JPS61273213A - Slip detection method for bridle roll - Google Patents

Abstract

PURPOSE:To detect a slipping state precisely by calculating an actual tension controlling value by correcting a tension command value with a detected value by a strip tension detector and deciding a state as a slipping state when the actual tension controlling value exceeds a prescribed value. CONSTITUTION:A tension command value consisting of electric currents driving a bridle roll 3 at a specified constant rotation is corrected with a detected tension by a tension detector 5 and the actual tension controlling value is calculated based on the corrected tension command value. The actual tension controlling value is given to a driving motor for the bridle roll 3 and to drive the roll 3 so that a tension of a strip 1 between a cold rolling mill 2 and the roll 3 is kept at a constant value. In that time, the actual tension controlling value which controls the driving motor for the roll 3 is monitored; the normal state without a slip between the strip 1 and roll 3 is decided when that controlling value does not exceed the prescribed value and a slipping state is decided when that controlling value exceeds the prescribed value.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention detects the slip of a bridle roll that applies a tension step to a strip based on an actual tension control value supplied to a drive motor that drives the bridle roll. This invention relates to a slip detection method for a bridle roll.

[Conventional technology]

Generally, bridle rolls are used in equipment such as continuous pickling, cold rolling mills, continuous annealing, skin pass mills, and refining because they can impart tension steps to the strip. Among these, when applied to a cold rolling mill or when performing a wet skin bath in a skin pass mill, rolling oil and skin bath oil adhere to the strip, reducing the coefficient of friction between the bridle roll and the strip. That will happen.

-a, the winding angle of the bridle roll is θ radian, and the friction coefficient is μ, then the maximum allowable tension level difference T0/TI on the entrance and exit sides of the bridle roll is 'l',
/7', W 6#.

Therefore, as the friction coefficient μ decreases, the allowable tension difference decreases exponentially. If this tolerance is exceeded, slippage will occur between the bridle roll and the strip, causing flaws in the strip, leading to a decrease in yield and production efficiency.

On the other hand, there is a demand for maximizing the bridle roll replacement cycle in order to reduce maintenance costs, and trying to satisfy this requirement increases the possibility of the bridle roll slipping.

Furthermore, recently there have been cases where bridle rolls are installed on the exit side of ultra-high-speed rolling mills of 2000 m/1 Iin, etc., but the higher the rotation speed, the more air is drawn in between the strip and the bridle roll, which reduces the coefficient of friction. also decreases. Therefore, it has been strongly desired to detect the slip state between the bridle roll and the strip.

For this reason, conventionally, as a method for detecting slip between the bridle roll and the strip,
As disclosed in No. 087, a transfer speed detection roller is brought into rolling contact with the conveyed strip, and the strip transfer speed is detected from the outer diameter and rotational speed of the transfer speed detection roller. The circumferential speed of the bridle roll is calculated from the product of this and the outer diameter, and if the strip transfer speed and the circumferential speed of the bridle roll are approximately zero, it is determined that there is no slip, and the two do not match. A bridle roll slip detection method has been proposed that determines that there is a slip in this state.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional bridle roll slip detection method, the strip transfer speed is calculated based on the outer diameter and rotation speed of the transfer speed detection roller that comes into contact with the strip, so rolling oil is applied to the strip. When the strip or skin bath oil adheres to the strip, slip occurs between the strip and the roller for detecting the transfer speed, resulting in a problem that the slip state cannot be detected with high accuracy.

Therefore, the present invention calculates an actual tension control value based on a speed command value that controls the rotational speed of the bridle roll and a tension detection value from a tension meter that detects the actual tension of the strip, and calculates the actual tension control value. The object of the present invention is to provide a bridle roll slip detection method capable of determining a slip state when the absolute value exceeds a predetermined set value and detecting the slip state between the bridle roll and the strip with high precision. .

[Means for solving problems]

In order to achieve the above object, the present invention corrects the tension command value for constant current control of the drive motor of the bridle roll that applies tension steps to the strip by the detected value of the strip tension detector. An actual tension control value for controlling the strip tension at a fixed value on the entrance side or exit side of the bridle roll is calculated, and when the actual tension control value exceeds a predetermined set value, it is determined that the bridle roll is in a slip state. It is characterized by what it did.

[Effect]

This invention corrects the tension command value for constant current control of the drive motor of the bridle roll, which applies tension steps to the strip, with the detected value of the strip tension detector. An actual tension control value for controlling the strip tension to a fixed value is calculated, and when this actual tension control value exceeds a predetermined set value, it is determined that a slip state has occurred.In other words, when slip occurs between the bridle roll and the strip, the control target is The tension difference between the input side and the output side of the bridle roll disappears, and therefore the tension detection value of the strip tension meter changes, and accordingly, the actual tension control value also changes significantly compared to the normal state. However, even if the rotation speed of the bridle roll is changed to correct this by changing the actual tension control value, the tension detection value of the strip tension needle does not change due to slip, and therefore the actual tension control value is in a state where it has changed significantly. will be maintained. In this way, by detecting when the actual tension control value changes significantly and exceeds the predetermined set value, the slip state between the bridle roll and the strip can be detected with high accuracy.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

First, the basic principle of the present invention will be explained in such a way that a strip l is cold rolled in a cold rolling mill 2 having a plurality of stands and then wound onto a tension reel 4 via a bridle roll 3, as shown in FIG. A case where a bridle roll is arranged on the exit side of a cold rolling mill will be explained.

Here, the bridle roll 3 separates the tension at the exit side of the final stand of the cold rolling mill 2 from the winding tension of the tension reel 4 to provide a tension difference between the two, thereby stabilizing the rolling of the strip l. It plays the role of maintaining the proper winding tension while maintaining the proper winding tension.

and strip tension detectors 5 for detecting the tension of the strip 1 between the cold rolling mill 2 and the bridle roll 3 and between the bridle roll 3 and the tension reel 4, respectively;
6 is arranged, and the tension command value ST, which is a current value for driving the bridle roll 3 to rotate at a constant value, is corrected based on the tension detection value T of the tension detector 5, and the actual tension control value SC is determined based on the corrected tension command value STA. is calculated and supplied to the driving motor 3a of the bridle roll 3 to rotate the bridle roll 3 so as to maintain the tension of the strip 1 between the cold rolling mill 2 and the bridle roll 3 at a constant value. On the other hand, the tension value T detected by the tension meter 6. is supplied to the driving motor 4a of the tension reel 4 as a current command value for driving the tension reel 4 with a predetermined winding force, and controls the tension of the strip 1 between the bridle roll 3 and the tension reel 4 to a predetermined set value. .

By the way, assuming that there is no slip between the strip 1 and the bridle roll 3, there is a predetermined tension difference between the entry and exit sides of the bridle roll 30, and in order to ensure this, the bridle roll 3 is The drive motor 3a is controlled by the actual tension control value, and the drive motor 4a of the tension reel 4 is controlled by the tension detection value of the tension meter 6, so that a predetermined tension difference is maintained between the two.

If a slip occurs between the strip 1 and the bridle roll 3 in this normal state, the bridle roll 3
Since the tension difference between the entrance and exit sides of the bridle roll 3 is approximately zero, the actual tension control value SC that controls the drive motor 3a of the bridle roll 3 is set to ensure the tension difference between the entrance and exit sides of the bridle roll 3. This is a very large value.

That is, an explanation will be given with reference to FIG. 2 showing the results of an experiment using as an example a fully continuous rolling mill that welds a strip l on the inlet side of the cold rolling mill 2 and cuts it on the outlet side. As shown in FIG. 2(a), when the tension on the entry side of the bridle roll 3 was changed while changing the rolling speed of the cold rolling mill 2, slipping of the bridle roll occurred intermittently. Here, the actual tension control value SC is ± of the tension setting value.
When the output was set to be saturated at 10%, the bridle roll 3 continued to slip, so the actual tension control value S
C is -10% and +10% as shown in Figure 2(d).
It was confirmed that both were saturated.

In addition, in the experimental results shown in FIG. 2, from time point t0 to time point 1.
In between, the tension target value on the exit side of the bridle roll 3 is set higher than the tension target value on the input side, and after the time t, manual intervention is performed to lower the tension target value by the tension reel 4. and do bridle roll 3
This is measurement data when the tension target value on the inlet side is controlled to be higher than that on the outlet side.

