JP2012152808A - Roll control method in hot rolling line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the holding state of rolls at a target value by simply suppressing a periodic influence caused by eccentricity of the rolls which hold a to-be-rolled material.SOLUTION: A roll control method is provided, which is employed in a hot rolling line 1A where a to-be-rolled material 3 rolled by a finishing mill 2 is coiled by a coiler 4. A repetitive controller 52 is used as a mechanism for generating a periodic signal corresponding to eccentricity of pinch rolls 42, which are provided in a pair state to hold the to-be-rolled material 3, and the gap between the pinch rolls 42 is controlled in synchronization with the periodic signal generated from the repetitive controller 52, so that the holding state of the pinch rolls 42 is maintained at steel sheet tension TPR as a target value.

Description

  The present invention relates to a roll control method in a hot rolling line in which a material to be rolled such as a steel plate rolled by a finish rolling mill is wound in a coil shape by a winder.

  In general, a hot rolling line for steel sheets is a slab heated to a high temperature in a heating furnace, rolled to a desired sheet thickness by a roughing mill and a finishing mill, and thinly rolled into a steel sheet strip, and then wound by a winder. It is configured to be wound in a coil shape. In addition, a pinch roll is provided on the upstream side of the winder, and by applying a predetermined steel sheet tension to the steel sheet wound around the pinch roll by sandwiching the steel sheet with a desired pressing force, It is trying to suppress the occurrence of winding defects such as aperture.

  In Patent Document 1, regarding the winding control in the hot rolling line, the steel sheet is wound with the pressing force value or the torque value of the pinch roll within a predetermined range, and thus the coil shape can be stably generated without causing a drawing wrinkle or the like. How to wind up is shown.

  In Patent Document 2, after the tail end of a metal strip such as a steel plate has passed through the finishing mill, the current of the electric motor that rotates the pinch roll is captured, and control is performed so as to adjust the gap between the upper and lower pinch rolls based thereon. The method is shown. This prevents the occurrence of throttling by controlling the tension of the steel plate as intended.

  In Patent Document 3, an estimation calculator for estimating the tension generated in the material to be rolled between the finish rolling mill and the winder is provided, and the driving torque of the winder is corrected based on the estimated tension value by the estimation calculator. Thus, a winding control method for controlling the tension of the material to be rolled to a target tension is shown.

  Non-Patent Document 1 states that in order to cause a control amount to follow or suppress a signal applied to the system, the system must include a mechanism for generating the signal (so-called internal model principle). Is described.

JP 2006-281262 A JP 2006-150403 A JP 09-052119 A

Michio Nakano et al., “Repetitive Control” The Society of Instrument and Control Engineers, Corona, 1989

  However, in such winding control of a steel plate, the steel plate tension fluctuates periodically, and it is sometimes difficult to suppress it. Therefore, as a result of intensive studies by the present inventors, it has been found that the cause of the periodic fluctuation of the steel plate tension is the eccentricity of the pinch roll.

  Patent Documents 1 and 2 both suppress the occurrence of wrinkles and telescopic movements by controlling the pinch roll gap so that the pressing force value or torque value (current value) of the pinch roll is within an appropriate range. It is. In this way, by controlling the pressing force value or torque value (current value) of the pinch roll, it is possible to suppress the winding shape defect. However, when the pinch roll has eccentricity, the periodic pinch roll due to eccentricity. There is a problem that it is not easy to control the control amount within an appropriate range due to a gap disturbance.

  Moreover, in patent document 3, the disturbance of a steel plate tension is estimated and the torque of a winder is corrected. However, in order to estimate the disturbance of tension, it is necessary to incorporate a disturbance generation mechanism in the estimator as described in Non-Patent Document 1, but in the case of this document, steady disturbance (frequency is 0Hz disturbance) is assumed as an assumed range, so when the eccentricity of the pinch roll is a disturbance, it is difficult to remove the influence, and the tension fluctuation cannot be suppressed, leading to a defective winding shape. There was a problem.

  By the way, with respect to the finishing mill, a technique for preventing periodic fluctuations in the thickness of the material to be rolled due to the influence of the eccentricity of the work roll is known. However, this countermeasure performs control using angle information as absolute position information regarding unevenness due to eccentricity of the work roll. For this reason, it is necessary to rotate the work roll in advance and perform frequency analysis to determine the roll eccentricity, which is complicated and lacks versatility, and also requires an encoder.

