WO2017163732A1 - Cooling device and thermal treatment device - Google Patents

Abstract

This cooling device (R) cools an object (X) to be treated using a mist-like cooling liquid and is provided with a heat transfer coefficient switching means for switching the heat transfer coefficient of the mist-like cooling liquid from a relatively low state to a relatively high state during cooling of the object (X).

Description

Cooling device and heat treatment device

The present disclosure relates to a cooling device and a heat treatment device.
This application claims priority on March 23, 2016 based on Japanese Patent Application No. 2016-058930 filed in Japan, the contents of which are incorporated herein by reference.

For example, in Patent Document 1, as a quenching device, when a component heated to a predetermined temperature is cooled by spraying a mist-like coolant, the ambient pressure is decreased before the component temperature exceeds the martensite transformation temperature. It is described that the boiling point of the coolant is lowered. According to such a quenching device, by suppressing the boiling point of the coolant, the vapor film generated between the surface of the component and the coolant droplets is maintained, thereby suppressing distortion and deformation of the component. Is supposed to be possible.

Japanese Unexamined Patent Publication No. 2013-181226

In the above quenching apparatus, it is said that the distortion and deformation of parts are suppressed by maintaining the vapor film. However, since the maintenance of the vapor film involves complicated factors such as the shape of the part that is the object to be treated, during the cooling period of the object to be treated from the start of cooling to the temperature exceeding the martensitic transformation temperature, It is difficult to stably maintain the vapor film only by lowering the boiling point. That is, the method of maintaining the vapor film in order to suppress the distortion and deformation of the components is not always practical, and it is difficult to reliably suppress the distortion and deformation of the workpiece.

The present disclosure has been made in view of the above-described circumstances, and an object thereof is to more reliably suppress deformation of an object to be processed when the object to be processed is cooled by a mist-like coolant.

In order to achieve the above object, in the present disclosure, as a first solving means related to a cooling device, a cooling device that cools an object to be processed using a mist-like coolant, Heat transfer coefficient switching means for switching the heat transfer coefficient of the mist coolant from a relatively low state to a relatively high state is provided.

According to the present disclosure, since the method of switching the heat transfer coefficient of the mist coolant from a relatively low state to a relatively high state during the cooling of the workpiece, the deformation of the workpiece is more reliably performed than in the past. Can be suppressed.

It is a 1st longitudinal cross-sectional view which shows the whole structure of the cooling device and multi-chamber type heat processing apparatus which concern on one Embodiment of this indication. It is a 2nd longitudinal cross-sectional view which shows the whole structure of the cooling device which concerns on one Embodiment of this indication, and a multi-chamber type heat processing apparatus. FIG. 3 is a sectional view taken along line AA in FIG. 2. FIG. 3 is a sectional view taken along line BB in FIG. 2. It is a graph which shows the temperature change of the cooling process in one embodiment of this indication. It is a graph which shows the change of the mist particle size of the mist-like cooling fluid in the cooling process in one embodiment of this indication. It is a graph which shows the heat conductivity of each cooling medium. It is a graph which shows the relationship between the injection quantity for every nozzle in the experimental result of this indication, and a heat transfer rate.

Hereinafter, a cooling device R and a multi-chamber heat treatment device M according to an embodiment of the present disclosure will be described with reference to the drawings.

As shown in FIG. 1, the multi-chamber heat treatment apparatus M is a heat treatment apparatus in which a cooling device R, an intermediate transfer device H, and three heating devices are integrated. Since FIG. 1 shows a longitudinal sectional view at the center position in the horizontal direction of the intermediate transfer device H, FIG. 1 shows only two of the three heating devices, that is, the heating device K1 and the heating device K2. Is drawn.

The multi-chamber heat treatment apparatus M is a heat treatment apparatus for performing a quenching process on the workpiece X. The to-be-processed object X is various metal parts, and is a part which consists of steel materials, such as die steel (SKD material) and high-speed steel (SKH material).

The cooling device R is a device that cools the workpiece X. As shown in FIGS. 1 to 4, the cooling device R includes a cooling chamber 1 and a plurality of first and second cooling nozzles 2a and 2b (first and second injections). Nozzle), a plurality of mist headers 3, a cooling pump 4, a heat exchanger 5, a cooling drain pipe 6, a cooling water tank 7, first and second control valves 8a and 8b, a cooling control unit 9, and the like.

