JPH0675907B2 - Film thickness control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic die lip control device applied to an extrusion and casting apparatus such as a film or sheet manufacturing apparatus.

[Conventional technology]

In an extrusion molding or casting apparatus for producing a sheet or film, it is necessary to produce a product in which the thickness of the sheet or film as a molded product is kept at a predetermined value. For example, an example of a conventional apparatus having a die having an adjusting mechanism capable of adjusting the film thickness in the film width direction will be described with reference to FIGS. 6 to 9.

The resin melted by the extruder 1 (FIG. 6) is sent to the die 2. In the manifold 3, the molten resin is spread in the width direction perpendicular to the drawing of FIG. 6 of the die 2, hangs down from the discharge port 5 of the slot of the die lip 4, cooled by the cooling roller 6, and solidified to form the film 7. It is wound up by the winder 10. As a thickness adjusting mechanism, in order to change the discharge amount of the resin along the longitudinal direction of the slot of the die lip 4, as shown in FIG.
Are distributed. The heater 12 is embedded in the die lip 4, and by changing the heat generated by the heater, it is possible to change the resin discharge amount by changing the viscosity of the resin at that location and changing the flow velocity. Therefore, the thickness of the film 7 can be automatically controlled by changing the heat generated by the heater 12. By the way, the amount of resin discharged at a certain location along the width direction of the die lip 4 is substantially proportional to the temperature of the die lip itself at that location. Therefore, if the temperature of the die lip 4 at a certain portion is raised, the amount of resin discharged at that portion is increased and the film thickness at that portion is increased. From this, by controlling the temperature of the die lip 4,
The thickness of the film 7 can be set to a predetermined profile. That is, the thickness of the film 7 is controlled by the die lip 4
Can be replaced with temperature control. Fig. 8 shows the heating value of all heaters from 13W to 6.5W along the die lip width direction.
(1) Surface temperature of the discharge port 5 of the die lip 4 (temperature of the thermometer 11 at the position shown by X in FIG. 6) (8)
(A)), (2) resin discharge amount of the entire die lip ((b) in the figure) and (3) simulation results showing changes in film thickness over time ((c) in the figure). ) For the middle die lip surface temperature, the experimental results are also shown.The figure also shows the result of the dynamic heat-fluid analysis inside the die lip. It can be seen that the film thickness decreases and the film thickness decreases accordingly, which confirms that the die lip temperature and the film thickness have a substantially proportional relationship.
Film thickness control can be replaced by die lip temperature control. FIG. 9 shows a block diagram of die lip temperature control for one operating end of the plurality of heaters 12.
The temperature of a thermometer at a certain position measured by a plurality of thermometers 11 (Fig. 6) attached to the surface of the discharge port 5 of the die lip 4 along the longitudinal direction of the discharge port at a position corresponding to each heater. The difference between the (die lip temperature) and its set value is input to the controller 13. The controller 13 calculates and outputs the required amount of heat generated by the plurality of heaters 12 corresponding to the location measured by the thermometer 11. When the heat generated by the heater 12 changes, the temperature of the die lip 4 changes, the discharge amount in the die lip 4 changes, and the film thickness of the portion of the heater 12 where the heat generated changes is changed, so that the thickness can be controlled. The thickness control over the entire film width can be performed by preparing the die lip temperature control loop shown in FIG. 9 by the number of locations where the die lip temperature control is performed. At this time, needless to say, many thermometers 11 are installed along the width direction of the die lip.

[Problems to be solved by the invention]

The above-mentioned conventional die lip temperature control system (Fig. 9) is not yet capable of sufficiently satisfactory control. It's a heater
This is because there is an interference phenomenon in which the die lip temperature of a portion corresponding to an adjacent heater is changed when the operation end of a certain portion of 12 is operated. That is, the operating end of the heater 12 shown in FIG. 9 and the control loop for controlling the die lip temperature corresponding to the heater position interfere with each other. As a result, the following problems occurred.

(1) Even if the stability of the control loop shown in FIG. 9 is assured, the operation of a certain operating end or heater 12 may affect the control loop that controls the die lip temperature corresponding to the adjacent heater. Therefore, the interference between the control loops occurs, and the stability of the entire control system cannot be guaranteed when the die lip temperature is applied over the entire width of the film. Therefore, the gain of the controller 13 is reduced so that the influence of mutual interference does not occur, resulting in a control system with poor quick response.

