JPH01249208A - Method for drive control for rolling roll - Google Patents

Abstract

PURPOSE:To prevent generation of slips by detecting a slip based on a difference between peripheral speeds of upper and lower rolls and changing load balance control into speed balance control to equalize both peripheral speeds of the upper and lower rolls. CONSTITUTION:Speed detectors PGu, PGd detect a speed of motors Mu, Md and electric current detectors 1u, 1d detect a load current of the motors Mu, Md; detected speeds are inputted to an adder-subtractor 1u and a subtractor 1d, and detected load currents are inputted to subtractors 3u, 3d, respectively. The adder-subtractor 1u outputs a speed difference found by calculation based on a speed command value Vref, feedback signal VFBu, and a correction signal from a slip prevention device 9 to a speed controller 2u. The subtractor 1d outputs a speed difference found by calculation based on the speed command Vref and feedback signal VFBu to the speed controller 2u. Speed correction signals from the speed controllers 2u, 2d are inputted to the subtractors 3u, 3d to drive the motors Mu, Md at a speed equal to the speed command value Vref.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a rolling method for preventing the slip phenomenon that occurs when hot or cold rolling a strip between a rolling roll and a strip in a tandem mill or the like. The present invention relates to a roll drive control method.

C. Prior Art] For example, when a strip is cold rolled at a high reduction rate in a cold tandem mill or the like, an abnormal rolling phenomenon called a slip phenomenon may occur between the work roll surface and the strip. This slip phenomenon is thought to occur when there is an extreme difference between the circumferential speed of the work roll and the strip moving speed. One of the reasons for this is as follows.

In a typical cold rolling mill, load balance control is used to control the drive motors for the upper and lower work rolls, in order to increase productivity by making the load currents of the upper and lower drive motors the same. However, in actual cold rolling, the load current of the circumferential drive motor often does not have the same value due to uneven lubrication conditions on the upper and lower sides, vertical asymmetry of the strip pass line, etc. In such a state, if an attempt is made to balance the loads on both drive motors using the load balance control described above, a speed difference will eventually occur in the re-drive motors.

When the speed difference between the upper and lower work rolls and the strip exceeds a certain value, the frictional work due to the relative slip between the work roll and the strip increases, the temperature of the oil film increases, and the temperatures of the work roll and strip surfaces also increase. The decrease in the viscosity of the oil film causes the oil film to run out, increasing the incidence of metal contact between the work roll and the strip, and causing slip defects on the work roll surface.

When the slip phenomenon occurs, slip flaws on the surface of the work roll are transferred to the strip, resulting in not only a decrease in the quality of the rolled product but also a problem such as a decrease in productivity due to replacement of the work roll.

FIG. 6 is a block diagram showing a conventional rolling roll drive control system, where Mu is the motor for driving the upper work roll, and Md is the motor for driving the upper work roll.
indicates the motor for driving the lower work roll.

Add/subtractor 1u+subtractor 1d for the speed command value V rat, respectively.
, speed control device 2u, 2d, load current detector 5u,
5d and thyristors 4u and 4d to the motors Mu and Md to drive the motors Mu and Md. During this process, the speed detector PGu attached to each motor Mu and Md
, PGd, and subtract it from the speed command value V rat as a feedback signal VFlu + vF8d. A signal corresponding to the speed difference is input to the speed control devices 2u and 2d, and the corresponding The correction signals from the speed control devices W2u and 2d are transmitted to the motors Mu and M.
d, the speeds of the motors Mu and Md are corrected, and drive control is performed at a speed that matches the speed command value V rat.

Furthermore, during rolling of the strip, the load currents of the motors Mu and Md of the upper and lower work rolls are detected, the difference between them is determined by the subtractor 8, and a signal corresponding to this is input to the load balance control device 7. A correction signal is output to the adder/subtractor 1u so that the loads of the work rolls match, and the speed of the motor Mu is corrected and controlled.

[Problem to be solved by the invention]

However, in the conventional method as described above, once a slip occurs between the upper work roll and the strip, the load on the upper work roll motor Mu decreases, and as a result,
A control signal is output from the load balance control device 7 so that the load is balanced on the motor Mu of the upper work roll, in other words, the speed is increased, which causes the problem that the slip phenomenon is further aggravated. Ta.

