JP2004167573A - Method for coiling hot-rolled steel strip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for coiling a hot rolled steel strip capable of stably coiling the hot rolled steel strip around a mandrel even when a slip occurs between the mandrel and the hot rolled steel strip. <P>SOLUTION: The method for coiling the hot rolled steel strip capable of stably coiling the hot rolled steel strip by the mandrel provided with a plurality of guide rolls around its circumference comprises measuring the rotating speed of the mandrel or/and the load current of a motor for driving the mandrel after the leading front of the hot rolled steel strip winds around the mandrel, detecting the occurrence of the slip between the mandrel and the hot rolled steel strip based on an increase of the rotating speed of the mandrel and/or a decrease of the load current of the motor for driving the mandrel and controlling opening and closing of the guide rolls. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for winding a hot-rolled steel strip.
[0002]
[Prior art]
In general, a hot-rolled steel strip heats a slab to a predetermined temperature in a heating furnace, and rolls the heated slab to a predetermined thickness in a rough rolling mill to form a coarse bar, and then the coarse bar comprises a plurality of rolling stands. It is manufactured by finish rolling in a finish rolling mill to form a hot-rolled steel strip having a predetermined thickness, cooling the hot-rolled steel strip on a hot run table by a cooling device, and winding it by a coiler.
[0003]
Among them, the following techniques are known for a method of winding a steel strip. That is, in the initial stage of winding, the drive control of the winding mandrel is started with the initial reference tension smaller than the normal reference tension as the target value, and thereafter, the target value is changed to the normal value on condition that no slip occurs. While the control is continued while gradually increasing to the reference tension, if a slip is detected during this time, the control is continued while gradually reducing the target value with the initial reference tension as the lower limit to eliminate the slip state, thereby eliminating the slip. As a condition, the target value is gradually increased again to realize a reliable transition to a favorable winding state under the normal reference tension. (For example, refer to Patent Document 1).
[0004]
[Patent Document 1]
JP-A-4-238626.
[Problems to be solved by the invention]
However, the above-described prior art has the following problems.
[0006]
In particular, when winding a hot-rolled steel strip having a high winding temperature of 640 ° C. or higher, such as extremely low carbon steel, the steel strip is softened. Immediately after removal, the end of the hot-rolled steel strip may bite into the wound steel strip. Thereafter, when the guide roll (unit roll or wrapper roll) is opened when the tightening of the hot-rolled steel strip starts with such biting, a noticeable gap appears between the wound steel strip and the mandrel. The steel strip may slip. When the slip occurs between the steel strip and the mandrel in this manner, there is a problem that the mandrel runs idle and cannot be wound.
[0007]
Regarding this point, Patent Document 1 discloses that when a slip is detected, the control is continued while gradually reducing the target value with the initial reference tension as a lower limit to eliminate the slip state. When a slip occurred when winding a hot-rolled steel strip having a high winding temperature such as carbon steel, once the slip occurred, the slip state could not be eliminated even if the reference tension was lowered.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the related art, and to stably wind a hot-rolled steel strip around a mandrel even when a slip occurs between the mandrel and the hot-rolled steel strip. An object of the present invention is to provide a method for winding a hot-rolled steel strip.
[0009]
[Means for Solving the Problems]
The method for winding a hot-rolled steel strip according to the present invention has the following features.
[0010]
(1) In a method for winding a hot-rolled steel strip on a mandrel having a plurality of guide rolls arranged around the mandrel, the mandrel rotation speed or the mandrel rotation speed after the tip of the hot-rolled steel strip is wound on the mandrel. And / or measuring the load current of the mandrel drive motor, and detecting the occurrence of slip between the mandrel and the hot-rolled steel strip based on the increase in the mandrel rotation speed or / and the decrease in the load current of the mandrel drive motor. A method for winding a hot-rolled steel strip, comprising controlling opening and closing of a roll.
[0011]
(2) The method of winding a hot-rolled steel strip according to claim 1, wherein when the occurrence of slip is detected, the following guide control (a) or (b) is performed.
(A) If there is an open guide roll, at least one of the guide rolls is closed again for a predetermined time (A), and then control is performed so that the guide roll is opened.
(B) If there is a guide roll that is closed, the guide roll is extended by closing it for a predetermined time (B), and then the guide roll is controlled to open.