The plurality of mist headers 3, the cooling pump 4, the heat exchanger 5, the cooling water tank 7, the first and second control valves 8a and 8b, and the cooling control unit 9 constitute a coolant supply device in the present disclosure. Moreover, such a coolant supply apparatus and the plurality of first and second cooling nozzles 2a and 2b constitute a heat transfer coefficient switching unit in the present disclosure.

The cooling chamber 1 is a vertical cylindrical container (a container whose central axis is in the vertical direction) that accommodates the workpiece X, and the internal space is the cooling chamber RS. An intermediate transfer device H is provided on the cooling chamber 1. The cooling chamber 1 is formed with an opening that allows the cooling chamber RS to communicate with the internal space (the transfer chamber HS) of the intermediate transfer device H. The workpiece X is carried into or out of the cooling chamber RS through this opening.

The plurality of first and second cooling nozzles 2a and 2b convert a predetermined coolant supplied from the cooling pump 4 through the mist header 3 and the heat exchanger 5 into a mist-like coolant (mist-like coolant). These are first and second injection nozzles that convert and inject them onto the workpiece X. The first cooling nozzle 2a is a first injection nozzle having a relatively small injection hole diameter (first hole diameter), and the second cooling nozzle 2b has an injection hole diameter (second hole diameter) that is greater than that of the first cooling nozzle 2a. Is also a large second injection nozzle. That is, the particle size (first mist particle size) of the mist coolant injected from the first cooling nozzle 2a is the particle size (second mist particle size) of the mist coolant injected from the second cooling nozzle 2b. Smaller than. Then, the mist particle size of the mist coolant is changed to the first mist particle size by switching the supply destination of the coolant from the first injection nozzle (first cooling nozzle 2a) to the second injection nozzle (second cooling nozzle 2b). To the second mist particle size. The heat transfer coefficient switching means switches the heat transfer coefficient of the mist cooling liquid by adjusting the mist particle diameter of the mist cooling liquid from a relatively small particle diameter to a relatively large particle diameter.

The plurality of first and second cooling nozzles 2a and 2b are distributed around the workpiece X accommodated in the cooling chamber RS as shown in FIGS. . More specifically, the plurality of first and second cooling nozzles 2a and 2b are multistage (specifically, five stages) in the vertical direction around the workpiece X, and the cooling chamber 1 (cooling room RS). In a state of being spaced apart in the circumferential direction, the workpieces X are distributed and arranged so as to surround the workpiece X as a whole and so that the distance from the workpiece X is as equal as possible.

The plurality of first and second cooling nozzles 2a and 2b are grouped into a predetermined number. That is, the plurality of first and second cooling nozzles 2a and 2b are grouped for each stage in the vertical direction of the cooling chamber RS, and are also grouped into a plurality in the circumferential direction of the cooling chamber 1 (cooling chamber RS). Yes. In such a plurality of groups (nozzle groups), as shown in FIGS. 3 and 4, mist headers 3 are individually provided.

More specifically, as shown in FIG. 1, the mist headers 3 are arranged in five stages in the vertical direction, and two mist headers 3 are arranged around the workpiece X as shown in FIG. Is provided in an arc shape so as to surround. Further, in the four stages from the second stage to the lowest stage from the top, as shown in FIG. 4, three mist headers 3 are provided in an arc shape so as to surround the periphery of the workpiece X. Among the five-stage mist headers 3, the plurality of second cooling nozzles 2 b are provided in the uppermost stage, the third stage from the top, and the lowest stage mist header 3, and the plurality of first cooling nozzles 2 a It is provided in the second and fourth mist headers 3 from the top. The plurality of first and second cooling nozzles 2 a and 2 b are adjusted such that the direction of the nozzle shaft is directed to the workpiece X and the cooling supplied from the pump 4 via the mist header 3. The liquid is sprayed toward the workpiece X.

Further, the plurality of second cooling nozzles 2b belonging to the uppermost stage are arranged at a position higher than the upper end of the workpiece X in the vertical direction, as shown in FIG. On the other hand, the plurality of second cooling nozzles 2b belonging to the lowest stage are arranged at a height substantially equal to the lower end of the workpiece X. Furthermore, the plurality of second cooling nozzles 2b belonging to the uppermost stage are located inside the first and second cooling nozzles 2a and 2b in the other stages, that is, from the first and second cooling nozzles 2a and 2b in the other stages. Is also arranged away from the inner surface of the cooling chamber RS.

Here, the cooling liquid is a liquid having a lower viscosity than the cooling oil generally used for cooling the heat treatment, for example, water. The injection holes of the plurality of first and second cooling nozzles 2a and 2b are shaped so that a cooling liquid such as water becomes droplets having a uniform and constant particle diameter at a predetermined injection angle. In addition, the injection angles of the plurality of first and second cooling nozzles 2a and 2b and the interval between the first and second cooling nozzles 2a and 2b adjacent to each other are as shown in FIGS. Among the droplets ejected from the second cooling nozzles 2a and 2b, the droplets located on the outer peripheral side intersect or collide with the adjacent outer peripheral droplets ejected from the first and second cooling nozzles 2a and 2b. It is set to be.

Further, the plurality of first and second cooling nozzles 2a and 2b are configured to supply the mist-like cooling liquid so as to totally surround the workpiece X with the aggregate of cooling liquid droplets, that is, the mist-like cooling liquid. It injects toward the to-be-processed object X. The particle size of the droplets in the mist cooling liquid is, for example, 20 to 700 μm. The positions and angles of the plurality of first and second cooling nozzles 2a and 2b are appropriately set so that the mist-like cooling liquid around the workpiece X has a uniform particle diameter and a uniform density.

The cooling device R of the present embodiment is a device that cools the workpiece X using the mist-like coolant, that is, a device that mist-cools the workpiece X. The cooling conditions such as the cooling temperature and cooling time in the cooling device R are appropriately set according to the purpose of the heat treatment in the workpiece X, the material of the workpiece X, and the like.

The plurality of mist headers 3 described above are arc-shaped pipes communicating with the plurality of first and second cooling nozzles 2a and 2b, and the coolant taken in from the supply port is supplied to the plurality of first and second cooling nozzles 2a, Distribute to 2b. In these mist headers 3, the positions of the supply ports are set so that the pressure loss is substantially uniform for the plurality of first and second cooling nozzles 2a and 2b, and the coolant is supplied to the plurality of first and second cooling nozzles 2a. 2b is distributed almost uniformly.

Here, the heat transfer coefficient of the mist-like coolant sprayed from the plurality of first and second cooling nozzles 2a, 2b toward the workpiece X is the particle size (mist particle size) of the mist-like coolant. Dependent. The mist particle size is determined by the hole diameters (first and second hole diameters) of the injection holes of the first and second cooling nozzles 2a and 2b. That is, the mist-like cooling liquid having the first mist particle size sprayed from the first cooling nozzle 2a having the first hole diameter has a relatively low mist particle size and thus has a relatively low heat transfer coefficient (first heat transfer coefficient). On the other hand, since the mist-like cooling liquid having the second mist particle size ejected from the second cooling nozzle 2b having the second hole diameter has a mist particle size larger than the first mist particle size, it is higher than the first heat transfer coefficient. It has a high heat transfer coefficient (second heat transfer coefficient).

The cooling pump 4 pumps the coolant in the cooling water tank 7 to the mist header 3. The heat exchanger 5 is a temperature adjuster that adjusts (maintains) the temperature of the coolant supplied from the cooling pump 4 to the mist header 3 based on a temperature instruction input from the cooling control unit 9. That is, the temperature of the coolant supplied from the cooling pump 4 to the mist header 3 is managed by the cooling control unit 9.

The cooling drain pipe 6 is a pipe that communicates the lower part of the cooling chamber 1 with the cooling water tank 7, and a drain valve (not shown) is provided in the middle of the pipe. The cooling water tank 7 is a liquid container for storing the cooling liquid drained from the cooling chamber 1 through the cooling drain pipe 6 or the cooling circulation pipe (not shown). The cooling circulation pipe is a pipe that connects the upper part of the cooling chamber 1 and the upper part of the cooling water tank 7 in order to return the cooling liquid overflowing from the cooling chamber 1 to the cooling water tank 7 during the immersion cooling.

The first and second control valves 8 a and 8 b are open / close valves provided between the plurality of mist headers 3 and the heat exchanger 5. Of the first and second control valves 8a and 8b, the second control valve 8b is the uppermost, third and lowermost mist header 3 provided with the second cooling nozzle 2b, and the heat exchanger 5. The first control valve 8a is provided between the second and fourth mist headers 3 and the heat exchanger 5 from the top where the first cooling nozzle 2a is provided. That is, the first control valve 8a switches supply / non-supply of the coolant to the plurality of first cooling nozzles 2a based on the first opening / closing signal input from the cooling control unit 8. On the other hand, the second control valve 8 b switches supply / non-supply of the coolant to the plurality of second cooling nozzles 2 b based on the second opening / closing signal input from the cooling control unit 8.

The cooling control unit 9 controls the overall operation of the cooling device R by operating the heat exchanger 5, the first and second control valves 8a and 8b, the drain valve, and the like described above. As part of the control of the cooling device R, the cooling controller 9 controls the first and second control valves 8a and 8b to supply / not supply the coolant to the plurality of first and second cooling nozzles 2a and 2b. Switch supply. Accordingly, during the cooling of the workpiece X, the heat transfer coefficient of the mist coolant is switched from a relatively low state to a relatively high state. The details of the switching process of the heat transfer coefficient of the mist coolant by the cooling controller 9 will be described later.

The intermediate transfer device H includes a transfer chamber 10, a transfer chamber mounting table 11, a cooling chamber lifting table 12, a cooling chamber lifting cylinder 13, a pair of transfer rails 14, a pair of pusher cylinders (a pusher cylinder 15 and a pusher cylinder 16), and a heating chamber. A lift 17 and a heating chamber lift cylinder 18 are provided. The transfer chamber 10 is a container provided between the cooling device R and three heating devices including the heating device K1 and the heating device K2, and the internal space is the transfer chamber HS. The workpiece X is loaded into the transfer chamber 10 from a loading / unloading port (not shown) by an external transfer device while being accommodated in a container such as a basket.

The transfer chamber mounting table 11 is a support table that closes the delivery port between the cooling chamber 1 and the transfer chamber 10 when the processing object X is cooled by the cooling device R, and is capable of mounting another processing object X. ing. The cooling chamber lift 12 is a support table on which the workpiece X is placed when the workpiece X is cooled by the cooling device R, and supports the workpiece X so that the bottom of the workpiece X is exposed as much as possible. To do. The cooling chamber lifting platform 12 is fixed to the tip of the movable rod of the cooling chamber lifting cylinder 13.

The cooling chamber elevating cylinder 13 is an actuator that moves the cooling chamber elevating platform 12 up and down (up and down). That is, the cooling chamber elevating cylinder 13 and the cooling chamber elevating platform 12 are dedicated conveying devices for the cooling device R, and the workpiece X placed on the cooling chamber elevating platform 12 is transferred from the conveying area HS to the cooling chamber RS. The workpiece X is transferred from the cooling chamber RS to the transfer chamber HS while being transferred.

The pair of transfer rails 14 are laid on the floor in the transfer chamber 10 so as to extend in the horizontal direction. These transport rails 14 are guide members when transporting the workpiece X between the cooling device R and the heating device K1. The pusher cylinder 15 is an actuator that presses the workpiece X when the workpiece X in the transfer chamber 10 is transferred toward the heating device K1. The pusher cylinder 16 is an actuator that presses the workpiece X when the workpiece X is transported from the heating device K1 to the cooling device R.

That is, the pair of transport rails 14, the pusher cylinder 15, and the pusher cylinder 16 are dedicated transport devices that transport the workpiece X between the heating device K1 and the cooling device R. Although FIG. 1 shows a pair of transport rails 14, a pusher cylinder 15 and a pusher cylinder 16, an actual intermediate transport device H includes a total of three pairs of transport rails 14, a pusher cylinder 15 and a pusher cylinder 16. I have. That is, the conveyance rail 14, the pusher cylinder 15 and the pusher cylinder 16 are provided not only for the heating device K1 but also for the other two heating devices.

The heating chamber lift 17 is a support table on which the workpiece X is placed when the workpiece X is transferred from the intermediate transfer device H to the heating device K1. That is, the workpiece X is conveyed right above the heating chamber lifting platform 17 by being pressed rightward in FIG. 1 by the pusher cylinder 15. The heating chamber elevating cylinder 18 is an actuator that moves the workpiece X on the heating chamber elevating platform 17 up and down (up and down). That is, the heating chamber elevating table 17 and the heating chamber elevating cylinder 18 are dedicated conveying devices for the heating device K1, and the workpiece X placed on the heating chamber elevating table 17 is transferred from the conveying chamber HS to the inside of the heating device K1. The workpiece X is transferred from the heating chamber KS to the transfer chamber HS while being transferred to the (heating chamber KS).

Since the three heating devices basically have the same configuration, the configuration of the heating device K1 will be described below as a representative. The heating device K1 includes a heating chamber 20, a heat insulating container 21, a plurality of heaters 22, a vacuum exhaust pipe 23, a vacuum pump 24, a stirring blade 25, a stirring motor 26, and the like.

The heating chamber 20 is a container provided on the transfer chamber 10, and the internal space is the heating chamber KS. The heating chamber 20 is a vertical cylindrical container (a container whose central axis is in the vertical direction), similar to the cooling chamber 1 described above, but is smaller than the cooling chamber 1. The heat insulating container 21 is a vertical cylindrical container provided in the heating chamber 20 and is formed of a heat insulating material having a predetermined heat insulating performance.

