JPH10263690A - Method for controlling tension of bridle roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate the coefficient of friction and to prevent a slip of a bridle roll and a strip. SOLUTION: By using the limit coefficient of friction made in a limit of generating a slip of a strip with the total bridle roll obtained from the tension value of the strip at the inlet side and the outlet side of the bridle roll A, the load balance ratio to each roll 10, 12, 14 in the bridle roll is decided, the load balance control to control the load on each roll based on this ratio is executed, and in the case of detecting the occurrence of the slip from the circumferential speed of each roll measured with pulse generators PLG1 to PLG4 during operating, the coefficient of friction in the slip occurrence time is estimated based on the respective tension values T1, T2 of the outlet side and the inlet side of the bridle roll, by using this estimating value, the set tension values T1 and T2 are decided and corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bridle roll tension control method suitable for controlling the tension of a strip in a bridle roll.

[0002]

2. Description of the Related Art Continuously transported strip (material)
In order to apply an appropriate tension to the bridle roll, it is important to control the bridle roll so that no slip occurs between the two.

As described above, in order to prevent a slip from occurring between the bridle roll and the strip,
It is necessary to accurately grasp the friction coefficient between the two, which is the limit at which slip occurs.

Conventionally, as a method of estimating a friction coefficient between a roll and a material, a ratio of a tension applied to a strip before and after a roll (a tension ratio) as proposed in Japanese Patent Application Laid-Open No. 8-145876 has been proposed. ) Is known.

In order to grasp the friction coefficient as described above, it is necessary to detect the occurrence of the slip.
As a method of detecting slip in a bridle roll, a method of detecting slip from the difference between the product of each roll diameter and the number of rotations of the bridle roll as disclosed in Japanese Patent Application Laid-Open No. 61-249620 is known. I have.

[0006]

However, in the conventional method proposed in the above-mentioned Japanese Patent Application Laid-Open No. 8-145876, when a plurality of rolls are set as in a bridle roll, there is a problem in that Since the tension of the rolls is unknown, there has been a problem that the friction coefficient of each roll cannot be accurately estimated only from the tension ratio applied to the strips before and after the bridle roll (the entrance side and the exit side).

Also, when setting the tension before and after the bridle roll, since the calculation is performed using a value assumed in advance as the friction coefficient, even if the tension ratio is determined based on the friction coefficient, the actual friction coefficient is determined. (Actual friction coefficient), there is a problem that slip easily occurs between the roll and the strip.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to reliably prevent a slip between a bridle roll and a strip by enabling a friction coefficient to be accurately estimated. An object of the present invention is to provide a bridle roll tension control method that can perform the above-described method.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a bridle roll tension control method for controlling the tension of a strip in a bridle roll having a plurality of rolls. Based on the calculated friction coefficient which is a limit at which slip occurs between the entire bridle roll and the strip, a load balance ratio for each roll constituting the bridle roll is determined from the limit friction coefficient, Load balance control is performed to control the load on each of the rolls based on the load balance ratio, and when slippage is detected from the peripheral speed of each of the rolls measured during operation, the entrance and exit of the bridle roll are detected. Based on the strip tension value of each side, the friction coefficient at the time of slip Constant and, using estimated value, determines a tension value to be set in each entry side and exit side of the bridle rolls, by modifying, is obtained by solving the above problems.

That is, in the present invention, by performing load balance control for balancing the friction margin of each roll of the bridle roll as described in detail below,
At that time, the friction coefficient between the roll and the material can be accurately estimated from the tension ratio measured before and after the bridle roll.

In the present invention, when the friction coefficient estimated at the time of occurrence of slip is sequentially learned and the set tension value is determined using the friction coefficient learned value, the friction coefficient estimated as described above is used. Since the difference between the actual friction coefficient and the actual friction coefficient can be reduced, slip on the bridle roll can be reliably prevented by determining the tension set values before and after the bridle roll based on the learning value.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 schematically shows a bridle roll applied to an embodiment of the present invention and a strip transport line including peripheral devices thereof, and FIG. 2 is a schematic configuration of a control system for controlling the bridle roll. FIG.

The bridle roll A applied to the present embodiment includes first, second and third three rolls 10, 12, 1
4, which is used to apply an appropriate tension to a strip S such as a steel sheet conveyed in the direction of the arrow.

The first, second, and third rolls 10,
The motors M1, M2, M3 rotate the motors 12, 14, respectively, and the peripheral speeds of the rotating rolls are output from pulse generators PLG1, PLG2, PLG3 attached to the motors M1, M2, M3, respectively. Each is measured based on the signal.

