JPS63194811A - Sheet thickness control method for rolling mill - Google Patents

Abstract

PURPOSE:To improve the sheet thickness control accuracy for a rolled stock by calculating a deformation amount and dividing the amount into a roll base and a housing base deformation amounts. CONSTITUTION:A deformation amount of a rolling mill for calculation of a gage sheet thickness is calculated and divided into a roll base and a housing base deformation amounts. That is, actually measured values such as a roll dia. and a sheet width are inputted to a data input part 31 and a roll base deformation amount is obtained by a roll base deformation amount calculation device 33 from a prescribed equation. A housing base deformation amount is obtained by a housing base deformation calculation device 32 by subtracting the roll base deformation amount at roll screwing time from a rolling mill deformation amount obtained from the elastic characteristic curve at roll screwing time. The control accuracy is improved because a roll opening controller 34 adds both the deformation amounts, calculates a roll opening, and controls the opening.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling plate thickness using a rolling mill using a gauge meter system.

[Prior art]

When rolling a metal material using a rolling mill, a gauge meter method is often used to control the thickness of the metal material.

The principle of the gauge meter method is that the thickness of the exit side of the rolled material is determined by the roll opening during rolling, and the gauge meter plate thickness that determines the roll opening is determined by the roll opening when no load is applied and the load when loaded. It is determined by the amount of deformation of the rolling mill. In this case, the amount of deformation of the rolling mill is determined by an elastic modulus, the so-called mill rigidity coefficient, which is a function of the rolling load and the width of the rolled material when the rolling mill is regarded as a type of elastic body. That is, the gauge meter plate thickness h9 is h,=S+P
/M ... (1) h, : Gauge meter plate thickness S, : Roll opening degree at no load P: Rolling load M: Mill rigidity coefficient, and as is clear from equation (1), gauge meter The control accuracy of the exit side plate thickness of the rolled material by the method depends on the setting accuracy of the mill rigidity coefficient M, that is, the accuracy of setting the amount of deformation of the rolling mill.

As disclosed in JP-A No. 51-69463, a method for controlling the roll opening degree by determining the amount of deformation of the rolling mill is based on the relationship between the amount of roll tightening and the load generated at that time. , a method in which an elastic characteristic curve is determined by the least squares method, a Neighborhood formula including a natural logarithm formula that can represent this curve is set in advance, and the amount of deformation is determined based on this formula to limit the roll opening degree. It has been known.

However, this amount of deformation is only a value when the plate width of the rolled material corresponds to the full width of the roll, and it does not reflect the dynamic state of the roll when actually rolling the rolled material.
As disclosed in Japanese Patent Application Laid-Open No. 53-113746, the total roll width determined at the time of roll tightening is determined based on the relationship between the oil film rigidity that changes depending on the roll rotation speed, the width of the rolled material, and the amount of change in the mill stiffness coefficient M. A common method is to correct the mill stiffness coefficient M corresponding to the mill stiffness coefficient M, and to control the roll opening degree based on the corrected mill stiffness coefficient M. In addition, as disclosed in JP-A No. 58-84608, the mill stiffness coefficient M at each point is calculated from the actual measured values of the rolling position, rolling load, and plate thickness obtained at multiple arbitrary points in each online rolling pass.
At the same time, the relationship between these mill rigidity coefficients M and the plate width of the rolled material in that rolling pass is determined, and based on this data, the mill rigidity coefficient M in the next rolling pass is corrected according to the plate width. method is known.

[Problem that the invention seeks to solve]

However, the amount of deformation in a rolling mill is determined by the amount of roll system deformation caused by the deflection of the roll shaft and the flatness of the rolls, and the housing to which the rolling load is transmitted via the rolls.

The amount of deformation of the roll system is the total amount of both the amount of deformation of the housing system such as the liner and dummy block, and the amount of deformation of the roll system is calculated by changing the load and the width of the rolled material, as in the method of JP-A-53-113746 mentioned above. However, the amount of deformation of the housing system is normally within the range of ±10% for each roll chance because the liner, dummy pro-tsuku, etc. that make up the housing are replaced when the rolls are reassembled. Therefore, it is difficult to accurately calculate the amount of rolling mill deformation, which is the sum of roll system deformation and housing system deformation, depending only on the deformation factors of roll system deformation, such as sheet width and roll rotation speed. It is difficult to calculate the amount of deformation.

