JP3327578B2 - Sliding part manufacturing method, molded article for sliding part, and sliding part obtained by sliding part manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art There are sliding parts having a shape as shown in FIG. 6, for example. Conventionally, in manufacturing such sliding parts, an outer part and an inner part are separately manufactured, and For the inner part, make the sliding part main body and each end part separately from each other, insert the outer part through the sliding part main body of the inner part, then attach each end part to both ends of the sliding part main body and make it That being done is done.

Therefore, a number of individual forming steps and processing steps are required until a final sliding part is obtained, and it is necessary to ensure that the sliding part main body and the end part are large enough to be engaged. Therefore, the size of the sliding component itself is limited, and it has not been possible to manufacture a minute sliding component.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a method for manufacturing a sliding part and a molded product for a sliding part, which can easily manufacture a sliding part of any shape and size by using the technique of composite injection molding. Is to provide.

[0005]

Thus, according to the invention of claim 1 of the present application, "the sinterable particles and the resin binder which can be removed by heating have a predetermined shrinkage ratio after sintering. Inner molding material consisting of compounded kneaded material
(A), the shrinkage after sintering in the kneaded material of sinterable particles and a resin binder that can be removed by heating, the inner molding material
(A) is prepared to be smaller than the outer molding material (B), and the inner molding material (A) is subjected to injection molding to form an inner molding (3).
Then, the outer molding material (B) is injection-molded around a surface serving as a sliding surface of the inner molding (3), so that the inner molding (3) and the outer molding (4) are formed. After obtaining the joined composite molded product (5), by heating the composite molded product (5),
Removing the resin binder in the composite molded product (5), sintering the sinterable particles, and between the sintered body of the inner molded product (6) and the sintered body of the outer molded product (7) Forming a gap (81) ".

In the manufacturing method of the present invention, a kneaded product of sinterable particles and a resin binder is used as the inner molding material. The mixing 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 same. As the sinterable particles, hard particles which can be sintered at a predetermined temperature are used, and metal fine particles, ceramic fine particles and the like are preferably used. Further, the size of the sinterable particles is such that the sprue or runner of the composite molding machine smoothly flows and does not hinder the injection, and can be adapted to a desired size of the sliding member as a 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 is heated in an atmosphere until the sinterable particles are sintered. A material that 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, the outer molding material
For (B), a kneaded product of sinterable particles and a resin binder is used. The same sinterable particles and resin binder as those used for the above-mentioned inner molding material (A) are used. However, the compounding of the sinterable particles and the resin binder in the outer molding material (B) is such that the shrinkage after sintering is smaller than that of the inner molding material (A).

The inner molding material (A) and the outer molding material (B)
In each case, a sufficient amount of sinterable particles to secure the intended shape and fluidity sufficient to uniformly disperse this amount of sinterable particles and not impair the function of the injection device are provided. And a sufficient amount of resin binder. Further, in each of the molding materials (A) and (B), it is preferable to knead so that the sinterable particles are uniformly dispersed in the resin binder.

In the practice of the production method of the present invention, at least two molds, ie, an inner molding die (12) and a composite molding die (13) are used for molding a so-called intermediate molded 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)
The composite injection molding machine having (22) is preferably used. The composite molding die (13) has a mold cavity configured to accommodate the inner molding (3) and to accommodate the outer molding (4) around the intended surface of the inner molding. Is used.

In the above composite injection molding machine, first, a melt of the inner molding material (A) was injected into the inner molding die (12) and subjected to molding conditions to mold the inner molding (3). Thereafter, the inner molded product (3) is accommodated in a mold cavity in the composite molded product mold (13), and a molten material of the outer molding material (B) is injected therein and subjected to molding conditions, whereby the inner molding is performed. A composite molded article (5) in which the outer molded article (4) is joined around the molded article (3) is obtained. In the above-described composite molding, when the outer molding material (B) is injection-molded outside the inner molded product (3), if the timing is long and a weld is forcibly formed, the sintering described later will be performed. This is preferable because a sliding gap can be easily formed during processing.

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

The composite molded article (5) is subjected to a heat treatment under conditions that allow the sinterable particles contained therein to sinter. In this heating process, the resin binder is removed (hereinafter, degreasing). Is called). It is preferable that the resin binder is degreased promptly. From this point, a vacuum sintering furnace is suitably used. An example of a heating condition when such a vacuum sintering furnace is used is 500 ° C. for about 50 hours.

By the heat treatment, the inner molded product (3) and the outer molded product (4) are each degreased and slightly shrunk in volume, after which 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 an outer porous body that 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 shrinks by sintering and welding, and the inner sintered body is shrunk.
(6) and the outer sintered body (7). In the above 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, the difference in these shrinkage rates causes formation in the composite molded article. The bonded surface that has been separated separates, and a gap (81) is generated.

[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 formed around a surface serving as a sliding surface of the inner molded product (3). By injecting and molding the outer molding material (B) whose shrinkage rate after sintering in the kneaded material is set to be smaller than the inner molding material (A), the outer molding material is formed around the inner molding material (3). A composite molded article (5) to which the molded article (4) is joined is obtained.

Next, when the composite molded article (5) is subjected to a heat treatment, the sinterable particles in the composite molded article (5) are sintered and the resin binder is removed. Although the volume shrinks, the volume shrinkage when the inner molded product (3) changes to its sintered body (6) is
Since (4) is larger than the volume shrinkage when the sintered body (7) changes, a gap (81) is formed between the inner sintered body (6) and the outer sintered body (7). Will occur. As a result, a sliding component is obtained in which the outer component is slidably engaged with a predetermined portion of the inner component that is obtained as an integral object, not as an assembled product from small components.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail 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 production 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 apparatus (1) is provided with a mold (12) for an inner molded product and a mold (13) for a composite molded product on a mold rotating mechanism (11). 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. I have.

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

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

In the next second injection step, as shown in FIG. 2, the inner molded product (3) obtained in the first injection step is transferred to a mold cavity in a composite molded die (13). Then, in this state, the molten material 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, a long timing is taken to form a weld. At this time, the first injection step is performed in parallel on the inner mold (12).

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

The composite molded article (5) obtained as described above
When heated in a vacuum incinerator (not shown) at 500 ° C. for about 50 hours, the resin binder in the composite molded product (5) is degreased and slightly shrinks in volume. With the weld line formed forcibly as a boundary, the SUS fine particles remaining in each molded product area are combined with each other to obtain a combination of a low-density inner porous body and a high-density outer porous body. Can be Further, when the combination of the porous bodies is subjected to heat treatment under the condition of sintering the respective SUS fine particles, the respective porous bodies are contracted in volume to the respective sintered bodies, but the inner sintered body (6 Since the contraction rate to the outer porous body is larger than the contraction rate to the outer sintered body (7), the bonding surface formed in the composite molded article separates due to the difference in the contraction rate, and the gap (81) Will occur. As a result, as shown in FIG.
As a result, the sliding component (8) holding the sliding gap (81) without welding the (6) and the outer sintered body (7) is obtained.

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.
(61) having a bulge and a sliding portion main body (62) between both ends thereof
Even if the inner sintered body (6) has a structure in which the outer sintered body (7) is inserted around the sliding portion main body (62), the inner sintered body (6) is ) And each end (61) can be molded as an integral body without being divided. Further, 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 cannot be manufactured by the conventional processing method can be easily manufactured. In addition, since it can be produced by injection molding, it can be provided in large quantities and at low cost. Furthermore, since a minute sliding component can be manufactured and the shrinkage ratio of each material can be freely changed, it is easy to set any sliding gap.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram of a main part illustrating a state of injection and filling of a molding material in a second injection step.

FIG. 3 is a schematic view of a main part for explaining removal of an inner molded product and a composite molded product.

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

FIG. 5 is a schematic sectional view taken along line XX of FIG. 4;

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

FIG. 7 is a schematic sectional view taken along line XX of FIG. 6;

[Explanation of symbols]

(1) Mold apparatus (2) Injection mechanism (3) Inner molding (4) Outer molding (5) Composite molding (6) Inner sintered body (7) Outer sintered body (8)… Sliding parts (11)… Mold rotation mechanism (12)… Mold for inner molding (13)… Mould for composite molding (21) (22)… Injection device (A)… Inner molding Material (B) ... Outside molding material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B29C 45/16 B29C 45/16 67/04 67/04 B29K 105: 16 B29K 105: 16

Claims (3)

(57) [Claims] 1. An inner molding material comprising a kneaded material blended so as to have a predetermined shrinkage ratio after sintering, comprising: a sinterable particle; and a resin binder removable by heating. A shrinkage ratio after sintering with a kneaded material with a removable resin binder is prepared with an outer molding material set to be smaller than the inner molding material, and an inner molding is obtained by injection molding the inner molding material. Next, the outer molding material is injection-molded around a surface serving as a sliding surface of the inner molded product to obtain a composite molded product in which the inner molded product and the outer molded product are joined to each other. By heat treatment, the resin binder in the composite molded product is removed, the sinterable particles are sintered, and a gap is formed between the sintered compact of the inner molded product and the sintered compact of the outer molded product. A method for manufacturing a sliding component, comprising: 2. An inner molding material composed of a kneaded material blended so as to have a predetermined shrinkage ratio after sintering, comprising a sinterable particle and a resin binder removable by heating; A shrinkage ratio after sintering in the kneaded product with the removable resin binder is constituted by an outer molding material set to be smaller than the inner molding material, and the inner molding material is formed into an inner molded product by injection molding. the said outer molding material around the sliding surface and comprising a surface of the inner molded product is injection molded, the sliding parts for molding the inner molding and overmolding becomes formed in composite molding, which is joined . 3. A sliding component obtained by the method according to claim 1.