JP2004246773A - Temperature control method for process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method controlling temperature with high accuracy by heating and cooling means in a manufacture process in an industrial or chemical plant. <P>SOLUTION: This method has the cooling means of two systems and the heating means of two systems each different in maximum heating quantity. When a temperature difference is large, PID control is executed by one of the means having large maximum heating quantity and large maximum cooling quantity. When the temperature difference reaches a preset temperature difference, the means is switched by a controller switch 22, and temperature control of a cylinder is executed by use of one of the means having small maximum heating quantity and small maximum cooling quantity as master control and the other as slave control, together. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a temperature control method for a process for precisely controlling temperature during heating and cooling processing in a manufacturing process that requires heating and cooling processing in an industrial or chemical plant.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, to perform temperature control in an industrial or chemical plant, a heating / cooling unit having a high maximum heating and maximum cooling capacity is used. For example, when a film is manufactured by an extruder, a large output is required at the beginning of the start of manufacturing in order to heat and melt a pellet-shaped plastic. That is, a heating unit having a large maximum heating amount is used to reach the target temperature in a short time. (See Patent Document 1)
[0003]
Further, some objects to be manufactured require heating and cooling. Also in this case, the target temperature is reached in a short time by using a cooling means having a large maximum cooling amount.
[0004]
[Patent Document 1]
JP-A-5-220806
[Problems to be solved by the invention]
However, when temperature control is performed using a single heating or cooling unit having a large maximum heating amount, there are the following problems.
[0006]
Each of the heating / cooling means having a large maximum heating amount or a maximum cooling amount is set at the initial stage of the production start, when the control value is changed with an extreme difference in the target value, and at the time of cooling. This is effective because the temperature can be reached in a short time. However, it is not possible to perform control for correcting the temperature for a minute temperature deviation due to the influence of disturbance in the manufacturing process. That is, even if the setting is changed from a large output to a small output immediately, there is a problem that the capability of the apparatus itself is limited, and the change cannot be immediately followed.
[0007]
The present invention has been made in view of such circumstances, and a main object of the present invention is to provide a temperature control method for a process capable of accurately controlling temperature by heating and cooling in a manufacturing process or the like.
[0008]
[Means for Solving the Problems]
[0009]
The present invention has the following configuration to achieve such an object.
That is, the invention according to claim 1 is a method for controlling a temperature of a process including a heating mechanism,
The heating mechanism is composed of a plurality of heating means having different maximum heating amounts, and when the actual deviation obtained from the target value and the actual measurement value of the temperature of the control target is larger than a predetermined target deviation, the maximum heating amount is large. The temperature control is performed by the heating means, and when the actually measured deviation is smaller than the target deviation, the temperature control is performed by the heating means having a small maximum heating amount.
[0010]
(Operation / Effect) According to the first aspect of the present invention, different heating means having different maximum heating amounts are used in accordance with the result obtained from the comparison between the actually measured deviation and the target deviation. As a result, the temperature of the process can be accurately controlled. For example, in order to cause the deviation between the target value and the measured value to be large and to reach the measured value to the target value in a short time, such as at the start of heating, a heating means having a large maximum heating amount is used. Can be raised to the vicinity of. In addition, when the measured value reaches the vicinity of the target value, by using the heating means having a small maximum heating amount, it is possible to perform stable temperature control while keeping the measured deviation near the target value small. . That is, in the vicinity of the target value, temperature control can be performed with high accuracy for a small deviation due to disturbance.
[0011]
According to a second aspect of the present invention, in the method for controlling a temperature of a process according to the first aspect,
The process further comprises a cooling mechanism,
The cooling mechanism is configured by a plurality of cooling units having different maximum cooling amounts, and when an actual deviation obtained from a target value and an actual measurement value of the temperature of the control target is larger than a predetermined target deviation, the cooling unit having a larger maximum cooling amount. The temperature control is performed by the means, and when the actually measured deviation is smaller than the target deviation, the temperature control is performed by the cooling means having a small maximum cooling amount.
