer surface of the vehicle, the joined projections are formed into a flat surface 54 by grinding or the like. When the opposite surface is on the outside, the joined projections may be left as they are.

The joining bead 50 is made of the same material as the A6N01 material which is the base material of the members 20 and 30.

Next, the joining bead 50 is inspected. This inspection may be performed in a state where the convex portion remains, or may be performed after the convex portion is cut.

As a result of the inspection, if a defect such as a crack or a pit is found in the joining bead 50, the surrounding joining bead 50 including this defect is removed (ground) by a grinder to form a repair area 70 (FIG. 1).

Next, as shown in FIG.
At 0, a repair bead 100 is formed by TIG welding. That is, overlay welding is performed. In the TIG welding, a welding rod made of the same material as that of the base material, that is, A6N01 material, is prepared and welded. This welding rod of A6N01 material is manufactured by cutting the surplus material of the extruded shapes (members) 20 and 30 of the base material.

By this welding, the joining bead 50 and the repair bead 100 are formed of the same material.

In TIG welding, since the electrode and the welding rod are different, the same material as the base material can be easily used as the welding rod.

Next, the convex portion is removed by cutting, and the surface on the convex portion side is subjected to air line processing.

Therefore, a high quality surface can be obtained without any trace of the repair bead 100 on the hairline processed portion 54 obtained by performing a hairline process on the joint bead portion.

Therefore, a vehicle having a good appearance can be constructed.

In the case of extruded A6N01 material and MIG welding, A5356 material is used as a welding wire. This combination is recommended by the welding wire manufacturer.

This combination is the best in terms of welding strength, execution and the like.

Material: A6N01 material, welding wire: A6N
As for the combination of 01 materials, wire: A6N01 material is not commercially available. Further, the combination of these two is excluded from welding strength: weldability and the like.

Therefore, in the present invention, a surplus of A6N01 material was cut into a welding rod.

Inspection and repair of the joining bead may be performed after cutting the convex part.

In the case of a hollow profile, if there is a joint on both sides, the above TIG welding is used for repairing the outer surface for performing hairline processing. Repair of the inner surface is made of A5356
MIG welding using a welding wire of a standard material is used.

As shown in FIG. 10, when the tip of the small diameter portion of the rotary tool is friction stir welded close to the bed, the lower surfaces of the members 20, 30 in FIG. 10 are finished smoothly. In some cases, this surface is used as an outer surface on the vehicle side to perform air line processing.
Even when the joint bead is repaired from the lower surface side in FIG. 10, the repair by the TIG welding can be performed. Thereafter, the repair bead is ground and smoothed.

[0041]

As described above, according to the present invention, when a member formed by hollow extrusion molding of an aluminum alloy material is joined by friction stir welding to form a structural member such as an aluminum vehicle, friction stir welding is performed. When repairing the defect of the joint bead due to the above, the repaired area is formed by removing the defective portion by grinding or the like, and the repaired area is welded by using a welding rod of the same material as the member.
A repair bead is formed by IG welding.

Since the joining bead and the repair bead formed by friction stir welding are formed of the same material, when the bead is subjected to hairline processing, a trace of the repair bead does not remain, and a high-quality joint surface can be obtained.

Accordingly, a vehicle or the like can be constructed without painting, and a structure that is lighter and more suitable for recycling can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a process of repairing a friction stir welding portion according to the present invention.

FIG. 2 is an explanatory view showing a repairing step of the friction stir welding section of the present invention.

FIG. 3 is an explanatory view showing a process of repairing a friction stir welding portion according to the present invention.

FIG. 4 is an explanatory view of a friction stir welding part.

FIG. 5 is an explanatory view of a defect of a friction stir welding part.

FIG. 6 is an explanatory view showing a conventional repair process of a friction stir welding portion.

FIG. 7 is an explanatory view showing a conventional repair process of a friction stir welding portion.

FIG. 8 is an explanatory view showing a conventional repair process of a friction stir welding portion.

FIG. 9 is an explanatory view for producing a side structure of a vehicle by friction stir welding.

FIG. 10 is a sectional view taken along line AA of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vehicle 20 1st member 30 2nd member 50 Joining bead by friction stir welding 60 Defect 70 Repair area 100 Repair bead

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunari Fukuyoro 794, Higashi-Toyoi, Katsumatsu-shi, Yamaguchi Prefecture Inside Hitachi Kasado Machine Industry Co., Ltd. (72) Inventor Akihiro Sato 7-1, Omika-cho, Hitachi City, Ibaraki No. 1 F-term in Hitachi Research Laboratory, Hitachi, Ltd. (reference) 3D026 BA01 BA14 4E001 AA03 BB07 CB01 4E067 AA05 BG00 DD00 EB00

Claims (2)

[Claims] 1. A method for repairing a joint formed by friction-stirring a member made of an aluminum alloy as a base material, wherein a defect included in a joint bead is removed by grinding to form a repair region. Forming a repair bead by TIG welding using a welding rod made of the same material as the base material of the member in the formed repair region. 2. The method for repairing a friction stir welded joint according to claim 1, further comprising a step of performing a hairline process on a joint including the repair bead and the joint bead.