JP3217120B2 - Apparatus and method for forming sintered body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a sintered body in which a mixture of raw material powder of a sintered body and a thermoplastic resin is molded by injection molding, then degreased and sintered to obtain a sintered body. The present invention relates to an apparatus and a method for manufacturing a sintered body for continuously multiplex-forming several other molded bodies.

[0002]

2. Description of the Related Art Conventionally, the following method has been known as a method for performing multiple molding of a sintered body by injection molding. FIG.
As shown in FIG. 2, a mold plate 50 is provided with a core 51 slidably provided with a concave portion on a molding surface portion. A template 52 is provided on the right side of the template 50, and a core 53 is slidably provided on the template 52. On the parting surface P where the mold plate 50 and the mold plate 52 are in contact, the molding surface portions 5 of the cores 51 and 53 are provided.
A cavity 54 is formed by 1a, 53a, the mold plate 50 and the mold plate 52, and a gate 55 for supplying raw material powder into the cavity 54 is provided on the parting surface P.

[0003] A first injection molding method using a molding apparatus for a sintered body having the above configuration will be described with reference to FIGS. The raw material powder is injected into the cavity 54 to obtain a molded body A (see FIG. 12). Molded product A by core 51
And the core 53 are moved rightward, and then only the core 51 is retracted to form a space between the core 51 and the molded body A,
The raw material powder is injected into this space to obtain a compact B (FIG. 13).
reference). After the completion of the molding, the molded bodies A and B are taken out from the parting surface P side, and the molded bodies are degreased and sintered to obtain a sintered body. Multiple molding of the injection molded body is performed by the injection molding apparatus and the injection molding method.

The second method will be described with reference to FIGS. Using the same molding apparatus as that used in the first injection molding method, the molded body A and the molded body B are separately molded. (See FIGS. 14 and 15). After completion of the molding, the molded bodies A and B are taken out from the mold, and then the molded bodies A and B are taken out.
(See FIG. 16).

[0005]

However, each of the above prior arts has the following disadvantages. That is, in the first method, as shown in FIG. 17 and FIG. 18, using a mixture of a sintered body raw material powder and a thermoplastic resin, a molded body A having a convex portion in the axial direction; When the compact A and the compact B have the same material when the compact B having the concave portion having the shape corresponding to the convex portion is formed by multiple molding, the compact A and the compact are formed in the sintering process. The contact surface C with B is welded, so that the molded body A and the molded body B cannot be slid (see FIG. 19).

Therefore, there is a method in which the material is changed into two types so as to prevent the molded body A and the molded body B from sticking.
It is necessary to purchase a new molding machine, and the conditions become complicated in the degreasing step and the sintering step, resulting in an increase in cost. Further, when the mold is opened and the separating agent is applied to the contact surface C between the molded body A and the molded body B by spraying, the separating agent is attached to a portion other than a desired portion, and the quality is deteriorated. Problems such as lowering the temperature occur.

In the second method, the compact A and the compact B are sintered separately, so that they are not welded. However, an assembling step after sintering is required, which leads to an increase in cost.

Accordingly, the present invention has been developed in view of the drawbacks of the above-described prior arts, and can prevent the welding of the contact surfaces of the respective molded products, and does not require the assembly of the sintered product. It is an object of the present invention to provide a molding apparatus and a manufacturing method.

[0009]

According to the present invention, a portion forming a cavity of a mold is made of a porous material, and a path for supplying a liquid to the mold made of the porous material is provided.

A first injection molding step of injection molding a mixture of the raw material powder of the sintered body and the thermoplastic resin into a mold made of a porous material to obtain a predetermined primary injection molded body; A coating step of leaching and applying a separating agent composed of a ceramic solution from a mold made of a porous material to a next injection molded body, and injecting the mixture into the primary injection molded body coated with the separating agent to form a secondary A secondary injection molding step of obtaining an injection molded body, a step of obtaining the final next injection molded body by repeating the coating step and the injection molding step sequentially, and a degreasing step of heating the final injection molded body to obtain a degreased body And a sintering step of sintering the degreased body to obtain a sintered body.

[0011]

According to the present invention, the final injection molded body is sintered after being degreased. At that time, the ceramics is in a state of being adhered to the contact portions between the respective degreased next injection molded bodies. By this ceramics, welding of the degreased injection molded body, that is, the degreased body can be prevented.