[0012]
(Operation / Effect) According to the second aspect of the present invention, the cooling means having different maximum cooling amounts can be selectively used according to the result obtained from the comparison between the actually measured deviation and the target deviation. As a result, the temperature of the process can be accurately controlled. For example, when the deviation from the target value is large and the temperature is high, the temperature can be reduced to near the target value in a short time by using a cooling unit having a large maximum cooling amount. In addition, when the measured value reaches the vicinity of the target value, by using the cooling means having a small maximum cooling amount, it is possible to perform stable temperature control while keeping the measured deviation near the target value small. . That is, in the vicinity of the target value, temperature control can be performed with high accuracy for a small deviation due to disturbance.
[0013]
According to a third aspect of the present invention, in the method of controlling a temperature of the process according to the first or second aspect, a parameter used for controlling the target temperature is set for each of the heating and cooling means. Is what you do.
[0014]
According to the third aspect of the present invention, the temperature control of the process can be performed with higher accuracy by individually setting the control parameters of each heating means and each cooling means.
[0015]
According to a fourth aspect of the present invention, in the method of controlling a temperature of the process according to the second or third aspect, the heating and the cooling are simultaneously performed when the measured value is near a target value. It is assumed that.
[0016]
According to the fourth aspect of the present invention, when the measured value reaches the vicinity of the target value, heating and cooling are performed simultaneously to perform temperature control in a more stable state. Can be. For example, when the temperature of a cylinder is controlled by heating a heater and circulating cooling water as in an extruder, etc., particularly when cooling is performed, cooling is performed by utilizing latent heat when the cooling water evaporates. It is effective to do. In this case, since the cooling capacity is high, the temperature of the cylinder may be immediately lowered to a low temperature simultaneously with the start of cooling.
[0017]
Therefore, when the cooling effect is remarkable, the temperature is controlled by heating in a stable state by performing the cooling while performing the heater heating with a small output. As a result, near the target value, stable temperature control can be performed while maintaining a small deviation.
[0018]
According to a fifth aspect of the present invention, there is provided the process temperature control method according to any one of the first to fourth aspects, wherein the process temperature control method is used for an extruder. is there.
[0019]
According to the fifth aspect of the present invention, the method according to any one of the first to fourth aspects is applied to an extruder, so that a small temperature deviation due to disturbance in a film manufacturing process. Temperature control can be accurately performed in a stable state, and the required deviation between the target value and the actually measured value can be set small to perform the temperature control.
[0020]
The present invention also discloses the following solution.
(1) In a temperature control method of a process having a heating / cooling mechanism,
A temperature control method for a process, wherein the setting of each control output at that time can be changed in the process of simultaneously performing heating and cooling.
[0021]
In the temperature control of a process that requires heating and cooling, for example, in order to heat a controlled object to reach a target temperature at the initial stage, it is necessary to increase the heating output and actively heat. Also, in the case of cooling, it is necessary to similarly actively cool.
However, there are the following problems when the measured value approaches the target value (temperature) or when switching from heating to temperature control by cooling.
＄
That is, when switching from heating to cooling in the vicinity of the target value, when using a cooling means having a high cooling capacity, for example, when using latent heat when the cooling water evaporates due to cooling water circulation, the current temperature is immediately changed. May drop to low temperatures. That is, there is a problem in that the hunting is caused to occur by lowering the target value beyond the target value.
[0023]
According to the invention described in the above (1), the temperature control in the vicinity of the target value can be more accurately performed by changing the setting of each control output in the process of simultaneously performing the heating and the cooling. In other words, when switching from heating to temperature control by cooling, when using a cooling unit having a high cooling capacity, hunting due to cooling is suppressed by changing the setting of the heating output according to the cooling output and controlling the temperature. can do.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
In the case of the present embodiment, a case where the resin temperature during film production in an extruder for producing a film is adjusted by controlling the temperature of a cylinder will be described as an example.