A speed measuring roll 16 is disposed downstream of the bridle roll A. Based on a signal from a pulse generator PLG4 attached to the roll, the transport speed of the strip S is determined as a roll peripheral speed. Measured before and after the bridle roll A
8. Discharge-side tensiometers 20 are provided, respectively, so that the tensions T1 and T2 before and after the roll A are respectively measured.

The control system shown in FIG. 2 includes a line controller 22 for controlling the entire line, a tension set value calculator 24, and a motor drive controller 26.

The peripheral speeds of the rolls 10, 12, 14, and 16 are input to the line control device 22 as pulse signals from pulse generators PLG1 to PLG4, respectively. Here, the signals from the PLG4 and the PLG1 to PLG4 are input.
The slip between the rolls and the strip S is detected by the difference between the transport speed of the strip S and the peripheral speed of each of the rolls 10, 12, and 14, which is obtained from each signal of the PLG3.

In addition, the line controller 22 includes an entrance tension T1 and an exit tension T2 measured before and after the bridle roll A from the entrance tension meter 18 and the exit tension meter 20, respectively.
Are input, and at the timing when the slip is detected as described above, each of the tension values T on the entrance side and the exit side at that time.
1, a coefficient of friction is estimated based on T2 by a method described later.

As described above, the friction coefficient estimated and calculated by the line control device 22 every time the occurrence of slip is detected is
The tension set value is input to the tension set value calculation device 24, where the learning is performed, and a tension set value to be set before and after the bridle roll A is determined using the learned value. 22. The line control device 22 outputs the inputted tension set value to the motor drive control device 26, and controls the torque of each of the motors M1, M2, M3 based on the set value.

Here, the premise of this embodiment is:
A load balance control method capable of balancing the friction margin between each roll and the material of the bridle roll will be described in detail with reference to FIGS.

Here, the frictional margin is defined as a friction coefficient (minimum necessary for preventing the entire bridle roll and the material from slipping, which is determined from a tension ratio before and after the bridle roll (entrance side, exit side). (Hereinafter referred to as the critical coefficient of friction) and the maximum coefficient of static friction between the roll and the material.

The above-mentioned load balance control method is a technique which has been proposed by the present applicant in Japanese Patent Application No. 8-288151. When controlling the load on each roll of a bridle roll composed of a plurality of rolls, Based on the strip tension values of the entrance side and the exit side of the bridle roll, calculate a limit friction coefficient that is a limit at which a slip occurs between the entire bridle roll and the strip,
A load balance ratio for each roll constituting the bridle roll is determined from the limit friction coefficient, and a load on each roll is controlled based on the load balance ratio.

FIG. 3 is an enlarged view of the relationship between the three rolls constituting the bridle roll shown in FIG. 1 for explaining the load balance control method, and FIG. FIG. 3 is a block diagram showing a schematic configuration of a load balance control device corresponding to the motor drive control device 26 shown in FIG. 2 and applied to roll drive control.

The bridle roll A continuously transports the strip indicated by the symbol S in the direction of the arrow. The first, second, and third rolls 10, 1 are arranged in this order from the entry side.
2 and 14.

The arrangement of the control device is reversed in FIG.
First, second and third motors M1, M2 for independently driving the second and third rolls 10, 12, 14 respectively.
2 and M3 are the first, second and third automatic current regulators (A
CR: Automatic Current Regulator) 30, 3
The field currents are adjusted by 1, 34, and the respective rotational driving forces are controlled.

The control device shown in FIG. 4 includes a load sharing calculator 22 for calculating a load balance ratio for each of the rolls 10, 12, and 14, based on a principle described later. The control device controls the loads on the first and third rolls 10 and 14 with reference to the second roll 12, and the first to third rolls are controlled by an ASR (automatic speed controller) (not shown). Total current command I _REF for roll
Is determined, the ratio of the current flowing through the first to third rolls is calculated by the load sharing calculator 36, and the field currents of the first and third rolls are controlled so as to achieve the ratio. It is supposed to. For this reason, in the computing unit 36, as shown, the M1 main circuit field current command: I1 _REF corresponding to the load shared by the first motor M1 and the third motor M3
M3 main circuit field current command corresponding to the load to be shared by:
I3 _REF is calculated.

The I1 _REF calculated by the load sharing calculator 36 is input to a subtractor 38, where a deviation from the M1 main circuit feedback current for the first motor: I1 _FB is calculated, and the deviation is calculated. The current is input to the integration (PI) controller 40, and a correction current for the first motor control according to the deviation is calculated. Thereafter, a correction current corresponding to the deviation is added to the M1 field current command: If1 _REF for the first motor by the adder 42, and the added value is output to the first automatic current controller 30, and The driving of one motor M1 is controlled.

On the other hand, the I3 _REF calculated by the load sharing calculator 36 is input to the subtractor 44, and when the deviation from the M3 main circuit feedback current: I3 _FB for the third motor is calculated, This is input to a proportional-integral (PI) controller 46, and a correction current for the third motor control according to the deviation is calculated. After that, the correction current according to the deviation is
In the adder 48, the M3 field current command for the third motor: If3
_REF , and the added value is output to the third automatic current regulator 34 to control the driving of the third motor M3.

In the load balance control, in the load sharing computing unit 36, the bridle roll A
Based on the strip tension values on the entrance side and the exit side of the bridle roll, a critical friction coefficient that is a limit at which slip occurs between the entire bridle roll and the strip is calculated, and the bridle roll is formed from the critical friction coefficient. A load balance ratio for each roll to be performed is determined, and an operation for controlling each motor is performed based on the load balance ratio.

First, the principle of the control calculation will be described. The first to third three rolls 10, 12, and 14 shown in FIG.
When the strip S is being conveyed by the bridle roll A, the tension on the entrance side and the exit side of the bridle roll A are T1 and T2, respectively, and the friction coefficient of both is μ,
Assume that the winding angle is θ.

For example, as described on pages 3 to 39 of the Mechanical Engineering Handbook (revised 6) published by the Japan Society of Mechanical Engineers, if Euler's formula satisfies the following equation (1), slip is established. Does not occur.

Exp {μ (θ 1 + θ 2 + θ 3)}> T 2 / T 1 (1) In this expression (1), exp (μ
θ)> T2 / T1 (assuming that T2> T1), it can be derived by applying the above Euler's formula to the three rolls shown in FIG.

That is, the following equations (2) to (4) are obtained from Euler's formula for each of the first to third rolls.
However, as also shown in FIG. 3, T12 is between the first roll and the second roll.
T23 represents the tension between the rolls, and T23 represents the tension between the second to third rolls. Θ1, θ2, θ3 are the first, second,
Strip S on each third roll 10, 12, 14
Is the winding angle.

Exp (μθ1)> T12 / T1 (2) exp (μθ2)> T23 / T12 (3) exp (μθ3)> T2 / T23 (4) In these equations (2) to (4), Since both the left and right sides are positive numbers, the following equation (5) holds for the product of these equations. That is, equation (1) is obtained from equation (5).

Exp (μθ1) · exp (μθ2) · exp (μθ3)> (T12 / T1) · (T23 / T12) · (T2 / T23) (5) Further, here, the following equation (6) is used. Is defined as the critical friction coefficient, where μ 'is satisfied.

Exp {μ ′ (θ 1 + θ 2 + θ 3)} = T 2 / T 1 (6) In this equation, the critical friction coefficient μ ′ is the entirety of the strip S and the bridle roll A, that is, the first, second, The coefficient of friction is a limit at which slippage occurs between the third rolls 10, 12, and 14.

In this case, the load sharing between the rolls is determined so that the relations of the following equations (7) to (9) are satisfied for the first to third rolls.

First roll exp (μ'θ1) = T12 / T1 (7) Second roll exp (μ'θ2) = T23 / T12 (8) Third roll exp (μ'θ3) = T2 / T23 … (9)

Assuming that the maximum static friction coefficient between the roll and the strip is μ ″, the case where the relationship of the following equations (10) to (12) holds for each roll is the slip limit.

First roll exp (μ ″ θ1) = T12 / T1 (10) Second roll exp (μ ″ θ2) = T23 / T12 (11) Third roll exp (μ ″ θ3) = T2 / T23 … (12)

Accordingly, the friction margins of the first to third rolls are all (μ ″ −μ ′), and it is possible to balance the friction margins of the rolls.

On the other hand, based on the value of the critical friction coefficient μ ′ given by the above-mentioned equation (6), the ratio of the torques τ 1, τ 2, τ 3 to be shared by the first, second, and third rolls is given by (13) can be calculated.

Τ1: τ2: τ3 = exp (μ′θ1) −1: exp (μ′θ1) {exp (μ′θ2) −1}: exp (μ′θ1) exp (μ′θ2) ｛exp ( μ'θ3) -1｝ (13)

The first, second and third rolls 10, 1
The winding angles θ1, θ2, θ of the strip S at 2 and 14
Since 3 is a fixed value, the front-rear tension ratio T2 obtained from the input and output tension values actually measured by the tension meters 18 and 20 is used.
Once / T1 is known, it is possible to determine the critical friction coefficient .mu. 'By substituting it into the above equation (6). As a result, the first, second and third coefficients can be determined from the above equation (13). Load balance ratio τ for each roll 10, 12, 14
1: τ2: τ3 can also be determined.

