JPS6050523B2 - Speed compensation device when rolled material is caught in a rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed compensating device for a rolled material caught in a rolling mill, which attempts to eliminate fluctuations in rolling roll speed when a rolled material is caught in the rolling mill.

FIGS. 1A and 1B are characteristic diagrams showing the state of "change in speed" when a load is suddenly applied to a rolling mill operating at a certain speed.

In the figures, the horizontal axis in both FIGS. 1A and 1B represents the passage of time, the vertical axis in FIG. 1A represents the speed, and the vertical axis in FIG. 1B (7) represents the current value.

1 is the change in speed, 2 is the change in current, 3 is the timing when the load is applied, 4 and 5 are the changes in speed current when the load value is different, and 6 is the original value of the changed speed. Represents the area on the drawing up to the point where it returns.

Generally, in a device such as a rolling mill, the rolling mill is rotated in advance at a constant speed, and the material to be rolled gets caught in that state, and a sudden load is applied.

It is generally known that when a rolling mill is under automatic speed control, the current and speed of the rolling mill drive motor change as shown in FIG. That is, when a load is applied at timing 3, speed 1 decreases. At the same time, current 2 acts to return rise rate 1 to its original set value. At this time, the area 6 expressed by the amount of decrease ΔN at speed 1 and its recovery time is used as a unit to express the control performance of the rolling mill,
Due to the nature of the rolling mill, it is said that the smaller the area 6, the better.
Also, the speed 1 and current 2 change depending on the load of the motor, and when the load is large, the current changes to 5 and the speed changes to 4, respectively. Fig. 2 is a block diagram showing a speed compensating device for biting of rolled material in a conventional rolling mill.
This is an example of something that reduces .

21 is a material to be rolled, 22 is a rolling roll that rolls the material to be rolled 21, 23 is a rolling pressure detector, 24 is an electric motor that drives the rolling roll, 25 is a rotational speed detector that detects the rotational speed of the electric motor 24, 26 27 is a speed reference signal, and 27 is a speed control device which feeds back the rotational speed of the electric motor 24 from the rotational speed detector 25 and controls the speed of the electric motor 24 to maintain the speed indicated by the speed reference signal.

28 is a speed control operational amplifier, 29 is a current control device, 3
0 is the current control signal derived from the operational amplifier 28, 31
3 is a proportional calculator, and 32 is a multiplication calculator.

A speed compensating device when a rolled material is bitten in a conventional rolling mill will be explained using FIG.

The basic idea behind this conventional method is that the rolled material 21 bites into the rolling rolls 22 and the speed 1 of the rolling mill decreases, so if an external force is applied to the electric motor 24 to counteract this load, We are of the view that a drop in speed of 1 will not occur. As soon as the material to be rolled 21 is bitten by the rolling roll 22, the rolling pressure detector 23 outputs an output. Next, this rolling pressure is calculated by a proportional calculator 31 in order to convert it into a current value of the rolling motor 24. On the other hand, a shunt field type DC motor is generally used as the motor 24, but three characteristics of the shunt field type DC motor are that the motor current required to produce the same output torque (not output capacity) is , a larger one is required at the field weakening speed than at the base rotation speed.

Therefore, in addition to the value calculated by the proportional calculator 31, the electric motor 2
When the actual speed signal of 4 is given and the operation is in the weakened 4 field region, the truly necessary current value is determined by the multiplier 32,
This current value is given to the current control device 29 as an external force signal necessary to cancel the load. The above is the operation of the conventional device, but this device requires a rolling pressure detector 23. A method of predicting and applying the rolling pressure using a rolling pressure detector can be considered, but the disadvantage is that the prediction must be made every time the rolling conditions change, and errors in the predicted value directly lead to deterioration of compensation accuracy. have. Another drawback is that a multiplication calculator 32 is required to compensate for the lack of torque at the time of field weakening using the actual speed of the rolling roll drive device, which complicates the control device accordingly. ) The present invention aims to provide a speed compensating device when a rolled material is caught in a rolling mill, which eliminates the above-mentioned drawbacks.

FIG. 3 is a block diagram showing an embodiment of a speed compensating device for biting of a rolled material in a rolling mill of the present invention, and FIG. 4 is a characteristic diagram for explaining FIG.

In Figure 3, 21, 22, 24, 25, 26, 27
is similar to that shown in FIG. 2, and its explanation will be omitted.

33 is a thyristor power supply device that supplies electric power to the motor 24 based on a command from the speed control device 27; 34 is a current detector that detects the load current flowing from the thyristor power supply device 33 to the motor 24; and 35 is a current detector 34. 36 is a switch, and 37 is a current upper limit setter, which functions so that the differential calculator 35 differentiates only changes in the load current within a certain range.
In Figure 4, A, B, and C take time on the horizontal axis, and Figure 4 A, C
? 1. The vertical axis shows the speed, and in FIG. 4B, the vertical axis shows the current value. In the figure, 11 is the speed change, 12 is the current change, 13 is the timing when the load is added, 14 is the speed change compensation value that should be added to reduce the speed change, and 15 is the speed compensated by the speed change compensation. 16 is the rate of change when the current 12 changes from timing 13, 17 and 18 are the area on the drawing until the speed that changed by one step returns to the original, 19 is the constant current value 11, and 20 is from timing 13. represents a certain period of time t1.

This invention will be explained using FIGS. 3 and 4.

First, when the material to be rolled 21 is bitten by the rolling roll 22, the speed changes as shown in 11 shown in FIG. 4A, but this is because the speed reference signal 30 is a constant value. Therefore, a speed increase curve 14 having the same shape as the speed decrease curve (corresponding to 11) drawn between time 13 when the load is applied and time 13 until the original speed is restored is controlled by the speed control device for a period of Tr. 27
, the velocity drop becomes 15 and the area 17 becomes 18.
(Ideally, the area 18 is zero). Next, as a method for determining the speed increase curve, that is, the speed compensation value 14, the current of the rolling roll drive device 24 (1
2) is used. By the way, the incomplete differential is functionally equivalent to a ``differential eleventh-order lag'' circuit.

Therefore, in order to obtain a correction signal (correction value) corresponding to the speed drop shown in FIG. 4A, if the rise of the current shown in FIG. 4B is imperfectly differentiated, the speed change compensation shown in FIG. 4C can be obtained. A value signal can be obtained. On the other hand, the value of the speed recovery time Tr after the load is applied is the impact recovery time and is usually expressed as WC: response angle frequency of the speed control system Rad/Sec.

This value has the same properties as a time constant and is determined only by WC, regardless of the magnitude of the load current.

This is one of the basic characteristics of linear control circuits. Therefore,
The time constant of the incomplete differentiation can be easily determined based on the response speed of the speed control system 27.

Next, it is generally known that the maximum value ΔN of the amount of speed reduction due to load jamming is proportional to the load current 12 of the rolling roll drive device 24. Also, the rate of change 16 of the current 12 when the load is caught
is proportional to the load current value, so the maximum amount ΔNC of the differential value obtained by incompletely differentiating the load current 12 at the timing 13 at the time of biting is the maximum value ΔN of the speed drop amount.
It is clear that it is proportional to . As an example of embodying the above principle, the current value from the current detector 34 is imperfectly differentiated by the differential calculator 35 in FIG. 3, and the speed change compensation value signal shown in FIG. 14 and this signal is added to the speed reference value 26 of the speed control device 27 in order to compensate for the speed drop curve 11 mentioned above.

Note that the method according to the present invention is almost equivalent to increasing the responsiveness of the speed control system 27, and keeping the differential circuit 35 active all the time means leaving the response high during steady rolling. Then, a certain time t1 from the time of load biting 13
(corresponding to 20 and slightly longer than Tr) After that, the differential calculator 35 can be turned off by a switch 36.
Further, as explained above, the speed compensation value 14 is a differential value of the load current 12, but the load current 12 may vary slightly depending on various rolling conditions. Therefore, if the load current 12 is differentiated as it is, the speed compensation value signal 14 will also vary accordingly.
5, the constant current value 19 (1
1), and the load current is 1.
Even if 2 fluctuates to a value of 11 or more, it does not matter at all. Furthermore, the speed compensation value curve 14 has a function equivalent to the signal that cancels the external force explained in FIG. 2, and the load current 1
A similar effect can be expected even if the differential signal of 2 is added to the current control system instead of the speed control system. As described above, in the present invention, the speed return time Tr is determined by the response speed of the speed control system, and the maximum value ΔN of the speed decrease is determined by the rate of change of current when the load is caught. This eliminates the need for a rolling pressure detector or its prediction and conversion from rolling pressure in the field weakening region to a compensation current value, which were required in the conventional method, resulting in a simpler configuration. , it is possible to compensate for the speed drop when the rolled material is bitten.

[Brief explanation of drawings]

Fig. 1 is a characteristic diagram of speed and load current, Fig. 2 is a block diagram showing a speed compensating device when a rolled material is bitten in a conventional rolling mill, and Fig. 3 is a diagram showing a speed compensation device for a rolled material in a conventional rolling mill. A block diagram showing an example of a speed compensator during material biting,
FIG. 4 is a characteristic diagram for explaining FIG. 3. In the figure, 21 is a rolled material, 22 is a rolling roll, 23 is a rolling pressure detector, 24 is an electric motor, 25 is a rotation speed detector, 2
6 is a speed reference signal, 27 is a speed control device, 28 is an operational amplifier for speed control, 29 is a current control device, 30 is a current control signal, 31 is a proportional calculator, 32 is a multiplication calculator, 34 is a current detection 35 is a differential calculator, 36 is a switch, 37
has an upper limit setter.

Claims (1)

[Claims] 1. A speed detector that detects the speed of an electric motor that drives a rolling roll that rolls a material to be rolled, and a speed signal detected by this speed detector and a speed reference signal that are compared with the speed reference signal. a speed control device that controls the speed of the electric motor so that it matches the speed reference signal and the compared value becomes zero; a current detector that detects the current of the electric motor; A compensation signal for canceling the speed change amount of the motor when the motor is jammed is derived by incompletely differentiating the current value from the current detector, and is applied to a speed control device of the motor or a current control device of the motor. A speed compensation device for biting rolled material in a rolling mill, which is equipped with a differential calculator for input. 2. A speed compensator in a rolling mill according to claim 1, wherein the differential calculator is configured to perform incomplete differentiation only within a certain range of current changes of the electric motor. 3. The rolling mill according to claim 1 or 2, wherein the compensation signal is derived from the time when the material to be rolled is bitten by the rolling roll until the time when the speed change of the electric motor stops. A speed compensation device when rolled material is bitten.