JPH09123133A - Molding method for ceramic powder and manufacture of ceramic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a manufacturing process, reduce manufacturing cost and manufacture a highly accurate member of three-dimensional curved surface in a manufacturing method for ceramics member. SOLUTION: An elastic thin-film bag 101 is inserted in a mold 13 formed into a shape and dimensions with a molding allowance considered. A space between the inner surface of the mold 13 and the thin-film bag 101 is evacuated to expand the thin-film bag 101 and make a close contact condition. Pelletized powder is charged from a formed input opening and excited by an exciter 14. After completion of charging, the input opening for the thin-film bag 101 is sealed under a reduced pressure condition, and a pelletized powder charging and sealing thin-film bag 201 is molded by a low temperature hydrostatic pressure molding machine for uniform density treatment. The bag is then shaped, burnt by a high-temperature hydrostatic pressure molding machine, and partially- polished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding ceramic powder and a method for manufacturing a ceramic member in a ceramic manufacturing process for manufacturing a member having a three-dimensional curved surface such as a turbine rotor blade or an engine valve by ceramic sintering.

[0002]

2. Description of the Related Art FIG. 11 is a schematic process showing a conventional method for manufacturing a ceramic member, FIG. 12 is a schematic process showing a method for manufacturing another conventional ceramic member, and FIG. FIG. 14 is a schematic cross section showing a method for filling granular powder, FIG. 14 is a schematic cross section showing a resin coating sealing method in a conventional ceramic powder molding method, and FIG. 15 is an appearance of an engine valve as a product example having a three-dimensional curved surface.
6 shows the appearance of a turbine rotor blade as a product example having a three-dimensional curved surface.

A method of manufacturing a ceramic member is shown in FIG.
As shown in FIG. 1, various methods are conventionally known.
That is, in the system A in which the granulated powder having the composition adjusted as the raw material powder is kneaded with the plastic medium or the fluid and then molded, the extrusion molding method (method of adding the plasticizer and extruding from the die),
Injection molding method (method of kneading thermoplastic resin and heating and extruding into a mold), slip casting method (method of injecting slurry-like granulated powder into a stone mold and absorbing and removing the medium into the mold) )and so on. On the other hand, in the B system which directly molds the granulated powder as it is, a rubber pressing method (a method of filling the rubber mold with the granulated powder and imparting water pressure), a pressure molding method (a method of pressing the upper and lower punches in the mold), etc. There is.

However, the above-mentioned various ceramic powder molding methods have their respective advantages and disadvantages. For example, in the A-system, the extrusion molding method (1) determines the product shape based on the die shape, and can only mold a product having a two-dimensional surface shape such as a round bar, a square bar, or a modified cross-section bar. And
In the injection molding method, since it is necessary to form the portion of the weir to be the injection path into the mold each time, a loss material that does not become a product is generated, and the yield of expensive ceramic raw material deteriorates. In addition, in the slip casting method, it takes a long time to absorb and dry the medium (liquid) of the slurry injected into the stone gauze mold, resulting in low productivity.

On the other hand, in the rubber press method of system B, although the rubber mold is an elastic body, the rubber thickness is large, so that the rubber pressure causes non-uniform behavior at a place with a small radius of curvature. It is difficult to apply uniform surface pressure to a product with a complicated and three-dimensional curved surface and to follow the shape. Further, in the pressure molding method, it is possible to cope with a complicated three-dimensional product shape by using a die having a complicated shape. However, in the case of a product shape whose length in the pressing direction (height) is larger than that of the cross section, Since the molded body is a powder, there is a drawback that it is difficult to achieve uniform compression and uniform density. In such a case, the dimensional change in the low density region becomes large during the firing in the subsequent process.

That is, the problems of the conventional methods for molding various ceramic powders are summarized as follows. Able to mold 3D curved products easily and at high speed. In order to maximize the yield of ceramic raw materials, it is not necessary to mold members other than the product shape (for example, weirs and inlets). No deformation during firing in the subsequent process, and uniform shrinkage,
To obtain a uniform packing density at the molding stage to obtain density, strength, etc. Be able to process a large amount in the molding process. It should be possible to obtain a molding strength that can withstand the member holding force and external processing force during machining in the next step.

