JP4573290B2 - High pressure heat treatment furnace - Google Patents

Description

  The present invention relates to a high-pressure heat treatment furnace that heat-treats metals such as cemented carbide, ceramics, composites, etc. at a high pressure of 1 MPaG or more, and more particularly to a high-pressure heat treatment furnace that enables rapid cooling in the furnace.

  In a high-pressure heat treatment furnace that heat treats cemented carbides, ceramics, etc. at a normal pressure of 1 MPaG or higher, an important issue is how to shorten the cooling time of the furnace in order to shorten the cycle time and improve the quality of processed products. It has become. FIG. 3 is a schematic configuration diagram of a conventional general high-pressure heat treatment furnace as disclosed in Patent Document 1 below, for example. In FIG. 3, reference numeral 3 denotes a pressure vessel composed of a furnace vessel 1 and a furnace lid 2 that closes both ends of the furnace vessel 1, and jackets 4 and 5 are provided on the outer periphery of the furnace vessel 1 and on the outside of the furnace lid, respectively. The cooling water is circulated in the inside. A hollow cylindrical heat insulating wall 6 having openings at both ends is provided in the pressure vessel 3, an inner case 17 is disposed therein, and the object to be heated 7 is accommodated therein. Reference numeral 8 denotes a heat insulating lid (bang) for opening and closing the opening of the heat insulating wall 6, and is driven to open and close by a cylinder 9 provided outside the furnace lid 2. Reference numeral 10 denotes a heater for heating the article 7 to be heated, and a heating chamber 11 is formed inside the heat insulating wall 6. In addition, as shown in FIG. 4, instead of providing a cooling water jacket on the outer peripheral portion of the furnace vessel 1, there is a type in which a water cooling tube 12 for circulating cooling water is provided on the inner wall of the furnace vessel 1. 3 and 4, reference numeral 16 is a space formed between the pressure vessel 3 and the heat insulating wall 6.

  In this heat treatment furnace, the workpiece 7 is inserted into the heating chamber 11 and the heat insulating wall 8 is closed, and then an atmosphere gas is introduced into the heating chamber 11 and the workpiece 7 is placed in a gas atmosphere by the heater 10. After the heating and sintering, the processing object 11 is taken out after the atmosphere gas in the heating chamber 11 and the processing object 7 are sufficiently cooled.

FIG. 5 is a diagram showing a change in the furnace temperature (heating chamber temperature) during operation in the heat treatment furnace. As shown in this figure, at the operation start time t ₀ , the heater is energized to start the temperature rise, and the heat treatment is performed while maintaining a predetermined treatment temperature (eg, 1500 ° C.) from time t ₁ to time t _2. Do. Then, the process stops the current supply to the heater at time t ₂ has been completed is moved to the cooling step. In the cooling process, the heat insulating lid 8 is initially closed, and when the furnace temperature is lowered to a predetermined temperature T, the heat insulating lid 8 is opened. It is assumed that the time at temperature T is t ₃ . As a result, natural convection occurs due to the temperature difference between the heating chamber 11 and the space 16, and the gas 18 flowing out of the heating chamber 11 is cooled by heat exchange with the water-cooled furnace wall inner surface, thereby promoting the cooling of the furnace. It is like that.

  FIG. 6 shows a heat treatment furnace disclosed in Patent Document 2. This heat treatment furnace is characterized in that it includes an internal circulation fan 19, a motor 20 that rotationally drives the internal circulation fan 19, and a circulation gas guide plate 21. In the cooling step, as in the heat treatment furnace described above, the heat insulating lid 8 is initially closed, and when the furnace temperature is lowered to a predetermined temperature, the heat insulating lid 8 is opened. The hot gas 18 in the heating chamber 11 is sucked from one opening (right side in the figure), and is circulated to the heating chamber 11 from the opposite opening (left side in the figure) by the circulation gas guide plate 21. Yes. This generates forced gas convection, promotes heat exchange with the inner surface of the pressure vessel 3, and improves the cooling capacity of the furnace.

Japanese Patent Laid-Open No. 4-26726 (FIG. 7) Japanese Utility Model Publication No. 62-55529 (FIG. 1)

However, the cooling method in the conventional high pressure heat treatment furnace described above has various problems as follows.
(1) In the system in which the jackets 4 and 5 are provided in the furnace vessel 1 and the furnace lid 2 as shown in FIG. 3, the heat transfer area is limited to the inner wall area of the pressure vessel 3. Low cooling capacity. Further, since the wall thickness of the pressure vessel 3 is thick enough to withstand high pressure, it is difficult to sufficiently cool the inner wall of the pressure vessel 3 even if water cooling is performed from the outer wall of the pressure vessel 3. For this reason, the cooling capacity is limited.
(2) In the method in which the water cooling tube 12 is provided on the inner wall of the furnace vessel 2 as shown in FIG. 4, the water cooling tube 12 itself is expensive. In order to secure 12 installation spaces, it is necessary to increase the furnace diameter. Further, there is a risk of water leakage and gas leakage from the water cooling tube 12. Furthermore, if the amount of water flow decreases due to clogging of dust in the water cooling tube 12, not only the cooling effect cannot be obtained, but there is also a risk that the water cooling tube 12 is damaged.
(3) In the system in which the internal circulation fan 19, the motor 20, and the circulation gas guide plate 21 are provided in the pressure vessel 3 as shown in FIG. 6, the structure becomes complicated due to the addition of the fan, the motor, etc., and the manufacturing cost increases. It becomes a factor. In addition, customer power facilities and running costs associated with power supply to the motor increase. In addition, there is a risk of failure due to bearing damage and the maintenance cost also increases. Moreover, depending on the wind pressure of the fan, there is a case where a lightweight object cannot be processed. Furthermore, the motor capacity is limited by the installation space of the motor, and the cooling capacity is limited.

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a high-pressure heat treatment furnace that has a high cooling capacity, can shorten the cycle time, has a simple structure, and is economical.

In order to achieve the above object, a high-pressure heat treatment furnace of the present invention includes a pressure vessel having a furnace vessel and a furnace lid for closing the furnace vessel, an opening provided at a position facing the furnace lid provided in the pressure vessel. A heat insulating wall that forms a heating chamber that accommodates an object to be processed, a heat insulating lid that is driven to open and close the opening of the heat insulating wall, and an object to be processed that is provided in the heating chamber. A heater for heating, a cooling member attached to the inner wall surface of the furnace lid and cooled by a refrigerant flowing through the inside, and a plurality of cooling fins connected to the cooling member for cooling the gas in the pressure vessel. wherein the cooling fins are oriented in the longitudinal direction of the fin in the direction along the flow of natural convection to thus resulting gas rather than fan after heating by the heater, open the opening by opening said heat insulating lid, Through the open opening Te, and wherein the plurality of cooling fins are provided as between the heating chamber and the pressure vessel in the outside of the heating chamber, in contact with the gas circulating by natural convection without depending on fan To do.

  In the high pressure heat treatment furnace of the present invention, it is preferable that the cooling fin and the cooling member are integrally formed.

  In the high-pressure heat treatment furnace of the present invention, each cooling fin preferably has a slit for absorbing thermal expansion.

  In the high-pressure heat treatment furnace of the present invention, the cooling fin is preferably made of a material having excellent thermal conductivity (aluminum, copper, etc.).

  According to the present invention, by providing a plurality of cooling fins for cooling the gas flowing in the pressure vessel, the cooling area in the pressure vessel is greatly increased, and as a result, the cooling performance is improved. Therefore, the effect that the cycle time of the furnace can be shortened is obtained.

  In addition, since there are no moving parts, there is no cause of malfunction, electricity or gas is not required, and there is no problem of life. Therefore, it is excellent in energy saving and can be used semipermanently.

  In addition, since the cooling fin is connected to the cooling member cooled by the refrigerant, the structure is simple and the number of parts is not increased so that the cost increase is minimized and economical. .

  Further, by attaching the cooling member to the inner wall surface of the furnace lid, it becomes possible to install it simply by extending the furnace vessel length, and the design is easy. In addition, since the cooling fins are in the vicinity of the position where the high temperature gas from the heating chamber is ejected, the cooling effect can be enhanced.

  Moreover, the clearance gap which arises in the connection part of a cooling fin and a cooling member can be eliminated by integrally forming a cooling fin and a cooling member. As a result, a sufficient amount of heat transfer between the cooling fins and the cooling member can be ensured to sufficiently exhibit the cooling performance.

  In addition, since each cooling fin has a slit for absorbing thermal expansion, deformation and breakage of the cooling fin can be prevented, and when the gas enters the slit, a vortex is generated in the gas flow and the cooling efficiency is improved. improves.

  Moreover, since the cooling fin is made of a material having excellent thermal conductivity, the gas in the pressure vessel can be effectively cooled. As a result, the cooling performance is improved and the cycle time of the furnace can be greatly shortened.

  Further, by setting the longitudinal direction of the cooling fin in a direction along the gas flow, natural convection is smoothly performed without hindering the gas flow, and good cooling performance can be exhibited.

