JP2005195238A - Heat treatment furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the property dispersion of a heated object by suppressing the escape of heat from a heat treatment space through supporting columns to the outside to suppress the temperature dispersion of the heated object. <P>SOLUTION: This heat treatment furnace comprises a furnace body 10 having a heat treatment space inside, a hearth 14 formed of a light heat insulating material and arranged on the bottom of the furnace body 10, a plurality of supporting columns 17 each having a lower end terminated inside the hearth 14 and an upper end exposed to the upper face of the hearth 14, a bed plate 18 on which the heated object W arranged on the supporting columns is placed, and a supporting material 19 arranged inside the hearth 14 for supporting the plurality of supporting columns 17 at their lower ends and having strength greater than the light heat insulating material. The supporting columns 17 are constructed to be stopped inside without passing through the bottom face of the hearth 14, thus suppressing the radiation of heat. The supporting material 19 supports the supporting columns 17 at their lower faces to prevent the sink-down of the supporting columns 17. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a heat treatment furnace, and more particularly to a heat treatment furnace of a type in which a base plate on which an object to be heated is placed is supported by a support.

Conventionally, what was described in patent document 1 is known as a bogie structure of a continuous furnace. FIG. 1 shows the structure, and reference numeral 1 denotes a transporting carriage on which the article to be heated W is placed and moved in a continuous furnace in a high temperature atmosphere. The bogie body 2 is made of a lightweight heat insulating material such as ceramic fiber, a support 3 made of hard heat insulating material is fixed to the bogie main body 2 in a penetrating state, and a plate-shaped cradle made of hard heat insulating material on the upper end of the support 3 4 is arranged, and the article W to be heated is placed on the cradle 4. The lower end portion of the column 3 is supported by a casing 5 disposed on the lower surface of the carriage body 2. The casing 5 is made of a hard material such as metal.

Although the lightweight heat insulating material itself of the carriage main body 2 is excellent in heat insulation, the column 3 arranged so as to penetrate the carriage main body 2 is inferior in heat insulation compared to the carriage main body 2. Although the support 3 is heated by passing through the furnace, heat is radiated through the support 3 and the casing 5, and the temperature in the vicinity of the support W of the article to be heated W is lowered, causing a temperature variation in the article to be heated W. For example, when used as a firing furnace for ceramic parts, the temperature variation affects the characteristics of the ceramic parts accommodated in the object to be heated.

The heat treatment furnace relates to a continuous furnace in which the bogie body is made of a lightweight heat insulating material, but there is a similar problem in a batch furnace in which the hearth is made of a light heat insulating material. That is, a hearth made of a lightweight heat insulating material is arranged at the bottom of the furnace body, a column is arranged in a through state in this hearth, a base plate for placing an object to be heated is arranged on the column, This is a case where the lower end is supported by a casing disposed on the lower surface of the hearth. Also in this case, heat is radiated through the support column and the casing, the temperature of the heated object in the vicinity of the support column is lowered, and this causes a temperature variation in the heated object.
Japanese Patent No. 3012906

Accordingly, an object of the present invention is to provide a heat treatment furnace capable of suppressing heat escaping from the heat treatment space through the support column to the outside, suppressing temperature variation of the heated object, and eliminating characteristic variation of the heated object. .

In order to achieve the above object, an invention according to claim 1 is directed to a furnace body having a heat treatment space therein, a hearth made of heat insulating material disposed at the bottom of the furnace body, and a lower end inside the furnace floor. It supports the lower end of the column, the column that is disposed so that the upper end is exposed on the upper surface of the hearth, the base plate that is disposed on the column, and on which the object to be heated is placed. And a support material that is disposed inside the hearth, has a larger area than the lower end surface of the support column, and has higher strength than the heat insulating material.

Moreover, the invention which concerns on Claim 5 is arrange | positioned at the bottom part of the furnace main body which has the heat processing space inside, and the said furnace main body, an upper side consists of a 1st heat insulating material, and a lower side is stronger than a said 1st heat insulating material. A hearth made of a high second heat insulating material, and a support column penetrating through the first heat insulating material so that the lower end is in contact with the second heat insulating material and the upper end is exposed on the upper surface of the hearth; A heat treatment furnace comprising: a base plate for placing an object to be heated, which is disposed on the support column.

In a heat treatment furnace composed of a heat-resistant material, a heat insulating effect is enhanced by using a lightweight heat insulating material for the hearth. A lightweight heat insulating material has a drawback that it has a low heat capacity but is inferior in load resistance. For this reason, the support | pillar for supporting a to-be-heated material is arrange | positioned inside a hearth, and a to-be-heated material is mounted on the base plate arrange | positioned on a support | pillar, and heat processing is performed.
Heat treatment is performed with a heating element such as a heater or a heating source such as hot air during heat treatment, but the amount of heat released through the support is large. The poor followability of the temperature rise in the vicinity of the column of the object to be heated is a cause of variations in the characteristics of the object to be heated.
In Claim 1, it is set as the structure which does not penetrate a support | pillar to the bottom face of a hearth but stops inside. However, in a structure that is simply stopped halfway, the heat insulating material that contacts the lower end surface of the support may not be able to support the weight of the support. Therefore, the support is stopped inside the hearth, and a support material having a strength higher than that of the heat insulating material is disposed on the lower surface of the support, and the support material supports the weight of the support. Thereby, sinking of a support | pillar can be prevented and the inclination of a baseplate can be suppressed.
Further, even if the support is heated, the lower end of the support is terminated by a support material provided inside the hearth, so that the amount of heat radiation is small and the temperature variation in the object to be heated can be reduced. As a result, it is possible to reduce the characteristic variation of the object to be heated (for example, ceramic electronic component).

As in claim 2, an intermediate material is provided in the hearth, which is disposed above the support material, has a higher strength than the heat insulating material, and has an insertion hole for inserting and supporting the support column. May be.
In the first aspect, since the support column does not penetrate the hearth, there is a possibility that the tip of the support column may swing or tilt inside the furnace, and the support state of the object to be heated may become unstable. Therefore, by supporting the intermediate portion of the support with the intermediate material, the swing and inclination of the support can be suppressed.

According to a third aspect of the present invention, the support member has an area sufficient to support a plurality of the columns, and a lower number of legs are provided on the lower surface of the support member, and the lower ends of the legs are It may be exposed on the lower surface of the hearth.
When the weight of the object to be heated placed on the base plate increases, the weight acts on the hearth portion located below the support post and the support material. Since the hearth portion is also formed of a heat insulating material, the load resistance of the hearth portion may become a problem depending on the weight.
Therefore, by providing a leg portion on the lower surface of the support member as in claim 3 and supporting the leg portion with a base or the like, the hearth portion can be prevented from being compressed.
Since the number of leg portions is smaller than that of the support columns, the amount of heat that escapes from the support columns to the leg portions via the support member is small, and it is possible to prevent the heat insulation performance from deteriorating.

According to a fourth aspect of the present invention, a concave portion or a convex portion into which the lower end portion of the support column is fitted may be formed on the upper surface of the support material.
By fitting the lower end portion of the support column into the concave portion or the convex portion of the support material, the position shift of the support column is eliminated, and the object to be heated can be stably supported.
In addition, what is necessary is just to provide a recessed part in a support material if a support | pillar is a column shape, and what is necessary is just to provide a convex part in a support material if a support | pillar is a cylinder shape.

The fifth aspect differs from the first aspect in which the support material for supporting the lower end of the support column is disposed inside the hearth as in the first aspect, and the hearth has a two-stage upper and lower structure and the first heat insulating material on the upper side. And a second heat insulating material having higher strength than the first heat insulating material is arranged on the lower stage side. And the sinking of a support | pillar is prevented by supporting the lower end of the support | pillar penetrated by the 1st heat insulating material with the 2nd heat insulating material.
Also in this case, similarly to the first aspect, the heat radiation from the heat treatment space via the support column is small, and the temperature variation in the object to be heated can be reduced.

According to the invention according to claim 1, the strut is not penetrated to the bottom surface of the hearth made of the heat insulating material, and is structured to stop inside, and the support material having higher strength than the heat insulating material is disposed at the lower end of the strut, Since the support material supports the weight of the support column, the amount of heat released through the support column is reduced, and the temperature variation in the object to be heated can be reduced. Moreover, since the lower end part of a support | pillar is supported by a support material, it can support a support | pillar stably and has the effect that the inclination of the baseplate which mounted the to-be-heated material can be suppressed.

According to the invention which concerns on Claim 5, while using a 1st heat insulating material on the upper side of a hearth and using a heat insulating material stronger than a 1st heat insulating material as a 2nd lower heat insulating material, a 1st heat insulating material is used. Since the lower end of the support penetrating through the second support is supported by the second heat insulating material, the amount of heat radiation through the support is reduced, the temperature variation in the object to be heated can be reduced, and the support sinks. It can prevent, and can support a to-be-heated object stably.

Embodiments of the present invention will be described below with reference to examples.

2 and 3 show a first embodiment of a heat treatment furnace according to the present invention.
This heat treatment furnace is an example of a batch furnace. Reference numeral 10 denotes a furnace body made of a lightweight heat insulating material, brick, refractory metal, etc., and 11 denotes a heat treatment space formed inside the furnace body 10. An appropriate number of heaters 12 are disposed in the heat treatment space 11. In place of the heater 12, a heating method such as hot air circulation may be used.
Examples of the object to be heated W to be heat-treated in the heat treatment furnace include a bag containing a non-fired ceramic laminate for a multilayer capacitor or a multilayer inductor. A ceramic electronic component is completed by firing such a ceramic laminate and forming external electrodes on the outer surface of the fired ceramic laminate. In the case of firing the ceramic laminate, if there is a temperature variation in the cage, it causes a variation in the characteristics of the individual ceramic laminates accommodated in the cage, so it is important to suppress the temperature variation as much as possible.

An opening 13 is provided at the bottom of the furnace body 1, and the opening 13 is opened and closed by a hearth 14 that can be moved up and down. The hearth 14 is made of a lightweight heat insulating material such as ceramic fiber, and has a convex portion 15 having a shape substantially fitting to the opening 13 at the upper portion and a base portion 16 for opening and closing the opening 13 at the lower portion. doing. A plurality of support columns 17 are fixed to the hearth 14 in the vertical direction. The lower end of the support column 17 terminates in the hearth 14, and the upper end protrudes from the upper surface of the hearth 14 and is exposed to the heat treatment space 11. A base plate 18 for placing the article to be heated W is disposed on the support column 17. A plurality of recesses 18a are formed on the lower surface of the base plate 18, and the upper ends of the columns 17 are fitted into these recesses 18a. The support column 17 and the base plate 18 are formed of a refractory material such as a refractory metal or alumina. In order to suppress heat dissipation, refractories such as alumina, mullite, SiC, and Si ₃ N ₄ are preferable, and alumina and mullite are particularly preferable because of their low thermal conductivity.
As the lightweight heat insulating material in the present invention, those having a bulk density of 0.1 to 0.5 g / cm ³ are preferable. For example, ceramic fiber (alumina, mullite, etc.), ceramic fiber as an aggregate, calcium silicate or the like is added. There is something.

A support member 19 that supports the lower ends of the plurality of support columns 17 in common is disposed inside the hearth 14. The support material 19 is formed of a material having a higher compressive strength or bending strength than the lightweight heat insulating material constituting the hearth 14, for example, a refractory material such as a refractory metal or alumina, and is formed of a flat plate here. . An intermediate material 20 is disposed inside the hearth 14 and above the support material 19 as necessary. The intermediate member 20 is provided with an insertion hole 20 a for inserting and supporting the support column 17, and the inclination of the support column 17 is suppressed by the intermediate member 20. The intermediate member 20 is also formed of a material having higher strength than the lightweight heat insulating material, for example, a refractory material such as a refractory metal or alumina.
The position of the support material 19 is preferably arranged at least 1/10 or more of the height of the hearth 14 and above the bottom surface of the hearth 14. Further, the intermediate material 20 is preferably arranged at a position as close to the upper surface of the hearth 14 as possible.
As the support material 19 and the intermediate material 20, it is preferable to use a material having strength and heat insulation.

As the lightweight heat insulating material and the support material 19 constituting the hearth 14, for example, those having the following conditions can be used.
Lightweight insulation (alumina fiber): Compressive strength 0.7 MPa, bending strength 0.5 MPa, bulk density 0.25 g / cm ³
Support material (alumina): compressive strength 30 MPa, bending strength 10 MPa, bulk density 285 g / cm ³

In this embodiment, as shown in FIG. 3, the hearth 14 has a structure in which a plurality of lightweight heat insulating materials are laminated, and includes an upper layer portion 15 that constitutes a convex portion, an intermediate layer portion 16 a that constitutes a base portion 16, and a lower layer portion. It has a 16b three-layer structure. The intermediate member 20 is fixed between the upper layer portion 15 and the middle layer portion 16a, and the support member 19 is fixed between the middle layer portion 16a and the lower layer portion 16b.

The lower surface of the lower layer portion 16 b of the hearth 14 is placed on a lifting platform 21 that supports the hearth 14. The lifting platform 21 is connected by a lifting device 22 and a lifting rod 22 a and is driven up and down by the lifting device 22. Therefore, the object to be heated W placed on the hearth 14 can be taken in and out of the furnace body 1, and the base portion 16 of the hearth 14 can open and close the opening 13 of the furnace body 1.
The weight of the article W to be heated placed on the base plate 18 is received by the support member 19 through the support column 17 and further received by the lower layer portion 16b of the hearth 14 disposed below the support member 19. . Since the support material 19 is formed in a wide area so that the plurality of support columns 17 can be supported in common, a load acts on the lower layer portion 16b of the hearth 14 in a wide range, and the lower layer portion 16b is a lightweight heat insulating material. Even if formed, bending can be suppressed.

In the above embodiment, the upper surface of the support member 19 is a flat surface. However, in order to stably support the lower end of the support column 17, an example in which a concave portion, a convex portion, a slit or the like is provided will be described below.
FIG. 4 shows an example of a support member 19 that receives a plurality of support columns 17.
FIG. 4A shows a structure in which a plurality of bottomed circular support holes 19a are provided on the upper surface of a flat support member 19, and the lower ends of a plurality of columnar columns 17 are fitted into the support holes 19a. It is.
FIG. 4 (b) is a plan view in which a plurality of bottomed square support holes 19a are provided on the upper surface of the flat support member 19, and the lower ends of the prismatic columns 17 are fitted into the support holes 19a. is there.
Note that (a) and (b) also show the intermediate member 20, and an insertion hole 20 a corresponding to the cross-sectional shape of the support column 17 is formed in the intermediate member 20.

FIG. 5 shows an example of the support member 19 that individually receives the column 17.
In FIG. 5A, a circular support hole 19a having a bottom is provided on the upper surface of a disk-shaped support member 19, and the lower end portion of the columnar column 17 is fitted into the support hole 19a.
In FIG. 5B, a disc-shaped support member 19 is provided with a projection 19b on the upper surface, and the lower end of a hollow cylindrical column 17 is inserted and fixed to the projection 19b.
5C, as in FIG. 5B, a projection 19b is provided on the upper surface of the support material 19 to insert and fix the lower end portion of the support column 17, and is inserted into the base material of the hearth 14 on the lower surface of the support material 19. Is provided with a projection 19c for positioning.
Note that the protrusions 19b and 19c as shown in FIGS. 5B and 5C can also be applied to a support material that supports a plurality of support columns as shown in FIG.

6 and 7 show a second embodiment of the heat treatment furnace according to the present invention.
The second embodiment is also an example of a batch furnace, and the same parts as those in FIG.
In this embodiment, the support member 19 has a large area enough to support a plurality of support columns 17, and a lower number of leg portions 23 than the support columns 17 are provided on the lower surface of the support member 19. It is intended to support. As the leg portion 23, a material having strength and heat resistance is used similarly to the support material 19. Here, the leg portion 23 is provided at a position different from that of the support column 17, the support column 17 is disposed at the center portion of the support member 19, and the leg portion 23 is disposed at the peripheral portion (here, the corner portion) of the support member 19. ing. The leg portion 23 penetrates the lower layer portion 16 b of the furnace body 14, and the lower end thereof is exposed on the lower surface of the hearth 14, and abuts on the lifting platform 21 that supports the hearth 14. Note that a plurality of bottomed circular support holes 19 a into which the lower end portions of the support columns 17 are fitted are provided on the upper surface of the support member 19 as in FIG.

The weight of the article W to be heated placed on the base plate 18 is received by the support member 19 via the support column 17 and further received by the hearth portion 16 b disposed below the support member 19. That is, the entire weight of the article to be heated W, the base plate 18, the support column 17, and the support member 19 is added to the hearth portion 16 b disposed below the support member 19. However, since the hearth portion 16b is also formed of a light heat insulating material, the light heat insulating material may bend.
Therefore, in the second embodiment, a leg portion 23 is provided on the lower surface of the support member 19, and the entire weight is supported by the leg portion 23. Since the lower end of the leg portion 23 is supported by the rigid elevator 21, it is possible to reliably prevent the hearth portion 16 b disposed below the support material 19 from being bent.

FIG. 8 shows a hearth in a third embodiment of the heat treatment furnace according to the present invention.
This hearth 30 is also used in a batch furnace, the upper side of the hearth 30 is made of a first heat insulating material 31 made of a lightweight heat insulating material, and the lower side is a second heat insulating material having higher strength than the first heat insulating material 31. 32. As the second heat insulating material 32, for example, a lightweight heat insulating material having higher strength than the first heat insulating material 31 may be used, or a hard heat insulating material such as brick may be used. The lower end of the support column 33 is in contact with the second heat insulating material 32, and is disposed through the first heat insulating material 31 so that the upper end is exposed on the upper surface of the hearth 30. A base plate 34 for mounting an object to be heated (not shown) is fitted on the support 33.
In the case of this embodiment, since the second heat insulating material 32 has higher strength than the first heat insulating material 31 that is a lightweight heat insulating material, the second heat insulating material 32 supports the weight of the object to be heated placed on the base plate 34. It is possible to prevent the second heat insulating material 32 from being bent. And since the 2nd heat insulating material 32 also has heat insulation, the thermal radiation amount via the support | pillar 33 can be suppressed and the temperature variation in a to-be-heated material can be made small.

As the 1st heat insulating material 31 and the 2nd heat insulating material 32, it can also form with ceramics, such as an alumina and a mullite. In that case, both of the same ceramics (for example, if the first heat insulating material 31 is an alumina ceramic, the second heat insulating material 32 is an alumina ceramic, and if the first heat insulating material 31 is a mullite ceramic, the second heat insulating material is used. The material 32 is also preferably a mullite ceramic). By selecting the same type of ceramics, the bonding strength between the first heat insulating material 31 and the second heat insulating material 32 can be increased, and the strength of the hearth 30 can be improved.

The present invention is not limited to the above embodiment.
For example, the support material 19 in the first embodiment can be applied to the hearth 30 having the structure as in the third embodiment. That is, the support material 19 may be disposed between the first heat insulating material 31 and the second heat insulating material 32, and the lower surface of the support column 17 may be supported by the support material 19.
Moreover, you may apply the intermediate material 20 in 1st Example to the hearth 30 of 3rd Example.
Moreover, although the support | pillar 17 and the support material 19 were comprised by the separate member, both can also be integrally molded and comprised.

The hearth of the present invention is configured to move not only the vertically movable hearth used in the batch type heat treatment furnace as in the embodiment, but also the carriage on which the object to be heated is moved in the heat treatment space of the furnace body. It can also be applied as a cart of a continuous heat treatment furnace. That is, the hearth may be movable in the horizontal direction. In this case, the cart itself may be provided with a pulley and run on a rail provided on the furnace body, or a roller hearth furnace in which the cart moves on a hearth roll arranged in parallel to the lower part of the furnace body by a roller feed rotation. But you can.
In the said Example, although the lightweight heat insulating material was used as a hearth, it is also possible to use heat insulating materials other than a lightweight heat insulating material.

It is a figure which shows the conventional cart structure. It is a figure which shows the structure of 1st Example of the heat processing furnace concerning this invention. It is sectional drawing of the hearth used with the heat processing furnace shown in FIG. It is a perspective view which shows the example of the support material which supports several support | pillars. It is a perspective view which shows the example of the support material which supports a single support | pillar. It is a figure which shows the structure of 2nd Example of the heat processing furnace concerning this invention. It is a perspective view which shows the frame | skeleton structure of the hearth shown in FIG. It is sectional drawing of the hearth in 3rd Example of the heat processing furnace concerning this invention.

Explanation of symbols

W object to be heated 10 furnace body 11 heat treatment space 13 opening 14 hearth 17 support 18 base plate 19 support material 20 intermediate material

Claims (5)

A furnace body having a heat treatment space inside;
A hearth made of heat insulating material, disposed at the bottom of the furnace body;
A column arranged such that the lower end is the end inside the hearth and the upper end is exposed on the upper surface of the hearth,
A base plate for placing an object to be heated, disposed on the column,
A heat treatment, comprising: a support material disposed inside the hearth so as to support a lower end of the support column, having a larger area than a lower end surface of the support column and having a higher strength than the heat insulating material. Furnace. An intermediate material having an insertion hole for inserting and supporting the support column is disposed inside the hearth and above the support material and having higher strength than the heat insulating material. Item 2. The heat treatment furnace according to Item 1. The support member has an area sufficient to support a plurality of the columns,
A lower number of legs is provided on the lower surface of the support material than the support column,
The heat treatment furnace according to claim 1 or 2, wherein a lower end of the leg portion is exposed on a lower surface of the hearth. The heat treatment furnace according to any one of claims 1 to 3, wherein a concave portion or a convex portion into which a lower end portion of the support column is fitted is formed on the upper surface of the support material. A furnace body having a heat treatment space inside;
A hearth is disposed at the bottom of the furnace body, the upper side is made of a first heat insulating material, and the lower side is made of a second heat insulating material having higher strength than the first heat insulating material,
A support column penetrating through the first heat insulating material such that the lower end is in contact with the second heat insulating material and the upper end is exposed on the upper surface of the hearth,
A heat treatment furnace comprising: a base plate for placing an object to be heated disposed on the support column.

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