JPH01275103A - Molding of sintering prototype - Google Patents

Abstract

PURPOSE:To obtain stably a sintering prototype with a uniform density, by using a member of the material permeable for slurry solvent as shielding member and moisten and swell the shielding member uniformly to impart flexibility and extensibility to it when adhering it closely to a prototype member. CONSTITUTION:A porous moistening material 11 made by mixing uniformly a porous material with water is laid on a pan 10 in layered form, and a shielding member 9 composed of water-soluble polyvinyl alcohol film is placed on said porous moistening material 11, said shielding member 9 being suction- held by a film holding frame 12. The same material as said porous moistening material 11 is laid in layered form to be at a standstill on the upper surface of said barrier member 9 and then said shielding member 9 is uniformly moistened. Thereafter, said porous moistening material 11 on said shielding member 9 is removed and said film holding frame 12 is moved upward, so that swelled shielding member 9 is obtained. Further, said member 9 is suction- contacted along a prototype model 4, while it s is extended with the suction from the side of a prototype model plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method suitable for molding a sintering original body having a complicated shape from a sintering raw material slurry.

C. Prior Art) One of the methods conventionally used for molding a sintering prototype from ceramic powder is the slurry casting method, which is widely used as a molding method for complex shapes.

However, the plaster molds used in the mud casting method have problems such as difficulty in releasing complex-shaped prototypes and lack of durability. For this reason, the present applicant tightly adheres to the molding surface of the original member an impermeable shielding member that is soluble in a slurry solvent or a porous shielding member that is permeable to the slurry solvent. place a frame on the opposite side, fill the frame with particulate matter, seal the top surface of the particulate matter, and create a negative pressure inside the frame to attract the shielding member to the particulate matter side. Then, the original member is released from the shielding member to form a mold having a molding surface, and this mold is matched with another mold formed in the same manner to form a cavity, and the mold is heated in the cavity. Previously, an invention was proposed in which a slurry made by adding a solvent to a solidified raw material is injected, and then the negative pressure inside the frame is released to collapse the molded surface.

(Unexamined Japanese Patent Publication No. 62-268603) (Problems with the Prior Art) However, the above invention also has the following problems. That is, in the process of closely adhering a non-porous shielding member that can be dissolved by a slurry solvent or a porous shielding member that can be penetrated by a slurry solvent to the molding surface of the original part, heating with a burner or the like is performed to increase the flexibility of the shielding member. It is undergoing softening treatment. For this reason, for example, when a polyvinyl alcohol film is used, heating causes a dehydration reaction and deterioration, producing polyvinyl ether, resulting in a portion that becomes insoluble in the solvent, and when the slurry is cast, absorption of the slurry solvent from the shielding member occurs. Removal may become uneven, non-uniform inking may occur, penetration of the slurry solvent may become poor, and partial defects (cavities) may occur, resulting in defects in the sintered body. Further, the partial deterioration of the shielding member may cause concentrated stress, which may cause the shielding member to partially break and cause the slurry to flow out.

Even when other resins are used as the shielding member, the same problem occurs due to chemical reaction deterioration due to heating.

(Object of the Invention) The present invention was made in view of the above-mentioned drawbacks, and it provides a shielding member with uniform flexibility and extensibility without using heat, and allows it to adhere to the original member, thereby making it healthy. The object of the present invention is to enable molding of a sintering original body.

c) Means for Solving Problems) In order to achieve the above object, the present invention utilizes the
In the method for forming a sintering prototype shown in No. 2-268603, a member made of a material that can be penetrated by the slurry solvent is used as the shielding member, and when the shielding member is brought into close contact with the original member, the shielding member is uniformly attached. It is characterized by being humidified and swollen, thereby imparting flexibility and extensibility to the shielding member.

A detailed explanation will be given below based on experimental examples and examples.

Experimental Example 1> An experiment was conducted on swelling properties by changing the solvent and the type of shielding member. As a method, samples of the shielding member were placed in beakers filled with each solvent to examine the solubility, and the results are shown in the table below.

As described above, swelling was possible by combining an appropriate solvent and a shielding member. In this experiment, the dissolved material was also considered to swell.

Experimental Example 2 In order to investigate a uniform humidification method, a water-soluble polyvinyl alcohol film was used as a shielding member, water was used as a solvent, and methods of immersion in the solvent, spray method, and immersion in solvent-containing powder were investigated. did.

In the solvent immersion method, the film is immersed in water in a beaker for about 3 minutes. The spray method uses an ultrasonic humidifier from the spray port.
The film is treated with a water droplet at the 0 crn position. The burial method uses porous material (Showa Denko 0 shares) AL 13 PC1 particle size 80
The film is immersed for 3 minutes in a porous humidifying material prepared by uniformly adding 3 to 5% by weight of water to μ).

As a result, it was found that the dipping method and spraying method resulted in films that were easily torn and lacked flexibility and extensibility.

In the case of the embedding method, the film was humidified uniformly, and the film also exhibited good flexibility and extensibility.

<Example> Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 shows an original model plate (1), which consists of a base (3) which has a hollow chamber (2) inside.
) on the top of the original model (4) and the protrusion for the slurry flow path (5).
) is attached, and the base (3) and the original model C4) are provided with a plurality of ventilation holes (6) communicating with the hollow chamber (2), and the hollow chamber (2) is connected to the hose C7) and the original model C4). Switching valve (
8) is connected to a suction device (not shown). Next, FIG. 2 shows a state in which the shielding member (9) is subjected to humidification and swelling treatment.

That is, a porous material (Showa Den I) is placed in a saucer-shaped container (10).
A porous humidifying material (11) prepared by adding 3 to 5% by weight of water uniformly to C strain AL 1B PC, particle size 80μ) is spread uniformly in a layer of approximately 2crn, and then a water-soluble material with a thickness of 30μ is spread. Shielding member (9) made of polyvinyl alcohol film
is adsorbed and held by the film holding frame (12) and placed on the porous humidifying material (11). The film holding frame (12) has a hollow chamber (I3) inside the wall, and a suction hole (14) communicating with the hollow chamber (13) is bored in the bottom plate, and the hollow chamber C13). is connected to a suction device (not shown) via a hose (15) and a switching valve (16). Such a holding frame (12) has a hollow chamber (
13) and a suction device (not shown) are communicated with each other to connect the holding frame (1
2) The shielding member (9) is held by suction by being pressed against the upper surface of the shielding member (9) while applying a suction action to the lower surface, and placed on the porous humidifying material (11).

Next, the porous humidifying material (
Spread the same material as in 11) evenly in a layer of about 1 crn and make a second layer.
It will be in the state shown in the figure. The shielding member (9) is left still in this state for about 3 minutes to uniformly humidify the shielding member (9). Then the shielding member (9)
The swollen shielding member (9) is removed by removing the upper porous humidifying material (11) and raising the film holding frame (12).
)was gotten.

Next, the hollow chamber (2) of the original model plate (1) is communicated with a suction device (not shown), and while a suction action is exerted on the surface of the original model plate (1), the swollen shielding member (9) is moved to the holding frame. (12) and placed on the surface of the original model plate (1). As a result, the shielding member (9) is extended by the suction action from the original model plate (1) and is brought into close contact with the original model (4) by suction. Thereafter, the suction action of the holding frame (12) is cut off and the holding frame (12) is removed from the original model board (1), and a coating layer (17) is applied to the upper surface of the shielding member (9).
form.

The coating mold layer (17) was mainly composed of diatomaceous earth of several microns, which is a porous aggregate, and was formed by applying a coating agent made by adding graphite and ethyl alcohol as a solvent to this.

Next, a molding frame (18) is placed on top of the original model board (1), and particles such as organic aggregate are placed in the hollow space defined by the molding frame (18) and the original model board (1). Filling material (19) consisting of
The original model plate (1) and the molding frame (18) are vibrated together with a vibrator, and the filling material (19) is filled with
) to increase the packing density.

The molding frame (18) has an annular decompression chamber (20) in the main body.
), and the decompression chamber (20) is connected to a hose (21).
and a switching valve C22), and is connected to a suction device (not shown).

In addition, a large number of ventilation holes (28) communicating with the decompression chamber (20) are bored in the inner wall of the main body, and the inner wall surface of the main body has holes to prevent the filling material (19) from passing through. A filter (24) is installed to develop fine grains.

In this state, the decompression chamber (20) and a suction device (not shown) are communicated with each other, and a non-ventilated sheet (25) is placed on the upper surface of the molding frame (18), resulting in the state shown in FIG. Through this operation, the filler (19) is subjected to external pressure via the sheet (25) due to 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, communication between the hollow chamber C2) of the original model board (1) and a suction device (not shown) is cut off, and when the molding frame (18) is separated from the original model board (1), a coating layer (17) is formed. shielding member (9)
is adsorbed to the filler (19) side, and then the mold is cut out to obtain a half-split mold for injecting raw material slurry for sintering.

By the same operation as above, another half mold is molded and the two half molds are matched, and the raw material slurry for sintering I7-
The injection tube (28) that communicates with the bottom of the storage tank (27) of (2G)
) is communicated with the slurry flow path (29) to bring it into the state shown in FIG.

In the example, the sintering raw material slurry IJ-(26) is a mixture of 100 parts of 0.5μ alumina powder and 1.0 parts of a binder made by emulsifying polyvinyl alcohol and wax (as organic solid content) and 20 parts of water. It was assumed that

In this state, the gate (30') is opened and the sintering raw material slurry (26) is injected into the cavity C31).

Sintering raw material slurry injected in this way (26)
The water permeates the shielding member (9) and is further sucked into the coating layer (17) and filler (19), resulting in the cavity (3
1) Inside is a ceramic original body made of aggregate (32)
is formed.

This state is maintained for a predetermined period of time to solidify the ceramic original body (32) to a state where the mold can be retained even if the ceramic original body (32) is demolded.

Next, the communication between the decompression chambers C20) of the molding frames (18) (18) which are vertically aligned and the suction device (not shown) is cut off, and the decompression state in the molding frames (18) is released, and at the same time the upper sheet (25) ) is removed, and then the upper molding frame body (18) is removed.

By this operation, the filler material (1
9) will be destroyed. In this state, the filler (19) is removed by air blowing to remove the solidified ceramic original body (32), the shielding member (9), the coating layer C17) which has adsorbed moisture, and the moisture condensation layer of the filler (19). (33) is made into one body and taken out, resulting in the state shown in FIG.

When this is fired, the moisture condensation layer (33) of the filler (19) made of particulate matter such as organic aggregate is burned away, and the mold layer (1
7) is dried and naturally disintegrated, yielding a ceramic sintered body with a desired shape and smooth skin.

In the examples, alumina powder was used as the aggregate of the raw material slurry for sintering, but other ceramic powders may be used. Further, the raw material for sintering may be not only ceramics but also powder metallurgy materials using metals and non-metals.

Furthermore, although a polyvinyl alcohol composition was used as the water-soluble shielding member in the examples, polyethylene glycol, polyethylene oxide, methyl cellulose,
Carboxymethyl cellulose, sodium polyacrylate,
Compositions consisting of polyvinyl pyrrolidone, polyvinyl butyral, etc. may also be used.

In addition, in the example, a water-soluble material was used as the shielding member, but if it is a polymer resin film that can be penetrated by the solvent in the raw material slurry for sintering and can be given extensibility by the slurry solvent and can be swelled, water-soluble material can be used. It doesn't have to be.

Furthermore, in the example, a method was adopted in which a porous material was used as the material to increase the flexibility and extensibility of the shielding member and cause it to swell.
A method of placing the liquid in a container (high solvent vapor) for a certain period of time may also be used.

(Effects of the invention) As is clear from the above explanation, since the method of uniformly humidifying the shielding member adsorbed to the original model board with the slurry solvent is used, flexibility and extensibility are uniformly imparted, and the slurry solvent (moisture) The effects of this are significant, such as uniform absorption and removal and inking, and the ability to stably obtain a sintering prototype with uniform density.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the original model plate, Figure 2 is a cross-sectional view showing the humidified state of the shielding member, Figure 3 is a cross-sectional view showing the molding state of the half mold, and Figure 4 is the molding state of the original body. FIG. 5 is a cross-sectional view showing a state in which the original shaped body is taken out. (1): Original model board (9): Shielding member (18):
Forming frame body (19): Filling material (26'): Raw material slurry for sintering (31): Cavity graduate 1 grade 2 illustration order 3 mortars

Claims (1)

[Claims] The shielding member (9) that is permeable to the solvent of the raw material slurry for sintering (26) is uniformly moistened with water or a solvent to swell it, and the swollen shielding member (9) is applied to the surface of the original model plate (1). The molding frame (1) is placed on the original model plate (1) by suction and brought into close contact with each other.
8), fill the molding frame (18) with a filler (19) made of granular material such as organic aggregate, and place the filler (19) on the molding frame (18).
9) Seal the top surface to create negative pressure inside the molding frame (18),
The filling material (19) is solidified in a vacuum and the shielding member (9) is adsorbed to the filling material side, and then the original model plate (1) is released from the shielding member (9) to form a half mold. The half mold is then molded together with another half mold molded in the same manner to form a cavity (31).
) A method for forming a sintering original body, characterized by injecting a sintering raw material slurry (26) into the mold, and then releasing the negative pressure state of the half mold.