JP2591884B2 - Isotropic hydrostatic pressing mold, molding method using the same, method and apparatus for manufacturing isotropic hydrostatic pressing mold, and isotropic hydrostatic pressing molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an isotropic hydrostatic pressing mold,
A molding method using the same, a method and an apparatus for producing the same, and an isotropic isostatic pressing product, and more particularly, a coating holder used for isotropic isostatic pressing, a method and an apparatus for producing the same, and the coating holder. The present invention relates to a molded product obtained by isotropic hydrostatic pressure treatment.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a powder, various methods such as isotropic isostatic pressing, dry packing, casting, extrusion and injection molding are known. In this isotropic isostatic pressing, only a compact having a simple shape and poor shape accuracy could be obtained. In such a situation, in recent years, in isotropic hydrostatic pressing, for example,
Japanese Patent Application Laid-Open No. 202799/1999 proposes a method in which a film of resin or the like is formed on the inner surface of a mold using a gas-permeable mold, the raw material powder is filled, and cold isostatic pressing is performed. In addition, Japanese Unexamined Patent Publication
No. 3-16900 discloses that a resin mold blow-molded in a metal mold is filled with powder, degassed and sealed to form a powder-filled resin mold in advance, and the powder-filled resin mold is cooled. A method of isostatic pressing has been proposed.

[0003]

However, the isotropic hydrostatic pressing method as described above is not yet fully satisfactory as an isotropic hydrostatic pressing method. In the method described in -202799,
Even though it has air permeability, there is a problem that the rigid mold itself inhibits the isotropic shrinkage of the raw material powder and cannot obtain a molded body having excellent shape accuracy. Also, JP-A-63-
In the method described in Japanese Patent No. 16900, the deaeration after filling the raw material powder is performed by vacuum suction from the filling powder side while the resin mold is opened, so that the resin mold is easily deformed and the molded body having good shape accuracy is obtained. There was a problem that was not obtained. The present invention has been made in view of such problems of the related art, and an object thereof is to provide a novel isotropic hydrostatic pressing mold having a specific resin coating, a method of manufacturing the same, and a method of manufacturing the same. It is to provide a manufacturing apparatus.

[0004]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned problems, and as a result, using a gas-permeable and pressure-medium-impermeable coating, pressurizing in a device capable of reducing pressure, The inventors have found that the object has been achieved, and have completed the present invention. Therefore, the isotropic hydrostatic pressing mold of the present invention is characterized in that a forming die used for isotropic hydrostatic pressing is provided with a film that is permeable to air and impermeable to a pressure medium.

Further, according to the production method of the present invention, an isotropic hydrostatic pressing mold is produced, in which a powder having a predetermined shape and a high density is filled in a gas permeable and pressure medium impervious film. A method, comprising: placing a split mold for powder filling comprising a male member and a female member having air permeability in a processing chamber provided with an exhaust port and a pressure medium supply / discharge port; The convex portion of the member and the land region adjacent thereto, and the cavity having the predetermined shape of the female member and the land region adjacent thereto are applied to the cavity, and the powder is applied to the cavity of the female member to which the coating is applied. And the surface of the powder is brought into contact with the convex portion of the male member on which the coating is applied, and then the processing chamber is evacuated to a reduced pressure through an exhaust port to remove air contained in the powder into the female mold. The convex portion of the male member is removed from the cavity of the female member while exhausting air through the member and the coating. And pressurized the powder with these convex portions to improve the packing density of the powder, and then, by using a heater provided in at least one land area of the male member and the female member, the coatings are separated from each other. After heating and joining,
A pressure medium is introduced into the processing chamber through the pressure medium supply / discharge port to obtain an isotropic hydrostatic pressing mold filled with powder at a high density.

Further, the manufacturing apparatus of the present invention is a manufacturing apparatus for an isotropic hydrostatic pressing mold in which a split mold comprising a male member and a female member is disposed in a processing chamber. Has an exhaust port and a pressure medium supply / discharge port, the female mold member has air permeability, and has a cavity of a predetermined shape for filling powder,
The male member includes a convex portion that fits into the cavity, at least one of the male member and the female member includes a coating bonding heater in a land area thereof, and the coating is formed of a gas-permeable and pressure medium. It is characterized by being impermeable.