Therefore, the applicant of the present invention has proposed a method of molding ceramic powder for solving the above-mentioned problems.
As shown in FIG. 12, the already proposed method for molding ceramic powder has a molding step of die press molding, resin-coated sealing, and low temperature isostatic molding. That is, in the die press molding, as shown in FIG. 13, the granulated powder 3 is retained in the die 4 by pressing the granulated powder 3 against the lower die 6 by the upper die 5. In the resin coating sealing step, as shown in FIG. 14, after the die press molding, the formed granulated powder 3 is transferred to the heating mold 11 by the work elevating mechanism 13 and heated by the heater 10. The resin melt 7 in the tank 8 is granulated by a pump 9 with a constant feeding mechanism 3 and the heating mold 1
1, and the outer surface of the granulated powder 3 is sealed with an organic resin film having elasticity, that is, a heat-melting resin to seal the entire outer surface of the member to form a resin layer 12. And
In the low temperature isostatic pressing step, although not shown, after covering the entire outer surface of the formed granulated powder with a seal, this is put in a container and subjected to low temperature isostatic pressing to perform molding.

[0008]

However, even the above-mentioned method for molding ceramic powder has the following problems. That is, the method of molding a ceramic powder proposed by the present applicant is such that the granulated powder 3 is shaped and molded in the mold press 4, and then the entire outer surface of the granulated powder 3 is covered and sealed with an organic resin, followed by low temperature isostatic molding. It is processed in the device. Therefore, although it is a mass production method that solves the above-mentioned problems (1), for example, as shown in FIG. 15, the identification mark (projection symbol ), Or, as shown in FIG. 16, when molding the convex portion of the connecting portion 2a of the turbine blade 2 by a die press, it is difficult to use the integral type in consideration of releasability from the die. Therefore, if a split mold is used, the mold design becomes complicated and expensive, and the mold precision is not sufficient. Further, when the cotter groove 1a is not formed at the time of die press molding, but is formed by a later machining process, a small amount of expensive ceramic raw material causes a loss. Furthermore, in a mass production line for engine valves and the like, it is extremely important to omit processes, make external setups, and reduce man-hours in the process from the viewpoint of drastically reducing manufacturing costs. , Resin-coated seals, low temperature isostatic molding, and many steps are required, and further reduction is required.

In short, further improvement of three-dimensional modeling property and improvement of raw material yield. Further omission of processes and reduction of man-hours. There is a demand for a method of molding a ceramic powder that achieves the above.

The present invention solves such a problem, and simplifies the manufacturing process and reduces the manufacturing cost, and at the same time, a ceramic powder capable of manufacturing a ceramic manufacturing component having a highly accurate three-dimensional curved surface. It is an object of the present invention to provide a body forming method and a ceramic member manufacturing method.

[0011]

In order to achieve the above object, a method of molding a ceramic powder according to the present invention is designed such that elasticity is preliminarily set in a molding die having a shape and a size in consideration of a molding allowance in a subsequent step. A thin film bag having the property of being inserted, the space between the inner surface of the mold and the thin film bag is decompressed to expand the thin film bag to form a charging opening, and a composition having a composition adjusted in advance from the charging opening is formed. The method is characterized in that the granular powder is charged and vibrated at the same time as it is vibrated, and the charging opening of the thin film bag is sealed under reduced pressure after the completion of the charging of the granulated powder.

[0012] Therefore, by using a mold having a shape and size in consideration of the molding allowance, a molded product having a complicated shape can be easily manufactured, and a thin film bag having elasticity is inserted into the mold. By inflating, the thin film bag can be attached closely to the mold without wrinkles, and by pouring the granulated powder into the thin film bag while vibrating, the entire thin film bag is made uniform. It can be packed at a high density, and by closing the opening of the thin film bag under reduced pressure, the thin film bag retains its shape even after being removed from the mold and does not contain foreign matter. The powder is molded.

Further, according to the method of manufacturing a ceramic member of the present invention, a thin film bag having elasticity is inserted into a molding die which is formed in advance in a shape and size taking into account a molding allowance in a subsequent step, and the inner surface of the molding die is inserted. The space between the thin film bag and the thin film bag is decompressed to form a charging opening, and a granulated powder having a composition adjusted in advance is charged and shaken from the charging opening, and the thin film is shaken. After sealing the bag charging opening under reduced pressure, the thin film bag filled with the granulated powder is subjected to a uniform density treatment by pressure molding, and then subjected to shaping machining and firing, and partial polishing finishing. It is a feature.

