JP2003001393A - Relining method for hollow member with wear-resistant layer on inner circumferential surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which enables relining of a hollow member with a wear-resistant layer on an inner circumferential surface such as an injection sleeve of a die-casting machine or the like. SOLUTION: The inner circumferential surface of the injection sleeve 1 (made of SKD 61) is scraped to remove a defective portion. A Ni-based self-fluxing alloy is thermal-sprayed on an outer surface of a pipe 3 with a thin wall thickness and then re-melted. The outer surface of the self-fluxing alloy layer 2 is machined so that its outer diameter becomes a little smaller than an inner diameter of the injection sleeve body 1. The pipe 3 with the thin wall thickness covered by the self-fluxing alloy layer 2 is inserted inside the injection sleeve body 1, and further an insert core 4 (made of SUS 304) is inserted inside the pipe 3. The whole work-piece is heated to 1050 deg.C and held for 20 min. in a vacuum furnace. The self-fluxing alloy layer 2 is pressed against the injection sleeve body 1 and jointed due to the difference of thermal expansion rate between the injection sleeve body 1 and the insert core 4. After taking out the insert core 4, the pipe 8 with the thin wall thickness is removed and the inside surface of the self-fluxing alloy layer 2 is finished to the designated dimension by machining.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for remanufacturing a hollow member having an abrasion resistant layer on its inner peripheral surface. The invention is particularly
The present invention relates to a method for regenerating an injection sleeve that serves both as a molten metal receiver and a pressure cylinder in a die casting machine for aluminum alloys.

[0002]

2. Description of the Related Art Conventionally, in a die casting machine, an injection sleeve which functions as a molten metal receiver and a pressure cylinder has been
Alloy tool steels such as IS-SKD61 are used.
The injection sleeve made of SKD61 has been widely used since it has heat resistance and is relatively inexpensive.

However, the SKD61 injection sleeve is
Corrosion resistance to molten aluminum, so-called melt damage resistance, is not always sufficient, and melt damage occurs in the lower part of the hot water supply port relatively early, often making it unusable. Therefore, the inner peripheral surface of the injection sleeve is made of a material excellent in wear resistance and melting resistance against molten aluminum (for example, Ni-based self-fluxing alloy,
An injection sleeve coated with a Co-based self-fluxing alloy) has been developed.

Even such a coating layer is flawed due to galling, melting damage and the like. When such a flaw grows and the injection sleeve becomes unusable, there is a demand to restore the flawed coating layer and regenerate the injection sleeve.

However, in order to regenerate the injection sleeve,
After cutting the inner peripheral surface of the injection sleeve to remove the old coating layer, the coating layer must be re-bonded to the inner peripheral surface of the injection sleeve using the HIP method. However, since the injection sleeve has openings such as a hot water inlet,
The structure makes it difficult to apply pressure during processing. Therefore, it was practically difficult to regenerate the injection sleeve.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the conventional method for repairing the coating layer on the inner peripheral surface of the injection sleeve, and the object of the present invention is to provide an inner peripheral surface. It is an object of the present invention to provide a method for regenerating a hollow member having a wear resistant layer on its surface.

[0007]

A method for remanufacturing a hollow member having an abrasion resistant layer on the inner peripheral surface of the present invention is a method for remanufacturing a hollow member having an abrasion resistant layer on the inner peripheral surface. The inner peripheral surface of the hollow member is removed by machining until the damaged portion generated on the inner peripheral surface is removed, and (b) a thin-walled cylinder having an outer diameter dimension smaller than the initial inner diameter dimension of the hollow member. A cylindrical member is prepared, (c) the Ni-based self-fluxing alloy or the Co-based self-fluxing alloy is sprayed on the outer peripheral surface of the tubular member, and then the self-fluxing alloy layer is remelted, and (d) The outer periphery of the tubular member is processed to have an outer diameter dimension slightly smaller than the inner diameter dimension of the hollow member after the inner peripheral surface is removed, and (e) the tubular member is placed inside the hollow member. Inset, (f) Furthermore,
A core made of a material having a thermal expansion coefficient larger than that of the material forming the base material portion of the hollow member is fitted inside the tubular member, and (g) the member assembled in this manner, By heating to a temperature at which a part of the self-fluxing alloy layer is melted and a liquid phase is generated, the self-fluxing alloy layer is pressed against the hollow member due to the difference in thermal expansion coefficient between the hollow member and the core. Together with joining the two,
(H) After removing the core from the member thus obtained, the inner peripheral surface is machined to remove the tubular member and the inner peripheral surface to which the self-fluxing alloy layer is joined. Is finished to a predetermined size.

According to the method of the present invention, since the self-fluxing alloy layer is bonded to the inner peripheral surface of the hollow member by utilizing the difference in the coefficient of thermal expansion between the hollow member and the core, the HIP method is used. Even if it is a hollow member having a shape that cannot be applied (for example, an injection sleeve of a die casting machine having an opening formed in a side wall), a wear resistant layer can be bonded to its inner peripheral surface. it can.

For example, the self-fluxing alloy layer is made of Si: 0.5.
wt% or more and 8.0 wt% or less, Mo: 5 wt% or more 37
It is a Ni-based self-fluxing alloy containing not more than wt% and B: not less than 0.6 wt% and not more than 3.2 wt%.

Preferably, the material forming the core is
The coefficient of thermal expansion is 1.25 times or more and 2.0 times or less that of the material forming the base material portion of the hollow member.

This is about the size of an injection sleeve of a die casting machine for aluminum alloys (for example, inner diameter: 50).
When the difference in the coefficient of thermal expansion is 1.25 times or less, the difference in the expansion amount between the hollow member and the core when heated is small, so that the self-melting on the inner peripheral surface of the hollow member occurs. This is because the force for pressing the alloy layer is insufficient and the alloy layer cannot be firmly bonded. On the other hand, when the difference in the coefficient of thermal expansion is double or more, the difference between the inner diameter dimension of the hollow member and the outer diameter dimension of the core when heated becomes small, so that the thickness of the self-fluxing alloy layer after joining is reduced. This is because the thickness becomes thin and it becomes difficult to secure the product size and wear resistance.

For example, when the base material portion of the hollow member is made of carbon steel or alloy steel, austenitic stainless steel such as SUS304 can be used as the material of the core.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an example in which the method of the present invention is applied to the reproduction of an injection sleeve of a die casting machine will be described.
This will be described with reference to the drawings.

Regeneration of the injection sleeve of a die casting machine for an unusable aluminum alloy was carried out by the following procedure.

(A) As shown in FIG. 1, the injection sleeve 1
The inner peripheral surface of was cut until the damaged portion generated on the inner peripheral surface was removed (may be other machining such as grinding). A hot water supply port 6 (opening) is provided on the side wall of the injection sleeve 1.

(B) The inner and outer surfaces of the S45C thin-walled pipe 3 were machined to the dimensions shown in FIG.

(C) The core 4 made of SUS304 was manufactured by machining to have the dimensions shown in FIG. Boron nitride (solid lubricant) was applied to the outer periphery of the core 4 and dried.

(D) Ni is formed on the outer peripheral surface of the thin pipe 3.
The base self-fluxing alloy was sprayed. The composition of the Ni-based self-fluxing alloy used in this example is Si: 4.6 wt%, M
o: 20 wt%, B: 3.1 wt%, Ni: balance.

(E) Next, the self-fluxing alloy layer was remelted. The thickness of the self-fluxing alloy layer after remelting was 2.5 mm.

(F) The outer circumference of the self-fluxing alloy layer 2 was machined to the dimensions shown in FIG. The outer diameter of the self-fluxing alloy layer 2 after machining is set to a dimension (-0.2 mm) slightly smaller than the inner diameter (Fig. 1) of the injection sleeve body 1 after the inner peripheral surface is cut. Has been done.

(G) As shown in FIG. 5, a thin pipe 3 having an outer periphery covered with a self-fluxing alloy layer 2 was fitted inside the injection sleeve body 1, and a core 4 was fitted inside the thin pipe 3.

(H) The thus-assembled product was heated to 1050 ° C. in a vacuum furnace and held for 120 minutes. By heating in this manner, the self-fluxing alloy layer 2 was pressed against the injection sleeve body 1 due to the difference in the thermal expansion coefficient between the injection sleeve body 1 and the core 4, and the two were bonded to each other. Incidentally, the thermal expansion coefficient of the alloy tool steel SKD61 used for the injection sleeve body 1 in this example is 11.7 × 10 ⁻⁶ / ° C., and the thermal expansion coefficient of SUS304 used as the core 4 is 17 .3 × 10 ^-6 / ° C
Is.

(I) After removing the core 4 from the thus obtained product, the inner peripheral surface is machined to the dimensions shown in FIG. 6 to remove the thin pipe 3 and the self-fluxing alloy layer. The inner peripheral surface to which 2 was joined was finished to a predetermined size. Thus, the regeneration of the injection sleeve was completed.

[0024]

According to the method for regenerating a hollow member of the present invention,
Since the self-fluxing alloy layer is joined to the inner peripheral surface of the hollow member by utilizing the difference in coefficient of thermal expansion between the hollow member and the core, it is a hollow member having a shape to which the HIP method cannot be applied. However, the wear resistant layer can be bonded to the inner peripheral surface of the wear resistant layer.

When the method of the present invention is applied to remanufacturing the injection sleeve of a die casting machine, the cost required for the remanufacturing is about 5 times the cost for newly manufacturing the injection sleeve.
0% is enough. Therefore, according to the method of the present invention, the running cost of the die casting machine can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a procedure of regenerating an injection sleeve based on the method of the present invention.

FIG. 2 is a diagram illustrating a procedure for reproducing an injection sleeve based on the method of the present invention.

FIG. 3 is a diagram illustrating a procedure for reproducing an injection sleeve based on the method of the present invention.

FIG. 4 is a diagram illustrating a procedure for reproducing an injection sleeve based on the method of the present invention.

FIG. 5 is a diagram illustrating a procedure for reproducing an injection sleeve based on the method of the present invention.

FIG. 6 is a view showing the shape of an injection sleeve reproduced according to the method of the present invention.

[Explanation of symbols]

1 ... Injection sleeve body, 2 ... self-fluxing alloy layer, 3 ... Thin-walled pipe, 4 ... 6 ... Hot water supply port.

Claims (4)

[Claims] 1. A method of remanufacturing a hollow member having an abrasion resistant layer on the inner peripheral surface, comprising: (a) machining the inner peripheral surface of the hollow member until a damaged portion on the inner peripheral surface is removed. (B) preparing a thin-walled tubular member having an outer diameter smaller than the initial inner diameter of the hollow member, and (c) a Ni-based self-fluxing alloy on the outer peripheral surface of the tubular member. Alternatively, after spraying a Co-based self-fluxing alloy, the self-fluxing alloy layer is re-melted, and (d) the outer circumference of the tubular member is set to the inner diameter of the hollow member after the inner peripheral surface is removed. The outer diameter of the hollow member is slightly smaller than that of the hollow member. (E) The tubular member is fitted inside the hollow member. (F) Further, the base material portion of the hollow member is placed inside the tubular member. Insert a core made of a material having a larger coefficient of thermal expansion than the constituent material, and (g) The member assembled by heating the self-fluxing alloy layer due to the difference in coefficient of thermal expansion between the hollow member and the core by heating to a temperature at which a part of the self-fluxing alloy layer is melted and a liquid phase is generated. While pressing against the hollow member and joining them together, (h) after removing the core from the member thus obtained, the inner peripheral surface is machined to remove the tubular member. In addition, the inner peripheral surface to which the self-fluxing alloy layer is bonded is finished to a predetermined size, and the hollow member having a wear resistant layer on the inner peripheral surface is regenerated. 2. The self-fluxing alloy layer comprises Si: 0.5 wt%.
Above 8.0 wt%, Mo: above 5 wt% and above 37 wt%
The method for regenerating a hollow member having an abrasion resistant layer on the inner peripheral surface according to claim 1, wherein B is a Ni-based self-fluxing alloy containing B: 0.6 wt% or more and 3.2 wt% or less. 3. The material forming the core has a coefficient of thermal expansion of 1.2 times that of the material forming the base material portion of the hollow member.
5. The ratio is 5 times or more and 2.0 times or less.
A method for regenerating a hollow member having an abrasion resistant layer on the inner peripheral surface thereof according to item 4. 4. The inner peripheral surface according to claim 3, wherein the base material portion of the hollow member is made of carbon steel or alloy steel, and the core is made of austenitic stainless steel. A method for regenerating a hollow member having a wear-resistant layer on its surface.