JP2014163637A - Thermal treatment device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal treatment device capable of suppressing heat transfer from the inside of a thermal treatment furnace to the outside through a drive shaft without making a drive mechanism of an in-furnace agitation fan complicated.SOLUTION: A thermal treatment device 1 includes an in-furnace agitation fan 2 provided in a thermal treatment furnace 3, and a drive shaft 4 provided so as to penetrate a furnace body of the thermal treatment furnace 3 and connected to the in-furnace agitation fan 2. In the thermal treatment device, at least a part of the drive shaft 4 is used as a hollow shaft 8, the in-furnace agitation fan 2 is connected to the hollow shaft 8 in the thermal treatment furnace, and a heat insulation material 10 having higher heat insulation property than air is provided in a hollow part of the hollow shaft 8.

Description

  The present invention relates to a heat treatment apparatus including an in-furnace agitation fan for agitating an atmosphere in a heat treatment furnace and a manufacturing method thereof.

  Heat treatment such as carburizing treatment is performed in a high-temperature heat treatment furnace with controlled atmosphere. In order to perform high-quality heat treatment, it is necessary to reduce the variation in atmosphere in the heat treatment furnace and make the furnace temperature as uniform as possible. For this reason, an in-furnace stirring fan for stirring the atmosphere in the furnace is provided in the heat treatment furnace.

  In general, the in-furnace stirring fan is connected to a drive shaft provided so as to penetrate the heat treatment furnace. The drive shaft is connected to a motor disposed outside the furnace, and is supported by a bearing provided adjacent to the heat treatment furnace outside the heat treatment furnace.

  The temperature inside the heat treatment furnace such as a carburizing furnace is very high (for example, 900 ° C. or more). Although the heat treatment furnace has a heat insulating structure so that the heat in the furnace is not transmitted to the outside of the furnace, the heat in the furnace is passed through a drive shaft of an in-furnace stirring fan provided so as to penetrate the heat treatment furnace. Will be transmitted to the outside of the furnace. This heat is transmitted to peripheral components around the drive shaft such as a bearing supporting the drive shaft and a motor connected to the drive shaft. Since the operating temperature range is specified for bearings and motors, if the temperature range exceeds the specified temperature range due to the heat transferred through the drive shaft, the performance of each component may be degraded or malfunction may occur. .

  In order to avoid such a situation, conventionally, high heat-resistant parts such as ceramic bearings have been adopted, or heat transfer measures described in Patent Documents 1 to 4 have been taken.

  The heat transfer countermeasure described in Patent Document 1 provides a cooling space by increasing the length of the drive shaft connected to the in-furnace agitation fan, and increasing the length between the in-furnace agitation fan and the fan-side bearing. Is made hollow. In addition, the atmosphere in this hollow part is air.

  The heat transfer measures described in Patent Documents 2 and 3 are provided with a water cooling mechanism or a gas cooling mechanism on a rotating shaft connected to an in-furnace stirring fan. The heat transfer countermeasure described in Patent Document 4 is provided with a cooling fan for cooling the bearing outside the rotating shaft connected to the in-furnace stirring fan.

Japanese Patent Laid-Open No. 62-268984 Japanese Patent Laid-Open No. 10-8148 JP 2003-21472 A JP 2012-229878 A

  However, the heat transfer countermeasure of Patent Document 1 has a problem in that the degree of freedom in design is reduced due to the drive shaft becoming too long. Moreover, although it is preferable that the temperature of a drive shaft or a bearing is 150 degrees C or less, in the heat transfer countermeasure described in patent document 1, there exists a possibility that the temperature of a bearing may reach 200 degreeC (Example of patent document 1). See

  Further, the water cooling mechanism or the gas cooling mechanism in the heat transfer countermeasures of Patent Documents 2 and 3 is complicated, and the manufacturing cost is increased. Moreover, in addition to the time and effort required for maintenance, the heat in the furnace is taken away by the cooling by the cooling mechanism, and the loss of heat becomes large.

  In addition, just by providing a cooling fan as a countermeasure for heat transfer in Patent Document 4, a sufficient cooling effect can be obtained when the inside of a heat treatment furnace becomes extremely high temperature (for example, 900 ° C. or more) as in carburizing. Absent.

  An object of the present invention is to solve the above-described problems, and can suppress heat transfer from the inside of the heat treatment furnace to the outside of the furnace via the drive shaft without complicating the drive mechanism of the in-furnace stirring fan. An object of the present invention is to provide a heat treatment apparatus and a manufacturing method thereof.

  In order to solve the above problems, according to the present invention, an in-furnace agitation fan provided in the furnace of the heat treatment furnace and a furnace body of the heat treatment furnace are provided so as to pass through and connected to the in-furnace agitation fan A drive shaft, wherein at least a part of the drive shaft is a hollow shaft, and in the heat treatment furnace, the in-furnace stirring fan is connected to the hollow shaft, A heat treatment apparatus is provided in which a heat insulating material having a higher heat insulating property than air is provided in the hollow portion.

  The hollow shaft is preferably formed so that the hollow shaft and the heat treatment furnace communicate with each other.

  The drive shaft may include a hollow shaft and a solid shaft connected in series to the hollow shaft. At this time, it is preferable that the joint part of the said solid shaft and the said hollow shaft exists in the furnace inner side from the furnace body surface of the said heat processing furnace. Further, a sealing member for sealing a gap formed between the heat treatment furnace and the solid shaft may be provided. At this time, it is preferable that the joint between the solid shaft and the hollow shaft is inside the furnace from the furnace body surface of the heat treatment furnace and inside the furnace from the seal member. The solid shaft may be supported by a bearing provided outside the heat treatment furnace. The hollow shaft and the solid shaft may be connected in series by welding.

  In addition, a cooling fan for cooling a bearing that supports the drive shaft may be provided on the drive shaft outside the furnace of the heat treatment furnace.

According to the present invention, there is also provided a manufacturing method for manufacturing the heat treatment apparatus, wherein the hollow shaft and the solid shaft are welded to each other after the hollow shaft and the solid shaft are fixed to each other by shrinkage fitting. The heat treatment apparatus manufacturing method is also provided in which the drive shaft is formed by connecting in series.

  According to the present invention, at least a part of the drive shaft is a hollow shaft, and a heat insulating material having higher heat insulation than air is provided in the hollow portion of the hollow shaft connected to the in-furnace agitation fan. Heat transfer from the inside of the furnace to the outside of the furnace can be suppressed. Thereby, the temperature rise of components around the drive shaft can be prevented.

It is a schematic longitudinal cross-sectional view which shows the periphery of the in-furnace stirring fan of the heat processing apparatus which concerns on embodiment of this invention. It is the figure which expanded the hollow shaft periphery in FIG. It is a figure which shows the heat processing apparatus which concerns on other embodiment of this invention. It is a figure which shows the drive shaft temperature and bearing temperature which exist outside the furnace of the heat processing furnace in the example of this invention, and a prior art example. It is a figure which shows the change of the elapsed time from the end of heat processing in the example of this invention, and a prior art example, and a bearing temperature.

  Hereinafter, an embodiment of the present invention will be described based on a heat treatment apparatus 1. In the present embodiment, only the vicinity of the in-furnace agitation fan 2 among the components of the heat treatment apparatus 1 will be described. 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.

  First, the in-furnace stirring fan 2 that stirs the atmosphere inside the heat treatment furnace 3 such as a batch-type or continuous carburizing treatment furnace is provided at the top of the furnace body of the heat treatment furnace 3. As shown in FIG. 1, the drive shaft 4 for rotating the in-furnace agitation fan 2 is accommodated in the central part of the housing 5 provided adjacent to the heat treatment furnace 3 so as to penetrate the furnace body of the heat treatment furnace 3. Is provided. One end of the drive shaft 4 is connected to the in-furnace agitation fan 2, and the other end of the drive shaft 4 is connected to a motor 6 disposed outside the housing 5. The material of the drive shaft 4 is, for example, stainless steel subjected to calorizing treatment. The furnace body of the heat treatment furnace 3 includes a furnace shell 9 in contact with outside air and a heat treatment furnace heat insulating material 16 inside the furnace shell 9.

  As shown in FIG. 1, the drive shaft 4 includes a solid shaft 7 and a hollow shaft 8, and the lower end of the solid shaft 7 is near the furnace shell 9 of the furnace body of the heat treatment furnace 3 or with the furnace shell 9 and heat treatment. It is preferable to extend from the boundary surface of the furnace heat insulating material 16 to the inside of the furnace. That is, the joint between the solid shaft 7 and the hollow shaft 8 is preferably located inside the furnace body (furnace shell 9) of the heat treatment furnace 3 in order to improve the strength of the drive shaft 4.

  On the other hand, a heat insulating material 10 having a higher heat insulating property (lower thermal conductivity) than air is provided in the hollow portion of the hollow shaft 8. In particular, in the present invention, the heat insulating material 10 “having higher heat insulation than air” means a heat insulating material having a thermal conductivity at 800 ° C. lower than that of air. More specifically, since the thermal conductivity of air at 800 ° C. is 0.071 W / (m · K), it means a thermal conductivity lower than that. For example, for the heat insulating material 10, it is preferable to use Microtherm (registered trademark) having a fine porous structure. Although the microtherm has different thermal conductivity depending on the type, the thermal conductivity at 800 ° C. is preferably in the range of 0.03 to 0.045 W / (m · K). Further, as other heat insulating materials, there is a Roslim (registered trademark) board having a thermal conductivity of 800 ° C. of 0.044 W / (m · K), which is suitable for the present invention. In addition, the heat conductivity of the heat insulating material 10 is measured based on ISO8302.

  As shown in FIGS. 1 and 2, a communication hole 13 through which the atmosphere in the hollow shaft 8 can pass through the atmosphere in the heat treatment furnace is provided at the bottom of the hollow shaft 8. The structure is cut off from the atmosphere outside the furnace of the furnace 3. By providing the communication hole 13, the gas expanded in the hollow shaft due to the influence of heat in the heat treatment furnace can be released into the heat treatment furnace. Therefore, the inside of the hollow shaft can be prevented from becoming a high pressure, and the deformation and breakage of the hollow shaft 8 can be prevented.

  As shown in FIG. 2, the solid shaft 7 and the hollow shaft 8 constituting the drive shaft 4 are fitted with the lower portion of the solid shaft 7 in the upper portion of the hollow shaft 8, and the outer peripheral surface of the solid shaft 7 and the hollow shaft 8 are The inner peripheral surface is brought into contact, and the outer peripheral surface of the solid shaft 7 and the circumferential surface of the cylindrical upper portion of the hollow shaft 8 are connected in series by welding. At this time, the solid shaft 7 may be brought into contact with the heat insulating material 10 of the hollow shaft 8 and welded. Thereby, the solid shaft 7 can be easily positioned during welding. Further, it is also preferable to weld the solid shaft 7 and the hollow shaft 8 after fixing them by shrink fitting. As a result, the solid shaft 7 and the hollow shaft 8 can be welded with high positional accuracy, and the shaft center of the drive shaft 4 can be prevented from shaking during rotation of the in-furnace stirring fan 2. Further, since the position of the solid shaft 7 is regulated even during welding, it is possible to reduce the quality variation of the welding.

  As described above, it is important to connect the solid shaft 7 and the hollow shaft 8 with high dimensional accuracy so that the deviation between the central axes of the solid shaft 7 and the hollow shaft 8 is minimized. That is, since the in-furnace agitation fan 2 rotates at high speed to agitate the in-furnace atmosphere at a high temperature, if the axial deviation between both the solid shaft and the hollow shaft is large, vibration occurs and causes a failure. Therefore, it is preferable to connect by welding after fixing by the shrink fitting.

  The solid shaft 7 is supported by a bearing 11 provided adjacent to the heat treatment furnace 3. As shown in FIG. 2, a seal member 12 is provided at the boundary between the outer peripheral surface of the solid shaft 7 and the furnace body (furnace shell 9) of the heat treatment furnace 3. The sealing member 12 fills a boundary (gap) formed between the heat treatment furnace 3 and the solid shaft 7, thereby preventing atmospheric gas in the furnace from leaking outside the furnace. Further, even when trouble such as breakage of the hollow shaft 8 occurs, it is possible to prevent air from being mixed into the furnace from the outside of the furnace. The outflow of gas, etc.) outside the furnace can also be prevented, so that troubles such as fire can be prevented. The seal member 12 is, for example, an O-ring or an oil seal.

  Further, the joint portion between the solid shaft 7 and the hollow shaft 8 is preferably located inside the furnace from the surface of the furnace body of the heat treatment furnace 3 and inside the furnace from the seal member 12. Thereby, even if the hollow shaft 7 is damaged, it is possible to prevent the atmospheric gas in the furnace from leaking out of the furnace, and the safety can be improved. It is also preferable for improving the strength of the drive shaft 4.

  A reinforcing plate 15 is provided on the upper surface of the upper plate 14 of the in-furnace agitation fan 2. As shown in FIG. 2, the reinforcing plate 15 is welded on the upper surface of the upper plate 14 of the in-furnace stirring fan 2, and the hollow shaft 8 is welded on the upper surface of the reinforcing plate 15 and the lower surface of the upper plate 14 of the in-furnace stirring fan 2. Has been.

  In the embodiment of the present invention, the heat treatment is performed by the heat treatment apparatus configured as described above. According to the heat treatment apparatus configured as described above, the drive shaft is constituted by a solid shaft and a hollow shaft, and the hollow portion of the hollow shaft connected to the in-furnace agitation fan has higher heat insulation than the air (heat By providing a heat insulating material having a low conductivity, heat transfer from the inside of the furnace to the outside of the furnace via the drive shaft can be suppressed. Thereby, the temperature rise of components around the drive shaft such as a bearing supporting the drive shaft and a motor connected to the drive shaft can be suppressed. As a result, each component can be used within the operating temperature range defined for each peripheral component, and a stable performance can be brought out and a decrease in durability can be suppressed. In addition, along with the suppression of heat transfer from the drive shaft, the peripheral components of the drive shaft can be switched from those made of ceramics having a high heat resistance such as ceramics to those made of a relatively low heat resistant material such as metal. As a result, component costs can be reduced. Moreover, since the heat insulating property is high, the energy cost for heating and keeping the temperature inside the furnace can be reduced.

  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.

  For example, in the above embodiment, the drive shaft is constituted by a solid shaft and a hollow shaft, but the entire drive shaft may be a hollow shaft. By providing a heat insulating material with higher heat insulation than air in the hollow part, the heat transfer via the drive shaft from the inside of the heat treatment furnace to the outside of the furnace is suppressed without complicating the drive mechanism of the stirring fan in the furnace. There is an effect. Further, in the above embodiment, the solid shaft, the hollow shaft, the reinforcing plate, the in-furnace stirring fan, and the like are welded to each other, but the welding location and the welding length are appropriately changed. Further, the fixing method of each component is not limited to welding, and may be fixed by other methods.

  As described above, the hollow shaft has a structure in which, for example, a communication hole through which the atmosphere in the hollow shaft can pass through the atmosphere in the heat treatment furnace is provided at the bottom. In order to obtain such a structure, the hollow shaft may be made by making a hole in the bottom surface of a cylindrical member with a bottom surface, or a donut-shaped disk is prepared as a bottom surface member on the cylindrical member and the two are welded together. It may be produced by bonding. Further, when the drive shaft is constituted by the hollow shaft and the solid shaft, the heat insulating material may be inserted into the hollow shaft before or after the solid shaft is joined.

  As shown in FIG. 3, as another embodiment of the present invention, a cooling fan 17 for cooling the bearing 11 may be provided on the drive shaft inside the housing 5 (outside of the heat treatment furnace). The cooling fan 17 rotates in accordance with the rotation of the drive shaft 4. Thereby, in addition to the heat transfer suppression effect and the high heat insulation effect described in the above embodiment, a bearing cooling effect by wind generated by the rotation of the cooling fan 17 can also be obtained.

  The heat transfer to the outside of the heat treatment furnace when using the heat treatment apparatus according to the present invention and the conventional heat treatment apparatus was compared. The heat treatment apparatus according to the present invention is an apparatus having the configuration shown in FIG. 1 described in the above embodiment, and the conventional heat treatment apparatus has a solid drive axis as the drive shaft.

  First, the drive shaft temperature and the bearing temperature outside the heat treatment furnace were measured. The results are shown in FIG. The temperature measurement points are P1 and P2 shown in FIG. Moreover, the furnace temperature of the heat treatment furnace is 950 ° C.

  As a result of the temperature measurement, the shaft temperature P1 during the heat treatment was 285 ° C. in the conventional example, whereas it was 135 ° C. in the example. Further, the bearing temperature P2 during the heat treatment was 135 ° C. in the example compared to 165 ° C. in the comparative example. According to the results of this example, a part of the drive shaft is a hollow shaft, and a heat insulating material having higher heat insulation than air is provided in the hollow portion of the hollow shaft, thereby increasing the temperature of peripheral components via the drive shaft. It can be greatly suppressed. In the case of the present invention example, the bearing temperature is 150 ° C. or lower. For this reason, it can replace with the ceramic bearing conventionally used, and can employ | adopt the metal bearing which is not so high in heat resistance, and can reduce cost.

  Next, the amount of heat released from the drive shaft in the heat treatment furnace (example of the present invention: hollow shaft provided with a heat insulating material, conventional example: solid shaft) was measured. As a result, the conventional example was 67 kcal / h, whereas the example of the present invention was 31 kcal / h. Further, the amount of heat released from the drive shaft outside the heat treatment furnace (example of the present invention: solid shaft, conventional example: solid shaft) was also measured. As a result, the conventional example was 123 kcal / h, whereas the example of the present invention was 27 kcal / h. From these results, it is shown that according to the example of the present invention, heat radiation from the drive shaft can be greatly suppressed, and heat transfer to the peripheral components of the drive shaft can be suppressed. In particular, the amount of heat released from the drive shaft (solid shaft) outside the furnace of the heat treatment furnace in the present invention is extremely small compared to the conventional example. That is, the present invention suppresses an increase in the temperature of the peripheral components around the drive shaft, and also has a high heat insulating effect because heat transfer and heat dissipation from the drive shaft periphery are small.

  Next, the bearing temperature after the furnace stirring fan was stopped (after the heat treatment was completed) was measured. The results are shown in FIG. The temperature measurement point is P2 shown in FIG. According to FIG. 5, in the case of the conventional example, the residual heat in the heat treatment furnace is transmitted to the bearing through the drive shaft, and the bearing temperature increases with the elapsed time. On the other hand, according to the example of the present invention, the temperature of the bearing does not increase with the elapsed time, and the bearing temperature decreases when the elapsed time reaches 30 minutes. That is, according to the example of the present invention, it is possible to prevent the temperature rise of the peripheral components around the drive shaft due to the residual heat in the heat treatment furnace after the heat treatment is completed.

  The present invention can be applied to a heat treatment apparatus including an in-furnace stirring fan that stirs the atmosphere in the heat treatment furnace.

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 2 Furnace stirring fan 3 Heat processing furnace 4 Drive shaft 5 Housing 6 Motor 7 Solid shaft 8 Hollow shaft 9 Furnace shell 10 Heat insulating material 11 Bearing 12 Seal member 13 Communication hole 14 Furnace stirring fan upper plate 15 Reinforcement plate 16 Heat treatment furnace insulation 17 Cooling fan WP weld

Claims (10)

A heat treatment apparatus including an in-furnace agitation fan provided in a furnace of the heat treatment furnace and a drive shaft provided so as to penetrate the furnace body of the heat treatment furnace and connected to the in-furnace agitation fan. ,
At least a portion of the drive shaft is a hollow shaft;
In the heat treatment furnace, the furnace stirring fan is connected to the hollow shaft,
A heat treatment apparatus characterized in that a heat insulating material having a higher heat insulating property than air is provided in a hollow portion of the hollow shaft.   The heat treatment apparatus according to claim 1, wherein the hollow shaft is formed so that the hollow shaft and the heat treatment furnace communicate with each other.   3. The heat treatment apparatus according to claim 1, wherein the drive shaft includes a hollow shaft and a solid shaft connected in series to the hollow shaft.   The heat treatment apparatus according to claim 3, wherein a joint between the solid shaft and the hollow shaft is located inside a furnace body surface of the heat treatment furnace.   5. The heat treatment apparatus according to claim 3, wherein a seal member that seals a gap formed between the heat treatment furnace and the solid shaft is provided.   6. The heat treatment apparatus according to claim 5, wherein a joint between the solid shaft and the hollow shaft is located inside the furnace from the furnace body surface of the heat treatment furnace and inside the furnace from the seal member. .   The heat treatment apparatus according to any one of claims 3 to 6, wherein the solid shaft is supported by a bearing provided outside the heat treatment furnace.   The heat treatment apparatus according to claim 3, wherein the hollow shaft and the solid shaft are connected in series by welding.   The heat treatment apparatus according to claim 1, wherein a cooling fan that cools a bearing that supports the drive shaft is provided on the drive shaft outside the heat treatment furnace. A manufacturing method for manufacturing the heat treatment apparatus according to claim 1,
After the hollow shaft and the solid shaft are fixed to each other by shrink fitting, the hollow shaft and the solid shaft are connected in series by welding to form the drive shaft. Production method.

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