Furthermore, as in JP-A No. 58-84608, if the relationship between the amount of deformation of the rolling mill and the strip width is calculated based on actual measurements, the rate of change in the amount of deformation including both the roll system and the housing system can be determined. However, in order to obtain a practically reliable value, a considerable amount of rolling data is required after changing the rolls, and it is difficult to demonstrate the effect within a 10-ruction where the housing system components are the same. After the roll reshuffling in which the constituent members of the system are replaced, it cannot be uniform.

The present invention has been made to solve these problems, and provides a plate thickness control method that improves control accuracy by calculating the deformation amount of a rolling mill separately for the roll system and housing system. The purpose is to provide.

[Means for solving problems]

The present invention provides an Fi and thickness control method in which the thickness of a rolled material is specified as a gauge meter thickness based on the calculated deformation amount of a rolling mill, and the roll opening degree is determined according to this gauge meter thickness. The amount of deformation of the machine is separated into the amount of roll system deformation and the amount of housing system deformation, and a predetermined formula is set for calculating the amount of roll system deformation, while the amount of housing system deformation is calculated using the actual value when tightening the rolls. By subtracting the amount of roll system deformation at the time of tightening the roll, which is calculated based on the predetermined formula, from the amount of deformation of the rolling mill determined from the elastic characteristic curve obtained from , during rolling, calculate the roll system deformation amount based on a predetermined formula, and calculate the housing system deformation amount based on the rolling load,
A feature is that the sum of the roll system deformation amount and the housing system deformation amount is set as the deformation amount of the rolling mill.

[Effect]

In the method of the present invention, a predetermined formula for calculating the amount of roll system deformation is set in advance, and the deformation amount of the rolling mill is determined from the elastic characteristic curve obtained from the actual measurement value when tightening the rolls, and based on the predetermined formula that has been set. , calculate the amount of roll system deformation when this roll is tightened, subtract the amount of roll system deformation from the amount of deformation of the rolling mill, and set that value as a function of the rolling load to calculate the amount of housing system deformation. At the same time, the roll system deformation amount is calculated according to the sheet width during rolling based on the predetermined formula, and the housing system deformation amount is calculated based on the rolling load, and these roll system deformation amounts and the housing system deformation amount are added. This is specified as the amount of deformation of the rolling mill, and the roll opening degree is determined based on the specified amount of deformation.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a block diagram showing the configuration of a thick plate rolling apparatus according to the present invention. In the figure, 1 is a roll section consisting of 4 rolls, and 2 wooden work rolls 1 that directly roll metal materials.
1.11 and two bank-up rolls 12.12 that support the bending of work rolls due to rolling. Also,
2 in the figure is a gate-shaped housing that supports four rolls on both sides and supports the rolling load, and measures the rolling load.
It supports a load cell 4 which sends the measured value to a predetermined device of a control section 3 to be described later, and a reduction screw 5 which moves the roll up and down by its rotation and determines the amount of reduction. Further, numeral 3 in the figure is a control unit that controls the plate thickness, and the operator inputs the measured dimensions of the rolls used in the rolling pass from the data input unit 31 each time the rolls are rearranged.
This measured dimension is given to the housing system deformation amount calculation device 32 and the roll system deformation amount calculation device 33. The housing system deformation amount calculation device 32 specifies the housing system deformation amount as a function of the rolling load each time the rolls are rearranged based on a predetermined formula, and provides this function to the roll system deformation amount calculation device 33. The roll system deformation amount calculation device 33 sets a formula that can calculate the roll system deformation amount as a function of the plate width and rolling load of the rolled material, and also performs rolling at the roll chance based on a predetermined formula each time the rolls are rearranged. While calculating the amount of roll system deformation according to the sheet width of the material, the calculated amount of roll system deformation and the amount of housing system deformation calculated based on the above function are added, and the value is calculated as the sheet width of the rolled material at the roll chance. is applied to the roll opening degree control device 34 as the deformation amount of the rolling mill corresponding to the amount of deformation of the rolling mill. The roll opening degree control device 34 detects the reduction position of the reduction screw 5 and provides this value to the housing system deformation amount calculation device 32 and the roll system deformation amount calculation device 33, while
The plate thickness of the rolled material is calculated based on the amount of deformation of the rolling mill calculated as described above, and this is used to determine the rolling position of the rolling screw 5, and the plate thickness of the rolled material is adjusted each time the roll opening degree is adjusted. control.

