JPH0712606B2 - Molding method for prototype for sintering - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for casting a powdery or granular material slurry into a mold to form a sintering original body having a complicated shape.

(Prior Art) Conventionally, gypsum has been widely used as one of the methods for molding a sintering original body having a complicated shape from ceramic powder, for example.

However, a plaster mold which has been often used in the past has a problem in that it is difficult to release a mold having a complicated shape and has no durability. Therefore, the applicant of the present invention has developed a special forming method for sintering prototypes as disclosed in Japanese Patent Laid-Open No. 62-268603.

(Problems of the prior art) The molding of the sintering prototype, which is disclosed in Japanese Patent Laid-Open No. 62-268603, is performed by closely contacting a shielding member on the molding surface of the prototype member, placing the molding frame on it, and forming the molding frame. Fill the inside of the body with a filler made of granular material such as silica sand, seal the upper surface of the molding frame body to create a negative pressure inside the molding frame body, make the packing material into a vacuum pack, and mold a half mold. Slurry is injected into a cavity defined by combining two molds.

However, the sintering prototype formed by the above method has the following problems. That is, in the process of sintering the sintering prototype, the filler made of particles such as silica sand remaining around the sintering prototype reacts with the sintering prototype to form the sintering prototype. When mixed as impurities, problems such as deterioration of quality and surface properties of the sintered body occur.

(Object of the invention) The present invention has been made with the object of solving these problems, and it is to provide a method for molding a sintering prototype without mixing impurities during sintering. .

(Means for Solving Problems) According to the present invention, a shielding member that can be dissolved in a slurry solvent or a shielding member that can penetrate a slurry solvent is adhered to the surface of an original model plate, and a molding frame is attached on the adhered shielding member. Is placed and the filling material is filled in the molding frame, the upper surface of the filling material is closed to make the molding frame negative pressure, and thus the shielding member is adsorbed to the filling material side, and then the prototype model plate Is separated from the shielding member to form a half mold having a molding surface, and a mold is formed in the same manner as the half mold to form a cavity by combining with one half mold and baking is performed in the cavity. Injecting a sintering raw material slurry formed by adding a solvent to the binding raw material, and then releasing the negative pressure state in the molding frame to collapse the half mold,
In the method for molding a sintering prototype, which takes out the sintering prototype, the filler is an inorganic particulate material having a melting point equal to or higher than the melting point of the sintering raw material.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a prototype model plate (1). The prototype model plate (1) has a base (3) in which a hollow chamber (2) is formed.
An original model (4) is attached to the upper part of the hollow chamber, and the base (3) and the original model (4) are provided with a plurality of ventilation holes (6) communicating with the hollow chamber (2) and the hollow chamber (2). (2) is communicatively connected to a suction device (not shown) via a hose (7) and a switching valve (8).

Next, FIG. 2 shows a state in which the shielding member (9) is subjected to a humidification and swelling treatment in order to impart extensibility to the shielding member (9). That is, water is uniformly added to a porous material (AL13PC manufactured by Showa Denko KK, particle size 80μ) in a saucer-shaped container (10) at 3 to 5% by weight.
The mixed porous humidifying material (11) is evenly spread in a layer shape of about 2 cm, and a shielding member (9) made of a water-soluble polyvinyl alcohol film having a thickness of 30 μ is attached to the film holding frame (12).
It is adsorbed and held by and placed on the porous humidifying material (11). The film holding frame (12) has a hollow chamber (13) inside the wall, and a suction hole (14) communicating with the hollow chamber (13) is formed in the lower plate portion of the film holding frame (13). ) Is connected to a suction device (not shown) through a hose (15) and a switching valve (16). Such holding frame (12)
Presses the shield member (9) onto the upper surface of the shield member (9) while the hollow chamber (13) communicates with a suction device (not shown) to cause the lower surface of the holding frame (12) to exert a suction action. It is held and placed on the porous humidifying material (11).

Next, the porous humidifying material (1
The same thing as 1) is spread evenly in a layer of about 1 cm, and the state shown in Fig. 2 is obtained. In this state, let it stand still for about 3 minutes and shield the member (9).
To evenly humidify. Then, the porous humidifying material (11) on the shielding member (9) was removed, and the film holding frame (12) was raised to obtain a swollen shielding member (9).

In the embodiment, a method of humidifying and swelling the shielding member (9) in order to impart extensibility to the shielding member (9) is adopted, but it is also possible to heat the shielding member (9) to impart extensibility. .

Then, the hollow chamber (2) of the original model plate (1) and a suction device (not shown) are connected to each other to cause the surface of the original model plate (1) to perform a suction action and the swelled shielding member (9) to the film holding frame. Place it on the surface of the original model plate (1) together with (12). As a result, the shielding member (9) becomes the original model plate (1).
It is sucked and adhered along the prototype model (4) while being stretched by the suction action from the side. After that, the suction action of the holding frame (12) is blocked, the holding frame (12) is removed from the original model plate (1), and a model layer (17) is formed on the upper surface of the shielding member (9).

The mold-coating layer (17) was formed by coating a mold-coating agent composed mainly of diatomaceous earth of several microns, which is a porous material, with graphite and ethyl alcohol as a solvent added thereto.

Next, the molding frame body (18) is placed on top of the prototype model plate (1), and the same hollow space defined by the molding frame body (18) and the prototype model plate (1) is the same as the sintering raw material described later. An inorganic particulate filler (19) consisting of coarse aluminum oxide particles (A-12C manufactured by Showa Denko KK) having an average particle diameter of 75μ, which is the melting point, is filled, and a prototype model plate (1) and a molding frame are filled with a vibrator. The body (18) is vibrated integrally to increase the packing density of the filler (19) made of inorganic particles.

The molding frame (18) has an annular decompression chamber (2
0) is configured, and the decompression chamber (20) includes a hose (21).
And a suction device (not shown) through the switching valve (22).

In addition, the decompression chamber (20) is provided on the inner wall of the main body of the molding frame (18).
A large number of vent holes (23) communicating with each other are bored, and a filter (24) having fine lines for preventing passage of the filler (19) is attached to the inner wall surface of the main body.

In this state, the decompression chamber (20) communicates with a suction device (not shown), and a non-breathable sheet (25) is placed on the upper surface of the molding frame (18) to obtain the state shown in FIG. By this operation, the filler (19) receives the external pressure through the sheet (25) by the suction action from the decompression chamber (20) side of the molding frame (18) and is brought into a vacuum solidified state. In this state, the communication between the hollow chamber (2) of the original model plate (1) and the suction device (not shown) is cut off,
When the molding frame body (18) is separated from the original model plate (1), the shielding member (9) having the coating layer (17) is adsorbed to the filler (19) side, and die cutting is performed. A half mold for pouring the sintering raw material slurry is obtained.

By the same operation as above, another half mold is formed, the two half molds are matched, and the sintering raw material slurry (2
The injection cylinder (28) communicating with the bottom of the storage tank (27) of 6) is communicated with the sintering raw material slurry flow-in port (29), and the state shown in FIG. 4 is obtained.

The sintering raw material slurry (26) used in the examples was aluminum oxide powder having a diameter of 0.5 μm (Showa Denko KK).
A mixture of 100 parts of AL-160SG (manufactured by AL-160SG) and 1.0 part of a binder obtained by emulsifying polyvinyl alcohol and wax (as an organic solid content) and 20 parts of water as a solvent was used. In this state, the gate (30) is opened to inject the sintering raw material slurry (26) into the cavity (31). The water content of the sintering raw material slurry (26) injected in this manner is dissolved and permeated with a part of the water-soluble shielding member (9) left, and is further filled with the coating layer (17) and the inorganic particles. It is sucked toward the material (19) side, and as a result, a sintering prototype (32) made of an aggregate is formed in the cavity (31). Such a state is maintained for a predetermined time, and the sintering prototype body (32) made of an aggregate is solidified until the shape can be maintained even when the mold is released.

Next, the communication between the decompression chamber (20) of the vertically aligned molding frames (18) (18) and a suction device (not shown) is cut off to release the decompressed state in the molding frame (18) and the upper sheet ( After removing 25), the upper molding frame (18) is removed.

By this operation, the filler (19) made of the inorganic particulate material that constitutes the upper half mold is collapsed. In this state, the filler (19) is removed by air blow to solidify the sintering prototype (32), a part of the shielding member (9), a coating layer (17) absorbing water, and inorganic particles. The moisture condensing layer (33) of the filler (19) made of a material is integrated and taken out to obtain the state shown in FIG. When this is baked at 1600 ° C. for 2 hours, the shielding member (9) that remains partially is heated and burned off, and the coating layer (17) and the water aggregating layer (33) of the filler (19) composed of inorganic particulate matter. Is dried by heating and spontaneously disintegrates to obtain a desired ceramic compact. At this time, since the filler (19) is made of inorganic particulate material having the same melting point as the sintering raw material, it does not react with the sintering original body, and the quality of the sintered body can be confirmed by observation with an electron microscope. It was also found that the inconvenience of deteriorating the surface properties did not occur.

In the examples, the sintering raw material and the filler are made of the same material and have the same melting point, but the filler need not be the same material as long as it has a melting point higher than that of the sintering raw material. .

For example with respect to an aluminum oxide sintered material for mullite same effect it is used _{(3Al 2 O 3 · 2SiO 2} ) was calcined granulated granules in a spray dryer powder (refractoriness 1820 ° C.) is obtained.

Further, although aluminum oxide powder was used as the sintering raw material in the examples, any of silicon carbide, silicon nitride, mullite, cordierite, potassium titanate, other non-oxides and oxides may be used. In this case, the filler is A material having a melting point higher than that of the sintering raw material may be used.

Also, if the inorganic particulate matter is made of a porous particulate matter having water absorption, it can contain moisture therein, so that the moisture condensing layer (33) is hardly formed, and the filler (19) is unshaped. At this time, it becomes possible to easily remove the raw body for sintering (32) from the surface by air blow.

(Effects of the Invention) In the present invention, when an inorganic particulate material having a melting point higher than that of the sintering raw material is used as a filler when molding the sintering prototype, it adheres to the sintering prototype. Also, during firing, there is no possibility of causing problems such as reaction with the sintering original form or burning and deterioration of the quality and surface properties of the sintered body.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an original model plate, FIG. 2 is a cross-sectional view showing a humidified state of a shielding member, FIG. 3 is a cross-sectional view showing a half-die forming state, and FIG. 4 is a sintering original form. Sectional view showing the molded state,
FIG. 5 is a cross-sectional view showing a state in which the sintering prototype is taken out. (1): Original model plate (9): Shielding member (18): Forming frame (19): Filler composed of inorganic particles (26): Sintering raw material slurry (31): Cavity

Claims (1)

[Claims] 1. A shield member which can be dissolved in a slurry solvent or a shield member which can penetrate a slurry solvent is adhered to the surface of an original model plate, and a molding frame body is placed on the adhered shield member and the molding frame is mounted. The body is filled with a filling material, the upper surface of the filling material is hermetically closed to make a negative pressure in the molding frame body, the shielding member is adsorbed to the filling material side, and then the original model plate is released from the shielding member. A half mold having a molding surface is molded, and a cavity is formed by matching with another half mold molded in the same manner as the half mold, and a solvent is added to the sintering raw material in the cavity. Injecting a sintering raw material slurry consisting of, after that the negative pressure state in the molding frame body is released to collapse the half mold, thereby injecting the sintering prototype, in the molding method of the sintering prototype, The filler has a melting point higher than that of the sintering raw material. Molding process of sintering original body, which is a particulate material.