JP2851726B2 - Hot press method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for firing a ceramic powder or a metal powder by a hot pressing method.

[0002]

2. Description of the Related Art Conventionally, a hot pressing method has been employed as a method for sintering ceramic powder or metal powder. Therefore, a hot press apparatus conventionally used is shown in FIG. The hot press device 11 includes a die 12 made of graphite or the like, a lower punch 13 and an upper punch 14. As a method of sintering the ceramic powder or the metal powder by the hot pressing device 11, a space 15 formed by the die 12 and the lower punch 13 is filled with the ceramic powder or the metal powder or a preform 16 thereof. The sintering is performed by applying pressure by the upper punch 14 and heating to a predetermined temperature by a heating body (not shown).

[0003]

However, according to the hot press apparatus 11, there is a gap a between the die 12, the lower punch 13, and the upper punch 14, all of which are made of graphite or the like. Therefore, the gap a tends to increase due to repeated use at a high temperature.

As described above, the die 12 and the punches 13, 1
When a gap a exists between the powder 4 and the powder 4, when the powder 16 to be pressed is pressed by the upper punch 13, a part of the powder enters the gap a, so that sufficient pressure is applied to the powder. In addition, there is a problem that projections are formed at the ends of the sintered body and so-called burrs are generated. Dice 1
When the sintered body is taken out of the lower punch 2, a minute defect occurs on the outer peripheral edge of the lower punch 13.

Further, the punches 13 and 14 are cooled during firing.
There is a problem that a tensile stress acts on the sintered body due to a difference in the coefficient of thermal expansion between the sintered body and the sintered body, thereby causing adverse effects such as a large loss of the end of the sintered body.

[0006]

Means for Solving the Problems As a result of studying the above problems, the present inventor has found that the die and the lower part are so arranged that the area for filling the powder to be pressed is inside the effective area for pressing. An edge member that can be deformed by pressure is disposed at an outer edge along the inner surface of the space formed by the punch, and the powder to be pressed is filled inside the edge member, and the powder to be pressed is pressed by the upper punch. It is characterized by applying body pressure and heating.

[0007]

According to the present invention, an edge member which can be deformed against pressure is arranged at an outer edge portion along a die inner surface of a space formed by the die and the lower punch, and pressure is applied by the upper punch. It is possible to prevent the powder to be pressed from entering the gap between the die and the punch of the powder to be pressed, thereby preventing the sintered body and the punch from being chipped, and ensuring stable firing. It can be performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a schematic layout diagram of a hot press apparatus used in the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG.
In FIG. 1, a hot press apparatus 1 includes a die 2 made of graphite or the like, a lower punch 3 and an upper punch 4. A heating means (not shown) is provided outside the die 2.
Is arranged.

According to the present invention, an edge member 6 that can be deformed by pressure is disposed at an outer edge portion of the space 5 formed by the die 2 and the lower punch 3 along the inner surface of the die. Then, ceramic powder or metal powder,
Alternatively, the pressurized powder 7 made of these preforms is filled. It is desirable that the edge member at this time has substantially the same width as the thickness of the powder to be pressed filled therein.

According to the method of filling the powder 7 to be pressed, the filling area A of the powder to be pressed is located inside the pressure effective area B (A> B).

The edge member 7 used in the above construction must be made of a material which can be deformed by itself and does not adversely affect the sintered body, and preferably has a predetermined thickness. A sheet material made of graphite is most preferred. The edge member preferably has a thickness of 0.2 mm or more, and if it is 0.2 mm or less, the effect of preventing the generation of burrs tends to be insufficient.

Next, FIG. 3 shows a state in which the edge member 6 is deformed by pressing with the upper punch. In the pressurized state, the edge member 7 enters the gap a between the die and the punches 4 and 7, and prevents the powder 7 to be pressed from entering the gap a. As a result, the powder 7 to be pressed is always pressed in the pressure effective area.

Next, the present invention will be described with reference to the following examples. According to the example, graphite sheets having different thicknesses were used as the edge members, and they were arranged as shown in FIGS. 1 and 2. Then, after filling the inside of the edge member with Al ₂ O ₃ powder, 0.1% of Al ₂ O ₃ is added.
Heating and pressurization was performed at 1700 ° C. at a pressure of 3 ton / cm ² .
Each of the edge members was fired 10 times, and the presence or absence of burrs at the end of the sintered body, the presence or absence of a defect in the sintered body, and the presence or absence of a minute defect in the punch were observed. As a comparative example, the same firing was performed without using the edge member, and the same evaluation was performed. The results are shown in Table 1.

[0014]

[Table 1]

According to Table 1, when the edge member was not used at all, many defects were observed, but improvement was observed by installing the edge member. In particular, by setting the thickness of the edge member to 0.4 mm or more, no burrs and defects of the sintered body and no minute defects of the punch were observed.

[0016]

According to the present invention, the outer edge along the inner surface of the die in the space formed by the die and the lower punch,
By arranging an edge member having the same width as the thickness of the powder to be pressed filled therein and being deformable with respect to pressure, and pressing the upper punch, the pressing of the powder to be pressed is performed. The powder can be prevented from entering the gap between the die and the punch, thereby eliminating the loss of the sintered body, improving the yield and simplifying the processing of the sintered body because no burr occurs. And the punch can be prevented from being minutely damaged, and the life of the punch can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic layout view of a hot press apparatus used in the present invention.

FIG. 2 is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a view showing a state in which an edge member is deformed at the time of pressing in FIG. 1;

FIG. 4 is a schematic layout diagram of a conventional hot press apparatus.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Hot press apparatus 2 Dice 3 Lower punch 4 Upper punch 6 Edge member 7 Pressurized powder

Claims (1)

(57) [Claims] An outer peripheral portion along an inner surface of a space formed by a die and a lower punch is provided with an edge member deformable with respect to pressure, and the inside of the edge member is filled with a powder to be pressed. A hot pressing method, wherein the pressurized powder is pressurized and heated by an upper punch after the pressurized powder is installed so as to be filled inside the pressurized effective area.