[invention Title]
Apparatus for endless rolling and method for the same
[Technical Field]
The present disclosure relates to an apparatus and a method for endless rolling, and more particularly, to an apparatus and a method for endless rolling for producing a thin steel sheet rolled coil and a thick steel sheet rolled coil.
[Background Art]
A hot rolling method recently garnering attention is the endless hot rolling method. In general, hot rolling is performed by rolling slabs to one sheet at a time; however, the endless hot rolling method refers to a method for producing steel sheets by continuously rolling slabs and cutting steel sheets formed thereby in front of a coiler. That is, a system for endless hot rolling is equipped with both continuous casting and rolling facilities, and is able to produce a hot-rolled coil,in a single continuous rolling process between a continuous caster and a rolling mill. However, in such a single continuous rolling process between a continuous caster and a rolling mill, a rolling speed may be limited by a casting speed of the continuous caster. Since the casting speed of continuous casters is generally slower than the

rolling speed of rolling mills, the rolling speed of the rolling mills may be reduced to match the relatively slow speed of the continuous casters. Accordingly, a steel sheet entering a rolling mill may be cooled due to moving at a relatively slow speed, and an issue may arise therefrom in that a reference rolling temperature required for rolling may not be secured. In detail, as a thickness of the steel sheet to be produced is increased, the rolling speed may be reduced, and thereby a temperature of the steel sheet may be significantly reduced. Thus, only a thin steel sheet may be produced by using the conventional endless rolling method.
[Related Art Document!
Korean Patent Laid-Open Publication No. 10-2013-0070237 (June 27, 2013)
[Technical Problem]
An exemplary embodiment in the present disclosure may provide an apparatus and a method for endless rolling, continuously producing a thin steel sheet rolled coil and a thick steel sheet rolled coil.
[Technical Solution]
According to an exemplary embodiment in the present disclosure, an apparatus for endless rolling may include a finishing rolling

unit rolling a steel sheet using as many rolling stands from among a plurality of rolling stands as set by a control signal to be input, and processing a thickness of the steel sheet to a target thickness through the rolling of the steel sheet; and a control unit setting the number of rolling stands performing the rolling based on a target thickness to be input, and generating the control signal.
The control unit may reduce the number of rolling stands performing the rolling when the target thickness to be input is increased, and increase the number of rolling stands performing the rolling when the target thickness to be input is reduced.
The finishing rolling unit may withdraw, from the rolling of the steel sheet, the rolling stands from a rolling stand disposed in a rear end of the finishing rolling unit towards a front end thereof based on the control signal.
The finishing rolling unit may increase an interval between the rolling roll withdrawn from the rolling and the steel sheet, and convert the withdrawn rolling stand to a dummy stand. The finishing rolling unit may convert the rolling stand to the dummy stand in response to the input of the control signal when the control signal is input prior to the steel sheet entering an interior of the finishing rolling unit.
When the control signal is input subsequently to the steel sheet entering the finishing rolling unit, the finishing rolling unit may set a virtual dividing line dividing the steel sheet into a steel sheet portion having a first target thickness and a steel

sheet portion having a second target thickness, and when the virtual dividing line is removed from the finishing rolling unit, convert the rolling stand to the dummy stand.
When the control signal is input prior to the steel sheet entering the finishing rolling unit, the finishing rolling unit may move the rolling roll at a predetermined constant speed, and convert the rolling stand to the dummy stand.
When the control signal is input subsequently to the steel sheet entering the finishing rolling unit, in a case in which the interval between the rolling roll and the steel sheet is less than a predetermined minimum interval, the finishing rolling unit may separate the rolling roll and the steel sheet from one another at a predetermined first speed, and in a case in which the interval between the rolling roll and the steel sheet is greater than the minimum interval, separate the rolling roll and the steel sheet from one another at a predetermined second speed.
According to another aspect of the present disclosure, a method for endless rolling may include setting a target thickness of a steel sheet produced through rolling by a finishing rolling unit; setting a number of rolling stands rolling the steel sheet from among a plurality of rolling stands included in the finishing rolling unit based on the target thickness; and increasing an interval between a rolling roll of a rolling stand withdrawn from the rolling and the steel sheet, and converting the withdrawn rolling stand to a dummy stand.

