JP5789495B2 - How to repair welds - Google Patents

Description

  The present invention relates to a method for repairing a welded portion of a metal member, particularly an aluminum alloy welded portion.

  When aluminum alloys are melt-welded, pores called blowholes or small depressions called pits opened on the surface of the welded part may be generated inside the welded part.

  A blowhole is generated when a gas component such as nitrogen, carbon monoxide, hydrogen, or a metal vapor such as zinc is taken into the weld, and a pit is observed on the surface of the weld. is there. These defects are caused by poor shielding during welding, lack of deoxidizer, oil content on the groove surface of the base material, surface adhesive such as a primer, moisture in the welding material, and the like. Although attempts have been made to suppress the appearance of these defects by adjusting the welding conditions and welding work environment, it is considered difficult to eliminate them completely.

  These defects are repaired in railcar structures assembled from aluminum alloy extruded profiles, especially in structures that are hairlined without painting the outer surface (outer surface) of the vehicle. It is targeted. Normally, a pit with a diameter of around 1 mm that appears on the surface of a melt welded part of a railway vehicle structure assembled by fusion welding is newly filled in the area including the pit (pit filling) and then welded beads are placed. In order to eliminate the blowhole inside, it was repaired by hitting the surface of the weld with a hammer or the like.

  However, in the process of filling welding by fusion welding, new blow holes and pits may be generated, and repair work may be necessary again. Repeating these repairs promotes the accumulation of thermal effects on the surrounding aluminum parts, including the welds, and reduces new strength such as reduced weld strength, increased weld deformation, and cracking of the aluminum base metal. There was concern that could be a factor in causing defects.

  Patent Document 1 discloses a technique for repairing a defect generated in a joint portion of an aluminum alloy material joined by friction stir welding by fusion welding. In this repair method, first, a step of removing defects contained in the joint bead by grinding, and a step of forming a repair bead by TIG welding using a welding rod of the same material as the base material of the member in the removed region, It is equipped with. And it is supposed that the process which performs a hairline process to the junction part containing a repair bead and a joining bead may be provided.

JP 2000-334583 A

When repairing aluminum alloy welds by fusion welding, not only new blowholes and pits may be generated in the repair process, but also the strength of the welds decreases as the heat input increases, There are problems such as an increase in the amount of deformation around the periphery.
An object of the present invention is to provide a repair method for a welded portion of an aluminum alloy that has been melt welded without decreasing the strength of the welded portion or increasing the amount of deformation around the welded portion.

  In the present invention, a build-up bead or build-up portion that covers a defect generated on the surface of the welded portion is formed, and the build-up bead or build-up portion is formed from above the build-up bead or build-up portion. The above-mentioned problem is solved by adopting a repairing process in which the above-described build-up bead or build-up portion is crushed by the above-mentioned rotary tool by pressing the rotary tool.

  As the rotary tool, a tool composed of a material harder (harder) than the material to be repaired is used. Various methods can be adopted as the method for forming the build-up bead or the build-up portion.

  The repair method which can repair the welding part of the aluminum alloy by this invention, without accompanying the strength fall of a welding part and the deformation amount increase around a welding part can be provided.

FIG. 1 is an appearance view after welding in butt welding of an aluminum alloy material and a state diagram of pits generated on the surface of a welded portion after finishing a weld bead smoothly. FIG. 2 is a process diagram showing a repair process comprising repair by fusion welding and repair by a steel round bar tool. FIG. 3 is a process diagram showing a repair process including repair using an aluminum alloy round bar tool and repair using a steel round bar tool. FIG. 4 is a process diagram of repair work by conventional fusion welding.

Hereinafter, with reference to drawings, the repair method (repair process) of the welding part by this invention is demonstrated. In this example, an aluminum alloy was used as the material of the member on which the welded portion to be repaired was formed.
FIG. 1 is an appearance view after welding in butt welding of an aluminum alloy material and a state diagram of pits generated on the surface of a welded portion after finishing a weld bead smoothly. When the two aluminum alloy members 10 and 20 are butted together and welded by fusion welding (for example, MIG welding) using a welding torch 40 as shown in FIG. A welding bead 30 is formed by a welding arc 41 and a welding rod (not shown) emitted from the welding torch 40.

  The weld bead 30 is then smoothed to the same surface height as the members 10 and 20. In some cases, blowholes generated in the welded portion during melt welding become pits 31 on the surface of the smoothened finish and are generated on the surface of the welded portion (welded bead). In this case, repair work is required again.