  The present invention has been made in view of the above, and it is possible to easily suppress the periodic influence due to the eccentricity of the roll that sandwiches the material to be rolled, and to maintain the roll clamping state at the target value. It aims at providing the roll control method in a hot rolling line.

  In order to solve the above-described problems and achieve the object, the roll control method in the hot rolling line according to the present invention is a hot rolling line in which a material to be rolled that has been rolled by a finish rolling mill is wound by a winder. A roll control method using a generation mechanism of a periodic signal due to eccentricity of a roll provided in pairs and sandwiching the material to be rolled, and in synchronization with the periodic signal generated by the generation mechanism of the periodic signal By operating the gap, the holding state of the roll is held at a target value.

  Moreover, the roll control method in the hot rolling line according to the present invention is characterized in that, in the above invention, the period of the periodic signal is variable according to the peripheral speed of the roll.

  The roll control method in the hot rolling line according to the present invention is characterized in that, in the above invention, the periodic signal generation mechanism is a repetitive controller.

  Moreover, the roll control method in the hot rolling line according to the present invention is characterized in that, in the above invention, the periodic signal generation mechanism is a disturbance estimator.

  According to the present invention, by using a mechanism for generating a periodic signal due to eccentricity of the roll and operating the gap of the roll in synchronization with the periodic signal generated by the mechanism for generating the periodic signal, fluctuations in the pressing force on the roll, etc. Therefore, it is possible to suppress the periodic influence due to the eccentricity of the roll holding the material to be rolled, and to keep the holding state of the roll such as the material to be rolled at a target value. A roll control method in a rolling line can be provided.

FIG. 1 is a diagram schematically showing a part of a hot rolling line according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration example of the iterative controller. FIG. 3 is a diagram schematically showing a part of a hot rolling line according to the second embodiment of the present invention. FIG. 4 is an explanatory diagram showing a comparison of simulation results of pressing force control between the conventional method and the first embodiment using a repetitive controller. FIG. 5 is an explanatory diagram showing a comparative example between the actual roll eccentricity and the estimated amount. FIG. 6 is an explanatory diagram showing a control result by simulation of the second embodiment using a disturbance estimator.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
Embodiment 1 of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a diagram schematically showing a part of a hot rolling line. In the hot rolling line 1A, a metal material heated to a high temperature by a heating furnace (not shown) is rolled to a desired plate thickness by a rough rolling mill (not shown) and a finishing rolling mill 2 to obtain a steel strip-shaped material 3 to be rolled. Extend thinly. Here, the finish rolling mill 2 takes the form of a hot tandem rolling mill that simultaneously rolls the high-temperature workpiece 3 with a plurality of rolling mills. In FIG. 1, the finishing rolling mill is paired to form the final rolling mill. Only the roll 21 is illustrated.

  Further, in the hot rolling line 1A, a cooling machine (not shown) and a winder 4 are provided at the subsequent stage of the finish rolling mill 2, and the rolled material 3 that has been finished and cooled is coiled. It is configured to wind up. The winder 4 includes a mandrel 41 that serves as a rotating mandrel that winds the material 3 to be coiled, and a pinch that is positioned on the upstream side of the mandrel 41 and holds the material 3 in a pressed state by a pressing force. A roll 42, an electric motor 43 that rotates the pinch roll 42, and a speed controller 44 that controls the speed of the pinch roll 42 by the electric motor 43 according to the winding rotation speed of the mandrel 41 are provided. Here, in the winding operation, the pinch roll 42 suppresses the occurrence of telescopic and drawing by applying a predetermined steel plate tension TPR that opposes the steel plate tension TMD by the mandrel 41 to the material 3 to be rolled. There is a need to maintain the steel plate tension TPR at a desired reference value (target value) as the pinch roll 42 is sandwiched.

  Such a steel plate tension TPR of the pinch roll 42 can be controlled, for example, by adjusting a pressing force (rolling force) by operating a gap between rolls of the pinch roll 42. Alternatively, the control can be performed by calculating the steel plate tension backward from the current value of the electric motor 43 that rotates the pinch roll 42 and operating the gap between the rolls so that the steel plate tension becomes the target value.

  Therefore, in the first embodiment, the pinch roll 42 is controlled, and the steel plate tension TPR is controlled to be held at a desired reference value, and the controller 5 is provided. The controller 5 includes an arithmetic unit 51, a repeat controller 52, and a PI controller 53. The computing unit 51 detects the actual pressing force detected from the pinch roll 42 to adjust the tension against a reference pressing force or torque applied from a process computer (not shown) as an instruction value corresponding to the target value of the steel plate tension TPR. By adding (subtracting) force or torque, the difference between the two is obtained. In the case of the actual torque, the actual torque value of the electric motor 43 that rotates the pinch roll 42 is converted.

The repetitive controller 52 is a mechanism for generating a periodic signal due to the eccentricity of the pinch roll 42, and includes a calculator 52a and a calculator 52b as shown in FIG. The repetitive controller 52 receives the signal from the computing unit 51 and outputs an output signal to the PI controller 53. The computing unit 52a adds the input signal and the feedback signal delayed by one turn from the computing unit 52b. The computing unit 52b ^performs a computation process of e- ^{Ts on} the output of the computing unit 52a and feeds back to the computing unit 52a with a delay of one round. Here, T is the time taken for the pinch roll 42 to make one rotation. If the radius of the pinch roll 42 is R and the peripheral speed is VPR, T can be calculated as T = 2πR / VPR. Therefore, when the peripheral speed (speed) of the pinch roll 42 changes, the time T indicating the cycle may be made variable according to the peripheral speed VPR, and a table or the like may be referred to. S is a Laplace operator, and e is the base of the natural logarithm. Thereby, the repeat controller 52 becomes a mechanism for generating a periodic signal for one period of the pinch roll, and the roll gap synchronized with the eccentricity with respect to the pinch roll 42 through the proportional control and integral control by the PI controller 53. A command signal is given. The pinch roll 42 is operated to open or close the roll gap in accordance with a roll gap command signal synchronized with eccentricity, thereby holding the steel plate tension TPR at a reference value.

  Thus, according to the first embodiment, in the pressing force control or torque control of the pinch roll 42 for maintaining the steel plate tension TPR at the reference value, the eccentric period of the pinch roll 42, that is, the outer periphery of the pinch roll 42 Since the repeat controller 52, which is a mechanism for generating a signal corresponding to the length, is used, the roll gap control synchronized with the eccentric period of the pinch roll 42 becomes possible, and the influence (pushing) by the eccentricity of the pinch roll 42 becomes possible. Force fluctuation or torque fluctuation) can be completely eliminated. In the first embodiment, it is only necessary to know the eccentricity period of the pinch roll 42, and a simple and highly versatile control method can be realized without requiring prior measurement and analysis.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram schematically showing a part of the hot rolling line. The same parts as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is also omitted. In the hot rolling line 1 </ b> B of the present embodiment, a controller 6 is used instead of the controller 5. The controller 6 includes a calculator 61 and a disturbance estimator 62. The calculator 61 is a periodic gap disturbance due to the eccentricity of the pinch roll 42 estimated by the disturbance estimator 62 with respect to the gap command value serving as a reference pressing force corresponding to the reference value of the target steel plate tension TPR. A certain gap fluctuation estimated value is subtracted and inputted so as to have an opposite phase, and a deviation between the two is given to the pressing force mechanism of the pinch roll 42 as a gap command value. The disturbance estimator 62 is a mechanism for generating a periodic signal for one period of the pinch roll, and receives the actual pressing force or torque detected from the pinch roll 42 as an input, and the periodic gap disturbance due to the eccentricity of the pinch roll 42 is a gap. Estimated as a fluctuation estimate.

  Here, the configuration of the disturbance estimator 62 will be described. First, when the transfer function expressing the response from the instruction of the pinch roll 42 to the pressing force is modeled as a first-order lag, equation (1) is established.

(D / dt) x = − (1 / T) x + K (u + d ₂ )
y = (1 / T) x
(1)
here,
x: State variable T: Time constant (sec)
K: Mill constant (ton / mm)
y: Pushing force (ton)
u: Pinch roll gap indication value (mm)
d ₂ : Gap disturbance (mm) due to eccentricity of the pinch roll 42

  Further, since the period of the disturbance is a period of one rotation of the pinch roll 42, the angular frequency ω shown in the equation (2) is obtained.