Here, a method of deriving the above equation (13) will be described. As described above, since the torques of the first to third rolls are set, the following equations (14) to (16) are obtained from the above equations (7) to (9).

T12 = T1exp (μ′θ1) (14) T23 = T12exp (μ′θ2) (15) T2 = T23exp (μ′θ3) (16)

Here, since the torque to be generated by the motor driving each roll is given by the following equations (17) to (19), the above equation (13) is obtained.

Τ1 = T12−T1 = T1 {exp (μ′θ1) −1} (17) τ2 = T23−T12 = T12 {exp (μ′θ2) −1} = T1exp (μ′θ1)} exp (μ'θ2) -12 (18) τ3 = T2 -T23 = T23 {exp (μ'θ3) -1} = T12exp (μ'θ2) {exp (μ'θ3) -1} = T1 exp (Μ′θ1) exp (μ′θ2) × {exp (μ′θ3) −1} (19)

Therefore, the load sharing calculator 36 uses the load balance ratio for the first, second, and third rolls 10, 12, and 14 obtained by the above equation (13).
The computing unit 36 controls each of the motors M1, M2 so that a load corresponding to the ratio is shared between the rolls 10, 12, and 14.
2. Reflect it on the control signal output to M3.

That is, as described above, the total current for each of the first to third rolls is determined as the current command I _REF from the viewpoint of speed control. Then, in order to balance the load between the rolls, I _REF is applied to each of the motors driving the first to third rolls by using the following equations (19) to (21) based on the ratio of the above equation (13). Set.

I1 _REF = I _REF × {τ 1 / (τ 1 + τ 2 + τ 3)} = I _REF × {exp (μ′θ 1) −1} {[exp {μ ′ (θ 1 + θ 2 + θ 3)} − 1] (20) ) I2 _REF = I _REF × {τ 2 / (τ 1 + τ 2 + τ 3)} = I _REF × exp (μ′θ 1) ｛exp (μ′θ 2) −1} {[exp ｛μ ′ (θ 1 + θ 2 + θ 3)} − 1 ] (21) I3 _REF = I _REF × {τ 3 / (τ 1 + τ 2 + τ 3)} = I _REF × exp (μ′θ 1) exp (μ′θ 2) × {exp (μ′θ 3) −1} {exp {Μ '(θ1 + θ2 + θ3)}-1] (22)

According to the above-described load balance control, the load sharing calculator 36 calculates the load balance ratio, and the magnetic fields of the motors M1, M2, M3 that drive the respective rolls based on a command reflecting the ratio. Since the current is controlled, each roll 1 of the bridle roll A has
The friction margins at 0, 12, and 14 can be balanced, and appropriate load balance control can be performed.

In this embodiment, the load balance control described in detail above is performed, and the following tension control is performed.

That is, as described above, the first, second, and third rolls 10, 12, which the bridle roll A shown in FIG.
14, the pulse generators PLG1, PLG
2, the strip S is measured based on the pulse signal from the PLG3, and the difference between the measured peripheral speed of each roll and the transport speed of the strip S similarly measured based on the signal from the pulse generator PLG4. And the occurrence of slip between the above-mentioned rolls 10, 12, and 14.

When the occurrence of slip is detected in any one of the three rolls 10, 12, and 14, the line control device 22 sets the entrance tension T1 and the exit tension measured at the detection timing. T2 is input, and the friction coefficient μ at that time is estimated by the following equation (23) having the same form as the above equation (6).

Exp {μ (θ1 + θ2 + θ3)} = T2 / T1 (23)

The relationship between the expressions (23) and (6) will be described. The two expressions are synonymous, but the expression (6) is
While the equation holds when performing the balance control based on the above equations (7) to (8), the equation (2)
In equation (3), the occurrence of slip when control is performed assuming that equation (6) is satisfied means that the actual friction coefficient μ becomes smaller than the limit friction coefficient μ ′ determined by equation (6). It can be estimated that the actual μ is
, T1.

The calculation for estimating the friction coefficient μ is executed every time the occurrence of slip is detected. Each estimated value is inputted to the tension set value calculating device 24, and learning for sequentially updating to a new estimated value is performed. .

