JPH018954Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a heat insulating layer for a hot isostatic pressing (hereinafter abbreviated as HIP) device that has excellent heat insulation in a high temperature region.

(Prior Art) Recently, there has been a growing trend to process metal powders, ceramic powders, etc. under high temperature and high pressure to produce heat-resistant sintered products, and HIP equipment is attracting attention as a device for this purpose.

By the way, in this HIP device, basically, as shown in FIG. 1, a high-pressure container is defined by a high-pressure cylinder 1 and an upper plug 2 and a lower plug 3 that seal the upper and lower openings of the cylinder. Hyperbaric chamber 4
is formed, a cylindrical heat insulating layer 5 and a heating device 6 are arranged inside the high pressure chamber 4 to form a furnace chamber 7, and the object to be processed M is integrally attached to the lower plug 3. The furnace chamber 7 is placed on the heat insulating seat 8
The HIP process is performed in a high-temperature, high-pressure gas atmosphere inside the chamber, but since the object to be treated and the furnace structure are housed within the high-pressure chamber, it is possible to prevent the strength of the high-pressure vessel itself from decreasing due to temperature increases, and to reduce the need for expensive high-pressure vessels. Insulating materials and structures are extremely important elements from the standpoint of effectively utilizing internal volume.

In particular, in recent HIP equipment, the processing temperature and pressure are gradually increasing, and in order to suppress heat transfer by convection and heat transfer by radiation based on the physical properties of high-pressure gas, a heat-insulating structure with excellent insulation in high-temperature areas is required. It has been demanded.

Therefore, in order to meet the demand for such a heat insulating structure, the present applicant has previously published Japanese Patent Application Laid-Open No. 56-6736 and Japanese Patent Application Laid-Open No. 58-58.
Several heat insulating structures were proposed in No. 199803 and others.

Of these, the former has a heat-insulating layer structure whose main components are a graphite cylinder formed by winding a flexible graphite sheet multiple times and a graphite cap that does not have flexibility. This is a heat insulating layer structure using a flexible graphite sheet with holes or holes in every other layer.

However, after further study and actual testing of each of the above-mentioned heat insulating layers, it was discovered that the following problems still remained.

That is, the accuracy of the thickness of a flexible graphite sheet is not as good as that of a metal sheet, and therefore it is difficult to keep the outer diameter of the wound cylindrical part within a certain tolerance. A gap is created between the graphite cylinder and the graphite cap, which causes convective movement of gas from the inside to the outside of the insulation layer, impeding the insulation performance.

It is also possible to uniformly reduce the inner diameter of the graphite cap, but this has the disadvantage that the amount of deformation required when covering the graphite cylinder becomes excessive, causing buckling and breakage of the graphite cylinder in the axial direction.

(Purpose of the invention) The present invention deals with the above-mentioned actual situation and problems, and combines the heat insulating layer structures according to both of the above proposals, as well as providing a graphite sheet with uneven parts on the upper graphite cap of the wound graphite cylinder. The purpose of this is to compensate for the non-uniformity of the thickness, to more reliably prevent convective movement, and to make it effective in insulating high-temperature areas.

(Structure of the invention) That is, the feature of the invention that meets the above object is that the heat insulation layer disposed in the high-pressure vessel has the following structure.

(a) A body in which a plurality of graphite cylinders formed by winding multiple layers of flexible graphite sheets are arranged concentrically, a canopy in which multiple layers of flexible graphite sheets are polymerized, and a canopy arranged between the canopies. (b) A flexible graphite sheet having holes or holes is arranged in every other layer of the flexible graphite sheet in the graphite cylinder of the body; c) The polymer canopy is arranged in contact with the upper end of the odd-numbered graphite cylinder; (d) A short cap-shaped graphite cap is tightly fitted and arranged so as to surround the upper end of the graphite cylinder, and its lower end is in contact with the upper end surface of the even-layered graphite cylinder, forming an axial overlap part with adjacent graphite caps, and sandwiching the upper end of the odd-numbered layer graphite cylinder in the overlap part; A convex part or an uneven part is provided in the overlap part of the graphite cap; (f) A hole or hole is not located in the graphite cylinder of the overlap part at least in the assembled state; (Example) The following Further, with reference to the accompanying drawings, specific embodiments of the present invention will be described in detail.

FIG. 2 shows a heat insulating layer structure according to one example of the present invention. JP-A-56-6736, which has no air permeability as a whole and is composed of a heat insulating material 18 such as inorganic fiber.
It consists of a known heat insulating layer as shown in FIGS. 2 and 3 of the publication.

On the other hand, the inner heat insulating layer 12 includes the essential parts of the present invention, and includes a plurality of graphite cylinders 11a to 11d formed by winding a plurality of flexible graphite sheets as described below on the outside of an inverted cup-shaped graphite cap 14. A body arranged in concentric circles, canopies 13a to 13c made of multiple layers of flexible graphite sheets, and graphite caps 14a and 14b in the form of short caps without flexibility arranged between the canopies. The polymerized canopies 13a and 13b are arranged in contact with the upper ends of the graphite cylinders 11a and 11c of odd-numbered layers, and
The graphite caps 14a, 14b are tightly fitted to surround the upper ends of the graphite cylinders 11a, 11c of the odd-numbered layers, and are axially moved by the adjacent graphite caps 14, 14a, 14a, 14b. A graphite cylinder 11a with an even number of layers at the lower end is inserted between the formed overlap portions,
It is arranged in contact with the upper end portion of 11d.

In the illustrated example above, the graphite cylinders 11a to 11 are formed by winding a plurality of layers of flexible graphite sheets.
d is a flexible graphite sheet 21 having holes or holes as shown in FIG. It is formed by alternately arranging and winding layers, and the upper and lower edges thereof are provided with holes or portions without holes, and the portion located in the above-mentioned overlap portion is formed by at least these holes or holes. The part without holes is inserted.

Further, the portion without a hole or hole may be at least an overlap portion, and an edge portion on the lower end side is sufficient as long as it does not cause damage to the graphite cylinder.

Note that the shape of the holes or holes of the flexible graphite sheet having the holes or holes arranged in every other layer is as follows:
It can be of any shape, such as circular or square, and
The holes may have the same size or a mixture of sizes, but it is preferable that the area occupied by the holes is about 70 to 95%. Furthermore, a method for punching holes in a flexible graphite sheet is also described in Tokkai Publication No. 199803/1983.
The sheet can be punched to a thickness of 0.1 to 1.0 mm, and any known perforation means, such as punching, can be used as appropriate.

Further, in the illustrated example, an inverted cup-shaped graphite cap 14 is arranged on the innermost side, but the graphite caps 14a and 14b fitted to the upper end of the graphite cylinder connect the graphite cylinder 11c and the polymerized canopy 13b. 7 inside the furnace through the small gap between
This can sufficiently prevent the formation of a gas convection circuit in which the high-temperature gas inside flows out of the inner heat insulating layer 12, flows down between the inner and outer heat insulating layers, and then flows into the furnace chamber again from the lower part of the inner heat insulating layer. The inner graphite cap 14 can be omitted.

In the figure, 20 is, for example, an inverted cup-shaped ceramic member, and this alone can also be used as the outer heat insulating layer.

Therefore, in the heat insulating layer structure having the above structure, the present invention further includes the graphite cap 1.
4, 14a, and 14b are provided with one or more convex portions or concavo-convex portions 16 as shown in FIGS. 3 to 5. 3 shows an example in which the protrusions 16 are formed only on the inner surface of the graphite cap 14a, FIG. 4 shows an example in which the protrusions 16 are formed only on the outer surface of the graphite caps 14, 14a, and FIG. This is an example in which uneven portions 16 are provided on the outer surface of the graphite cap 14a and on both the inner and outer surfaces of the graphite cap 14a. However, in the case of FIG. 5, the convex portion and the concave portion are provided at corresponding positions in the axial direction, and of course,
It is desirable that the height of the convex portion be greater than the depth of the concave portion.

Examples of the present invention have been described below, but modifications in details may be made at will as long as they do not deviate from the purpose of the present invention, and the structure can form a heat insulating layer structure with higher practical effects than conventional heat insulating layers. Can be done.

