JP3161629B2 - Two-layer component manufacturing method, molded product for two-layer component, and two-layer component obtained by two-layer component 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 two-layer part, a molded product for a two-layer part, and a two-layer part obtained by a method for manufacturing a two-layer part.

[0002]

2. Description of the Related Art As a conventional two-layer molding technique, there is known a two-layer molding method used for producing a two-layer molded product such as a key top. Since this is made by plastics molding technology such as injection molding using different kinds of thermoplastic resins, it is also possible to obtain a fine two-layer molded product. However, since the two-layer molded product obtained by this method is a resin molded product, one that can withstand use at high temperatures cannot be produced.

Further, a two-layer material composed of a combination of different metals can be processed to produce a two-layer part that can withstand high temperatures. It is difficult to make the final part.

Recently, a raw material obtained by kneading fine particles of metal, ceramic, etc. and a resin binder is injection-molded, and the obtained molded product is subjected to heat treatment to degrease a predetermined portion of the resin binder, thereby forming a complicated shape. A technique for manufacturing a component is known (see Japanese Patent Application Laid-Open No. 4-70313).

[0005]

SUMMARY OF THE INVENTION The present invention relates to a two-layer component made of a different material selected from hard materials such as metals and ceramics, and to easily produce a two-layer component in which these different materials are firmly bonded. To provide a two-layer part manufacturing method and a molded product for a two-layer part.

[0006]

Thus, according to the invention of claim 1 of the present application, "the sinterable particles and the resin binder removable by heating have a predetermined shrinkage ratio after sintering. First molding material comprising compounded kneaded material
(A) and a second molding material having a different shrinkage ratio after sintering set to be smaller than that of the first molding material (A) by a mixture of sinterable particles different from the above and a resin binder removable by heating. (B)
The door was prepared, killing fit by the first molding material (A) Jo凹
A first molded product (3) having a portion (31) is molded, and the second molding material (B) is formed into at least the above-mentioned fitted-in shape of the first molded product (3).
Injection molding so as to fill the recess (31)
A composite molded product in which (3) and the second molded product (4) are fitted and joined.
By molding (5), and then heat-treating the composite molded product (5), the resin binder in the composite molded product (5) is removed, and each of the sinterable particles is sintered. A method of manufacturing a two-layer part comprising manufacturing a two-layer part (8) in which a sintered body (6) of a first molded article and a sintered body (7) of a second molded article are fitted and joined "
Is provided.

[0007] In the molding method of the present invention, the first molding material
(A) uses a kneaded product of sinterable particles and a resin binder. The compounding of the sinterable particles and the resin binder in the kneaded product is adjusted according to the shrinkage ratio between the first molded product (3) and the sintered body (6) obtained by sintering the first molded product (3). . 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. In addition, 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 two-layer member as the final product. Is selected.

[0008] 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 molding method of the present invention, the second molding material
For (B), a kneaded product of sinterable particles and a resin binder is used. The sinterable particles and the resin binder are selected from those similar to those used in the first molding material (A), but the sinterable particles used in the second molding material (B) A type different from that used for the first molding material (A) is always selected. Also, the second molding material
The compounding of the sinterable particles and the resin binder in (B) is as follows.
The shrinkage after sintering is set to be smaller than that of the first molding material (A).

The first molding material (A) and the second 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. In each of the molding materials (A) and (B), kneading is preferably performed so that the sinterable particles are uniformly dispersed in the resin binder.

In the present invention, the first molded product (3) formed from the first molding material (A) is constituted so as to have a mating concave portion (31). The second molded product (4) formed from the second molding material (B) is at least one of the first molded products (3).
It is formed so as to fit with the mating concave portion (31), and more preferably, is formed so as to fit with the mating concave portion (31) and join with the surface having the concave portion .

In the practice of the molding method of the present invention, the first
At least two molds having at least two molds, one for a molded product and the other for a composite molded product, and separately melting and injecting the first molding material (A) and the second molding material (B); Injection equipment (2
1) A composite injection molding machine having (22) is preferably used. In addition, the mating concave portion (31) formed in the first molded product is
Either movable mold or the fixed mold in the first molding die is formed by using what is configured in split die.