[Advantageous Effects]
According to exemplary embodiments in the present disclosure, the apparatus and the method for endless rolling may produce a thick steel sheet, rolled coil as well as a thin steel sheet rolled coil, and produce the thin and thick steel sheet rolled coils in an alternating manner.
According to the exemplary embodiments in the present disclosure, by using the apparatus and the method for endless rolling, the rolling stand may be converted to the dummy stand during the endless rolling process, such that a process defect rate may be reduced as the number of entries of the steel sheet into the finishing rolling unit is reduced, and a loss in coil production due to ends of the coil being cut may be reduced.
[Brief Description Of Drawings]
FIG. 1 is a (Schematic diagram illustrating an apparatus for endless rolling according to an exemplary embodiment in the present disclosure;
FIG. 2 is a graph illustrating a temperature of a steel sheet based on a position of a finishing rolling mill included in an apparatus for endless rolling according to an exemplary embodiment in the present disclosure;
FIGS. 3A through 3C are schematic diagrams illustrating

operations of an apparatus for endless rolling according to an exemplary embodiment in the present disclosure;
FIGS . 4A and 4B are graphs illustrating dummy stand conversion control in an apparatus for endless rolling according to an exemplary embodiment in the present disclosure; and
FIG. 5 is a flowchart illustrating a method for endless rolling according to an exemplary embodiment in the present disclosure.
[Detailed Description]
Exemplary embodiments in the present disclosure will now be described in detail with reference to the accompanying drawings.
The disclosure may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. It will be further understood that the terms "include" and/or "have," when used in this specification, specify the presence of stated elements, but do not preclude the presence or addition of one or more other elements, unless otherwise described.

FIG. 1 is a schematic diagram illustrating an apparatus for endless rolling according to an exemplary embodiment in the present disclosure.
Referring to FIG. 1, an apparatus for endless rolling according to an exemplary embodiment in the present disclosure may include a finishing rolling unit 10 and a control unit 20. Hereinafter, the apparatus for endless rolling according to the exemplary embodiment in the present disclosure will be described with reference to FIG. 1.
A continuous caster 1 may initially solidify, in a predetermined form, molten steel refined in a steel manufacturing process, .and produce a casting in a form of a semi-finished steel product, such as a slab, a bloom, a billet or an ingot. The steel sheet S may be primarily rolled by a roughing mill 2. A heating unit 3 may heat the steel sheet S, the steel sheet S may be rolled by the finishing rolling mill 10, and the steel sheet S may be formed to have a desired target thickness. The produced steel sheet S may be wound in a form of a coil by a coiler 5. When the winding of the coil is completed, a cutting unit 4 may cut the steel sheet S. Here, according to exemplary embodiments, the roughing mill 2 or the heating unit 3 may be omitted, and the number of rolling stands fl through f5 provided in the finishing rolling mill 10 may vary.
As illustrated in FIG. 1, the apparatus for endless rolling may produce a hot-rolled coil of a steel sheet S in a single

continuous rolling process between the continuous caster 1 and the finishing rolling mill 10. That is, since the steel sheet S is continuously rolled rather than divided into coil units, the coil-may be produced with a consistent quality. However, due to the single continuous rolling process between the continuous caster 1 and the finishing rolling mill 10, a rolling speed may be limited by a casting speed of the continuous caster 1. Since the casting speed of the continuous caster 1 may be slower than that of the finishing rolling mill 10 in general, the rolling speed may also be relatively slow to match the relatively slow speed, of the continuous caster 1. As a result, the steel sheet S entering the finishing rolling mill 10 may be cooled, leading to a failure to secure therein a reference rolling temperature required for rolling.
In detail, rolling speeds of the respective rolling stands
^- Vceast
fl through f5 may be obtained from ip-^ where Vfn denotes a rolling speed of an fn-th rolling stand, and Hfn denotes a thickness of the steel sheet S rolled in the fn-th rolling stand. Also, Qcast denotes mass flow of a semi-finished steel product provided from the continuous caster 1, and may be calculated by multiplying a thickness of the semi-finished steel product and the casting speed. In the above equation, as the thickness of the steel sheet S produced through being rolled in the rolling stands f 1 through f 5 is increased, the rolling speed Vfn may be reduced. Here, as the rolling speed

