JP2811847B2 - Rolling mill thickness control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate thickness control device that realizes a highly responsive plate thickness control in a rolling mill adopting a hydraulic pressure reduction system.

[Conventional technology]

FIG. 15 shows an example of a single-stand cold reversible rolling mill in which reels are arranged on an entrance side and an exit side as a conventional rolling mill employing a hydraulic pressure reduction method. In this figure, a rolled material 30 is sent out from a rewinding reel 20, and is supplied to a deflector roll 21.
After passing through between the work rolls 3 and 4, a predetermined rolling is performed, and then the roll is wound on a take-up reel 27 through a deflector roll 26. The unwinding and winding reels 20 and 27 are driven by motors 19 and 28, respectively, and further, reel motor tension control devices 18 and 29 for maintaining a constant tension applied to the rolled material 30 on the entrance and exit sides of the rolling mill 32. Is provided. The tension controllers 18, 29 generally control the motor current to be proportional to the tension. The rolling speed of the line is controlled to a predetermined value by controlling the speed of the work roll driving motor 23 of the rolling mill 32 by the speed control device 24.

In FIG. 15, 1 is a load cell for detecting a rolling load, 2 is an upper backup roll, 3 and 4 are upper and lower work rolls, and 5 is a lower backup roll. 66 is a hydraulic pressure reduction device, 6 is a hydraulic cylinder for setting the roll gap between the work rolls 3 and 4, 7 is a pipe between the hydraulic cylinder 6 and the servo valve 8, and 9 is a reduction ram 6 'mounted in the hydraulic cylinder. This is a displacement meter that detects the displacement of 10 is the servo valve 8
Servo amplifier sends the opening command to the (current signal), 11 is a coefficient multiplier which gives a control gain K _G to amplify an output signal of the adder-subtractor 12, and controls the pressing position S of the pressure ram 6 '.

The basic position control loop compares the command signal R with the output signal S of the displacement meter 9 and calculates the difference signal e by a coefficient unit 11.
In multiplying the gain K _G, this signal controls the degree of opening of the servo valve 8 via a servo amplifier 10, by adjusting the amount of pressure oil supplied from the pipe 7 to the hydraulic cylinder 6, pressure ram 6 'Position. As a result, the lower backup roll 5 and the lower work roll 4 move to adjust the opening (roll gap) between the upper and lower work rolls 3 and 4 to a predetermined value.

Further, only by controlling the position S of the rolling ram 6 ', an error occurs in the roll gap between the work rolls 3 and 4 by an amount corresponding to the elongation of the mill receiving the rolling load. Therefore, the reference rolling load _Pref is usually stored at a certain timing after the start of rolling, and the difference Δ from the rolling load during rolling detected by the load cell 1 is Δ
P is obtained by an adder / subtractor 17, and it is divided in a coefficient unit 16 by a mill constant Km (corresponding to a spring constant of a rolling mill, which is obtained in advance) to obtain the elongation of the mill, and determine what percentage to correct for the elongation of the mill. A correction signal C _P for correcting the position S of the rolling down ram 6 ′ is obtained by multiplying by the correction gain C, and this is given as a command for the basic position control loop to correct the rolling down ram position S.

Further, in order to match the absolute thickness h of the rolled material 30 on the exit side of the rolling mill 32 with the target value _href , a thickness gauge 25 provided on the exit side of the rolling mill 32 (the thickness gauge 22 is used when traveling in the reverse direction). ) Is compared with the target value _href by the adder / subtractor 31 to calculate the deviation Δ
h is passed through an integration controller 15, and then a correction signal Ch for correcting the position of the rolling down ram 6 'by multiplying the coefficient unit 14 by a correction gain 1+ (M / Ke) for correcting the actual rolling down position. This is also given as a command for the basic position control loop, and the rolling ram position S is corrected. Here, M is obtained in advance as a constant representing the hardness of the rolled material 30. Ke is a controlled mill constant and has a relationship of Ke = Km / (1-C).