Therefore, a molded product having a complicated shape can be easily manufactured by using a mold having a shape and a size in consideration of the molding allowance, and a thin film bag having elasticity is inserted into the mold. By inflating, the thin film bag can be attached closely to the mold without wrinkles, and by pouring the granulated powder into the thin film bag while vibrating, the entire thin film bag is made uniform. It can be filled with high density, and by closing the charging opening of the thin film bag under reduced pressure, the thin film bag retains its shape even after being removed from the mold, and no foreign matter is mixed in, and granulated powder is filled. The formed thin film bag is pressure-molded so that the molded product is uniformly compressed and densified. By performing shaping machining, firing, and partial polishing finish, a ceramic member with high dimensional accuracy is manufactured.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an outline of a molding step representing a method for manufacturing a ceramic member according to an embodiment of the present invention.

As shown in FIG. 1, the method of manufacturing a ceramic member according to the embodiment of the present invention is as follows. Raw powder manufacturing process, B. Mixing step, C.I. Granulation process,
D. Powder molding process, E. Machining process, F.I. High temperature isostatic firing, G.I. Finish polishing, H. The inspection process comprises D. The powder forming process is performed in D1. In-mold thin film bag vacuum filling press molding step, and D2. Separated from the low temperature isostatic pressing process.

That is, A. In the raw material powder manufacturing process, various raw material powders that are the basis of the product to be manufactured are prepared and blended in a predetermined ratio. B. In the mixing step, various raw material powders mixed in a predetermined ratio are kneaded, and C.I. In the granulation step, granulated powder necessary for molding is generated.

Then, D. D in the powder molding process
1. In the press forming process of vacuum filling in a thin film bag in a mold, the molding cost when molding the granulated powder, the machining cost before firing, the shrinking cost during firing, etc., according to the shape and dimensions of the manufactured parts of the ceramic member. Prepare a split-type molding die processed into a shape and dimensions that take into consideration. In addition, a tubular thin-film bag made of rubber, vinyl, vinylidene chloride, or the like, which has excellent spreadability and airtightness, is prepared. Then, the thin film bag is inserted into the molding die, the space between the inner surface of the molding die and the thin film bag is decompressed, and the thin film bag is inflated to form the charging opening.

Then, granulation powder of ceramics whose composition has been adjusted in advance is charged into the thin film bag held in the molding die through the charging opening, and at the same time, the molding die is vibrated to produce the thin film bag in the thin film bag. Fill with granular powder. Thereafter, the gas remaining inside is sucked and removed from the charging opening of the thin film bag, and the charging opening is hermetically sealed under the reduced pressure. Then, the mold is opened and the sealed thin film bag filled with granulated powder is taken out.

Further, D2. Low temperature isostatic pressing (CIP: Co
In the ld Isostatic Pressing process, a large amount of granulated powder-filled sealed thin-film bags are put into a low temperature isostatic press and pressure-molded to homogenize and integrate the density to create a ceramic powder molded product. . After that, E. In the machining process,
The thin film bag is removed from the molded product of the ceramic powder, and the portion that becomes the extraneous portion is removed by a cutting machine to finish the size and shape close to the net shape before firing. Furthermore,
F. High temperature isostatic pressing (HIP: Hold Isostatic Pressing)
In the step, a molded product of ceramic powder is put into a high-temperature isostatic molding device, pressure-fired, and G. In the finish polishing step, the surface is polished and H. In the inspection process, the size and shape are inspected and completed.

According to the method for manufacturing a ceramic member according to the above-described embodiment of the present invention, D1. Thin-film bag in a mold In a vacuum filling press molding process, using a split-type molding die that has a shape that takes into account the molding allowance, etc. for the shape dimensions of the manufactured ceramic member parts, it is close to a net shape The size and shape can be finished, and it is easy to take out after molding. Further, by using a thin film bag having excellent spreadability and airtightness, the thin film bag can be closely adhered in the molding die and can be molded with high precision without causing wrinkles. Then, by vibrating the molding die when the ceramic granulated powder is put into the thin film bag in the molding die, the granulated powder can be packed in the thin film bag at a high density. Further, by sealing and sealing the charging opening of the thin film bag under reduced pressure, even if the thin film bag filled with the ceramic granulated powder at a high density is taken out from the molding die, the granulated powder will not be discharged due to the tension of the thin film bag. It has shape-retaining property, has sufficient durability against external force, and does not contain dust or foreign matter or absorb moisture even when left for a long period of time, ensuring quality. Also, D2. In the low-temperature hydrostatic molding process, the granulated powder-filled sealed thin film bag was subjected to low-temperature hydrostatic molding to cause cohesion and shrinkage between the granules, but the shape was retained because the external force acted evenly. Compressed in the state.

