JPH035919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a green compact, and in particular to a method for forming a green compact, particularly for a member having a thin walled portion at the inner bottom such as an automobile suspension ball, or the like, the thickness in the compression direction at the center and outer peripheral portion thereof is The present invention relates to a method for molding thick powders having different shapes using a powder molding press.

Conventionally, there is a method shown in FIG. 1 as a method for forming a green compact in which the thickness in the compression direction is different between the center part and the outer peripheral part. It is divided into an inner punch 2 corresponding to the thin center part and an outer punch 3 corresponding to the thick outer peripheral part, and both the inner and outer punches 2 and 3 are slidably fitted to each other, and the die A powder forming press is used in which a lower punch 6 is vertically and slidably fitted into the die hole 5 of No. 4. During the press forming operation, first, as shown in Fig. 5, lower the lower punch 6,
After supplying the powder 7 into the die hole 5 with its top open, the upper punch 1 is lowered into the die hole 5, and as shown in FIG. The powder is compressed into a large size, and the green compact 8 is taken out by raising the upper punch 1 and the lower punch 6 as shown in FIG. 1c.

However, in the method shown in FIG.
There is a difference in the compression ratio between the thin center part and the thick outer peripheral part, and the thin part has a high density, causing compression cracks in the green compact.

In order to eliminate this problem, a method as shown in FIG. 2 has been conventionally used. In the method shown in FIG. 2, the lower punch 6 is also divided into an inner punch 9 and an outer punch 10 corresponding to the inner punch 2 and outer punch 3 of the divided upper punch 1, and as shown in FIG.
As shown in FIG. 2, before filling the powder 7 into the die 5, the lower inner punch 9 corresponding to the thin wall portion is raised in advance so that the compression ratio is even.
After filling the die hole 5 with powder, the lower inner punch 9 is lowered to a predetermined position as shown in FIG.
Compress and form.

However, in the conventional method shown in FIG. 2, the drive mechanism for the lower punch 6 is complicated, and there are problems such as the powder molding press that makes it possible is limited.

The present invention solves the above-mentioned conventional problems, and relatively easily produces a powder compact with a uniform density, which has different thicknesses in the compression direction, has a thicker part on the outside, a thinner part on the inside, and is particularly concave on the upper side. The purpose is to provide a method that can be molded into. Another object of the present invention is to provide a method for molding a green compact that prevents scattering of powder during molding, improves the environment, and improves the yield of raw materials. Another object of the invention is to simplify the machine by allowing powder to be fed into a closed die cavity without the use of conventional powder feeders.

Therefore, according to the present invention, an inner upper punch for thin-walled parts and an outer upper punch for thick-walled parts, which are divided into vertically slidable parts, are used, and the lower punch does not operate dividedly during powder compression. After the inner upper punch is lowered into the closed die cavity, the outer upper punch is raised to a position where the powder compression ratio is equal to that of the inner upper punch portion, and the powder is supplied. open your mouth,
The method is characterized in that a die cavity is filled with powder, the powder is compressed, and green compacts having different thicknesses in the compression direction are formed with a uniform compaction density.

According to a preferred embodiment of the present invention, the powder supply outer cylinder having the powder supply port on the inner circumferential wall is fitted and attached to the outer periphery of the outer upper punch in the vertical movement direction, and the outer upper punch closes the powder supply port. Lower the powder supply cylinder onto the top of the die to close the upper end opening of the die hole to form a die cavity, lower the inner upper punch into the die cavity, and then raise the outer upper punch to make the compression ratio even. The powder supply port is opened to fill the powder into the die cavity, and the powder in the die cavity is compressed with an upper punch to produce a green compact.

The invention will now be explained with reference to the drawings.

FIG. 3 shows the entire molding apparatus according to the present invention,
As shown in FIG. 4, the upper punch 1 is divided into an inner upper punch 2 corresponding to the thin wall portion and an outer upper punch 3 corresponding to the thick wall portion, and these inner and outer punches 2 and 3 are slidable relative to each other. is mated to.

In addition, a powder supply outer cylinder 1 is attached to the outer periphery of the outer upper punch 3.
1 are fitted and attached so as to be vertically movable, and the powder supply outer cylinder 11 is provided with a powder supply passage 13 having a powder supply port 12 opening at the lower part of the inner circumferential wall thereof.
These powder supply passages 13 are connected to a powder supply hopper 15 for supplying powder via a supply hose 14, and the powder supply hopper 15 is supported on a forming press frame 16 so as to be movable up and down, and has an inner upper punch 2 and an outer upper punch 2. The upper punch 3 and the powder supply cylinder 11 are connected to a known suitable actuating device 17 so as to be able to move up and down separately and together, and to move the outer upper punch 3 relative to the powder supply cylinder 11. The powder supply port 12 is opened when the powder supply port 12 is raised.

A lower punch 6 is provided in the die hole 5 of the die 4 so as to be movable up and down.
The powder supplied and filled into the die cavity 5 formed by lowering the die is compressed by the upper and lower punches 1 and 6 to obtain a desired green compact.

When producing a green compact using the above-described apparatus, the lower punch 6 in the die hole 5 is lowered as shown in FIG. 4a, and then the upper punch 1 and the lower punch 6 are lowered as shown in FIG. 4b. The powder supply outer cylinder 11 is lowered together, the upper outer punch 3 and the powder supply outer cylinder 11 are stopped at the upper surface of the die 4, and the inner upper punch 2 is placed inside the sealed die cavity 18 thus formed.
further lower only to a predetermined position. Then,
As shown in FIG. 4c, the upper outer punch 3 is raised to open the powder supply port 12 on the inner circumferential wall of the powder supply outer cylinder 11 to the die cavity 18, and the lower punch 6 is opened to the die cavity 18 if necessary. It further descends into the hole 5 to a predetermined position, thereby charging and filling the powder 7 from the powder supply hopper 15 into the die cavity 18 via the powder supply passage 13.

After filling the powder, as shown in FIG. 4d, the outer upper punch 3 is lowered and the lower punch 6 is raised, and the upper and lower punches 1 and 6 compress the powder 7 in the die cavity 18 to form a green compact. 8, and finally, as shown in FIG.
is raised to push up the green compact 8 from the die 4 and take it out.

As described above, before filling the powder into the die cavity 18, the inner upper punch 2 is lowered and inserted into the die cavity 18, and the outer upper punch is compressed so that the compression ratio is the same as that of the inner upper punch. By setting it to , it is possible to obtain a green compact with uniform density throughout.

Powder supply passage 1 to be provided in powder supply outer cylinder 11
3 shall have a hole diameter necessary for uniformly supplying the powder 7 into the die cavity 18, and there shall be at least four, preferably six or more supply passages 13.
It is preferable to uniformly supply the powder from the powder supply port 12 formed by a groove formed on the entire inner wall of the powder supply cylinder 11 through the powder supply cylinder 11.

FIG. 5 shows an embodiment of the present invention in which a green compact having a center hole 19 at the bottom and having different thicknesses in the compression direction as shown in FIG. 6 is manufactured according to the present invention. In this example, unlike the example explained with reference to FIG. 4, the lower punch 6 is not used, and instead, an extrusion punch 20 for extruding the compact from inside the die cavity 18 to the outside of the die 4 is provided inside the die hole 5. It is installed so that it can move up and down. Reference numeral 21 indicates a core rod provided at the center of the die hole 5 for providing the center hole 19.

In this example, the die cavity 18 is formed in the same manner as in the previous example, and after inserting the inner upper punch 2 into the die cavity 18, the powder supply port 12 is opened as shown in FIG. After filling the inside with powder 7 and compressing and molding the powder by lowering the upper punch 1, the powder compact 8 can be pushed out of the die by the extrusion punch 20 and taken out.

According to the present invention, after lowering and inserting the inner upper punch corresponding to the thin section into the die cavity to a predetermined insertion position, the die cavity is filled with powder, and the powder is filled into the die cavity by the inner and outer punches of the upper punch. Since a green compact with a uniform green density is produced by compressing it with
Since there is no need for a synchronous operating mechanism for operating the inner punch in synchronization with the upper punch, the structure of the punch operating mechanism can be simplified. Further, as shown in the example, a powder supply cylinder is provided on the outer periphery of the upper outer punch, and a closed die cavity is formed by closing the upper end of the die hole with the powder supply cylinder with the upper surface of the die facing down. Powder is filled into the closed die cavity by moving the outer upper punch up and down relative to the powder supply cylinder, which prevents powder from scattering during molding, improves the working environment, and improves raw material yield. can be made better,
In addition, the powder supply operation is facilitated, and the molding operation can be easily automated.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams showing the conventional manufacturing process of a green compact, FIG. 3 is a schematic diagram of a molding device used in the method according to the present invention, and FIG. 4 is a green compact according to the method of the present invention. FIG. 5 is an explanatory diagram showing another embodiment of the present invention, and FIG. 6 is a perspective view of a green compact manufactured by the method shown in FIG. 1...Upper punch, 2...Inner upper punch, 3...
Upper outer punch, 4... die, 5... die hole,
6...Lower punch, 7...Powder, 8...Powder compact, 9...Inner punch, 10...Outer punch, 1
1...Powder supply outer cylinder, 12...Powder supply port, 13
... Powder supply passage, 14 ... Supply hose, 15 ...
...Powder supply hopper, 18...Die cavity,
19... Center hole, 20... Extrusion punch, 21...
...Coalotsud.

Claims (1)

[Claims] 1 The powder in the die cavity formed by the die and the upper and lower punches is moved and pressurized by the upper and lower punches.
When molding a compact that has different thicknesses in the compression direction, with a thicker part on the outside and a thinner part on the inside, the upper punch is divided into an inner upper punch corresponding to the thinner part and an outer upper punch corresponding to the thicker part. The lower punch is divided into two parts and each operates independently, and the lower punch operates as a single unit.
In addition, a powder supply cylinder having a powder supply port on the inner circumference side is fit and attached to the outer periphery of the upper outer punch so that it can move vertically, and the powder supply cylinder is inserted into the die while the outer upper punch closes the powder supply port. After lowering the inner upper punch to the upper surface and closing the upper opening of the die hole to form a closed die cavity, and lowering the inner upper punch into the closed die cavity, the outer upper punch is pressed so that its powder compression ratio is equal to that of the inner upper punch part. The powder supply port is opened and the powder is filled into the die cavity, and the upper outer punch and the upper inner punch are lowered, or the lower punch is simultaneously raised to release the powder inside the die cavity. A method for producing a compacted powder, characterized by compacting the powder.