JPH0138238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressurizing device for a hot press that uses a high-temperature, high-pressure gas as an internal atmosphere gas.

In recent years, ceramics and fine ceramics have been in the spotlight as various mechanical materials or electrical and electronic materials. After being formed by various forming methods such as molding, it is sintered to increase its strength.

This sintering method includes an atmospheric pressure molding method, but the hot pressing method is widely used depending on the material in order to obtain a sintered body that is sufficiently dense and has a density close to the theoretical density.

Ceramics to date generally have relatively low vapor pressure even at their melting point, with the exception of some nitrides that easily sublimate.However, in order to find new materials, volatile components such as group V When attempting to obtain ceramics containing ceramics by the hot pressing method, it is necessary to obtain the volatile components, as it is well known that the vapor pressure of such volatile components increases exponentially as the temperature rises. It is urgently necessary to suppress the evaporation of ingredients.

By the way, conventional hot presses generally use a hydraulic press as the pressurizing device, but as mentioned above, when creating a high-pressure inert gas atmosphere inside the furnace in order to suppress the evaporation of volatile components, In order to push out the plunger against this internal pressure,
In addition to requiring a large pressure and making the device bulky, there was also the problem that oil adhering to the plunger disturbed the composition of the atmospheric gas inside.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hot press apparatus that uses high-pressure atmospheric gas so that the plunger can resist the internal pressure without disturbing the composition of the atmospheric gas and while maintaining sufficient airtightness inside the furnace body. The purpose is to provide a pressurizing device that is devised to allow smooth movement into the furnace.

The present invention will be described in detail below based on an embodiment shown in the drawings. Supports 3, 3 are erected on a foundation concrete 2 in which a groove 1 is provided.
An electric furnace body 4 made of, for example, stainless steel and having a heat-resistant and pressure-resistant structure is attached to the pillars 3, 3, and is equipped with a high-pressure joint 4a. Inside the electric furnace body 4,
For example, a two-split heating element 5 made of graphite is installed upright, and inside this heating element 5, a furnace top 4b
A punch rod 6 made of stainless steel and graphite, for example, is suspended from the punch rod.

An upper cylinder 7 is securely attached to the furnace bottom 4c in communication with the furnace body 4, and a known take-out valve 9 is connected to a mounting flange 8 of the upper cylinder 7 in a secure manner. Take-out valve 9
The lower connecting flange (not shown) of the intermediate cylinder 10 and the upper connecting flange (not shown) of the intermediate cylinder 10 are securely and removably connected by a split fastening ring 11 to the other side of the intermediate cylinder 10. The lower connecting flange 10a of the lower cylinder 12 is hermetically connected to the upper connecting flange 12a of the lower cylinder 12 via an insulator 13, such as Teflon, by a mounting bolt. Although not shown, an insulator 14 such as baking material is interposed between the mounting bolt and the lower flange 10a, so that the lower cylinder 12 and the electric furnace body 4 are electrically insulated from each other. There is.

A guide cylinder 15 to which the lower connecting flange 12b is screwed is inserted coaxially into the lower cylinder 12, and while the guide cylinder 15 is housed inside, the lower cylinder 12
A pressurizing cylinder 16 is housed inside so as to be movable in the axial direction. This pressurizing cylinder 16 and the upper flange 1 of the lower cylinder 12
A seal member 17 is provided between the pressurizing cylinder 16 and the lower cylinder 12, and seals between the pressurizing cylinder 16 and the lower cylinder 12. At the same time, this seal member 17
Inside the furnace, lower cylinder 12 and pressure cylinder 1
A ring-shaped piston 18 is provided at the bottom of this pressurizing cylinder 16, which seals between the pressurizing cylinder 16 and the third pressure chamber 12c between the pressurizing cylinder 16 and the guide cylinder 15. Between and pressurizing cylinder 16 and lower cylinder 12
There is a seal between the two.

High-pressure joints 19 and 20 are attached to the upper flange 12a of the lower cylinder 12, and passages 21 and 22 are provided from the high-pressure joints 19 and 20. The passage 21 opens at the upper part of the sealing member 17 and connects the electric furnace body. 4, and the passage 22 opens at the lower part of the sealing member 17 and communicates with the inside of the lower cylinder 1.
A third pressure chamber 12 is provided between the pressure cylinder 16 and the pressure cylinder 16.
It communicates with c.

On the other hand, the lower flange 12 of the lower cylinder 12
Similarly, high-pressure joints 23 and 24 are attached to b, and from these high-pressure joints 23 and 24 there is a passage 2.
5 and 26 are provided, and the passage 25 is provided in communication with the guide cylinder 15.
The passage 26 opens into a second pressure chamber 28 provided following the lower end of the pressurizing cylinder 12 . The high pressure joints 19 and 24 are connected to the valve 2.
9 through a communication pipe 30, and a gas introduction pipe (not shown) communicating with an external cylinder 33 is connected to the high pressure joint 23.