First Example A first example of the above-described embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 2 is a schematic view of a ceramic powder molding apparatus for carrying out the method for manufacturing a ceramic member according to the first embodiment of the present invention, FIG. 3 is a schematic view of a thin film bag, and FIG. 4 is a molding of ceramic powder. 5 is a schematic showing a mounting process of the thin film bag by the apparatus, FIG. 5 is a schematic showing a charging process of the granulated powder by the molding device of the ceramic powder, and FIG. In general, FIG. 7 is a schematic diagram showing a process of taking out a granulated powder-filled sealed thin film bag by a ceramic powder molding device, and FIG. 8 is a schematic diagram of a low-temperature isostatic molding device for press-molding a granulated powder-filled sealed thin film bag. 9 shows an outline of a high temperature isostatic pressing apparatus for firing a sealed thin film bag filled with granulated powder.

In this embodiment, as an example of a ceramic product having a three-dimensional curved surface, a method of manufacturing an engine valve will be described in detail. As the target valve, the finished product has an umbrella diameter of 35.0 mm, a shaft diameter of 7.5 mm, and a total length of 120 mm. And as the raw material of granulated powder,
Raw material powders such as silicon nitride (Si ₃ N ₄ ), yttria (Y ₂ O ₃ ), alumina (Al ₂ O ₃ ) are mixed at a predetermined ratio, and after solvent wax is mixed, they are distributed and kneaded to form granulated powder. Generated.

Molding apparatus 10 for ceramic powder of this embodiment
2, as shown in FIG. 2, a rotary table 1 having a diameter of 1200 mm is mounted on a base plate (not shown) by a rotary shaft 11.
2 is rotatably supported and the indexing angle is 9
It is 0 degree, and intermittent rotation is possible at four divided positions. Then, at each position, that is, four stations I, I
Various work is done in I, III, IV. In addition, in FIG. 2, in order to make the molding apparatus for the present ceramic powder easy to understand, the stations I, II, III, and IV located along the circumferential direction on the rotary table 12 are illustrated in parallel. There is. Each of the stations I, II, III, and IV is equipped with a split mold 13, and an ultrasonic vibration generator 14, an exhaust pipe 15 and a suction pump 16 are provided at the bottom of the mold to reduce the exhaust pressure. A mechanism is provided.

Since the mold 13 is functionally free from impact, it is manufactured from inexpensive carbon steel, and its surface is coated with a resin for rust prevention and lubrication.
It is a two-part type considering the removability after molding. The molding surface of the mold 13 has a shape and dimensions that take into account the molding allowance (shrinkage allowance, polishing allowance, etc.) in the subsequent process, and in this embodiment, an average of about 30 is based on the past results. % The shape and size are enlarged, but since it differs depending on the part, it is calculated backward from the completed size and set by the computer. As for the surface roughness of the mold 13, since the resin coating is applied and the thin film bag is used for molding, it is considered that the molded product is hardly affected by the surface roughness of the mold,
No polishing finish is necessary, NC lathe finish is sufficient, and the device is extremely inexpensive.

Further, the thin film bag 101, as shown in FIG.
It is formed by sealing a thin film tube 102 with a predetermined length and winding it around a roll 105 with perforations 104. In this embodiment, synthetic rubber (butadiene-stainless rubber) is used as the material of the thin film bag 101, and the thickness in the free state is 0.03 mm, the width W = 6.0 mm, and the pitch P = 1.
A 00 mm tube 102 wound around a roll 105 with a diameter of 300 mm is used.

[Station-I] This station is a step for mounting the thin film bag 101 in the mold 13.
That is, a fixed table 17 is disposed above the mold 13 which can be opened and closed to the left and right, and the above-mentioned thin film bag 101 is rotatably attached to the fixed table 17 in a roll state, and the thin film bag is also attached. A pair of supply rollers 18 for supplying 101 to the lower mold 13 is attached. Further, an upper gripping mechanism 19 and a lower gripping mechanism 20 capable of gripping the ends of the thin film bag 101 are provided above and below the mold 13.

