JP3018843B2 - Heat treatment furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a heat treatment furnace such as a resistance furnace having a resistance heating element.
The present invention relates to a heat treatment furnace provided with a heat insulating wall structure that is less likely to warp, deteriorate, and the like even when the temperature is repeatedly lowered.

[0002]

2. Description of the Related Art Conventionally, resistance furnaces, induction furnaces, arc furnaces, plasma furnaces, and the like are known as heat treatment furnaces used for heat treatment of various industrial materials such as carbon materials and ceramic materials. A resistance furnace using Joule heat generated by passing an electric current through a resistance heating element is widely used.

Normally, this resistance furnace type heat treatment furnace forms a heat treatment chamber for an object to be treated by attaching a heat insulating material to an inner wall surface of a cylindrical or box-shaped furnace shell, and forms a cylindrical or rod-shaped heat treatment chamber in the heat treatment chamber. The resistance heating element is disposed vertically or annularly, and the object to be processed is allowed to stand still in the heat treatment chamber or continuously passed through the heat treatment chamber at a high temperature of about 2000 to 3000 ° C. and under a reduced pressure atmosphere. Heating is performed using radiant heat radiated from the surface of the resistance heating element in an inert gas atmosphere such as nitrogen or argon. As a resistance heating element, a metal material or a ceramic material cannot be put to practical use.
Carbon materials (mainly graphite), which are sufficiently inexpensive even at a high temperature range of 00 to 3000 ° C. without causing melting and decomposition, and are relatively inexpensive materials, are generally used.

As a general heat insulating wall structure at a high temperature, as shown in FIG. 5, the heat insulating wall structure 3 has a furnace shell side formed heat insulating material 30 and a heat treatment The room-side formed heat insulating material 31 is mainly provided in this order.
In order to protect these two layers of heat insulating materials 30 and 31 from intense radiant heat radiated from a heat source (not shown) inside the heat treatment chamber, for example, And a protective layer 33 made of a material such as a sheet-like c / c composite or a graphite plate. The heat treatment chamber side molded heat insulating material 31 is divided stepwise through predetermined gaps in order to allow expansion and contraction at the time of high temperature heating and to seal the atmosphere in the furnace. Felt 3 made of graphite
9 are filled. And these molded heat insulating materials 30,
31 and the protective layer 33 are provided with a through-hole 32 and a tubular boss 35 made of graphite and made of a furnace shell side molded heat insulating material 3.
The boss 35 is integrated with a left end of the boss 35 and a surface of the protective member 33 with a bolt 36 and a nut 37 made of a carbon material or a c / c composite through a carbon seat 38.

[0005] As the temperature of the heat treatment furnace rises and falls, the heat insulating material 3
The boss 35 is expanded so that the heat insulating material 3 can be easily moved.
Of the molded heat insulating material 3
The number of divisions of 0 and 31 was reduced so that the number of joints was reduced.

As a conventional heat treatment furnace to be subjected to such a high-temperature region, particularly a high-temperature heat treatment at 2500 ° C. or higher, the one disclosed in, for example, JP-A-63-153388 has been proposed.

In this heat treatment furnace, at least a part of the side wall surface of the heat insulating material in the processing chamber is formed of a graphite-based material having a bulk density of 0.3 g / cm ³ or more, and an outer surface area (A) of the graphite heater.
h) and the ratio A of the surface area (Ai) of the side wall surface of the processing chamber of the heat insulating material.
h / Ai is 0.1 to 0.4 and bulk density is 0.3 g / cm ³
The relationship between the surface area (Ar) of the wall surface formed of the above graphite-based material and the outer surface area (Ah) of the graphite heater is Ar> Ah, and the emissivity of the graphite-based material at 2000 ° C. is 0.8.
The following is intended to extend the life of the graphite heater and the heat insulating material against thermal degradation.

[0008]

However, in the above-mentioned conventional heat treatment furnaces, each of the molding heat insulating materials used is formed by laminating a felt as a base material through a binder such as a phenol resin, and the heat treatment furnace such as a resistance furnace. In the case of heat treatment furnaces used for industrial use, products processed at 2000 to 2400 ° C. are used in many cases because the price increases when the heat treatment temperature is high. is there.

For this reason, when the temperature is repeatedly increased and decreased at a high temperature, particularly at a high temperature of 2500 ° C. or higher, which is higher than the above-mentioned processing temperature, a progressive warp occurs in the molded heat insulating material, and the heat insulating material is stretched on the side wall surface of the processing chamber. There was a disadvantage that the graphite-based material was damaged. As a result, voids due to warping are generated at the joints of the molded heat insulating material, causing temperature unevenness in the heat treatment chamber, and deteriorating the quality of the object to be processed. There is a problem that the life as a heat insulating material is reached.

Further, the broken portion of the graphite-based material cannot reflect the radiant heat radiated from the surface of the resistance heating element, so that the radiant heat directly hits the molded heat insulating material and is generated when the object to be processed is heated. Since the pyrolysis gas is permeated into the formed heat insulating material, there is a disadvantage that the deterioration of the expensive formed heat insulating material is promoted.

The present invention has been made in view of such circumstances, and even when heat treatment conditions are high temperature and severe for a long time, the heat insulating material inside the heat treatment chamber may be warped or deteriorated. An object of the present invention is to provide a heat treatment furnace having a heat insulating wall structure capable of performing a high-temperature treatment for a sufficiently long time without performing the heat treatment.

[0012]

In order to achieve the above object, a heat treatment furnace according to the present invention has a resistance heating element for heating an object to be processed, a resistance heating element surrounding the object to be processed and the resistance heating element, and a heat insulating inner surface. A heat treatment chamber having a heat treatment chamber in which a material is fixed, wherein the heat treatment furnace heat-treats the object by radiant heat radiated from the surface of the resistance heating element; (a) the heat insulating material is fixed to a furnace shell (B) the heat treatment chamber, comprising at least two layers of a furnace shell-side heat insulation material and a plurality of heat treatment chamber-side formed heat insulation materials laminated on the furnace shell side heat insulation material and divided into a plurality of pieces facing the heat treatment chamber; On the surface of the side molded heat insulating material, the flexural modulus is 0.5 Ton / mm ² or less and the thickness is 3
by joining a flexible sheet-like protective material that is divided into a plurality consisting mm or less graphite stretched in a planar shape, (c) wherein the junction of the heat treatment chamber side molding insulation, said Allowed
An aforesaid plate made of graphite is provided via a flexible sheet-like protective material, and an L-shaped member made of graphite is provided around the heat-insulating material on the side of the heat treatment chamber. The member is fixed to the surface of the furnace shell side formed heat insulating material by a fixing member.

[0013] In this case, the furnace shell side formed heat insulating material, the heat treatment room side formed heat insulating material, the flexible sheet-shaped protective material, the plate and the L
The shape member is made of graphite, a cylindrical boss, and graphite material or c.
It is preferable that the fixing member is integrally fixed with a fixing member having a pull-out preventing structure including a bolt and a nut made of a / c composite. That is, the pull-out prevention structure referred to here means a structure in which a nut screwed to the bolt is fixed to the heat insulating material so that the boss or the bolt inserted into the heat insulating material does not come off to the heat treatment chamber side. A material that has a specific dimensional relationship.

Further, the heat-insulating material on the furnace shell side and the heat-insulating material on the heat treatment chamber side have a rectangular shape after joining, and the relationship between the length (L) and the thickness (t) of the long side is L ≦ L. It is preferably 7t.

Further, the furnace shell side heat insulating material and the heat treatment room side heat insulating material have a rectangular shape after joining, and the relationship between the length (L) of the long side and the thickness (t) is L ≦ L. It is preferably 7t.

[0016]

According to the heat treatment furnace of the present invention, the surface of the heat-insulating material on the heat treatment room side has a flexural modulus of 0.5 Ton / mm ² or less,
In addition, since a flexible sheet-shaped protective material having a thickness of 3 mm or less is stretched, even if the furnace shell-side formed heat insulating material and the heat treatment room side formed heat insulating material warp or undulate due to radiant heat from the resistance heating element. Since it has a low flexural modulus, it can follow the warpage, undulation, etc. of the heat insulating material without being damaged, and can always block radiant heat.