Further, the isotropic hydrostatic pressing molded article of the present invention is an isotropic hydrostatic pressing mold formed by filling powder in a gas permeable and pressure medium impervious film at a high density. It is characterized by being obtained by hydrostatic pressing.

Hereinafter, the manufacturing apparatus of the present invention will be described in detail. The manufacturing apparatus of the present invention has a processing chamber provided with an exhaust port and a pressure medium supply / discharge port, and in this processing chamber, an isotropic hydrostatic pressing mold of the present invention, that is, for forming a specific film holding body. Equipped with split mold. The shape, material, dimensions, and the like of the processing chamber are not particularly limited, and it is sufficient to ensure airtightness in the chamber. For example, a dome shape, a box shape, a column shape,
It may be made of metal or resin. Further, the number of exhaust ports and pressure medium (hereinafter, abbreviated as “pressure medium”) supply / discharge ports is not limited.

The split mold comprises a male member and a female member, and the female member has a cavity for imparting a predetermined shape to the film holder. The female member is formed so that air can pass therethrough. For example, a case where the entire female member is formed of a porous material can be mentioned. In addition, the female member is formed of metal and / or resin and an appropriate number of pores are formed. Then, the cavity and the outside of the female member may be communicated. In this case, the size, porosity, number, and the like of the pores can be appropriately changed according to the pressure medium introduced into the processing chamber. That is, the material of the female member only needs to have air permeability.

On the other hand, the male member has a convex portion which can fit into the cavity of the female member and press the powder. Further, it is preferable that an end opposite to the convex portion protrudes and extends to the outside through the processing chamber. This is because the pressurization of the powder may be performed only by the weight of the male member, but pressurization can also be performed by connecting the protruding end to a pressurizing source outside the processing chamber. It is. The material of the male member is not limited, and can be made of a rigid body such as metal, ceramics, and resin.

The male member and / or the female member may have a land area, that is, a portion of a mating surface which comes into close contact with each other when the male member and the female member are clamped.
A heater for joining a coating for powder filling is provided. A heater may be provided in the land area of both the male member and the female member. The method of installing the heater is not particularly limited, but examples thereof include attachment and burying. The male member and the female member are not necessarily required to be formed integrally. Particularly, in the case of the female member, a plurality of split molds may be combined, or a turbine rotor having a complicated shape may be used. Then, it is also possible to use a slide core type.

Next, the production method of the present invention will be described in detail. In the manufacturing method of the present invention, first, the convex portion of the male member and the land region adjacent thereto, and the cavity of the female member and the land region adjacent thereto have air permeability and a hydraulic medium. Is applied. As an example of this coating, a silicone polymer coating can be mentioned. Examples of the deposition method include a blow molding method. The film thickness can be appropriately selected depending on the material constituting the film, the method of applying the film, the shape of the film holder, the powder, and the like.
1 mm to 0.3 mm is preferred.

Next, the powder is filled into the cavity on which the coating is applied. Examples of the powder include ceramic powder, metal powder, and plastic.
Next, the convex portion of the male member processed as described above is brought into contact with the surface of the powder filled in the cavity, and is placed in the processing chamber in this state. That is, for example, when the split mold is a vertical type, the male member is placed on the female member so that the convex portion and the powder surface are in contact with each other, and this is arranged in the processing chamber as it is. . As a result, the powder is surrounded by the coating. At the time of this contact, as described above, it is preferable that the end (top) of the male member opposite to the convex portion is projected outside the processing chamber.

Next, the processing chamber is sealed, and then the exhaust port is opened, and the processing chamber is evacuated and evacuated by a vacuum pump or the like. During this exhaust, the powder is deaerated through the gas permeable coating and the wall of the female member, and the convex portion of the male member is fitted into the cavity by its own weight, and presses the powder. Improve the packing density of powder. At this time, the pressing force may be increased by applying an external force to the end protruding outside the processing chamber. By this exhaust / pressurization treatment, the powder is given a predetermined shape accurately by the cavity and the convex portion. The pressure in the processing chamber can be appropriately selected depending on the properties of the powder and the coating, but is preferably about 10 Torr.

Next, the exhaust port is closed, and among the coatings applied to the projections and the land areas adjacent thereto and the cavities and the land areas adjacent to the cavities, the coatings of both land areas are separated by the heating. The powder is sealed by joining with a vessel. Therefore, this joining does not impair the shape of the obtained film holder, and is excellent in shape accuracy. In joining the films, an adhesive or the like may be used.

Next, the pressure medium supply / discharge port is opened, and the pressure medium is introduced into the processing chamber to immerse the male member and the female member. By immersion by introducing the pressure medium, it is possible to prevent air from flowing into the degassed powder as described above. Further, the female member may have a pressure medium permeability, in which case the pressure medium passes through the wall of the female member to reach the cavity and presses the powder through the coating. . Thereby, the packing density of the obtained film holding body is further increased. The pressure medium used is not particularly limited, and examples thereof include water, oil, and a pressure medium used for isotropic hydrostatic pressurization. Then, the mold is released to obtain a film holding body, that is, an isotropic hydrostatic pressing mold.

Next, the isostatic pressing mold of the present invention will be described. The isotropic isostatic pressing mold of the present invention has good shape retention, excellent flexibility, good shape transferability, and is densely filled with powder. Therefore, if the isotropic hydrostatic pressure is applied using a pressure medium, since the shape following property is good, a molded body which isotropically shrinks, has high shape accuracy and uniform density can be obtained. For this reason, isotropic isostatic pressing may be possible even for parts having a complicated shape such as a turbine rotor. Moreover, since the powder is densely packed and the amount of air mixed into the powder is extremely small,
It is possible to prevent the yield from lowering due to breakage of the coating or leakage of the pressure medium.

The coating can be decomposed and removed by a treatment such as binder removal generally performed at 500 ° C. or higher. However, any powder that can be fired in an oxygen atmosphere may be burned in the firing step. When heat treatment at 500 ° C. or more cannot be performed, or when there is a possibility that the molded product may be adversely affected during firing, the molded product can be removed in advance with a suitable tool such as a knife.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the manufacturing apparatus of the present invention. In FIG. 1, the manufacturing apparatus 1 is configured by disposing a split mold 20 including a male mold 30 and a porous female mold 40 in a processing chamber 10. The processing chamber 10 includes an exhaust valve 12 and a water supply / drain valve 14 which is an example of a pressure medium supply / discharge valve. The exhaust valve 12 is connected to a vacuum pump (not shown). It is connected to the.

The female mold 40 is made of ceramics having a pore diameter of 120 μm and has air permeability. In addition, this female mold 40
Has an annular cavity 42 at the top. In addition,
In this embodiment, the female mold 40 is formed integrally, but may be formed from a plurality of divided molds.
On the other hand, the male mold 30 is made of SUS, and has an annular convex portion 32 fitted into the cavity 42 at the bottom thereof. The top part 34 of the male mold 30 is connected to the processing chamber 10.
Are arranged so as to protrude to the outside through an opening 16 provided at the top. In this case, by mounting an O-ring 18 between the opening 16 and the male mold 30, airtightness in the processing chamber 10 is maintained.

Further, a heater 70 for bonding the air-permeable and water-impermeable coatings 50 and 52 is embedded in the land area 36 of the male mold 30. In the present embodiment, the heater 70 is installed in the land area outside the outer peripheral wall 32a of the convex portion 32. However, the present invention is not limited to this. Depending on the manner in which the coatings 50 and 52 are applied, The arrangement can be changed as appropriate.

Next, an example of the manufacturing method of the present invention will be described. First, a silicone-based coating 5 as an example of the coating
0 and 52, respectively, with the male projection 32 and land area 36 and the female cavity 42 and land area 4 respectively.
4 was applied by a blow molding method. Coatings 50 and 52
Has a thickness of about 0.3 mm. Next, a spray-dried powder 60 of silicon nitride (average particle size 70 μm) is filled in the cavity 42, the male mold 30 is placed on the female mold 40, and
And the surface of the silicon nitride powder 60 as the powder. At this time, the top 34 of the male mold 30 was disposed outside the processing chamber 10 via the opening 16 of the processing chamber 10.

Next, the processing chamber 10 is closed and the exhaust valve 1 is closed.
The inside of the processing chamber 10 was evacuated to about 10 Torr via the vacuum pump 2. At this time, the air mixed into the powder 60 is
2 and the wall of the female mold 40, and the protrusion 32 was fitted into the cavity 42 by the weight of the male mold 30 to press the powder 60, thereby improving the packing density. Thereafter, the exhaust valve 12 was closed, and the coatings 50 and 52 were heat-welded by the heater 70, and the powder 60 was sealed in these coatings.

Next, water was introduced into the processing chamber 10 through the water supply / drain valve 14, and the split mold 20 was immersed. During this treatment, the introduced water passed through the wall of the female mold 40, reached the cavity 42, and was immersed in the coatings 50 and 52. Then, the water is drained through the water supply / drain valve 14, released from the split mold 20, and has a height of 10 mm, an inner diameter of 100 mm, an outer diameter of 1 mm.
A ring-shaped coating holder (isotropic isostatic pressing mold) 2 having an annular shape of 50 mmφ was obtained.

FIG. 2 shows a sectional view of the obtained film holder 2. In this figure, the holding body 2 is configured such that a powder 60 is surrounded by the coatings 50 and 52. In addition,
In this embodiment, the coatings 50 and 52 are both air-permeable and water-impermeable coatings. However, it is sufficient that the coating 50 is water-impermeable and does not have to be air-permeable. It may be a coating.

The film holder 2 thus obtained is
Since the powder is filled at a high density, it has appropriate elasticity and rigidity, has a predetermined shape, and is surrounded by air-permeable and water-impermeable coatings 50 and 52.
Therefore, the film holder 2 can be suitably used as an isotropic hydrostatic pressing mold.

Next, an example of a method for producing an isotropic hydrostatically molded product obtained by using the film holder 2 will be described. The coating holder 2 was placed on an isotropic hydrostatic press, and the
/ Cm ^{2 at} a hydrostatic pressure of 30 seconds. Next, the coating films 50 and 52 were removed to obtain a high-density annular isotropic hydrostatic pressure molded product. The obtained ring-shaped isotropic isostatic pressing body was calcined in air at 500 ° C. for 1 hour to remove the binder, and then heated to 1700 ° C. at a temperature rising rate of 1000 ° C./hr in a nitrogen atmosphere. By firing at this temperature for 1 hour, an annular fired body having a height of 7.7 mm, an inner diameter of 77 mm, and an outer diameter of 115 mm was obtained.

Next, an example of a method for manufacturing a ceramic turbine rotor using the manufacturing method of the present invention will be described. FIG. 3 is a cross-sectional view illustrating an example of a mold member for manufacturing a ceramic turbine rotor. In the figure, the female member 40 ′ is an upper mold 40A having air permeability,
It is composed of a slide mold 40B and a lower mold 40C. The cavity defined by these split molds 40A, 40B and 40C is filled with silicon nitride powder 60 as described above, and this powder 60 is surrounded by silicone-based coatings 50 and 52. . The male member 30 'as described above is placed on the powder 60.

After the powder is filled as shown in FIG. 3, the powder 60 is degassed as described above, the silicone coatings 50 and 52 are joined, and a pressure medium is introduced to remove the powder 60. It was formed into a predetermined shape. Next, the slide mold 40B was slid and released from the mold to obtain a coating-holding turbine rotor having a predetermined shape (see FIG. 4). The outer diameter of the turbine rotor having the coating was 150 mmφ. As described above, this coating-bearing turbine rotor is isotropically hydrostatically pressed and fired to produce an outer diameter of 115 mm.
A ceramic turbine rotor of mmφ was obtained. This ceramic turbine rotor had a complicated shape and had no shape defects.

