Control device for rolling device, rolling equipment, and method for operating rolling device

Abstract

This control device for a rolling device is to be used for controlling a rolling device including a pair of rolling rolls provided so as to sandwich a metal plate, and a winding machine for winding the metal plate rolled by the pair of rolling rolls, the control device being configured such that after the distal end part of the metal plate is passed between the pair of rolling rolls in a state in which a gap between the pair of rolling rolls is greater than the plate thickness of the metal plate, the pair of rolling rolls are rotated so that the distal end part of the metal plate reciprocates between the pair of rolling rolls and the winding machine before the distal end part of the metal plate reaches the winding machine, in a state in which a distal-end-part tension applied to the distal end part of the metal plate is zero and in which the metal plate is pressed down by the pair of rolling rolls.

Description

Control device for rolling mill, rolling equipment, and method for operating rolling mill

[0001] The present disclosure relates to a control device for a rolling mill, rolling equipment, and a method for operating a rolling mill.

[0002] In the rolling of metal sheets, it is necessary to improve the yield.

[0003] Patent Document 1 describes a method in which, after the leading end of a metal sheet unwound from an unwinder passes between a pair of rolling rolls, the metal sheet is pressed down and the rolling rolls are started to rotate in a state in which the leading end tension (tension between the pair of rolling rolls and the unwinder) applied to the leading end of the metal sheet is zero. By rolling the metal sheet in this state in which the leading end tension is zero (tip untension state) from the time the leading end of the metal sheet passes through the pair of rolling rolls until it reaches the unwinder, it is possible to roll more of the leading end of the metal sheet compared to when rolling is started in a state in which the leading end of the metal sheet is held by the unwinder, and therefore yield can be improved.

[0004] Patent No. 7119130

[0005] Incidentally, it is believed that the yield can be significantly improved by performing rolling in a state where the tension at the tip end of the metal strip is zero (hereinafter also referred to as tip-tensionless rolling) for each of several rolling passes in a reverse rolling mill. Here, after tip-tensionless rolling, the tip end of the metal strip is gripped by the winder when it reaches the winder. However, if tip-tensionless rolling is performed for each rolling pass, it is necessary to release the grip of the metal strip by the winder before tip-tensionless rolling is performed for each rolling pass from the second pass onwards, and then grip the metal strip again by the winder. This requires time for releasing and gripping the metal strip. Furthermore, once the tip end of the metal strip is gripped by the winder, the tip end of the metal strip is deformed in a bent manner depending on the shape of the gripped portion, etc. Therefore, when the tip end is threaded between the rolling roll and the winder during tip-tensionless rolling from the second pass onwards, the bent portion may get caught on components of the rolling mill, making it difficult to thread the strip smoothly. Therefore, if tension-free rolling of the tip of the metal plate is performed for each rolling pass as described above, there is a risk that production efficiency will decrease.

[0006] In view of the above circumstances, at least one embodiment of the present invention aims to provide a control device for a rolling device, rolling equipment, and a method for operating a rolling device that can effectively improve yield while suppressing a decrease in production efficiency.

[0007] A control device for a rolling mill according to at least one embodiment of the present invention is a control device for controlling a rolling mill including a pair of rolling rolls arranged to sandwich a metal plate, and a winding machine for winding up the metal plate rolled by the pair of rolling rolls, and is configured to rotate the pair of rolling rolls so that the tip of the metal plate moves back and forth between the pair of rolling rolls and the winding machine before the tip of the metal plate reaches the winding machine, after the tip of the metal plate passes between the pair of rolling rolls with the gap between the pair of rolling rolls being larger than the thickness of the metal plate, in a state where the tip tension applied to the tip of the metal plate is zero and the metal plate has been rolled down by the pair of rolling rolls.

[0008] Furthermore, a rolling facility according to at least one embodiment of the present invention comprises: a rolling device including a pair of rolls arranged to sandwich a metal plate therebetween, and a winder for winding up the metal plate rolled by the pair of rolls; and the above-mentioned control device configured to control the rolling device.

[0009] Furthermore, at least one embodiment of a method for operating a rolling mill includes a pair of rolling rolls arranged to sandwich a metal plate therebetween, and a winder for winding up the metal plate rolled by the pair of rolling rolls, and includes: a plate passing step of passing a leading end of the metal plate between the pair of rolling rolls in a state where the gap between the pair of rolling rolls is larger than the thickness of the metal plate; and a rolling step of rotating the pair of rolling rolls so that the leading end of the metal plate reciprocates between the pair of rolling rolls and the winder before the leading end of the metal plate reaches the winder in a state where leading end tension applied to the leading end of the metal plate is zero and the metal plate has been rolled down by the pair of rolling rolls.

[0010] According to at least one embodiment of the present invention, there are provided a control device for a rolling mill, rolling equipment, and a method for operating a rolling mill that can effectively improve yield while suppressing a decrease in production efficiency.

[0011] FIG. 1 is a schematic configuration diagram of a rolling facility equipped with a control device according to an embodiment; FIG. 2 is a flowchart illustrating a method of operating a rolling apparatus according to an embodiment; FIG. 3 is a schematic diagram illustrating a state of a rolling roll and a metal sheet when rolling is started; FIG. 4 is a schematic diagram illustrating a state of a rolling roll and a metal sheet when rolling is started; FIG. 5 is a schematic diagram illustrating a state of a rolling roll and a metal sheet when rolling is started; FIG. 6 is a schematic diagram illustrating a state of a rolling roll and a metal sheet when rolling is started; FIG. 7 is a schematic diagram illustrating a state of a rolling roll and a metal sheet when rolling is started; FIG. 8 is a diagram illustrating a method of operating a rolling apparatus according to an embodiment; FIG. 9 is a diagram illustrating a method of operating a rolling mill according to an embodiment; FIG. 10 is a diagram illustrating a method of operating a rolling mill according to an embodiment; FIG. 11 is a diagram illustrating a method of operating a rolling mill according to an embodiment; FIG. 12 is a diagram illustrating a method of operating a rolling mill according to an embodiment; It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, and are not intended to be limiting unless otherwise specified. It is to be understood that the invention is not limited to the disclosed general description and is not to be construed as limiting unless otherwise specified.

[0012] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples. In the following description, the "entrance side" and "exit side" of a rolling mill or the like refer to the upstream and downstream sides, respectively, of the rolling mill or the like in the traveling direction of the material (metal plate) in the rolling equipment, and are relative terms based on the traveling direction of the material. In other words, when the traveling direction of the material is reversed, the entry side and the exit side are reversed.

[0013] (Configuration of Rolling Facility) First, the overall configuration of a rolling facility including a rolling device according to several embodiments will be described. Fig. 1 is a schematic configuration diagram of a rolling facility equipped with a control device according to one embodiment. As shown in Fig. 1, the rolling facility 1 includes a rolling device 2 and a control device 30 for controlling the rolling device 2.

[0014] 1 is a rolling apparatus (reverse mill) that rolls a metal sheet S that is passed between a pair of roll rolls 16A, 16B by reciprocating the rolls. The rolling apparatus 2 includes a rolling mill 10 including a pair of roll rolls (work rolls) 16A, 16B that are arranged to sandwich the metal sheet S, which is the rolling material, an unwinder 4 that is provided on the entry side of the roll rolls 16A, 16B in the traveling direction of the metal sheet S, and a winder 14 that is provided on the exit side of the roll rolls 16A, 16B in the traveling direction of the metal sheet S, and is configured to roll the metal sheet S with the pair of roll rolls 16A, 16B.

[0015] The rolling mill 10 may include, in addition to a pair of rolls (work rolls) 16A, 16B, a pair of intermediate rolls 18A, 18B and a pair of backup rolls 20A, 20B, which are provided on opposite sides of the pair of rolls 16A, 16B from the metal sheet S. The intermediate rolls 18A, 18B and the backup rolls 20A, 20B are configured to support the rolls 16A, 16B. The rolling mill 10 also includes a reduction device 22 for applying a load to the pair of rolls 16A, 16B to reduce the metal sheet S sandwiched between the outer pair of rolls 16A, 16B. The reduction device 22 may include a hydraulic cylinder.

[0016] A motor 11 is connected to the rolling rolls 16A, 16B via a spindle or the like (not shown), and the rolling rolls 16A, 16B are rotated by the motor 11. When rolling the metal sheet S, the rolling rolls 16A, 16B are rotated by the motor 11 while the metal sheet S is being pressed down by the reduction device 22, thereby generating a frictional force between the rolling rolls 16A, 16B and the metal sheet S, and this frictional force causes the metal sheet S to be sent to the exit side of the rolling rolls 16A, 16B (i.e., the winder 14 side).

[0017] The unwinder 4 is configured to unwind the metal sheet S toward the rolling mill 10. The winder 14 is configured to wind the metal sheet S from the rolling mill 10. The unwinder 4 and the winder 14 are driven by motors 5 and 15, respectively.

[0018] The unwinder 4 is configured to apply an entry-side tension (or tension on the unwinder 4 side; tension between the unwinder 4 and the rolling rolls 16A, 16B) to the metal sheet S when the metal sheet S is rolled. The winder 14 is configured to apply an exit-side tension (or tension on the winder 14 side; tension between the rolling rolls 16A, 16B and the winder 14) to the metal sheet S when the metal sheet S is rolled. That is, by appropriately driving the unwinder 4 and the winder 14 with the motors 5, 15, the entry-side tension and the exit-side tension are applied to the metal sheet S. By appropriately applying the entry-side tension and the exit-side tension to the metal sheet S, it is possible to suppress meandering of the metal sheet S when rolling.

[0019] Incidentally, rolling is stopped just before the tail end of the metal sheet S unwound from the unwinder 4, and when rolling is completed with the metal sheet S pressed down by the rolling rolls 16A, 16B, the metal sheet S is then unwound from the winder 14 toward the rolling mill 10, and rolling is performed by advancing the metal sheet S in the opposite direction to the previous direction while being wound up by the unwinder 4. In other words, the roles of the unwinder 4 and the winder 14 are interchanged depending on the direction of travel of the metal sheet S.

[0020] The rolling device 2 may further include an entrance pinch roll 6 and a side guide 8 for guiding the metal sheet S introduced from the unwinder 4 into the rolling mill 10, and an exit pinch roll 12 for guiding the metal sheet S sent from the rolling mill 10 to the winder 14.

[0021] The rolling device 2 may include a cutter 24 that is provided between the rolling rolls 16A, 16B and the winder 14 and that cuts the metal sheet S.

[0022] Various measuring instruments may also be provided in the rolling mill 2. For example, as shown in Fig. 1, the rolling mill 2 may be provided with a roll-down position sensor 37 for detecting the roll-down positions of the rolls 16A, 16B, and / or a sheet edge position detector 38 for measuring the positions of the edges of the metal sheet S in the width direction at the exit side of the rolls 16A, 16B. Signals indicating the results of measurements by these measuring instruments are sent to the control device 30.

[0023] The control device 30 may receive signals indicating the measurement results from the various measuring instruments described above, and based on these measurement results, control the operation of the motor 11 for driving the rolling rolls 16A, 16B, the motor 5 for driving the unwinder 4, the motor 15 for driving the winder 14, the screw-down device 22, and / or the cutter 24, etc.

[0024] The control device 30 may include a processor (such as a CPU), memory (RAM), an auxiliary storage unit, an interface, etc. The control device 30 receives signals from the various measuring instruments described above via the interface. The CPU is configured to process the signals received in this manner. The CPU is also configured to process programs loaded in the memory.

[0025] The processing contents of the control device 30 may be implemented as a program executed by the CPU and stored in the auxiliary storage unit. When the program is executed, the program is expanded in memory. The CPU reads the program from the memory and executes the instructions contained in the program.

[0026] (Method of operating the rolling mill) Next, an operation method including control of the rolling mill 2 using the above-described control device 30 will be described. The control of the rolling mill 2 described below is control when starting to roll the metal sheet S wound around the unwinder 4. Note that the rolling mill 2 may be operated by manually performing some or all of the processes performed by the control device 30 described below.

[0027] Fig. 2 is a flowchart showing a method for operating the rolling mill 2 according to one embodiment. Figs. 3 to 7 are schematic diagrams each showing the state of the rolls 16A, 16B and the metal sheet S when rolling of the metal sheet S is started under the control of the control device 30.

[0028] In one embodiment, as shown in Fig. 2, the control device 30 first adjusts the positions of the pair of rolls 16A, 16B so that the gap (inter-roll gap) d between the pair of rolls 16A, 16B is larger than the thickness of the metal sheet S (step S2). At this time, the reduction device 22 may be operated as needed to adjust the vertical positions of the pair of rolls 16A, 16B. Then, while maintaining the inter-roll gap larger than the sheet thickness, the leading edge Sa of the metal sheet S (a portion including the leading edge St of the metal sheet S; see Fig. 3) is passed between the pair of rolls 16A, 16B (step S4).

[0029] FIG. 3 is a schematic diagram showing the state of the rolling rolls 16A, 16B and the metal sheet S when step S4 is completed. As shown in FIG. 3, at the completion of step S4, the gap d0 between the pair of rolling rolls 16A, 16B is larger than the thickness H0 of the metal sheet S before rolling, and the leading end Sa of the metal sheet S passes between the rolling rolls 16A, 16B. In addition, the leading end Sa of the metal sheet S is located on the exit side of the rolling rolls 16A, 16B and has not yet reached the winder 14. Therefore, the leading end tension acting on the leading end Sa of the metal sheet S (tension on the winder 14 side) is zero. In addition, at this point, the unwinder 4 is not applying tension to the metal sheet S, so the tension on the unwinder 4 side is also zero.

[0030] Next, with the tension at the tip ends of the metal sheet S being zero, the pair of rolls 16A, 16B roll down the metal sheet S (step S6). In step S6, the roll down device 22 is operated based on the measurement results from the roll down position sensor 37 so that the inter-roll gap becomes a value d1 that is smaller than the thickness H0 of the metal sheet S. Figure 4 is a schematic diagram showing the state of the rolls 16A, 16B and the metal sheet S when step S6 is completed. As shown in Figure 4, the inter-roll gap d1 at the completion of step S6 is smaller than the thickness H0 of the metal sheet S before rolling.

[0031] Then, by rotating the pair of rolls 16A, 16B, rolling is performed in a state where the tension at the tip ends is zero (tip-free rolling) (step S8). In step S8, the current value of the motor 11 for driving the rolls 16A, 16B is appropriately adjusted to rotate the rolls 16A, 16B.

[0032] In step S8, the pair of rolling rolls 16A, 16B may be rotated in the forward direction or the reverse direction. Here, the forward rotation of the rolling rolls 16A, 16B refers to the rotation direction in which the metal sheet S advances from the rolling rolls 16A, 16B toward the winder 14 (the direction of the arrow shown in FIG. 5 ), and the reverse rotation of the rolling rolls 16A, 16B refers to the rotation direction in which the metal sheet S advances from the winder 14 toward the rolling rolls 16A, 16B (the direction of the arrow shown in FIG. 7 ). When the pair of rolling rolls 16A, 16B are rotated in the forward direction in step S8, the metal sheet S advances in the direction of the arrow shown in FIG. 4 .

[0033] In step S8, the pair of rolling rolls 16A, 16B are rotated within a range in which the leading end portion Sa of the metal sheet S is located between the rolling rolls 16A, 16B and the winder 14. During this time, since the leading end portion Sa of the metal sheet S has not reached the winder 14, no tension is applied to the metal sheet S by the winder 14, and the tension at the leading end portion is maintained at zero.

[0034] When the pair of rolling rolls 16A, 16B are rotated, the tension applied to the metal sheet S by the unwinder 4 (tension on the unwinder 4 side) may be set to be greater than zero. This makes it possible to suppress meandering of the metal sheet S when performing tensionless rolling at the tip end.

[0035] 5 is a schematic diagram showing the state of the rolls 16A, 16B and the metal sheet S when the rolls 16A, 16B are rotated in the forward direction to perform rolling in step S8. As shown in FIG. 5, the portion of the metal sheet S that has been reduced by the rolls 16A, 16B and advanced toward the winder 14 of the rolls 16A, 16B has a thickness H1 that is thinner than the thickness H0 before rolling. Note that the thickness of a non-reduced portion 50 of the metal sheet S that has not been reduced by the rolls 16A, 16B remains the same as the thickness H0 before rolling. The non-reduced portion 50 includes the leading end St of the metal sheet S.

[0036] Next, after stopping the rotation of the rolling rolls 16A, 16B, the inter-roll gap between the pair of rolling rolls 16A, 16B is changed to a value d2, which is smaller than the inter-roll gap d1 in steps S6 to S8 (step S10). In step S10, the reduction device 22 is operated based on the measurement results from the reduction position sensor 37 so that the inter-roll gap becomes d2. FIG. 6 is a schematic diagram showing the state of the rolling rolls 16A, 16B and the metal sheet S upon completion of step S10. As shown in FIG. 6, the inter-roll gap d2 at the completion of step S10 is smaller than the thickness H1 of the metal sheet S rolled in step S8 (or the inter-roll gap d1 in step S8).

[0037] Next, the pair of rolls 16A, 16B are rotated in the direction opposite to the direction of rotation in step S8, thereby performing rolling with zero tension at the tip ends (tip-free rolling) (step S12, FIG. 7). In step S12, the current value of the motor 11 for driving the rolls 16A, 16B is appropriately adjusted to rotate the rolls 16A, 16B.

[0038] If the pair of rolls 16A, 16B are rotated in the forward direction in step S8 (see FIG. 5), then the pair of rolls 16A, 16B are rotated in the reverse direction in step S12. In this case, the metal sheet S advances in the direction of the arrow shown in FIG. 7 (the direction from the winder 14 toward the rolls 16A, 16B). Note that if the pair of rolls 16A, 16B are rotated in the reverse direction in step S8, then the pair of rolls 16A, 16B are rotated in the forward direction in step S12.

[0039] In step S12, the pair of rolling rolls 16A, 16B are rotated within a range in which the leading end Sa of the metal sheet S is located between the rolling rolls 16A, 16B and the winder 14. During this time, the leading end Sa of the metal sheet S has not reached the winder 14, so no tension is applied to the metal sheet S by the winder 14, and the tension at the leading end is maintained at zero.

[0040] When the pair of rolling rolls 16A, 16B are rotated, the tension applied to the metal sheet S by the unwinder 4 (tension on the unwinder 4 side) may be set to be greater than zero. This makes it possible to suppress meandering of the metal sheet S when performing tensionless rolling at the tip end.

[0041] 7 is a schematic diagram showing the state of the rolls 16A, 16B and the metal sheet S when the rolls 16A, 16B are rotated in the reverse direction to perform rolling in step S12. As shown in Fig. 7, the portion of the metal sheet S that has been reduced by the rolls 16A, 16B and advanced toward the unwinder 4 of the rolls 16A, 16B has a thickness H2 that is thinner than the thickness H1 of the metal sheet S rolled in step S8. Note that the thickness of the non-reduced portion 50 of the metal sheet S that has not been reduced by the rolls 16A, 16B remains the thickness H0 before rolling.

[0042] After step S12, the metal sheet S is transported so that the leading end portion Sa of the metal sheet S reaches the winding machine 14. At this time, the metal sheet S may be transported while being rolled. When the leading end portion Sa of the metal sheet S reaches the winding machine 14, the leading end portion Sa is gripped by the winding machine 14 (step S16). Then, while the metal sheet S is being wound by the winding machine 14 and tension (tension on the winding machine 14 side, i.e., delivery tension) is applied to the metal sheet S by the winding machine 14, the rolling rolls 16A, 16B are rotated to perform rolling (step S18).

[0043] After the tip end is tension-free rolled in step S12, the non-rolled portion 50 of the metal sheet S may be cut off using the cutter 24 (see FIG. 1) before the tip end Sa is gripped by the winder 14 in step S16 (step S14).

[0044] In the above-described embodiment, after the leading edge portion Sa of the metal sheet S is passed between the pair of rolling rolls 16A, 16B in steps S2 to S4, the leading edge portion Sa of the metal sheet S is rolled by reciprocating (i.e., moving in both directions) between the pair of rolling rolls 16A, 16B and the winder 14 in a state where the leading edge tension applied to the leading edge portion Sa of the metal sheet S is zero (i.e., in a state where the leading edge is not tensioned) (steps S6 to S12). Therefore, similar to the case where unidirectional rolling without leading edge tension is performed for each rolling pass, the yield can be improved. Furthermore, by rolling the leading edge portion Sa of the metal sheet S in a state where the leading edge portion Sa of the metal sheet S is not tensioned, the thickness of the metal sheet S can be significantly reduced before the leading edge portion Sa of the metal sheet S is gripped by the winder 14 and the metal sheet S is wound up. Therefore, from the second pass onwards, the metal sheet S can be rolled while maintaining the state where the metal sheet S is gripped by the winder 14. Therefore, unlike when unidirectional tip tension-free rolling is performed for each rolling pass, there is no need to release or re-grapple the metal sheet S with the winder 14 before and after tip tension-free rolling, and the time required for releasing and gripping the metal sheet S can be shortened. Furthermore, while the tip portion Sa of the metal sheet S is rolled by reciprocating the winder 14 in a tip tension-free state, the tip portion Sa of the metal sheet S is not gripped by the winder 14, so the tip portion Sa of the metal sheet S is not deformed by gripping. Therefore, while the tip portion Sa of the metal sheet S is rolled by reciprocating the winder 14 in a tip tension-free state, the threading of the tip portion Sa of the metal sheet S between the rolling rolls 16A, 16B and the winder 14 is not easily hindered, so the time required for threading the tip portion Sa of the metal sheet S can be shortened. Therefore, according to the above-described embodiment, it is possible to effectively improve the yield while suppressing a decrease in production efficiency.

[0045] In one embodiment, when rolling the tip portion Sa of the metal sheet S by reciprocating between the pair of rolling rolls 16A, 16B and the winder 14 in a state where the tip portion tension applied to the tip portion Sa of the metal sheet S is zero (steps S6 to S12), first, in step S8, the pair of rolling rolls 16A, 16B may be rotated so that the metal sheet S progresses in a direction from the winder 14 toward the pair of rolling rolls 16A, 16B (i.e., the rolling rolls 16A, 16B may be rotated in the reverse direction), and then, in step S10, the pair of rolling rolls 16A, 16B may be rotated so that the metal sheet S progresses in a direction from the pair of rolling rolls 16A, 16B toward the winder 14 (i.e., the rolling rolls 16A, 16B may be rotated in the forward direction).

[0046] An example of an operating procedure according to the embodiment will be described with reference to Figures 8a to 8g, each of which is a diagram for explaining a method of operating a rolling mill according to one embodiment.

[0047] In one embodiment, first, the positions of the pair of rolls 16A, 16B are adjusted so that the gap (roll gap) d between the pair of rolls 16A, 16B is larger than the thickness of the metal sheet S (step S2), and the leading end Sa of the metal sheet S is passed between the pair of rolls 16A, 16B (step S4) ( FIG. 8 a). Then, the metal sheet S is unwound by the unwinder 4 so that the leading end Sa of the metal sheet S is located near the winder 14 ( FIG. 8 b). Note that in the procedure up to this point, the metal sheet S has not yet been rolled down, and the roll gap is larger than the thickness H0 of the metal sheet S, so the thickness of the metal sheet S is the thickness H0 before rolling.

[0048] Next, the gap between the rolling rolls 16A and 16B is changed to d1, which is smaller than the thickness H0 of the metal sheet S, and the metal sheet S is rolled down (step S6, FIG. 8c). Then, by rotating the pair of rolling rolls 16A and 16B in opposite directions, the metal sheet S is advanced from the winder 14 toward the rolling rolls 16A and 16B, and subjected to tensionless tip rolling (step S8). At this time, the thickness of the portion of the metal sheet S that was rolled in step S8 (the portion closer to the unwinder 4 than the rolling rolls 16A and 16B) becomes a thickness H1, which is thinner than the thickness H0 before rolling (see FIG. 8d). Furthermore, the thickness of the portion of the metal sheet S that was not rolled in step S8 (the portion closer to the winder 14 than the rolling rolls 16A and 16B) remains the thickness H0 before rolling. When the leading edge Sa of the metal sheet S approaches the rolling rolls 16A, 16B, the rotation of the rolling rolls 16A, 16B is stopped (FIG. 8d). At this time, the portion of the metal sheet S closer to the winder 14 than the rolling rolls 16A, 16B is a non-reduced portion 50 that has not been reduced by the rolling rolls 16A, 16B, and has a thickness H0.

[0049] Next, the gap between the rolls 16A and 16B is changed to d2, which is smaller than the inter-roll gap d1 in steps S6 to S8, and the metal sheet S is rolled down (step S10). Then, by rotating the pair of rolls 16A and 16B in the forward direction, the metal sheet S is advanced from the rolls 16A and 16B toward the winder 14, and subjected to tensionless tip rolling (step S12, FIG. 8e). At this time, the thickness of the portion of the metal sheet S rolled in step S10 (the portion located closer to the winder 14 than the rolls 16A and 16B (excluding the non-rolled down portion 50)) becomes a thickness H2, which is thinner than the thickness H1 after rolling in step S8 (see FIG. 8e). Furthermore, the thickness of the portion of the metal sheet S that was rolled in step S8 but not rolled in step S10 (the portion located closer to the unwinder 4 than the rolls 16A and 16B) remains the same as the thickness H1.

[0050] Here, once the non-reduced portion 50 of the metal sheet S (the portion including the tip St) has passed through the cutter 24, the non-reduced portion 50 may be cut off from the metal sheet S by the cutter 24 (step S14, FIG. 8e). This allows the thickness of the tip portion Sa including the tip St' after cutting of the metal sheet S to be set to the thickness H2 after rolling in step S10 (see FIG. 8f).

[0051] After the non-rolled portion 50 is cut off in step S14, the pair of rolling rolls 16A, 16B may be rotated in the forward direction until the leading end Sa of the metal sheet S reaches the winding machine 14, thereby performing tensionless leading end rolling of the metal sheet S (step S12, Figure 8f).

[0052] When the leading end portion Sa of the metal sheet S reaches the winding machine 14, the winding machine 14 grips the leading end portion Sa (step S16, FIG. 8g). Thereafter, while the metal sheet S is being wound by the winding machine 14 and tension (tension on the winding machine 14 side, i.e., delivery tension) is applied to the metal sheet S by the winding machine 14, the rolling rolls 16A, 16B are rotated to perform rolling.

[0053] In the above-described embodiment, the metal sheet S is rolled while being advanced in a direction from the winder 14 toward the rolling rolls 16A, 16B in a state where there is no tension at the tip end (step S8), and then the metal sheet S is rolled while being advanced in a direction from the rolling rolls 16A, 16B toward the winder 14 (step S10). Thereafter, the tip end portion Sa of the metal sheet S located near the winder 14 can be gripped by the winder 14, and normal rolling can be started early. Therefore, it is possible to effectively improve the yield while more effectively suppressing a decrease in production efficiency.

[0054] In one embodiment, when rolling the tip portion Sa of the metal sheet S by reciprocating between the pair of rolling rolls 16A, 16B and the winder 14 in a state where the tip portion tension applied to the tip portion Sa of the metal sheet S is zero (steps S6 to S12), first, in step S8, the pair of rolling rolls 16A, 16B may be rotated so that the metal sheet S progresses in a direction from the pair of rolling rolls 16A, 16B toward the winder 14 (i.e., the rolling rolls 16A, 16B may be rotated in the forward direction), and then, in step S10, the pair of rolling rolls 16A, 16B may be rotated so that the metal sheet S progresses in a direction from the winder 14 toward the pair of rolling rolls 16A, 16B (i.e., the rolling rolls 16A, 16B may be rotated in the reverse direction).

[0055] An example of an operating procedure according to the embodiment will be described with reference to Figures 9a to 9g, each of which is a diagram for explaining a method of operating a rolling mill according to one embodiment.

[0056] In one embodiment, first, the positions of the pair of rolls 16A, 16B are adjusted so that the gap (roll gap) d between the pair of rolls 16A, 16B is larger than the thickness of the metal sheet S (step S2), and the leading end Sa of the metal sheet S is passed between the pair of rolls 16A, 16B (step S4) ( FIG. 9 a). The leading end Sa of the metal sheet S is positioned near the rolls 16A, 16B on the exit side of the rolls 16A, 16B. In the procedure up to this point, the metal sheet S has not yet been rolled down, and the roll gap is larger than the thickness H0 of the metal sheet S, so the thickness of the metal sheet S is the thickness H0 before rolling.

[0057] Next, the gap between the rolls 16A and 16B is changed to d1, which is smaller than the thickness H0 of the metal sheet S, and the metal sheet S is rolled down (step S6, FIG. 8b). Then, by rotating the pair of rolls 16A and 16B in the forward direction, the metal sheet S is advanced from the rolls 16A and 16B toward the winder 14, and subjected to tensionless tip rolling (step S8). At this time, the thickness of the portion of the metal sheet S that was rolled in step S8 (the portion closer to the winder 14 than the rolls 16A and 16B) becomes a thickness H1, which is thinner than the thickness H0 before rolling (see FIG. 9c). Meanwhile, the thickness of the portion of the metal sheet S that was not rolled in step S8 (the portion closer to the unwinder 4 than the rolls 16A and 16B) remains the thickness H0 before rolling. When the leading end Sa of the metal sheet S approaches the winder 14, the rotation of the rolling rolls 16A, 16B is stopped (FIG. 9c). At this time, the portion of the metal sheet S closer to the leading end St than the portion rolled in step S8 is a non-reduced portion 50 that has not been reduced by the rolling rolls 16A, 16B, and has a thickness H0.

[0058] Next, the gap between the rolls 16A, 16B is changed to d2, which is smaller than the inter-roll gap d1 in steps S6 to S8, and the metal sheet S is pressed down (step S10). Then, the pair of rolls 16A, 16B are rotated in opposite directions, and the metal sheet S is subjected to tensionless tip rolling while advancing from the winder 14 toward the rolls 16A, 16B (step S12, FIG. 9d). At this time, the thickness of the portion of the metal sheet S rolled in step S10 (the portion located closer to the unwinder 4 than the rolls 16A, 16B) becomes a thickness H2, which is thinner than the thickness H1 after rolling in step S8 (see FIG. 9d).

[0059] Next, the gap between the rolls 16A and 16B is changed to d3, which is smaller than the inter-roll gap d2 in steps S10 to S12, and the metal sheet S is pressed down. Then, by rotating the pair of rolls 16A and 16B in the forward direction, the metal sheet S is advanced from the rolls 16A and 16B toward the winder 14, and tension-free rolling without the tip is performed ( FIG. 9e ). At this time, the thickness of the portion of the metal sheet S closer to the winder 14 than the rolls 16A and 16B becomes a thickness H3, which is thinner than the thickness H2 of the metal sheet S rolled in step S12 (see FIG. 9e ). Furthermore, the thickness of the portion of the metal sheet S closer to the unwinder 4 than the rolls 16A and 16B remains the same as the thickness H2 of the metal sheet S rolled in step S12.

[0060] Here, once the non-reduced portion 50 of the metal sheet S (the portion including the tip St) has passed through the cutter 24, the non-reduced portion 50 may be cut off from the metal sheet S by the cutter 24 (step S14, FIG. 9e). This allows the thickness of the tip portion Sa including the tip St' after cutting of the metal sheet S to be set to the thickness H3 after rolling at the roll gap d3 (see FIG. 9f).

[0061] After the non-rolled portion 50 is cut off in step S14, the pair of rolling rolls 16A, 16B may be rotated in the forward direction until the leading end Sa of the metal sheet S reaches the winding machine 14, thereby performing tensionless leading end rolling of the metal sheet S (FIG. 9f).

[0062] When the leading end portion Sa of the metal sheet S reaches the winding machine 14, the winding machine 14 grips the leading end portion Sa (step S16, FIG. 9g). Thereafter, while the metal sheet S is being wound by the winding machine 14 and tension (tension on the winding machine 14 side, i.e., delivery tension) is applied to the metal sheet S by the winding machine 14, the rolling rolls 16A, 16B are rotated to perform rolling.

[0063] In the above-described embodiment, the metal sheet S is rolled while proceeding in a direction from the rolling rolls 16A, 16B toward the winder 14 in a state where there is no tension at the tip end (S8), and then, before the tip portion Sa of the metal sheet S reaches the winder 14, the metal sheet S is rolled while proceeding in a direction from the winder 14 toward the rolling rolls 16A, 16B. Thereafter, by again proceeding and rolling the metal sheet S in a state where there is no tension at the tip end in a direction from the rolling rolls 16A, 16B toward the winder 14 (see FIGS. 9e to 9g), the thickness of the metal sheet S can be further reduced before winding of the metal sheet S begins. Therefore, the yield can be more effectively improved.

[0064] As described above, in some embodiments, after rotating the pair of rolling rolls 16A, 16B so that the tip portion Sa of the metal sheet S moves back and forth between the pair of rolling rolls 16A, 16B and the winding machine 14 (steps S6 to S12), the non-reduced portion 50 of the metal sheet S that has not been reduced by the pair of rolling rolls 16A, 16B may be cut off by a cutting machine 24.

[0065] 10 and 11 are schematic diagrams showing the winder 14 and the metal sheet at the start of winding the metal sheet S. When the leading end Sa of the metal sheet S is passed between a pair of rolling rolls 16A, 16B and then rolled down by the rolling rolls 16A, 16B and the rotation of the rolling rolls 16A, 16B is started, a non-rolled down portion 50 of the metal sheet S (a portion including the leading end St of the metal sheet S) located on the outlet side of the rolling rolls 16A, 16B when the rolling rolls 16A, 16B start to rotate is not rolled down by the rolling rolls 16A, 16B even after the rolling rolls 16A, 16B start to rotate, and therefore the thickness H0 before rolling (a thickness greater than the thickness of the portion to be rolled (e.g., H1)) is maintained. 10, when the metal sheet S is wound by a winding machine 14 after tension-free rolling at the tip end, a step 54 between the first and second turns of the metal sheet S becomes large in the winding machine 14. This step can cause tension fluctuations during rolling of the metal sheet S and machine vibrations due to the tension fluctuations.

[0066] In this regard, by cutting off the non-reduction portion 50 having a large thickness after tension-free rolling of the tip of the metal sheet S as in the above-described embodiment, the thickness of the tip portion Sa including the tip St' of the metal sheet S after cutting off the non-reduction portion 50 becomes a thickness after rolling (e.g., H1) that is smaller than the thickness H0 before rolling. As a result, as shown in FIG. 11 , the step 54 between the first and second turns of the metal sheet S in the winding machine 14 can be reduced. This makes it possible to suppress tension fluctuations caused by the step 54 and machine vibrations resulting therefrom. Therefore, it is possible to effectively improve yield while suppressing degradation of product quality due to tension fluctuations and the occurrence of breakdowns due to machine vibrations, and also suppressing a decrease in production efficiency.

[0067] The contents described in each of the above embodiments can be understood, for example, as follows.

[0068] [1] A control device (30) for a rolling mill according to at least one embodiment of the present invention is a control device for controlling a rolling mill (2) including a pair of rolling rolls (16A, 16B) arranged to sandwich a metal sheet (S) therebetween, and a winder (14) for winding up the metal sheet rolled by the pair of rolling rolls, and is configured to rotate the pair of rolling rolls so that the tip of the metal sheet reciprocates between the pair of rolling rolls and the winder before the tip of the metal sheet reaches the winder, in a state in which the gap between the pair of rolling rolls is larger than the thickness of the metal sheet, and after the tip tension applied to the tip of the metal sheet is zero and the metal sheet is rolled down by the pair of rolling rolls.

[0069] In the configuration [1] described above, after the leading end of the metal sheet is passed between a pair of rolling rolls, the leading end of the metal sheet is rolled by reciprocating between the pair of rolling rolls and the winder in a state in which the leading end tension applied to the leading end of the metal sheet is zero (i.e., in a state in which the leading end is not tensioned). Therefore, similar to the case in which unidirectional tip-tensionless rolling is performed for each rolling pass, the yield can be improved. Furthermore, by rolling the leading end of the metal sheet by reciprocating in a state in which the leading end is not tensioned, the thickness of the metal sheet can be significantly reduced before the leading end of the metal sheet is gripped by the winder and the metal sheet is wound. Therefore, from the second pass onward, the metal sheet can be rolled while the winder maintains the gripped state of the metal sheet. Therefore, unlike the case in which unidirectional tip-tensionless rolling is performed for each rolling pass, it is not necessary to release or re-grip the metal sheet by the winder before and after tip-tensionless rolling, and the time required for releasing and gripping the metal sheet can be shortened. Furthermore, since the leading end of the metal sheet is not gripped by the winder while the leading end of the metal sheet is rolled by reciprocating the rolling roll without tension at the leading end, the leading end of the metal sheet is not deformed by gripping. Therefore, while the leading end of the metal sheet is rolled by reciprocating the rolling roll without tension at the leading end, the threading of the leading end of the metal sheet between the rolling roll and the winder is not easily hindered, and the time required for threading the leading end of the metal sheet can be shortened. Therefore, according to the configuration [1] above, it is possible to effectively improve yield while suppressing a decrease in production efficiency.

[0070] [2] In some embodiments, in the configuration of [1] above, the control device is configured to rotate the pair of rolling rolls so that the metal sheet advances in a direction from the winder toward the pair of rolling rolls when the tip tension is zero and the metal sheet is pressed down by the pair of rolling rolls, and then rotate the pair of rolling rolls so that the metal sheet advances in a direction from the pair of rolling rolls toward the winder.

[0071] According to the configuration [2] above, the metal sheet is rolled while being advanced in a direction from the winder toward the rolling roll in a state where there is no tension at the tip end, and then the metal sheet is rolled while being advanced in a direction from the rolling roll toward the winder, so that the tip end of the metal sheet located near the winder can be gripped by the winder, and normal rolling can be started early. Therefore, it is possible to effectively improve the yield while more effectively suppressing a decrease in production efficiency.

[0072] [3] In some embodiments, in the configuration of [1] or [2] above, the control device is configured to rotate the pair of rolling rolls so that the metal plate advances from the pair of rolling rolls toward the winder when the leading end tension is zero and the metal plate is rolled down by the pair of rolling rolls, and then rotate the pair of rolling rolls so that the metal plate advances from the winder toward the pair of rolling rolls before the leading end of the metal plate reaches the winder.

[0073] According to the configuration [3] above, the metal sheet is rolled while traveling in a direction from the rolling roll toward the winder in a state where there is no tension at the tip end, and then, before the tip end of the metal sheet reaches the winder, the metal sheet is rolled while traveling in a direction from the winder toward the rolling roll, so that by subsequently traveling and rolling the metal sheet again in a state where there is no tension at the tip end in a direction from the rolling roll toward the winder, the thickness of the metal sheet can be further reduced before winding of the metal sheet begins, thereby more effectively improving yield.

[0074] [4] In some embodiments, in any of the configurations [1] to [3] above, the rolling device includes a cutter (24) provided between the pair of rolling rolls and the winder for cutting the metal plate, and the control device is configured to rotate the pair of rolling rolls so that the tip of the metal plate reciprocates between the pair of rolling rolls and the winder, and then use the cutter to cut off the non-reduced portion (50) of the metal plate that has not been reduced by the pair of rolling rolls.

[0075] When the leading end of a metal sheet is passed between a pair of rolls and then rolled down by the rolls to start rotation, the non-rolled portion of the metal sheet located on the outlet side of the rolls at the start of rotation of the rolls is not rolled down by the rolls even after the rolls start rotating, and therefore maintains its thickness before reduction (thicker than the rolled portion). Therefore, when the metal sheet is wound on a winding machine after tension-free rolling of the leading end, a step between the first and second turns of the metal sheet becomes large on the winding machine. This step can cause tension fluctuations during rolling of the metal sheet and machine vibrations due to the tension fluctuations. According to the configuration [4] above, the non-rolled portion with a larger thickness is removed after tension-free rolling of the leading end of the metal sheet, thereby reducing the step between the first and second turns of the metal sheet on the winding machine. This suppresses tension fluctuations and resulting machine vibrations due to the step. Therefore, it is possible to effectively improve yield while suppressing deterioration in product quality due to tension fluctuations and occurrence of breakdowns due to machine vibrations, and while suppressing a decrease in production efficiency.

[0076] [5] A rolling facility (1) according to at least one embodiment of the present invention comprises: a rolling device (2) including a pair of rolling rolls (16A, 16B) arranged to sandwich a metal sheet (S) therebetween, and a winder (14) for winding up the metal sheet rolled by the pair of rolling rolls; and a control device (30) according to any one of the above [1] to [4] configured to control the rolling device.

[0077] In the configuration [5] above, after the leading end of the metal sheet is passed between a pair of rolling rolls, the leading end of the metal sheet is rolled by reciprocating between the pair of rolling rolls and the winder in a state where the leading end tension applied to the leading end of the metal sheet is zero (i.e., in a state where the leading end is not tensioned). Therefore, similar to the case where unidirectional tip-tensionless rolling is performed for each rolling pass, the yield can be improved. Furthermore, by rolling by reciprocating in a state where the leading end of the metal sheet is not tensioned, the thickness of the metal sheet can be significantly reduced before the leading end of the metal sheet is gripped by the winder and the metal sheet is wound. Therefore, from the second pass onwards, the metal sheet can be rolled while the winder maintains the gripped state of the metal sheet. Therefore, unlike the case where unidirectional tip-tensionless rolling is performed for each rolling pass, it is not necessary to release or re-grip the metal sheet by the winder before and after tip-tensionless rolling, and the time required for releasing and gripping the metal sheet can be shortened. Furthermore, since the leading end of the metal sheet is not gripped by the winder while the leading end of the metal sheet is rolled by reciprocating the rolling roll without tension at the leading end, the leading end of the metal sheet is not deformed by gripping. Therefore, while the leading end of the metal sheet is rolled by reciprocating the rolling roll without tension at the leading end, the threading of the leading end of the metal sheet between the rolling roll and the winder is not easily hindered, and the time required for threading the leading end of the metal sheet can be shortened. Therefore, according to the configuration [5] above, it is possible to effectively improve yield while suppressing a decrease in production efficiency.

[0078] [6] According to at least one embodiment of the present invention, there is provided a rolling facility comprising: a rolling device including a pair of rolling rolls arranged to sandwich a metal plate, a winding machine for winding up the metal plate rolled by the pair of rolling rolls, and a cutter (24) arranged between the pair of rolling rolls and the winding machine for cutting the metal plate; and the control device described in [4] above, which is configured to control the rolling device.

[0079] According to the configuration [6] above, after tension-free rolling of the leading end of the metal sheet, the non-reduction portion with a large thickness is removed, so that the step between the first and second turns of the metal sheet in the winding machine can be reduced. This makes it possible to suppress tension fluctuations caused by the step and the resulting machine vibrations. Therefore, it is possible to effectively improve yield while suppressing deterioration of product quality due to tension fluctuations and the occurrence of breakdowns due to machine vibrations, and also suppressing a decrease in production efficiency.

[0080] [7] A method for operating a rolling mill (2) according to at least one embodiment of the present invention is a method for operating a rolling mill (2) including a pair of rolling rolls (16A, 16B) arranged to sandwich a metal sheet (S) therebetween, and a winder (14) for winding up the metal sheet rolled by the pair of rolling rolls, the method comprising: a plate passing step (S4) of passing a leading end (Sa) of the metal sheet between the pair of rolling rolls in a state in which a gap between the pair of rolling rolls is larger than a thickness of the metal sheet; and a rolling step (S8, S12) of rotating the pair of rolling rolls in a state in which leading end tension applied to the leading end of the metal sheet is zero and in a state in which the metal sheet has been rolled down by the pair of rolling rolls, so that the leading end of the metal sheet reciprocates between the pair of rolling rolls and the winder before the leading end of the metal sheet reaches the winder.

