JPH0551370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the drive of a speed detection roll in a rolling mill.

[Prior Art] Conventionally, plate speed detection in the rolling process is used for mass flow AGC, and for this purpose, a plate speed detection roll (deflector roll) is brought into contact with a strip to detect the speed. The deflector roll in this case is mostly used in an idle state, and when the frictional force between the plate and the roll decreases, especially when the front and rear tension is low,
Slip occurs when the coefficient of friction between the plate and the roll decreases, which has an adverse effect on mass flow AGC, etc. The slip tendency is particularly noticeable during line acceleration and deceleration.

As a countermeasure, there is a method in which the deflector roll is driven by a motor, and the motor is controlled by current control or a speed control system with drooping (drooping characteristics).

[Problems to be Solved by the Invention] However, the above method has the following problems.

(1) Problems with the current control method As shown in Figure 8, when driving the motor, the target current value is the amount given as a function of the mechanical loss and the acceleration/deceleration compensation (the inertia of the deflector roll during acceleration/deceleration). moment compensation) is given. However, mechanical loss tends to fluctuate due to various causes, and when the current target value is given as a function of the initial setting value, the frictional force between the strip and the deflector roll decreases and slip occurs, and the deflector roll accelerates ( Current target value>
actual mechanical loss) or deceleration (current target value <
Actual mechanical loss) occurs, and the speed limit circuit operates, causing the speed of the deflector roll to increase to the line speed + speed limit bias. For example, the speed limit bias is set to 10 to 15% of the maximum speed, so on the maximum speed line of 1000 mpm,
If a slip occurs while driving at 200mpm,
Increases to 200 + 1000 x (10-15%) = 300-350mpm. For this reason, it is not possible to accurately measure the stripping speed, and the error is also very large.

(2) Problems with the drooping + speed control method When driving the deflector roll, there is no need to perform external work such as conveying the strip, so the motor capacity can be small. Therefore, in order to prevent the load from tripping due to load fluctuations on the load side, as shown in Figure 9,
It is necessary to add drooping. However, as shown in Figure 10, when the read rate is zero, no current flows in the steady state (total target speed totalv _rer = feedback speed
v _FB ), so the movement is the same as a conventional idle roll and has no effect on slips.

Also, since acceleration current flows during acceleration/deceleration, total target speed totalv _ref = target speed v _ref −I _FB ×
a%, a total target speed lower than the strip speed is given, and it becomes easy to slip.

As a countermeasure for this, it is conceivable to multiply the deflector roll alone by a lead rate to compensate for its own mechanical loss, as shown in FIG. 1B.
The lead rate biases the strip speed to compensate for the cancellation caused by drooping. However, since the read rate is preset and the drooping amount changes depending on the load condition, it is impossible to use it without both. This is because their personalities are completely different. If the lead ratio is set to an appropriate value, the deflector roll will allow its own mechanical loss compensation and acceleration/deceleration current to flow, making it possible to create a control system that is resistant to slips.

However, in the past, the lead rate was set to zero or constant, so when a change in mechanical loss occurs, the total target speed does not match the strip speed, making slips more likely to occur.

An object of the present invention is to provide a speed detection roll control device that can accurately detect the strip speed when controlling the strip speed based on the drive rotation speed of the drive motor that drives the strip speed.

[Means for Solving the Problems] The present invention for solving the above problems includes providing a deflector roll that comes into contact with the strip during rolling to detect its moving speed, and also adjusting the deflector roll to match the moving speed of the strip. A device configured to be rotationally driven by a drive motor, comprising: a speed detector for detecting the current driving rotational speed of the drive motor; a current detector for detecting a current value applied to the drive motor; A lead rate correction table that determines a lead rate based on a speed signal, and a drooping applicator that determines a drooping amount based on the current value; and a lead rate corrected by the lead rate correction table. The present invention is characterized in that the target speed is corrected with the amount of drooping from the drooping applicator, and the drive motor is controlled based on the total target speed after this correction.

[Function] In the present invention, since the lead rate is taken into account when controlling the speed, a control system that is resistant to slips can be constructed, and the lead rate is changed based on the current drive rotational speed of the drive motor. An appropriate rotational speed can be given to the speed detection roll while preventing the occurrence of slips during acceleration and deceleration.

[Specific Structure of the Invention] The present invention will be explained in more detail below based on the drawings.

FIG. 2 is a schematic diagram of reverse rolling. The strip 2 unwound from the input reel 1 is sent to a rolling mill 5 via a speed detection roll 3 on the back tension side and a plate thickness detection device 4 using X-rays or the like on the back tension side. After the speed is detected by the plate thickness detecting device 6 on the side and the speed detecting roll 7 on the forward tension side, the sheet is wound onto the exit reel 8. In the present invention, the deflector rolls 3 and 7 for detecting both speeds are
The drive is controlled as follows.

Generally, the back tension side is always in a high tension state (usually 13 to 25 tons), so the frictional force between the deflector roll and the strip is very large, making it difficult to slip. Additionally, speed control and current control have significantly different responsiveness, with current control being faster.
For example, speed control is 10 to 30 rad/sec, and current control is 70 to 300 rad/sec. Also, on the back tension side, due to AGC correction, the reverse rate changes more than the forward rate (lead rate), resulting in severe speed fluctuations. As in the embodiment, if the drive of the deflector roll on the back tension side is controlled by current control, the response is quick and stable control without slip is possible.

On the other hand, on the forward tension side, winding is performed at a low tension due to limitations on the proper winding tension of the coil, so slipping is likely to occur. Furthermore, on the forward tension side, fluctuations in the read rate are small and the speed is stable. Therefore, if the drive of the forward tension side deflector roll is controlled based on the rotational speed of the deflector roll, which has a control system that is resistant to slips, the deflector roll can be controlled stably and without slipping.

FIG. 1A is a diagram showing the control of the deflector roll 3 on the back tension side. First, when a target speed is given, the mechanical loss vs.
In the speed mechanical loss conversion table 10, the first
A target current is calculated in response to the mechanical loss correction signal from the slip detector 30 shown in Figure B, and the acceleration/deceleration compensation signal is added to this to calculate the total target current. Next, the target current signal is inputted to the motor MB via the current control device 11 to drive the deflector roll 3 on the back tension side. A current detector 12 is provided between the current control device 11 and the motor MB, and the current is controlled while feeding back the current current to the total target current signal.

On the other hand, the drive control of the speed detection roll on the forward tension side will be explained with reference to FIG. This and a drooping signal, which will be described later, are added to the target speed value to obtain the total target speed. This total target speed signal is then subtracted by a speed feedback signal obtained from the rotary generator 21 that detects the rotational drive speed of the drive motor MF that drives the deflector roll 7, and then inputted into the speed control device 22 to obtain the target speed. After determining the current value, the current feedback signal from the current detector 23 is subtracted, and then the current control device 24 drives the motor MF to drive the deflector roll 7 on the forward tension side. The signal from the current detector 23 feeds back to the target current value, and a drooping setting device 25 applies drooping to the total target speed value. The speed signal from the forward tension side rotary generator 21 not only feeds back to the total target speed value but also feeds back to the lead rate correction table 20 to calculate the lead rate.

By the way, in the past, the lead rate was assumed to be constant. If the lead rate is constant, if a change in mechanical loss occurs, the total target speed will no longer match the strip speed, making it easy to slip. Therefore, in the present invention, the lead rate is corrected in accordance with a change in mechanical loss based on a change in drive rotational speed of the deflector roll.

For this purpose, a lead rate correction signal is input into the lead rate correction table 20. This lead rate correction signal is obtained based on the drive speed from the rotary generator 13 attached to the drive motor MB, the drive speed from the rotary generator 21, each plate thickness signal from the plate thickness detectors 4 and 6, etc. This is given by a slip detector 30 that calculates the amount of slip, mechanical loss, and correction amount of lead rate. This slip detector 30
The mechanical loss correction signal calculated by is given to the mechanical loss conversion table 10 as a mechanical loss correction signal.

In a speed control system, if the lead rate is optimal, the control system will be extremely resistant to slips.
Improper use may cause slips. In the present invention, as described above, the lead rate is given after being corrected as a function of the current drive rotational speed.

Originally, it is optimal for the lead rate to correct the target speed reduction due to drooping (drooping a% x current for mechanical loss) which is affected by the current for mechanical loss of the deflector roll. However, mechanical loss changes depending on line speed and is not constant.

Therefore, in the present invention, the mechanical loss is corrected based on the line speed as shown in FIG. 3, and the lead rate is changed based on this. The optimal lead rate is mechanical loss x% x a (drooping)%
is given by

Furthermore, if the lead rate is kept constant as in the past, the mechanical loss current required in the lead rate region smaller than the optimum lead rate does not flow, so the strip moves in the direction of being pulled by the strip and slips in the direction of delay. It's easy to do. Further, in a read rate region larger than the optimum read rate, a current higher than the mechanical loss current flows, and the strip tends to slip in the advancing direction with respect to the strip speed. By such lead rate correction, only the mechanical loss of the deflector roll flows, and a control system that is always resistant to slipping can be achieved.

Although a control system that is sufficiently strong against slips has been constructed in this way, it does not have the ability to compensate for changes in mechanical loss over time.

Therefore, it is desirable to detect slips and correct mechanical losses and lead rates based on mass flow AGC as described below.

In Fig. 2, when the inlet speed of the rolling mill is V _E , the outlet speed is V _D , and the inlet plate thickness is H _X , the outlet mass flow AGC plate thickness h _M is h _M = V _E ×H _X /V _D is given by This mass flow AGC plate thickness h _M is the plate thickness just below the mill reduction, so by tracking this plate thickness, as shown in Figure 4, the difference _Δε from the outlet plate thickness h
is calculated, and a slip can be detected when this Δε exceeds a certain level.

If a slip is detected in this way,
As shown in Fig. 5, the output Δy after giving a dead band to Δε is multiplied by the gain, and the mechanical loss conversion table 1 of the deflector roll on the back tension side is calculated.
Correction is added to the lead rate correction table 20 for the deflector rolls on the zero and forward tension sides. In this case, the correction gain is set to a low gain because the deflector roll on the back tension side is less likely to slip, and the correction gain is set to a high gain because the deflector roll on the forward tension side is more likely to slip. It is preferable to do so. In addition, as shown in the figure, in order to prevent sudden changes in the table value before and after the speed, it is desirable to make corrections by linear approximation to the table values at 10% points before and after the slip occurrence speed.

〔Example〕

Next, an example will be shown, and the effects of using the device of the present invention will be clarified by comparison with a conventional device.

In other words, in obtaining low carbon steel cold rolled steel sheets,
A 2.3 mm plate was reverse rolled to a width of 0.5 mm x 1005 mm. The number of passes is 5. The deflector roll used had a diameter of 313 mm and a length of 1200 mm.

The case of the present invention is shown in FIG. 6, and the conventional example is shown in FIG. It can be seen that the exit plate thickness accuracy in the final pass has been improved.

〔Effect of the invention〕

As described above, according to the present invention, when controlling the drive motor that drives the deflector roll by speed control, a lead rate is given and the lead rate is adjusted to a mechanical loss corrected based on the speed change of the deflector roll. Since the voltage is applied while being corrected, it is possible to perform control that is extremely resistant to slips.

[Brief explanation of drawings]

Fig. 1A is an explanatory diagram of the current control system of the drive motor of the speed detection roll on the back tension side according to the present invention, and Fig. 1B is an explanatory diagram of the speed control system of the drive motor of the speed detection roll on the forward tension side. ,
Figure 2 is a schematic diagram of the reverse rolling equipment, Figure 3 is a diagram showing the relationship between line speed and lead rate, Figure 4 is a diagram showing the slip detection mechanism, Figure 5 is a diagram showing the lead rate correction method, and Figure 5 is a diagram showing the lead rate correction method. Fig. 6 is a diagram showing the effect of the present invention device, Fig. 7 is a diagram showing the effect of the conventional device, Fig. 8 is a conventional current control diagram, Fig. 9 is a diagram showing conventional speed control, and Fig. 10 is a diagram showing the conventional speed control. FIG. 3 is a relationship diagram between stripping speed, read rate, and current. 1... Entrance reel, 2... Strip, 3...
Back tension side speed detection roll, 5... Rolling roll, 7... Forward tension side speed detection roll, 8... Output side reel.

Claims (1)

[Scope of Claims] 1. A device that is provided with a deflector roll that comes into contact with the strip during rolling to detect its moving speed, and that the deflector roll is rotationally driven by a drive motor in accordance with the moving speed of the strip, a speed detector that detects the current driving rotational speed of the drive motor; a current detector that detects a current value applied to the drive motor; and a lead rate correction table that determines a lead rate based on the speed signal from the speed detector. and a drooping applicator that determines a drooping amount based on the current value, and a target speed is determined by the lead rate corrected by the lead rate correction table and the drooping amount from the drooping applicator. 1. A speed detection roll control device for a rolling strip, characterized in that the drive motor is controlled based on the corrected total target speed.