JPH02310004A - Extrusion molding method of intimate mixture of powder - Google Patents

Abstract

PURPOSE:To obtain a two-dimensional or three dimensional curved surface without having post processing, by a method wherein a velocity ingredient of an extruder speed is added in the direction vertical to an extruding direction. CONSTITUTION:An extrusion molding device of an intimate mixture of powder is constituted of an extrusion cylinder 1, screw 2 and die 3 comprised of dies 12, 12 ', die holder 15 and a breaker plate 16. The cylinder 1 and die 3 can be heated to a desired temperature with heaters 21, 22 positioning at the outside of the cylinder 1 and die holder 15. Lengths of respective linear parts 42, 42 ' of the dies 12, 12 ' are different from each other. The intimate mixture obtained by mixing and kneading ceramics, at least a kind of metallic powder and a binder having plasticity is melted by filling the same into a space between the cylinder 1 and screw 2 after heating of the cylinder 1, screw 2 and die 3. Since a velocity ingredient vertical to an extruding direction is generated by generating difference in flow resistance at the time when the intimate mix ture passes through an air gap between the linear parts 42, 42 ' since the lengths of the linear parts 42, 42 ' of the dies 12, 12 ' are different from each other, an extrusion molded body 30 becomes a bent matter having a two-dimensional curved surface.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an extrusion molding method for a powder mixture, particularly a method for extruding a powder mixture that can provide an extruded body having a two-dimensional or three-dimensional curved surface. Regarding molding method = 1-.

[Prior Art] Conventionally, extrusion molding has been widely used as a method for continuously molding thermoplastic plastic materials, various rubbers, etc. into molded bodies having a constant cross section, such as tubular or rod shapes.

Furthermore, using the above-mentioned extrusion molding method to produce thermoplastic plastics, rubber, etc., for example, by mixing ferromagnetic powder such as barium ferrite powder and extrusion molding, so-called plastic magnets and rubber magnets can be produced. Manufacturing methods are widely used industrially.

On the other hand, in recent years, a method of molding ceramic powder or metal powder by extrusion molding has attracted attention.

That is, about 10 to 20 parts by weight of an organic binder is added to ceramic powder or metal powder, mixed and kneaded, and then extruded to obtain a green molded product.Then, the desired sintered product is obtained through a depine mite process and a sintering process. More specifically, a mixture of ceramic powder or metal powder and an organic binder is filled in the cylinder of an extruder in a molten state, and then extruded from a die by a screw located in the cylinder. The extruded molded product is then cut into a desired length and used as is, such as the so-called plastic magnets and rubber magnets mentioned above.

The extruded body undergoes a binder removal and sintering process to become a product that can be used as a sintered body.

[Problems to be Solved by the Invention] In the conventional method for extruding a powder mixture described above, the mixture is extruded uniformly and continuously in the extrusion direction, so the molded bodies obtained have the same cross-sectional shape. The shape is parallel to the extrusion direction. Therefore, in order to obtain an extruded product with a curved surface perpendicular to the extrusion direction, the extruded product must be subjected to post-processing I, so-called bending, which not only increases the number of processing steps, but also requires post-processing because the extruded product itself is fragile. ] The two disadvantages were that the degree of freedom was small, and that the bending process was likely to result in uneven density in the bending process.

Therefore, the technical problem of the present invention is to eliminate the drawbacks of the conventional extrusion molding method for powder mixtures in two-dimensional or three-dimensional form without post-addition balls during extrusion molding of powder mixtures. The object of the present invention is to provide a method for obtaining an extrusion molded product of a powder mixture having an original curved surface.

"Means for Solving the Problems" The extrusion molding method for a powder mixture of the present invention is a method for extruding a mixture obtained by mixing and kneading at least one of ceramic and metal powders and a binder having plasticity. A method for obtaining a molded article using the above method is characterized in that when extruding the mixture, the flow velocity in the extrusion direction has a velocity gradient in a direction perpendicular to the extrusion direction to produce an extruded curved article.

That is, 1. the present inventors added a speed gradient of the extrusion speed in a direction perpendicular to the extrusion direction during the process of extrusion forming the mixture into an extruded body, thereby increasing the extrusion direction and the direction in which the extruded body is extruded. The present invention was completed by focusing on the fact that the extrusion molded product has a two-dimensional or three-dimensional curved surface as a result of the extrusion molded product having a two-dimensional or three-dimensional curved surface.

[Example] Next, an example of the present invention will be described in detail with reference to the drawings.

Example 1 FIG. 1(a) is a partial top sectional view showing a first example of an apparatus for carrying out the present invention, and FIG. 1(b) is a side sectional view of FIG. 1(a). .

In FIGS. 1(a) and 1(b), the extrusion molding apparatus for one powder mixture includes an extrusion cylinder 1 and a screw 2.

Dies 11.11', 12.12' and die holder 1
5 and a breaker plate 16. Further, the cylinder 1 and the die 3 can be heated to a desired temperature by heaters 21 and 22 located outside the cylinder 1 and the die holder 5.

In FIG. 1(a), the die 12 and the die 12' differ only in the length of the straight portions 42 and 42', and in FIG. 1(b), the die 1] and the die ]]' are respectively They all have the same shape, including the lengths of the straight portions 41 and 41'.

The following extrusion molding was performed using such an apparatus.

Fe50wv%-Co50wt as raw material for extrusion molding
% alloy powder 1 with an average particle size of 101z+n
5.5 parts by weight of ethylene vinyl acetate copolymer resin
parts by weight, 2.7 parts by weight of high-density polyethylene, and 2 parts by weight of 1-1.8 parts of dioctyl phthalate were mixed and kneaded to obtain a mixture.

Next, the heater 21 is heated to 130°C, and the heater 22 is heated to 120°C.
Close cylinder 1. After heating the screw 2 and die 3, the above-mentioned mixture is filled between the cylinder 1 and the screw 2 and melted, and by further rotation of the screw 2, the molten mixture passes through the breaker plate 1-16 and further into the die 1.
The molded product 30 was extruded through the gap formed by 1.11' and 12°12', and a curved product 30 was obtained.

Here, in the extrusion molding method of the powder mixture described above, since the lengths of the straight parts 42 and 42' of the dies 12 and 12' are different, when the molten mixture passes through the gap between the straight parts 42 and 42', Since a difference in flow resistance = 6 - occurs and a velocity gradient occurs in a direction perpendicular to the extrusion direction, the extruded body 30 becomes a curved object with a two-dimensional curved surface H.

Furthermore, the extrusion molded body 30 described above was heated with argon gas for 2 hours.
y? from room temperature to 10°C per hour in an atmosphere flowing at g/min.
Heat up to 600℃ at a heating rate.

After holding at 600° C. for 2 hours, the binder was removed by cooling to room temperature, and then the material was placed in a vacuum furnace at a heating rate of 200° C./hour from room temperature.

After heating to 1200°C and holding for 10 hours.

By rapid cooling, a Fe--Co alloy sintered body having a shape similar to the extruded body 30 was obtained.

For comparison, 2 dies 12.12' straight section 42°4
The mixture was extruded in the same manner as in the first embodiment, in which the lengths of 2' and 2' were equal, and all other conditions were made in duplicate, to obtain an extruded product having no curved surface and a surface parallel to the extrusion direction. In the softened state immediately after extrusion, the extruded body 30 of the first embodiment described above was deformed into an appropriate shape, and then the binder was removed in the same manner as in the first embodiment. Cracks were generated in the curved surface portion, and a good debinding body could not be obtained, thus confirming the usefulness of the first example.

Example 2 FIG. 2(a) is a partial top sectional view showing a second example of an apparatus for carrying out the extrusion molding method of the present invention, and FIG. 2(b) is a partial side sectional view.

In FIGS. 2(a) and 2(b), the extrusion molding apparatus for a powder mixture includes a cylinder 1, a screw 2, and a die 11.
12, a die 3 consisting of a die holder 15, and a breaker plate 16. Furthermore, the cylinder 1 and the die 3 are heated by the heater 21 located outside the cylinder 1 and the heater 22, 22' located outside the die holder]
It has a structure that allows it to be heated to the desired temperature.

Extrusion molding using such an apparatus was carried out as follows.

As raw materials for extrusion molding, 5.1 parts by weight of ethylene vinyl acetate polymer resin, 2.3 parts by weight of polybutyl methacrylate, 2.6 parts by weight of high density polyethylene, per 100 parts by weight of alumina powder with an average particle size of 0.5 μm. 2.0 parts by weight of dibutyl phthalate was mixed and kneaded to obtain a mixture.

Next, heat the heater 21 to 140°C, and heat the heater 22' to 130°C.
After heating the screw 2 and die 3, the above-mentioned mixture is filled between the cylinder 1 and the screw 2 and melted, and by further rotation of the screw 2, the molten mixture is Breaker plate 1
6 and a die], and the extruded product 30' was placed through the gap formed by 1.12.

Here, in the extrusion molding method for a powder mixture described above, since the heating temperatures of the heaters 22 and 22' of the dies 11.12 are different, there is a difference in viscosity when the molten mixture passes through the gap between the dies 11.12. This causes a difference in flow resistance and a velocity gradient perpendicular to the extrusion direction, resulting in the extruded product 30' being a curved object with a two-dimensional curved surface.

Furthermore, the above-mentioned extrusion molded body 30' was heated with 2 g of nitrogen gas.
The binder was removed by heating from room temperature to 600°C at a temperature increase rate of 10°C/hour in an atmosphere with a flow of 10°C/min, holding the temperature at -8-160°C for 2 hours, and then cooling to room temperature. Then, using a gas furnace in an air atmosphere, the temperature was increased from room temperature to 1.
After heating to 600℃ and holding for 2 hours, 20℃ per hour.
After slowly cooling from 0°C to 800°C.

The extruded body 30' is cooled by cooling in air.
An alumina sintered body with a similar shape? 1 no, ta.

For comparison, the heaters 22 and 22' of the dies 11 and 12 were both heated to 30°C, and the mixture was extruded in the same manner as in the second embodiment described above. Obtain an extruded body consisting of a surface,
After deforming it into a shape equivalent to the extrusion molded body 30' in the second embodiment described above in the softened state immediately after extrusion 7,
The binder was removed using the same method as in the second example.

The usefulness of the second example was confirmed because cracks were generated in the curved surface part and a good debinding body could not be obtained.

Embodiment 3 FIG. 3(a) is a partial top sectional view showing yet another example of an apparatus for carrying out the extrusion molding method of the present invention, and FIG. 3(b) is a side sectional view.

As shown in FIGS. 3(a) and 3(b), the extrusion molding device for a powder mixture consists of a cylinder 1, a screw 2, and a die 1.
2. It includes a die 3 consisting of 12', 12', 12"', a die holder 15, and a breaker plate 16. Furthermore, a heater 21 located outside the cylinder 1 and a heater 22 located outside the die holder 15. It has a structure in which the cylinder and die 3 can be heated to a desired temperature.

In FIG. 3(a), the dice 12 and the die 12' have different lengths of the straight portions 42, 42', and in FIG. 3(b)
), the straight part 4 between die 12' and die 12°
The lengths of 2' and 42'' are different.

Extrusion molding was carried out as follows using such an apparatus.

Next, Ti80at%-Ni20 was used as a raw material for extrusion molding.
Ni powder with an average particle size of 10 ft m was added to an alloy powder with an average particle size of 12 μm with a composition of at% Ti50aL.
%-Ni50 at% and 100 parts by weight of mixed powder mixed in a ball mill, ethyl/vinyl acetate copolymer resin.

7.8 parts by weight, 11.0 parts by weight of polybutyl methacrylate, 4.2 parts by weight of paraffin wax with a melting point of 68°C.

A mixture was obtained by mixing and kneading 2.8 parts by weight of dibutyl phthalate.

Next, the heater 21 was heated to 130°C, and the heater 22 was heated to 120°C.
Cylinder 1. as °C. After heating the screw 2 and die 3, the above-mentioned mixture is filled between the cylinder 1 and the screw 2 and melted, and as the screw 2 rotates, the molten mixture passes through the breaker plate 16 and further through the die 12.
12', 12'.

]2° to obtain a coil-shaped extruded product 30'.

The die 12, 12' and the die 12' in the method of extruding a powder mixture described hereinabove.

12" straight sections 42, 42' and 42'.

Because the lengths of 42-゛ are different, the molten mixture is in the straight part 4.
2. When passing through the gaps between 42', 42', and 42°, there is a difference in flow resistance and a velocity gradient occurs in the direction perpendicular to the extrusion direction, so the extruded product becomes coiled and has a so-called three-dimensional shape. It is a curved object with a curved surface.

Further, the extruded body 30'' described above was heated from room temperature to 600° C. at a temperature increase rate of 10° C./hour in an atmosphere in which argon gas was flowed at 2.Q/m]n.

After holding it at 600°C for 2 hours, the binder was removed by cooling it to room temperature, and then it was placed in a vacuum furnace and heated from room temperature to 1.00'C at a heating rate of 150°C per hour. By holding for a certain period of time, a coil-shaped Ti--Ni alloy sintered body having a shape similar to the extruded body 30' was obtained.

For comparison, the lengths of the straight parts 42, 42', 42', 42'' of the dice 12. The mixture was extruded to obtain an extrusion molded body having a surface parallel to the extrusion direction without a curved surface, and in a softened state immediately after extrusion, the extrusion molded body 3 in the third embodiment described above was obtained.
After deforming to a shape equal to 0', the binder was removed in the same manner as in the third embodiment, and cracks were generated in the two curved surfaces, making it possible to obtain a good binder-free body.

The usefulness of the third example was confirmed.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various changes can be made without departing from the gist of the present invention.

For example, in the above embodiments, a so-called thermoplastic polymer was used as the binder, but it goes without saying that water-soluble materials such as various rubbers and methyl cellulose can also be used as the binder.

In addition, ceramics or metal powder can also be used as Fe-
It goes without saying that the material is not limited to Co alloy powder, alumina powder, and Ti-Ni alloy powder.

Further, in all of the above-mentioned embodiments, the extrusion molded body is debindered and sintered, but there is no problem in using the extrusion molded body itself as a final product.

[Effects of the Invention] As described above, the extrusion molding method for a powder mixture of the present invention is such that when extruding a mixture of at least one of ceramic and metal powders and a binder having plasticity, the flow rate in the extrusion direction is by having a velocity gradient perpendicular to the extrusion direction.

Since a curved object can be manufactured by adding a two-dimensional or three-dimensional curved surface to an extrusion molded object, the manufacturing process that requires two-dimensional bending and pressure can be simplified, and the extrusion can be removed during the two-dimensional processing. This has the effect of avoiding deformation or destruction due to stress applied to the molded body.

Therefore, the method of extrusion molding a powder mixture of the present invention can simplify the manufacturing process and improve the yield.

It is extremely useful for one's livelihood.

[Brief explanation of drawings]

FIG. 1(a) is a top sectional view showing an example of an apparatus for carrying out the extrusion molding method of the present invention, and FIG.
), FIG. 2(a) is a top sectional view showing another example of an apparatus for carrying out another extrusion molding method of the present invention, and FIG. 2(b) is a side sectional view of = 15 ~ Figure 3(a) shows yet another example of an apparatus for carrying out the extrusion molding method of the present invention.
FIG. 3(b) is a side sectional view of FIG. 3(a). In the figure. 1...Nylinder, 2.=Screw 13...Die, 1
]. 11', 12.12', 12', 12°°°・Dice, 15...Die holder, 16...Breaker plate. 21.22. 22'...Heater, 3C1, 30'
. 30″/Extrusion molded body, 41.4i’, 42°42’
, 42', 42'''' ---Die straight part.

Claims (1)

[Claims] 1. A method for obtaining a molded body by extruding a mixture obtained by mixing and kneading at least one of ceramics and metal powder and a binder having plasticity, comprising: A method for extruding a powder mixture, characterized in that a curved object is produced by extruding the object by making the flow velocity in the extrusion direction have a velocity gradient in a direction perpendicular to the extrusion direction.