WO2019030997A1

WO2019030997A1 - Hardening apparatus

Info

Publication number: WO2019030997A1
Application number: PCT/JP2018/017584
Authority: WO
Inventors: 田中　健一; 祐輝山下
Original assignee: 中外炉工業株式会社
Priority date: 2017-08-09
Filing date: 2018-05-07
Publication date: 2019-02-14
Also published as: TW201910520A; JP6713964B2; JP2019031724A

Abstract

Provided is a hardening apparatus that performs hardening processing of a workpiece, said apparatus comprising: a cooling bath that accommodates a liquid coolant for cooling the workpiece, which has been subjected to heating processing; a cooling unit that cools the coolant in the cooling bath; a heating unit that heats the coolant in the cooling bath; a temperature measuring unit that measures the temperature of the coolant in the cooling bath; and a control unit that controls the operations of the cooling unit and the heating unit. The control unit performs control in such a way that: after the end of the time during which the workpiece is hardened by means of the coolant, the cooling unit and the heating unit are not operated, and the coolant is allowed to cool; and, at a predetermined timing before the next workpiece is introduced, the cooling unit is operated to cool the coolant if the temperature of the coolant measured by the temperature measuring unit is higher than a temperature to be maintained, which is set in advance.

Description

Hardening equipment

The present disclosure relates to a quenching apparatus for quenching a workpiece such as a machine part.

Conventionally, as an apparatus for quenching a workpiece such as a mechanical component (for example, a gear, a shaft), a quenching apparatus including a heating chamber for heating the workpiece and a cooling tank for cooling the workpiece heated in the heating chamber has been proposed (See, for example, Patent Document 1).

An oil (quenched oil) is filled in the cooling tank of the quenching device of Patent Document 1 as a coolant for cooling the work. The workpiece is cooled by immersing the workpiece in the quenching oil in the cooling tank.

When the hardening device of Patent Document 1 is operated, the temperature of the hardened oil used for cooling the work rises each time. Therefore, it is necessary to cool the quenching oil to a predetermined temperature in preparation for the next cooling process. Therefore, as disclosed in Patent Document 2, a cooling device for cooling the temperature of the quenched oil has been proposed.

JP, 2014-237886, A Japanese Patent Application Laid-Open No. 6-158148

However, when using a cooling device for quenching oil as in Patent Document 2, after cooling a certain work, the quenching oil is cooled and heated until the next work comes, and maintained at a predetermined heat retention temperature There is a need to. On the other hand, there are two types of workpiece processing methods: continuous processing that processes workpieces continuously, and batch processing that processes multiple workpieces together, and the time interval until the next workpiece is transported to the cooling tank Various (eg, minutes to hours).

Under such circumstances, particularly when the time interval until the next work is transported is long, the heat retention operation for keeping the quenching oil warm becomes long. As described above, temperature control of a coolant such as quenching oil for cooling a work may be performed inefficiently, and it can be said that there is still room for improvement in efficiently performing temperature control of the coolant. .

This indication solves the above-mentioned subject, and it aims at providing a hardening device which can perform temperature control of a coolant more efficiently.

The hardening device according to one aspect of the present disclosure is a hardening device for hardening a workpiece, which includes a cooling tank containing a liquid coolant for cooling the heat-treated workpiece, and a cooling agent in the cooling tank. , A heating unit for heating the coolant in the cooling tank, a temperature measuring unit for measuring the temperature of the coolant in the cooling tank, and a control unit for controlling the operation of the cooling unit and the heating unit And, after the quenching time of the work by the coolant is completed, the control unit cools the coolant without operating the cooling unit and the heating unit, and before the next work is input. At a predetermined timing, when the temperature measured by the temperature measuring unit is higher than a predetermined temperature keeping temperature, the cooling unit is operated to control the cooling of the coolant.

According to the above configuration, after the quenching time of the work is completed, the cooling agent is allowed to cool without operating the cooling unit, and the operation of the cooling unit is started based on the measured temperature of the coolant thereafter. As a result, temperature control can be efficiently performed as compared with the case where the cooling unit is operated immediately after the work is cooled to perform forced cooling as in the prior art.

In the quenching apparatus, when the measured temperature is lower than the heat retention temperature before the predetermined timing, the control unit changes to the operation of the cooling unit until the next workpiece is input. In the meantime, the heating unit may be controlled to operate so that the measured temperature approaches the heat retention temperature. As a result, by maintaining the temperature of the coolant near the temperature keeping temperature, the temperature of the coolant can be made the temperature keeping temperature when the next work is introduced, and the work can be subjected to desired cooling processing.

In the quenching apparatus, the control unit operates the cooling unit at the predetermined timing, and then the heating unit is moved so that the measured temperature approaches the heat retention temperature until the next workpiece is inserted. You may control to drive. As a result, by maintaining the temperature of the coolant near the temperature keeping temperature, the temperature of the coolant can be made the temperature keeping temperature when the next work is introduced, and the work can be subjected to desired cooling processing.

In the hardening device, the control unit has a prediction program for predicting a temperature transition when the coolant is allowed to cool and / or a prediction program for predicting a temperature transition when the coolant is cooled by the cooling unit. The timing to start the operation of the cooling unit may be determined based on the prediction program so that the measured temperature becomes the heat retention temperature when or before the next work is input. Thereby, the temperature control of the coolant can be performed more efficiently.

In the quenching apparatus, the control unit may determine a timing at which the cooling unit is started so that the measured temperature becomes the heat retention temperature when the next workpiece is introduced. Thereby, control which does not operate a heating part becomes possible, and temperature control of a coolant can be performed more efficiently.

According to the present disclosure, temperature control of the coolant can be performed more efficiently.

The figure which shows schematic structure of the hardening apparatus of Embodiment 1. The figure which shows an example of the flow of the hardening process by the hardening apparatus of Embodiment 1 The figure which shows an example of the flow of the hardening process by the hardening apparatus of Embodiment 1 The figure which shows an example of the flow of the hardening process by the hardening apparatus of Embodiment 1 The figure which shows an example of the flow of the hardening process by the hardening apparatus of Embodiment 1 The figure which shows an example of the flow of the hardening process by the hardening apparatus of Embodiment 1 The figure which shows an example of the temperature transition of the coolant at the time of performing temperature control by the temperature control mechanism of the hardening apparatus of Embodiment 1. The figure which shows an example of the temperature transition of the coolant at the time of performing temperature control by the temperature control mechanism of the hardening apparatus of Embodiment 1. Diagram showing an example of the temperature transition of the coolant when the temperature control method of the conventional example is performed The figure which shows the example of the temperature transition of the coolant at the time of temperature control by the temperature control mechanism of the hardening apparatus of Embodiment 2.

Hereinafter, preferred embodiments of a hardening device and a hardening method according to the present disclosure will be described with reference to the attached drawings. The present disclosure is not limited to the specific configurations of the following embodiments, and configurations based on similar technical ideas are included in the present disclosure.

(Embodiment 1)
FIG. 1 is a schematic view showing a schematic configuration of a hardening device 2 in the first embodiment.

The hardening apparatus 2 shown in FIG. 1 is a heat treatment furnace as an apparatus for hardening a workpiece W (a mechanical component (for example, a gear, a shaft) or the like) as an object to be treated.

The quenching device 2 shown in FIG. 1 has a function of performing a cooling process in addition to the heating process of the workpiece W, and is configured as a multi-chamber heat treatment furnace that constitutes a plurality of spaces. As shown in FIG. 1, the hardening device 2 includes a heating chamber 4, a relay chamber 6, a cooling tank 8, a transport tray 10, a lift elevator 12, a first door 14, and a second door 16. , A third door 18, a control unit 20, and a temperature control mechanism 24.

When the hardening device 2 is operated, the work W is heated in the heating chamber 4, and the heat-treated work W is horizontally transported to the relay chamber 6, and then lowered to the cooling tank 8 below by the elevator 12 for cooling To process. In such a configuration, the cooling tank 8 contains a liquid coolant C (oil, water, chemical solution, etc.) for cooling (quenching) the work W.

The cooling tank 8 is provided with a temperature control mechanism 24 for controlling the temperature of the coolant C. The temperature control mechanism 24 illustrated in FIG. 1 includes a stirring unit 26, a motor 28, a temperature measurement unit 30, a heating unit 32, a cooling flow path 33, a pump 34, and a cooling unit 36. These functions will be described later.

The invention of the present disclosure is particularly characterized by the temperature control method of the coolant C by the temperature control mechanism 24, and a specific method will be described later.

Next, respective components of the hardening device 2 will be described.

The heating chamber 4 is a space for heating the work W. The work W is heated to a predetermined temperature in the heating chamber 4. In FIG. 1, a state in which the work W is disposed in the heating chamber 4 is illustrated.

A first door 14 and a second door 16 are provided as doors for carrying the work W in and out of the heating chamber 4. The first door 14 and the second door 16 are moved up and down by a drive mechanism (not shown). The heating chamber 4 can be opened and closed by the vertical movement of the first door 14 and the second door 16. The third door 18 also has the same configuration, so the description will be omitted.

The relay chamber 6 is a space provided on the side of the heating chamber 4. The relay chamber 6 is a space serving as a relay point when the workpiece W heated in the heating chamber 4 moves to the cooling tank 8. In the example of FIG. 1, the cooling tank 8 is provided below the relay chamber 6.

The cooling tank 8 is a tank for cooling the work W. The cooling tank 8 of the first embodiment has a function of performing an oil-cooling type cooling process, and an oil at a predetermined temperature (for example, 120 ° C.) is accommodated as the liquid coolant C.

The conveyance tray 10 is a member for placing and conveying the work W in the hardening device 2. Similarly, the elevating elevator 12 is a member for raising and lowering the transport tray 10 on which the work W is placed between the relay chamber 6 and the cooling tank 8.

The control unit 20 is a member that controls the operation of the hardening device 2. The control unit 20 is electrically connected to each component of the hardening device 2 described above, and can control the operation of each component. The control unit 20 is configured of, for example, a microcomputer.

Next, respective components of the temperature control mechanism 24 will be described.

The stirring unit 26 is a member that stirs the coolant C in the cooling tank 8. The stirring by the stirring unit 26 makes the temperature of the coolant C in the cooling tank 8 uniform. The stirring unit 26 shown in FIG. 1 has a propeller 26 a at its tip and is rotationally driven by a motor 28.

The temperature measurement unit 30 is a member that measures the temperature of the coolant C in the cooling tank 8. Although the temperature measurement unit 30 in the first embodiment is a thermocouple (temperature sensor), the present invention is not limited to this, as long as the temperature measurement unit 30 can measure the temperature of the coolant C in the cooling tank 8.

The heating unit 32 is a member that heats the coolant C in the cooling tank 8. Although the heating part 32 in Embodiment 1 is a heater, it is not restricted to this, as long as it can heat the coolant C in the cooling tank 8.

The cooling flow path 33 is a flow path for sending the coolant C in the cooling tank 8 to the cooling unit 36 described later. The cooling channel 33 shown in FIG. 1 is provided as a channel that bypasses the cooling tank 8. The cooling channel 33 includes an upstream channel 33 a connected from the cooling tank 8 to the cooling unit 36 and a downstream channel 33 b connected from the cooling unit 36 to the cooling tank 8.

The pump 34 is a pump for drawing the coolant C in the cooling tank 8 into the upstream side flow path 33 a and sending it to the cooling unit 36.

The cooling unit 36 is a member that cools the coolant C. Although the cooling unit 36 in the first embodiment is a heat exchanger, the invention is not limited to this, as long as the cooling unit C in the cooling tank 8 can be cooled.

The operation of each component of the temperature control mechanism 24 described above is controlled by the control unit 20.

An example of the flow of the hardening process when the hardening device 2 configured as described above is operated will be described with reference to FIGS. 2A to 2E.

First, the work W is carried into the heating chamber 4 as shown in FIG. 2A. Specifically, the first door 14 is raised and opened. The heating chamber 4 is preheated by a heater (not shown) provided therein. Next, the workpiece W placed on the transport tray 10 outside the hardening device 2 is carried into the inside of the hardening device 2 (A1 in the figure). In order to carry in the conveyance tray 10, any conveyance mechanism may be used, such as rotating a roller (not shown) on which the conveyance tray 10 is placed from the outside. Thereafter, the first door 14 is lowered and closed, and the work W in the heating chamber 4 is heated to a predetermined temperature (for example, 850 ° C.).

Next, the transport tray 10 is moved to the relay chamber 6. Specifically, the second door 16 is raised and opened, and the work W after the heat treatment is horizontally moved toward the relay chamber 6 (A2 in the drawing). For the movement of the transport tray 10, the above-mentioned transport mechanism (not shown) is used.

As shown in FIG. 2B, the transfer tray 10 and the work W are placed on the elevator 12 in the relay chamber 6. Thereafter, the second door 16 is lowered and closed.

