JP2004114139A - Jig for cold hydrostatic pressing, and manufacturing method of molding using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jig for cold hydrostatic press capable of obtaining a molding having a plurality of through holes with wholly uniform powder density. <P>SOLUTION: The jig 10 for cold hydrostatic press comprises an tubular elastic frame 17 surrounding a formed substance, a lower lid 16 and an upper lid 15 for sealing the upper and lower opening parts of the elastic frame 17, a plurality of core metals 11a, 11b arranged in the elastic frame 17, and elastic members 13, 14 are attached to the each inside area of the lower lid 16 and the upper lid 15 and both edge parts of each metal core 11a, 11b are fixed to the elastic members 13, 14. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold isostatic pressing jig for pressing a molding powder made of ceramics, metal, or a composite material thereof using hydrostatic pressure. In particular, the present invention relates to a cold isostatic pressing jig capable of obtaining a molded body having a plurality of parallel through holes and a method of manufacturing the molded body.
[0002]
[Prior art]
A molded body of ceramics or the like is generally molded by a die press method, a cold isostatic molding method (generally, also referred to as a rubber press or a CIP molding), an injection molding method, a cast molding method, or the like. When manufacturing a ceramic having a through-hole in a molded body, forming a hole by post-processing such as cutting leads to an increase in man-hours, and it is difficult to form a hole depending on a material, or an expensive material is used. In some cases, material loss causes the price of the product to rise.
[0003]
Therefore, it is desirable to form such a through hole at the stage of molding as much as possible. In this case, a method is used in which a rod-shaped core is placed in a cavity of a mold, molded, and then the core is removed to form a through-hole in a molded body.
[0004]
In recent years, products made of ceramics and the like have been used in liquid crystal and semiconductor manufacturing apparatuses and have become larger, and in order to reduce the weight thereof, it has been required to form a plurality of through holes.
[0005]
However, in the case of forming a plurality of through-holes, for a large-sized one, the molding method using a die press or an injection molding method requires a large-scale apparatus, and there is a restriction on equipment because it becomes an expensive apparatus. It was difficult to obtain a large powder compact.
[0006]
Further, cold isostatic pressing devices as disclosed in Patent Documents 1 to 5 have been proposed, but all of these devices only form a single through-hole, and a plurality of through-holes having a uniform density are used. It does not suggest a molded article having the same.
[Patent Document 1] Japanese Patent Application Laid-Open No. 10-85994 [Patent Document 2] Japanese Patent Application Laid-Open No. 10-249826 [Patent Document 3] Japanese Patent Application Laid-Open No. 10-80910 [Patent Document 4] Japanese Patent Application Laid-Open No. 2-207997 [Patent] Document 5: Japanese Patent Application Laid-Open No. 9-24496 [Problems to be Solved by the Invention]
In the cold isostatic pressing method, it is easy to form a large product, and it is possible to ideally obtain a powder compact having a uniform pressure.However, when forming a plurality of through holes, a general single Similar to the formation of the through hole, as shown in FIG. 3, a cylindrical elastic frame 37 surrounding the powder 40 to be molded, and the upper and lower openings of the elastic frame 37 are closed by the lower lid 36 and the upper lid 35. It was considered that molding was possible by sealing and fixing a plurality of cores 31a and 31b to the lower lid 36 and the upper lid 35 in the elastic frame 37. Between the core 31a and the core 31b, the pressure propagation required for molding was hindered by the cores 31a and 31b themselves, and only a molded body having a non-uniform green density at the center was obtained.
[0007]
In particular, as the number of the metal cores 31 increases, the pressure propagation is hindered by the metal cores 31, and the central portion is a green compact powder body with poor clogging.
[0008]
In the cold isostatic pressing method, pressure acts from any direction, and the cold isostatic pressing jig 30 is contracted as a whole. Therefore, the jig 30 for cold isostatic pressing also contracts in the axial direction of the metal cores 31a, 31b, and the metal cores 31a, 31b and the upper lid 35, the lower lid 36 are pressed against each other, and the molded body can be taken out without moving. Sometimes disappeared.