Therefore, when high-pressure, for example, inert gas is introduced into the electric furnace body 4 through the high-pressure joint 4a provided on the side, the pressurizing cylinder 16 is pushed downward, but the valve 29 is opened and electricity is not supplied. When the inert gas inside the furnace body 4 is guided to the second pressurizing chamber 28 through the communication pipe 30, the second pressurizing chamber 28 becomes at the same pressure as the inside of the electric furnace body 4. Therefore, let the pressure inside the electric furnace body 4 be P,
Let A be the pressure receiving area on the upper end side of the pressurizing cylinder 16, and let B be the pressure receiving area on the lower end side, A×
If the relational expression P<B×P is satisfied, the pressurizing cylinder 16 will automatically move toward the electric furnace body 4, but the stainless steel and graphite fixed to the upper end of the pressurizing cylinder 16 will move automatically. Considering that the punch die 32 placed on the punch rod 31 made of graphite is also made of graphite, the relational expression A×P≧B×P was established in the embodiment.
Therefore, when gas is introduced from the external cylinder 33 through the high-pressure joint 23, the pressing force from the electric furnace body 4 side of the pressurizing cylinder 16 is reduced as described above, so that the gas is pressurized at a relatively low pressure. cylinder 1
6 to the electric furnace body 4 side. This also makes it possible to calculate the pressing force even when the pressing process begins, without having to directly pull the internal pressure.

Note that when the pressure cylinder 16 rises, the gas in the third pressure chamber 12c between the lower cylinder 12 and the pressure cylinder 16 is discharged to the outside from the high pressure joint 20 via the passage 22.

Next, when the hot press is finished, the high pressure joint 2
When high-pressure gas is introduced from the other high-pressure joint 20 while removing high-pressure gas from 3, the high-pressure gas enters the third pressure chamber 12c through the passage 22, pushes the piston 18, and releases the pressurized cylinder. After lowering it to the lowest position, the take-out valve 9 is closed, the fastening ring 11 is loosened, only the pressurizing cylinder 16 is lowered, and the punch mold 31 is lowered.
The sample is taken out from the

As explained in detail above, this invention uses gas pressure in the pressurizing device, so if the same type of gas as the atmospheric gas inside the furnace body is used, the composition of the atmospheric gas will not be disturbed. Since the pressure inside the furnace body is used to move the pressurized cylinder, the pressurized cylinder can be moved without having to increase the pressure of the introduced gas very much.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, with Fig. 1 being a front view of a hot press device embodying the invention, Fig. 2 being an enlarged sectional view of the pressurizing device, and Fig. 3 showing the pressurizing device. FIG. 3 is an enlarged cross-sectional view of the cylinder in a raised state. 4... Electric furnace body, 5... Heating element, 6... Punch rod, 12... Lower cylinder, 12c... Third pressure chamber, 15... Guide cylinder, 17... Seal member, 18... Piston, 19, 20... High pressure joint, 23, 24... High pressure joint, 27... First pressure chamber, 28... Second pressure chamber.

Claims (1)

[Claims] 1. In a hot press that uses high-pressure gas as an atmospheric gas, a gas is used in the pressurizing system, a guide cylinder with an open top is provided coaxially inside the cylinder, and a guide cylinder with an open top is provided between the guide cylinder and the cylinder. A pressure cylinder is installed in a secret manner, a high pressure joint is attached to the guide cylinder side for introducing gas from an external cylinder, and a high pressure joint is attached to the cylinder side so as to act on the end of the flesh pressure part of the pressure cylinder. A hot press characterized in that a communication pipe is attached to the furnace body to introduce atmospheric gas inside the furnace body, and the pressurizing cylinder is moved using the atmospheric gas inside the furnace body and the gas outside the furnace body. Pressure device. 2. When moving the pressurized cylinder using atmospheric gas inside the furnace body and gas outside the furnace body, a guide cylinder with an open top is provided in the coaxial direction inside the cylinder, and pressurization is carried out between this guide cylinder and the cylinder. A piston comprising a movable cylinder, a sealing member sealing between the pressurizing cylinder and an upper flange of the cylinder, and a sealing member provided in the pressurizing cylinder between a lower part of the pressurizing cylinder and the cylinder and the guide cylinder. The furnace side and the piston side of the pressurizing cylinder are communicated via a communication pipe, and the upper and lower flanges of the cylinder are connected to the cylinder and the guide cylinder, respectively, so that water from an external cylinder is communicated with the piston side of the pressurizing cylinder. 2. The hot press apparatus according to claim 1, further comprising a high-pressure joint for introducing gas.