JP2007229791A - Method for repairing casting defect - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for repairing any defect of an aluminum casting even when a defect is found in a final stage in which the aluminum casting is finished to final dimension. <P>SOLUTION: In the method for repairing a casting defect 2 formed in a surface of the casting 1 of aluminum or its alloy by friction stir welding using a rotary tool 10, a filling material 4 made of a metal similar to the casting and having a volume larger than that of a hole 3 formed by drilling a defective part is inserted in the hole 3 so that its head part is protruded from the hole; the rotary tool 10 is pressed against the head part of the filling material 4 and rotated; and the head part of the filling material 4 and its peripheral casting are subjected to friction stir to weld the head part of the filling material 4 with the peripheral casting 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a casting defect repairing method for repairing a defect generated on the surface of a casting of aluminum or an alloy thereof by friction stirring using a rotary tool, and a structure of a portion repaired by the repairing method.

  Aluminum or its alloy castings or die casts (hereinafter abbreviated as aluminum castings) have a large difference in the coefficient of thermal expansion between the solid and liquid aluminum. Cause defects.

  Conventionally, as shown in Patent Document 1 below, as a repair of these defects, friction generated by rotating a tool made of a material substantially harder than an aluminum casting while being rotated and inserted into the surface of the aluminum casting. A repair method has been proposed in which defects on the surface portion of an aluminum casting are removed by friction stir that is softened (plastic flow) by heat.

JP 2002-96158 A

  In the prior art, the defects on the surface are filled by the softness of the aluminum casting itself, so that the portion subjected to the friction stir processing by the rotary tool is recessed. Therefore, it is impossible to repair the defect at the final stage of processing. That is, assuming that the surface is recessed by friction stir processing, it is necessary to prepare a large aluminum casting beforehand, repair defects by friction stir processing, and then grind the entire surface to obtain the required dimensions there were.

  Therefore, in the above prior art, the friction stir processing is performed on the entire surface of the large aluminum casting, and even if it takes time and effort for processing, it is sufficient that the entire surface is dense. Is.

  However, when a defect is found at the final stage after the dimension adjustment, the defect cannot be repaired by the conventional technique.

  Therefore, the object of the present invention has been repaired by a casting defect repairing method and a repairing method capable of repairing a defect occurring in an aluminum casting even when a defect is found at the final stage after dimension adjustment. To provide the structure of the site.

  A feature of the present invention that achieves the above object is to provide a defect repairing method for repairing defects generated on the surface of a casting of aluminum or an alloy thereof by friction stirring using a rotary tool. A filler made of a metal material similar to the casting with a volume larger than the hole is inserted into the hole formed in such a manner that the head protrudes from the hole, and the filler is pressed and rotated with a rotary tool; The filler and the surrounding casting are frictionally stirred to join the filler and the surrounding casting. In this case, the joint part by stirring has a structure formed in the head part or peripheral part of the filler.

  Furthermore, another feature of the present invention that achieves the above object is that the filler is screw-shaped.

  According to the present invention, a hole is machined only at a location where a defect has occurred, and the space of the hole is filled with a filler. It is possible to repair the defect even in the final stage after the alignment, and to provide a repair structure.

  Hereinafter, the present invention will be described according to the embodiments shown in the drawings.

  FIG. 1 is a diagram showing a repair process of a first embodiment in which a defect (nest) generated in an aluminum alloy casting is repaired by friction stirring.

In FIG. 1A, reference numeral 1 denotes a portion where a defect (nest) 2 of the aluminum alloy casting 1 is present.
As shown in FIG. 1B, the defect 2 is removed by drilling with a drill or the like to form a cylindrical drill hole 3.

  Next, as shown in FIG. 1 (c), the hole 3 has the same or similar alloy composition as that of the aluminum alloy casting 1, good plastic fluidity, and the same shape as the hole 3, with a slight diameter. A small solid cylindrical filler 4 is inserted. The length of the filler 4 is a little longer than the depth of the drill hole 3, and therefore has a volume larger than the space volume of the drill hole 3. Furthermore, the rotary tool 10 that is slightly larger than the diameter of the filler 4 and harder than the aluminum alloy casting 1 or the filler 4 is disposed on the upper portion so that the respective axes are concentric with the filler 4. The rotating device is appropriately selected and used.

  Thereafter, a pressing force is applied to the head of the filler 4 while rotating the rotary tool 10, and the lower end of the rotary tool 10 contacts the upper surface of the head of the filler 4 and the peripheral portion of the hole 3 in the aluminum alloy casting 1. Lower to the position where

  Then, frictional heat is generated by contact between the rotary tool 10 and the filler 4, the upper surface of the filler 4 and the peripheral portion of the hole 3 in the aluminum alloy casting 1 are softened, and the rotational force from the rotary tool 10 is further increased. As shown in FIG. 1 (c), the stir weld 4a in which the filler 4 and the aluminum alloy casting 1 are in a plastic flow state is formed at the head of the filler 4 as shown in FIG.

  Next, after confirming that the stir weld 4a has been generated, when the rotary tool 10 is pulled up, the aluminum alloy casting 1 and the filler 4 are bonded to the joint layer (joint) in which the stir weld 4a is solidified at the opening of the drill hole 3. Part) 4b, and the repair is completed.

  When the surface 4c of the bonding layer 4b is raised from the surface of the aluminum alloy casting 1, a finishing process such as surface grinding is performed on the bonding layer 4b so as to have the same surface position as the aluminum alloy casting 1. Smooth the surface.

  When the length of the filler 4 is equal to or slightly shorter than the depth of the drill hole 3, the filler 4 has a volume smaller than the space volume of the drill hole 3, and the bonding layer 4 b may be recessed from the surface of the aluminum alloy casting 1. Come out. Therefore, by using a filler 4 having a volume larger than the space volume of the drill hole 3, if the surface of the bonding layer 4b is the same surface position as the aluminum alloy casting 1 or a raised portion 4c is formed, It is not necessary to cut the entire surface of the aluminum alloy casting 1 by finishing only the bonding layer 4b at the same surface position as that of the aluminum alloy casting 1, and it is possible to repair casting defects at the final stage.

  Even when it is considered that the formation of the bonding layer 4b is insufficient, the outer dimension of the aluminum alloy casting 1 is not changed, so that the processing from FIG. 1A can be performed again.

  Since partial repair for the casting defect portion is sufficient and heating of the aluminum alloy casting 1 can be minimized, deterioration of characteristics such as hardness and strength caused by the heat treatment can be minimized.

  The above-described steps may be performed in an inert atmosphere or under reduced pressure so that corrosion does not progress inside the drill hole 3.

According to the above configuration, the structure of the portion repaired by the casting defect repairing method of repairing the defect 2 generated on the surface of the casting of aluminum or its alloy by friction stirring using the rotary tool 10,
A filler 4 made of a metal material similar to the casting with a volume larger than the hole is inserted into a hole formed by drilling the defective portion, and the head protrudes from the hole. By being pressed against the head of the filler 4 and rotated, the head of the filler 4 and the surrounding casting are frictionally stirred to form a joint 4b that joins the head of the filler 4 and the surrounding casting. The structure of the site | part repaired by the repair method of a casting defect characterized by having the structure formed in the head of the filler 4, especially the filler 4 is formed.

  FIG. 2 is a diagram showing a repair process in a second embodiment in which a defect (nest) generated in an aluminum alloy casting is repaired by friction stirring.

  FIG. 2A shows a defect (nest) 2 existing in the aluminum alloy casting 11 by removing the defect by drilling with a drill or the like as shown in FIG. Furthermore, a state where the filler 14 having a screw shape is attached to the tool chuck 20 of the machine tool shown in FIG. 2B and the tip of the filler 14 faces the opening of the drill hole 13 is shown. Yes.

  The material of the filler 14 is similar to the alloy component of the aluminum alloy casting 11, has good plastic fluidity, and is slightly harder than the aluminum alloy casting 11. The shape of the filler 14 is the same as that of the thread valley diameter and the diameter of the drill hole 3, and the length thereof is slightly longer than the sum of the length of the part where the machine tool chucks the tool and the depth of the drill hole 3. . The filler 14 is arranged so that each axis is concentric with the drill hole 13.

  Next, as shown in FIG. 2B, the filler 14 is rotated by the tool chuck 20 of the machine tool instead of the rotating tool so that the direction of the screw 14 is opposite to the direction of the screw (left rotation if it is a right screw). While applying a pressing force, the tip end surface of the filler 14 is lowered to a position where it contacts the bottom of the drill hole 13. At this time, frictional heat is generated by contact between the filler 14 and the drill hole 1, and the peripheral portion of the drill hole 13 on the soft side is first softened by frictional heat due to the frictional heat, and the peripheral portion of the filler 14 is filled with the filler. The stir welded portion (plastic fluid metal) 11a in which the material 14 and the aluminum alloy casting 11 are in a plastic flow state is generated.

  Depending on the direction of the screw of the filler 14, the plastic fluid metal 11 a generates a flow not only in the rotation direction but also in the vertical direction, that is, in the drill hole 13.

  Next, as shown in FIG. 2 (c), the screw portion of the hard filler 14 is softened with a slight delay, and the plastic flow metal 11a generated in the vertical direction is received and stirred together. As a result, a mixed layer 15 of the thread portion of the filler 14 and the plastic fluidized metal 11a is generated.

  The hole 13 is filled with the plastic fluidized metal 11a and the mixed layer 15, and when the rotation is stopped, the frictional heat is not generated, so that the mixing part 15 is solidified. As a result, the aluminum alloy casting 11 and the filler 14 are mixed with the mixing part 15. The solidified joining layer 15a and the joining layer (joining part) 11b in which the plastic fluid metal 11a solidifies are integrated as a whole.

  Next, as shown in FIG. 2 (d), the filler 14 is removed from the chuck, and removal processing is performed on the chuck portion of the filler 14 to smooth the upper surface of the filler 14 and its surroundings, thereby completing the repair. .

  In this embodiment, the chuck portion provided in the filler 14 is omitted, the filler 14 is pushed into the drill hole 13 by the chuck, the tool is changed from the chuck to the rotary tool, and the filler 14 is further rotated by the rotary tool. The same bonding layer 11b and bonding layer 15a can be formed even if they are pushed in. In this case, only the chuck portion provided in the filler 14 may be small, and the surface finishing after joining becomes simple.

According to the above configuration, the structure of the portion repaired by the casting defect repairing method of repairing the defect 2 generated on the surface of the casting of aluminum or its alloy by friction stirring using the rotary tool 10,
A filler 14 made of a metal material similar to the casting in a volume larger than the hole is inserted into a hole (drilled hole 13) formed by drilling the defective part with its head protruding from the hole, When the rotary tool (tool chuck 20) is pressed against the filler 14 and rotated, the head of the filler 14 and the surrounding casting are frictionally stirred to join the peripheral part of the filler 14 and the surrounding casting. The structure of the site repaired by the casting defect repairing method, wherein the joint 11b is formed, is formed.

It is the figure which showed the process of 1st embodiment used as the repair method of this invention casting defect. It is the figure which showed the process of 2nd embodiment used as the repair method of this invention casting defect.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Aluminum alloy casting, 2 ... Defect (nest), 3 ... Drill hole (hole), 4,14 ... Filler, 4a ... Stir-joint part, 4b, 11b ... Joining layer (joint part), 10 ... Rotary tool, 20 ... Tool chuck.

Claims (6)

In the repairing method of casting defects, repairing defects generated on the surface of the casting of aluminum or its alloy by friction stirring using a rotating tool,
A filler made of a metal material similar to the casting with a volume larger than the hole is inserted into a hole formed by drilling a defective part, and the head protrudes from the hole. A method for repairing a casting defect, wherein the filler and the surrounding casting are joined by frictional stirring of the filler head and the surrounding casting by pressing and rotating the filler.   2. A method for repairing a casting defect according to claim 1, wherein the filler is a screw.   The method for repairing a casting defect according to claim 1, wherein the surface of the joint portion obtained by joining the head portion of the filler and the surrounding casting by friction stirring is subjected to surface grinding with the same surface position as the casting. Repair method for casting defects. A structure of a part repaired by a casting defect repairing method for repairing a defect generated on the surface of a casting of aluminum or an alloy thereof by friction stirring using a rotary tool,
A filler made of a metal material similar to the casting with a volume larger than the hole is inserted into a hole formed by drilling the defective portion, and the head protrudes from the hole. A casting defect repairing method is characterized in that a joint is formed by frictionally stirring the filler head and the surrounding casting so as to join the filler and the surrounding casting. The structure of the part repaired by.   In the structure of the portion repaired by the casting defect repairing method according to claim 4, the joint is repaired by a casting defect repairing method, wherein the joint is formed at a head portion or a peripheral portion of the filler. Structure of the affected part.   In the structure of the portion repaired by the casting defect repairing method of claim 4, the same surface position as the casting with respect to the joint surface of the joint where the filler head and the surrounding casting are joined by friction stirring. The structure of the site | part repaired by the repair method of the casting defect characterized by having the structure where the surface grinding to which was given was given.

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