JP2022190490A - Heat treatment apparatus and method of controlling temperature of coolant in heat treatment apparatus - Google Patents

Abstract

To provide a heat treatment apparatus for cooling a heated object, such as quenching, with excellent energy saving performance and reduced operation costs.SOLUTION: A heat treatment apparatus 1 has: a cooling tank 6 in which a coolant C for cooling a heated object 100 is stored; a thermometer 7 for measuring a temperature of the coolant C; a temperature adjustment mechanism 25 including a cooling section 27 for cooling the coolant C and a heating section 28 for heating the coolant C; and a control section 8 for controlling the temperature adjustment mechanism 25. The control unit 8 is configured to execute an induction cooling mode. In the induction cooling mode, the control section 8 sets a target temperature Tt of the coolant C to change over time, and drives the temperature adjustment mechanism 25 so that a measured temperature Tm of the coolant C becomes the target temperature Tt.SELECTED DRAWING: Figure 1

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus and a cooling liquid temperature control method in the heat treatment apparatus.

As a device for quenching a metal work, there is known an oil quenching device including a heating chamber for heating the work and an oil quenching chamber for cooling the work heated in the heating chamber with quenching oil (for example, , see Patent Document 1).

Quenching oil for cooling the work is stored in the oil quenching chamber. The work is cooled by immersing the work in the quenching oil in the oil quenching chamber.

Japanese Unexamined Patent Application Publication No. 2002-309314

When the workpiece is cooled by the oil quenching device, the quenching oil temperature rises. While the quenching oil is repeatedly used for multiple quenching treatments, the temperature of the quenching oil immediately before quenching must be the temperature (predetermined temperature) set to perform the desired heat treatment. There is Therefore, the quenching oil after quenching of the work must be cooled to the predetermined temperature in preparation for the next cooling process. Therefore, a heat exchanger is used to cool the quenching oil.

Conventionally, the heat exchanger starts cooling the quenching oil immediately after the quenching of the workpiece is finished, rapidly cooling the quenching oil, and stops the operation after the temperature of the quenching oil drops to the predetermined temperature. was However, after the quenching oil is cooled to the predetermined temperature, it sometimes takes a long time before the next quenching operation. In this case, in order to maintain the temperature of the quenching oil at the predetermined temperature, a heating unit for keeping the quenching oil warm is operated at regular intervals. Since the heating unit consumes a large amount of energy, reckless operation of the heating unit is not preferable from the viewpoint of energy saving, and causes high energy costs.

The present invention has been made in view of the above background, and provides a heat treatment apparatus that performs a process of cooling a heated object, such as quenching, to be excellent in energy saving and to reduce operating costs. for the purpose.

(1) A heat treatment apparatus according to one aspect of the present invention, which has been made based on the above findings, comprises a cooling tank in which a cooling liquid for cooling a heated object to be processed is stored, and a temperature sensor for measuring the temperature of the cooling liquid. a temperature adjustment mechanism including a sensor, a cooling unit for cooling the cooling liquid, and a heating unit for heating the cooling liquid; and a control unit for controlling the temperature adjustment mechanism, the control unit is configured to be able to execute an induction cooling mode, and the control unit sets the target temperature of the cooling liquid so as to change with the passage of time in the induction cooling mode, and the measured temperature of the cooling liquid is the target temperature.

According to this configuration, the cooling liquid whose temperature has been raised by putting the heated object into the cooling bath is cooled until the next heated object is put into the cooling bath. be able to. During this cooling, in the induction cooling mode, the control unit sets the target temperature of the coolant to change over time, and drives the temperature adjustment mechanism so that the actually measured temperature of the coolant reaches the target temperature. . With this configuration, it is possible to prevent the coolant from being rapidly cooled by the cooling unit. As a result, the controller can gradually lower the temperature of the coolant. As a result, once the temperature of the cooling liquid has reached the temperature required when the object to be processed starts cooling, the heating operation of the cooling liquid for maintaining this temperature can be reduced to zero or the necessary minimum. That is, as a result of being able to reduce the energy for heating the cooling liquid, the heat treatment apparatus that performs the process of cooling the heated workpiece such as quenching can be configured to be excellent in energy saving, and the energy cost etc. can be reduced. operating costs can be reduced.

(2) Based on the period from the start to the end of the induction cooling mode and the temperature difference between the measured temperature at the start of the induction cooling mode and the target temperature at the end of the induction cooling mode The target temperature may be set.

According to this configuration, the target temperature for each unit time required when the induction cooling mode is executed is the period from the start to the end of the induction cooling mode, the measured temperature at the start of the induction cooling mode, and the target temperature at the end of the induction cooling mode. can be set based on the temperature difference between As a result, the target temperature can be set for each unit of time by a simple calculation, and can also be set with a high degree of freedom.

(3) The control unit linearly lowers the target temperature of the coolant over time in the induction cooling mode.

According to this configuration, it is possible to set the target temperature for each unit time required when the induction cooling mode is executed by simple calculation.

(4) The target temperature has a predetermined temperature range, and within the temperature range, a target center temperature, a target upper limit temperature higher than the target center temperature, and a target lower limit temperature lower than the target center temperature. and are set, and the control unit may drive the temperature adjustment mechanism so that the measured temperature falls between the target upper limit temperature and the target lower limit temperature.

According to this configuration, since the temperature range is provided for the target temperature, it is not necessary to strictly control the coolant temperature, and coolant temperature control can be realized with a simpler configuration.

(5) The difference between the target upper limit temperature and the target lower limit temperature in the latter half of the induction cooling mode is smaller than the difference between the target upper limit temperature and the target lower limit temperature in the initial period of the induction cooling mode. Sometimes.

According to this configuration, after cooling the object to be processed, the temperature of the cooling liquid into which the heated object to be processed is introduced next can be adjusted to the required temperature more accurately at the time the object to be processed is introduced. can get closer.

(6) The control unit may drive the cooling unit to cool the coolant when the measured temperature is higher than the target center temperature.

According to this configuration, the trigger for starting driving of the cooling unit can be configured simply.

(7) When the actually measured temperature is equal to the target upper limit temperature, the control unit starts driving the cooling unit to cool the coolant, and when the actually measured temperature has decreased to the target center temperature The driving of the cooling unit may be stopped.

According to this configuration, it is possible to suppress excessive cooling of the coolant by the cooling unit. As a result, an operation that requires a lot of energy, such as reheating the cooling liquid in the heating unit due to the cooling liquid temperature being too low, can be reduced.

(8) The control unit may drive the heating unit to heat the coolant when the measured temperature is lower than the target center temperature.

According to this configuration, the temperature of the coolant can be maintained so that the temperature of the coolant does not become too low from the target center temperature.

(9) When the measured temperature is the target lower limit temperature, the control unit starts driving the heating unit to heat the coolant, and when the measured temperature rises to the target center temperature The driving of the heating unit may be stopped.

According to this configuration, it is possible to suppress excessive heating of the coolant by the heating unit. As a result, the temperature of the coolant can be maintained with minimal heating.

(10) The heat treatment apparatus is a carburizing apparatus for carburizing the object to be treated, in which the object to be treated is heated to a predetermined carburizing temperature, cooled to a predetermined soaking temperature, and then is maintained at the soaking temperature for a predetermined time, and then the object to be treated is put into the cooling bath, and the control unit controls the temperature of the object to be treated so that the temperature of the object to be treated is changed from the carburizing temperature to the soaking temperature Predicting the temperature drop time until the temperature drops to the temperature, ending the induction cooling mode in the middle of the temperature drop time, and then executing the constant temperature mode that controls the temperature adjustment mechanism so as to keep the target temperature constant. It may be configured as

According to this configuration, the controller can run the induction cooling mode for a longer period of time. Accordingly, the time for executing the constant temperature mode can be shortened. In the constant temperature mode, it is necessary to keep the target temperature constant, so it is necessary to frequently heat the cooling liquid by the heating unit. However, by shortening the execution time of this constant temperature mode, the energy consumption associated with the heating operation can be reduced.

(11) In order to solve the above problems, a cooling liquid temperature control method in a heat treatment apparatus according to one aspect of the present invention includes a cooling tank in which a cooling liquid for cooling a heated object to be processed is stored; and a temperature adjustment mechanism including a heating unit for heating the coolant, wherein the target temperature of the coolant is set to change over time Then, the temperature adjustment mechanism is driven so that the actually measured temperature of the coolant becomes the target temperature.

According to this configuration, in the heat treatment apparatus that performs the process of cooling the heated object to be processed, the configuration can be excellent in energy saving, and operating costs such as electricity charges can be reduced.

Advantageous Effects of Invention According to the present invention, a heat treatment apparatus that performs a process of cooling a heated object to be processed can be configured to be excellent in energy saving and reduce operating costs.

FIG. 1 is a schematic cross-sectional view of a heat treatment apparatus according to one embodiment of the present invention, showing a state of the heat treatment apparatus viewed from the side. FIG. 2 is a block diagram for explaining the main part of the electrical configuration of the heat treatment apparatus. FIG. 3 is a diagram for explaining the relationship between the processing pattern of the object to be processed and the coolant temperature. FIG. 4 is a diagram showing an example of the history of the actually measured temperature of the coolant in the "forced cooling control example". FIG. 5 is a diagram showing an example of the history of the actually measured temperature of the coolant in the "heating control example". FIG. 6 is a diagram for explaining the relationship between the processing pattern of the workpiece and the coolant temperature in a modification in which the heat treatment apparatus performs a process different from that of the carburizing apparatus.

EMBODIMENT OF THE INVENTION Hereinafter, it demonstrates, referring drawings for the form for implementing this invention.

FIG. 1 is a schematic cross-sectional view of a heat treatment apparatus 1 according to an embodiment of the present invention, showing a state of the heat treatment apparatus 1 viewed from the side. FIG. 2 is a block diagram for explaining the main part of the electrical configuration of the heat treatment apparatus 1. As shown in FIG.

1 and 2, in the present embodiment, heat treatment apparatus 1 is a carburizing furnace. The heat treatment apparatus 1 is configured to introduce a heat treatment gas into the heating chamber 3 so as to carburize the workpiece 100 placed in the heating chamber 3 . The material of the object to be treated 100 may be any material that can be carburized on the surface. As an example of the object 100 to be processed, metal parts such as steel parts can be exemplified. Carburizing treatment is a heat treatment method in which carbon penetrates and diffuses into the surface of steel, and is a treatment for obtaining high surface hardness by quenching the steel in the cooling tank 6 of the cooling chamber 4 after carburizing heating.

The heat treatment apparatus 1 includes a heat treatment mechanism 2 including a heating chamber 3 and a cooling chamber 4, a heating chamber thermometer 5 for measuring the ambient temperature in the heating chamber 3, and a cooling liquid C in a cooling tank 6 of the cooling chamber 4. , a control section 8 and an operation/display section 9 .

In this embodiment, the heating chamber 3 and the cooling chamber 4 of the heat treatment mechanism 2 form a heat treatment space for carburizing the object 100 to be treated. The heating chamber 3 and cooling chamber 4 may be used not only for carburizing but also for other heat treatments such as nitriding, carbonitriding, quenching, gas nitrocarburizing, and aluminum hydrochlorination. The heat treatment mechanism 2 may be a batch furnace in which the objects 100 to be treated in the heat treatment mechanism 2 are replaced for each heat treatment cycle (carburizing treatment), or a plurality of objects to be treated while conveying the objects 100 in one direction. It may be a continuous furnace in which the workpieces 100 are successively and continuously heat-treated. In this embodiment, an example in which the heat treatment mechanism 2 is a batch furnace will be described. The path of the workpiece 100 in the heat treatment mechanism 2 of this embodiment is indicated by a dashed line.

In this embodiment, the heat treatment mechanism 2 includes a heating chamber 3, a cooling chamber 4, a first door 11 for opening and closing the entrance 4a of the cooling chamber 4, a first door opening/closing mechanism 12, the heating chamber 3 and the cooling chamber 4. a second door 14 for opening and closing the passage 13 between the heating chamber 3 and the cooling chamber 4; a second door opening/closing mechanism 15; doing.

The heating chamber 3 is provided for heating, carburizing, and soaking the object 100 to be processed. The heating chamber 3 is formed in a hollow shape and can accommodate the object 100 to be processed. In this embodiment, the workpiece 100 is loaded into the heating chamber 3 through the cooling chamber 4 .

The heating chamber 3 is provided with a heating chamber thermometer 5 , a gas supply pipe 18 for introducing heat treatment gas into the heating chamber 3 , a fan 21 , and a heating chamber heater 22 .

A fan 21 is provided to stir the gas (heat treatment gas) in the heating chamber 3 . The fan 21 has an electric motor and stirring blades, and is driven to rotate during heat treatment of the object 100 to be processed. This makes the gas distribution in the heating chamber 3 more uniform.

The heating chamber heater 22 is provided to heat the gas in the heating chamber 3 and the object 100 to be processed. Examples of the heating chamber heater 22 include a gas burner and a resistance heater. The heating chamber heater 22 is configured to be able to change the temperature of the heating chamber 3 .

A heating chamber thermometer 5 (temperature sensor) is provided to measure the ambient temperature in the heating chamber 3 . The heating chamber thermometer 5 includes, for example, a thermocouple, and the temperature measuring portion is arranged inside the heating chamber 3 . The heating chamber thermometer 5 outputs a detection signal obtained by detecting the ambient temperature in the heating chamber 3 to the controller 8 .

The cooling chamber 4 is provided for quenching by cooling (quenching) the workpiece 100 heated in the heating chamber 3 . The cooling chamber 4 is formed in a hollow shape and can accommodate the object 100 to be processed. An entrance 4a is formed in the cooling chamber 4, and the workpiece 100 is taken in and out of the cooling chamber 4 through the entrance 4a.

The first door 11 opens the entrance 4a when the material 100 to be processed is loaded through the entrance 4a, and is closed except when the material 100 to be processed is passed through the entrance 4a. The first door opening/closing mechanism 12 includes a power source such as a pneumatic cylinder, and is configured to open/close the first door 11 by receiving a predetermined command signal.

The space in the cooling chamber 4 is continuous with the space in the heating chamber 3 via the passage 13 . The cooling chamber 4 includes a cooling bath 6 in which a cooling liquid C for cooling the heated workpiece 100 is stored. The cooling tank 6 is arranged, for example, in the lower part of the cooling chamber 4 , and the workpiece 100 is quenched by being immersed in the cooling liquid C in the cooling tank 6 . The cooling liquid C is quenching oil in this embodiment, but may be another cooling medium such as cooling water.

The cooling chamber 4 is provided with a liquid thermometer 7 , a temperature adjustment mechanism 25 for adjusting the temperature of the cooling liquid C, and a stirrer 26 .

The temperature adjustment mechanism 25 includes a cooling portion 27 for cooling the coolant C and a heating portion 28 for heating the coolant C. As shown in FIG.

The cooling unit 27 includes, for example, a heat exchanger 27a provided in a pipe 27c installed so that the cooling liquid C in the cooling tank 6 circulates and in contact with the cooling liquid C, and a pump 27b for pumping coolant C such that C circulates. Upon receiving a predetermined command signal (operation start signal) from the control unit 8, the cooling unit 27 starts the operation of the pump 27b to pass the cooling liquid C through the heat exchanger 27a, thereby cooling the cooling liquid C. Continuously, when a predetermined command signal (operation stop signal) is given from the control unit 8, the operation of the pump 27b is stopped and the cooling operation of the coolant C is stopped. In this embodiment, driving the cooling unit 27 means driving the pump 27b. It should be noted that the cooling unit 27 may be configured so as to be capable of lowering the temperature of the cooling liquid C and perform the cooling operation by receiving the command signal from the control unit 8. is not limited.

The heating unit 28 is arranged, for example, so as to come into contact with the coolant C in the cooling bath 6 . The heating unit 28 continues the heating operation of the cooling liquid C by receiving a predetermined command signal (operation start signal) from the control unit 8, and receives a predetermined command signal (operation stop signal) from the control unit 8. , the heating operation of the coolant C is stopped. It should be noted that the heating unit 28 may be configured so as to be able to raise the temperature of the cooling liquid C and perform the heating operation by being given the command signal from the control unit 8. Specific configuration is not limited. Another example of the heating unit 28 is a heat pump type heater.

A stirrer 26 is provided to stir the coolant C. As shown in FIG. The stirrer 26 has a stirring blade arranged in the cooling liquid C and an electric motor for rotationally driving the stirring blade. The stirrer 26, for example, rotates constantly to stir the cooling liquid C while the object 100 to be processed is carried into the heat treatment mechanism 2, thereby making the temperature of the cooling liquid C in the cooling tank 6 as uniform as possible. may operate so that

Liquid thermometer 7 is an example of the "temperature sensor" of the present invention. A liquid thermometer 7 is provided to measure the temperature of the coolant C. As shown in FIG. Liquid thermometer 7 includes, for example, a thermocouple, and a temperature measuring portion is arranged in cooling bath 6 . Liquid thermometer 7 outputs a detection signal obtained by detecting the temperature of cooling liquid C to control unit 8 .

The second door 14 opens the passage 13 when the object 100 to be processed is transferred between the heating chamber 3 and the cooling chamber 4, and is closed while the object 100 is being heated in the heating chamber 3. . The second door opening/closing mechanism 15 includes a power source such as a pneumatic cylinder, and is configured to open/close the second door 14 by receiving a predetermined command signal. The timing at which the second door 14 is opened and closed is appropriately set.

The transport mechanism 16 has a table on which the workpiece 100 is placed and a moving mechanism for moving the table. The moving mechanism has, for example, an electric motor and a motion conversion mechanism that converts the output of the electric motor into a table moving force. The transport mechanism 16 moves the workpiece 100 to a position within the heating chamber 3, a position above the cooling tank 6 in the cooling chamber 4, a position where the entire workpiece 100 is immersed in the cooling liquid C, configured to move between

The control unit 8 is provided to control various devices of the heat treatment apparatus 1 including the temperature adjustment mechanism 25 . The controller 8 is formed using a PLC (Programmable Logic Controller) or the like. The control unit 8 may be formed using a computer including a CPU (Central Processing Unit), a ROM (Read Only Memory) and a RAM (Random Access Memory), or may include an FPGA (Field Programmable Gate Array). It may be a configuration, or may be formed using a sequence circuit or the like.

In the case where the control unit 8 has an arithmetic device, a program for the control unit 8 to perform the processing shown in this embodiment is stored in the control unit 8, or the program is given from the outside. For example, the operation of the control unit 8 in this embodiment can be realized by developing this program in the memory of the arithmetic device and executing it.

The control unit 8 includes a heating chamber thermometer 5, a fan 21, a heating chamber heater 22, a liquid thermometer 7, a first door opening/closing mechanism 12, a second door opening/closing mechanism 15, a conveying mechanism 16, and a stirrer. 26 , the cooling section 27 , the heating section 28 and the operation/display section 9 are electrically connected.

The control unit 8 receives the detection result of the heating chamber temperature by the heating chamber thermometer 5 . The controller 8 controls the rotation of the fan 21 by outputting a command signal to the fan 21 . The control unit 8 controls the heating operation in the heating chamber 3 by the heating chamber heater 22 and the heating chamber temperature by outputting a command signal to the heating chamber heater 22 .

The control unit 8 receives the detection result of the coolant temperature by the liquid thermometer 7 . The controller 8 controls the opening/closing operation of the first door 11 by outputting command signals to the first door opening/closing mechanism 12 . The control unit 8 outputs a command signal to the second door opening/closing mechanism 15 to control the opening/closing operation of the second door 14 . The control unit 8 outputs a command signal to the transport mechanism 16 to control the transport operation of the workpiece 100 by the transport mechanism 16 . The control unit 8 controls the stirring operation of the cooling liquid C by the stirrer 26 by outputting a command signal to the stirrer 26 . For example, the control unit 8 drives the stirrer 26 while the cooling liquid C is being heated by the heating unit 28 and while the cooling liquid C is being cooled by the cooling unit 27 . The control unit 8 controls the cooling operation of the cooling liquid C by the cooling unit 27 by outputting a command signal to the cooling unit 27 . The control unit 8 controls the heating operation of the cooling liquid C by the heating unit 28 by outputting a command signal to the heating unit 28 .

The operation/display unit 9 is, for example, a touch panel, and is configured to display various operation keys and information. The operation/display section 9 is configured to communicate with the control section 8 . A command signal generated by an operator operating the operation/display unit 9 is output from the operation/display unit 9 to the control unit 8 . The control unit 8 also outputs data specifying predetermined display contents to the operation/display unit 9 .

FIG. 3 is a diagram for explaining the relationship between the processing pattern of the workpiece 100 and the temperature of the coolant C. FIG. The upper diagram of FIG. 3 is a diagram for explaining the processing pattern of the workpiece 100. The horizontal axis indicates time, and the vertical axis indicates the measured value of the heating chamber temperature (ambient temperature in the heating chamber). . In this embodiment, the heating chamber temperature is substantially the same as the design temperature of the heating chamber 3 . The lower diagram of FIG. 3 is a diagram for explaining the temperature of the coolant C, where the horizontal axis represents time and the vertical axis represents the temperature of the coolant C. As shown in FIG.

The treatment pattern of the workpiece 100 will be described. This treatment pattern is carburizing treatment, and preheating is performed by heating the heating chamber 3 to a predetermined preheating temperature (for example, about 900° C. to 950° C.) (timings A3 to A4 ). Next, carburizing is performed while introducing a heat treatment gas at a carburizing temperature equal to the preheating temperature (timings A4 to A5). Furthermore, diffusion is performed at a diffusion temperature equal to the preheating temperature and the carburizing temperature (timings A5 to A6). Next, the temperature of the heating chamber is lowered by ΔF° C. (for example, about 50° C. to 100° C.) to the soaking temperature (timings A6 to A7), and soaked for a certain period of time (timings A7 to A1). Next, the workpiece 100 is transported to the cooling chamber 4 and immersed in the cooling liquid C for quenching (timings A1 to A2'). During the initial period of the hardening period P1, purging is performed to replace the gas in the cooling chamber 4 with the gas for heat treatment (timings A1 to A2). Further, after the purge is completed, the object 100 to be processed is loaded into the heating chamber 3 through the cooling chamber 4 through the inlet/outlet 4a. When the object 100 to be processed is loaded into the heating chamber 3, the ambient temperature of the heating chamber 3 decreases. Timing A2-A3). After reheating, the processes after preheating (timings A3 to A4) are repeated. For example, the workpiece 100 is immersed in the coolant C in the cooling chamber 4 during quenching, and placed in the gas atmosphere of the heating chamber 3 or the cooling chamber 4 except during this immersion. When the workpiece 100 is transferred between the heating chamber 3 and the cooling chamber 4, the second door 14 is opened.