That is, by adopting the above-mentioned heat insulating layer structure, the high temperature part of the furnace chamber 7 is insulated in the thickness direction by the laminated part of the graphite sheet with extremely high insulation properties, so that even if the temperature in the furnace chamber is increased to 2000 degrees Celsius or higher, the inside The outer surface temperature of the heat insulating layer can be maintained below 1000℃, and the intervening sheet without holes or holes and the graphite cap with uneven parts prevent gas flow inside and outside the inner heat insulating layer. To obtain a heat insulating layer with excellent thermal insulation by reliably preventing high-temperature gas in the furnace chamber from flowing out of the inner heat insulating layer through the contact portion between the polymer canopy and the graphite cylinder and from convective movement of gas in the furnace chamber. Can be done.

(Effects of the invention) As described above, the heat insulating layer of the present invention has holes or flexible graphite sheets with holes interposed in the graphite cylinder forming the body, so the contact area between adjacent sheets is small and the insulation layer is improved by heat conduction. There is no drop in the temperature, and since there is no direct contact between the sheets on both sides, gas can freely flow in and out, making it difficult to create a pressure difference between the inside and outside of the insulation layer, and there is no risk of deformation or damage to the insulation layer. Since the upper part is securely tightened by the concave and convex portion provided in the graphite cap overlap, the sealing effect at the contact area between the graphite cylinder and the polymer canopy is improved, and the generation of convection from the inside to the outside of the insulation layer is ensured. It has a remarkable effect of preventing heat loss and reducing heat loss.

In addition, since there are no holes or holes in the graphite cylinder in the overlap area, there is no deterioration due to tightening, and the irregularities are caused by the uneven thickness of the flexible graphite sheet, which is less accurate than the metal sheet. Even if there is some variation in the finished outer diameter of the graphite cylinder, this can be compensated for by local deformation, and the outer diameter of the wound cylinder can be kept within a certain tolerance, resulting in good convection prevention. It has the effect of exerting its effect.

Thus, by using a flexible graphite sheet and laminating multiple layers, it effectively blocks heat transfer from three aspects: conduction, convection, and radiation, increasing its practical effect as a heat insulating layer in high-temperature regions.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the basic configuration of the HIP device.
Fig. 2 is a sectional view of a main part showing an example of the heat insulating layer of the HIP device according to the present invention, and Figs. 3 to 5 show examples of the uneven structure of the graphite cap overlap portion of the heat insulating layer. Fig. 2 A partial enlarged sectional view, No. 6
The figure is a configuration explanatory diagram showing a graphite cylindrical winding mode. 1...High pressure cylinder, 2...Upper plug, 3...
...Lower plug, 4...High pressure chamber, 5...Insulation layer, 6
... Heating device, 7 ... Furnace chamber, 11a to 11d ...
Graphite cylinder, 13a, 13b, 13c...Polymerized canopy, 14, 14a, 14b...Graphite cap, 16...Irregularities, 21...Flexible graphite sheet without holes, 22...Possible to have holes. Flexible graphite sheet, M...Object to be treated.

Claims (1)

[Scope of utility model registration request] A body in which a plurality of graphite cylinders formed by winding multiple layers of flexible graphite sheets are arranged concentrically, a canopy made of multiple layers of flexible graphite sheets, and a short cap-shaped cap placed between the canopies. The graphite cylinder of the body has a hole or hole in every other layer of the flexible graphite sheet, and the polymer canopy has a graphite cap at the upper end of the graphite cylinder of the odd numbered layers. Furthermore, a short cap-shaped graphite cap is closely fitted to surround the upper end of the graphite cylinder, and its lower end is in contact with the upper end surface of the even-numbered graphite cylinder. , adjacent graphite caps form an axial overlap part, and the upper ends of the graphite cylinders of the odd-numbered layers are sandwiched in the overlap part, and the overlap part of the graphite caps is provided with a convex part or an uneven part. A heat insulating layer for a hot isostatic pressurizing device, characterized in that, at least in an assembled state, the graphite cylinder of the overlap portion has no holes or holes.