JPS62158511A - Shape control method for plate rolling - Google Patents

Abstract

PURPOSE:To make a rolled stock a good shape and to improve the yield by setting a thermal crown of a work roll calculated using a model calculation based on a roll cooling condition and a bending force of an intermediate roll and of the work roll based on a roll shift amount. CONSTITUTION:A thermal crown state of a work roll 6 is calculated using a model calculation based on a roll cooling condition (a flow rate, temp., and concentration) of a plate rolling mill 5. A bending force of an intermediate roll 7 and of the work roll 6 is calculated based on a shift amount of the intermediate roll 7 with consideration for a condition of a stock in the inlet side (a dimension, crown, and deformation resistance) and a rolling condition (a tension, speed, screwdown ratio, and roll diameter); and the shift amount of the roll 7 is set so that a bending force distribution of the work roll 6 equals to the target value. With the above procedures, a dimension and shape of the rolled stock 1 and the yield are improved.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a shape IJ control method in plate rolling (prior art) The rolled plate must have a good shape, that is, the flatness of the plate should be It is desirable that the quality is uniformly good not only in the longitudinal direction of the plate but also in the width direction of the plate. In particular, recently, requirements for the shape of rolled plates have become more severe.

On the other hand, many plate shape control methods have been proposed and implemented. The plate shape is mainly controlled by adjusting the bending deflection or crown of the roll.

As a means of mechanically adjusting the bending deflection or crown of the roll, bank-up roll bending, medium 1iJ]
Roll benders, work roll bends, displacement of intermediate rolls in the plate width direction, division of bank up bearings in the plate I width direction: A moromi, hollow bending deflection, or internal pressure adjustment of the rolls. In addition, as a first step to thermally adjust the roll crown, we perform 4 steps such as roll cooling water adjustment and roll local heating.
There are steps. The means for controlling the bending deflection or crown of these rolls is determined by presetting operations (e.g., roll pending force, intermediate roll movement amount) based on the material plate (e.g., hot-rolled coil) and rolling conditions before rolling starts. In addition, during rolling, the plate shape is detected on the exit side of the rolling mill and the roll crown control means is feedback-controlled.

As a method for setting the operation amount of the roll crown control means, for example, there is a method described in Japanese Patent Application Laid-Open No. 80-46804. In this method, the roll pending force and intermediate roll movement amount are set based on the plate shape.

(Problems to be Solved by the Invention) The temperature distribution of the work roll changes as rolling progresses due to heat of deformation of the rolled material, frictional heat between the work roll and the rolled material, and the like. Therefore, among the crowns of the work rolls, the thermal crowns caused by the temperature distribution also change as rolling progresses.

However, in the past, when setting the operation of the roll crown control means, no consideration was given to the thermal crown at all. Therefore, there was a problem in that even if shape control was performed, a good shape could not be obtained.

(Means for Solving the Problems) In the shape control method of the present invention, first, the work roll thermal crown is determined by calculation using a numerical calculation model or by actual measurement. To obtain the work roll thermal crown using a numerical calculation model, roll coolant conditions (flow rate, temperature, and concentration) or work roll surface temperature are used. The roll coolant conditions are measured or set according to the rolling conditions, and the work roll surface temperature is determined according to the actual temperature! 11.

The numerical calculation model for determining the work roll thermal crown CT is generally.

C = f(+ (t, z,
par) = (1). Here, t
is the rolling time, and 2 is the axial position of the work roll.

In addition, par is the diameter, length, surface temperature of the work roll,
Thermal conductivity, initial thermal crown, coolant flow rate,
These are temperature, e degree, and other parameters related to the work roll. The required one is selected from the above parameters depending on which of the roll coolant conditions and the work roll surface temperature is used to determine the work roll thermal crown CT.

Next, the operation layer of the shape control means is calculated by the numerical calculation model based on the work roll thermal crown, the conditions of the plate on the entry side of the rolling mill, and the rolling conditions, which are calculated by the numerical calculation model or obtained by actual measurement.

The numerical calculation model for calculating the above operation %F is generally as follows.