FIG. 1 is a side view showing a schematic configuration of an extruder, and FIG. 2 is a block diagram showing a schematic configuration of a cylinder and its surroundings.
[0025]
The extruder 1 used in the present embodiment includes a hopper 3 that supplies a material 2 such as a pellet-shaped plastic, a transport unit 5 that transports the material 2 while frictionally shearing the material 2 with an internal screw 4, and a material 2 in the transport unit. And a die 7 that coats the surface of a cooling roll 8 that cools and hardens the material 2 melted in the transport unit.
[0026]
The material 2 applied to a roll from the extruder 1 and formed into a film is subjected to a thickness adjustment roll 9, a group of transport rolls r, and a surface treatment unit that performs a surface treatment (for example, a corona treatment) of the filmed material 2. The paper is conveyed in the order of 10 and wound up and collected on a turret 11 which is a collection unit. Hereinafter, the configuration of each unit will be specifically described.
[0027]
A plurality of cylinders 6 (for example, five in FIG. 1) are provided at substantially equal intervals from the base end to the front end of the transport unit 5. Each cylinder is provided with a heater (heating means) and a pipe (not shown) capable of circulating cooling water as cooling means. Further, as shown in FIG. 2, a PID controller 200 for transmitting various output signals for adjusting the heating means and the cooling means is provided. The PID controller 200 shown in FIG. 2 is used for both heating and cooling for convenience of description. This PID controller 200 will be described later.
[0028]
The heating unit controls the heating temperature by operating the heater 12, a power controller 13 that supplies power to supply power to the heater 12, and an amount of power supplied to the heater 12 (on / off timing). And a semiconductor relay 14 (SSR: Solid State Relay).
[0029]
The power controller 13 is configured so that the heater 12 can output a different maximum heating amount. Specifically, as shown in FIG. 2, two power adjusting resistors R1 and R2 having different resistance values are combined in parallel with the resistance switching relays 15a and 15b.
[0030]
Each of the resistance switching relays 15a and 15b is connected to the PID controller 200, and one of the sides is turned on in response to a signal from the PID controller 200. For example, when the resistor R1 is turned on when the relationship between the resistance values is R1 <R2, a large power is supplied to the heater 12, and when the resistor R2 is turned on, a small power is supplied to the heater 12. . Therefore, two types of heaters having different maximum heating amounts can be configured.
[0031]
The cooling means includes a cooling unit 16 serving as a cooling water supply source, a main electromagnetic valve 17 for switching on / off of the cooling water supply, and a different amount of cooling water when the electromagnetic valve 17 is turned on. It comprises a first system comprising a first solenoid valve 18 and a first manual valve 19 and a second system comprising a second solenoid valve 20 and a second manual valve 21 so as to circulate through a pipe provided in the cylinder. I have.
[0032]
That is, the first system is set to a state where the opening degree of the first manual valve 19 is increased in advance. The second manual valve 21 on the second system side is set to be smaller than the opening degree of the first manual valve 19 on the first system side. Therefore, the amount of cooling water supplied to the cylinder 6 is different, and two systems of cooling means having different maximum cooling amounts are configured. The switching of the supply of the cooling water to the two systems is performed by turning on the solenoid valve 17, turning on one of the first or second solenoid valves 18 and 20, and turning off the other by a signal transmitted from the PID controller 200. It is done by.
[0033]
The degree of opening of the first and second manual valves 19 and 21 is determined in a timely manner by an experiment conducted in advance.
[0034]
Each of the cylinders 6 shown in FIG. 1 is individually provided with the above-mentioned heating and cooling means, and is configured so that the temperature can be controlled independently for each cylinder 6.
[0035]
Returning to FIG. 1, as the roll 9 for adjusting the thickness of the coating material, for example, a roll made of metal or rubber is appropriately used. The cooling roll 8 is configured so that cooling water circulates inside the roll. In other words, the molten material 2 is cooled and hardened in the process of being uniformly stretched on the roll.
[0036]
Next, a method of controlling the temperature of the process, which is a feature of the present embodiment, will be described with reference to FIGS.