The plurality of heaters 22 are rod-shaped heating elements, and are provided at predetermined intervals in the circumferential direction in the heat insulating container 21 in a vertical posture. The plurality of heaters 22 heats the workpiece X accommodated in the heating chamber KS to a desired temperature (heating temperature). The heating conditions such as the heating temperature and the heating time are appropriately set according to the purpose of the heat treatment for the workpiece X, the material of the workpiece X, and the like.

Here, the heating condition includes the degree of vacuum (pressure) of the heating chamber KS. The vacuum exhaust pipe 23 is a pipe that communicates with the heating chamber KS, and has one end connected to the upper part of the heat insulating container 21 and the other end connected to the vacuum pump 24. The vacuum pump 24 is an exhaust pump that sucks air in the heating chamber KS through the vacuum exhaust pipe 23. The degree of vacuum in the heating chamber KS is determined by the amount of air exhausted by the vacuum pump 24.

The stirring blade 25 is a rotating blade provided in an upper portion in the heat insulating container 21 in a posture in which the direction of the rotation axis is a vertical direction (vertical direction). The stirring blade 25 is driven by the stirring motor 26 to stir the air in the heating chamber KS. The stirring motor 26 is a rotational drive source provided on the heating chamber 20 so that the output shaft is in the vertical direction (vertical direction). The output shaft of the stirring motor 26 positioned on the heating chamber 20 is coupled to the rotating shaft of the stirring blade 25 positioned in the heating chamber 20 so as not to impair the airtightness (sealability) of the heating chamber 20. Yes.

Note that the multi-chamber heat treatment apparatus M according to this embodiment includes a control panel (not shown). The control panel includes an operation unit for a user to set and input various conditions in the heat treatment, various conditions input from the operation unit, and a control program stored in advance in the cooling device R, intermediate transfer devices H and 3. And a controller that operates the two heating devices in cooperation with each other. That is, the multi-chamber heat treatment apparatus M performs the quenching process on the workpiece X by automatically controlling the cooling device R, the intermediate transfer device H, and the three heating devices by the control panel.

Here, the above-described cooling control unit 8 is a functional component that performs cooling control of the workpiece X by the cooling device R among the control functions of the control panel. That is, in addition to the cooling control of the workpiece X by the cooling device R, the control panel performs the conveyance control of the workpiece X by the intermediate transfer device H and the heating control of the workpiece X by the three heating devices.

Next, the operation (quenching process) of the multi-chamber heat treatment apparatus M according to this embodiment will be described in detail with reference to FIGS. 5A and 5B.

In the quenching treatment by the multi-chamber heat treatment apparatus M, the workpiece X is heated to a predetermined temperature T1 (heating temperature), and then first cooled to a temperature T2 (cooling temperature) and then rapidly cooled to a martensite transformation point. Secondary cooling is performed. When quenching the workpiece X, the workpiece X is accommodated in the intermediate transfer device H from the loading / unloading port by the operator. When the loading / unloading port is closed by the operator and the inside of the transfer chamber HS becomes a sealed space, the intermediate transfer device H operates the pusher cylinder 15 to place the workpiece X on the heating chamber lifting platform 17. Move. Further, the intermediate transfer device H operates the heating chamber elevating cylinder 18 to accommodate the workpiece X in the heating chamber KS of the heating device K1.

Then, when the workpiece X is accommodated in the heating chamber KS, the heating device K1 operates the heater 22 to heat the workpiece X to the temperature T1. And the intermediate conveyance apparatus H will move the to-be-processed object X on the cooling chamber raising / lowering stand 12 by operating the heating chamber raising / lowering cylinder 18 and the pusher cylinder 16, if the said heating is completed. Further, the intermediate transfer device H moves the workpiece X to the cooling chamber RS by operating the cooling chamber elevating cylinder 13, and further blocks the delivery port between the transfer chamber 10 and the cooling chamber 1 by the transfer chamber mounting table 11. . Then, the cooling device R operates the cooling pump 4 to inject the mist-like cooling liquid from the plurality of first and second cooling nozzles 2a and 2b toward the workpiece X. As a result, the workpiece X is primarily cooled (mist cooling) from the temperature T1 to the temperature T2.

In this primary cooling (mist cooling), as shown in FIG. 5A, the workpiece X at temperature T1, that is, the workpiece X having an austenite structure, avoids the transformation point Ps (so-called pearlite nose) to the pearlite structure and reaches the temperature T2. It is cooled rapidly. That is, the workpiece X is rapidly cooled from the temperature T1 to the temperature T2 by the injection of mist-like cooling liquid from the plurality of first and second cooling nozzles 2a and 2b between time t1 and time t2 in FIG. 5A. . In FIG. 5A, the surface temperature history of the workpiece X is indicated by a solid line, and the internal temperature history of the workpiece X is indicated by a broken line.

Here, in the primary cooling (mist cooling) in the present embodiment, the switching operation from the state in which the heat transfer coefficient of the mist-like coolant is relatively low to the state in which it is relatively high at time ta, which is an intermediate time between time t1 and time t2. Is performed once. That is, the cooling control unit 9 sets the first control valve 8a to the open state and the second control valve 8b to the closed state in the period from the time t1 to the time ta (preliminary cooling period S1). As shown, a mist-like cooling liquid having a first mist particle size C1 is sprayed toward the workpiece X from the first cooling nozzle 2a. That is, in the first cooling period S1, the workpiece X is cooled by the mist cooling liquid having the first heat transfer coefficient.

In the period from time ta to time t2 (late cooling period S2), the cooling control unit 8 sets the first control valve 8a to the closed state and the second control valve 8b to the open state, that is, the coolant Is switched from the first cooling nozzle 2a to the second cooling nozzle 2b, so that the mist-like cooling liquid having the second mist particle size C2 is supplied from the second cooling nozzle 2b to the workpiece X as shown in FIG. 5B. Inject toward. That is, in the latter cooling period S2, the workpiece X is cooled by the mist cooling liquid having the second heat transfer coefficient higher than the first heat transfer coefficient in the first cooling period S1.

Here, the first heat transfer coefficient of the mist coolant in the first cooling period S1, that is, the first mist particle size C1, can suppress the deformation of the workpiece X due to the primary cooling (mist cooling) to the maximum. Is set to That is, the first mist particle size C1 is determined for each material and shape of the workpiece X through experiments performed in advance. Further, the previous cooling period S1, that is, the time ta is also determined for each material and shape of the workpiece X through experiments and the like performed in advance.

As explained in the background art, since the vapor film cannot be maintained by mist cooling, the parts (objects to be processed) are deformed. However, in the present embodiment, instead of maintaining the vapor film, by setting the first mist particle size C1 in the high temperature period of the workpiece X in which deformation can occur in the workpiece X, that is, the previous cooling period S1. Reduce the heat transfer coefficient of the mist coolant. As a result, the deformation of the workpiece X is suppressed by suppressing the cooling efficiency of the workpiece X.

In such mist cooling of the workpiece X during the previous cooling period S1, the temperature drop of the workpiece X is relatively slow. Therefore, if the mist cooling is performed with the mist-like coolant having the first mist particle size C1 in the late cooling period S2 as in the previous cooling period S1, the transformation point Ps to the pearlite structure should be avoided in the primary cooling. May not be possible. Therefore, in the present embodiment, mist cooling is performed in the late cooling period S2 with a mist-like coolant having a second mist particle size C2 having a particle size larger than the first mist particle size C1. Therefore, the cooling efficiency in the late cooling period S2 is improved more than the cooling efficiency in the previous cooling period S1, thereby realizing primary cooling avoiding the transformation point Ps to the pearlite structure.

Here, as shown in FIG. 6, a quenching silver cylinder in tap water, oil (JIS Japanese Industrial Standard C 2320-1999 Type 1 No. 2 oil), nitrogen (10 bar 15 m / s), which is a typical coolant. The surface heat transfer characteristic curve of each coolant calculated by the concentrated heat capacity method is known from the data of the cooling curve of the specimen (10 mm diameter, 30 mm length).
According to FIG. 6, it can be seen that in the high temperature region where the surface temperature of the silver cylindrical specimen is about 600 ° C. or higher, 30 ° C. tap water has a larger surface heat transfer coefficient than the 80 ° C. oil.

