JPS5840437B2 - Atsuenkino sokudoseigiyosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for a rolling mill, and more particularly to a speed control device for a rolling mill that compensates for a speed drop when a load is applied, that is, an impact drop.

Generally, a speed control device for a rolling mill is constructed as shown in FIG.

In FIG. 1, 1 is a rolling roll, 2 is a rolled material, 3 is a motor for rotating the rolling roll, 4 is a speed detector that detects the speed of the motor 3, and 5 is a device that calculates the deviation between the set speed ωp and the actual speed. an adder; 6 is a speed control unit that outputs a current command value whose deviation should be made zero according to the output of the adder 5; 7 is an adder that calculates the deviation between the speed control unit 6 and the output of the current detector 11; 8 is a current control unit that receives the output of the adder 7 and outputs a voltage command value to make the deviation zero; 9 is a firing angle control unit that controls the firing angle of the Cyrisk device 10 based on the output of the current control unit 8; , 10 is a cyrisk device for applying voltage to the electric motor 3, and 11 is a current detector.

In this example, the speed control is performed by first applying a set speed ωp to start the electric motor 3, and performing negative feedback control of the speed so that the difference between the output signal from the speed detector 4 and the set speed ωp becomes zero. This is done by taking in the output signal of the current detector 11 and performing negative feedback control of the current so that the difference between it and the current command becomes zero.

This control system is shown in a block diagram as shown in FIG.

In FIG. 2, 5' corresponds to adder 5 in FIG.
'corresponds to the speed control section 6 in FIG. 1, 7' corresponds to the adder 7 in FIG. 1, and 8' corresponds to the current control section 8 in FIG.

9' corresponds to the gain of the firing angle control section 9 and the thyrisk device 10 in FIG.

Further, 3' corresponds to the electric motor 3 in FIG.

The symbols in FIG. 2 are as follows.

Kn: Proportional gain of speed control unit Tn: Integral time of integral control in speed control unit Explaining the control device of FIG. 1 with the block diagram of FIG. 2, when the load τ□ applied to the motor changes, the motor speed ω changes, this speed change is detected by 5' and the current pattern is detected by 6'.
This current pattern I is compared with the detected value ■ of the actual current flowing through the motor at 7', and based on the deviation, the current is controlled at 8' and 9' so that the speed ω becomes ωp. .

For example, in hot rolling, when a rolled material is squeezed into a rolling mill, a rolling load is applied to the motor in a stepwise manner, causing the motor speed to drop by one step, and then gradually recover due to the speed control effect.

FIG. 3 shows this state.

This kind of speed drop is usually called an impact drop.

Other possible causes of impact drop during rolling include eccentricity of the backup roll, changes in the thickness of the rolled material, and changes in temperature and hardness at skid marks and the like.

The adverse effects caused by impact drops are particularly noticeable in multi-high rolling mills that include a plurality of rolling stands.

That is, the impact drop generates tension (or compressive force) between each stand, which deteriorates the thickness and shape of the rolled material.

For hot rolling, etc., where little tension can be applied to prevent sheet breakage, use the Impact Dron! ° is the biggest problem.

In order to compensate for this impact drop, it is possible to consider a method of increasing the speed in advance, but this method only compensates for the narrowing of the rolled material and cannot prevent impact drops during rolling.

Further, when narrowing the rolled material, mechanical shock is large, and it is not preferable to increase the rolling speed in advance because it goes against this.

The present invention was made in view of the above problems, and an object of the present invention is to provide a speed control device for a rolling mill that does not change the speed of an electric motor even if the rolling load changes.

In the present invention, the load applied to the electric motor is proportional to the rolling torque,
Moreover, based on the rolling theory that the rolling torque is proportional to the rolling load, the rolling load is detected and converted into the current value required to rotate the motor, and the current value is used as a command value to control the motor current and speed. The present invention is characterized in that the control circuit for changing the current command value is adapted to correct the current command value according to the deviation between the predetermined speed value and the actual speed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to explain the present invention in more detail, a detailed description of the present invention will be provided.

FIG. 4 shows an embodiment of the present invention, and FIG. 5 is a block diagram thereof.

In Fig. 4, 1 to 6 and 8 to 11 are the same devices as in Fig. 1, 12 is a load cell that detects the rolling load, and 13 is a current command value that takes in the output of the load cell 12 and becomes a load control signal. This is a load control section that outputs .

Gain K in the load control section 13. is given by the following equation.

Further, the load control unit 13 provides the gain KP, and also compensates for the delay when the actual load of the motor is transmitted through the shaft between the roll and the motor and is applied using the -th order lead/lag element.

This -next lead/lag element TP□ is adjusted so that the phases of both the output torque of the electric motor and the rolling torque match at the roll end of the shaft.

A function generator 14 inputs the speed of the electric motor 3 from the speed detector 4, and outputs 1 when the actual speed ω is less than the base speed ω3, and outputs the ratio ω/ω8 when the actual speed ω is equal to or higher than the base speed.

15 indicates a multiplier.

The function generator 14 and multiplier 15 are provided to compensate for the induced voltage ζφ changing in inverse proportion to the speed above the base speed.

