JP2007297664A - Reduced pressure slow-cooling apparatus and heat treatment apparatus for steel member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a slow-cooling apparatus which can suppress the occurrence of cooling strain in comparison with a conventional apparatus and also can exhibit high cooling efficiency in the low possibility of the occurrence of the cooling strain, and to provide a heat treatment apparatus including this excellent slow-cooling apparatus and a carburizing treatment apparatus. <P>SOLUTION: A reduced pressure slow-cooling apparatus is provided with: a cooling chamber 10 closable while housing a material 2 to be treated; a pressure reducing device for reducing the pressure in the cooling chamber 10; a cooling fan 11 for circulating cooling gas in the cooling chamber and can change the circulating speed of the cooling gas; heat exchangers 12, 13 for cooling the cooling gas; and blasting guides 15, 16 for changing over the circulating route of the cooling gas. This apparatus is constituted so as to switched into a rapid cooling mode for contacting the cooling gas with the heat exchangers 12, 13 and circulating the gas or a slow cooling mode for circulating the cooling gas without contacting the gas with the heat exchangers 12, 13 by operating the blasting guides 15, 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gradual cooling apparatus for gradually cooling a material to be treated such as a steel member in a high temperature state, and a steel member heat treatment apparatus including the gradual cooling apparatus.

For example, as a device for cooling a material to be treated such as a heated high-temperature steel member, a cooling gas (atmosphere gas) is circulated by a fan in a cooling chamber that accommodates the material to be treated, and the cooling gas and the material to be treated are circulated. There is a device that performs a cooling process by exchanging heat with.
In addition, in order to suppress the occurrence of cooling distortion due to uneven cooling, measures such as changing the circulation speed of the cooling gas or providing a baffle plate so that the circulation path is appropriate can be used. There has been proposed a gas-cooled vacuum heat treatment furnace that aims to be non-existent (see Patent Document 1).

  However, the conventional gas-cooled vacuum heat treatment furnace does not always provide a sufficiently uniform cooling effect, and there is a problem that the dimensional accuracy varies in the material to be processed which is likely to generate cooling distortion. In particular, the cooling by the gas-cooled vacuum heat treatment furnace described in Patent Document 1 is intended for uniform and high-speed cooling, and it is difficult to suppress cooling distortion in a material to be processed with strict dimensional accuracy such as gears. Met.

  Further, gears or ring-shaped steel members are often subjected to carburizing treatment as a treatment for increasing the surface hardness while maintaining toughness. The carburizing treatment is a treatment for increasing the surface carbon concentration in a state where the steel member is heated to the austenitizing temperature or higher. Conventionally, a so-called carburizing and quenching process is often performed immediately after the carburizing process, in which a quenching process such as oil quenching is performed to ensure the toughness of the core and to increase the surface hardness. However, it is difficult for a steel member subjected to carburizing and quenching to solve the problem of distortion. For this reason, a method has been developed in which parts with strict dimensional accuracy are gradually cooled after carburizing, and then subjected to induction hardening locally (see Patent Document 2).

  When the combination of slow cooling after carburizing and induction hardening is performed, it is necessary to maintain high dimensional accuracy before induction hardening. That is, it is necessary not to generate distortion in the steel member in the slow cooling step after the carburizing process.

  However, when the steel member is cooled from the state above the austenitizing temperature, the steel member may be distorted even if it is slowly cooled. The cause of the distortion during the slow cooling is considered as follows. That is, when cooling a steel member from a high temperature, the cooling gas is circulated as described above, and forced cooling is often performed to collide with the material to be treated. The difference in the cooling effect increases between the two, and distortion is generated accordingly. Further, even when forced cooling is stopped, the retention of the cooling gas having different temperatures causes a difference in cooling effect, resulting in distortion.

Such distortion caused by gradual cooling, particularly in gears and other ring-shaped parts, leads to a decrease in roundness and dimensional accuracy in the axial direction, which greatly affects product quality.
In addition to carburizing treatment of gears and other ring-shaped parts, the development of a slow cooling device capable of enhancing the effect of suppressing cooling distortion when cooling a heated material to be treated includes heat treatment of steel members and the like. It was highly desired in the technical field.
On the other hand, slow cooling when the possibility of occurrence of cooling distortion is low leads to a decrease in production efficiency due to an increase in cooling time. Therefore, development of a highly practical slow cooling device that can be performed by appropriately switching between optimal slow cooling and efficient rapid cooling is desired.

JP 2005-29872 A Japanese Patent Laid-Open No. 11-131133

  The present invention has been made in view of such conventional problems, and it is possible to suppress the occurrence of cooling distortion as compared with the prior art, and to improve the cooling efficiency when the possibility of occurrence of cooling distortion is low. And a heat treatment apparatus including the excellent slow cooling apparatus and carburizing apparatus.

The first invention includes a cooling chamber that can be sealed in a state in which a material to be treated is accommodated,
A decompression device for decompressing the cooling chamber;
A cooling fan that circulates the cooling gas in the cooling chamber and can change the circulation speed;
A heat exchanger for cooling the cooling gas;
A ventilation guide for switching the cooling gas circulation path,
By operating the blower guide, it is possible to switch between a rapid cooling mode in which the cooling gas is circulated in contact with the heat exchanger and a slow cooling mode in which the cooling gas is circulated without being in contact with the heat exchanger. It is in the reduced pressure slow cooling apparatus characterized by the above-mentioned (Claim 1).

The reduced-pressure slow cooling device of the present invention has both the above-described configuration, and thus has both an excellent cooling strain suppression effect (slow cooling effect) and a cooling efficiency improvement effect (rapid cooling effect) when the possibility of occurrence of cooling strain is low. Obtainable.
First, the cooling chamber in the reduced pressure gradual cooling device can be depressurized by the depressurizing device, and the circulation speed of the cooling gas can be changed by the cooling fan. Therefore, even when a material to be processed that is very susceptible to cooling distortion is processed, generation of the cooling distortion can be suppressed as much as possible.