Further, since the protective material is not damaged or deteriorated even at a high temperature of 2500 ° C. or more, the thermal insulation gas deteriorates due to the permeation and adsorption of the pyrolysis gas generated from the object to the heat insulating material and the heat treatment. The deterioration of the surface of the chamber-side formed heat insulating material due to radiant heat from the resistance heating element is prevented.

Further, since the furnace shell-side formed heat insulating material and the heat treatment room side formed heat insulating material are fixed at their joints and peripheral portions with a contact plate, an L-shaped member, a fixing member, and the like, they are apparently integrated in the thickness direction. Heat insulation material, thus improving rigidity,
As a result, warpage of the peripheral portion of the heat treatment chamber side heat insulating material exposed to high temperatures is prevented.

Furthermore, the furnace shell side heat insulating material and the heat treatment room side heat insulating material have a rectangular shape after joining, and the relationship between the length (L) of the long side and the thickness (t) is L ≦ 7t. Therefore, the area per sheet can be reduced, and deformation due to warpage can be suppressed even with the same thickness.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat treatment furnace according to the present invention will be specifically described below with reference to the drawings. 1 is a longitudinal sectional view of a heat treatment furnace according to the present invention, FIG. 2 is an enlarged sectional view of a furnace wall portion of FIG. 1, FIG. 3 is a right side view thereof, and FIG. It is.

In FIG. 1, reference numeral 1 denotes a box-shaped heat treatment furnace in which a heat treatment chamber 5 is formed, and a furnace shell side formed heat insulating material 30 and a heat treated room side formed heat insulating material 31 are provided inside the furnace shell 2. Is fixed, and further on the inner wall surface of the heat treatment room side formed heat insulating material 31,
A flexible sheet-like protective material 40 which is a feature of the present invention is stretched. In the heat treatment chamber 5, three resistance heating elements 6 are arranged in three rows in a direction perpendicular to the plane of the drawing, and two ends thereof are fixed to the electrodes 7 and both ends are fixed to the electrodes 7 and the power supply terminal sections 8 insulated from the furnace shell 2. Supported by. Each of the resistance heating elements 6 causes the object 4 placed on the support member 9 by Joule heat generated by a current supplied from an external power supply facility (not shown).
To radiate heat to perform heat treatment. Further, in the heat treatment furnace 1, the inert gas G is supplied to the bottom of the furnace so that the object 4 can be heated under an inert gas atmosphere such as nitrogen gas or argon gas under a predetermined pressure. Mouth 10
An exhaust port 12 with an electromagnetic valve 11 is provided at the furnace top, and is controlled by a controller (not shown). Note that 13
Is a radiation thermometer for measuring and controlling the surface temperature of the resistance heating element 6 through the viewing window 14. The output signal from the radiation thermometer 13 is transmitted to the heating controller 15, and the heat treatment chamber 5
The output of the resistance heating element is controlled so that the inside temperature becomes constant. Reference numeral 16 denotes a door for taking the workpiece 4 into and out of the heat treatment chamber 5, and can be opened and closed by a device (not shown).

Here, the furnace shell 2 has a thickness of 3 to 3 mm.
It is made of a steel plate of 10 mm, for example, stainless steel, carbon steel or the like, and its outer shape can be formed in any shape such as a box shape or a cylindrical shape.

As the furnace shell-side formed heat insulating material 30 and the heat treatment room-side formed heat insulating material 31, it is preferable to use a material made of graphite, and the thickness thereof is not less than 2500 ° C. in the heat treatment room of the present invention. In the area, each 100
It is preferably about 250 to 250 mm and about 100 to 200 mm.