[Problems to be solved by the invention]

In the rolling mill shown in FIG. 15, when the roll gap is changed by changing the position S of the rolling ram 6 'in order to control the thickness of the rolled material 30, the entrance and exit side tension acting on the rolled material 30 also changes. . For example, to reduce work thickness,
When the roll cap between 3 and 4 is narrowed, the rolled material 30 extends, and the tension on the entrance and exit sides decreases. Tension control devices 18 and 2 for controlling motors 19 and 28 of rewind and take-up reels 20 and 27 on the input and output sides
Since the response of 9 is generally one order of magnitude slower than hydraulic pressure reduction,
Even if the roll gap is changed and the tension changes, the tension cannot be returned to the set value at the same speed as the hydraulic pressure. For this reason, the tension on the entrance and exit sides is reduced, and as a result, an effect is produced as if the deformation resistance of the rolled material 30 has apparently increased, and the roll gap tends to increase (the sheet thickness does not decrease). In other words, even if you try to reduce the thickness under high-speed hydraulic pressure,
The plate thickness cannot be reduced at a speed higher than the response of the tension control device of the inlet / outlet reel motors 19, 28.

It is often heard at rolling mills that no matter how fast the ram position is controlled using hydraulic reduction, the accuracy of the thickness control is not as good as expected, but for the reasons mentioned above.

FIG. 16 shows a simulation example using a computer by the present inventor, and clarifies the above. The object of the simulation was a single-stand cold reversible rolling mill shown in Fig. 15 with a set inlet tension of 1.36 TO.
N, output side set tension 2.35TON, inlet side thickness 0.52mm, width 1800mm
Under the condition that the target material thickness is 0.3 mm at a rolling speed of 1800 m / min, the roll gap is set to 10 μm
This is an example of a decrease. Response under hydraulic pressure is 90 in frequency response
Degree phase lag of 20 Hz, and step response of 0.04
It is a fast one that reaches the target value in seconds or less. According to the simulation results, the roll gap is 10 μm
In other words, the exit side plate thickness change Δh reaches a steady value in approximately one second. Although the actual hydraulic pressure reduction reaches the target value in 0.04 seconds, the plate thickness changes only 25 times slower, as described above, because the response of the inlet / outlet tension control devices 18, 29 is slow. It is. That is, generally, the tension of the reels 20, 27 is controlled by keeping the motor current constant.
This is because the inertia of the reels 20 and 27 including the reels 9 and 28 is considerably large, so that it takes about one second until the peripheral speed of the reels 20 and 27 reaches the next steady value that suppresses the tension fluctuation by the current control.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a thickness control device for a rolling mill capable of improving the response of thickness control and obtaining a product thickness with high accuracy. .

[Means for solving the problem]

The present invention relates to a thickness control device for a rolling mill including a tension control device that adjusts a tension applied to a rolling material on both the entrance side and the entrance side of a rolling mill having a hydraulic pressure reduction device. There, the tension control device, a tension detector that detects the tension applied to the rolling material, a press roll that presses the rolling material, and a hydraulic cylinder that drives the press roll in the rolling material direction, A servo valve for controlling a flow rate to the hydraulic cylinder based on a difference between a predetermined tension set value and a tension detected by the tension detector, while measuring a diameter of a coil wound on a reel. And a calculator for changing the sign and magnitude of the control gain of the tension control device based on the measurement result.

(Operation)

According to the present invention, a tension control device is provided on both the entry side and the entry / exit side of the rolling mill, and the tension control device presses the rolling material with a tension detector that detects a tension applied to the rolling material. A presser roll, a hydraulic cylinder that drives the presser roll in the rolling material direction, and a servo valve that controls a flow rate to the hydraulic cylinder based on a difference between a predetermined tension set value and a tension detected by a tension detector. In addition, a measuring device for measuring the diameter of the coil wound on the reel and a speed detector for the rolled material are provided, and the sign and magnitude of the control gain of the tension control device are changed based on the measurement result. Since a computing unit is provided, the fluctuation of the tension due to the fluctuation of the roll gap can be suppressed quickly. This makes it possible to maximize the high-speed controllability of the hydraulic pressure reduction and enhance the response of the plate thickness control. As a result, it is possible to obtain an accurate product plate thickness.