Therefore, a mist cooling experiment was performed using water as a mist-like cooling liquid of the test body (object to be processed), for example, using the following cooling device simulating the above embodiment.
A cooling device consists of a water tank, predetermined piping, and a nozzle.
The water tank has a capacity of 60 L and stores water used for cooling. The water tank is pressurized with nitrogen gas and connected to a predetermined pipe.
Two types of nozzles were adopted: a one-fluid nozzle that injects only water and a two-fluid nozzle that injects gas by using water to make it finer. More specifically, the one-fluid nozzle 1-1 has a 1 / 4M JJXP 060 HTPVC manufactured by Ikeuchi Co., Ltd., the one-fluid nozzle 1-3 has a 1/4 KSFHS 0865 manufactured by Everloy, and the one-fluid nozzle 1-4 has a A 1/4 KSAMF 1875-1 / 4 A24 1/4 W20 manufactured by Everloy Co., Ltd. was used for the M1 / 4 EX438 manufactured by Arakura Kogyo Co., Ltd. and the two-fluid nozzle 2-2, respectively. The nozzle is provided at an end of a predetermined pipe opposite to the end where the water tank is attached. The tip of the nozzle is installed at a position spaced 200 mm from the surface of the test body.
As a test body, disc-shaped stainless steel (JIS Japanese Industrial Standard SUS304) having a thickness of 50 mm and a diameter of 100 mm was used. The specimen is inserted into an electric furnace and heated to 1000 ° C.
The water stored in the water tank is pressurized with nitrogen gas, and the pressurized water is sprayed from the nozzle to the test specimen heated to 1000 ° C. Further, water is jetted from each nozzle so that the jet fluid pressure is 0.03 to 0.5 MPa.

Next, a temperature measurement method will be described.
The thermocouple is 180 in the circumferential direction at four positions of 2 mm, 6 mm, 10 mm, and 25 mm in the depth direction from the surface at the center position of the test body, and 25 mm from the upper end and 2 mm from the surface on the side surface of the test body. It is installed at a total of 6 locations, 2 ° shifted.
And the temperature change until the test body heated to 1000 degreeC is mist-cooled and becomes normal temperature is measured.

FIG. 7 shows the result of calculating the average heat transfer coefficient from the time change of the temperature of the thermocouple inserted into the test body after performing the mist cooling test. FIG. 7 shows the average heat transfer coefficient when the surface temperature of the specimen corresponds to a range of 600 to 1000 ° C.
The dotted line in FIG. 7 indicates the value when oil cooling is performed. When the one-fluid nozzle 1-3 or the two-fluid nozzle 2-2 is used, the mist cooling using water is not possible. However, almost the same heat transfer coefficient as oil cooling was achieved. That is, according to the cooling device using the mist cooling, the heat transfer coefficient of the mist cooling liquid can be reduced substantially equal to that of oil cooling. And deformation | transformation of the to-be-processed object X can be suppressed by suppressing the cooling efficiency of the to-be-processed object X. FIG.

As described above, according to the cooling device R in the present embodiment, the period during which the workpiece X is relatively high, that is, the first cooling period S1, and the period when the workpiece X is relatively low, that is, the latter cooling period S2. Since the mist particle size of the mist cooling liquid is adjusted from the first mist particle size C1 to the second mist particle size C2, deformation of the workpiece X is suppressed in the primary cooling and the transformation point Ps to the pearlite structure is avoided. It is possible.

In addition, this indication is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above embodiment, as shown in FIG. 5B, the heat transfer coefficient of the mist coolant is adjusted by adjusting the mist particle size of the mist coolant from the second mist particle size C1 to the first mist particle size C2. Is switched from the first heat transfer coefficient to the second heat transfer coefficient, but the present disclosure is not limited to this. The thermal conductivity may be switched from the first heat transfer coefficient to the second heat transfer coefficient by switching the density of the mist coolant (mist density). For example, the heat transfer coefficient of the mist coolant may be switched by adjusting the density of the mist coolant from a relatively low density to a relatively high density.

For example, a gas-liquid two-phase flow of a coolant and a predetermined gas is sprayed from the spray nozzle onto the workpiece X as a mist coolant, and the mist density is adjusted to the first mist density by adjusting the mixing ratio of the gas to the coolant. The heat transfer rate is switched from the first heat transfer rate to the second heat transfer rate by adjusting from to the second mist density. Instead of such adjustment of the mist density, the mist density may be switched by adjusting the flow rate of the coolant supplied to the injection nozzle.

(2) Although the first mist particle size C1 and the second mist particle size C2 are switched at the time ta as shown in FIG. 5B in the above embodiment, the present disclosure is not limited to this. For example, the mist-like coolant having the first mist particle size C1 and the mist-like coolant having the second mist particle size C2 are supplied from the first and second cooling nozzles 2a and 2b over a predetermined period (overlap period) from the time ta. Alternatively, only the mist-like coolant having the second mist particle size C2 may be injected from the second cooling nozzle 2b after the overlap period has elapsed.
That is, the mist particle size of the mist coolant is changed from the first mist particle size to the second mist particle through a state in which the mist coolant solution having the first mist particle size and the mist coolant solution having the second mist particle size are mixed. The diameter may be adjusted.