ω = V / r (2)
here,
V: Peripheral speed of pinch roll 42 (m / sec)
r: radius of the pinch roll 42 (m)

  Therefore, the angular frequency ω may be made variable according to the peripheral speed (speed) V of the pinch roll 42, and a table or the like may be referred to.

  The disturbance dynamics can be expressed by equation (3).

  When the expressions (1) and (3) are put together, the state space expression shown in the expression (4) is obtained.

By configuring a generally known state estimator (observer) for this equation (4), d ₂ that is the gap disturbance of the pinch roll 42 can be estimated.

  For simplicity, the expression (4) is expressed as the following expression (5).

  At this time, the state estimator for estimating the state vector z is as shown in Equation (6).

Here, L is a gain matrix selected so that the real part of the pole of A−L · c is negative. An element d _{2 of} the estimated state quantity z ^ (^ is on z) is an estimated value of gap fluctuation due to eccentricity of the pinch roll 42. By subtracting this estimated value from the gap command value that becomes the reference pressing force in the calculator 61 and taking the deviation, the influence of the eccentricity of the pinch roll 42 can be removed and the pressing force can be stabilized as the reference pressing force. .

  Thus, according to the second embodiment, in the pressing force control of the pinch roll 42 for maintaining the steel plate tension TPR at the reference value, the eccentric period of the pinch roll 42, that is, the outer peripheral length of the pinch roll 42 is set. Since the disturbance estimator 62, which is a corresponding signal generation mechanism, is used, gap control synchronized with the eccentricity period of the pinch roll 42 becomes possible, and the influence of the eccentricity of the pinch roll 42 is completely eliminated. Can do.

The effect of the first embodiment was confirmed by comparing the control method according to the first embodiment with the conventional method that does not use the repetitive controller 52 in FIG. Here, the simulation condition is
Pinch roll radius: 0.45m
Pinch roll eccentricity: 20 μm
Mill constant: 23 ton / mm
Pinch roll peripheral speed: 10m / sec
Standard pressing force: 4000kg
It was.

  The comparison results are shown in FIG. According to this result, according to the control method of the first embodiment using the repetitive controller 52, the reference pressing force 4000kg can be stabilized without variation, whereas the conventional method has periodic variation remaining. I understand that.

  A simulation was performed for the control method of the second embodiment using the disturbance estimator 62. As a result, when the actual eccentricity of the pinch roll 42 is compared with the estimated value, it can be seen that the actual eccentricity matches the estimated value at an early stage, as shown in FIG. Then, it has been found that by using such an estimated value of the periodic eccentricity for the control, the reference pressing force can be controlled without fluctuation as shown in FIG.

  The present invention is not limited to the first and second embodiments described above. For example, in these embodiments, the pinch roll 42 of the winder 4 is controlled, and the roll gap is operated in synchronization with the eccentric period of the pinch roll 42 so that the steel plate tension TPR becomes the reference value. However, the roll gap of the finish rolling mill 2 is controlled by controlling the rolling load in synchronization with the eccentric period of the roll 21 so that the thickness of the material 3 to be rolled becomes a reference value. May be operated.

1A, 1B Hot rolling line 2 Finishing mill 21 Roll 3 Rolled material 4 Winding machine 42 Pinch roll 52 Repeat controller 62 Disturbance estimator

Claims (4)

A roll control method in a hot rolling line in which a material to be rolled that has been rolled by a finish rolling mill is wound by a winder,
By using a mechanism for generating a periodic signal by eccentricity of a roll that is provided in pairs and sandwiches the material to be rolled, by operating the gap of the roll in synchronization with the periodic signal generated by the mechanism for generating the periodic signal, A roll control method in a hot rolling line, characterized in that the sandwiched state of the roll is maintained at a target value.   The roll control method in a hot rolling line according to claim 1, wherein the period of the periodic signal is variable according to the peripheral speed of the roll.   The roll control method in a hot rolling line according to claim 1 or 2, wherein the generation mechanism of the periodic signal is a repetitive controller.   The roll control method in a hot rolling line according to claim 1 or 2, wherein the periodic signal generation mechanism is a disturbance estimator.

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