JPH0570561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for molding powder using isostatic press molding.

(Prior art) Conventionally, when powder is molded using the isostatic press molding method, the powder is placed in a rubber bag a as shown in Figure 4.
Fill the opening of rubber bag a with rubber band b.
Alternatively, as shown in Fig. 5, fill the rubber tube c with powder and close the opening of the rubber tube c with a rubber band b, or as shown in Fig. 6, fill the powder into a rubber tube c with a thickness of 5 to 10 mm. The rubber tube d was filled with the rubber tube d, and a 5-10 mm thick rubber or stainless steel lid e was glued or banded to the rubber tube d (see g), and then hydrostatic press molding was performed. . Note that f ₁ in Fig. 7 is a molded product formed using the rubber bag a shown in Fig. 4, and f ₂ in Fig. 8 is a molded product formed using the rubber tube c shown in Fig. 5. f ₃ in FIG. 9 shows a molded body formed using the rubber cylinder d and lid e in FIG. 6, respectively.

(Problems to be Solved by the Invention) In the conventional powder molding method shown in FIGS. 4, 5, and 6, the amount of deformation during hydrostatic press molding is large, as shown in FIGS. 7, 8, and 9. It is difficult to obtain a molded product with the desired size and shape, and after molding a molded product larger than the desired size, processing such as cutting and polishing is performed to obtain a molded product with the desired size and shape. I was trying to get it. For example, 100mmφ, thickness 0.4
When a thin rubber tube with a diameter of 300 mm and a length of 300 mm is filled with 1500 ml of powder and isostatic press molded, the dimensions of the obtained molded product are approximately 80 mmφ and 160 mm in length.
Rubber wrinkles were formed at both ends of the molded product, and 10 mm of both ends were cut off to obtain a molded product with a length of 140 mm. Furthermore, the cylindrical surface has unevenness, so in order to make it a perfect cylindrical surface, it was ground by 10mm and had a diameter of 60mm.
A molded body was obtained. In other words, 1500ml of powder is hydrostatically press-molded to obtain a molded product of π×4×4×16≒804.25ml, and then machined to obtain a molded product of π×3×3×
14 = 395.64 ml of molded body was obtained, and the difference was
408.6ml, 50% of the molded body after isostatic pressing
It was necessary to whittle away some of the strength, and that amount was wasted. Further, the machining process took about 9 hours, and a lot of time was required to obtain a molded product having the desired size and shape.

(Means for Solving the Problems) The present invention addresses the above-mentioned problems by filling powder into a container made of a material such as styrofoam that has shape retention properties and shrinks under pressure. Then, the container was covered with a flexible hollow body, and then a vacuum was drawn between the container and the hollow body to bring the hollow body into close contact with the container, and then the opening of the hollow body was closed. Later, a method for forming powder characterized by hydrostatic press molding was adopted, and its purpose was to provide an improved method for forming powder that could reduce machining allowances and processing time. It is in.

(Function) As described above, the method for molding powder of the present invention involves filling the powder into a container made of a material such as expanded polystyrene that has shape retention properties and shrinks under pressure. A rubber bag that does not have shape retention properties,
Compared to the conventional case where the rubber tube is filled and then subjected to isostatic press molding, it is possible to obtain a molded product with dimensions and shape close to the desired size after isostatic press molding, and the machining allowance and processing are reduced. less time.