[0037]
As shown in FIG. 3, the target deviations eh and el on the high temperature and low temperature sides with respect to the target value SV of the temperature of each cylinder 6 obtained in advance through experiments or the like are set and input to the controller switch 22. With the start of film production, the temperature of the cylinder 6 is sequentially measured by a temperature sensor or the like. The deviation between the actually measured value PV and the target value SV is input to the controller switch 22. Note that the target deviations eh and el may be set to individual values on the high temperature side and the low temperature side, or threshold values may be set.
[0038]
Here, a case will be described in which the controller switching unit 22 selects switching to the heating PID controller side (e> 0) and mainly performs temperature control by heating.
[0039]
First, the controller switch 22 inputs e, which is the difference between the target value SV and the actually measured value PV, and switches and selects the heating PID controller when e> 0 is determined. At the same time as selecting the heating PID controller side, the actually measured deviation e is compared with the target deviation el, and when the actually measured deviation e satisfies the relationship el <e, the control is switched to the first heating PID controller 23. On the other hand, when the actual deviation e is in the relationship of the target deviation el ≧ e, the switching to the second heating PID controller 25 is performed.
[0040]
That is, when the measured deviation e is larger than the target deviation el, the heating means having the larger maximum heating amount is selected to be controlled by the PID control, and when the measured deviation e is smaller than the target deviation el, the heating means having the smaller maximum heating amount is selected as the PID control. Switch and select timely to control.
[0041]
Specifically, when the deviation has a relationship of el <e, the controller switch 22 selects the first heating PID controller 23 and the first cooling PID controller 27.
[0042]
As shown in FIG. 4, each of the first heating and first cooling PID controllers 23 and 27 includes an arithmetic processing unit 32 for obtaining a PID control output and the like, and a memory 33 for storing the obtained PID control output. I have.
[0043]
In the arithmetic processing unit 32 in the first heating and first cooling PID controllers 23 and 27, first, the proportional output MVp is calculated from the following equation (1) using the actual deviation e which is the difference between the target value SV and the actual measured value PV. Then, the integral output MVi is obtained from the following equation (2), and the differential output MVd is obtained from the following equation (3). As shown in the following equation (4), the control output MV is obtained from the sum of these.
[0044]
MVp = 100 / PB × e (1)
MVi = 100 / PB (1 / Ti × ∫edt) (2)
MVd = 100 / PB (Td × de / dt) (3)
MV = MVp + MVi + MVd (4)
[0045]
Here, PB indicates a proportional band, Ti indicates an integration time, and Td indicates a differentiation time.
[0046]
The temperature of the cylinder 6 is controlled based on the obtained control output MV. In this case, since the deviation obtained by actual measurement is large and temperature control by rapid heating is mainly performed, the control output MV obtained from the first cooling PID controller is set to zero.
[0047]
That is, in the cylinder temperature control process 31, the signal and the control output from the first heating PID controller 23 turn on the resistance switching relay 15 a that outputs the large electric power shown in FIG. 2 and turn on and off the SSR 14. Is operated to change the amount of power supplied from the power controller 13 to control the temperature of the cylinder 6 while adjusting the amount of heating of the heater 12.
[0048]
If the relationship between the actually measured deviation e and the target deviation el satisfies the relationship el ≧ e in the process of performing the temperature control with the heating means having the large maximum heating amount, the controller switch 22 controls the side with the small maximum heating amount. The 2nd heating PID control controller 25 is selected, and the second cooling controller 29 that controls the side with the smaller maximum cooling amount is selected. In this case, PID control parameters are set so that temperature control can be performed at the same time near the target value with heating as main control and cooling as sub-control.
[0049]
That is, the second heating and second cooling PID controllers 25 and 29 also include, as shown in FIG. 4, an arithmetic processing unit 32 for obtaining a PID control output and the like, and a memory 33 for storing the obtained PID control output. ing.