Therefore, when the thin film bag 101 is supplied into the mold 13 by the pair of supply rollers 18, the lower gripping mechanism 2
0 grips its lower end and guides it into the mold 13, while the upper gripping mechanism 19 grips and separates the upper end of the thin film bag 101,
The mold 13 is closed and then hooked in the opening 13a.
In this state, the suction pump 16 is operated to remove the gas between the inner surface of the mold 13 and the thin film bag 101 through the exhaust pipe 15 and bring them into close contact with each other, so that the thin film bag 101 is extended and brought into close contact with the molding surface. , Is mounted in the mold 13.

[Station-II] This station is a process for charging and filling granulated powder into the thin film bag 101 mounted in the mold 13. That is, the fixed table 17 is provided above the mold 13 with the granulated powder supply tank 21 and the granulated powder supply nozzle 22 so that the granulated powder constant feeding mechanism is provided. Therefore, the thin film bag 101 mounted on the mold 13
The granulated powder supply nozzle 22 descends with respect to the granulated powder, and the granulated powder in the granulated powder supply tank 21 measured by a fixed amount is introduced from the granulated powder supply nozzle 22. At this time, the vibrator 14 should be operated. Then, the granulated powder is sized and filled without gaps.

[Station-III] This station is a process for depressurizing the thin film bag 101 filled with the granulated powder by the mold 13 to close the charging opening and seal the inside.
That is, the fixed table 17 is provided with a suction pressure reducing mechanism 24 which is located above the mold 13 and has a suction pump 23 so that the suction pressure reducing mechanism 24 can move up and down. A filter 25 made of a non-woven fabric is provided to prevent suction of the granulated powder. Around the opening 13a of the mold 13, a rubber tentacle 26 is provided which removes the upper end of the thin film bag 101 hooked on the opening 13a and hooks it on the suction nozzle 24a of the suction decompression mechanism 24. Has been. Furthermore, the ultrasonic seal welding machine 27 that closes the upper end of the thin film bag 101 close to the tentacles 26
Is provided.

Therefore, the thin film bag 101 mounted on the die 13
With the granulated powder filled in the inside, the suction pressure reducing mechanism 24 descends with respect to the mold 13, and the suction nozzle portion 24a of the suction pressure reducing mechanism 24 is brought into close contact with the opening 13a of the mold 13 By operating the decompression mechanism 24, the gas remaining in the thin film bag 101 can be sucked and removed. After that, the upper end of the thin film bag 101 hooked on the opening 13a is removed by the rubber tentacle 26 and hooked on the suction nozzle portion 24a of the suction decompression mechanism 24, and the ultrasonic seal welding machine 27
Can close and seal the upper end of the thin film bag 101.

[Station-IV] This station is a process for taking out the granulated powder-filled sealed thin film bag 201 formed by filling the thin film bag 101 with the granulated powder in the mold 13 to the outside. That is, the carry-out robot 28 is installed adjacent to the rotary table 12, and the carry-out robot 2
A gripping arm 29 capable of gripping the granulated powder-filled sealed thin film bag 201 is attached to the unit 8. Therefore, when the granulated powder-filled sealed thin film bag 201 is molded in the mold 13, the carry-out robot 2
8 is close to the rotary table 12, and the gripping arm 29 can grip the granulated powder-filled sealed thin film bag 201 and move to the next step.

As shown in FIG. 8, the low temperature isostatic molding apparatus 31 has a multi-stage arranging jig 33 set in a high-pressure container 32, and room temperature water 34 as a pressurizing medium is injected into the upper part. The upper lid 35 is attached to the above. In addition, the high pressure container 32 has an inlet 36 for injecting room temperature water 34.
The upper lid 35 is provided with an air vent valve 37 that releases the air inside.

Further, as shown in FIG. 9, in the high temperature isostatic firing apparatus 41, a heater 44 and a multi-stage array jig 45 are set in a container consisting of a base 42 and an upper lid 43, and the base 4
A shaker 46 is set inside 2, and a power source 47 is connected to the heater 44 and the shaker 46. Also, the upper lid 43
A supply pipe 48 and an exhaust pipe 49 each having a valve
The pressurizing system (not shown) is connected to the supply pipe 48, and the exhaust system is connected to the exhaust pipe 49.

