JP2829165B2 - Manufacturing method of hollow 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 hollow body using metal powder.

[0002]

2. Description of the Related Art In the case of forming a member having a predetermined shape using metal powder, a so-called powder metallurgy technique in which a green body having a desired shape is formed in advance with the metal powder and the green body is sintered thereafter. It depends on you.

When a hollow body is manufactured by such a powder metallurgy technique, it is necessary to form a green body of a metal powder into a hollow shape as described above, and the hollow body is formed by a known technique such as powder pressing. Since the formation of a green body is industrially difficult, the green body is generally formed by so-called slip casting.

[0004]

By the way, the formation of the green body by the slip casting is as follows.
A metal powder is suspended in a liquid medium, and the suspension containing the metal powder is absorbed into a mold by a capillary phenomenon or the like, thereby forming a metal powder layer on the mold surface of the mold, thereby forming a green.・ It forms the body.

Therefore, it takes a long time to form a green body by such slip casting.
Forming a green body with a thick metal powder layer is industrially difficult in practice.

The present invention has been made based on such a background, and has as its object to form a green body having a hollow shape in a short time. It is also an object of the present invention to be able to form in an objective manner.

[0007]

In order to achieve this object, an invention according to claim 1 is to knead a binder curable by water and a metal powder in a solvent to form a slurry. The material is applied to the mold surface of a mold having a mold surface forming the outer surface of the hollow body to form a hollow shape, and thereafter, the material is supplied with water from the hollow inner surface side. And cured.

[0008]

According to the first aspect of the present invention, a slurry-like material is formed in a hollow shape inside a molding die, and water is supplied from the inner surface side of the slurry-like material to perform curing.

Therefore, instead of forming the material layer by absorbing the suspension as in the conventional slip casting, a slurry-like material is applied to the mold surface of the mold to form a hollow body. Therefore, the green body is formed in a short time, so that the green body having a thick metal powder layer can be industrially implemented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings. First, the first embodiment will be described with reference to FIGS.

The manufacturing process of the first embodiment is as shown in FIG.

Hereinafter, the manufacturing method will be described with reference to FIG. 4. The outer mold, the inner mold, the material, and the like as the molding dies used in this manufacturing method are as follows.

First, the outer mold 1 is made of gypsum having an appropriate water permeability, and has a mold surface 2 for forming a bottomed cylindrical hollow body inside thereof. See figure).

The outer mold 1 is not limited to gypsum but may be formed of other materials such as water-impermeable silicone rubber.

As will be described later, the mold surface 2 of the outer mold 1 is coated with a slurry-like material 3 containing a metal powder and made of a binder dissolved in a solvent, and is formed into a hollow shape. Things.

The metal powder in this embodiment is a powder of stainless steel (JIS SUS316L).
As shown in FIG.

The metal powder is a metal powder produced by a gas atomizing method, and has an average particle size of about 6
It is about μm, but may be 10 μm or less in average particle size.

[0018]

[Table 1]

An acrylic resin binder (true specific gravity 1.05) is used as a binder, and an alcohol solvent (true specific gravity 0.93) is used as a solvent.

The mixing ratio of the metal powder, the binder and the solvent is, for example, when the weight of the metal powder is 100, the binder is 5 and the solvent is 25.

The production of a hollow body using these is carried out as follows (see FIG. 4).

First, a binder corresponding to the above mixing ratio is sufficiently dissolved in a solvent while stirring for about 5 hours.

Thereafter, a predetermined amount of the metal powder is added, and the metal powder is uniformly mixed in the binder to produce a slurry-like material. The mixing time is, for example, about 30 minutes in a Shinagawa mixer.

The viscosity of the slurry-like material thus obtained is, for example, about 140 dPa · S.

Then, the slurry-like material is charged into, for example, a vacuum Shinagawa mixer or the like and deaerated for about 8 minutes.

Next, a molding step of the thus degassed slurry-like material is performed.

In the molding step, the slurry-like material 3 is applied along the mold surface 2 of the outer mold 1 to have a desired thickness (in this embodiment, a cylindrical shape with a bottom). In this case, a material 3 having a thickness of 10 to 20 mm is entirely formed in a layer inside the outer mold 1 (see FIG. 2).

This embedding work may be performed using a known coating device, or may be performed manually.

Thereafter, the outer mold 1 coated with the material 3 is immersed in the water W of the water tank 4 and left standing for about 24 hours (see FIG. 1).

In the step of allowing the outer mold 1 to stand in water,
Water W is supplied to the mold surface 2 side of the material 3 by the water permeability of the outer mold 1 itself, whereby the material 3 hardens from the mold surface 2 side (hereinafter, referred to as an outer surface 3a). I do.

Since the surface of the material 3 inside the hollow shape (hereinafter referred to as the inner surface 3b) is filled with the water W in the water tank 3, the inner surface 3b of the hollow shape is filled with the water W. Also, the curing of the material 3 proceeds.

That is, since the curing of the hollow material 3 proceeds simultaneously from both the outer surface 3a and the inner surface 3b of the hollow shape, the material 3 is rapidly cured.

When the material 3 is hardened (after 24 hours in this embodiment), the outer mold 1 is pulled out of the water tank 4 and the residue inside the hollow material 3 in the outer mold 1 is drained. (See FIG. 3 (a)), the inside of the hollow material 3 is filled with new water W and left for a while to complete the hardening of the material 3 (see FIG. 3 (b)).

After the material 3 is completely cured on the mold surface 2 as described above, the water W inside the hollow material 3 is drained,
After the material 3 has sufficient strength, it is released from the outer mold 1 to obtain a green body 5 as an intermediate (see FIG. 3 (c)).

The green body 5 has the outer surface formed along the shape of the mold surface 2 using the metal powder and the binder as main materials. In this embodiment, the green body 5 has a bottomed cylindrical shape. .

After releasing the green body 5 from the outer mold 1, the green body 5 is left to stand for an appropriate time or dehydrated and dried by a drying device.

The green body 5 sufficiently dried in this way is, for example, approximately 1000 to 1300 ° C. in a vacuum sintering furnace 6.
And sintering for about 3 hours to obtain a sintered product formed into a hollow shape.

In the embodiment described above, the water filling and draining steps are provided between the draining step and the demolding step. For example, when the thickness of the material 3 is small or the standing time in water is reduced. If the settings are sufficient, these steps can be omitted as shown by the broken lines in FIG.

Next, a second embodiment will be described with reference to FIGS.

In the second embodiment, the structure for supplying water to the inside of the hollow material is different from that of the first embodiment.
Other points are the same as in the first embodiment.

In the following, only the differences will be described, and the common points will be denoted by the same reference numerals in the drawings, and description thereof will be omitted.

That is, in the second embodiment, the inner mold 7 formed in a column shape concentrically with the center O of the outer mold 1 is provided. The inner mold 7 is a mold for accurately forming a hollow portion into a predetermined shape inside the material 3.
Like the outer mold 1, it is formed of gypsum having appropriate water permeability.

For this reason, when the outer mold 1 is filled with the material 3 and the inner mold 7 is placed at a predetermined position and immersed in the water tank 4, the outer surface 3a of the material 3 is formed in the same manner as in the previous embodiment. Water W is supplied through the outer mold 1, water W is supplied to the inner surface 3 b of the material 3 through the inner mold 7, and the material 3 cures simultaneously from the inner and outer side surfaces 3 a and 3 b.

Thus, according to the second embodiment, the material 3 is rapidly cured.

As described above, since the hollow portion of the material 3 is formed by the inner mold 7, there is an advantage that the shape of the hollow portion inside the hollow body is accurately formed.

Since the inner mold 7 is used as described above, the sludge discharging step performed in the first embodiment may be omitted, and the water filling step and the like may be performed as necessary.

With the green body 5 thus formed, a hollow body formed into a predetermined shape can be manufactured by drying and sintering in the same manner as in the first embodiment.

In the embodiment described above, the hollow body having a cylindrical shape with a bottom is described. However, it is needless to say that the present invention is not limited to this and can be applied to various hollow shapes.

[0049]

As described above, according to the first aspect of the present invention, a slurry-like material is formed in a hollow shape inside a molding die, and water is supplied from the inner surface side of the slurry-like material. Thus, curing is performed.

Therefore, instead of forming a material layer by absorbing a suspension as in conventional slip casting, a slurry-like material is applied to the mold surface of the mold to form a hollow body. Therefore, the green body is formed in a short time, so that the green body having a thick metal powder layer can be industrially implemented.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an underwater standing step in a first embodiment of the manufacturing method of the present invention.

FIG. 2 is a cross-sectional view of a material embedding state in the first embodiment.

FIG. 3 is an explanatory view of a manufacturing process in a first embodiment of the manufacturing method of the present application, wherein (a) is a drainage process, (b) is a water filling process, (c) is a demolding process, and (d) is a This is a sintering process.

FIG. 4 is a manufacturing process diagram in the first embodiment of the manufacturing method of the present application.

FIG. 5 is an explanatory diagram of an underwater standing process in a second embodiment.

FIG. 6 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 W Water 1 Outer die (molding die) 2 Mold surface 3 Material 3a Outer surface 3b Inner surface 4 Water tank 5 Green body 6 Vacuum sintering furnace 7 Inner die (molding die)

Claims (3)

(57) [Claims] 1. A mold having a mold surface for forming an outer surface of a hollow body by mixing a binder curable by water and a metal powder in a solvent to form a slurry. A method for producing a hollow body, characterized in that the material is applied to a surface to form a hollow shape, and thereafter, the material is hardened by supplying water from the hollow inner surface side. 2. The method of manufacturing a hollow body according to claim 1, wherein the molding die is formed of a water-permeable material, and the material formed into a hollow shape by applying to a mold surface of the molding die includes: A method for producing a hollow body, comprising supplying water from both a molding die side and a hollow inner surface side, and curing from both inner and outer surfaces of the hollow material. 3. The method for manufacturing a hollow body according to claim 2, wherein the mold having a hollow material is allowed to stand in water, so that the mold is permeated on the outer surface side of the material, and water is introduced. A method for producing a hollow body, comprising supplying water while allowing water to penetrate into the hollow inner surface of the material.