1. A rolling control device for use in a single-stand rolling mill that includes two vertically-arranged rolling rolls to apply a load to a rolled material, which is sandwiched between the two rolling rolls, and pass the rolled material between the two rolling rolls while rotating the rolling rolls for rolling the rolled material, 5 the rolling control device comprising a soft-reduction thickness change control means that, at a time of the rolled material having an entry-side thickness of a first thickness being rolled with a first load applied thereto so that the rolled material has an exit-side thickness of a second thickness, sequentially executes: 10 first control in which a load applied to the rolled material is reduced from the first load to a second load with which the rolled material has an exit-side thickness of substantially the same thickness as the first thickness; second control in which the rotation of the rolling rolls is suspended in a state that the second load is applied to the rolled material; 15 third control in which the rotation of the rolling rolls is resumed but in the reverse rotational direction in a state that the second load is applied to the rolled material; and fourth control in which a load applied to the rolled material is increased from the second load to a third load with which the rolled material has an exit-20 side thickness of a third thickness that is smaller than the second thickness.

2. The rolling control device according to claim 1, further comprising: a flying-gauge-change control means that, at the time of the rolled material having an entry-side thickness of the first thickness being rolled with the first load 25 applied thereto so that the rolled material has an exit-side thickness of the second thickness, executes: fifth control in which a load applied to the rolled material is changed, in a state that the rolling rolls are being rotated, from the first load to a fourth load with which the rolled material has an exit-side thickness of a fourth 30 thickness that is different from the second thickness.

3. The rolling control device according to claim 2, further comprising: 34 a rolling procedure control means that controls a rolling procedure for producing a finished coil formed of multiple parts sectioned in the longitudinal direction to have different thicknesses from one another after the rolled material is rolled multiple times by the rolling rolls of the single-stand rolling mill, wherein the rolling procedure control means includes: 5 a soft-reduction-rolling control means that, when the rolling direction of the rolled material is changed at positions except for both ends of the rolled material, controls rolling at the time of producing the finished coil, based on a rolling procedure inclusive of changing the rolling direction using the soft-reduction thickness change control means; and 10 a flying-gauge-change-rolling control means that, when a thickness of the rolled material is changed at positions except for both ends of the rolled material, controls rolling at the time of producing the finished coil, based on a rolling procedure inclusive of changing the thickness using the flying-gauge-change control means. 15

4. The rolling control device according to claim 3, wherein the rolling procedure control means further includes: an operating time estimation means that, on the basis of an inputted product specification of the distribution of thicknesses in the longitudical direction of the finished coil, estimates a first operating time for producing the 20 finished coil according to a rolling procedure based on the soft-reduction-rolling control means, and a second operating time for producing the finished coil according to a rolling procedure based on the flying-gauge-change-rolling control means; and a rolling procedure selection means that compares the first operating time 25 with the second operating time, and then selects, as the rolling procedure for producing the finished coil, a rolling procedure based on the soft-reduction-rolling control means if the first operating time is shorter than the second operating time, or a rolling procedure based on the flying-gauge-change-rolling control means if the first operating time is equal to 30 or longer than the second operating time.

5. A rolling control method for use in a rolling control device of a single-stand rolling mill that includes two vertically-arranged rolling rolls to apply a load to a rolled 35 material, which is sandwiched between the two rolling rolls, and pass the rolled material between the two rolling rolls while rotating the rolling rolls for rolling the rolled material, the rolling control method, for sequential execution at a time of the rolled material having an entry-side thickness of a first thickness being rolled with a first load applied 5 thereto so that the rolled material has an exit-side thickness of a second thickness, comprising: reducing, as first control, a load applied to the rolled material from the first load to a second load with which the rolled material has an exit-side thickness of substantially the same thickness as the first thickness; 10 suspending, as second control, the rotation of the rolling rolls in a state that the second load is applied to the rolled material; resuming, as third control, the rotation of the rolling rolls but in the reverse rotational direction in a state that the second load is applied to the rolled material; and 15 increasing, as fourth control, a load applied to the rolled material from the second load to a third load with which the rolled material has an exit-side thickness of a third thickness that is smaller than the second thickness.

6. The rolling control method according to claim 5, further comprising: as fifth control at the time of the rolled material having an entry-side thickness 20 of the first thickness being rolled with the first load applied thereto so that the rolled material has an exit-side thickness of the second thickness, changing a load applied to the rolled material, in a state that the rolling rolls are being rotated, from the first load to a fourth load with which the rolled material has an exit-side thickness of a fourth thickness that is 25 different from the second thickness.

7. A rolling control method using a rolling control device of a single-stand rolling mill that includes two vertically-arranged rolling rolls to apply a load to a rolled material, which is sandwiched between the two rolling rolls, and pass the rolled material between the two rolling rolls while rotating the rolling rolls for rolling the 30 rolled material, wherein the rolling control device includes: a soft-reduction thickness change control means that, at a time of the rolled material having an entry-side thickness of a first thickness being rolled 36 with a first load applied thereto so that the rolled material has an exit-side thickness of a second thickness, sequentially executes: first control in which a load applied to the rolled material is reduced from the first load to a second load with which the rolled material has an exit-side thickness of substantially the same thickness as 5 the first thickness; second control in which the rotation of the rolling rolls is suspended in a state that the second load is applied to the rolled material; third control in which the rotation of the rolling rolls is resumed but in the reverse rotational direction in a state that the second load is 10 applied to the rolled material; and fourth control in which a load applied to the rolled material is increased from the second load to a third load with which the rolled material has an exit-side thickness of a third thickness that is smaller than the second thickness so as to be executed in the order as listed 15 below, at a time of the rolled material having an entry-side thickness of a first thickness being rolled with a first load applied thereto so that the rolled material has an exit-side thickness of a second thickness; and a flying-gauge-change control means that, at the time of the rolled material 20 having an entry-side thickness of the first thickness being rolled with the first load applied thereto so that the rolled material has an exit-side thickness of the second thickness, executes fifth control in which a load applied to the rolled material is changed, in a state that the rolling rolls are being rotated, from the first load to 25 a fourth load with which the rolled material has an exit-side thickness of a fourth thickness that is different from the second thickness, the rolling control method comprising, at a time of controlling a rolling procedure for producing a finished coil formed of multiple parts sectioned in the longitudinal 30 direction to have different thicknesses from one another after the rolled material is rolled multiple times by the rolling rolls of the single-stand rolling mill: 37 controlling rolling at the time of producing the finished coil, when the rolling direction of the rolled material is changed at positions except for both ends of the rolled material, based on a first rolling procedure inclusive of changing the rolling direction using the soft-reduction thickness change control means; and 5 controlling rolling at the time of producing the finished coil, when a thickness of the rolled material is changed at positions except for both ends of the rolled material, based on a second rolling procedure inclusive of changing the thickness using the flying-gauge-change control means.

8. The rolling control method according to claim 7, further comprising: 10 estimating, on the basis of an inputted product specification of the distribution of thicknesses in the longitudical direction of the finished coil, a first operating time for producing the finished coil according to the first rolling procedure, and a second operating time for producing the finished coil according to a rolling procedure based on the second rolling procedure; 15 and comparing the first operating time with the second operating time, and then selecting, as the rolling procedure for producing the finished coil, the first rolling procedure if the first operating time is shorter than the second operating time, or the second rolling procedure if the first operating time 20 is equal to or longer than the second operating time.

9. A non-transitory computer readable medium storing a program causing a computer to execute the rolling control method according to any of claims 5 to 8.

TECHNICAL FIELD
[0001] The present invention relates to a rolling control device, a rolling control 5 method and a program of the same.
BACKGROUND ART
[0002] One form of a rolling mill for rolling a rolled material such as a steel strip is a single-stand rolling mill that includes a set of rolling rolls and tension reels provided on both sides of the rolling rolls. In the single-stand rolling mill, the rolled material is 10 reeled out from an entry-side tension reel installed on the entry side with respect to the rolling direction, is rolled by the rolling rolls so as to have a reduced thickness, and is reeled onto an exit-side tension reel installed on the exit side with respect to the rolling direction. In rolling operation using such a single-stand rolling mill, the rolled material is usually rolled multiple times to have a thickness of the product 15 specification, while changing over the rolling direction in a state that the material is reeled at both ends in the tension reels.
[0003] Even in rolling with a single-stand rolling mill, products having different thicknesses sometimes need to be produced in a single rolled material. In such a case, if the amount of change in thickness is small, a roll gap, a gap between upper 20 and lower rolling rolls (work rolls), may be changed during the rolling to change a thickness of a strip on the exit side. In contrast, if the amount of change in thickness is large, the rolled material is process-wise separated in the longitudinal direction, for example, into a front half having a larger thickness and a rear half having a smaller thickness, so as to have both the front half and the rear half rolled to the larger 25 thickness and then only the rear half rolled to the smaller thickness, to produce products having different thicknesses.
[0004] However, if the above-described method is used especially for a case where the amount of change in thickness is large, only the rear half is further rolled multiple times to have such a need that the rolling is paused at the boundary between the 30 front half and the rear half to change over the rolling direction. As a result, a strip- thickness largely varies at spots where the rolling is paused, to decline a production yield of the rolled material.
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[0005] In order to avoid this declination in a production yield, the roll gap may be changed during the rolling even for the case where the amount of change in thickness is large, to change an exit-side strip-thickness. However, in this case, the number of times of rolling needs to be determined according to the smaller thickness of the product to be finished, to cause a problem that the rolling requires a longer 5 time to decrease operation efficiency.
[0006] Patent Document 1 discloses a method for use in a tandem rolling mill that determines the number of stands required for rolling in accordance with product specifications of a rolled material, and if there is an extra number of stands, releases a rolling mill stand so as not to be used at a time of a welding point passing through, 10 while if there is insufficient number of stands, puts a rolling mill stand into operation so as to be used at a time of a welding point passing through, to obtain the required product thickness, thereby effectively using multiple rolling mill stands.
PRIOR ART DOCUMENT
Patent Document 15
[0007] Patent Document 1: Japanese Patent No. 5422032
SUMMARY OF THE INVENTION
Problems to be solved
[0008] Changing the number of passes (the number of times of the rolling mill rolling the rolled material) in a single stand rolling mill is equivalent to changing the 20 number of rolling mill stands in a tandem rolling mill. In this sense, it is perceived that the technique disclosed in Patent Document 1 may be used even in a single stand rolling mill to change the number of passes according to the thickness of the finished product produced from a rolled material.
[0009] However, in a single stand rolling mill, if the number of passes is increased, 25 the rolling direction needs to be changed many times. In order to change the rolling direction, the rolling mill needs to be suspended and this requires a technique different from the technique disclosed in Patent Document 1 of switching between use and disuse of the rolling mill without suspending the rolling mill. That is, such a technique is required, practically without decreasing production quality of the product, 30 that determines timings of changing over the rolling direction having the highest operation efficiency, based on the required number of rolling passes according to the product specification such as a thickness, to achieve rolling operation taking the shortest time.
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[0010] In view of the above problems of the prior art, the present invention intends to provide a rolling control device, a rolling control method and a program of the same that are capable of shortening an operating time of rolling in a single stand rolling mill without decreasing the production quality of the product.
Solution to Problems 5
[0011] In order to achieve the objective of the present invention, a rolling control device according to the present invention is designed for use in a single stand rolling mill that includes two vertically-arranged rolling rolls to apply a load to a rolled material which is sandwiched between the two rolling rolls, and pass the material between the two rolling rolls while rotating the rolling rolls for rolling the material. The 10 rolling control device includes a soft-reduction thickness change control means that executes in the order as listed below, at a time of the material having an entry-side thickness of a first thickness being rolled with a first load applied thereto so that the material has an exit-side thickness of a second thickness: first control in which a load applied to the material is reduced from the first load to a second load with which the 15 material has an exit-side thickness of substantially the same thickness as the first thickness; second control in which the rotation of the rolling rolls is suspended in a state that the second load is applied to the material; third control in which the rotation of the rolling rolls is resumed but in the reverse rotational direction in a state that the second load is applied to the material; and fourth control in which a load applied to 20 the material is increased from the second load to a third load with which the material has an exit-side thickness of a third thickness that is smaller than the second thickness.
Advantageous Effects of the Invention
[0012] The present invention provides a rolling control device, a rolling control 25 method and a program of the same that are capable of shortening the operating time of rolling without reducing the production yield of a product in rolling with a single stand rolling mill.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a diagram showing an example of the overall configuration of a 30 single stand rolling mill and a rolling control device according to an embodiment of the present invention;
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FIG. 2 is a diagram showing an example of rolling a rolled material by rolling rolls, and parameters related to rolling control;
FIG. 3 is a diagram showing an example configuration of functional blocks in a left strip-thickness controller in the rolling control device;
FIG. 4 is a diagram showing an example configuration of functional blocks in a right 5 strip-thickness controller in the rolling control device;
FIG. 5 is a diagram showing an example rolling schedule for rolling the rolled material by a single stand rolling mill;
FIG. 6A is a diagram showing product specification <1> of a finished coil obtained by rolling as an example; FIG. 6B is a diagram showing product specification <2> as 10 another example;
FIG. 7 is a diagram showing a first half of an example of a conventional generic rolling procedure for producing a finished coil;
FIG. 8 is a diagram showing a second half of the example of a conventional generic rolling procedure for producing the finished coil; 15
FIG. 9 is a diagram showing an example rolling procedure based on a flying gauge change method, for producing a finished coil,;
FIG. 10 collectively shows examples of calculation formulas for corrected exit-side strip-thicknesses of, and corrected rolling loads for, respective product parts in each pass used in the flying gauge change method; 20
FIG. 11 is a chart illustating in detail the flying gauge change method;
FIG. 12 is a diagram showing a first half of an example rolling procedure based on a soft-reduction method, for producing a finished coil;
FIG. 13 is a diagram showing a second half of the example rolling procedure based on the soft-reduction method, for producing the finished coil; 25
FIG. 14 is a chart illustrating in detail the soft reduction method;
FIG. 15 is a diagram showing key points of the differences in the rolling procedure among rolling methods of producing the finished coil having the product specification <1> shown in FIG. 6;
FIG. 16 is a diagram showing key points of the differences in the rolling procedure 30 among rolling methods of producing the finished coil having the product specification <2> shown in FIG. 6;
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FIG. 17 is a diagram showing an example configuration of a rolling procedure controller included in the rolling control device according to the present embodiment;
FIG. 18 is a diagram showing an example format of a finished coil pattern DB (database);
FIG. 19 is a chart showing an example of a basic form of a rolling speed pattern on 5 the condition that the maximum rolling speed Vo is given;
FIG. 20 is a diagram showing an example of a rolling speed pattern in each pass in a rolling procedure based on the flying gauge change method;
FIG. 21 is a diagram showing an example of a rolling speed pattern in each pass in a rolling procedure based on the soft-reduction method; 10
FIG. 22 is a diagram showing an example of calculation formulas for calculating the rolled lengths of respective leader parts and product parts in each pass in the rolling procedure based on the flying gauge change method;
FIG. 23 is a diagram showing an example of calculation formulas for calculating the rolled lengths of respective leader parts and product parts in each pass in the rolling 15 procedure based on the soft reduction method; and
FIG. 24 shows an example flowchart of an operating-time estimation process.
DETAILED DESCRIPTION
[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in each drawing, common components are 20 denoted by the same reference numerals and duplicate descriptions thereof are omitted.
<1. Structure of Rolling Mill and Rolling Control Device>
[0015] FIG. 1 is a diagram showing an example of the overall configuration of a single-stand rolling mill 100 and a rolling control device 200 according to an 25 embodiment of the present invention. As shown in FIG. 1, the single-stand rolling mill 100 according to the present embodiment mainly includes: a rolling roll 1 that constitutes a rolling stand; a left tension reel (TR) 3L that is arranged on the left side of the rolling roll 1; and a right tension reel (TR) 3R that is arranged on the right side of the rolling roll 1. Here, the rolling roll 1 includes: an upper work roll 1au, an upper 30 intermediate roll 1bu, and an upper backup roll 1cu that are arranged on an upper side of a rolled material 2; and a lower work roll 1ad, a lower intermediate roll 1bd, and a lower backup roll 1cd that are arranged on a lower side of the rolled material 2.
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[0016] In such a single-stand rolling mill 100, rightward rolling is executed so that the rolled material 2 is reeled out from the left TR 3L, rolled by the rolling roll 1, and then reeled onto the right TR 3R. In contrast, leftward rolling is executed so that the rolled material 2 is reeled out from the right TR 3R, rolled by the rolling roll 1, and then reeled onto the left TR 3L. 5
[0017] In addition, as shown in FIG. 1, the single-stand rolling mill 100 includes various measuring instruments and control devices that are required for rolling control. The measuring instruments include a left tensiometer 4L, a right tensiometer 4R, a left thickness gauge 5L, a right thickness gauge 5R, a left TR tachometer 7L, a right TR tachometer 7R, and a rolling load meter 8. 10
[0018] Here, the left tensiometer 4L and the right tensiometer 4R are arranged so as to be attached to a left deflection roll 6L and a right deflection roll 6R, respectively, to measure the tension on the left side and the right side of the rolled material 2 during rolling. In addition, the left thickness gauge 5L and the right thickness gauge 5R measure a thickness of the rolled material 2 on the entry side and the exit side 15 during rolling, respectively. At this time, which one is on the entry side or which one is on the exit side depends on the rolling direction. Further, the left TR tachometer 7L and the right TR tachometer 7R measure the amount of rotation (the number of rotations and a rotation angle) of the left TR 3L and the right TR 3R, respectively. Furthermore, the rolling load meter 8 is arranged so as to be attached to the rolling 20 roll 1 to measure a load applied to the rolled material 2 by the rolling roll 1.
[0019] Moreover, control devices such as a left TR control device 9L, a right TR control device 9R, a roll gap control device 10, and a mill speed control device 11 are included. Here, the left TR control device 9L and the right TR control device 9R control electric motors driving the left TR 3L and the right TR 3R, respectively. In 25 addition, the mill speed control device 11 controls electric motors that drive the upper work roll 1au and the lower work roll 1ad. Further, the roll gap control device 10 controls the size of a roll gap between the upper work roll 1au and the lower work roll 1ad. Note that these control devices are suitably controlled by the rolling control device 200 while the rolled material 2 is rolled. 30
[0020] Next, prior to describing the configuration of the rolling control device 200, a description will be given of rolling the rolled material 2 by the rolling roll 1.
