JPH0288720A - Method for controlling tension of metal strip - Google Patents

Abstract

PURPOSE:To prevent tension variation of a metal strip even during shifting a cooling roll by controlling driving motors for cooling rolls based on the detected tension and current. CONSTITUTION:The driving motor is controlled by prevent the tension variation of the metal strip S based on the tension of the metal strip S at inlet and outlet sides of the cooling rolls 1A-1D and the currents of the driving motors 5A-5D for revolutionally driving the cooling rolls 1A-1D, so that the tensions of the metal strip S at inlet and outlet sides of the cooling rolls 1A-1D are equalized and load balance of the driving motors 5A-5D for the cooling rolls 1A-1D coming into contact with the metal strip S in obtd. Therefore, as the tension of the metal strip S at inlet and outlet sides of the cooling rolls 1A-1D is controlled, by elimination non-control condition of the strip S at the inlet side thereof and obtaining the tension balance of the metal strip S between the cooling rolls 1A-1D, the tension variation is prevented to all over before, during and after the cooling roll, and passing condition of the strip is held to good.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling the tension of a metal strip, and in particular, to a method for controlling the tension of a metal strip in a continuous annealing furnace.
The present invention relates to an improvement in a tension control method for a metal strip, which is suitable for use when cooling a metal strip while applying tension while winding it around a plurality of cooling rolls and bridle rolls provided on the inlet and outlet sides thereof.

[Conventional technology]

In continuous annealing lines for metal strip, etc., cooling rolls are widely used to rapidly cool the heated metal strip. This cooling roll circulates a cooling liquid inside a hollow roll, and the strip is wound around the roll while the roll is rotated for cooling. Various technologies have been proposed for such cooling rolls (Japanese Patent Laid-Open No. 54-118315, Japanese Patent Laid-open No. 57-20712).
6, Japanese Patent Publication No. 58-96824, etc.). Here, a conventional example of a cooling roll section provided with a cooling roll in a continuous annealing furnace is shown in FIG. 2, and an example of tension control of the metal strip in this cooling roll section will be explained next. As shown in , the cooling rolls are provided with cooling rolls IA to ID for cooling the metal strip S, and on the inlet and outlet sides of these cooling rolls IA to ID,
An entry bridle roll 2E and an exit bridle roll 2D are provided to control the speed and tension of the metal strip S. In addition, the reference numeral 3 in FIG. 2 is a deflector roll, and 14D is a tension meter provided between the outlet side of the cooling roll groups IA to ID and the outlet side bridle roll 2D to detect the tension of the metal strip S there. It's a roll. A metal strip S such as a steel strip is heated and soaked in the heating zone/soaking zone in the previous stage, and then conveyed in the direction of the arrow, wound around the cooling rolls IA to ID, and rapidly cooled to a predetermined temperature. , and sent to the cooling zone in the subsequent stage. Reference numerals 4A to 4D in FIG. 2 are cylinders that move the cooling rolls IA to 1D forward and backward, and the cylinders 4A to 4D are
By moving the cooling rolls IA to ID back and forth with respect to the strip S, the metal strip S is aligned with the cooling roll I.
Control the strip temperature by changing the length of the strip wrapped around A to ID. In addition, symbols 5A to 5D in FIG. 2 are cooling rolls IA to ID.
It is a drive motor that rotates the The rotational drive motors 58 to 5D control the rotational speed v1 to v of each cooling roll IA to ID.
Each current controller (ACR) 7A to 7D and each speed controller (ASR) 9