Also, when controlling the speed of the upper and lower work rolls, the load becomes unbalanced and the motor power cannot be used effectively.
There was also a problem that the number of passes increased or roll overcurrent occurred on one side.

The present invention has been made in view of the above circumstances, and its purpose is to prevent the slip phenomenon from occurring, and even if it occurs, to effectively suppress it without promoting it. The present invention provides a roll drive control method.

[Means to solve the problem]

The drive control method for rolling rolls according to the present invention detects the circumferential speed of each rolling roll and the speed of the rolled material on the exit side during rolling, and detects the difference between the circumferential speeds of both rolling rolls, or the difference between the circumferential speed of one of the rolling rolls and the rolled material. When the difference between the material speed and the material speed reaches a predetermined value, the load balance control is replaced by speed balance control in which the peripheral speed of at least one of the rolling rolls is adjusted to match the peripheral speeds of the upper and lower rolling rolls.

[Effect]

In the present invention, the occurrence of slip is detected or predicted based on the difference in the circumferential speed of the upper and lower work rolls, or the difference between the circumferential speed and the speed of the rolled material on the exit side of the stand, and the speed balance is controlled from the load balance control. Control is then switched to directly match the circumferential speeds of the upper and lower work rolls.

[Example] The present invention will be specifically described below based on drawings showing examples thereof.

FIG. 1 is a block diagram showing the control system of a rolling mill according to the present invention, in which 1u is an adder/subtractor, 1d is a subtracter, 2u is a speed control device for the upper work roll motor Mu, and 2d is a lower work roll motor. Roll motor Md speed control device, 3u, 3d
4u is a current control device for the upper work roll motor Mu, and 4d is a current control device for the lower work roll motor Md.

Speed 1 of upper and lower work rolls relative to motor Mu+Md
Order value V1. llf is an adder/subtractor 1u + a castle calculator 1d, respectively.
, speed control devices 2u, 2d, % subtractors 3u, 3d, current control devices 4u+4d, thyristors 5u, 5d, and are input to the upper work roll motor Mu and the lower work roll motor Md, which are driven to rotate. During this process, motor Mu is detected by speed detectors PGu and PGd attached to motors Mu and Md.

The load current of the motors Mu and Md is detected by the current detectors 1u and Id, and the detected speed is sent to the adder/subtractor lu and the subtractor 1d as a feedback signal VFBu l "Fad, and the load current is The feed puncture signals I□. and IF□ are input to subtracters 3u and 3d, respectively.

From the adder/subtractor 1u, the speed difference obtained by adding and subtracting the speed command values r, f, the feedback signal VFllu, and a correction signal from the slip prevention device 9, which will be described later, is sent to the speed control device 2.
υ, and the subtractor 1d outputs the speed difference obtained by subtracting the speed command value ■rQf and the feedback signal VFlu to the speed control device 2u, and the speed control devices 2u and 2d output a corresponding speed correction signal. is output to subtractors 3u and 3d, which subtract feedback signals IFfiu and IFIld from this speed correction signal, and the difference is sent to motors Mu and Md through thyristors 5u and 5d.
input the speed command values ■, for each motor Mu, Md. , the corrective control is performed so as to drive at a speed equal to .

Also, the speed detection values from the speed detectors PGu, PGd of the motors Mu, Md and the load detection values of the current detectors 1u, Id are taken into the slip prevention device 9, respectively.

The slip prevention device 9 includes a slip detection circuit 10 and a slip prevention circuit 20 as shown in FIGS.

FIG. 2 is a block diagram of the slip detection circuit 10,
The speed ■1 of the upper work roll motor Mu detected by the speed detector PGu is sent to the subtracter 11.12, and the speed Vd of the motor Md detected by the speed detector PGd is sent to the subtracter 1.
Go to 1.13, and the exit strip speed of the rolling stand■
, are input to subtracters 12 and 13, respectively, and subtraction is performed.

From the subtractor 11 are the motors Mu for the upper and lower work rolls.

The speed difference ΔVud of Md is output to the circumferential speed calculator 14.

The circumferential speed calculator 14 calculates the circumferential speed difference X1 between the upper and lower work rolls.
is calculated and output to the comparator 15. The comparator 15 compares the absolute value of the circumferential speed difference x with a preset manual value to see if it is larger than 1, and when 1xll>K,
- Outputs a signal to the OR circuit 1B indicating that a slip has occurred or is predicted to occur between the upper work roll and the strip 7, and outputs a signal to the OR circuit 18 indicating that a slip has occurred or is predicted to occur in the upper work roll. output the signal.

Further, the subtractor I2 outputs the difference X2 between the speed of the upper work roll motor Mu or the equivalent upper work roll circumferential speed and the strip speed vs on the exit side of the stand to the comparator 16, and when X2<0 In other words, when the circumferential speed of the work roll is greater than the output strip speed, a signal is output to the OR circuit 18, and the OR circuit 18 outputs a signal indicating that slip has occurred or is predicted to occur on the upper work roll. output.

Further, from the subtractor 13, the difference X between the old lower work roll motor speed v4 or the equivalent work roll circumferential speed and the stripping speed (2) on the exit side of the stand.

is output to the comparator 17, and when x<0, in other words, when the circumferential speed of the work roll is greater than the stripping speed on the exit side, a slip is generated or is predicted to occur on the lower work roll. Output a signal.

The signals generated from these comparators 15, 16, and 17 that predict the occurrence of a slip are sent to an OR circuit 18.
The output is output from the OR circuit 18 to a relay circuit (not shown), and by energizing the relay circuit or turning on the internal relay on the software, the normally open contact a in the slip prevention circuit 20 shown in FIG. It is designed to control the contact point to open the circuit.

FIG. 3 is a block diagram of the slip prevention circuit 20 according to the method of the present invention, which includes a load balance control system 21 and a speed balance control system 31. The load balance control system 21 includes a detected value I of the load current of the upper and lower work roll motors Mu and Md detected by the current detection units 2S5u and 5d,
, is input to the subtracter 22, and the difference ΔI is calculated by the load calculator 2.
3, the load calculator 23 calculates the load difference corresponding to the current difference ΔI, and outputs the signal necessary to eliminate this to PI (
A control signal necessary for the PI controller 24 to eliminate the difference in load is output to the adder 26 through the normally closed contact b and the hold circuit 25.

Until a slip occurs or a slip is predicted to occur, the normally closed contact A is closed and the normally open contact A is opened.
There is no output from the speed balance control system 31, and the output from the load balance control n system 21 is directly output to the adder/subtractor 11u, where it is added to the speed command value Vrar and sent to the speed control device 2u.
Output to.

When a slip occurs or a signal predicting that a slip occurs is issued from the OR circuit 18, the normally closed contact is opened, and the control of the load balance control system 21 is stopped, and the hold circuit controls the current PI controller 24. The output is held as is, and thereafter the held signal from the hold circuit 25 continues to be output to the adder 26.

On the other hand, the speed balance control system 31 includes a speed detector PGu.

Each motor Mu of the upper and lower work rolls detected by PGd.

The speeds V, , V, (or the circumferential speeds of the upper and lower work rolls) of 11d are manually input to the subtracter 32, and the difference ΔVud is input to the circumferential speed difference calculator 33 to generate a signal corresponding to the circumferential speed difference as PI.
The PI controller 34 outputs a control signal necessary to eliminate the circumferential speed difference to the adder 26 when the normally open contact a is closed.

The adder 26 connects the output of the r'I controller 34 and the hold circuit 2.
and the bold value of 5 and input it to the adder/subtractor 141,
As mentioned above, the speed command value ■1□ and the speed detector P
Add/subtract the output from Gu and output to the speed control device 2u.
Control as shown in FIG. 1 is performed.

FIGS. 4(a), 4(b), and 4(c) are explanatory diagrams showing an example of the above-mentioned control contents. As the peripheral speed difference between the upper and lower work rolls (or the speed difference between the motors Mu and Md) increases as shown in Figure 4 (a), the load balance increases as shown in Figure 4 (b). Although the output of the control system 21 also increases, there is no output from the speed balance control system 31 as shown in FIG. 4(c).