Now, a method of manufacturing the above-mentioned ceramic ceramic member of this embodiment will be described. As described above, the ceramic granulated powder is produced by blending a predetermined raw material powder in a predetermined ratio, blending a solvent wax, and then distributing and kneading the granulated powder. (Granulated powder supply tank 21). On the other hand, the roll-shaped thin film bag 101 is also attached to the fixed table 17, and the supply roller 18
Can be supplied by. In this state, as shown in FIG. 2, the rotary table 11 is intermittently rotated by 90 degrees at a cycle time of about 5 seconds, and at Station-I, the work of mounting the thin film bag 101 in the mold 13, Station- Filling and filling of the granulated powder into the thin film bag 101 at II, decompression and sealing of the thin film bag 101 filled with granulated powder at Station-III, filling and sealing of the granulated powder formed at Station-IV The operation of taking out the thin film bag 201 is continuously performed.

That is, first, in station-I,
As shown in FIG. 4, the thin film bag 101 is supplied into the mold 13 in the open state by the supply roller 18, and the lower gripping mechanism 2
0 grips the lower end of the thin film bag 101 and guides it into the mold 13, while the upper gripping mechanism 19 grips the upper end and separates it. Then, after the mold 13 is closed, the upper gripping mechanism 19 moves the mold 13
The thin film bag 101 is hooked on the opening 13a of the. In this state, the suction pump 16 is operated and the mold 1 is passed through the exhaust pipe 15.
The gas between the inner surface 3 and the thin film bag 101 is removed, and the thin film bag 101 is expanded and inflated so as to be brought into close contact with the molding surface of the mold 13.

Next, in Station-II, as shown in FIG. 5, the granulated powder supply nozzle 22 is lowered to measure the fixed amount of the granulated powder in the granulated powder supply tank 21. It is thrown from 22 into the thin film bag 101 mounted on the mold 13, and at this time, by vibrating the mold 13 by the vibrator 14, the granulated powder is sized and filled without gaps.

Further, in Station-III, as shown in FIG.
As shown in FIG.
To lower the suction decompression mechanism 24 into the opening 13a of the mold 13.
The suction nozzle portion 24a of the
By operating 4 the gas remaining in the thin film bag 101 is removed by suction. After that, the upper end of the thin film bag 101 that has been hooked on the opening 13a by the tentacles 26 is replaced with the suction nozzle portion 24a of the suction pressure reducing mechanism 24, and the ultrasonic seal welding machine 27 closes and seals the upper end of the thin film bag 101. To do.

Then, in Station-IV, FIG.
As shown in, the granulated powder-filled sealed thin film bag 201 molded in the mold 13 is grasped and taken out by the grasping arm 29 of the carry-out robot 28, and conveyed to the next step.

In this way, a sealed thin film bag 201 filled with granulated powder
When a large number of are molded, these are molded into a low temperature isostatic molding device 3
1. Low temperature isostatic molding is performed. That is, as shown in FIG.
A large number of granulated powder-filled sealed thin film bags 201 are set in the multi-stage arrangement jig 33 in the high-pressure container 32, and the normal temperature water 3
While injecting 4, the inside air is discharged from the air vent valve 37 of the upper lid 35 to close it, and the inside pressure is increased to 1500 kg / cm ² .

Then, after pressure molding for a predetermined time, the granulated powder-filled sealed thin film bag 201 is taken out from the low temperature hydrostatic pressure molding device 31, and the end of the granulated powder-filled sealed thin film bag 201 is hooked by a wire or the like. Remove the thin film bag 101 and remove the ceramic powder 3
Get 01. After that, the ceramic powder 301 is removed by a cutting machine to remove the portion that becomes the extraneous material, and the size and shape close to the net shape before firing is finished.

Then, the ceramic powder 301 is subjected to high temperature isostatic firing in the high temperature isostatic firing apparatus 41. That is, as shown in FIG. 9, a large number of ceramic powders 301 are set in a multi-stage array jig 45 in a container composed of a pedestal 42 and an upper lid 43, and an inert gas is supplied from a supply pipe 48 to supply the inside. Is heated, the inside is heated by the heater 44, and firing is performed while the vibrator 46 constantly vibrates. Then, after pressure firing for a predetermined time, the ceramic powder 301 is taken out from the high temperature hydrostatic pressure firing device 41 to obtain a ceramic sintered body. Then, in the finish polishing step, the surface of the ceramic sintered body is polished to a predetermined shape and dimension, and the dimension and shape are inspected to complete the engine valve.

