JPH0693306A - Production of sliding parts, molded article for sliding parts and sliding parts obtained by production method of the same - Google Patents

Abstract

PURPOSE:To easily produce the sliding part having any shape and size by forming a composite molded article with an inner forming material consisting of a sinterable grain and a thermally removable binder and having a large contraction coefficient after sintering and an outer forming material having a small contraction coefficient. CONSTITUTION:A sinterable grain and a thermally removable resin binder are used to prepare an inner forming material A having a large contraction coefficient after sintering and an outer Forming material B having a small contraction coefficient after sintering. The molten material A is injected into an inner formed body forming die 12 by using an injector 21 to form an inner formed material 3. The inner formed material 3 is placed in an composite formed material forming die 13, and the molten material B is injected into the die 13 from an injector 22 to form a composite material 5. The composite material 5 is heat-treated to remove the resin binder to produce a sliding part 8 having a gap 81 between the inner sintered body 6 and an outer sintered body 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding part manufacturing method, a molded part for a sliding part, and a sliding part obtained by a sliding part manufacturing method.

[0002]

2. Description of the Related Art As a sliding part, there is one having a shape as shown in FIG. 6, for example. Conventionally, in manufacturing such a sliding part, an outer part and an inner part are separately manufactured, and For the inner part, the sliding part body and each end part are made separately, after the outer part is inserted through the sliding part body of the inner part, each end part is attached to both ends of the sliding part body. It is being done.

Therefore, a large number of individual molding and processing steps are required to obtain the final sliding component, and it is necessary to secure a sufficient size for engaging the sliding portion main body and the end component. Therefore, the size of the sliding component itself is limited, and it is impossible to manufacture a minute sliding component.

[0004]

DISCLOSURE OF THE INVENTION The present invention is directed to a method for producing a sliding component and a molded product for a sliding component, which can easily produce a sliding component of any shape and size by using the technique of composite injection molding. To provide.

[0005]

Thus, according to the invention of "Claim 1" of the present application, "so that the sinterable particles and the resin binder removable by heating have a predetermined shrinkage ratio after sintering. Inner molding material consisting of blended kneaded material
(A), a kneaded material of sinterable particles and a resin binder that can be removed by heating, and the shrinkage rate after sintering is the inner molding material
An outer molding material (B) set to be smaller than (A) is prepared, and the inner molding material (A) is injection-molded to form an inner molding (3).
Then, the outer molding material (B) is injection-molded around the surface to be the sliding surface of the inner molding (3) to obtain the inner molding (3) and the outer molding (4). After obtaining the joined composite molded article (5), by subjecting the composite molded article (5) to heat treatment,
The resin binder in the composite molded product (5) is removed, the sinterable particles are sintered, and the sintered product (6) of the inner molded product and the sintered product (7) of the outer molded product are removed. A method of manufacturing a sliding component, which comprises forming a gap (81).

In the manufacturing method of the present invention, the inner molding material is a kneaded product of sinterable particles and a resin binder. The composition of the sinterable particles and the resin binder in the kneaded product is adjusted according to the shrinkage ratio between the inner molded product (3) and the sintered body (6) obtained by sintering the inner molded product (3). As the sinterable particles, granular particles that are hard and can be sintered at a predetermined temperature are used, and metal fine particles, ceramic fine particles, and the like are preferably used. The size of the sinterable particles is such that they can smoothly flow through the sprue, runner, etc. of the composite molding machine and do not hinder the injection, and can be adapted to the desired size of the sliding member to be the final product. Is selected.

When the resin binder is kneaded with the sinterable particles, the resin binder maintains fluidity so as not to impair the function of injection molding, and a heating atmosphere until the sinterable particles are sintered. What can be completely vaporized and removed below is used. As such a resin binder, those known in the art can be used as they are.

In the manufacturing method of the present invention, an outer molding material
As (B), a kneaded product of sinterable particles and a resin binder is used. As the sinterable particles and the resin binder, the same ones as those used for the above-mentioned inner molding material (A) are used. However, the mixture of the sinterable particles and the resin binder in the outer molding material (B) is such that the shrinkage rate after sintering is smaller than that of the inner molding material (A).

The above inner molding material (A) and outer molding material (B)
In each case, a sufficient amount of sinterable particles to secure each intended shape and fluidity to the extent that this amount of sinterable particles can be uniformly dispersed and the function of the injection device is not impaired are provided. It is prepared from a sufficient amount of resin binder. Further, it is preferable that the molding materials (A) and (B) are kneaded so that the sinterable particles are uniformly dispersed in the resin binder.

