JP2001259824A - Method for repairing defect on aluminum cast member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for repairing the defect on an aluminum cast member by which the deformation, residual stress and thermally affected part after repairing are hardly created, the entrapment of inclusions into the jointed part scarcely occurs and any heat treatment after repairing is unnecessary. SOLUTION: This repairing method is performed by repairing the casting defect on the cast member manufactured of the aluminum alloy by a plastic flow method in which, while rotating a tool being harder than this member, the tool is inserted into the defective part. In this process, the tool is inserted to the whole depth of the defective part while gradually inserting the tool from the sound part in this member and the depth of the tool is gradually made shallower after reaching the final position of the defective part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for repairing defects in aluminum and aluminum alloy castings used for parts of automobiles, vehicles, aviation, ships, power generation equipment, elevators, information communication equipment, and the like, and more particularly to a method for repairing the surface of castings and the like. A new plastic flow repair method that makes internal defects sound without melting.

[0002]

2. Description of the Related Art Molten aluminum is easily oxidized to produce alumina, and in an aluminum casting, it is present as an alumina inclusion on the surface and inside, and becomes a defect. On the other hand, an aluminum casting has a large sink in solidification and causes casting defects as shrinkage cavities. Conventionally, these defects have been repaired by welding after removal by a grinder or cutting. The repair of aluminum by welding could be a defect again due to the formation of new oxides and nitrides. Further, deformation and cracking of the casting due to heat at the time of welding are unavoidable and remain as a major problem.

[0003] On the other hand, a friction stir welding method is used for joining a cast aluminum material or a rolled plate material. In Japanese Patent Publication No. 7-505090, a rotary tool made of a material substantially harder than the work is inserted into the joint of the work. There is a method of continuously joining in the joining line direction by moving the tool while rotating it. That is, this is a method of performing friction stir welding (hereinafter referred to as plastic flow welding) utilizing plastic flow of metal due to frictional heat generated between the tool and the workpiece. Unlike the conventional fusion welding such as arc welding, the plastic flow joining method is characterized by solid-state joining that can be joined without melting. Therefore, the heating temperature is low, so that deformation after bonding is small, no harmful structure is generated in the heat-affected zone of the base material, and there are no inclusions such as oxygen substances and nitrogen substances in the bonded part because they are not melted because they are not melted. There is.

On the other hand, aluminum and aluminum alloy castings used for parts of automobiles, vehicles, aviation, ships, power generation equipment, elevators, information communication equipment, etc. are melted, entrapment of inclusions such as oxides and nitrogen during casting, and further solidification. Sometimes shrinkage cavities cause surface defects. Conventionally, these defects have been repaired by welding after removal by grinder or cutting, but they become defects again due to the formation of new oxides and nitrides, and deformation and cracking due to heat during welding are difficult to avoid. Was left as. Here, by applying the plastic flow joining method for repairing defects in an aluminum casting, it is expected that effects such as little thermal deformation after joining and a joining repair portion with little inclusion of inclusions can be obtained.

[0005]

The plastic flow joining method utilizes a plastic flow caused by frictional heat between a rotary tool and a joining material. Unlike the conventional fusion welding method, the heat applied to the joining material is extremely low. Low. For this reason, it is possible to repair a defective portion with almost no thermal deformation and with few residual stresses and heat affected zones. Furthermore, since there is no melting process, a repaired joint without inclusions of inclusions such as aluminum oxide and nitrogen can be obtained. Furthermore, the omission of the heat treatment after joining can be expected.

On the other hand, defects existing on the surface or inside of the conventional aluminum casting are removed by a grinder or cutting and then proceed to a repairing process. However, this plastic flow joining method exists on the surface or inside because a rotating tool is used. If the defect is small, it is possible to continue to repair joining while removing it with this tool.

An object of the present invention is to provide a method for repairing a defect of an aluminum casting member which requires less deformation, residual stress and heat affected zone after repair, less inclusion of inclusions in a joint, and no heat treatment after repair. To offer.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a casting defect of a cast member made of an aluminum alloy is repaired by a plastic flow method by inserting the tool into the defective portion while rotating a tool harder than the member. Repairing method, wherein the tool is gradually inserted from the sound part of the member so as to reach the entire depth of the defective portion, and after the end point of the defective portion, the depth of the tool is gradually reduced. It is characterized by doing.

Aluminum casting is made of Al-Cu, Al-Cu-
Si, Al-Si, Al-Si-Mg, Al-Si-C
u, Al-Si-Cu-Mg, Al-Si-Cu-Ni
-An alloy such as Mg is preferable, which is produced by casting using a mold, a sand mold, and a shell mold, and is characterized in that casting defects on the surface and inside of the casting are repaired by a plastic flow joining method.

When the defect of the casting is small, the plastic flow repair is started as it is. When the defect is large, it is preferable that the repaired part is raised by 0.5 to 3 mm. For this plastic flow repair joining, an aluminum casting containing Si-Mg as a main composition is desirable.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG.
~ 7.5wt%, Mg 0.25 ~ 0.45wt%, C
It is a perspective view which shows the repair method which performed plastic flow repair joining as it was, without deleting the surface defect of the Al alloy casting containing a little u, Zn, Fe and Mn. In this embodiment, a repair joining portion 4 was formed by inserting a tool 3 for plastic flow repair joining into the casting 2 of the aluminum alloy and moving it in the joining direction while rotating. As a result,
The repaired joint was free from defects and had no deformation. The tool 3 is made of tool steel and has a portion to be inserted into the casting at the tip and a shoulder portion larger than the diameter thereof, and is inserted so that the tip does not come out of the casting. For repair, insert the casting gradually from the sound part as shown in the figure, detect the depth in advance, insert the tool 3 according to the depth, and replace the sound part where the defect 2 has passed. In this method, the depth of the tool is gradually reduced again when the tool reaches the surface, and the process ends when the tool reaches the surface.

(Embodiment 2) FIG. 2 shows the same Al alloy as in Embodiment 1.
It is a perspective view which shows the repair method when the surface defect of an alloy casting is large. As shown in the drawing, repair joining by plastic flow was carried out on a portion that was cut away while leaving the defect portion and its periphery slightly larger than the diameter of the tool 3. As shown in FIG. 2, a defect 2 having a defect portion and its periphery left beforehand by cutting a tool 3 for plastic flow repair joining to an aluminum alloy casting 1 by cutting.
And repaired by moving in the joining direction while rotating. As a result, a repaired joint having no defect in appearance and having no deformation was obtained. Also in this embodiment, the first and the last parts of the repair are described in the first embodiment.
It was performed in the same way as.

[0013]

According to the present invention, there is little deformation, residual stress and heat affected zone after repairing, there is little inclusion of inclusions in the joint, and defect repair of aluminum cast members that does not require heat treatment after repairing. It can be performed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a repair method according to the present invention.

FIG. 2 is a perspective view showing a repair method according to the present invention.

[Explanation of symbols]

1 ... aluminum alloy casting, 2 ... defect, 3 ... tool, 4 ... repair joint.

Claims (3)

[Claims] 1. A repair method for repairing a casting defect of a cast member made of an aluminum alloy by a plastic flow method by inserting a tool into the defective portion while rotating a tool harder than the member. Inserting the tool so as to reach the entire depth of the defective portion while gradually inserting the tool from the sound portion of the member, and gradually reducing the depth of the tool after the end point of the defective portion. Repair method for defects of aluminum castings. 2. The method according to claim 1, wherein the aluminum casting is C
A method for repairing a defect in an aluminum casting member, comprising: an alloy containing at least one of u, Si, Mg and Ni. 3. The aluminum casting according to claim 2, wherein the weight of the aluminum casting is 6.5 to 7.5 wt% of Si and 0.25 to 0.4 of Mg.
5% by weight, Cu 5% or less, Zn 6.5% or less, F
Al containing at least one of e1% or less and Mn1.5% or less
A method for repairing a defect of an aluminum casting member, which is made of an alloy casting.