JPS6340845B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high temperature rubber press method for pressure sintering of powder materials, removal of internal defects in cast and sintered products, diffusion bonding, etc.

BACKGROUND ART A hot isostatic pressing method is known as a pressurizing method for pressure sintering of powder materials, removal of internal defects in cast and sintered products, diffusion bonding, and the like.

Currently, in the hot isostatic processing method used industrially, inert gases such as argon and nitrogen, or air are used as pressure media.
It compresses the object to be processed at a high temperature of several hundred to 2,000 degrees Celsius under gas pressure reaching 1,000 to 2,000 Kgf/ ^cm2 , and because it uses gas pressure, the object to be processed is large or irregularly shaped. Regardless of the size, it is compressed uniformly to the inside, and combined with the high temperature, it is extremely effective for true densification.

By the way, in this pressurization method, pressurization, depressurization, heating with a heater installed inside the high-pressure container, and temperature lowering are performed, and the object to be processed is removed after completely recovering the gas pressure medium from the high-pressure container. The cycle time is long, e.g. 7~1 cycle.
It took 8 hours, and productivity was extremely low.

In order to shorten the cycle time, attempts have been made to heat and lower the temperature of the object to be processed outside the high-pressure container, and only pressurize, depressurize, and raise the temperature of the supplied gas pressure medium in the high-pressure container.

However, this still reduces the cycle time to about 1
It takes about time.

Therefore, it is recommended to increase the capacity of the compressor for gas pressure medium or increase the number of compressors.

However, in reality, commercially available high-pressure compressors have a limited capacity, and it is not rational to increase the number of compressors to an extreme in terms of balance with the main equipment.

In order to dramatically shorten cycle time and increase productivity, there is a method in which powder is used as a pressure medium, the powder pressure medium is pressurized by normal press compression, and the object to be processed is pressurized through the powder. This is proposed in Publication No. 55-120499.

In this conventional example, the object to be processed is heated in advance in a preheating furnace, but due to friction between the powder and friction between the high-pressure container and the powder, an imbalance in pressure distribution occurs in the pressure medium, causing the object to be processed to be heated evenly. It is difficult to pressurize and compress unidirectionally.

Therefore, the present invention aims to shorten the cycle time and uniformly pressurize the object to be processed, despite using a normal dry rubber press that uses powder as a pressure medium and a rubber mold placed on the inner surface of a high-pressure container. Therefore, in the present invention, a rubber mold is arranged on the inner surface of a high-pressure container, and a liquid pressure medium is supplied between the high-pressure container and the rubber mold to compress the material inside the rubber mold. This is the so-called rubber press method in which the object to be treated is isotropically pressurized. Supplying a powder pressure medium into the rubber mold, then taking out the pot-shaped object outside the rubber mold, and then, with the high pressure container sealed,
It is characterized in that a liquid pressure medium is supplied between the high-pressure container and the rubber mold, and the object to be processed is isotropically pressurized via the rubber mold and the powder pressure medium.

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

FIG. 1 shows a so-called dry rubber press used directly in the present invention, during pressurization and compression. In the figure, reference numeral 1 denotes a press frame within which a rectangular space is formed.

The press frame 1 is pivotable about a vertical axis by a hinge structure (not shown), and the high-pressure container 2 can be relatively freely moved in and out of the space of the press frame 1 through this pivoting motion.

The high-pressure container 2 has a cylindrical shape, and a top closer 3 is attached to its top side, and a bottom closer 4 is attached to its bottom side.
1B, respectively.

The top closer 3 consists of a cylindrical outer plug 6 that is inserted into the high-pressure vessel 2 and fastened with bolts 5, and an inner plug 7 that is removably inserted into and supported by the outer plug 6.

The bottom closer 4 consists of a cylindrical outer plug 9 that is inserted into the high-pressure container 2 and fastened with bolts 8, and an inner plug 10 that is removably inserted into and supported by the plug 9.

A cylindrical support 11 is provided on the inner peripheral surface of the high pressure container 2.
is inserted and fitted, and the upper and lower peripheral edges of the support 11 are respectively fixed to the inner surface of the container by welding in this example, and the support 11 has a large number of through holes 12 opened in the radial direction.

A thick rubber mold 14 is provided around the inner peripheral surface of the support 11 via a thin rubber mold 13, and the rubber molds 13 and 14 are arranged on the inner surface of the high-pressure container 2 here.

Furthermore, an inlet/outlet 15 for a pressure medium made of liquid is formed in the high-pressure container 2, and in this example, it is formed in the lower peripheral wall of the container 2 and communicates with each of the through holes 12 via a radial passage 16. .

Furthermore, in FIG. 1, reference numeral 17 denotes an object to be treated, and the inner plug 10 of the bottom closer 4 is inserted into the pressurized chamber via a support 18 made of alumina or the like.
is placed on top.

In addition, in FIG. 1, 19 is alumina powder,
A pressure medium made of BN powder etc., 20 is a rubber plate,
It is attached to the inner plug 7 of the top closer 3.

Accordingly, in the present invention, the object to be processed 17 is heated to 100
℃ and then inserted into the inside of the rubber molds 13 and 14. At that time, from the viewpoint of preventing thermal burnout of the rubber molds 13 and 14, the tip-shaped object 21 made of a heat insulating material shown in FIG. Therefore, it is inserted inside the rubber molds 13 and 14 of the high-pressure container 2 while surrounding the object 17 to be processed.

That is, in this embodiment, the object to be processed 17, which has been heated externally in advance, is surrounded on the inner plug 10 of the bottom closer 3 by the tip-shaped object 21 having the engaging part 21A at the center of the top, and in this state, the object 17 is heated under high pressure. The lower end of the pulling rod 22, which is inserted from below the container 2 and is movable up and down after insertion, is connected to the engaging portion 21A.

As another embodiment, the tip-shaped object 21 with the pulling rod 22 is kept on standby within the high-pressure container 2, or it is made to protrude downward, and when it is kept on standby, the inner plug on which the object to be processed 17 is placed is 10 is inserted into the high-pressure container 2 from below, and the object to be processed 17 is inserted into the standby pot-shaped object 21 and surrounded by the object 21.

When the tip-shaped object 21 is projected downward, the object 17 to be processed is inserted into the object 21, and the tip-shaped object 21 and the inner plug 10 are raised in synchronization and inserted into the high-pressure container 2.

In any of the embodiments, in short, the object to be processed 17 in the high-pressure container 2 is surrounded by a pot-like object 21 made of a heat insulating material.

However, the illustrated embodiment is more compact in the height direction (due to the lifting rod).
can be constructed, and handling is also advantageous.

The object to be processed 1 is placed inside the high-pressure container 2 with a pot-shaped object 21.
7 is surrounded, a pressure medium 19 of powder such as alumina or BN is supplied into the high-pressure container 2 from the powder feeder 23 shown in FIG.

During this process, the rubber molds 13 and 14 are kept from heating by a pot-shaped object 21 made of a heat insulating material.

After the supply of pressure medium 19 has progressed to a certain extent, the tip-shaped object 21 is removed via the lifting rod 22.
When the powder is gradually pulled up, the pressure medium 19 is filled from the bottom, and if the powder supply is continued, the pressure medium 19 is filled as shown in FIG.

In this process, the object to be processed 17 is a tip-shaped object 21.
Or heated and cooled with pressure medium 19, rubber mold 1
3 and 14 are not exposed to the heat of the object to be processed 17.

In particular, when alumina is used as the pressure medium 19, the heat insulation effect is great.

Note that when the pressure medium 19 is insufficient,
It is replenished by the feeder 23.

After filling the pressure medium 19 and taking out the top-shaped objects 22 from the rubber molds 13 and 14, the inner plug 7 of the top closer 3 is inserted and the upper and lower inner end surfaces 1A of the press frame 1 are placed above and below the high-pressure container 2, The high-pressure container 2 is brought into a sealed state so that the high-pressure container 1B is connected and supported (see FIG. 1).

In this state, when a liquid pressure medium is introduced from the inlet/outlet 15 and supplied to the through hole 12, the rubber molds 13, 14
As a result, the pressure medium 19 is compressed, and the object to be processed 17 is isotropically pressurized via the rubber molds 13, 14 and the powder pressure medium 19.

After pressure molding, the liquid pressure medium is decompressed and discharged to the outside of the container 2 through the inlet/outlet 15.
The rubber molds 13 and 14 are restored to the inner wall side of the high pressure vessel 2 by their elastic restoring force, while the pressure medium 19
is in a pressure-molded state, and a gap is created between the pressure-molded product 19A and the rubber mold 14, as shown in FIG. 4, for example.

Therefore, after pivoting the press frame 1,
As shown in FIG. 4, the product 17A together with the powder molded product 19A is extracted from the container 2 through the inner plug 10 of the bottom closer 4, and thereafter, the molded product 1
After the 9A is removed, crushed, transported, discharged, etc., handling is carried out.

In addition, if the processing pressure with a liquid pressure medium is low or if a powder pressure medium 19 that is difficult to mold is used, remove the inner plug 7 in the top closer 3 and lower the tip-shaped object 21 as shown in FIG. When the inner plug 10 of the bottom closer 4 is lowered, the pressure medium 19 flows down and is collected separately as shown in the figure, and in this case as well, the rubber molds 13 and 14 are
7 will not be exposed to heat.

Further, the object to be treated 17 is optimally made of low-grade steel, but any material that can be subjected to hot isostatic pressing using a gas pressure medium can be applied.

For example, it is possible to perform pressure sintering of metal and ceramic powder materials, and to remove internal defects from cast and sintered products.

Radioactive metal waste and radioactive ceramic waste (bricks, concrete, incineration ash, ceramic filters, etc.) are also subject to this regulation.

Powdered materials and radioactive waste are processed by filling them into capsules and sealing them.

Next, examples will be given.

Approximately 80 micron powder of high speed steel, inner diameter 60 mm, height
It was filled into a 120 mm x 1 mm thick mild steel capsule by tapping. The filling rate is about 60%.

To this, a lid having a degassing pipe with an inner diameter of 10 mm and a length of 500 mm was TIG welded.

Next, connect the degassing tube to a vacuum device and heat it to about 300℃.
While heating the capsule, the inside of the capsule is vacuum degassed to 10 ^-1 TOrr through a degassing tube for about 1 hour, and in that state, the degassing tube is heated with a gas burner and pressed together.
The capsule was sealed.

The sealed capsule produced in this way,
It was placed in an Elema furnace heated at 1100°C and heated for 2 hours.

Capsule (object to be processed) taken out from the Elema furnace
is surrounded by a pot-shaped object made of heat insulating material with glass wool placed between 1 mm thick mild steel plates, with an inner diameter of 200 mm.
The material was placed in a high-pressure container of 1.0 mm in diameter, and a pressure medium made of alumina powder was immediately filled between the rubber mold and the pot-like object.

After filling with the pressure medium, the pot-shaped object was pulled out and the high-pressure container was replenished with powder pressure medium until it was full, and then the high-pressure container was sealed.

Then, the object to be processed was pressurized at 200 MPa for 5 minutes, and then the object was depressurized and taken out from the container.

Note that the pressure is applied after the object to be processed is loaded into the press.
It took about 2 minutes to reach 200 MPa, and about 2 minutes to take out the treated body (product) after starting the pressure reduction.

That is, the time the object to be processed stayed in the rubber press was about 10 minutes.

The processing body was thermally protected by a temporary sintered body of alumina powder, which was a pressure medium, and the rubber-shaped protective tip was not needed after it was taken out.

As a result of measuring the density of the treated body, it was found that the high speed steel was sufficiently densified and had true density.

The present invention is as described above, and the pressure medium is a solid,
That is, since powder or pellets are used, cycle time can be extremely shortened and productivity can be improved.
Incidentally, compared to the gas pressure medium, which requires a long gas compression and recovery time, the present invention, which uses a powder pressure medium, is advantageous.

The object to be processed can be compressed isotropically to achieve true density. Incidentally, when uniaxially compressing a solid powder pressure medium, an imbalance in pressure distribution always occurs, but in the present invention, in which the powder pressure medium is supplied into a rubber mold and pressurized, isotropic compression is possible.

Although a rubber mold is used, heat damage to the rubber mold can be prevented because a powder pressure medium is used and the object to be processed is surrounded by a pot-like object made of a heat insulating material.

Complete sealing of the object to be processed (capsule) is not required. Incidentally, in the case of a gas pressure medium, complete sealing of the capsule is essential, but this is not a problem in the present invention, which uses a powder pressure medium.

Furthermore, it is possible to process even slender objects, and since the powder pressure medium can be crushed and reused, it can be used repeatedly. By the way, methods using castor oil, grease, etc.
The pressure medium deteriorates over time.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a dry rubber press used directly in the present invention, showing it during pressurization, Figure 2 is a cross-sectional view of the powder press being supplied to a high-pressure container, and Figure 3 is a cross-sectional view of the dry rubber press being supplied. A cross-sectional view of a heat-insulating tip-shaped object being pulled out,
FIG. 4 is a sectional view after treatment, and FIG. 5 is a sectional view showing an example of recovery when the pressure medium is not formed. 1...Press frame, 2...High pressure container, 3...
...Top closer, 4...Bottom closer, 1
3, 14...Rubber mold, 15...Liquid pressure medium inlet/outlet,
17...Object to be processed, 19...Pressure medium, 21...
A spiky object.

Claims (1)

[Claims] 1 A so-called rubber press method in which a rubber mold is placed on the inner surface of a high-pressure container, and a liquid pressure medium is supplied between the high-pressure container and the rubber mold to isotropically pressurize the object to be processed inside the rubber mold. The object to be processed, which has been previously heated externally, is surrounded by a pot-like object made of a heat insulating material in a high-pressure container, and a powder pressure medium is supplied into the rubber mold while the object is surrounded, and then, The tip-shaped object is taken out of the rubber mold, and then, with the high-pressure container sealed, a liquid pressure medium is supplied between the high-pressure container and the rubber mold, and the object to be processed is filled with the rubber mold and powder pressure medium. A high-temperature rubber press method characterized by applying pressure isotropically.