The flexible sheet-like protective material 40 is made of graphite having anisotropy, has a flexural modulus of 0.5 Ton / mm ² or less, and has a thickness of 3 m.
m or less. The reason is,
The above properties have remarkable anisotropy in thermal and electrical properties, and thermal conductivity is high in the plane direction, but in the direction perpendicular to the plane,
That is, it is low in the thickness direction, which is a suitable characteristic for blocking radiant heat. The above-mentioned characteristic is, in a high-temperature region of 2500 ° C. or higher, 2400 ° C. or lower in a heat treatment furnace used for industrial use as described above. Because the treated molded insulation is used in view of cost considerations,
At the time of actual heating, undulations of about 3 to 5 mm cannot be avoided as the molded heat insulating materials 30 and 31, but by covering the flexible sheet-like protective material 40, intense radiant heat from the resistance heating element is blocked. In addition, it protects itself without cracking, burning, etc., it curves when the temperature rises according to the undulations of the formed heat insulating materials 30 and 31 and returns to the original flat sheet when the temperature drops. This is because they perform their functions. This protective function cannot be obtained if the specific flexural modulus and thickness are exceeded.

As a sheet-like protective material exhibiting such two characteristics, for example, a sheet-like material having a thickness of about 0.2 to 3 mm obtained by pressure-expanding expanded graphite can be mentioned. The flexural modulus is 0.5 Ton / mm ² or less, the bulk density is about 1.0 g / cm ³ , and the structure is dense. Commercially available products include "Carbofit" (manufactured by Hitachi Chemical Co., Ltd.), "Permafoil" (manufactured by Toyo Tanso Co., Ltd.), "Nica Film" (manufactured by Nippon Carbon Co., Ltd.), and "Grafoil" (Union Carbite Co., Ltd.) Made)
Etc. exist. This flexible sheet-like protective material 40 is easy to process such as drilling and shaping, and a relatively thin material can be bent with a small radius of curvature.
It can be affixed to a corner portion in a heat treatment chamber, and is inexpensive and economically advantageous compared to a conventional sheet-like c / c composite or a protective material made of a graphite plate.

Next, the heat insulating wall structure of the heat treatment furnace will be specifically described with reference to FIG.

First, in order to easily fix the furnace shell side formed heat insulating material 30 to the furnace shell 2, it is divided into a plurality of parts and each of the furnace shell side formed heat insulating materials 30 is provided with a pull-out preventing nut 41 on the furnace shell 2 side. Hole 30a for embedding, and hole 30b for embedding boss 35
To process. In addition, the furnace shell side formed heat insulating material 3 (not shown)
In the same manner as the joint of the heat treatment chamber-side molded heat insulating material 31 shown in FIG. 2, a joint 31 is provided with a gap 31a so that the formed heat insulating materials do not abut each other at a half-thickness position, and has different stair-like joint positions. It is processed in.

On the other hand, the heat-treating-chamber-side molded heat insulating material 31 is processed in a stepwise manner with a gap 31a provided so that the formed heat insulating materials do not abut each other at half the thickness, and the boss 35 is embedded. The hole 30b is 5 to 5 times larger than the outer diameter of the boss 35.
By increasing the inner diameter of 15 mm and providing a slight gap between the hole and the boss, the molded heat insulating material 3 accompanying the rise and fall of the heat treatment furnace 3
The first expansion / contraction force is not directly applied to the boss 35.

After the above processing is completed in advance, graphite cement is applied to the outer peripheral surface of the boss 35 on the furnace shell side molded heat insulating material 30 outside the furnace, and then the boss 35 is embedded to the hole 30a end face.
A bolt 36 made of a carbon material or a c / c composite is penetrated into the boss 35, a pull-out prevention nut 41 is screwed into the boss 35, and assembled inside the furnace shell 2.

Next, the heat treatment room-side formed heat insulating material 31 divided into a plurality of pieces is assembled according to a predetermined procedure.
The number of divisions is preferably larger than that of the furnace shell-side formed heat insulating material 30 from the viewpoint of preventing and reducing warpage, and the relationship between the length (L) of one side of the heat treatment room-side formed heat insulating material 31 and the thickness (t). Is L ≦ 7
If t, the shape may be any of a square, a rectangle, and the like. Here, it is not preferable that the length (L) of one side of the heat-treating-chamber-side formed heat insulating material 31 exceeds seven times the thickness (t) of the formed heat insulating material since the warpage of the formed heat insulating material becomes large.

