JPH0422643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a speed control device for a rolling mill in rolling equipment for steel, etc., when rolling is performed with a speed difference between the upper and lower rolls of the rolling mill.

[Technical background of the invention and its problems]

Conventionally, the upper and lower rolls of a rolling mill were controlled to rotate at the same speed, but in recent years, methods have been introduced in which the upper and lower rolls are rolled at different speeds for purposes such as improving the shape of the plate and reducing rolling power. (hereinafter referred to as different circumferential speed rolling) has been used. Generally, in different circumferential speed rolling, the rolling torque of the high-speed rolls is large, and the rolling torque of the low-speed rolls is smaller than that of the high-speed rolls, resulting in an imbalance between the rolling torques of the upper and lower rolls. This unbalance of rolling torque becomes larger as the speed difference between the upper and lower rolling rolls increases, and the load applied to the high-speed rolls increases.
In different circumferential speed rolling, the total rolling torque is smaller than in normal rolling where there is no speed difference between the upper and lower rolling rolls, but when the speed difference between the upper and lower rolling rolls exceeds a certain value, the rolling torque of the high-speed rolls becomes normal. It becomes larger than the rolling torque during rolling. That is, if the field current of the high-speed roll driving motor is kept constant, the armature current will be larger than the armature current during normal rolling.
However, there is a limit to the armature current that can flow through the motor, and the motor control device limits the armature current so that it does not exceed this limit value (hereinafter referred to as current limit value).

As described above, if the capacity of the motor for driving the upper and lower rolls is selected from the rolling torque during normal rolling, the speed difference between the upper and lower rolls will exceed a certain value during rolling at different circumferential speeds, and the armature of the motor for driving the high-speed rolls will As a result of the current being limited by the current limit value, not only the rolling torque of the high-speed rolls is insufficient, but also the speed of the high-speed rolls decreases, resulting in unsatisfactory rolling. In order to avoid this, selecting a large capacity of the electric motor for driving the upper and lower rolling rolls in consideration of different circumferential speed rolling leads to an increase in the price of the electric motor and the motor control device.

[Purpose of the invention]

An object of the present invention is to provide a speed control device for a rolling mill that performs stable different circumferential speed rolling even when the armature current of a high-speed roll reaches a current limit value.

[Summary of the invention]

The present invention includes a speed control device that controls the circumferential speed of the upper roll and the lower roll via an electric motor,
A speed control device for a rolling mill that performs different circumferential speed rolling, comprising a speed reference calculation means for giving a speed difference between the circumferential speeds of the upper roll and the lower roll by a constant circumferential speed command and different circumferential speed rate commands for the upper roll and the lower roll, When the current of the electric motor that drives the upper roll or the lower roll exceeds a predetermined current, a speed setting correction means is provided to reduce the constant circumferential speed command. If the armature current of the drive motor for the upper and lower rolling rolls exceeds a predetermined current during rolling, the uniform circumferential speed command is reduced to correct the upper and lower rolling roll speeds so that the current limit value is not exceeded, and rolling at different circumferential speeds is continued. This is a rolling mill speed control device that makes it possible to

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a system diagram showing one embodiment of the present invention. The upper roll 1 and the lower roll 2 are driven by an upper roll drive electric motor 3 and a lower roll drive electric motor 4, respectively, and the upper/lower roll drive electric motors 3 and 4 are driven by an upper roll speed control device 5 and a lower roll speed control device, respectively. It is controlled by a roll speed control device 6.
The upper/lower roll speed control devices 5 and 6 control the drive motors 3 and 4 in accordance with a speed reference signal from a speed reference calculation circuit 7. The speed standard calculation circuit 7 determines the speed standard for the upper and lower rolls from the uniform peripheral speed rolling speed which is the output of the speed setting calculation circuit 8, and the upper roll different peripheral speed rate and the lower roll different peripheral speed rate which are the outputs of the different peripheral speed rate setting circuit 9. calculate. The speed setting calculation circuit 8 calculates the constant peripheral speed rolling speed from the constant peripheral speed speed setting value that is the output of the constant peripheral speed speed setting circuit 10 and the speed correction factor that is the output of the speed setting correction circuit 11. The speed setting correction circuit 11 receives as input the armature currents of the upper/lower roll drive motors 3, 4 from the upper/lower roll speed control devices 5, 6, and calculates a speed correction factor.

FIG. 2 is a detailed diagram of the speed setting correction circuit 11. The current control detection circuits 21 and 22 monitor the armature current of the upper/lower roll drive motors 3 and 4 from the upper/lower roll speed control devices 5 and 6, and detect that the current reaches the current limit value. . The speed correction factor calculation circuit 23 multiplies the current limit detection signals from the current limit detection circuits 21 and 22 by the speed correction factor set in the speed correction factor setting circuit 24 each time the upper roll or the lower roll is subject to current limit. Calculate the final speed correction factor. For example, if the setting value of the speed correction factor setting circuit 24 is K (0<K<1) and the current limit is applied n times, the output of the speed correction factor calculation circuit 23 is
K ⁿ .

FIG. 3 is a diagram illustrating the function of the speed setting calculation circuit 8, in which a multiplier 31 applies speed correction to the constant circumferential speed setting speed a, which is the output of the constant circumferential speed speed setting circuit 10, and the output of the speed setting correction circuit 11. Calculate the constant circumferential speed rolling speed by multiplying by the ratio K ⁿ .

