DESCRIPT.t.ON TITLE OF INVENTION: ROLLING CONTROL APPARATUS, ROLLING CONTROL METHOD, AND ROLLING CONTROL PROGRAM TECHNICAL FIELD t 0001 l The present inventlon relates to a rolling control apparatus, a roll-ing control method and a rolling controf program/ and relates more specifically to learning a parameter of a rolling control- while executing rolling for producing an actual product. BACKGROUND ART t 0002 l In a rolling mil-l-, rolling operation is executed by controlling tensj-on and rolling load applied to a rol-l-ed material using a ro11 gap that is a space between upper and fower work rolls and the rol-1 speed of facil-i-tles before and after the rolling mill. In the rolling ooeraEion, a feedback control is executed which is for operating the roll- gap and the roll- speed which are control manipulateci var:-able of the rolling mill accordi-ng to a preset pattern, a::c naintaining the sheet thj-ckness, tenslon, and rolllng ,336 of the rolled material which are the control state amounts of the rolling mill at preset values. t00031 When a pattern for operating speed as described above is to be using the deformation resistance such the rol-1 gap and the rol-l formed, calculation is executed of the rol-Ied material- and the l- l iiii-i037-rN (PCT) friction coefficient of the rol-Ied material and the wcrk rolfs of the rol-l-ing mi1I. Therefore, in order to form a pattern with high accuracy of the rolling result in flying sheet thickness change for changing the target sheet thickness without stopping the rolling operation/ accel-eration and decel-eration of the rolling speed and the like, i-t is required to obtain the deformation resistance and the friction coefficient with high accuracy. | 0004 l However, these deformation resistance and friction coefficient are dynamic parameters changing according to an operation state such as the friction of the work rolIs and the roll coofant and the l-ike and a state of a material of a nonrolled material, and are required to be obtained again when the condition changes. Therefore, it is desired to increase the sample number by obtaining the deformation resistance and the friction coefficj-ent based on values measured while roJ-ling operation is executed. t000sl From the past, methods for obtaining an appropriate parameter during rolling operation have been proocsei variously (refer to Patent Literatures 1 to 3 for example) . Ho-*ever, the methods disclosed in the literatures are methods for cbtaining an appropriate parameter for correctlng a parameter, and are different in the purpose from the invention of the present application which acqulres data samples under various conditions while executing the ro1I1ng operation. CITATION L]ST HH-1037-rN (PCT) PATENT LITERATURES t 00061 PATENT LITEMTURE 1: Japanese Unexamined Patent Application Publicati-on No. H6-15318 PATENT LITERATURE 2: Japanese Unexamlned Patent Application Publicati-on No. 2001-245204 PATENT LITERATURE 3: Japanese Unexamj-ned Patent Application Publication No . 2009-208115 SUMMARY OE INVENTION TECHNICAI PROBLEMS t 0007 l The frlction coefficient p can be calculated by a mathematlcal model using the rol-l-ing speed. In general, the behavior of the friction coefficient becomes conspicuous in a low speed section. In order to secure the sample numbers with respect to the speed, j-t is desired to take data j-n a speed band of a wide range. Also, the deformation resistance k can be calculated by a mathematical model that uses the draft and the rolling speed. By intentionally operating the draft in calculating the deformation resistance, it is possibl-e to increase the data sample number of the deformation resistance and to improve the calculation accuracy of the deformation resistance. t000Bl However, when many drafts are changed i-n one cycle and the change amount of the final draft is excessively increased, offgage occurs which is a problem that the sheet thickness after rolling does not satisfy the product quality, and therefore it is .r I HH-1037-IN (PCT) difficult to obtain the data sample whil-e executing the rolling operation. Accordingly, in order that the product is not affected, the draft that is the sheet thickness preset val_ue should be changed within a range the sheet thickness control can assist. l000el The present invention has been developed in view of the circumstances as described above, and its object is to acquire data samples under various conditions while executing the rolling operatlon without deteriorating the product quality. SOLUTION TO PROBLEMS t0 010l An aspect of the present invention is a rolling controlapparatus that controls a tandem rolling mill that rolls a rolled material wlth a plurality of pairs of rolls including: a roll gap control unit that controls a roll gap of the plurality of pairs of rolls by a feedback control so as to bring a sheet thickness of the roll-ed material rol-red by the prurality of pairs of rol-ls closer to a preset sheet thickness designated; a transporting speed presetting unlt that presets a time-sequentlal change of a transporting speed of the rolled material; a preset sheet thickness change setting unit that presets a time-sequential change of a preset sheet thickness for controlling a roll gap of rolls other than rolls of the rearmost stage out of the plurality of pai-rs of rolls based on the time-sequential change of the transporting speed preset; and a parameter calculating unit that calculates a parameter in control of the rolling mill based on a measured value in a rolling state in rolling executed based on t L,lt-ll ll-1 HH-1037-rN (PCr) the transporting speed and the preset sheet thickness preset so as to change time-sequentially. t 0 0111 AIso, another aspect of the present inventi-on is a rolli-ng control method that control-s a tandem rolling mill that rol-ls a rolled material with a pIuraIlty of pairs of rol-Is including the steps of: controlling a roll gap of the plurality of pairs of rolls by a feedback control so as to bring a sheet thickness of a rol-led material roll-ed by the plurality of pairs of rolls closer to a preset sheet thickness designated; presetting a timesequential change of a transportation speed of the rolled material; presetting a time-sequentj-al change of a preset sheet thickness for controlling a roll- gap of rol-Is other than roll-s of the rearmost stage out of the plurality of pairs of rolls based on the time-sequential change of the transportation speed preset; and calculating a parameter in control- of the rolling mill based on a measured value in a rolling state in rolli-ng executed based on the transporting speed and the preset sheet thickness preset so as to change time-sequentially. i 0012 l Further, a still- other aspect of the present invention is a rolling control- program that controls a tandem rolling mil1 that roll-s a rolled material with a plurality of pairs of rol-Is making an information processing apparatus execute: a step of controlling a roll gap of the plurality of pairs of rol-ls by a feedback control so as to bring a sheet thickness of a roll-ed material- rolled by the plurality of pairs of rolls closer to a preset sheet thickness designated; a step of presetting a time- I I llill i_l -. , I ll -r[r.nLil]ltllll I .11,..,1 HH-1031-rN (PCT) seqrlentj-al change of a transportation speed of the roll-ed material; a step of presetting a time-sequential change of a preset sheet thickness for control-ling a ro11 gap of roll-s other than roli-s of the rearmost stage out of the plurality of pairs of roll-s based on the time-sequential- change of the transportation speed preset; and a step of calculating a parameter in control of the rol-ling mil1 based on a measured value in a rolling state j-n rolling executed based on the transporting speed and the preset sheet thickness preset so as to change time-sequentially. ADVANTAGEOUS EFFECTS OF TNVENTTON l0 013l According to the present invention, data samples can be acquired under various conditions while executing the rolling operation without deteriorating the product qualj-ty. BR,IEF DESCRIPTION OF DRAWINGS I 0014 l [Fiq. 1] Fig. 1 is a drawing showing an entire structure of a roIling mill and a rolling control apparatus according to an e=.codiment of the present invention. [Fig. 2) Fig. 2 ts a drawing showing a hardware configuration of the rolling contro1 apparatus according to an embodiment of the present invention. [Fiq. 3] Fig. 3 is a flow chart showing a determination motion of a rolling mode according to an embodiment of the present invention. [Fig. 4) Frg. 4 is a timing chart of a rolling contro]- HH-1037-rN (PCT) according to an er,bodiment of the present invention. [Fig. 5] Fig. 5 1s a drawing showing a calcul-ation form of a preset sheet thickness change amount accordi-ng to an embodiment of the present invention. [Fig. 6] Fig. 6 is a drawing for describing a determination form of a draft change rate according to an embodiment of the present invention. [Fig. '7) Fig. 7 is a drawing showing an application example of the maximum draft change amount according to an embodiment of the present invention. [Fig. 8] Fig. B is a flow chart showing a motion of an abnormality detection unit according to an embodiment of the present invention. [Fig. 9] Fig. 9 is a timing chart of a rolling controlaccording to an embodiment of the present invention. DESCRIPTION OF EMBODiMENTS t 001s l Embodiment 1 In the preseo*u embodiment, an example of control wifl- be described in which, ':l a tandem rolling mill incl-uding four roll stands, rollj-ng is executed while changing the roll-ing condition such as the roll gap of the roII stands other than that of the rearmost stage, thereby the data sampJ-es under various conditions are collected, the deformatj-on resistance and the friction coeffj-cient are calculated, and the rolling model is l-earnt. t0 016l Fig. 1 is a block diagram showing a functional configuratj-on - t"t ' I HH-1037-rN (PCT) of a rolling miIl 10 and a rolling ccn'Lro1 apparatus 100 according to the present emlcodiment. As shown in Fig. 1, the rolling mil-I 10 according to the present embodiment incfudes four roll stands L, and sheet thickness meters 2 measuring the sheet thlckness he to ha of a ro1led material M are arranged between the respective roll- stands 7, in the front stage of the roll- stand 1 of the foremost stage, and in the rear stage of the ro11 stand 1 of the rearmost stage. Also, in the respective roll- stands L, rolling load measuring apparatuses 3 measuring the rolling loads P1 to Pa with respect to the rolled material are arranged. t 0017 l Further, i-n each of the respective ro11 stand 1, a PLG (Pul-se Logic Generater) 4 measuring the roll speeds RV1 to RVa of work rolls actually rolling the rolled material is arranged, and it is used as the roll speed measuring apparatus. Also, as shown in Fig. 1, the work roll-s of the roll- stands l are driven by motors M. t001Bl In the rolling mil-l 10 according to the present embodiment, the sheet-like rolled material M wound into a coil shape is rewound, is fed to the rolling mill iC, a::ci i-s rolled in order by the plural rol-l stands 1 shown in Fig. i. in the rolling controlapparatus 100 according to the present embodiment, rolling control is executed for each one coil- by which the rolled material- is wound. AIso, when the rolling materials of different coils are to be rolled continuously, the rear end of the rolled material included in a coil during rolling and the front end of the rolled material of a coil to be rolled next are connected to IL HH-1037-IN (?CT) each other by welding and the like, and thereby rolling is executed continuously. At that time, the rolled materi-al of the coil that has completed rolling is cut and detached from the rolled material- of the coil of the rear stage after the roll speed is slowed down. The control- of the rofl speed i-n cutting and detaching the rol-Ied material- is one of the points according to the present embodiment. i 0 0191 On the other hand, as shown in Fig. 1, the rolll-ng control apparatus 100 incl-udes a rolling state monitoring unit 101, a friction coefficient cal-culation unit 702, a deformation resistance cal-cul-ation unit 103, a rolling load calcul-ation unj-t 704, a setup calcul-ation unit 105, a speed change amount calculation unit 106, a cut speed change unit 10'1, a draft change specification calculation unit 108, a preset sheet thickness change unit 109, an integrator reset unit 110, a rol-l- gap control unit 771, an abnormality monitoring unit 7L2, a draft change amount correction uni-t 11-3 and an al-arm output unit 7!4. t0 02 01 The rolling state monitoring unit 101 monitors the ror.:-ing state in the rolling mill 10 by acquiring information of h3 --c ha, P1 to Pa, RV1 to RVa described above from the rolling miIl 1C. The friction coefficient calculatlon unit 702 and the deformatlon resistance cal-culation unit 103 acquire the information of ho to lns, P1 to Pa, RV1 to RV4 described above from the roll-ing state monitoring unit 101, and calculate the friction coefficient p and the deformation resistance k respectively based on an expression (1) below. l.lu.-l ,l I - I HH-1037-IN (PCT) P-b.k.fr (H, h) .fz (l.r) .Zp (1) b: sheet width k: deformation resistance fr: tension correction term fzz friction coefficient correction term Zpi learning factor t0 0211 In the expression (1), P is the rol-ling load of the roll stand 1, b is the sheet width of the rol-led material, k is the deformation resistance of the rolled material, f1 is the tension correction term of the rolled material-, and f2 is the friction coeffi-cient correction term of the rol-l-ed material and the work rol-Is. Also, Zo is the known learnj-ng factor for l-earning a calculated value of the rolling load from the rolling load of the actual resul-t. Further, H that is a parameter of f1 is the sheet thickness of the rolled materlal on the entry side of the ro11 stand, and h is the sheet thickness of the rol-Ied material- on the exit side of the ro11 stand. For example, when the rol-Iing state in the ro11 stand 1 positloned at the l-eftmost side in Fig. 1 is to be calculated, Pr is used for the rolling' load P, he is used for H that is the parameter of the tension correction term f1, and hi is used for h respectively. 