JPS60250816A - Method for controlling initial roll gap in cold rolling mill - Google Patents

Abstract

PURPOSE:To improve the prediction accuracy of rolling load and to control an initial roll gap to an adequate value by measuring the hardness of a material to be cold-rolled and predicting the rolling load by using the average deformation resistance calculated in accordance with the measured value. CONSTITUTION:The hardness of the position on an inlet coil 13 on a coil car 12 where the roll gap is initially set is measured by a Vickers hardness meter 11 disposed on the inlet side of a cold tandem rolling mill 3 and the measured value is inputted to a computer 14 for control. The average deformation resistance is then operated and the rolling load is calculated in accordance with the calculated average deformation resistance, the coefft. of friction, the sheet thickness on the inlet side of the stand and the sheet thickness on the outlet side of the stand. Arithmetic is then made in accordance with the rolling load, the sheet thickness on the outlet side of the stand and mill constant to calculate the roll gap for initial setting. Control devices 15a-15e for the draft position are controlled in accordance with the calculated roll gap, by which the draft positions of screw- down devices 10a-10e are set. The coil 13 is set in state to a feed side reel 2 and the rolling is started.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling the initial roll gap in a cold rolling mill, and in particular to a method for controlling the initial roll gap to an appropriate value by improving the accuracy of predicting rolling load. This is what I did.

[Prior art]

Generally, the roll gap S (mm) to be initially set in a cold rolling mill is calculated by a gauge meter method according to the following formula (1) based on a predicted rolling load P (ton).

5=h-(P/M)・・・・・・・・・・・・(1) Here, h is the thickness of the plate on the exit side of the stand (mm), and M is the Mill constant (
ton/mm).

As is clear from this equation (1), in order to calculate the appropriate roll gap S in the initial state of cold rolling, the rolling load P
prediction becomes an important factor. This rolling load P is generally calculated by calculating the following equation.

P=f (k, μ, h, hz)・・・・・・・・・・・・
・(2) Here, k is the average deformation resistance (kg/mm”)
, μ is the friction coefficient 1, h is the plate thickness at the entrance of the stand (mm),
h is the plate thickness (mm) on the exit side of the stand.

Further, in general, the average deformation resistance is expressed by the following equation (3).

-□・ko・(1ε.)n・・・・・・(3) Here, ko is the work hardening coefficient, t is the average total strain of the stand, and the thickness of the base plate and the thickness of the stand exit side. It is a function. ε
. is a strain correction coefficient, and n is a work hardening index.

In order to predict the rolling load using equation (2), it is necessary to calculate the average deformation resistance using equation (3).

The conventional prediction of average deformation resistance is ko, ε. , n are experimentally determined, using the values determined for each steel type, and C is the base plate thickness,
A common method was to calculate the average deformation resistance based on the thickness of the plate on the exit side of the stand, and use them to calculate the average deformation resistance according to equation (3).

[Problem that the invention seeks to solve]

However, in the conventional rolling load prediction method as described above, the average deformation resistance etc. required to calculate the rolling load P are predicted under predetermined calculation conditions depending on the steel type, etc. It was difficult to accurately estimate the rolling load P, and it was not possible to improve the prediction precision of the rolling load P. Therefore, the setting error of the roll gap becomes large, and an off-gauge occurs in the initial state until the roll gap is corrected to the correct one by an automatic plate thickness control device (AGC). In particular, even though the deformation resistance is the same steel type,
Due to hot rolling conditions (fluctuations in finishing temperature due to skid marks, etc., fluctuations in coiling temperature) and variations in strip components, fluctuations in the longitudinal direction between coils and within the coils are large (,
It was particularly difficult to estimate the value of deformation resistance at the location where the roll gap was set.

[Purpose of the invention]

This invention was made by focusing on the problems of the conventional method described above, and it measures the hardness of the cold-rolled material at the position where the initial setting of the roll gap is performed using a hardness meter, and uses this measurement value to prepare the material beforehand. By calculating the deformation resistance and using it to predict the rolling load, the rolling load prediction accuracy is improved, and the initial setting of the roll gap is performed with high precision, thereby solving the problems of the conventional method described above. It is intended to.

[Means for solving problems]

In order to achieve the above object, as a means to solve the problem, the present invention measures the hardness of the cold rolled material at the position where the initial setting of the roll gap is performed using a hardness meter,
The rolling load is predicted using the average deformation resistance calculated based on the measured value, and the initial roll gap is set based on the predicted rolling load.

〔Example〕

The present invention will be explained in detail below.

First, the outline of the present invention will be explained. There is a relationship between the hardness X and the yield stress y of the strip as shown in FIG. 2. This relationship can be expressed as the following formula.

y=ax...Fist...+41 Furthermore, the yield stress y can be expressed by the following formula.

y=to, ε. ”・・・・・・・・・・・・(5) Focusing on the above points, the present invention calculates the average deformation resistance k from the above equations (31, (4) and (5) according to the following equation. do.

Here, a is determined from the relationship shown in Figure 2, and ε. , n is determined by a tensile test etc. for each steel type, 100 is calculated from the base plate thickness and stand outlet side plate thickness, and X is measured by a hardness meter installed at the entrance side of the cold rolling mill.The average deformation resistance can be determined by k can be calculated.

Therefore, in accordance with the above relationship, the present invention measures the hardness at a longitudinal position of a strip as a material to be cold-rolled for initial setting of the roll gap using a hardness meter installed on the entrance side of a cold-rolling machine; By calculating the average deformation resistance using equation (6) using the value It is something.

Next, an example will be described in which the method of the present invention is applied to a five-stand cold tandem rolling mill.

That is, in FIG. 1, 1 is a strip as a material to be rolled, which is pulled out from a supply reel 2,
The sheet is rolled to a predetermined thickness by the roll stands 4a to 4e of the cold tandem rolling mill 3 and wound onto the tension reel 5. Each roll stand 4a-4e has work rolls 6a-5e.

7a to 7e and the bank unprowl 8 that connects these
a to 3e, 9a to 9e, and upper backup roll 8a
The work rolls 6a to 5e are provided with rolling devices 10a to 10e, each of which is constituted by, for example, a hydraulic cylinder, and which adjust the rolling blades by moving the rollers 6a to 8e up and down.

The strip 1 is inserted between 7a and 7e.

On the other hand, a Vickers hardness tester 11 is arranged on the entrance side of the cold tandem rolling mill 3, and this is used to determine the initial setting of the roll gap of the coil 13 placed on the coil car 12 and to be cold rolled. Measures hardness and outputs the measured value as a digital signal.

The lowering devices 10a to 10e are controlled by a control computer 1.
4, the lowering position control devices 158 to 15d are controlled by
controlled by The control computer 14 is supplied with the hardness detection signal from the hardness meter 11, calculates the deformation resistance by calculating the equation (6) based on this, and calculates the deformation resistance by (2
) to calculate the rolling load, and (11
Calculate the set value of the lowering position by calculating the formula.

Next, the processing procedure of the control computer 14 will be explained with reference to FIG.

The control computer 14 executes the process shown in FIG. 3 when the detection signal from the hardness meter 11 is supplied.

That is, in step (2), the detection signal of the hardness meter 11 is read, and this is temporarily stored as the hardness detection value X in a predetermined storage area of a storage device (not shown), and then the process proceeds to step (2).

In step (2), the hardness detection value X stored in step (2) is read, a is calculated from this and the previously stored characteristic curve shown in FIG. 2, and strain correction coefficient ε is determined for each steel type by a tensile test or the like. , calculate the average deformation resistance k by calculating the above equation (6) from the work hardening index n, the base plate thickness, and the stand exit side plate thickness, and temporarily store this in a predetermined storage area of the storage device. do.

Next, proceed to step (2), read the average deformation resistance k calculated in step (2), and calculate the equation (2) based on this, the previously stored friction coefficient μ, the stand entrance side plate thickness h1, and the stand exit side plate thickness h2. The calculation is performed to calculate the rolling load P, and this is temporarily stored in a predetermined storage area of the storage device.

Next, the process proceeds to step (2), where the rolling load P calculated in step (2) is read, and based on this and the pre-stored stand exit side plate thickness h2 and mill constant M, the above (11 formula) is calculated to calculate the roll gap. S is calculated and temporarily stored in a predetermined storage area of the storage device.

Next, the process moves to step (2), and the roll gap S calculated in step (2) is outputted to the rolling position control bags N15a to 15e as a roll gap setting value.

The timing at which the set value of the roll gap S is output from the control computer 14 to the rolling position control devices 15a to 15e is determined when the coil 13 measured by the hardness meter 11 is set on the supply reel 2 of the cold tandem rolling mill 3. It was selected when

Next, the effect will be explained. First, the distortion correction constant ε is stored in the control computer 14 in advance. , work hardening index n.

Figure 2 shows the coefficient a, average total strain, and friction coefficient μ
, stand entrance side plate thickness h1. Input the stand outlet side plate thickness h2 and the mill constant M, and store these in a predetermined storage area of the storage device. In this state, the hardness of the roll gap of the input coil 13 on the coil car 12 is measured using the Vickers hardness meter 11 placed on the input side of the cold tandem rolling mill 3, and the measured value Input to the control computer 14.

In this way, when the hardness measurement (liX) is input to the control computer 14, the process shown in FIG. 3 is executed.

For this purpose, first, the detection signal of the hardness meter 11 is read, and then the hardness measurement value X, the coefficient a, and the distortion correction constant ε are read. , based on the average total strain and the processing effect index n (6
) to calculate the average deformation resistance k.

Then, its average deformation resistance and friction coefficient μ.

The rolling load P is calculated by calculating the formula (2) based on the stand entry side plate thickness and the stand exit side plate thickness h2.

Next, the formula (1) is calculated based on the rolling load P, the stand exit side plate thickness h2, and the mill constant M to calculate the intended initial setting roll gap S, and based on this, the rolling position control is performed. By controlling the devices 158 to 15e, the rolling positions of the rolling devices fit 10a to 10e are set.

In this state, the coil 1 was measured using the hardness meter 11.
3 is set on the supply reel 2 and rolling is started, accurate initial rolling can be performed.

Incidentally, the conventional method (0°εO+ for the deformation resistance coefficient for each steel type)
Fig. 4 shows the test results for the first stand, where a comparison was made between 15 coils with the same steel type, base plate thickness, thickness at the exit side of each stand, and plate width between the method of the present invention and the method of the present invention. show.

As is clear from FIG. 4, in the case of the present invention, as shown by curve L+, it follows the measured value shown by curve L2. In this case, although the actual measured values are the same steel type, base plate thickness, stand exit side plate thickness, and plate width, the rolling load changes for each coil.
It can be seen that the present invention faithfully follows the actually measured values.

On the other hand, in the case of the conventional method, as shown by curve L3 in Fig. 4, the calculation conditions other than the friction coefficient are the same, so the rolling load P is a substantially constant value regardless of the properties of the coil, and the actual measurement value and multiplication are The values are far apart, making it impossible to perform accurate rolling.

In the above embodiment, the case where the present invention is applied to a cold tandem rolling mill 3 having five stands has been described, but the present invention is not limited to this, and any number of stands can be selected. Of course.

In addition, the hardness of the coil can be measured not only at the entrance side of the cold rolling mill but also at any location, and when the measured coil is set in the cold rolling mill, the hardness can be measured based on the measured value. (The roll gap may be controlled.

〔Effect of the invention〕

As explained above, according to the present invention, before starting cold rolling, the hardness at the position where the roll gap is initially set is measured using a hardness meter on the entrance side of the cold rolling mill, and based on the measured value. Calculate the deformation resistance, calculate the rolling load from this,
The roll gap for initial setting is calculated based on this rolling load, and the rolling position control device is controlled based on this roll gap, making it possible to predict the rolling load as a value that faithfully follows the actual measurement value. , it is possible to significantly improve the rolling load prediction accuracy and prevent off-gauge from occurring during the initial setting of the roll gap.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment to which the present invention can be applied, FIG. 2 is a characteristic curve diagram showing the relationship between hardness and yield stress, and FIG. 3 is a flowchart showing the processing procedure of the control computer. Fourth
The figure is a characteristic curve diagram showing the relationship between the predicted value and the measured value of the rolling load in the method of the present invention and the conventional method. 1... Strip, 2... Supply side reel, 3... Cold tandem rolling mill, 4a to 4e.
...Roll stand, 5...Tension reel, 6a to 5g. 7a-7e... Work roll, 10 a-10
e=-... Reduction device, 11... Hardness meter, 1
2...Coil car, 13...Inlet coil, 14...Control computer, 15a to 15-e
・・・・・・Down position control device. Patent applicant Kawasaki Steel Co., Ltd. Representative Patent attorney Tetsuya Mori Patent attorney Yoshiaki Naito Patent attorney Tadashi Shimizu Representative Patent attorney Kore Kajiyama

Claims (1)

[Claims] The hardness of the cold-rolled material at the position where the roll gap is initially set is measured using a hardness meter, the rolling load is predicted using the average deformation resistance calculated based on the measured value, and the initial roll is adjusted based on the predicted rolling load. An initial roll gap control method in a cold rolling mill characterized by setting a gap.