JPH06218416A - Method and device for controlling speed of rolling mill - Google Patents

Abstract

PURPOSE:To surely prevent the drop of the rotational speed of work rolls when a material to be rolled is bitten into a rolling mill by only simple calculation. CONSTITUTION:The extrapolated value of torque arm is calculated with a torque arm arithmetic device 20, stored in a memory 22 and rolling load that is detected with a load cell and torque arm extrapolated value stored in the memory are multiplied with a multiplier 26. Obtained rolling torque is added to torque command value that is outputted from a speed controller 10, power control command value is calculated with a torque controller 12 using the torque command value and an impressed voltage to a motor 16 from the power unit 14 is controlled based on that command value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applicable to control of a rolling mill for continuously rolling a material to be rolled, and a speed control method and apparatus suitable for the rolling mill, and more particularly, the tip of the material to be rolled is caught in a rolling stand. TECHNICAL FIELD The present invention relates to a rolling mill speed control method and device capable of preventing a reduction in the rotation speed of a work roll when the rolling is performed and accurately fitting a material to be rolled to a target dimension from the tip.

[0002]

2. Description of the Related Art Generally, a rolled material S such as a metal strip is used.
2 is a continuous rolling mill in which a plurality of rolling mills (stands) consisting of work rolls W and backup rolls B as schematically shown in FIG. 2 are continuously provided (a four rolling mill is shown in the figure for convenience). In the case of rolling in, the so-called speed control method is widely used in which the work roll W is driven by an electric motor and the torque of the electric motor is adjusted so that the rotation speed of the electric motor matches a predetermined target speed.

This speed control method will be described below in the case of using the speed control device shown in FIG.

The above speed control device comprises a speed controller 1
0, a torque controller 12, an electric motor power supply device 14, and an electric motor 16.

Here, the speed command value corresponding to the target rolling speed is compared with the speed feedback value based on actual measurement, and the speed controller 10 calculates the torque command value according to the deviation. This torque command value is compared with the torque feedback value from the electric motor 16, and the power supply control command value is obtained in the torque controller 12 according to the deviation,
It is output to the electric motor power supply device 14, and the electric motor power supply device 14 adjusts the voltage applied to the electric motor 16 according to the power supply control command value. By doing so, the rotation speed of the electric motor 16 is made to coincide with the speed command value, and the rolling speed by the work roll driven by the electric motor 16 is made to coincide with the target value.

However, when disturbance such as rolling torque is applied to the load torque of the electric motor 16, the speed of the electric motor fluctuates.
For example, at the moment when the material to be rolled is caught in the rolling mill, the rolling torque rises instantly from 0, which causes a large reduction in speed. Particularly, in the speed control method using the apparatus of FIG. 3, the torque is corrected after the speed feedback largely drops, so that the correction operation is slow and takes about 50 to 200 msec even with the current technology.

When the speed of the work roll of a certain stand decreases, it becomes impossible to synchronize with the speed of the material to be rolled on the upstream stand, so that the tension of the material to be rolled fluctuates, which causes the fluctuation. The width and thickness of the product change. If the dimensions of the product change in this way and deviate from the tolerance, the product must be cut off, which leads to a decrease in yield.

As a technique for solving this problem, the torque disturbance estimator 18 for estimating the torque disturbance from the detected speed and the torque feedback value is provided in the control device shown in FIG. 2 as shown in FIG. Is proposed, and a control method is proposed in which the torque disturbance value estimated here is reflected in the torque command value.

Although various estimation methods used in the torque disturbance estimator 18 are known, a representative one uses an observer theory.

[0010]

However, since the torque disturbance estimator 18 also estimates the disturbance torque based on the drop in the velocity feedback, the correction operation is delayed by about 30 to 100 msec, which is sufficient. The reality is that control accuracy cannot be obtained.

Further, since the torque disturbance estimator 18 needs to execute high-speed and complicated calculations, there is a problem that the apparatus itself becomes expensive and a great deal of time and labor is required for trial run adjustment and maintenance. .

The present invention has been made to solve the above-mentioned conventional problems, and the rotation speed of the work roll is reduced by a simple calculation, for example, when the material to be rolled is caught in the roll. It is an object of the present invention to provide a speed control method and device for a rolling mill, which can reliably prevent

[0013]

The present invention provides a speed control method for a rolling mill which controls the speed of the rolling mill when rolling a material to be rolled by a continuous rolling mill in which a plurality of rolling mills are connected in series, The object is achieved by controlling the speed of the rolling mill with the rolling load measured during rolling and the rolling torque obtained from the torque arm.

The present invention is also such that the torque arm is obtained by using at least the thickness of the material to be rolled on the inlet side and the outlet side of the rolling mill and the rolling load.

The present invention also provides a plurality of rolling mills, load measuring means for measuring the rolling load when the material to be rolled is rolled by the rolling mill, and a speed controller for calculating a torque command value based on the speed command value. And a speed controller for a rolling mill including a torque controller that calculates a power supply control command value for controlling the driving force of the electric motor based on the torque command value, the torque arm calculating means and the torque arm calculating means By obtaining the rolling torque on the basis of the torque arm and the rolling load, the above-mentioned problem is achieved in the same manner.

[0016]

In the present invention, since the rolling mill speed is controlled by the rolling load measured during rolling and the rolling torque obtained from the torque arm, the rolling torque which is the main factor of the torque disturbance is directly detected. However, it is possible to control the torque of the electric motor according to the rolling torque, and as a result, it is possible to prevent a decrease in the rotation speed of the work roll that occurs when the material to be rolled is caught in the rolling mill. .

Therefore, it is possible to prevent the correction operation from being delayed as in the conventional control method of controlling the torque of the electric motor after detecting the decrease in the rotation speed.

The control principle of the present invention will be described in detail below.

The present invention directly detects the rolling torque, and the method is as follows.

The rolling torque at the time of tensionless rolling is as follows (1)
As shown in the equation, it is known to be expressed by the product term of rolling load and torque arm.

G = α × P (1) G: rolling torque [t-m] α: torque arm [m] P: rolling load [t]

The rolling load can be measured by a rolling load meter (for example, a load cell mounted between the chock of the backup roll and the housing) that is generally attached to the rolling mill. If the arm is known, the rolling torque can be calculated.

Next, the method of obtaining the torque arm will be described. It is known that the torque arm α is generally given by the following equation (2).

Α = λ × {R ′ × (H−h)} ^1/2 × (R / R ′) (2) λ: Torque arm coefficient R: Work roll radius [m] R ′: Flat work roll Radius [m] H: Inlet plate thickness [m] h: Outlet plate thickness [m]

In the above equation (2), the torque arm coefficient λ is a value determined by the friction condition, but it is known that it is about 0.5 in the case of hot rolling.

The flat work roll radius R'is determined by the following Hitch
The cock formula is known.

R ′ = [1+ {Co / (H−h)} × P] × R (3) Co = 16 × (1-ν _o ² ) / (π × Eo) (4) R: Work Roll radius [m] ν _o : Roll Poisson's ratio Eo: Roll Young's modulus [t / m]

From the equations (3) and (4), the flat work roll radius R'can be obtained by using the rolling load P. As the rolling load P, an actual measurement value of a rolling load meter at the time of rolling may be used, but in order to prevent the rotation speed of the work roll from decreasing when the material to be rolled is bitten, before rolling, It is better to calculate the torque arm in advance using the predicted rolling load. Here, the case of using the predicted rolling load will be described.

This predicted rolling load is given by the following equation (5).

Pr = Q × {R ′ × (H−h)} ^1/2 × K × W (5) Pr: Predicted rolling load [t] K: Deformation resistance of metallic material [t / m ² ] Q : Rolling force function W: Plate width of rolled material [m]

In the above equation (5), the deformation resistance K of the metal material (rolled material) is a value determined by the composition of the material and the temperature. Further, the rolling force function Q can be obtained by using the widely known Shida equation or the like.

Since the above equation (5) includes R'on the right side, it is necessary to obtain R'and Pr by simultaneous equations with equation (3). Regarding this method, numerical calculation such as Newton's method is required. Can be obtained by As an example,
“Plate rolling theory and practice” The method described on page 40 of the Iron and Steel Institute of Japan, September 1984 can be mentioned.

This method is the Bland & Ford method, and the roll flat equation (3) is used, and the unknown quantities to be obtained are R'and P. In this case, as shown in FIG.
In the -R 'plane, the roll flat type becomes a straight line.

First, it is assumed that there is no roll flatness, points are obtained by the rolling load equation, and the value of P is used to obtain the rolling load at the point corresponding to R'obtained from equation (3). Here, considering that the rolling load formula is approximated by a straight line,
Since this can be approximated by a straight line connecting the points (chain line in the figure), a new approximate value of R'is obtained by the intersection of this straight line and the equation (3), and the corresponding point gives the approximate value of P. .

After that, it is sufficient to continue until the convergence is sufficiently obtained such that the next approximate value of R'is obtained at the intersection of the straight line connecting the points and the equation (3). This method is an application of the Newton method used to obtain a numerical solution of a non-linear equation, but a very highly accurate solution can be obtained in a short time.

The torque arm can be calculated from the inlet side plate thickness H, the outlet side plate thickness h, and the rolling load P by using the respective formulas detailed above.

