JP6817799B2 - Heat treatment furnace - Google Patents

Description

The present invention relates to a heat treatment furnace for heat-treating workpieces such as automobile parts and machine parts.

There are vacuum carburizing furnaces described in Patent Document 1 and Patent Document 2 as a furnace for performing carburizing treatment, which is an example of heat treatment. In the vacuum carburizing furnace of Patent Document 1, a heat insulating material is provided so as to face the inner surface of the furnace shell, and a support member (hearth) for supporting the work is attached to the hearth so as to penetrate the heat insulating material. There is. A work loaded on a tray or a basket is arranged at the upper end of the support member. Similarly, in the vacuum carburizing furnace of Patent Document 2, a heat insulating material is provided along the inner surface of the furnace shell, and a pedestal provided so as to penetrate the heat insulating material is attached so as to be in contact with the shell. The work is placed on the gantry. In a conventional furnace, heat treatment, carburizing treatment, etc. are performed with the work supported in this way.

Japanese Unexamined Patent Publication No. 2006-112770 Japanese Unexamined Patent Publication No. 2009-52838

In order to suppress quality variation after heat treatment of each work, it is desirable that the treatment conditions during heat treatment of each work are the same. For example, if the amount of heat input to each work during heat treatment can be made uniform and temperature variation can be suppressed, variation in heat treatment quality of the work can also be suppressed.

However, in the conventional furnace, since the support member that supports the work is attached so as to come into contact with the furnace shell, heat escape due to heat conduction through the support member occurs. Along with this, the amount of heat input differs between the work arranged near the support member on the jig and the work arranged in other parts, and the temperature varies from work to work. As a result, the heat treatment quality of each work to be heat-treated in the same lot varies.

The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress variations in temperature of the work during heat treatment and to suppress variations in heat treatment quality of the work.

The present invention that solves the above problems is a heat treatment furnace that heat-treats a work, and includes a first heat insulating material provided in the furnace and a support member that supports the work, and the furnace shell side of the support member. The end portion is supported by the first heat insulating material without penetrating the first heat insulating material, and the second heat insulating material is arranged so as to overlap the first heat insulating material .

According to the heat treatment furnace according to the present invention, heat escape through the support member supporting the work is suppressed. Thereby, the temperature variation of the work during the heat treatment can be suppressed.

According to the present invention, it is possible to suppress the temperature variation of the work during the heat treatment and suppress the variation of the heat treatment quality of the work.

It is a vertical sectional view which shows the schematic structure of the vacuum carburizing furnace which concerns on embodiment of this invention. FIG. 5 is a cross-sectional view taken along the line AA in FIG. It is a vertical sectional view which shows the schematic structure of the vacuum carburizing furnace which concerns on other embodiment of this invention. It is a figure which shows the schematic structure of the 2nd heat insulating material which concerns on other embodiment of this invention, and is the sectional view corresponding to the sectional view AA in FIG.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the present specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals to omit duplicate description.

In this embodiment, a vacuum carburizing furnace will be described as an example of the heat treatment furnace. As shown in FIG. 1, in the vacuum carburizing furnace 1 according to the present embodiment, the vacuum chamber 2, the heat insulating material case 3 in which the work W is housed, and the first heat insulating material provided inside the heat insulating material case 3 are provided. 11 and a rail 20 extending in the depth direction D ₂ (vertical direction on the paper surface in FIG. 1) on which the tray-shaped jig J is placed, and a support member 4 for supporting the work W from below via the rail 20 and the jig J. It has. The jig J on which the plurality of works W are mounted is conveyed so as to slide and move in the depth direction D ₂ on the rail 20.

The heat insulating material case 3 is formed in a rectangular parallelepiped shape, and a metal such as SUS310S, SUS304, or SS400 is used as the material. The heat insulating material case 3 is carried in from a carry-in inlet (not shown) provided in the furnace shell 2a, and is placed on a cradle 5 provided on the bottom of the furnace. The cradle 5 is composed of a plate-shaped member, a roller, or the like.

The first heat insulating material 11 is arranged along the inner surfaces of the side wall portion 3a, the bottom portion 3b, and the ceiling portion 3c in the heat insulating material case. In the following description, the first heat insulating material 11 arranged on the side wall portion 3a of the heat insulating material case is the side wall heat insulating material 11a, and the first heat insulating material 11 arranged on the bottom 3b of the heat insulating material case is the bottom heat insulating material 11b and heat insulating material 11. The first heat insulating material 11 arranged on the material case ceiling 3c is referred to as a ceiling heat insulating material 11c. As the first heat insulating material 11, it is sufficient that heat conduction can be blocked and a heat insulating effect can be obtained. For example, heat resistant bricks, ceramic boards, ceramic fibers, vacuum heat insulating materials, porous heat insulating materials and the like are used.

The heat insulator casing 3, a heater 6 extending in the width direction D ₁ of the heat insulator casing 3 is provided so as to be inserted from one side wall portion 3a. The heaters 6 are arranged above and below the work W, respectively, and penetrate one side wall portion 3a (right side wall portion in FIG. 1) and the side wall portion heat insulating material 11a of the heat insulating material case 3, and the other side wall portion heat insulating material. The tip portion is fixed to 11a so as to be embedded. The heaters 6 have a U-shape, and a plurality of heaters 6 are installed along the depth direction D ₂ of the heat insulating material case 3 so as to cover each work W mounted on the jig J in a plan view. Further, a thermocouple 7 for measuring the temperature inside the heat insulating material case is provided on the other side wall portion 3a (the left side wall portion in FIG. 1) of the heat insulating material case 3. The thermocouple 7 is fixed so as to penetrate the hearth 2a, the side wall portion 3a of the heat insulating material case 3, and the side wall portion heat insulating material 11a. The thermocouple 7 is inserted after the heat insulating material case 3 is carried into the furnace. The heater 6 in FIG. 1 is shown by a chain double-dashed line for simplification of the drawing.

The support member 4 that supports the work W is formed so as to extend in the vertical direction, and has a rectangular cross-sectional shape as shown in FIG. Further, a plurality of support members 4 are arranged at predetermined intervals. As the material of the support member 4, for example, a metal such as SUS310S, a heat-resistant steel such as SCH24, and a heat-resistant metal such as W and Mo are used. The shape of the jig J is not limited to the tray shape, and may be a basket-shaped jig or a multi-stage jig on which the work W is placed in a hierarchical manner. Further, the number of support members 4 is not particularly limited.

An end plate 8 is provided at the lower end of each support member 4 to increase the contact area between the support member 4 and the bottom heat insulating material 11b by making surface contact with the bottom heat insulating material 11b. As the material of the end plate 8, for example, a metal such as SUS310S, a heat-resistant steel such as SCH24, and a heat-resistant metal such as W or Mo are used. A counterbore is formed in the end plate 8, and the pin 9 fixed to the lower end of the support member 4 is fitted into the counterbore, so that the support member 4 and the end plate 8 are detachably fixed. Has been done.

A plurality of recesses are formed on the upper surface of the bottom heat insulating material 11b according to the size of the end plate 8, and the end plate 8 is in contact with the bottom surface in the recesses. By providing the end plate 8 at the lower end of each support member 4 in this way, it is possible to receive the weight of the work W, the jig J, and the rail 20 on the surface. As a result, the supporting posture of the jig J can be stabilized, and the occurrence of cracks in the bottom heat insulating material 11b can be suppressed. Further, since the end plate 8 is provided in the recess of the bottom heat insulating material 11b, the end plate 8 can be easily positioned at the time of installation. It is not necessary to provide the end plate 8 at the lower end of the support member 4 depending on the weight of the work W, the jig J, the number of the support members 4, the strength of the bottom heat insulating material 11b, and the like. For example, if the number of support members 4 is large, the weights of the work W, the jig J, and the rail 20 are dispersed and transmitted to the bottom heat insulating material 11b, so that the bottom heat insulating material 11b cracks even if the end plate 8 is not provided. It becomes difficult. Further, in the present embodiment, the bottom heat insulating material 11b is provided with a concave portion, but a concave portion may be provided at the lower end portion of the support member 4 and a convex portion may be provided on the upper surface portion of the bottom heat insulating material 11b for fitting. ..

As shown in FIGS. 1 and 2, the bottom 3b of the heat insulating material case 3 is provided with a second heat insulating material 12 that covers the upper surface of the end plate 8 of the support member 4 in addition to the bottom heat insulating material 11b. .. The second heat insulating material 12 is elongated along the depth direction D ₂ of the heat insulating material case 3, and covers each group of support members 4 arranged in the depth direction D ₂ with one heat insulating material. The second heat insulating material 12 is formed with an opening 12a that matches the shape of the support member 4. When arranging the second heat insulating material 12 on the end plate 8, the support member 4 is installed on the bottom heat insulating material 11b, and then the opening 12a of the second heat insulating material 12 is passed through the support member 4. The second heat insulating material 12 is placed on the upper surface of the end plate 8.

By providing the second heat insulating material 12, the upper surface of the end plate 8 that reflects the radiant heat of the heater 6 is covered, and the variation in the amount of heat input to each work W can be suppressed. Further, since the second heat insulating material 12 is provided, the deformation of the bottom heat insulating material 11b due to heat shrinkage can be suppressed, and the variation in the positions of the work W and the heater 6 can be suppressed. As a result, it is possible to suppress variations in the amount of heat input to each work W. Furthermore, by providing the second heat insulating material 12, the sooting of the bottom heat insulating material 11b can be suppressed, and the repair frequency of the bottom heat insulating material 11b can be reduced. As a result, it is possible to repair the inside of the furnace while the support member 4 is arranged on the upper surface of the bottom heat insulating material 11b, so that the repair work efficiency can be improved. Although it is not essential to provide the second heat insulating material 12, it is preferable to provide the second heat insulating material 12 from the viewpoint of suppressing temperature variation of the work W. As the second heat insulating material 12, it is sufficient that heat conduction can be blocked and a heat insulating effect can be obtained. For example, heat resistant bricks, ceramic boards, ceramic fibers, vacuum heat insulating materials, porous heat insulating materials and the like are used. Further, the bottom heat insulating material 11b is made of a hard heat insulating material having high compressive strength and processing accuracy, and the second heat insulating material 12 is made of a heat insulating material having better heat insulating properties than the bottom heat insulating material 11b. The materials of the material 12 and the first heat insulating material 11 may be different. As a result, the bottom heat insulating material 11b that supports the weight of the work W, the jig J, and the rail 20 is less likely to crack, and the second heat insulating material 12 can ensure sufficient heat insulating properties.

In the present embodiment, in the bottom portion 3b of the heat insulating material case 3, the third heat insulating material 13 is provided on the upper surface of the bottom heat insulating material 11b where the second heat insulating material 12 is not provided. The third heat insulating material 13 is spread so as to fill the gap between the second heat insulating material 12 and the side wall heat insulating material 11a, and the upper surface of the third heat insulating material 13 and the upper surface of the second heat insulating material 12 are the same ( They are arranged so that they are approximately the same height). By providing such a third heat insulating material 13, the distance between the heater 6 and the heat insulating material below the work becomes constant, and each work W can be heated more uniformly. Although it is not essential to provide the third heat insulating material 13, it is preferable to provide the third heat insulating material 13 from the viewpoint of suppressing temperature variation of the work W. As the third heat insulating material 13, it is sufficient that heat conduction can be blocked and a heat insulating effect can be obtained. For example, heat resistant bricks, ceramic boards, ceramic fibers, vacuum heat insulating materials, porous heat insulating materials and the like are used. Further, the third heat insulating material 13 and the second heat insulating material 12 may be integrally formed.

The vacuum carburizing furnace 1 according to the present embodiment is configured as described above. Although the description is omitted, the vacuum carburizing furnace 1 is necessary for carrying out vacuum carburizing treatment such as a gas inlet that supplies a processing gas into the heat insulating material case, an exhaust pipe that evacuates the inside of the furnace, and a vacuum pump. It has a simple configuration.

According to the vacuum carburizing furnace 1 of the present embodiment, the heat treatment is performed in a state where the lower end portion of the support member 4 that supports the work W from below is in contact with the bottom heat insulating material 11b. In other words, the heat treatment is performed in a state where the lower end portion of the support member 4 is not in contact with the heat insulating material case 3 or the furnace shell 2a. As a result, heat escape due to heat conduction through the support member 4 is suppressed during heat treatment such as heat treatment or carburizing treatment of the work W, and it is possible to suppress temperature variation of each work W. As a result, variations in heat treatment quality of each work W can be suppressed.

In the present embodiment, the inner bottom surface of the recess is provided in the first heat insulating material 11, and the support member 4 of the work W is brought into contact with the inner bottom surface of the recess, but the first heat insulating material 11 is not provided with the recess. , The support member 4 of the work W may be brought into contact with the upper surface of the first heat insulating material 11. Further, the number of works W is not limited. For example, in the case of carburizing a large-sized work W, in a conventional carburizing furnace in which heat escape occurs via the support member 4, carburizing variation occurs for each part of one work W. On the other hand, in the carburizing furnace as in the present embodiment, even when such a work W is carburized, the effect of suppressing heat escape can be obtained, so that the carburizing variation for each part of the work W can be suppressed.

Further, in the present embodiment, the upper end portion of the support member 4 is in contact with the lower surface of the rail 20 and the lower end portion of the support member 4 is in contact with the bottom heat insulating material 11b as the support structure of the work W. The structure is not limited to this. Other support structures may be used as long as the work W can be held in the heat treatment region for a certain period of time. That is, of the end portions of the support member 4 (work side end portion 4a and furnace shell side end portion 4b in the above embodiment), the furnace shell side end portion 4b does not penetrate the first heat insulating material 11 and is a heat insulating material. If the first heat insulating material 11 is supported so as to be interposed between the case 3 and the case 3, heat escape through the support member 4 can be suppressed even in another support structure. Further, since the first heat insulating material 11 is interposed between the furnace shell side end portion 4b of the support member 4 and the heat insulating material case 3, it is less likely to be affected by disturbance and the heat treatment quality can be improved. it can.

Further, in the present embodiment, the heat insulating material case 3 for accommodating the work W is provided in the furnace, but the heat insulating material case 3 may not be provided as shown in FIG. Even with such a configuration, the support member 4 that supports the work W does not come into contact with the furnace shell 2a, that is, the first heat insulation is provided between the furnace shell side end portion 4b of the support member 4 and the furnace shell 2a. If the structure is such that the material 11 is interposed, it is possible to obtain effects such as suppressing heat escape via the support member 4 and being less susceptible to disturbance. However, for example, when the heat insulating material needs to be repaired, the furnace cannot be used during the heat insulating material repair work in the furnace having the heat insulating material arranged on the inner surface of the furnace shell, resulting in high productivity. It will decrease. On the other hand, in a furnace provided with the heat insulating material case 3, heat treatment can be performed using another heat insulating material case during the repair work of one heat insulating material case 3, and it is possible to suppress a decrease in productivity. Become. From this point of view, it is preferable to provide the heat insulating material case 3.

Further, in the present embodiment, a group of support members 4 arranged in the depth direction D ₂ of the heat insulating material case 3 are covered with one second heat insulating material 12, but as shown in FIG. 4, for example, a plurality of supporting members 4 are covered. It may be covered with the second heat insulating material 12. By providing the plurality of second heat insulating materials 12, each of the second heat insulating materials 12 can be passed through the support member 4 even if the position accuracy of the opening 12a is low. As a result, the work efficiency at the time of installing the second heat insulating material 12 is improved. Further, when the heater 6 for heating the work W is arranged between the work W and the second heat insulating material 12, the second heat insulating material 12 is placed in the heater 6 according to the distance between the wires of the heater 6. It is preferable to have a shape that allows passage between the strands. As a result, after removing the detachably fixed support member 4, the second heat insulating material 12 can be lifted and tilted to be pulled out through the wires of the heater 6. As a result, the repair work of the second heat insulating material 12 can be performed without removing the heater 6.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical idea described in the claims, and of course, the technical scope of the present invention also includes them. It is understood that it belongs to.

The present invention can be applied to a vacuum carburizing furnace. In addition to the vacuum carburizing furnace, the present invention can also be applied to a carburizing furnace that carburizes by another method such as gas carburizing, or a nitriding furnace that performs gas nitriding treatment, gas nitrocarburizing treatment, or the like. That is, the present invention can be applied to a heat treatment furnace that performs heat treatment that requires heating of a work.

1 Vacuum charcoal furnace 2 Vacuum chamber 2a Shell 3 Insulation case 3a Side wall of insulation case 3b Bottom of insulation case 3c Ceiling of insulation case 4 Support member 4a Work side end of support member 4b Furnace of support member Shell side end 5 Cradle 6 Heater 7 Thermocouple 8 End plate 9 Pin 11 First insulation 11a Side wall insulation 11b Bottom insulation 11c Ceiling insulation 12 Second insulation 12a Second insulation Opening 13 Third heat insulating material 20 Rail D ₁ Width direction of heat insulating material case D ₂ Depth direction of heat insulating material case J Jig W work

Claims (5)

A heat treatment furnace that heat-treats a work
The first heat insulating material provided in the furnace and
A support member for supporting the work is provided.
The furnace shell side end of the support member is supported by the first heat insulating material without penetrating the first heat insulating material .
A heat treatment furnace in which a second heat insulating material is arranged so as to overlap the first heat insulating material . The support member is provided so as to support the work from below.
The heat treatment furnace according to claim 1, wherein an end plate that comes into surface contact with the first heat insulating material is provided at the lower end of the support member. Before Stories second heat insulating material is provided to cover the upper surface of said end plate, the heat treatment furnace according to claim 2. The heat treatment furnace according to claim 3 , wherein a third heat insulating material is provided on the upper surface of the first heat insulating material in a portion where the second heat insulating material is not provided. A heat insulating case for accommodating the work is provided.
The heat treatment furnace according to any one of claims 1 to 4 , wherein the first heat insulating material is provided inside the heat insulating material case.

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