Vfn falls, a decrease in a temperature of the steel sheet S may thus be significant. In other words, although the single continuous rolling process between the continuous caster 1 and the finishing rolling mill 10 is useful for producing a thin steel sheet, in a case of producing a thick steel sheet, the rolling speed Vfn may be reduced; therefore, securing an appropriate rolling temperature in the finishing rolling unit 10 may be difficult.
Accordingly, the apparatus for endless rolling according to the exemplary embodiment may use all of the rolling stands to roll the thin steel sheet. On the other hand, however, to roll the thick steel sheet, the apparatus for endless rolling may convert from a rolling- stand to a dummy stand in sequence, from a rolling stand disposed in a rear end of the finishing rolling unit 10 towards a front end thereof based on a target thickness, thereby securing an appropriate rolling temperature in the finishing rolling unit 10. In particular, since the apparatus for endless rolling according to the exemplary embodiment is capable of converting the rolling stands fl through f5 to dummy stands during the rolling operation, endless rolling may be performed without cease, even in a case in which thin steel sheets and thick steel sheets are produced in an alternating manner.
In detail, as illustrated in FIG. 1, the finishing rolling unit 10 of- the apparatus for endless rolling according to the exemplary embodiment may include the plurality of rolling stands fl through f5, and adjust the number of rolling stands performing

rolling based on a control signal to be input. In other words, the finishing rolling unit 10 may roll the steel sheet S using the rolling stands, the number of the rolling stands being set based on the control signal to be input, and process the thickness of the steel sheet S to a target thickness.
Here, the finishing rolling unit 10 may withdraw, from the rolling, the rolling stands in sequence, from the rolling stand disposed in the rear end of the finishing rolling unit 10 towards the front end thereof. As described hereinbefore, as the target thickness is increased, the rolling speed may be reduced, and as the rolling speed is reduced, the temperature of the steel sheet S being rolled in the finishing rolling unit 10 may be reduced.
Namely, a temperature distribution of the steel sheet . S entering an interior of the finishing rolling unit 10 may be represented as illustrated in the graph of FIG. 2. In detail, HI, H2, and H3 denote different thicknesses of steel sheets, respectively, and fl through f5 denote the rolling stands, respectively, included in the finishing rolling unit 10. Here, the thicknesses of the steel sheets satisfy HI < H2 < H3, respectively, and as illustrated in FIG. 1, the rolling stands fl through f5 may be sequentially disposed from the front end of the finishing rolling unit 10 to the rear end thereof. As illustrated in FIG. 2, in a case of a relatively thin steel sheet having the thickness Hi, all of the rolling stands fl through f5 satisfy a temperature higher than a reference rolling temperature tO . On the other hand, however.

in a case of. a steel sheet having the thickness H2, the rolling temperature may drop below the reference rolling temperature tO starting from the rolling stand f5, and in a case of the steel sheet having the thickness H3, the rolling temperature may drop below the reference rolling temperature tO starting from the rolling stand f4 . Accordingly, the finishing rolling unit 10 may withdraw, from the rolling, the rolling stands in sequence, from the rolling stand disposed in the rear end of the finishing rolling end 10 towards the front end thereof, based on the target thickness. For example, the finishing rolling unit 10 may perform rolling using all of the rolling stands f1 through f5 with respect to the steel sheet having the thickness HI, whereas the finishing rolling unit 10 may withdraw, from the rolling, the rolling stand f4 from among all of the rolling stands fl through f5 with respect to the steel sheet having the thickness H2, and withdraw, from the rolling, the rolling stands f4 and f5 from among all of the rolling stands fl through f5 with respect to the steel sheet having the thickness H3.
In detail, the finishing rolling unit 10 may adjust a position of a rolling roll included in the rolling stand withdrawn from the rolling, and thereby increase an interval between the rolling roll and the steel sheet S to be greater than a predetermined interval. In this instance, the rolling roll may not be in contact with the steel sheet S, and thus rolling may not be performed on the steel sheet S. Here, the withdrawn rolling stand may be referred to as a dummy stand. The rolling stand may be converted to the dummy stand

