JP2601975B2 - Adjustment method of rolling load measuring device for sheet rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for maintaining the accuracy of a load measuring device of a sheet rolling mill having a rolling load measuring device.

[0002]

2. Description of the Related Art Rolling load measurement of a plate rolling mill is an important measurement which can be said to be indispensable in order to ensure the thickness accuracy of a rolled material. At present, most rolling mills measure the load of a rolling device. Equipped with a load measuring device. The measured value of the rolling load is used for estimating and controlling the thickness variation during rolling through the estimation of the elastic deformation of the rolling mill based thereon. From this viewpoint, the accuracy of the rolling load measuring device is very important, and a very expensive rolling load measuring device having excellent detection accuracy and durability is often used. Therefore, the relative accuracy of the rolling load measuring device is considered to be very high, but the absolute accuracy depends on how to perform the zero adjustment of the rolling load measuring device, and further until the rolling load is transmitted to the rolling load measuring device. In such a case, disturbances such as the weight of the roll and the spindle, friction between the roll chock and the housing, and the like are present, so that the situation is not necessarily highly accurate. At present, the zero point adjustment of the rolling load measuring device seems to employ various methods for each factory, but is roughly divided into the following three types.

[0003] Adjustment is not particularly adjusted after assembling in a rolling mill, as it is at the time of shipment from a measuring apparatus maker. That is, a method in which the rolling load measuring device itself sets the time point when no load is applied to a zero point. The zero point is defined as the time when the roll balance force is applied so that the upper roll system does not separate from the reduction device or cause slip between the rolls. However, it is a method of adjusting at the time of assembling the rolling mill based on the calculated value based on the roll balance force and the weight of the roll or the like or the actually measured value, and thereafter performing only electrical checks. A method in which the roll balance force is actually applied with the roll gap open at the time of regular repair or the like, and that state is set to the zero point of the rolling load measuring device.

[0004] The roll balance force referred to here is:
Generally, this means a force for pressing each roll chock in a direction opposite to the rolled plate surface in a hydraulic system, and in the case of work rolls, the roll bending device and the actuator referred to in the present invention are often the same. However, in the case of a roll bending device, in order to positively control the deflection of the roll, it is usual that the hydraulic pressure in the working cylinder is frequently and accurately controlled for each rolling condition. In many cases, the apparatus has a pressure detection device capable of detecting the pressure of the hydraulic oil sent to the cylinder with high accuracy, and performs feedback control so as to obtain a predetermined pressure. On the other hand, when we say role balance,
There is almost no change from the hydraulic pressure set in advance by a pressure control valve or the like, and therefore, in many cases, a highly accurate pressure detecting device is not provided.

[0005]

As described above, the main purpose of measuring the rolling load is to improve the thickness accuracy of the rolled material. However, there is a need for a method of improving the thickness accuracy using a rolling load measuring device. Is roughly divided into the following three methods. (1) The thickness variation is predicted in consideration of the mill deformation based on the relative change in the rolling load, and rolling reduction is performed to compensate for the variation. (2) The absolute value of the sheet thickness during rolling is estimated in consideration of the mill deformation from the absolute value of the rolling load, and rolling reduction is performed so as to obtain a predetermined sheet thickness. (3) In setting calculation of the rolling load to be performed for setting the rolling device before rolling, the deformation resistance, the coefficient of friction, and the like are learned by referring to the previous rolling load actual value of the same material in the previous calculation.

[0006] In the above-described technique for ensuring the thickness accuracy, it is important that the relative accuracy of the rolling load measuring device is important in (1) and the absolute accuracy of the rolling load measuring device is important in (2) and (3). Become. Particularly, in order to ensure the absolute accuracy of the detection of the rolling load, the above-mentioned adjustment methods such as above have been conventionally performed, but the original method of accurately detecting the load acting between the work roll and the rolled material is used. The most reasonable zero adjustment method at present for the purpose is

However, even when the above method is adopted, the roll balance force is not controlled by a sufficiently calibrated measuring device in most cases, and the roll balance force is exerted by the friction between the roll chock and the housing. The difference between the force and the weight of the rolls and spindles, etc. (if the rolling load measuring device is at the bottom of the rolling mill, plus the weight of the rolls and spindles, etc.) is correctly transmitted to the rolling load measuring device. I doubt it. Furthermore, even if the zero adjustment is performed at the time of periodic repair as in the method described above, if the roll is changed during that time, only the weight difference between the roll at the time of the zero adjustment and the current roll will be zero point. Will cause an error.
Further, in the conventional method, it is impossible to inspect the change over time in the sensitivity of the rolling load measuring device, and at present it is necessary to rely on the accuracy at the time of shipment from the manufacturer.

As described above, the conventional method of maintaining and controlling the accuracy of the rolling load measuring device is not sufficient, and the error of the rolling load measurement resulting therefrom is a hindrance to the improvement of the accuracy of the rolled sheet thickness. . On the other hand, in the present invention, a method for maintaining the accuracy of a rolling load measuring device for solving the above problems of the conventional method and improving the accuracy of the measurement of the rolling load measuring device for both relative values and absolute values is disclosed. I do.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the gist of the present invention is to provide a sheet rolling machine having a hydraulic work roll bending device and a rolling load measuring device for measuring the load of a drafting device. In the method of adjusting the mill, in the state where the roll gap is open during non-rolling, the work roll bending device applies two or more levels of load in the direction in which the upper and lower work roll gaps are opened to supply oil to the working cylinder of the work roll bending device. The relative pressure between the hydraulic pressure detected by the pressure measuring device, the effective area of the working cylinder, the roll bending force calculated from the configuration and number of the working cylinders, and the output of the rolling load measuring device for measuring the load of the rolling device. Analyzing the relationship and calibrating the zero point or both the zero point and the sensitivity of the rolling load measuring device from the correlation between the two. In a method of adjusting the rolling load measuring device of the plate rolling mill, characterized. The sensitivity in the present invention refers to a proportional coefficient between current or voltage and load.

FIG. 1 shows an example of a side view of a typical plate rolling mill. The rolling mill shown in FIG.
-1, 8-2 are supported by reinforcing rolls 9-1, 9-2, and the upper reinforcing roll 9-1 is a reinforcing roll balance device 6--6.
The rolling weight measuring device 1 and the rolling-down device 12 are pressed by 1, 6-2, and are configured to follow the movement of the rolling-down device. Also, the increment work roll bending devices 2-1 and 2-2 and 3-1 and 3-2 also have a role of a roll balance, and work rolls 8-1 through work roll chock 10-1 and 10-2. And 8-2 are pressed against the reinforcing rolls 9-1 and 9-2.

FIG. 1 also shows a roll-bending device 4-1, 4-2 and 5-1, 5-2 for applying a force in a direction opposite to the roll balance for reference. In the method of adjusting the rolling load measuring device, the roll bending force in the direction in which the upper and lower work roll gaps are opened is assumed as the resultant force, and the decrease work roll bending device is not an essential requirement.

The work roll bending device shown in FIG. 1 is of a hydraulic system, and at least the work roll bending devices 2-1 and 2-2 on the rolling load measuring device 1 side have a pressure of hydraulic oil supplied to a working cylinder. It is assumed that the measuring device 14 is provided.

FIG. 1 shows a non-rolling state in such a rolling mill.
With the upper and lower work roll gaps open as described above, a load of two or more levels is applied by the roll bending devices 2-1 and 2-2, the actual value of the oil pressure by the pressure measurement device 14, the effective sectional area of the working cylinder, and the The work roll bending force is calculated from the number, and the correspondence between the work roll bending force and the load measured by the rolling load measuring device 1 is obtained as data.

When the roll gap is opened, the work roll body is unloaded, and the load applied by the work roll bending device is directly transmitted to the rolling load measuring device 1 except for the weight of the roll and spindle. Will be done. Therefore, the applied roll bending force and the value measured by the rolling load measuring device 1 should ideally coincide with each other except for the bias due to the weight of the roll, the spindle, and the like.
The basic idea of the present invention is to calibrate the zero point or both the zero point and the sensitivity.

FIG. 2 shows the actual hot strip mill finish rolling mill No. An example of data obtained by the above method using six stands is shown. In FIG. 2, five levels of roll bending force loads are taken, and all data at the time of loading and at the time of unloading are plotted. In the figure, there is data with a significant difference in the output of the rolling load measuring device for almost the same value of the roll bending force, but this is the difference between when the load is applied and when the load is unloaded. It is considered that the hysteresis caused by the phenomenon became apparent.
When the zero point of the rolling load measuring device is checked only by a constant roll balance force as in the conventional method, such a hysteresis directly becomes an error of the zero point.

On the other hand, by collecting data for a plurality of load levels as shown in FIG. 2 and performing a data process of linearly approximating the data by, for example, the least squares method,
It is possible to minimize the influence of such hysteresis. Generally, the pressure sensor of the hydraulic circuit used in the pressure measuring device 14 is a rolling load measuring device 1.
It is much more compact and inexpensive than it is, and it is easy to periodically exchange pressure sensors that have been fully checked for accuracy, and to install multiple sensors in the same hydraulic circuit to perform accuracy checks with each other. Yes, quality control is very easy. Therefore, there is a great advantage that it is possible to control the accuracy of a rolling load measuring device which is very expensive and cannot be easily replaced by using this.

In FIG. 2, the least squares approximation of the data including the gradient of the straight line is performed for the purpose of calibrating both the zero point and the sensitivity of the rolling load measuring device, but the purpose is to calibrate only the zero point. If so, a linear approximation with a fixed gradient of 1 may be performed as shown in FIG. For example, when both the zero point and the sensitivity are calibrated, the following equation is obtained by linear approximation of the data in FIG.

P _W = 1.039F-59.6 (1) P _D = 1.022F-82.9 (2) Here, P _W and P _D are working-side and driving-side rolling load measuring devices, respectively. The output value, F, is the roll bending force, and the unit is both tonf. In the present invention, since the value of F is considered to be a sufficiently calibrated and accurate value, values obtained by evaluating the true load applied between the upper and lower work rolls on the working side and the driving side are Q _W and Q _D. Then, the equations (1) and (2)
Accordingly, Q _W and Q _D are obtained from the measured values P _W and P _{D according} to the following equations.

Q _W = (P _W +59.6) /1.039 (3) Q _D = (P _D +82.9) /1.022 (4) During the rolling measured and calculated in this manner. Q _W ,
Since the value of Q _D are also included roll bending force F, if you want to estimate the true load acting between the work rolls and the rolling material, Q _W, of each time point from the value of Q _D What is necessary is just to subtract the measured value of the roll bending force F.
Also, instead of performing calculations as in equations (3) and (4),
Substantially similar sensitivity and bias adjustments may be made electrically.

For the purpose of zero point calibration only, FIG.
The following relationship is obtained from the linear approximation in which the gradient is fixed to 1. P _W = F−55.1 (5) P _D = F−80.4 (6) Therefore, the true loads Q _W and Q _D including the roll bending force are calculated from the measured values P _W and P _{D according} to the following equations. Desired. Q _W = P _W +55.1 (7) Q _D = P _D +80.4 (8)

In the above procedure, the weights of the rolls and the spindles are not mentioned at all, but physically, between the roll bending force F and the value detected by the rolling load measuring device 1, the weights of the rolls and the spindles are not included. Should exist. However, since this value is constant unless the rolls are exchanged, the bias component is the bias component of the rolling load detection device itself in accordance with the original purpose of detecting the rolling load, which is to detect the load acting between the upper and lower work rolls. The idea is to absorb in the. Of course, the roll bending force F and the true load Q _W ,
It is also possible to describe the relationship Q _D, but even in this case, the basic of the procedure is the same.

By the way, when the roll is changed after the calibration of the rolling load measuring device by the above-described method, the weight of the roll is different. Will change. In order to cope with this, the rolling load measuring device should be calibrated by the above-described method again immediately after the roll change.
This makes it possible to maintain the same accuracy of the rolling load measuring device as before the roll change.

Further, in the above description, the outputs of the rolling load measuring devices on the working side and the driving side are individually handled. However, even if data obtained by summing the outputs of both are processed, the same effect can be obtained with respect to the thickness control. Can be. Further, in the above description, 4
Although a step rolling mill is taken as an example, the adjusting method of the rolling load measuring device of the present invention can be applied to other rolling mills in exactly the same manner.

[0024]

FIG. 4 shows an actual hot strip mill finish rolling mill No. The data of the correspondence between the roll bending force and the rolling load measuring device was collected at a seven stand (four-high rolling mill) in accordance with the method for adjusting the rolling load measuring device of the present invention. In FIG. 4, straight line approximation with a fixed gradient of 1 is performed only for the purpose of adjusting the zero point of the rolling load measuring device. From these approximate lines, the true loads Q _W and Q _{D are obtained.}
Is calculated by the following equation. Q _W = P _W +90.5 (9) Q _D = P _D +59.7 (10)

On the other hand, FIG. 5 shows data collected after six months from the same rolling mill, from which the following correction formula is obtained. Q _W = P _W +59.6 (11) Q _D = P _D +131.1 (12)

Therefore, when the corrections of the equations (9) to (12) are not performed, the rolling load is 59.6+
This means that there was a bias change of 131.1− (90.5 + 59.7) = 40.5 tonf. If the rolling operation is continued while keeping such a bias change, the thickness accuracy is seriously affected. Of course, a sheet thickness measuring device is provided on the rear side of the rolling mill, and it is possible to perform rolling control to a predetermined thickness after rolling to some extent to perform compensation control. In the rolling of the same material, it is impossible to expect a highly accurate sheet thickness from the first rolling chance. Further, such a bias change has a bad influence on a gauge meter type for estimating an absolute plate thickness from mill deformation, and thus has a serious influence on the control accuracy of the absolute value type automatic plate thickness control.

On the other hand, when the rolling is performed by correcting the equations (9) to (12), the rolling load acting between the rolled material and the work roll can always be accurately measured. The learning coefficient of the resistance formula and the like settles to a constant value at an early stage, and high thickness accuracy can be expected from the first rolled material. Further, since the accuracy of the gauge meter system is also improved, the automatic thickness control accuracy of the absolute value system is also dramatically improved.

[0028]

According to the present invention, by adopting the method for adjusting the rolling load measuring device of a plate rolling mill, it is possible to accurately detect the rolling load acting between the rolled material and the work rolls, Dramatic improvement in plate thickness accuracy can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a side surface of a four-high rolling mill, which is a typical plate rolling mill.

FIG. 2 is a diagram in which a roll bending force is applied when no load is applied to an actual hot strip mill finishing and rolling mill No. 6 stand, a correspondence relationship with an output of a rolling load measuring device is plotted, and the data is linearly approximated by a least square method. is there.

FIG. 3 is a diagram in which data is approximated by a straight line with a gradient 1 for the same data as in FIG. 2;

FIG. 4 is a graph showing the relationship between the output of the rolling load measuring device and the roll bending force applied when no load is applied to the actual hot strip mill finishing and rolling mill No. 7 stand, It is the figure approximated by a straight line.

FIG. 5 is a diagram in which similar data is sampled six months after the data sampling in FIG. 4 is performed using the same rolling mill as in FIG. 4, and the data is approximated by a straight line having a gradient of 1.

[Explanation of symbols]

1 Rolling load measuring device 2-1, 2-2, 3-1, 3-2 Increase work roll bending device 4-1, 4-2, 5-1, 5-2 Decrease work roll bending device 6-1 , 6-2, 7-1, 7-2 Reinforcement roll balancing device 8-1, 8-2 Work roll 9-1, 9-2 Reinforcement roll 10-1, 10-2 Work roll chock 11-1, 11-2 Reinforced roll chock 12 Roll-down device 13 Housing 14 Work roll bending device Operating oil pressure measuring device

Claims (1)

(57) [Claims] In a method for adjusting a sheet rolling mill having a hydraulic work roll bending device and a rolling load measuring device for measuring the load of a drafting device, the work roll bending device is provided in a state where a roll gap is open during non-rolling. By applying two or more levels of load in the direction of opening the upper and lower work roll gaps, the hydraulic pressure detected by the pressure measuring device for the supply oil to the working cylinder of the work roll bending device, the effective sectional area of the working cylinder and the working cylinder Analyze the correspondence between the roll bending force calculated from the configuration and the number, and the output of the rolling load measuring device that measures the load of the rolling-down device, and determine the zero point or the zero point and the sensitivity of the rolling load measuring device from the correlation between the two. A method for adjusting a rolling load measuring device of a plate rolling mill, wherein both are calibrated.