JPH09285817A - Equipment and method for taking up steel strip of hot rolling equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To take up a steel strip in a hot rolling equipment in a normal condition. SOLUTION: When a strip is coiled around a mandrel 10, the outer diameter of the mandrel 10 is firstly expanded to the same dimension as the inner diameter of a coil 40a, and in the second and subsequent coiling, the control is realized to avoid steps and the mandrel 10 is finely expanded. When the prescribed coiling number is reached, the diameter of the mandrel 10 is secondarily expanded to press the inner surface of the coil 40a, the lead ratio of the mandrel 10 is reduced to reduce the necking quantity of the strip. The frequency in controlling the step avoidance is reduced by releasing the control to avoid the step at early stage, and the friction of a segment 4 of the mandrel 10 and a unit roller is reduced to coil the strip in a normal condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip steel winding device and a winding method for hot rolling equipment for winding hot rolled strip steel rolled by a finish rolling mill in a coiler.

[0002]

2. Description of the Related Art A down coiler of a hot rolling facility for winding hot rolled steel strip rolled by a finish rolling mill with a coiler will be described with reference to FIGS. FIG. 15 is a front view of a general down coiler in which a unit roller is omitted, FIG. 16 is a state taken along the line AA in FIGS. 15 and 18, and FIG.
5 and the BB line arrow state in FIG. 18, and FIG. 18 shows the CC line arrow state in FIG. 16 showing the details of the mandrel.

In the figure, 51 is a hollow shaft, the neck of the hollow shaft 51 is supported by a bearing 60, and the tip of the hollow shaft 51 is pivotally mounted on an outboard 59 supported by a mandrel support (not shown). . The hollow shaft 51 is a speed reducer 6.
Hollow shaft 5 which penetrates 3 and penetrates reduction gear 63
1, a rotary cylinder 41 is attached. A reciprocating shaft 52 that is capable of reciprocating in the axial direction is provided in the hollow portion of the hollow shaft 51, and a rod portion (not shown) of the rotary cylinder 41 is connected to the reciprocating shaft 52. Rotary cylinder 41
The rotary portion of the rotary joint 42 is attached to the. The hollow shaft 51 is driven and rotated by a motor 61 via a drive shaft 62 and a speed reducer 63.

A wedge ring 53 is fixed to the outer peripheral surface of the hollow shaft 51, and a segment ring 55 is axially slidably fitted to the outer peripheral surface of the hollow shaft 51. The wedge portion of the inner peripheral surface of the segment 54 divided into four in the circumferential direction is slidably fitted to the wedge portion of the wedge ring 53, and the segment 54 divided into four is guided by the segment ring 55 in the radial direction d. ing. A cotter 56 is fixed to the segment ring 55 and the reciprocating shaft 52, and the cotter 56 is movable in the elongated hole 51 a of the hollow shaft 51 in the axial direction.

The above-mentioned rotary cylinder 41 and hollow shaft 5
1, reciprocating shaft 52, wedge ring 53, segment 5
4, the mandrel 50 is constituted by the cotter 56 and the outboard 59.

The winding condition of the strip steel (strip) will be described with reference to FIGS. 19 to 23. FIG. 19 is a side view showing the concept of the down coiler in FIG. 15, and FIGS.
An explanation of the operation of the down coiler is shown in 3.

In FIG. 19, 30 is a pinch roll, and an accelerometer 31 is attached to the pinch roll 30. Around the mandrel 50, a first unit roller 46a and a second unit roller 46b that move with respect to the shaft center.
And a third unit roller 46c are arranged. The strip 40 rolled by a finish rolling machine (not shown) is supplied to the mandrel 50 by the pinch roll 30, and the strip 40 is wound around the mandrel 50 and wound into a coil.

As shown in FIG. 20, in the first winding, the mandrel 50 has a predetermined outer diameter, and the first unit roller 46a, the second unit roller 46b, and the third unit roller 46c are set at fixed positions. First unit roller 4
6a, the second unit roller 46b, and the third unit roller 46c wind the strip 40 while pressing it on the mandrel 50. Strip 4 at the beginning of the second roll
When the top end of 0 comes, as shown in FIG. 21, the pressing of the first unit roller 46a is released by the step avoidance control, and as shown in FIG. 22, the second unit roller 4a is released.
When the top end comes to the positions of 6b and the third unit roller 46c, the second unit roller 46b and the third unit roller 46c
The pressing of the unit roller 46c is released to prevent the top end mark from being generated.

In this way, the first unit roller 46
a, the step avoidance control of the second unit roller 46b and the third unit roller 46c is performed, and the strip 40 is removed by 5 to 6
When the layers are wound up, the step avoidance control is canceled. After the step avoidance control is released, the mandrel 50 is over-expanded to prevent the interlayer gap and the slip between the segment 54 and the coil from occurring.

When the mandrel 50 is set to have a predetermined outer diameter and is overexpanded, the reciprocating shaft 52 and the cotter 5 are driven by the rotary cylinder 41 as shown in FIGS.
6. The wedge portion of each segment 54 is slid on the wedge portion of the wedge ring 53 through the segment ring 55 to move the segment 54 in the dc direction in FIG.
The movement of the segment 54 causes the mandrel 50 to expand or contract in the radial direction d.

[0011]

In the conventional winding of the strip steel, the diameter of the mandrel 50 is set to a fixed dimension (the inner diameter of the coil) from the first winding, and the strip 40 is wound while controlling the step difference. So strip 4
The number of times of step avoidance control until the tension is generated at 0 is 4 to 5
It was necessary to rotate the strip 40, and the tension of the strip 40 was delayed. If the tension generation of the strip 40 is slow, scratches may occur on the surface of the strip 40, and if the number of steps for avoiding the step is increased, the wear of the segment 54 of the mandrel 50 and the unit roller 46 is increased.

Further, in the conventional winding of the strip steel, since sufficient winding property cannot be ensured, the strip steel is inevitably wound at a high mandrel lead rate. Therefore, the necking amount of the strip 40 is increased.

[0013]

In order to solve the above problems, a strip steel winding device for hot rolling equipment according to the present invention includes a mandrel for winding the strip steel and reciprocating a wedge ring to expand and contract a segment. A hydraulic servo means for reciprocating the wedge ring, a hydraulic pressure detector for detecting the hydraulic pressure of the hydraulic servo means, a movement detector for detecting the movement state of the wedge ring, and a tip of the steel strip. The steel strip tip position detecting means for detecting the position, the detection information of the hydraulic pressure detector, the movement detector and the strip steel tip position detecting means are input and the hydraulic servo means is operated based on the input information. And a control device.

The mandrel includes a drive rotary hollow shaft having a long hole extending in the axial direction, a reciprocating shaft axially moving in a hollow portion of the drive rotary hollow shaft, and the drive rotary hollow shaft. A rotary cylinder that rotates to reciprocate the reciprocating shaft; a wedge ring that is axially slidably fitted to an outer peripheral surface of the drive rotating hollow shaft through a wedge portion; A cotter that axially movably penetrates in the axial direction to connect the wedge ring and the reciprocating shaft, a segment that is divided in the circumferential direction and slides axially with the wedge ring through a wedge portion, and the drive rotation hollow It is characterized by comprising a stopper ring attached to the shaft and moving the segment only in the radial direction.

In order to solve the above-mentioned problems, the strip steel winding method of the hot rolling equipment according to the present invention winds the strip steel into the mandrel by causing the strip steel to be bitten into the unit roller and the mandrel capable of expanding and contracting. At this time, the outer diameter of the mandrel is made smaller than the inner diameter of the strip steel coil at the start of winding the strip steel, and the tip of the strip steel is outside the mandrel when it is bitten into the mandrel and the unit roller. Diameter expansion is started, and after the first winding of the strip steel is completed, the outer diameter of the mandrel is primary expanded to the same dimension as the inner diameter of the strip steel coil, and the required number of turns after the second winding is increased. The unit roller is actuated by step avoidance control to slightly expand the diameter of the mandrel, and after the steel strip tension is generated by the required number of turns, the diameter of the steel strip is secondarily expanded and the mandrel is controlled by the constant pressure to produce the steel strip coil. And cancels the step avoidance control of the unit rollers with pressurized inner peripheral surface at a predetermined pressure.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION At the start of winding a strip steel (strip), the outer diameter of the mandrel is made smaller than the inner diameter dimension of the strip steel coil. When the strip steel tip position detecting means detects the biting of the strip between the mandrel and the unit roll, the movement detector detects the moving state of the wedge ring, that is, the outer diameter dimension of the mandrel and the hydraulic servo means. Then, the wedge ring is reciprocally moved to start the diameter expansion of the mandrel, and after the first winding of the strip is completed, the diameter is primary expanded to the same dimension as the inner diameter dimension of the strip steel coil. Up to the required number of windings after the second winding, the unit roll is operated by the step avoidance control and the outer diameter of the mandrel is finely expanded.

When the strip steel coil reaches the required number of turns and tension is generated in the strip, the mandrel is expanded in diameter to switch to constant pressure control, and the hydraulic pressure of the hydraulic servo means when the mandrel is expanded in diameter is changed. The hydraulic pressure of the hydraulic servo means is adjusted while being detected by the hydraulic pressure detector. In this state, the mandrel presses the inner peripheral surface of the strip steel coil with a required pressure and cancels the step avoidance control.

By reducing the mandrel lead rate by reducing the mandrel's primary diameter, minute diameter and secondary diameter to reduce the necking amount of the steel strip, the number of steps for avoiding steps is reduced and the surface of the steel strip or the mandrel is reduced. To reduce the friction between the segment and the unit roller.

The reciprocating shaft, the cotter and the wedge ring are moved in the axial direction by the hydraulic servo means to slide the wedge portion of the wedge ring onto the wedge portion of the segment.
Since each segment is axially constrained by the stopper ring, each segment moves only in the radial direction by being guided by the stopper ring by sliding of the wedge ring, and expands or contracts the outer diameter of the mandrel.

[0020]

EXAMPLE A strip steel winding device and a strip steel winding method for hot rolling equipment according to an embodiment of the present invention will be described with reference to FIGS. 1 to 14. 1 is a front view of a down coiler in which a unit roller is omitted, and FIG. 2 is II-II in FIGS. 1 and 4.
1 and 4 in FIG. 3, IV-IV line in FIG. 2 in FIG. 4, FIG. 5 is a side view showing the concept of the down coiler, and FIG. 7 to 12 show the operation of the down coiler, and FIGS. 13 and 14 are flowcharts showing the operation of the down coiler. The same members as those shown in FIGS. 15 to 23 are designated by the same reference numerals, and duplicate explanations are omitted.

1 to 4, reference numeral 1 denotes a hollow shaft, and the neck portion of the hollow shaft 1 is supported by a bearing 60,
The tip of the hollow shaft 1 is axially attached to an outboard 9 supported by a mandrel support (not shown). The hollow shaft 1 is provided so as to penetrate the reduction gear 63, and the hollow cylinder 1 that penetrates the reduction gear 63 is equipped with a rotary cylinder 11. A reciprocating shaft 2 capable of reciprocating in the axial direction is provided in the hollow portion of the hollow shaft 1, and a rod portion (not shown) of the rotary cylinder 11 is connected to the reciprocating shaft 2. The rotary portion of the rotary joint 12 is mounted on the rotary cylinder 11, and the rotary joint 12 is equipped with a sill-nack sensor 13 as a movement detector, hydraulic pressure sensors 14a and 14b, and a servo valve 14. Cylinac sensor 13,
The hydraulic pressure sensors 14a and 14b and the servo valve 14 are electrically connected to the control device 20. Rotary joint 1
2. The hydraulic pressure sensors 14a and 14b and the servo valve 14 constitute a hydraulic servo means.

A wedge ring 3 is slidably fitted on the outer peripheral surface of the hollow shaft 1, and a wedge portion 3a is formed on the wedge ring 3. A segment 4 divided into four in the circumferential direction is arranged on the outer circumference of the wedge ring 3, and a wedge portion 4a slidably fitted to the wedge portion 3a is formed on the inner circumference of the segment 4. Both ends of the segment 4 are supported by stopper rings 7 and 8 fitted to the hollow shaft 1, and the segment 4 is supported by the stopper rings 7 and 8 so as not to be movable in the axial direction but to be movable in the radial direction. ing. The hollow shaft 1 is formed with an elongated hole 1a extending in the axial direction, and the reciprocating shaft 2 is provided with a cotter 6 penetrating the elongated hole 1a. Both ends of the cotter 6 are fixed to the wedge ring 3, and the reciprocating shaft 2 and the wedge ring 3 are joined by the cotter 6.

A mandrel 10 is constituted by the rotary cylinder 11, the hollow shaft 1, the reciprocating shaft 2, the wedge ring 3, the segment 4, the cotter 6, the stopper rings 7 and 8 and the outboard 9 described above.

In FIG. 5, between the pinch roll 30 and the mandrel 10, a laser emitter 21a and a laser sensor 21b as a strip steel tip position detecting means are provided.
The laser sensor 21b is electrically connected to the control device 20. A reduction cylinder 47 is provided around the mandrel 10.
A first unit roller 46a, a second unit roller 46b, and a third unit roller 46c that reciprocate toward the axis of the mandrel 10 by a, 47b, and 47c are provided. A solenoid valve unit 48 is installed in each of the pressure reduction cylinders 47a, 47b, 47c.
Is electrically connected to the controller 20. Although the laser light emitter 21a and the laser sensor 21b have been described as an example of the strip steel tip position detecting means, an eddy current sensor can also be applied.

In FIG. 6, reference numeral 21 is a mandrel outer diameter calculation processing section, and the mandrel outer diameter calculation processing section 21 inputs the detection signal of the sillnac sensor 13 and compares the mandrel diameter expanding pressure / unit roller movement timing calculation section. Signal to 24. Reference numeral 22 denotes a mandrel diameter expansion pressure calculation processing unit, and the mandrel diameter expansion pressure calculation processing unit 22 includes the hydraulic pressure sensor 14a,
The detection signal of 14b is received, and a signal is sent to the mandrel diameter expanding pressure / unit roller movement timing comparison calculating section 24.

Reference numeral 23 is a winding start time / winding layer number calculation processing unit, and the winding start time / winding layer number calculation processing unit 23 receives a laser light reception interruption signal from the laser sensor 21b, and the mandrel diameter A signal is sent to the expanding pressure / unit roller movement timing comparison calculation unit 24. Reference numeral 25 is a mandrel / unit roller control data storage unit, and the mandrel / unit roller control data storage unit 25 is a mandrel diameter expanding pressure / unit roller movement timing comparison calculation unit 2
It transmits and receives with 4.

The mandrel diameter expanding pressure / unit roller movement timing comparison / calculation section 24 sends a signal to the solenoid valve unit operation instructing section 26 for operating the solenoid valve unit 48, and at the same time, the servo valve operating instructing section for operating the servo valve 15. 27
Send a signal to

The mandrel outer diameter calculation processing section 21 described above,
Mandrel diameter expansion pressure calculation processing unit 22, winding start timing / number of winding layers calculation processing unit 23, mandrel diameter expansion pressure / unit roller movement timing comparison calculation unit 24, mandrel / unit roller control data storage unit 25, solenoid valve The unit operation instruction section 26 and the servo valve operation instruction section 27 constitute the control device 20.

The operation of the strip winding device of the hot rolling equipment having the above-mentioned structure will be described with reference to the flowcharts of FIGS. 13 and 14. First, at the start of winding the strip 40, the outer diameter of the mandrel 10 is made smaller than the inner diameter of the coil 40a, and the strip 40 hot-rolled by a finish rolling machine (not shown) is used as the pinch roll 30 shown in FIG.
Is supplied to the mandrel 10 as shown in FIG.
That is, as shown in FIG. 7, the diameter D of the predetermined mandrel 10
On the other hand, the outer diameter is reduced to D-2β, and the first unit roller 46a, the second unit roller 46b, and the third unit roller 46c are arranged with the thickness t + α of the strip 40 separated.

The laser sensor 21b is a laser light emitter 21.
The laser from a is received, and a signal is constantly transmitted to the winding start time / rolling layer number calculation processing unit 23 of the control device 20. When the laser is cut off by the strip 40, the tip end of the strip 40 is It detects that it has passed. Winding start time / number of winding layers calculation processing unit 23
Is determined by the traveling speed of the strip 40 and the distance from the laser sensor 21b to the first unit roller 46a.
6a is calculated, and the calculation result is transmitted to the mandrel diameter expanding pressure / unit roller movement timing comparison calculating section 24.

The mandrel diameter expanding pressure / unit roller movement timing comparison calculation unit 24 compares and calculates the bite calculation result with the unit roller step avoidance control data stored in the mandrel / unit roller control data storage unit 25. , The comparison result is transmitted to the solenoid valve unit operation instructing section 26 to operate the solenoid valve unit 48. Solenoid valve unit 4
8, the first unit roller 46a and the second unit roller 4 are controlled by the step avoidance control as shown in FIG.
6b and the third unit roller 46c are sequentially rolled down, as shown in FIG.
Just before the second winding, the outer diameter of the mandrel 10 is primarily expanded from D-2β to a predetermined diameter (inner diameter of the coil 40a) D, as shown in FIG.

At this time, the servo valve 15 is used by the servo valve 15 while the rod position of the rotary cylinder 11 of the mandrel 10 is being detected by the syrnak sensor 13.
Activate By the operation of the rotary cylinder 11, the reciprocating shaft 2, the cotter 6 and the wedge ring 3 move to the right in FIG. 4, and the wedge portion 3 a slides on the wedge portion 4 a of each segment 4. Since the segments 4 are axially constrained by the stopper rings 7 and 8 due to the sliding of the wedge portions 3a and 4a, the segments 4 move only in the radial direction d.

As shown in FIGS. 10 and 11, the coil 40
After the second roll of a, the first unit roller 46a, the second unit roller 46b, and the third unit roller 46c are controlled to avoid a step, and the outer diameter of the mandrel 10 is slightly increased.

As shown in FIG. 12, coil coil 40a
Becomes a predetermined number of turns (third turn in the illustrated example), the mandrel 10 is switched from the outer diameter control to the diameter expansion pressure control. That is, the mandrel expanded pressure calculation processing unit 22 receives the hydraulic pressures of the rod side and the head side of the rotary cylinder 11 from the hydraulic pressure sensors 14a and 14b, and calculates the expanded pressure of the mandrel 10 based on the pressure difference. Calculated mandrel 10
The expansion pressure of the mandrel diameter expansion pressure / unit roller movement time comparison calculation unit 24 is input, and the mandrel diameter expansion pressure / unit roller movement time comparison calculation unit 24 calculates the expansion pressure of the mandrel 10 and the mandrel. The secondary expanded pressure data stored in the unit roller control data storage unit 25 is compared and calculated. The result of the comparison calculation is transmitted to the servo valve operation instructing section 27 to operate the servo valve 15,
Adjust to the specified secondary expansion pressure.

In this way, the mandrel 10 is subjected to primary diameter expansion, minute diameter expansion and secondary diameter expansion to pressurize the inner peripheral surface of the coil, and at the same time the first unit roller 46a, the second unit roller 46b and the third unit roller 46b. By canceling the step avoidance control of the unit roller 46c early, the lead rate of the mandrel 10 can be lowered, and the number of steps of the step avoidance control can be reduced.

[0036]

According to the present invention, when the strip steel is wrapped around the mandrel, the outer diameter of the mandrel is expanded to the same dimension as the inner diameter of the strip steel coil, and the mandrel is controlled at the second and subsequent turns together with the step avoidance control. The diameter of the mandrel is finely expanded, and when the required number of turns is reached, the mandrel is secondarily expanded to pressurize the inner surface of the strip steel coil, whereby the lead rate of the mandrel can be lowered. Therefore, the necking amount of the steel strip can be reduced. Further, since the step avoidance control is canceled early, the number of steps of the step avoidance control can be reduced, and the friction of the mandrel segment and the unit roller can be reduced.

[Brief description of drawings]

FIG. 1 is a front view of a down coiler in which a unit roller is omitted in a strip steel winding device of a hot rolling facility according to an embodiment of the present invention.

FIG. 2 is a view taken along the line II-II in FIGS. 1 and 4.

FIG. 3 is a view taken along the line III-III in FIGS. 1 and 4.

FIG. 4 is a view taken along line IV-IV in FIG. 2;

FIG. 5 is a side view showing the concept of a down coiler.

FIG. 6 is a configuration block diagram of a control device.

FIG. 7 is an explanatory view of the action of the down coiler.

FIG. 8 is an operation explanatory view of the down coiler.

FIG. 9 is an explanatory view of the action of the down coiler.

FIG. 10 is an operation explanatory view of the down coiler.

FIG. 11 is an operation explanatory view of the down coiler.

FIG. 12 is an explanatory view of the action of the down coiler.

FIG. 13 is a flowchart showing the operation of the down coiler.

FIG. 14 is a flowchart showing the operation of the down coiler.

FIG. 15 is a front view of a general down coiler.

16 is a view taken along the line AA in FIG.

FIG. 17 is a view taken along the line BB in FIG.

18 is a view taken along the line CC in FIG.

FIG. 19 is a side view showing the concept of a down coiler.

FIG. 20 is an explanatory view of the action of the down coiler.

FIG. 21 is an operation explanatory view of the down coiler.

FIG. 22 is an operation explanatory view of the down coiler.

FIG. 23 is an operation explanatory view of the down coiler.

[Explanation of symbols]

1 Hollow shaft 2 Reciprocating shaft 3 Wedge ring 3a Wedge part 4 Segment 4a Wedge part 6 Cotta 7,8 Stopper ring 10 Mandrel 11 Rotary cylinder 13 Silnack sensor 14a, 14b Hydraulic pressure sensor 15 Servo valve 20 Control device 21a Laser light emitter 21b Laser Sensor 21 Mandrel outer diameter calculation processing unit 22 Mandrel diameter expansion pressure calculation processing unit 23 Winding start time / number of winding layers calculation processing unit 24 Mandrel diameter expansion pressure / unit roller movement time comparison calculation unit 25 Mandrel / unit roller control data Storage unit 26 Solenoid valve unit operation instruction unit 27 Servo valve operation instruction unit 40 Strip 40a Coil 46a First unit roller 46b Second unit roller 46c Third unit roller 48 Solenoid valve unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuhisa Miyaguchi 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries Ltd. Hiroshima Works (72) Inventor Ryuichi Ohzono 4 Kannon-shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima 6-22 No. 22 Hiroshima Factory of Mitsubishi Heavy Industries, Ltd.

Claims (3)

[Claims] 1. A mandrel that winds a strip steel and reciprocates a wedge ring to expand or contract a segment, a hydraulic servo means that reciprocates the wedge ring, and a hydraulic pressure that detects a hydraulic pressure of the hydraulic servo means. A pressure detector, a movement detector for detecting the movement of the wedge ring, a strip steel tip position detecting means for detecting the position of the tip of the strip steel, the hydraulic pressure detector, the movement detector and the A strip winding device for hot rolling equipment, comprising: a controller for operating the hydraulic servo means based on the input information detected by the strip steel tip position detecting means. 2. The mandrel according to claim 1,
A drive rotary hollow shaft having a long hole extending in the axial direction, a reciprocating shaft for axially moving the hollow portion of the drive rotary hollow shaft, and a reciprocating motion of the reciprocating shaft rotating with the drive rotary hollow shaft. A rotary cylinder, a wedge ring axially slidably fitted to the outer peripheral surface of the drive rotary hollow shaft via a wedge portion, and an elongated hole of the drive rotary hollow shaft so as to be movable in the axial direction. A cotter that penetrates and connects the wedge ring and the reciprocating shaft, a segment that is divided in the circumferential direction and slides axially with the wedge ring through a wedge portion, and a segment that is attached to the drive rotary hollow shaft and that has the segment in the radial direction. A strip-winding device for hot rolling equipment, which comprises a stopper ring that moves only to the bottom. 3. When winding a strip steel into a mandrel and a unit roller and an expandable / contractible mandrel and winding the strip steel on the mandrel, at the start of winding the strip steel, the outer diameter of the mandrel is changed to the inner diameter of the strip steel coil. Smaller than the start of the outer diameter of the mandrel when the tip of the strip steel bites into the mandrel and the unit roller,
After the completion of the first winding of the strip steel, the outer diameter of the mandrel is primary expanded to the same dimension as the inner diameter of the strip steel coil, and the unit roller is moved by the step avoidance control until the required number of windings after the second winding. The mandrel is actuated to slightly expand the diameter, and after the steel strip tension due to the required number of turns is generated, the mandrel is secondarily expanded and the mandrel under constant pressure control presses the inner peripheral surface of the steel strip coil with a required pressure. At the same time, the step avoidance control of the unit roller is released, and a strip steel winding method for hot rolling equipment.