JPH0224163B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for straightening camber of a rolled material during thick plate rolling.

During rolling of thick plates, due to the difference in hardness between the left and right sides of the material to be rolled, the difference in the stiffness (mill constant) of the left and right sides of the rolling mill, and other various factors, there is a There is a problem in that a meandering phenomenon occurs in which the biting position shifts in the width direction, and a phenomenon in which the rolled material curves in the width direction, that is, camber occurs. If this camber is large, the material to be rolled will damage the rolling rolls and guides, and in severe cases may cause damage, causing great damage in terms of time and property. Even if the camber is small,
At curved portions of the rolled material, the planned plate dimensions cannot be achieved, and the product yield, that is, the amount of product/the amount of raw materials, decreases.

One of the major causes of the above-mentioned camber is the meandering phenomenon, and several control methods have been proposed to prevent meandering. However, once a camber occurs, it cannot be corrected by meandering control. Therefore, in plate rolling, a rolling control method has been proposed in which the camber of the material to be rolled is measured and, in order to correct the camber, the thickness of the material to be rolled is varied in the width direction. By the way, all of the conventionally proposed methods are devised based on the concept of camber.
Generally, the amount called camber is used as an index to know how to cut a regular rectangular steel plate from a cut plate. Although there is no established definition, the bulge C at the center of the plate is usually measured by connecting the front and rear edges of the plate as shown in FIG. 12 with a straight line, and this bulge C is called the camber amount. Therefore, it can be said that this is a very rough concept in the process of controlling the bending in the width direction of a rolled material. The bending of the rolled material is not always uniform in the longitudinal direction; some bends, called nose bends, occur only at the longitudinal ends of the rolled material, while others occur only in the longitudinal center. This is because there are bends, and depending on the rolling method, there is a possibility that any bends may occur. In the correction control of such bending, the method of describing the bending determines the quality of controllability. Furthermore, when creating a thickness difference in the width direction of the rolled material, since no automatic method for controlling the thickness difference in the width direction has been established, completely open-loop control has been required. That is,
After measuring the bending of the material to be rolled, the difference between the left and right roll openings of the rolling mill is initially set and the material to be rolled is rolled in that state, or depending on the degree of bending in the longitudinal direction of the material to be rolled. The problem was to appropriately change the difference in opening between the left and right rolls during rolling. In any case,
It was not possible to feed back the difference in thickness in the width direction necessary to correct the camber at each point in the longitudinal direction of the rolled material during rolling, resulting in open-loop control.

By the way, according to the research of the present inventors, when the rolled material originally has a camber, or when the left and right roll openings of the rolling mill are made different, the rolled material easily causes a meandering phenomenon during rolling. . For this reason, even if an attempt is made to straighten an arcuate camber with uniform curvature and the difference in opening between the left and right rolls of the rolling mill is kept constant, the material to be rolled will continue to meander from the initial biting position. Therefore, there is always a tendency that the thickness difference of the rolled material changes in the longitudinal direction of the rolled material, and that the camber cannot be corrected as intended. For these reasons, it is extremely difficult to correct the camber without feeding back the difference in thickness between the left and right plates.

The present invention has been made in view of these problems, and is a method for rolling a rolled plate during thick plate rolling, in which a camber occurring in an intermediate rolling pass during thick plate rolling can be reliably corrected in the next pass. The purpose of this invention is to provide a method for camber straightening of materials.

The present invention provides a camber straightening method for a rolled material in thick plate rolling, in which the longitudinal profile of the widthwise centerline of the rolled material and the widthwise plate thickness at each point in the longitudinal direction are determined in a pass during rolling. The distribution is measured, and from these two measured values, the target plate thickness difference in the width direction at each point in the longitudinal direction required to straighten the camber of the rolled material is calculated, and in the next pass, the rolling load difference between the left and right sides of the rolling machine is calculated. , measure the difference in thickness in the width direction of the rolled material directly under the roll from the amount of meandering and the difference in opening between the left and right sides of the roll,
The above object is achieved by adjusting the horizontal opening degree of the rolling rolls based on the deviation between the measured thickness difference in the width direction and the target thickness difference in the width direction.

That is, in the camber straightening method according to the present invention, when rolling a thick plate, the longitudinal profile of the widthwise center line of the material to be rolled is measured in an intermediate rolling pass, and the widthwise coordinate of the centerline is functionally approximated by the longitudinal direction coordinate. At the same time, the thickness distribution in the width direction at each point in the longitudinal direction is measured, and from these two measured values, the target left and right thickness difference in the width direction necessary to straighten the centerline profile is calculated. In order to calculate the thickness difference in the width direction, which is calculated as a function of the longitudinal coordinate of the material, and which changes in the longitudinal direction in the next pass, we measure the amount of meandering of the material to be rolled at every moment during rolling, and measure the difference in rolling load between the left and right sides of the rolling machine. Measure the difference in opening between the left and right rolls of the rolling mill, calculate the difference in actual thickness between the left and right plates in the width direction from these measured values, and automatically adjust the opening between the rolls on the left and right based on the deviation from the target left and right thickness difference calculated above. By implementing automatic width direction thickness control, an appropriate width direction thickness difference is created over the longitudinal direction of the rolled material, and camber correction of the rolled material is realized.

The present invention will be described in detail below with reference to the drawings.

First, the principle of the method of the present invention will be explained.

Now, as shown in Figs. 1 and 2, a material to be rolled 10 having a bend corresponding to a circular arc with a radius r and a central angle θ and whose center line l _C is a plate width b is being rolled. As a result, it is assumed that the rolled material 12 has a straight shape without bending as shown in FIGS. 3 and 4. Here, in the rolling from the rolled material 10 to 12, assuming that there is no metal flow in the sheet width direction, the left side plate length l _L of the rolled material 10 before rolling, the center plate length l _C ,
The right side plate length l _R , the left side plate thickness H _L , the center plate thickness H _C , the right side plate thickness H _R , and the plate length l of the rolled material 12 after rolling,
Between the left side plate thickness h _L , center plate thickness h _C , and right side plate thickness h _R ,
An opening equation as shown in the following equation is established.

H _L・l _L /h _L = H _R・l _R /h _R = H _C・l _C /h _C = l …(1) Here, the length of the left side plate of the rolled material 10 before rolling, l _L ,
The right side plate length l _R and the center plate length l _C are expressed as shown in the following equation.

l _L = (r+b/2)θ...(2) l _R =(r-b/2)θ...(3) l _C =rθ...(4) Therefore, from equations (1) to (4) above, Rolled material 1 after rolling
The left side plate thickness h _L and right side plate thickness h _R of No. 2 are given by the following equations.

h _L = (h _C / H _C ) (1+b/2r) H _L … (5) h _R = (h _C / H _C ) (1-b/2r) H _R … (6) Therefore, after rolling Assuming that the difference in thickness between the left and right plates of the rolled material 12 is Δh=h _L −h _R , the difference in thickness between the left and right plates Δh is expressed by the following equation.

Δh=(h _C /H _C ) {(H _L - H _R ) + (b/2r) (H _L + H _R )}...(7) Therefore, as shown in Figures 1 and 2 above, In order to correct the bending of the rolled material 10 which has a large camber, the material to be rolled with a thickness difference Δh between the left and right plates as expressed by equation (7) at the point when the center thickness becomes h _C is rolled. It turns out that all you have to do is manufacture it. just,
In reality, there is a metal flow in the width direction of the plate, and there is also strain absorbed inside the rolled material as residual stress, so equation (7) is expressed as Δh = (1 + α) (h _C /H _C ) {(H _L −H _R ) +b/2r(H _L +H _R )} (8). Here, α is the bending relaxation coefficient generally given as a function of plate width and plate thickness,
Determined by experiment.

In actual rolling, it is rare for the material to be rolled to form a neat circular arc with a single radius of curvature r, as shown in FIG. 1 above. In the case of such a circular arc, the method of determining the amount of camber may be sufficient, but in the case of a bend as shown in FIG. 5, control using the concept of camber becomes extremely difficult.
First, it is necessary to determine which part has the amount of camber, and as the target length is made smaller, the amount of camber becomes much smaller. Therefore, in the present invention, attention is paid to the center line l _C of the material to be rolled 10, and the profile of this center line is approximated by an n-th order polynomial as shown in the following equation, for example.

y=f(x) =Cnx ⁿ +C _o-1 x ^n-1 +...+C ₁ x+C ₀ ...(9) Here, x is the longitudinal position of the rolled material 10, y
Similarly, Cn, C _{o-1 .} . . , C ₀ are coefficients. This approximation does not need to be a polynomial as long as the width direction position y is expressed as a function of the longitudinal direction position x, and may be, for example, the following trigonometric function approximation.

y=f(x) = _n 〓 ⁱ⁼¹ A _i sin(2π/l _i )(x+r _i )...(10) Here, A _i is the amplitude, l _i is the wavelength, and r _i is the initial phase.

When calculating the center line profile using the n-th polynomial, the applicant has already filed a patent application in 1983-
As proposed in No. 176697, for example, the following method can be adopted. That is, the method is, first,
The distance between the reference line parallel to the longitudinal direction of the rolled material 10 and the center position of the rolled material 10 is measured at three locations in the longitudinal direction of the rolled material 10, and the center positions measured at two of the locations are connected. The deviation distance between the straight line and the center position measured at the remaining one point is determined, and the rolled material 1 is
The relationship between the displacement distance repeatedly determined at each position in the longitudinal direction of 0 and the longitudinal position of the material to be rolled 10 is determined as an n-2 degree polynomial by regression calculation, and then,
Each coefficient of this n-2nd degree polynomial, any two sets of data used when performing the regression calculation, and each coefficient when the center line profile of the rolled material 10 is approximated as an nth degree polynomial. Each coefficient of the n-th degree polynomial is determined using the relationship established between the two, and the center line profile of the rolled material 10 is approximated as the n-th degree polynomial. Here, the above-mentioned "deviation distance" is the "deviation distance" between the extension of the straight line connecting the center positions measured at two adjacent locations and the center position measured at the remaining one location. Alternatively, the "shift distance" between a straight line connecting the center positions measured at two points at both ends and the center position measured at one point in the center may be used.

Assume that a center line profile y=f(x) as shown in FIG. 6 is obtained by such function approximation. Then, the radius of curvature r(x ₀ ) of the rolled material 10 at any point x ₀ is r(x ₀ )=−(1+f′(x ₀ ) ² )3/2/f″(x ₀ ) …(11) can be approximated as follows, where f′(x) is f
(x) is once differentiated by x, and f″(x) is f(x) is differentiated twice by x.In addition, in Figure 6, the positive direction of the y-axis is the left side in the width direction, and the negative direction is is defined as the right side, and the radius of curvature r(x) is defined as positive when it bulges to the left, that is, when it is convex upward, and negative when it bulges to the right, that is, when it is convex downward.

From equations (8) and (11), Δh (x ₀ ) = (1 + α) (h _C /H _C ) {(H _L (x ₀ )−H _R (x
₀ ))−f″(x ₀ )・b/2(1+f′(x ₀ ) ² ) ^3/2 (H _L
(x ₀ )+H _R (x ₀ ))}...(12) is obtained. This equation (12) gives the target left and right plate thickness difference Δh at the point x ₀ in the longitudinal direction of the rolled material 10.

In actual rolling, the rolled material 10 during rolling
By tracking and knowing the position x ₀ of the rolled material directly under the roll of the rolling mill, the target left and right plate thickness difference Δh at that position can be determined. In addition, the entry side plate thickness H _L
and H _R are measured using a thickness gage in the previous pass, or obtained using a gauge meter method from the rolling load.

By the way, in a rolling situation where the left and right roll openings of the rolling mill are different and the material to be rolled is meandering, the deformation of the rolling mill becomes asymmetrical, as shown in FIG. At this time, assuming that the linear load distribution applied to the rolling mill is a linear distribution as shown in Figure 8, the difference hdf in the thickness of the left and right sheets of the rolled material is hdf = h _L - h _R = E ₁ Sdf + E ₂ Pdf + E ₃ δ...(13) This fact was also confirmed through experiments. Here, Sdf represents the difference in opening degree between the left and right rolls, Pdf represents the difference in rolling load between the left and right sides, and δ represents the amount of deviation of the center line in the width direction of the rolled material from the center line of the rolling mill (referred to as meandering amount). E ₁ , E ₂ , E ₃ are roll barrel length, plate width,
This is a coefficient expressed by numerical values such as roll crown and mill rigidity characteristics. These coefficients can be considered to be values that do not change during rolling, and therefore, the difference in the left and right roll openings is
If Sdf, the left and right rolling load difference Pdf, and the meandering amount δ can be measured during rolling, the measured left and right plate thickness difference hdf at that time will be given by equation (13).
In FIG. 7, 2 and 4 are upper and lower backup rolls, respectively, and 6 and 8 are upper and lower work rolls, respectively.

The target left and right plate thickness difference Δh (x ₀ ) of the rolled material 10 expressed by equation (12) and the measured left and right plate thickness difference expressed by equation (13)
By configuring a control system that adjusts the left and right roll opening difference Sdf from hdf, it is possible to automatically control the left and right plate thickness difference, similar to so-called automatic plate thickness control (AGC).

FIG. 9 shows an example of the configuration of the control system. The difference between the measured left and right plate thickness difference hdf and the target left and right plate thickness difference Δh (x ₀ ) is calculated proportionally.
Through so-called PID control that performs differentiation and integration, a roll left/right opening difference command value Sdf ^* is output to the reduction control device. Accordingly, the rolling reduction control device actually sets the roll left and right opening difference to Sdf, thereby changing the left and right plate thickness difference of the material to be rolled, and at the same time changing the meandering amount. Then, measure the changed meandering amount, the left and right rolling load difference Pdf generated as a result of the changed left and right opening difference, the meandering amount δ, and the roll left and right opening difference Sdf, and determine the measured left and right plate thickness difference that should be fed back. Ask for hdf.
By repeating this series of operations, left and right plate thickness difference control can be automatically performed. The part surrounded by the dotted line in FIG. 9 can be assembled using an analog computer or a digital computer with high calculation speed.
According to the above method, it becomes possible to delicately correct any bends in the rolled material.

An example of an apparatus for implementing the present invention will be described below with reference to FIG. 10.

When the material to be rolled 10 is being rolled by the rolling mill 20 in the direction of arrow A, the left and right rolling loads P _L and P _R detected by the left side load cell 22 and right side load cell 24 of the rolling mill 20 and the rolling mill 20 Roll left and right opening detected by the roll left and right opening gauges 32 and 34
Based on S _L , S _R and the meandering amount δ detected by the meandering amount measuring device 26 of the rolled material 10 , the left and right plate thicknesses H _L , H _R on the rolling mill side of the rolled material 10 are calculated using a gauge meter type.
and the center plate thickness H _C are calculated by the calculator 38,
The average plate thicknesses H _L i , H _R i , and H _C i of each longitudinal minute section Δxi of the rolled material 10 are stored in the memory 40 . The amount of meandering δ means the amount of lateral deviation of the plate directly under the rolling mill (the amount of deviation from the center of the rolling mill), but there are many difficulties in actually measuring this directly under the rolling mill. The amount of lateral deviation of the plate is measured near the rolling mill, and from this the amount of lateral deviation of the plate directly below the rolling mill is often predicted (estimated). Rolled material 10
At the same time, using a thickness gauge 28 such as a radiation thickness gauge,
Thickness distribution in the width direction, that is, left and right plate thickness and center plate thickness H _L ,
H _R and _HC are actually measured. This is also the average plate thickness H′ _L i, H′ _R for each minute section Δxi in the longitudinal direction of the rolled material 10.
i, H′ _C i. The rolled material 10 is further subjected to initial data for calculating the bending of the rolled material by the bending shape detector 30, and the bending shape is determined by using the calculator 36 into the form of the above-mentioned function type y=f(x). It is expressed as Plate thickness distribution H _L i,
From H _R i, H _C i (or H' _L i, H' _R i, H' _C i) and the function y=f(x), the calculator 44 calculates a longitudinal minute interval according to equation (11). The target left and right plate thickness difference Δhi for each Δxi is determined and stored in the memory 46. The material to be rolled 10 finishes rolling in the direction of arrow A, then begins rolling in the opposite direction, and the load cell 2
At the same time as 2 and 24 detect the load, this is regarded as the plate end and automatic control of the left and right plate thickness difference is initiated. The control calculator 48 receives pulses from the pulse generator 50 in accordance with the rotation of the rolling mill 20, tracks the rolled material, and determines which section Δxi the position of the rolled material directly below the roll corresponds to. For example, if a portion of Δxj is being rolled at a certain point, the target plate thickness difference Δhj is retrieved from the memory 46, and
This is given as the target plate thickness difference. The control calculator 48 calculates the roll left and right openings S _L , S _R , and the left and right rolling loads.
P _L , P _R , and meandering amount δ measured by meandering amount measuring device 26
The arithmetic processing within the dotted line section in FIG. 9 mentioned above is performed mainly by taking in the information, and a roll left/right opening degree difference command value Sdf ^* including feedback is output to the reduction control device 52. Note that the coefficients E ₁ , E ₂ , and E ₃ in FIG. 9 are calculated by the calculator 54 before the start of this pass based on the width of the material to be rolled 10, the roll barrel length of the rolling mill 20, the mill rigidity, the roll crown, etc. It is calculated and given to the control calculator 48 before the start of control. Rolling down control device 5
2 performs horizontal position control of rolling down based on the roll opening degree difference command value Sdf ^* . The control parameters of the PID control shown in FIG. 9 may be adjusted by performing simulation using a process model as shown in FIG. 9, or by actually performing rolling. However, since it is difficult to adjust by actual rolling, it is better to design by simulation to some extent.

In the above description, each computing unit is assumed to be independent, but it is of course possible to perform several initial calculations at once using, for example, a rolling mill control calculator. However, it is preferable to configure only the control calculator 48 independently from the viewpoint of calculation speed.

Figure 11 shows the state of the center line of the rolled material when lead was rolled using the method of the present invention using a model mill that was approximately 1/15 the size of the actual rolling mill. . The lead used for rolling was 5 mm thick, 300 mm wide,
It was made of pure lead with a length of 500 mm and had an arc shape with a radius of 500 mm as shown by the broken line 60 in Figure 11. When this lead plate is rolled to a thickness of 4 mm, automatic left and right plate thickness difference control is carried out in order to give the target left and right plate thickness difference calculated based on the present invention. A lead plate with a centerline shape could be obtained. As is clear from this figure, when the bending is corrected by the method of the present invention, the bending can be removed to almost zero, confirming the effectiveness of the present invention.

As explained above, according to the present invention, it is possible to easily correct the bending of the rolled material in the longitudinal direction, which has been difficult in the past, and the entire length of the rolled material in the longitudinal direction can be corrected by closed-loop control. The effect is that it is possible to obtain a straight band shape without bending over the entire length.

[Brief explanation of drawings]

Fig. 1 is a plan view of a rolled material having an arc-shaped camber with radius r, for explaining the conventional method for straightening the bending of a rolled material, and Fig. 2 is a plan view taken along the - line in Fig. 1. The sectional view, FIG. 3, is a plan view of the rolled material shown in FIG. 1 after camber straightening rolling.
The figure is a sectional view taken along the line - in FIG. 3, FIG. 5 is a plan view of a rolled material having complicated bends, and FIG. 6 is a cross-sectional view taken along the line - in FIG. Fig. 7 is a diagram showing a function approximation of the center line of a rolled material having a bend in the width direction; Fig. 7 is a cross-sectional view showing a rolling model of a rolling mill; Fig. 8 is a diagram showing the load distribution applied to the rolled material. The line diagram shown in Figure 9 is
FIG. 10 is a block diagram showing an example of a control system of an automatic left and right plate thickness control device in which the method of the present invention is adopted.
FIG. 11 is a block diagram including a partial plan view, and FIG. 11 is a diagram similarly showing the effect of correcting the bending. FIG. 12 is an explanatory diagram of the camber. DESCRIPTION OF SYMBOLS 10...Rolled material, 20...Rolling machine, 28...Thickness gauge, 36...Bending amount calculator, 44...Target plate thickness difference calculator, 48...Plate thickness difference control calculator, 52...
...pressure control device.

Claims (1)

[Claims] 1 During thick plate rolling, the longitudinal profile of the widthwise center line of the rolled material and the widthwise plate thickness distribution at each point in the longitudinal direction are measured during a pass during rolling, and the thickness distribution of the rolled material at each point in the longitudinal direction is measured. The target plate thickness difference in the width direction at each point in the longitudinal direction of the rolled material required to correct the camber of the material is calculated, and in the next pass, the rolling load difference between the left and right sides of the rolling mill, the amount of meandering, and the difference between the left and right rolling rolls is calculated. Measure the difference in thickness in the width direction of the rolled material directly below the rolls from the difference in opening, and then adjust the left and right opening of the rolls based on the deviation between the measured thickness difference in the width direction and the target thickness difference in the width direction. A method for straightening the camber of a rolled material in thick plate rolling, the method comprising adjusting the camber of a rolled material.