In the practice of the manufacturing method of the present invention, at least two metal molds, an inner molded product mold (12) and a composite molded product mold (13), are used to mold a so-called intermediate product. At least two injection devices (21) having a mold and individually melting and injecting the inner molding material (A) and the outer molding material (B)
A composite injection molding machine having (22) is preferably used. The mold (13) for the composite molded article has a mold cavity for accommodating the inner molded article (3) and capable of accommodating the outer molded article (4) around the intended surface of the inner molded article. Is used.

In the above composite injection molding machine, first, the melt of the inner molding material (A) is injected into the inner molding die (12) and subjected to molding conditions to mold the inner molding (3). Then, the inner molded product (3) is housed in the mold cavity in the composite molded product mold (13), and the melt of the outer molding material (B) is injected into the mold cavity to subject it to molding conditions, A composite molded product (5) is obtained in which the outer molded product (4) is joined to the periphery of the molded product (3). In the above composite molding, when the outer molding material (B) is injection-molded on the outside of the inner molding (3), if the timing is set to be long and the weld is forcibly formed, sintering which will be described later is performed. It is preferable in that the sliding gap can be easily formed during processing.

The composite molded article obtained above is the molded article for sliding parts of the invention according to the "claim 2" of the present application.

The above-mentioned composite molded product (5) is subjected to a heat treatment under the condition that the sinterable particles contained therein can be sintered. In this heating process, the resin binder is removed (hereinafter, degreasing). Is said). It is preferable that the resin binder be degreased quickly, and from this point, a vacuum sintering furnace is preferably used. An example of heating conditions when using such a vacuum sintering furnace is 500 ° C. and about 50 hours.

By the above heat treatment, the inner molded product (3) and the outer molded product (4) are degreased and their volumes are slightly shrunk, and thereafter the sinterable particles contained in each molded product are separated from each other. It is obtained as a combination of a so-called inner porous body and outer porous body which are bonded while maintaining the shape of each molded product. In this case, the density of the inner porous body is smaller than the density of the outer porous body.
When the combination of the above-mentioned porous bodies is subjected to sintering conditions, each porous body is sintered and welded to shrink, and the inner sintered body
It is a combination of (6) and the outer sintered body (7). In the above-mentioned sintering, since the shrinkage rate when becoming the outer sintered body (6) is set to be smaller than the shrinkage rate when becoming the inner sintered body, it is formed in the composite molded product due to the difference in these shrinkage rates. The bonded surfaces that have been separated are separated and a gap (81) is created.

[0015]

According to the present invention, an inner molding material comprising a kneaded product of sinterable particles and a resin binder removable by heating
After (A) is injection-molded to form the inner molded product (3), sinterable fine particles and a resin binder that can be removed by heating are provided around the sliding surface of the inner molded product (3). By molding the outer molding material (B) whose shrinkage rate after sintering is set to be smaller than the inner molding material (A) in the kneaded product with A composite molded article (5) in which the molded article (4) is joined is obtained.

Next, when the composite molded product (5) is heat-treated, the sinterable particles in the composite molded product (5) are sintered and the resin binder is removed, and the entire composite molded product (5) is Although the volume will shrink, the volume shrinkage rate when the inner molding (3) changes to its sintered body (6) is the outer molding.
Since (4) is larger than the volumetric shrinkage rate when changing to the sintered body (7), a gap (81) is formed between the inner sintered body (6) and the outer sintered body (7). Will occur. This results in a sliding component in which the outer component is slidably engaged with a predetermined portion of the inner component, which is obtained in one piece rather than an assembly product from small components.

[0017]

The present invention will be described in detail below with reference to the illustrated embodiments, but the present invention is not limited thereto. Example 1 FIG. 1 is a schematic view of a main part of an example of a composite injection molding apparatus used in the manufacturing method of the present invention. In the figure,
(1) is a mold device having a rotation mechanism, and (2) is an injection mechanism. The mold device (1) is provided with an inner molded product mold (12) and a composite molded product mold (13) on a mold rotating mechanism (11). Further, the injection mechanism (2) is provided with an injection device (21) in which the inner molding material (A) is melted and filled and an injection device (22) in which the outer molding material (B) is melted and filled. There is.

In this embodiment, the inner molding material (A) was
56% SUS fine particles as sinterable particles, and resin binder 44
%, And the mixture is kneaded to be uniform, and the outer molding material (B) contains the same SUS as above.
A mixture in which 60% of fine particles and 40% of a resin binder similar to the above are mixed and kneaded to be uniform is used.

In the above construction, first, in the first injection step, as shown in FIG. 1, the melt of the inner molding material (A) is injected into the inner molding die (12) and then subjected to molding conditions. To mold the inner molding (3).

