JPH0657841B2 - Powder molding method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improvement in a powder molding method, and more particularly to a molding method for a molded body having a recess in a direction perpendicular to the powder pressing direction.

The powder molding method of the present invention can be used for manufacturing carbon products such as electric brushes, mechanical parts using sintered metal, and molding ceramic products.

[Prior Art] In powder molding, a molded body having a recess or a protrusion parallel to the pressing direction can be easily molded by providing a protrusion or a recess corresponding to the male mold. However, a molded product having a concave portion which is not perpendicular to the pressing direction cannot be taken out from the mold by providing a protrusion corresponding to the female mold.

Therefore, in order to form a molded article having such a recessed shape, it was usual to form the recessed portion later by cutting.

On the other hand, Japanese Patent Laid-Open No. 59-35603 discloses that a movable mold is moved forward and backward in a mold space to press a molded product having a hollow shape. 3 and 4 show a pressing method in this publication, a male die (01) and a female die (02) are arranged, a core rod (03) is provided in a guide (04), and a core rod (03) is provided. Move the ball (05) with the exercise. At the time of molding, the balls (05) are projected as shown in FIG. 3 to mold the powder (06), and when the powder (06) is taken out from the mold, the core rod (03) is pulled down and the balls (05) are retracted to form the molded body (07). Take out.

However, this method has a problem of spring back of the molded body (07). The molded body (07) immediately after molding is obtained by compressing and solidifying powder and has a property of swelling to the surroundings. This is the spring back of the molded body. When the ball (05) is retracted as shown in FIG. 4, a gap (08) is created between the ball (05) and the guide (04). In the figure, the gap (08) is concentrated on the upper side of the ball (05) to retract the ball (05) diagonally downward, but the surface of the gap (08) is spherical and not flat. It occurs in. That is, when the movable mold whose tip is not flat is retracted into the mold whose surface is flat and the tip of the movable mold is aligned with the surface of the surrounding mold, since the surface of the movable mold is not flat, there is a depression on the mold side. Occurs. Here the molded body (0
The lower edge (09) of (7) is springbacked to create a gap (0
It expands into 8) and is ground by the guide (04). Even if there is no springback, if there is a gap (08) there will be an edge.
(09) and other parts are easily ground, making precise molding difficult.

[Object of the Invention] An object of the powder molding method of the present invention is to make it possible to manufacture a molded body having a recess in a direction perpendicular to the pressing direction. It is an object of the present invention to provide a powder molding method capable of precise molding without grinding of powder immediately after molding due to springback.

[Structure and Operation of the Invention] The present invention relates to a pressurizing step of pressurizing powder filled in a female mold by upper and lower male molds to form a molded body, and moving at least one of the male molds to form the molded body. In a powder molding method having a step of taking out from the female mold, a rotating movable mold is provided in the female mold, and the movable mold is provided with a protrusion and a notch to flatten the surface of the notch. In the pressing process, the protruding part of the movable mold is protruded from the female mold into the mold space, and in the removing process, the movable mold is rotated to make the flat surface of the cutout part the same as the surrounding female mold surface. It is characterized in that it is arranged on a plane and the molded product is taken out.

Further, the present invention is characterized in that the molded body is an electric brush, the lead wire is inserted into the upper male mold to supply the lead wire into the powder, and the lead wire is fixed in the molded body. To do.

[Example] An example will be described below by taking an example of forming an electric brush using rotation and sliding of a movable die, but the present invention is not limited to this.

The molding of the electric brush (2) shown in FIG. 2 will be described with reference to FIGS. 1 (a) and 1 (b). This electrobrush (2) is a rectangular parallelepiped shaped body (4) made of graphite or a mixture of graphite and copper, to which a lead wire (6) made of a twisted wire made of copper or the like is fixed. An arcuate recess (8) is provided on one surface of (4).

Returning to FIG. 1 (a), (10) is an upper male type, (12) is a lower male type,
The upper male mold (10) is provided with a through hole for passing the lead wire (6). The female die (14) is provided with a movable die (16) so that it can be rotated by using a connecting rod (18) connected to a cam mechanism (not shown). (20) is the protrusion of the movable type (16),
(22) is a corresponding notch.

First, the upper male mold (10) stands still above the female mold (14) leaving a gap enough to fill the raw material powder, and the lead wire (6) is pulled out by a predetermined length. When the raw material powder is filled, the upper male mold (10) and the lower male mold (12) move toward the center of the female mold (14) and compression molding is performed. At this time, the projecting portion (20) of the movable mold (16) projects into the female mold (14), and molding is performed along this. Although the molding is performed by the double pressing method here, other molding methods such as the single pressing method may be used.

When the pressurization is finished, the process moves to FIG. 1 (b), the movable die (16) rotates, the protruding portion (20) is housed inside the female die (14), and the notch surface (22) of the movable die (16) ) Forms the same plane as the molding surface of the female mold (14). Further, the upper male mold (10) moves upward and the lead wire (6) is pulled out. Further, the upper male mold (10) and the lower male mold (12) move upward, and the molded body (4) is taken out. Next, the lead wire (6) is cut at an appropriate position, and the molded product (4) is transferred by a pusher (not shown) or the like. Finally, the lower male mold (12) is returned to move to the next molding.

[Effect of the Invention] With the powder molding method of the present invention, it is possible to easily mold a molded body having a recess in a direction perpendicular to the pressing direction.

In the present invention, the movable die rotates after being pressed so that the cutout portion appears on the surface of the female die, and the surface of the cutout portion and the surface of the surrounding female die are flush with each other. Therefore, there is no problem that the spring-back molded body is scraped in the mold, and even if precise molding is performed, it is not ground at the boundary between the movable mold and the female mold. The present invention is suitable for precision molding of small parts, and particularly in the case of an electric brush, it is possible to form a recess such as a semicircle or an ellipse in a small molded body, and the lower edge of the recess is a springback or the like. It will not be scraped.

[Brief description of drawings]

1 (a) and 1 (b) are a cross-sectional view and a partial cross-sectional view showing the powder molding method of the embodiment, and FIG. 2 is a perspective view of an electric brush molded by the method of the embodiment. 3 and 4 are cross-sectional views showing a molding method of a conventional example. In the figure, (10) …… upper male type, (12) …… lower male type, (14) …… female type, (16) …… movable type, (20) …… protruding part, (4) …… Molded body.

Continuation of the front page (56) Reference JP-A-59-35603 (JP, A) JP-A-54-91877 (JP, A) JP-A-51-149106 (JP, A) Actual development 59-43106 (JP , U)

Claims (2)

[Claims] 1. A pressurizing step of pressurizing powder filled in a female mold by upper and lower male molds to form a molded body, and removing at least one of the male molds to take out the molded body from the female mold. A powder molding method having a step of providing a rotating movable die in the female die, and providing the movable die with a protrusion and a notch to make the surface of the notch flat. Then, the protruding part of the movable mold is protruded from the female mold into the mold space, and in the take-out step, the movable mold is rotated so that the flat surface of the notch surface is flush with the surrounding female mold surface. A powder molding method, characterized in that the molded body is taken out. 2. The molded body is an electric brush, and the lead wire is inserted into the upper male mold to supply the lead wire into the powder, and the molded body is molded so as to fix the lead wire. The powder molding method according to claim 1.