JP2778809B2 - How to prevent strip slip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a method for preventing a strip from slipping on a roll that maintains the conveyance of the strip by performing a roll peripheral speed control using a preset roll diameter value, disposed between two bridle rolls, The present invention relates to an improvement in which the roll peripheral speed is accurately controlled and slip is prevented even in a case where a roll diameter of a helper roll is reduced due to wear.

[Prior art]

For example, in a horizontal continuous processing line for strips in which the strip is conveyed while maintaining the tension in the strip by two bridle rolls such as an inlet bridle roll and an outlet bridle roll, the strip between the two bridle rolls A helper roll is placed between these two bridle rolls in order to maintain the transport. FIG. 5 shows a horizontal continuous processing line for strips.
It is an arrangement drawing of a helper roll. In FIG. 5, the strip 1 carried in from the right sequentially passes through a tension bridle roll TBR, a helper roll 10, and a master bridle roll MBR. The master bridle roll MBR controls the strip speed in the horizontal continuous processing line to be constant. The tension bridle roll TBR controls the strip tension in the horizontal continuous processing line by controlling the rotation speed slightly lower than the rotation speed of the master bridle roll MBR. That is, the lower the rotation speed of the tension bridle roll TBR, which is slightly lower than the rotation speed of the master bridle roll MBR, the greater the strip tension in this horizontal continuous processing line. Helper roll 10 placed between these tension bridle rolls TBR and master bridle roll MBR
Is for supporting the main transport torque by these two bridle rolls by the driving force of the helper roll 10 and the frictional force between the helper roll 10 and the strip 1 to maintain the transport of the strip. Yes (or to keep the strip in a state where catenary transport is not possible). FIG. 6 is a diagram showing the transport of the strip 1 by the frictional force of the helper roll 10. In FIG. 6, the strip 1 carried in from the right is in contact with the helper roll 10 at a winding angle θ radians. Here, the back tension in this helper roll 10 is F ₁
Assuming that the forward tension is F ₂ and the friction coefficient between the helper roll 10 and the strip 1 is μ, the condition for preventing the slip between the helper roll 10 and the strip 1 is as follows: become. ^{_{F 2 / F 1 <e μθ}} ( where F _2> when the _{F 1) ... (1a) F} 1 / F 2 <e μθ ( provided that when the _{F 2 <F 1) ... (} 1b) Thus, helper rolls in the 10 roll rotation control of the rear tension F ₁ and the front tension F ₂ is the (1a), (1b)
You must satisfy the condition of the expression. Thereby, it is possible to maintain the conveyance of the strip between the two bridle rolls as described above while preventing the slip. Conventionally, as such roll peripheral speed control of the helper roll 10, first, a preset strip speed V, a roll diameter D of the helper roll 10, a reduction ratio i between the electric motor and the helper roll 10, and the following formula: The rotation speed of the drive motor
Determine the N _{M. N M = V / πDi = K} × V ... (2) ( where the constant K 1 / πDi) to the rotational speed N _M of the thus determined drive motor target rotational speed (command rotational speed), droop characteristic The roll peripheral speed of the helper roll 10 is made equal to the strip speed by a feedback rotation speed control having a DC motor or a rotation speed control using a drooping characteristic of the DC motor itself (or, The speed difference is kept within a predetermined value) to prevent a slip from occurring. In Japanese Patent Publication No. 57-25465, the running speed of the strip is detected by detecting the Doppler frequency of the electromagnetic wave applied to the strip, and the detected running speed of the strip is compared with the rotational speed of the roll previously input. , A slip amount is determined by comparing the slip amount, and the speed of the roll drive motor is controlled based on the slip amount.