FIG. 4 is a detailed diagram of the speed reference calculation circuit 7.
The multiplier 41 multiplies the constant circumferential speed rolling speed ^aKn , which is the output of the speed setting calculation circuit 8, and the top roll different circumferential speed rate _h1 , which is the output of the different circumferential speed rate setting circuit 9, to calculate the upper roll speed reference signal. , the multiplier 42 calculates the lower roll speed reference signal by multiplying the uniform peripheral speed rolling speed aK ⁿ , which is the output of the speed setting calculation circuit 8, and the lower roll different peripheral speed rate _h2 , which is the output of the different peripheral speed rate setting circuit 9. do. 43,
44 is a rate circuit for avoiding sudden changes in speed.

FIG. 5 shows changes in speed and armature current of the upper/lower roll driving electric motors 3, 4 during rolling at different circumferential speeds when the upper roll is a high speed roll and the lower roll is a low speed roll. At time _t1 , the current limit detection circuit 21 in FIG. 2 detects that the armature current of the upper roll drive motor 3 reaches the current limit value A, and the speed correction factor calculation circuit 23 changes the speed correction factor to the speed. Output to the setting calculation circuit 8. As shown in FIG. 3, this speed correction factor is multiplied by the constant circumferential speed set speed which is the output of the constant circumferential speed setting circuit 10 by a multiplier 31, and the constant circumferential speed set speed is corrected. In this way, after time t ₁ in FIG. 5, the electric motors 3 and 4 for driving the upper and lower rolls
When the different circumferential speeds of the upper and lower rolls are corrected and the speeds of the upper and lower rolls are reduced, the speed difference between the upper and lower rolls becomes relatively smaller. As a result, the rolling torque decreases and the armature current of the upper roll driving motor becomes smaller than the current limit value.
In FIG. 5, B indicates the upper roll current, C the lower roll current, D the constant circumferential speed rolling speed, E the upper roll speed, and F the lower roll speed.

[Other Examples]

In this embodiment, when calculating the speed correction factor, the speed correction factor set in the speed correction factor setting circuit 24 is multiplied every time the upper roll or the lower roll is subject to current restriction. The speed correction factor set by the speed correction factor setting circuit 24 may be reduced every time the current is limited. For example, if the setting value of the speed correction factor setting circuit 24 is C (0<C>1) and the current is limited m times, the output of the speed correction factor calculation circuit 23 will be 1-mC.

In addition, in this embodiment, it is detected that the upper roll or the lower roll reaches the current limit value, but this current limit value can be set to the motor rated current value, motor overload rated current value, or the effective value RMS of the motor. (Root
Of course, it is also possible to set the current value to 1 (Mean Scare) = 1 current value.

Further, in this embodiment, the constant circumferential speed rolling speed is corrected in the form of a speed correction rate, but it goes without saying that it may be corrected in an absolute amount called a speed correction amount.

In addition, in this example, the case where the rolling mill has one stand has been explained, but in the case of a tandem rolling mill consisting of multiple consecutive stands, speed correction is made with respect to the speed standard that is the master of each speed standard of the multiple stands. It goes without saying that all you have to do is implement the following.

〔Effect of the invention〕

As detailed above, according to the present invention, even when the armature current of the drive motor of the high-speed roll reaches the current limit during rolling at different circumferential speeds, this is detected and the different circumferential speed ratio of the upper and lower rolls is changed. By reducing the speed of the upper and lower rolls without changing the speed of the upper and lower rolls, the speed difference between the upper and lower rolls becomes relatively smaller, and as a result, the rolling torque decreases.
It becomes possible to suppress the current of the high-speed rolls within the current limit value and perform stable rolling at different circumferential speeds.

[Brief explanation of drawings]

Figure 1 is a system diagram showing one embodiment of the present invention, Figure 2 is a system diagram showing an embodiment of the present invention.
Figure 3 is a detailed diagram of the speed setting correction circuit of the present invention, Figure 3 is an explanatory diagram of the speed setting calculation circuit of the invention, Figure 4 is a detailed diagram of the speed reference calculation circuit of the invention, and Figure 5 is a diagram of different peripheral speeds. FIG. 3 is an explanatory diagram showing changes in speed and current of the upper/lower rolling roll drive motor when the present invention is applied during rolling. 1... Upper rolling roll, 2... Lower rolling roll, 3
...Electric motor for driving the upper roll, 4... Electric motor for driving the lower roll, 5... Upper roll speed control device, 6...
Lower roll speed control device, 7...Speed reference calculation circuit, 8...Speed setting calculation circuit, 9...Different circumferential speed rate setting circuit, 10...Constant circumferential speed speed setting circuit, 11...
Speed setting correction circuit, 21, 22... Current limit detection circuit, 23... Speed correction factor calculation circuit, 24... Speed correction factor setting circuit, 31, 41, 42... Multiplier, 43, 44... Rate circuit.

Claims (1)

[Claims] 1 Equipped with a speed control device that controls the circumferential speed of the upper roll and lower roll via an electric motor, and uses a constant circumferential speed command and a different circumferential speed rate command for the upper roll and lower roll to create a speed difference between the circumferential speeds of the upper roll and the lower roll. In a speed control device for a rolling mill that performs different circumferential speed rolling, the speed control device is equipped with a speed reference calculation means that gives a speed reference calculation means that reduces the constant circumferential speed command when the current of the electric motor that drives the upper roll or the lower roll exceeds a predetermined current. A speed control device for a rolling mill, characterized in that a setting correction means is provided.