JPS61114081A - Graphite heating part for hot isostatic pressing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a graphite heating unit for equipping a hot isostatic press (hereinafter referred to as rHIPJ) used under high temperature and high pressure conditions.

[Conventional technology]

HIP is a device that performs heat treatment such as pressure sintering or diffusion bonding on materials charged in a high-pressure cylinder with a built-in heating element using an inert gas as a pressure medium, and produces an isotropic and dense sintered body. It is commonly used for the purpose of obtaining This device has a temperature of 1200~2000℃ and a pressure of 1000~2000℃.
Since it is used under severe conditions of 9 f/cm'', the structural members are required to have a material structure that can withstand these severe conditions and that can provide the necessary control mechanism.

Among these, metal heating elements with resistance heating wires made of molybdenum or tantalum have been used as heating components, but these heating elements have a heating temperature (1750°C
Since there are material limitations in the following), graphite heating elements have recently become useful. Graphite material can be used stably for a long period of time even in a high temperature range exceeding 1700℃, has a small coefficient of thermal expansion and temperature coefficient of resistivity, and is highly workable, making it suitable for the heating element for this purpose in terms of material and quality. Satisfy the required conditions.

On the other hand, as the HIF becomes larger, the shape of the furnace chamber tends to become more vertically elongated, and in this case, a phenomenon occurs that causes an imbalance in the temperature distribution in the vertical direction due to gas convection. Therefore, in order to cope with this problem, it is necessary to improve the structure of the heating element, and the following proposals have been made.

(1) Add a step to the cross-sectional diameter of the cylindrical graphite heating element,
An integrated variable diameter structure that allows the upper part to be made smaller in diameter to relatively change the amount of heat generated in the vertical direction.

(2) A structure in which a group of inverted U-shaped carbon heaters are electrically insulatively supported and fixed at their lower ends and arranged in single or multi-stage rows along a virtual cylinder (Japanese Patent Publication No. 56-44345).

(3) A structure in which graphite cylindrical heating elements with jittery horse surfaces are arranged in at least two stages, upper and lower, and both terminals of each heating element are pulled out from the heat generation direction to a position that escapes downward in the cylinder axis direction and connected to the lower electrode. (Special Publication No. 56-53188).

; However, the structures of these prior art techniques have the following problems. That is, since (1) is an integral structure, the amount of heat generated in the vertical direction cannot be arbitrarily controlled independently, and furthermore, the shape is complicated, so processing requires complicated labor. (2) In the case of a single-stage structure, it is necessary to use an inverted U-shaped carbon heater with long legs, which makes it difficult to control the amount of heat generated in the vertical direction, or in the case of a multi-stage structure, it is difficult to control the amount of heat generated in the vertical direction. The insulating support and fixing means become complicated and the durability of this part is severely restricted. Although the structure (3) has the advantage of being able to individually control the heat generation amount of each stage heating element, the terminal part of the upper stage heating element must be pulled out downward, which makes the support and fixation extremely unstable, and mechanical or There is a high risk of damage due to electrical shock. Furthermore, as the number of stages is increased, temperature uniformity on the circumferential surface is impaired and the processed shape becomes more complicated.

- [Problems to be solved by the invention] The present invention solves the problems of the above-mentioned conventional structure, is easy to process and assemble, and impairs the temperature uniformity of the peripheral surface area.

It is possible to freely control the amount of heat generated in the vertical direction without
・HI with a highly stable structure that can be used with jl
The present invention provides a graphite heat generating part for P.

[Means for Solving Problems, Embodiments] The present invention will be described below based on illustrated embodiments.

Figure 1 shows the structure of the main parts of a HIP device incorporating a graphite heat generating part of the present invention, in which 1 is an outer shell defining a high pressure chamber, 2 is a heat insulating layer, and 3 is for heating a molded product. It is a graphite heating part for The outer shell 1 is hermetically divided by a cylinder member 4 forming a side wall and upper and lower plugs 5゜5', and the heat insulating layer 2, which has a cylindrical shape, forms a recess in the graphite heat generating part 3. is set up. The graphite heat generating part 3 is connected to a device electrode part 7 fixed to the bottom of the furnace chamber via an insulating stand 6.