[Problems to be solved by the invention]

However, as described above, using the strip speed V set in advance, the roll diameter D of the helper roll 10, the reduction ratio i between the electric motor and the helper roll 10, and the roll circumference, the formula (2) is used. In the method of performing the speed control, if the error between the previously determined roll diameter D of the helper roll 10 and the actual roll diameter of the helper roll 10 increases, the peripheral speed, the strip speed, and the peripheral speed of the helper roll 10 become larger. Will not match. That is, the deviation between the peripheral speed of the helper roll 10 and the strip speed increases. If the deviation between the peripheral speed of the helper roll 10 and the strip speed becomes too large in this way, it becomes larger than the range that can be covered by the droop characteristic of the feedback control and the drooping characteristic of the DC motor as described above.
Slip occurs between 10 and strip 1.
That is, when the absolute value of the error between the previously determined roll diameter D of the helper roll 10 and the actual roll diameter of the helper roll 10 exceeds a certain value, the gap between the helper roll 10 and the strip 1 becomes larger. There is a problem that slip occurs. For example, in a horizontal continuous processing line in which such a helper roll 10 is used, at the start of operation, the roll diameter of the helper roll 10 is accurately measured, and thereby the roll diameter D of the aforementioned helper roll 10 is determined. By doing so, it is needless to say that the slip between the helper roll 10 and the strip 1 can be prevented at the start of the operation. However, when the helper roll 10 is used continuously for a long time, the diameter of the helper roll 10 decreases due to wear of the contact surface of the helper roll 10 with the strip 1. In particular, in the case of asbestos rolls and the like, the contact surface of the asbestos roll (helper roll) with the strip is significantly worn, and therefore the degree of reduction in the helper roll roll diameter is also severe. When the roll diameter decreases due to such wear of the helper roll, the error between the previously determined roll diameter of the helper roll and the actual roll diameter of the helper roll becomes equal to or more than a certain value. It cannot be covered by the droop characteristic of the feedback control or the drooping characteristic of the DC motor, and a slip occurs between the surface of the helper roll and the strip. Note that such a change in the roll diameter of the helper roll from the start of operation is not limited to a decrease in the roll diameter due to wear of the helper roll. When the horizontal continuous processing line is started, the helper roll is heated and thermally expanded by the hot strip that is passed through, and the roll diameter of the helper roll may increase. Even in such a case, if the roll diameter of the helper roll is excessively increased, a slip occurs between the surface of the helper roll and the strip. Similarly, in Japanese Patent Publication No. 57-25465, the peripheral speed of a roll is calculated (estimated) from the rotation speed of the roll and the previously determined roll diameter of the roll. . Therefore, when the roll diameter of this roll is reduced by abrasion or increased by thermal expansion, there is a problem that slip occurs between the roll and the strip. Supposing that the technology of Japanese Patent Publication No. 57-25465 is developed, the surface of a rotating roll is also irradiated with electromagnetic waves, and the Doppler frequency due to this is detected to accurately detect the peripheral speed of this roll. it can. However, in this case, there is a problem that newly installed devices such as an electromagnetic wave oscillation source and a device for detecting Doppler frequency are complicated and very expensive. The present invention has been made in order to solve the above-mentioned conventional problems. In a roll such as a helper roll which performs roll peripheral speed control using a preset roll diameter value, a device having a relatively simple structure is provided. By using only the roll diameter of the roll, even if the roll diameter is reduced by abrasion or increased by thermal expansion, the peripheral speed of the roll is exactly adapted to the strip speed of the strip being conveyed, whereby It is an object of the present invention to provide a method for preventing a slip of a strip, which can improve the stability of the transport of the strip and prevent the occurrence of slip between the roll and the strip, thereby also preventing the slip flaw on the strip surface. And

[Means for achieving the object]

The present invention is arranged between two bridle rolls, and by controlling the roll peripheral speed by using a preset roll diameter value, a method for preventing a strip from slipping on a roll for maintaining the transport of the strip, Detecting a strip transport torque, estimating a relationship between a roll peripheral speed of the roll and a strip speed of a strip being transported from the strip transport torque, correcting the roll diameter value, and correcting the corrected roll diameter value. The above object has been achieved by controlling the peripheral speed of the roll using

[Action]

The present invention is a roll peripheral speed of a roll such as a helper roll,
It is noted that the speed difference between the strip speed of the strip conveyed by the roll and the strip tension acting on the strip is substantially proportional. That is, detecting the strip tension of the strip, detecting the deviation of the peripheral speed of the roll from the target peripheral speed, and correcting the roll diameter value used for the roll peripheral speed control. In the present invention, the strip tension of the strip is determined by detecting the strip tension from the strip transport torque. FIG. 4 shows the speed difference between the peripheral speeds of the two helper rolls 10,
It is explanatory drawing about the relationship with the tension between rolls between these two helper rolls. In FIG. 4, the strip 1 is carried in from the right side, and sequentially passes through the helper roll 10a and the helper roll 10b. The distance between these two helper rolls 10a and 10b is L, and the inter-roll tension is F. In FIG. 4, the tension F between the rolls is such that the Young's modulus is E.
, And the cross-sectional area of one strip is A, and the helper roll 10a
Roll peripheral speed was between V _1, a roll peripheral speed of the helper rolls 10b and V _2, when the d / dt and S, can be expressed by the following equation. F = [(EA / V ₁ ) / {1+ (L / V ₁ ) S}] × (V ₂ −V ₁ ) (3) As is apparent from the equation (3), the tension F between the rolls is obtained.
The two helper rolls 10a, is proportional to the speed difference between roll peripheral speeds of 10b (V ₂ -V _1). Here, in a roll such as one helper roll, the strip speed at the one roll position is set to one of the roll peripheral speeds V ₁ and V ₂ of the two helper rolls 10a and 10b in FIG. Assuming that it corresponds to the roll peripheral speed,
The forward tension or rearward tension of this one roll (reverse to the strip speed, the peripheral speed of the one roll becomes the rearward tension if it is fast, and the frontal tension if it is slower) It is clear that this is proportional to the speed difference between the strip speed and the peripheral speed of this one roll. Therefore, for example, it is assumed that the motor torque of the motor driving the roll is detected, and the strip transfer torque of the strip is obtained from the motor torque. that way,
For example, a strip tension is determined from the strip transport torque, a speed difference between the roll peripheral speed of the roll and the strip speed of the strip being transported is determined from the strip tension, and the speed difference and the strip speed are determined from the speed difference. The deviation of the roll peripheral speed of the roll can be detected (there is another method of calculating the deviation of the roll peripheral speed from the strip transfer torque using a preset data table). At this time, when the actual rotation speed of the roll matches the target rotation speed, the roll peripheral speed of the roll matches (or corresponds to) the strip speed of the strip. Should be. Therefore, the deviation of the roll peripheral speed is due to the deviation of the roll diameter value. That is, the roll diameter value of the roll can be corrected from the deviation of the roll peripheral speed. In addition, the strip slip prevention method of the present invention is not limited to the helper roll in the horizontal continuous processing line. That is, it is a roll that rotates in contact with the strip being passed, and the rotation control of this roll may be a roll peripheral speed that uses a preset roll diameter value of this roll. The anti-slip function and effect can be obtained. Further, the present invention does not limit how to obtain the strip transfer torque.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment to which the present invention is applied. In FIG. 1, the strip 1 is carried in from the right side and sequentially passes through three helper rolls 10. Each of these three helper rolls 10 is provided with a drive motor 12 to which a rotation speed detector 14 is attached. Thereby, the roll peripheral speed of each of these helper rolls 10 is set to be substantially the same as the strip speed of the strip 1 being passed (the roll peripheral speed is slightly higher than the slip top speed). 1 is maintained. These drive motors 12 and the rotation speed detector 14 attached to these drive motors 12 are connected to a motor control device 20 arranged for each helper roll. This also allows these motor control devices 20
Controls the rotation speed of each drive motor 12. Like these motor control devices 20, slip prevention devices 22 are also provided for each helper roll. These slip prevention devices 22 control the peripheral speed of the helper roll 10 in accordance with the strip speed V from a master bridle control device (not shown). In these anti-slip device 22, a helper roll rotation speed detection value N ₁ from the rotational speed detector 14 described above, the power current detector
The motor drive current detection value I from 16 is input,
Also, helper roll rotation speed command value N _C is output. Helper roll rotation speed command value N _C outputted from the slip prevention device 22, which corresponds to the rotational speed N _M of the above (2) type drive motor is input to the motor control unit 20. Accordingly, while the roll peripheral speed is controlled by the motor control device 20 and the slip prevention device 22, the occurrence of the strip 1 between the strip 1 being passed and the helper roll 10, as described later, is prevented. The control for prevention is performed. FIG. 2 is a block diagram of the slip prevention device 22 used in the embodiment of the present invention shown in FIG. In FIG. 2, the slip prevention device 22 includes a motor driving current moving average calculation unit 22a, a strip conveyance torque calculation unit 22b, a mechanical loss torque data table 22c, a roll peripheral speed calculation unit 22d, and a roll diameter value D memory. 22e, a roll diameter initial setting section 22f, and a roll diameter initial setting section 22f