[Second Embodiment] FIG. 10 schematically shows a thin film bag used in a method of manufacturing a ceramic member according to a second embodiment of the present invention.

As shown in FIG. 10, the thin film bag 10 of this embodiment.
1a is a discontinuous thin film bag in which a rib 103a for reinforcement is integrally formed on the mouth portion 102a. Synthetic rubber (butadiene-stainless rubber) is applied as a material of the thin film bag 101a, and a material having a thickness in a free state of 0.08 mm, a length of 85 mm and a caliber of 4.0 mm is used.

The mold used is the same as that used in the first embodiment. Regarding the ceramic powder molding apparatus, the stations I and I described above in the ceramic powder molding apparatus 10 of the first embodiment are used.
Of I, III, and IV, only station I was changed and the other stations were used as they were. That is, in the station I of the ceramic powder molding apparatus 10 shown in FIG.
Roll-shaped thin film bag 101 attached to the fixed table 17
Instead of the pair of supply rollers 18, a thin film bag 101a shown in FIG. 10 and a small carry-in robot (not shown) that holds the thin film bag 101a and inserts it into the mold 13 are used. In addition,
The upper gripping mechanism 19 and the lower gripping mechanism 20 are used as they are for gripping the thin film bag 101a.

Therefore, when the thin film bag 101a is supplied into the mold 13 by the small carry-in robot, the lower gripping mechanism 20
While gripping the lower end of the mold and guiding it into the mold 13, the upper gripping mechanism 19 grips the rib 103a of the thin film bag 101a,
Then, the rib 103a is hooked on the opening 13a of the mold 13. In this state, the suction pump 16 is operated and the exhaust pipe 1
By removing the gas between the inner surface of the mold 13 and the thin film bag 101a through 5 and bringing them into close contact with each other, the thin film bag 101a extends and comes into close contact with the molding surface, and is mounted in the mold 13.

The processes of the other stations II, III and IV, the low temperature isostatic pressing device 31, the high temperature isostatic pressing device 41 and the like are the same as those in the above-mentioned embodiment, and the description thereof will be omitted.

[0050]

As described above in detail with reference to the embodiments of the invention, according to the method for molding a ceramic powder of the present invention, the shape and size are formed in advance in consideration of the molding allowance in the subsequent step. Insert a thin film bag with elasticity into the mold,
The space between the inner surface of the mold and the thin film bag is decompressed, and the thin film bag is expanded, and the granulated powder is charged and vibrated simultaneously from the charging opening formed. Since it is hermetically sealed under reduced pressure, it is possible to easily manufacture a molded product having a complicated shape by using a mold having a shape and size that takes into account the molding allowance, and a thin film having elasticity in this mold. By inserting the bag and inflating it, the thin film bag can be attached closely to the mold without wrinkles, and by introducing granulated powder into the thin film bag while vibrating, the thin film bag It is filled with uniform and high density over the whole area, and it is possible to obtain uniform shrinkage, density and strength without deformation in the subsequent process. By sealing the charging opening of the thin film bag under reduced pressure, this thin film bag The shape is retained even if it is removed from the mold, and foreign matter such as foreign matter is mixed in. Receiving difficult, it is possible to form the ceramic powder closer to net shape. As a result, a three-dimensional curved surface product can be easily and quickly molded with high quality, and it is not necessary to mold waste parts other than the product such as weirs and flow paths at the time of molding, which is expensive. Higher yield can be achieved by reducing the amount of ceramic raw material used.