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FIG. 2 is a diagram showing an example of rolling the rolled material 2 by the rolling roll 1 and parameters related to rolling control. As shown in FIG. 2, the rolling is executed in a manner such that the rolled material 2 is sandwiched between the upper work roll 1au and the lower work roll 1ad of the rolling roll 1 and then pressed flat to reduce the thickness of the rolled material 2. 5
[0021] At this time, the rolled material 2 is pulled with an entry-side tension Tb and an exit-side tension Tf, and is pressed flat with a rolling load P received from the upper work roll 1au and the lower work roll 1ad for rolling so as to cause an entry-side thickness “H” to be reduced to an exit-side thickness “h.” Note that the rolling load “P” depends on a roll gap “S.” 10
[0022] In such rolling operation, an entry-side speed Ve of the rolled material 2 is slower than a work roll speed VR, while an exit-side speed Vo is faster than the work roll speed VR. Here, as shown in FIG. 2, the relationship between the work roll speed VR, the entry-side speed Ve, and the exit-side speed Vo can be expressed by using a forward ratio “f” and a backward ratio “b.” At this time, the important thing is toward 15 which side the rolled material 2 is proceeding, and the direction in which the rolled material 2 is proceeding is referred to as a rolling direction. In addition, the forward side of the rolling direction with reference to the rolling roll 1 is referred to as an exit side, while the opposite side is referred to as an entry side. For the rolling operation, the important thing is on which of the entry-side or exit-side in the rolling direction the 20 subject matter resides.
[0023] Now, returning to the description of FIG. 1, the configuration of the rolling control device 200 will be described. As shown in FIG. 1, the rolling control device 200 includes a rolling speed setter 18. The rolling speed setter 18 calculates a rolling speed at the current position (immediately below the rolling roll 1) of the rolled 25 material 2 being rolled, based on the rolling procedure set by a rolling procedure controller 20 according to the finished coil specification, to output the calculated rolling speed to the mill speed control device 11. According to the received rolling speed, the mill speed control device 11 controls electric motors that drive the upper work roll 1au and the lower work roll 1ad, so as to keep the work roll speed VR 30 constant and so on. Note that in the present specification, the mill speed in the rightward rolling direction is set to be in a positive direction to have a positive value,
9
while the mill speed in the leftward rolling direction is set to be in a negative direction to have a negative value.
[0024] In addition, the rolling control device 200 includes a left tension setter 13L, a right tension setter 13R, a left tension controller 14L, a right tension controller 14R, a left tension-to-current converter 15L and a right tension-to-current converter 15R. 5 Here, the left tension setter 13L and the right tension setter 13R calculate tension required for stably and efficiently rolling the rolled material 2, according to the rolling procedure set by the rolling procedure controller 20. Further, the left tension controller 14L and the right tension controller 14R use differences between values actually measured by the left tension meter 4L and the right tension meter 4R, and 10 values calculated by the left tension setter 13L and the right tension setter 13R, to correct the tension calculated by the left tension setter 13L and the right tension setter 13R.
[0025] This corrected tension is the tension to be applied to the rolled material 2, and the tension is materialized by the rotational torque of the left TR 3L and the right 15 TR 3R. Therefore, the left tension-to-current converter 15L and the right tension-to-current converter 15R convert the corrected tension to current values for obtaining the motor torque corresponding to the tension. Then, the converted current values are outputted to the left TR control device 9L and the right TR control device 9R.
[0026] The left TR control device 9L and the right TR control device 9R drive the 20 electric motors of the left TR 3L and the right TR 3R, respectively, based on the received current values, to apply tension set by the left tension setter 13L and the right tension setter 13R to the rolled material 2.
[0027] Note that the left tension-to-current converter 15L and the right tension-to-current converter 15R convert tension values to current values (electric motor torque 25 values), based on the mechanical system of the tension reel and its control model, but the control model contains an error. Therefore, in the present embodiment, the left tension controller 14L and the right tension controller 14R are used to obtain differences between the tension values actually measured by the left tensiometer 4L and the right tensiometer 4R, and the values calculated by the left tension setter 13L 30 and the right tension setter 13R, or the like. Then, based on the differences or the like, the tension calculated by the left tension setter 13L and the right tension setter 13R is corrected. Therefore, in the present embodiment, the error is minimized.
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[0028] Further, the rolling control device 200 includes a rolling load setter 19, a load controller 17, a left strip-thickness controller 16L, and a right strip-thickness controller 16R. The rolling load setter 19 calculates the rolling load for materializing the specified thickness, according to the rolling procedure designated by the rolling procedure controller 20. The load controller 17 corrects the rolling load calculated by 5 the rolling load setter 19 with the rolling load actually measured by the rolling load meter 8, to output the corrected rolling load to the roll gap control device 10. However, as the thickness of the rolled material 2 is important for product quality, the left strip-thickness controller 16L and the right strip-thickness controller 16R execute control to be described later, to reflect the result on the rolling load outputted to the gap control 10 device 10. That is, the rolling load outputted from the load controller 17 is corrected based on the control results of the left strip-thickness controller 16L and the right strip-thickness controller 16R, and then inputted to the roll gap control device 10.
[0029] The rolling procedure controller 20 determines a detailed rolling procedure based on the specification of the finished coil obtained as a result of rolling the rolled 15 material 2, and also calculates the current position in the longitudinal direction of the rolled material 2 being rolled, based on the information obtained from the left TR tachometer 7L and the right TR tachometer 7R. Then, the rolling procedure controller 20 outputs the determined rolling procedure and the current position in the longitudinal direction to the left tension setter 13L, the right tension setter 13R, the 20 rolling speed setter 18, and the rolling load setter 19. Note that the configuration and function of the rolling procedure controller 20 characterize the present embodiment, and therefore these will be described in detail later with reference to drawings.
[0030] The rolling control device 200 having the above-described configuration is implemented by a computer including an arithmetic processing unit (CPU: Central 25 Processing Unit) and a storage device (ROM (Read Only Memory), RAM (Random Access Memory), hard disk device, or the like). The functions of the respective parts including the load controller 17, which constitute the rolling control device 200, are implemented by the arithmetic processing unit executing a predetermined program stored in the storage device. 30
[0031] Moreover, the computer for implementing the rolling control device 200 is not limited to one computer. The rolling control device 200 may be implemented by
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multiple computers connected to one another via a network or communication lines so as to communicate with one another.
[0032] FIG. 3 is a diagram showing an example configuration of functional blocks in the left strip-thickness controller 16L in the rolling control device 200, while FIG. 4 shows an example configuration of functional blocks of the right strip-thickness 5 controller 16R in the rolling control device 200. As shown in FIG. 3, the left strip-thickness controller 16L includes a feedforward strip-thickness controller 30 and a feedback strip-thickness controller 40, and, as shown in FIG. 4, the right strip-thickness controller 16R has the like configuration. Note that in FIGS. 3 and 4, it is assumed that the rolling direction of the rolled material 2 is rightward. 10
[0033] As shown in FIG. 3, the feedforward strip-thickness controller 30 executes transfer processing on an entry-side strip-thickness deviation ΔH, which has been measured by a strip-thickness meter (the left strip-thickness meter 5L in the example in FIG. 3) on an entry side with respect to the rolling roll 1, to the position just under the rolling roll 1 by a transfer-time compensating unit 31. Then, the result is multiplied 15 by a conversion gain 32, for converting the entry-side strip-thickness deviation ΔH into the roll gap S, and a control gain 33 (GFF) to execute feedforward control, and then the controlled result is outputted to the roll gap control device 10 of the rolling roll 1.
[0034] Note that the transfer processing is processing to compensate time to be 20 determined in accordance with a time difference TFF between a timeTEX-MIL, during which a spot of the rolled material 2 where the entry-side strip-thickness deviation ΔH has been measured is transported to a position just below the rolling roll 1, and a control output timing shift amount ΔTFF for controlling an entry-side strip-thickness. Additionally, the conversion gain 32 is given by the ratio of a plasticity constant Q and 25 a mill constant M.
[0035] As shown in FIG. 4, the feedback strip-thickness controller 40 multiplies an exit-side strip-thickness deviation Δh, which has been measured by a strip-thickness meter (the right strip-thickness meter 5R in the example in FIG. 4) on the exit side from the rolling roll 1, by a conversion gain 41 and a control gain 42 (GFB). Then, 30 integration processing 43 is executed on the result to complete feedback control, and the controlled result is outputted to the roll gap control device 10 of the rolling roll 1. Note that the conversion gain 41 is a gain for converting the exit-side strip-thickness
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deviation Δh into the roll gap S, and is a value determined by the plasticity constant Q and the mill constant M.
[0036] According to FIGS. 3 and 4, in a case of the rightward rolling direction, the feedforward strip-thickness controller 30 of the left strip-thickness controller 16L has a signal inputted from the left strip-thickness meter 5L, but the feedback strip-5 thickness controller 40 has no signal inputted. In addition, in a case of the rightward rolling direction, the feedback strip-thickness controller 40 of the right strip-thickness controller 16R has a signal inputted from the right strip-thickness meter 5R, but the feedforward strip-thickness controller 30 has no signal inputted. This means that in a case of the rightward rolling direction, the left strip-thickness controller 16L is 10 responsible for the feedforward strip-thickness control while the right strip-thickness controller 16R is responsible for the feedback strip-thickness control.