Every time learning is performed by the arithmetic unit 24,
The learning value mu _L of the frictional coefficient, by substituting the mu of the formula (1), the entry side of the bridle roll A which satisfies the relationship of this equation, each tension setting value T1, T2 of the outlet side was determined ,
By outputting it to the line control device 22,
The motor 22 controls the motor drive controller 26 so that each of the motors M1 and M
2. Instruct to control the torque of M3.

As described above, in the present embodiment,
By performing load balance control to balance the friction margin of each roll of the bridle roll A, the exact friction between the bridle roll A and the material is determined from the tension ratio between the entrance side and the exit side of the bridle roll A when slippage is detected. The coefficient can be estimated.

That is, in the bridle roll A shown in FIG. 3, only the tensions T1 and T2 on the entrance side and the exit side can be observed.
, T2 alone cannot be used to estimate the coefficient of friction between the roll and the plate. This is because if the balance control is not performed on the load sharing of the first, second, and third rolls 10, 12, 14, the tension T12 between the rolls
This is because the coefficient of friction between each roll and the strip S cannot be estimated unless T23 is also observed. (This is because the friction margin of each roll is not constant (unbalanced)
This is because only one specific roll slips and the other rolls do not slip. )

However, by applying the balance control as in the present embodiment, the friction margin of each roll is constant (balanced). Therefore, when a slip occurs, the first, second, and third slips occur. Slip occurs simultaneously on three rolls. Therefore, by observing only the entrance and exit tensions T1 and T2, the friction coefficient between the roll and the plate can be accurately estimated.

Further, in the present embodiment, the estimated friction coefficient is learned, and the longitudinal tension of the bridle roll is set by using the learned value, thereby making it possible to prevent slippage in the bridle roll.

FIG. 5 shows a specific control result according to the present embodiment. From FIG. 5 (A), it can be understood that the learning value of the friction coefficient fluctuates at the beginning of the control, but approaches the true friction coefficient value as the learning progresses, and becomes stable. Also, from FIG. 7B, it can be seen that as the learning progresses, the number of occurrences of the slip decreases, and the slip can be prevented.

As described in detail above, according to the present embodiment,
By performing the load balance control of the bridle roll, the friction coefficient between the roll and the material can be accurately estimated. Further, by learning the estimated friction coefficient and setting the tension before and after the bridle roll using the learned value, slip of the bridle roll can be prevented.

Although the present invention has been specifically described above, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.

For example, although the case where the bridle roll is composed of three rolls has been described, the present invention is not limited to this.

[0069]

As described above, according to the present invention,
By being able to accurately estimate the coefficient of friction, it is possible to reliably prevent slippage occurring between the bridle roll and the strip.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a main part of a strip transport line applied to one embodiment.

FIG. 2 is a block diagram showing a schematic configuration of a bridle roll control system.

FIG. 3 is an explanatory diagram showing a relationship between a bridle roll and tension.

FIG. 4 is a block diagram showing a schematic configuration of a load balance control device.

FIG. 5 is a diagram showing the effect of the present invention.

[Explanation of symbols]

 A ... Bridle roll S ... Strip 10 ... First roll 12 ... Second roll 14 ... Third roll 16 ... Speed measuring roll 18 ... Incoming tensiometer 20 ... Outgoing tensiometer 22 ... Line controller 24 ... Tension setting calculator Reference numeral 26: motor drive control device 30: first automatic current regulator 32: second automatic current regulator 34: third automatic current regulator 36: load sharing calculator 38, 44 ... subtractor 40, 46 ... proportional integral controller 42, 48 ... Adder

Claims (2)

[Claims] 1. A bridle roll tension control method for controlling the tension of a strip in a bridle roll having a plurality of rolls, wherein the entire bridle roll is controlled based on a strip tension value on each of an entrance side and an exit side of the bridle roll. Calculate a limit friction coefficient which is a limit at which a slip occurs between the strip and the strip, determine a load balance ratio for each roll constituting the bridle roll from the limit friction coefficient, and determine the load balance ratio based on the load balance ratio. In addition to performing load balance control for controlling the load on the roll, if slippage is detected from the peripheral speed of each roll measured during operation, the slip tension is detected based on the strip tension values on the entrance and exit sides of the bridle roll. To estimate the coefficient of friction when slippage occurs, and Determining a tension value to be set for each of the entrance side and the exit side of the bridle roll, and correcting the tension value. 2. The method according to claim 1, wherein the friction coefficient estimated when a slip occurs is sequentially learned,
A tension control method for a bridle roll, wherein the tension value to be set is determined using a friction coefficient learning value.