JP3398026B2 - Manufacturing method of sintered body - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered body for producing a sintered body of metal or ceramics.

[0002]

2. Description of the Related Art A metal sintered body obtained by compacting and sintering fine metal powder can obtain a uniform composition by alloying the powder, as compared with a general cast product. The temperature can be controlled easily, the grain size can be controlled, and the physical properties such as strength can be predicted accurately. High dimensional accuracy can be obtained. A shape close to a product is obtained, and the amount of processing is small. By using MA (mechatronic alloy material) as the powder raw material, high strength can be secured as a fine structure. And so on.

On the other hand, a ceramic sintered body obtained by compressing and sintering powder ceramics can be produced at a lower cost and in a shorter construction period than a general ceramic molded product. Complex shapes can be manufactured. And so on.

For this reason, in machine parts such as impellers of rotary machines, which have complicated shapes and require high dimensional accuracy, it is widely practiced to use metal sintered bodies instead of cast products. . This also applies to the ceramic sintered body.

The process for producing such a sintered body is usually composed of a mixing process of mixing the raw material powder and various additives, a process of molding the powder after mixing, and a process of sintering the powder. Become. The molding process includes a press molding method, a cold static pressure molding method (CIP method) in which molding powder is put in a rubber mold and pressurized in a liquid, or a heat for simultaneously performing molding and sintering in a high temperature and high pressure atmosphere. There is a static pressure forming method (HIP method).

[0006]

However, in any of the above conventional methods, it is necessary to make an expensive mold or rubber mold in the molding process, which makes the unit price as a product expensive. turn into. Further, in the case of a product having a complicated shape, it is difficult to mold such a mold or rubber mold itself into a shape close to the product, and therefore,
There is a problem that post-processing needs to be performed after molding.

In view of the above, the present invention provides a sintered body which can be manufactured by a simple process without forming an expensive die or rubber die and having a complicated shape. It is intended to provide a manufacturing method.

[0008]

The invention according to claim 1 comprises the step of producing a porous resin container from particles or powder of a thermoplastic resin, and a powder sintering material inside the porous resin container. The step of filling and the step of heating the porous resin container filled with the powder sintering material in an non-oxidizing atmosphere to fuse the particles or powders of the thermoplastic resin into a gas-liquid tight resin container And a step of increasing the density of the powder sintered material inside by subjecting the gas-liquid-tight resin container to a hydrostatic molding process,
And a step of producing the sintered body by sintering the compressed powdery sintered material.

As a result, for example, a porous resin container can be prepared with a relatively easy and accurate shape and dimension by a stereolithography method, the inside of which is filled with the powdered sintered material, and then heated in a non-oxidizing atmosphere. By fusing the resins together, a gas-liquid-tight resin container containing the powder sintered material inside is formed. This is densified by a static pressure molding process and then sintered to produce a sintered body. In the static pressure molding process, liquid or gas is used depending on the case, and the resin container is also made airtight or liquidtight according to it.

The invention according to claim 2 is the method for producing a sintered body according to claim 1, characterized in that a rapid model producing method is used in the step of producing the porous resin container. As a rapid model manufacturing method, a selective laser sintering method, a droplet injection method, a melt deposition method, an optical molding method, a thin plate laminating method,
There are solid foundation curing methods and the like. Thereby, the porous resin container is relatively easily and accurately formed based on the shape data stored in advance.

According to a third aspect of the present invention, the method for producing a sintered body according to the first aspect is characterized in that the step of heating in a non-oxidizing atmosphere is performed in a vacuum atmosphere. This allows
Since the gas in the powder sintered material is removed through the porous resin container, it is compressed in this process and the density is increased.

According to a fourth aspect of the present invention, a porous resin container is divided into a plurality of pieces, the powder sintered material is filled through the openings of the divided portions, and the openings are joined to each other before a non-oxidizing atmosphere. The method for producing a sintered body according to claim 1, wherein heating is performed in the inside. As a result, the device for producing the porous resin container can be downsized, and a precise shape can be easily produced.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention in which an integrated impeller of a rotary machine is manufactured from a metal sintered body will be described below with reference to the drawings.

First, as shown in FIG. 1, porous resin containers 10 and 12 for forming internal spaces 10a and 12a along the shape of a molded product by joining with a thermoplastic resin such as polycarbonate are prepared. . The porous resin containers 10 and 12 are formed to have a thin wall thickness t of, for example, about 1 mm, and the inside thereof is filled with a powdered sintered material and provided with powder filling ports 10b and 12b which are connected to each other.

In this embodiment, the two porous resin containers 10 and 12 form a resin container for one molded product, but the resin is divided appropriately according to the shape of the product. It goes without saying that the container may be configured.

As shown in FIG. 2, the porous resin containers 10 and 12 have particles of a thermoplastic resin such as polycarbonate in a chamber 22 of a laser selective sintering apparatus 20 using a stereolithography method and having a predetermined thickness. For example, it is manufactured by forming a raw material particle layer 24 by uniformly filling it with a thickness of 0.1 mm and irradiating it with a laser beam. The laser selective sintering device 20 includes a laser irradiation device 21 arranged above the chamber 22 and a control device (not shown), and the storage unit of the control device has a resin container 1 to be manufactured in advance.
Shapes 0 and 12 are stored as numerical data, for example.

