Heat treatment control device and control program

Abstract

To prevent the delay of overshoot suppression when reaching a target treatment temperature from a temperature rising state during heat treatment.SOLUTION: A heat treatment control device 30 raises a temperature of the atmosphere in a heat treatment chamber 10 to a predetermined target treatment temperature Tht. The heat treatment control device 30 performs temperature control such that the temperature is raised toward the target treatment temperature Tht for a predetermined time tP from the start of the temperature rise, and before the temperature reaches the target treatment temperature Tht and after the predetermined time tP has elapsed, the degree of temperature rise is reduced as the temperature approaches the target treatment temperature Tht by a filter whose time constant τ changes with a time t.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a heat treatment control device and a control program for raising the temperature of an atmosphere in a heat treatment chamber to a predetermined target treatment temperature. [Background technology]

[0002] In heat treatment, the atmosphere in the heat treatment chamber is controlled to rise to a target treatment temperature. When controlling the temperature to rise to the target treatment temperature, feedback control is performed so that the temperature follows the target value of the temperature control. However, when the temperature reaches the target treatment temperature from a temperature rising state so that the target value becomes the target treatment temperature, the temperature overshoots the target treatment temperature. Patent Document 1 discloses that when the temperature reaches the target treatment temperature from a temperature rising state, the overshoot is suppressed by changing at least one of the proportional gain, differential gain, and integral gain of the PID control. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6365189 specification Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when the temperature reaches the target processing temperature from a rising state, a feedback method is used in which the gains are repeatedly changed and the amount of overshoot is checked while adjusting the gains to an appropriate level, which causes a delay in suppressing over-short circuits.

[0005] An object of the present invention is to prevent a delay in suppressing overshoot when the temperature reaches a target processing temperature from a temperature-rising state. [Means for solving the problem]

[0006] (1) In order to solve the above problem, the heat treatment control device of the present invention is a heat treatment control device that heats the atmosphere in a heat treatment chamber to a predetermined target treatment temperature, and heats the atmosphere toward the target treatment temperature for a predetermined time from the start of the temperature rise. Before the target treatment temperature is reached and after the predetermined time has elapsed, the temperature is controlled by a filter whose time constant changes over time so that the rate of temperature rise slows as the temperature approaches the target treatment temperature.

[0007] (2) The predetermined time is set according to the heat transfer characteristics of the heat treatment system.

[0008] (3) In order to solve the above problem, the heat treatment control program of the present invention is a heat treatment control program for raising the temperature of the atmosphere in a heat treatment chamber to a predetermined target treatment temperature, and causes a computer to execute a step of raising the temperature toward the target treatment temperature from the start of the temperature increase for a predetermined time, and, before the target treatment temperature is reached and after the predetermined time has elapsed, controlling the temperature by using a filter whose time constant changes over time so that the rate of temperature increase slows as the target treatment temperature is approached. [Effects of the Invention]

[0009] According to the present invention, it is possible to prevent a delay in suppressing overshoot when the temperature reaches the target processing temperature from a temperature rising state during heat treatment. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a configuration diagram of a heat treatment system. [Figure 2] FIG. 2 is a functional block diagram of a control device. [Figure 3] 4 is a time chart showing target values ​​of temperature control. [Figure 4] 10 is a flowchart showing a process for setting a target value for temperature control. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [System Configuration] 1 shows the overall configuration of a heat treatment system 1. The heat treatment system 1 includes a heat treatment chamber 10, a gas supply unit 20, and a control unit 30.

[0012] The heat treatment chamber 10 is equipped with a fan 11, a heater 12, and a temperature sensor 13. The gas supply device 20 is equipped with a gas tank 21, piping 22, and a valve 23. The control device 30 is electrically connected to the fan 11, the heater 12, the temperature sensor 13, and the valve 23. The workpiece 100 is made of steel and is placed in a case or a support table.

[0013] The electric motor of the fan 11 in the heat treatment chamber 10 is controlled by the control device 30, and the fan 11 agitates the atmosphere so that the atmosphere is uniformly distributed. The heater 12 is controlled by the control device 30 to heat the heat treatment chamber 10 to a predetermined target treatment temperature T ht The atmosphere is heated to the target processing temperature T ht After reaching the target processing temperature T ht The temperature sensor 13 outputs the detected temperature T of the atmosphere to the control device 30.