Then, the circumferential speed difference between the upper and lower work rolls is a value at which slip is predicted to occur, for example, 3% (work roll circumferential speed difference/
When the circumferential speed of the work roll corresponding to the speed command value is reached (1+), the output of the load balance control system 21 is held at the value at that time, the load balance control is stopped, and the output from the speed balance control system 31 is changed instead. occurs, and speed balance control is performed. This reduces the circumferential speed difference between the upper and lower work rolls, and when the circumferential speed difference becomes zero (t2), the speed balance control system 31
The output of is also maintained at that time.

After that, when the difference in circumferential speed between the upper and lower work rolls increases again (point 0 in the figure), the load balance control system 21 outputs a signal corresponding to the difference in circumferential speed until the difference reaches 3%, and When the speed difference reaches 3% (t3), the signal of the load balance control system 21 is held at the output at that time,
Instead, a control signal is output from the speed balance control system 31, and the same control as described above is performed.

Thereafter, as the circumferential speed difference between the upper and lower work rolls fluctuates, the control signal from the load balance control system 21 is output until the difference reaches 3%. An upper limit value is set for the output, and after that, control of the load balance control system 21 is stopped and control is performed only by the speed balance control system 31.

[Numerical example] Next, the method of the present invention will be explained using specific numerical values.

Using a 5-stand tandem rolling mill (upper and lower work roll diameter: 420 mm), plate thickness: 2.5 m + n, plate width:
During rolling with load balance control at a rolling speed of 1200 m/min with Q and 5 mm as the target thickness for a 1050 mm strip, the circumferences of the upper and lower work rolls were rolled as shown in Figure 5 (a) and (b). The speed difference fluctuates, and the circumferential speed difference is 3%.
, the speed balance control system is operated while the load balance control system output is set to the current output 202, as shown in FIG. 5 (b). Control was performed to adjust the circumferential speed of the upper work roll so that the circumferential speeds matched.

As a result, the circumferential speeds of the lower work rolls matched after a few seconds, and the occurrence of slip flaws could be prevented.

In the above embodiment, the load and circumferential speed of the upper and lower work rolls are determined from the load current and rotational speed of the drive motors Mu and Md, respectively. Of course, it is also possible to detect.

〔effect〕

As described above, in the method of the present invention, when the speed difference between the upper and lower rolls or the difference between the upper and lower rolls and the stripping speed on the exit side exceeds a certain level, the load balance control is adjusted to the speed balance while maintaining the load balance output. Since the process is started by switching to control, it is possible to prevent the occurrence of slip phenomena, and even if slip phenomena occur, the inconvenience of accelerating them is eliminated, effectively suppressing the occurrence of slip defects, etc. The present invention has excellent effects such as:

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the control system for implementing the method of the present invention, Figs. 2 and 3 are block diagrams showing the details of the slip prevention device, and Figs. 4 (a) and (b). . (c) is an explanatory diagram showing the control contents by the method of the present invention,
Figures (a) and (b) are explanatory diagrams showing control contents in numerical examples,
FIG. 6 is a block diagram that does not show the control system of the conventional method. Mu, Md...Motor PGu, PGd...Speed detector lu, ld...Speed control device 2u, 2d.
...Current control device 5u, 5d...Thyristor 9...
・Slip prevention device 11.12.13...Subtractor 1
4... Circumferential speed calculator 15.16.17... Comparator
18...OR circuit 21...Load balance control system 24...PI controller 25...Hold circuit 26...
... Adder 31 ... Speed balance control system 33 ...
Peripheral velocity calculator 34...PI controller 1 patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono District 1 Ward 5 Figure 5

Claims (1)

[Claims] 1. During rolling of the material to be rolled, the load on the upper and lower rolls is detected, and when a difference occurs between the two detected loads, the circumferential speed of one of the rolls is adjusted to eliminate this difference. In a rolling roll drive control method including load balance control, the circumferential speed of each rolling roll and the speed of the rolled material on the outlet side are detected during rolling, and the difference between the circumferential speeds of both rolling rolls or the circumferential speed and the rolled material of either roll is detected. When the difference with the rolling material speed reaches a predetermined value, instead of the load balance control, speed balance control is performed to adjust the peripheral speed of at least one of the rolling rolls so that the peripheral speeds of the upper and lower rolling rolls match. A drive control method for rolling rolls.