Controlled by A to 9D. Furthermore, reference numeral 11 in FIG. 2 is a speed corrector that corrects the speed at which the cooling rolls IA to ID move. This speed corrector 11 includes a position detector 13A such as a magnetic scale.
~ Cooling roll I detected and output by 13D
Position detection signals P1 to P4 of A to ID, and rotational speed signals v1 to cooling rolls IA to ID detected by a speed detector such as a pulse generator (PLG) not shown.
V4 is being input. The length of the metal strip S between each of the cooling rolls IA to ID changes with the movement of the cooling rolls IA to ID. ~Based on v4,
The temporal change in length (dL/dt) is calculated and added to the speed command Vref to the speed controllers 9A to 9D via addition points 20A to 20D to correct the speed. In addition, when performing feedback control of the rotational speeds v1 to v4 in this manner, in order to prevent an adverse effect on the subsequent rolls,
An input signal to a certain speed controller (for example, 9A) is simultaneously input in cascade to a subsequent speed controller (for example, 9B) via addition points 20A to 20D. On the other hand, the entry side bridle roll 2E is provided with a drive motor 6E for rotating it, and the exit side bridle roll 2D is provided with a drive motor 6D for rotating it. , entry side bridle roll 2E
is mainly used as a speed control mask to control the passing speed of the metal strip S, and the exit bridle roll 2D is mainly used as a tension control mask to apply a predetermined tension to the metal strip S. That is, in the entrance bridle roll 2E, the drive motor 6E is controlled by the speed controller 10E and the current controller 8E so that the roll speed matches the speed command value vre. In addition, in the exit bridle roll 2D, the input signal to the speed controller 9D of the cooling roll 4D is cascade inputted via the addition point 21, and the input signal is input to the speed controller 1.
0D, the speed of the drive motor 6D is controlled by the current controller 8D, but in addition to this, the tension controller (AT
R) The signals from 12D are input to the speed controller 10D via the summing point 21 and added. In addition, the strip tension at the outlet side of the cooling roll ID is detected by the tension meter roll 14D, and is added to the addition point 22.
It is fed back to the tension controller 12D via. However, in the conventional cooling roll section, the tension of the metal strip S is simply feedback-controlled based on the actual tension of the metal strip S on the exit side of the cooling roll ID, as described above. I
The tension in the metal strip S on the input side of A is equivalent to an uncontrolled state.6 In particular, during the movement of the cooling rolls IA to ID, there is a possibility that a tension difference will occur between the metal strips on the input side and the output side. In addition, in the cooling roll section, since the load balance between the drive motors 5A to 5D that drive the cooling rolls IA to ID that are in contact with the metal strip S is not maintained, the load is not balanced during the movement of the cooling rolls IA to ID. , each cooling roll IA
There was a high possibility that the tension balance of the strip S between ID and ID would be lost. Therefore, in the conventional cooling roll section, the cooling roll I
When the amount of movement of A to ID is small or the cooling rolls IA to I
If D is moved slowly, the tension fluctuation of the metal strip S is small and it is not a big problem, or if the cooling rolls IA to ID are moved or released rapidly,
When the cooling rolls IA to ID are released from the metal strip S, tension fluctuations occur, making it difficult to control the tension to a target value. In particular, when all the cooling rolls IA to ID are rapidly released at once, a very large tension fluctuation occurs, which may cause problems such as meandering and throttling of the metal strip S.

Problem to be Solved by the Invention 1 The present invention has been made in view of the above-mentioned conventional problems, and provides strip tension control that can reliably prevent tension fluctuations in the metal strip even while the cooling roll is moving. The task is to provide a method. [Means for Achieving the Object] The present invention provides a strip tension control method in which tension is applied to a metal strip while winding it around a plurality of cooling rolls and bridle rolls provided on the entrance and exit sides of the metal strip. When cooling the cooling roll, detecting the tension of the metal strip at the entrance and exit sides of the cooling roll, and detecting the current of a drive motor that rotationally drives the cooling roll,
Based on the detected tension and current, so that the tension of the metal strip at the entrance and exit sides of the cooling roll is the same, and the load of the drive motor of the cooling roll in contact with the metal strip is balanced, The above object has been achieved by controlling the drive motor of the cooling roll and preventing tension fluctuations in the metal strip.

[Operation and effects of the invention]

In the present invention, in the method for controlling the tension of a metal strip, the tension of the metal strip on the entrance side and the exit side of the cooling roll is the same, and the load balance of the drive motor of the cooling roll that is in contact with the metal strip is adjusted. The drive motor is controlled based on the tension of the metal strip on the output side of the cooling roll and the current of the drive motor that rotationally drives the cooling roll so that the tension of the metal strip is prevented from changing. There is. Therefore, since the tension of the metal strip on the entrance and exit sides of the cooling roll is controlled, there is no uncontrolled state of the strip on the entrance side, and the tension of the metal strip between the cooling rolls is balanced. In front of the cooling roll, not only during operation but also while the cooling roll is moving.
It is possible to prevent tension fluctuations throughout the middle and back metal parts, and maintain good threading conditions. Also, while the cooling roll is moving,
Since the load of the drive motors of the cooling rolls in contact with the metal strip is balanced, the tension of the metal strip between the cooling rolls is balanced and fluctuations in the tension of the strip can be prevented. Furthermore, when the cooling rolls are released, the tension of the metal strips is balanced between the cooling rolls until just before they are released, so even if the cooling rolls are suddenly released, there will be no large tension fluctuations, and no meandering or meandering of the metal strips will occur. Aperture, etc. can be suppressed. Therefore, it is possible to improve the operating rate, yield, etc. of process equipment (for example, a continuous annealing furnace) in which the cooling roll is used. Furthermore, if the drive motor of the bridle roll is controlled together with the drive motor of the cooling roll so that the tension before and after the cooling roll is the same, a further effect of preventing tension fluctuation can be obtained.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. This embodiment is a cooling roll section, as shown in FIG. 1, which is continuously provided in a continuous annealing furnace similar to that shown in FIG. 2 above. In FIG. 1, the reference numeral 14E indicates the cooling roll IA~
A tension meter roll 15 is provided on the input side of the ID for detecting the tension of the metal strip S, and 15 is a load balance control for balancing the load between the drive motors of the cooling rolls that are in contact with the metal strip S. vessel, 1
6 is a tension controller (ATR) for making the strip tension before and after the cooling rolls IA to ID the same. The rest of the configuration of the apparatus of this embodiment is the same as that of the conventional cooling roll section shown in FIG. In the cooling roll section according to the embodiment, the position detector 13
Position detection signals P1 to P4 of each of the cooling rolls IA to ID, which are detected and output by A to 13D, are input to the load balance controller 15. The load balance controller 15 determines whether each of the cooling rolls IA to ID is in contact with the metal strip S based on the input position detection signals P1 to P4. On the other hand, the drive motors 58 to 5D for each of the cooling rolls IA to ID
The actual current flowing through the load balance controller 15 is detected, and the detected current signal is fed back to the load balance controller 15. The load balance controller 15 uses these fed-back current signals to generate a correction signal so as to balance the load only between the drive motors of the cooling rolls that are in contact with the metal strip S determined as described above. Output to each speed controller 9A to 9D. In this case, the load balance may be equally distributed or may be a predetermined distribution determined from the positional relationship between each roll and the metal strip. The tension controller 16 also includes tension meter rolls 14B and 1 provided on the front and rear sides of the cooling rolls IA to ID.
A signal representing the difference in tension values detected by the 4D is input from the addition point 23. The tension controller 16 uses addition points 24.20A to 20 to correct the speed commands of the cooling rolls IA to ID so that the input tension signals are equal.
A correction signal is applied to each speed controller 9A-9D via D. Further, this correction signal becomes a cascade signal and is input to the speed controller 10D of the exit bridle roll 2D. Therefore, while the cooling rolls IA to ID are moving, the tension is balanced not only between each of the cooling rolls IA to ID but also before and after the cooling rolls, so tension fluctuations do not occur and the tension of the entire cooling roll section is adjusted to the target tension T r e Control f to be constant. In addition, even if the cooling rolls IA to ID are suddenly released, the tension is balanced by the cooling rolls IA to ID until just before they are released.
Sudden tension fluctuations in the metal strip S can be prevented. In the above embodiment, the entrance bridle roll 2
Although the speed of the metal strip S was controlled by E, the speed can also be controlled by the exit bridle roll 2D.

[Brief explanation of the drawing]

FIG. 1 is a block diagram including a partial layout diagram showing the overall configuration of a cooling roll unit according to an embodiment of the present invention; FIG. 2 is a block diagram showing the overall configuration of a conventional cooling roll unit;
FIG. 2 is a block diagram including a partial layout. S...Metal strip, ■A~ID...Cooling roll, 2E, 2D...Bridle roll on entry and exit sides, 4A
~4D...Cylinder, 5A~5D...Cooling roll drive motor, 7A~7D
...Current controller (ACR), 8E, 8D...Inlet side,
Current controller on the output side, 9A to 9D...Speed controller (AS
R), 10E, IOC...input side, exit side speed controller,
11... Speed corrector, 12D... Tension controller (ATR), 13A to 13D... Position detector, 14E, 14D... Tension meter roll, 15.
...Load balance controller, 16...Tension controller that balances the strip tension before and after the cooling roll, Vref...Speed command, T'rer...Tension command.

Claims (1)

[Claims] (1) When cooling a metal strip while applying tension while winding it around a plurality of cooling rolls and bridle rolls provided on the entrance and exit sides thereof, The tension of the metal strip is detected, and the current of the drive motor that rotationally drives the cooling roll is detected, and the tension of the metal strip on the entrance and exit sides of the cooling roll is the same, and
controlling the drive motor of the cooling roll in contact with the metal strip based on the detected tension and current so that the load of the drive motor of the cooling roll in contact with the metal strip is balanced, and preventing tension fluctuations in the metal strip; A method for controlling tension in a metal strip, characterized in that: