JPS63165013A - Method for controlling plate thickness of rolling mill - Google Patents

Abstract

PURPOSE:To correctly control a plate thickness by calculating the displacement amt. of a roll from the roll dimension and plate width and the housing displacement amt. by using the observed value of a mill rigidity coefft. with a tightening method, and calculating the mill rigitity coefft. from those. CONSTITUTION:The roll displacement amt. dR at the center part of a roll per 1000 tons load in a rolling load area is calculated from the roll dimension and plate width. The housing displacement amt. dM per 1000 tons load in the rolling load area is then calculated by using the mill rigidity coefft. with tightening method. The mill rigidity coefft. M is calculated by the equation M=1000/(dR+ dM) by using the roll displacement dR and housing displacement amt. dM calculated respectively. The displacement amt. P/M of a rolling mill is calculated from this mill rigidity coefft. M and rolling load P, and the plate thickness control is thus performed by performing the control of the rolling reduction position of the rolling mill.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a rolling mill plate that predicts the displacement amount of the rolling mill from the mill rigidity coefficient and rolling load, and controls the rolling position based on this predicted value. This invention relates to a thickness control method.

(Prior Art) The roll gap during rolling, that is, the thickness of the rolled plate, is given by the sum of the rolling position S and the amount of displacement δ caused by the rolling load. : h=s+δ+ΔS0 (1) This displacement amount δ is given by the rolling load P and the mill rigidity coefficient M as follows: δ −P/M (2). Therefore, the plate thickness is calculated as h - S + (P/M) + ΔS0 (3) (here, ΔS0 is the zero point correction value of the roll gap).

In controlling the rolling mill, the rolling position S is calculated backward using equation (3) based on the expected value of the plate thickness, etc., and the plate thickness is controlled. Therefore, calculating an accurate value of the mill stiffness coefficient M is a key point in plate thickness control.

As the value of the mill rigidity coefficient M, an actual value M0 of the mill rigidity coefficient calculated from the relationship between the tightening amount and the load in the roll kiss state can be used.

However, the value of the mill stiffness coefficient M depends not only on the elastic properties of the rolling mill during rolling but also on the strip width. Therefore, in the past, the actual value M0 of the mill stiffness coefficient obtained by the tightening method is corrected for the plate width W, and for example, the following (4)
M is calculated using a formula.

M = M, 10m (W, -W)...14
) Here, W8 is a constant constant in each rolling mill, and m
is the plate width coefficient determined in advance from aluminum rolling etc.

(Problems to be Solved by the Invention) The conventional calculation of the mill stiffness coefficient M using equation (4) etc. takes into account the influence of the plate width W, but does not accurately calculate the relationship between M and the plate width W. Not given. Therefore, the value of M used in equation (3) becomes inaccurate. As a result, the accuracy of the gauge meter thickness calculated using the gauge meter equations (3) and (4) deteriorates where the sheet width in the roll pattern is large (changes and cannot be corrected by feedback).

Therefore, the purpose of the present invention is to calculate the accurate value of the mill stiffness coefficient for all plate thicknesses, and to use the gauge meter formula to calculate the displacement of the rolling mill based on this, thereby making it possible to accurately control the plate thickness. An object of the present invention is to provide a method for controlling plate thickness of a rolling mill. In particular, to provide a strip thickness control method for a rolling mill that accurately reflects the dependence of the mill stiffness coefficient on the strip width and can control the strip thickness to a predetermined value with high precision even when the strip width changes suddenly during a roll pattern. The purpose is to

(Means for Solving the Problems) While continuing research to achieve this objective, the inventors of the present invention have focused on the importance of the following fact. The displacement amount δ of the rolling mill is the displacement amount δ of the roll system and the displacement amount δ of the housing system.
It is decomposed into the sum of: δ Shit δyo + 69...
・(5) Here, the amount of displacement of the roll system is the amount of displacement due to deflection and flattening of the work roll and backup roll, and the amount of displacement of the housing system is the amount of displacement due to deformation of the housing, shrinkage of the reduction screw, etc. other than the roll system. This is the amount of displacement due to deformation of . Of these displacement amounts δ and δ8, only δ□ changes depending on the plate width W, and δI does not depend on the plate width W.

Moreover, the displacement amount δ1 depending on the sheet width W can be calculated theoretically with high precision from the roll dimensions and sheet thickness using a roll division model. On the other hand, the value of δ8, which does not depend on the plate width W, can be calculated with high accuracy from the measured value M0.

By the way, the mill stiffness coefficient M is calculated from equations (2) and (5) as follows: M - dP/d δ = dP/(d δ + d δ ) = 1/ (
d 6m /dP+d δ, /dP) ・
・It can be calculated using (6). Therefore, if we calculate the displacement 11 dll and d of δ and δ□ per specified rolling load, and then calculate M using equation (6), the obtained values have extremely high accuracy for each plate thickness. .

Thus, the gist of the present invention is that the mill stiffness coefficient M
Calculate the displacement P/M of the rolling mill from the and rolling load P,
Accordingly, in the plate thickness control method that controls the rolling position of the rolling mill, a) the roll system displacement NdR per predetermined rolling load is calculated from the roll dimensions and the plate width, and b) the housing system displacement amount dH per predetermined rolling load. C) calculate the mill stiffness coefficient M from the roll system displacement l1d11 and the housing system displacement amount dR calculated in steps a) and b), respectively. A method of controlling plate thickness of a rolling mill, comprising: calculating the thickness of a rolling mill;

For example, the predetermined rolling load P0 in step a) is 10
00), and first calculate the value dRl of the roll system displacement amount δ7 per this load. Since the dimensions of the work roll and backup roll are known, if the load and plate width are given, d8 can be calculated theoretically using a split model as the sum of the roll deflection amount and the contact flattening amount. In addition, it is preferable to use an approximation formula of the calculation formula based on the division model to calculate dR in the actual operation.

In step b), the same rolling cylinder ff1p as in step a) is used.
Since the value dRI of the housing system displacement amount δ per o does not depend on the sheet width, it is approximated by the predetermined rolling load P calculated by the following formula and the housing displacement position dMo in the roll kiss state per per o (dlI kqdM). .

dllo≧(P@/Ml)−da. ...(7) However, dR. is the amount of roll system displacement per load P0 in the roll kiss state, and can be calculated using the split model (or its approximate expression) in the same way as in step a). Also M
o is an actual value of mill rigidity measured by the tightening method, and is measured at each roll chance.

It is also possible to use the value of dHo obtained by equation (7) as it is as the value of dH. However, it is preferable to calculate dRI as follows. That is, the actual value (average value) of dH for the relevant rolling mill is calculated in advance for each roll chance, and then calculated from equation (7) for each corresponding roll chance. Compare with the calculated aSO. From this, dH and d
Find the relational expression % formula % that holds true between lTo (a and b are constants), and calculate di using formula (71) and formula (8).

Next, in step C), M is calculated as follows: M=pH/(dm+dH) (9).

Control of the plate thickness is performed accurately by using the value of M calculated by equation (9) for M in equation (3) above.

(Embodiments) Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The rolling mill position control is based on the above equation (3). The calculation of M in formula (3) is performed in steps a), b), and c) as described above. Each step will be explained separately below.

a) Calculation of dR dR is the load in the relevant rolling load range (1°00)
The amount of roll displacement at the center of the roll per roll is used.

The roll system displacement amount δ is the deflection of the bank-up roll axis δ□, the contact flatness δ■ between the bank-up roll and the work roll, and the contact flatness δ between the work roll and the rolled material. (δ, = δ1 + δ. + δ.), and the amount of deformation δ and δ is the sum of the three. , δ113 can be accurately calculated using a well-known division model from the plate width W, the roll diameters of the work roll and backup roll, roll barrel length, and neck length. dlI is 1000 of the value of δ1 at the center of the roll
Converted amount per ton; dR-6m/1000 (++uw/)n]...
(10) However, in calculating δ8 in actual operation,
Preferably, an approximation of equation (10) as a function of plate width and roll dimensions is used to simplify the calculations.

b) Calculation of dH For dR, use the displacement amount of the housing system per 1000 tons of load in the relevant rolling load range (dll-δK
/1000 (sm/)n]).

The amount of displacement in the housing system does not depend on the plate width, but there are many factors such as elongation of the housing, contraction of the reduction screw, deformation of the liner, etc., and it is also affected by the contact state of each of these factors. be. Therefore, its value differs for each daily roll chance.

However, dH can be predicted from the mill stiffness coefficient M0 measured by the roll tightening method. That is, by using the measured value M of roll tightening, it is possible to accurately calculate the rigidity of the housing system of the mill, which varies for each roll chance.

The total displacement of the mill in the roll kiss state can be determined from the mill stiffness coefficient M0 determined by the tightening method. Therefore, from this value, the displacement amount of the roll system in the roll kiss state 6
By subtracting the mouth, d) IO is determined by the amount of deformation of the housing system in the roll kiss state: dR. = (1000/Me) -d l. ...(1
1) However, dllll is d in step a) above.
A value calculated using the approximation formula of the partitioned model in the same manner as the calculation of l is used.

Furthermore, the housing system displacement I a I per 1000 tons
The actual value of + is calculated from the measured value of the mill displacement amount δ, and the average value of dH is calculated for each roll chance, and this is compared with dlIO calculated by equation (11).

O in Figure 1 is (d step 5) at each roll chance.
This is a plot of points corresponding to . As can be seen from the figure, dllO and dN are approximately equal. However, in order to accurately calculate the value of the housing system displacement amount dH, it is necessary to
R. It is preferable to obtain a relational expression expressed by from FIG. 1 and calculate dll using this relational expression. In the case of Fig. 1, for example, dH=0.23+0.88・dol+...(12
) holds true. (The solid line graph in the figure shows this relationship.) Therefore, in this case, dR = 0.23 + 0.88·dR using dHo in equation (11).・ ・ ・
By calculating with (13), dH
o value can be calculated.

c) Calculation of M M to be used in calculating the gauge meter thickness using the above equation (3) is calculated using the following equation using dRl and dN calculated in a) and b) above.

M-t000/(d*+dll)...(1
4) (Effects of the Invention) In the present invention, the displacement amount of the mill is determined by the roll system displacement amount dR, which depends on the sheet width, and the housing system displacement, which does not depend on the roll system displacement amount dR! aM
The mill stiffness coefficient M can be calculated extremely accurately by dividing these values into 2 and calculating these values individually using an appropriate method.

Figure 2 shows the mill stiffness coefficient M actually measured at a certain roll chance (rolled plates are indicated by . for each case W) and the mill stiffness coefficient M calculated by the method of the present invention ((4) above).
The calculated values are shown in the solid line graph). On the other hand, the chain line graph in the figure shows the value of M calculated using the conventional equation (4). As can be seen from this figure, M calculated by the formula (14) according to the present invention matches the measured value extremely well throughout each board width W.

As described above, according to the present invention, accurate values of M can be obtained for all plate widths W. Therefore, the accuracy of the gauge meter thickness does not deteriorate even at a location where the sheet width W suddenly changes during the roll chance.

The upper graph in FIG. 3 shows a portion of the change in finished sheet width W within a certain roll chance. The lower graph compares the deviation in gauge meter thickness calculated by the present invention (○ and solid line graph) with the deviation in gauge meter thickness calculated by the conventional method (. and chain line graph).

(The deviation here is the difference between the actual measured value of the finished plate thickness and the gauge meter thickness, and a deviation of -〇 indicates that the gauge meter thickness matches the actual measured value.) As can be seen from the figure, The gauge meter thickness calculated by the conventional method deviates significantly from the actual thickness at locations A and B where the board width W suddenly changes. On the other hand, the gauge meter thickness calculated according to the present invention compares favorably with the actual thickness at these locations A and B as well.

As described above, according to the present invention, it is possible to maintain the accuracy of the gauge meter thickness even when the sheet width suddenly changes, and to control the rolled sheet thickness to a desired value with high accuracy.

[Brief explanation of the drawing]

Figure 1 is a graph for determining the relational expression used to calculate the displacement of the housing system used when calculating the mill lockability coefficient according to the present invention; A graph comparing the calculated mill stiffness coefficient with the actual measured value; and Figure 3 shows the variation in gauge meter thickness deviation due to changes in sheet width within the roll chance for cases according to the present invention and cases according to the conventional method. This is a comparison graph.

Claims (1)

[Claims] The displacement amount P of the rolling mill is calculated from the mill rigidity coefficient M and the rolling load P.
In the plate thickness control method, which calculates /M and controls the rolling position of the rolling mill using this method, a) the amount of roll system displacement d_R per predetermined rolling load is calculated from the roll dimensions and the plate width, and b) the predetermined rolling load. Calculating the housing system displacement amount d_H per unit using the actual value M_0 of the mill stiffness coefficient by the tightening method, and c) calculating the roll system displacement amount d_R and housing system displacement calculated in steps a) and b), respectively. A method for controlling plate thickness of a rolling mill, comprising: calculating a mill stiffness coefficient M from a quantity d_H.