As described above, in this embodiment, the heat treatment apparatus 1 is a carburizing treatment apparatus for carburizing the object 100 to be treated. Next, the object 100 to be treated is maintained at the soaking temperature for a predetermined time, and then the object 100 to be treated is put into the cooling bath 6 to perform quenching.

In the above processing pattern, the processing pattern in the heating chamber 3 includes "rewarming", "preheating", "carburizing", "diffusion", "cooling down", and "soaking" as one cycle.

While the above processing pattern is being performed in the heating chamber 3, the cooling chamber 4 performs "quenching", "lowering the temperature of the cooling liquid", and "fixing the temperature of the cooling liquid".

As shown in FIG. 3, during the quenching period P1, purging, loading of the workpiece 100, and start of reheating are performed (timings A1 to A2'). In the present embodiment, the cooling liquid C temperature drop (periods P2 to P4) is performed until the latter stage of the temperature drop in the heating chamber 3 after the completion of quenching. In the present embodiment, the constant temperature of the coolant (constant temperature period P5) is performed until the timing A1 at which quenching is started after the temperature of the coolant C is lowered.

In this embodiment, the cooling liquid C is cooled and kept at a constant temperature during the period described above, but this does not have to be the case. The period for decreasing the temperature of the cooling liquid C may be shorter than the period described above, or may be longer than the period described above, and the constant temperature period for the cooling liquid C may be omitted.

In this embodiment, the hardening period P1 is, for example, a period of about 20 minutes (timings A1 to A2'). A period from the end of the hardening period P1 to the completion of reheating is defined as a natural cooling period P2 (timings A2' to A3). A period from the start of preheating to the completion of diffusion is defined as a first slow cooling period P3 (timings A3 to A6). Also, the period from the end of the first slow cooling period P3 to the middle of the temperature drop is defined as the second slow cooling period P4 (timings A6 to A6'). Also, the period from the end of the second slow cooling period P4 to the completion of soaking is defined as the constant temperature period P5 (timings A6' to A1). In the lower diagram of FIG. 3, periods P1 and P2 show an example of the measured temperature Tm of the coolant C, and periods P3 to P5 show an example of the target temperature Tt of the coolant C. As shown in FIG.

During the quenching period P1, the workpiece 100 is immersed in the cooling liquid C, so that the measured temperature Tm of the cooling liquid C sharply increases by, for example, about 20° C., and then gradually decreases. In the present embodiment, during the quenching period P1, the control unit 8 performs neither the heating operation by the heating unit 28 nor the cooling operation by the cooling unit 27, and allows the coolant C to cool naturally. The length of the quenching period P1 may be set by an operator operating the operation/display unit 9, or may be set by the operator selecting a processing pattern displayed on the operation/display unit 9. may be set. Note that the control unit 8 may perform the cooling operation of the cooling liquid C by the cooling unit 27 during the hardening period P1.

The workpiece 100 is removed from the cooling bath 6 during periods P2 to P5. In the present embodiment, during the natural cooling time P2, the control unit 8 executes the natural cooling mode so that neither the heating operation by the heating unit 28 nor the cooling operation by the cooling unit 27 is performed. The controller 8 determines that the natural cooling period P2 ends when the measured temperature of the heating chamber 3 reaches the preheating temperature.

In the first slow cooling period P3 and the second slow cooling period P4, the control section 8 is configured to execute the induction cooling mode. The induction cooling mode is a mode in which the target temperature Tt of the cooling liquid C is set to change over time, and the temperature adjustment mechanism 25 is driven so that the measured temperature Tm of the cooling liquid C becomes the target temperature Tt. . In particular, in the present embodiment, the induction cooling mode is a mode in which the temperature adjustment mechanism 25 is driven such that the measured temperature Tm of the coolant C falls within the target temperature Tt.

The control unit 8 controls the period (P3, P4) from the start to the end of the induction cooling mode, and the temperature difference ΔT1 between the measured temperature Tm1 of the coolant C at the start of the induction cooling mode and the target temperature Ttf at the end of the induction cooling mode. A target temperature Tt for each unit time is set based on (Tm1-Ttf).

Specifically, the control unit 8 first refers to the first slow cooling period P3. When defining the first slow cooling period P3, the controller 8 refers to the time required for preheating, carburizing, and diffusion. The time required for preheating, carburizing, and diffusion may be set by, for example, an operator operating the operation/display unit 9, or the operator may set the processing pattern displayed on the operation/display unit 9. It may be set along with the selection. Then, the control unit 8 sets the total time (timings A3 to A6) required for preheating, carburizing, and diffusion as the first slow cooling period P3. The temperature of the heating chamber 3 during preheating, carburizing, and soaking may be set by an operator operating the operation/display unit 9, or the processing pattern displayed on the operation/display unit 9 may be set. may be set by the control unit 8 based on the selection of the operator.

Further, the control unit 8 calculates the second slow cooling period P4. When calculating the second slow cooling period P4, the control unit 8 refers to the temperature drop time (timings A6 to A7). The temperature drop time is the time required for the temperature of the workpiece 100 to drop from the diffusion temperature to the soaking temperature. be. This temperature-lowering period is calculated by the control unit 8 based on the known characteristics of the heat treatment apparatus 1, the treatment pattern of the workpiece 100, and the like.

The control unit 8 calculates the temperature drop time (timings A6 to A7) using the following formula (1).
Cooling time = ΔF/Vm (min) (1)
ΔF is (carburizing temperature−soaking temperature) in the heating chamber 3 . Also, Vm is the temperature drop rate (° C./min) of the heating chamber 3 in the heat treatment mechanism 2, and is a constant, for example.

In this embodiment, the time required for the measured temperature Tm of the heating chamber 3 to reach the soaking temperature + the predetermined temperature f (for example, 10° C.), that is, the time required for (ΔF−f)/Vm (min) , is set as the second slow cooling period P4. Expressed as a formula, the second slow cooling period P4 is given by the following formula (2).
Second slow cooling period P4=(ΔF−f)/Vm (min) (2)

The control unit 8 may calculate the second slow cooling period P4=(ΔF−f)/Vm(min) without calculating the cooling time=ΔF/Vm(min). Further, the control unit 8 may set the temperature lowering time (period of timings A6 to A7)=second slow cooling period P4. That is, the second slow cooling period P4 may end at the start of soaking (timing A7). Also, the second slow cooling period P4 may end immediately before the start of quenching (timing A1). In this case, the control unit 8 may set the total period (timings A6 to A1) of the cooling period (period of timings A6 to A7) and the soaking period (period of timings A7 to A1) as the second slow cooling period P4. .

The control unit 8 sets the above-described first slow cooling period P3+second slow cooling period P4 as the induction cooling mode execution period.

Next, the control unit 8 determines the actual measured temperature Tm1 of the cooling liquid C at timing A3 at the time of completion of reheating (when the temperature of the heating chamber reaches the preheating temperature), , the temperature difference ΔT1 between the coolant C and the target temperature Ttf is calculated. This target temperature Ttf is the final target temperature of the coolant C, and is set in advance based on the processing pattern of the workpiece 100 and the like. The final target temperature Ttf of the coolant C may be set by an operator operating the operation/display unit 9, or may be set based on the operator setting a processing pattern displayed on the operation/display unit 9. may be set by the control unit 8.

In the present embodiment, the control unit 8 sets the target temperature Tt of the coolant C so as to linearly decrease as time elapses in the induction cooling mode. Further, in this embodiment, the target temperature Tt has a predetermined temperature width (Tt1-Tt2). Within the temperature range (Tt1-Tt2), a target center temperature Tt0, a target upper limit temperature Tt1 higher than the target center temperature Tt0, and a target lower limit temperature Tt2 lower than the target center temperature Tt0 are set. The controller 8 drives the temperature adjustment mechanism 25 so that the measured temperature Tm is between the target upper limit temperature Tt1 and the target lower limit temperature Tt2.