The torque arm α thus obtained
And the rolling load P measured by the rolling load meter (formula (1) above), the rolling torque G can be obtained. By adding the obtained rolling torque G to the torque command value for the torque controller for controlling the power supply for the electric motor, it is possible to quickly reduce the rotation speed of the work roll that occurs when the material to be rolled is caught in the rolling mill. In addition, it is possible to surely prevent it.

[0038]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a speed control device for a rolling mill according to an embodiment of the present invention.

The speed control device for a rolling mill according to the present embodiment includes, in the device shown in FIG. 3, a torque arm calculation device 20, a memory 22 for storing a torque arm estimated value calculated by the calculation device 20, and Except for including a multiplier 26 that executes the multiplication of the torque arm estimated value read from the memory 22 and the rolling load detected by the load cell 24,
It is substantially the same as that shown in FIG. Therefore,
Descriptions of common parts are omitted. The part surrounded by the broken line in the figure can be configured on a single computer.

In the present embodiment, in the torque arm computing device 20, the input side plate thickness set value, the output side plate thickness set value, the deformation resistance estimated value and the work roll diameter which have been input are used, and the above (1) to (5) are used. The torque arm is calculated in advance according to the formula, and the calculated torque arm is stored in the memory 22. This torque arm is used as a fixed value for each unit of the material to be rolled.

Next, the rolling torque is calculated by the multiplier 26 from the product of the torque arm stored in the memory 22 and the rolling load measured by the load cell 24, and the obtained rolling torque is transferred from the speed controller 10 to the torque controller 12.
Is added to the torque command value output to.

The torque command value obtained by adding the rolling torque as described above is input to the torque controller 12, and the power supply control command value calculated based on the torque command value is input to the power supply device 24 for the electric motor. Device 24 to electric motor 1
By appropriately controlling the voltage applied to No. 6, it is possible to reliably prevent a decrease in the rotation speed of the work roll that occurs when the material to be rolled is caught in the roll.

As described above in detail, according to this embodiment,
Since the rolling torque is directly detected and the torque of the electric motor can be adjusted, it is possible to reliably prevent a decrease in the work roll rotation speed when the material to be rolled is caught in the rolling mill, and the tip of the material to be rolled. Therefore, it is possible to roll with a desired size. Further, since it is possible to adjust the torque according to the rolling torque even during rolling, there is an advantage that an extremely highly accurate speed command value can be obtained.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

Since the present invention synchronizes the material speeds of the upstream stand and the stand in which the rolled material is bitten when the material to be rolled is bitten, if there are two or more stands. It can be applied to speed control of all continuous rolling mills, whether cold or hot.

Further, in the above embodiment, the case where the speed feedback and the torque feedback are performed is shown, but the present invention is not limited to such feedback, but can be applied to the case where the control is performed based on the calculated value or the like.

Further, in the embodiment, the case where the torque arm is calculated in advance using the set value is shown, but the torque arm may be calculated using the actually measured value.

[0049]

As described above, according to the present invention, it is possible to reliably prevent the rotation speed of the work roll from decreasing when the material to be rolled is bitten by a simple calculation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a speed control device for a rolling mill according to an embodiment of the present invention.

FIG. 2 is an explanatory view schematically showing an example of a continuous rolling mill.

FIG. 3 is a block diagram showing a schematic configuration of a speed control device for a conventional rolling mill.

FIG. 4 is a block diagram showing a schematic configuration of another conventional speed control device for a rolling mill.

FIG. 5 is a diagram for explaining an example of a calculation method.

[Explanation of symbols]

 10 ... Speed controller 12 ... Torque controller 14 ... Electric motor power supply device 16 ... Electric motor 18 ... Torque disturbance estimator 20 ... Torque arm computing device 22 ... Memory 24 ... Load cell 26 ... Multiplier

Claims (3)

[Claims] 1. A rolling mill speed control method for controlling a rolling mill speed when rolling a material to be rolled by a continuous rolling mill in which a plurality of rolling mills are connected in series, and a rolling load measured during rolling, A speed control method for a rolling mill, characterized in that the speed of the rolling mill is controlled by the rolling torque obtained from the torque arm. 2. The speed control method for a rolling mill according to claim 1, wherein the torque arm is obtained using at least the thickness of the material to be rolled on the rolling mill entrance side and the rolling mill side, and the rolling load. . 3. A plurality of rolling mills, load measuring means for measuring a rolling load when a material to be rolled is rolled by the rolling mill, a speed controller for calculating a torque command value based on the speed command value, and a torque command. A speed control device for a rolling mill, comprising: a torque controller for calculating a power supply control command value for controlling a driving force of an electric motor based on a value; a torque arm calculating means; a torque arm calculated by the torque arm calculating means; And a rolling torque calculating means for obtaining a rolling torque on the basis of a load and a speed control device for a rolling mill.