JPS6018213A - Shape controlling method in rolling mill - Google Patents

Abstract

PURPOSE:To control properly the sheet shape and sheet crown of a steel strip by inputting the detecting values of a crown meter and a shape meter located respectively at the exit of a rolling mill to a feedback control device and correcting a bending force of each stand, in rolling the strip by a tandem finishing mill. CONSTITUTION:In rolling a steel strip 4 by a six-stage tandem finishing mill, the sheet crown and sheet shape of the strip 4 are detected by a crown meter 8 and a shape meter 9 arranged respectively at the exit of the mill, to input the detected results to a feedback control device 7. The device 7 outputs an additional signal, basing on these sheet crown and sheet shape, to the bending-correcting output of a predictive control device 6 which houses a model equation for predicting the thermal crown of a roll with the passage of time, to perform a feedback control. The rolling material 4 is rolled by correcting the deviation of a bending force by the work roll of each stage, to obtain a sheet material having prescribed sheet shape and sheet crown at the exit.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a finishing mill for a hot strip steel rolling mill, and is particularly suitable for obtaining a desired plate shape and plate crown [Background of the Invention] Conventional rolling The plate shape and plate crown control device installed in the machine adjusts the initial settings of the rolling mill dimensions, the width of the rolled material, rolling schedule, roll profile, etc.
In order to obtain the target plate crown and plate shape, control parameters such as the axial movement amount of the roll pending cutter intermediate roll and work roll are determined by a calculator, and after initial setting of each parameter, the plate shape on the exit side is determined. Control was performed by feedback of the plate crown and plate crown. However, since the roll profile changes over time due to heat generation and cooling due to rolling and wear, it is difficult to take the roll profile into account in predictive control, and feedback control has become increasingly dependent on the roll profile. Therefore, there is a drawback that the plate shape and plate crown deviate from the target values due to a delay in control.

Also, according to (Kawasaki Steel Technical Report, 1979 issue), the amount of diametric thermal expansion of a work roll is expressed by a certain hyperbolic tangent formula, and compared to experimental values and strictly calculated values using the finite element method, It has been reported that the rolling part can be accurately approximated by the above formula. However, as stated in the same report, this approximation formula has poor accuracy in the rolled part and does not take into account the axial movement of the work rolls. The work roll shift mill (hereinafter referred to as a work roll shift mill) has the disadvantage that the accuracy immediately after the work roll is moved makes it impossible to apply the above approximation formula.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, an object of the present invention is to provide a required plate corresponding to each stage of a rolling mill, and to apply a rolling load to each stage when a material to be rolled passes through the rolling mill. A predictive control device that takes in the deviation and roll crown deviation and corrects the pending force of the corresponding stage; and a predictive control device that takes in the plate shape and plate crown of the rolled material on the exit side of the rolling mill and adjusts the bending correction output of each of the predictive control devices. In a rolling mill shape control device comprising a feedback control device for correction, a model equation for predicting the thermal crown of the roll over time is stored in the predictive control device, and the predictive control device adjusts the thermal crown over time based on this model equation. The above object is achieved by employing a control method that modifies the pending force while taking into account changes in the roll crown.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a rolling mill to which the rolling mill shape control method of the present invention is applied, and shows a 6-high tandem finishing mill of a hot steel strip rolling mill. There are 6 rolling machines
The first stage is Fl, the second stage is F2, etc.
...The 6th row is written as F6.

F1 to F3 are four-stage work roll shift mills consisting of a pair of work rolls 1 that are movable in the axial direction and a pair of reinforcing rolls 2 disposed outside of the work rolls 1. F4 to F6 are six-high rolling mills each having a pair of axially movable intermediate rolls 3 between a pair of work rolls 1 and a pair of reinforcing rolls 2. F
The rolling mills of each stage from 1 to F6 are controlled by a setup control device 5.
The setup is controlled by Also, PI ~ F6
Each stage up to is provided with a corresponding predictive control device 6, and these predictive control devices 6 take in rolling load deviation and roll crown deviation from each corresponding stage, and send a signal to correct the pending force of each stage. Output. A crown meter 8 and a shape meter 9 are provided on the exit side of the rolling mill F6 to detect the plate crown and plate shape of the rolled material 4 and output detected values to the feedback control device 7. The feedback control device 7 outputs an addition signal to the bending correction output of the predictive control device 6 at each stage based on the plate crown and plate shape.

Next, the plate shape and the control operation of the plate crown will be explained. First, depending on the rolling schedule of each stage, the width of the rolled material, the roll initial crown, etc., the initial value is the pending force of work roll 1, the amount of movement of work rolls F1 to F3, and the amount of movement of intermediate rolls F4 to F6. is set up by the setup control device 5. Next, the rolled material 4 is passed through the plate, and the rolling load deviation and roll crown deviation at Fl are taken in, and the predictive control device 6 corrects the pending force of Fl, and the plate crown ratio deviation of each stage obtained by calculation. and the deviation of the elongation rate difference are transmitted to the predictive control device 6 of F2. The F2 predictive control device 6 takes in the rolling load deviation and roll crown deviation at F2, and
Fix the role-pending card. Similarly, the predictive control device 6 of each stage corrects the roll pending force of each stage, and the tip of the plate of the rolled material 4 exits F6. Furthermore, the feedback control device 7 takes in the plate crown and plate shape from the crown meter 8 and shape meter 9 provided on the exit side of the F6, and based on these plate crown and plate shape, the predictive control device 6 of each stage An addition signal is sent to the bending correction output of the controller to perform feedback control. Therefore, the material to be rolled 4 passes between the pair of work rolls 1 of the rolling mill of each stage, and is finally rolled to the desired plate thickness on the exit side of the sixth rolling mill. .

Next, a predictive model for thermal crown, which is one element of roll crown deviation, used by the predictive control device 6 will be described. The authors devised the following equation to approximately express the amount of thermal expansion (thermal crown) of a work roll.

T+(x)=C-tan-'(exp (1(1・Z
I(X)I) ・ZI(X)Dπ 2 A+ = −10b Ll.

B/ = (1-exp (-pntn))13+
+exp (-pn tn)B+-, where T is the amount of thermal expansion per radius of the work roll (μ), X is the roll axial distance from the center of the mill (w++), and u is the heat per radius at the center of the mill. Expansion amount (μ), α is heat radiation coefficient (1/sec)
It depends on the amount of coolant, temperature of the rolled material, width of the plate, material quality, etc.
tR is the rolling time (seconds), 1c is the idling time (seconds), u- is the amount of thermal expansion per diameter (μ) at the center of the roll at 1R-■, and the material, plate width, and temperature of the rolled material. etc., uO = 0 (initial value), a, b, c are constants, β is the heat input coefficient (1/sec), which is determined by the width, temperature, material quality, etc. of the rolled material, B is the rolling Lumber plate width (mm), R
is the work roll radius (rnrn), ρB is the influence coefficient due to plate width change, γ is the influence coefficient due to work roll shift, tB is the time (seconds) after changing the rolled material plate width, Δδws is one work roll shift) quantity (Third), ts indicates the elapsed time (seconds) after the work roll shift l-. Note that the subscript 1 represents constants and variables related to one rolled material. The predictive control device 6 of this embodiment determines the work roll crown over time using the above approximate equation and outputs a bending correction signal to each stage.

The above approximation formula makes it possible to predict changes in the roll crown over time, including the thermal crown, and the results agree well with actual measurements and the exact solution obtained by the finite element method. As a result, the predictive control device 6 using the JJ equation described above can perform more accurate predictive control including the influence of the work roll shift, and the amount of feedback control from the feedback control device 7 can be reduced accordingly. It is possible to roll products with plate crowns and plate shapes.

According to this embodiment, a model formula that can predict the amount of thermal crown is stored in the predictive control device 6, and the predictive control device 6 performs control to correct the pending force of each stage of the rolling mill using this predictive model formula. As a result, the amount of feedback from the feedback control device 7 can be reduced, the responsiveness of the control can be improved, and control can be easily performed to obtain the desired shape and plate crown of the rolled material 4 with high precision.

〔Effect of the invention〕

As described above, according to the rolling mill shape control method of the present invention, the pending force of each stage of the rolling mill is controlled while predicting the thermal crown of the roll over time using a model equation that can predict the amount of thermal crown. By making corrections using a predictive control device, it is possible to obtain the desired plate shape and plate crown with high precision.

[Brief explanation of the drawing]

The figure is a configuration diagram showing an embodiment of a rolling mill to which the rolling mill shape control method of the present invention is applied. 1... Work roll, 2... Reinforcement roll, 3...
Intermediate roll, 4... Rolled material, 5... Cent-up control device, 6... Predictive control device, 7... Feedback control device, continued from page 1 0 Inventor: Yahitachi 3-1-1 Ichisaiwai-cho, 502 Kandate-cho, Tsuchiura City, Hitachi, Ltd. Mechanical Research Laboratory ■Applicant: Hitachi, Ltd. No. 5-1, Marunouchi-chome, Chiyoda-ku, Tokyo Procedural amendment (method) ) % formula % Indication of the case 1982 Special iQ Application No. 128184 Name of the invention Relationship with the person who corrects the shape control method of a rolling mill Name of the patent applicant (!1101 Body type association U: 8 Work Name: Nisshin Steel Co., Ltd. Agent Address: 100) No. 5-1, Kunouchi-chome, ChiyouJ-ku, Tokyo Subject of amendment 1: Documents proving authority of representation or more

Claims (1)

[Claims] (2) A predictive control device that is provided corresponding to each stage of the rolling mill and corrects the pending force of the corresponding stage by incorporating the rolling load deviation and roll crown deviation of each stage when the material to be rolled passes through; A shape control device for a rolling mill comprising a feedback control device that takes in the plate shape and plate crown of the rolled material on the exit side of the rolling mill and corrects the bending correction output of each of the predictive control devices. A shape control for a rolling mill, characterized in that a model formula for predicting thermal crown over time is stored, and the predictive control device corrects the pending force based on the model formula while taking into account changes in the roll crown over time. Method.