[0050]
Therefore, each of the arithmetic processing units of the second heating and cooling PID controllers 25 and 29 determines an output relationship when heating and cooling are simultaneously performed. Specifically, as shown in FIG. 5, when the actually measured value PV reaches the target value SV, an output region where the heating control output MVh and the cooling control output MVc can be simultaneously output is determined. At this time, the a value on the heating control output side and the b value on the cooling control output side are values obtained in advance by experiments and the like, and can be arbitrarily changed. The control outputs MVh and MVc at this time are obtained by the following equations (5) and (6).
[0051]
MVh = (MV + a) × 100 / (100 + a) (5)
MVc = −1 × {(MV + b) × 100 / (100 + b)} (6)
[0052]
The obtained control output MVh on the heating side is input to the second heater heating temperature control process 26. Then, in the cylinder temperature control process 31, the resistance switching relay 15b on the side outputting the small electric power shown in FIG. 2 is turned on and the SSR 14 is turned on / off by the signal and the control output from the second heating PID controller 25. Is controlled to change the amount of power supplied from the power controller 13 to control the temperature of the cylinder 6 while adjusting the maximum heating amount of the heater 12.
[0053]
At the same time, the second chiller cooling temperature control process 30 turns on the solenoid valve 17 and turns on the second solenoid valve 20 having a small maximum cooling amount according to a signal from the second cooling PID controller 29, Is fully opened to control the temperature of the cylinder 6 while adjusting the timing of supplying and circulating the cooling water into the cylinder.
[0054]
Therefore, in the vicinity of the target value SV, temperature control by heating and cooling is simultaneously performed, and it is possible to suppress hunting near the target value SV due to the extreme action of cooling or heating, and a small deviation due to disturbance. Temperature control can be performed stably.
[0055]
In the above embodiment, from the time when the target deviation e is reached, the temperature control of the cylinder 6 is performed with the heating as the main control and the cooling as the sub-control. However, the cooling is set as the main control, and the heating as the sub-control. Temperature control may be performed.
[0056]
As described above, since the temperature of the cylinder 6 is controlled based on individual PID control parameters for each of the heating means and the cooling means having different maximum heating amounts and maximum cooling amounts, highly accurate temperature control can be performed. Become. That is, when heating is required rapidly, the heater 12 is set to have a large maximum heating amount, so that the actually measured value PV can reach the target value SV in a short time. Further, at the time when the actually measured deviation e reaches the target deviation el and in the vicinity of the target value SV, the heater 12 is set to have a small heating amount, and the cylinder 6 is set to have a small maximum cooling amount. By controlling the temperature of the cylinder 6 by setting the supply of the cooling water and simultaneously operating the heating and the cooling, it is possible to perform the temperature control corresponding to the small deviation due to the disturbance.
[0057]
When a film was manufactured by the extruder 1 using the temperature control method of the above-described process, the following results were obtained.
[0058]
In the conventional apparatus in which the PID control is performed using a single heating means having a large maximum heating amount, the required value of the deviation between the target value and the actually measured value of the cylinder 6 can be managed only up to 4 ° C at the maximum. In the apparatus, it was confirmed that the required value of the deviation was set to 1 ° C. or less to enable the production of a film. Therefore, a high-quality film can be manufactured.
[0059]
The present invention is not limited to the above-described embodiment, but can be modified as follows.
[0060]
(1) In the apparatus of the above-described embodiment, as shown in FIG. 5, both the heating side and the cooling side are provided with PID controllers for each two systems according to the temperature deviation. However, as shown in FIG. The two systems, one on the cooling side and the other on the cooling side, may be configured so that the same PID controllers 40 and 41 can perform PID control. In this case, each of the PID controllers 40 and 41 may be configured to be able to set a PID control parameter for each of the maximum heating and cooling capacities and to control them individually.
[0061]
(2) In the apparatus of the above embodiment, each of heating and cooling was provided in two systems, but may be provided in two or more systems. By using two or more systems, the width of the temperature deviation can be finely divided and the temperature can be controlled according to each deviation, so that more accurate temperature control can be performed.
[0062]
(3) In the above-described apparatus, the temperature of the cylinder 6 is controlled using one pattern of PID control parameters that can simultaneously perform heating and cooling near the target value. However, each PID controller has two patterns of PID control parameters. May be used.
[0063]
For example, when rapid heating is required, such as at the start of manufacturing, or when rapid cooling is required before the end of manufacturing, as shown in FIG. 7, a PID having a large output of the heating control output MVh and the cooling control output MVc is used. After reaching a preset target deviation e using the control parameters, the cylinder 6 using the PID control parameters for simultaneous heating and cooling shown in FIG. Temperature control may be performed.
[0064]
(4) In the above-described embodiment, the control output MV of the first cooling PID controller 27 is set to zero until the actually measured deviation e reaches the target deviation el. The temperature may be controlled so that fine adjustment of the temperature is performed while cooling the substrate.
[0065]
【The invention's effect】
As is clear from the above description, according to the present invention, by using different heating means having a maximum heating amount according to a predetermined target deviation with respect to a target temperature, the process temperature control can be performed in a stable state throughout. It can be carried out. That is, in the manufacturing process, by using a heating means having a large maximum heating amount at the start of the manufacturing process, it is possible to reach the predetermined target temperature in a short time. Further, by using a heating means having a small maximum heating amount from a predetermined target deviation or less, it is possible to perform fine temperature adjustment for a small deviation due to disturbance. Therefore, it is possible to cope with a small temperature deviation due to disturbance, as compared with the case where the temperature is controlled using a single heating unit having a large maximum heating amount as in the related art, so that it is possible to manufacture a product with strict temperature control.
[Brief description of the drawings]
FIG. 1 is a side view showing a schematic configuration of an extruder used in an embodiment and its periphery.
FIG. 2 is a block diagram illustrating a configuration of a cylinder.
FIG. 3 is a block diagram showing a control process of a cylinder.
FIG. 4 is a block diagram showing an internal configuration of each PID controller.
FIG. 5 is a diagram showing a relationship between a heating control output and a cooling control output in a temperature control process.
FIG. 6 is a block diagram showing a modified example of the cylinder control process.
FIG. 7 is a diagram illustrating a relationship between a heating control output and a cooling control output in a temperature control process according to a modification.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Extruder 6 ... Cylinder 12 ... Heater 13 ... Power controller 14 ... SSR
15a, b: Resistance switching relay 16: Cooling units 17, 18, 20: Solenoid valves 19, 21: Manual valves R1, R2: Resistors

Claims (5)

In a temperature control method of a process having a heating mechanism,
The heating mechanism is composed of a plurality of heating means having different maximum heating amounts, and when the actual deviation obtained from the target value and the actual measurement value of the temperature of the control target is larger than a predetermined target deviation, the maximum heating amount is large. A temperature control method for a process, wherein temperature control is performed by a heating unit, and when the actually measured deviation is smaller than a target deviation, the temperature control is performed by a heating unit having a small maximum heating amount. The method for controlling a temperature of a process according to claim 1,
The process further comprises a cooling mechanism,
The cooling mechanism is configured by a plurality of cooling units having different maximum cooling amounts, and when an actual deviation obtained from a target value and an actual measurement value of the temperature of the control target is larger than a predetermined target deviation, the cooling unit having a larger maximum cooling amount. A method for controlling a temperature of a process, wherein temperature control is performed by a means, and when the actually measured deviation is smaller than the target deviation, the temperature is controlled by a cooling means having a small maximum cooling amount. A method for controlling a temperature of a process according to claim 1 or 2,
A temperature control method for a process, wherein a parameter used for controlling the target temperature is set for each of the heating and cooling means. The method of controlling a temperature of a process according to claim 2 or claim 3,
A method for controlling the temperature of a process, wherein heating and cooling are performed simultaneously when the measured value is close to a target value. The temperature control method for a process according to any one of claims 1 to 4,
A process temperature control method, wherein the process temperature control method is used for an extruder.

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