JP2014066468A - Heat treatment furnace and reflector thermal insulation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat treatment furnace including a reflector thermal insulation material in which thermal insulation performance and heat reflectivity are not deteriorated even when the material is used for a long period under a high-temperature carburization atmosphere or an oxidation atmosphere.SOLUTION: A heat treatment furnace 10 for treating a treatment object 20 with heat includes a reflector thermal insulation material 1 in the furnace. In the reflector thermal insulation material 1, a plurality of reflectors R for reflecting heat are arranged so that respective faces are parallel with each other and stored in an airtight case 2. Even when the inside of the heat treatment furnace 10 is under a high-temperature carburization atmosphere or under an oxidation atmosphere, heat reflectivity and thermal insulation performance can be maintained without carburizing or oxidizing the reflectors R of the reflector thermal insulation material 1.

Description

  The present invention relates to a heat treatment furnace and a reflector heat insulating material used in the heat treatment furnace.

  Conventionally, it has been proposed that a furnace body such as a heating furnace or a heat treatment furnace is provided with a heat insulating layer along an outer wall and further uses a heat reflecting plate for the purpose of energy saving.

  Patent Document 1 discloses a heat treatment furnace used for carburizing treatment, nitriding treatment, or the like in which a furnace body is configured by a ceramic fiber layer, a heat insulating layer made of a silica-based ceramic block, and a furnace shell layer in order from the inside of the furnace. Yes.

  In Patent Document 2, a refractory heat-insulating brick having an iron content of 1% by weight or less is used as the first layer, and carburizing treatment or nitriding having a heat insulating structure made of a heat insulating material such as a microporous structure made of amorphous silica after the second layer. A heat treatment furnace used for processing or the like is disclosed.

  And in patent document 3, the heat processing furnace used for the baking etc. of the ceramic body which has the heat insulation structure provided with the reflector formed by laminating | stacking a several reflector in the furnace inside of the casing in which the heat insulating material was provided is disclosed. Has been.

JP 2007-93160 A Japanese Patent Laid-Open No. 9-79761 JP 2012-21742 A

  However, in a high-temperature atmosphere furnace in which the maximum operating temperature is 800 to 1100 ° C., it is a problem to suppress deterioration of the heat insulating material in the carburizing atmosphere or the oxidizing atmosphere.

  In the structure of the furnace described in Patent Documents 1 and 2, there is a problem of contamination due to divergence of the heat insulating material and deterioration of heat insulating performance due to moisture adsorbed on the heat insulating material. Furthermore, the fine porous structure heat insulating material is extremely brittle and has low durability. Moreover, the heat treatment furnace used for the carburizing process and the nitriding process described in these patent documents is not provided with a heat reflecting plate.

  In the heat treatment furnace described in Patent Document 3, the heat insulating material by a plurality of reflectors can maintain the initial reflectivity and heat insulating performance in an inert gas or in a vacuum, but a high-temperature carburizing atmosphere or oxidizing atmosphere Among them, the reflector plate is carburized or oxidized to discolor, and the heat insulation effect is greatly reduced. Further, the heat reflectance is lowered, and the intended energy saving effect cannot be expected. Further, when the gas in the furnace is heat-treated while being stirred with a fan, it is easily affected by convection between the reflectors.

  On the other hand, in order to cope with the downsizing of the furnace, it is desirable that the thickness of the heat insulating layer is equal to or thinner than the conventional one. In addition, conventional small heat treatment furnaces have poor workability due to the narrow inside of the furnace, and care must be taken not to break the outer wall (furnace shell) and the brittle microporous insulation material during maintenance. It is necessary to remove. Therefore, it is desirable to improve maintainability.

  The object of the present invention has been made in view of these circumstances, and even when used for a long time in a high-temperature carburizing atmosphere or an oxidizing atmosphere, the heat insulating performance and the heat insulation performance of the reflector are not reduced. It is to provide a heat treatment furnace including the same.

  In order to solve the above problems, the present invention is a heat treatment furnace for heat-treating an object to be processed, and includes a reflector heat insulating material in the furnace, and the reflector heat insulating material includes a plurality of reflectors that reflect heat, Provided is a heat treatment furnace characterized in that the surfaces are arranged in parallel with an interval and are housed in a sealed case.

  The heat treatment furnace may include a furnace shell layer covering an outer periphery, a heat insulating layer provided inside the furnace shell layer, and the reflector heat insulating material provided inside the heat insulating layer.

  Moreover, the said reflector heat insulating material may be installed in the side wall and ceiling surface in a furnace. Furthermore, an atmosphere stirring fan may be provided in the furnace. And the said to-be-processed object may be heat-processed in 850 degreeC or more carburizing atmosphere.

  The reflector heat insulating material may be provided with a gas inlet and an outlet for circulating an inert gas or a reducing gas. The plurality of reflectors of the reflector heat insulating material may be made of a nickel base alloy super heat-resistant alloy having a heat reflectance of 50% or more on the furnace inner side and stainless steel on the furnace outer side.

  Further, the present invention provides a reflector heat insulating material, characterized in that a plurality of reflectors that reflect heat are arranged in parallel and spaced from each other and housed in a sealed case. provide.

  According to the present invention, even if the inside of the heat treatment furnace is in a high-temperature carburizing atmosphere or oxidizing atmosphere, the reflecting plate of the reflecting plate heat insulating material is hardly carburized or oxidized, and the heat reflectivity and heat insulating performance can be maintained.

It is sectional drawing which shows the example of the reflecting plate heat insulating material concerning this invention. It is sectional drawing which shows the example from which the reflecting plate heat insulating material concerning this invention differs. It is sectional drawing which shows the example of the heat processing furnace concerning this invention. It is sectional drawing which shows the example from which the heat processing furnace concerning this invention differs. It is sectional drawing which shows the reflecting plate heat insulating material used in the Example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 shows an example of an embodiment of a reflector heat insulating material according to the present invention.

  The reflector heat insulating material 1 is composed of a rectangular parallelepiped case 2 and a plurality of reflectors R housed therein. The material of the case 2 is, for example, stainless steel excellent in heat resistance and oxidation resistance, and SUS310 or the like is used. The plurality of reflectors R are housed in parallel inside the case 2 with a predetermined interval and are supported by the support member 3 at the top and bottom. The plurality of reflectors R are preferably parallel to each other, but may be substantially parallel, even if not strictly parallel.

  The case 2 includes a main body having an opening on one surface of a rectangular parallelepiped and a lid that closes the opening surface. For example, in FIG. 1, one surface on the front side or the back side is an opening surface, and a plurality of reflecting plates R are inserted into the main body of the case 2 with the lid open, and each reflecting plate is matched with the position of the support member 3. After accommodating R in a predetermined position, the opening surface is closed with a lid. The lid may be attached so as to completely seal the gap by welding or brazing, but may not be sealed in a completely airtight state. The lid only needs to be able to substantially suppress the intrusion of carburizing gas or oxidizing gas into the case 2 in the furnace, and in consideration of maintainability, the lid may be simply fitted or fixed by screwing or the like.

  The material of the reflecting plate R is a metal plate that has excellent heat resistance and high heat reflectivity, and stainless steel, heat resistant alloys, and the like are suitable. A plurality of reflectors R may be used, and the material of the reflector R may be changed between the high temperature part and the low temperature part. In a high temperature portion (in this specification, a temperature range of about 700 ° C. to 1000 ° C.) of the furnace inner side 11, in a material having a small thermal reflectance deterioration with time even in an oxidizing gas or a carburizing gas, for example, in a carburizing gas atmosphere at 950 ° C. It is preferable that the heat reflectance after holding for one week is 50% or more. Specifically, a nickel base alloy super heat resistant alloy such as “Hanes Alloy” (registered trademark) is preferable. Although it is not carburized in the low temperature part (the temperature range below 700 ° C. in this specification) of the furnace outer side 12, it is a temperature range where oxidation occurs, and therefore, stainless steel that is difficult to oxidize, such as SUS304 or SUS310, is used. Is preferred. Further, in a temperature region where the temperature is low and is not easily oxidized, it is preferable to use a stainless steel that has been subjected to Ag plating or the like to increase the heat reflectance. The total number of reflectors R is preferably about 8 to 12. If the number is too small, the heat insulation effect is lowered. On the other hand, if the number is too large, the case 2 that houses the reflector R becomes thick and requires a lot of space in the furnace, which makes it difficult to use in a small heat treatment furnace. Furthermore, it is preferable to dispose a black body plate between the plurality of reflectors in the low temperature part. Black body plates are made by applying a heat-resistant black body paint to the surface of a commercially available black iron plate or SUS, etc., and it has been found that the heat insulation effect is further improved compared to the case where only a reflector plate is arranged. It was.

  Further, the interval between the reflecting plates R in the case 2 is preferably 0.5 cm to 5 cm, and more preferably 1 cm to 4 cm. If the interval is too narrow, the reflecting plates R may come into contact with each other when they are thermally deformed, resulting in a decrease in heat insulation. If it is too wide, the case 2 becomes too thick.

  In the reflector heat insulating material 1 of the present invention having the above-described configuration, the plurality of reflectors R are accommodated in the substantially sealed case 2, so that intrusion of oxidizing gas or carburizing gas is prevented. Or it suppresses and the oxidation and carburization of the reflecting plate in case 2 are prevented. In addition, even if the outer surface of the case 2 turns black due to oxidation or carburization, the reflection plate R in the case 2 can maintain heat reflection and heat insulation effects.

  Although the case 2 is substantially sealed, the atmospheric gas in the furnace may enter the case 2 from the gap between the lid and the main body due to thermal expansion or the like. Therefore, as shown in FIG. 2, the case 2 is provided with a gas inlet 4 and an outlet 5 for circulating an inert gas or a reducing gas, and the inert gas or the reducing gas flows through the atmosphere in the case 2. This may be controlled to suppress discoloration of the reflector R.

  Furthermore, as shown in FIG. 2, a heat insulating material 6 may be further attached to the outside of the case 2 on the furnace outer side 12 to suppress heat radiation due to heat conduction from the outer periphery of the case 2 to the outside. As this heat insulating material 6, what has been used as a conventional heat insulating material such as a vacuum heat insulating panel or a porous heat insulating material may be used.

  Moreover, in this invention, you may comprise the reflector heat insulating material 1 by the separate case of multiple (for example, two pieces) by the furnace inner side 11 and the furnace outer side 12. FIG. For example, a reflector R made of a nickel-base alloy super heat-resistant alloy or the like is accommodated in the case of the reflector insulating material 1 inside the furnace 11, and SUS304 or SUS310 is contained in the case of the reflector insulating material 1 outside the furnace 12. A reflector R made of, for example, is accommodated. Also in this case, heat radiation due to heat conduction to the outside can be suppressed as in the above embodiment. Moreover, it is preferable to arrange | position heat insulating materials, such as a felt-like heat insulation packing seal, between several cases (connection part), and solid heat conduction is suppressed by this, and heat insulation performance can further be improved.

  FIG. 3 shows an example of a high-temperature heat treatment furnace 10 using the reflector heat insulating material 1 according to the present invention. A heat insulating layer 22 made of, for example, a vacuum heat insulating material or a porous heat insulating material is formed on the ceiling and side walls inside the furnace shell 21 made of a metal material such as iron or stainless steel that forms the outer surface of the heat treatment furnace 10. ing. A heat insulating structural member 23 such as a ceramic block or a heat-resistant brick is disposed on the floor. And the reflector heat insulating material 1 of this invention shown, for example in FIG. 1 or FIG. 2 is provided in the inner surface of the heat insulation layer 22 of a ceiling part and a side wall part. Although it is effective to provide the reflector heat insulating material 1 as much as possible on the entire surface of the ceiling and side walls so as to surround the heat treatment chamber 24 inside the heat treatment furnace 10, it is not always necessary to cover the entire surface. Moreover, it is preferable that the surface of the reflector R inside the case of the reflector heat insulating material 1 is substantially parallel to the surface of the ceiling part or the side wall part of the heat treatment chamber 24 so as to increase the reflection effect. In the heat treatment chamber 24, for example, a heater 25 is provided so as to surround the object 20 to be processed, and the heat treatment chamber 24 is heated to 800 ° C. to 1100 ° C., preferably about 850 ° C. to 1050 ° C. in the carburizing treatment. A heat treatment such as carburization is performed on the workpiece 20 carried into the chamber 24.

  FIG. 4 shows an example of a different embodiment of the high-temperature heat treatment furnace 30 according to the present invention. In addition to the configuration of FIG. 3, a fan 26 for stirring the atmosphere is provided in the upper part of the furnace. Conventionally, in a heat treatment furnace using a reflector heat insulating material composed of a plurality of reflectors, by stirring the atmosphere, there has been a problem that the treatment gas flows between the reflector plates R and the heat insulation is reduced, In the present invention, since the reflecting plate R is covered with the case 2, the processing gas having a relatively low temperature does not enter between the reflecting plates R, and heat insulation can be maintained. Further, convection does not occur between the plurality of reflectors, and the atmosphere and temperature distribution in the furnace are not affected. Moreover, since the entire case 2 can be taken out during maintenance, replacement can be performed without working for a long time in the furnace.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

[Invention Example 1]
As the reflective heat insulating material 1 shown in FIG. 5, a rectangular parallelepiped case 2 made of SUS310S having a thickness of 1 mm and a case lid made of the same material were prepared. In this case 2, there are 10 reflectors made of SUS304 (R1 in FIG. 5, 2 R2, 2 R3, 4 R4), and the support member makes the surface of the reflector plate surface. After being held in parallel so as to be substantially parallel to each other, the case was covered and sealed. The thickness of all the reflectors is 1.0 mm, and the interval between the first to sixth reflectors (R1, R2, R3) from the inside of the furnace is 10 mm, and the sixth and seventh sheets from the inside of the furnace. The distance between the reflectors (the outer side of the furnace of R3 and the innermost side of the furnace of R4) was 30 mm, and the distance between the seventh and tenth reflectors from the inner side of the furnace was 20 mm. Also, the inner surface of the case 2 and the first reflector from the inner side of the furnace (the outer side of the furnace R1), the outer surface of the case 2 and the tenth reflector from the inner side of the furnace (the outermost side of the furnace R4). The interval was set to 20 mm. That is, the thickness of the reflector heat insulating material 1 was 192 mm (20 cm or less).

After the reflector heat insulating material 1 having the above structure is exposed to a carburizing atmosphere and a temperature of 950 ° C. for one week (the surface of the case 2 turns black), the surface temperature of the case 2 inside the furnace 11 of the reflector heat insulating material 1 When the radiant heat energy released from the surface of the case 2 on the outside 12 of the furnace when the temperature was 950 ° C. was calculated, it was about 21 W / m ² .

[Invention Example 2]
As shown in FIG. 5, in order from the inside of the furnace, two reflectors R1 made of Haynes alloy, two reflectors R2 made of SUS304, two reflectors R3 having a mirror polished surface of SUS304, and the surface of SUS304 A reflector heat insulating material similar to that of Example 1 of the present invention was prepared except that four reflectors R4 plated with Ag and four reflectors R in total were attached to the inside of the case 2.

The radiant heat energy released from the surface of the case 2 on the outside 12 of the furnace was calculated under the same conditions as in Example 1 of the present invention, and it was about 14 W / m ² .

[Invention Example 3]
In order from the inside of the furnace, two reflection plates R1 made of Haynes alloy, two reflection plates R2 made of SUS304, two reflection plates R3 whose surfaces of SUS304 are mirror-polished, and reflection with Ag plating on the surface of SUS304 A reflective heat insulating material similar to Example 1 of the present invention was produced except that three plates R4 and a total of nine reflectors R were attached to the inside of the case 2.

When the radiant heat energy from the surface of the case 2 on the outside 12 of the furnace was calculated under the same conditions as in Example 1 of the present invention, it was about 20 W / m ² . That is, even in the present invention example 3 in which the thickness of the reflective heat insulating material of the present invention example 1 was reduced by 21 mm (about 10%), the heat insulation equivalent to or higher than that of the present invention example 1 was obtained.

[Invention Example 4]
In order from the inside of the furnace, two reflectors R1 made of Haynes alloy, two reflectors R2 made of SUS304, two reflectors R3 having a mirror-polished surface of SUS304, and a black body paint were applied to the surface of SUS304. One black plate (7th from the furnace inner side 12), 3 reflectors R4 (8th, 9th, 10th from the furnace inner side 12) with SUS304 surface plated with Ag A reflective heat insulating material similar to that of the present invention example 1 was produced except that a total of ten reflectors R were attached to the inside of the case 2.

When the radiant heat energy from the surface of the case 2 on the furnace outer side 12 was calculated under the same conditions as in Example 1 of the present invention, it was about 5 W / m ² . It was found that the heat insulation performance was greatly improved by arranging the black body plate between the plurality of reflectors.

[Invention Example 5]
In order from the inside of the furnace, two reflectors R1 made of Haynes alloy, two reflectors R2 made of SUS304, two reflectors R3 having a mirror-polished surface of SUS304, and a black body paint were applied to the surface of SUS304. One reflector R4 (seventh from the furnace inner side 12) made of black body, one reflector R4 (8th from the furnace inner side 12) with Ag plating on the surface of SUS304, a total of eight reflectors A reflective heat insulating material similar to Example 1 of the present invention was produced except that the plate R was attached to the inside of the case 2.

When the radiant heat energy from the surface of the case 2 on the outside 12 of the furnace was calculated under the same conditions as in Example 1 of the present invention, it was about 17 W / m ² . In other words, the present invention example 5 in which the thickness of the reflective heat insulating material of the present invention example 1 is reduced by 42 mm (about 20%) by disposing the black body plate between the plurality of reflectors is equivalent to that of the present invention example 1. The above heat insulation was obtained.

  In addition, a heat insulating material 6 of a vacuum heat insulating panel having a thickness of 5 cm is attached to the outside of the case 2 on the furnace outer side 12 of the reflective heat insulating material 1 of Invention Examples 1 to 5, and the heat treatment furnace having the structure shown in FIG. 3 or FIG. By constructing 10, it is possible to provide a heat treatment furnace having excellent heat insulation performance and maintainability.

[Comparative example]
As a comparative example, a reflector heat insulating material 1 was produced in which ten reflectors were held inside a case 2 having the same structure as that of Example 1 except that the reflector R was not accommodated in the case 2.

When the radiant heat energy from the surface of the reflector 12 on the outside 12 of the furnace was calculated under the same conditions as in Example 1 of the present invention, it was about 2000 W / m ² . This is because the reflector has become a black body (black) due to carburization and thus does not serve as a heat insulating material.

In addition, as a reference example, a 200 μm thick heat insulating material “Microtherm” (registered trademark) made of amorphous silica or the like was used instead of the reflector heat insulating material 1 and exposed to the same heat conditions. . In this case, the heat dissipated on the surface of the microtherm on the outside 12 of the furnace (including heat dissipation due to heat conduction in addition to radiant energy) was about 2100 W / m ² .

  The present invention can be applied to a heat treatment furnace such as high-temperature carburizing treatment or oxidation treatment.

DESCRIPTION OF SYMBOLS 1 Reflection board heat insulating material 2 Case 3 Support member 10, 30 Heat treatment furnace 11 Furnace inner side 12 Furnace outer side 20 To-be-processed object 21 Furnace shell 22 Thermal insulation layer 23 Thermal insulation structural material 24 Heat treatment chamber 25 Heater 26 Fan R Reflector

Claims (8)

A heat treatment furnace for heat-treating a workpiece,
Reflector heat insulation in the furnace,
The heat treatment furnace characterized in that the reflection plate heat insulating material includes a plurality of reflection plates that reflect heat, the surfaces are arranged in parallel at intervals and are accommodated in a sealed case.   The furnace shell layer which covers outer periphery, the heat insulation layer provided inside the said furnace shell layer, and the said reflector heat insulating material provided inside the said heat insulation layer, It is characterized by the above-mentioned. Heat treatment furnace.   The heat treatment furnace according to claim 1, wherein the reflector heat insulating material is installed on a side wall and a ceiling surface in the furnace.   The heat treatment furnace according to any one of claims 1 to 3, wherein an atmosphere stirring fan is provided in the furnace.   The heat treatment furnace according to any one of claims 1 to 4, wherein the object to be treated is heat-treated in a carburized atmosphere at 850 ° C or higher.   The heat treatment furnace according to claim 1, wherein the reflector heat insulating material is provided with a gas inlet and an outlet for circulating an inert gas or a reducing gas.   The plurality of reflecting plates of the reflecting plate heat insulating material are made of a nickel base alloy super heat-resistant alloy having a heat reflectance of 50% or more on the inside of the furnace and made of stainless steel on the outside of the furnace. The heat treatment furnace in any one of.   A reflector heat insulating material characterized in that a plurality of reflectors that reflect heat are arranged in parallel with each other in parallel and are housed in a sealed case.

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