That is, when the cooling gas is stirred (circulated) during cooling, the cooling gas is reduced in pressure to reduce the difference in cooling rate between the upstream and the downstream of the circulating cooling gas compared to the atmospheric pressure state. Can be reduced. On the other hand, even in the case where stirring is not performed at all, in the reduced pressure state, the difference in cooling rate due to the residence of the cooling gas having different temperatures can be reduced as compared with the case of atmospheric pressure.
By utilizing the effect of such a reduced pressure of the cooling gas, the generation of distortion can be suppressed even if the workpiece is susceptible to cooling distortion, and the cooling process is performed while maintaining high dimensional accuracy. Can do.

  The slow cooling effect can also be improved by lowering the cooling gas circulation rate than usual. For this reason, it is possible to obtain even more excellent slow cooling conditions by the synergistic effect of the above-described cooling gas decompression effect and circulation rate reduction effect.

Furthermore, in the reduced pressure gradual cooling device, it has the heat exchanger and the air blowing guide, and by operating the air blowing guide, a quenching mode for circulating the cooling gas in contact with the heat exchanger; The cooling gas is configured to be switchable to any one of a slow cooling mode in which the cooling gas is circulated without being brought into contact with the heat exchanger.
Thereby, when the said slow cooling mode is selected, since the circulating cooling gas is not cooled by the heat exchanger, it is maintained in a high temperature state to some extent. Therefore, the cooling ability itself with respect to a to-be-processed material is suppressed, and a slow cooling effect can further be improved by the combination of the pressure reduction mentioned above and the circulation speed reduction or both.

  In addition, when processing a material to be processed with little occurrence of cooling distortion, or when cooling in a relatively low temperature range where there is little risk of occurrence of cooling distortion, the cooling efficiency can be improved by selecting the rapid cooling mode. Can be improved. That is, by operating the air blowing guide and bringing the cooling gas into contact with the heat exchanger to exchange heat, it is possible to always bring a relatively low-temperature cooling gas having a high cooling ability into contact with the material to be processed. Thereby, the cooling efficiency can be improved. It is also possible to further improve the cooling efficiency, particularly by maximizing the circulation speed of the cooling gas.

  As described above, according to the present invention, there is provided a slow cooling device that can suppress the occurrence of cooling distortion as compared with the conventional case and can improve the cooling efficiency when the possibility of occurrence of cooling distortion is low. Can be provided.

The second invention is a carburizing apparatus for carburizing a material to be processed made of a steel member,
And a slow cooling device for cooling the material to be treated after the carburizing treatment,
The slow cooling device is a steel member heat treatment device characterized by comprising the reduced pressure slow cooling device of the first invention.

The heat processing apparatus of this invention processes the to-be-processed material which consists of a steel member especially, Comprising: It has the said carburizing processing apparatus. And it also has the pressure reduction slow cooling apparatus mentioned above as a slow cooling apparatus. Therefore, the heat treatment apparatus can cool the material to be treated in a high temperature state, which has been carburized by the carburizing apparatus, with the cooling distortion suppressed as much as possible by using the reduced pressure annealing apparatus, and has a dimensional accuracy. Carburizing treatment can be performed without deteriorating.
Then, for example, the entire carburizing and quenching process can be carried out in a state in which the dimensional accuracy is maintained high by combining with induction hardening that is less likely to cause distortion.

In the reduced pressure gradual cooling device of the first aspect of the invention, the cooling chamber has a lateral flow path through which the cooling gas passes without contacting the material to be treated, and the material to be in contact with the material to be treated. A rectifying plate that separates the central flow path through which the cooling gas passes is arranged,
The cooling gas sent from the fan installation zone in which the cooling fan is disposed passes through the side flow path or the central flow path and is sent to the folding zone located on the opposite side of the fan installation zone. , Configured to return to the fan installation zone from the folding zone through the central channel or the side channel,
It is preferable that the heat exchanger and the air guide are arranged in the folding zone (Claim 2).

In this case, the cooling gas can be circulated in a loop using the side flow path and the central flow path. At this time, when the heat exchanger is disposed in the vicinity of the fan installation zone, the cooling gas sucked and exhausted by the fan may come into contact with the heat exchanger at a relatively high speed and the heat exchange efficiency may be reduced. . On the other hand, as described above, by installing the heat exchanger and the air guide in the folding zone located on the opposite side of the fan installation zone across the side flow path and the central flow path, Thus, the cooling gas in a state where the air conditioner is in contact with the heat exchanger can be gently brought into contact with the heat exchanger, thereby efficiently cooling.
Further, the use of the folding zone facilitates the arrangement of the heat exchanger and the air guide.

In addition, the folding zone has a U-shaped channel that communicates between the side channel and the central channel, and the air blowing guide is pivoted in the U-shaped channel. The circulatory path in the U-shaped flow path can be switched between an inner peripheral path and an outer peripheral path depending on the swing position, and the heat exchanger It is preferable that it is disposed only in one of the inner peripheral path and the outer peripheral path.
In this case, the circulation path can be easily switched by the air guide, and the contact state between the heat exchanger and the cooling gas can be easily controlled.

In the heat treatment apparatus for steel members according to the second aspect of the invention, the carburizing apparatus includes a heating chamber that accommodates and heats the material to be treated, and a heated chamber that accommodates the heated material to be treated under reduced pressure. It is preferable to separately have a vacuum carburizing chamber for carburizing treatment in the carburizing gas.
In this case, an efficient so-called vacuum carburizing process can be performed by providing the vacuum carburizing chamber, and further, the heating step before the carburizing process can be performed by having the heating chamber separately from the vacuum carburizing chamber. And the vacuum carburizing process after a heating can be performed simultaneously in parallel, and a more efficient heat treatment can be performed.

  The heating chamber, the vacuum carburizing chamber, and the cooling chamber of the vacuum slow cooling apparatus are each configured to be capable of individually adjusting the internal reduced pressure state and individually controlling the introduction of atmospheric gas. It is preferable to provide a transfer device for moving the material to be processed so as to sequentially move the heating chamber, the vacuum carburizing chamber, and the cooling chamber.

In this case, the heating chamber, the vacuum carburizing chamber, and the cooling chamber can be individually adjusted for the internal decompression state and the introduction state of the atmospheric gas. Thus, it is possible to perform optimum processing in parallel. Therefore, the process can be performed very efficiently.
In addition, the material to be treated can be efficiently moved by providing a transfer device that moves the material to be treated so as to sequentially move the heating chamber, the vacuum carburizing chamber, and the cooling chamber.
By having such a configuration, as a continuous vacuum carburizing and slow cooling device, the vacuum carburizing process and the subsequent reduced pressure slow cooling process can be proceeded very efficiently.

  Further, it is preferable that a preparation chamber is connected to the carry-in port of the heating chamber, and the preparation chamber is independently configured to be able to be depressurized. In this case, the material to be treated before being charged into the heating chamber is accommodated in the preparation chamber, and an atmosphere state suitable for charging into the heating chamber can be obtained to further increase the efficiency. it can.

  Moreover, it is preferable that the said conveying apparatus is comprised so that conveyance of the heat processing jig | tool holding the said to-be-processed material is carried out (Claim 8). As a result, a stable conveyance state can be obtained, and a plurality of materials to be processed can be handled at the same time, so that higher efficiency can be achieved.

Further, the material to be treated is a ring-shaped member having a ring-shaped main body, and is placed on the heat treatment jig with the axis of the ring-shaped member in a vertical direction, or of the ring-shaped member. It can be configured such that the shaft is conveyed in a state of being suspended in a suspension frame provided in the heat treatment jig with a horizontal axis.
In the ring-shaped member, the roundness of the ring-shaped main body is often important. However, it is very effective to use the heat treatment apparatus of the present invention equipped with the above-described reduced pressure annealing apparatus, and cooling distortion Can be processed while suppressing as much as possible.
In addition, as described above, the support structure of the ring-shaped member by the heat treatment jig includes the support structure that is placed on the heat treatment jig with the axis of the ring-shaped member in the vertical direction, and the axis of the ring-shaped member. It is possible to adopt a support structure that hangs horizontally on a suspension frame provided on the heat treatment jig.

Moreover, the said to-be-processed material can be used as the gear member which has a tooth | gear part in the outer peripheral surface or inner peripheral surface of the said main-body part (Claim 10).
In the case of a gear member, the dimensional accuracy is particularly strict, and it is particularly effective to use the heat treatment apparatus of the present invention. Examples of the gear member include a ring gear that is a component of an automatic transmission or the like.

Example 1
A vacuum slow cooling apparatus according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 1 to 3, the reduced pressure gradual cooling device 1 of the present example includes a cooling chamber 10 that can be sealed in a state in which the material to be processed 8 is accommodated, and a decompression device (not shown) that depressurizes the inside of the cooling chamber 12. The cooling gas is circulated in the cooling chamber 10, and the cooling fan 11 capable of changing the circulation speed, the heat exchangers 12 and 13 for cooling the cooling gas, and the air flow for switching the circulation path of the cooling gas. Guides 15 and 16 are provided. Then, by operating the air blowing guides 15 and 16, a quenching mode in which the cooling gas is circulated in contact with the heat exchangers 12 and 13, and slow cooling in which the cooling gas is circulated without being in contact with the heat exchangers 12 and 13 It can be switched to either mode.
This will be described in detail below.

  As shown in FIGS. 1 and 2, in the cooling chamber 10 of the reduced pressure gradual cooling apparatus 1, side flow passages 101 and 102 for passing the cooling gas to the periphery thereof without contacting the material 8 to be processed, A pair of left and right rectifying plates 141 and 145 that separate the central flow path 104 through which the cooling gas passes so as to come into contact with the material to be processed 8 are disposed. That is, in this example, a pair of left and right side flow paths 101 and 102 provided on both sides in the cooling chamber 10 when viewed from the front, and a central passage 104 at the center in the left and right direction are the pair of left and right rectifying plates 141, It is partitioned by 145. The fan installation zone Z1 is above the upper ends of the current plates 141 and 145, and the turn-back zone Z2 is below the lower ends.

  As shown in the figure, the rectifying plates 141 and 145 have lower end portions 142 and 146 having a smooth curved surface. A pair of arc-shaped rectifying plates 143 and 147 are provided in the turn-back zone Z2 so as to face the pair of lower end portions 142 and 146. The arc-shaped rectifying plates 143 and 147 have a curved shape that bends upward from the bottom in the cooling chamber 10 toward the center in the width direction, that is, a shape in which the upper surface side is concave.

  Therefore, a U-shaped flow path surrounded by the lower end portion 142 of the rectifying plate 141 and the arc-shaped rectifying plate 143 is formed on the right side in FIG. On the left side, a U-shaped channel surrounded by the lower end 146 of the current plate 145 and the arc-shaped current plate 147 is formed.

  In the U-shaped flow path on the right side in the drawing in the turn-back zone Z2, the seven heat exchanging portions 121 are arranged in two rows so that they are substantially perpendicular to the cooling gas flow with respect to the rectifying plates 141 and 145. An obliquely arranged heat exchanger 12 is arranged. Similarly, in the U-shaped flow path on the left side in the drawing in the turn-back zone Z2, a heat exchanger 13 in which seven heat exchanging portions 131 are diagonally arranged in two rows is disposed.

Air blow guides 15 and 16 are provided above the heat exchangers 12 and 13, respectively.
The air guide 15 on the right side of the figure includes a first guide plate 151 and a second guide plate 152, and is configured to swing around swing support points C1 and C2 in the U-shaped channel. Has been. For example, the swing fulcrum C1 and C2 are fixed inside the cooling chamber 10, and the second guide plate 152 has a support piece 153 so as to be V-shaped with the swing fulcrum C2 as a base point. Yes. A long hole 154 is provided in the support piece 153, and a support pin 106 of the lifter 105 described later is inserted into the long hole 154.

  In addition, gears 157 and 158 are provided at the swing fulcrums C1 and C2 of the first guide plate 151 and the second guide plate 152, respectively, from the state where the second guide plate 152 is erected (closed state). The first guide plate 151 is configured to swing in conjunction with the engagement of the gears 157 and 158 when swinging in a lying state (open state) or in the opposite direction. Has been. The first guide plate 151 and the second guide plate 152 both have a curved surface shape, and in the open state shown in FIG. 1, both function as a rectifying plate having a series of smooth curved surfaces. When switched to the closed state shown in FIG. 2, the flow path between the rectifying plate 141 is closed.

  Similarly, the air blow guide 16 on the left side in FIGS. 1 and 2 includes a first guide plate 161 and a second guide plate 162, each centering on the swing fulcrums C3 and C4 in the U-shaped flow path. Is configured to swing. The second guide plate 162 has a support piece 163 so as to be V-shaped with the swing fulcrum C4 as a base point. A long hole 164 is provided in the support piece 163, and a support pin 107 of the lifter 105 described later is inserted into the long hole 164.

  In addition, gears 167 and 168 are provided at the swing fulcrums C3 and C4 of the first guide plate 161 and the second guide plate 162, respectively, so that the second guide plate 162 is standing (closed). The first guide plate 161 is configured to swing in conjunction with the engagement of the gears 167 and 168 when swinging in a lying state (opened state) or in the opposite direction. Has been. Further, both the first guide plate 161 and the second guide plate 162 have a curved surface shape, and in the open state shown in FIG. In the closed state shown in FIG. 2, the flow path between the current plate 145 is closed.

As shown in FIGS. 1 and 2, support pins 106 and 107 that engage with the elongated holes 154 and 164 of the support pieces 153 and 163 connected to the second guide plates 152 and 162 are provided below the cooling chamber 10. A provided lifter 105 is provided. By raising the lifter 105, the air guides 15 and 16 are closed, and by lowering the lifter 105, the air guides 15 and 16 are opened.
Further, the lifter 105 includes a transport device 76 formed of a chain conveyor for transporting the material to be processed on the upper surface thereof.

  As shown in FIG. 3, the first guide plate 151 has a large number of slit portions 155. This is to avoid interference with a plurality of vertical rectifying plates 19 that are erected in the vertical direction on the surface of the rectifying plate 141. The first guide plate 161 described above also has a similar slit portion (not shown).

  By having such a configuration, the cooling gas sent from the fan installation zone Z1 in which the cooling fan 11 is disposed passes through the side passages 101 and 102 and is located on the side opposite to the position of the fan installation zone Z1. Is sent to the turn-back zone Z2, and returns from the turn-back zone Z2 through the central flow path 104 to the fan installation zone Z1. Here, as described above, the turn-back zone Z2 has a U-shaped channel that communicates between the side channels 101 and 102 and the central channel 104, and the air guides 15 and 16 swing. Depending on the position, the circulation path in the U-shaped channel can be switched between the inner circumferential path R2 (FIG. 1) and the outer circumferential path R1 (FIG. 2).

  In this example, since the heat exchangers 12 and 13 are disposed only at the positions corresponding to the outer peripheral path R1, the cooling is performed only when the air blowing guides 15 and 16 are closed as shown in FIG. Contact between the gas and the heat exchangers 12, 13 is possible. The heat exchangers 12 and 13 are connected to a refrigerant circulation device (not shown), and the refrigerant can be circulated inside the heat exchange units 121 and 131.

  Therefore, when the air blowing guides 15 and 16 are closed (FIG. 2), the cooling gas is cooled and circulated every time the cooling gas contacts the heat exchangers 12 and 13. Further, when the air blowing guides 15 and 16 are opened (FIG. 1), the cooling gas is in a slow cooling mode in which the cooling gas circulates in a relatively high temperature state without contacting the heat exchangers 12 and 13. .

  Further, as described above, the cooling fan 11 is configured to be able to change the circulation speed when the cooling gas is circulated. Specifically, it is possible to control between a state where the fan rotation speed is 0 rpm, which is not circulated, and a state where the fan rotates, which is the maximum circulation speed, is 1500 rpm. The cooling fan 11 of this example is housed in a housing 115 that is open at the bottom and sides, and is configured to discharge the cooling gas sucked from below to the sides.

  Further, a decompression device (not shown) for decompressing the inside of the cooling chamber 10 is connected via a vacuum valve 109 as shown in FIG. 3, and is configured so that the pressure in the cooling chamber 10 can be decompressed to 1 Pa. .

Since it has the above configuration, the reduced pressure gradual cooling device 1 of this example can obtain both an excellent cooling distortion suppression effect and a cooling efficiency improvement effect when the possibility of occurrence of cooling distortion is low.
First, the cooling chamber 10 in the reduced pressure gradual cooling device 1 can be depressurized by the depressurizing device, and the cooling fan 11 can also change the circulation rate of the cooling gas. Therefore, even when a material to be processed that is very susceptible to cooling distortion is processed, generation of the cooling distortion can be suppressed as much as possible.

For example, when the cooling gas is stirred (circulated) during cooling, the cooling gas is reduced in pressure to reduce the difference in cooling rate between the upstream and the downstream of the circulating cooling gas compared to the atmospheric pressure state. Can be reduced. On the other hand, even in the case where stirring is not performed at all, in the reduced pressure state, the difference in cooling rate due to the residence of the cooling gas having different temperatures can be reduced as compared with the case of atmospheric pressure.
By utilizing the effect of such a reduced pressure of the cooling gas, the generation of distortion can be suppressed even if the workpiece is susceptible to cooling distortion, and the cooling process is performed while maintaining high dimensional accuracy. Can do.

  The slow cooling effect can also be improved by lowering the cooling gas circulation rate than usual. For this reason, it is possible to obtain even more excellent slow cooling conditions by the synergistic effect of the above-described cooling gas decompression effect and circulation speed reduction effect.

Further, the reduced pressure gradual cooling device 1 has heat exchangers 12 and 13 and air blowing guides 15 and 16. By operating the air blowing guides 15 and 16, the cooling gas is brought into contact with the heat exchangers 12 and 13. It is possible to switch between a rapid cooling mode in which the cooling gas is circulated and a slow cooling mode in which the cooling gas is circulated without contacting the heat exchangers 12 and 13.
Thus, when the slow cooling mode is selected, the circulating cooling gas is not cooled by the heat exchangers 12 and 13, and thus is maintained at a high temperature to some extent. Therefore, the cooling capacity itself with respect to a to-be-processed material falls, and the slow cooling effect can further be improved by the combination of the pressure reduction mentioned above and / or the circulation speed reduction.