The control device calculates a shape obtained by cutting into a thickness corresponding to the thickness of the raw material particle layer 24, and instructs the laser irradiation device 21 to perform laser light scanning along a pattern in which this shape is viewed in plan. Send a control signal. The laser irradiation device 21 irradiates the raw material particle layer 24 with laser light from a laser light source 26 such as a carbon dioxide gas laser generator through a mirror 28. Then, the raw material particle layer 24
The portion irradiated with the laser light is selectively melted, and the surface layers of the particles of the resin 24 adjacent to each other are fused to each other to form the porous resin thin piece 30. By repeating this process, the resin thin pieces 30 are sequentially laminated to form the porous resin container 1
0, 12 are produced.

Next, in each of the porous resin containers 10 and 12,
After filling the metal powder 32, which is a powder sintering material, to a predetermined density while applying vibration, by fitting the other powder filling port 12b into the one powder filling port 10b, as shown in FIG. Both porous resin containers 10 and 12 are integrated.

Then, when this is placed in a gas-liquid tight container and heated to a temperature above the softening temperature of the thermoplastic resin 24 under reduced pressure,
While the gas in the porous resin containers 10 and 12 is being removed, the resin particles are fused to form resin containers 40 and 42 having a non-porous dense surface layer. In this process, metal powder 3
The gas existing inside 2 also passes through the peripheral walls of the porous resin containers 10 and 12 by vacuum suction and is exhausted to the outside, so that the metal powder 32 is compressed into the resin containers 40 and 42,
The packing density is increased while the original shape is stopped.

Next, the resin container 4 filled with the metal powder 32
After cooling 0 and 42 once, CIP processing is performed. That is, the metal powder 32 is, for example, placed in a liquid while being surrounded by the non-porous resin containers 40 and 42, and static pressure is applied to uniformly compress the metal powder 32. As a result, the packing density of the metal powder 32 is further increased while maintaining its shape, and a molded body of the metal powder 32 is obtained.

Next, the molded body is sintered at a predetermined temperature in a heating furnace and metal particles are bonded to each other to form a shape in conformity with the shape of the internal spaces 10a, 12a of the porous resin containers 10, 12. A metal sintered body (integrated impeller) is manufactured.

In the above process, the resin container is produced by using the laser selective sintering device 20,
Even when a product having a complicated shape is sintered, the resin container can be easily molded, and the cost for manufacturing the container is low. Moreover, since the shape of the container is precise, the amount of finishing processing to be performed on the sintered product is small, and the molding process of the product itself is simple, so that the cost is also low in this respect.

In this embodiment, an example in which a metal sintered body is manufactured is shown, but a ceramic sintered body can be manufactured in substantially the same manner by using powdered ceramics instead of metal powder. You can If a resin material having heat resistance is used, the hot isostatic pressing method can be used in the sintering step.

[0024]

EXAMPLE Using the laser selective sintering apparatus 20 shown in FIG. 2, polycarbonate resin porous containers 10 and 12 as shown in FIG.
m of Ni-Cr-Mo alloy metal powder 32 was filled while vibrating. The powder density at this time was 57% as measured by the Archimedes method.

Next, the two porous resin containers 10 and 12 filled with the metal powder 32 are integrated and then heated at 200 ° C. for 2 hours in a reduced pressure container of 1 torr to form a polycarbonate layer on the surface of the metal powder 32. Fused. After cooling, a CIP treatment was performed in which water was used as a medium in the pressure vessel and the pressure was 800 Mpa. The powder density at this time was 80% when measured by the Archimedes method.

Then, 140 M in an argon gas atmosphere
It was pressurized to pa and heated at 1000 ° C. for 1 hour to be sintered. This gives a tensile strength of 700 MPa and a porosity of 0.
% Sintered body (integrated impeller) could be produced. The tensile strength of the same shape cast with the same material was about 600 MPa.

[0027]

As described above, according to the present invention,
For example, a gas-liquid-tight resin container is formed based on a porous resin container that is relatively easily and accurately formed by a stereolithography method, etc.
It is possible to manufacture a sintered body product in a simple process without forming an expensive mold or a rubber mold and reducing the finishing process even with a complicated shape.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a porous resin container according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a process of producing a porous resin container.

FIG. 3 is a cross-sectional view of a porous resin container filled with metal powder.

[Explanation of symbols]

10,12 Porous resin container 10a, 12a internal space 20 Laser selective sintering equipment 24 Thermoplastic resin 32 metal powder (sintered powder material) 40,42 Non-porous resin container

Claims (4)

(57) [Claims] 1. A step of forming a porous resin container from granules or powders of a thermoplastic resin, a step of filling the inside of the porous resin container with a powdered sintering material, and a filling of the inside thereof with a powdered sintering material. The porous resin container is heated in a non-oxidizing atmosphere, and the thermoplastic resin particles or powders are fused together to form a gas-liquid tight resin container, and the gas-liquid tight resin container is subjected to static pressure. And a step of increasing the density of the powdery sintered material inside by performing a molding process, and a step of sintering the compressed powdery sintered material to produce a sintered body. Production method. 2. The method for producing a sintered body according to claim 1, wherein a rapid model production method is used in the step of producing the porous resin container. 3. The method for producing a sintered body according to claim 1, wherein the step of heating in a non-oxidizing atmosphere is performed in a vacuum atmosphere. 4. A porous resin container is divided into a plurality of pieces, which are filled with a powdered sintered material through the openings of the divided parts, and the openings are joined together before heating in a non-oxidizing atmosphere. The method for producing a sintered body according to claim 1.