JPH0739520Y2 - Extrusion mold - Google Patents

Description

[Detailed Description of Device] a. Purpose of the Invention [Field of Industrial Application] The present invention relates to an extrusion molding die used for manufacturing a powder compact, and particularly to the structure thereof.

[Conventional technology]

Generally, when a metal or ceramics sintered product is manufactured by a powder metallurgy method, a raw material powder and a binder are mixed, molded by a compression molding press machine, and a molded body is sintered to manufacture the product.

When obtaining a powder compact, the one with a relatively simple shape is molded by the vertical pressing method, but in the case of a hollow structure and a thin shape, it is performed by an extrusion molding method using an extrusion molding die. It was

In the conventional extrusion molding method, 10 to 20% by weight (hereinafter referred to as wt.
%)), Kneaded and kneaded to form pellets or granules, which are then fed to an extruder, softened by heating and discharged while forming into the shape of the die outlet, and after cooling to a prescribed length. It was cut into pieces and then sintered to obtain a product.

[Problems to be solved by the device]

Since the mixture of the powder and the organic binder used in the above-mentioned step of molding the green compact is contained in a high concentration of the powder,
Since the specific gravity of the powder becomes large and the moldability is lower than that of general-purpose extrusion molding plastics, the molding temperature is raised, so when extruded in the horizontal direction, especially in the case of a thin shape with a hollow part inside, There is a drawback that deformation due to its own weight is likely to occur immediately after being extruded from the mold. Conventionally, it has been considered to deal with the method by making the extruder vertical, or using a crosshead to make the extrusion direction vertical, but with these methods, post-extrusion processing is performed with the die and floor. It had to be done in the vertical direction between the plane and it was not a fundamental solution because it limited production speed and workability. A technical object of the present invention is to provide an extrusion molding die capable of extruding a thin-walled molding having a hollow portion or the like without being horizontally deformed.

B. Configuration of the Invention [Means for Solving the Problems] In order to solve the above-mentioned problems, the inventor has found that a molded product immediately after being extruded from an extruder by a raw material composed of a mixture of raw material powder and an organic binder. In the state where it is not sufficiently cooled and solidified, especially thin-walled ones with hollow parts inside are deformed by their own weight immediately after being discharged from the extrusion mold, or deformed due to slight shaking of the conveyor etc. As a result of studying in consideration of the fact that it will cause the mold, the mold extruded from the die part of the mold is sufficiently cooled, until the mold for hollow part molding is cooled to a temperature that can withstand its own weight and the deforming force of the conveyor. It has been found that the deformation of the compact can be suppressed by extending the core outward from the die of the die.

The present invention is an extrusion molding die having a structure in which the tip of the core protrudes from the die part of the mold, and the core remains inside the molded body until the extruded molded body is solidified and deformed. It is a structure that suppresses.

That is, in a die for molding a powder compact having a hollow portion by extrusion molding a raw material obtained by kneading a metal or ceramic powder and a binder, a die part (core) for forming the hollow portion is formed into a die. The present invention provides an extrusion molding die characterized in that a powder compact is cooled and solidified from a die portion of a product discharge port to a position where it can withstand deformation, and is projected outward.

[Action]

Due to the structure in which the core of the extrusion mold of the hollow thin-walled powder compact is protruded from the die part of the mold to a position until the mold is sufficiently cooled and can withstand deformation, external force and self-weight Suppressed deformation.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial cross-sectional view showing a die peripheral portion of an extrusion molding machine according to an embodiment of the present invention. FIG. 1 (a) is a plan view and FIG. 1 (b) is a front view. . FIG. 2 is a front view of a die used in the extruder of the embodiment of the present invention shown in FIG. In addition, Table 1 shows the binders used for preparing the raw material pellets used in the examples of the present invention and the mixing ratio thereof.

Example 1 In FIG. 1, the cross-sectional dimension of the molding part of the mold 2 is 40 m in width.
m, 3 mm long. Further, a core 21 for forming a hollow portion in the molded body 4 is installed inside thereof, and its cross-sectional dimension is 37 mm in width and 1 mm in length.

The average particle size of the pellets used as the raw material for the powder compact is 0.5 μm.
Ni-Zn ferrite calcined powder of was mixed with a thermoplastic binder having the composition shown in Example 1 of Table 1, and the mixture was mixed with a pressure kneader.
The mixture was kneaded at 130 ° C. for 30 minutes and pelletized with an extrusion pelletizer. The raw material pellets were put into an extruder 1 having a screw 11 having a diameter of 30 mm and an L / D of 22 shown in FIG.
The raw material kneaded by the screw 11 flows into the mold 2, the core 21 forms a hollow portion, and the molded body 4 is extruded. The extruded compact 4 is a conveyor 3
Is guided and taken by the belt 31 of.

The barrel temperature of the extruder 1 is 130 with a band heater.
Set a constant temperature between ~ 140 ℃, belt 3 of conveyor 3
The rotation speed of 1 was synchronized with the extrusion speed of the molded body 4.

Immediately after being molded by this extrusion molding machine 1 and extruded from the discharge port of the mold, the molded body 4 is in a state where it is not sufficiently cooled and solidified, and if there is nothing to maintain its shape in the hollow portion, The upper part is in a state of being deformed by its own weight. In order to prevent this, the mold used in the present embodiment has a core 21 for forming a hollow portion in the molded body 1 as a first core.
As shown in the figure, it is projected about 60 mm from the die of the ejection port of the die. The molded body 4 immediately after being extruded from the die of the ejection port of the die is prevented from being deformed by its own weight or the shake of the conveyor. A cooling gas is blown to the molded body at the intermediate position of the core 21 protruding in the meantime as shown by the arrow in FIG. 1 (b) to accelerate the cooling and solidification of the molded body and enhance the shape retention of the molded body 4. . Formed body 4 being drawn out by forced air cooling in the middle part
The deformable range is shortened to a stable state quickly, and even if the protruding portion of the core 21 comes out of the hollow portion of the molded body 4, the molded body 4 is picked up by the conveyor with a good shape without being deformed by its own weight. be able to.

The molded body 4 produced by the above method was cut, and the cross-sectional dimensions were measured. As a result, the width was 39.9 mm, the length was 2.9 mm at both ends, and the central portion was 2.9 mm, and a good molded body without deformation was obtained.

Example 2 The raw material pellets of the powder compact used in this example were produced by high-frequency melting of an alloy having a composition of Fe50 wt% and Co50 wt% as an raw material powder in an argon gas atmosphere, and an average particle size of 10 μm by a water atomizing method. The obtained powder was used to prepare pellets for extrusion molding under the same conditions as in Example 1 with the binder composition shown in Example 2 of Table 1, and extrusion molding was performed.
The mold 2 has a cross-sectional dimension of the molding part of 60 mm in width, 5 mm in length,
A core 21 for forming a hollow portion inside the molded body 4 had a cross-sectional dimension of 56 mm in width, 1.5 mm in length, and a length of a protrusion of 100 mm from the die of the die discharge port. The molded body 4 produced by the above method was cut and the cross-sectional dimensions were measured. As a result, the width was 59.8 mm, the length was 4.9 mm at both ends and the central portion, and a good molded body without deformation was obtained.

Example 3 The raw material pellet of the green compact used in this example was Sm25.2.
wt%, Co49.2wt%, Cu9.2wt%, Fe15.0wt%, Zr1.4wt%
Ingot of the following composition is melted and heated at 1180 ℃ in Ar atmosphere for 5
After solution heat treatment for 2 hours, aging treatment was performed at 800 ° C. for 2 hours.
Further, a powder was crushed with a jaw crusher, a disc mill, and a ball mill to an average particle size of about 12 μm. Using this as a raw material powder, extrusion molding pellets were produced under the same conditions as in Example 1 with the binder composition shown in Example 3 of Table 1. The raw material pellets were used for extrusion molding. The mold 2 has a cross-sectional dimension of the molding
The core 21 having a cross section of 50 mm, 3.5 mm in length, and having a hollow portion formed inside the molded body 4 had a width of 47 mm, a length of 1 mm, and a protrusion of 100 mm from the die cap.

The molded body 4 produced by the above method was cut and the cross-sectional dimensions were measured. As a result, the width was 49.9 mm, the length was 3.4 mm at both ends and the central portion, and a good molded body without deformation was obtained.

Comparative Example Pellets for extrusion molding were made from the powder used in Example 1 under the same conditions as in Example 1, and the core 21 was extruded using a length not protruding from the die of the die discharge part. I did. When the cross-sectional dimensions of the molded body 4 obtained at that time were measured, the width was 39.9 mm and the length was 2.9 mm at both ends, whereas the center was 2.3 mm.

As described above, as shown in Examples and Comparative Examples, it can be understood that when a green compact is molded using the extrusion molding die of the present invention, it can be manufactured without impairing the shape of the molded body.

In the present invention, the length of the ejection port of the core of the mold projected from the die is an extrusion molding condition (eg temperature, extrusion speed, etc.).
And the type of raw material of the green compact to be molded (for example, raw material powder, kind of binder, mixing ratio, etc.), and change by using the forced cooling method as shown in FIG. 1 (b) after extrusion of the compact Therefore, it is determined according to each condition.

C. Effect of the Invention [Effect of the Invention] As described in detail above, according to the extrusion molding method using the extrusion molding die according to the present invention, in the production of a thin powder compact having a hollow portion inside, Since the molded body is cooled and solidified without impairing its shape, a good molded body without abnormal deformation can be manufactured. Therefore, according to the present invention, extrusion molding of a compact thin-walled compact having a complicated thin shape can be efficiently produced with good quality, which is very useful in industry.

[Brief description of drawings]

1A and 1B are a plan view and a front view showing a part of a peripheral portion of a die portion of an extrusion molding machine according to an embodiment of the present invention in a sectional view, and FIG.
Is a plan view, FIG. 1 (b) is a front view, and arrows indicate the blowing direction of the cooling gas. FIG. 2 is a front view of a die used in the extruder of the embodiment of the present invention shown in FIG. 1 ... Extruder, 11 ... Screw, 2 ... Mold, 21
...... Core, 3 ... Conveyor, 31 ... Belt, 4 ... Molded body.

Claims (1)

[Scope of utility model registration request] 1. A mold for molding a powder compact having a hollow part by extrusion molding a raw material obtained by kneading a metal or ceramic powder and a binder, and forming a mold part for forming the hollow part. An extrusion molding die, characterized in that a powder compact is cooled and solidified from a die portion of a discharge port to a position where it can withstand deformation and is projected outward.