KR100273949B1 - Device and method for control of thickness of plate in cold rolling - Google Patents

Abstract

PURPOSE: An apparatus and method for controlling a thickness of a sheet when increasing or reducing speed of continuous cold rolling are provided which agrees a sheet thickness of the outlet of a rolling mill with a target sheet thickness by carrying out efficient controlling in the increasing or decreasing speed sections of the continuous cold rolling. CONSTITUTION: The apparatus for controlling a thickness of a sheet when increasing or reducing speed of continuous cold rolling comprises a rolling load detecting means (40) detecting a rolling load (P); a rolling speed detecting means (30) detecting a rolling speed (V); increasing or decreasing speed judging means judging whether a rolling section is an increasing or decreasing speed section; a memory means (10) remembering rolling variables, an oil film thickness of a supplementary roll and a friction coefficient; a rolling variable calculation means calculating a thickness variation of an oil film of the supplementary roll and a variation between a work roll and a rolling plate; a roll gap compensation calculation means calculating a roll gap compensation from the oil film thickness of the supplementary roll, the friction coefficient, the thickness variation of the oil film of the supplementary roll, the friction coefficient variation, the rolling load (P) and the rolling speed (V); a roll gap control actuator (200) controlling a roll gap according to the roll gap compensation; and a repeating means repeating the roll gap controlling again when the difference therebetween exceeds a certain control cycle by comparing a past velocity with a present velocity, wherein the thickness variation of the oil film and the friction coefficient variation are calculated according to the following Formulae 1 and 2: (Formula 1) (Formula 2) where l is a distance between a diameter of the neck part of a supplementary roll and an inner diameter of a bearing sleeve, and g is a minimum oil film thickness.

Description

Device thickness control device and method during acceleration and deceleration of cold rolling

The present invention relates to an apparatus and a method for controlling plate thickness during acceleration and deceleration of rolling speed inevitably generated in continuous cold rolling.

In recent years, most of the cold rolling process is continuous with the pickling line or the continuous annealing line as well as the continuity between coils. In the continuous rolling mill of the cold rolling mill that continuously rolls between coils, after the cold rolling is completed, the welded portion is cut and re-wound for the transfer to the post process. Therefore, in order to cut the material, the rolling speed should be slowed down (normally 200 m / min) than the normal rolling speed (usually 1400-1500 m / min) and accelerated to the normal speed for the next coil rolling after the cutting operation. Therefore, in continuous rolling, deceleration and acceleration of rolling speed necessarily occur. 1 shows such acceleration and deceleration sections and normal speed sections. In other words, the continuous rolling mill operated at the normal rolling speed should reduce the rolling speed (deceleration section) when it reaches the cutting point, and after cutting, it should be accelerated (acceleration section) to reach the normal rolling speed after rolling. However, the thickness of the plate is not effectively controlled in the acceleration and deceleration section. Figure 2 is a chart of the thickness change over the entire length of the rolled plate measured in the actual rolling, it can be seen that the thickness deviation occurs severely in the deceleration section of the front end and the acceleration section of the rear end. Therefore, there is a need for an apparatus and method for effectively controlling the plate thickness in the acceleration / deceleration section of the rolling speed.

The present invention provides a sheet thickness control device and a control method for deceleration of continuous cold rolling, which effectively control the acceleration / deceleration section of the continuous cold rolling of the present invention to match the plate thickness on the rolling mill exit side with the target plate thickness.

An object of this invention is rolling load detection means for detecting a rolling load (P) on the plate; Rolling speed detecting means for detecting a rolling speed V; Acceleration / deceleration determination means for determining whether the rolling section is an acceleration / deceleration section; Several rolling parameters for calculating rolling parameters, the above rolling speed (V) and the set film thickness (δ _o ) of the reinforcement roll at the normal rolling speed (Vs) and the coefficient of friction between the working roll and the rolling plate (μ) storage means for storing _o ); Between the rolling load P obtained from the rolling load detection means, the rolling speed V obtained from the rolling speed detection value, and various rolling parameters of the storage means and the oil film thickness change amount δ of the reinforcing roll and the work roll and the rolling plate. Rolling variable calculation means for calculating a friction coefficient change amount [mu]; The oil film thickness (δ _o ) of the reinforcement rolls obtained by the storage means and the rolling parameter calculation means, the friction coefficient (μ _o ) between the work roll and the rolling plate, the amount of change in the film thickness of the reinforcement roll (δ) and the work roll; Roll gap compensation amount calculating means for calculating a roll gap compensation amount from the friction coefficient change amount between the rolled plates and the rolling load P and rolling speed V; A roll gap control actuator for controlling a roll gap in accordance with the roll gap compensation amount obtained by the roll gap compensation amount calculating means; Among the continuous rolling speeds stored in the storage means, the past speed Vpa is compared with the present speed Vpr obtained from the rolling speed detector, and if the difference exceeds a certain control period, the above roll gap control is repeatedly performed. It is achieved by a control device for a continuous cold rolled sheet thickness comprising a means for.

In addition, an object of the present invention is the process of determining whether the rolling speed is the acceleration / deceleration section; In the case of acceleration / deceleration section, the rolling load (P) obtained from the rolling load detector, the rolling speed (V) obtained from the rolling speed detector, and the variation of the film thickness of the reinforcement roll (δ) from the various rolling parameters stored in the storage unit and the work roll; A rolling variable calculation process of calculating a friction coefficient change amount between the rolling plates; The oil film thickness (δ _o ) of the reinforcement roll obtained by the storage means and the friction coefficient (μ _o ) between the work roll and the rolled plate, and the oil film thickness change amount (δ) of the reinforcement roll obtained in the rolling parameter calculation process, and the work roll and rolling A roll gap compensation amount calculation process of calculating a roll gap compensation amount from a friction coefficient change amount between the plates and the rolling load P and the rolling speed V obtained from the rolling load measuring device and the rolling speed measuring device; A roll gap control process of controlling a roll gap according to the roll gap compensation amount obtained by said roll gap compensation amount calculating means; Among the continuous rolling speeds stored in the storage means, the past speed Vpa is compared with the present speed Vpr obtained from the rolling speed detector, and if the difference exceeds a certain control period, the above roll gap control is repeatedly performed. It is achieved by the method of controlling the continuous cold rolled sheet thickness, including the process of.

1 is a view showing an acceleration and deceleration interval inevitably generated in the continuous cold rolling;

2 is a view showing a deviation of the plate thickness occurring in the acceleration and deceleration section in the conventional rolling control;

3 is a block diagram showing a configuration of an embodiment according to the present invention;

4 is a view showing a state attached to the existing rolling mill of the embodiment of the present invention;

5 shows a table of constant values used in determining a roll gap compensation amount;

6 shows the principle that the plate thickness is determined during cold rolling;

7 shows the principle upon which the invention is based;

8 is a flow chart showing the operation of the central processing unit in the embodiment of the present invention;

Figure 9 shows the specifications at the time of testing the examples of the present invention;

10 is a view showing the experimental results of the present invention when rolling speed acceleration; And

11 is a view showing the experimental results of the present invention when rolling speed reduction.

<Explanation of symbols for main parts of drawing>

10: memory 20: input device 30: rolling speed measuring instrument

40: rolling load measuring instrument 150: central processing unit 200: roll gap control actuator

DETAILED DESCRIPTION Examples of the present invention will now be described with reference to the accompanying drawings.

3 shows a block diagram of an example in which the invention is practiced. The central processing unit 15 is connected to a rolling load (P) measuring device 40, a rolling speed (V) measuring device 30, and an input device 20. In addition, the central processing unit 150 is connected to the storage unit 10, and is connected to the roll gap control actuator 200 at its output end. The rolling load P detected by the rolling load measuring device 40 and the rolling speed V detected by the rolling speed measuring device 30 are input to the central processing unit 150. The storage unit 10 stores various parameter values set through the input device 10, and also stores a rolling load P and a rolling speed V. FIG. The storage unit 10 also stores a program such as an operation procedure of the central processing unit 150. Various values stored in the storage unit 10 may be converted through an input unit. The central processing unit 150 is configured around a micro-processor and reads various values from the rolling load measuring device 40, the rolling speed measuring device 30, and the storage units 10 as described below. Perform the operation. The roll gap control actuator 200 which performs the roll gap control connected to the output end of the central processing unit 150 changes the vertical displacement of the reinforcement roll (15 'in FIG. 4), thereby causing gaps between the work rolls 5 and 5'. In this embodiment, a hydraulic cylinder is used to change the pressure (see Fig. 4).

The storage unit 10 continuously stores the rolling speed provided from the rolling speed measuring device. The central processing unit 150 reads the past velocity (Vpa) of a certain time ago (for example, the rolling speed inputted 0.5 seconds ago) from the continuously stored rolling speed, and also reads the current from the rolling speed measuring device 30. Read the present velocity (Vpr) and compare their values to determine whether there is acceleration (ie, whether deceleration or acceleration is present). If there is a difference between the present speed and the past speed and an acceleration exists, the following control is performed as the acceleration / deceleration section.

The central processing unit 150 is a rolling variable from the rolling load P obtained from the rolling load measuring device 40 and the rolling speed measuring device 30, the current rolling speed Vpa, and various rolling parameter values stored in the storage unit 10. The calculation is performed to calculate the oil film thickness change δ of the reinforcing roll changed during the rolling process and the friction coefficient change μ between the work roll and the rolling plate. The above operation is calculated according to the following equations.

[Equation 1]

[Equation 2]

[Equation 3]

Where ℓ is the distance between the reinforcement roll neck diameter and the bearing sleeve inner diameter

D is inner diameter of reinforcing roll bearing sleeve

B is the reinforcement roll sleeve width, g is the minimum film thickness

(eta) is a bearing oil film viscosity, and it is as above-mentioned that they are stored in the memory | storage part 10 via the input device 20 as a set value.

Thereafter, the central processing unit 150 is formed between the oil roll thickness δ _o of the reinforcing roll bearing film thickness reinforcing roll and the work roll and the rolling plate at the normal rolling speed, which is a set value stored in the storage unit 10 through the input unit 20. Read the coefficient of friction (μ _o ). Then, the roll gap using the pressure load (P), the current rolling speed (Vpr) and the oil film thickness change amount (δ) of the reinforcement roll obtained from the calculation of the rolling parameters and the friction coefficient change amount (μ) between the work roll and the rolling plate The compensation amount S is calculated (60). To calculate the roll gap compensation amount, the following equation is used.

[Equation 4]

Where K is the stiffness of the rolling mill, δP / δμ is the sensitivity to the friction coefficient of the rolling load, the size according to the rolling speed is calculated using the following equation. The values of C ₀ , C 1, C ₂ , and C 3 are as shown in the table of FIG. 5.

[Equation 5]

The roll gap compensation amount obtained by the central processing unit 150 is output to the roll gap control actuator unit 200 to compensate for the roll gap. In this embodiment, the roll gap control actuator is composed of a servo valve 23 for converting an electrical signal into a mechanical signal and a hydraulic cylinder 13 for compensating a roll gap by changing displacement of the reinforcement roll (FIG. 4).

The control described above is divided into a constant rolling speed range and repeatedly adjusts the roll gap every time the rolling speed range is reached. For example, the control cycle is set repeatedly so that the roll gap is adjusted once each time the rolling speed is accelerated by 50 m per minute. A method of repeatedly performing such control cycles will be described in detail with reference to the flowchart of FIG. 8 below.

The following briefly describes the principle of roll gap compensation, which is the background of the present invention.

It is a conceptual diagram which shows the characteristic of plate rolling. When the roll gap of the rolling mill is set to S and the material having the thickness H is rolled, rolling is performed at the first point where the elastic curve EL (Elastic Line) of the rolling mill and the deformation curve PL (Plastic Line) of the raw material meet. At this time, the point h1 where the intersection point 1 meets the horizontal axis becomes the thickness after the rolling of the raw material, and the point where it meets the vertical axis becomes the rolling load P. However, if the elastic curve EL is moved to EL 'or the plastic curve PL is moved to PL' due to external factors or both are out of the normal state, the thickness of the rolled product is changed to h2, h3, h4, etc. The deviation occurs from the thickness h1.

In the case of deviation from the normal state as described above, a control for compensating for the roll gap can be performed to achieve a desired target thickness. This will be described with reference to FIG. 7. If the elastic curve or the plastic curve is changed in the normal rolling state and a deviation occurs from the target plate thickness, the elastic curve can be compensated to obtain the required target thickness. That is, in Fig. 7, when the elastic curve EL or the plastic curve PL is deformed to EL 'or PL' due to external factors and the thickness of the material causes a deviation of h to the second point instead of the first point, the elastic curve is EL " When moved, the point is re-intersected at the third point and h, orthogonal to the horizontal axis of the third point, becomes the thickness after rolling, so that the target thickness value can be achieved. Therefore, the elastic curve is moved by compensating the roll gap to control the rolling thickness, and accordingly, the present invention is to control the plate thickness by changing the elastic curve of the rolling mill by adjusting the roll gap. The equations are all obtained experimentally and show an excellent effect on plate thickness control as shown below (see FIGS. 10 and 11).

The operation of the central processing unit 150 in the present embodiment will be described with reference to FIG. 8.

First, the central processing unit 150 reads the current rolling speed Vpr and the past rolling speed Vpr stored in the storage unit 10 from the rolling speed measuring device 30 in step S1. Thereafter, these are compared in the step S2 to determine whether it is an acceleration / deceleration section. If it is determined that the current speed and the past speed are not equal to the acceleration / deceleration section, the rolling load P is received from the rolling load measuring device 40 in step S3 and the various rollings stored in the storage unit 10 are stored. The parameters are read out, and in step S4, the rolling variable calculation 50 is performed from the calculation formulas of (1), (2) and (3) to change the oil film thickness variation δ of the reinforcement roll and the working roll changed during the rolling process. The amount of change of the friction coefficient between the rolled plates is obtained. Subsequently, in step S5, the reinforcement roll bearing oil film thickness δ _o at the normal rolling speed and the friction coefficient μ _o between the work roll and the rolling plate are read from the storage unit 10, and the pressure load P described above is performed in step S6. And roll gap compensation amount (S) using the current rolling speed (Vpr) and the oil film thickness variation (δ) of the reinforcement roll obtained from the above calculation of rolling parameters and the friction coefficient variation (μ) between the work roll and the rolling plate (4). , (5) Obtained from the equation. The present roll gap compensation amount is then output to the roll gap compensation control actuator 200 (step S7). Next, the control period is set to perform the above control in a constant rolling speed change range, but FIG. 8 shows an example. First, in step S8, it is determined whether the acceleration section or the deceleration section is compared by comparing the past speed Vpa and the present speed Vpr. In the case of the deceleration section, when the current speed reaches the cutting speed (step S8), the roll deceleration control is terminated because the deceleration section is over, but if the cutting speed is not reached, step S11 is reached. Also, in the case of the acceleration section, if the current speed reaches the normal rolling speed Vs (step S10), it means that the acceleration section is finished, so the roll gap control is terminated, but otherwise, the flow proceeds to step S11. In step S11, it is determined whether a constant control period (that is, a constant rolling speed range change amount) has been reached. In this embodiment, the control period is 50 m / min. If the predetermined control period is exceeded, the above roll gap control is performed again. However, if it still remains within a certain control period (i.e. when the change in rolling speed has not yet reached 50 m / min in the case of acceleration, for example), step S12 is reached. In step S12, the current speed is replaced by the past speed, and the current rolling speed is read from the rolling speed measuring device 30 again. Thereafter, the process returns to step S8 to repeat the routine so that the above roll gap control is performed within a certain control period.

9 to 11 show computer simulation results of this embodiment. 9 shows the main specifications and rolling conditions of the cold rolling mill used. In addition, the acceleration / deceleration pattern starts rolling at 200 m / min, accelerates for 10 seconds, rolls at normal speed at 1500m / min, and deceleration is the same as acceleration, and decelerates at 200 M / min for 10 seconds. Let's do it. FIG. 10 and FIG. 11 show thickness deviations of respective stand shafts during acceleration rolling and deceleration rolling, respectively, in which a dotted line is a case where the present invention is not used and a solid line is the result of this embodiment. As shown in the figure, if there is no application of the present invention, there is a deviation from the target thickness value (the plate thickness becomes thinner than the target value in the acceleration rolling, and thicker than the target value in the case of the deceleration rolling). It can be seen that the deviation ratio is maintained at almost zero to achieve the target thickness without deviation even during acceleration and deceleration.

As described above, the present invention effectively controls the acceleration / deceleration section of the continuous cold rolling to match the plate thickness on the rolling mill exit side with the target plate thickness.

Claims (2)

An apparatus for controlling plate thickness during acceleration and deceleration of a rolling speed in continuous cold rolling, comprising: rolling load detection means for detecting a rolling load (P) applied to a sheet material; Rolling speed detecting means for detecting a rolling speed V; Acceleration / deceleration determination means for determining whether the rolling section is an acceleration / deceleration section; Rolling variables such as the gap between the diameter of the reinforcement roll neck portion and the inside diameter of the bearing sleeve, the inside diameter of the reinforcement roll bearing sleeve, the reinforcement roll sleeve width, the minimum oil thickness and the oil film viscosity, and the above rolling speed (V) and the normal rolling Means for storing an oil film thickness δ _O of the set reinforcement roll at a speed Vs and a coefficient of friction μ _O between the work roll and the rolled plate; From the rolling load P obtained from the rolling load detection means, the rolling speed V obtained from the rolling speed detection value, and the rolling parameters of the storage means, the amount of change in oil film thickness of the reinforcing roll from the working roll and the rolled plate Rolling variable calculating means for calculating; The oil film thickness (δ _O ) of the reinforcement rolls obtained by the storage means and the rolling parameter calculation means, the friction coefficient (μ _O ) between the work roll and the rolling plate, the amount of change in the film thickness of the reinforcement roll (δ) and the work roll, Roll gap compensation amount calculating means for calculating a roll gap compensation amount from the friction coefficient change amount between the rolled plates and the rolling load P and rolling speed V; A roll gap control actuator for controlling a roll gap in accordance with the roll gap compensation amount obtained by the roll gap compensation amount calculating means; Among the continuous rolling speeds stored in the storage means, the past speed Vpa is compared with the present speed Vpr obtained from the rolling speed detector, and if the difference exceeds a predetermined control period, the above roll gap control is repeatedly performed. It comprises a repeating means to make, wherein the oil film thickness change amount (δ) and the friction coefficient change amount (μ) is the following equation (1) and (2), (One) μ = 0.001 × exp [4.9 × (3.28 × V) ^0.038 ] (2) And l is the distance between the reinforcement roll neck portion diameter and the bearing sleeve inner diameter, and g is the minimum oil film thickness. CLAIMS What is claimed is: 1. A method of controlling plate thickness during acceleration and deceleration of a rolling speed in continuous cold rolling, comprising: determining whether the rolling speed is an acceleration / deceleration section; When the rolling speed corresponds to the acceleration / deceleration section, the rolling load (P) obtained from the rolling load detector, the rolling speed (V) obtained from the rolling speed detector, the diameter of the reinforcing roll neck portion stored in the storage unit and the bearing sleeve inner diameter From the rolling parameters such as the gap, the inner diameter of the reinforcement roll bearing sleeve, the width of the reinforcement roll sleeve, the minimum oil thickness and the oil film viscosity, the oil film thickness variation (δ) of the reinforcement roll and the friction coefficient variation (μ) between the work roll and the rolling plate are calculated. Rolling variable calculation step; Oil film thickness (δ _O ) of the reinforcement roll obtained by the storage means, friction coefficient (μ _O ) between the work roll and the rolled plate, oil film thickness change amount (δ) of the reinforcement roll obtained in the rolling parameter calculation process, and work roll A roll gap compensation amount calculating step of calculating a roll gap compensation amount from a friction coefficient change amount between the rolling plate and the rolling plate, and the rolling load P and the rolling speed V respectively obtained from the rolling load measuring device and the rolling speed measuring device; A roll gap control step of controlling a roll gap in accordance with the roll gap compensation amount obtained by said roll gap compensation amount calculating means; Among the continuous rolling speeds stored in the storage means, the past speed Vpa is compared with the present speed Vpr obtained from the rolling speed detector, and if the difference exceeds a predetermined control period, the above roll gap control is repeatedly performed. Control method of the continuous cold-rolled sheet thickness comprising a repeating step.