The present invention has been described with reference to the embodiments.
The present invention is not limited to this, and various modifications can be made within the scope of the present invention. For example, the split mold 20 may be not only a vertical type but also a horizontal type. Also,
The shape of the cavity 42 can be appropriately changed according to the intended article. Further, in the present embodiment, the silicon nitride powder was filled, but not only this, but also various powders,
Granules can also be used. Further, since these fillers only need to have air permeability, it is possible to use a porous body, for example, a foamable resin.

[0031]

As described above, according to the present invention,
A novel isotropic hydrostatic pressing mold having a resin coating, a method for manufacturing the same, and a manufacturing apparatus therefor are provided, since a pressurization is performed in a device capable of reducing pressure using a film having air permeability and impermeability to a pressure medium. be able to. Further, conventionally, complicated-shaped components such as turbine rotors have been manufactured by injection molding and casting. However, according to the present invention, isotropic, isostatic pressing provides low cost, excellent shape accuracy, and high quality large-sized components. A turbine rotor can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a manufacturing apparatus of the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a film holding body (isotropic isostatic pressing mold) of the present invention.

FIG. 3 is a sectional view showing an example of a mold member for manufacturing a ceramic turbine rotor.

FIG. 4 is a plan view of a coating-holding ceramic turbine rotor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Coating holding body (isotropic isostatic pressing mold) 10 Processing chamber 12 Exhaust valve 14 Water supply / drain valve 20 Split mold 30, 30 'Male mold 32 Convex part 36 Land area 40 Female mold 40A Upper mold 40B Slide mold 40C Lower mold 42 Cavity 44 Land area 50 Coating 52 Coating 60 Powder 70 Heater

Claims (6)

(57) [Claims] 1. A mold for use in isostatic pressing under pressure, which comprises a coating film that is permeable to air and impermeable to a pressure medium. 2. The method according to claim 1, wherein a powder is densely packed in a film that is permeable to air and impermeable to a pressure medium.
The isostatic pressing mold described. 3. An isotropic hydrostatic pressing method using the forming die according to claim 1 and filling the shape imparting portion of the forming die with powder and isostatic pressing. 4. A method for producing an isotropic hydrostatic pressing mold, wherein a powder having a predetermined shape and a high density is filled in a film permeable to a pressure medium and impermeable to a pressure medium. A mold for powder filling comprising a member and a female member having air permeability is arranged in a processing chamber having an exhaust port and a pressure medium supply / discharge port, and the coating is formed on the convex portion of the male member and Adhering to the adjacent land area, the cavity having a predetermined shape of the female member and the land area adjacent thereto, filling powder into the cavity of the female member to which the coating is applied, The convex part of the attached male member is brought into contact with the surface of the powder, and then the processing chamber is evacuated to a reduced pressure through an exhaust port, and the air contained in the powder is discharged through the female member and the coating. While removing the exhaust gas, the convex portion of the male member is fitted into the cavity of the female member, and the powder is removed. And pressurized with the convex portions of the above to improve the packing density of the powder. Then, the coatings are heated and joined by a heater provided in at least one land area of the male member and the female member. A pressure medium is introduced into the processing chamber through the pressure medium supply / discharge port to obtain an isotropic hydrostatic pressing mold filled with powder at a high density. Manufacturing method. 5. A manufacturing apparatus for an isotropic hydrostatic pressing mold, wherein a split mold comprising a male member and a female member is disposed in a processing chamber, wherein the processing chamber has an exhaust port and a pressure medium. The female member has air supply and discharge ports, the female member has a cavity having a predetermined shape filled with powder, and the male member has a convex portion fitted with the cavity. At least one of the member and the female member is provided with a coating bonding heater in a land area thereof, and the coating is air-permeable and non-permeable to a pressure medium. . 6. An isotropically isostatically pressed body obtained by isostatically pressing a mold obtained by the production method according to claim 4.