[0014] A gas tank 21 of the gas supply device 20 supplies atmospheric gas to the heat treatment chamber 10 via a pipe 22. The amount of gas supplied is adjusted by a valve 23. The atmospheric gas is appropriately discharged to the outside through an exhaust pipe 14 so as not to become excessive inside the heat treatment chamber 10.

[0015] [Heat treatment process] When the heat treatment is started, the controller 30 controls the atmosphere in the heat treatment chamber 10 to a predetermined target treatment temperature T ht The temperature is then raised to the target processing temperature T ht While the temperature control of the atmosphere is being performed, the control device 30 executes a process to set the target value T of the temperature T of the atmosphere. SV The atmosphere is heated to a predetermined target processing temperature T ht When controlling the temperature increase to t PUp to target processing temperature T ht The temperature is increased towards the target processing temperature T ht and before a predetermined time t P After the time t has elapsed, the target processing temperature T ht The closer to the target value T, the slower the temperature rise will be. SV Then, the atmosphere is heated to the target processing temperature T ht After reaching the target value T SV The target processing temperature T ht The control device 30 also sets the target value T SV and the temperature T of the atmosphere detected by the temperature sensor 13. The output command value of the heater 12 is set to control the output of the heater 12, thereby controlling the temperature T of the atmosphere in the heat treatment chamber 10.

[0016] [Buffering] 2 is a functional block diagram of the control device 30. FIG. SV 1 is a time chart showing the time when the temperature rise starts and the temperature of the temperature-controlling device 30 is increased by a predetermined time t. The control device 30 includes a temperature profile setting unit (heat pattern setting unit) 31, a correction time setting unit 32, a time constant generating unit 33, a corrected temperature profile generating unit (corrected heat pattern generating unit) 34, a target value setting unit 35, and a temperature control unit 36. The temperature profile setting unit 31, the correction time setting unit 32, the time constant generating unit 33, the corrected temperature profile generating unit 34, and the target value setting unit 35 are operated, and the control device 30 P Up to target processing temperature T ht The temperature is increased towards the target processing temperature T ht and before a predetermined time t P After the time t has elapsed, the target processing temperature T ht The closer to the target value T, the slower the temperature rise will be. SVThe control device 30 is configured as a computer, and includes a processor, memory, etc. as a hardware configuration, and a program for controlling the temperature T of the atmosphere in the heat treatment chamber 10 is stored in the memory, and the above-mentioned units (31 to 36) are realized by the processor executing the program.

[0017] The temperature profile setting unit 31 sets a target processing temperature T according to the heat treatment conditions of the workpiece 100. ht and its target processing temperature T ht The heating rate k when heating up to T and the ambient temperature T is set to the target processing temperature T. ht A constant heating rate k T Temperature profile (heat pattern) T pro In Figure 3, the temperature profile T pro is shown by a broken line. P Until the temperature profile T pro is the target value T SV 3. The temperature profile setting unit 31 calculates the temperature profile from the initial temperature T0 of the atmosphere in the heat treatment chamber 10 detected by the temperature sensor 13 when the heat treatment is started to the target treatment temperature T ht Heating rate up to k T Temperature profile T pro Set the target processing temperature T ht and temperature rise rate k T is stored in advance in the control device 30 as a table for each heat treatment condition of the workpiece 100, and the temperature profile setting unit 31 sets the target treatment temperature T ht and temperature rise rate k T and obtain the temperature profile T pro The temperature profile T pro When this is set, the temperature rise rate k T The target processing temperature T ht Temperature profile that rises to pro The temperature rise time t0 is also determined. Tis the temperature rise time t0 and the target processing temperature T ht and the initial temperature T0, k T =(T ht -T0) / t0.