by adjusting the position of the rolling roll. That is, as the rolling stand f5 of FIG. 3A,' an interval between the rolling rolls of the rolling stand f5 and the steel sheet S may be increased to be greater than the predetermined interval, and the rolling stand f5 may be converted to the dummy stand.
Here, the conversion to the dummy stand by the finishing rolling unit 10 may be performed in different manners, based on the position of the steel sheet S. In other words, a control signal may be input prior to the steel sheet S entering the finishing rolling unit 10, or the control signal may be input subsequently to the steel sheet S entering the finishing rolling unit 10. Accordingly, control of the rolling roll may vary according to cases.
In detail, as illustrated in FIG. 3A, in a case in which the control signal is input prior to the steel sheet S entering the interior of the finishing rolling unit 10, the rolling stand may bei immediately converted to the dummy stand in response to the input of the control signal. Due to the steel sheet S being prior to entering the finishing rolling unit 10, the effect of the conversion of the.rolling stand to the dummy stand may be absent, and in order to prepare for a subsequent entry of the steel sheet S, the rolling stand may be immediately converted to the dummy stand when the control signal is input.
On the other hand, as illustrated in FIG. 3B, in a case in which the control signal is input subsequently to the steel sheet

S entering the interior of the finishing rolling unit 10', a virtual dividing line P diving the steel sheet S into a first steel sheet
51 portion having a first target thickness and a second steel sheet
52 portion having a second target thickness may be set. As
illustrated in FIG. 3C, when the virtual dividing line P passes
through the rolling stand f4, the rolling stand f4 may be converted
to the dummy stand, and when the virtual diving line P passes through
the rolling stand f5, the rolling stand f5 may be converted to the
dummy stand. Accordingly, both of the rolling stands f4 and f5 may
be controlled to perform rolling with respect to the second steel
sheet S2 portion while both of the rolling stands f4 and f5 may
be controlled to operate as the dummy stands with respect to the
first steel sheet SI portion. Here, in a manner equal thereto, the
manner of controlling the rolling stand may be applied to an instance
in which the dummy stand is converted to the rolling stand.
In addition, in the conversion to the dummy stand, the finishing rolling unit 10 may vary a moving speed of the rolling roll based on the position of the steel sheet S.
In the case that the control signal is input prior to the steel sheet S entering the interior of the finishing rolling unit 10, the rolling stand may be converted to the dummy stand by moving the rolling roll of the rolling stand at a predetermined constant speed. As described hereinbefore, due to the steel sheet S being prior to entering the finishing rolling unit 10, the effect of the conversion to the dummy stand may be absent, such that the rolling

roll may rapidly move at the constant speed and the rolling stand may be converted to the dummy stand.
On the other hand, in the case that the control signal is input subsequently to the steel sheet S entering the interior of the finishing rolling unit 10, issues may arise, such as an impact occurring due to contact between the rolling roll and the steel sheet S, or instability while the steel sheet S is passing through the finishing rolling unit 10 caused by the interval between the steel sheet S and the rolling roll. Thus, in order to prevent such issues, the moving speed of 'the rolling roll may be divided into a plurality of sections to control the operation of the rolling roll.
In detail, as illustrated in FIGS. 4A and 4B, the rolling roll
i
may be controlled by varying the moving speed thereof. Here, a distance between the rolling roll and the steel sheet is referred to as a roll gap g, a distance between the steel sheet and the rolling roll during the rolling operation is referred to as a rolling roll gap gO, and a distance between the steel sheet and the rolling roll while operating as the dummy stand is referred to as a dummy roll gap gl.
As illustrated in FIG. 4A, in a case in which the rolling stand is converted to the dummy stand, the rolling roll may be separated from the steel sheet at a predetermined first speed until the rolling roll gap gO reaches a predetermined minimum gap. That is, in a section in which the rolling roll is in contact with the steel sheet,

the moving speed of the rolling roll may be minimized, and instability in the transfer of the steel sheet caused by an increase of the roll gap may be avoided. When the roll gap is greater than the minimum gap, the rolling stand may be rapidly converted to the dummy stand by moving the rolling roll at a predetermined second speed b. In this instance, as illustrated in FIG. 4A, a < b may be satisfied.
Also, as illustrated in FIG. 4B, in a case in which the dummy stand is converted to the rolling stand, the moving speed of the rolling roll may be controlled through being divided into three sections .until the dummy roll gap gl reaches the rolling gap gO. In detail, the rolling roll may rapidly move to reduce the roll gap at a third speed c, and a fourth speed d may be determined within a range in which the impact occurring due to the contact between the rolling roll and the steel sheet does not influence the transfer of the steel sheet. A fifth speed e may be determined within a range in which the instability in the transfer of the steel sheet caused by the gap decrease is absent. In this instance, as illustrated in FIG. 4B, e < d < c. may be satisfied.
Although FIGS. 4A and 4B illustrate the moving speed control of the rolling roll by dividing the moving speed into the two or three sections, the moving speed of the rolling roll may be controlled by dividing the moving speed into a plurality of sections to be greater than three.
The control unit 20 may set the number of rolling stands fl

through f5 performing rolling based on the target thickness to be input, and generate the control signal corresponding to the set number of rolling stands fl through f5. The target thickness may be input using a 'separate interface by a user, or set based on a predetermined operation schedule. Here, the control unit 20 may reduce the number of rolling stands performing rolling as the target thickness to be input is increased while increasing the number of rolling stands performing rolling as the target thickness to be input is decreased. Since an intensity of rolling pressure is reduced as the target thickness is increased, the intensity of rolling pressure may be adjusted by reducing the number of rolling stands performing rolling. Also, since the intensity of rolling pressure is increased as the target thickness is decreased, the number of rolling stands performing rolling may be increased. However, as described hereinbefore, as the target thickness is increased, the rolling speed may be reduced, and in particular, the rolling temperature may drop below the reference rolling temperature.to in sequence, from the steel sheet S disposed in the rear end of the finishing rolling unit 10 towards the front end thereof. Accordingly, the control unit 20 may control the finishing rolling unit 10 to convert the rolling stands to the dummy stands in sequence, from the rolling stand disposed in the rear end of the finishing rolling unit 10 towards the front end thereof. FIG. 5 is a flowchart illustrating a method for endless rolling according to an exemplary embodiment in the present disclosure.

Referring to FIG. 5, a method for endless rolling according to an exemplary embodiment in the present disclosure may include setting a target thickness SIO, setting rolling stands S20, and converting to a dummy stand S30.
Hereinafter, the method for endless rolling according to the exemplary embodiment in the present disclosure will be described with reference to FIG. 5.
In the setting of the target thickness SIO, the finishing rolling unit may set the target thickness of the steel sheet produced through rolling by the finishing rolling unit. The target thickness may be directly input using a separate interface, or the like, by a user, or set based on a predetermined operation schedule.
In the setting of the rolling stands S20, the number of rolling stands rolling the steel sheet may be set from among the plurality of rolling stands included in the finishing rolling unit, based on the target thickness. In this instance, as the target thickness to be input is increased, the number of rolling stands performing the rolling may be reduced. In other words, since an intensity of rolling pressure required is reduced as the target thickness is increased, the intensity of rolling pressure may be -adjusted by reducing the number of rolling stands performing rolling. However, the rolling speed my fall in the finishing rolling unit as the target thickness is increased, and in particular, the rolling temperature may be reduced below the reference rolling temperature from the steel sheet disposed in the rear end of the finishing rolling unit

towards the front end thereof. Accordingly, the rolling stands may be set.as the rolling stand rolling the steel sheet in sequence, from the rolling stand disposed in the front end of the finishing rolling unit towards the rear end thereof.
In the converting to the dummy stand S30, the interval between the rolling roll of the rolling stand withdrawn from the rolling and the steel sheet may be increased, and the withdrawn rolling stand may be converted to the dummy stand. That is, as the rolling roll of the dummy stand is not in contact with the steel sheet, the dummy stand may no longer perform rolling with respect to the steel sheet. Here, the converting of the dummy stand S30 may be omitted from the rolling process in sequence, from the rolling stand disposed in the rear end of the finishing rolling unit towards the front end thereof.
In particular, in the converting of the dummy stand S30, the conversion to the dummy stand may be performed in different manners based on the position of the steel sheet. Prior to the steel sheet entering the interior of the finishing rolling unit, the rolling stand may be immediately converted to the dummy stand. In this instance, the conversion to the dummy stand may not have direct effect on the steel sheet, thus allowing the immediate conversion from the rolling stand to the dummy stand. On the other hand, subsequently to the steel sheet entering the interior of the finishing rolling unit, the conversion to the dummy stand may be controlled using the virtual dividing line dividing the steel sheet-

into the first steel sheet portion having the first target thickness and the second steel sheet portion having the second target thickness. In detail, when the virtual dividing line passes through the rolling stands, the rolling stands may be converted to dummy stands, such that the rolling stands may perform rolling until the virtual dividing line passes therethrough.
In the converting of the dummy stand S30, the moving speed of the rolling roll may vary based on the position of the steel sheet. Prior to the steel sheet entering, the interior of the finishing rolling unit, the rolling roll may rapidly move at a predetermined constant speed, and the rolling stand may be converted to the dummy stand. On the other hand, subsequently to the steel sheet entering the interior of the finishing rolling unit, there may arise issues such as the impact occurring due to contact between the rolling roll and the steel sheet, or instability in the transfer of the steel sheet caused by the interval between the steel sheet and the rolling roll. Accordingly, to prevent such issues, as illustrated in FIG. 4, the moving speed of the rolling roll may be divided into a plurality of sections to control the rolling roll. Descriptions pertaining to the dividing of the moving speed of the rolling roll into the plurality of sections are provided in the preceding and thus, repeated descriptions will be omitted herein for conciseness.
While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that

modifications and variations could be made without departing from the scope of the present invention as defined by the appended claims.
[Description of Reference Numbers]

continuous caster heating unit coiler
2 : roughing mill
4 : cutting unit
10 : finishing rolling mill
20 : control unit S : steel sheet
SIO- : SET TARGET THICKNESS S20 : SET ROLLING STANDS 330 : CONVERT TO DUMMY STAND

WE CLAIMS:-
An apparatus for endless rolling, comprising: a finishing rolling unit rolling a steel sheet using as many rolling stands from among a plurality of rolling stands as set by a control signal to be input, and precessing a thickness of the steel sheet to a target thickness through the rolling of the sheel sheet; and
a control unit setting the number of rolling stands performing the rolling based on a target thickness to be input, and generating the control signal.
[Claim 2]
The apparatus for endless rolling of claim 1, wherein the control unit reduces the number of rolling stands performing the rolling when the target thickness to be input is increased, and increases the number of rolling stands performing the rolling when the target thickness to be input is reduced.
[Claim 3]
The apparatus for endless rolling of claim 2, wherein the. finishing rolling unit withdraws, from the rolling of the steel sheet, the rolling stands from a rolling stand disposed in a rear end of the finishing rolling unit towards a front end thereof based on the control signal.

IClaim 4]
The apparatus for endless rolling of claim 3, wherein the finishing rolling unit increases an interval between the rolling roll withdrawn from the rolling and the steel sheet, and converts the withdrawn rolling stand to a dummy stand.
[Claim 5l
The apparatus for endless rolling of claim 4, wherein the finishing rolling unit converts the rolling stand to the dummy stand in response to the input of the control signal when the control signal is. input prior to the steel sheet entering an interior of the finishing rolling unit.
[Claim 6l
The apparatus for endless rolling of claim 5, wherein when the control signal is input subsequently to the steel sheet entering the finishing rolling unit, the finishing rolling unit sets a virtual dividing line dividing the steel sheet into a steel sheet portion having -a first target thickness and a steel sheet portion having a second target thickness, and when the virtual dividing line is removed from the finishing rolling unit, converts the rolling stand to the dummy stand.
[Claim 7]

The apparatus for endless rolling of claim 5, wherein when the control signal is input prior to the steel sheet entering the finishing rolling unit, the finishing rolling unit moves the rolling roll at a predetermined constant speed, and converts the rolling stand to the dummy stand.
[Claim 8]
The apparatus for endless rolling of claim 7, wherein when the control signal is input subsequently to the steel sheet entering the finishing rolling unit, in a case in which the interval between the rolling roll and the steel sheet is less than a predetermined minimum interval, the finishing rolling unit separates the rolling roll and the steel sheet from one another at a predetermined first speed, and in a case in which the interval between the rolling roll and the steel sheet is greater than the minimum interval, separates the rolling roll and the steel sheet from one another at a predetermined second speed.
[claim 9]
A method for endless rolling, comprising:
setting a target thickness of a steel sheet produced through rolling by a finishing rolling unit;
setting a number of rolling stands rolling the steel sheet from among a plurality of rolling stands included in the finishing rolling unit based on the target thickness; and

increasing an interval between a rolling roll of a rolling stand withdrawn from the rolling and the steel sheet, and converting the withdrawn rolling stand to a dummy stand.