The overlap period is a period in which the mist coolant with the first mist particle size C1 and the mist coolant with the second mist particle size C2 coexist. That is, it is a period in which a mist-like coolant having a heat transfer coefficient located between the first heat transfer coefficient and the second heat transfer coefficient exists. By switching the mist particle size of the mist coolant from the first mist particle size C1 to the second mist particle size C2 through such an overlap period, switching from the first heat transfer coefficient to the second heat transfer coefficient. Can be relaxed. Therefore, according to the said structure, accumulation | storage of the thermal stress in the to-be-processed object X can be suppressed.

(3) In the above embodiment, the mist-like cooling liquid having the first mist particle size C1 is injected in the first cooling period S1, and the mist-like cooling liquid having the second mist particle size C2 is injected in the latter cooling period S2. The disclosure is not limited to this. In the late cooling period S2, in addition to the mist coolant having the second mist particle size C2, the mist coolant having the first mist particle size C1 may be injected. In this case, not only the mist particle size is increased and the heat transfer rate is increased, but also the mist density can be increased, so that the heat transfer rate can be further increased.

(4) In the above embodiment, as shown in FIG. 1, the multi-chamber heat treatment apparatus M (heat treatment apparatus) in which the cooling device R, the intermediate transfer device H, and the three heating devices are integrated has been described. The present disclosure is not limited to this. The necessary minimum components of the heat treatment apparatus are a heating apparatus and a cooling apparatus, as long as the heat treatment apparatus includes a heating apparatus that heats the workpiece and a cooling apparatus that cools the workpiece heated by the heating apparatus, The transport device such as the intermediate transport device H may be a separate body.

According to the cooling device and the heat treatment device of the present disclosure, since a method of switching the heat transfer coefficient of the mist-like coolant from a relatively low state to a relatively high state during the cooling of the workpiece, deformation of the workpiece is performed. Can be suppressed more reliably than before.

K1, K2 Heating device M Multi-chamber heat treatment device R Cooling device X Object 1 Cooling chamber 2a, 2b First and second cooling nozzles (first and second injection nozzles)
3 Mist Header 4 Cooling Pump 5 Heat Exchanger 6 Cooling Drain Pipe 7 Cooling Water Tank 8a, 8b First and Second Control Valves 9 Cooling Control Unit

Claims (7)

1. A cooling device for cooling an object to be processed using a mist-like coolant,
   A cooling device comprising heat transfer coefficient switching means for switching the heat transfer coefficient of the mist-like coolant from a relatively low state to a relatively high state during cooling of the workpiece.
2. The heat transfer coefficient switching means switches the heat transfer coefficient of the mist coolant by adjusting the mist particle size of the mist coolant from a relatively small particle size to a relatively large particle size. Cooling system.
3. The heat transfer coefficient switching means is
   A first injection nozzle that includes an injection hole having a first hole diameter, and that converts the mist particle size of the mist coolant into the mist coolant having a relatively small first mist particle size;
   A second injection nozzle that has an injection hole having a second hole diameter larger than the first hole diameter, and converts the cooling liquid into the mist-like cooling liquid having a second mist particle diameter larger than the first mist particle diameter;
   A coolant supply device for supplying the coolant to the first spray nozzle and the second spray nozzle;
   3. The mist particle size of the mist-like coolant is adjusted from the first mist particle size to the second mist particle size by switching the supply destination of the coolant from the first injection nozzle to the second injection nozzle. The cooling device as described.
4. The heat transfer coefficient switching means is configured such that the mist particle size of the mist coolant is a mixture of the mist coolant having the first mist particle size and the mist coolant having the second mist particle size. The cooling device according to claim 2, wherein the first mist particle size is adjusted to the second mist particle size via the first mist particle size.
5. The heat transfer coefficient switching means is configured such that the mist particle size of the mist coolant is a mixture of the mist coolant having the first mist particle size and the mist coolant having the second mist particle size. The cooling device according to claim 3, wherein the first mist particle size is adjusted to the second mist particle size.
6. The cooling device according to claim 1, wherein the heat transfer coefficient switching means switches the heat transfer coefficient of the mist coolant by adjusting the density of the mist coolant from a relatively low density to a relatively high density.
7. A heating device for heating the workpiece;
   A heat treatment apparatus comprising: the cooling apparatus according to any one of claims 1 to 6 that cools the workpiece heated by the heating apparatus.

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