JPS62267401A - Method for molding sintered member - Google Patents

Abstract

PURPOSE:To prevent the generation of cracking by interposing a hard org. elastic material between packed powder and male mold at the time of compacting powder for a sintered member by a metallic mold. CONSTITUTION:The compounded powder 5 for a sintered hard alloy is injected in a prescribed amt. as uniformly as possible into the metallic mold assembled by the respective members of a cylindrical female mold 1, lower male mold 2 and upper male mold 3. The hard org. elastic material (polyurethane rubber plate, etc.) 6 is then placed on the powder 5 and the mold 3 is pushed into the mold 1 by a press machine to exert the prescribed pressure to the powder and to form a green compact. The surface of the green compact in contact with the rubber plate 6 has slight ruggedness and the green compact is sintered as it is or after slight grinding. The thin sintered member sized about 0.5-2.0mm is thus efficiently produced without generating crack.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an improvement in the manufacturing method of cemented carbide, sometimes sintered metal, ceramics, and cermets.

(1) Conventional methods for manufacturing sintered parts containing cemented carbide include the so-called hot press method, in which powders of various components are mixed to prepare a finished powder, and this powder is sintered at the same time as the compacted powder. A cold press method is known in which the material is molded into a predetermined shape and then sintered in a separate step.

Since the present invention relates to improvement of the powder compaction method in the cold press method, further explanation will be given.

The powder compaction method in the cold press method includes a method using a mold and a method using a rubber mold, and the present invention belongs to improvements in the method using a mold.

In the mold pressing method, powder is injected into the female die of a mold made of a female die made of hardened steel or cemented carbide and two upper and lower male dies, and then pressed by the upper and lower male dies. It is known to create a green compact by applying pressure. However, if the desired green compact is thinner than its surface area, cracks often occur. In such cases, it is necessary to make a green compact that is sometimes several times thicker than the desired thickness, and grind it to the desired dimensions before or after sintering, which requires a large amount of resources and man-hours. There is a problem with this.

(c) Problems to be solved by the present invention In the production of thin sintered members with a thickness of 0.5 to 2.0 mm, the demand for which is rapidly increasing in recent years, the green compact production method using the conventional mold method The aim is to save valuable resources and improve productivity by eliminating these drawbacks.

B.) Means for solving the problems The present invention provides a new method for producing a green compact to solve the above-mentioned problems, and its basic points are as follows.
By interposing an elastic plate between the filler powder and the male die and applying pressure, cracks can be prevented and a thin powder compact can be obtained.

The main cause of cracks in powder compacts is the uneven packing density of the powder injected into the mold, and it is clear that this occurs due to slippage between particles during compaction. It is theoretically impossible to inject blended powder into a mold with uniform density.

However, when the filling thickness is large, slight non-uniformity in the packing density is absorbed by each other, and slippage between particles does not occur and cracks do not occur. However, if the powder filling thickness is small, the non-uniformity of the density is not absorbed and causes slippage between particles, causing cracks.

In the present invention, unevenness in powder packing density is absorbed by creating slight irregularities with an elastic body interposed between the powder and the male mold, and a thin powder compact can be efficiently manufactured without cracking. can do.

(@Example) An example of the production of a perforated carbide disk-shaped compact with a diameter of 120 mm, a hole diameter of 22 mm, and a thickness of 1 mm is shown below.

Figure 1 1 is a cylindrical female mold with an inner diameter of 120mm, 2 is an outer diameter of 120mm
The lower male type has an outer diameter of 120 and a hole diameter of 22.
Upper male mold of W, 4 is 2 rods with outer diameter 2211s, 6 is thickness 2
It is a polyurethane rubber temporary that fits lightly with the female molds 1 and 2 rods 4 in the intestine.

First, approximately 130P of blended powder 5 for cemented carbide is injected as uniformly as possible into the mold assembled from each member of 1.2.3.
A polyurethane rubber plate No. 6 is placed on top of the mold, and then the Fresne machine is operated to push the upper mold 3 into the female mold 1, applying a pressure of 1 ton per 1 d of surface area of the powder compact. Thereafter, the green compact is taken out from the mold according to a conventional method.

Slight irregularities occur on the surface of the removed powder compact that is in contact with the polyurethane rubber, but depending on the required precision of the product, it is sintered as it is or after a slight grinding is performed in a conventional manner.

The organic hard elastic body shown in No. 6 is not limited to a polyurethane rubber plate, and the powder is not limited to a cemented carbide powder.

FIG. 2 shows an enlarged cross-section of a powder compact produced by the method according to the invention, and FIG. 3 shows a known compact, ! Fig. 4 shows an enlarged cross-section of the green compact, and a shows the state of cracks that occur.

[Brief explanation of drawings]

The figures are for explaining the implementation and examples of the present invention, and FIG. 1 is a cross-sectional view of the mold structure in the present invention, FIG. 2 is an enlarged cross-sectional view of the powder compact according to the present invention, and FIG. The figure is a sectional view of a mold structure made by a known method, and FIG. 4 is an enlarged sectional view of a green compact made by a known method. 1-Female mold 2-Lower male mold 3-Upper male mold 4-2 rod 5-Powder (green compact) 6-Organic hard elastic body a-Crack

Claims (1)

[Claims] A method for compacting a sintered member, in which a hard organic elastic body is inserted between the inserted powder and the punch when the powder for the sintered member is compacted using a mold.