Further, according to the method for manufacturing a ceramic member of the present invention, the thin film bag having elasticity is inserted into a molding die which is formed in advance in a shape and size taking into account the molding allowance in the subsequent step, and this molding is performed. The space between the inner surface of the mold and the thin film bag is depressurized, and the granulated powder is charged and charged from the charging opening formed by expanding the thin film bag. After sealing with, the thin film bag filled with granulated powder was subjected to a densification process by pressure molding, and after that, it was configured to perform shaping machining and firing, and partial polishing finish.
By using a mold having a shape and size that takes into account the molding allowance, a molded product of a complicated shape can be easily manufactured, and by inserting a thin film bag having elasticity into this mold and inflating it, The thin film bag can be attached closely to the molding die without wrinkles, and the granulated powder is put into the thin film bag while being vibrated, so that the entire thin film bag is filled with uniform and high density. It is possible to obtain uniform shrinkage, density and strength without deformation in the subsequent process, and by closing the charging opening of the thin film bag under reduced pressure, the shape is retained even when the thin film bag is removed from the mold. And is less susceptible to damage such as foreign matter,
It is possible to form a ceramic powder that is closer to the net shape, and by pressing a thin film bag filled with granulated powder, the molded product is uniformly compressed and densified. By performing firing and partial polishing finish, a ceramic member having high dimensional accuracy can be manufactured. As a result, a three-dimensional curved surface product can be easily and quickly molded with high quality, the amount of expensive ceramic raw material used can be reduced, and the yield can be increased, and the filling rate in the device can be increased. It is possible to improve productivity and contribute to cost reduction.

[Brief description of the drawings]

FIG. 1 is a schematic view of a forming process showing a method for manufacturing a ceramic member according to an embodiment of the present invention.

FIG. 2 is a schematic view of a ceramic powder molding apparatus for carrying out the method for manufacturing a ceramic member according to the first embodiment of the present invention.

FIG. 3 is a schematic view of a thin film bag.

FIG. 4 is a schematic diagram showing a mounting process of a thin film bag by a ceramic powder molding device.

FIG. 5 is a schematic view showing a step of charging and filling granulated powder by a ceramic powder molding device.

FIG. 6 is a schematic diagram showing a vacuum sealing process of a thin film bag by a ceramic powder molding device.

FIG. 7 is a schematic diagram showing a step of taking out a sealed thin film bag filled with granulated powder by a ceramic powder molding device.

FIG. 8 is a schematic view of a low temperature hydrostatic pressure molding apparatus for pressure molding a sealed thin film bag filled with granulated powder.

FIG. 9 is a schematic view of a high temperature isostatic pressing apparatus for firing a sealed thin film bag filled with granulated powder.

FIG. 10 is a diagram.

FIG. 11 is a schematic process diagram showing a conventional method for manufacturing a ceramic member.

FIG. 12 is a schematic process diagram showing another conventional method for manufacturing a ceramic member.

FIG. 13 is a schematic cross-sectional view showing a filling method of granulated powder in a conventional ceramic powder molding method.

FIG. 14 is a schematic cross-sectional view showing a resin sealing method in a conventional ceramic powder molding method.

FIG. 15 is an external view of an engine valve as a product example having a three-dimensional curved surface.

FIG. 16 is an external view of a turbine rotor blade as a product example having a three-dimensional curved surface.

[Explanation of symbols]

 10 Ceramic Molding Device 12 Rotary Table 13 Mold (Molding Mold) 14 Ultrasonic Shaker 15 Exhaust Pipe 16 Suction Pump 18 Supply Roller 19 Upper Gripping Mechanism 20 Lower Gripping Mechanism 21 Granulated Powder Supply Tank 23 Suction Pump 24 Suction Decompression Mechanism 27 Ultrasonic Seal Welding Machine 28 Carrying Out Robot 31 Low Temperature Hydrostatic Pressure Molding Equipment 41 High Temperature Hydrostatic Pressure Molding Equipment 101 Thin Film Bag 201 Granulated Powder Filled Sealed Thin Film Bag 301 Ceramic Powder

Claims (2)

[Claims] 1. A thin film bag having elasticity is inserted into a molding die which is formed in a shape and size in consideration of a molding allowance in a later step, and the space between the inner surface of the molding die and the thin film bag is depressurized. To form a charging opening by inflating the thin film bag, and simultaneously charging and charging granulated powder having a composition adjusted in advance through the charging opening, and after the completion of charging the granulated powder, A method for molding ceramic powder, characterized in that the charging opening is sealed under reduced pressure. 2. A thin film bag having elasticity is inserted into a molding die which is formed in a shape and size in consideration of a molding allowance in a later step, and the space between the inner surface of the molding die and the thin film bag is depressurized. The thin film bag is inflated to form a charging opening, and the granulated powder having the composition adjusted in advance is charged and vibrated at the same time from the charging opening, and the charging opening of the thin film bag is sealed under reduced pressure. After that, the thin film bag filled with the granulated powder is subjected to a densification treatment by pressure molding, and thereafter, shaping machining and firing,
A method for manufacturing a ceramic member, which comprises partially polishing and finishing.