According to the experimental results shown in Fig. 2, under normal conditions, tension detection values T1 and 'ro corresponding to preset tension steps are output from the tension detector 5.6. When a slip occurs between the bridle roll 1 and the bridle roll 3, the tension detection values T, , To of the tension detector 5.6 are approximately equal as shown in FIG. 2) and (C1), and the tension between them is The bridle roll 3 is detected as having no level difference. Therefore, the bridle roll 3 is rotated as shown in FIG. The actual tension control value SC in the saturated state that reverses the tension and weakens the tension on the inlet side is the driving motor 3 of the bridle roll 3.
It is output to a. Also, at time t8. From now on, T
An actual tension control value SC in a saturated state that rotates the bridle roll 3 in the normal direction and weakens the tension on its exit side is output to the drive motor 3a so as to maintain the relationship I>T o.

Based on the above knowledge, the present inventors monitor the actual tension control value SC that controls the drive motor 3a of the bridle roll 3, and when the actual tension control value SC does not exceed a predetermined set value, the tension is increased between the strip 1 and the bridle roll 3. It is determined that the condition is normal with no slippage, and if the value exceeds a predetermined set value, it is determined that slippage has occurred between the strip 1 and the bridle roll 3, so that rolling oil, skin bath oil, etc. We discovered that it is possible to detect slip conditions with high accuracy without being affected.
This invention has now been provided.

Next, a specific embodiment applicable to the bridle roll slip detection method according to the present invention will be described with reference to FIG.

In FIG. 3, 7 is a tension setting circuit for setting the strip tension between the cold rolling mill 2 and the bridle roll 3, and outputs a tension command value ST having a current value corresponding to a desired strip tension.

This tension command value ST is supplied to a subtraction circuit 8 which is supplied with a tension detection value T from a strip tension meter 5 disposed on the entrance side of the bridle roll 3, and is detected by the tension meter 5 in this subtraction circuit 8. The actual tension detection value T1 is subtracted and corrected, and the subtraction circuit 8 outputs it as a corrected tension command value STA.

The corrected tension command value STA is supplied to the gain correction circuit 9, and the fixed gain G set in advance is supplied to the gain correction circuit 9.
+ and then supplied to the gain correction circuit lO,
The rotation speed of the bridle roll 3 is multiplied by the gain G2 from the function generator 12 determined based on the rotation speed detection value from the rotation speed detector 11 that detects the rotation speed.

Thereafter, the gain correction output of the gain correction circuit 10 is supplied to the division circuit 13 as the dividend, and the division circuit 13
Division is performed using the tension command value ST supplied from the tension setting circuit 7 as a divisor to calculate a corrected tension command value which is a percentage of the tension command value.

The corrected tension command value is then supplied to an integrator 15 via a gate circuit 14 to which a control signal ATR indicating whether or not to perform actual tension control is supplied from the outside, and is integrated by this integrator 15 to control the actual tension. This is output as a value SC, which is supplied to the limiter 16 to limit its upper and lower limit values to predetermined values and output to the driving motor 3a of the bridle roll 3.

On the other hand, the actual tension control value SC output from the integrator 15 is
It is supplied to the absolute value circuit 17 and converted into an absolute value, and then compared with the dark value TH from the dark value setting circuit 19 in the comparator circuit 18, and when the absolute value of the actual tension control value SC is less than the threshold value TH. It is determined that there is no slip between the strip 1 and the bridle roll 3, and the logical value is "0".
When the threshold value TH is exceeded, it is determined that a slip has occurred between the strip 1 and the bridle roll 3, and a slip state detection signal SD of logical value "1" is output.

This slip state detection signal SD is supplied to the slip state alarm circuit 20, and when the slip state detection signal SD is the logical value "1" in this slip state alarm circuit 20,
An acoustic signal generator such as a buzzer is activated to generate an alarm sound, or an optical signal generator such as a lamp is activated to generate an alarm light.

Assuming that there is no slip between the strip 1 and the bridle roll 3 in a normal state, the tension command value ST from the tension setting circuit 7 and the strip tension meter 5
The subtraction circuit 8 outputs a corrected tension command value STA according to the difference value between the tension detection value T1 and the tension detection value T1. That is, when the tension detection value T1 of the strip tension meter is smaller (or larger) than the tension command value ST, a positive (or negative) corrected tension command value STA is output from the subtraction circuit 8, and the gain correction circuit 13 outputs a positive (or negative) corrected tension command value STA. After performing a predetermined gain correction in step .14 and further integrating the value in an integrator 15, the limiter 16 limits the value to a predetermined range and outputs it to the driving motor 3a of the bridle roll 3 as an actual tension control value SC. Therefore, the drive motor 3a
is driven forward (or reverse) at a predetermined speed, the bridle roll 3 rotates forward (or reverse), increasing (or decreasing) the strip tension between the cold rolling mill 2 and the bridle roll 3, thereby increasing the strip tension. is controlled so that it becomes a value corresponding to the tension command value ST. In this normal state, the deviation between the tension command value ST and the tension detection value T1 is small, and the absolute value of the actual tension control value SC is less than or equal to the predetermined threshold value TH. Therefore, the slip state alarm signal S output from the comparator circuit 18
D maintains the logical value "0" and the alarm circuit 20 does not issue an alarm.

When this normal state becomes such that rolling oil or skin bath oil adheres to the strip 1 and slip occurs between the strip 1 and the bridle roll 3, the tension difference between the input side and the output side of the bridle roll 3 becomes approximately zero. Therefore, the strip tension between the cold rolling mill 2 and the bridle roll 3 depends on the winding force of the tension reel 4, and is determined by the tension command value ST from the tension setting circuit 8 and the strip tension meter 5. The deviation from the strip tension detection value T becomes large. Therefore, the corrected tension command value STA output from the subtraction circuit 8 becomes thicker in the positive or negative direction (the output value of the division circuit 13 also increases accordingly, and the actual tension obtained by integrating this with the integrator 15 The control value SC also increases.This actual tension control value SC is converted into an absolute value by the absolute value circuit 17 and the value is supplied to the comparator circuit 1°8. Compare and the comparison result is
When the actual tension control value SC exceeds the predetermined threshold TH, the comparator circuit 18 outputs a slip state detection signal SD with a logical value of "1" to the slip state alarm circuit 20, and the alarm circuit 20 issues a predetermined slip alarm. Emitted.

In addition, in the above embodiment, the case where the bridle roll was arranged on the exit side of the cold rolling mill 2 was explained, but the bridle roll is not limited to this, and the bridle roll is arranged on the entry side of the cold rolling mill 2, the pickling device, Of course, the present invention can be applied even when the looper is placed at any arbitrary position such as the entrance or exit side of the looper.

Further, in the above embodiment, the case where the strip tension on the entry side of the bridle roll 3 is controlled is explained, but the invention is not limited to this, and the present invention can also be applied to the case where the strip tension on the exit side of the bridle roll 3 is controlled. obtain.

〔Effect of the invention〕

As explained above, according to the present invention, the strip tension on the entry side or the exit side of the bridle roll is detected by a strip tension meter, and the strip tension command value is corrected based on the detected value, so that the actual tension control value is When controlling the rotational drive of the bridle roll based on this actual tension control value to perform tension control, slipping occurs between the strip and the bridle roll when the actual tension control value is greater than a predetermined set value. The slip state of the bridle roll is now detected.

For this reason, there is no need to separately install a speed detection roller to detect the strip speed as in the conventional example, and the actual tension control value is monitored without being affected by rolling oil, skin bath oil, etc. that adheres to the strip. Since the slip state is detected using the above-mentioned method, the slip detection accuracy can be significantly improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an example of a cold rolling equipment to which the present invention can be applied, and Fig. 2 shows experimental results in a state where slip occurred in the rolling mill exit bridle roll of a fully continuous cold rolling equipment. The signal waveform diagram shown in FIG. 3 is a block diagram showing an example of an actual tension control device that can be applied to the present invention. 1... Strip, 2... Cold rolling mill, 3... Bridle roll, 3a...
Drive motor, 4... tension reel, 5.
6...Strip tension meter, 7...Tension setting circuit, 8...Subtraction circuit, 10°11...
... Gain correction circuit, 13 ... Division circuit, 1
5...Integrator, 16...Limiter, 1
7...Absolute value circuit, 18...Comparison circuit, 19...Threshold value setting circuit, 20...Slip condition alarm circuit.

Claims (1)

[Claims] By correcting the tension command value for constant current control of the drive motor of the bridle roll that applies tension steps to the strip using the detected value of the strip tension detector,
An actual tension control value is calculated for controlling the strip tension on the entrance side or exit side of the bridle roll to a fixed value, and when the actual tension control value exceeds a predetermined set value, it is determined that the bridle roll is in a slip state. A bridle roll slip detection method characterized by: