JPS613607A - Detection of slip of rolling roll - Google Patents

Abstract

PURPOSE:To detect surely and quickly slip by detecting the field currents of DC motors for un-coiler and coiler. CONSTITUTION:The field currents If1 and If2 of the un-coiling and coiling motors change sharply and simultaneously in the same direction when the slip arises between a material to be rolled and a rolling mill. The detection signal from the current detector 24 of the current If1 is inputted to a differentiator 25 and the detection signal from the current detector 27 of the current If2 is inputted to the other differentiator 28. The signals corresponding to the directions of the change in the currents If1, If2 from differentiators 25, 28 are respectively outputted to a multiplier 26 by which the two signals are multiplied. The output from the multiplier is inputted to a polarity discriminator 29. The polarity of the output from the discriminator 29 changes to (+) when the currents If1, If2 change sharply in the same direction upon generation of the slip. The generation of the roll slip is thus electrically, surely and quickly detected in said direction.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention is a rolling machine that continuously rolls rolled materials such as steel plates, films, and paper, by electrically reducing the slip phenomenon that occurs between the rolling rolls and the rolled materials. related to a method of detecting

[Background of the invention]

It is generally known that in cold rolling systems for steel plates, slippage occurs between the rolling rolls and the material to be rolled due to the surface condition of the rolling rolls, the surface condition of the material to be rolled, or other factors. It is being This slip causes fluctuations in the tension of the rolled material, resulting in a decrease in product quality, and also generates abnormal noise, so it must be suppressed or prevented as much as possible.

The traditional method for detecting the occurrence of this slip was generally based on empirical judgment by an expert. The empirical judgment is based on, for example, the rolling condition of the rolling mill or abnormal sounds.

A more advanced method is to actually measure the running speed of the material to be rolled at the entrance and exit sides of the rolling roll using a roll circumferential speed detector, etc., find the ratio, and use a predetermined rolling reduction ratio. There is a method in which the ratio of the calculated running speeds is determined in advance and it is determined that a slip has occurred when the difference between the two values exceeds a certain value (see Japanese Patent Publication No. 59-1132).

This method has higher detection accuracy than methods based on intuitive judgment by experts, and is extremely superior in that it can be processed uniformly. This method requires additional equipment such as, and new equipment is required in order to apply it to an existing rolling system.

[Purpose of the invention]

An object of the present invention is to provide a detection method that can reliably detect the slip phenomenon occurring between a rolling roll and a rolled material by an electrical method.

[Summary of the invention]

In order to achieve the above object, the rolling roll slip detection method according to the present invention includes disposing an unwinding machine and a winding machine driven by a DC motor on the entry side and exit side of the rolling mill,
A rolling system that continuously rolls a rolled material wound into a coil while unwinding the material, characterized in that fluctuations in the field current of the DC motors of the unwinding machine and the winding machine are detected. .

[Embodiments of the invention]

Next, an embodiment of the slip detection method according to the present invention will be described based on the drawings.

First, FIG. 1 shows an overview of a cold rolling system that uses a planer plate as the material to be rolled. In FIG. 1, an unwinding machine 2 is disposed on the entry side of a rolling mill 1, and a strip-shaped rolled material 3 is transferred from a coil-shaped rolled material 3 attached to this unwinding machine 2 at the exit of the rolling mill 1. Rolling is performed while being wound up by a winding machine 4 disposed on the side. The rewinding machine 2 and the winding machine 4 are driven by a rewinding DC motor (hereinafter referred to as the unwinding motor) 5 and a winding DC motor (hereinafter referred to as the winding motor) 6, respectively. In order to keep the tension of the rolled material 3 constant, each of these electric motors 5 and 6 applies a field current directly proportional to the rolling speed (speed of the mill 1) to each of its field windings 7 and 8 by a control circuit to be described later. Normally, the armature voltage is controlled to be kept constant by supplying That is, if the speed of the rolling mill 1 is constant, the armature voltage is also constant.

Next, details of rolling control will be explained. As shown in FIG. 1, control circuits 9 and 10 are added to the unwinding motor 5 and the take-up motor 6, respectively, and are attached to a DC motor 11 for driving the rolling mill 3 via a coupling 12. It appears that the mill speed feedback signal vm from the pilot generator 13 is used for shift feedback control.

In the control circuit 9, a main current command m set in advance by a setup computer (not shown) or the like is given to a main current control device 14, and the main current control device 14 is driven from the main power thyristor device 15 based on the control number. A current m2 is applied to the armature of the rewinding motor 5. On the other hand, the mill speed feedback signal m from the pilot generator 13 is fed back to the addition element 16, and the rewinding motor 5 is fed back to the addition element 16.
Armature voltage feedback signal from vf! and the combined signal is given to the motor control device 17. The field Zyristor device 18 is controlled by the output control signal, and a field current is applied to the field winding 7 to keep the mill speed constant.

The control circuit 10 has exactly the same configuration as the control circuit 9, and the main current control device 19 supplies the drive current ml from the main power supply thyristor device 20 to the winding motor 6 according to the main current command m. Also, the mill speed feedback signal vm
and armature voltage feedback signal Vf1 are given to the motor control device 22 via the addition element 21, and the field thyristor device 2
3, the field current that keeps the mill speed constant is applied to the field winding 8.
supplied to

Next, the control operation will be explained based on the signal waveforms of each part shown in FIG. In FIG. 2, the section from time tO to t3 shows various signals of the normal rolling section, and the armature voltages Vf1°vf2 of the unwinding motor 5 and the take-up motor 6 are the rolling mill speed
m, and the field currents Ift and If2 are constant at this time. Now, when the rolling speed is accelerated over time tlxt, the armature voltage Vf2. of each electric motor 5.6 increases. Vft changes. At this time, each armature current of 1 ml, Im2, changes as shown in the figure. This is to keep the tension acting on the rolled material 3 constant by passing a forcing current to compensate for acceleration.

Suppose that slip occurs between the rolled material 3 and the rolling mill 1 during such operation (time ts
). Then, the traveling speed of the material to be rolled 30 suddenly becomes lower than the speed of the rolling mill 1, and the decrease in the traveling speed of the material to be rolled 3 leads to a decrease in the rotational speed of the winding motor 6, so that the armature voltage fI decreases. I will do it. The control circuit 10 is configured to keep the armature voltage Vf1 constant, and when the value of the armature voltage feedback signal f1 decreases with respect to the value of the mill speed feedback signal m, the stain motor control device 17 is activated. It operates to rapidly increase the field current If+. However, if the slip continues, the relationship between the traveling speed of the rolled material 30 and the speed of the rolling mill 1 is still not resolved, and the control circuit 9 acts to further increase the field current ■fl. As a result, the field current f continues to increase rapidly and finally reaches the saturation point.

On the other hand, the effects of a sudden drop in the traveling speed of the rolled material 30 due to the occurrence of slip also appear as a drop in the rotational speed of the unwinding motor 5, resulting in a drop in the armature voltage f2. The control circuit 9 is configured to keep the armature voltage Vfz constant, and since the value of the armature voltage feedback signal Vf decreases with respect to the mill speed feedback signal VmO value, the motor control device 22 controls the field current Ifz. act to rapidly increase the However, if the slip continues as on the winding side, the field current If increases more and more, and finally reaches the saturation point.

In this way, during normal rolling up to time 1o #18, constant voltage control is performed to keep the tension constant on the premise that the rolling speed of the mill and the running speed of the rolled material 3 match. However, once slip occurs, an over-control state occurs based on the difference between the mill rolling speed and the running speed of the rolled material 3, and in severe cases, the rolled material 3 is over-tensioned.
There is even a risk of it breaking.

In addition, when the traveling speed of the material 3 to be rolled due to slip becomes higher than the rolling speed of the mill, both the field currents Ifl and Ifm decrease, contrary to the above-mentioned control operation. In addition, in FIG. 2, T indicates the variation in plate thickness on the outlet side of the rolling mill, and P indicates the rolling load.

Now, in this way, when slip occurs, each field current J
Both fl and If* suddenly change in the same polar direction, and a phenomenon that is clearly different from that during normal rolling occurs. Therefore, each field current Ifl.

By detecting a sudden change in Ifz, it becomes possible to accurately and electrically detect the occurrence of slip. This is the detection principle of the present invention.

Next, a device for accurately detecting and determining slip will be described.

FIG. 3 shows an example of the detection capacity. In FIG. 3, a detection signal from a current detector 24 of the field current Ifs of the winding motor 5 is input to a differentiator 25.

The differentiator 25 generates a signal corresponding to the direction of change in the field current Ifs (for example, (+) if it increases, (+) if it decreases).
-)) is output to the multiplier 26.

On the other hand, the current detector 27 for the field current Ift of the rewinding motor 6
The detection signal from the is input to another differentiator 28, and similarly, a signal corresponding to the direction of change in the field current Ifz is input to the multiplier 26.
is output to. The multiplier 26 multiplies the two differential output signals together and outputs the result to the polarity discriminator 29. Polarity discriminator 29
It is possible to determine the polarity of the input signal and detect whether syslip has occurred based on the polarity.

Next, the operation will be explained. During normal rolling (t″o=ts), the changing directions of the field currents Ifs and Ifz are opposite to each other as shown in FIG.
The polarity of the output signal from 8 is (+).

(-), and this signal is multiplied by the multiplier 26, so the polarity of the multiplier output becomes (-), and the output signal of the polarity discriminator 29 does not mean that a slip has occurred. However, as shown from time t3 to t4 in FIG.
+ and Ifm change simultaneously and in the same direction and rapidly, the polarities of the output signals from each differentiator 25 and 28 are both (+), and therefore the polarity of the output signal of the multiplier 26 is also ( +). This signal having a (+) polarity means generation of a slip signal in the polarity discriminator 29, and based on this signal, the reduction rate of the rolling mill can be lowered to prevent the occurrence of slip. Note that, for example, in terms of signal processing, even if all the polarity states of the above-mentioned signals are reversed, the result will be the same, and it goes without saying that the detection can be performed in the same way. In addition, although a differentiator was used to detect the polarity, in another embodiment, a comparator was used to detect each field current If.

Engineering f! The reference value (
A threshold value) may be set, and it may be determined that a slip has occurred when both field currents I'l+Tf2 exceed a reference value. Furthermore, the flesh field current If1. By directly adding or subtracting the If* detection signal, the direction of change in the field currents is opposite during normal times, resulting in a nearly constant value υ; when abnormal, the values change in the same direction, so the added/subtracted value becomes an abnormal value. The occurrence of slip can be detected.

In this way, by monitoring the behavior of the fields V and currents Ifl and If2, it is possible to realize The occurrence of slip can be electrically detected accurately and quickly using existing equipment. As a result, the time from the occurrence of slip to the time when preventive measures are taken can be shortened, and it is possible to minimize deterioration in quality due to slip, or to prevent breakage of the rolled material. This contributes to improving the yield of the rolled material. In addition, in the event of a break, it is necessary to temporarily stop the rolling line, but since the slip is detected quickly, it is possible to suppress the occurrence of a break, prevent loss of operating time, and improve productivity. can contribute to the improvement of

〔Effect of the invention〕

As described above, according to the present invention, the traveling speed of the material to be rolled is directly detected by detecting the fluctuation of the field current of the DC motor for driving the winding machine and the unwinding machine installed in the rolling system. It is possible to electrically detect slip occurring between the rolling roll and the rolled material reliably and quickly without using such means.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a general cold rolling system, Fig. 2 is a waveform diagram showing signal waveforms of each part of the rolling control device, and Fig. 3 is a detection device for carrying out slip detection according to the present invention. It is a block diagram showing an example. DESCRIPTION OF SYMBOLS 1... Rolling mill, 2... Unwinding machine, 3... Rolled material, 4... Winding machine, 5... Unwinding motor, 6... Winding motor, ■fl.・・Field current of the winding motor, If2・
...Field current of the rewinding motor, 24...Current detector, 2
5... Differentiator, 26... Multiplier, 27... Current detector, 28... Differentiator, 29... Polarity discriminator.

Claims (1)

[Claims] 1. A rolling system in which an unwinding machine and a winding machine driven by a DC motor are arranged on the entry and exit sides of the rolling mill, and rolling is performed while unwinding the rolling machine wound into a coil. In the rolling roll, slip occurring between the rolling roll of the rolling mill and the rolled material is detected by detecting fluctuations in field currents of DC motors of the unwinding machine and the winding machine. slip detection method.