[0012]

[Embodiment 1] FIGS. 1 to 6 are sectional views of a main part of an apparatus used in this embodiment. As shown in FIG. 1, a slide base 2 is slidably provided in a mold plate 1, and a core 3 made of porous ceramics and having a concave portion in a molding surface portion is provided at a tip end thereof.
Is fixed. A fluid flow path 2 a for supplying the separating agent 4 is provided inside the slide base 2.
a reaches the core 3.

A template 5 is provided on the right side of the template 1, and a core 6 is slidably provided in the template 5. On the parting surface P where the template 1 and the template 5 are in contact with each other, cavities 7 are formed by the tip portions 3a and 6a of the cores 3 and 6 and the template 1 and the template 5. A gate 8 for supplying raw material powder is provided.

In this embodiment, a liquid obtained by dispersing a ceramic powder in ethanol was used as the separating agent 4, and SUS304 and a thermoplastic resin were mixed as raw material powders of the molded product to perform injection molding.

An injection molding method using a molding apparatus for a sintered body having the above configuration will be described with reference to FIGS. A raw material powder is injected into the cavity 7 to obtain a molded body A (see FIG. 2). The porous core 3 is advanced by the thickness of the molded body to be molded next, and the molded body A and the core 6 are moved (see FIG. 3). The separating agent 4 in the flow path 2a is pressurized to seep into the core 3 made of a porous material. When the pressurization is further continued, the separating material 4 oozes out on the contact surface between the core 3 and the molded body A, and the film 9 of the separating agent 4 is formed on the contact surface (see FIG. 4).

After the application of the separating agent 4 to the molded body A, the core 6 is stopped at a position shown in FIG. 4 by a stop mechanism (not shown), and only the core 3 of the molded body to be molded next is formed. It is retracted by the thickness (leftward in FIG. 5).
At this time, since the molded body A does not move from the position shown in FIG. 4, a space 10 (a cavity for subsequent molding) is formed between the core 3 made of a porous material and the molded body A ( (See FIG. 5). The raw material powder is injected into the space 10 (cavity) to obtain a compact B (see FIG. 6).

After the molding is completed, the molded bodies A and B are taken out from the parting surface P side, and heated and degreased at a temperature of about 320 ° C. under the atmospheric pressure. After the degreasing is completed, the compact is vacuum-sintered at a temperature of about 1350 ° C. to obtain a sintered body.

According to this embodiment, since the separating agent is applied to the contact surface with the molded body obtained by the multiple molding, the molded body and the molded body are not welded in the sintering step. .

The material of the porous core 3 may be any material as long as it can withstand the temperature of the molded body during injection molding and is not eroded by the separating agent, and porous metal and porous ceramics may be used. The liquid for dispersing the ceramic powder used as the separating agent 4 may be any substance as long as it does not corrode the thermoplastic resin contained in the molded article during injection molding. And isopropyl alcohol.

Further, the ceramic powder used as the separating agent 4 may be any substance as long as it does not react with the material constituting the degreased injection-molded article and does not react with the ceramic itself. For example, alumina (Al ₂ O ₃ ), sialon, zirconia oxide (ZrO)
₂ ), chromina (Cr ₂ O ₃ ), silicon carbide (Si
C), 3Al ₂ O ₃ -2SiO ₂ , titanium oxide (TiO ₂ )
₂ ), TiO ₂ —Al ₂ O ₃ , Al ₂ O ₃ —ZrO ₂ ,
Hexagonal silicon nitride (h-BN), PBN, carbon (C),
Cubic silicon nitride (c-BN), silicon oxide (Si
O ₂ ) and silicon nitride (Si ₃ N ₄ ) may be used.

[0021]

[Embodiment 2] The structure of the molding apparatus is the same as that of Embodiment 1 described above.
It is the same as (FIG. 1). In the present embodiment, 2
Injection molding was performed by using a liquid in which ceramics powder was dispersed in one of the liquid-mixing adhesives (epoxy-based) and mixing the other liquid with the raw material powder.

The injection molding method of this embodiment will be described with reference to FIGS. It is the same as in Example 1 above, until the separating agent is pressurized and the separating agent is applied to the molded body. By applying the separating agent 4 to the molded product A, one of the two-component mixed adhesives in the molded product A reacts with the separating agent 4 (the other liquid of the two-component mixed adhesive). Then, the mixture is solidified while containing the ceramic powder to form a separating agent film 9 (adhesive and ceramic film).

After the application of the separating agent 4, when the porous core 3 is retracted as shown in FIG. 5, a minute amount of material particles constituting the core 3 comes out, and the core 3 is porous. Therefore, since the core 3 has better releasability from the molded body A than the molded body A when the core 3 is moved (retracted), the separation property of the separating agent 4 from the film 9 of the separating agent 4 formed by solidifying the adhesive is reduced. The film 9 remains on the molding A side. Thereafter, the next molded body B is molded in the same manner as in Example 1 (see FIG. 6), and the molded bodies A and B are degreased and sintered to obtain a sintered body.

According to this embodiment, the adhesive solidifies on the contact surface between the molded bodies obtained by the multiple molding and forms a separation film. There is no welding between the body and the molded body.

[0025]

[Embodiment 3] The structure of the molding apparatus is the same as that of Embodiment 1 described above.
It is the same as (FIG. 1). In the present embodiment, a liquid obtained by mixing a ceramics powder with a stearyl alcohol liquid is used as the separating agent 4, and SUS304 is used as a raw material powder for the compacts A and B.
Injection molding was performed by mixing powder (containing Cu) and a thermoplastic resin.

The injection molding method of this embodiment will be described with reference to FIGS. It is the same as in the first embodiment until the separating agent 4 is pressurized and the separating agent 4 is applied to the molded body A. When the separating agent 4 is applied to the compact A, the oxidation of the stearyl alcohol solution is promoted by the Cu contained in the raw material powder of the compact A, and the stearyl alcohol solution is solidified while containing the ceramic powder. Then, a film 9 (ceramic film) of the separating agent 4 is formed (see FIG. 4). Thereafter, in the same manner as in the first embodiment, the core 3 is retracted (see FIG. 5) to form the space 10, the next compact B is formed, and the compacts A and B are degreased and sintered. To obtain a sintered body.

According to the present embodiment, since a film of the separating agent is formed on the contact surface between the molded bodies obtained by the multiple molding and the molded body, the molded bodies are separated from each other in the sintering step. No welding.

[0028]

[Embodiment 4] FIGS. 7 to 11 are sectional views of a main part of an apparatus used in this embodiment. In this embodiment, the same members as those in the first embodiment are denoted by the same reference numerals. As shown in FIG. 7, the template 1 includes
A slide base 2 is slidably provided inside, and a core 11 made of porous pumice stone is fixed to a tip portion thereof. A fluid flow path 2a for supplying a separating agent 4 is provided inside the slide base 2, and the flow path 2a
Has reached one.

A template 5 is provided on the right side of the template 1, and a core 6 is slidably provided in the template 5. On the parting surface P where the template 1 and the template 5 are in contact, the tip portions 11a and 6a of the cores 11 and 6 and the cavity 7 are formed by the template 1 and the template 5, and the cavity 7 is formed on the parting surface P. A gate 8 for supplying a resin into the inside is provided. In the present embodiment, an aerobic adhesive was used as the separating agent 4, and SUS304 and a thermoplastic resin were mixed as raw material powder of the molded body, and injection molding was performed.

FIGS. 7 to 11 show the injection molding method of this embodiment.
This will be described with reference to FIG. The adhesive in the flow path 2a is pressurized, and the adhesive is absorbed into the core 11 made of pumice stone. At this time,
The adhesive soaked into the pumice stone is in a semi-solid state because it comes into contact with air (see FIG. 7). In this state, the raw material powder is injected into the cavity 7. When the raw material powder is injected to form the compact A, the compact A is bonded to the core 11 with the adhesive (see FIG. 8). In this state, the core 11 is advanced by the thickness of the molded body to be molded next, and the molded body A and the core 6 are moved (see FIG. 9).

