JPH04301002A - Method for compacting powder - Google Patents

Abstract

PURPOSE:To compact the powder into even high-quality thin-walled products of intricate shapes at a low cost by sufficiently packing the powder when its green compact is formed. CONSTITUTION:The raw powder 12 is placed between a couple of stainless steel sheets 11 having plasticity and clamped. The sheets 11 holding the powder 12 between are supported by the upper and lower metallic dies 16 and 15 and plastically deformed by the gas pressure, hence the powder is compacted and formed, and the green compact 18 of the powder 12 is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-molding method in powder metallurgy for producing mechanical parts by press-molding raw powder or mixed powder.

0002

BACKGROUND OF THE INVENTION In powder metallurgy, when manufacturing mechanical parts by press-molding raw material powder or mixed powder, a method of compression-molding with a press using various molds is generally used.

FIGS. 6 to 8 show a conventional powder compaction method. As shown in FIG. 6, when molding a green compact such as metal or ceramics, a capsule 101 made of glass or the like is used.
is filled with powder 102 and covered with a lid 103, and then welded 104.
Seal with. And H. I. P. Equipment (HOT
ISOSTATIC PRESSING) or C. I. P. Equipment (COLD ISOSTATIC
Pressure P is applied using a device such as PRESSING.

By the way, in order to add a shape to a powder compact, as shown in FIG. After filling with a lid 113 and sealing with welding 114, this is pressurized to form a compacted powder body 11.
5 is being processed. Further, as shown in FIG. 7, after the powder is press-molded into a suitable shape, the powder 121 is shaped into a desired shape by machining such as cutting.

[0005]

[Problems to be Solved by the Invention] In the conventional powder compaction method as described above, it is difficult to produce products that are thin and have a somewhat complex shape, for example, a cup-shaped product as shown in FIG. You may want to manufacture it. in this case,
Using a hollow capsule 131, this capsule 131
The inside is filled with powder 132, sealed with a core 133 and a lid 134, and pressurized to process the green compact. Alternatively, a thin-walled shape is obtained by performing machining on the molded green compact.

However, it is difficult to fill the powder 132 sufficiently and uniformly into the narrow gap between the hollow capsule 131 and the core 133 due to the shape, and if the powder 132 is not filled sufficiently, the pressure may increase. There is a problem that defects occur in the powder. In addition, molded compacts are generally brittle, and cracks are likely to occur during machining, and a large amount of excess material must be left in the compacts before machining, making them expensive. There is a problem in that a large amount of powder is discarded, leading to an increase in costs.

[0007] The present invention is intended to solve these problems, and an object of the present invention is to provide a method for press-molding a powder compact at low cost and with high quality.

[0008]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the method of press-molding powder of the present invention involves sandwiching raw material powder between a pair of plate materials having plastic properties, and pressing the plate materials in the sandwiched state. This method is characterized in that the raw material powder is compacted and molded at the same time by plastic molding.

[0009]

[Operation] A powder compact is formed by filling a predetermined amount of raw material powder between a pair of plates and sandwiching them, and plastically forming the plates into a predetermined shape using a machine tool in this sandwiched state. At this time, the powder compaction and molding of the raw material powder are performed simultaneously.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows the principle of a powder processing and molding method according to an embodiment of the present invention, and FIGS. 2 to 4 show products molded by the powder processing and molding method.

In this embodiment, a Ni alloy is used as the powder. First, as shown in FIG. 1(A), Ni alloy powder 12 is evenly filled between two stainless steel plates 11 as plate materials. Then, as shown in FIG. 1B, the outer periphery of the stainless steel plate 11 is sealed by welding 13, and the gas generated from the powder 12 is removed by a vacuum pump (not shown) connected via a pipe 14.

Next, as shown in FIG. 1(C), the lower mold 15
A stainless steel plate 11 holding powder 12 is placed thereon, and the stainless steel plate 11 is supported by an upper mold 16 while a forming gas 17 is supplied inside to perform pressure molding. In addition,
For two-phase stainless steel plates, this pressure forming is carried out at a temperature of 950 DEG C. and a strain rate of about 2.times.10@-4 S@-1.

[0014] Then, the molding is completed, and the stainless steel plate 11
When the lower die 15 comes into contact with the lower mold 15, the gas pressure P is increased, for example,
Powder 12 is compacted at a pressure of 00 to 150 kgf/cm2. At this time, it is desirable to apply compressive stress to the stainless steel plate 11 to prevent defects from occurring between the powders by applying back pressure together with the molding pressure. After powder compaction, the stainless steel plate 11 is taken out from between the lower mold 15 and the upper mold 16, and finally the stainless steel plate 11 is removed by cutting or the like, as shown in FIG.
As shown in (D), a green compact 18 of Ni alloy is obtained.

By press-molding the powder 12 in this manner, a box-shaped powder compact 19 as shown in FIG. 2 can be easily obtained. Note that the compacted product is not limited to such a shape, but may have any shape that can be formed by plastic molding, such as the cup-shaped cover 20 shown in FIG. 3 or the reinforcing material 21 for a door panel shown in FIG. 4. It can be molded into anything.

FIG. 5 shows the principle of a powder processing method according to another embodiment of the present invention. In this example, Ti was used as powder.
-Using an Al alloy. First, as shown in FIG. 1(A), Ni alloy powder 22 is evenly filled between two stainless steel plates 11 as plate materials. Then, as shown in FIG. 5(B), the outer periphery of the stainless steel plate 11 is seal-welded 13. Next, as shown in FIG. 5(C), powder 22 is placed on the lower mold 15.
A stainless steel plate 11 sandwiching the stainless steel plate 11 is placed thereon, supported by an upper die 16, and a forming gas 17 is supplied inside to perform pressure forming.

Then, the molding is completed, and the stainless steel plate 11
When the lower mold 15 comes into contact with the lower mold 15, the stainless steel plate 11 is
and the upper mold 16, as shown in FIG. 5(D). I. P. The powder 12 is compacted (pressure P
)do. In addition, in the compacted powder after superplastic forming (950°C), the Ti-Al alloy powder 22 has a larger particle size and higher deformation stress than the Ni alloy powder, so it is
00 kgf/cm2). After powder compaction, by removing the stainless steel plate 11, the T
A green compact 18 of i-Al alloy is obtained.

In each of the above-mentioned embodiments, metal powder was pressure-molded, but a mixed powder of ceramics such as alumina or zirconia and metal may also be formed. In addition to stainless steel plates, α+β titanium (Ti-6Al-4V, Ti-6Al
-6V-2Sn, molding temperature 900℃) and aluminum alloy (fine grain 7475, molding temperature 510℃), etc., and for molding a mixture of aluminum powder and silicon carbide particles,
If you form a sandwich with 475 aluminum alloy plates,
A SiCp/Al composite is obtained.

As described above, in this example, the powder is not filled into a narrow gap, but is placed on a flat plate and pressed with another flat plate from above, making it easy to fill the powder. By setting the amount, you can control the thickness of the powder compact. Furthermore, by using superplastic material for the plate material, it is possible to apply a large amount of pressure to the powder, making it possible to obtain a wide variety of product shapes. Furthermore, since the powder is pressed and molded while being held between the plate materials, the powder is less likely to be unevenly distributed and a sintered body of good quality can be obtained.

[0020]

Effects of the Invention As described above in detail with reference to examples, according to the method for pressure molding powder of the present invention, the raw material powder is sandwiched between a pair of plate materials having plastic properties. Since the plate material is plastically formed in the state and compacting and molding of the raw powder are performed at the same time, it is possible to form a high-quality green compact by filling the powder sufficiently uniformly between the pair of plate materials.
Moreover, molding can be performed at low cost. Moreover, by simultaneously performing the powder compaction and molding of the raw material powder, the work becomes easier and productivity can be improved. As a result, it has become easier to form green compacts even for products with thin walls and complex shapes.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the principle of a method for pressure molding powder according to an embodiment of the present invention.

FIG. 2 is a perspective view of a product molded by a powder pressure molding method.

FIG. 3 is a perspective view of a product molded by a powder pressure molding method.

FIG. 4 is a perspective view of a product molded by a powder pressure molding method.

FIG. 5 is a schematic diagram for explaining the principle of a powder processing and molding method according to another embodiment of the present invention.

FIG. 6 is a diagram showing the principle of a conventional powder pressure molding method.

FIG. 7 is a diagram showing the principle of a conventional powder pressure molding method.

FIG. 8 is a diagram showing the principle of a conventional powder pressure molding method.

FIG. 9 is a diagram showing the principle of a conventional powder pressure molding method.

[Explanation of symbols]

11 Stainless steel plate (plate material) 12, 22 Powder 15 Lower mold 16 Upper mold 17 Forming gas 18, 23 Powder compact

Claims (1)

[Claims] [Claim 1] A method of producing a powder, characterized in that the raw material powder is held between a pair of plates having plastic properties, and the plates are plastically formed in the sandwiched state, thereby performing compaction and shaping of the raw material powder at the same time. Pressure molding method.