JP3005368B2 - Manufacturing method of powdered sintered products - 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 compact from a mixture of a powder and a molding aid, removing the molding aid in a step of degreasing, and sintering to produce a sintered part. About.

[0002]

2. Description of the Related Art Sintered parts made of metal or ceramics have been rapidly developed by the practical application of powder injection molding technology. This technique is difficult by forming a material obtained by kneading an organic polymer material, whose main component is generally called a binder, a thermoplastic resin or wax into a metal or ceramic powder, using an injection molding machine, and then degreased and sintered. It has the feature that even processed and complicated three-dimensionally shaped parts can be manufactured with high precision and in large quantities. Further, according to this method, since fine powder is used, a sintered part having a higher sintering density than a sintered part obtained by a general direct pressure pressing method and having excellent mechanical properties can be obtained. However, there are parts that cannot be formed by a single molding even with this method, or that require a very complicated mold structure in a single molding.

For this reason, after forming a plurality of divided bodies having a desired shape from metal or ceramic powder, the divided bodies are joined in either a degreasing step after molding or a sintering step after degreasing to form a desired shape. A method of obtaining parts has been considered (Japanese Patent Application Laid-Open No. 60-204675).

[0004]

According to this manufacturing method, it is possible to manufacture a complicated three-dimensional part made of metal or ceramics which is impossible or difficult with one molding, but the parts joined after molding are fired. There is a problem in that the bonding strength after binding is weak, and when bonding is performed after degreasing, the strength of the degreased body itself is extremely weak, and the degreased body is deformed due to handling mistakes or the like during handling.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to make it possible to assemble a degreased product without deforming it. Another object of the present invention is to provide a method for manufacturing a powder sintered product capable of manufacturing a component having a high bonding surface strength.

[0006]

In order to achieve the above object, the present invention forms a plurality of divided bodies having a desired shape from a mixture of a sinterable powder and a molding aid, and a predetermined amount of the molding aid. After removing and assembling the divided body into a final shape, the remaining molding aid is removed and sintering is performed. Also, the present invention forms a plurality of divided bodies having a desired shape from a mixture of a non-oxide type powder and a molding aid which can be sintered, removes the molding aid in a non-oxidizing atmosphere, and oxidizes the surface in an oxidizing atmosphere. After that, it is assembled into a final shape and sintered.

[0007]

According to the present invention, in the degreasing step, the binder of the molded divided body is degreased by a predetermined amount, and after assembling, the remaining binder is degreased and sintered again. Can be obtained. In the present invention,
By oxidizing the surfaces other than the joining surface of the divided body that has been degreased in a non-oxidizing atmosphere in an oxidizing atmosphere and sintering after joining, there is no deformation failure due to handling mistakes during joining, and after sintering It is possible to obtain a sintered component having a high bonding strength.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. As a specific example, a method for producing a powder sintered product in the shape of an L-shaped tube as shown in FIG. 1 will be described. If a part having this shape is to be manufactured by injection molding, the mold structure becomes very complicated. Further, since a material such as a metal or a mixture of ceramic powder and a thermoplastic resin is used as a material, the fluidity is not as good as that of a general plastic, and it may be impossible to mold a component having a complicated mold structure. Therefore, a part can be obtained by molding a plurality of divided bodies having a desired shape, sintering them after assembling them, and the present invention is characterized by an assembling process.

(Example 1) In this example, SUS316L powder having an average particle diameter of about 10 µm was kneaded at a weight ratio of 100: 11 with respect to a mixture of an acrylic resin and a wax. Then, the divided bodies 1 and 2 as shown in FIG. 2 are molded by an injection molding machine. Usually, the degreasing step is performed by heating to 500 ° C. in a reducing atmosphere at about 24 hours to remove almost 100% of the binder.
0%. Next, as shown in FIG. 3, after assembling the divided bodies 1 and 2 with the joining surface 3, the remaining binder is degreased, and further sintering is performed at 1350 ° C. and about 1 hr, as shown in FIG. Powder sintered product is obtained.

(Example 2) In this example, SUS316L powder having an average particle size of about 10 μm was kneaded at a weight ratio of 100: 11 with respect to a mixture of an acrylic resin and a wax. Then, the divided bodies 1 and 2 as shown in FIG. 2 are molded by an injection molding machine. Usually, the molded article is heated to 500 ° C. in a reducing atmosphere at about 24 hours to remove almost 100% of the binder, and then sintered, but when the degreasing step is completed at 500 ° C., the joining surface 3 Is exposed to an oxidizing atmosphere to form an oxide film on the surface. Next, as shown in FIG. 3, the divided bodies 1 and 2 are assembled in accordance with the bonding surface 3, and the surface oxide is reduced while heating in a reducing atmosphere.
Hr is sintered to obtain a powder sintered product as shown in FIG.

[0011]

As described above, the present invention forms a plurality of divided bodies having a desired shape from a mixture of a sinterable powder and a molding aid, removes a predetermined amount of the molding aid, and After assembling the body into the final shape, the remaining molding aid is removed and sintering is performed, whereby a sintered part having a high bonding strength after sintering can be obtained. The present invention also provides a method for forming a plurality of divided bodies having a desired shape from a mixture of a non-oxide type powder and a forming aid which can be sintered, removing the forming aid in a non-oxidizing atmosphere, and treating the surface in an oxidizing atmosphere. After oxidizing, by assembling to the final shape and sintering, it can be assembled without deforming the degreased product,
Further, it is possible to obtain a part having a stronger joint surface than when assembled in a state of a molded product.

[Brief description of the drawings]

FIG. 1 is a view showing the appearance of a powder sintered product obtained by the method of the present invention.

FIG. 2 is a diagram showing the divided body.

FIG. 3 is a view showing a state in which a divided body is assembled.

[Explanation of symbols]

 1 split body 2 split body 3 joining surface

Claims (2)

(57) [Claims] 1. A plurality of divided bodies having a desired shape are formed from a mixture of a sinterable powder and a molding aid, a predetermined amount of the molding aid is removed, and the divided bodies are assembled into a final shape. A method for producing a powder-sintered product, comprising removing remaining molding aid and sintering. 2. A plurality of divided bodies having a desired shape are formed from a mixture of a sinterable non-oxide powder and a molding aid, the molding aid is removed in a non-oxidizing atmosphere, and the surface is oxidized in an oxidizing atmosphere. A method for manufacturing a powdered sintered product, comprising: assembling into a final shape after sintering;