[0018] The correction time setting unit 32 sets the temperature profile T pro Modified temperature profile (modified heat pattern) T corpro The correction time τ as a parameter for generating m Set the correction time τ m is the modified temperature profile T corpro To generate the temperature profile T pro The correction time τ is set as the time to be subtracted from the temperature rise time t0. m By setting the target processing temperature T SV The closer to the target value T, the slower the temperature rise. SV The timing at which the setting begins is a predetermined time t P is set. Note that the predetermined time t P is the temperature profile T pro From the temperature rise time t0 to the correction time τ m is set as the time subtracted from t P =t0-τ m The predetermined time t P is the time from the temperature rise time t0 to the correction time τ m Since it is set by subtracting pro is the target processing temperature T SV The timing is set before the target processing temperature T SV The target value T is set at a timing before it reaches SV The timing at which the setting begins is a predetermined time t P is set according to the heat transfer characteristics of the heat treatment system 1. Therefore, the predetermined time t P After the time has elapsed, the target value T SV The buffering process for setting the correction time τ is set according to the heat transfer characteristics of the heat treatment system 1. m are stored in advance in the control device 30 in the form of a table for each heat treatment condition of the workpiece 100, for example.

[0019] The corrected temperature profile generator 34 generates the temperature profile T pro From the temperature rise time t0 to the correction time τ m The predetermined time t obtained by subtracting P (t P =t0-τ m ) at the target processing temperature T ht A modified temperature profile T is generated by heating at a constant rate k up to corpro Therefore, the modified temperature profile T corpro The temperature rise rate k is k=(T ht -T0) / t P In addition, the corrected temperature profile T corpro is the target processing temperature T ht A predetermined time t P After that, the target processing temperature T ht In Figure 3, the modified temperature profile T corpro is shown by a dashed dotted line.

[0020] The time constant generating unit 33 generates the corrected temperature profile T corpro is filtered to obtain the target value T SV The time constant generating unit 33 generates a time constant τ of the filter when setting the correction time τ m The time constant τ that changes over time is generated using the ratio of the temperature rise time t0 to the temperature rise time t as a proportionality constant. Specifically, when the time t from the start of temperature rise is until the temperature rise time t0, the time constant generation unit 33 calculates the correction time τ m The ratio τ of the temperature rise time t0 m / t o The time constant generating unit 33 generates a time constant τ that changes with time t using a proportional constant of τ. When the time t is t0 or more, the time constant generating unit 33 sets the time constant τ to the corrected time τ m It is set as a fixed value. JPEG2025158338000002.jpg33165

[0021] The target value setting unit 35 determines whether the time constant τ is equal to or smaller than the correction time τ m The ratio τ of the temperature rise time t0 m / t oCorrected temperature profile T with a filter that varies proportionally with time t corpro The target value of temperature control T SV The target value setting unit 35 sets the corrected temperature profile T corpro The filter applied to is a first-order lag filter, and its transfer function F(s) is given by the following equation (2): In the following equation, s is the Laplace operator. JPEG2025158338000003.jpg25139 Also, corrected temperature profile T corpro is a given time t P is the temperature profile that rises at a temperature rise rate k, and its transfer function R(s) is given by the following equation (3). JPEG2025158338000004.jpg25147Therefore, at a given time t P Corrected temperature profile up to T corpro The target value T is obtained by processing the SV The transfer function G(s) is given by the following equation (4). JPEG2025158338000005.jpg27136

[0022] The target value T SV First, if the right-hand side of the above equation (4) is expressed as the following equation (5), A, B, and C in equation (5) can be expressed as the following equation (6). JPEG2025158338000006.jpg25158JPEG2025158338000007.jpg25158Therefore, the target value T SV The transfer function G(s) can be expressed by the following equation (7). JPEG2025158338000008.jpg26159By performing the inverse Laplace transform on the above equation (7), the given time t P Target value T SV The time function g(t) is obtained as shown in equation (8) below. JPEG2025158338000009.jpg25166

[0023] In Figure 3, the target value TSV The time chart is shown by a solid line. The target value T SV is the time constant τ, and the correction time τ m The ratio τ of the temperature rise time t0 m / t o Corrected temperature profile T with a filter that varies proportionally with time t corpro As a result, the target value T SV is the time t from the start of temperature rise to a predetermined time t P Until it reaches the target value T SV and the temperature profile T pro On the other hand, the target value substantially coincides with the predetermined time t P From now on, the target value T SV is a constant target processing temperature T ht The modified temperature profile T is set to corpro is set by processing it with a filter with a time constant τ, and the target processing temperature T ht The closer the temperature approaches the target value, the slower the rate of temperature rise is set. P From the timing of the temperature profile T pro The target value T is blunted relative to SV is set.

[0024] As described above, the target value setting unit 35 sets the target temperature at a predetermined time t P Up to target processing temperature T ht The temperature is increased towards the target processing temperature T ht and before a predetermined time t P After the time t has elapsed, the target processing temperature t is calculated by a filter whose time constant τ changes with time t. P The closer to the target value T, the slower the temperature rise. SV Therefore, during heat treatment, the temperature rises to a certain target treatment temperature T ht When the transition to P Temperature profile T pro and at a given time t P From the timing of the target processing temperature T ht The target value T smoothly transitions to SVThis allows the temperature to be increased from the elevated temperature to the target processing temperature T ht When the temperature T of the atmosphere in the heat treatment chamber 10 reaches the target treatment temperature T ht Therefore, it is possible to prevent a delay in suppressing overshoot.

[0025] The target value setting unit 35 uses a filter whose time constant τ changes with time t to adjust the corrected temperature profile T corpro The timing at which the filter is applied to the corrected temperature profile T does not have to be the timing at which the temperature rise starts, but may be any timing after the temperature rise starts. corpro The timing to start applying the P The timing is sufficient to reach the target processing temperature T ht before reaching a predetermined time t P After the time has elapsed, the filter will ht The closer to the target value T, the slower the temperature rise. SV Any timing is acceptable as long as it can be set.

[0026] Here, the target value T SV But at a given time t P Temperature profile T pro substantially coincides with the predetermined time t P After the temperature profile T pro The reason why the target value is blunted relative to the value of the reference value will be further explained below.

[0027] Corrected Temperature Profile T corpro is the time t from the start of temperature rise to a predetermined time t P The temperature is increased at a rate k until it reaches a predetermined time t P From this timing, the target processing temperature T ht Then, when time t is a predetermined time t P Until the target value T SV is expressed by the above-mentioned formula (8). Here, the time constant τ is determined by the above-mentioned formula (1), so the ratio t / τ of the time t to the time constant τ is the correction time τ of the temperature rise time t0. m Ratio t0 / τm That is, the relationship of the following equation (9) is established. JPEG2025158338000010.jpg28166

[0028] Correction time τ m is a predetermined time t that is set as a parameter that is adjusted according to the heat transfer characteristics of the heat treatment system 1. P is the time to identify the temperature profile T pro In order to substantially prevent a delay in following the temperature rise time t0, the correction time τ m is set to a value of several percent to 5% of the temperature rise time t0. m For example, when the temperature rise time t0 is set to 5%, the target value T SV From the relationship in equation (9), exp(-t / τ) in the first term of equation (10) below is a value that can be practically ignored. JPEG2025158338000011.jpg22167Therefore, the target value T expressed by the time function g(t) in equation (8) SV The first term of can be ignored.

[0029] Predetermined time t P Target value T SV The time function g(t) can be expressed using only the second term because the first term can be ignored, and the second term of g(t) can be expressed as shown in the following equation (11). JPEG2025158338000012.jpg46150Therefore, at a given time t P Target value T SV The time function g(t) of T Temperature profile T pro Then, at a predetermined time t P From the timing of the corrected temperature profile T corpro is a constant target processing temperature T ht The filter is applied to this. P From now on, the target processing temperature T htThe closer to the target value T, the slower the temperature rise. SV and the temperature profile T pro The target value T is blunted relative to SV is set. In this way, the target value T SV is a given time t P Temperature profile T pro and at a given time t P After the temperature profile T pro This is a blunted target value.

[0030] In addition, the predetermined time t P is the time from the temperature rise time t0 to the correction time τ m The temperature profile T pro The target value T is blunted relative to SV is set as the timing to start setting. P is set as a parameter that is adjusted according to the heat transfer characteristics of the heat treatment system 1. For example, in the heat treatment system 1, the predetermined time t P If the heat transfer coefficient is relatively high and heat is easily transferred, the correction time τ m is set to a relatively large value and for a given time t P Set the time to a short value and set the temperature profile T pro The target value T is blunted relative to SV The predetermined time t P Set the target processing temperature T ht If the heat transfer coefficient is relatively low and heat transfer is difficult, the correction time τ m is set to a relatively small value and the time t P Set the temperature profile T pro The target value T is blunted relative to SV The predetermined time t P is set close to the temperature rise time t0 and the target processing temperature T ht This allows for an early transition to