And a roll peripheral speed control unit 22h. Note that the mechanical loss torque in the mechanical loss torque data table 22c is an abbreviation for mechanical loss torque, and will be described in detail in the description of the operation of the strip transport torque calculation unit 22b described later. The slip prevention device 22 includes a helper roll rotation speed detection value N _1, and the motor drive current detection value I, strip and the conveying speed V is input. In internal slip prevention device 22, the helper roll rotation speed detection value N ₁ is inputted to the mechanical loss data table 22c, the motor drive current detection value I is inputted to the motor drive current moving average calculation unit 22a, the strip The transport speed V is input to the roll peripheral speed calculator 22d. Also, output from the roll peripheral speed control device 22h helper roll rotation speed command value N _C, as described above with reference to FIG. 1, is output to the slip prevention device 22 outside, is input to the motor control unit 20 . Hereinafter, the operation of the embodiment of the present invention will be described with reference to FIG. 1 and FIG. The power current detector 16 measures the current of the power source of the drive motor 12 connected to the motor control device 20. The motor drive current detection value I output from the power current detector 16 is proportional to the torque at which the drive motor 12 rotates the helper roll 10. The motor drive current detection value I output from the power current detector 16 is input to the motor drive current moving average calculation unit 22a inside the slip prevention device 22. The motor drive current moving average calculation unit 22a calculates and outputs a moving average of the motor drive current detection value I, which is input as needed, within a predetermined time. When calculating the moving average, the motor driving current moving average calculating unit 22a determines the moving average of the input motor driving current detection value I in the time range for which the moving average is to be calculated.
The moving average is calculated after removing abnormally varied values such as the max value and the min value. The motor drive current also changes due to causes other than the change in the roll diameter of the helper roll 10 due to friction, thermal expansion, and the like. However, changes due to such other causes are changes in a relatively short time. Thus, by obtaining the moving average within the predetermined time, fluctuations in the motor drive current (those having a short fluctuation cycle) due to causes other than a change in the roll diameter of the helper roll 10 due to abrasion, thermal expansion, etc. are also eliminated. Can be. In the strip conveying torque calculating unit 22b, based on the input of the calculation in the motor driving current moving average calculation unit 22a (detected) moving average of the motor drive current detection value I, the strip conveying torque T _C (strips are conveyed 1 (Corresponding to the front tension or the rear tension of the helper roll 10). Torque generated by the electric motor that drives the helper roll 10 mainly, the strip conveying torque T _C, mechanical loss torque T _M from the motor until it is in contact to the strip 1 helper roll 10 (hereinafter, Mekarosutoruku T _M ). Therefore, the strip transport torque T _C can be obtained by previously obtaining the mechanical loss torque T _M and subtracting this from the torque of the electric motor. Here, in the drive system of the helper roll 10, the inventor has found that the mechanical loss torque T _M can be obtained in accordance with the rotation speed of the helper roll 10, as follows. FIG. 3 is a graph showing the relationship between the helper roll rotation speed detection value and the mechanical loss torque. Shown in the graph of FIG. 3, the graph of the relationship between the helper roll 10 rotational speed detection value N ₁ and Mekarosutoruku T _M,
When only the helper roll 10 is rotated by the drive motor 12 (when the helper roll 10 is rotated by the drive motor 12 without passing through the strip 1), a moving average of the motor drive current detection value I is obtained and graphed. It was done. Helper roll rotation speed detection value shown in FIG.
The inventor has confirmed that the relationship between N ₁ and the mechanical loss torque T _M is the same when the strip 1 is passed. Therefore, the mechanical loss torque obtained from this graph
Using T _M , from the moving average of the motor drive current detection value I,
Strip transfer torque can be determined. The relationship between the helper roll rotation speed detection value N ₁ and Mekarosutoruku T _M, as shown in the graph of Figure 3, the
In the present embodiment, it is stored as a map in the mechanical loss torque data table 22c. The roll peripheral speed calculating section 22d sets a preset strip 1 transport torque setting value (for transporting the strip 1 by the helper roll 10 or according to the strip transport torque input from the strip transport torque computing section 22b, or It is determined whether or not the actual roll peripheral speed of the helper roll 10 is faster or slower than the target roll peripheral speed by comparing the actual roll peripheral speed with the target roll peripheral speed. Furthermore,
If an error (deviation of the roll peripheral speed) is detected between these two peripheral speeds at this time, the roll peripheral speed calculation unit 22d determines the cause of the error by the actual roll diameter of the helper roll 10, This is based on an error from the roll diameter value D written in the roll diameter value D memory 22e, and the roll diameter value D memory 22e is rewritten and updated (to match the actual roll diameter). The roll diameter initial setting unit 22f performs data maintenance of the roll diameter D memory 22e using the roll diameter initial setting unit 22g. As described above, even if the roll diameter of the helper roll 10 changes due to wear, thermal expansion, etc., the roll diameter value D
The roll diameter value of the memory 22e can be accurately maintained corresponding to the actual roll diameter of the helper roll 10. Therefore, when the roll peripheral speed control device 22h performs the roll peripheral speed control using the roll diameter value D of the roll diameter value D memory 22e, the peripheral speed of the helper roll 10 matches the strip speed of the strip 1. Can be done. Thereby, the stability of the threading of the strip 1 can be improved and the helper roll 10 can be prevented from slipping. Further, the anti-slip device 22 according to the embodiment of the present invention.
Can use a control device or the like using a microprocessor, which has become very inexpensive in recent years. Therefore, as compared with the roll peripheral speed control method of detecting the Doppler frequency by irradiating the surface of the helper roll 10 with an electromagnetic wave and detecting the peripheral speed of the helper roll 10, the structure is simpler and the cost can be reduced. Having.

【The invention's effect】

As described above, according to the present invention, in a roll such as a helper roll that performs roll peripheral speed control using a preset roll diameter value, the roll is formed using only a relatively simple device. If the roll diameter of the roll is reduced by abrasion or increased by thermal expansion, the peripheral speed of the roll is precisely adapted to the strip speed of the strip being transported, thereby increasing the stability of strip transport. In addition to this, an excellent effect of preventing the occurrence of slip between the roll and the strip and thereby preventing the occurrence of slip flaws on the strip surface can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment to which the present invention is applied, FIG. 2 is a block diagram of a slip prevention device used in the embodiment of the present invention, and FIG. FIG. 4 is a graph showing the relationship with the mechanical loss torque. FIG. 4 is an explanatory diagram showing the relationship between the peripheral speed difference between the two helper rolls and the inter-roll tension between these helper rolls. FIG. 6 is a diagram showing the arrangement of the helper rolls in the horizontal continuous processing line. FIG. 6 is a diagram showing the transport of the strip by the frictional force of the helper rolls. 1 ... strip, 10 ... helper roll, 12 ... drive motor, 14 ... rotation speed detector, 16 ... motor drive current detector, 20 ... motor control device, 22 ... slip prevention device, 22a ... … Motor moving current moving average calculator, 22b… Strip transport torque calculator, 22c… Mechanical loss torque data table, 22d… Roll peripheral speed calculator, 22e… Roll diameter D memory, 22f… Roll diameter Initial setting section, 22h: Roll peripheral speed control device, F ₁ … Back tension, F ₂ … Forward tension, N ₁ … Detected helper roll rotation speed, N _C …… Helper roll rotation speed command value, W ...... motor drive power, I ...... motor drive current detection value, V ...... strip conveying velocity, T _C ...... strip conveying torque, T _M ...... Mekarosutoruku.

Claims (1)

(57) [Claims] 1. A method for preventing a strip from slipping in a roll which is disposed between two bridle rolls and which controls a roll peripheral speed using a preset roll diameter value to maintain the transport of the strip. The strip diameter is corrected by estimating the relationship between the roll peripheral speed of the roll and the strip speed of the strip being transported from the strip transport torque, and correcting the roll diameter value. A method of controlling a roll peripheral speed of the roll using a value.