  In addition, when processing a material to be processed with little occurrence of cooling distortion, or when cooling in a relatively low temperature range where there is little risk of occurrence of cooling distortion, the cooling efficiency can be improved by selecting the rapid cooling mode. Can be improved. That is, by operating the air blowing guides 15 and 16 to bring the cooling gas into contact with the heat exchangers 12 and 13 to exchange heat, a relatively low temperature cooling gas having a high cooling capacity is always brought into contact with the workpiece. Can be made. Thereby, the cooling efficiency can be improved. It is also possible to further improve the cooling efficiency, particularly by maximizing the circulation speed of the cooling gas.

(Example 2)
In this example, as shown in FIG. 4, the reduced-pressure slow cooling apparatus 1 shown in Example 1 is incorporated in a heat treatment apparatus 2 as a continuous vacuum carburizing apparatus.
That is, as shown in the figure, the heat treatment apparatus 2 of this example cools the carburizing apparatus 6 for performing the carburizing process of the workpiece 8 made of a steel member and the workpiece 8 after the carburizing process. It has the said pressure reduction slow cooling apparatus 1 as a slow cooling apparatus for this.

  The carburizing apparatus 6 separately includes a heating chamber 4 that accommodates and heats the workpiece 8 and a vacuum carburizing chamber 5 that accommodates the heated workpiece 8 and performs carburizing treatment in a carburizing gas under reduced pressure. Have. Further, in this example, the preparation chamber 3 is connected in front of the heating chamber 4, and a first passage 45 is disposed between the heating chamber 4 and the vacuum carburizing chamber 5, and the vacuum carburizing chamber 5 and the cooling chamber are arranged. The second passage 55 is disposed between the second passage 55 and the second passage 55.

The preparation chamber 3 has an entrance door 31 that seals the carry-in port on the front side thereof, and a preparation chamber seal door 32 that seals the carry-out port on the rear side (a carry-in port to the heating chamber 4). Yes.
The heating chamber 4 has a heating chamber seal door 42 that can seal the carry-in port in front of the heating chamber 4 with the preparation chamber seal door 32 and seal the carry-out port behind it (the carry-in port of the vacuum carburizing chamber 5). is doing. Furthermore, the heating chamber 4 has heat insulating doors 411 and 412 at the front and rear to prevent heat during heating from leaking to the outside.

Further, the vacuum carburizing chamber 5 can be sealed at the front entrance by the heating chamber seal door 42, and the rear exit (the entrance of the cooling chamber 10) can be sealed by the cooling chamber seal door 181. It is configured. Further, the vacuum carburizing chamber 5 has heat insulating doors 511 and 512 at the front and rear for preventing heat at the time of heating from leaking to the outside.
The cooling chamber 10 is configured such that the front entrance can be sealed by the cooling chamber seal door 181, and the rear exit can be sealed by the exit door 182.

In addition, each chamber is configured such that the internal decompression state can be individually adjusted and the introduction of the atmospheric gas can be individually controlled.
Specifically, the preparation chamber 3 is configured such that the inside can be decompressed by a decompression device provided outside via a vacuum valve 309.
The heating chamber 4 is configured such that the inside can be decompressed by a decompression device provided outside via a vacuum valve 409. Further, the heating chamber 4 is provided with a nitrogen gas introduction valve 408 connected to an external nitrogen gas supply source.
The inside of the vacuum carburizing chamber 5 can be decompressed by a decompression device provided outside via a vacuum valve 509, and a desired carburizing gas is supplied from a carburizing gas supply device provided outside via a carburizing gas introduction valve 508. It is configured to be able to introduce. The vacuum carburizing chamber 5 is provided with a nitrogen gas introduction valve 507 connected to an external nitrogen gas supply source.
Further, as described above, the cooling chamber 10 is configured such that the inside can be decompressed by the decompression device provided outside via the vacuum valve 109. The cooling chamber 10 is provided with a nitrogen gas introduction valve 108 connected to an external nitrogen gas supply source.

The heating chamber 4 includes a fan 43 that circulates the atmospheric gas and includes a heater 44 that heats the atmospheric gas, and is configured to perform convection heating. In addition, the heating chamber 4 can also perform the vacuum heating which heats by the radiant heat of the heater 44 by making the vacuum state without operating the fan 43.
Further, the vacuum carburizing chamber 5 includes a carburizing chamber heater 54 and is configured to heat the workpiece 8 to a temperature suitable for carburizing.

In addition, the heat treatment apparatus 2 includes a transfer apparatus 72 that moves the material to be processed so as to sequentially move in the preparation chamber 3 (heating chamber 4), the first passage 45, the vacuum carburizing chamber 5, the second passage 55, and the cooling chamber 10. -76 are provided. Note that a supply line and a carry-out line for the material to be processed 8 to the heat treatment apparatus 2 are connected to the front of the preparation chamber 3 and the rear of the cooling chamber 10, respectively (not shown).
The first passage 45, the second passage, and the transfer devices 73, 75, and 76 in the cooling chamber 10 are all of the chain conveyor type, and the transfer device 72 serving as a transfer for the preparation chamber 3 and the heating chamber 4 is The pusher method and the transfer device 74 of the vacuum carburizing chamber 5 adopt a lift and carry method.

Next, operation | movement of the heat processing apparatus 2 of the said structure is demonstrated easily.
(Carrying material to be processed)
First, nitrogen gas is introduced into the preparation chamber 3 with the inlet door 31 and the preparation chamber seal door 32 of the preparation chamber 3 closed, and an atmospheric pressure state is obtained.
Next, the entrance door 31 is opened, and the material to be processed 8 is carried into the preparation chamber by interlocking the conveyance device of the carry-in line (not shown) with the conveyance device 71.
Next, in a state where the entrance door 31 and the preparation chamber seal door 32 are closed, the vacuum valve 309 is evacuated to make the inside of the preparation chamber 3 in a reduced pressure state.

(Carrying the heated material into the processing chamber)
The heating chamber 4 is evacuated from the vacuum valve 409 in a state where the preparation chamber seal door 32 and the heating chamber seal door 42 before and after the heating chamber 4 are closed. Then, when the heating chamber 4 and the preparation chamber 3 are in substantially the same decompressed state, the preparation chamber seal door 32 and the heat insulating door 411 are opened, and the conveyor chamber 72 of the preparation chamber 3 (heating chamber 4) is used. The processing material 8 is carried into the heating chamber 4. And the preparation room seal door 32 and the heat insulation door 411 are closed, and the center part of the heating chamber 4 is made into heat insulation and a sealing state. Further, the above operation is repeated, and the second set of workpieces 8 is carried into the heating chamber 4.

(Temperature rise of material to be treated)
The nitrogen gas introduction valve 408 of the heating chamber 4 is opened, nitrogen gas is introduced into the heating chamber 4, the pressure is restored to near atmospheric pressure (600 hPa), and the processing is performed by the heat of the heater 44 while stirring the atmospheric gas with the fan 43. The material 8 is heated by convection. Thereafter, after the temperature of the workpiece 8 reaches a high temperature range, the inside of the heating chamber 4 is depressurized via the vacuum valve 409 and switched to vacuum heating using radiant heat transfer.

(Carrying material into carburizing chamber)
After reducing the pressure in the heating chamber 4 and the vacuum carburizing chamber 5 to the same pressure, the heat insulating door 412 in the heating chamber 4, the heating chamber sealing door 42, and the heat insulating door 511 in the vacuum carburizing chamber 5 are opened, and the transfer devices 72 and 73 are connected. The material to be treated 8 is transported by using it and moved from the heating chamber 4 to the vacuum carburizing chamber 5. And the heating chamber seal door 42 and the heat insulation door 511 are closed, and the center part of the vacuum carburizing chamber 5 is insulative and sealed.

(Carburizing diffusion treatment)
After the workpiece 8 is heated by the carburizing chamber heater 54 and reaches a temperature suitable for the carburizing process, the carburizing gas introduction valve 508 is opened to introduce the carburizing gas for a predetermined time. At this time, the vacuum valve 509 is opened, and the vacuum state of the vacuum carburizing chamber 5 is maintained. After the predetermined carburizing process time has elapsed and the carburizing process is completed, the carburizing gas introduction valve 508 is closed and the diffusion process is performed.

(Cooling chamber conveyance of processed material)
After completion of the diffusion treatment, the pressures in the vacuum carburizing chamber 5 and the cooling chamber 10 are made the same, and then the heat insulating door 512 and the cooling chamber seal door 181 of the vacuum carburizing chamber 5 are opened. And the to-be-processed material 8 is moved using the conveying apparatuses 74-76, and it arrange | positions in the cooling chamber 10. FIG. Thereafter, the cooling chamber seal door 181 is closed, and the inside of the cooling chamber 10 is hermetically sealed.

(Cooling of treated material)
Various methods can be implemented for cooling the workpiece 8 by taking advantage of the function of the above-described reduced pressure gradual cooling apparatus 1.
For example, first, in the first 30 minutes of processing, the inside of the cooling chamber 10 is decompressed from the reduced pressure state of 0 hPa when the workpiece 8 is inserted to 200 hPa, and the rotation speed of the cooling fan 11 is increased. Drive down to a low speed of 100 rpm. Furthermore, the air blowing guides 15 and 16 described above are set in the open state (FIG. 1) to be in the slow cooling mode. Thereby, a very excellent slow cooling effect is obtained.
Next, nitrogen gas is introduced from the nitrogen gas introduction valve 108 to increase the pressure in the cooling chamber 10 to 600 hPa, and the rotation speed of the cooling fan 11 is increased to a maximum of 1500 rpm. Further, the air blowing guides 15 and 16 are set in a closed state (FIG. 2) to set a rapid cooling mode. As a result, efficient rapid cooling is realized in a temperature region where distortion is unlikely to occur.

(Removal of processing material)
After the cooling of the workpiece 8 is completed, nitrogen gas is introduced into the cooling chamber 10 to restore the atmospheric pressure. Thereafter, the outlet door 182 is opened, and the workpiece 8 is unloaded from the cooling chamber 10 by interlocking the transfer device 76 of the cooling chamber 10 and the unloading line transfer device (not shown).

As described above, the heat treatment apparatus 2 of the present example can continuously perform the vacuum carburization process and the subsequent cooling process by combining the reduced-pressure slow cooling apparatus 1 of Example 1 described above with the carburizing apparatus 6. A vacuum carburizing slow cooling device can be configured.
The point to be noted here is that since the vacuum slow cooling device 1 is incorporated, an excellent slow cooling effect is obtained in the initial stage of cooling, and an efficient and rapid cooling effect is obtained in the latter half of the cooling. is there.

That is, in a state where the cooling distortion of the workpiece 8 that has undergone the carburizing treatment is likely to occur, an excellent slowdown is realized by realizing a reduced pressure state, reducing the stirring speed of the cooling fan 11, and selecting the slow cooling mode by the air blowing guides 15 and 16. A cold effect can be obtained. Furthermore, when the material to be treated 8 is cooled to some extent and is not easily distorted, the reduced pressure state is released, the stirring speed of the cooling fan 11 is increased, and the quenching mode is selected by the air blowing guides 15 and 16. Excellent quenching effect can be obtained.
By providing the reduced pressure gradual cooling device 1 capable of obtaining these two contradictory effects, it is possible to perform the processing of the steel member that requires carburizing while maintaining very excellent dimensional accuracy. In addition, when performing a hardening process after that, it is preferable to apply the induction hardening method which does not generate | occur | produce distortion easily, and it is possible to maintain the said outstanding dimensional accuracy by this.

Next, an example of the heat pattern in the case of processing the to-be-processed material which is a steel member using the heat processing apparatus 2 of this example is shown.
As shown in FIG. 5, the heat pattern of this example is a combination of a 60-minute heating pattern P1, a 60-minute soaking pattern P2, and a 60-minute cooling pattern P3. Each is performed in the heating chamber 4, the vacuum carburizing chamber 5, and the cooling chamber 10 described above.

  FIG. 6 shows the cooling pattern P3 in more detail and detail. In the figure, time is taken on the horizontal axis, the rotational speed (a) of the cooling fan 11 is plotted on the first vertical axis, the temperature (b) of the material to be treated is plotted on the second vertical axis, and the cooling chamber 10 is plotted on the third vertical axis. The internal pressure (cooling gas pressure) (c) is taken. Further, the flow path switching state (d) is shown in FIG.

  As known from the figure, in this example, during the first cooling step P31, the air guides 15 and 16 are positioned in the open state (FIG. 1) and the U-shaped flow path of the turn-back zone Z2 is set. The slow cooling mode in which the inner peripheral side is the cooling gas circulation path is selected, the rotation speed of the cooling fan 11 is set low, and the cooling gas pressure is set to a reduced pressure state sufficiently lower than the atmospheric pressure to perform the reduced pressure slow cooling. It was.

  Next, during the second cooling step P32, the air blowing guides 15 and 16 are kept open, the cooling gas circulation path is kept in the slow cooling mode, and the rotational speed of the cooling fan 11 is sufficiently higher than the rated value. Although it is low, it is slightly higher than in the case of the first cooling step P31, and further, the cooling gas pressure is lower than the atmospheric pressure, but it is gradually cooled under reduced pressure under conditions set slightly higher than in the case of the first cooling step P31. In this example, the temperature of the material to be processed reaches the so-called A1 transformation point during the second cooling step P32.

  Next, during the third cooling step P33, the air guides 15 and 16 are changed to a closed state (FIG. 2), and the outer peripheral side of the U-shaped flow path in the turn-back zone Z2 is used as a cooling gas circulation path. The rapid cooling mode is set, and rapid cooling is performed under conditions in which the rotational speed of the cooling fan 11 and the cooling gas pressure are set sufficiently high.

  As described above, in the first cooling step P31 in which the first material to be treated is in the highest temperature state, the pressure of the cooling gas (pressure of the cooling chamber 10) and the circulation speed (the number of rotations of the cooling fan 11) are reduced, and Further, by performing the slow cooling in the state where the slow cooling mode is also selected for the circulation channel, it is possible to reliably suppress the occurrence of cooling distortion. Next, in the second cooling step P32 in which the material to be treated has been cooled to some extent, the possibility of occurrence of cooling distortion is reduced, so the cooling capacity is slightly increased, but the structure when exceeding the A1 transformation point of steel. The slow cooling condition is maintained in order to suppress the occurrence of distortion associated with transformation. Thereby, generation | occurrence | production of the distortion at the time of exceeding A1 transformation point can be suppressed as much as possible. Thereafter, in the third cooling step P33, the cooling gas pressure and the circulation speed can be maximized, and the cooling capacity can be maximized by setting the circulation flow path to the rapid cooling mode.

Next, an example of a heat treatment jig and a support structure for the material to be processed that can be used by the heat treatment apparatus 2 will be described.
As shown in FIG. 7, the heat treatment jig 91 of the first example is a heat treatment jig for placing the ring-shaped member 81 having the ring-shaped main body portion 810 with the axis centering in the vertical direction. As shown in the figure, the heat treatment jig 91 has a skeletal structure provided with a large number of voids 910 so that a cooling gas can flow therethrough. The heat treatment jig 91 has a plurality of positioning projections 912, and is configured so that the mounting position of each ring-shaped member 81 can be easily determined.
This heat treatment jig 91 is suitable for the case where the ring-shaped main body portion 810 is thin, and for the case of an internal gear in which the positioning projection 912 and the tooth surface do not contact with each other. Can be avoided.

As shown in FIG. 8, the heat treatment jig 92 of the second example is configured to be conveyed while being hung on a suspension frame 925 provided in the heat treatment jig 92 with the axis of the ring-shaped member 82 being in the horizontal direction. Heat treatment jig. As shown in the figure, the bottom plate portion 921 of the heat treatment jig 92 has a skeletal structure provided with a large number of gaps 920 so that a cooling gas can flow therethrough. A plurality of support columns 923 are set up on the bottom plate portion 921, and the support frame 923 supports the horizontal frame 924 and the suspension frame 925.
In the heat treatment jig 92 of this example, the ring-shaped main body 820 of the ring-shaped member 82 is relatively thick, and when it is suspended from the inner diameter side, there is almost no deformation due to its own weight. In the case of an external gear that does not abut, the load can be increased, which is optimal.

  Note that the heat treatment jig applicable to the heat treatment apparatus 2 is not limited to the above two examples, and can be changed to other forms.

(Example 3)
This example is an example in which the internal configuration of the vacuum slow cooling device 1 in the first embodiment is changed.
That is, as shown in FIG. 9 and FIG. 10, the reduced pressure gradual cooling device 1b of this example is provided so as to be inclined so that the rectifying plates 141b and 145b become wider as going downward. Each of them is provided with a vertical rectifying plate 19b.

Further, as shown in the figure, the cooling fan 11 is not provided with a housing, but the cooling gas is sucked from the lower center and discharged to the side.
Other configurations are the same as those of the first embodiment.

According to the reduced pressure gradual cooling device 1b of the present example, as described above, the vertical rectifying plates 19b are provided on both the inner and outer surfaces of the left and right rectifying plates 141b and 145b. Can be realized.
In other respects, the same effects as those of the first embodiment can be obtained.

Example 4
This example is an example in which the internal configuration of the vacuum slow cooling device 1 in the first embodiment is changed.
That is, as shown in FIG. 11 and FIG. 12, the reduced pressure gradual cooling device 1c of the present example enables the rectifying plates 141c and 145c to swing around the rotation shaft 140c at the upper end. It was configured to change the interval. Further, as shown in the figure, the cooling fan 11 is not provided with a housing, but the cooling gas is sucked from the lower center and discharged to the side.

Other configurations are the same as those of the first embodiment.
According to the reduced pressure gradual cooling device 1c of this example, the positions of the left and right rectifying plates 141c and 145c can be changed as described above, so that an optimal cooling gas circulation path can be formed according to the processed product. Further, since the flow rate of the cooling gas passing through the central flow path 104 can be changed by changing the positions of the left and right rectifying plates 141c and 145c without changing the number of rotations of the cooling fan 11, further fine processing conditions are realized. be able to.
In other respects, the same effects as those of the first embodiment can be obtained.

(Example 5)
This example is an example in which the internal configuration of the vacuum slow cooling device 1 in the first embodiment is changed.
That is, as shown in FIGS. 13 and 14, in the reduced-pressure slow cooling device 1 d of this example, the rectifying plates 141 d and 145 d are configured to have a substantially C-shaped cross section, and a cavity is provided inside. Further, no vertical rectifying plate was provided on the inner side surface and the outer side surface of the rectifying plates 141d and 145d.