[0031] The temperature control unit 36 ​​sets the target value T SV Specifically, the temperature control unit 36 ​​controls the temperature T of the atmosphere in the heat treatment chamber 10 based on the target value T SV The output command value of the heater 12 is set according to the deviation between the target temperature T and the temperature T detected by the temperature sensor 13, and the output of the heater 12 is controlled. SV is controlled to follow the

[0032] Figure 4 shows the target temperature control value T SV 10 is a flowchart showing the process of the control device 30 for setting the target value T SV When setting the temperature profile T pro Next, in step S12, the corrected temperature profile generator 34 sets the temperature profile T pro From the temperature rise time t0 to the correction time τ m The predetermined time t obtained by subtracting P At the processing temperature T ht A modified temperature profile T corpro In step S13, the time constant generating unit 33 generates a correction time τ m The ratio τ of the temperature rise time t0 m / t o In step S14, a time constant τ is generated that changes with time t using a filter in which the time constant τ changes in proportion to time t. corpro The target value of temperature control T SV The control device 30 performs the process shown in FIG. P Up to target processing temperature T ht The temperature is increased towards the target processing temperature T ht and before a predetermined time t P After the time t has elapsed, the target processing temperature T ht The temperature control step is executed so that the rate of temperature rise slows as the temperature approaches .

[0033] [program] The program is configured as a program for executing the processes of steps S11 to S14. The program may be provided to a computer via a computer-readable storage medium or a network. The various processes of the program do not have to be configured on a single computer or medium, but may be distributed across multiple servers or computers that can send and receive data via network communication.

[0034] [Effects of this embodiment] According to this embodiment, the predetermined time t P From the timing of the target processing temperature T ht The target value T smoothly transitions to SV Since the temperature is controlled based on the ht This can prevent a delay in suppressing overshoot when the

[0035] Furthermore, according to this embodiment, the predetermined time t P is set as a parameter that is adjusted according to the heat transfer characteristics of the heat treatment system 1, and the temperature profile T pro The target value T is blunted relative to SV The timing to set is the predetermined time t P Therefore, the temperature profile T pro The target value T is blunted relative to SV The timing to set it will be appropriate.

[0036] [Variations] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

[0037] In the above embodiment, the target processing temperature T ht A constant heating rate k T Temperature profile T pro However, the temperature rise rate k T Changing the temperature profile Tpro may be set. [Industrial Applicability]

[0038] The present invention can be widely applied as a heat treatment control device and control program for raising the temperature of the atmosphere in a heat treatment chamber to a predetermined target treatment temperature. [Explanation of symbols]

[0039] 1 heat treatment system, 10 heat treatment chamber, 11 fan, 12 heater, 13 temperature sensor, 14 exhaust pipe, 20 gas supply device, 21 gas tank, 22 piping, 23 valve, 30 control device, 31 temperature profile setting unit, 32 correction time setting unit, 33 time constant generation unit, 34 corrected temperature profile generation unit, 35 target value setting unit, 36 temperature control unit, 100 workpiece

Claims

1. A heat treatment control device that heats the atmosphere in a heat treatment chamber to a predetermined target treatment temperature, A heat treatment control device that raises the temperature toward the target processing temperature for a predetermined time from the start of the temperature rise, and controls the temperature using a filter whose time constant changes over time so that the rate of temperature rise slows as the temperature approaches the target processing temperature, before the target processing temperature is reached and after the predetermined time has elapsed.

2. The temperature rise control device for heat treatment according to claim 1 , wherein the predetermined time is set in accordance with the heat transfer characteristics of the heat treatment system.

3. A control program for heat treatment that heats the atmosphere in a heat treatment chamber to a predetermined target treatment temperature, On the computer, A heat treatment control program that executes a step of raising the temperature toward the target treatment temperature for a predetermined time from the start of the temperature rise, and, before the target treatment temperature is reached and after the predetermined time has elapsed, controlling the temperature by using a filter whose time constant changes over time so that the rate of temperature rise slows as the target treatment temperature is approached.

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