〔Example〕

(Embodiment 1) Fig. 1 shows an embodiment in which the present invention is applied to a single-stand cold reversible rolling mill. This is the same as the conventional apparatus shown in FIG. 15 except that the tension control device 34 according to the present invention is arranged on both the entrance and exit of the rolling mill 32. 15 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 2 shows an embodiment of the tension control devices 33 and 34. Second
In the figure, reference numeral 35 denotes a press roll for pressing the rolled material 30, which is rotatably supported by the arm. 37 is a load detector (load cell) attached to the bearing of the presser roll 35,
The reaction force from the rolling material 30 is detected. Arm 36 is lever 38
And rotates about the rotating spindle 39, and as a result, the presser roll 35 moves up and down. Lever 38 is a hydraulic cylinder
The piston is connected to a piston rod 41 mounted on the cylinder 40, and rotates around a rotating main shaft 39 by adjusting the amount of fluid to the hydraulic cylinder 40 with a servo valve 42. As a result, the integrated arm 36 rotates and moves the presser roll 35 up and down. The adjustment of the opening of the servo valve 42 is based on the rolled material 30 detected by the load detector 37.
The tension T of the rolled material 30 is calculated from the reaction force of the rolled material 30 by a tension calculator 46, and the calculated value is compared with a tension set value _Tref by an adder / subtractor 45 to obtain a deviation ΔT. coefficient
By multiplying K _T and controlling the servo valve 42 via the servo amplifier 43, the deviation ΔT is controlled to be zero.

According to the tension control devices 33 and 34 shown in FIG. 2, when the roll gap changes, the resulting change in tension is detected by the load detector 37 of the bearing of the presser roll 35, and this is detected as the target value T _ref. The high-speed servo valve 42 adjusts the inflow and outflow of the fluid to and from the hydraulic cylinder 40 so as to coincide with the above. As a result, the presser roll 35 moves up and down, and the tension of the rolled material 30 changes immediately. For this reason, the result of changing the roll gap under hydraulic pressure is immediately reflected in the exit side plate thickness, and plate thickness control with a higher response can be performed as compared with the case where a tension control device using a conventional motor current is used. In the apparatus shown in FIG. 1, the reel motor tension controllers 18 and 19 suppress the slow tension fluctuation,
The tension controllers 33, 34 act to absorb fast tension fluctuations.

FIG. 3 is a simulation example in which the response of the reel motor tension controllers 18 and 29 on the entry and exit sides of the rolling mill 32 in FIG. 15 is three times faster under the same conditions as in FIG. Roll gap is stepped by 10 compared to
When it is reduced by μm, the delivery side thickness Δh reaches a steady value approximately three times faster, and after approximately 0.3 seconds.

Since the tension controllers 33 and 34 shown in FIG. 2 can provide a response as high as the hydraulic pressure reduction, the plate thickness can be controlled by suppressing the tension fluctuation more quickly than in the simulation example shown in FIG.

FIG. 4 is a simulation example in which the response of the entrance reel motor tension controller 18 in the rolling mill of FIG. 15 is the same as that of FIG. 16, and the response of only the exit tension controller 29 is three times faster. In FIG. 5, the response of the output side reel motor tension controller 29 is the same as that in FIG. 16, and only the input side reel motor tension controller 18 controls the tension three times faster. It is a simulation example in the case.

As can be seen from FIGS. 4 and 5, only by controlling the tension on the entrance side of the rolling mill, which has a greater effect on the deformation resistance of the rolling material 30 than on the exit side, at a high speed, the entrance and exit sides in FIG. It can be seen that the same effect as in the case of high-speed control can be obtained. Therefore, in the case of the rolling direction shown in the drawing, of the tension control devices 33 and 34 on the entrance side shown in the embodiment of the present invention in FIG. Is obtained. In a reversible rolling mill, tension control devices 33 and 34 need to be installed on both the entrance and exit sides of the rolling mill. However, in a non-reversible rolling mill that performs rolling in only one direction, the tension control devices 33 and May be just installed.

Embodiment 2 Another embodiment of the present invention is shown in FIG. This is because the tension controllers 48 and 49 detect the tension of the rolled material 30 by the load detector 50 attached to the bearings of the deflector rolls 21 and 26, and adjust the pressing amount of the presser roll 35 based on this detection to adjust the rolled material. 30
Is controlled. Example 1
The same reference numerals are used for the parts common to.

FIG. 7 shows an embodiment of the tension control devices 48 and 49 shown in FIG. In FIG. 7, reference numeral 35 denotes a press roll for holding the rolled material 30, which is rotatably supported by the arm 36. Reference numeral 50 denotes a load detector attached to the bearings of the deflector rolls 21 and 26, and detects a reaction force from the rolled material 30. Arm 36 is a lever
It is connected to a rotation shaft 38 and rotates about a rotating spindle 39, and as a result, moves up and down the press roll 35. The lever 38 is connected to a piston rod 41 mounted on a hydraulic cylinder 40,
By adjusting the amount of liquid to the hydraulic cylinder 40 by the servo valve 42, the liquid is rotated about the rotating main shaft 39. As a result, the integrated arm 36 rotates and moves the presser roll 35 up and down. The opening of the servo valve 42 is adjusted by the rolled material detected by the load detector 50.
The tension T of the rolled material 30 is calculated and calculated from the reaction force of the rolling material 30 by a tension calculator 46, and the calculated value is compared with a tension set value _Tref by an adder / subtractor 45 to obtain a deviation ΔT. multiplied by the coefficient K _T, by controlling the servo valve 42 through a servo amplifier 43 is controlled so that the deviation ΔT is zero.

According to the tension controllers 48 and 49 shown in FIG. 7, when the roll gap changes, the resulting tension change is detected by the load detector 50 of the bearing portion of the deflector rolls 21 and 26, and this is set to the target value. High speed servo valve to match T _ref
At 42, the inflow and outflow of fluid to and from the hydraulic cylinder 40 are adjusted, and as a result, the presser roll 35 moves up and down, and the tension of the rolled material 30 changes immediately. For this reason, the result of changing the roll gap under hydraulic pressure is immediately reflected on the exit side plate thickness, and high response plate thickness control is realized by using together with the conventional motor current tension control device as in the first embodiment. it can.

(Embodiment 3) FIG. 8 shows still another embodiment of the present invention. This is an example in which a fluid film is used as the tension control device 61 instead of the presser roll, and includes a fluid pad 57, a control valve 58, a fluid source 59, and a pipe 60 connecting them. The above embodiment
The same reference numerals are used for portions common to 1 and 2.

The fluid pad 57 injects a fluid supplied from a fluid source 59 via a control valve 58 onto the lower surface of the rolled material 30, supports the rolled material 30 by the pressure, and applies tension. The load detector 50 is attached to bearings of the deflector rolls 21 and 37, and detects a reaction force from the rolled material 30.

The detection output of the load detector 50 is input to a tension calculator 62, and the tension T of the rolled material 30 is obtained. The calculated tension T
Is compared calculating the tension setting value T _ref by subtractor 63, the deviation ΔT is determined. The coefficient unit 64 adds a coefficient K _TV to this deviation ΔT.
Is multiplied as an input of the control valve regulator 65. Control valve regulator 65
Adjusts the opening of the control valve 58 in accordance with the input signal, and controls the amount of fluid ejected from the fluid pad 57. That is, if the detected tension T is smaller than the tension setting value T _ref, to increase the amount of fluid by opening the control valve 58 to increase the tension. Conversely, the detected tension T is greater than the tension setting value T _ref, by reducing the amount of fluid decreases the tension squeezing control valve 58. Thus, the tension applied to the rolled material 30 is controlled by the pressure of the fluid film, and the deviation ΔT becomes zero.

Fourth Embodiment FIG. 9 shows an example in which the tension control device 100 utilizes the attractive force of the electromagnet 101, and the pressure material is limited to a ferromagnetic material such as iron. Those denoted by the same reference numerals as those in FIG. 8 have the same functions as those described in FIG. 103 is an electromagnet output controller. Deviation between the detected tension T and the tension setting value T _ref delta
The tension control is performed by driving the electromagnet 101 according to T to generate a vertical attractive force on the rolled material 30. Note that, instead of the electromagnet 101, a linear motor may be arranged above and below the rolling material to apply tension by an attractive force or a repulsive force. In that case, the rolling material is limited to a conductive material.

By the way, it was mentioned earlier that the response of the plate thickness control can be improved by increasing the response of the tension control with reference to FIGS. 3, 4, 5, and 16. The function of the tension control device of the present invention will be clarified.

FIG. 10 is a view for explaining the principle of a tension control device for the rewinding and winding reels 20, 27. Now, assuming that the diameter of the coil 67 is D, the tension is T, and the torque of the motor 19 (28) is τ, the torque τ required to generate the tension T at the coil diameter D is represented by the coil diameter D and the tension T. Τ 比例 T · D (1) On the other hand, since the output torque of the motor 19 (28) can be expressed as τ∝i · φ (2), T∝i · (φ / D) (3) is obtained from the equations (1) and (2). i represents a motor current, and φ represents a motor field magnetic flux. Here, if the coil diameter D and the motor field magnetic flux φ are controlled to be proportional, (φ / D) becomes constant, and the tension T is proportional to the motor current i. From this, reel 20, 27
In the tension control, the control is performed to make the coil diameter D proportional to the motor field magnetic flux φ, and then the motor current is set to obtain the necessary tension T. The above is the tension control method during the steady rolling of the unwinding and winding reels 20 and 27 (the rolling speed after acceleration is constant).

As shown in FIG. 16, in such a conventional tension control method, since the response of the tension control is slow even when the roll gap is changed, the exit side plate thickness changes only with the response time of the tension control.
Therefore, even if a high-speed hydraulic pressure reduction device was used, the accuracy of the thickness was not improved.

FIG. 11 is a Bode diagram showing the effect on the exit side plate thickness Δh when the roll gap ΔS is changed. The dotted line is an example using the conventional tension control device, and the solid line is an example in which the tension control device of the present invention (for example, 48 (FIG. 7)) is inserted at the entrance of the rolling mill. In the conventional example indicated by the dotted line, the effect of the roll gap ΔS is attenuated to 1/1000 at 3.75 Hz. Although this sharp downward peak will be described later, the inertia of the reel 20 (27) and the rolled material
The spring constant of thirty arises due to the resonance that it makes. On the other hand, in the device of the present invention shown by the solid line, the downward peak shifts to the lower frequency side, and the attenuation at the peak is reduced to about 1/10. Further, it can be seen that the characteristic is completely flat at 2 to 10 Hz, which is currently focused, and the roll gap ΔS is reflected in the plate thickness Δh.

FIG. 12 is a block diagram for explaining the function of the tension control device of the present invention, and the control device portion is omitted because the response is fast. The dotted line indicates the characteristics of the tension control device of the present invention.

Symbol, E: Young's modulus of the rolling mill, b: plate width, H: thickness, L _1:
Roller-reel distance, J: Moment of inertia of reel including coil, R: Coil radius (= D / 2), Kt: Gain of tension controller, S: Laplace operator, ΔV: Speed fluctuation during rolling,
ΔTb: Back tension fluctuation.

The concept of this block diagram will be described below. First, the reel 20 (27) including the coil 67 is accelerated by a tension value Tb proportional to the motor current value from a current control device (not shown), and a reel peripheral speed v is generated (block 69). The disturbance with respect to the reel peripheral speed v is a speed change ΔV of the rolled material 30 caused by a change in the tension on the entrance side and the exit side of the rolling mill 32 and a variation in the thickness of the rolling mill 30. It will be a balance. This is integrated at 73 to become the longitudinal elongation difference Δl of the rolled material 30. In block 76, a change Δσ in tension stress is calculated from the difference Δl in the longitudinal direction, and bH is multiplied to obtain a back tension fluctuation ΔTb. The tension value Tb is compared with the tension value Tb by the adder 80, and the reel 20 (27) is driven by the deviation Tb-ΔTb, and the effect of ΔV is corrected in the process described above. However, due to the large inertia of the reel 20 (27) indicated by the block 69, the correction speed is low as described above. The tension control device (eg, 48) of the present invention detects the tension variation ΔTb and multiplies it by the conversion coefficient
In addition, the control amount Klc is multiplied by the control gain Kt to obtain the control amount Δlc, and the tension control is performed. As can be seen from FIG. 12, the response is fast because the inertia of the reel (block 69) is not interposed.

If the transfer function from ΔV to ΔTb is determined without considering the characteristics within the dotted line from FIG. 12, the following equation is obtained.

From equation (4), the resonance frequency ω _n is This value was 3.75 Hz in the conventional device shown by the dotted line in FIG.

Next, the transfer function from ΔV to ΔTb including the characteristics of the tension control device of the present invention in the dotted line is given by the following equation. Here, G represents the dynamic characteristic of the tension control device (block 86 in FIG. 12), It is.

From equation (5), the resonance frequency ω _n is Has changed. That is, the tension control device of the present invention functions to change the Young's modulus of the rolled material 30 by control, and as a result, the inertia of the reel 20 (27) and the spring constant (Young's modulus) of the rolled material 30
It can be seen that with the shift to a region where the resonance frequency ω _n does not affect the thickness control to make the function. If Kt is a positive value,
Taking the resonance frequency lower than the actual resonance frequency and taking a negative value corresponds to shifting the resonance frequency to the higher frequency side. By doing so, even if the roll gap is moved at a high frequency, which occurs in the conventional control system, it is possible to prevent the phenomenon that the tension is large due to the resonance of the reel 20 (27) and the plate thickness does not change. Then, the result of operating the roll gap is reflected on the sheet thickness, so feedforward AG
Conventional sheet thickness control methods such as C and Visla AGC work effectively.

(Embodiment 5) An embodiment based on the above invention is shown in FIG. (6)
As can be seen from the equation, the inertia of the reel changes as the coil radius R changes. FIG. 13 is characterized in that the radius R is detected by, for example, the optical sensor 90, and the correction amount ΔKt of the control gain Kt is obtained by the calculator 91 based on the radius R, and the control gain Kt is changed based on the correction amount ΔKt.

(Embodiment 6) FIG. 14 shows another embodiment based on the above-mentioned invention, in which a rolled material 30 is used.
Is detected by the detector 93, and the frequency of the input side plate thickness disturbance is calculated based on the detected speed V to obtain a necessary ω _n, and the control gain required to give it from the equation (6) is corrected. It is characterized in that the control gain Kt is changed by back-calculating the quantity ΔKt by the computing unit 94.

[Modification example]

In the above-described embodiment, only the case where the present invention is applied to a single-stand cold reversible rolling mill has been described. However, such conventional rolling mills as a non-reversible rolling mill that rolls in one direction and a tandem rolling mill having two or more stands are used. It goes without saying that the present invention can be applied to all rolling mills in which the problems described in the art occur.

In addition, the tension can be detected by a reaction force from the rolled material on rolls and other parts arranged in the traveling path of the rolled material other than the presser roll and the deflector roll.

〔The invention's effect〕

As described above, according to the present invention, a tension control device is provided on both the entry side and the entry / exit side of the rolling mill, and the tension control device is provided with a tension detector for detecting the tension applied to the rolling material. A press roll for pressing the rolled material, a hydraulic cylinder for driving the press roll in the direction of the rolled material, and a flow rate to the hydraulic cylinder based on a difference between a predetermined tension set value and a tension detected by a tension detector. And a measuring device for measuring the diameter of the coil wound on the reel, a speed detector for the rolled material, etc., and a positive or negative control gain of the tension control device based on the measurement result. Since we provided a computing unit to change the sign and size,
Fluctuations in tension due to fluctuations in the roll gap can be quickly suppressed, and the high-speed controllability of the hydraulic pressure can be maximized to increase the response of plate thickness control and obtain accurate product plate thickness. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration of a sheet thickness control device of a cold reversible rolling mill to which the present invention is applied. FIG. 2 is a diagram showing a specific example of the tension control devices 33 and 34 in FIG. FIGS. 3 to 5 are diagrams showing computer simulation results showing the response when the response of the reel motor tension controllers 18 and 29 is three times faster in the apparatus shown in FIG. 15. FIG. 3 shows the input / output tension control. FIG. 4 shows a case where the response of both the devices 33 and 34 is made faster, FIG. 4 shows a case where the response of only the output side tension controller 34 is made faster, and FIG. FIG. 6 is a block diagram showing another embodiment of the present invention. FIG. 7 is a diagram showing a specific example of the tension control devices 48 and 49 in FIG. FIG. 8 is a diagram showing still another embodiment of the tension control device according to the present invention. FIG. 9 is a block diagram showing one embodiment of the present invention using an electromagnet or a linear motor as a tension control device. FIG. 10 is a view for explaining the principle of tension control of the rewind and take-up reels 20, 27. FIG. 11 is a Bode diagram showing the effect on the exit side plate thickness Δh when the roll gap ΔS is changed. FIG. 12 is a block diagram for explaining the function of the tension control device of the present invention. FIG. 13 is a block diagram showing an embodiment of the present invention in which the control gain is modified according to the coil diameter. FIG. 14 is a block diagram showing one embodiment of the present invention in which the control gain is modified according to the speed of the rolling mill. FIG. 15 is a block diagram showing a system configuration of a conventional thickness control device for a reversible cold rolling mill. FIG. 16 is a diagram showing a simulation result showing a response of the thickness control of the apparatus shown in FIG. 6 ... hydraulic cylinder (hydraulic cylinder), 8 ... servo valve, 32 ... rolling mill, 20 ... rewind reel, 21 ... deflector roll, 27 ... take-up reel, 19, 28 ... reel motor Tension control (current control) device, 30 ... Rolled material (rolled material), 33, 34, 48, 49, 61 ... Tension control device, 35 ... Pressing roll, 37, 50 ... Load detector (Tension detection Device), 57: Fluid pad (fluid support mechanism), 66: Hydraulic pressure reduction device.

Claims (7)

(57) [Claims] 1. A thickness control device for a rolling mill, comprising a tension control device for adjusting a tension applied to a rolling material on both the entrance side and the entrance side of a rolling mill provided with a hydraulic pressure reduction device. Wherein the tension control device detects a tension applied to the rolled material, a pressurizing roll that presses the rolled material, and a hydraulic cylinder that drives the pressurized roll in the direction of the rolled material. A servo valve that controls a flow rate to the hydraulic cylinder based on a difference between a predetermined tension set value and a tension detected by the tension detector,
A measuring device for measuring the diameter of the coil wound on the reel is provided, and a computing device for changing the sign and magnitude of the control gain of the tension control device based on the measurement result is provided. Thickness control device for rolling mill. 2. A thickness control device for a rolling mill comprising a tension control device for adjusting the tension applied to a rolling material on both the entrance side and the entrance side of a rolling mill provided with a hydraulic pressure reduction device. Wherein the tension control device detects a tension applied to the rolled material, a pressurizing roll that presses the rolled material, and a hydraulic cylinder that drives the pressurized roll in the direction of the rolled material. A servo valve that controls a flow rate to the hydraulic cylinder based on a difference between a predetermined tension set value and a tension detected by the tension detector,
A rolling detector provided with a speed detector for detecting the speed of the rolling material, and a computing unit for changing the sign and magnitude of the control gain of the tension control device based on the detection result. Machine thickness control device. 3. A thickness control device for a rolling mill having a tension control device for adjusting the tension applied to a rolling material on both the entrance side and the entrance side of a rolling mill provided with a hydraulic pressure reduction device. Wherein the tension control device detects a tension applied to the rolled material, a tension detector, a fluid support mechanism that forms a fluid film supporting the rolled material, a predetermined tension set value, A control valve for controlling an output amount of the fluid support mechanism based on a difference from a tension detected by a tension detector. 4. A thickness control device for a rolling mill comprising a tension control device for adjusting the tension applied to a rolling material on both the entrance side and the entrance side of a rolling mill provided with a hydraulic pressure reduction device. Wherein the tension control device detects a tension applied to the rolling material, a tension detector that applies an attractive force to the rolling material, a predetermined tension set value, and a tension detected by the tension detector. A controller for controlling the attraction force of the electromagnet based on a difference between the tension and the applied tension. 5. A thickness control device for a rolling mill comprising a tension control device for adjusting a tension applied to a rolling material on both the entrance side and the entrance side of a rolling mill provided with a hydraulic pressure reduction device. Wherein the tension control device, a tension detector that detects the tension applied to the rolling material, and a linear motor that applies a suction force or a repulsive force to the rolling material,
A rolling machine comprising: a controller for controlling a suction force or a repulsion force of the linear motor based on a difference between a predetermined tension set value and a tension detected by the tension detector. Thickness control device. 6. The method according to claim 3, wherein the sign and magnitude of the control gain of the tension control device are changed based on the measured diameter of the coil wound on the reel. A thickness control device for a rolling mill as described in the above. 7. The rolling mill according to claim 3, wherein the sign and magnitude of the control gain of the tension control device are changed based on a signal from a speed detector of the rolling material. Thickness control device.