After such preparation is completed, the heat-treating-chamber-side heat insulating material 31 having a convex side in contact with the furnace-shell-side heat-insulating material 30 is mounted on the boss 35 protruding from the furnace-shell-side heat-insulating material 30. Then, a molded felt 39 made of graphite is filled as an absorbing material in a gap portion of the joint.

Next, the heat-treating-chamber-side formed heat insulating material 31 having a concave side in contact with the furnace-shell-side formed heat insulating material 30 is transferred to the boss 35.
, A flexible sheet-like protective material 40 is stretched, and a nut 37 made of a carbon material or a c / c composite is screwed and fixed through a graphite plate 42 to be integrated.

FIG. 4 is an overall right side view in which the heat insulation in the heat treatment chamber has been completed by the above procedure (illustration of the furnace wall 2 and the flexible sheet-like protective material 40 on the inner wall is omitted). The left side shows a state in which the flexible sheet-like protective material 40 has been peeled off, and the heat-treating-room-side formed heat insulating material 31 divided into rectangles.
(6 parts in the figure) are fixed together with the flexible sheet-like protective material 40 by a plurality of the fixing members (7 places in the figure) per division, and four adjacent heat treatment chamber-side formed heat insulations. The joints (two places in the figure) at the four corners of the material 31 are further fixed via a contact plate 42. The fixing at the portions where the sides of the divided heat treatment chamber-side formed heat insulating material 31 are adjacent to each other (four places in the figure) is basically the same as the method of fixing the above-mentioned four corner joints. ′
Are the same except for the size of

Further, the heat treatment chamber-side molding heat insulating material 31 is prevented from warping, and apparently has a heat insulating wall formed integrally in the thickness direction to improve rigidity and to form a furnace shell having a small thermal deformation force. To form the heat insulating material, graphite L-shaped component members 4 are formed around the four corners of the heat treatment room side formed heat insulating material 31.
3 and 43 'are disposed, and at each of the four corners, a plate-like splicing member 44 made of graphite is fixed.
The constituent members 43 and 43 'constitute an L-shaped member. This
As shown in the figure, the heat-insulating chamber side molded heat insulating material
31 is fixed to the furnace shell side molded heat insulating material 30 together with the flexible sheet-shaped protective material 40.

In the above-described embodiment, the joint between the furnace shell-side molded heat insulating materials 30 (not shown) and the joint between the heat treatment chamber-side molded heat insulating materials 31 (not shown) are stair-stepped at half the thickness as shown. The present invention is not limited to the embodiment processed into a shape, and may be processed stepwise in a state where the thickness is different from each other. Heat treatment room 5 for side molded heat insulating material 31
When a protective material such as a flexible sheet-like protective material 40 is stretched on the side, the formed heat insulating materials may be joints separated by a gap between straight surfaces in the thickness direction. In addition, the staggered length at the joining position when processed into a stepped shape as shown is preferably 100 mm or less, and more preferably 50 mm or less, from the viewpoint of suppressing the warpage of the formed heat insulating material. Further, in this embodiment, the heat insulating material is shown as having two layers of the furnace shell side formed heat insulating material 30 and the heat treatment room side formed heat insulating material 31, but at least two layers are sufficient. It may be a layer.

The joining position between the flexible sheet-like protective members 40 does not match the joining position of the heat-insulating material 31 formed in the heat treatment chamber in order to prevent the harmful gas generated in the heat treatment chamber 5 from passing through.
It is preferable to shift the position. Also, the joint is 100-2
It is preferable to overlap them in a range of about 00 mm. Further, the place where the flexible sheet-like protective material 40 is stretched is a heat treatment room side formed heat insulating material 31 facing the heat treatment room 5 side as shown in the figure.
The flexible sheet-like protective material 40 may be further stretched on the boundary surface between the furnace shell-side molded heat insulating material 30 and the heat treatment room-side molded heat insulating material 31 without being limited to the mode of stretching the flexible sheet-shaped protective material 40. . Further, the stretching of the flexible sheet-like protective material 40 is not limited to one, and a plurality of flexible sheet-like protective members 40 may of course be overlapped.

The material 4 to be treated in the heat treatment furnace of the present invention is not particularly limited. For example, a c / c composite or a graphite material used for an electrode substrate of a fuel cell can be treated. it can.

The heat treatment furnace 1 shown in FIGS. 1 to 4 has a furnace shell size of 2 m in width, 1.3 m in height, and 2 m in depth. Furnace shell side heat insulating material 30 and thickness 1 treated at 2400 ° C.
A heat-insulating chamber-side heat insulating material 31 having a rectangular shape of
The heat insulating material 3 was configured by being divided. The flexible sheet-like protective material 40 is made of graphite “Carbofit” having a bending elastic modulus of 0.5 Ton / mm ² or less, a thickness of 1.5 mm, and a material of graphite. Stretched in layers. The pull-out prevention nut 41 and the contact plate 42 are made of graphite, and the bolt 36
The nut 37 is made of a c / c composite to form the heat insulating material 3.

The heat treatment furnace 1 having such a heat insulating wall structure 3 was repeatedly heated and lowered up to a maximum heat treatment temperature of 2500 ° C. 50 times in an inert gas atmosphere. No abnormality was particularly observed in the shape protection material 40.

[0040]

[Comparative example]

Comparative Example 1 In the heat treatment furnace 1 shown in FIGS. 1 to 4, the same heat treated material and fixed member as those in the above embodiment except that the furnace shell side formed heat insulating material 30 and the heat treatment room side formed heat insulating material 31 were divided into three parts. And a heat insulating wall structure 3 made of a flexible sheet-like protective material 40. 150 mm thick furnace shell side formed heat insulating material 30 forming a heat treatment chamber
The size of one ceiling and floor is 665 mm long,
The size of one piece of the ceiling and floor of the heat treatment room side formed heat insulating material 31 having a width of 2000 mm and a thickness of 100 mm is 615 mm in height and 1700 mm in width, and the size per piece of furnace wall is 580 mm in height and width. In each case of 800 mm, the length (L) of one side exceeded seven times the thickness (t) of each single-layer heat insulating material. Then, as a result of repeated operation under the same heat treatment conditions as in the above-described embodiment, a part of the fixing member, the c / c composite bolt 36, was damaged due to warpage at the joint after 12 batches. The undulation of the flexible sheet-like protective material 40 also became large, causing temperature unevenness in the heat treatment chamber, and the life as a heat insulating material was reached by warping at the 29th batch.

COMPARATIVE EXAMPLE 2 The heat insulating wall structure 3 of the heat treatment furnace 1 shown in FIG. 1 does not have a contact plate or an L-shaped member at the divided joint portion and the peripheral portion of the heat insulating material. The conventional structure as shown in the figure was adopted. That is, the heat-insulating chamber-side formed heat insulating material 31 is divided into three rectangular shapes, and a "K sheet" having a bending elastic modulus of 1 Ton / mm ² and a thickness of 1.2 mm is formed as a protective layer 33 by a sheet-like c / c composite.
(Made by Kureha Chemical Co., Ltd.), and the seat 38 is made of graphite.
The bolts and nuts 36 and 37 were repeatedly operated under the same heat treatment conditions as in the above example except that a fixing member made of c / c composite was used. The split joint and the peripheral portion began to warp toward the heat treatment chamber, and undulation was observed in the “K sheet”. The warpage of the heat-treating-chamber-side molded heat insulating material 31 further progressed due to the repetition of the temperature increase and decrease, and the "K sheet" was damaged after 10 batches. In the 23rd batch, the life as a heat insulating material was reached due to the warpage, so that the heat treatment could not be continued.

[0042]

As described above, the heat insulating material of the heat treatment furnace is composed of at least two layers of the heat insulating material on the furnace shell side and the heat insulating material on the heat treatment room side. The rate is 0.5 Ton / mm ² or less and the thickness is 3
mm or less flexible sheet-like protective material is stretched, and the joint between the four corners of the heat-insulating material and the portion where the sides are adjacent to each other are fixed to the furnace shell side by a fixing member via a plate and an L-shaped member. Therefore, even at a high temperature of 2500 ° C. or more, a furnace wall having an excellent heat insulating structure, which does not warp the heat insulating material and does not cause troubles such as deterioration and wear and adsorption of pyrolysis gas, can be easily obtained.

Further, even when the heat treatment conditions are high temperature and severe conditions for a long time, the number of the heat insulating materials is increased to reduce the area per one sheet and the flexible sheet-like protective material. The warp of each heat insulating material can be made small because of the extension.

Therefore, the heat treatment furnace of the present invention can provide an excellent effect that a long-time high-temperature treatment of an object to be processed can be performed and a replacement cycle of the heat insulating material is lengthened.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of a heat treatment furnace according to the present invention.

FIG. 2 is an enlarged sectional view of the heat insulating wall of FIG.

FIG. 3 is a right side view of the heat insulating wall of FIG. 2;

FIG. 4 is an overall right side view of the heat insulating wall of FIG. 2;

FIG. 5 is a partial sectional view of a heat insulating wall structure of a conventional heat treatment furnace.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 heat treatment furnace 30 furnace shell side formed heat insulating material 2 furnace shell 31 heat treated room side formed heat insulating material 3 heat insulating wall structure 32 through hole 4 processed object 33 protective layer 5 heat treatment room 34 graphite plate 6 resistance heating element 35 boss 7 electrode 36 bolt Reference Signs List 8 power supply terminal part 37 nut 9 support material 38 seat 10 air supply port 39 molded felt 11 solenoid valve 40 flexible sheet-like protective material 12 exhaust port 41 pull-out prevention nut 13 radiation thermometer 42, 42 'this plate 14 viewing window 43, 43 'L
Shaped component 15 Heating controller 44 Splicing member 16 Door G Inert gas

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F27B 17/00 F27D 1/00 F27D 1/14

Claims (3)

(57) [Claims] 1. A resistance heating element for heating an object to be processed, and a heat treatment chamber surrounding the object to be processed and the resistance heating element and having a heat insulating material fixed on an inner surface thereof. In a heat treatment furnace for heat-treating the object by radiated heat, (a) the heat insulating material is laminated on a furnace shell side molded heat insulating material fixed to a furnace shell, and on the furnace shell side formed heat insulating material, It is composed of at least two layers of the heat treatment chamber-side molded heat insulating material divided into a plurality of pieces facing the heat treatment chamber, and (b) the surface of the heat treatment chamber-side molded heat insulator has a flexural modulus of 0.5 Ton / mm ² or less. And the thickness is 3
by joining a flexible sheet-like protective material that is divided into a plurality consisting mm or less graphite stretched in a planar shape, (c) wherein the junction of the heat treatment chamber side molding insulation, said Allowed
An aforesaid plate made of graphite is provided via a flexible sheet-like protective material, and an L-shaped member made of graphite is provided around the heat-insulating material on the side of the heat treatment chamber. A heat treatment furnace, wherein a member is fixed to a surface of the furnace shell side formed heat insulating material by a fixing member. 2. The heat insulating material on the furnace shell side, the heat insulating material on the heat treatment chamber side, the flexible sheet-like protective material, the plate and the L-shaped member,
2. The heat treatment furnace according to claim 1, wherein the boss is made of graphite and is integrally fixed by a fixing member having a pull-out preventing structure comprising a bolt and a nut made of graphite or c / c composite. . 3. The heat insulating material on the furnace shell side or the heat insulating material on the heat treatment chamber side has a rectangular shape after joining, and the relationship between the length (L) and the thickness (t) of the long side is L ≦ L. The heat treatment furnace according to claim 1, wherein the heat treatment furnace is 7t.