JPH06304631A - Method for correcting roll opening of mill in metallic plate rolling - Google Patents

Abstract

PURPOSE:To optimize the quantity of correction for sinking of a cylinder by correcting an opening between rolls in accordance with a value obtained by estimating a bitten load pattern of the following pass and a sunk quantity of the cylinder from an actual passing load of the preceeding pass. CONSTITUTION:When a metal plate is rolled by a reversible rolling mill which can adjust a roll opening with a hydraulic rolling-down cylinder 5, the bitten load and its change pattern in the following pass are estimated from a rolling load when the preceeding pass passes through between the work rolls, a quantity DELTAS of correction for sinking of the hydraulic rolling-down cylinder 5 is obtained and a roll opening suitable to rolling of the following pass is obtained according to this quantity of correction for sinking. Further, the quantity DELTAS of correction (reference quantity of correction) for sinking is changed dynamically according to an actual biting speed. In this way, the deviation of plate thickness especially in the end part of the metallic plate 1 can be reduced extremely, adjustable correspondence can be taken to every metallic plate to be rolled and correspondence can be taken easily to an order severe in allowance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting the roll opening of a rolling mill in strip rolling, and more particularly, to determine the thickness deviation of the biting end of the strip to be rolled, It aims to improve the product quality by making it smaller by correcting it quickly.

[0002]

2. Description of the Related Art In strip rolling, it is general to install a hydraulic pressure reducing device capable of high response in order to improve the precision of strip thickness. However, since the hydraulic pressure reduction device uses hydraulic oil, there is a problem that the cylinder sinks due to the compression of the oil when the plate material is bitten, which adversely affects the plate thickness accuracy. And as a countermeasure for this, the opening of the roll is corrected (the opening of the roll is made slightly smaller) by an amount corresponding to the sinking amount of the cylinder before the plate material is caught in the roll of the rolling mill, The bite correction control for returning the roll opening adjusted by the correction immediately after the biting is generally performed, and the correction control mainly has the following two patterns.

1. Determine and control empirically. That is,
The correction amount and the correction time are empirically determined and controlled from the plate thickness, plate width, slab size, slab heating conditions, etc. and the plate thickness deviation at the plate edge after actual rolling. 2. The amount of oil column subsidence ΔS is calculated by predicting the amount of elasticity change of the oil in the cylinder, and control is performed based on this.

## EQU1 ## ΔS = αV ₀ {(F / 2A) ・ (1 / K) ・ (1 / A)} (1) where V ₀ : (oil volume in the cylinder) + (control Oil volume in the pipe from the valve to the cylinder) F: Predicted rolling load A: Cylinder area K: Oil bulk modulus α: Correction coefficient (≦ 1)

As a prior document relating to this point, JP-A-51
-48744, JP-A-58-167014, JP-A-59-183
Reference is made to the 915 publication and the like.

[0005]

Currently, in the field of strip rolling, various attempts have been made to improve the precision of strip thickness by introducing the above-described hydraulic pressure reducing device having high responsiveness.
Under the present circumstances, it was not possible to completely eliminate the sinking of the cylinder due to the elastic compression of the hydraulic oil when the plate material was bitten, and the development of a new method was desired. The amount of subsidence of the cylinder depends on the volume change of the hydraulic oil as shown in the above formula (1), and it is necessary to reduce the subsidence of the cylinder and to recover the subduction as quickly as possible. It is good to install the servo valve for controlling oil as close to the cylinder as possible, but the variation of the plate is large and the plate thickness deviation is much inferior to the steady part when the conventional method is applied. It was a thing.

An object of the present invention is to propose a new method capable of solving the above-mentioned conventional problems that have occurred in plate rolling and improving the plate thickness accuracy, particularly the plate thickness accuracy at the end portion of the plate material. .

[0007]

The present invention, when performing strip rolling using a reversible rolling machine whose roll opening can be adjusted by a hydraulic pressure reduction cylinder, bites in the next pass from the rolling load at the time of slippage in the previous pass. A plate rolling characterized by predicting a load and its change pattern, obtaining the amount of subduction correction of the hydraulic pressure reduction cylinder based on this, and correcting to a roll opening suitable for rolling in the next pass according to this subduction correction amount. In the present invention, the roll opening correction method of the rolling mill is defined as follows.
It is particularly desirable to change it dynamically according to the actual biting speed.

[0008]

The amount of depression of the cylinder at the biting end of the plate member is determined by the depression of the hydraulic oil during compression and the recovery by the supply of hydraulic oil from the servo valve.
Of these, the supply of hydraulic oil depends on the response of the cylinder's fixed position control system.Therefore, the steeper the rolling load rises when the plate material bites, the slower the recovery of the rolling load and the larger the cylinder's sinking amount. When the load rises slowly, the constant position control system of the cylinder can easily follow it, so the amount of depression is small.
By considering the above matters, it is possible to easily predict the rising pattern of the rolling load, and
If the amount of depression of the cylinder at this time (the amount of depression of the oil column) can be estimated, the amount of correction of the depression of the cylinder can be optimized.

FIG. 1 shows actual data of the biting load of the plate material and the sinking amount of the cylinder. The amount of subsidence of the cylinder has a substantial correlation with the load, but there are variations. Further, FIG. 2 is a graph showing the relationship between the load rise time at a specific load (about 4000 tons) and the depression of the cylinder. In FIG. 2, the faster the rise of the load is, the greater the depression of the cylinder is.

From the results shown in FIG. 1 and FIG. 2 above, using both parameters to predict the amount of depression of the cylinder,
The prediction formula is as follows.

[Formula 2] ΔS _max = 0.13 × F _max −3000 · Δt (2)

Further, the rise time of the rolling load in the next pass can be predicted from the load at the trailing edge of the previous pass and the rolling speed.

The basic control procedure of the present invention will be described below by taking thick plate rolling as an example. Plate rolling is reversible rolling and multi-pass rolling. Therefore, to predict performance of the pass before Shirinuke load F _1max from _(p) and the biting force F _{2max (p)} follows the path as follows (see Figure 3).

[ _Formula 3] F _{2max (p)} = F _{1max (p)}・ {(Next pass predicted average load) / (Previous pass actual average load)} (3) Where, next pass predicted average load: Prediction by reduction schedule Load Subscript 1: Previous pass Subscript 2: Next pass (P): Forecast (R): Actual

The load rising time Δt _{2 (p)} can be calculated as follows.

[Formula 4] Δt _{2 (p)} = Δt _{1 (R)} · (V _{2 (p)} / V _{1 (R)} ) ... (4) where V _{1 (R)} : trailing edge speed (actual) V _{2 (p)} : Biting speed (estimate) Δt _{1 (R)} : Load rise time when slipping out

On the other hand, the cylinder sinking correction amount ΔS _{2 (p)}
Can be calculated from the following equation based on equation (2) above.

[Formula 5] ΔS _{2 (p)} = 0.13 × F _{2 max (p)} −3000 · Δt _{2 (p)} (5)

Although the above formula (5) is a simple formula, it is possible to further improve the accuracy by collecting a large amount of actual data. According to ΔS _{2 (p)} , the roll opening is performed before the next pass is caught. Correct the degree.

Although the present invention basically performs rolling in accordance with such a procedure, the subduction correction amount Δ _{2 (p)} obtained by the above equation (5 ₎ uses the predicted biting speed. Due to operator intervention, an error may occur in the above speed measurement. Therefore, even in such a case, it is preferable that the material is dynamically corrected by using the actual speed of the material being conveyed to the rolling mill so that an appropriate correction amount is obtained.

FIG. 4 shows the configuration of a control system of an apparatus suitable for carrying out the present invention. This system is capable of finely capturing the load change at the biting end and the trailing edge of the plate material. In addition, the controller enables high-speed sampling, and the rolling speed is incorporated into the hydraulic pressure control panel so that the speed can be dynamically corrected with respect to the subduction correction amount ΔS from the upper process computer (P / C). Is. In the figure, reference numeral 1 is a plate material to be rolled, 2 is a work roll of a rolling mill, 3 is a backup roll, 4 is a load cell, 5 is a hydraulic pressure reduction cylinder, 6 is a cylinder position detector, and 7 is a hydraulic pressure reduction control. Board, 8
Is a servo amplifier, 9 is a servo valve, 10 is hydraulic piping, 11 is a hydraulic source, 12 is a process computer, 13 is a controller,
14 is a motor and 15 is a speed detector.

FIG. 5 shows the configuration of a control system for correcting the current subsidence. This system corrects the opening degree of the roll before the feed plate material 1 is caught in the hydraulic pressure control panel 7 through the controller 13 from the upper process computer 12 through the cylinder oil column subsidence correction amount ΔS and the correction time Δt.
After Δt seconds after the plate has been bitten, the correction command is cut off and the control for returning to the original roll opening degree is entered, and at the same time, AGC (Automatic Gauge Control) control for compensating the load fluctuation is entered.

[0019]

Example A sheet material (steel type SS400) having a thickness of 16 mm, a width of 3048 mm and a length of 38234 mm was rolled by applying the apparatus having the control system shown in FIG. As a result, when rolling is performed by the control system shown in FIG. 5, the sheet thickness deviation at the end is σ = 18.
Although it was 0 μm, σ = 120 μm according to the present invention, and it was confirmed that the degree of quality improvement was very high.

[0020]

According to the present invention, the biting load pattern of the next pass and the amount of subsidence of the cylinder are predicted from the actual trailing trail load results of the previous pass, and the roll opening is corrected based on this. By optimizing the amount of cylinder subsidence correction, the plate thickness deviation, especially at the edges of the plate material, can be made extremely small (the yield can be improved by reducing the amount of cut-off). Further, according to the present invention, it is possible to appropriately deal with each plate material to be rolled, and it is possible to easily deal with an order with a strict tolerance.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a biting load of a plate material and a sinking amount of a cylinder.

FIG. 2 is a graph showing the relationship between the load rise time and the amount of depression of the cylinder.

FIG. 3 is an explanatory diagram of a roll opening correction procedure according to the present invention.

FIG. 4 is a diagram showing an example of a correction control system according to the present invention.

FIG. 5 is a diagram showing an example of a correction control system currently used.

[Explanation of symbols]

 1 plate material 2 work roll 3 backup roll 4 load cell 5 hydraulic pressure reduction cylinder 6 cylinder position detector 7 hydraulic pressure reduction control panel 8 servo amplifier 9 servo valve 10 hydraulic piping 11 hydraulic power source 12 process computer 13 controller 14 motor 15 speed detector

Claims (2)

[Claims] 1. When performing strip rolling using a reversible rolling mill whose roll opening can be adjusted by a hydraulic pressure reduction cylinder, the biting load and its change pattern in the next pass are predicted from the rolling load when the trailing edge of the previous pass is removed. Based on this, the amount of subduction correction of the hydraulic pressure reduction cylinder is obtained, and according to the amount of subduction correction, the roll opening is corrected to a roll opening suitable for rolling in the next pass. Method. 2. The subduction correction amount (reference correction amount) is dynamically changed according to the actual biting speed.
The method described.