In the above-described composite injection molding machine, first, a melt of the first molding material (A) is injected into a first molding die and subjected to molding conditions to form a first molding (3). Later, this first
By injecting the melt of the second molding material (B) into the molded article (3) and subjecting it to molding conditions, the second molded article (4) fits into at least the concave portion (31) of the first molded article (3). Composite moldings joined and joined
(5) is obtained.

The composite molded product (5) obtained as described above is a molded product for a two-layer part 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 the process leading to the sintering, the resin binder is removed. (Hereinafter referred to as degreasing). 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 above-mentioned heat treatment, the first molded product (3) and the second molded product (4) are degreased and slightly shrunk in volume, and thereafter the sinterable particles contained in each molded product are reduced. It is obtained as a combination of a so-called first porous body and a second porous body, which are bonded to each other while maintaining the shape of each molded product. In this case, the density of the first porous body is smaller than the density of the second porous body.
When the combination of the porous bodies is subjected to sintering conditions, the particles of each porous body shrink due to sintering and welding of the particles, and
This is a combination of the sintered body (6) and the second sintered body (7). In the above sintering, the contraction rate of the second sintered body (7) is the first sintered body.
Since it is set smaller than the contraction rate in (6), the first
The contraction rate of the concave portion (61) of the sintered body (6) is larger than the contraction rate of the fitting body portion (71) of the second sintered body (7) filled in the concave portion, and can be firmly fitted. Becomes

[0017]

According to the present invention, a first molding material comprising a kneaded mixture of sinterable particles and a resin binder removable by heating.
(A) is an injection molded first part having a mating concave portion (31).
After the molded article (3) is molded, a mixture of sinterable particles different from those described above and a resin binder removable by heating is placed in at least the mating recess (31) of the first molded article (3). Then, the second molding material (B) prepared so that the shrinkage rate after sintering becomes smaller than that of the first molding material (A) is filled and subjected to molding. As a result, at least the above-mentioned mating concave portion (3
The composite molded article (5) fitted and joined to each other in 1) is obtained.

Next, when the composite molded product (5) is subjected to a heat treatment, the sinterable particles in the composite molded product (5) are sintered, and the resin binder is removed. While maintaining the combined state, it becomes a so-called bonded body of porous sinterable particles, and when this is subjected to sintering conditions, it sinters and welds and contracts in volume.
The volume shrinkage when changing from (3) to the sintered body (6) is
Since it is larger than the volume shrinkage ratio when changing from the second molded product (4) to its sintered body (7), the fitting state is a so-called cold shrinkage, and there is no gap at the fitting part, and it is very strong. The first sintered body (6) and the second sintered body (7) are fitted and welded with the fitted state.

[0019]

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) includes two movable dies (12) and (13) provided on a mold rotating mechanism (11), and two movable dies (12) and (13) fixed to each other. It is composed of fixed types (14) and (15). Among the fixed dies, a first forming fixed die (14) includes an inner die (16) constituting a sprue (a) and a plurality of dies for forming a concave portion (31) which is in contact with the inner die (16) and is fitted and killed in the mold cavity. The split mold (17) and the external mold (18) that supports them are configured, and the split mold (17) group slides to the center as the internal mold (16) retreats to the injection mechanism side. Have been. The injection mechanism (2) is provided with an injection device (21) in which the first molding material (A) is melted and filled and an injection device (22) in which the second molding material (B) is melted and filled. Have been.

In this embodiment, the first molding material (A) includes:
55% iron fine particles and 45% resin binder as sinterable particles
And a mixture kneaded so as to be uniform by mixing the same, and the second molding material (B) contains ceramic fine particles 6
A mixture obtained by blending 0% and 40% of the same resin pellets as described above and kneading the mixture is used.

In the above configuration, first, in the first injection step, as shown in FIG. 1, the first molding material (A) is melted in a cavity formed by a movable mold (12) and a fixed mold (14). After the injection, the first molding (3) is molded under molding conditions. After molding,
When the internal type (16) of the fixed type (14) is retracted, the split type (17)
The group slides toward the center, and then the mold rotation mechanism (1
Move the movable molds (12) and (13) by 1) and open the mold,
A first mold in which a mating concave portion (31) is formed in a movable mold (12).
A molded product (3) is obtained.

Next, the process proceeds to the second injection step. First, the mold rotating mechanism (11) is operated to rotate, and the movable mold (12) in which the first molded product (3) is accommodated is fixed (15). After the movable mold (13) is opposed to the fixed mold (14), each mold is closed as shown in FIG. 2, and in this state, the molten material of the second molding material (B) is injected and molded. Attach conditions. Note that the injection of the second molding material (B) is performed by fitting the concave-shaped recess (3) formed in the first molding (3).
It is made so that 1) is sufficiently filled. At this time, the first injection step is performed in parallel in the mold cavity composed of the movable mold (13) and the fixed mold (14).

When the second injection step is completed, the respective dies are opened as shown in FIG. 3, and the first molded product (3) and the second molded product (4) are separated from the movable mold (12). The composite molded articles (5) fitted and joined to each other are discharged.

The composite molded article (5) obtained as described above
Is subjected to a heating condition of, for example, about 500 ° C. for about 50 hours in a vacuum incinerator (not shown). The iron fine particles and the ceramic fine particles in the composite molded product (5) are sintered, and the resin binder is melted and vaporized and removed. (Degreasing), the composite molded product (5) having the size shown in FIG. 4 is shrunk entirely, and the first sintered body (6) having the size shown in FIG. A two-layer part (8) in which the body (7) is fitted and welded is obtained. In the degreasing process, the first molded product (3)
Since the shrinkage ratio of the second molded product (4) is larger than that of the second molded product (4), the shrinkage ratio of the indented concave portion (61) of the first sintered body (6) is reduced by the second shrinkage filled in the concave portion. It is larger than the contraction rate of the fitting body portion (71) of the united body (7), and the fitting state becomes a so-called cold fit, and the first fitting part has a very strong fitting state without any gap. The sintered body (6) and the second sintered body (7) are fitted and welded. As a result, a two-layer molded article that is firmly bonded at a high temperature can be obtained even when the sintered bodies are formed of different sintered bodies having different coefficients of thermal expansion.

[0025]

According to the present invention, a two-layer part which cannot be manufactured by the conventional processing method can be easily manufactured. In addition, since it can be manufactured by injection molding, a large amount and inexpensive two-layer part can be provided. Furthermore, since a minute component can be manufactured and the contraction rate of each material can be freely changed, a two-layer component that does not generate a gap at a high temperature can be manufactured even from materials having different coefficients of thermal expansion.

[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 a composite molded product.

FIG. 4 is a schematic cross-sectional view of a composite molded product.

FIG. 5 is a schematic cross-sectional view of a two-layer component.

[Explanation of symbols]

(1) Mold device (2) Injection mechanism (3) First molded product (4) Second molded product (5) Composite molded product (6) First sintered body (7) 2 sintered body (8) ... two-layer part (11) ... mold rotating mechanism (12) (13) ... movable type (14) (15) ... fixed type (17) ... split type (21) (22) ... Injection device (A)… Inner molding material (B)… Outer molding material

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 35/00-35/65 C22C 1/04-1/05 B28B 1 / 24,7 / 16

Claims (3)

(57) [Claims] 1. A first molding material comprising a kneaded material blended so that a sinterable particle and a resin binder removable by heating have a predetermined shrinkage ratio after sintering, and a sinterable material different from the above. A second molding material having a shrinkage ratio after sintering set to be smaller than that of the first molding material is prepared from a mixture of the particles and a resin binder that can be removed by heating, and the first molding material is prepared.
A first molded article having a mating concave portion is molded with a molding material, and the second molding material is placed on at least the first molded article.
Injection molding is performed so as to fill the indentation-shaped concave portion ,
By molding a composite molded product in which the molded product and the second molded product are fitted and joined, and then subjecting the composite molded product to a heat treatment, the resin binder in the composite molded product is removed, and each sintering process is performed. A method for manufacturing a two-layer part, comprising sintering possible particles to manufacture a two-layer part in which a sintered body of a first molded article and a sintered body of a second molded article are fitted and joined . 2. Sinterable particles and removable by heating
Resin binder has a certain shrinkage after sintering.
A first molding material composed of a kneaded material mixed with
Different sinterable particles and resin vine removable by heating
Shrinkage after sintering with the compound with
And the second molding material which is also set to be small,
The molding material is molded into a first molding having a mating recess.
And the second molding material is at least the above-mentioned engagement of the first molding.
Injection molding to fill the recess
And a second molded product are fitted and joined to form a composite molded product.
Molded product for two-layer parts . 3. The method according to claim 1, wherein
Are two-layer parts .