  FIG. 2 is a process diagram showing a repair process including repair by fusion welding and repair by a steel rotary tool. Although not shown in the drawings, the rotary tool includes a gripping part that is gripped by the repair machine at one end in the longitudinal direction, and a contact part that is in contact with a joining member (including a welded part) at the other end. It is configured to include. FIG. 2 shows a case where the pit 31 that appears on the surface of the welded portion (weld bead) is repaired after the weld bead 30 obtained by welding the aluminum alloy members 10 and 20 by fusion welding is smoothed.

  In this case, first, the build-up bead 32 is formed so as to cover the pit 31 by fusion welding (for example, MIG welding). Since the blow hole 33 may be included inside the newly formed overlaying bead 32, the cylindrical steel round bar tool 50 having a contact portion with a smooth end face is rotated at an arbitrary number of rotations. Then, the build-up bead 32 is pushed down so that the end face of the steel round bar tool 50 is aligned with the surface height of the aluminum alloy members 10 and 20 from above the build-up bead 32 to form the repair bead 34. To do.

Here, the build-up bead 32 is crushed by pushing down the end face of the contact portion of the rotary tool (steel round bar tool 50) to the surface of the member to be repaired. Blow holes 33 that may appear on the surface and become pits 31 during the surface (smooth) finishing of the process can be eliminated. For this reason, if the repair bead (the original build-up bead 32) is smooth (surface) finished with a grinder or the like, the surface of the welded portion without the pits 31 can be obtained on the finished surface.
At this time, if a steel round bar tool 50 having an outer diameter larger than the width (length) of the built-up bead 32 is prepared, it is necessary to move in the horizontal plane only by moving the steel round bar tool 50 in the vertical direction. The repair can be completed with less man-hours.

  According to the method for repairing a welded portion of an aluminum alloy by this method, since the number of repair operations by melt welding is only one, the amount of heat input associated with the repair operation can be reduced. Therefore, it is possible to repair the welded portion of the aluminum alloy that has been melt-welded without lowering the strength of the welded portion or increasing the amount of deformation around the welded portion.

In this embodiment, a modified example of the method for forming the built-up portion covering the defect will be described.
FIG. 3 is a process diagram showing a repair process including repair using a first rotary tool (aluminum alloy round bar tool) and repair using a second rotary tool (steel round bar tool). Here, the same rotary tool as used in Example 1 was used as the second rotary tool. FIG. 3 shows a case where the pit 31 that appears on the surface of the welded portion (weld bead) is repaired after the weld bead 30 obtained by welding the aluminum alloy members 10 and 20 by fusion welding is smoothed.

  First, an aluminum alloy round bar having a smooth end face is prepared. The aluminum alloy round bar tool 60 is preferably made of the same material as the weld bead 30 or the aluminum alloy members 10 and 20. Next, the aluminum alloy round bar tool 60 is positioned above the pit 31 formed on the surface of the weld bead 30 formed in the welded portion of the aluminum alloy members 10 and 20, and the aluminum alloy is rotated at a predetermined rotational speed. The round bar tool 60 is pushed down in such a manner that the pit 31 is crushed to a height at which the end face is not lower than the surface of the aluminum alloy members 10 and 20 (a height similar to that of the aluminum alloy members 10 and 20).

  The member on the end face of the aluminum alloy round bar tool 60 pressed against the surface of the pit 31 fills the pit 31 on the surface of the welded portion of the aluminum alloys 10 and 20 and moves to the surface of the welded portion so that the aluminum overlay 61 is formed. Form.

  Next, a cylindrical steel round bar tool 50 having a smooth end face is prepared, and the steel round bar tool 50 is rotated from above the aluminum overlay 61 while rotating the steel round bar tool 50 at an arbitrary rotation speed. The aluminum build-up portion 61 is pushed down in such a manner that the end face of the tool 50 is aligned with the surface height of the aluminum alloy members 10 and 20. By this step, the aluminum overlay 61 can be more firmly fixed to the surface of the welded portion. After that, if the surplus portion of the aluminum built-up portion 61 that has been crushed and stretched by the steel round bar tool 60 is smoothed with a grinder or the like until the surface height of the aluminum alloy members 10 and 20 is the same, The surface of the welded part without the pit 31 can be obtained.

  At this time, if a steel round bar tool 50 and an aluminum alloy round bar tool 60 having an outer diameter larger than the width (length) of the aluminum overlay 61 are prepared, the steel round bar tool 50 and the aluminum alloy Since only the round bar tool 60 is moved in the vertical direction and no movement in the horizontal plane is required, the repair can be completed with a small number of man-hours.

  According to the repair method of the welded portion of the aluminum alloy by this method, the additional fusion welding (repair welding) can be omitted, so that the amount of heat input accompanying the repair work can be minimized. For this reason, it is possible to repair the welded portion of the melt-welded aluminum alloy without decreasing the strength of the welded portion and increasing the amount of deformation around the welded portion.

