JPS5948690B2 - Rolling mill plate thickness control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheet thickness control method that maintains the thickness distribution in the sheet width direction of a rolled material in a regular shape and controls the rolling of a flat sheet.

In recent years, demands for rolled products with good shapes have become increasingly strict.

Currently, the shape is mainly controlled by a roll bending device, but this alone has a limited ability to control the shape, and it has been necessary to prepare various rolls with different initial crowns.

Recently, in order to increase the shape control ability, a new rolling mill has been developed that is equipped with a device that moves the rolls in the axial direction and is used in conjunction with roll bending, and the applicant has already filed an application for this rolling mill. .

(Japanese Unexamined Patent Publication No. 47-29260) Such a rolling mill as shown in FIG. 1 is hereinafter referred to as an HC mill.

In Fig. 1, 1 is an upper reinforcing roll, 2 is a movable upper intermediate roll, 3 is an upper work roll, 4 is a rolled material, 5 is a lower work roll, 6 is a lower intermediate roll which is also movable, and 7 is a lower reinforcement roll. It's a roll.

As shown in the figure, in the HC mill, by installing the ends of the intermediate rolls 2 and 6 within the work roll barrel, the roll bending effect by the penting devices 8 and 9 is significantly increased, and the shape control ability is greatly increased. It has characteristics.

Now, to express the position of this intermediate roll, the distance δ between the edge of the rolled material plate and the edge of the roll is used, as shown in Figure 1 □.

When the roll edge is on the inside of the plate, as shown in the figure, δ is negative, when it is on the outside of the plate, it is positive, and when the plate edge and the roll edge match, δ is
is 0.

Since normal rolling is symmetrical about the center line of the rolling mill, the upper roll position δ1 and the lower roll position δ2 are equal.

However, the known intermediate row drive device (for example, Japanese Patent Application No. 48-53559 (Japanese Patent Publication No. 52-26508)
) allows the values of δ1 and δ2 to be independently selected, and is used when rolling is asymmetrical.

Conventionally, methods for correcting such asymmetrical rolling include changing the amount of rolling reduction between the operating side and the driving side of the rolling mill, or controlling the pending force independently for the left and right sides.

However, in this method, the rolling load itself changes, which adversely affects the accuracy of the plate thickness in the longitudinal direction.

Furthermore, as another method, it has been considered to move the side guides to shift the entire rolling line to either the left or right.

However, since the positions of the tension reel and payoff reel also have to be moved, tandem rolling mills have the disadvantage that the equipment becomes large-scale.

The object of the present invention is to eliminate such drawbacks and to provide a method for correcting asymmetrical rolling using a simple mechanism and having no adverse effect on the thickness of the sheet in the longitudinal direction.

The present invention is characterized in that a rolling mill in which a pair of upper and lower intermediate rolls movable in the axial direction is arranged between a pair of upper and lower work rolls each having a bending device and a pair of upper and lower reinforcing rolls. One end of these upper and lower intermediate rolls is moved to a symmetrical position with respect to the center line of the rolling mill according to the strip width, and the left and right strip thicknesses in the strip width direction on the input side of the rolled material are detected. Based on this plate thickness difference, the end position of one of the upper and lower intermediate rolls is set to move in the axial direction from the large thickness to the small thickness among the left and right plate thicknesses in the plate width direction. A method for controlling plate thickness in a rolling mill, characterized in that the positions of upper and lower intermediate rolls are set asymmetrically with respect to the center line of the rolling mill.

The above configuration makes it possible to prevent elongation and meandering phenomena in the rolled material without affecting the thickness accuracy of the rolled material in the longitudinal direction.

The reason why rolling is asymmetrical is that the thickness distribution in the width direction of the base material differs between the left and right sides.

In other words, if a base material with a good shape but a thickness distribution of thinner on the right and thicker on the left as shown in Figure 2 is rolled so that the thickness is uniform on the exit side, the thickness of the base material will naturally increase. The amount of elongation on the left side becomes large, causing unilateral elongation and even causing the board to meander.

In order to simplify the explanation of the correction method, here, we will discuss the case where a material having a good shape as a base material and having a thickness distribution as shown in FIG. 2 enters the rolling mill.

When such a base material is rolled to have a uniform thickness in the width direction on the exit side, the thicker part of the base material on the left side elongates more than the right side, resulting in one-sided elongation.

Generally, in sheet rolling, a good shape is given priority over a uniform thickness distribution in the width direction.

In other words, even if you ignore the slight unevenness in the thickness distribution, you still have to roll a plate with a flat shape.

To achieve this, it is sufficient to roll the sheet so that the thickness distribution on the exit side is similar to that of the base material.

Here, the plate thickness at the center of the base material is H6, the plate thickness on the right side is HR1, and the left side is HL, and the plate thickness at the same position on the exit side is calculated.

, hR9hL.

In addition, the difference in plate thickness between the left and right sides is ΔH (=HRHt, ) and Δ
h (2 hR - hL), in order to roll a plate with a good shape as described above, ΔHJh
...(1) Current status.

This relationship must be established.

Conventionally, in order to satisfy this relationship, the rolling position on the left side was raised and the pending force on the left side was increased, but this had the disadvantages mentioned above, and the thickness of the center plate increased.

There is a possibility that it may change.

As shown in Figure 3, a method to solve this problem is to move only the upper roll in the HC mill to the right side, which is the side with the smaller thickness of the left and right plates in the width direction, that is, toward the center of the plate. Just shift it.

That is, this enhances the bending effect on the left side, and the plate thickness distribution on the exit side satisfies equation (1), so the shape is maintained well.

Moreover, since the pending force and the rolling position do not change, there is no influence on the load cells 10 and 11, and no change in the longitudinal plate thickness is observed.

FIG. 4 shows an embodiment of the present invention.

There are various known methods for setting the position of moving rolls in general symmetrical rolling.

For example, Japanese Patent Application No. 48-81506 (Special Publication No. 56-31
161) is shown in a simplified manner. In FIG. 4, the strip width is determined by the strip width detector or strip width setter 12, and the roll position δ is uniquely determined by b.

and pending force PBO are calculated by the computing units 13 and 18, respectively, and output to the roll movement command devices 14, 15 and the bending finger device 19.

Roll axial drive device 16 based on commands from each command device.
．． 17. The bending devices 8 and 9 operate.

In this way, by setting the roll position and pending force determined by a certain sheet width, even if the rolling load or rolling reduction rate changes, rolling with a good shape will always be possible without any control of the roll position or roll bender. can.

Here, the HR
Suppose that a mismatch between HL and HL is detected.

Under normal conditions, upper roll position δ1 and lower roll position δ2
are both δ.

However, if left in this state, one-sided elongation and meandering will occur as described above.

Therefore, one of the rolls is Δδ as shown in Figure 3.
only have to be moved.

That is, δ1 = δ0 + Δδ...
・(2) becomes.

This amount of movement Δδ is a function of ΔH/Ho, which is shown in FIG.

As will be seen from now on, 1Δδ peak 1 and 1ΔH/HCI are proportional, and the proportionality constant changes depending on the pending force at that time.

That is, if PB is large, Δδ may be small.

Therefore, Δδ is also a function of plate width and pending force.

Therefore, Δδ=f (ΔH/Ho, b, PB)...
...(3).

Next, regarding the sign of Δδ, when moving toward the center of the plate, it is negative, and when moving outward, it is positive.

In the case of FIG. 2, since ΔH (=HRHL) is negative, it is sufficient to move the roll in the negative direction.

In this way, the positive and negative signs of ΔH and Δδ always match.

Now, when HR and HL are detected by the plate thickness gauges 20 and 21, the following calculation is performed by the calculator 22.

Using this ΔH/Ho and the following PBO, the calculation of equation (3) is performed by the computing unit 23 to find Δδ.

This Δδ and δ during normal rolling mentioned above.

are added by the adder 24 as shown in equation (2), and the upper roll position δ1 is output and sent to the command device.

In this way, the outlet plate has a cross-sectional shape that corresponds to the shape of the base material, and it is possible to prevent one-sided elongation and meandering.

The example shown in FIG. 4 is a case where only the upper moving roll is controlled, but the same applies, of course, to the case where only the lower roll is controlled.

According to the present invention, it is possible to change the rolling load that affects the longitudinal thickness of the rolled material using a simple mechanism without requiring a large-scale device such as moving a tension reel or a payoff reel. The present invention has the effect that it is possible to realize a plate thickness control method for a rolling mill that can perform asymmetrical rolling without causing left-right asymmetrical rolling, thereby preventing the occurrence of elongation or meandering phenomena in the rolled material.

[Brief explanation of drawings]

Figure 1 shows a rolling mill (H) with axially movable rolls.
C mill), Figure 2 is a diagram showing the plate thickness distribution of the base material that causes one-sided elongation, Figure 3 is a diagram showing a method for preventing one-sided elongation, and Figure 4 is an example of the present invention. FIG. 5 is a diagram showing the relationship between the plate thickness deviation indicating the asymmetry of the plate and the amount of roll axis movement for correcting it. Explanation of symbols, 2, 6...Intermediate roll, 12...
...Plate width setting device, 13...Arithmetic unit, 14,
15...Roll movement command device, 16.17...
... Roll drive device, 20, 21 ... Plate thickness gauge, 22, 23 ... Arithmetic unit, 24 ...
Adder.

Claims (1)

[Claims] 1 In a rolling mill in which a pair of upper and lower intermediate rolls that are movable in the axial direction are arranged between a pair of upper and lower work rolls having a bending device and a pair of upper and lower reinforcing rolls, these upper and lower intermediate rolls are arranged according to the width of the rolled material. One end of the roll is moved to a symmetrical position with respect to the center line of the rolling mill, and the thickness of the left and right plates in the width direction on the input side of the rolled material is detected.
Based on this plate thickness difference, the end position of one of the upper and lower intermediate rolls is set to move in the axial direction along the direction from the larger plate thickness to the smaller plate thickness among the left and right plate thicknesses in the plate width direction. A method for controlling plate thickness in a rolling mill, characterized in that rolling is performed by setting intermediate rolls asymmetrically with respect to the center line of the rolling mill.