JPH0824948B2 - Work roll shift mill rolling position control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling position control method suitable for rolling a plate material by a rolling mill (work roll shift mill) having a work roll shift mechanism.

[0002]

2. Description of the Related Art Generally, in a rolling mill (mill), when a load is applied, a roll gap is opened by elastic deformation of liners, screws, rolls and the like which are components of the rolling mill.
This is commonly referred to as mill elongation property. It is also known that there is a difference in mill elongation characteristics between the work side and the drive side. It was thought to be unique to the equipment of the rolling mill.

When there is a difference in mill elongation characteristics, if the plate thickness, plate width, steel type, etc. of the rolled material change, the rolling load changes, and the mill elongation amount on the work side and the drive side has a left-right difference. Then, the thickness of the left and right plates will be different, and the camber
(Horizontal bending of the plate) occurs, which causes rolling trouble such as side guide bumping.

As a means for correcting the difference in mill elongation, there is a method in which the mill elongation characteristic is expressed by a mill rigidity (constant) and the left and right rolling positions are set based on this constant and the predicted rolling load.
For example, as disclosed in Japanese Patent Publication No. 60-3883, the work side rolling load and the drive side rolling load are equally applied to each other, and it is assumed that 1/2 of the predicted rolling load acts on both sides, and the mill elongation amount. As disclosed in Japanese Patent Publication No. 60-3882,
A means for calculating a mill elongation amount by using a constant ratio of the sum and difference of rolling loads, calculating the work side rolling load and the drive side load from this ratio and the next material predicted rolling load, and the like are used.

[0005]

By the way, in recent years, there has been a strong demand for higher precision of the strip thickness in the width direction, and various crown control rolling mills have been introduced. The work roll shift mill is also a type of the work roll shift mill, which moves the work rolls in the width direction according to the plate width to further exert the effect of the roll bender and improve the crown control capability.

However, when the plate crown becomes small, the plate is likely to be displaced from the center during rolling, and camber is likely to occur. That is, when the plate crown is large, when the plate is displaced from the center, the rolling reduction on the edge side far from the center increases, and the plate itself has an action of returning to the center of the rolling mill. This is because the smaller the effect, the smaller the effect.

Another feature of the work roll shift mill is that it can cope with work roll wear dispersion by periodically performing roll shift, that is, it can be used for schedule-free rolling (rolling forward width constraint relaxation rolling). That's right.

However, by making the schedule free,
The rolling load will change greatly for each rolled material, and in the work roll shift mill, compared to conventional rolling mills,
There is a problem that plate passing problems due to camber or the like increase significantly.

Therefore, in the work roll shift mill, it is very important to improve the precision of setting the left and right rolling positions more than the conventional rolling mill. In the work roll shift mill,
When the shift becomes large, the contact length between the work roll and the backup roll becomes small, so that the mill rigidity decreases.

The relationship between the work roll shift and the mill elongation characteristic is obtained by actually shifting in an actual rolling mill and measuring the mill rigidity. An example of the measurement result is shown in FIG. As shown in FIG. 3, the characteristics are different between the work side and the drive side of each rolling mill, and the characteristics are changed by changing the rolls.

Therefore, in the rolling position setting method according to the above-mentioned conventional technique, the mill elongation characteristic is given by a constant, and when the work roll is shifted, the change in the mill elongation characteristic is not taken into consideration. Becomes insufficient.

It was thought that the difference in rolling load in the shift mill originally did not occur due to the point symmetry of the mechanism, but in an actual machine, due to looseness of the rolling machine, etc., each rolling machine and each rolling machine It turned out that it changed for every condition.

FIG. 4 shows an example of the result of an investigation on the relationship between the load difference rate and the work roll shift amount. here,
The load difference rate was defined by dividing the difference between rolling loads by the sum of rolling loads. As is clear from FIG. 4, the conventional means for making the method of applying the predicted rolling load constant or uniform does not make sense.

The present invention is intended to solve such a problem, and even for a rolling mill having a work roll shift mechanism, it is possible to reliably prevent the occurrence of a camber of a plate material and obtain a stable leading edge threading property. Thus, it is an object of the present invention to provide a method for controlling the rolling position of a work roll shift mill that can significantly reduce rolling troubles in the rolling process.

[0015]

In order to achieve the above object, the method for controlling the rolling position of a work roll shift mill according to the present invention is such that when a sheet material is rolled by a rolling mill having a work roll shift function, it is rolled. A method for adjusting and controlling the rolling positions of the work side and drive side in rolling the next material in order to prevent the occurrence of camber in the plate material,
Based on the work roll shift amount, the strip width of the rolled material, and the predicted load at the time of rolling the next material, the mill elongation characteristic function of each of the work side and drive side and the predicted load of each work side and drive side are calculated, and these mills are calculated. Based on the elongation characteristic function and the predicted load, the amount of mill elongation for each of the work side and drive side is calculated to obtain the amount of left and right mill elongation difference, and the left and right reduction positions are changed by the amount of the left and right mill elongation difference. It is characterized by that.

[0016]

In the rolling position control method of the work roll shift mill of the present invention described above, when rolling a sheet material with a rolling mill having a work roll shift function, the work roll shift amount, the rolled material sheet width, and the prediction at the time of the next material rolling are predicted. The amount of difference between the left and right mill elongations is calculated from the mill side characteristic function of each of the work side and drive side obtained based on the load and the predicted load. By changing the left and right rolling positions by that amount, the mill elongation is changed. The rolling position of the work roll shift mill can be adjusted by adjusting the rolling position of each of the work side and drive side according to changes in characteristics and predicted load.
The occurrence of the camber is prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for controlling a rolling position of a work roll shift mill as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flow chart for explaining the procedure, and FIG. 2 is a tandem stand for the method. 6 is a graph showing the relationship between each stand and the leveling amount when applied, in comparison with conventional control.

The procedure of the rolling position control method according to this embodiment will be described with reference to FIG. 1. First, the set value of the left and right rolling position of each stand is stored for an arbitrary i-th rolled material (step S1). In the i-th rolling, the load cell of each stand detects the work side (WS) and drive side (DS) rolling loads, and the average value of the tip portion is stored (step S2). Based on the (i + 1) th rolling setting condition, the set value of the rolling position of each stand and the predicted rolling load are calculated (step S3).

Next, the work side and drive side mill elongation characteristics are determined using the change function of the mill elongation characteristics of the work roll shift mill (step S4). The mill elongation property of the work roll shift mill changes depending on roll shift, rolled material strip width, and rolling load.
As a result of analyzing a lot of data, a change function of mill elongation characteristics due to work roll shift was obtained as an expression expressing these changes. The change function of the mill elongation characteristic due to the work roll shift for each of the work side and drive side is expressed by the following equation.

Mw = Mow (1-Aw) Md = Mod (1-Ad) where Mow and Mod are terms indicating mill elongation characteristics in the absence of work roll shift on the work side and drive side, respectively. It can be expressed as follows.

[0021]

[Equation 1]

Further, Aw and Ad are terms showing the influence of the work roll shift, and can be expressed as follows.

[0023]

[Equation 2]

Here, Mw and Md are the mill constants on the work side and drive side, S is the shift amount, L is the roll length, B is the strip width, Pw and Pd are the rolling loads on the work side and drive side, respectively. Ewn, Edn, Fwn, F
dn, Ja, and Jb are coefficients determined by each rolling mill, and subscripts w and d indicate that they are related to the work side and drive side, respectively.

Next, the ratio of the sum of the rolling loads on the work side and the rolling load on the drive side and the difference between the rolling loads are calculated using the function of the shift amount and the work roll taper rolling amount (step S5).
The inventors of the present invention have found that it is possible to predict and calculate the load difference by repeatedly investigating the relationship between the work roll shift amount, the amount of initial processing applied to the work roll, the work roll bender amount, and the load difference rate. . Rolling load difference rate α
Can be expressed as:

[0026]

(Equation 3)

Here, S is a shift amount, T is a roll initial processing amount, D is a work roll bender amount, αo, Can, Cb
n and Ccn are coefficients determined by each rolling mill and each rolling condition.

Predicted rolling load Pclcu of each stand
And the calculated rolling load difference rate α, the predicted rolling loads Pw and Pd on the work side and the drive side are obtained by the following equation (step S6).

Pw = (1 + α) · Pclcu / 2 Pd = (1-α) · Pclcu / 2 Then, in step S4, the mill elongation characteristics of the work side and drive side of each stand calculated based on the rolling setting conditions. Using the functions Mw and Md and the predicted rolling loads Pw and Pd obtained in step S6, the mill elongation amount ΔS on the work side and drive side of each stand is expressed by the following equation.
By calculating w and ΔSd, the difference δΔS between the left and right mill elongations is obtained (step S7).

ΔSw = Pw / Mw ΔSd = Pd / Md δΔS = ΔSw−ΔSd Then, the left-right elongation difference δΔS obtained in step S7 is
As in the following formula, addition and subtraction are performed on the set value of the rolling position of each stand (step S8).

Sw = Sow + δΔS / 2 Sd = Sod−δΔS / 2 Here, Sow and Sod are set values of the rolling position on the work side and the drive side, respectively. Represented by.

[0032]

[Equation 4]

Then, when the i + 1th line is set, the set value of the rolling position corrected as described above is output (step S9),
By changing the left and right reduction positions by the left and right elongation difference δΔS, it is possible to adjust the reduction positions of the work side and drive side according to changes in the mill elongation characteristics and predicted load. The occurrence of camber (rolled material) is reliably prevented.

As described above, according to the method of this embodiment, the occurrence of the camber of the plate material can be reliably prevented even in the rolling mill having the work roll shift mechanism, so that the stable leading edge passing property can be obtained and the rolling can be performed. Rolling troubles in the process can be significantly reduced.

FIG. 2 shows the result of applying the method of the present invention to a tandem stand. Since it is difficult to reproduce exactly the same conditions, the calculated values when the present invention is applied to the same rolled material are shown in order to compare with the conventional control. The amount of manual intervention by the operator at the time of passing the plate tip is performed to supplement the conventional control. It was confirmed that the method of the present invention has such a precision that it does not require manual intervention by the operator, because it is distributed to each rolling mill in a well-balanced manner.

Further, the results of applying the method of the present invention are shown in the table below. As is clear from this table, the frequency of manual intervention of the rolling position by the operator, which was close to 80% in the past, was reduced to 55%. Also, the degree of sudden roll reshuffling due to defective sheet passing was reduced from 1.5% to 1%, confirming that it is extremely effective. In addition, in the table, F1 to F
7 represents each stand number in the tandem stand.

[0037]

[Table 1]

[0038]

As described above in detail, according to the method for controlling the rolling position of the work roll shift mill according to the present invention, the work roll shift amount, the strip width of the rolled material, and the predicted load during the rolling of the next material can be obtained. The left and right mill elongation differences are calculated from the work side and drive side mill elongation characteristic functions and the predicted loads, and the left and right rolling positions are changed by that amount. It is possible to adjust the rolling positions of the work side and drive side according to changes in the rolling conditions, and it is possible to reliably prevent the occurrence of sheet material camber even with a rolling mill that has a work roll shift mechanism, and to significantly reduce rolling troubles during the rolling process. effective.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining a procedure of a method for controlling a rolling position of a work roll shift mill as an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between each stand and the leveling amount when the method of the present invention is applied to a tandem stand, in comparison with conventional control.

FIG. 3 is a graph showing changes in mill rigidity caused by work roll shift.

FIG. 4 is a graph showing changes in load difference rate caused by work roll shift.

Claims (1)

[Claims] 1. When rolling a plate material with a rolling mill having a work roll shift function, the rolling positions of the work side and the drive side in the rolling of the next material are adjusted to prevent the occurrence of camber of the rolled material. It is a method of controlling, based on the work roll shift amount, the rolled material strip width and the predicted load at the time of rolling the next material, the mill elongation characteristic function of each of the work side and the drive side, and the predicted load of each of the work side and the drive side. And, based on these mill elongation characteristic functions and predicted loads,
A work roll shift mill characterized by calculating the amount of mill elongation on each of the work side and drive side to determine the amount of left and right mill elongation difference and changing the left and right rolling positions by the amount of the left and right mill elongation difference. Rolling position control method.