[0012]
(3) When the occurrence of slip is detected, the predetermined times (A) and (B) are controlled to be 3 seconds to 20 seconds, and the hot-rolled steel strip according to claim 2 is controlled. Winding method.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 is an explanatory diagram showing an example of a hot-rolled steel strip winding machine and an embodiment of the method of the present invention using the same.
[0014]
The winding machine (coiler) shown in FIG. 2 is disposed around the mandrel 2 around which the hot-rolled steel strip 1 is wound, and guides the tip of the hot-rolled steel strip 1 to the outer peripheral surface of the mandrel 2 and heats the strip. Guide rolls 3a to 3d (unit roll or wrapper roll) for pressing the steel strip 1 against the mandrel 2, a pinch roll 4 for restraining the hot-rolled steel strip 1 on the mandrel entry side, and a drive for rotating the mandrel. The motor 10, a rotational speed detector 11 for measuring the mandrel rotational speed, a current detector 12 for measuring the load current of the mandrel drive motor, and a slip between the mandrel and the hot-rolled steel strip based on the measurement results. The control device 13 controls the guide roll to close for a predetermined time when the occurrence is detected, or to extend the closed time.
[0015]
The guide rolls 3a to 3d serve to generate a frictional force between the hot-rolled steel strip 1 and the mandrel 2 by pressing the hot-rolled steel strip 1 against the mandrel 2 when the leading end of the hot-rolled steel strip 1 is wound. do. When the winding of the end of the hot-rolled steel strip 1 is completed (for example, after about 5 turns), the guide rolls 3a to 3d open and separate from the hot-rolled coil. Here, the guide roll needs to be closed as short as possible in order to prevent roll abrasion caused by pressing the steel strip and to improve the shape of the inside of the coil. It opens immediately.
[0016]
The opening / closing of the guide rolls 3a to 3d is controlled independently of each other, or is controlled by a plurality of sets. Slip often occurs between the mandrel and the hot-rolled steel strip immediately after at least one guide roll is opened.
[0017]
The pinch roll 4 guides the leading end of the hot-rolled steel strip 1 in the direction of the throat guide 7 serving as a guide plate, and the back of the hot-rolled steel strip 1 after passing through the final rolling stand of the finishing mill. Acts as a tension retainer.
[0018]
Here, the opening of the guide roll indicates that the roll moves in the anti-mandrel direction and separates from the steel strip surface, and the closing of the guide roll indicates that the roll moves in the mandrel direction and abuts on the steel strip surface. Is shown.
[0019]
Hereinafter, an embodiment of the method of the present invention using the apparatus configuration of the above-described winder (coiler) will be described.
[0020]
FIG. 1 shows the measurement results of the mandrel rotation speed and the mandrel current of the motor for driving the mandrel when the hot rolled steel strip is wound by the mandrel.
[0021]
Generally, the winding of the steel strip around the mandrel is performed by rotating the steel strip around the outer peripheral surface of the mandrel rotating at a peripheral speed (shown as “speed reference” in FIG. 1) slightly higher than the feeding speed of the steel strip. This is performed by pressing the tips and utilizing the frictional resistance generated between them.
[0022]
When the end of the steel strip wraps around the mandrel, the rotational speed of the mandrel decreases until it matches the speed of the steel strip (indicated as “steel strip speed” in FIG. 1) due to frictional resistance accompanying the pressing of the steel strip, At the same time, the driving power of the mandrel, specifically, the load current of the mandrel driving motor (indicated as “mandrel current” in FIG. 1) increases. Thereafter, when the winding of the tip of the steel strip is completed, the guide rolls 3a to 3d open and separate from the coil, but the mandrel current at that time is set to "100%".
[0023]
If a slip occurs between the mandrel and the hot-rolled steel strip immediately after the guide roll is opened, the rotation speed of the mandrel starts to increase, and the load current of the mandrel drive motor starts to decrease.
[0024]
Therefore, in the present invention, based on such a change in the rotation speed of the mandrel and / or the load current of the motor for driving the mandrel, the occurrence of slip between the mandrel and the hot-rolled steel strip is detected, and the opening and closing control of the guide roll is performed. It was made.
[0025]
In the present invention, the degree of increase in the mandrel rotation speed determined to be the occurrence of slip or the degree of decrease in the load current of the mandrel drive motor is not particularly limited, but generally, the deviation between the mandrel rotation speed and the speed reference value is not limited. Is less than 5% for 0.3 seconds or more, or the state where the load current of the mandrel drive motor is reduced by 10% or more with respect to the aforementioned mandrel current of 100% for 0.3 seconds or more? It is preferable to determine that slip has occurred between the mandrel and the hot-rolled steel strip when either of the above occurs first.
[0026]
However, when the deviation between the rotation speed of the mandrel and the speed reference value is less than 5%, or when the load current of the mandrel driving motor is reduced by 10% or more with respect to the aforementioned mandrel current of 100%. If the slip is determined with the continuation time of 0.3 seconds, the actual speed of the mandrel and the chattering of the actual current may result in erroneous determination that a slip has occurred without slipping, or the slip detection timing May be delayed, and it is conceivable to extend the duration of 0.3 seconds. However, when the slip occurs, the operation start timing of the guide roll is delayed, so that the deviation between the rotation speed of the mandrel and the speed reference value is less than 5%, and the load current of the motor for driving the mandrel is reduced to 100% of the aforementioned mandrel current. It is more preferable to determine that a slip has occurred between the mandrel and the hot-rolled steel strip when both of the occurrences of at least 10% and the decrease have occurred.
[0027]
In the present invention, when the occurrence of slip between the mandrel and the hot-rolled steel strip is detected based on the measurement result of the mandrel rotation speed and / or the load current of the mandrel driving motor, if there is an open guide roll, At least one of the guide rolls is closed again for a predetermined time (A), and then the guide roll is controlled to be opened. If there is a closed guide roll, it is closed for a predetermined time (B). It controls to extend the closing time and then open the guide roll.
[0028]
Here, it is common to measure both the mandrel rotation speed and the load current of the mandrel drive motor, but the slippage between the mandrel and the hot-rolled steel strip is detected from one of the measurement results, and guidance is performed. It is also possible to control the opening and closing of the roll.
[0029]
The slip state can be eliminated by closing the guide roll for a predetermined time or extending the time during which the closed guide roll is closed for a predetermined time, because the slip is suppressed while the guide roll is closed. If the steel strip can be wound with the slip suppressed for a predetermined time, the winding allowance will increase accordingly, and the force to reduce the coil inner diameter by the steel strip will act toward the coil inner diameter, so the generated gap will be reduced. This is because it can be made smaller.
[0030]
The time ((A) and (B) for controlling the open guide roll to be closed again for a predetermined time (A) or to extend the time for closing the closed guide roll for a predetermined time (B). )) Is preferably 3 seconds to 20 seconds, and the slip state can be eliminated by controlling the guide roll to close for 3 seconds to 20 seconds.
[0031]
Next, a specific control method of the present invention will be described based on an example of a hot-rolled steel strip winder shown in FIG.
[0032]
At the time of winding the leading end of the hot-rolled steel strip 1, the guide rolls 3 a to 3 d are closed, and by pressing the hot-rolled steel strip 1 against the mandrel 2, a frictional force is generated between the hot-rolled steel strip 1 and the mandrel 2. Then, the hot-rolled steel strip 1 starts to be wound around the mandrel. When the winding of the end of the hot-rolled steel strip 1 is completed (for example, after about 5 turns), the guide rolls 3a to 3d open and separate from the hot-rolled coil. Immediately after the guide rolls 3a to 3d are opened, a slip occurs between the mandrel and the hot-rolled steel strip. At this time, the mandrel is rotated based on the rotation speed of the mandrel or / and the load current of the motor for driving the mandrel. And control of opening and closing of the guide rolls 3a to 3d.
[0033]
In the present invention, the control device 13 sends the mandrel rotation speed measured by the rotation speed detector 11 and the load current of the mandrel drive motor measured by the current detector 12 from the drive motor 10 that rotationally drives the mandrel. The control device 13 stores the speed reference value obtained by inputting and multiplying the feeding speed of the steel strip by the lead rate and the current value of the mandrel current when the guide roll opens and separates from the coil.
[0034]
Then, in the control device 13, the state in which the deviation between the rotation speed of the mandrel and the speed reference value is less than 5% is continued for 0.3 seconds or more, or the load current of the mandrel driving motor is increased by the guide roll opening. When it is detected that the state in which the current value of the mandrel current at the time of leaving the coil is reduced by 10% or more or 0.3 seconds or more occurs first, the mandrel and the hot-rolled steel strip are connected. It is preferable to determine that a slip has occurred.
[0035]
However, under the above conditions, the actual speed of the mandrel and the chattering of the actual current may cause an erroneous determination that a slip has occurred without slipping, or the slip detection timing may be delayed. In the device 13, the deviation between the rotation speed of the mandrel and the speed reference value is less than 5%, and the load current of the motor for driving the mandrel is reduced by 10% or more from the mandrel current when the guide roll opens and separates from the coil. It is more preferable to determine that a slip has occurred between the mandrel and the hot-rolled steel strip when detecting the occurrence of the occurrence.
[0036]
When the occurrence of slip between the mandrel and the hot-rolled steel strip is detected, the control device 13 closes the guide roll for a predetermined time or controls the guide rolls 3a to 3d so as to extend the closed time. .
[0037]
【Example】
Conventionally, for a production volume of 150,000 tons / month of a hot-rolled steel strip having a high winding temperature of 640 ° C. or higher, as shown in FIG. The slippage occurred between the steel strip and the mandrel due to biting into the inside of the steel strip, and the winding trouble that the mandrel idled and could not be wound occurred on average 5 cases / month.
[0038]
Therefore, the mandrel rotation speed and the load current of the mandrel drive motor of the method of the present invention shown in FIG. 2 were measured, and the slip between the mandrel and the hot-rolled steel strip was measured based on the measurement result of the mandrel rotation speed or the load current of the mandrel drive motor. When the occurrence was detected, the opening and closing of the guide roll was controlled. The time for controlling the open guide roll to be closed again for a predetermined time or the time for controlling the closed guide roll to be closed for a predetermined time was set to 10 seconds.
[0039]
As a result, the winding trouble of 5 cases / month could be reduced to 0 cases / month. Once a winding trouble occurs, in addition to the coil in which the winding trouble has occurred, the slab or coarse bar or finish biting on the rolling line, which is scheduled to be rolled and wound on a coiler after that Since the steel strip inside (usually 3 coils) could not be used, the winding trouble was reduced to 0 cases / month, so that about 300 tons / month of damage could be prevented.
[0040]
【The invention's effect】
As described above, according to the present invention, even when slippage occurs in the mandrel, the hot-rolled steel strip can be stably wound by the mandrel, and the operation rate of the winder can be improved. As well as prevent winding trouble.
[0041]
[Brief description of the drawings]
[0042]
FIG. 1 is an explanatory diagram of a measurement result of a mandrel rotation speed and a mandrel current of a mandrel driving motor when a hot-rolled steel strip is wound by a mandrel.
FIG. 2 is an explanatory view showing an example of a hot-rolled steel strip winding machine and an embodiment of the method of the present invention using the same.
FIG. 3 is an explanatory view showing a state in which a bite occurs inside a steel strip in which the tip of a hot-rolled steel strip is wound.
[Explanation of symbols]
1 Hot-rolled steel strip 2 Mandrel 3a-3d Guide roll (unit roll or wrapper roll)
Reference Signs List 4 Pinch roll 5 Control device 7 Throat guide 10 Drive motor 11 Rotation speed detector 12 Current detector 13 Control device

Claims (3)

In a method for winding a hot-rolled steel strip around a mandrel having a plurality of guide rolls disposed around the mandrel, a mandrel rotation speed and / or a mandrel after a tip of the hot-rolled steel strip is wound around the mandrel. The load current of the drive motor is measured, and the occurrence of slip between the mandrel and the hot-rolled steel strip is detected based on the increase in the mandrel rotation speed and / or the decrease in the load current of the mandrel drive motor, and the opening and closing of the guide roll. A method for winding a hot-rolled steel strip, comprising controlling. The method for winding a hot-rolled steel strip according to claim 1, wherein when the occurrence of slip is detected, the following guide control of (a) or (b) is performed.
(A) If there is an open guide roll, at least one of the guide rolls is closed again for a predetermined time (A), and then control is performed so that the guide roll is opened.
(B) If there is a guide roll that is closed, the guide roll is extended by closing it for a predetermined time (B), and then the guide roll is controlled to open. 3. The method of winding a hot-rolled steel strip according to claim 2, wherein when the occurrence of slip is detected, the predetermined times (A) and (B) are controlled to be 3 seconds to 20 seconds. .

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