Other configurations are the same as those of the first embodiment.
According to the reduced pressure slow cooling device 1d of the present example, the shape of the left and right rectifying plates 141d and 145d is substantially C-shaped as described above, so that the rectifying plates 141d and 145d and the material to be processed 8 are It becomes easy to secure a space between them, the flow of the cooling gas is adjusted, and the effect that the material to be treated can be cooled uniformly can be obtained. In other respects, the same effects as those of the first embodiment can be obtained.

Explanatory drawing which shows the state which is using the pressure reduction slow cooling apparatus in slow cooling mode in Example 1. FIG. Explanatory drawing which shows the state which is using the pressure reduction slow cooling apparatus in Example 1 in rapid cooling mode. Explanatory drawing which shows the structure seen from the side surface of the pressure reduction slow cooling apparatus in Example 1. FIG. Explanatory drawing which shows the structure of the heat processing apparatus (continuous vacuum carburizing slow cooling apparatus) in Example 2. FIG. Explanatory drawing which shows the outline | summary of the heat pattern in Example 2. FIG. Explanatory drawing which shows the change pattern of the cooling fan rotation speed at the time of cooling, the temperature of a to-be-processed material, and the pressure in a cooling chamber in Example 2. FIG. Explanatory drawing which shows an example of the support structure of the heat processing jig | tool and to-be-processed material which can be used with the heat processing apparatus in Example 2. FIG. Explanatory drawing which shows the other example of the support structure of the heat processing jig | tool and to-be-processed material which can be used with the heat processing apparatus in Example 2. FIG. Explanatory drawing which shows the structure seen from the front of the pressure reduction slow cooling apparatus in Example 3. FIG. Explanatory drawing which shows the structure which looked at the decompression slow cooling apparatus in Example 3 from the side surface. Explanatory drawing which shows the structure seen from the front of the pressure reduction slow cooling apparatus in Example 4. FIG. Explanatory drawing which shows the structure which looked at the decompression slow cooling apparatus in Example 4 from the side surface. Explanatory drawing which shows the structure seen from the front of the pressure reduction slow cooling apparatus in Example 5. FIG. Explanatory drawing which shows the structure which looked at the decompression slow cooling apparatus from Example 5 in the side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Decompression slow cooling apparatus 10 Cooling chamber 11 Cooling fan 12, 13 Heat exchanger 15, 16 Blower guide 2 Heat treatment apparatus 3 Preparation chamber 4 Heating chamber 5 Vacuum carburizing chamber 6 Carburizing processing apparatus

Claims (10)

A cooling chamber that can be sealed in a state in which a material to be treated is accommodated;
A decompression device for decompressing the cooling chamber;
A cooling fan that circulates the cooling gas in the cooling chamber and can change the circulation speed;
A heat exchanger for cooling the cooling gas;
A ventilation guide for switching the cooling gas circulation path,
By operating the blower guide, it is possible to switch between a rapid cooling mode in which the cooling gas is circulated in contact with the heat exchanger and a slow cooling mode in which the cooling gas is circulated without being in contact with the heat exchanger. A reduced pressure gradual cooling device characterized by comprising: 2. The cooling chamber according to claim 1, wherein the cooling chamber has a lateral flow path through which the cooling gas passes without contacting the material to be processed, and a central flow path through which the cooling gas passes so as to contact the material to be processed. A rectifying plate is arranged to separate
The cooling gas sent from the fan installation zone in which the cooling fan is disposed passes through the side flow path or the central flow path and is sent to the folding zone located on the opposite side of the fan installation zone. , Configured to return to the fan installation zone from the folding zone through the central channel or the side channel,
The reduced pressure gradual cooling device, wherein the heat exchanger and the air blowing guide are arranged in the folding zone.   In Claim 2, the said folding | turning zone has a U-shaped flow path which connects between the said side flow path and the said central flow path, and the said ventilation guide is in this U-shaped flow path. The heat exchanger includes a swingable guide plate having a swing fulcrum, and is configured to be able to switch a circulation path in the U-shaped flow path between an inner peripheral path and an outer peripheral path depending on a swing position. Is a reduced pressure gradual cooling apparatus, which is disposed only in either the inner peripheral path or the outer peripheral path. A carburizing apparatus for performing a carburizing process on a workpiece made of a steel member;
And a slow cooling device for cooling the material to be treated after the carburizing treatment,
The slow cooling apparatus comprises the reduced pressure slow cooling apparatus according to any one of claims 1 to 3, wherein the steel member heat treatment apparatus is characterized.   5. The carburizing apparatus according to claim 4, wherein the carburizing apparatus includes a heating chamber that accommodates and heats the material to be treated, and a vacuum carburizing chamber that accommodates the heated material to be treated and carburizes in a carburizing gas under reduced pressure. The heat processing apparatus of the steel member characterized by having separately.   6. The heating chamber, the vacuum carburizing chamber, and the cooling chamber of the reduced pressure gradual cooling device according to claim 5, wherein the internal reduced pressure state can be individually adjusted and the introduction of atmospheric gas can be individually controlled. A steel member heat treatment apparatus, further comprising a transfer device that moves the workpiece so as to sequentially move the heating chamber, the vacuum carburization chamber, and the cooling chamber.   7. The heat treatment apparatus for steel members according to claim 6, wherein a preparation chamber is connected to the carry-in port of the heating chamber, and the preparation chamber is configured to be able to be decompressed independently.   8. The steel member heat treatment apparatus according to claim 6, wherein the conveyance device is configured to be capable of conveying a heat treatment jig holding a plurality of the workpieces.   In Claim 8, the said to-be-processed material is a ring-shaped member which has a ring-shaped main-body part, and it mounts on the said heat processing jig | tool with the axial center of this ring-shaped member being perpendicular | vertical, or the said ring A steel member heat treatment apparatus, wherein the steel member is transported in a state of being hung on a suspension frame provided in the heat treatment jig with the axis of the cylindrical member in a horizontal direction.   The steel member heat treatment apparatus according to claim 9, wherein the material to be treated is a gear member having a tooth portion on an outer peripheral surface or an inner peripheral surface of the main body portion.

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