[0009]
Therefore, as a method for obtaining the shape of the plurality of through holes, a casting method in which powder is made into a swamp and poured into a gypsum mold or a wooden mold has been mainly used.
[0010]
However, this casting method has a problem that a plaster mold or a wooden mold is required, and it is difficult and expensive to produce the mold. In addition, it is necessary to make the ceramic muddy, pour it into a mold, dry the molded body, remove the outer frame, and remove the core, but the timing of drying and release is difficult, and if it is pulled out lately, cracks will occur due to shrinkage of the molded body. In many cases, the problem is that if the material is quickly removed, the molded product is soft and cannot be kept in shape, and a molded product having a required shape cannot be obtained. In addition, when performing cast molding, it requires skill to dry the molded body, and furthermore, there is a problem that the tool has a limited lengthwise direction to perform the blanking in the processing, and also, the molded body of the cast molding is difficult. Then, there was a problem that a cavity called a nest therein or a foreign substance was mixed therein.
[0011]
Therefore, in order to obtain a large-sized molded body having a shape of a plurality of through holes, it has been general to form a hole in the molded body formed by the cold isostatic pressing method by cutting. However, as described above, an increase in man-hours and an increase in the price of a product due to a loss of a material have become problems, and a method of obtaining a large-sized powder compact having a plurality of hole shapes has been desired.
[0012]
[Means for Solving the Problems]
In view of the above problem, the present invention has a tubular elastic frame surrounding a molded object, a lower lid and an upper lid for sealing upper and lower openings of the elastic frame, and are disposed in the elastic frame. A jig for cold isostatic pressing comprising a plurality of metal cores, wherein an elastic member is brought into contact with each inner surface region of the lower lid and the upper lid, and both ends of each of the metal cores are fixed to the elastic member. It is characterized by doing.
[0013]
Further, the present invention is characterized in that the material of the elastic member has a Shore hardness in a range of 30 ° to 80 °.
[0014]
Further, an axial movement of the cored bar is suppressed by an outer frame which is arranged on an outer periphery of the elastic frame and has a plurality of holes fixed to both the upper and lower lids.
[0015]
Then, the cold isostatic pressing jig filled with powder is inserted into a water tank to which hydrostatic pressure can be applied, and pressurization is performed by applying hydraulic pressure to the cold isostatic pressing jig. -It is characterized in that a compact is obtained by performing compression.
[0016]
[Action]
During molding with a cold isostatic pressing device, a plurality of cores are subjected to pressure toward the center with the compression of the elastic frame pressed from the outer periphery, but the cores are in the inner surface area of the upper and lower lids. Is fixed to the elastic member that abuts the plurality of metal cores, the plurality of metal cores move while the elastic members between the metal cores also contract with the movement of the metal cores. As a result, a sufficient pressure is transmitted to the powder in the portion between the metal cores, and a compact having a uniform powder density as a whole can be obtained.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a schematic sectional view showing an example of a jig for cold isostatic pressing according to the present invention.
FIG. 2 shows a cold isostatic pressing apparatus for forming using a generally used hydrostatic pressure.
[0018]
The cold isostatic pressing jig 10 of the present invention includes a cylindrical elastic frame 17 surrounding the powder 20 to be molded, an upper lid 15 for sealing the upper and lower openings in the elastic frame 17, and a lower lid 15. A cover 16, rod-shaped metal cores 11 a and 11 b disposed in the elastic body frame 17 in parallel with the cylindrical side surface thereof, and elastic members 13 and 14 abutting on respective inner surface regions of the lower lid 16 and the upper lid 15. That is, both ends of each of the metal cores 11 a and 11 b are fixed to the elastic members 13 and 14.
[0019]
When being molded by the cold isostatic pressing apparatus of the present invention, the plurality of metal cores 11a and 11b receive pressure toward the center as the elastic frame 17 is pressed from the outer periphery. Since the metal cores 11a and 11b are fixed to the elastic members 13 and 14 abutting on the inner surface regions of the upper and lower lids 15 and 16, the plural metal cores 11a and 11b move. Thereby, sufficient pressure is propagated also to the powder 20 in the portion between the cored bars 11a and 11b, and it is possible to obtain a molded body having a uniform powder density as a whole.
[0020]
The metal cores 11a and 11b are for forming through holes in the molded body. Therefore, a metal material such as stainless steel, steel material, or super hard, which easily forms a through hole, is used. The length of the metal material is the same as that of the upper lid 15 and the lower lid 16 or slightly. It is desirable that the distance is slightly larger. By slightly increasing the length of the same length or the distance between the upper and lower lids 15 and 16, the cores 11 a and 11 b have a degree of freedom, and when contracted by pressure, the cores 11 a and 11 b are elastically smooth. It is possible to move in the direction of the central axis of the body frame 17. Further, a support portion 110 having a smaller diameter than the other diameters is formed at the ends of the cored bars 11a and 11b.
[0021]
As a structure for fixing the cores 11a and 11b to the elastic members 13 and 14, the end faces of the support portions 110 at both ends of the cores 11a and 11b penetrating the elastic members 13 and 14 as shown in FIG. , 16 or a structure having a slight gap is preferable. This is because the elastic members 13 and 14 are prevented from expanding inward in the longitudinal direction during contraction. However, even if the support portions 110 of the elastic members 13 and 14 do not penetrate, a counterbore-shaped hole is formed, and the core bars 11a and 11b can be used.
[0022]
Further, if the surfaces of the cores 11a and 11b are plated or coated with a hard thin film, it is possible to improve the slipperiness with the powder 20 and the releasability, and further improve the cores 11a and 11b. Rust can be prevented. Specific examples include hard chrome plating, TiN coating, TiC coating, DLC coating, and the like. The end faces of the metal cores 11a and 11b can be used without any problem even if they have a straight shape, a tapered shape, or a stepped shape.
[0023]
The upper and lower lids 15 and 16 may be made of metal, and may be made of metal such as stainless steel or steel.
[0024]
Further, a powder inlet 19 and an air vent 21 are formed in the upper elastic member 13, and the upper and lower elastic members 13 and 14 are sealed and closed by the elastic frame 17. When the powder 20 is supplied, the air escapes from the air vent 21 so that the powder 20 can be smoothly and uniformly filled.
[0025]
Also, the material of the elastic members 13 and 14 needs to have a Shore hardness in the range of 30 ° to 80 °, and if it is less than 30 °, the core metals 11a and 11b cannot be supported. The pitch accuracy between the metal cores 11a and 11b cannot be maintained. On the other hand, if it exceeds 80 °, the resilience and shrinkage deteriorate, and a uniform molded body cannot be obtained. Therefore, the hardness of the material of the elastic members 13 and 14 needs to be in the range of 30 ° to 80 ° in Shore hardness, and preferably in the range of 50 ° to 70 °.
[0026]
By the way, the method for measuring the Shore hardness may be a method specified by JIS A or a method measured according to the method.
[0027]
Any material that satisfies these materials may be used as long as it is soft, excellent in shrinkage, and water resistance. Rubber is good.
[0028]
Further, in the cold isostatic pressing jig of the present invention, outer frames 18a and 18b having a plurality of holes formed for applying water pressure are formed on the outer periphery of the elastic frame 17, and the upper and lower lids 15, 16 are fixed to both sides. Therefore, the outer frames 18a and 18b not only make it possible to suppress the axial movement of the metal cores 11a and 11b, but also to form an elastic frame even when molding a small-diameter or long one. Since no pressure is applied in the direction of the central axis of 17, the molded body can be molded without bending.
[0029]
The outer frames 18a and 18b can be divided into a plurality of parts. For example, the outer frames 18a and 18b include a cylindrical outer frame 18a having a shorter length than the elastic body frame 17 and a cylindrical outer frame 18b having the remaining length. Although not shown, the outer frame 18b is shaped to be half.
[0030]
The outer frame 18a is in contact with the flange of the lower lid 16, and a half of the outer frame 18b is arranged on the upper part of the outer frame 18a. It is fixed.
[0031]
By the way, the material of the outer frames 18a and 18b may be a material that can withstand high pressure, and may be a steel material, stainless steel, or the like because it can be obtained and processed at low cost.
[0032]
As shown in FIG. 2, the cold isostatic pressing apparatus 21 places a workpiece in a pressure chamber 23 in a cylindrical pressure vessel 22, covers the pressure vessel 22 with a lid 25, and seals it. This is a device for injecting a high-pressure liquid 24 such as water into the sealed pressure chamber 23 and pressurizing the workpiece, and a generally known device can be used.
[0033]
For the method of molding using the cold isostatic pressing jig 10 of the present invention, the cold isostatic pressing jig 10 filled with powder is inserted into a pressure chamber 23 to which a hydrostatic pressure can be applied. , Filled with a high-pressure liquid 24, covered with a lid 25, and sealed. Then, the liquid pressure of 60 to 200 MPa is gradually increased indirectly through the cold isostatic pressing jig 10, and the liquid pressure is applied to perform pressurization and compression to obtain a molded body.
[0034]
【Example】
(Experiment 1)
Using the cold isostatic pressing jig of the present invention shown in FIG. 1 and the conventional cold isostatic pressing jig shown in FIG. 3, a cold isostatic pressing apparatus is used to form two through holes. An experiment was performed to form a molded body.
[0035]
As shown in FIG. 1, the cold isostatic pressing jig 10 seals a cylindrical elastic frame 17 surrounding a powder 20 to be molded, and upper and lower openings in the elastic frame 17. An upper cover 15 and a lower cover 16, bar-shaped cores 11 a and 11 b arranged in the elastic body frame 17 in parallel with the cylindrical side surfaces thereof, and an elastic member 13 in contact with each inner surface region of the lower cover 16 and the upper cover 15. , 14 having both ends fixed to the elastic members 13, 14, respectively. The elastic frame 17 has outer frames 18 a, 18 b on the outer periphery thereof. At this time, the Shore hardness of the elastic members 13 and 14 was set to 60 °.
[0036]
As shown in FIG. 3, the cold isostatic pressing jig 30 includes a cylindrical elastic frame 37 surrounding an object to be molded, an upper lid 35 and a lower lid 36 for sealing upper and lower openings, and a plurality of metal cores. What consisted of 31a and 31b was prepared.
[0037]
The powder was 99.5% purity alumina powder containing a binder, and a powder having a compression ratio of 1.2 when a single through hole was formed was used.
[0038]
The formed body was formed to have a diameter of 200 mm and a length of 300 mm so that holes of 40 mm were opened at a pitch of 100 mm.
[0039]
As a result, the molded body molded using the jig for cold isostatic pressing of the present invention was a molded body having a constant green density, while using the conventional jig for cold isostatic pressing. In the molded article, the core metal was bent and the core metal did not come off, and a molded article could not be obtained.
[0040]
Furthermore, when sintering was performed at 1700 ° C., the compact formed by the jig for cold isostatic pressing of the present invention had a desired shrinkage ratio between hole pitches and hole diameters and outer diameters of 0.83 to 0.82. It could be fired without any problems.
(Experiment 2)
Next, an experiment was conducted on the elastic members having different Shore hardnesses of 20 °, 30 °, 50 °, 60 °, 70 °, 80 °, and 90 °.
[0041]
As a result, it becomes difficult to fix the core metal sufficiently at 20 °, and it tends to be difficult to keep the distance between the core metals.
In the case of 90 °, the shrinkage tended to decrease, and the central portion tended to be non-uniform as compared with 30 ° to 80 °. With respect to those having an angle of 30 ° to 80 °, a molded article having a uniform green density as a whole could be obtained. In particular, those in the range of 50 ° to 70 ° showed almost no variation in green density, and when cut into a desired shape as it was and fired, a molded product showing good shrinkage was good.
[0042]
【The invention's effect】
As described above, according to the present invention, a tubular elastic frame surrounding a molded object, a lower lid and an upper lid that seal upper and lower openings of the elastic frame, and are disposed in the elastic frame. A jig for cold isostatic pressing comprising a plurality of metal cores, wherein an elastic member is brought into contact with each inner surface region of the lower lid and the upper lid, and both ends of each of the metal cores are brought into contact with the elastic member. Since it is characterized by being fixed, when molding with a cold isostatic pressing device, with the compression of the elastic body frame pressed from the outer periphery, a plurality of cores receive pressure toward the center, Since the mandrel is fixed to the elastic member in contact with the inner surface area of the upper and lower lids, a plurality of mandrel moves. As a result, a sufficient pressure is transmitted to the powder in the portion between the metal cores, and a compact having a uniform powder density as a whole can be obtained.
[0043]
Further, according to the present invention, the material of the elastic member has a Shore hardness in the range of 30 ° to 80 °, so that the propagation of the molding pressure can be further improved, and furthermore, the uniformity can be further improved. A compact having a powder density can be obtained.
[0044]
Further, the outer frame having a plurality of holes fixed to both the upper and lower lids, which is arranged on the outer periphery of the elastic frame, suppresses the axial movement of the cored bar, thereby reducing the diameter or the length of the cored bar. It is possible to mold even a molded body, and it is possible to obtain a molded body that is not bent.
[0045]
Then, the cold isostatic pressing jig filled with powder is inserted into a water tank to which hydrostatic pressure can be applied, and pressurization is performed by applying hydraulic pressure to the cold isostatic pressing jig. -The compact obtained by compression can form a compact having a plurality of through-holes having a uniform powder density.
[0046]
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of a jig for cold isostatic pressing according to the present invention.
FIG. 2 is a schematic sectional view showing an example of a cold isostatic pressing apparatus.
FIG. 3 is a schematic sectional view showing an example of a conventional jig for cold isostatic pressing.
[Explanation of symbols]
10, 30 ... jig for cold isostatic pressing 11, 31 ... core metal 13 ... upper elastic body 14 ... lower elastic body 15, 35 ... upper lid 16, 36 ... lower lid 17 ... elastic body frame 18 ... outer frame 19 ... Powder inlets 20, 40 Powder 21 Air vent 22 Pressure vessel 23 Pressure chamber 24 High-pressure liquid 25 Lid

Claims (4)

A cold static frame comprising a cylindrical elastic frame surrounding a molded object, a lower lid and an upper lid for sealing the upper and lower openings of the elastic frame, and a plurality of metal cores arranged in the elastic frame. A hydrostatic jig, wherein an elastic member is brought into contact with each inner surface region of the lower lid and the upper lid, and both ends of each of the cored bars are fixed to the elastic member. Molding jig. The jig for cold isostatic pressing according to claim 1, wherein the material of the elastic member has a Shore hardness in a range of 30 ° to 80 °. The axial movement of the metal core is suppressed by an outer frame having a plurality of holes fixed to both of the upper and lower lids and arranged on an outer periphery of the elastic body frame. 3. The jig for cold isostatic pressing according to 2. 4. The cold isostatic pressing jig according to claim 1, wherein the jig for cold isostatic pressing is filled with a powder in a water tank capable of applying hydrostatic pressure. A method for producing a molded article, characterized in that a molded article is obtained by applying pressure and compression by applying a liquid pressure to a tool.

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