Rolling-device control device, rolling equipment, and method for operating rolling device

Abstract

Provided is a rolling-device control device for controlling a rolling device including a pair of rolling rolls provided so as to sandwich a metal plate, a winding machine for winding the metal plate rolled by the pair of rolling rolls, and a cutting machine provided between the pair of rolling rolls and the winding machine to cut the metal plate, the control device being configured so that: after a distal-end section of the metal plate is made to pass between the pair of rolling rolls in a state in which the gap between the pair of rolling rolls is larger than the plate thickness of the metal plate, the pair of rolling rolls are rotated in a state in which the distal-end section tension applied to the distal-end section of the metal plate is zero and in a state in which the metal plate is pressed by the pair of rolling rolls; and, subsequently, the non-pressed section of the metal plate that is not pressed by the pair of rolling rolls is cut off by the cutting machine.

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, when rolling a metal sheet in a tensionless tip state (tip-free tension rolling) by passing the tip end of the metal sheet between a pair of rolls and then rolling it down with the rolls and rotating the rolls, the non-rolled portion of the metal sheet located on the outlet side of the rolls when the rolls start to rotate is not rolled down by the rolls even after the rolls start to rotate, so the large thickness of the metal sheet before rolling is maintained. Therefore, when the metal sheet is wound on a winding machine, a large difference in thickness occurs between the first winding, which includes the non-rolled portion (tip end) of the metal sheet, and the second winding, which has been rolled without tension at the tip end and has a thinner thickness. This difference in thickness can cause tension fluctuations during rolling of the metal sheet and machine vibrations due to the tension fluctuations, which can result in deterioration of product quality due to tension fluctuations and machine malfunctions due to vibrations.

[0006] In view of the above circumstances, at least one embodiment of the present invention aims to provide a control device for a rolling mill, rolling equipment, and a method for operating a rolling mill that can effectively improve yield while suppressing deterioration in product quality or occurrence of machine failure.

[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, 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, wherein the control device is configured to: pass a leading end of the metal plate between the pair of rolling rolls with a gap between the pair of rolling rolls larger than the thickness of the metal plate; then rotate the pair of rolling rolls in a state where leading end tension applied to the leading end of the metal plate is zero and in a state where the metal plate has been rolled down by the pair of rolling rolls; and then cut off the non-reduced portion of the metal plate that has not been rolled down by the pair of rolling rolls with the cutter.

[0008] Furthermore, at least one embodiment of the rolling equipment of the present invention comprises a rolling device including a pair of rolling rolls arranged to sandwich a metal plate, a winder 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 winder for cutting the metal plate; and the above-mentioned control device configured to control the rolling device.

[0009] Furthermore, at least one embodiment of the present invention provides a method for operating a rolling mill including a pair of rolls arranged to sandwich a metal plate, a winder for winding up the metal plate rolled by the pair of rolls, and a cutter arranged between the pair of rolls and the winder for cutting the metal plate, the method comprising: a plate passing step of passing a leading end of the metal plate between the pair of rolls in a state where the gap between the pair of rolls is larger than the thickness of the metal plate; a rolling step of rotating the pair of rolls in a state where leading end tension applied to the leading end of the metal plate is zero and in a state where the metal plate is rolled down by the pair of rolls; and a cutting step of cutting off, after the rolling step, an unreduced portion of the metal plate that has not been reduced by the pair of rolls with the cutter.

[0010] At least one embodiment of the present invention provides a control device for a rolling mill, rolling equipment, and a method for operating a rolling mill that can effectively improve yield while suppressing deterioration in product quality or occurrence of machine failure.

[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 showing a method of operating a rolling mill according to an embodiment; FIG. 3 is a schematic diagram showing the state of a rolling roll and a metal sheet when rolling is started; FIG. 4 is a schematic diagram showing the state of a rolling roll and a metal sheet when rolling is started; FIG. 5 is a schematic diagram showing the state of a rolling roll and a metal sheet when rolling is started; FIG. 6 is a schematic diagram showing the state of a rolling roll and a metal sheet when rolling is started; FIG. 7 is a schematic diagram showing the state of a rolling roll and a metal sheet when rolling is started; FIG. 8 is a schematic diagram showing the state of a rolling roll and a metal sheet when rolling is started; FIG. 9 is a diagram for explaining a method of operating a rolling mill according to an embodiment; FIG. 10 is a diagram for explaining a method of operating a rolling mill according to an embodiment; FIG. 11 is a diagram for explaining a method of operating a rolling mill according to an embodiment; FIG. 12 is a diagram for explaining a method of operating a rolling mill according to an embodiment; FIG. 13 is a diagram for explaining a method of operating a rolling mill according to an embodiment;

[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 8 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 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.

[0033] 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.

[0034] 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 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.

[0035] In step S8, with the tension applied to the tip portion of the metal sheet S at zero and with the metal sheet S being pressed down by the rolling rolls 16A and 16B, the rolling rolls 16A and 16B may be rotated so that the tip portion Sa of the metal sheet S moves back and forth between the rolling rolls 16A and 16B and the winding machine 14 before the tip portion Sa of the metal sheet S reaches the winding machine 14.

[0036] For example, step S8 may be performed as follows. First, as shown in Fig. 5, while maintaining the inter-roll gap between the rolls 16A and 16B at d1, the rolls 16A and 16B are rotated in the forward direction, and the metal sheet S is rolled while traveling from the rolls 16A and 16B toward the winder 14. As a result, the sheet thickness on the exit side (winder 14 side) of the rolls 16A and 16B becomes H1. Thereafter, before the leading end Sa of the metal sheet S reaches the winder 14, the rotation of the rolls 16A and 16B is stopped, and as shown in Fig. 6, the inter-roll gap between the pair of rolls 16A and 16B is changed to d2, which is smaller than the inter-roll gap d1 in steps S6 to S8. 7, while maintaining the inter-roll gap between the rolls 16A and 16B at d2, the rolls 16A and 16B are rotated in the opposite direction, and the metal sheet S is rolled while proceeding in the direction from the winder 14 toward the rolls 16A and 16B. As a result, the sheet thickness on the exit side (unwinder 4 side) of the rolls 16A and 16B becomes H2, which is smaller than H1.

[0037] In this way, by performing tip tensionless rolling so that the tip portion Sa of the metal sheet S moves back and forth between the rolling rolls 16A, 16B and the winding machine 14 before the tip portion Sa of the metal sheet S reaches the winding machine 14, the metal sheet S can be made significantly thinner by tip tensionless rolling compared to when the metal sheet S is advanced in only one direction before the tip portion Sa of the metal sheet S reaches the winding machine 14.

[0038] In step S8, when tension-free tip rolling is performed so that the tip portion Sa of the metal sheet S moves back and forth between the rolling rolls 16A, 16B and the winder 14 before it reaches the winder 14, the rolling rolls 16A, 16B may first be rotated in the reverse direction to roll the metal sheet S while it advances in the direction from the winder 14 toward the rolling rolls 16A, 16B, and then the gap between the rolls may be made smaller, and the rolling rolls 16A, 16B may be rotated in the forward direction to roll the metal sheet S while it advances in the direction from the rolling rolls 16A, 16B toward the winder 14.

[0039] Furthermore, in step S8, before the leading end portion Sa of the metal sheet S reaches the winder 14, leading end tensionless rolling may be performed by reciprocating the leading end portion Sa of the metal sheet S one or more times (for example, 1.5 reciprocations (one and a half reciprocations)) between the rolling rolls 16A, 16B and the winder 14. In this case, the metal sheet S can be made even thinner by leading end tensionless rolling.

[0040] In step S8, for example, as shown in FIG. 8, tensionless tip rolling may be performed while adjusting the size of the roll gap so as to form a thickness changing portion 52 in which the thickness H1′ of the metal sheet S gradually increases as the distance from the tip St of the metal sheet S increases in the longitudinal direction (traveling direction) of the metal sheet S.

[0041] After the tip end is tension-free rolled in step S8, the non-rolled portion 50 of the metal sheet S is cut off using the cutter 24 (see Figure 1) (step S14) before the tip end Sa is gripped by the winding machine 14 in step S16 described below.

[0042] Thereafter, 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 in a state where the leading end portion is not tensioned. 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 normal rolling (step S18).

[0043] An example of an operating procedure according to the embodiment described above will be described in more detail with reference to Figures 9a to 9e, each of which is a diagram for explaining a method of operating a rolling mill according to one embodiment.

[0044] 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.

[0045] 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 reduced (step S6, FIG. 9b). Then, by rotating the pair of rolling rolls 16A and 16B, the metal sheet S is advanced while performing tip-end tensionless 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 rolling rolls 16A and 16B) becomes a thickness H1 that is thinner than the thickness H0 before rolling (see FIG. 9c). Furthermore, 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 rolling rolls 16A and 16B) remains the thickness H0 before rolling. As described above, in step S8, tip-end tensionless rolling may be performed while reciprocating the tip portion Sa of the metal sheet S until the thickness of the metal sheet S reaches the desired thickness.

[0046] Next, the cutter 24 cuts off the non-reduced portion 50 (the portion having a thickness of H0, including the tip St of the metal sheet S) that has not been reduced in thickness (step S14, FIG. 9c). For example, once the non-reduced portion 50 (the portion including the tip St) of the metal sheet S has passed the cutter 24, the cutter 24 may cut off the non-reduced portion 50 from the metal sheet S. This makes it possible to make the thickness of the tip portion Sa, including the tip St' after cutting of the metal sheet S, equal to the thickness of the portion that has been subjected to tensionless tip rolling (H1 in the drawing) (see FIG. 9d).

[0047] 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. 9d).

[0048] 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. 9e). 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 being applied to the metal sheet S by the winding machine 14, the rolling rolls 16A, 16B are rotated to perform normal rolling (i.e., rolling while applying delivery tension).

[0049] 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. Therefore, if the non-reduction portion 50 is not cut off as in step S14 described above, as shown in Fig. 10, when the metal sheet S is wound by the winding machine 14 after the tension-free rolling at the tip end, a step 54 between the first and second turns of the metal sheet S will be 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.

[0050] In this regard, as in the embodiment described above, by removing the non-reduction portion 50 having a large thickness in step S14 after performing tensionless rolling on the tip of the metal sheet S, the thickness of the tip portion Sa including the tip St' of the metal sheet S after removing the non-reduction portion 50 becomes a thickness after rolling (e.g., H1) that is smaller than the thickness H0 before rolling. Therefore, 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.

[0051] Furthermore, as described above, when the metal sheet S is tension-free rolled at the leading end in step S8 so as to form a thickness varying portion 52 (see FIG. 8) in which the thickness of the metal sheet S gradually increases with increasing distance from the leading end St of the metal sheet S, the step between the first and second turns of the metal sheet on the winding machine can be made smaller, as shown in FIG. 12, for example. This makes it possible to more effectively suppress tension fluctuations caused by the step 54 and the resulting machine vibrations.

[0052] Furthermore, as described above, when the leading end portion Sa of the metal sheet S is rolled without tip tension by reciprocating (i.e., moving in both directions) the leading end portion Sa of the metal sheet S between the pair of rolling rolls 16A, 16B and the winder 14 in step S8, the yield can be improved in the same way as when unidirectional leading end portion Sa of the metal sheet S is rolled multiple times (e.g., for each rolling pass). Furthermore, by rolling the leading end portion Sa of the metal sheet S by reciprocating in a state of no leading end tension, the thickness of the metal sheet S can be significantly reduced before the leading end 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 in which 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, it is possible to effectively improve the yield while suppressing a decrease in production efficiency.

[0053] The contents described in each of the above embodiments can be understood, for example, as follows.

[0054] [1] 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 rolls arranged to sandwich a metal plate, a winder for winding up the metal plate rolled by the pair of rolls, and a cutter arranged between the pair of rolls and the winder for cutting the metal plate, wherein the control device is configured to: pass a leading end of the metal plate between the pair of rolls in a state where the gap between the pair of rolls is larger than the thickness of the metal plate; then rotate the pair of rolls in a state where leading end tension applied to the leading end of the metal plate is zero and the metal plate is rolled down by the pair of rolls; and then cut off the non-reduced portion of the metal plate that has not been rolled down by the pair of rolls with the cutter.

[0055] When rolling (hereinafter also referred to as tip-tensionless rolling) is performed by passing the tip of a metal sheet between a pair of rolls, then reducing it with the rolls and rotating the rolls to perform rolling in a state where the tension at the tip is zero (tip-tensionless state), the non-reduced portion of the metal sheet located on the outlet side of the rolls when the rolls start to rotate is not reduced by the rolls even after the rolls start to rotate, so the thickness before reduction (thicker than the portion to be rolled) is maintained. Therefore, when the metal sheet is wound on a winding machine, there is a large difference in thickness between the first winding, which includes the non-rolled portion of the metal sheet, and the second winding, which has been subjected to tip-tensionless rolling and has a thinner thickness. This difference can cause tension fluctuations during rolling of the metal sheet and machine vibrations due to the tension fluctuations. In this regard, according to the configuration [1] above, after the leading end of the metal sheet is subjected to tensionless rolling, the non-reduction portion with a larger thickness is removed. Therefore, the thickness of the leading end of the metal sheet after the non-reduction portion is removed is smaller than the thickness before rolling. Therefore, the thickness of the first turn of the metal sheet in the winding machine is reduced, and the step between the first and second turns can be reduced. This reduces tension fluctuations caused by the step and the resulting machine vibrations. 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.

[0056] [2] In some embodiments, in the configuration of [1] above, the control device is configured to adjust the size of the gap between the pair of rolling rolls so that when the pair of rolling rolls are rotated with the tip tension at zero and the metal plate being pressed down by the pair of rolling rolls, the thickness of the metal plate gradually increases as the distance from the tip of the metal plate increases in the longitudinal direction of the metal plate.

[0057] According to the configuration [2] above, the metal plate is tension-free rolled at the leading end so that the thickness of the metal plate gradually increases as the distance from the leading end of the metal plate increases, so that the step between the first and second turns of the metal plate on the winding machine can be made smaller, thereby more effectively suppressing tension fluctuations caused by the step and the resulting machine vibrations.

[0058] [3] 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 arranged between the pair of rolling rolls and the winding machine for cutting the metal plate; and the control device according to [1] or [2] above, configured to control the rolling device.

[0059] According to the configuration [3] above, after the leading end of the metal plate is subjected to tensionless rolling, the non-reduction portion with a larger thickness is removed. Therefore, the thickness of the leading end of the metal plate after the non-reduction portion is removed is smaller than the thickness before rolling. Therefore, the thickness of the first turn of the metal plate in the winding machine is reduced, and the step between the first and second turns can be reduced. This reduces tension fluctuations caused by the step and the resulting machine vibrations. 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.

[0060] [4] A method for operating a rolling mill according to at least one embodiment of the present invention is a method for operating a rolling mill including a pair of rolls arranged to sandwich a metal plate, a winder for winding up the metal plate rolled by the pair of rolls, and a cutter arranged between the pair of rolls and the winder for cutting the metal plate, the method comprising: a plate passing step in which a leading end of the metal plate is passed between the pair of rolls in a state in which a gap between the pair of rolls is larger than a thickness of the metal plate; a rolling step in which the pair of rolls is rotated in a state in which leading end tension applied to the leading end of the metal plate is zero and in a state in which the metal plate is rolled down by the pair of rolls; and a cutting step in which, after the rolling step, an unreduced portion of the metal plate that has not been reduced by the pair of rolls is cut off by the cutter.

[0061] According to the method [4] above, after the tip of the metal plate is subjected to tensionless rolling, the non-reduction portion with a larger thickness is removed. Therefore, the thickness of the tip of the metal plate after the non-reduction portion is removed is smaller than the thickness before rolling. Therefore, the thickness of the first turn of the metal plate in the winding machine is reduced, and the step between the first and second turns can be reduced. This reduces tension fluctuations caused by the step and the resulting machine vibrations. 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.

[0062] 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.

[0063] 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.

[0064] 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 52 Sheet thickness change portion 54 Step H0-H1 Sheet thickness S Metal sheet Sa Tip portion St, St' Tip d0-d1 Gap between rolls

Claims

1. A control device for controlling a rolling mill including a pair of rolls arranged to sandwich a metal plate, a winder for winding up the metal plate rolled by the pair of rolls, and a cutter arranged between the pair of rolls and the winder for cutting the metal plate, wherein the control device is configured to: pass a leading end of the metal plate between the pair of rolls with a gap between the pair of rolls larger than the thickness of the metal plate; then rotate the pair of rolls in a state where leading end tension applied to the leading end of the metal plate is zero and the metal plate is rolled down by the pair of rolls; and then cut off the unrolled portion of the metal plate that has not been rolled down by the pair of rolls with the cutter.

2. A control device for a rolling mill according to claim 1, configured to adjust the size of the gap between the pair of rolling rolls so that, when the pair of rolling rolls are rotated with the tip tension at zero and the metal plate being pressed down by the pair of rolling rolls, the thickness of the metal plate gradually increases as the distance from the tip of the metal plate increases in the longitudinal direction of the metal plate.

3. 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 1 or 2 configured to control the rolling device.

4. A method for operating a rolling mill including a pair of rolls arranged to sandwich a metal plate, a winding machine for winding up the metal plate rolled by the pair of rolls, and a cutter arranged between the pair of rolls and the winding machine for cutting the metal plate, the method comprising: a plate passing step of passing a leading end of the metal plate between the pair of rolls in a state where the gap between the pair of rolls is larger than the thickness of the metal plate; a rolling step of rotating the pair of rolls in a state where leading end tension applied to the leading end of the metal plate is zero and in a state where the metal plate is rolled down by the pair of rolls; and a cutting step of cutting off, after the rolling step, an unreduced portion of the metal plate that has not been rolled down by the pair of rolls with the cutter.

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