In the next second injection step, as shown in FIG. 2, the inner molding (3) obtained in the first injection step is transferred to the mold cavity in the composite molding die (13). Then, in this state, the melt of the outer molding material (B) is injected and subjected to molding conditions. When the outer molding material (B) is injected into the inner molding (3) for molding, the timing is set long and the weld is formed. At this time, the first injection step is concurrently performed on the inner molding die (12).

When the second injection step is completed, the molds (12) and (13) are opened as shown in FIG.
The inner molded product (3) is taken out from 2), and the composite molded product (5) in which the outer molded product (4) is joined around the inner molded product (3) from the mold for composite molded product (13). Is taken out. A schematic front view of the composite molded product (5) is shown in FIG. 4, and a schematic cross-sectional view taken along line XX thereof is shown in FIG.

Composite molded article (5) obtained as described above
When subjected to heating conditions of about 500 ° C. for about 50 hours in a vacuum incinerator (not shown), the resin binder in the composite molded article (5) is degreased and its volume shrinks slightly. The SUS fine particles remaining in each molded product area bond to each other at the boundary of the forcibly formed weld line, and a combination of a low-density inner porous body and a high-density outer porous body is obtained. To be Further, when the porous body combination is heat-treated under the condition that each SUS fine particle is sintered, each porous body undergoes volume contraction into a sintered body, but the inner sintered body of the inner porous body (6 ) Is larger than that of the outer porous body to the outer sintered body (7), the difference in the shrinkage causes the joining surface formed in the composite molded article to separate, resulting in a gap (81). Will occur. After all, as shown in FIG. 6, the inner sintered body obtained by sintering while shrinking as a whole is obtained.
Thus, the sliding component (8) is obtained in which the sliding gap (81) is held without the (6) and the outer sintered body (7) being welded.

As is clear from the above, according to the manufacturing method of the present invention, the inner sintered body (6) has both end portions as shown in FIG.
There is a bulge in (61) and the sliding part body (62) is between the both ends.
Even if it is a structure having the outer sintered body (7) inserted around the sliding body (62), the inner sintered body (6) is ) And each end portion (61) without being divided and can be molded as an integrated body. Moreover, since the inner sintered body (6) and the outer sintered body (7) can be molded together, a very small sliding component can be manufactured.

[0024]

According to the present invention, parts which could not be produced by the conventional processing method can be easily produced. In addition, since it can be manufactured by injection molding, it can be provided in large quantities and at low cost. Further, since minute sliding parts can be manufactured and the shrinkage rate of each material can be freely changed, it is easy to set any sliding gap.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of an example of a composite injection molding machine used in a manufacturing method of the present invention.

FIG. 2 is a schematic view of a main part for explaining an injection / filling state of a molding material in a second injection step.

FIG. 3 is a schematic view of a main part for explaining how to take out an inner molded product and a composite molded product.

FIG. 4 is a schematic front view of a composite molded product.

5 is a schematic cross-sectional view taken along line XX of FIG.

FIG. 6 is a schematic front view of sliding parts.

FIG. 7 is a schematic sectional view taken along line XX of FIG.

[Explanation of symbols]

(1)… Molding device (2)… Injection mechanism (3)… Internal molded product (4)… Outer molded product (5)… Composite molded product (6)… Inner sintered body (7)… Outer sintered body (8)… Sliding parts (11)… Mold rotating mechanism (12)… Inner molding die (13)… Composite molding die (21) (22)… Injection device (A)… Inner molding Material (B): Outer molding material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B29C 67/04 7344-4F B29K 105: 16

Claims (3)

[Claims] 1. An inner molding material comprising a kneaded material in which sinterable particles and a resin binder which can be removed by heating are blended so as to have a predetermined shrinkage ratio after sintering; An outer molding material having a shrinkage rate after sintering with a kneaded material with a removable resin binder is set to be smaller than the inner molding material, and the inner molding material is injection-molded to obtain an inner molding, Then, the outer molding material is injection-molded around the surface to be the sliding surface of the inner molding to obtain a composite molding in which the inner molding and the outer molding are joined together. Is heat-treated to remove the resin binder in the composite molded article and sinter the sinterable particles to form a gap between the sintered body of the inner molded article and the sintered body of the outer molded article. A method for manufacturing a sliding component, which comprises forming. 2. An inner molding material composed of a kneaded material in which sinterable particles and a resin binder which can be removed by heating are blended so as to have a predetermined shrinkage ratio after sintering; The kneaded material with a removable resin binder is composed of an outer molding material whose shrinkage rate after sintering is set smaller than the inner molding material, and the inner molding material is formed into an inner molding by injection molding, Molded article for sliding part formed by injection molding the above-mentioned outer molding material around the surface to be the sliding surface of the outer-inner molded article to form a composite molded article in which the inner molded article and the outer molded article are joined . 3. A sliding component obtained by the manufacturing method according to claim 1.