[0037] In contrast, in a case of the leftward rolling direction, the signals inputted to the feedforward strip-thickness controller 30 and the feedback strip-thickness controller 40 are switched. That is, the feedforward strip-thickness controller 30 of the 15 right strip-thickness controller 16R has a signal inputted from the right strip-thickness meter 5R, and the feedback strip-thickness controller 40 of the left strip-thickness controller 16L has a signal inputted from the left strip-thickness meter 5L. That is, in a case of the leftward rolling direction, the left strip-hickness controller 16L is responsible for the feedback strip-thickness control while the right strip-thickness 20 controller 16R is responsible for the feedforward strip-thickness control.
[0038] Therefore, in a case of the rightward rolling direction, the roll gap control device 10 has a signal applied as a control command value, where the signal is determined by the feedforward control output from the left strip-thickness controller 16L and the feedback control output from the right strip-thickness controller 16R. 25 Also, in a case of the leftward rolling direction, the roll gap control device 10 has a signal applied as the control command value, where the signal is determined by the feedback control output from the left strip-thickness controller 16L and the feedforward control output from the right strip-thickness controller 16R.
[0039] Note that in FIG. 1, for example, strip-thickness meters and tension reels 30 arranged on the left side and the right side of the rolling role 1 are referred to as tthe left strip-thickness meter 5L, the right strip-thickness meter 5R, the left TR 3L, the right TR 3R, and the like. In the present embodiment, the roles of these components
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change depending on the rolling direction, and therefore, hereinafter, these will be referred to as an entry-side strip-thickness meter, an exit-side strip-thickness meter, an entry-side TR, an exit-side TR and the like as appropriate, according to the rolling direction.
<2. Rolling Schedule> 5
[0040] FIG. 5 is a diagram showing an example rolling schedule for rolling the rolled material 2 by the single stand rolling mill 100. In FIG. 5, a base material thickness H1 is the thickness just before starting rolling operation by the rolling roll 1 of the rolled material 2, and a first pass shows a first rolling. In the first rolling (first pass), the base material thickness H1 is reduced to an exit-side strip-thickness h1, 10 and in a second rolling (second pass), the entry-side strip thickness h1 is reduced to an exit-side strip-thickness h2. Likewise, a third rolling (third pass) and a fourth rolling (fourth pass) are executed, and in a fifth rolling (fifth pass), an entry-side strip-thickness h4 is reduced to an exit-side strip-thickness h5. In addition, tension to the rolled material 2 on the entry side and exit side of the rolling roll 1 in respective rolling 15 passes is referred to as entry-side tension and exit-side tension, and expressed as Tb1 to Tb5 and Tf1 to Tf5, respectively.
[0041] Note that the strip-thickness and tension as described above vary by quality of the rolled material 2, power of the rolling roll 1 (the maximum load, ampacity of the motors for driving the rolling roll 1 and the tension reels, etc.), rolling oil (oil used for 20 lubrication between the upper and lower work rolls 1au, 1ad and the rolled material 2), and the like. Therefore, in general, these values are empirically set by a rolling operator. In this case, a rolling model can be used, for example, to calculate by computer strip-thicknesses which allow the rolling load to be constant in each pass. The tension can also be calculated according to a certain rule from measurements, 25 such as stresses, of the rolled material 2. Here, it is assumed that the strip-thickness and tension to be set in the rolling schedule are calculated in advance by some means.
[0042] In addition, deformation resistance depends on the rolled material and represents the hardness of the rolled material 2. Its value can be obtained empirically 30 for each material by mechanical means such as a tensile test. Further, the coefficient of friction between the upper and lower work rolls 1au, 1ad and the rolled material 2 is represented by “μ.” The friction coefficient “μ” depends on the speed and the
14
surface roughness of the upper and lower work rolls 1au, 1ad, but here, for the purpose of simplicity, is assumed to be a fixed value.
[0043] Once the entry-side strip-thickness H, the exit-side strip-thickness h, the entry-side tension Tb, the exit-ide tension Tf, deformation resistance km, and the friction coefficient μ are determined in the single-stand rolling mill 100, a known 5 rolling load formula can be used to obtain a required rolling load P. As a known rolling load formula, a formula by BLAND & FORD is available, for example. Here, although a description thereof is omitted, the rolling load P is expressed as a function of the entry-side strip-thickness H, the exit-side strip-thickness h, the entry-side tension Tb, the exit-side tension Tf, the deformation resistance km, and the friction 10 coefficient μ. That is, the rolling load P is expressed as P = P(H, h, Tb, Tf, km, μ). Therefore, the rolling loads P1 to P5 in the first to fifth passes of the rolling schedule in FIG. 5 are calculated by the rolling load formula shown in the lower part of FIG. 5.
[0044] FIG. 6A is a diagram showing product specification <1> of a finished coil obtained by rolling as an example, and FIG. 6B is that showing product specification 15 <2> as another example. These finished coils are assumed to be produced according to the rolling schedule shown in FIG. 5.
[0045] As shown in FIG. 6A, the finished coil having the product specification <1> includes a product part A having a thickness h3, a product part B having a thickness h4, and leader parts A, B, C having a thickness h5. The leader parts A, B, C are parts 20 used as welded parts or used such as for reeling onto a tension reel, for example, and are cut off for scrapping at the time of delivering the product to a customer. In addition, in FIG. 6A, LA and LB respectively represent the lengths of the product part A and the product part B, and LDA, LDB, LDC respectively represent the lengths of the leader parts A, B, C. Note that as a matter of fact, the lengths LA, LB of the product 25 parts A, B are much larger than the lengths LDA, LDB, LDC of the leader parts A, B, C.
[0046] Likewise, the finished coil having the product specification <2> shown in FIG. 6B includes a product part C having a thickness h3, and leader parts D, E having a thickness h5. LC represents the length of the product part C, and LDD, LDE respectively represent the lengths of the leader parts D, E. 30
<3. Rolling Procedure for Producing Finished Coil>
[3.1 Conventional Generic Rolling Procedure]
15
[0047] FIG. 7 is a diagram showing a first half of an example of a conventional generic rolling procedure for producing a finished coil. Additionally, FIG. 8 is a diagram showing a second half of the same example. Note that in the examples of FIGS. 7 and 8, the finished coil having the product specification <1> shown in FIG. 6 is to be produced. 5
In addition, sub-procedures in FIGS. 7 and 8 mean lower level procedures included in the rolling procedure for producing the finished coil. Note that sub-procedures in FIGS. 9, 12, and 13 also mean lower level procedures.
[0048] First, as shown under sub-procedure 1 in FIG. 7, the coil (rolled material 2) is rolled over the entire length thereof from the base material thickness H1 (thickness 10 level indicated by a thin broken line) to the exit-side strip-thickness h1 in the first pass (thickness level indicated by a bold dot-and-dash line). Next, under sub-procedure 2, the rolling direction is reversed to roll the coil over the entire coil length thereof to the exit-side strip thickness h2 in the second pass. In the first and second passes of the rolling, rolling loads P1 and P2 are respectively applied to the coil under the rolling. 15 Note that values such as entry-side strip-thickness, exit-side strip-thickness, and rolling loads in each pass, such as the first pass and second pass, are based on the rolling schedule indicated in FIG. 5.
[0049] Next, under sub-procedures 3 to 5, the leader part A is formed at a leading end of the coil. First, under sub-procedure 3, the coil is rolled from the leading end 20 thereof to a coil position CP1-1 so as to reduce the exit-side strip-thickness to the exit-side strip-thickness h3 in the third pass. Next, under sub-procedure 4, the rolling direction is reversed to roll the coil back to the leading end thereof so as to reduce the exit-side strip-thickness to the exit-side strip-thickness h4 in the fourth pass. Further, under sub-procedure 5, the rolling direction is reversed to roll the coil from 25 the leading end thereof to the coil position CP1-1 so as to reduce the exit-side strip-thickness to the exit-side strip-thickness h5 in the fifth pass.
[0050] The leader part A has been formed in the first half of the rolling procedure shown in FIG. 7, and then under sub- procedure 6 in FIG. 8, the coil is rolled from the coil position CP1-1 to a trailing end of the coil so as to reduce the exit-side strip-30 thickness to the exit-side strip-thickness h3 in the third pass. Note that under sub-procedure 6 and beyond in FIG. 8, the rolled coil portion is indicated by a thick solid line.
16
[0051] Subsequently, under sub-procedure 7, the rolling direction is reversed to roll the coil from the trailing end thereof to a coil position CP1-2 so as to reduce the exit-side strip-thickness to the exit-side strip-thickness h4 in the fourth pass. Next, in order to form the leader part B, the coil is rolled from the coil position CP1-2 to a coil position CP1-3 so as to reduce the exit-side strip-thickness to the exit-side strip-5 thickness h5 in the fifth pass. Lastly, in order to form the leader part C, the coil is rolled from a coil position CP1-4 to the trailing end thereof so as to reduce the exit-side strip-thickness to the exit-side strip-thickness h5 in the fifth pass.
[0052] According to the above-described rolling procedure in FIGS. 7 and 8, the finished coil having the product specification <1> shown in FIG. 6 is produced. Here, 10 the reason of rolling the leading end of the coil three times in the third pass so as to reduce the strip thickness at the leading end of the coil to h5, as under sub-procedures 3 to 5 in FIG. 7, is because the lengths of the product parts A, B are overwhelmingly longer than those of the leader parts A, B, C. That is, there is no need under sub-procedure 5 and beyond to return the coil to the leading end, thereby 15 shortening the rolling time.
[0053] FIG. 15 is a diagram showing key points of the differences in the rolling procedure among rolling methods of producing the finished coil having the product specification <1> shown in FIG. 6. Note that a description will be given in detail later of the flying gauge change method and the soft-reduction method in FIG. 15. 20
[0054] In FIG. 15, each of the bold solid arrowed lines indicates a rolling range and a rolling direction of the rolled coil. In addition, each of inverted triangles (∇) in the drawing represents a point where the rolling roll 1 needs to be suspended to change a reduction level, that is, the rolling load. Normally, when the rolling roll 1 is suspended in a reducing state, the strip-thickness at a point where the rolling roll 1 25 has been suspended is reduced to form a portion out of the product tolerance (hereinafter referred to as a “stop mark”).
[0055] In the conventional generic rolling procedure, when a strip- thickness is to be changed, the rolling roll 1 is suspended in a reducing state to change the reduction level, that is, the rolling load. Therefore, in a case where the conventional 30 generic rolling procedure is used to produce a finished coil having the product specification <1>, the finished coil comes with a defect in thickness due to the stop
17
marks at four portions (excluding both ends). A stop mark generated in the finished coil is a major cause of deteriorating quality of the finished coil.
[0056] Therefore, in order to improve the quality of the finished coil, it is important to avoid forming a stop mark in the finished coil. In viewing this, as a method of changing a strip thickness without forming any stop mark, a description will be given 5 below of a flying gause change method and a soft reduction method.
[3.2 Rolling Procedure based on Flying Gauge Change Method]
[0057] FIG. 9 is a diagram showing an example rolling procedure based on the flying gauge change method, for producing a finished coil. In the flying gauge change method, when a strip-thickness is changed, the reduction level, that is, the rolling 10 load is changed without suspending the rolling roll 1 except when the rolling direction is reversed at either end of the coil. Therefore, there is no defect in thickness due to a stop mark formed in the finished coil.
[0058] Note that the rolling procedure in FIG. 9 is for producing a finished coil having the product specification <1> shown in FIG. 6, and the rolling schedule 15 thereof is in accordance with the rolling schedule shown in FIG. 5. In this case, due to the rolling capability of the rolling roll 1, it is assumed that the exit-side strip-thickness in each pass shown in FIG. 5 cannot be reduced any more. Then, a finished coil having the product specification <1> fails to be produced by rolling the coil four times in accordance with the exit-side strip-thickness h4 of the product part B, 20 and rolling the coil five times is inevitable by all means.
[0059] In the first pass rolling under sub-procedure 1, the base material of rolled coil is rolled over the entire length thereof from the leading end to the trailing end, while the rolling load is changed at each product part and each leader part. At this time, the exit-side strip-thicknesses of, and the rolling loads for, the product parts A, 25 B are corrected to values smaller than the exit-side strip-thicknesses and rolling loads shown in the rolling schedule in FIG. 5. In FIG. 9, corrected exit-side strip-thicknesses of the product parts A, B are described as h1T1, h1T2, and corrected rolling loads are described as P1T1, P1T2.
[0060] In the second to fifth passes under sub-procedure 2 to 5, the rolled coil is 30 rolled after the rolling direction is reversing, while the rolling load is changed over the entire length of the coil as under sub-procedure 1. Also in this case, the exit-side strip-thicknesses of, and the rolling loads for, the product parts A, B are corrected to
18
values smaller than the exit-side strip-thicknesses and the rolling loads shown in the rolling schedule in FIG. 5. Note that in FIG. 9, the corrected values are described as h2T1, h2T2, P2T1, P2T2 under sub-procedure 2, --- (snip) ---, and h5T1, h5T2, P5T1, P5T2 under sub-procedure 5.
[0061] As described above, in the coil rolling procedure using the flying gauge 5 change method, the rolled coil is rolled over the entire length thereof without the rolling roll 1 being suspended, while the exit-side strip-thickness and the rolling load are changed as appropriate. Therefore, there is no defect in thickness due to a stop mark caused in a finished coil, thereby improving quality of the finished coil.
[0062] From another point of view, in the coil rolling procedure using the flying 10 gauge change method, the rolled coil is rolled over the entire length thereof in each pass and the product part is also rolled as often as the number of times of rolling required for forming the leader part. Therefore, in producing the finished coil having the product specification <1> shown in FIG. 6, for example, the overall rolling time may be longer than that required for the conventional generic rolling procedure. 15 Longer rolling time means that operation efficiency in rolling decreases. Additionally, in the finished coil having the product specification <2> shown in FIG. 6, the length of the product part C is overwhelmingly longer than the lengths of the leader parts D and E, to further decrease the operation efficiency.
[0063] FIG. 10 collectively shows examples of calculation formulas for corrected 20 exit-side strip-thicknesses of, and corrected rolling loads for, respective product parts in each pass used in the flying gauge change method. In FIG. 10, hiT1 and hiT2 (where i = 1,..., 5) represent corrected exit-side thicknesses of the product parts A and B in the i-th pass, and PiT1 and PiT2 represent corrected rolling loads for the product parts A and B in the i-th pass. Additionally, a formula by BLAND & FORD or the like can be 25 used as a function for calculating the rolling load, as previously described.
[0064] FIG. 11 is a chart illustrating in detail the flying gauge change method, and will be described here in detail using operation for a part within an area A under sub-procedure 3 in FIG. 9 as an example. In the flying gauge change method, the rolling load is changed from P3 to P3T1, for example, while the rolling roll 1 is kept in 30 operation (that is, in a state where the rolling speed is constant), to change the exit-side strip-thickness from h3 to h3T1. During this time, the entry-side tension and the exit-side tension are kept constant.
19
[0065] The distance from the leading or trailing end of the coil to any point of the finished coil having the product specification <1> shown in FIG. 6 can be obtained based on the cumulative number of rotations of the tension reels (left TR 3L, right TR 3R). For example, assuming that the length of the product part A in the finished coil is LA, the length in the third pass on the entry side is (h5/h2)*LA according to the mass 5 flow constant rule. Therefore, one can obtain, for each pass, a distance from the leading or trailing end of the coil to one of the coil positions CP1-1 to CP1-4 or a length LT of the tapered part of the leader part A, B, or C in FIG. 6A.
[0066] Further, timing points for starting operation such as changing a rolling load may be generated from these pieces of information to change the rolling load based 10 on the change of the entry-side strip-thickness so that the exit-side strip-thickness is accordingly changed. Here, the length of the tapered part and the actual value of the entry-side speed in each pass may be used to obtain an elapsing time of changing the rolling load.
[0067] The flying gauge change as described above is always executed under the 15 condition of [the exit-side strip-thickness < the entry-side strip-thickness], and rolling the rolled material 2 (rolled coil) at this time is executed within a range of plastically deformed state.
[3.3 Rolling Procedure based on Soft Reduction Method]
[0068] FIG. 12 is a diagram showing a first half of an example rolling procedure 20 based on a soft-reduction method, for producing a finished coil. Also, FIG. 13 is a diagram showing a second half of the example rolling procedure based on the soft-reduction method, for producing the finished coil. Note that in the example shown in FIGS. 12 and 13, the finished coil having the product specification <1> shown in FIG. 6 is to be produced. 25
[0069] The soft reduction method is characterized in that the rolling direction is changed with the rolled material 2 (rolled coil) being in an elastically deformed state. In general, the rolled material 2 is in a plastically deformed state at the time of rolling so as to have the exit-side strip-thickness “h” thinner than the entry-side strip-thickness “H.” As the rolling load, the entry-side tension, and the exit-side tension are 30 reduced in this state, the state transitions to an elastically deformed state in which the entry-side thickness and exit-side thickness of the rolled material 2 are substantially equal to each other. In the elastically deformed state, the rolled material
20
2 is pressed flat by the rolling roll 1 to have its thickness temporarily reduced, but restores its thickness after being moved away from just under the rolling roll 1 to have the exit-side thickness substantially equal to the entry-side thickness. This state is referred to as a soft reduction state and, in the soft reduction state, no stop mark is formed in the rolled material 2 even with the rolling roll 1 being suspended. Note that 5 strictly speaking, the strip thickness slightly varies even in a soft reduction state, but the variation in strip-thickness is small enough to be ignored as compared with the case where the rolling roll 1 is suspended in a state of rolling.
[0070] Then, in a case of suspending the rolling in order to change the rolling direction, putting the rolled material 2 into an elastically deformed state, that is, a soft 10 reduction state will prevent a stop mark from being formed in the finished coil. Therefore, using this soft reduction method allows for producing a finished coil with substantially the same production efficiency as the conventional generic rolling procedure, without deteriorating quality of the finished coil.
[0071] Hereinbelow, the rolling procedure based on the soft reduction method will 15 be described with reference to FIGS. 12 and 13. First, under sub-procedure 1 in FIG. 12, the coil (rolled material 2) is rolled over the entire length thereof from the base material thickness H1 (thickness level indicated by a thin broken line) to the exit-side strip-thickness h1 in the first pass (thickness level indicated by a bold dot-and-dash line). Next, under sub-procedure 2, the rolling direction is changed to roll the coil over 20 the entire length thereof to the exit-side strip-thickness h2 in the second pass. Note that the rolling in the first and second passes is the same as that of the conventional generic rolling procedure (see FIG. 7).
[0072] Next, under sub-procedure 3, in order to form the leader part A, the rolling load P3 is applied to roll the coil from the leading end to the coil position CP1-1, and 25 then the rolling load is reduced to the rolling load Pe2 and the rolling is suspended. Here, it is assumed that the rolling load Pe2 is a rolling load with which the exit-side strip-thickness becomes substantially equal to the entry-side strip-thickness h2, and at this time a portion of the rolled coil is in an elastically deformed state. Next, under sub-procedure 4, the rolling direction is changed rightward so as to resume the rolling 30 in a state where the rolling load Pe2 is still applied to the coil, that is, the portion of the rolled coil is still in the elastically deformed state. The rolling load is then increased to a rolling load P4 to roll the leading end of the coil.
21
[0073] Next, under sub-procedure 5, the rolling direction is changed rightward so as to roll the coil over the entire length thereof based on the flying gauge change method. Note that in this case, a flying gauge change is executed at the coil position CP1-1 from the exit-side strip-thickness h5 to the exit-side strip-thickness h3.
[0074] Next, under sub-procedure 6 in FIG. 13, the rolling direction is changed 5 leftward so as to roll the coil with the rolling load P4 to the exit-side strip-thickness h4 therefrom to the coil position CP1-2, and then the rolling load is reduced to the rolling load Pe3 for putting a portion of the rolled coil into an elastically deformed state, before the rolling is suspended. Then, under sub-procedure 7, the rolling direction is changed rightward in the elastically deformed state and the rolling load is increased 10 to the rolling load P5 to roll the coil therefrom to the coil position CP1-3. As a result, the leader part B having the exit-side strip-thickness h5 is obtained. Then, the rolling load is reduced to the rolling load Pe4 to continue the rolling to have the exit-side strip-thickness h4 therefrom to the coil position CP1-4. Finally, the flying gauge change is executed at the coil position CP1-4 to roll the coil up to the trailer end so as 15 to have the exit-side strip-thickness h5, thereby finishing the rolling.
[0075] Note that rolling under sub-procedure 7 from the coil position CP1-3 to the coil position CP1-4 can be said to be rolling with soft reduction because the entry-side strip-thickness and the exit-side strip-thickness are equal to each other. Note that this part of the coil can be moved alternatively by reeling the rolled material 2 20 onto the left TR 3L or the right TR 3R in a state of reduction operation being released, that is, in a state of the upper and lower work rolls 1au, 1ad and the rolled material 2 not being in contact with each other.
[0076] FIG. 14 is a chart illustrating in detail the soft reduction method, and here, a description is given in detail of transitioning from sub-procedure 3 to sub-procedure 4 25 in FIG. 12. As shown in FIG. 12, in the soft reduction method, the rolling load P3 of the rolling roll 1 under sub-procedure 3 is reduced to the rolling load Pe2 (tension may be also reduced as required), with which the exit-side strip-thickness h3 of the rolled material 2 equals to the entry-side strip-thickness h2, to put the rolled material 2 in the vicinity just below the rolling roll 1 into an elastically deformed state. Once the 30 rolled material 2 is put into the elastically deformed state, the rolling by the rolling roll 1 is suspended, the rolling direction is reversed, and then the rolling is resumed. This inhibits any stop mark from being formed in the rolled material 2 (coil).
22
[0077] It should be noted that even in the rolling using this soft reduction method, the distance from the leading or trailing end to any point of the coil of the rolled material 2, which is being rolled, can be obtained, to calculate timings of starting to change such as the rolling load, the entry-side tension, and the exit-side tension as well as an elapsing time of changing the values. 5
[0078] FIG. 15 is, as described above, a diagram showing key points of the differences in the rolling procedure among rolling methods of producing the finished coil having the product specification <1> shown in FIG. 6. Additionally, FIG. 16 is a diagram showing key points of the differences in the rolling procedure among rolling methods of producing the finished coil having the product specification <2> shown in 10 FIG. 6.
[0079] In FIGS. 15 and 16, each of the bold solid arrowed lines indicates a rolling range and a rolling direction of the rolled coil. In addition, each of inverted triangles (∇) in the drawings represents a point where the rolling roll 1 needs to be suspended to change a rolling level or the rolling load, in other words, a point where a stop mark 15 is formed. Further, each of bold broken lines in the drawings represents a portion of the rolled coil which can be moved (reeled up) in a state of the reduction operation being released.
[0080] As shown in FIGS. 15 and 16, the rolling procedure based on the soft reduction method is characterized in that its operation efficiency is substantially equal 20 to that of the conventional generic rolling procedure, and there is no defect in thickness due to a stop mark in the finished coil. In contrast, the rolling procedure based on the flying gauge change method is characterized in that its operation efficiency is likely decreased because the rolled coil is rolled over the entire length thereof for the required number of times, but there is no defect in thickness due to a 25 stop mark in the finished coil.
[0081] However, depending on such as the number of leader parts formed in a finished coil, the rolling procedure based on the flying gauge change method may have better operation efficiency than that based on the soft reduction method. This is because the rolling procedure based on the flying gauge change method requires 30 less number of times of suspending the rolling roll 1. Incidentally, in the example in FIG. 15, the rolling procedure based on the flying gauge change method requires suspending the rolling roll 1 only five times, all at the time of suspension at both ends
23
of the coil, while the rolling procedure based on the soft reduction method requires such suspension seven times in total because of further suspension at the time of forming the leader parts A and B. Therefore, depending on the suspension time and/or the length of product parts A and B, the rolling procedure based on the flying gauge change method may have better operation efficiency than that based on the 5 soft reduction method.
[0082] Then, the rolling control device 200 according to the present embodiment has a function of evaluating the operation efficiency of each of the rolling procedure based on the flying gauge change method and the rolling procedure based on the soft reduction method, on the basis of specification of a finished coil of a rolled coil, 10 and selecting a rolling procedure having better operation efficiency. Further, according to the rolling procedure selected by said function, the rolling control device 200 controls rolling the rolled coil. These functions are implemented by the rolling procedure controller 20 (see FIG. 1) of the rolling control device 200. Hereinbelow, the rolling procedure controller 20 will be described in detail. 15
<4. Configuration and Function of Rolling Procedure Controller 20>
[0083] FIG. 17 is a diagram showing an example configuration of the rolling procedure controller 20 included in the rolling control device 200 according to the present embodiment. As shown in FIG. 17, the rolling procedure controller 20 includes a flying-gauge-change-rolling controller 21, a soft-reduction-rolling controller 20 22, a longitudinal position recognizer 23, and a production method selector 24.
[0084] In FIG. 17, the production method selector 24 estimates the operating time of rolling using each of the flying gauge change method and the soft reduction method with respect to inputted specification of a finished coil, and selects one having a shorter operating time as a rolling procedure for producing the finished coil. 25 Here, the specification of a finished coil means, for example, information such as distribution of thicknesses in the longitudinal direction of a coil having the product specification <1> or <2> shown in FIG. 6. In addition, the longitudinal position recognizer 23 calculates a position in the longitudinal direction of the rolled material 2 (distance from the leading end, for example) just below the rolling roll 1, based on the 30 number of rotations of the left TR 3L or the right TR 3R detected by the left TR tachometer 7L or the right TR tachometer 7R.
24
[0085] In the case where the flying gauge change method is selected by the production method selector 24, the flying-gauge-change-rolling controller 21 is activated for operation. The flying-gauge-change-rolling controller 21 calculates rolling load, a rolling speed, left tension, and right tension at the longitudinal position of the rolled coil calculated by the longitudinal position recognizer 23, according to 5 the rolling procedure based on the flying gauge change method shown such as in FIG. 9. Then, the flying-gauge-change-rolling controller 21 outputs the calculated rolling load, rolling speed, left tension, and right tension to the rolling load setter 19, the rolling speed setter 18, the left tension setter 13L, and the right tension setter 13R in FIG. 1. 10
[0086] Alternatively, in the case where the soft reduction method is selected by the production method selector 24, the soft-reduction-rolling controller 22 is activated for operation. The soft-reduction-rolling controller 22 calculates rolling load, a rolling speed, left tension, and right tension at the longitudinal position of the rolled coil calculated by the longitudinal position recognizer 23, according to the rolling 15 procedure based on the soft reduction method shown such as in FIGS. 12 and 13. Then, the soft-reduction-rolling controller 22 outputs the calculated rolling load, rolling speed, left tension, and right tension to the rolling load setter 19, the rolling speed setter 18, the left tension setter 13L, and the right tension setter 13R in FIG. 1.
[0087] In addition, as shown in FIG. 17, the production method selector 24 includes 20 subblocks such as a rolling procedure selector 25, an operating flying-gauge-change time estimator 26, an operating soft-reduction time estimator 27, and a finished coil pattern selector 28. Based on the identification name of a finished coil inputted by the production manager or the like, for example, the finished coil pattern selector 28 selects information about the distribution of thicknesses in the longitudinal direction of 25 the finished coil corresponding to the inputted identification name from among the finished coil pattern DB 50. Note that the format of the finished coil pattern DB 50 will be separately described with reference to FIG. 18.
[0088] The operating flying-gauge-change time estimator 26 generates a rolling procedure using the flying gauge change method, on the basis of the information 30 about the distribution of thicknesses in the longitudinal direction of the finished coil selected by the finished coil pattern selector 28, and estimates the total rolling time (operating time) according to said rolling procedure. Likewise, the operating soft-
25
reduction time estimator 27 generates a rolling procedure using the soft reduction method, on the basis of the information about the distribution of thicknesses in the longitudinal direction of the finished coil selected by the finished coil pattern selector 28, and estimates the total rolling time (operating time) according to said rolling procedure. 5
[0089] The rolling procedure selector 25 compares the operating time estimated by the operating flying-gauge-change time estimator 26 with that estimated by the operating soft-reduction time estimator 27 to determine the rolling procedure having a shorter operating time. Then, based on the comparison result, the rolling procedure selector 25 notifies the flying-gauge-change-rolling controller 21 or the soft-reduction-10 rolling controller 22 of the estimated result. Note that at this time, the information about the distribution of thicknesses in the longitudinal direction of the selected finished coil is also notified to the flying-gauge-change-rolling controller 21 or the soft-reduction-rolling controller 22.
[0090] FIG. 18 is a diagram showing an example format of the finished coil pattern 15 DB (database) 50. As shown in FIG. 18, the finished coil pattern DB 50 is a database in which information about the distribution of thicknesses in the longitudinal direction of finished coils to be produced is registered in advance. That is, in the finished coil pattern DB 50, information about the distribution of thicknesses in the longitudinal direction of the finished coils is registered in association with the respective 20 identification names of the finished coils. Additionally, in the finished coil pattern DB 50, the registered information about the distribution of thicknesses in the longitudinal direction of the finished coils is sorted by the number of leader parts, the number of thicknesses in the product parts (the number of product parts having different thicknesses), and the like. 25
[0091] In addition, for those patterns having the distribution of thicknesses in the longitudinal direction of the finished coil selected by the finished coil pattern selector 28, having the operating times estimated by the operating flying-gauge-change time estimator 26 or the operating soft-reduction time estimator 27, and then having the rolling procedures selected by the rolling procedure selector 25, such results may be 30 registered in the finished coil pattern DB 50.
[0092] For example, in FIG. 18, the finished coil having specification <1> indicates that the rolling procedure based on the flying gauge change method has required a
26
shorter operating time than that based on the soft reduction method. On the contrary, the finished coil having specification <2> indicates that the rolling procedure based on the soft reduction method has required a shorter operating time than that based on the flying gauge change method. Additionally, detailed procedural information of the selected rolling procedure (information about the sub-procedures such as in FIGS. 5 9, 12, and 13) may also be registered in the finished coil pattern DB 50.
[0093] As described above, on the condition that the selected rolling procedure and the detailed information about the rolling procedure are registered in the finished coil pattern DB 50, rolling a coil so as to have the same specification as that of the registered finished coil no longer requires estimating the operating time or the like. 10 Therefore, the load on the computer including the production method selector 24 is reduced.
[0094] Note that in the above description of the production method selector 24, the operating flying-gauge-change time estimator 26 and the operating soft-reduction time estimator 27 are designed to calculate the respective rolling procedures based 15 on the information about the distribution of thicknesses in the longitudinal direction of a given finished coil. Here, the rolling procedure means a specific one shown such as in FIG. 9, 12, or 13, and such a rolling procedure is more efficiently generated in many cases with a skilled operation engineer or engineers taking part therein. Therefore, it is assumed that computer programs implementing the operating flying-20 gauge-change time estimator 26 and the operating soft-reduction time estimator 27 are coded so that the operation engineer(s) can take part as appropriate.
[0095] FIG. 19 is a chart showing an example of a basic form of a rolling speed pattern on the condition that the maximum rolling speed Vo is given. Here, it is assumed that the rolling speed is accelerated, when the rolling is started, at a 25 predetermined acceleration “α” until it reaches the maximum rolling speed Vo, while the rolling speed is decelerated, when the rolling is stopped, at a predetermined acceleration “–α” from the maximum rolling speed Vo. In this case, the rolled length “l” is calculated as the area of the trapezoid represented by the rolling speed pattern. Then, the rolling time “t” since the rolling is started until the rolling is stopped is 30 calculated by the formula shown in the square frame in FIG. 19.
[0096] Therefore, each of the operating flying-gauge-change time estimator 26 and the operating soft-reduction time estimator 27 first generates a rolling speed pattern
27
as shown in FIG. 20 or 21 for generating a rolling procedure based on the information about the distribution of thicknesses in the longitudinal direction of the given finished coil. Here, FIG. 20 is a diagram showing an example of a rolling speed pattern in each pass in a rolling procedure based on the flying gauge change method, while FIG. 21 is a diagram showing an example of a rolling speed pattern in each pass in a 5 rolling procedure based on the soft reduction method. It is assumed here that the rolling speed in each pass is VL for the leader parts A, B and C, and the rolling speeds in respective passes are V1 to V5 for the product parts A and B. Note that strictly speaking, these rolling speed patterns are different from actual rolling speed patterns, but rarely matter for estimating the rolling time. 10
[0097] The rolled length of the rolled coil varies depending on the delivery destination of the finished coil, the size (length) of the base coil material, and the like, and information about what finished coil is to be produced is determined by an operation engineer or an operator, before the rolled coil is rolled. These pieces of information are part of the finished coil specifications shown in FIG. 17, and detailed 15 information such as the rolling speed is to be registered beforehand in the finished coil pattern DB 50 in association with the identification information of the product specification.
[0098] FIG. 22 is a diagram showing an example of calculation formulas for calculating the rolled lengths of respective leader parts and product parts in each 20 pass in the rolling procedure based on the flying gauge change method. Likewise, FIG. 23 is a diagram showing an example of calculation formulas for calculating the rolled lengths of respective leader parts and product parts in each pass in the rolling procedure based on the soft reduction method. Note that the examples of the calculation formulas shown in FIGS. 22 and 23 relate to the finished coil of the 25 product specification <1> in FIG. 6.
[0099] In general, the mass flow constant rule (volume constant rule) holds true for rolling the rolled material 2, and then [(the strip thickness) x (the rolled length)] is constant even after the rolling. Therefore, once the final rolled length and the exit-side thickness in each pass are given, the rolled length in each pass can be 30 calculated. Note that in this example, the product specification <1> in FIG. 6 gives the final rolled lengths of the leader pars A, B, C being LDA, LDB, LDC, respectively, and the final rolled lengths of the product parts A, B being LA, LB. Additionally, the
28
exit-side strip-thicknesses of the leader parts A, B, C and the product parts A, B in each pass are also given. Therefore, the rolled lengthes of respective parts in each pass can be calculated.
[0100] As described above, once the rolled length and the maximum rolling speed in each pass are given, the rolling time in each pass can be calculated. However, in 5 the actual rolling operation, machine operation by the operator and confirmation of the operation result are required for changing over the rolling direction, and it takes a certain amount of time. Therefore, the operating time should take the time required for changing over the rolling direction into account.
[0101] In the rolling procedure based on the flying gauge change method, the 10 rolling direction is switched when each of sub-procedures 1 to 5 is completed, as shown in FIG. 9. Likewise, in the rolling procedure based on the soft reduction method, the rolling direction is switched when each of the sub-procedures 1 to 7 is completed, as shown in FIGS. 12 and 13. However, in two of these, at the completion of each of sub-procedures 3 and 6, the rolling direction is switched in a state of soft 15 reduction. Normally, the time of switching the rolling direction in a state of the soft reduction is different from that in a state of a strip thickness being reduced.
[0102] The switching time in actual rolling operation is measured to obtain such a time of switching the rolling direction. Therefore, the average value of the actually obtained switching times may be stored as the time of switching the rolling direction 20 in a state of a strip thickness being reduced or the time of switching the rolling direction in a state of soft reduction into the storage device or the like inclusive of the finished coil pattern DB 50.
[0103] FIG. 24 shows an example flowchart of an operating-time estimation process. As shown in FIG. 24, the operating flying-gauge-change time estimator 26 25 first calculates the rolled length in each rolling pass (each of sub-procedures 1 to 5 in FIG. 9), based on the finished coil specification (step S10). The formulas shown in FIGS. 22 and 23 may be used to execute this processing.
[0104] Subsequently, the operating flying-gauge-change time estimator 26 calculates the rolling time, based on the maximum speed, the rolled length, etc. in 30 each rolling pass (each of sub-procedures 1 to 5 in FIG. 9) (step S20). This calculation uses the rolling speed pattern shown in FIGS. 20, 21 and the formulas for
29
calculating the rolling time shown in FIG. 19. At this time, the rolling speed patterns shown in FIGS. 20 and 21 are retrieved from the finished coil pattern DB 50.
[0105] Next, the operating flying-gauge-change time estimator 26 adds the time of switching the rolling direction in respective rolling passes to the total rolling time in respective rolling passes obtained as described above to calculate the operating time 5 (step S30 ). At this time, the time of switching the rolling direction is retrieved from the finished coil pattern DB 50.
[0106] Note that the flowchart of the operating time estimation process in the operating soft-reduction time estimator 27 is also the same as that in FIG. 24, so the description thereof is omitted herein. 10
<4. Advantageous Effects>
[0107] As described above, according to the embodiment of the present invention, either the rolling procedure based on the flying gauge change method or the rolling procedure based on the soft reduction method causes no defect in thickness in the finished coil to be produced due to a stop mark. Therefore, deteriorating product 15 quality can be inhibited.
In addition, in the present embodiment, the operating time is estimated according to the product specification of the finished coil in either case of using the flying gauge change method or the soft reduction method of the product coil, to produce the finished coil in accordance with the rolling procedure having a shorter operating time. 20 Therefore, the operating time is shortened to improve the operation efficiency of the rolling.
<5. Complements>
[0108] Hereinabove, in the present embodiment, the base material of the rolled material is assumed to have an even thickness in the longitudinal direction of the coil, 25 but the rolling control device 200 according to the present embodiment can also be applied to a case where the base material has an uneven thickness.
[0109] In addition, the present embodiment is configured to select a rolling procedure based on the estimated value of the operating time, but may be configured to select a rolling procedure based on required accuracy of the strip thickness 30 according to the product specification of the rolled material. In general, the rolling procedure based on the flying gauge change method gives better accuracy of the strip thickness than the rolling procedure based on the soft reduction method,
30
because of the smaller number of suspension times of the rolling roll 1. Therefore, the selection criterion in this case is whether or not to select a rolling procedure based on the flying gauge change method, which has better accuracy of the strip thickness, at the expense of operational efficiency.
[0110] Further, the present embodiment is directed to the single-stand rolling mill 5 100, but the same technique as that of the present embodiment is also applied to a tandem rolling mill having two stands or more, in which the rolling direction is changed over to increase the number of rolling passes.
Furthermore, the present embodiment is configured to change the rolling load during soft reduction or flying gauge change, but the same technique may also be 10 applied to a case where a roll gap required for obtaining the rolling load is calculated to control the roll gap for changing the rolling load.
[0111] It should be noted that the present invention is not limited to the embodiments and modifications described above, and various modifications are further included. For example, the above-described embodiments and modifications 15 have been described in detail for the purpose of illustrating the present invention, and are not necessarily limited to those including all the components described herein. In addition, part of a certain embodiment or modification may be replaced by that of another embodiment or modification, or a certain embodiment or modification may be added with part of another embodiment or modification. Further, part of each 20 embodiment or modification may be deleted, or added with / replaced by that included in other embodiments or modifications.

WE CLAIM:
1. A rolling control device for use in a single-stand rolling mill that includes two vertically-arranged rolling rolls to apply a load to a rolled material, which is sandwiched between the two rolling rolls, and pass the rolled material between the two rolling rolls while rotating the rolling rolls for rolling the rolled material, 5
the rolling control device comprising
a soft-reduction thickness change control means that, at a time of the rolled material having an entry-side thickness of a first thickness being rolled with a first load applied thereto so that the rolled material has an exit-side thickness of a second thickness, sequentially executes: 10
first control in which a load applied to the rolled material is reduced from the first load to a second load with which the rolled material has an exit-side thickness of substantially the same thickness as the first thickness;
second control in which the rotation of the rolling rolls is suspended in a state that the second load is applied to the rolled material; 15
third control in which the rotation of the rolling rolls is resumed but in the reverse rotational direction in a state that the second load is applied to the rolled material; and
fourth control in which a load applied to the rolled material is increased from the second load to a third load with which the rolled material has an exit-20 side thickness of a third thickness that is smaller than the second thickness.
2. The rolling control device according to claim 1, further comprising:
a flying-gauge-change control means that, at the time of the rolled material having an entry-side thickness of the first thickness being rolled with the first load 25 applied thereto so that the rolled material has an exit-side thickness of the second thickness, executes:
fifth control in which a load applied to the rolled material is changed, in a state that the rolling rolls are being rotated, from the first load to a fourth load with which the rolled material has an exit-side thickness of a fourth 30 thickness that is different from the second thickness.
3. The rolling control device according to claim 2, further comprising:
34
a rolling procedure control means that controls a rolling procedure for producing a finished coil formed of multiple parts sectioned in the longitudinal direction to have different thicknesses from one another after the rolled material is rolled multiple times by the rolling rolls of the single-stand rolling mill, wherein the rolling procedure control means includes: 5
a soft-reduction-rolling control means that, when the rolling direction of the rolled material is changed at positions except for both ends of the rolled material, controls rolling at the time of producing the finished coil, based on a rolling procedure inclusive of changing the rolling direction using the soft-reduction thickness change control means; and 10
a flying-gauge-change-rolling control means that, when a thickness of the rolled material is changed at positions except for both ends of the rolled material, controls rolling at the time of producing the finished coil, based on a rolling procedure inclusive of changing the thickness using the flying-gauge-change control means. 15
4. The rolling control device according to claim 3, wherein
the rolling procedure control means further includes:
an operating time estimation means that, on the basis of an inputted product specification of the distribution of thicknesses in the longitudical direction of the finished coil, estimates a first operating time for producing the 20 finished coil according to a rolling procedure based on the soft-reduction-rolling control means, and a second operating time for producing the finished coil according to a rolling procedure based on the flying-gauge-change-rolling control means; and
a rolling procedure selection means that compares the first operating time 25 with the second operating time, and then selects, as the rolling procedure for producing the finished coil, a rolling procedure based on the soft-reduction-rolling control means if the first operating time is shorter than the second operating time, or a rolling procedure based on the flying-gauge-change-rolling control means if the first operating time is equal to 30 or longer than the second operating time.
5. A rolling control method for use in a rolling control device of a single-stand rolling mill that includes two vertically-arranged rolling rolls to apply a load to a rolled
35
material, which is sandwiched between the two rolling rolls, and pass the rolled material between the two rolling rolls while rotating the rolling rolls for rolling the rolled material,
the rolling control method, for sequential execution at a time of the rolled material having an entry-side thickness of a first thickness being rolled with a first load applied 5 thereto so that the rolled material has an exit-side thickness of a second thickness, comprising:
reducing, as first control, a load applied to the rolled material from the first load to a second load with which the rolled material has an exit-side thickness of substantially the same thickness as the first thickness; 10
suspending, as second control, the rotation of the rolling rolls in a state that the second load is applied to the rolled material;
resuming, as third control, the rotation of the rolling rolls but in the reverse rotational direction in a state that the second load is applied to the rolled material; and 15
increasing, as fourth control, a load applied to the rolled material from the second load to a third load with which the rolled material has an exit-side thickness of a third thickness that is smaller than the second thickness.
6. The rolling control method according to claim 5, further comprising:
as fifth control at the time of the rolled material having an entry-side thickness 20 of the first thickness being rolled with the first load applied thereto so that the rolled material has an exit-side thickness of the second thickness, changing a load applied to the rolled material, in a state that the rolling rolls are being rotated, from the first load to a fourth load with which the rolled material has an exit-side thickness of a fourth thickness that is 25 different from the second thickness.
7. A rolling control method using a rolling control device of a single-stand rolling mill that includes two vertically-arranged rolling rolls to apply a load to a rolled material, which is sandwiched between the two rolling rolls, and pass the rolled material between the two rolling rolls while rotating the rolling rolls for rolling the 30 rolled material, wherein the rolling control device includes:
a soft-reduction thickness change control means that, at a time of the rolled material having an entry-side thickness of a first thickness being rolled
36
with a first load applied thereto so that the rolled material has an exit-side thickness of a second thickness, sequentially executes:
first control in which a load applied to the rolled material is reduced from the first load to a second load with which the rolled material has an exit-side thickness of substantially the same thickness as 5 the first thickness;
second control in which the rotation of the rolling rolls is suspended in a state that the second load is applied to the rolled material;
third control in which the rotation of the rolling rolls is resumed but in the reverse rotational direction in a state that the second load is 10 applied to the rolled material; and
fourth control in which a load applied to the rolled material is increased from the second load to a third load with which the rolled material has an exit-side thickness of a third thickness that is smaller than the second thickness so as to be executed in the order as listed 15 below, at a time of the rolled material having an entry-side thickness of a first thickness being rolled with a first load applied thereto so that the rolled material has an exit-side thickness of a second thickness; and
a flying-gauge-change control means that, at the time of the rolled material 20 having an entry-side thickness of the first thickness being rolled with the first load applied thereto so that the rolled material has an exit-side thickness of the second thickness, executes
fifth control in which a load applied to the rolled material is changed, in a state that the rolling rolls are being rotated, from the first load to 25 a fourth load with which the rolled material has an exit-side thickness of a fourth thickness that is different from the second thickness,
the rolling control method comprising, at a time of controlling a rolling procedure for producing a finished coil formed of multiple parts sectioned in the longitudinal 30 direction to have different thicknesses from one another after the rolled material is rolled multiple times by the rolling rolls of the single-stand rolling mill:
37
controlling rolling at the time of producing the finished coil, when the rolling direction of the rolled material is changed at positions except for both ends of the rolled material, based on a first rolling procedure inclusive of changing the rolling direction using the soft-reduction thickness change control means; and 5
controlling rolling at the time of producing the finished coil, when a thickness of the rolled material is changed at positions except for both ends of the rolled material, based on a second rolling procedure inclusive of changing the thickness using the flying-gauge-change control means.
8. The rolling control method according to claim 7, further comprising: 10
estimating, on the basis of an inputted product specification of the distribution of thicknesses in the longitudical direction of the finished coil, a first operating time for producing the finished coil according to the first rolling procedure, and a second operating time for producing the finished coil according to a rolling procedure based on the second rolling procedure; 15 and
comparing the first operating time with the second operating time, and then selecting, as the rolling procedure for producing the finished coil, the first rolling procedure if the first operating time is shorter than the second operating time, or the second rolling procedure if the first operating time 20 is equal to or longer than the second operating time.
9. A non-transitory computer readable medium storing a program causing a computer to execute the rolling control method according to any of claims 5 to 8.