When the advance of the core 11 is completed, the core 6 is stopped at a position shown in FIG. 9 by a stop mechanism (not shown), and only the core 11 is retracted by an amount corresponding to the thickness of the molded body to be molded next. (Left direction in FIG. 10). At this time, the surface layer of the core 11, which is the bonding surface with the molded body A, is separated from the core 11 main body and remains on the bonding surface of the molded body A, and the pumice stone having the aerobic adhesive on the surface of the molded body A A film 12 is formed. Since the compact A does not move from the position shown in FIG. 9, a space 10 is formed between the core 11 made of pumice and the compact A.
(Cavities for performing subsequent molding) are formed (see FIG. 10).

The raw material powder of the molded body B to be molded next is injected into the space 10 (cavity) (see FIG. 11). Thereafter, the next compact B is formed in the same manner as in the first embodiment, and the compacts A and B are degreased and sintered to obtain a sintered body.

According to this embodiment, since the peeled pumice film is formed on the contact surface with the compact obtained by the multiple molding, the compact and the compact are welded in the sintering step. I have nothing to do.

In each of the above embodiments, a molded article and a molded article were used.
According to the apparatus and method for forming a sintered body of the present invention, the second forming step described in each of the examples is repeated a desired number of times to perform the third forming. Thereafter, multiple molding can be performed many times.

[0035]

As described above, according to the apparatus and method for molding a sintered body according to the present invention, a separating agent is applied to the contact surface between the molded bodies obtained by multiplex molding. This eliminates the problem that the compacts adhere to each other in the sintering process. Thereby, each molded body can be manufactured without going through steps such as molding, degreasing, sintering and assembling separately, and the cost can be kept low.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing a first embodiment.

FIG. 2 is a cross-sectional view of a main part showing the first embodiment.

FIG. 3 is a sectional view of a main part showing the first embodiment.

FIG. 4 is a sectional view of a main part showing the first embodiment.

FIG. 5 is a sectional view of a main part showing the first embodiment.

FIG. 6 is a sectional view of a main part showing the first embodiment.

FIG. 7 is a cross-sectional view of a main part showing a fourth embodiment.

FIG. 8 is a cross-sectional view of a main part showing a fourth embodiment.

FIG. 9 is a cross-sectional view of a main part showing a fourth embodiment.

FIG. 10 is a sectional view of an essential part showing a fourth embodiment;

FIG. 11 is a cross-sectional view of a main part showing Example 4;

FIG. 12 is a sectional view of a main part showing a conventional example.

FIG. 13 is a sectional view of a main part showing a conventional example.

FIG. 14 is a sectional view of a main part showing a conventional example.

FIG. 15 is a sectional view of a main part showing a conventional example.

FIG. 16 is a sectional view showing a conventional example.

FIG. 17 is a perspective view showing a conventional example.

FIG. 18 is a sectional view showing a conventional example.

FIG. 19 is a partial sectional view showing a conventional example.

[Explanation of symbols]

 1,5 template 2 slide base 3,6 core 4 separating agent 7 cavity 8 gate

Continuation of the front page (72) Inventor Katsumi Sekine 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside O-Limpus Optics Co., Ltd. (72) Inventor Naohito Shiga 2-43-2 Hatagaya, Shibuya-ku, Tokyo O-Limpus Optics (72) Inventor Michio Shirai 2-43-2 Hatagaya, Shibuya-ku, Tokyo O-Limpus Optics Industry Co., Ltd. (72) Inventor Kenji Haga 2-43-2 Hatagaya, Shibuya-ku, Tokyo O-limpus Optics Within Industrial Co., Ltd. (72) Inventor Jun Inahashi 2-43-2, Hatagaya, Shibuya-ku, Tokyo Olympus Optical Industrial Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) B22F 3/03

Claims (2)

(57) [Claims] An apparatus for forming a sintered body, wherein a portion forming a cavity of a mold is made of a porous material, and a path for supplying a liquid to a mold made of the porous material is provided. 2. A primary injection molding step of injection molding a mixture obtained by mixing a sintered body raw material powder and a thermoplastic resin into a mold made of a porous material to obtain a predetermined primary injection molded body; A coating step of leaching and applying a separating agent composed of a ceramic solution from a mold made of a porous material to a next injection molded body, and injecting the mixture into the primary injection molded body coated with the separating agent to form a secondary A secondary injection molding step of obtaining an injection molded body, a step of obtaining the final next injection molded body by repeating the coating step and the injection molding step sequentially, and a degreasing step of heating the final injection molded body to obtain a degreased body And a sintering step of sintering the degreased body to obtain a sintered body.