More specifically, the control unit 8 sets the target core temperature Tt0 for each time Px in the induction cooling mode at the start of the first slow cooling period T3. In the present embodiment, the target core temperature Tt0 is set such that the rate of decrease of the target core temperature Tt0 is constant during the induction cooling mode execution period (period P3+P4). That is, the control unit 8 sets the target center temperature Tt0=actually measured temperature Tm1-{Px/(P3+P4)}×ΔT1 of the coolant C at the start of the induction cooling mode. In the lower diagram of FIG. 3, this target center temperature Tt0 is shown by a linear graph.

In the present embodiment, in the first slow cooling period P3, the target upper limit temperature Tt1 is set as the target center temperature Tt0+α1° C. (α1° C.=3° C. in the present embodiment), and the target lower limit temperature Tt2 is The target center temperature is set as Tt0-α2° C. (α2° C.=3° C. in this embodiment). Note that α1 and α2 may be less than 3 or 3 or more. Also, α1 and α2 may be the same value or different values.

In the present embodiment, in the second slow cooling period P4, the target upper limit temperature Tt1 is set as the target center temperature Tt0+α3° C. (α3° C.=1° C. in this embodiment), and the target lower limit temperature Tt2 is set as the target center temperature Tt0+α3° C. The temperature is set as Tt0-α4° C. (α4° C.=1° C. in this embodiment). Note that α3 and α4 may be less than 1 or greater than or equal to 1. Also, α3 and α4 may be the same value or different values.

In the present embodiment, compared with the first slow cooling period P3, that is, the difference (Tt1−Tt2) (6° C. in this embodiment) between the target upper limit temperature Tt1 and the target lower limit temperature Tt2 at the beginning of the induction cooling mode, The difference (Tt1−Tt2) (2° C. in this embodiment) between the target upper limit temperature Tt1 and the target lower limit temperature Tt2 in the second slow cooling period P4, ie, the latter half of the induction cooling mode, is made small.

In the present embodiment, when switching from the first slow cooling period P3 to the second slow cooling period P4, the controller 8 controls the control unit 8 every unit time (for example, every time it takes to lower the temperature of the coolant C by 1° C.). ) is reset. Specifically, the control unit 8 controls the measured temperature Tm2 of the coolant C at the end of the first slow cooling period P3 (timing A6 set by the control unit 8) and the temperature during soaking, that is, immediately before the next quenching A temperature difference ΔT2 between the coolant C and the target temperature Ttf is calculated. Next, the control unit 8 sets a target core temperature Tt0 for each time Px (for example, each time it takes to lower the temperature of the coolant C by 1° C.) in the second slow cooling period P4. At this time, the target core temperature Tt0 is again set such that the rate of decrease of the target core temperature Tt0 is constant during the second slow cooling period P4.

That is, the control unit 8 sets the target central temperature Tt0=actually measured temperature Tm2-(Px/P4)×ΔT2 of the coolant C at the start of the second slow cooling period P4. In the lower diagram of FIG. 3, for convenience, the target central temperature Tt0 after resetting is the same as the graph of the target central temperature Tt0 before resetting.

Note that the control unit 8 does not need to reset the target temperature Tt described above at the start of the second slow cooling period P4.

The control unit 8 drives the temperature adjustment mechanism 25 so that the actually measured temperature Tm of the coolant C becomes equal to the target temperature Tt during the induction cooling mode execution period including the first slow cooling period P3 and the second slow cooling period P4. do. As described above, in the present embodiment, the control unit 8 predicts the cooling time (timings A6 to A7) for the temperature of the workpiece 100 to drop from the carburizing temperature to the soaking temperature, and The induction cooling mode is terminated at (timing A6'). Next, during the constant temperature period P5, the controller 8 executes the constant temperature mode in which the temperature adjustment mechanism 25 is controlled so as to keep the target temperature constant.

During the constant temperature period P5, the control unit 8 executes the constant temperature mode to drive the temperature adjustment mechanism 25 so that the actually measured temperature Tm of the coolant C becomes a constant target temperature Ttf. Specifically, the control unit 8 sets the time (timings A6' to A1) from the end of the second slow cooling period P4 to the end of soaking as the constant temperature period P5. The soaking period may be set by an operator operating the operation/display unit 9, or may be set by the operator by selecting a processing pattern displayed on the operation/display unit 9. may be set.

Next, the control unit 8 sets a target center temperature Tt0, a target upper limit temperature Tt1, and a target lower limit temperature Tt2 as the target temperature Tt of the coolant C. As shown in FIG. In the constant temperature period P5, the target center temperature Tt0 is the final target temperature Ttf of the coolant C (Tt0=Ttf). The target upper limit temperature Tt1 is a temperature higher than the target central temperature Tt0 by, for example, about 0 to 2.degree. The target lower limit temperature Tt2 is a temperature lower than the target central temperature Tt0 by, for example, about 0 to 2°C. When the measured temperature Tm of the cooling liquid C becomes equal to or higher than the target upper limit temperature Tt1, the control unit 8 drives the cooling unit 27 to lower the temperature of the cooling liquid C so that the measured temperature Tm of the cooling liquid C becomes equal to or lower than the target lower limit temperature Tt2. When it becomes, the heating unit 28 is driven to raise the cooling liquid C.

As described above, the control unit 8 executes the natural cooling mode during the hardening period P1 and the natural cooling period P2 so that neither the heating unit 28 nor the cooling unit 27 is driven. During the period P2, the coolant C is naturally cooled. By executing the induction cooling mode in the first slow cooling period P3 and the second slow cooling period P4, the control unit 8 drives the temperature adjustment mechanism 25 so that the measured temperature Tm of the cooling liquid C gradually decreases. . Further, the control unit 8 drives the temperature adjustment mechanism 25 so that the measured temperature Tm of the coolant C becomes a constant target center temperature Tt0 during the constant temperature period P5.

In this embodiment, the control unit 8 is configured to minimize the time for heating the coolant C by the heating unit 28 . The history of the measured temperature Tm of the cooling liquid C obtained by the temperature control of the cooling liquid C by the control unit 8 will be described more specifically with reference to two examples shown in FIGS. 4 and 5. FIG.

In this embodiment, the control unit 8 performs temperature control of the cooling liquid C according to the "forced cooling control example" shown in FIG. 4 and temperature control of the cooling liquid C according to the "heating control example" shown in FIG. be able to. The temperature control of the coolant C by the "forced cooling control example" shown in FIG. is also a control when the natural cooling speed of the coolant C is slow. On the other hand, the temperature control of the coolant C according to the "heating control example" shown in FIG. 5 is control when the natural cooling rate of the coolant C is higher than the target cooling rate.

FIG. 4 is a diagram showing an example of the history of the measured temperature Tm of the coolant C in the "forced cooling control example". The measured temperature Tm is indicated by a solid line.

1 and 4, as described above, the control unit 8 executes the natural cooling mode during the quenching period P1 and the natural cooling period P2 to cool the heating unit 28 and the cooling unit 27. not drive anything. As the workpiece 100 is immersed in the cooling liquid C and quenched under such conditions, the measured temperature Tm of the cooling liquid C sharply rises in the first half of the quenching period P1, and then gently decreases. .

Then, when the natural cooling period P2 ends and shifts to the first slow cooling period P3, the control section 8 executes the induction cooling mode. In the induction cooling mode, the controller 8 drives the temperature adjustment mechanism 25 so that the measured temperature Tm falls within the target temperature Tt set for each unit time (the time required to lower the temperature of the coolant C by 1° C.). . In the "forced cooling control example" of FIG. 4, the control unit 8 drives the cooling unit 27 to cool the coolant C when the measured temperature Tm is higher than the target center temperature Tt0.

The control unit 8 starts driving the cooling unit 27 to cool the cooling liquid C when the measured temperature Tm of the cooling liquid C is equal to the target upper limit temperature Tt1. The control unit 8 naturally cools the coolant C until a certain timing D1, for example, in the first slow cooling period P3. Then, the control unit 8 determines that the measured temperature Tm of the cooling liquid C has reached the target upper limit temperature Tt1 at timing D1, and drives the cooling unit 27 to cool the cooling liquid C. Then, the control unit 8 stops driving the cooling unit 27 when it determines that the measured temperature Tm of the coolant C has decreased to the target center temperature Tt0 at a certain timing D2 after the timing D1.

In this way, when the measured temperature Tm of the coolant C reaches the target upper limit temperature Tt1, cooling of the coolant C by the cooling unit 27 is started. By repeating the operation of stopping the driving of the portion 27, the actually measured temperature Tm gradually decreases stepwise in the first slow cooling period P3. In the example of the forced cooling control, the heating operation by the heating unit 28 is not performed regardless of whether the cooling unit 27 is operating or not. Further, in the forced cooling control example, the driving of the cooling unit 27 may be stopped when the measured temperature Tm reaches an arbitrary temperature between the target upper limit temperature Tt1 and the target lower limit core temperature Tt2.

When the first slow cooling period P3 ends and shifts to the second slow cooling period P4, the control unit 8 resets the target temperature Tt as described above. Then, the controller 8 continues to drive the temperature adjustment mechanism 25 so that the measured temperature Tm falls within the set target temperature Tt. In the second slow cooling period P4 as well, the temperature adjustment mechanism 25 is driven in the same manner as in the first slow cooling period P3, except that the target temperature Tt has a different temperature width, so that the measured temperature Tm gradually decreases stepwise. descend.

When the second slow cooling period P4 ends and shifts to the constant temperature period P5, the control unit 8 sets the target center temperature Tt0 to a constant final target temperature Ttf, and sets the measured temperature Tm to the final target temperature Ttf. 25. In the constant temperature period P5, the control unit 8 heats the cooling liquid C by the heating unit 28 when the measured temperature Tm reaches the target lower limit temperature Tt2.

FIG. 5 is a diagram showing an example of the history of the measured temperature Tm of the coolant C in the "heating control example". 1 and 5, the "heating control example" shown in FIG. 5 differs from the "forced cooling control example" shown in FIG. This is the control contents in the induction cooling mode. The control of the temperature adjustment mechanism 25 by the control unit 8 in the periods P1, P2, and P5 is the same as the example shown in FIG. 4, so the explanation is omitted.

In the "heating control example" of FIG. 5, the control unit 8 drives the heating unit 28 to heat the coolant C when the measured temperature Tm is lower than the target center temperature Tt0.

The control unit 8 starts driving the heating unit 28 to heat the cooling liquid C when the measured temperature Tm of the cooling liquid C is equal to the target lower limit temperature Tt2. The control unit 8 naturally cools the coolant C until a certain timing E1, for example, in the first slow cooling period P3. Then, the control unit 8 determines that the measured temperature Tm has reached the target lower limit temperature Tt2 at timing E1, and drives the heating unit 28 to heat the coolant C. As shown in FIG. Then, when the controller 8 determines that the measured temperature Tm has risen to the target center temperature Tt0 at a certain timing E2 after the timing E1, it stops driving the heating unit 28 .

In this way, when the measured temperature Tm of the coolant C reaches the target lower limit temperature Tt2, heating of the coolant C by the heating unit 28 is started. By repeating the operation of stopping the drive of the portion 28, the actually measured temperature Tm gradually decreases stepwise in the first slow cooling period P3. Note that in the heating control example, the cooling operation by the cooling unit 27 is not performed regardless of whether the heating unit 28 is operating or not. Further, in the heating control example, the driving of the heating unit 28 may be stopped when the measured temperature Tm reaches an arbitrary temperature between the target upper limit temperature Tt1 and the target lower limit core temperature Tt2.

When the first slow cooling period P3 ends and shifts to the second slow cooling period P4, the control unit 8 resets the target temperature Tt as described above. Then, the controller 8 continues to drive the temperature adjustment mechanism 25 so that the measured temperature Tm falls within the set target temperature Tt. In the second slow cooling period P4 as well, the temperature adjustment mechanism 25 is driven in the same manner as in the first slow cooling period P3, except that the temperature width (Tt1-Tt2) of the target temperature Tt is different. The temperature Tm gradually decreases.

As described above, according to the present embodiment, in the induction cooling mode, the control unit 8 sets the target temperature Tt of the coolant C so as to change over time, and the measured temperature Tm of the coolant C is set to The temperature adjustment mechanism 25 is driven so as to reach the target temperature Tt. According to this configuration, the cooling liquid C whose temperature is raised by the heated object 100 being put into the cooling bath 6 is cooled until the next heated object 100 is put into the cooling bath 6 . It can be cooled in between. During this cooling, the control unit 8 sets the target temperature Tt of the coolant C to change with time in the induction cooling mode (slow cooling periods P3 and P4), and sets the measured temperature Tm of the coolant C to is the target temperature Tt. With this configuration, the cooling liquid C can be prevented from being rapidly cooled by the cooling unit 27 . Thereby, the control unit 8 can gradually lower the temperature of the coolant C. FIG. As a result, after the temperature of the cooling liquid C reaches the temperature (final target temperature Ttf) required at the start of quenching of the workpiece 100, the heating operation of the cooling liquid C for maintaining this temperature is set to zero or can be minimized. That is, as a result of being able to reduce the energy for heating the cooling liquid C, the heat treatment apparatus 1 that performs the process of cooling the heated workpiece 100, such as quenching, can be configured to be excellent in energy saving, and Operating costs such as energy costs can be reduced.

Further, according to the present embodiment, the target temperature Tt for each unit time required when the induction cooling mode is executed is set to the period from the start to the end of the induction cooling mode (slow cooling periods P3, P4) and It can be set based on the temperature difference ΔT1 between the measured temperature Tm1 and the target temperature Ttf at the end of the induction cooling mode. As a result, the target temperature can be set for each unit of time by a simple calculation, and can also be set with a high degree of freedom.

Further, according to the present embodiment, in the induction cooling mode, the control unit 8 linearly lowers the target temperature Tt of the coolant C as time elapses. According to this configuration, the target temperature Tt required for each unit time when the induction cooling mode is executed can be set by a simple calculation.

Further, according to the present embodiment, since the temperature range (Tt1-Tt2) is provided for the target temperature Tt, it is not necessary to strictly control the coolant temperature, and coolant temperature control is realized with a simpler configuration. can.

Further, according to the present embodiment, compared with the difference (Tt1−Tt2) between the target upper limit temperature Tt1 and the target lower limit temperature Tt2 at the beginning of the induction cooling mode (period P3), the target A difference (Tt1-Tt2) between the upper limit temperature Tt1 and the target lower limit temperature Tt2 is reduced. According to this configuration, after cooling the object 100 to be processed, the temperature of the cooling liquid C into which the object 100 to be heated next is introduced can be more accurately requested at the time the object to be processed 100 is introduced. temperature (final target temperature Ttf).

Further, according to the present embodiment, the control unit 8 can drive the cooling unit 27 to cool the coolant C when the measured temperature Tm is higher than the target center temperature Tt0. According to this configuration, the trigger for starting the driving of the cooling unit 27 can be simplified.

Further, according to the present embodiment, the control unit 8 starts driving the cooling unit 27 to cool the coolant C when the measured temperature Tm is equal to the target upper limit temperature Tt1, and the measured temperature Tm reaches the target center temperature Tt1. The driving of the cooling unit 27 can be stopped when the temperature has decreased to Tt0. According to this configuration, excessive cooling of the coolant C by the cooling unit 27 can be suppressed. As a result, an operation that requires a large amount of energy, such as reheating the cooling liquid C in the heating unit 28 due to an excessive decrease in the cooling liquid temperature, can be further reduced.

Further, according to the present embodiment, the control unit 8 can drive the heating unit 28 to heat the coolant C when the measured temperature Tm is lower than the target center temperature Tt0. According to this configuration, the temperature of the coolant C can be maintained so that the temperature of the coolant C does not become too low from the target center temperature Tt0.

Further, according to the present embodiment, the control unit 8 starts driving the heating unit 28 to heat the coolant C when the measured temperature Tm is equal to the target lower limit temperature Tt2, and the measured temperature Tm reaches the target central temperature Tt0. The driving of the heating unit 28 can be stopped when the temperature rises to According to this configuration, excessive heating of the coolant C by the heating unit 28 can be suppressed. As a result, the temperature of the coolant C can be maintained with minimal heating.

In addition, according to the present embodiment, the control unit 8 predicts the cooling time (timings A6 to A7) for the temperature of the workpiece 100 to drop from the carburizing temperature to the soaking temperature. At (timing A6', end of period P4), the induction cooling mode is ended, and then the constant temperature mode (constant temperature period P5) is executed. According to this configuration, the controller 8 can perform the induction cooling mode for a longer period of time. Accordingly, the time for executing the constant temperature mode can be shortened. In the constant temperature mode (constant temperature period P5), it is necessary to keep the target temperature Tt constant. However, by shortening the execution time of this constant temperature mode, the energy consumption associated with the heating operation can be reduced.

Although the embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments. The present invention can be modified in various ways within the scope of the claims.

(1) In the above-described embodiment, in the induction cooling mode (slow cooling periods P3 and P4) of the "heating control example" shown in FIG. The measured temperature Tm was gradually lowered. However, this need not be the case. For example, when the measured temperature Tm of the cooling liquid C is lower than the target central temperature Tt0, the heating unit 28 is temporarily adjusted so that the measured temperature Tm of the cooling liquid C reaches between the target central temperature Tt0 and the target upper limit temperature Tt1. After the cooling liquid C is heated, the cooling unit 27 may intermittently cool the cooling liquid C as shown in the "forced cooling control example" in FIG. In this case, in the induction cooling mode, the time for the heating unit 28 to heat the coolant C can be shortened.

(2) In the above-described embodiment, in the induction cooling mode (the first slow cooling period P3 and the second slow cooling period P4), the target temperature Tt is continuously (linearly) lowered over time as an example. explained. However, this need not be the case. For example, in the induction cooling mode, the target temperature Tt may be lowered stepwise (stepwise), or may be raised once as time elapses.

(3) In the above-described embodiment, the cooling operation of the cooling liquid C by the cooling unit 27 is not performed during the hardening period P1 and the natural cooling period P2. However, this need not be the case. For example, the control unit 8 may perform the cooling operation of the cooling liquid C by the cooling unit 27 during the hardening period P1. Further, the control unit 8 may perform the cooling operation of the cooling liquid C by the cooling unit 27 during the natural cooling period P2. In the quenching period P1 and the natural cooling period P2, whether to perform the natural cooling or the cooling operation of the cooling liquid C by the cooling unit 27 can be selected by the operator by operating the operation/display unit 9. good.

(4) In the above-described embodiment, the end of the natural cooling period P2 was when the measured temperature Tm of the heating chamber 3 returned to the preheating temperature. However, this need not be the case. The end of the natural cooling period P2 may be the time after the start of preheating. Alternatively, the natural cooling period P2 may be omitted and the first slow cooling period P3 may be started immediately after the hardening period P1.

(5) The end of the second slow cooling period T4 may be the end of soaking (timing A1). In this case, the constant temperature mode can be omitted.

(6) In the above-described embodiment, the heat treatment apparatus 1 is a carburizing apparatus. However, this need not be the case. For example, the present invention may be applied to other heat treatment apparatuses such as a nitriding apparatus, a carbonitriding apparatus, a quenching apparatus, a gas nitrocarburizing apparatus, and an aluminum solution treatment apparatus. Even when the present invention is applied to the other heat treatment apparatus, the control unit can execute the induction cooling mode, for example, between the completion of quenching by cooling liquid and the next quenching.

Next, an example of control when the heat treatment apparatus 1 performs a process other than the carburizing process will be described. In the following, points different from the embodiment will be mainly described, and configurations similar to the embodiment will be given the same reference numerals or explanations in the drawings, and detailed explanation will be omitted.

FIG. 6 is a diagram for explaining the relationship between the treatment pattern of the workpiece and the cooling liquid temperature in a modified example in which the heat treatment apparatus 1 performs a treatment different from that of the carburizing treatment apparatus. In the modification shown in FIG. 6, the heat treatment apparatus 1 heats the workpiece 100 at the heat treatment temperature instead of the preheating/carburizing/diffusion temperature in the embodiment. Further, in the modification shown in FIG. 6, soaking at a temperature lower than the heat treatment temperature is not performed. The upper diagram of FIG. 6 is a diagram for explaining the processing pattern of the workpiece 100. The horizontal axis indicates time, and the vertical axis indicates the measured value of the heating chamber temperature (the atmospheric temperature in the heating chamber). ing. The lower diagram of FIG. 6 is a diagram for explaining the temperature of the coolant C, where the horizontal axis represents time and the vertical axis represents the temperature of the coolant C. As shown in FIG.

To explain the processing pattern of the workpiece 100 in the modification shown in FIG. 6, the heating chamber 3 is heated to a predetermined heat treatment temperature to heat the workpiece 100 (timings A3 to A1). . Next, the workpiece 100 is transported to the cooling chamber 4 and immersed in the cooling liquid C for quenching (timings A1 to A2'). During the initial period of the hardening period P1, purging is performed to replace the gas in the cooling chamber 4 with the gas for heat treatment (timings A1 to A2). Further, after the purge is completed, the object 100 to be processed is loaded into the heating chamber 3 through the cooling chamber 4 through the inlet/outlet 4a. When the object 100 to be processed is loaded into the heating chamber 3, the ambient temperature of the heating chamber 3 decreases. (Timings A2 to A3). After rewarming, the process after timing A3 is repeated.

In the above processing pattern, the processing pattern in the heating chamber 3 includes "rewarming" and "heating" as one cycle.

While the above processing pattern is being performed in the heating chamber 3, the cooling chamber 4 performs "quenching", "lowering the temperature of the cooling liquid", and "fixing the temperature of the cooling liquid".

As shown in FIG. 6, during the quenching period P1, purging, loading of the workpiece 100, and start of reheating are performed (timings A1 to A2'). In this modification, the cooling liquid C is lowered in temperature (periods P2 to P4) for a predetermined period (timings A2' to A3'') after quenching is completed. In this modified example, the constant temperature of the coolant (constant temperature period P5) is performed until the timing when quenching is started after the temperature of the coolant C is lowered (timings A3'' to A1).

In this modification, the period from the end of the quenching period P1 to the completion of reheating is defined as the natural cooling period P2 (timings A2' to A3). Also, the period from the start to the middle of the period in which the heating chamber temperature is the heat treatment temperature is defined as the first slow cooling period P3 (timings A3 to A3'). A predetermined period from the end of the first slow cooling period P3 is defined as the second slow cooling period P4 (timings A3' to A3''). is defined as the constant temperature period P5 (timings A3'' to A1). In the lower diagram of FIG. 6, periods P1 and P2 show an example of the measured temperature Tm of the coolant C, and periods P3 to P5 show an example of the target temperature Tt of the coolant C. As shown in FIG.

In this embodiment, the cooling liquid C is cooled and kept at a constant temperature during the period described above, but this does not have to be the case. The period for decreasing the temperature of the cooling liquid C may be shorter than the period described above, or may be longer than the period described above, and the constant temperature period for the cooling liquid C may be omitted.

In this modification, the timings A1, A2, A2', A3, A3', and A3'' may be set by the operator operating the operation/display unit 9, or may be displayed on the operation/display unit 9. It may be set according to the worker's selection of the processing pattern. Note that the timings A2 and A3 may be left to chance. Similarly, the hardening period P1, the natural cooling period P2, the first slow cooling period P3, the second slow cooling period P4, and the constant temperature period P5 are set by the operator operating the operation/display unit 9. Alternatively, it may be set according to the worker's selection of a processing pattern displayed on the operation/display unit 9 . Note that the natural cooling period P2 may be configured to be left to chance.

The workpiece 100 is removed from the cooling bath 6 during periods P2 to P5. In this modification, the controller 8 executes the natural cooling mode during the hardening period P1 and the natural cooling period P2. The controller 8 determines that the natural cooling period P2 ends when the measured temperature of the heating chamber 3 reaches the heat treatment temperature (timing A3).

In the first slow cooling period P3 and the second slow cooling period P4, the control section 8 is configured to execute the induction cooling mode.

The control unit 8 controls the period from the start to the end of the induction cooling mode (periods P3 and P4), and the temperature difference between the measured temperature Tm1 of the coolant C at the start of the induction cooling mode and the target temperature Ttf at the end of the induction cooling mode. A target temperature Tt for each unit time is set based on ΔT1 (Tm1−Ttf).

Specifically, the controller 8 first calculates the first slow cooling period P3 and the second slow cooling period P4. Then, the control unit 8 sets the above-described first slow cooling period P3+second slow cooling period P4 as the induction cooling mode execution period.

Next, the control unit 8 determines the measured temperature Tm1 of the coolant C at timing A3 (when the heating chamber temperature reaches the heat treatment temperature), and the temperature Tm1 of the coolant C at the end of the induction cooling mode (timing A3''). is calculated as a temperature difference ΔT1 from the target temperature Ttf.

In this modified example, similarly to the embodiment, in the induction cooling mode, the control unit 8 sets the target temperature Tt of the coolant C so as to linearly decrease as time elapses.

In this modification, when switching from the first slow cooling period P3 to the second slow cooling period P4, the control unit 8 controls the temperature of each unit time (for example, every time it takes to lower the temperature of the coolant C by 1° C.). The target temperature Tt is configured to be reset.

Note that the control unit 8 does not need to reset the target temperature Tt described above at the start of the second slow cooling period P4. In addition to the first slow cooling period P3, the controller 8 may continue the same temperature control as in the first slow cooling period P3 during the second slow cooling period P4.

In this modification, the control unit 8 executes the constant temperature mode during the constant temperature period P5.

Also in this modification, the control unit 8 controls the temperature of the cooling liquid C according to the "forced cooling control example" shown in FIG. 4 and the "heating control temperature control of the cooling liquid C according to "Example" can be performed.

(7) The present invention only requires that the controller 8 can execute the induction cooling mode, and is not limited to other configurations. In other words, the present invention sets the target temperature Tt of the coolant C to change over time, and drives the temperature adjustment mechanism 25 so that the measured temperature Tm of the coolant C becomes the target temperature Tt. Any configuration may be used, and other configurations are not limited.

INDUSTRIAL APPLICABILITY The present invention can be applied as a heat treatment apparatus and a temperature control method for cooling liquid in the heat treatment apparatus.

1 heat treatment device 6 cooling bath 7 liquid thermometer (temperature sensor)
8 Control unit 25 Temperature adjustment mechanism 27 Cooling unit 28 Heating unit 100 Workpiece C Cooling liquid Tm Measured temperature of cooling liquid Tm1 Measured temperature at the start of induction cooling mode Tt Target temperature of cooling liquid Tt0 Target core temperature Tt1 Target upper limit temperature Tt2 Target lower limit temperature Ttf Target temperature at the end of induction cooling mode Tt1-Tt2 Temperature width ΔT1 Temperature difference

Claims (11)

a cooling tank in which a cooling liquid for cooling the heated object to be processed is stored;
a temperature sensor that measures the temperature of the coolant;
a temperature adjustment mechanism including a cooling unit for cooling the cooling liquid and a heating unit for heating the cooling liquid;
A control unit that controls the temperature adjustment mechanism,
The control unit is configured to be able to execute an induction cooling mode,
In the induction cooling mode, the control unit sets the target temperature of the cooling liquid to change with time, and drives the temperature adjustment mechanism so that the actually measured temperature of the cooling liquid becomes the target temperature. heat treatment equipment. The heat treatment apparatus according to claim 1,
The control unit controls the target temperature based on the period from the start to the end of the induction cooling mode and the temperature difference between the measured temperature at the start of the induction cooling mode and the target temperature at the end of the induction cooling mode. heat treatment equipment. The heat treatment apparatus according to claim 1 or claim 2,
The heat treatment apparatus, wherein the control unit linearly lowers the target temperature of the coolant over time in the induction cooling mode. The heat treatment apparatus according to any one of claims 1 to 3,
The target temperature has a predetermined temperature range,
Within the temperature range, a target center temperature, a target upper limit temperature higher than the target center temperature, and a target lower limit temperature lower than the target center temperature are set,
The heat treatment apparatus, wherein the control unit drives the temperature adjustment mechanism so that the measured temperature falls between the target upper limit temperature and the target lower limit temperature. The heat treatment apparatus according to claim 4,
The heat treatment apparatus, wherein the difference between the target upper limit temperature and the target lower limit temperature in the latter stage of the induction cooling mode is smaller than the difference between the target upper limit temperature and the target lower limit temperature in the initial period of the induction cooling mode. . The heat treatment apparatus according to claim 4 or claim 5,
The heat treatment apparatus, wherein the control unit drives the cooling unit to cool the coolant when the actually measured temperature is higher than the target center temperature. The heat treatment apparatus according to claim 6,
The control unit starts driving the cooling unit to cool the cooling liquid when the measured temperature is the target upper limit temperature, and the cooling unit when the measured temperature has decreased to the target center temperature. Heat treatment equipment that stops the drive of. The heat treatment apparatus according to any one of claims 4 to 7,
The heat treatment apparatus, wherein the control unit drives the heating unit to heat the coolant when the measured temperature is lower than the target center temperature. The heat treatment apparatus according to claim 8,
The control unit starts driving the heating unit to heat the cooling liquid when the measured temperature is the target lower limit temperature, and the heating unit when the measured temperature rises to the target center temperature. Heat treatment equipment that stops the drive of. The heat treatment apparatus according to any one of claims 1 to 9,
The heat treatment apparatus is a carburizing treatment apparatus for carburizing the object to be treated, in which the object to be treated is heated to a predetermined carburizing temperature, then cooled to a predetermined soaking temperature, and then the object to be treated is heated for a predetermined period of time. The soaking temperature is maintained, and then the object to be processed is put into the cooling bath,
The control unit predicts the cooling time required for the temperature of the object to be processed to decrease from the carburizing temperature to the soaking temperature, terminates the induction cooling mode during the cooling time, and determines the target temperature. A heat treatment apparatus configured to execute a constant temperature mode that controls the temperature adjustment mechanism to maintain a constant . a cooling tank in which a cooling liquid for cooling the heated object to be processed is stored;
a temperature adjustment mechanism including a cooling unit for cooling the cooling liquid and a heating unit for heating the cooling liquid;
In a heat treatment apparatus comprising
A cooling liquid temperature control method in a heat treatment apparatus, wherein the target temperature of the cooling liquid is set to change with time, and the temperature adjustment mechanism is driven so that the actually measured temperature of the cooling liquid becomes the target temperature. .

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