This is not necessary in electric motors where ζψ does not change.

Reference numeral 16 denotes an adder that adds the output of the multiplier 15, the output of the speed control section 6, and the negative feedback amount of the current detector 11.

Next, the operation of this embodiment will be explained. Until rolling is started, the rolling load P input from the load cell 12 is zero, and the output of the load control section 11 is zero.

In this state, the speed ω of the electric motor 3 is controlled by the speed controller 6
The speed is maintained at a predetermined speed ω2 by the operation.

Next, when rolling is started, the load control section 13 is operated by the load detection value P from the load cell 12, and the multiplier 15
The current command value is multiplied by the output of the function generator 14 to perform speed correction, and a current command value is output to the adder 16.

Since the output of the newly added multiplier 15 disrupts the balance of automatic current control, in other words, the absolute value of the output of the current detector 11 and the sum of the outputs of the speed control section 6 and the multiplier 15 becomes equal in the adder 16. Therefore, the difference is given to the current control unit 8 as the output of the adder 16.

The current control unit 8 outputs a voltage command value to the firing angle control unit 9 based on the given difference, and the firing angle control unit 9 controls the firing angle of the thyrisk device 10 based on this voltage command value.

As a result, a current that balances the applied load τ flows through the motor 3.

What is important here is the time it takes for the actual load τ to be actually applied from the rolling roll 1 to the electric motor 3 via the shaft, and the time it takes for the rolling load detected by the load cell 12 to be applied to the control system and to the electric motor 3. The timing must match the time taken to cause the current change.

In the case of the present invention, since the rolling load is detected as a means for detecting the load, it is possible to match the timing.

In other words, it usually takes 100 to 200 m5 from when the rolled material is bitten by the rolling roll until the load τ□ is transmitted to the electric motor 3 via the shaft. Since the time it takes to detect τ is 50 to 100 m5, the timing of operating the sidecar system according to the load and changing the current of the electric motor 3 can be made to coincide with the timing of applying the actual load τ to the electric motor 3.

For this timing coincidence, the load control section 13 is provided with a primary lead/lag circuit.

In this way, it is possible to prevent impact drop of the electric motor 3 when the rolled material is caught.

Further, even during subsequent rolling, if the rolling load changes, a proportional rolling load P is detected and the current of the electric motor 3 is controlled, so that no impact drop occurs at all times.

When changing the rolling speed for acceleration, deceleration, or tension control, the input ωp (speed command value) of the speed control section 6 may be changed.

By changing this ωp, an acceleration/deceleration current 1 is applied to the current control section 8, whereby the electric motor 3 is operated at the speed ωp.

A block diagram of the embodiment shown in FIG. 4 is shown in FIG.

In this figure, the same numbers and symbols as in FIG. 2 indicate the same contents.

13' corresponds to 13 in FIG. 4, and is expressed as the product of the -th lead/lag element 1+T P2S and the load conversion gain, 1+T,S.

14' corresponds to 14 in FIG. 4, and represents a function generator that outputs 1 up to a predetermined speed and outputs a signal proportional to ω/ω8 above that.

15' corresponds to 15 in FIG. 4, and speed correction is performed using this.

τ1 in the figure represents an actual load, which corresponds to the load applied to the electric motor 3.

Although the input from the actual load τ□ to the load control unit 13' is shown by a broken line, this only indicates that the load is detected by the load P.

As explained in detail above, the present invention detects the load by detecting the rolling load with a quick response, and when the actual load is applied to the motor, a current corresponding to the actual load flows, so that impact drops can be almost completely eliminated. can.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of a conventional speed control device for a rolling mill, Fig. 2 is a block diagram of the device shown in Fig. 1, Fig. 3 is a diagram showing an impact drop, and Fig. 4 is a diagram of the present invention. FIG. 5 is a block diagram of the embodiment of FIG. 4, showing an embodiment of the invention. Explanation of symbols, 1...Roll roll, 2...
・Rolled material, 3...Electric motor, 4...Speed detector, 5...Adder, 6...Speed control section, 7... ... Adder, 8 ... Current control section, 9 ... Firing angle control section, 10 ... Cyrisk device, 11 ... Current detector, 12...
...Load cell, 13...Load control section, 1
4...function generator, 15...multiplier,
16...Adder.

Claims (1)

[Claims] 1. An electric motor for rotating rolling rolls, a speed detector that detects the speed of the electric motor, a speed control section that outputs a current command based on the deviation between a speed setting value and the output of the speed detector, and a current that flows to the electric motor. a current detector that detects current; a current control section that outputs a voltage command based on a deviation between the current command and the output of the current detector; and a firing angle of a cyrisk device that drives the electric motor based on the voltage command. In a speed control device for a rolling mill, the speed control device includes a rolling load detector that detects the rolling load applied to the rolling rolls, and a load control signal that takes in the output of the rolling load detector and generates a load control signal according to the load. and a function generator that takes the output of the speed detector and outputs 1 when the actual speed is below the scheduled base speed, and outputs the value of the ratio of the actual speed to the base speed when the actual speed is above the base speed. and a multiplier that provides a multiplication value of the output of the function generator and the load control signal as a correction signal for the current command.