JPH11188422A - Winding method of hot rolled steel band - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method in which the effective necking protective effect is obtained in the method for winding a hot rolled steel band around a mandrel while the tension is given. SOLUTION: The tension given to a steel band is set at the initial value τ1 which is smaller than the tension set in steady time τ2 (steady state value) from the time t1 when the tip of the steel band is wound around a mandrel to the initial stage winding completion time t2 . From the time t2 to the time t3 when the fixed numbers of winding are completed (become stabled winding condition), the tension is increased gradually at a fixed rate of change from the initial value τ1 to the steady value τ2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for winding a hot-rolled steel strip around a mandrel while applying tension.

[0002]

2. Description of the Related Art As shown in FIG.
After leaving the finishing mill 2, it is guided by the conveying rollers 3, bent by the pinch roll 4, and then wound around the mandrel 5. At the time of this winding, the steel strip 1 is placed between the finishing mill 2 and the mandrel 5 or between the pinch roller 4 and the mandrel 5 so as to prevent the steel strip 1 from being displaced or loosened in the width direction. A predetermined tension is applied to the belt 1. Until the end of the steel strip 1 is wound around the mandrel 5, the rotational speed of the mandrel 5 is set to be higher than the supply speed of the steel strip 1, and the steel is wound when the end of the steel strip 1 is wound around the mandrel 5. A predetermined tension is applied to the belt 1.

In such a method of winding a hot-rolled steel strip, particularly in the case of a low-carbon steel having a thickness of, for example, 3 mm or less, the tip of the steel strip is wound around the mandrel, and the load torque is applied to the mandrel. At the timing of occurrence, the position immediately after exiting the final stand of the finishing mill (when the temperature is 700 to 9)
There is a problem that necking (where the width and thickness of the steel strip is locally reduced) is apt to occur in the part where the temperature is as high as 00 ° C.

To prevent this necking, for example,
Japanese Unexamined Patent Publication No. Sho 59-78721 discloses a technique as shown in FIG.
It is disclosed to perform a tension setting. That is, this
In the method, the tip of the steel strip begins to wind around the mandrel
Finish the winding of the specified number of turns (initial winding completed
(Time t)₁~ T_Two) Zhang given to steel strip
Set tension τ at steady state_TwoSmaller, at the start of winding
Initial value τ such that necking does not occur in₁Set to
When initial winding is completed_TwoIs the set tension τ at steady state _TwoSet
It is a fixed value.

[0005]

However, in the above-mentioned conventional method, the tension set value is increased stepwise to the set tension at the steady state in a step-like manner when the initial winding is completed.
The uniformity of the mandrel, pinch roll, rolling roll, and the like is likely to be lost, and there is a possibility that winding appearance defects such as loose winding may occur near the switching point of the tension set value. In addition, since the response of the control is low and the disturbance is large, the effect of preventing necking cannot be obtained as expected.

The present invention has been made in view of such problems of the prior art, and is directed to a method of winding a hot-rolled steel strip around a mandrel while applying tension. It is another object of the present invention to provide a method capable of obtaining an effective necking prevention effect without adversely affecting the winding shape and the sheet passing property of the coil.

[0007]

In order to solve the above-mentioned problems, a method of winding a hot-rolled steel strip according to the present invention comprises: a hot-rolled steel strip which is conveyed at a predetermined speed; In the method for winding a hot-rolled steel strip, in which the steel strip is wound around a mandrel while applying tension, when the steel strip tip is wound around a mandrel, the tension to be applied to the steel strip is set to a value higher than a set tension in a steady state. Set to a small initial value, and then until a predetermined winding state is reached (for example, until winding of a predetermined number of turns is completed, or until a predetermined time has elapsed)
During this period, the tension applied to the steel strip is gradually increased from the initial value to the set tension in a steady state.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram illustrating a winding-side facility of a hot-rolled steel strip, FIG. 2 is a schematic block diagram illustrating a tension control device that controls a winding tension of the steel strip, and FIG. 6 is a graph showing a relationship between a tension set value controlled in a form and time.

As shown in FIG. 1, after the hot-rolled steel strip 1 has exited the final stand 2a of the finishing mill 2,
After being guided by a pinch roll 4 and bent by a pinch roll 4, it is wound up around a mandrel 5. The tension applied to the steel strip 10 between the mandrel 5 and the final stand 2a is controlled by a current value A supplied to an electric motor 6 for rotating the mandrel 5, as shown in FIG. .

[0010] A current detector 7 is connected to the electric motor 6.
Current detection value A from the current detector 7 ₁Is the current controller 8
Is output to The current controller 8
A force setting device 9 is connected, and the current control device 8
For realizing the tension set value τ input from the
Current value Aτ of motor 6 and current detection value A₁Calculate deviation from
Then, the current value A corresponding to the deviation is output to the electric motor 6.

The tension setting unit 9 sets a tension setting value τ as shown in FIG.
As shown in 3, the end of the steel strip wrapped around the mandrel
Time t₁From the time when the winding of the specified number of turns
At the end of the initial winding) t_TwoDuring the period, the set tension at steady state (constant
Normal value) τ_TwoSmaller, necking at the beginning of winding
Initial value τ that does not occur₁At time t_TwoFurther from
Time t at which the constant number of windings is completed_ThreeUntil the first
Period value τ₁From the steady value τ _TwoUp to a constant rate of change up to
At time t_ThreeFor a while after that, the steady-state value τ _TwoIt
Each is output to the current control device 8. Time t_ThreeAfter
For a while_TwoAfter maintaining the tension of the winding
At the end, for example, gradually reduce the tension.
Is preferred.

Therefore, according to this equipment, the tension applied to the steel strip 10 between the mandrel 5 and the final stand 2a is smaller than that in the steady state from the first time the tip of the steel strip is wound around the mandrel until the initial winding is completed. (Initial value) τ ₁
And a tension that increases at a constant rate from the initial value τ ₁ to the steady value τ ₂ until the winding of a predetermined number of turns is completed.

As described above, in the method according to the present embodiment, the tension is not increased immediately after the completion of the initial winding (ie, at time t ₂ ) until the winding becomes more stable, instead of increasing the tension to the steady value τ _2. As a result, the steady value τ ₂ is obtained when stable winding is performed (that is, at time t ₃ ), so that necking is effectively prevented without a defective winding appearance or the like. In addition, the response of the control is high, and the disturbance is small.

As a specific example, the initial winding number (time t
The number of turns) at ₂ and 5 to 10 vol., And the stable winding number (winding number at time t ₃₎ and 10 to 20 vol., The initial value tau ₁ of tension about 50-90% of the stationary value tau ₂ Setting. From the initial value tau ₁ but necking preventing effect increases the rate of changing the tension to a steady value tau ₂ is small is high, because the production capacity takes time to take-up as the speed is low is reduced, the rate of both The optimum value is set in consideration of the balance. In addition, each value is set to an optimum value according to the capabilities and operating conditions of the rolling equipment and the winding device.

Actually, in winding a hot-rolled steel strip having a thickness of 1.8 mm and a width of 1000 mm made of a general low-carbon steel, SPHC, the steady-state value τ _{2 of the} tension is set to 1.3 to 1.3 mm.
And 1.6 kgf / mm ^2, set 85% of the steady-state value tau ₂ to an initial value tau ₁ tension, the time from time t ₂ to time t ₃ was a 3-5 seconds, at time t ₂ Stationary value τ ₂
The effect of reducing the average value of the necking amount in the width direction from 3.2 mm to 2.5 mm was obtained as compared with the case of the above.

[0016] In the above embodiment, although increased at a constant rate the tension setting value from the initial value tau ₁ to a steady value tau _2, the present invention is not limited thereto, the time t ₃ from time t ₂
The rate of increase in tension may be changed between the two.

In the above embodiment, the tension is gradually increased at the completion of the initial winding (time t ₂ ). However, the present invention is not limited to this, and the time when the tip of the steel strip is wound around the mandrel ( The tension may be gradually increased immediately after the time t ₁ ) or immediately thereafter. Then, in this case, the time t
The tension set value at ₁ may be “0”.

[0018]

As described above, according to the present invention,
In the method of winding a hot-rolled steel strip around a mandrel while applying tension, an effective anti-necking effect can be obtained without adversely affecting the winding appearance and the sheet passing property of the coil.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a winding-side facility of a hot-rolled steel strip.

FIG. 2 is a schematic block diagram showing a tension control device for controlling a winding tension of a steel strip in one embodiment of the present invention.

FIG. 3 is a graph showing a relationship between an initial tension setting value and a time at the time of winding a steel strip in one embodiment of the present invention.

FIG. 4 is a graph showing a relationship between a tension set value and a time at an initial stage of winding a steel strip in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot-rolled steel strip 2 Finish rolling mill 2a Final stand 3 Conveying roller 4 Pinch roll 5 Mandrel 6 Electric motor 7 Current detector 8 Current control device 9 Tension setting device

Claims (1)

[Claims] 1. A method for winding a hot-rolled steel strip, wherein the tip of a steel strip which has been hot-rolled and conveyed at a predetermined speed is wound around a mandrel, and the steel strip is wound around a mandrel while applying tension. When wrapping the steel strip tip around the mandrel, set the tension to be applied to the steel strip to an initial value smaller than the steady-state set tension,
A method for winding a hot-rolled steel strip, wherein the tension applied to the steel strip is gradually increased from the initial value to the set tension in a steady state until a predetermined winding state is obtained.