F = fr (Ct, c + CH, P, pa
r) a=o...-(2). Here, 0
D is the work roll thermal crown obtained by calculating with the above formula (1) or by actual measurement, CI is the initial crown of the work roll, intermediate roll, backup roll, etc., CH is the plate crown at the entrance side of the rolling mill, P
is rolled wool. par is a parameter related to other work roles. Further, Δ=0 represents the condition that the plate is flat.

Once the manipulated variable is determined as described above, it is set in the shape control means. Shape control means include the aforementioned backup roll bender, intermediate roll bender, work roll bender, displacement of the intermediate roll in the plate width direction, division adjustment of the backup bearing in the plate width direction, internal pressure adjustment of the hollow roll, roll cooling water adjustment, and roll local heating. etc.

(Operation) The above numerical calculation model formula (2) provides an operation iF such that the crown of the work roll including the thermal crown becomes flat in the rolling state. For example, if the crown shape of the work roll is inappropriate and causes edge elongation in the rolled plate, the numerical calculation model formula (2) gives a larger value of increased spending force. And if you set the roll bender to such a pending power,
During rolling, the crown of the work roll is modified and the plate is rolled to a uniform thickness throughout.

(Example) Example I: Determination of work roll thermal crown based on roll coolant conditions FIG. 1 shows an example of a cold rolling mill in which the present invention is implemented.

The cold rolling mill 5 is a six-high rolling mill consisting of a work roll 6, an intermediate roll 7, and a backup roll 8. The cold rolling mill 5 is equipped with a work roll bender 11, an intermediate roll bender 13 and an intermediate roll shift 14 as roll crown control means. Further, the work roll 6 is cooled with a coolant 1B. A plate crown detector 18 for measuring the crown CH of the hot rolled coil 1 to be rolled is arranged on the entry side of the cold rolling mill 5. The cold rolling mill 5 is controlled by a control computer and a controller (neither shown).

FIG. 2 is a flowchart showing the procedure for setting the operation amount of the shape control means. Hereinafter, a method for setting the operation amount of the shape control means in the cold rolling mill configured as described above will be explained with reference to FIG. 2.

The work rolls are cooled by roll coolant. Of coolant! ffl, temperature, and concentration.

It is set according to the rolling conditions using a predetermined reference table. Once the temperature distribution in the body length direction of the work roll is obtained, the thermal crown can be determined by taking into account the thermal expansion of the work roll, so first, the heat transfer coefficient α of the roll coolant is determined. The heat transfer coefficient α is determined by the position in the length direction of the work roll2, as shown by the first-order equation (3). Coolant flowff1Q
, is a function of temperature Tt+ and concentration CM.

α(Z) = f (Z, Q, Tw, Cw
)...(3) Equation (3) is determined in advance by experiment. Fig. f53 is a diagram showing an example of the relationship between the heat transfer coefficient α and the coolant flow rate Q, and FIG. These diagrams are stored in the control computer.

Once the heat transfer coefficient α is determined, the thermal crown C is determined using the following equation (4). Note that the subscript j of the thermal crown CB represents the dividing position of the work roll in the body length direction, and the work roll is divided into, for example, 50 pieces in the body length direction.

C-=2(1+ν) X cos (5]Z) −(4a) input=α(Z)/
KM... (4b)h (x) =exn
, x=Rf'';;: -(4e) (See Table 1 for the values of e and n) Here, C, MiCo(Z): Initial thermal crown t:
Rolling time C: Boisson ratio α2=IJ5
β: Coefficient of linear expansion KR: Thermal conductivity qo: Amount of frictional heat transmitted to the roll Tw: Coolant temperature 2Q = Roll body length: yi Friction coefficient P,: Average rolling pressure J: Heat work force ■
VR' roll circumferential speed H: entry side plate thickness h. : Exit plate thickness f, advance rate η: Distribution ratio of frictional heat to roll (rotation 0,5) ΔV: Absolute value of speed difference between plate and roll Average R°: Unbalanced roll radius E: Young's modulus Table 1 Values of parameters e and n Once the thermal crown is determined, the shift amount S of the intermediate roll that makes the plate flat is determined. For this purpose, the shape evaluation function A2. t; and A4
Define. As shown in FIG. 5, the steepness is expressed by the ratio of the height δ of the plate wave to the length of the plate wave.

Δ2=in. -People. , Δ4=in, -Person C... (5) Here, in. , entering 6. Enter. are the plate ends and 1 shown in Fig. 5, respectively.
/a part and plate steepness in the central part.

Also, shape evaluation function A2 and Ai1 Shiji's #! l(&
It is assumed that i calculation model is expressed by formula (6).

Δ2=A2pP ten elephants (A2su4 (c 豐J+C+3)
J+1 +A2+j C+J+A2B+ CeJ) +A2MF
enemy+A2NF 1 +A2qCoq+A2eC+e+A
2゜Aa = A4pP ten places (A 4wj (Cn3+
Crt) J+1 + A a+4 C+j+ A naj CeJ) +
A 4NFenemy+AanF+ +AaqCt+a+A4
eC) Ie+Aa.

...CB) Aab: Influence coefficient = αabR + βabW + γabS + δah... (6a
) (The subscript a stands for 2 and 4, and the subscript b stands for P, W, I.
, B, M, N, q.

(represents e and o respectively) P: Rolling load = Kkr ¥71 (1,08 + 1.79 rk =
0.4kb + 0. Etkr...
・(6d)r = (H-h)/H・1ce) Here, R: Work roll radius R": Flattened work roll radius H: Inlet side plate thickness h: Outlet side plate thickness W: Plate width k: Friction coefficient kb: Deformation resistance of the plate at the entrance side of the rolling mill kf: Deformation resistance of the plate at the exit side of the rolling mill αab+βab, γab, δd
b: Constant S: Intermediate roll shift expression n: Number of roll divisions Cttj: Initial crown of the work roll CI j: Initial crown of the middle 1ifl roll C8j: /< Initial crown of the pick-up roll C, j: Thermal crown of the work roll CHq: Difference in crown between the center of the entry board and the 17th section CHe: Difference in crown between the center of the entry board and the end of the board Fv: Work roll bender force Fl: Intermediate roll bender force Next, the above shape evaluation function The formula representing Δ2 and A4 (
6) to define the shape function J.

J=(A2(Fw, F+, S)?+A4(Fw,
F+, 5) 2) ・・・
(7) In order to find the setting value of intermediate roll shift 1ffls, Fs=p1=Q and J=(A2(0,0,S)2+Δ4(0,0,5)2)
...(8) Find S that minimizes the following.

Once the set value of the intermediate roll shift amount S is determined, the work roll bending force FW and the intermediate roll bending force F+ can be determined. That is, when the above equation (6) is solved for the work roll bending force FW and the intermediate roll bending force F+, the following equation is obtained:%Fw=Bn2A? +BwnA4+BwpP+BwqC
++q10B yec He+ B jlQ +2 (Bwwj (C114+C+4)J:1 + B yrjCIJ+ B yeJCoJ)F+=8
12Δ20B+4Δa + B tpP 10B IQC
HQ+ B +eClé+ B l.

+ B ++JC+, ++ B +njCeJ)...
(3) Here, Bab is a constant similar to the above Aab.

In the above equation (9), if A2 = A4 = O and substitute the previously determined intermediate roll shift Ff (S), the work roll venter jE F y and the intermediate roll venter force F
, is required.

Embodiment II: Determining the work roll thermal crown from the work roll surface temperature FIG. 6 is a flowchart showing the procedure for setting the operation amount of the shape control means of the embodiment II. In this example, the actual Δ1
Fill in the above from the work roll surface temperature T (Z, ) after 1 work (
=α(Z)/KR). (In Example I, α was determined from the coolant conditions) Work roll surface temperature T
(Z) is measured by scanning the work roll surface with a radiation thermometer.

Now, assuming that E hours have passed since the start of rolling, the work roll surface temperature T (Z) is expressed by the following formula (work 0).

Degree a + = 11.93 a + = i
,! ]9.

Solving equation (10) for input (Z) yields the following equation (11)
is obtained.

The thermal crown C++ of the work roll can be found by substituting the input (Z) obtained by equation (11) into equation (4a) and further using equation (4).

Hereinafter, as shown in the flowchart of FIG. 6, similarly to the embodiment, the intermediate roll shift amount S, work roll bending force Fw, and intermediate roll bending force Fl are determined, and each is set to the intermediate roll shift or roll bending.

Example m': When actually measuring the thermal crown of the work roll In this example, the thermal crown of the work roll is actually measured by δ
11, therefore, it is not necessary to determine the thermal crown using a numerical calculation model formula based on the coolant conditions or the work roll surface temperature as in the previous embodiment. The thermal crown of the work roll is measured using an air micrometer or camp sensor.

Using the actually measured thermal crown of the work roll, the intermediate roll shift amount S, work roll bending force Fw, and intermediate roll bending force F were determined in the same manner as in Examples T and TI.
Find 1. Then, the obtained operation m S , F
Set VI and F to intermediate roll shift or roll bender.

Here, a specific example of the shape of the plate obtained by the method of Example (2) will be described. The shape of the plate was evaluated using shape evaluation functions Δ2 and A4.

The rolling equipment was a 6-stand tandem cold rolling mill, and the plate shape was formed on the exit side of the 6th stand. The specifications of the rolling stand and rolling conditions are as follows.

Work roll diameter: 335mm 1rl length: 1422mm Intermediate roll diameter: 5!114mm 1rl length: 1457mm
Pack unroll diameter: I 152mm 1H length: +520 ■Plate size/Plate thickness 2.3mm -+ 0.15mm, Plate width 12
00mm rolling reduction ratio 332 Rolling load: 690 ton Front 12 kg/mm2 Rear 6 kg/m+
m2:Jrj7 Figure shows the shape evaluation function A2 and Δqlt of the plate rolled under the above conditions, and the work roll bender F11.
and intermediate roll bender F+ are shown as parameters. The shape evaluation functions Δ2 and A4 are expressed by the tension distribution of the plate, and the arrow Fw indicates the increasing direction of the work roll bending force Fw, and the arrow Fl indicates the increasing direction of the intermediate roll bending force F+. Also, mark
are the measured values of the shape evaluation functions A2 and A4, mark 0 is the calculated value of the shape evaluation functions Δ2 and A1 by the conventional method (not taking into account the thermal crown), and mark 0 is the value of the present invention (taking into account the thermal crown). The calculated values are shown respectively. As is clear from FIG. 7, according to the present invention, the calculated value and the measured value of the plate shape agree well.
In other words, the plate shape can be predicted with high accuracy.

(Effect of the invention) According to this invention, shape setting accuracy is improved.

The steepness of the plate is greatly improved. This eliminates defective shapes and improves yield. Furthermore, there is no need to slow down the rolling line for shape correction, improving productivity.

[Brief explanation of drawings]

FIG. 1 shows an example of a cold rolling mill in which the present invention is implemented, and is a schematic perspective view of the rolling mill. FIG. 3 is a diagram showing an example of the relationship between the heat transfer coefficient α and the coolant flow rate Q, FIG. 4 is a diagram showing an example of the relationship between the heat transfer coefficient α and the coolant concentration CI+, FIG. 5 is a drawing for explaining the shape evaluation function, FIG. 6 is an embodiment of the present invention, and is a flowchart showing the procedure for setting the operation amount of the roll crown control means, and FIG. 7 is a diagram for explaining the shape evaluation function A2. It is a diagram showing a comparison between actual measured values and calculated values of A4. l, 2... Rolled plate, 6... Work roll, 7...
Intermediate roll, 8...Backup roll, 11...
Work roll venter, 13... Intermediate roll venter, 14... Intermediate roll shift, 1B... Roll coolant, 18... Shape detector.

Claims (1)

[Claims] In a method of rolling a plate using a plate rolling mill equipped with shape control means, the work roll thermal crown is calculated by a numerical calculation model based on the roll coolant conditions (flow rate, temperature and concentration) or the work roll surface temperature, or is actually measured. The shape control means is operated by a numerical calculation model based on the work roll thermal crown, plate conditions (dimensions, crown and deformation resistance) at the entrance of the rolling mill, and rolling conditions (tension, speed, rolling reduction, roll diameter, etc.). A shape control method in plate rolling, characterized by calculating a quantity and setting a shape control means to the calculated operation quantity.