JPH09295195A - Sheet forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet forming method in which a sheet of excellent quality is formed at a low cost, and any special die is dispensed with in the forming. SOLUTION: A forming die 10 comprises an outer frame die 12, a lower die 16 to be slidably fitted to a die space 14 of the outer frame die 12, and an upper die 18. A first forming face 20 is provided on the lower die 16 and a second forming face 22 is provided on the upper die 18 respectively. In addition, a paper or resin sheet 24 is provided on the first forming face 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin plate in which raw material powder is pressed by a set of molds to form a thin plate.

[0002]

2. Description of the Related Art It is known to obtain a sintered compact having a desired shape by pressure-molding a raw material powder of metal, ceramics or the like in a mold and sintering the compact. For example, in the conventional technique of this kind, there is a method disclosed in Japanese Patent Laid-Open No. 3-291199 as a technical idea for obtaining a sintered body of a thin plate. This is because a metal plate having the same shape as the mold space is provided between one of the pair of pressure-molding dies and the raw material powder, and the other die is used with respect to one of the dies. By relatively displacing, the raw material powder is pressure-molded to obtain a thin plate-shaped molded product. The plate body is used as a mounting table for the molded product after the molding process. Therefore, the handling performance of a brittle molded product can be improved.

[0003]

However, in the method disclosed in Japanese Patent Laid-Open No. 3-291199 mentioned above,
When the plate body has irregularities on the surface, or when the elastic modulus of the plate body is high, a point where stress is concentrated on the molded body is generated at the time of pressurizing and separating the mold, whereby the molded product May cause destruction. Further, when the plate body itself has undulations, it may adversely affect the flatness and surface roughness of the molded body, or stress may be concentrated on the molded body, thereby destroying the molded body. Therefore, it becomes difficult to obtain a high-quality molded product with a high yield.

Further, in the above method, the plate itself has to be constructed in accordance with the required degree of accuracy of the flatness and surface roughness of the molded body itself, resulting in a high cost. Since the reuse of the plate body is also required, the accuracy of maintenance for the plate body must be high.

Further, when the plate body is arranged in the mold, a high assembling precision of the forming punch and the plate body is required for the above reason, which causes a problem of high manufacturing cost.

Moreover, when the plate member is to be peeled from the molded product, local stress is applied to the molded product itself, and cracks occur in the molded product.

The present invention has been made in order to overcome the above-mentioned various inconveniences, and moreover, it is possible to supply a high-quality thin plate as a molded body at a low cost and a special mold is required at the time of molding. It is an object of the present invention to provide a thin plate molding method that does not include

[0008]

In order to achieve the above object, the present invention provides a raw material powder between two molds by relatively displacing the first mold and the second mold. In the method of obtaining a molded product by pressing, a first step of disposing a sheet member that disappears by heating on a first molding surface of the first mold, and placing the raw material powder on the sheet member. The second step of performing the first molding surface of the first mold and the second molding surface of the second mold by relatively displacing the first and second molds. A third step of press-molding the raw material powder into a predetermined shape, and a fourth step of obtaining a thin plate-shaped molded product formed by relatively separating the first mold and the second mold from each other. And a fifth step of obtaining a completed thin plate by sintering the molded product obtained in the fourth step, and further comprising the sheet member. It characterized by having a step of allowed to disappear by heating in the fourth or fifth step.

According to this method, since the sheet member is heated to disappear in the fourth step or the fifth step,
There is no need to separate the sheet member from the molded product, and thus no unnecessary force is applied to the molded body. Therefore, cracks and the like do not occur due to the local application of stress.

Further, the present invention is characterized in that the sheet member is paper or a resin material.

As a result, since the sheet member made of paper or a resin material is flexible when the molded body is pressed or released from the mold, the molded body does not have a point where stress is concentrated and the molded body is molded. It is possible to avoid cracks and the like in the body. Further, since the sheet member itself and the shape of the molded product are adapted, it is not affected by the waviness and the like of the metal plate body.

Further, the surface roughness of the sheet member can be freely selected by selecting the sheet member. Therefore, a high quality molded product can be molded, and the yield of the molded product is improved. The sheet member can be supplied at low cost. Therefore, there is an advantage that the cost can be suppressed at low cost.

Furthermore, since the sheet member is appropriately deformed according to the pressure applied to the mold, the mold is not required to have high accuracy. Therefore, the cost of the mold can be reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A method for forming a thin plate according to the present invention will be described below in detail with reference to the accompanying drawings with reference to preferred embodiments.

1A-1E, reference numeral 10
[Fig. 3] schematically shows a molding die according to the present embodiment. This molding die 10 basically comprises an outer frame die 12, a lower die 16 as a first die and a second die 16 which are slidably fitted in a die space 14 of the outer frame die 12. It is composed of an upper mold 18 as a mold. The lower mold 16 has a first molding surface 20,
On the other hand, each of the upper molds 18 has a second molding surface 22. Further, the first molding surface 20 in the mold space 14
A sheet member 24 made of paper or a resin material is disposed on the top.

The molding die 10 according to the present embodiment is basically constructed as described above. Next, its operation, function and effect will be explained.

The first molding surface 20 in the mold space 14
A raw material powder 26 in which an appropriate amount of a binder and a lubricant are mixed is filled on a sheet member 24 made of paper or a resin material provided above (FIG. 1A). After that, the upper mold 18 is displaced downward with respect to the lower mold 16 by a driving source (not shown), and the raw material powder 26 is pressure-molded (FIG. 1B).

Then, the upper mold 18 is separated from the lower mold 16, and after the upper mold 18 is separated from the outer frame mold 12, the lower mold 16 is further raised to obtain a pressure molded product 28 (FIG. 1).
C). Thereafter, the pressure-formed product 28 is transferred to a sintering device (not shown) while being placed on the sheet member 24 (FIG. 1D),
A thin plate is obtained by sintering in the sintering apparatus (FIG. 1E). During this, during the sintering, as described above, the sheet member 24 made of, for example, paper disappears due to the sintering temperature. Therefore, the pressure-molded product 28, which is relatively brittle during transfer, is sufficiently kept in shape by the sheet member 24, the sheet member 24 disappears due to the sintering temperature during sintering, and after sintering, The sintered compact is hardened and secures its shape by its own rigidity. In this case, at the time of pressure molding and releasing, since the pressure molded product 28 and the lower mold 16 have the sheet member 24 interposed therebetween, non-uniform stress does not act on the pressure molded product 28. That is, even if the first molding surface 20 has some irregularities, it is absorbed by the sheet member 24. Therefore, strictness in mold precision is not required.

If a sheet member 24 having a small surface roughness is selected in advance for the thin plate as the completed sintered compact,
It has excellent smoothness. For this reason, the pressure molded product 28
It is not necessary to consider the step of removing the sheet member 24 from the sheet or the maintenance of the sheet member. Therefore, the manufacturing process can be shortened and the cost can be reduced.

Note that FIGS. 1A to 1E according to the present embodiment.
Although the sheet member 24 is provided only on the first molding surface 20 of the lower mold 16 in the molding die 10 of FIG. 1, the second molding surface of the upper mold 18 may be different depending on the quality of the thin plate as the final product. 22
It goes without saying that the sheet member 24 may be arranged on the top.

Specific experimental examples are shown below.

As a raw material powder, an aluminum nitride raw material powder (average particle size 1.2 μm) containing 2% by weight of yttrium oxide and 1% by weight of dysprosium oxide was prepared. Further, the aluminum nitride raw material powder was kneaded with an acrylic resin binder and a lubricant. The outer frame mold 12 uses SKD-11 having a mold space 14 of 61 mm × 61 mm so that the aluminum nitride raw material powder may have a thickness of 0.8 mm on the sheet member 24 provided in the mold space 14. Arranged. Then, the aluminum nitride raw material powder was pressure-molded between the lower mold 16 and the upper mold 18. Then, the lower mold 16 and the upper mold 18 are separated from each other, and a pressure molded product 28 is formed.
I got

At this time, Table 1 shows the results of molding by changing the pressing force and the material of the sheet member by the conventional method and the thin plate molding method according to the present embodiment. Here, the conventional method means a method disclosed in Japanese Patent Laid-Open No. 3-291199, that is, a method in which the sheet member is a metal plate. Further, the numerical values in Table 1 show the number of times that a molded product having no defect was obtained out of 10 times of pressure molding.

[0024]

[Table 1]

As shown in Table 1, the conventional thin plate forming method,
In particular, in the method of dry molding, defects such as cracks occurred in the pressure-molded product, and there were no successful cases at a pressure of 50 to 200 MPa. On the other hand, in the thin plate molding method according to the present embodiment, it is easily understood that the yield of the pressure molded product 28 is excellent. After this, the pressure molded product 28
Is transferred while being placed on the sheet member 24 and is sintered by a sintering device (not shown), and is 2 inches × 2 inches × 0.0
A 25-inch thin plate could be obtained.

[0026]

According to the thin plate forming method of the present invention,
The following effects and advantages can be obtained.

It is possible to supply a high-quality thin plate at a low cost without causing defects such as cracks.

Further, even if the molding surface of the mold has some irregularities, the sheet member absorbs the irregularities, so that strictness in mold precision is not required.

Further, it is not necessary to consider the step of removing the sheet member from the pressure-molded product and the maintenance of the sheet member. Therefore, the manufacturing process can be shortened and the cost can be reduced.

[Brief description of drawings]

FIG. 1A is a schematic vertical cross-sectional view of a molding die according to an embodiment of the present invention in which a sheet member and raw material powder are placed, and FIG. 1B is an exterior view of the molding die of FIG. 1A. FIG. 1C is a schematic vertical cross-sectional view showing a state in which the raw material powder is clamped by lowering the upper die with respect to the frame and the lower die. 1D is a schematic vertical cross-sectional view showing a pressure-formed product that is transferred while being placed on a sheet member, and FIG. 1E is a sintering process. It is a schematic longitudinal cross-sectional view showing the formed thin plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Molding die 12 ... Outer frame mold 14 ... Mold space 16 ... Lower mold 18 ... Upper mold 20 ... First molding surface 22 ... Second molding surface 24 ... Sheet member 26 ... Raw material powder 28 ... Press molding Goods

Claims (2)

[Claims] 1. A method for obtaining a molded product by squeezing a raw material powder between two molds by relatively displacing the first mold and the second mold, wherein A first step of disposing a sheet member that disappears by heating on the first molding surface; a second step of placing the raw material powder on the sheet member; and the first and second molds. A third step of relatively displacing the raw material powder into a predetermined shape between the first molding surface of the first mold and the second molding surface of the second mold; A fourth step of relatively separating the first mold and the second mold to obtain a thin plate-shaped molded product, and sintering the molded product obtained in the fourth process A fifth step of obtaining a completed thin plate, and further comprising the sheet member as the fourth or fifth step.
The method for forming a thin plate, which has a step of heating and erasing in the step of. 2. The method for forming a thin plate according to claim 1, wherein the sheet member is paper or a resin material.