The procedure for carrying out the method of the present invention in the plate rolling apparatus having the above configuration will be explained with a focus on the operation of the control section 3. Each time the rolls are rearranged, a rolling down device consisting of a rolling down screw etc. automatically tightens and releases the rolls between 1000 t and 3200 t by 2@ each, and
During that time, the rolling reduction amount WS measured by the roll opening control device 34 and the rolling blade P measured by the load cell 4
These detection values are provided to the housing system deformation amount calculation device 32 and the roll system deformation amount calculation device 33.

On the other hand, when the operator inputs measured dimensions such as the diameter of the newly rearranged rolls and the width of the metal material to be rolled from the data input section 31, these values are transferred to the housing system deformation calculation device 32 and the roll system. It is given to the deformation amount calculation device 33. The housing system deformation calculation device 32 calculates the elastic characteristics of the roll chance based on the above-described rolling position S and the rolling blade P. In this embodiment, as shown in FIG.
The elastic properties are approximately represented by a straight line above 1500, and by a curve including a natural logarithm below 1500.

Further, the housing system deformation amount calculating device 32 calculates the roll system deformation amount at the time of roll tightening of the roll chance based on the actual measured dimensions of the given roll. In this example, based on a roll deflection model based on a 5-hoet roll-barrel split dynamic model, the details of which will be described later, the rolling blade was adjusted to a pitch of 500t while the rolling blade changed from 1ooot to 3000t. The amount of system deformation is calculated and specified as a function δ□F of the rolling blade. Figure 3 is a diagram showing the elastic properties (curve 1) and the amount of roll system deformation (curve 2) during roll tightening calculated as described above using curves. The elastic characteristic curve showing the amount of change in is the sum of the amount of deformation of the roll system and the amount of deformation of the housing system. is identified as the amount of deformation δ9(7,).

Next, the roll system deformation amount calculation device 33 changes the combination of diameter dimensions of the backup roll and the work roll in advance, and calculates the roll system deformation amount of roll flatness and roll deflection corresponding to the combination. is calculated as a function δR(W+P) of the rolling blade P and the width W of the rolled material based on the same roll deflection model as mentioned above, and the actual roll dimensions and Roll system deformation amount δ□ according to the plate width of rolled material
821. Identify. In addition, in this example, the calculation formula for δ□W+Fl based on the roll deflection model is as follows, in which the plate width W of the rolled material is classified into four stages, and coefficients are set in advance according to each stage. This section is stored in the roll system deformation calculation device 33.

δ, 1(It+P) = g(w)・P...
(2) However, Wl < W : g6v)=az + arz (
C++ ・W+CB)W, <W≦Wl: g(1'
/1=az++ azz CCz+ ・W+C2Z)W
3<W≦Wz: g(W)=a:+++ aff
2 (C:++-W+ C32)W≦W3: g(
W) = aa++ aaz (C41' W+ C42
)a, ~a4□: Coefficient CIl~ determined by roll dimensions
C4□: The coefficient roll system deformation amount calculation device 33 calculates the sum of the housing system deformation amount δ8 at the roll chance calculated separately as described above and the roll system deformation amount δ8 according to the sheet width. The amount of deformation is given to the roll opening control device 34.

The roll opening degree control device 34 calculates the plate thickness of the rolled material based on the given amount of deformation of the rolling mill, uses this to calculate the roll opening degree for the next pass, and adjusts the rolling screw according to this calculated value. 5 and determine the position to be rolled down.

Next, the roll deflection model based on the 5-hoet roll barrel split dynamic model used in this example will be explained using equations. As shown in Figure 4, work roll 1
The roll barrel part of 1 and Hibatsuku Aprol 12 is 2m long.
It is assumed that the unit length is ΔX, and the contact pressure P acting between the work roll 11 and the backup roll 12 is -ffi within each divided section of length ΔX. In addition, the rolled material is divided by the extension of the roll barrel part, and the number of divided sections is 2.
0, and the rolling load qj per unit length ΔX is uniform within each divided section. Note that i and j are subscripts that designate arbitrary divided sections.

First, the displacement Yb (++) of the backup roll on the work roll contact surface in the i-th section is expressed as in the following formula.

Kb + Rc8+++ −(3) Also,
The displacement Y w (=) of the work roll on the bank-up roll contact surface in the i-th section is expressed as in the following formula.

10 Zw+t+ Kw Rcwu+...(
41 (αjjW 'J point on the work roll, and the displacement of the work roll at the contact surface of the rolled material in the i-th section Yupt=, + Rcw+t+ Zz=+ Kw −
f5) L+=, 'expressed as the surface displacement of the rolling material contact surface of the work roll. In this case, each surface displacement is expressed as a function of contact pressure Pi+rolling load q in the i-th section as shown in the following equation.

Zbf=, +zW(i+ = u P i ・
...(61Z F (=) = ” o Q =
・” <7) Each coefficient in equations (3) to (7) above is defined as follows. The influence coefficient α, j that the load at point j has on the deflection of the axis at point i is shown in Fig. 5. According to the model of a beam with free support at both ends, it is expressed as the following formula.

-3βT2-β3)] (However, γ≧β≧Ls) ...(8)-3γβ2
-γ3)] [d・Needle portion diameter Also, the coefficient U related to the contact surface displacement of the backup roll/work roll is T, u−T. -L From the formula regarding the amount of axial center proximity of the two cylinders of 60, it is theoretically expressed as the following formula.

u ” C+ Iln 2 R+ +Cz Iln
2 RzπE R: Roll radius P: Contact load per unit width Subscripts 1, 2: Cylinder number However, in practice, the following constants can be applied.

u -3, I X 10-'112/kg -(1
0-3) Furthermore, the coefficient v0 related to the surface displacement of the contact surface between the work roll and the rolled material is expressed by the following formula based on the old Tchcock theory of roll flatness.

Next, the following formula holds true regarding the displacement between the backup roll, work roll, and rolled material.

YbLi+=Yw+i+ (i=L2−
m) ・−・aaYwzt+ = h<
=) (i=1+2=n)...a:+t That is, in the case of deformation only due to deflection, the axial center displacement between the bank up roll and the work roll, the amount of displacement at the contact surface of the rolled material of the work roll, and the amount of the rolled material The amount of displacement at the work roll contact surface is assumed to be the same for each.

In addition, when the vertical forces of the work rolls are balanced, the bending force of the work rolls is J, and the rolling load is Q.
Then, the formula becomes as below.

Next, the distribution of the rolling load on the rolled material is expressed as shown in the following equation, taking into account the forward tension σ of the rolled material. Here, the width of the rolled material is B, and Q/B = q.

Then, it is expressed as θσf (where 1=L2...n)゛...α9.

Furthermore, the center plate thickness is used instead of the average plate thickness T as a base value representing the distribution state. Use. Therefore, h=h0・
...0η holds true.

In addition, the forward tension σ is the elastic modulus of the rolled material.

Then, it is expressed as follows.

σr (=,= E p ・ (ΔT2−Δε1t+
+)...Q81 Here, Δε'i fi) is the difference between the elongation strain of the rolled material in the i-th section and the average elongation strain, and this is called the elongation strain deviation. Furthermore, ΔF,12 is
The average elongation strain deviation that satisfies equation (19-2) is (19
It is expressed as -1>2.

However, in addition, in equation (19-1), the elongation strain deviation Δεl (
i) is given by the following formula using the total plate thickness deviation Δε, (i, and the plastic flow coefficient η).

Δε1(i)=−ηΔεh(i) ” If the reduction rate is 17, the total thickness deviation Δε0.

is H, , H, which can be approximately expressed as if the rolling reduction rate 17 is small. Therefore, from equations 09) to (21), the forward tension σ
0. ．． is expressed as equation (22).

When the above equations are substituted, the following equations (23) to (25) must hold true. First, from the balance of forces in the vertical direction between the work roll and the backup roll, by substituting equations (3), (4), and (6) into the measurement, -'ip
, 1 (('rt7w +cxrtb)
・Δx−uP1j++1 10Σqノ ・αIJW 'Δx −(Kl + Kw
) w1 (However, i-1, 2...m) Also, when formulas (5) and (7) are substituted into the relational expression α1 of the displacement between the work roll and the rolled material, (where, i-1 ,2
...n) ...(24) Furthermore, the forward tension σf(!,
Substituting equation (22) representing (where id, 2...n)...(25) Solving the above simultaneous-order equations of equations (23) to (25), 00 equation, and αω equation. , unknown number P, <However, 1=L2...m).

qi (However, I□L2 ”・n) + ht=, (
However, i = 1.2...n), Kb, and Kw are determined, and these unknowns are substituted into the predetermined formula to calculate the axial displacement of the work roll or the axial displacement of the back unroll, and this calculated value is is identified as the deflection of the roll, and the amount of deformation due to the flattening of the work roll at the contact surface of the rolled material is calculated based on a predetermined formula.

In addition, in plate rolling using the method of the present invention, the calculation error of gauge meter plate thickness has been reduced from ±80 μm to ±45 μm, and furthermore, the plate thickness error due to cent amplifier control has been reduced to ±12 μm.
It decreases from 0 μm to ±75 μm.

Furthermore, although this embodiment has been described with respect to thick plate rolling, the method of the present invention can also be applied to plate thickness control in hot rolling and cold rolling.

〔effect〕

The method of the present invention separates and calculates the deformation amount of the rolling mill into the roll system deformation amount and the housing system deformation amount, thereby making it possible to identify the factors that cause each deformation and the deformation amount in accordance with the deformation timing. Therefore, the gauge meter plate thickness is specified based on the amount of deformation of the rolling mill, and the roll opening degree is determined based on the gauge meter plate thickness, thereby providing an excellent effect of improving the plate thickness control accuracy of the rolled material.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a plate rolling mill according to the present invention, FIGS. 2 and 3 are schematic diagrams showing the concept of the method of the present invention,
FIGS. 4 and 5 are schematic diagrams of the roll section according to the method of the present invention. 1... Roll part 2... Housing 3... Control part 4... Load cell 11... Work roll 12.
... Bank unroll 31 ... Data input section 32
... Housing system deformation amount calculation device 33 ... Roll system deformation amount calculation device 34 ... Roll opening degree control device patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono Figure 2-P Name 3 Figure 4 Illustration 5

Claims (1)

[Claims] 1. A plate thickness control method in which the thickness of a rolled material is specified as a gauge meter plate thickness based on the calculated amount of deformation of a rolling mill, and the roll opening degree is determined according to this gauge meter plate thickness. In this method, the deformation amount of the rolling mill is separated into the roll system deformation amount and the housing system deformation amount, and a predetermined formula for calculating the roll system deformation amount is set, while the housing system deformation amount is determined by the roll tightening. By subtracting the amount of roll system deformation at the time of roll tightening calculated based on the predetermined formula from the amount of deformation of the rolling mill determined from the elastic characteristic curve obtained from the actual measurement value, Then, during rolling, the roll system deformation amount is calculated based on a predetermined formula, and the housing system deformation amount is calculated based on the rolling load, and the sum of these roll system deformation amounts and housing system deformation amounts is calculated during rolling. A method of controlling plate thickness using a rolling mill, characterized in that the amount of deformation of the machine is determined.