  For comparison with the repair work according to the present invention, a conventional repair work process will be described. FIG. 4 is a process diagram of repair work by conventional fusion welding. A blow hole 33 may be newly generated in the built-up bead in which the pit 31 generated on the surface of the welded portion of the aluminum alloy members 10 and 20 is repair welded by fusion welding with the welding torch 40. In this case, when the built-up bead 31 is smoothly finished to the surface height of the members 10 and 20, the newly generated blow hole 33 appears as a new pit 33 on the surface of the welded portion. In order to eliminate the newly appearing pit 33, additional repair welding is required.

  In this case, although repair welding is performed according to the same procedure (process), the strength of the welded portions of the aluminum alloy members 10 and 20 and the peripheral portion thereof is decreased due to heat input caused by additional repair welding, or heat input. Large deformation may occur due to expansion due to heat and contraction due to heat removal. Such a decrease in strength and an increase in the deformation amount not only induce deterioration of the appearance (appearance) of the railway vehicle structure, but in some cases, new defects such as cracks in the vicinity of the repair welds of the aluminum alloy members 10 and 20 occur. Since it may be a factor, the conventional repair welding work requires a very high level of skill.

  On the other hand, according to the repair method of the weld part described in Example 1 and Example 2, not only high skill is required, but also the heat input to the weld part accompanying repair welding can be suppressed. Therefore, since the strength reduction and the deformation increase can be reduced, a high-quality railway vehicle structure can be provided.

  Although the present invention has been described by taking the railway vehicle structure as an example, the present invention is not limited to the application to the railway vehicle structure, and is particularly applicable to repair of blowholes and pits generated in a fusion welded portion of an aluminum alloy. is there.

DESCRIPTION OF SYMBOLS 10, 20 ... Aluminum alloy member 30 ... Weld bead 31 ... Pit 32 ... Overlay bead 33 ... Blow hole 34 ... Repair bead 40 ... Welding torch 41 ... Welding arc 50 ... Steel round bar tool 60 ... Aluminum alloy round bar tool 61 ... Aluminum overlay

Claims (8)

In the repair method of repairing the welded part of the metal member,
A build-up bead that covers defects generated on the surface of the weld is formed by fusion welding,
Pressed from the side of forming the KinikuSakari bead previous to said overlay beads, the overlay bead while rotating the rotary tool end surface is smooth at a predetermined rotational speed,
A method for repairing a welded portion, wherein the overlay bead is crushed by the rotary tool. In the repair method of the welding part of Claim 1,
A method for repairing a welded portion, wherein an outer diameter of the rotary tool is larger than a size of the build-up bead. In the repair method of the welding part of Claim 1,
A welding tool repairing method comprising using a rotary tool made of a material having a hardness higher than that of the metal member as the rotary tool. In the repair method of the welding part of Claim 3,
A welding part repairing method using a steel rotary tool as the rotary tool. In the repair method of repairing the welded part of the metal member,
The rotating part presses against a defect generated on the surface of the welded part while rotating the first rotating tool made of the same material as the metal member, thereby forming a built-up part that covers the defect. ,
The rotating part is crushed with the second rotating tool by pressing the rotating part with a second rotating tool made of a material harder than the metal member while rotating. A method for repairing a welded portion characterized by the above. In the repair method of the welding part of any one of Claim 1 to 5,
The method for repairing a welded portion, wherein the metal member is an aluminum alloy. In repairing aluminum alloy welds,
Forming a built-up bead that covers defects generated on the surface of the weld by fusion welding; and
A steel round bar tool having a smooth end face is positioned on the side where the built- up bead is formed, and the steel round bar tool is rotated at a predetermined rotation speed to crush the build-up bead by the end face. While pushing down the end face to the surface of the aluminum alloy,
A method for repairing a welded part of an aluminum alloy, comprising: In repairing aluminum alloy welds,
An aluminum alloy round bar tool having a smooth end face is positioned on the side where the weld part is formed on the defect formed on the surface of the weld part by fusion welding, and the aluminum alloy round bar tool is rotated at a predetermined rotational speed. a step in the end face while rotating against the defects, which forms together with filling the defect by the material of the end face, the cladding portion is moved on the surface of the welded portion of the material of said end face,
A steel round bar tool having a smooth end surface is positioned on the side where the build-up portion is formed, and the steel round bar tool is rotated at a predetermined rotational speed to crush the build-up bead by the end surface. While pushing down the end face to the surface of the aluminum alloy,
A method for repairing a welded part of an aluminum alloy, comprising:

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