JPH04311502A - Production of metal parts - Google Patents

Abstract

PURPOSE:To produce parts which are difficult to produce by a technique for injection-molding metal powder with the conventional molding tool or to produce parts which are difficult to produce without using a slide core with a low-cost mold. CONSTITUTION:Spherical parts 1 are formed with brass and set in rectangular prism-shaped cavities 2 formed in a movable mold 3. Stainless steel powder well mixed with a thermoplastic resin binder, a lubricant and a plasticizer is injected into the cavities 2 with an injection molding machine, molded and cooled. The resulting molded body 5 is taken out and the gate 6 is cut off to obtain molded parts each contg. embedded spherical brass. The parts are immersed in 10% nitric acid soln. and spherically recessed parts are obtd. by chemically dissolving the brass in the soln. The binder is then removed and sintering is carried out to produce sintered parts.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of manufacturing complex, precision metal parts using metal powder.

0002

BACKGROUND OF THE INVENTION In conventional metal powder injection molding technology, various measures have been taken to manufacture complex and precise parts, such as adding a slide core to the mold. However, even with these efforts, there are some shapes that cannot be molded into desired parts, and steps such as adding machining after sintering have been taken. Furthermore, even in the case of parts that can be manufactured using slide cores, there are drawbacks such as the cost of the mold being very high and the manufacturing time of the mold being extremely long.

0003

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, facilitates the manufacture of molds, and reduces the cost of molds, making it possible to manufacture complex or precise parts. Furthermore, it is possible to manufacture parts with shapes that could not be manufactured using conventional molds.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a chemically soluble metal part that is preformed into a desired shape from a material different from that of the intended finished part. After setting in the cavity of the mold, a material made by mixing metal powder and an organic binder is injected to obtain a molded body. Thereafter, the metal parts set in this molded body are chemically melted to obtain a molded body made only of the injected set material. By degreasing and sintering this molded body, desired shapes or precision parts are manufactured.

[0005]

[Operation] The present invention allows complex and precise parts to be manufactured without using expensive molds, and also enables the manufacture of parts that cannot be produced using ordinary molds.

[0006]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. A spherical part 1 was made using a brass material and set in a cavity 2 formed in a rectangular parallelepiped shape in a mold 3 on the moving side. A well-mixed material of stainless steel powder, thermoplastic plastic as a binder, lubricant, and plasticizer was injected into this cavity using an injection molding machine. At this time, the stainless steel powder has an average particle size of 10 μm.
SUS-316 material was used. Furthermore, polystyrene, ethylene vinyl acetate, and butyl methacrylate were used as thermoplastic materials, stearic acid was used as a lubricant, and dibutyl phthalate was used as a plasticizer.

At this time, the ratio of metal to organic material was 100:13 by weight. Further, the molding temperature was 170°C. After molding, the mold was cooled, the mold was opened, the molded body 5 was taken out, and the gate 6 was cut to obtain a molded part as shown in the cross-sectional view in FIG. This part was immersed in a 10% nitric acid solution to chemically dissolve the brass to obtain a part as shown in cross section in FIG. After that,
Organic substances were removed in a debinding furnace in an air atmosphere. The binder-removed molded body was sintered at 1300° C. in a vacuum furnace to produce a sintered part as shown in the cross-sectional view in FIG. The density of the sintered body was 96% of the true density of the material.

The parts according to this example had shapes that could not be manufactured using ordinary injection molds. Suitable materials for the parts to be set in the cavity in the present invention include aluminum, zinc, copper, and other materials that are chemically easily dissolved by acids. Further, the parts to be set in the cavity can be formed by machining, lost wax method, die casting method, powder metallurgy method, etc.

[0009]

[Effects of the Invention] As described above, the present invention allows parts that are difficult to manufacture using ordinary molds to be manufactured, and parts that are difficult to manufacture without using slide cores etc. to be manufactured using inexpensive molds. It has the advantage that it can be used and manufactured.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing a cross section of a mold showing a molding state for explaining the present invention.

FIG. 2 is a diagram showing a cross section of an injection-molded molded article.

FIG. 3 is a diagram showing a state in which a part set in a cavity from an injection-molded molded body is chemically dissolved.

FIG. 4 is a sectional view showing a sintered state.

[Explanation of symbols]

1 Insert part formed of a material different from powder metal 2 Cavity 3 Movable side mold 4 Fixed side mold 5 Molded body 6 Gate of molded body

Claims (1)

[Claims] Claim 1: A metal powder and an organic binder are mixed into pellets, injection molded into a mold formed into a desired shape, and after the binder is removed from the molded body, sintering is performed to form a metal part. In the injection molding technology for manufacturing metal powder, a part made of a metal material different from the metal powder is inserted into a mold, and then a material made of a mixture of metal powder and a binder is placed in the mold so as to cover the part. The parts are molded by injection molding into the molded body, and then the metal parts made of a material different from the metal powder are removed from the molded body by chemical melting treatment, etc., and the parts are degreased and sintered. A method for manufacturing metal parts.