Next, as shown in FIG. 2C, the transport tray 10 is lowered to the cooling tank 8 using the elevator 12. By lowering the lifting elevator 12, the transport tray 10 is disposed in the cooling tank 8, and the work W is immersed in the liquid coolant C (A3 in the figure). Thereby, the workpiece W is cooled to a predetermined temperature (for example, 120 ° C.) and subjected to quenching treatment.

The work W for which the cooling process in the cooling tank 8 is completed is then returned to the relay chamber 6 as shown in FIG. 2D (A4 in the figure). Thereafter, as shown in FIG. 2E, the third door 18 is opened, and the transport tray 10 on which the workpiece W is placed is unloaded out of the hardening device 2 (A5 in the figure).

By performing the process of FIGS. 2A to 2E described above, the hardening process is performed on the workpiece W. The same quenching process is performed on a plurality of works W sequentially transferred to the quenching device 2.

When such a hardening process is continued, the temperature of the coolant C in the cooling tank 8 used for cooling the work W rises (e.g., rises to about 140 ° C.) with each hardening process. On the other hand, when the next work W is introduced into the cooling tank 8, it is necessary to lower the temperature of the coolant C to a predetermined temperature (for example, 120 ° C.). That is, it is necessary to cool the coolant C every time the quenching process is completed.

In the hardening device 2 of the first embodiment, the temperature control of the coolant C is performed using the temperature control mechanism 24 described above. A specific temperature control method will be described using FIGS. 3 and 4.

3 and 4 are graphs showing the transition of the temperature of the coolant C when the temperature of the coolant C is controlled by the temperature control mechanism 24 of the first embodiment. In FIG. 3 and FIG. 4, the horizontal axis represents time, and the vertical axis represents temperature (temperature measured by the temperature measurement unit 30).

As shown in FIGS. 3 and 4, the temperature control mechanism 24 according to the first embodiment releases the coolant C without operating the heating unit 32 and the cooling unit 36 after the quenching time X1 for one work W is completed. Perform cold operation (heat release) (cooling time X2, X5). In parallel with the cooling operation of the coolant C, the temperature measuring unit 30 continuously measures the temperature of the coolant C (for example, every one minute), and during the time until the predetermined timing Xt determined in advance, the measurement temperature Determines whether the temperature is lower than the temperature T1.

The hardening time X1 is the time from when the workpiece W is attached to the coolant C to when it is pulled up. The predetermined timing Xt is a timing stored (set) in advance in the control unit 20 as a time point (for example, 10 minutes before) the time point Xn at which the next work W is put into the cooling tank 8 (for example, 10 minutes) The time point Xn at which the next work W is introduced into the cooling tank 8 is also stored in the control unit 20). The heat retention temperature T1 is a temperature stored in advance in the control unit 20 as a desired temperature of the coolant C at the start of the cooling process of the work W.

The example shown in FIG. 3 shows the case where the measurement temperature does not fall below the heat retention temperature T1 until the predetermined timing Xt. In such a case, the cooling operation of the coolant C is continued without operating the heating unit 32 and the cooling unit 36 from the end of the hardening time X1 to the predetermined timing Xt (cooling time X2).

Thereafter, the cooling unit 36 is operated at a predetermined timing Xt. The coolant C is cooled by the operation of the cooling unit 36 and reaches the heat retention temperature T1 (cooling time X3).

Furthermore, after the measured temperature of the coolant C reaches the heat retention temperature T1, the heat retention operation is performed in which the heating unit 32 is intermittently operated such that the measured temperature approaches the heat retention temperature T1 (heat retention time X4).

On the other hand, FIG. 4 shows the case where the measured temperature of the coolant C falls below the heat retention temperature T1 by the predetermined timing Xt. As shown in FIG. 4, after the cooling operation is performed from the end of the hardening time X1 to a predetermined timing Xt (cooling time X5), the operation of the cooling unit 36 (cooling time X3) shown in FIG. The heat retention operation similar to that shown in FIG. 3 is performed until the time point Xn when the next work W is introduced into the cooling tank 8 (heat retention time X6).

According to the control shown in FIGS. 3 and 4, the temperature of the coolant C is maintained at the heat retention temperature T1 in any case at the time point Xn when the next work W is introduced into the cooling tank 8 . Thereby, desired cooling processing can be performed on the next workpiece W.

An example of the temperature transition of the coolant C according to the temperature control method of the conventional example is shown in FIG. 5 with respect to the temperature control method of the first embodiment described above.

In the conventional example shown in FIG. 5, the cooling unit 36 is operated immediately after the end of the hardening time X1 of the workpiece W (cooling time X7). Thereafter, the heat retention operation at the heat retention temperature T1 is performed until the time point Xn at which the next work W is input (heat retention time X8).

According to such a temperature control method, both the cooling time X7 and the heat retention time X8 become long, and in particular, the heat retention time X8 becomes significantly longer as the time point Xn at which the next work W is introduced is later. As a result, the heat retention operation for ON / OFF controlling the heating unit 32 becomes long, and the temperature control method becomes inefficient.

On the other hand, according to the temperature control method of the first embodiment described above, after completion of the quenching time X1 of the work W, the cooling unit 36 and the heating unit 32 are not operated, and the cooling operation thereafter is performed. The operation of the cooling unit 36 is started based on the measured temperature of C. According to such a method, the period for operating the cooling unit 36 and the period for operating the heating unit 32 become shorter as compared with the conventional example shown in FIG. can do. Thereby, temperature control of the coolant C can be performed more efficiently.

Second Embodiment
The temperature control method of the coolant C according to the second embodiment of the present disclosure will be described. In the second embodiment, points different from the first embodiment will be mainly described, and the description overlapping with the first embodiment will be omitted.

In the second embodiment, in addition to the temperature control method of the first embodiment, the control unit 20 has a prediction program for predicting the temperature transition of the coolant C, and the temperature control is performed based on the prediction program. Different from Form 1.

In the prediction program in the second embodiment, the temperature transition of the coolant C when the coolant C is allowed to cool without operating the cooling unit 36 and the temperature of the coolant C when the coolant C is cooled by the cooling unit 36 It predicts the transition. The temperature transition when the coolant C is allowed to cool can be obtained from, for example, an arithmetic expression that predicts the temperature transition based on factors such as the type of the coolant C and the amount of heat released from the cooling tank 8. In addition, the temperature transition when the coolant C is cooled by the cooling unit 36 is, for example, a temperature transition based on factors such as the type of the coolant C, the amount of heat released from the cooling tank 8, and the size of the output of the cooling unit 36. It is obtained from an arithmetic expression to be predicted.

An example of the temperature transition of the coolant C by the temperature control method of Embodiment 2 is shown in FIG.

As shown in FIG. 6, according to the temperature control method of the second embodiment, based on the above-described prediction program, cooling by cooling unit 36 after cooling time X9 for cooling coolant C and cooling time X9. A cooling time X10 for cooling the agent C is determined. Specifically, the operation start timing of the cooling unit 36, which is the timing at which the cooling time X9 is switched to the cooling time X10, is determined based on the prediction program.

In the second embodiment, in particular, the operation start timing of the cooling unit 36 is determined such that the measured temperature of the coolant C is just the heat retention temperature T1 at the time point Xn when the next work W is introduced. As a result, the heat retention operation using the heating unit 32 is not necessary, and a desired cooling process can be performed on the next workpiece W only by operating the cooling unit 36. By such a method, temperature control of the coolant C can be performed more efficiently.

In addition, when using a prediction program, you may provide an air temperature measurement part, a timer, and a cooling rate memory | storage part as a new structure of the hardening apparatus 2. FIG. In this way, it is also possible to calculate the amount of heat required for cooling from the heating temperature, the specific heat of the work W, and the weight.

Although the invention of the present disclosure has been described above by citing the first and second embodiments described above, the invention of the present disclosure is not limited to the first and second embodiments. For example, in the first embodiment, the heating unit 32 and the cooling unit 36 are illustrated in FIG. 1 as being in different places, but the present invention is not limited to such a case. The cooling unit and the heating unit may be in the same place, or an apparatus in which the cooling and heating functions are combined may be used.

Although the case where the coolant C contained in the cooling tank 8 is a quenching oil has been described in the first embodiment, the present invention is not limited to such a case, and a liquid coolant other than oil may be used.

In the first embodiment, although the case where the workpiece W is transported in the order shown in FIGS. 2A to 2E has been described, the present invention is not limited to such a case. After the heat treatment is performed in the heating chamber 4, it may be transported in any order as long as the cooling treatment is performed in the cooling tank 8. In addition, the work W which has been cooled and treated as heating and cooling in one processing chamber or as a wall without providing the third door 18 opens and closes the second door 16 and the first door 14, The configuration of the transport path and the processing chamber may be changed according to the processing type of the work W, such as a batch type of returning to the position.

Moreover, although the case where ON / OFF of the heating part 32 was repeated as heat retention operation which makes the temperature of the workpiece | work W approach heat retention temperature T1 was demonstrated in the said Embodiment 1, it does not restrict to such a method. Any operation method using the heating unit 32 and / or the cooling unit 36 may be used as long as the temperature of the work W can be brought close to the heat retention temperature T1.

In the second embodiment, in the prediction program, both the prediction of the temperature transition when the coolant C is allowed to cool and the prediction of the temperature transition when the coolant C is cooled by the cooling unit 36 are described. However, this is not the case. Only one of the predictions may be performed. In other words, the control unit 20 has a prediction program that predicts the temperature transition when the coolant C is allowed to cool and / or a prediction program that predicts the temperature transition when the coolant C is cooled by the cooling unit 36. May be

In the second embodiment, the cooling unit 36 is started to operate so that the measured temperature of the coolant C becomes just the heat retention temperature T1 at the time point Xn when the next work W is introduced, but in such a case Not limited to. Before the next work W is input, the operation start timing of the cooling unit 36 may be determined based on a prediction program so that the measured temperature of the coolant C becomes the heat retention temperature T1.

In addition, the effect which each has can be exhibited by combining suitably the arbitrary embodiment in said various embodiment.

While the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art. Such variations and modifications are to be understood as included within the scope of the present disclosure as set forth in the appended claims unless they depart therefrom. In addition, changes in the combination or order of elements in each embodiment can be realized without departing from the scope and spirit of the present disclosure.

The present disclosure is applicable to any hardening device that hardens a workpiece.

DESCRIPTION OF SYMBOLS 2 Hardening apparatus 4 heating chamber 6 relay chamber 8 cooling tank 10 conveyance tray 12 raising / lowering elevator 14 1st door 16 2nd door 18 3rd door 20 control part 24 temperature control mechanism 26 stirring part 26a propeller 28 motor 30 temperature measurement Part 32 Heating part 33 Cooling flow path 33a Upstream side flow path 33b Downstream side flow path 34 Pump 36 Cooling part C Coolant W Workpiece T1 Heat retention temperature X1 Quenching time X2, X5, X9 Cooling time X3, X7, X10 Cooling time X4 , X6, X8 Incubation time Xt Prescribed timing Xn When the next work is put into the cooling tank

Claims

A hardening device for hardening the workpiece,
A cooling tank containing a liquid coolant for cooling the heat-treated workpiece;
A cooling unit configured to cool the coolant in the cooling tank;
A heating unit that heats the coolant in the cooling tank;
A temperature measurement unit that measures the temperature of the coolant in the cooling tank;
A control unit that controls the operation of the cooling unit and the heating unit;
The control unit allows the coolant to cool without operating the cooling unit and the heating unit after the quenching time of the work by the coolant is completed, and at a predetermined timing before the next work is input, The quenching apparatus controls to operate the cooling unit to cool the coolant when the temperature measured by the temperature measuring unit is higher than a predetermined temperature keeping temperature.
When the measured temperature is lower than the heat retention temperature before the predetermined timing, the control unit changes the operation of the cooling unit until the next work is input, before the predetermined temperature. The hardening apparatus according to claim 1, wherein the heating unit is controlled to operate such that the temperature approaches the heat retention temperature.
The control unit controls the heating unit to operate so that the measured temperature approaches the heat retention temperature until the next work is input after operating the cooling unit at the predetermined timing. The hardening apparatus according to claim 1 or 2, wherein
The control unit has a prediction program for predicting a temperature transition when the coolant is allowed to cool and / or a prediction program for predicting a temperature transition when the coolant is cooled by the cooling unit, and the next work is input The timing according to any one of claims 1 to 3, wherein operation start time of the cooling unit is determined based on the prediction program such that the measured temperature becomes the heat retention temperature at or before the start of the operation. Hardening equipment.
5. The hardening device according to claim 4, wherein the control unit determines the timing to start the operation of the cooling unit such that the measured temperature becomes the heat retention temperature when the next workpiece is introduced.