(2) Conversely, considering the design of a stable control system as a multivariable system that takes into consideration the mutual interference between the operating ends of the heater 12, normally 100 or more operating ends of the heater 12 are arranged in the die lip width direction. Since the detected value of the die lip temperature is equal to the number of operating ends, it is a very large control system. Therefore, it is difficult to design with stability guaranteed in such a large system.

[Means for solving problems]

 The present invention takes the following means to solve the above problems.

That is, as a molten resin discharge amount adjusting mechanism, a plurality of heaters has a die arranged along the longitudinal direction of the slot of the die, and at a position corresponding to the heater on the surface near the discharge port of the slot of the die. In an extrusion molding apparatus or a casting molding apparatus having a plurality of thermometers arranged, a plurality of samplers to which the output of each thermometer is input, a distributor to which each output of the sampler is input, and the same distribution The output of each basic control system calculation value memory and the plurality of basic control system calculation value memories to which the output of each basic control system is input respectively A film comprising: a superposition adder to be input, and a heater generated heat command value memory to which the output of the superposition adder is input and whose own output is feedback-connected to each of the basic control systems. Only control device.

[Action]

In the above structure, each thermometer measures the temperature of the discharge port of the die slot corresponding to each position of the heater. In the distributor, the detection data of the die lip temperature profile is input through the sampler from each of the thermometers at certain time intervals. Next, each basic controller inputs the required number of die lip temperature data sets from the distributor and the generated heat command value to each heater determined by the previous control calculation from the heater generated heat command value memory described later. Then, the heater generated heat calculation value for a predetermined number of heaters is output. Each basic control system calculation value memory inputs and stores the heater generated heat calculation value for a predetermined number of heaters obtained by the above basic control system. Next, the superposition adder adds the calculated values from the above-mentioned basic control system calculated value memories for each heater to determine the heater generated heat command value for each heater. The heater generated heat command value memory stores the heater generated heat command value for each heater of the superposition adder until the next control calculation.

The above operation is performed for the following time series temperature data.

In this way, each basic control system can control the die lip temperature of the part corresponding to each heater belonging to the system to a predetermined value, and the die lip temperature over the entire longitudinal direction of the die slot, that is, the thickness over the entire width of the film is controlled. It can be controlled stably.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. In order to avoid redundancy, detailed description of the conventional device will be omitted, and description will be made mainly regarding the present invention.

As shown in FIGS. 6 and 7, the extrusion molding apparatus includes a heater 12 which is a plurality of operation ends as a molten resin discharge amount adjusting mechanism.
Is disposed along the longitudinal direction of the die slot, and a thermometer (the surface temperature of the die is near the surface of the ejection port 5 at the downstream position corresponding to the heater 12 along the longitudinal direction of the ejection port 5 of the slot. A die 4 on which a total of 11 are disposed. In order to control these heaters 12, a film thickness control device composed of the following means (FIG. 1) is provided. The output of each thermometer 11 is connected to each sampler 100. The output of each sampler 100 is connected to the distributor 101. The output of the distributor 101 is a plurality of basic control systems 102-i (i = 1 to N).
Respectively connected to. The outputs of the basic control system 102-i are in one-to-one correspondence with the basic control system calculation value memory 103-.
connected to i. The output of the basic control system calculated value memory 103-i is connected to the superposition adder 104. The output of the superposition adder 104 is connected to a command value memory 105 of the heat generated by the heater, and the output of the command value memory 105 of the heat generated by the heater is feedback-connected to each basic control system.

In order to make the explanation easy to understand, the idea that led to the above-described embodiment is first described below.

(1) Although the operation of one operation end of the heater 12 changes the die lip temperature at the location corresponding to the adjacent heater, the interference range is limited, so the operation affects the die lip temperature distribution centering on a certain heater. Consider a control system including an operating end disposed within the range. This control system is a control system that can control the die lip temperature only at a portion corresponding to the heater selected at the center to a predetermined value. In other words, this control system determines the die lip temperature at the location corresponding to a certain heater.
The control system tries to maintain a predetermined value by changing not only the heater but also the amount of heat generated by an adjacent heater.
Since this control system has a small number of heaters and considers interference with the die lip temperature between the heaters, the following is possible.

(A) Since the number of heaters is small, the stability of the control system can be guaranteed, and the control system with good quick response can be designed.

(B) It is possible to design a disturbance-compensated control system that can always control the die lip temperature at a location corresponding to the central heater to a predetermined value even when disturbance occurs in the central heater as well as the adjacent heater.

(C) Since it is a control target that takes into consideration the interference between the heaters and the die lip temperature, the generated heat quantity distribution including the adjacent heaters is effective in changing the die lip temperature at the location corresponding to the central heater. It is possible to design a control system that operates.

A control system with the above features and a small number of heaters is called a "basic control system".

(2) The above "basic control system" is applied to each operating end of the heater 12 in order to stably and quickly control the die lip temperature over the entire film width. At this time, the stability of the die lip temperature control over the entire film width is guaranteed from the following. In the basic control system i'for a certain heater i, it is guaranteed that the die lip temperature of the portion corresponding to the heater is stably controlled to a predetermined value even if disturbance is applied to the adjacent heater. Next, the basic control system (i +
When 1) 'is applied, it is guaranteed that the die lip temperature of the portion corresponding to the heater i + 1 is stably controlled to a predetermined value. However, for the basic control system i ′ applied to the heater i, the generated heat quantity command in the basic control system (i + 1) ′ applied to the heater i + 1 can be regarded as a disturbance applied to the heater i of the basic control system i ′. it can. By the way, as described in (b) above, in the basic control system, even if a disturbance is applied to the heater, the die lip temperature in the portion corresponding to the heater to which the basic control system is applied is stably compensated for the disturbance. Therefore, it is understood that the die lip temperature of the portion corresponding to the heater i can be stably controlled even if another basic control system is applied to the heater i + 1.

In order to specifically describe the present invention, first, as a basic control system, as shown in FIG. 2, five sets of heaters h1 to h5 among a plurality of heaters 12 arranged in the longitudinal direction of the slot of the die lip.
Consider a system consisting of h5 and die lip temperatures t1 to t5 corresponding to each heater. The basic control system is a die lip thermometer at the location corresponding to the central heater h3 even if disturbance heat enters the heaters h1 to h5.
It is a control system that can control the temperature of t3 to a predetermined value. In addition to the central heater h3 in the basic control system, there are two heaters h1 and h on both sides.
2 and the heaters h4 and h5 are considered because there is interference that the heat generated by the heater h3 affects the temperatures of the die lip thermometers t1 and t2 and the die lip thermometers t4 and t5, and the die lip thermometer t1 and the die lip thermometer t5. The effect on the die lip temperature outside the temperature of is a negligible result. Therefore, the basic control system has an operating end composed of five heaters. On the other hand, the temperatures y ₁ (t) to y ₅ (t) of the die lip thermometers t1 to t5 at locations corresponding to the heaters h1 to h5 in order to enable effective heater generated heat distribution in consideration of interference between the operating ends.
Use the detection value (abbreviated as y _{1 to} y ₅ ). Therefore, the controlled object for designing the basic control system is represented by the following transfer function matrix G _(s) .

Where u _{1 (s) to} u _{5 (s)} : Heat generated by heaters h _{1 to} h ₅ u _{1
(T) to} u _{5 (t)} Laplace transformed y _{1 (s)} to y _{5 (s)} : Laplacing die lip temperatures y _{1 (t) to} y _{5 (t)} at locations corresponding to heaters h1 to h5 Transformed g _{1 (s)} to g _{3 (s)} : Transfer functions for each input and output.

g _{1 (s)} is, for example, the temperature y ₃ when only the heater h3 is changed.
Is a transfer function that gives the time change of. g _{2 (s)} is a heater
This is a transfer function that gives the time change of the temperature y ₃ when only h2 or the heater h4 is changed. g _{3 (s)} is heater h1 or heater
This is a transfer function that gives the time change of temperature y ₃ when only h5 is changed. The asymmetric peak of the transfer function matrix G _(s ) in equation (1) represents the interference of the adjacent heater with the die lip temperature.
The input u _{i (s)} and the output y _{i (s} ) of the equation (1) (i = 1 to 1 ₎
The following equation of state, which is convenient for control system design, is used to express the relationship between 5).

x (t) = Ax (t) + Bu (t) (2) y (t) = Cx (t) (3) x is a state vector, u is an input vector, u (t) = [u _1
(T) , u _{2 (t)} , u _{3 (t)} , u _{4 (t)} , u _{5 (t)} ] ^T (T
Represents transposition). y is an output vector, and y _(t) = [y _1
(T) , y _{2 (t)} , y _{3 (t)} , y _{4 (t)} , y ₅ (t)] ^T. Equations (2) and (3) are controllable and observable. From equations (2) and (3), input u _(t) and output y _(t)
The relationship of is shown in FIG. The double line in FIG. 3 shows the vector quantity. The configuration of the basic control system satisfying the following conditions is as shown in FIG. The double line in FIG. 4 indicates the vector quantity.

(1) die lip temperature y _3, even if disturbance heat enters the heater h1~h5 is quick response well-controlled to a predetermined value.

(2) to control the die lip temperature y _3, the heater h1~
The change in heat value of h5 is an effective distribution.

The structure and operation of the basic control system shown in FIG. 4 will be described below.

(1) discrete time t = newly in tk ₊₁ die lip temperature detection values _{y (tk +1) ≡y (s} +1) (y 1 (k +1), y 2 (k +1), y 3 ₍ k ₊₁₎ , y
_A vector consisting of _{4 (} k ₊₁₎ , yk ₍ k ₊₁₎ ) is obtained through the thermometer 20 and the sampler 21.

(2) Of the detected die lip temperature y ₍ k ₊₁₎ , y _{3 (} k ₊₁₎
There are input to the subtracter 22, the subtracter 22 is a die lip temperature setpoint r _{3 (k +1)} Temperature deviation between _{ε (k +1) = r 3} (k +1) -y 3 a _{(k +1)} Output.

(3) The integrator 23 uses the temperature deviation ε (k +
1) is input and the time integral value of the temperature deviation is output from the following equation.

x _I (k + 1) = x (k) +0.5 (tk _{+ 1-} tk) {ε (k) +
ε (k + 1)} (4) where ε (k): the previous die lip temperature was detected (time t =
tk) temperature deviation X _I (k): Output of integrator 23 at time t = tk The integrator 23 always compensates for disturbance heat that fluctuates the die lip temperature y ₃ with the heat generated by the heater, and always maintains the die lip temperature y ₃ Plays the role of a disturbance compensator that ensures that is equal to the set value.

(4) Heater generated heat u ₍ k ₎ calculated at time t = tk and die lip temperature detection value y ₍ k _{+ 1)} are input to the observer 24, and the state estimation value at time tk _{+ 1} is obtained. Is output.

(5) Output of integrator 23 x _{I (} k _{+ 1)} and output of observer 24 Is input to the heater generation heat controller 25, and the heater generation heat command value u ₍ k _{+ 1)} is output.

Next, the procedure for applying the basic control system will be described with reference to FIG.

FIG. 5 (a) shows that the basic control system (1) is applied to control the die lip temperature y ₃ to a predetermined value. Basic control system (1) is die lip temperature y ₁ ~y ₅ the detected die lip temperature y ₁ ~y heat generated command value corresponding heater ₅ u ₁ by ⁽¹⁾ ~u
₅ ⁽¹⁾ is defined. FIG. 3B shows that the basic control system (2) is applied to control the die lip temperature y ₄ to a predetermined value. Basic control system (2) defines a die lip temperature y ₂ ~y ₆ detect and die lip temperature y ₂ ~y heat generated command value corresponding heater ₆ u ₂ ⁽²⁾ ~u ₆ ^(2). The figure (c) shows a basic control system (3) for controlling the die lip temperature y ₅ to a predetermined value.
Indicates that is applied. The basic control system (3) detects the die lip temperatures y _{3 to} y ₇ to generate heat command values u ₃ ^{(3) to} u ₇ for the heater.
Specify ⁽³⁾ . FIG. 5D shows that the basic control system (4) is applied to control the die lip temperature y ₆ to a predetermined value. The basic control system (4) detects the die lip temperatures y _{4 to} y ₈ and determines the generated heat command values u ₄ ^{(4) to} u ₈ ⁽⁴⁾ of the heater. The figure (e) shows that the basic control system (5) is applied to control the die lip temperature y ₇ to a predetermined value. Basic control system (5). Detect the die lip temperature y _{5 to} y ₉ and determine the heat generation command value u ₅ ^{(5) to} u ₉ ⁽⁵⁾ of the heater. The same applies below.

By applying the above basic control systems (1) to (5), the final command value u ₅ of the heater h5 is given by the following equation.

u ₅ = u ₅ ⁽¹⁾ + u ₅ ⁽²⁾ + u ₅ ⁽³⁾ + u ₅ ⁽⁴⁾ + u ₅ ⁽⁵⁾ (5) As shown in the above equation, the generated heat command value for one heater is 5 It is determined in the process of applying the basic control system. Next, by sequentially applying the basic control system in order to control the die lip temperature of each operation end, that is, the portion corresponding to each heater to a predetermined value, the die lip temperature control over the entire film width becomes stable and Explain what is done quickly.

The basic control system (3) for controlling the die lip temperature y ₅ at a location corresponding to the heater u ₅ to a predetermined value is taken as an example. Heater h3
Since the generated heat command values u ₃ ⁽¹⁾ and u ₃ ⁽²⁾ from the basic control systems (1) and ⁽²⁾ are added to the generated heat command value in the basic control system ( ₃ ⁾ , the heater h3 is (u _It is thought that it receives one type of disturbance heat of ₃ ⁽¹⁾ + u ₃ ⁽²⁾ ). Next, the heater h4 uses the generated heat command value of the basic control system (3) as the basic control system (1), (2),
Since the generated heat command values u ₄ ⁽¹⁾ , u ₄ ⁽²⁾ , u ₄ ⁽⁴⁾ are added from (4), the heat h4 is (u ₄ ⁽¹⁾ + u ₄ ⁽²⁾ + u ₄ ⁽⁴⁾ Next, the heater h5 receives the generated heat command value of the basic control system (3) as the basic control system (1), (2),
Generated heat command values u ₅ ⁽¹⁾ , u ₅ ⁽²⁾ , u ₅ ⁽⁴⁾ , u ₅ from (4) and (5)
^{Since (5)} is added, the heater h5 is (u ₅ ⁽¹⁾ + u ₅ ⁽²⁾ + u
₅ ⁽⁴⁾ + u ₅ ⁽⁵⁾ ) is considered to be subjected to the disturbance heat. Next, the heater h6 generates heat command values u ₆ ⁽²⁾ , u ₆ from the basic control systems (2), (4) and (5) based on the heat generation command values of the basic control system (3).
⁽⁴⁾ , u ₆ ⁽⁵⁾ is added, so heater h6 is (u ₆ ⁽²⁾ + u _{6
^{(4) + u 6 8 5}} )) is considered disturbed heat of. Finally, the heater h7 adds the generated heat command values u ₇ ⁽⁴⁾ and u ₇ ⁽⁵⁾ from the basic control systems (4) and (5) to the generated heat command value of the basic control system (3). It is considered that h7 receives the disturbance heat of (u ₇ ⁽⁴⁾ + u ₇ ⁽⁵⁾ ). From the above, the basic control system (3)
It is considered that each of the heaters of 1 above receives the disturbance heat from the basic control system applied before and after that. However, the basic control system (3) changes the die lip temperature y ₅ to the heater h3 to
It is understood that the basic control system (3) can stably control the die lip temperature y ₅ because the heat can be controlled to a predetermined value with high responsiveness even if the disturbance heat enters the h 7. This can be said for the basic control system that controls the die lip temperature at other places as well, and it is understood that the die lip temperature control over the entire film width can be stably performed.

Finally, the operation of the present embodiment including the above consideration will be described.

The thermometer 11 (Fig. 1) is placed at a position (Fig. 2) corresponding to each position of a large number of heaters 12 embedded in the die in order to detect the die lip temperature profile over the width of the film to be extruded. Mounted. Therefore, the number of thermometers 11 and the number of heaters 12 are equal. Thermometer 11
Outputs the detected die lip temperature value to the distributor 101 through the sampler 100 at certain time intervals. Sampler 100
Can be replaced with a multi-point switch (multiplexer). The distributor 101 inputs as many data sets of the thermometers 11 as required by the basic control system to the basic control system 102-i. For example, a basic control system 102-i for controlling the die lip temperature i at a portion corresponding to the heater i is input with a data set of 5 points of die lip temperatures i-2, i-1, i, i + 1, i + 2 by the distributor 101. To be done. The basic control system 102-i is a distributor
Each time a data set of the die lip temperature is sent from 101, the generated heat command value for each heater determined by the previous control calculation is stored from the heater generated heat command value memory, which will be described later, from the basic control system 102-i. Input the previous heater generated heat command value (current heater generated heat) for a predetermined number of heaters belonging to the basic control system calculated value memory 10
The calculated heater generated heat value is stored in 3-i. The superposition adder 104 adds the calculated values from the basic control system calculated value memory 103-i for each heater to determine the heater generated heat command value S for each heater. The command value output S of the superposition adder 104 is also stored in the heater generated heat command value memory 105. When a new die lip temperature data set is input to the distributor 101 through the sampler 100 after a certain period of time,
The above calculation procedure is executed, a new heater generated heat command value is output from the superposition adder 104, and stored in the heater generated heat command value memory 105.

As described above, each basic control system can control the die lip temperature of the portion corresponding to each heater to a predetermined value and can stably control the die lip temperature over the entire longitudinal direction of the slot of the die.

〔The invention's effect〕

 The present invention has the following effects.

In order to control the film thickness, a large number of heaters are arranged in the longitudinal direction of the slot of the die lip as an adjusting mechanism. In the die lip temperature control of a portion corresponding to one heater, disturbance entering the heater and the adjacent heater It is possible to control the die lip temperature to a predetermined value by applying a basic control system with high responsiveness that compensates for disturbance and realizes effective heater heat distribution in consideration of interference effects between heaters. . Further, by applying the basic control system for each die lip temperature of the portion corresponding to the heater, the die lip temperature control over the entire film width can be stably performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a control device according to an embodiment of the present invention, FIG. 2 is a diagram showing correspondence between arbitrary 5 sets of heater positions and 5 sets of die lip temperature detection positions, and FIG. Block diagram showing a dynamic mathematical model of die lip temperature, 4th
FIG. 5 is a block diagram showing the structure of the basic control system of the above embodiment, FIG. 5 is a flow chart showing the application procedure of the basic control system of the above embodiment to the die lip temperature control point, and FIG. 6 is a film manufacturing plant. FIG. 7 is a diagram showing a conceptual configuration, FIG. 7 is a heater arrangement diagram embedded in a longitudinal direction of a slot of a die lip, and FIG. 8 is a simulation result diagram showing changes of a die lip temperature, a resin discharge amount, and a film thickness with respect to a heater generated heat amount change. FIG. 9 is a block diagram of a control device according to a conventional example. In the figure, 1 ... Extruder, 2 ... Die, 3 ... Manifold, 4 ... Die lip, 5 ... Die lip slot discharge port, 6 ... Cooling roller, 7 ... Film, 10 ... Winding machine , 11 ... thermometer, l ... longitudinal direction of slot of die lip, 12 ... heater, 100 ... sampler, 101 ... distributor, 102-i (i = 1 to N) ... basic control system, 103 -I ... Basic control system calculation value memory, 104 ... Superposition adder, 105 ... Heater generated heat command value memory, S ... Heater generated heat command value, h1 to h5 ... Heater, t1 to t5 ... Die lip Temperature, 20 ... Thermometer, 21 ... Sampler, 22 ... Adder, 23 ... Integrator, 24 ... Observer, 25 ... Heater generation heat controller, 26 ... Memory 130 ... Die lip temperature process , 131 …… Die lip temperature.

Claims (1)

[Claims] 1. A molten resin discharge amount adjusting mechanism having a die in which a plurality of heaters are arranged along the longitudinal direction of the slot of the die, and corresponds to the heater on the surface near the discharge port of the slot of the die. In an extrusion molding apparatus or a casting molding apparatus having a plurality of thermometers arranged at downstream positions, a plurality of samplers to which the outputs of the thermometers are respectively input, and a distributor to which each output of the sampler is input , A plurality of basic control systems to which the outputs of the distributor are respectively input, a plurality of basic control system calculation value memories to which the outputs of the basic control systems are respectively connected, and a calculation value of each basic control system It is provided with a superposition adder to which the output of the memory is input, and a heater generated heat command value memory to which the output of the superposition adder is input and which feeds back its own output to each of the basic control systems. Surufu Lum thickness control device.