As shown in FIG. 2, the structure of the graphite heating section 3 includes a plurality of cylindrical graphite heating elements 8a, 8b, 8c surrounded by supporting terminals 9a, 9b, 9c, 9.
By connecting to d, they are arranged and fixed in series in multiple stages to form an integral structure.

The form of the cylindrical graphite heating elements 8a-c may be, for example, an unprocessed graphite cylinder or a graphite cylinder with a spiral slit formed therein, but in order to increase heat generation efficiency as a small current circuit, they may be arranged alternately as shown in the figure. It is desirable to form the circumferential surface in a jagged shape with slits cut therein.

Support terminals 9a-d each support cylindrical graphite heating elements 8a-c.
It is a member that functions to stably hold the parts and to supply electricity to each part separately. It is composed of a graphite support with a base end lO attached to the bottom. This shape may be a simple rod-shaped body, but
Forming it as a divided curved plate (shape shown) concentric with the cylindrical graphite heating element has the advantage that the supporting form is more stable and that it also has a heat retaining function.

The cylindrical heating element and the support terminal are connected by fastening both terminal portions 11 of the heating element in each stage to the collar flange 12 of the support terminal attached at the corresponding position with graphite bolts and nuts. Therefore, the number of supporting terminals usually needs to be twice the number of stages of cylindrical graphite heating elements, but as shown in Fig. It is also possible to have a structure in which it is directly connected to the device electrode portion 7 without being connected to a support terminal, and in this case, the number of support terminals required to be provided is reduced, making it possible to simplify the structure.

The proximal end 10 of the support terminal is coupled to the device electrode portion 7 to finally form a unitary structure.

[Action and effect of the invention]

The graphite heating section for HIP of the present invention is heated by supplying power to the cylindrical graphite heating element through the device electrode part and the support terminal, and each heating element is arranged independently in multiple stages in series. Therefore, the individual heat generation amount can be easily controlled by changing the amount of power supplied. Moreover, due to its structure, the number of stages of cylindrical graphite heating elements can be increased to three or more stages, which was difficult with conventional equipment, and the heating elements that make up each stage are formed in the same cylindrical shape. , it becomes possible to finely adjust the temperature distribution in the vertical direction without impairing the uniformity of the peripheral surface temperature. Therefore, the imbalance in temperature distribution caused by the convection of the pressurized gas is effectively eliminated, and the production of high-quality molded bodies is always guaranteed.

In addition, since each cylindrical graphite heating element is fixed to the support terminal with both terminals suspended, the holding structure is extremely stable and will not be damaged by mechanical or electrical shock during use. .

In addition, since the shape of the heating element can be unified, processing, assembly, and interchangeability are easy, and by forming the support terminal into a split curved plate, it is possible to provide a heat retention effect, compared to conventional equipment. This brings a variety of extremely practical functions to the system.

[Brief explanation of the drawing]

The figure shows an embodiment of the present invention, and Figure 1 shows an H1d! Cross-sectional structural diagram of the plant, 2nd
The figure is a partially cutaway perspective view of a cylindrical graphite heat generating section. l...outer shell part, 2...insulation layer, 3...graphite heat generating part, 4...cylinder part, 5.5'...upper and lower plugs, 6...insulation stand, 7...・Device electrode part, 8
a-c... Ro. Cylindrical graphite heating element, 9a-d... support terminal,
10... Proximal end portion, 11... Terminal portion, 12.
...Tsuba flange.

Claims (1)

[Claims] 1. A plurality of cylindrical graphite heating elements are arranged and fixed in series in multiple stages by connecting via terminal portions to separate support terminals provided around the outer surface of the heating elements, and A graphite heating part for hot isostatic pressing, which is formed into an integral structure by connecting the base end of a support terminal to an electrode part of the device. 2. Graphite heating for hot isostatic pressing according to claim 1, in which the terminal portion of the cylindrical graphite heating element located at the lowest stage is directly connected to the device electrode portion without connecting to the support terminal. Department.