JPS5850198A - Powder molding method - Google Patents

Abstract

PURPOSE:To obtain a uniform powder molding using a hydrostatic pressure press by connecting a powder filling device having a powder reservoir on the rotation shaft to a mold and rotating at high speed and thereby filling the powder densely to every nook and corner of cavities. CONSTITUTION:A powder filling device is connected to a mold 1 having cavities 6, 7 of required shape and roatated at high speed around a rotation symmetric axis 3. Since a powder reservoir 2 is provided on the rotation shaft of the powder filling device, generation of centrifugal force is restrained, and the powder flows easuly in vertical direction and filled densely to every nook and corner of cavaties 6, 7. This preformed product is pressed at cold by a hydrostatic pressure press in a high pressure medium and a uniform powder molding is obtained.

Description

Detailed Description of the Invention The present invention is a method for manufacturing complex-shaped parts that are difficult to uniaxial press molding by powder metallurgy. Regarding how to.

Powder compaction methods include a uniaxial press method using a metal mold, a so-called CIP method using hydrostatic pressure, and the like, each of which has been widely put into practical use.

In recent years, parts with shapes that are difficult to mold using single-axis presses can also be molded using powder,
Due to the excellent material properties that can only be obtained through metallurgy, there is an increasing demand for manufacturing using powder metallurgy. It is easily considered that the most effective method for such a shape is to use the CIP method. However, the CIP method for complex-shaped parts has had very difficult problems.

In other words, in the CIP method, the powder is compressed homogeneously because hydrostatic pressure is applied, and the density distribution should be uniform.However, uniform filling of powder is easy for simple shapes, but difficult for complex shapes. .

Powder packed unevenly causes density distribution even when using the CIP method. Therefore, it is difficult to fill parts with complex shapes, especially parts such as thin fins, and it is almost difficult to mold them even by the Cf)P method.

In the present invention, 1. As a method for filling this powder, we have found that it is possible to precisely fill even the smallest details by using a method that utilizes centrifugal force or centrifugal force, rather than using conventionally known vibration methods or ultrasonic photoluminescence methods.

In the filling by centrifugal force of the present invention, the centrifugal force F due to rotation is P = m - r ω2 m = mass of object subjected to centrifugal force "r - radius of rotation ω = powder particles are moved by angular velocity and packed. Therefore, it is naturally limited to symmetrical products that are rotationally symmetrical or similar in shape.

However, rotationally symmetrical objects can be found in many parts that have intricate carvings and are required to be manufactured by powder metallurgy, such as in turbine rotors.

Since such parts are used as rotating bodies, it is important to have a high density at the fin tips located farthest from the rotation axis. However, according to the method of the present invention, the centrifugal force F is
Since the size increases in proportion to , it is easier to fill the tip with a higher density, which is completely opposite to the tendency of the tip to become less dense in the conventional method, which is very convenient for manufacturing parts. This will be explained in detail with reference to FIGS. 1 and 2.

The cavities 5 and 6 are filled with the powder 8 in the required amount of i.
The problem is how to feed the powder, but if it is not on the rotating shaft, the centrifugal force will prevent the powder from moving up and down, making it impossible to feed it. Therefore, we adopted a method of filling while supplying powder from the powder reservoir 2 provided on the same rotating shaft (A). This made it possible to easily flow vertically.

The preliminary photoreceptor obtained in this way was molded.

5 in a pressure medium with a pressure of 3 to M-, CIP
It was found that a homogeneous molded body could be obtained by doing so. .

To add centrifugal force, according to the above formula F = mrJ,
It is necessary to increase (ω), that is, adjust the rotational speed, but this differs depending on the size and shape of each object.

Example: A synthetic resin mold for a turbine rotor having 20 fins with a maximum diameter of 120 m, an inner diameter of 20 m, and a wall thickness of 1.5 W, and a powder reservoir connected to the mold and provided on the rotating shaft. Fix the device to the shaft and rotate at 7
While rotating at 50 Orpm, powder was supplied from the powder sump and filled.

After filling, the mold was sealed and subjected to CIP at 4.51/u.

The obtained molded body was divided and the density was measured, and the density was 842% at the fin tip and 85.24 at the boss.

Brief Explanation of Ball Drawings 5 Fig. 1 is a conceptual diagram of a centrifugal light beam device used in the method of the present invention, and Fig. 2 is a sectional view of a hollow mold according to another embodiment of the present invention.

l, 5: mold, 2: powder reservoir, 3: rotating shaft,
4: Rotation direction, 6: Boss cavity, 7: Fin cavity, 8: Powder, A: Rotation shaft 71 diagram

Claims (1)

[Claims] (1) In a method of molding powder into a rotationally symmetrical shape or a shape similar to it, a powder light beam consisting of a mold having a cavity similar to the target shape and a powder reservoir connected to the mold and provided on a rotation axis The filling device is rotated at high speed around an axis of rotational symmetry, and after the centrifugal force causes the powder to be densely filled in every detail in the circumferential direction, the entire mold is cold statically pressed in a high-pressure pressure medium. A powder compacting method characterized by: