JPH0576404B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method suitable for molding and manufacturing ceramic powder or metal/nonmetal powder into a complex-shaped, high-density sintered body having a thick wall portion. .

(Prior art) Conventionally, for example, when manufacturing a high-density sintered body with a complex shape and a thick wall part using ceramic powder, ceramic powder is molded using a slurry casting method, an injection molding method, or a powder pressing method. A method is adopted in which the molded body is molded into a predetermined shape and the molded body is fired. However, in the slurry casting method, the ceramic is made into a slurry state, so there is a problem in that it takes a very long time to fill the mold and dry the molded product.In addition, in the injection molding method, the organic binder is added to the ceramic. Since a large amount of powder is mixed in, it is difficult to make a compact with uniform density and to operate during the degreasing process.Furthermore, in the case of powder pressing, an expensive mold is required to obtain a complex-shaped compact. There were problems such as:

On the other hand, isostatic pressing is known as a method for molding ceramic powder into a uniform, high-density molded body, but in the past, the material before being subjected to this pressure molding method, the so-called original body, was shaped into a complex shape. Since molding is not possible, the isostatic pressing method can generally only mold compacts with simple shapes, and therefore it has been difficult to produce high-density sintered compacts with complex shapes.

(Object of the invention) The present invention was made in view of the above circumstances, and
The object of the present invention is to provide a method that makes it possible to manufacture a high-density sintered body with a complex shape.

(Means for Solving the Problems) The method for producing a sintered body according to the present invention is to provide a non-ventilated flexible mold on the cavity surface of a split mold for molding a prototype body, which has a large number of ventilation holes communicating from the cavity surface to the outer surface. After attaching the flexible film in a removable manner, the split molds are aligned to define a cavity, and after filling the raw material powder of the sintered body into the cavity surrounded by the flexible film, the upper end of the cavity is filled. The opening is covered with a non-ventilated flexible membrane lid, the divided mold is placed in a pressure container, and the pressure container is airtightly closed, and then the pressure inside the pressure container and the cavity is reduced by suction. A liquid is introduced into a pressure-resistant container and the pressure of the liquid is increased to compress and mold the raw material powder into a high density through the flexible membrane and flexible membrane lid, and after completion of the compression molding, from inside the pressure-resistant container. The method is characterized in that the divided mold is carried out, the divided mold is opened, the molded body is taken out, and the molded body is placed in a firing furnace and sintered.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. As shown in Fig. 1, there are many ventilation holes 2 leading from the cavity surfaces 1a and 1b to the back
Split type 3a, 3 with holes a, 2a, 2b, 2b
b, and 2 which is non-breathable and flexible between them.
The two resin films 4a, 4b are sandwiched and molded together to define a cavity.Next, suction covers 5a, 5b are brought into contact with the back surfaces of the split molds 3a, 3b, and the valve 6
Switch a, 6b to vent holes 2a, 2a, 2b, 2
A suction action is caused to occur on the cavity surfaces 1a, 1b via b, thereby causing the resin films 4a, 4b to be attracted to the cavity surfaces 1a, 1b as shown by the two-dot chain line. Next, as shown in FIG. 2, after placing the split molds 3a and 3b on the vibration table 5 with the resin films 4a and 4b adsorbed on the cavity surfaces 1a and 1b, the upper parts of the split molds 3a and 3b are The hopper 6 is carried in, and then the gate 7 is opened to drop and supply the ceramic powder C in the hopper 6 into the cavity, and the oscillators 8a and 8b mounted on the vibration table 5
is driven to vibrate the divided molds 3a and 3b and fill the ceramic powder C into the cavity.

Next, after switching the valves 6a and 6b, the suction covers 5a and 5b are separated from the divided molds 3a and 3b, and the hopper 6 is carried out from the divided molds 3a and 3b, and then, as shown in FIG. membrane 4
A resin film lid 9 of the same quality as those of the molds 3a and 4b is placed over the upper opening of the cavity, and the divided molds 3a and 3b are inserted into the pressure container 10. Next, the pressure container 10
The upper end opening is hermetically closed by the lid 11 (at this point, the lid 11 is closed to the resin film lid 9).
is not pressed against the split molds 3a, 3b), when the valve 12 is switched to vacuum the pressure inside the pressure vessel 10, the pressure inside the cavity surrounded by the resin films 4a, 4b is also reduced.

Next, the lid 11 is completely lowered and the resin film lid 9 is pressed down with the lid 11. That is, the resin film lid 9 and the resin films 4a, 4b are combined with the lid 11 and the split molds 3a, 3b.
Grip with. As a result, when performing isostatic pressing to be described later, the liquid introduced into the pressure vessel 10 is supplied to the upper surface of the resin membrane lid 9 in the same way as the cavity surfaces 1a and 1b, and the resin membrane lid 9 and the resin The ceramic powder surrounded by the membranes 4a and 4b is not locally deformed significantly, and as a result, the ceramic powder surrounded by the resin membrane lid 9 and the resin membranes 4a and 4b is deformed by the subsequent isostatic pressing. , compression molding can be performed accurately into a shape corresponding to the cavity surfaces of the split molds 3a and 3b. Next, the valve 12 is switched to stop the suction into the pressure vessel 10, and then the valve 13 is switched to introduce the liquid into the pressure vessel 10 and increase its pressure, so that the liquid enters the pressure vessel 10. At the same time as the liquid is filled, it flows through the vent holes 2a, 2b and enters between the cavity surfaces 1a, 1b and the resin membranes 4a, 4b, and then the pressure of the liquid is applied to the resin membranes 4a, 4b and the resin membrane cover 9. It acts from the right angle direction. As a result, the ceramic powder C in the cavity is compressed and its density is uniformly increased, and so-called isostatic pressing is performed. Next, the split molds 3a and 3b are taken out of the pressure container 10, the split molds 3a and 3b are opened to take out the molded body, and the molded body is placed in a firing furnace and fired, so that the resin film of the molded body is burned away. A predetermined ceramic sintered body is obtained.

In addition, in the above embodiment, the ceramic powder C was surrounded by the resin films 4a and 4b.
The membrane is not limited to this, and any membrane may be used as long as it is non-air permeable and flexible; for example, it may be a membrane formed by applying resin or synthetic rubber to the cavity surfaces 1a and 1b.

Further, the above method can obtain the same effect even when applied to powder metallurgy using metals and non-metals.

(Effects of the Invention) As is clear from the above description, according to the present invention, a complex-shaped original body having a thick portion can be divided into three parts.
A and 3b are molded, and the original shape is split into mold 3.
Since it is compressed by the isostatic pressing method while being held at points a and 3b, excellent effects such as making it possible to easily and reliably manufacture a sintered body having a complex shape and a uniform high density are achieved.

[Brief explanation of the drawing]

1 to 3 are longitudinal cross-sectional views for explaining the steps of the method of the present invention.

Claims (1)

[Claims] 1. After a non-breathable flexible membrane is removably attached to the cavity surface of a split mold for molding a prototype body, which has a large number of ventilation holes leading from the cavity surface to the outside surface, the split molds are molded together to form a cavity. After filling the raw material powder of the sintered body into the cavity surrounded by the flexible membrane, the upper opening of the cavity is covered with an air-impermeable flexible membrane lid, and the flexible membrane is surrounded by the flexible membrane. The split mold is placed in a pressure-resistant container with the membrane lid on top, and the upper end opening of the pressure-resistant container is hermetically closed with a lid provided with a protrusion on its lower surface. The inside of the cavity is depressurized by suction,
The vicinity of the outer peripheral edge of the upper end opening of the cavity in the flexible membrane lid and the upper part of the flexible membrane are gripped with the protrusion of the lid and the split mold, and the depressurized pressure vessel is A liquid is introduced into the container and the pressure of the liquid is increased to compress and mold the raw material powder into a high density through the flexible membrane and the flexible membrane lid, and after completion of the compression molding, the dividing is carried out from inside the pressure container. A method for manufacturing a sintered body, which comprises carrying out a mold, opening the split mold, taking out a molded body, and placing the molded body in a firing furnace for sintering.