(Example) Next, the powder molding method of the present invention will be explained with reference to FIG.
A 180 mm hard container made of foamed polypropylene, with the bottom opening closed by the bottom lid 3.
Filled with 900 ml of powder, then closed the upper opening of the container 1 with the upper lid 2, and then closed one opening with a rubber band, 100 mmφ, 300 mm long,
The container 1 was covered with a thin rubber tube (not shown) with a thickness of 0.4 mm, and then the space between the container 1 and the rubber tube was evacuated using a vacuum pump to bring the rubber tube into close contact with the container 1. After closing the other opening of the same rubber tube with a rubber band, isostatic press molding (1000
(Kg/ ^cm2 ) to form a cylindrical molded body with a diameter of 65 mm and a height of 145 mm. After molding, both ends were ground 2.5mm each, and the cylindrical surface was ground 2.5mm, resulting in a diameter of 60mmφ and height.
Obtain a 140 mm molded body. As mentioned above, only 900ml of powder is required to obtain a 60mmφ and 140mm height, and compared to the conventional case, the difference is 1500ml.
-900ml = 600ml, and the cutting allowance is also (65mmφ x 145mm) (6.5/2) after hydrostatic pressing ² π x 14.5 = 481.1
The result is 85.31 ml, which is obtained by subtracting (60 mmφ x 140 mm) (6/2) ² π x 14 = 395.84 ml after machining from 5 ml.

In the above embodiment, a hard container made of foamed polypropylene is used as the container 1, but a soft container made of foamed polypropylene may also be used. In that case, the surface finish of the molded body will be better than that of the embodiment shown in FIG. 1 above.

An example of forming a plate-shaped object is as follows: Fill a foamed polypropylene soft container with a thickness of 5 mm and internal dimensions of 150 mm x 100 mm x 200 mm with 3000 ml of powder, and close the container with a lid. Thereafter, a plate-shaped body is formed through the same process as in the embodiment shown in FIG. In this case, a 124 mm x 83 mm x 165 mm plate-like body with very little deformation and a good surface finish was obtained.

Further, an example of forming a hollow molded body will be explained with reference to FIGS. 2 and 3. The lower end opening of a foamed polypropylene soft container 1 having a thickness of 10 mm is closed with a bottom lid 3, and a stainless steel core 4 is inserted into the container. The powder 5 is inserted into the container 1, and its lower end is inserted into the hole in the bottom lid 3, and the space between the lower end of the core and the bottom lid 3 is sealed with clay 6. Then, the powder 5 is inserted into the container 1. After filling the container 1, the upper end opening of the container 1 is closed with the upper lid 2, and the gap between the upper end surface of the core and the upper lid 2 is sealed with clay, and then the container 1 is placed in a thin rubber bag 7 with a thickness of 0.4 mm.
The space between the container 1 and the rubber bag 7 is then evacuated using a vacuum pump to remove the rubber bag 7.
is brought into close contact with the container 1, and then the opening of the rubber bag 7 is closed with a rubber band 8, followed by isostatic press molding to form the hollow molded product shown in FIG. 3.

(Effects of the Invention) As described above, the method for molding powder of the present invention involves filling the powder into a container made of a material such as expanded polystyrene that has shape retention and shrinks under pressure. A rubber bag that does not retain the shape of powder,
Compared to the conventional case where the rubber tube is filled and then subjected to isostatic press molding, it is possible to obtain a molded product with dimensions and shape close to the desired size after isostatic press molding, and the machining allowance and processing are reduced. It has the effect of reducing time.

Although the present invention has been described above with reference to embodiments, it goes without saying that the present invention is not limited to such embodiments, and that various design modifications can be made without departing from the spirit of the present invention. .

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of a container used in the powder molding method of the present invention, FIG. 2 is a side view showing another example of the same container, and FIG. 3 is a perspective view showing an example of the molded product. Figures 4, 5 and 6 are perspective views showing examples of conventional containers, and Figures 7, 8 and 9 are perspective views showing examples of molded bodies. 1, 2, 3... Container, 5... Powder, 7... Hollow body.

Claims (1)

[Claims] 1 Powder is filled into a container made of a material such as styrofoam that has shape retention and shrinks under pressure, and then the container is covered with a flexible hollow body, and then the same container and the same hollow body are covered. A method for molding powder, which comprises: drawing a vacuum between the hollow body and the container to bring the hollow body into close contact with the container; then, after closing the opening of the hollow body, hydrostatic press molding is performed.