JPH0459114A - Method for controlling sheet thickness of rolling mill - Google Patents

Abstract

PURPOSE:To reduce the fraction defective of sheet thickness by controlling the sheet thickness with measuring both of the edge part sheet thickness of the width direction and the central part sheet thickness of the material to be rolled on the control for sheet thickness of the rolling mill. CONSTITUTION:The inlet side sheet thickness meter 4 and the outlet side sheet thickness meter 5 are set on the reverse type rolling mill 1. In this time, it is composed of the contact type sheet thickness meter 4a, 5a to measure the edge part sheet thickness of width direction of the strip (s) at the inner side and the X-ray sheet thickness meter 4b, 5b to measure the central part sheet thickness of width direction of the strip (s) at the outside. In such a way, the rolling in consideration of the edge-drop and the sheet crown can be realized, so the fraction defective for sheet thickness can be reduced, the yield can be improved and the rolling efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for controlling plate thickness of a rolling mill, which controls plate thickness using a measured value of plate thickness of a material to be rolled.

<Prior Art> In a rolling mill, such as a cold rolling mill, plate thickness control is performed to obtain a predetermined plate thickness. This plate thickness control (AGC)
There are several types of methods, including BISRA's AGC, which uses rolling force measurements to control plate thickness.
In monitor AGC, constant mass flow AGC, and feedforward AGC, plate thickness control is performed using plate thickness measurement values. Usually, plate thickness control is performed by combining a plurality of these AGCs to improve the accuracy of plate thickness control.

On the other hand, there are two types of plate thickness measurement methods: non-contact type and contact type. The former uses radiation such as X-rays to measure the plate thickness at the center of the width of the rolled material in a non-contact manner. In the latter method, the thickness of the rolled material is measured by directly bringing the contactor into contact with the groove in the width direction of the material to be rolled. Then, A using the plate thickness measurement value
In GC, it is common to install either a non-contact thickness gauge or a contact thickness gauge.

<Problems to be Solved by the Invention> However, the rolled material subjected to cold rolling usually has different plate thicknesses at the center in the width direction and at the edges in the width direction. (The thickness of the part is larger, but the opposite is true in some cases.) Swelling is mainly caused by encitrotubes and temporary crowns that occur during hot rolling.

Therefore, the longitudinal plate thickness control accuracy has been greatly improved by various technological improvements (control accuracy about ±2-2).
However, the accuracy of the plate thickness in the width direction cannot be said to be sufficient. For example, if you use the thickness measurement value at the center in the width direction for thickness control,
The plate thickness at the edges in the width direction, which is embossed, is large because the temporary crown ratio and edge droop ratio in hot rolling do not change much even in cold rolling. There is something to know.

The present invention aims to solve the problems of the above-mentioned prior art.

<Means for Solving the Problems> The present invention provides a method for controlling the thickness of a material to be rolled using a measured value of the material in a rolling mill, in which the width of the material to be rolled is determined using two thickness gauges. A method for controlling plate thickness of a rolling mill, characterized in that the plate thickness of a directional edge portion and a central portion in a width direction is measured, and the plate thickness of a material to be rolled is controlled using either or both of these measured values. .

The method for controlling the thickness of a rolling mill is characterized in that when the material to be rolled is a rigid material, both of the measured values are used; , a plate thickness control method for a rolling mill characterized in that the larger of the measured values is used, and when the material to be rolled is made thinner, the smaller of the measured values is used. A rolling mill plate thickness control method 2 (Operation) In plate thickness control of a rolling mill, it is necessary to control the plate thickness so that the plate thickness after rolling falls within an allowable range. That is, the plate thickness must be controlled so as to satisfy the following equations (1) and (2).

t * am < t e ≦t, wm
---(1) L1 so-≦1c≦t, m----(2
) where, -: Lower limit of allowable plate thickness t, w: Upper limit of allowable plate thickness t, : Thickness of the edge portion in the width direction of the rolled material te: Thickness of the center portion of the rolled material in the width direction. Therefore, the present invention In this case, both the thickness at the edge in the width direction and the thickness at the center in the width direction are measured, and these measured values are used to control the thickness.

That is, in the case of a strict material with strict requirements for plate thickness accuracy, the plate thickness setting value trot is given by the following equation, and the plate thickness is controlled so as to satisfy equation (4).

t ,, + t c+a = Lrar Here, L us 'Measurement value of plate thickness at edge part cm' Measurement value of plate thickness at center area Also, if you want the plate thickness to be thicker within the range that does not result in defective plate thickness, The thickness setting value t rllf is given by equation (5).

tr? j = t @ lock-α
--(5) Here, α is for safety, and may be approximately 3σ, which corresponds to the plate thickness control accuracy. Then, as shown in equation (6), the thicker of the plate thickness measurements t am and tcm is (5
) Plate thickness control is performed so that L rat of the equation is satisfied.

MAX (tell, -) = t□, -・----
(6) On the other hand, if you want to make the board thinner, (sword, (
8) Plate thickness control is performed using formula.

1,,,=1) Eyelid +α --(71MIN
(t,,,t,,)=t,,, -・-1-(81
The above is shown as a flowchart in FIG. 3. In FIG. 3, 1. is the control plate thickness measurement value.

As described above, in the present invention, by selecting and performing the above-mentioned three sheet thickness control methods, the rolling part takes into consideration the encitrotube and sheet crown.

<Example> An example in which the present invention is applied to a reverse cold rolling mill will be described.

