JP2003170204A - Rolling method and rolling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make further extreme thin rolling possible with a compact structure. <P>SOLUTION: In a rolling method for a rolling device provided with a reversible type rolling mill, and first and second coilers arranged on the upstream and downstream sides, respectively, a rolling direction is switched in such a state in which the remnant of winding of a rolled material exists at the first and second coilers respectively, when the rolling direction is switched to at least a final pass among a plurality of reversible rollings. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rolling method and rolling equipment.

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a Steckel rolling facility suitable for hot rolling, and relates to a rolling method for efficiently and economically producing ultra-thin strip steel.

In the production process of strip steel produced by hot rolling equipment, first, a slab having a thickness of 200 mm or more is cast by a continuous casting machine. The slab is unidirectionally or reversibly rolled by a plurality of rough rolling mills to manufacture a bar material.
Then, this bar material is rolled by a group of finishing tandem rolling mills in which a plurality of bar materials are continuously arranged to obtain a predetermined plate thickness. Then, this bar material is cooled by a cooling device and wound by a coiler to form a coiled steel strip. Such hot rolling equipment is intended for mass production and is extremely large-scale equipment.

[0004] In recent years, with the large amount of iron scrap being produced, the importance of its recycling has increased, and the idea of disposing small-scale small-scale production facilities in a distributed manner has become more prevalent than the large-scale mass production concentrated in one station. Hot rolling equipment, which is said to be hot and has a hot coil production scale of about 1 million tons / year, has come to be constructed.

Further, as described in JP-A-8-267101, a mini hot rolling facility for rolling a coiled strip steel to a strip plate sheet or the like by a reversible hot rolling mill having a pair of coiler furnaces is also introduced. There is. In addition, JP 2001
No. 137907 also discloses a Steckel facility.

[0006]

In the above-mentioned conventional example, there is a problem that the construction cost is high due to the small-species mass-production facility, and it is not possible to meet the market needs of various kinds. The so-called Steckel mill introduced in the above-mentioned publicly known example is a reversible finishing mill as described in Nippon Metallurgy Technical Report No. 5 (1996) "Construction of a new compact mill". It has a pair of coiler furnaces that operate in tandem with the reversible finish rolling mill. When rolling strip steel, the tip of the material to be rolled bites into the reversible finishing mill in the first pass. It is rolled and rolled, its tip sticks into the grip groove of the mandrel of the rear coiler furnace, and then the mandrel rotates in conjunction with the reversible finishing mill to wind the material to be rolled. The rolling mill is stopped immediately after the trailing edge of the material to be rolled in the first pass has passed the reversible finishing mill, and in the second pass, the material to be rolled flows in the direction opposite to that of the first pass and is rolled. Similarly, its tip (rear end in the first pass) is inserted into the grip groove of the mandrel of the front coiler furnace, and then the mandrel rotates in conjunction with the reversible finishing mill to wind up the material to be rolled. Such an operation is carried out for several passes to roll the strip steel. In the above-mentioned conventional example, it is not possible to roll the ultra-thin strip steel. That is, a certain thickness or more is required for the tip of the rolled material to penetrate into the grip groove of the mandrel of the coiler furnace. In order to roll ultra-thin strip steel by the above conventional rolling method, the equipment such as the guide mechanism of the ultra-thin strip steel from the reversible finishing mill to the mandrel of the coiler furnace and the mechanism of the mandrel grip groove are completely reviewed. New equipment must be installed, and the equipment investment will be extremely large.

An object of the present invention is to provide a rolling method and rolling equipment capable of further ultra-thin rolling with compact equipment.

[0008]

The present invention is directed to a reversible rolling mill capable of rolling rolled material in the forward and reverse rolling directions, and to the upstream side of the reversible rolling machine, A rolling method using a rolling facility equipped with a first coiler capable of winding and unwinding, and a second coiler capable of winding and unwinding of the rolled material on the downstream side of the reversible rolling mill, comprising a plurality of reversible rolling steps. When the rolling direction is switched to at least the final pass of the rolling, the rolling direction is switched in a state where unrolled material of the rolled material exists in each of the first coiler and the second coiler.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION When rolling ultra-thin strip steel, the mandrel of a pair of coiler furnaces arranged before and after the reversible finishing mill and operated in conjunction with the reversible finishing mill is to be rolled. Passing the material to be rolled before and after the reversible finishing mill in a state in which several turns of the leading end and the trailing end of the material are always wound,
It is desirable to repeat rolling multiple times.

In the embodiment of the present invention, the ultra-thin strip steel can be rolled at an economical construction cost without changing the equipment structure of the conventional Steckel mill.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of rolling equipment which is an embodiment of the present invention. This rolling equipment is mainly
A first coiler 3 capable of winding and unwinding rolled material with a heating furnace, a reversible finish rolling machine 4 capable of reversible rolling, and a rolled material unwinding and unwinding with a heating furnace sequentially from the upstream side. It is a Steckel rolling facility in which the second coiler 5 and the second coiler 5 are sequentially arranged from the upstream side. First coiler 3 and second coiler 5
The reversible finishing rolling mill 4 is arranged between and. After being reversibly rolled by this rolling facility, it is wound up by a down coiler or the like arranged on the downstream side of this rolling facility. It is desirable to provide a cutting machine between the rolling equipment and the down coiler for cutting unnecessary portions of the front and rear ends of the rolled material. In the present embodiment, the left side of the drawing is called the upstream side and the right side of the drawing is called the downstream side.

A rolling material 1 which is an intermediate bar material roughly rolled by a rough rolling mill is supplied to the rolling equipment of FIG. The rolled material 1 after the rough rolling is moved in the arrow direction (forward rolling direction) from the upstream side to the downstream side on the transport table 2.

The first coiler 3 is a reversible finishing mill 4
A coiler furnace 3a that is provided on the upstream side of the above and covers the whole to suppress the temperature decrease inside, and a mandrel 10a that serves as an axial center when winding the rolled material 1. Coiler furnace 3
In a, for example, the temperature of the coiled rolled material 1 is set to 850
The temperature is kept above ℃ (for example, 850 ℃ to 1050 ℃). Although it is described as a heating furnace, it also serves as a predetermined heat retention. The mandrel 10a is provided with a grip groove for sandwiching the end of the rolled material. The inside guide 1 plays a role of guiding the rolled material 1 toward the grip groove and the mandrel 10a so that the rolled material 1 can be easily wound.
1a is provided on the entrance side of the first coiler 3. One of the inside guides 11a is attached to the lower part of the coiler furnace 3a as a rotating shaft and can rotate about this shaft, and by this rotation, it can move up and down about the shaft. Further, a deflector guide 13a and a deflector roller 12a are provided on the entrance side of the first coiler 3, and the rolled material 1 is configured to pass between them. The deflector guide 13a is configured to rotate around one side thereof, and is positioned along the inside guide 11a at the time of winding or unwinding work so as to guide the rolled material 1 toward the mandrel 10a. Fulfill Other than the winding and unwinding work, for example, when the rolled material 1 is passed from the upstream side, it is positioned along the pass line and serves as a guide for conveying the rolled material 1 from the upstream side to the downstream side. Fulfill Between the first coiler 3 and the reversible finishing mill 4, a pair of upper and lower pinch rollers 8a and 8b are arranged on the inlet side of the first coiler 3, and the pinch roller 8a and the pinch roller 8a are arranged. The rolled material 1 can be sent from the reversible finishing mill 4 to the first coiler 3 by the roller 8b.

When the rolled material 1 is fed to the first coiler 3, the pinch roller 8a and the pinch roller 8b are rotatably driven by a rotary drive device and serve to feed the rolled material 1. In addition, the rolled material 1 is attached to the mandrel 10a.
When rolled and rolled, it is desirable not to contact the rolled material 1 in order to suppress the temperature decrease of the rolled material 1. For example, the upper pinch roller 8a may be moved upward.

In the present embodiment, the reversible finishing mill 4 includes an upper work roll 6a and a lower work roll 6 for rolling the rolled material 1.
b, and one reversible four-high rolling mill provided with an upper reinforcing roll 7a and a lower reinforcing roll 7b that respectively support the upper work roll 6a and the lower work roll 6b. However, other multi-high rolling mills may be applied. Further, in the present embodiment, the rolling mill is described as one unit, but two or more rolling units may be arranged,
A twin mill provided with two roll groups in one housing may be applied.

The second coiler 5 is a reversible finishing mill 4
A coiler furnace 5a that is provided on the downstream side of the above to suppress the temperature decrease inside the mandrel and a mandrel 10b that serves as an axis when the rolled material 1 is wound up are provided. Coiler furnace 5
In a, for example, the temperature of the coiled rolled material 1 is set to 850
The temperature is kept above ℃ (for example, 850 ℃ to 1050 ℃). The mandrel 10b is provided with a grip groove for sandwiching the end of the rolled material. An inside guide 11b, which plays a role of guiding the rolled material 1 toward the grip groove and the mandrel 10b, is provided on the entrance side of the second coiler 5 so that the rolled material 1 can be easily wound. One of the inside guides 11b is attached to the lower part of the coiler furnace 5a as a rotary shaft and can rotate about this shaft, and by this rotation, it can move up and down about the shaft. Further, a deflector guide 13b and a deflector roller 12b are provided on the entrance side of the second coiler 5, and the rolled material 1 is configured to pass between the both. The deflector guide 13b is configured to rotate around one side thereof, and is positioned along the inside guide 11b at the time of winding or unwinding work so as to guide the rolled material 1 toward the mandrel 10b. Fulfill Other than the winding and unwinding work, for example, when the rolled material 1 is passed from the upstream side, it is positioned along the pass line and serves as a guide for conveying the rolled material 1 from the upstream side to the downstream side. Fulfill Between the second coiler 5 and the reversible finishing mill 4, a pair of upper and lower pinch rollers 9a and 9b are arranged on the entry side of the second coiler 5, and the pinch roller 9a and the pinch roller 9a are disposed. The rolled material 1 can be sent from the reversible finishing mill 4 to the second coiler 5 by the roller 9b.

Like the pinch roller 8a and the pinch roller 8b described above, the pinch roller 9a and the pinch roller 9b are also driven to rotate by a rotary drive device when the rolled material 1 is fed to the second coiler 5, and are rolled. It plays the role of feeding the material 1. Further, when the rolled material 1 is wound around the mandrel 10b and rolled, it is desirable not to come into contact with the rolled material 1 in order to suppress the temperature decrease of the rolled material 1. For example, the upper pinch roller 9a may be moved upward.

Next, a general procedure for reversible rolling will be described below. The outline of the reversible rolling is as follows. First, a rolled material 1 having a thickness of about 25 mm or less passes under the front side coiler furnace 3a and is rolled by a reversible finishing mill 4 to a rear side coiler furnace 5a. Be wound up. Here, the reversible finishing mill 4
By the front side pinch roller 8a and the pinch roller 8b arranged on the upstream side and the downstream side, and the rear side pinch roller 9a and the pinch roller 9b, the rolled material 1 operates so as to be fed into each coiler. The reversible finishing mill 4 is repeatedly reversibly rolled to produce a hot ultrathin plate having a thickness of 2 mm or less.

Here, before finish rolling in this equipment, for example, a material such as SUS material or ordinary steel and having a thickness of 170 to 250 is used.
Rolled material 1 which is an intermediate bar material, which is roughly rolled by a roughing mill to slab material having a width of 400 mm, a width of 400 to 2000 mm, and a length of 10 m.
Is manufactured. The thickness of the rolled material 1 which is the intermediate bar material is about 25 mm or less, and the temperature thereof is, for example, about 1050 ° C.
is there.

The individual steps of reversible rolling will be described below with reference to FIG. FIG. 2 shows a configuration diagram of the rolling facility.

In the first pass (forward rolling), the rolled material 1 is conveyed from the upstream side, and the deflector guide 13a is moved to the position shown in FIG.
As shown in Fig. 1, the rolling material 1 is set at the lower position (rolling line, pass line), and the rolling material 1 is moved on the conveying table 2 toward the downstream side (in the direction of the arrow in the figure) and supplied to the reversible finishing mill 4. To do. This rolled material 1 is rolled by the upper work roll 6a and the lower work roll 6b of the reversible finishing mill 4, and is conveyed toward the mandrel 10b side by the pinch rollers 9a and 9b on the rear surface side. Rolled material 1 that has passed through the pinch rollers 9a and 9b
Is the deflector guide 13b and the inside guide 11
Guided by b, the tip of the rolled material 1 is inserted into the grip groove 14b provided in the mandrel 10b, and the transportation of the rolled material 1 is temporarily stopped. With the tip of the rolled material 1 inserted into the grip groove 14b, the mandrel 1
0b is rotated in the winding direction as shown in the figure, and rolled material 1
Is rolled up and rolled in conjunction with the reversible finishing mill 4. Then, after the rear end of the rolled material 1 passes through the upper work roll 6a and the lower work roll 6b of the reversible finishing mill 4,
Stop rolling once. The rolling of the first pass is completed in the above steps, and the rolled material 1 is stored in the second coiler 5 in a coil shape.

Next, the coil-shaped rolled material 1 in the second coiler 5 is conveyed backward from the downstream side to the upstream side, and the second pass reverse rolling is performed. Similar to the first pass above,
The rolled material 1 is fed toward the first coiler 3 by the front side pinch roller 8a and the pinch roller 8b.
At the time of switching the rolling direction from the first pass (forward rolling) to the second pass (reverse rolling), the rolled material 1 is not wound around the mandrel 10a of the first coiler 3. As described above, rolling in a state where the rolled material 1 is not wound around one coiler at the time of switching the rolling direction is referred to as first switching.

Here, the deflector guide 13a is in the upper position (mandrel 1) as shown in FIG. 1 during reverse rolling.
0a to the position for guiding the rolled material 1). The rolled material 1 is inserted into the grip groove 14a in the mandrel 10a by the guide of the deflector guide 13a and the inside guide 11a, and reverse rolling is performed as in the first pass.

The above-described forward rolling and reverse rolling are sequentially repeated to perform reversible rolling a plurality of times. FIG. 3 shows a state in which a plurality of rolling passes are performed and rolling is performed while the rolled material 1 is wound on the front coiler furnace 3a and the rear coiler furnace 5a. As the rolling of each pass is performed, the plate thickness of the rolled material 1 becomes thinner.

If the thickness of the rolled material 1 becomes excessively thin and exceeds the thinness limit, the rigidity of the material of the rolled material 1 will be insufficient, and the tip of the rolled material 1 will be in the grip groove 14b provided in the mandrel 10b. Difficult to stab. Further, when the plate thickness is extremely thin (2.0 mm or less), there are problems such as surface scratches due to meandering and winding deviation of the plate.

That is, the problem of the meandering of the plate is due to the influence of a slight difference in the rolling-down setting between the operating side and the driving side as the plate thickness becomes thinner. Due to this influence, the rolled material is likely to meander when the tip of the rolled material is inserted into the grip groove 14b.

If rolling and winding on the mandrel 10b are continued while the tip of the rolled material is meandering, the rolled material 1 comes off the end of the work roll, making it difficult to continue rolling. In order to prevent the rolled material 1 from coming off from the work roll end, for example, there is a method of reducing the rolling speed when the rolled material 1 is inserted into the grip groove 14b at the tip of the rolled material. The thinner the thickness, the faster the temperature will drop, making proper finish rolling difficult.

Further, problems such as surface scratches due to winding deviation are caused by the application of tension. That is, in normal rolling,
After the front end of the rolled material is inserted into the grip groove 14b, tension is applied at the start of winding to prevent flaws on the rolled material due to slippage in the circumferential direction of the mandrel and prevent slippage. However, in the case of rolling ultra-thin sheets,
When the tension is applied, there is a possibility that the leading end of the rolled material may come out of the grip groove 14b or the rolled material may be broken.

In this embodiment, the rolled material 1 is further thinly rolled from such a state to obtain an ultra thin strip steel.

In the present embodiment, in the rolling after the state where the thinness limit of an arbitrary strip thickness is not exceeded (a strip thickness thinner than an arbitrary strip thickness),
As shown in FIG. 3, the mandrel 10a, 10b of the first coiler 3 and the second coiler 5 is reversibly rolled with a few turns of the rolled material 1. That is, each rolling pass is terminated and a plurality of reversible rollings are repeated while leaving several turns at the leading end and the trailing end of the rolled material 1. In this way, when changing the rolling direction, the rolled material 1 is applied to one coiler.
Rolling in the state of being wound is called a second switching method.

Ultra-thin rolling is possible by repeatedly performing reversible rolling by the above-mentioned first switching method and then switching and rolling by this second switching method. This second switching method is preferably applied at least when switching to the final path. By repeatedly performing reversible rolling with the first switching method, it is possible to roll a sufficient length range in the length direction of the rolled material. After that, by switching by the second switching method and rolling, it is possible to roll to a thin plate thickness.

It is desirable to leave about 2 to 3 turns when switching the rolling direction with one coiler wound and the other coiler leaving several turns. This makes it possible to roll ultra-thin by the desired unwinding, while maintaining an appropriate winding tension when winding with the other coiler, preventing the rolled material from coming off from the mandrel. can do. Further, since the appropriate winding tension can be maintained at the time of switching, the speed can be increased immediately after the start of rolling in the subsequent pass, and the productivity is improved.

It should be noted that portions of the rolled material 1 at both ends (leading end and trailing end) in the longitudinal direction, which have a large plate thickness, may be wound up as they are, or may be cut by a cutting machine or the like and hot-cut into a down coiler. You may wind it up as a finishing material. If you wind it up as it is, there is no need to install a cutting machine, and
Both ends can be dealt with in a later step. Further, by arranging a cutting machine between the present reversible rolling equipment and the down coiler or on the downstream side of the present reversible rolling equipment, a plate at both end portions (leading end portion and rear end portion) in the longitudinal direction of the rolled material 1 is obtained. A thick part can be cut, and a rolled material having an appropriate thickness can be wound up on a down coiler.

Next, a description will be given of the control by the second switching system in which the coiling direction is rolled up by one coiler and the rolling direction is switched while leaving the other coiler several turns. When switching the rolling direction in the reversible rolling equipment, the drive mechanism related to the rolling direction in the reversible rolling equipment is controlled.

The drive mechanism related to the rolling direction is mainly composed of
Mandrel 10 of first coiler 3 and second coiler 5
a and mandrel 10b rotation drive device, transport table 2
Roller driving device, a pinch roller 8a and a pinch roller 8b, a pinch roller 9a and a pinch roller 9b, and a roll driving device for a rolling mill. In addition, each drive device is provided with a control device. As shown in FIG. 4, the control device includes a coiler control device 22 that controls the rotation drive device of the mandrel 10a and the mandrel 10b, and a transport table control device 2 that controls the rotation drive device of the roller of the transport table 2.
3, a roller control device 24 that controls the rotation drive device of the pinch roller 8a and the pinch roller 8b, the pinch roller 9a and the pinch roller 9b, a rolling control device 25 that controls the rotation drive device of the rolls of the rolling mill, and the like.

With the control by the second switching system for switching the rolling direction with one coiler winding and leaving the other coiler for several windings, the rolling direction can be switched by, for example, changing the switching system. A control command is sent from the switching timing detection device 20a to the control command device 21 so as to change or change the switching method by detecting or inferring it, and the transport table control device 23, the roller control device 24, and the rolling control are performed. The device 25 and the like are controlled. It is also possible to preset in advance which pass of a plurality of reversible rolling passes when the rolling direction is switched to change the switching system to the second switching system. For example, in all 6-pass rolling, the first switching method is applied up to the 5th pass, reversible rolling is performed by changing the rolling direction, and the second switching method is used when switching the rolling direction to the 6th pass, which is the final pass. It can be applied and the rolling direction can be changed to perform rolling.

At least when the rolling direction is switched to the final pass among the multiple reversible rollings, the rolling direction is switched while the unrolled material 1 remains in each of the first coiler 3 and the second coiler 5. Thereby, it is possible to roll to a thinner strip thickness without installing another rolling mill on the downstream side of the reversible rolling equipment.

The timing of changing the switching system can be determined, for example, by providing a measuring device for measuring the number of revolutions on the pinch roller 8a and the pinch roller 8b, the pinch roller 9a and the pinch roller 9b, and calculating the rolling time from the number of revolutions to determine the rolling condition And it is possible to detect based on this rolling time. Alternatively, a method of attaching a measuring device to the end of the roll may be used. Further, the mandrel 10a and / or the mandrel 10b may be provided with a detection device for detecting the unwound amount of the rolled material 1.

Further, when the rolled material thickness detecting device 20b detects or estimates the thickness of the rolled material and the rolled material thickness becomes a desired thickness or less, the switching method is changed. From the rolled material thickness detection device 20b to the control command device 21
The control command device 21 controls the transport table control device 23, the roller control device 24, the rolling control device 25, etc. to change the switching method. From the rolling conditions, it is estimated how many of the multiple reversible rolling passes will result in a plate thickness of 2 mm or less, and the second switching system will be used when the rolling direction is switched to the next pass. It is also possible to preset whether to change to.
For example, when the total thickness of the 6th pass is 2mm or less in the 5th pass, the first switching method is applied up to the 5th pass, the rolling direction is changed, and reversible rolling is performed. When the rolling direction is switched to the sixth pass, the second switching method may be applied to change the rolling direction to perform rolling.

In the plate thickness estimation, for example, an estimated value at a desired time can be detected from the rolling conditions (plate thickness before rolling, reduction amount, number of passes, etc.).

The plate thickness can be detected, for example, by providing a plate thickness detector on the inlet side or the outlet side of the rolling mill.

Therefore, according to the present embodiment, even if the thickness becomes excessively thin, exceeding the thinness limit, it becomes possible to carry out rolling. Then, regardless of the plate thickness of the rolled material 1, it is possible to perform rolling for obtaining a further ultra-thin strip steel, for example, a hot finish material having a thickness of 0.8 to 2.0 mm. Further, even when the plate thickness is extremely thin (2.0 mm or less), it is possible to prevent the above-mentioned meandering and winding deviation of the plate.

At the stage of hot finishing, ultra-thin (2.0 m
Since it is possible to obtain the hot-rolled material of m or less), the load in the post-process, for example, the cold process is reduced, and the productivity is improved.

According to this embodiment, further ultra-thin strip steel can be rolled with economical equipment construction cost and compact equipment.

[0045]

According to the present invention, with a compact equipment,
It is possible to provide a rolling method and rolling equipment capable of further ultrathin rolling.

[Brief description of drawings]

FIG. 1 is a side view of rolling equipment according to an embodiment of the present invention.

FIG. 2 is a side view of rolling equipment when a rolled material is inserted into a grip groove of a mandrel.

FIG. 3 is a side view of rolling equipment according to an embodiment of the present invention.

FIG. 4 is a control configuration diagram of rolling equipment according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Rolled material, 2 ... Conveying table, 3 ... First coiler,
3a, 5a ... coiler furnace, 4 ... reversible finishing mill, 5 ...
2nd coiler, 6a ... upper work roll, 6b ... lower work roll, 7a ... upper reinforcement roll, 7b ... lower reinforcement roll, 8
a, 8b, 9a, 9b ... Pinch roller, 10a, 10
b ... mandrel, 11a, 11b ... inside guide,
12a, 12b ... Deflector rollers, 13a, 13
b ... Deflector guide, 14a, 14b ... Grip groove, 20a ... Switching timing detection device, 20b ... Rolled material thickness detection device, 21 ... Control command device, 22 ... Coiler control device, 23 ... Conveying table control device, 24 ... Roller Control device, 25 ... Rolling control device.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinichi Kaga             4-6 Kanda Surugadai, Chiyoda-ku, Tokyo             Within Hitachi, Ltd. F term (reference) 4E002 BA03 BC01 BD03 BD08 CB08

Claims (18)

[Claims] 1. A reversible rolling machine capable of rolling a rolled material in forward and reverse rolling directions, and a first rewinding and unwinding apparatus for rolling the rolled material upstream of the reversible rolling machine. A rolling method using a rolling facility comprising a coiler and a second coiler capable of winding and unwinding the rolled material on the downstream side of the reversible rolling mill, wherein at least a final pass of a plurality of reversible rollings is performed. A rolling method, characterized in that, when the rolling direction is switched, the rolling direction is switched in a state where unrolled material of the rolled material exists in each of the first coiler and the second coiler. 2. A rolling method in which reversible rolling is performed by a reversible rolling mill arranged between a first and a second coiler capable of winding and unwinding rolled material, the reversible rolling being performed a plurality of times by the reversible rolling mill. A rolling method, wherein the rolling direction is switched at least when the rolling direction is switched to the final pass of the rolling, in a state where unrolled parts of the rolled material exist in each of the first coiler and the second coiler. 3. A reversible rolling mill capable of rolling a rolled material in the forward and reverse rolling directions, and a winding shaft for winding and unwinding the rolled material upstream of the reversible rolling machine. A rolling method using a rolling facility comprising one mandrel and a second mandrel that serves as a shaft for winding and unwinding the rolled material on the downstream side of the reversible rolling mill, wherein the first mandrel and the second mandrel are provided. A first step of switching the rolling direction in the state where no unrolled part of the rolled material is present in each of the mandrels, and after the first step, the rolled material is applied to each of the first mandrel and the second mandrel. A rolling method comprising a second step of switching the rolling direction in the presence of an unrolled portion. 4. The rolling method according to claim 3, wherein when the thickness of the rolled material is thicker than a desired plate thickness, rolling is performed in the first step, and the thickness of the rolled material is a desired plate thickness. A rolling method of rolling in the second step in the case of the following thickness. 5. The rolling method according to claim 3, wherein rolling is performed in the first step from a first pass of a plurality of reversible rollings to a desired pass, and the desired pass of a plurality of reversible rollings is performed. Thereafter, a rolling method of rolling in the second step until the final pass. 6. A reversible finishing mill capable of finish rolling a rolled material in forward and reverse rolling directions, and winding and unwinding of the rolled material upstream of the reversible finishing rolling machine. A first coiler, a hot rolling method by a rolling facility comprising a second coiler capable of winding and unwinding the rolled material on the downstream side of the reversible finish rolling mill, wherein the first coiler and A first step in which the rolling direction is switched in a state in which there is no unrolled part of the rolled material in each of the second coilers; and after the first step, the thickness of the rolled material is less than or equal to a desired thickness. In the above case, the hot rolling method is characterized by comprising a second step of switching the rolling direction in a state where unrolled material of the rolled material exists in each of the first coiler and the second coiler. 7. A reversible rolling machine capable of rolling a rolled material in forward and reverse rolling directions, and a first rewinding and unwinding apparatus for rolling the rolled material upstream of the reversible rolling machine. A rolling facility comprising a coiler and a second coiler capable of winding and unwinding the rolled material on the downstream side of the reversible rolling mill, wherein the rolling direction is switched to at least the final pass among a plurality of reversible rollings. At times, the rolling equipment is provided with a control device for switching and controlling a rolling direction in a state where unrolled material of the rolled material exists in each of the first coiler and the second coiler. 8. Rolling equipment for reversible rolling by a reversible rolling mill disposed between a first and a second coiler capable of winding and unwinding rolled material, the reversible rolling mill performing reversible rolling a plurality of times. When switching the rolling direction to at least the final pass of the rolling, equipped with a control device for switching the rolling direction in the state that there is an unwinding of the rolled material in each of the first coiler and the second coiler, Rolling equipment. 9. A reversible rolling machine capable of rolling a rolled material in forward and reverse rolling directions, and a winding shaft for winding and unwinding the rolled material on the upstream side of the reversible rolling machine. One mandrel, a rolling facility comprising a second mandrel serving as a shaft for winding and unwinding the rolled material on the downstream side of the reversible rolling mill, wherein the first mandrel and the second mandrel are From the first rolling step of rolling by changing the rolling direction in a state in which there is no unrolled material of the rolled material, a state in which unrolled material of the rolled material exists in each of the first mandrel and the second mandrel. A rolling facility equipped with a control device for switching to a second rolling step in which the rolling direction is changed in step 1. 10. The rolling facility according to claim 9, comprising a thickness detection device for measuring or estimating the thickness of the rolled material. 11. The rolling facility according to claim 9, further comprising a thickness detecting device for measuring or estimating the thickness of the rolled material, wherein the controller controls the thickness of the rolled material by the thickness detecting device. Is a control device for switching to the second step when the thickness becomes less than a desired thickness. 12. The rolling facility according to claim 9, wherein each of the first mandrel and the second mandrel is provided with a detection device for detecting an unwound amount of the rolled material. 13. The rolling equipment according to claim 9, wherein each of the first mandrel and the second mandrel is provided with a detection device for detecting an unwound amount of the rolled material, and the control device is configured to Rolling equipment characterized by being a control device that switches to the second step when the unwound amount of the rolled material reaches a desired amount by a detection device that detects the unwound amount. 14. A reversible finish rolling machine capable of finish rolling a rolled material in forward and reverse rolling directions, and winding and unwinding of the rolled material upstream of the reversible finishing rolling machine. A hot rolling facility comprising a first coiler and a second coiler capable of winding and unwinding the rolled material on the downstream side of the reversible finishing mill, wherein the thickness of the rolled material is desired. When the thickness is less than or equal to the thickness, a hot-rolling facility is provided with a control device that switches the rolling direction in a state where unrolled material of the rolled material exists in each of the first coiler and the second coiler. 15. A rolling mill control device for reversible rolling by means of a reversible rolling mill disposed between a first and a second coiler capable of winding and unwinding rolled material. At least at the time of switching the rolling direction to the final pass, the rolling direction is controlled to be switched in a state where unrolled material of the rolled material exists in each of the first and second coilers. 16. A control device of a rolling facility for reversibly rolling with a reversible rolling mill disposed between a first and a second coiler capable of winding and unwinding rolled material, wherein a plurality of the reversible rolling mills are provided. A control characterized by switching the rolling direction in a state in which unrolled parts of the rolled material exist in each of the first coiler and the second coiler at least when switching the rolling direction to the final pass of the reversible rolling. apparatus. 17. A control device of a rolling facility for reversible rolling by a reversible rolling mill arranged between first and second mandrels capable of winding and unwinding rolled material, wherein the first mandrel and the first mandrel are provided. From the first rolling step of rolling by switching the rolling direction in the state where there is no unrolled part of the rolled material on each of the two mandrels, unrolled part of the rolled material on each of the first mandrel and the second mandrel. In the presence of the above, the control device switches to a second rolling step in which the rolling direction is switched and rolling is performed. 18. A control device for hot rolling equipment for reversible rolling by means of a reversible finishing mill disposed between a first and a second coiler capable of winding and unwinding rolled material, said rolling material comprising: If the thickness is less than or equal to a desired thickness, the heat is characterized by including a control device that switches the rolling direction in a state where unrolled material of the rolled material exists in each of the first coiler and the second coiler. Control device for hot rolling equipment.