JPH0222122B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a solid hot isostatic sintering method, generally abbreviated as SHIP method, and a hydrostatic (isostatic pressure) hot pressing method using a solid lubricant. This relates to a device used for.

(Conventional technology and its problems) The general hot press method heats and presses powdered sintered material filled in a mold to sinter it into the desired product shape, but the product shape is limited. In addition, so-called "porosity" is likely to occur, and the sintered density cannot be uniformly increased to produce a high-strength product.

In order to eliminate these drawbacks of sintered products manufactured by the hot press method, an isostatic pressure method (so-called HIP method) was developed in which the sintered primary product was pressurized using a gas such as argon as a pressure medium. However, due to the handling of high-pressure gas, a large-scale furnace protection facility was required, which significantly increased equipment costs, making it impractical as equipment for manufacturing small items, especially in small-scale factories.

Therefore, it was considered to remove defects in sintered products using the SHIP method that uses a solid lubricant as described above. This SHIP method is used to manufacture translucent zinc oxide, etc. In this method, a pressurizing mold is filled with a solid lubricant such as h-BN, and the primary sintered product is embedded in the fixed lubricant. This is a method in which the internal primary sintered product is pressurized with isostatic pressure via the solid lubricant and heated at the same time by mechanically pressurizing the solid lubricant as in the usual hot pressing method.

This SHIP method has advantages such as not requiring large-scale protection facilities for the furnace like the HIP method explained earlier, and also being able to remove sintering defects in the same way as the HIP method. In order to achieve this goal, it is necessary to maintain the lubricity of solid lubricants at their best. Used as a fixed lubricant
-Since the lubricity (fluidity) of BN etc. changes depending on temperature etc., it is extremely difficult to maintain the lubricity of the solid lubricant at its best while adjusting the sintering conditions such as temperature and pressure to the purpose of sintering. In some cases, the solid lubricant in the mold may cause a bridging phenomenon, making it impossible to pressurize the material to be sintered with the intended isostatic pressure.

(Means for solving the problem) The present invention proposes an isostatic pressure hot press device that can solve the problems in the conventional SHIP method as described above. and a cylindrical shape facing the pressurizing punch rod of the pressurizing means. A rod-shaped vibration adding means inserted from outside the furnace is provided in the inner cavity of the receiving punch rod, which is made up of a main body and an inner end member and has a hollow portion inside, and the tip of this vibration adding means is inserted into the hollow portion of the receiving punch rod. A pressing means for pressing against or separating the inner end member from the back surface is provided, and a cooling water passage is provided for the vibration applying means.

(Example) An example of the present invention will be described below based on the attached illustrative drawings.

1 is a mold for pressure sintering, which includes a cylindrical mold 2, a pressurizing punch rod 3 that can be raised and lowered and fits into the upper half of the mold 2, and a pressurizing punch rod 3 that fits into the lower half of the mold 2. It consists of a receiving punch rod 4 that fits together, and the inside is filled with a suitable solid lubricant S such as h-BN.
A sintered material (primary sintered product) W is buried inside this solid lubricant S. Reference numeral 5 denotes a heat insulating inner casing containing the mold 1, which is supported within a water-coolable outer casing 6. 7 is an induction heating coil surrounding the inner casing 5;
The mold 1 is heated from the outside of the inner casing 5 to a predetermined temperature by high-frequency induction heating.
It is also possible to use internal electric heating elements. The outer casing 6 has an exhaust port 8 for evacuating the inside thereof, and a gas supply port 9 for filling the casing 6 with a suitable inert gas.
and a gas outlet 10 are provided.

11 is a hydraulic cylinder unit supported by an upper support plate 12, and its piston rod 11
a passes through a guide member 6a provided on the ceiling of the outer casing 6, and the tip of the piston rod 11a is connected to the upper end of the pressurizing punch rod 3 protruding upward from the inner casing 5 via an intermediate member 13 made of a refractory material. It is brought into contact with the The receiving punch rod 4 includes a hollow cylindrical body 14 that passes through the inner casing 5, and this cylindrical body 14.
It is composed of an inner end member 15 fitted inside the cylindrical body 14, and a receiving plate 16 that supports the outer end of the cylindrical body 14,
The receiving board 16 is supported by a lower handheld board 17 via a handheld member 6b provided at the bottom of the outer casing 6. This lower support plate 17 is connected to the upper support plate 12.

Reference numeral 18 denotes a vibration applying means having an ultrasonic vibrator 20 attached to one end of a rod-shaped vibration transmitting member 19, and is supported by a piston rod 21a of a cylinder unit 21 for moving up and down in the axial direction. The rod-shaped vibration transmission member 19 is connected to the lower support plate 17 and the bottom support member 6 of the outer casing 6.
b, and the receiving plate 16 in the axial direction so as to be movable up and down, and are inserted into the cylindrical body 14 of the receiving punch rod 4, and are pushed up by the piston rod 21a of the cylinder unit 21.
It is pressed against the back surface of the inner end member 15 of the receiving punch rod 4.

Note that the member that enters the outer casing 6, that is, the piston rod 11a of the cylinder unit 11
cooling water passages 22, 2 for the vibration adding means 18, etc.
3, so that it can be water cooled. Also, although illustrations and explanations of specific structures have been omitted, both the inner and outer casings 5, 6, the induction heating coil 7, etc. In order to make it possible to attach and detach the press, it is constructed so that it can be opened and closed or divided in the horizontal and horizontal directions or in the vertical direction, similar to conventional hot press devices of this type.

To explain the isostatic pressure hot pressing method of the present invention using the apparatus configured as described above, as shown in the figure, a pressure sintering mold 1 is filled with a solid lubricant S, and the solid lubricant is A state in which an appropriate number of materials W to be sintered are buried inside S so as not to contact the formwork 2 or both punch rods 3 and 4, and the induction heating coil 7 is energized to heat the mold 1 to a predetermined temperature. In this step, the cylinder unit 11 is operated and its piston rod 11a presses the pressurizing punch rod 3 toward the receiving punch rod 4 side, and the solid lubricant S in the formwork 2 is separated from the pressurizing punch rod 3 and below. Side support plate 17
It is compressed between the punch rod 4 for receiving and supported by the punch rod 4 for receiving. As a result, the solid lubricant S applies pressure evenly to the internal sintered material W from all directions due to its lubricity (fluidity). That is, the material to be sintered W embedded in the solid lubricant S is heated to a predetermined temperature while being subjected to isotropic pressure.

In the process of isostatically hot pressing the material W to be sintered, the vibration applying means 18 is raised by the piston rod 21a of the cylinder unit 21, and the tip of the rod-shaped vibration transmitting member 19 is pressed against the receiving punch rod 4. The solid lubricant S in the mold 1 is vibrated by operating the vibrator 20 while being in pressure contact with the back surface of the inner member 15. As a result, the solid lubricant S in the mold 1 is transferred to the pressurizing punch rod 3.
The material to be sintered is compressed and vibrates at the same time as it is compressed between the punch rod 4 and the receiving punch rod 4, and together with its own lubricity (fluidity), the material to be sintered is compressed completely without any gaps without causing any bridging phenomenon. It is possible to reliably apply isotropic pressure to the surface of W.

The application of vibration to the solid lubricant S may be performed continuously during the entire process of the hot press, or may be applied intermittently at appropriate intervals. or,
In some cases, it is also possible to apply vibration to the solid lubricant S only immediately after starting hot pressing. The amplitude and frequency of the vibration to be added are
Of course, the setting must be made so that the intended isostatic hot pressing effect on the material W to be sintered is not adversely affected.

The vibration source used as the vibration applying means is not limited to an ultrasonic vibrator. For example, a method using hydraulic pressure or electromagnetic force, a mechanical method using an eccentric rotating body, etc. can be selected as appropriate.

Incidentally, when performing the above-described isostatic pressure hot pressing, the air inside the outer casing 6 can be replaced with an atmosphere adjusting gas such as nitrogen or argon, or it can be evacuated to create a vacuum.

(Effects of the Invention) According to the present invention, the means for pressurizing the powdery solid lubricant embedding the material to be sintered includes a pressurizing punch rod, a cylindrical body facing the punch rod, and an inner end member. A receiving punch rod having a hollow portion inside is provided,
Since a rod-shaped vibration adding means inserted from outside the furnace is provided in the cavity inside the receiving punch rod, no pressure is applied to the vibration adding means, and therefore the vibration used in the vibration adding means is As a source, an ultrasonic vibrator or the like which has poor pressure resistance but excellent vibration performance can be used. Therefore, the granular solid lubricant is pressurized and at the same time is subjected to efficient vibration, which improves its own lubricity (fluidity) and allows it to adhere to the material to be sintered without causing bridging. It is possible to contact without any gaps and to surely apply isostatic pressure to the material to be sintered, thereby reliably obtaining the desired isotropic hot press effect.

In addition, since a pressing means is provided to separate the tip of the vibration applying means from the back surface of the inner end member of the receiving punch rod, the vibration is applied from a position extremely close to the powder solid lubricant. can be applied reliably, and the vibration applying means is kept away from the inner end except when pressurizing or vibrating.
It can be protected from the high temperature atmosphere around the mold.
Cooling water is passed inside the vibration adding means, so
Even if the vibration applying means receives heat from a high-temperature environment, the temperature does not rise and deterioration can be prevented. Since the vibration applying means is separated from the cylindrical main body, heat is not transferred from the cylindrical main body to the vibration applying means by thermal conduction. During machining vibration, the vibration applying means receives heat conduction from the inner end member, but since cooling water is passed through it, excessive temperature rise can be prevented.

[Brief explanation of drawings]

The drawing is a longitudinal side view showing an embodiment of the present invention. 1...Mold for pressure sintering, 2...Cylinder-shaped formwork, 3...Punch rod for pressurization that can be raised and lowered, 4...Punch rod for receiving, 5...Inner casing made of heat insulating material, 6... ... Water-coolable outer casing, 7 ... Induction heating coil, 11 ... Hydraulic cylinder unit for pressurization, 14 ... Cylindrical body, 15 ... Inner end member of receiving punch rod 4, 18 ... Vibration adding means ,1
9... Rod-shaped vibration transmission member, 20... Ultrasonic vibrator, 21... Cylinder unit for raising and lowering the vibration adding means (pressing means), 22, 23... Cooling water passage.

Claims (1)

[Claims] 1. A pressurizing means for pressurizing the powdery solid lubricant filled in the mold and embedding the material to be sintered, and a heating means for heating the mold, and a pressurizing punch rod in the pressurizing means. A rod-shaped vibration applying means inserted from outside the furnace is provided in the internal cavity of a receiving punch rod consisting of an opposing cylindrical body and an inner end member and having a hollow inside, and the tip of this vibration applying means is connected to the An isostatic hot press apparatus characterized in that a pressing means is provided for pressing against or separating the inner end member of the receiving punch rod from the back surface thereof, and the vibration applying means is provided with a cooling water passage.