In FIG. 1, 1 is a reverse cold rolling mill;
w is a work roll, ■b is a puncture-up roll, and 1s is a lowering device.

The strip S is unwound from the coil C, rolled in the direction of arrow A or B, and wound around the coil C. The case of rolling in the direction A will be described below. 2 is a rewinding machine;
3 is a winding machine, 4 is an inlet side plate thickness gauge, 5 is an outlet side plate thickness gauge,
As shown in Fig. 2, a contact-type plate thickness meter (for example, one that captures the movement of a contact with a differential transformer and converts it into plate thickness) 4a measures the plate thickness of the edge portion in the width direction of the strip S on the inner side.
, 5a, and X-ray thickness gauges 4b and 5b for measuring the thickness of the strip S at the center in the width direction.

The contact position of the contact type plate thickness gauges 4a and 5a is set at 20 mm from the edge in the width direction of the strip S toward the center (this range is the guaranteed range of the product), X-ray plate thickness gauge 4
b and 5b were set approximately at the center of the strip S in the width direction.

Plate thickness measurement value using exit side plate thickness gauge 5 1. ,．． 1- is arithmetic unit 6
is input. The calculation unit 6 calculates the control amount (plate thickness deviation) based on the upper and lower limits of allowable plate thickness and the required level for strict materials, etc., which are input manually by a host computer or a terminal device.

7.8 is a length measuring roll, and its detected value and plate thickness deviation Δ
The mass flow is inputted to the control device 9, and known constant mass flow control is performed using the lowering device IS.

At this time, monitor AGC may also be used. Note that 10 is a deflation crawl.

The reverse type cold rolling machine shown in Fig.
Cold rolling was carried out using a 5US304 hot-rolled coil with a thickness of 0 mm and a plate width of 1000 mm. At this time, half of the ten throat coils were cold rolled by the conventional method and the other half by the control method of the present invention. In addition, in the conventional method, @
I took one test. In addition, allowable plate thickness t, width=2.9, t,
Low 3.1 cylinder, therefore, plate thickness setting Lef = 3.
It was set to 0 mm. The results are shown in Table 1.

Table 1 From Table 1, it can be seen that in the conventional method, the plate thickness after one pass [maximum value -
The minimum value] is 90n, but it can be seen that it decreases to 70- in the present invention. In addition, the average value of the minimum and maximum plate thickness after one pass was 2.975+mn using the conventional method.
On the other hand, it can be seen that in the method of the present invention, the value is 2.995m+, which is almost the set value.

This is because the present invention uses actual measurements (it, , t-) and controls the average value to be 3.0 m.

Note that even if the plate thickness is made thicker or thinner, as a result of implementing the method according to the present invention, [maximum value - minimum value]
The above value 10n does not change much, only the average value is 3.
O1! ll1), and the excellent effects of the present invention were recognized.

In addition, the results of implementing the control method of the present invention on an actual cold rolling line were compared with the results of operating using the conventional method.
Shown in Table 2.

The number of coils cold rolled by the method of the present invention was 713.
Coil, average weight per coil is +0.6ton
The average plate thickness of the hot coil is 4.0 Onw, and the average plate thickness after cold rolling is 1.06 m1). In addition, the number of coils cold rolled by the conventional method was 883 coils and 1 coil.
The average weight per piece is 10.7 tons, the average thickness of the hot coil is 4.03 mm, and the average thickness after cold rolling is 1.07
It is mm.

Table 2 From Table 2, it can be seen that the method of the present invention reduced the defective board thickness rate to zero compared to the conventional method, and improved the yield. Furthermore, it can be seen that according to the method of the present invention, rolling efficiency is also improved.

<Effects of the Invention> As explained above, in the present invention, both the edge thickness and center thickness in the width direction of the rolled material are measured, and these are used to control the thickness. This makes it possible to perform rolling with consideration to edge droop and plate crown, resulting in reduced plate thickness defects, improved yield, and improved rolling efficiency, and also greatly contributes to quality assurance.

[Brief explanation of the drawing]

The first is an overall configuration diagram of an embodiment of the present invention, FIG. 2 is a diagram showing an example of the arrangement of plate thickness needles used in the present invention, and FIG. 3 is a flowchart of the present invention. 4a...Contact type plate thickness gauge, 5...Outside plate thickness gauge, 5b...X-ray plate thickness gauge, 7.8...Length measuring roll, 10...Deflation crawl, C... coil. 4b...X-ray plate thickness gauge, 5a...Contact type plate thickness gauge1. 6... Arithmetic unit, 9... Control device, S... Strang,... Reverse rolling mill, W... Work roll, b... Hankhumph I)-le,

Claims (4)

[Claims] (1) In a rolling mill plate thickness control method that uses plate thickness measurements to control the plate thickness of a rolled material, two plate thickness gauges are used to measure the widthwise edges and widthwise center of the rolled material. measure the thickness,
A method for controlling plate thickness of a rolling mill, characterized in that the plate thickness of a material to be rolled is controlled using either or both of these measured values. (2) The method for controlling plate thickness in a rolling mill according to claim 1, characterized in that, when the material to be rolled is a rigid material, both of the measured values are used. (3) When the rolled material is made thicker, the larger of the measured values is used.
The described method for controlling plate thickness in a rolling mill. (4) The method for controlling plate thickness of a rolling mill according to claim 1, wherein a smaller value of the measured value is used when the material to be rolled is made thinner.