[0081] In the method [7] above, after the leading end of the metal sheet is passed between a pair of rolling rolls, the leading end of the metal sheet is rolled by reciprocating between the pair of rolling rolls and the winder in a state in which the leading end tension applied to the leading end of the metal sheet is zero (i.e., in a state of no leading end tension). Therefore, similar to the case in which unidirectional rolling without leading end tension is performed for each rolling pass, the yield can be improved. Furthermore, by rolling the metal sheet by reciprocating in a state of no leading end tension, the thickness of the metal sheet can be significantly reduced before the leading end of the metal sheet is gripped by the winder and the metal sheet is wound up. Therefore, from the second pass onward, the metal sheet can be rolled while maintaining the grip of the metal sheet by the winder. Therefore, unlike the case in which unidirectional rolling without leading end tension is performed for each rolling pass, it is not necessary to release or re-grip the metal sheet by the winder before and after rolling without leading end tension, and the time required for releasing and gripping the metal sheet can be shortened. Furthermore, since the leading end of the metal sheet is not gripped by the winder while the leading end of the metal sheet is rolled by reciprocating the roll without tension at the leading end, the leading end of the metal sheet is not deformed by gripping. Therefore, while the leading end of the metal sheet is rolled by reciprocating the roll without tension at the leading end, the threading of the leading end of the metal sheet between the rolling roll and the winder is not easily hindered, and the time required for threading the leading end of the metal sheet can be shortened. Therefore, according to the method [7] above, it is possible to effectively improve the yield while suppressing a decrease in production efficiency.

[0082] [8] In some embodiments, the method of [7] above further comprises a step (S14) of cutting the metal plate after the rolling step so as to remove a non-reduced portion of the metal plate that has not been reduced by the pair of rolling rolls.

[0083] According to the method [8] above, after tension-free rolling of the tip of the metal sheet, the non-reduction portion with a large thickness is removed, so that the step between the first and second turns of the metal sheet on the winding machine can be reduced. This makes it possible to suppress tension fluctuations caused by the step and the resulting machine vibrations. Therefore, it is possible to effectively improve yield while suppressing deterioration of product quality due to tension fluctuations and the occurrence of breakdowns due to machine vibrations, and also suppressing a decrease in production efficiency.

[0084] The above describes an embodiment of the present invention, but the present invention is not limited to the above-described embodiment, and also includes forms in which the above-described embodiment is modified, or forms in which these forms are appropriately combined.

[0085] In this specification, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions expressing that things are in an equal state, such as "identical," "equal," and "homogeneous," not only express a state in which there is a strict equivalence, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions expressing shapes such as a rectangular shape or a cylindrical shape not only express shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0086] REFERENCE SIGNS LIST 1 Rolling equipment 2 Rolling mill 4 Unwinder 5 Motor 6 Entry pinch roll 8 Side guide 10 Rolling mill 11 Motor 12 Exit pinch roll 14 Winder 15 Motor 16A Rolling roll 16B Rolling roll 18A Intermediate roll 18B Intermediate roll 20A Backup roll 20B Backup roll 22 Screw down device 24 Cutting machine 30 Control device 37 Screw down position sensor 38 Sheet edge position detector 50 Non-reduction portion 54 Step H0 to H3 Sheet thickness S Metal sheet Sa Tip portion St, St' Tip d1 to d3 Gap between rolls

Claims

1. A control device for a rolling mill including a pair of rolling rolls arranged to sandwich a metal plate therebetween, and a winder for winding up the metal plate rolled by the pair of rolling rolls, the control device being configured to rotate the pair of rolling rolls so that the leading edge of the metal plate reciprocates between the pair of rolling rolls and the winder before the leading edge of the metal plate reaches the winder, after the leading edge of the metal plate has passed between the pair of rolling rolls with the gap between the pair of rolling rolls being larger than the thickness of the metal plate, in a state where the leading edge tension applied to the metal plate is zero and the metal plate has been rolled down by the pair of rolling rolls.

2. A control device for a rolling mill according to claim 1, configured to rotate the pair of rolling rolls so that the metal sheet advances in a direction from the winder toward the pair of rolling rolls when the tension at the tip end is zero and the metal sheet is being pressed down by the pair of rolling rolls, and then rotate the pair of rolling rolls so that the metal sheet advances in a direction from the pair of rolling rolls toward the winder.

3. A control device for a rolling mill according to claim 1 or 2, configured to rotate the pair of rolling rolls so that the metal sheet advances from the pair of rolling rolls toward the winder when the tension at the leading end portion is zero and when the metal sheet is being pressed down by the pair of rolling rolls, and then rotate the pair of rolling rolls so that the metal sheet advances from the winder toward the pair of rolling rolls before the leading end portion of the metal sheet reaches the winder.

4. A control device for a rolling mill as set forth in claim 1 or 2, wherein the rolling mill includes a cutter provided between the pair of rolling rolls and the winder for cutting the metal plate, and is configured such that after the pair of rolling rolls are rotated so that the leading end of the metal plate reciprocates between the pair of rolling rolls and the winder, the non-reduced portion of the metal plate that has not been reduced by the pair of rolling rolls is cut off by the cutter.

5. A rolling facility comprising: a rolling device including a pair of rolling rolls arranged to sandwich a metal plate; and a winding machine for winding up the metal plate rolled by the pair of rolling rolls; and a control device according to claim 1 or 2 configured to control the rolling device.

6. A rolling facility comprising: a rolling device including a pair of rolling rolls arranged to sandwich a metal plate, a winding machine for winding up the metal plate rolled by the pair of rolling rolls, and a cutter arranged between the pair of rolling rolls and the winding machine for cutting the metal plate; and a control device according to claim 4 configured to control the rolling device.

7. A method for operating a rolling mill including a pair of rolls arranged to sandwich a metal sheet, and a winder for winding up the metal sheet rolled by the pair of rolls, comprising: a plate passing step of passing a leading end of the metal sheet between the pair of rolls in a state where the gap between the pair of rolls is larger than the thickness of the metal sheet; and a rolling step of rotating the pair of rolls so that the leading end of the metal sheet reciprocates between the pair of rolls and the winder before the leading end of the metal sheet reaches the winder, in a state where leading end tension applied to the leading end of the metal sheet is zero and the metal sheet has been rolled down by the pair of rolls.

8. A method for operating a rolling mill according to claim 7, further comprising, after the rolling step, a step of cutting the metal plate so as to remove a non-reduced portion of the metal plate that has not been reduced by the pair of rolling rolls.

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