  A preferred embodiment of the present invention will be described below in detail with reference to FIGS.

  FIG. 1 is a schematic configuration diagram showing an embodiment of a high-pressure heat treatment furnace of the present invention. In FIG. 1, reference numeral 3 is a pressure vessel composed of a hollow cylindrical furnace vessel 1 and a flat plate-like furnace lid 2 that closes both ends of the furnace vessel 1. The pressure vessel 3 is configured to be able to control the internal pressure. In addition, a jacket is provided on the outer periphery of the furnace vessel 1, and cooling water is circulated as a refrigerant inside to cool the furnace vessel 1.

  Reference numeral 6 denotes a hollow cylindrical heat insulating wall provided in the pressure vessel 3, an inner case 17 is disposed therein, and the article 7 to be heated is accommodated therein. Further, both ends of the heat insulating wall 6 have openings that open at positions facing the furnace wall 2. Reference numeral 8 denotes a heat insulating lid (bang) that opens and closes the opening of the heat insulating wall 6, and is opened and closed by a cylinder 9 provided outside the furnace cover 2. Reference numeral 10 denotes a heater for heating the article 7 to be heated, and a heating chamber 11 is formed inside the heat insulating wall 6. Reference numeral 16 denotes a space formed between the pressure vessel 3 and the heat insulating wall 6.

  Reference numeral 13 is a cooling fin for cooling the gas 18 in the pressure vessel 3, and is connected to a cooling member 14 attached to the inner wall surface of the furnace lid 2. The cooling member 14 has a circular flat plate shape, and has a structure in which cooling water flows as a refrigerant. Further, the cooling member 14 has an opening 14a for passing the rod of the cylinder 9 in the center. The cooling fins 13 have a rectangular flat plate shape, and a plurality of the cooling fins 13 are connected perpendicularly to one surface of the cooling member 14 at a predetermined interval. A metal material having excellent thermal conductivity is used for the cooling fin 13, and it is particularly preferable to use aluminum, copper, or the like having good thermal conductivity. Since copper has higher thermal conductivity than aluminum and a smaller linear expansion coefficient, it can be said that copper is more suitable as a material for the cooling fin than aluminum.

  In this embodiment, since the high-pressure heat treatment furnace is a horizontal type, the gas 18 blown out from the heating chamber 11 flows in the direction of the arrow. Accordingly, the cooling fins 18 are preferably set so that the direction along the direction in which the gas 18 flows, that is, the length direction (longitudinal direction) is directed in the vertical direction. Thereby, natural convection is performed smoothly without disturbing the flow of the gas 18, and good cooling performance can be exhibited.

  The cooling fin 13 may be provided with a slit for absorbing thermal expansion. For example, the slit may be provided with a plurality of notches extending in the width direction (short direction) of the cooling fin 13 over the length direction (longitudinal direction) of the cooling fin 13. Thereby, it is possible to prevent the deformation and breakage of the cooling fin by absorbing the thermal stress, and the effect that the cooling efficiency is improved by generating a vortex in the gas flow when the gas enters the slit.

  In FIG. 1, the cooling member 14 is attached to the furnace lid 2. The cooling water introduced into the cooling member 14 configured in this way cools the cooling member 14 and is discharged. The cooling fins 13 connected to the cooling member 14 are cooled by the cooling member 14.

  The cooling fins 13 and the cooling members 14 may be formed separately and then joined by welding or the like. However, it is difficult to closely contact all the mating surfaces of the cooling fins 13 and the cooling members 14. It is also conceivable that the cooling performance cannot be sufficiently exhibited. Therefore, in order to eliminate the gap between the cooling fin 13 and the cooling member 14, it is preferable to integrally form both. As a result, a sufficient amount of heat transfer between the cooling fins 13 and the cooling member 14 can be ensured.

Next, the operation of the high pressure heat treatment furnace of the present invention configured as described above will be described. FIG. 2 is a diagram showing changes in the furnace temperature (heating chamber temperature) during operation in the high-pressure heat treatment furnace of the present invention, the solid line shows the temperature change according to the present invention, and the broken line shows the conventional high-pressure of FIG. The temperature change by the heat treatment furnace is shown. As shown in this figure, at the operation start time t ₀ , the heater is energized to start the temperature rise, and the heat treatment is performed while maintaining a predetermined treatment temperature (eg, 1500 ° C.) from time t ₁ to time t _2. Do. Then, the process stops the current supply to the heater at time t ₂ has been completed is moved to the cooling step. In the cooling process, the heat insulating lid 8 is initially closed, and when the furnace temperature is lowered to a predetermined temperature T ′, the heat insulating lid 8 is opened. At this time, the high-temperature gas 18 in the heating chamber 11 blows out from the opening of the heat insulating wall 6 toward the space 16 and comes into contact with the cooling fins 13. Since the cooling fins 13 are cooled by the cooling members 14, the temperature T ′ when the opening and closing door is opened can be set to a temperature higher than the opening temperature T of the heat insulating lid of the conventional high-pressure heat treatment furnace in FIG. . As a result, the time t ₃ ′ for opening the heat insulating lid can be advanced from the time t _{3 in} FIG.

  The gas 18 that has come into contact with the cooling fins 13 circulates through the pressure vessel 3 while performing heat exchange with the cooling fins 13 while being cooled, and is circulated from the opening of the heat insulating wall 6 to the heating chamber 11. A large number of the cooling fins 13 are provided in the pressure vessel, and the cooling area thereof is greatly increased compared to the conventional case, so that the cooling performance is high. As a result, as shown in FIG. 2, the cooling time can be greatly shortened, and the effect that the cycle time of the furnace can be shortened can be obtained. For example, the cooling time can be shortened to about half compared to the conventional case.

  In the present invention, the following effects can be obtained in addition to the effects described above. That is, since there is no moving part in the cooling mechanism of the furnace, there is no cause of malfunction, electricity or gas is not required, and there is no problem of life. Therefore, it is excellent in energy saving and can be used semipermanently. In addition, since the cooling fin is connected to the cooling member 14 that is cooled by the refrigerant, and the cooling member 14 is attached to the inner wall portion of the pressure vessel 3, a cooling method using a water cooling tube, a cooling method using a motor and a fan, etc. Compared to, the structure is simple and the number of parts is not increased so that the cost increase can be minimized. In addition, by attaching the cooling member 14 to the inner wall of the furnace lid 2, it can be installed simply by extending the length of the furnace vessel, and the design is easy.

  In the above-described embodiment, the furnace lid 2 of the pressure vessel 3 is a flat plate, but it may be a curved end plate. In this case, the side of the cooling member 14 facing the furnace lid 2 is formed according to the curved shape of the end plate.

  In the above-described embodiment, the horizontal type sintering furnace has been described. However, the present invention is naturally applicable to a vertical type sintering furnace.

  In addition, the present invention is not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention.

It is a schematic block diagram of embodiment of this invention. It is a figure which shows the mode of the change of the furnace temperature (heating chamber temperature) at the time of operation in the high-pressure heat treatment furnace of this invention. It is a schematic block diagram of the conventional high-pressure heat treatment furnace. It is a schematic block diagram of the conventional high-pressure heat treatment furnace. It is a figure which shows the mode of the change of the furnace temperature (heating chamber temperature) at the time of operation in the high pressure heat processing furnace of FIG. 3, FIG. It is a schematic block diagram of the conventional high-pressure heat treatment furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace vessel 2 Furnace lid 3 Pressure vessel 4 Jacket 6 Heat insulation wall 7 Heated object 8 Heat insulation lid 9 Cylinder 10 Heater 11 Heating chamber 13 Cooling fin 14 Cooling member 16 Space 17 Inner case 18 Gas

Claims (4)

A pressure vessel having a furnace vessel and a furnace lid for closing the furnace vessel;
A heat insulating wall that is provided in the pressure vessel, has an opening at a position facing the furnace lid, and forms a heating chamber that accommodates an object to be processed therein;
A heat insulating lid that is driven to open and close the opening of the heat insulating wall;
A heater provided in the heating chamber for heating an object to be processed;
A cooling member attached to the inner wall surface of the furnace lid and cooled by a refrigerant flowing through the interior;
A plurality of cooling fins connected to the cooling member and cooling the gas in the pressure vessel,
The cooling fins are oriented in the longitudinal direction of the fin in the direction along the flow of the thus generated gas to natural convection without a fan,
After heating by the heater, the heat insulating lid is opened to open the opening, and through the opened opening, between the inside of the pressure vessel outside the heating chamber and the heating chamber, it is natural not to use a fan. The high-pressure heat treatment furnace , wherein the plurality of cooling fins are provided so as to come into contact with a gas circulated by convection .   The high-pressure heat treatment furnace according to claim 1, wherein the cooling fin and the cooling member are integrally formed.   The high-pressure heat treatment furnace according to claim 1, wherein each cooling fin has a slit for absorbing thermal expansion.   The high-pressure heat treatment furnace according to claim 1, wherein the cooling fin is made of a material having excellent thermal conductivity.

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