10022) The rolling load calculation unit 104 determines the loading load in rolling of the next coil- based on the friction coefficient p calculated by the friction coefficient calculation unit 702, the deformation resistance k calculated by the deformation resistance calculation unit 103, and the rolling 10 I ___t HH-1037-rN (PCT) result acquired by the rolling state monitoring unit 101. That is, the frj-ction coefficient calculation unit 702, the deformation resistance calculation unit 103 and the rolling load calculation unit 104 function as parameter calculation units that calculate parameters in control of the roll-J-ng mil1 10. t0 02 31 The setup cafculation unit 105 determines the rolling condition including the line speed in the rolling mil1 10 and the draft in each roll stand for each coil rolled in the rolling mill 10. In the present embodiment, to acquire vari-ous data samples by executj-ng rolling under various conditions in the rolling mlll 10 is the object. The setup calculation unit 105 control-s varj-ous conditions for it. 100241 The speed change amount calculation unit 106 determines the speed of the time the motor M drives the work rolls of the rol-1 stand 1, which is the rolling speed, based on the rolling condition determined by the setup calculation unit 105. A1so, the speed change unj-t 701 controls the rotational speed of the time the motor M drives the work rolls based on the rolling speed determined by the speed change amount calculation unit 106. [ 002s ] The draft change specification calculation unit 108 controls presetting of the draft of the rolled material rolled by the work rolls of the roII stand 1 based on the rolling condition determined by the setup calculation unit 105. More specifically, the draft change specification calculation unit 108 determines the change amount of the draft in addition to the timing of 11 i I r,Lll rr-1 -- I - HH-1037-rN (PCT) starting and the timing of finishing of changing the draft. [0026] The preset sheet thickness change unit 109 determines the preset sheet thlckness based on the change start timing, the change finish timing and the change amount of the draft determined by the draft change specification calculation unit 108. This preset sheet thickness is a target value used in a feedback control- of the rolling result. The integrator reset unit 110 outputs a reset signal for resetting the J-ntegrati-ng period in the feedback control according to the change of the preset sheet thickness inputted from the preset sheet thickness chanqe unit 109. t0027l The roll gap control unit 111 adjusts the roll gap of the roll- stand 1 based on an expression (2) below based on the information of ho to ha inputted from the rolling state monj-toring unit 101 and the preset sheet thickness inputted from the preset sheet thickness change unit 109. aS=FCrah (2) AS: roll gap change amount Ah: exit slde sheet thickness deviation t00281 AS is the roll- gap change amount outputted by the roll gap control- unit 111 outputs as a control- val-ue for the feedback control-, and Ah is the deviation of the sheet thickness on the exit side of the roll- stand 1 inputted from the roll-ing state monitoring unit 101 from the preset sheet thickness. Also, C is a L2 . t I 1..1 HH-1031-rN (PCT) constan-L ietermined by the characterj-stics of the ro11 stand 1 and the rol-l-ed material- M. t002el In the present embodiment, the rolling state monitoring unit 101 acquires the information of he to ha, P1 to Pa, RV1 to RVa at a predetermined sampling period. Also, the roll gap control- unit 111 executes the feedback control by calculating the roll gap change amount according to the expression (2) above and outputting the same according to the sampling period. A1so, the rol-1 grap control- unlt 111 makes the total period when the information of the rol-ling state has been inputted from the rolling state monitoring unit 101 the integrating period until a reset signal is inputted from the integrator reset unit 110, and resets the integrating period when the reset signal is inputted. [0030] AIso, as shown in Fig. 1, the rol-ling miI} 10 includes four roll stands 1. Therefore, the preset sheet thickness change unit 109 and the roll gap control unit 111 according to the present embodimen-L control the preset sheet thickness for each ro11 stand 1. A1so, tri"ie preset sheet thickness of the f ourth roll- stand which is :::e rearmost stage out of the four rol-I stands l- shown in Eig. .:- is made the product sheet thickness that is the final target sheet thickness, and the first-third preset sheet thicknesses are preset so as to gradually approach the product sheet thickness from the original sheet thickness of the rolled material. t 0031 l The abnormality monitoring unit 112 monitors whether the 13 lr'il!r'7r 11 | L ,l.. HH-1037-rN (PCT) all-owable range as the preietermined product sheet thickness has been satisfied or not based on the information of ha that becomes the final product sheet thj-ckness out of the information of the rolling state acquired by the rolling state monitoring unlt 101. When the val-ue of ha deviates from the allowabl-e range as the product sheet thickness, the abnormality monitoring unit L72 outputs an abnormallty detection signal showing that abnormality has been detected. Also, the abnormali-ty monitorj-ng unit LL2 detects a slip between the roll stand 1 and the roll-ed materialbased on the information of h6 to ha, P1 to Pa, RV1 to RVa acQuj-red by the rolling state monitoring unit 101. In other words, the abnormality monitoring unit Ll2 is an abnormality detection unit that detects abnormality of rolling. t 0032 l The draft change amount correction unit 113 outputs a contro1 signal for making the draft change specification calculation unit 108 correct 'uhe preset val-ue of the draft based on the abnormality detection signal outputted by the abnormality monitoring unit 7L2. The aiar:r,. output unj-t ll-4 notif ies an operator of occurrence of -.he off-gage based on the abnormality detection signal outputteo by the abnormality monitoring unit lL2. t 0033 l The rolling control apparatus 100 as shown in Fig. 1 is achieved by combination of software and hardware. Here, the hardware that configures the respective function blocks of the rolling control apparatus 100 will- be described referring to Fig. 2. Fig. 2 ts a block diagram showing a hardware confj-guration for achieving the respective function blocks of the rolling control 74 .l'1 rl HH-1037-rN (PCT) apparatus 100 accordlng to the present ernbodiment. As shown in Fig. 2, the rolling control apparatus 100 accordlng to the present embodi-ment has a confi-guration simil-ar to those of generalized servers and information processing terminal-s such as a PC (Personal Computer) and the like. [ 0034 ] That is, in the rolling control apparatus 100 according to the present embodiment, a CPU (Central Processing Unit) 207, a RAM (Random Access Memory) 202, a ROM (Read Only Memory) 203, a HDD (Hard Disk Drive) 204 and an I/E 205 are connected to each other through a bus 208. AIso, to the I/F 205, an LCD (Liquid Crystal DispJ-ay) 206 and an operation unit 207 are connected. t003sl The CPU 201 is a calculating means and controls the motion of the entire rolling control- apparatus 100. The RAI{ 202 is a volatile storage medium capable of reading and writing information at a high speed, and is used as a working region when the CPU 201 processes information. The ROM 203 is a read only non-volatile storage medium, and programs such as firmware are stored there. t00361 The HDD 204 is a non-volatil-e storage medi:r:. capable of reading and writing lnformation, and an OS (Operating System), various control- programs, applications/programs and the like are stored there. The I/E 205 connects and controls the bus 208 and the various hardware, networks and the like. Further, the I/E 205 functions also as an input/output unit allowing the rolling control apparatus 100 to exchange information wi-th the rolling 15 I Il^Jl, lt.l .- L. I HH-1037-IN (PCT) mill 10. [0037 ] The LCD 206 ts a visual user interface for allowing an operator to confirm the state of the rolling control- apparatus 100. The operatlon unit 207 is a user interface such as a keyboard, a mouse and the like for al-lowing an operator to lnput information to the roll-ing control apparatus 100. In such hardware confi-guration, the programs stored in the recording media such as the ROM 203, the HDD 204, or an optical disk not illustrated and the l-ike are read by the RAM 202, the CPU 201 executes calculation according to the program, and thereby a software control unit is configured. By combination of the software control unit and the hardware configured thus, the function of the rolling control apparatus 100 according to the present embodiment is achieved. t 0038 l In such the roll-ing control apparatus 100, the points according to the present embodiment are presetting of the rolling condj-tion by the setup calculatj-on unit 105, determination of the preset sheet thickness by the draft change specification calculation unit 108 and the preset sheet thickness change unit 109, and learning of the rolling model by calculation of the friction coefficient p and the deformation resistance k in the rolling operation under the rolling condition determi-ned thus. Below, motions according to the points of the present embodiment will be described. t003el As described above, in the rolling mill according to the \6 I l,rl iL1 -- tl J-..arLJllllll,lll.l l, l HH_1037_IN (PCT) present embodiment, rolling control is executed for each coi-I. A1so, the setup calculation unit 105 according to the present embodiment determines whether a normal rolling operation is to be executed, or a learni-ng rolling in which a rolling model is l-earnt is to be executed. Fig. 3 is a flow chart showing a determination motion of an operation mode by the setup calculation unit 105. t00401 As shown rn F:-g. 2, when the determinatj-on motion operation mode is started, the setup calcul-ation unit determines whether the material kind of the coil to be next is equal or not to the material kind of the coil rolled material- being rolled at present (S301). A1so, material kind of the coil- to be roll-ed is inputted to control- apparatus 100 by manual work of the operator. [ 0041 ] of 105 the roll-ed of the the the rolling As a result of 5301, when the material kind of the coil to be rolled next is equal to the material kind of the coil of the rol-Ied material being ro1led at present (S301/NO), the setup calculation unit 105 confirms whether execution of the rolling operation next under an every coil learning mode has been preset or not (5302). When determination of 5302 results not to be the every coil learning mode (5302lNO;, the setup calculation unit 105 determines to be under a mode of normal rolling (5304), and the process is completed. 10042) On the other hand, as a result of determi-nation of 5301, when the material kind of of the coil to be rolled next is i'7 . t, I I HH-1037-rN (PCT) different from the material kind of the coil- of the roll-ed material- being roll-ed at present (S301/YES), or as a result of determination of 5302, when execution of the rol-ling operatj-on under the every coil learning mode has been preset (S302/YES;, the setup calculation unit 105 determines to be under the mode of learning rolling (5303), and the process is completed. t0 04 31 Here, in Fig. 4, a timing chart showing "Iine speed", "mode determj-nation timlng", "preset sheet thickness change timing", "preset sheet thickness change amount", "integrator reset timing", "parameter calculation timing", and "rolling l-oad model cal-cul-atj-on tJ-ming" in the learning rolling mode is shown. t0044 l The "line speed" shown in Fig. 4 is calculated by the speed change amount calculation unit 106 based on the roll-ing condition determined by the setup calculatj-on unj-t 105, and is controlled by the speed change unlt 101. As shown in Fig. 4, the "line speed" that is the transporting speed of the rolled material is decelerated regularly. This is the cut speed for cutting the roll-ed material- whose rolling has finished in a case where rolling is executed continuously by welding and connecting different coils to each other as described above, and is the minimum speed that is the l-owest speed in the l-ine speed control of the rolling mill 10 according to the present embodiment. t004sl A1so, as shown in Fig. 4, the line speed according to the present embodiment changes in respective periods of an accel-eration period accelerating from the cut speed, a stationary 18 I -t HH-1037-rN (PCT) period thereafter, and a deceleratj-on period decelerating from the speed of the stati-onary period to the cut speed. Out of them, the stationary speed in the stationary period 1s the rolling speed that is the transporting speed of the rol-l-ed material in ordinary rolling operation, and the stationary period is the ordinary perlod. t00461 Further, the "l-j-ne speedrr shown in Fig. 4 corresponds to the roll- speed of any one of the roll- stands 1 included by four units as shown in Fig. 1. Here, to cope with the length of the rolled material- of the portion extended by rolling, with respect to the p1ura1 roll stands 1 incl-uded in the tandem rol-Iing mill, the ro11 speed is set to be faster for those arranged in the rear stage. Therefore, control of accelerating, stationary and decelerating l-ine speed as shown in Fig. 4 is executed corresponding to such difference of the roII speed for respective ro11 stands as described above. t00471 The "mode determination timing" is timing when the motion described in Fig. 3 is executed, and is the timing before deceleration for the cut speed descrj-bed above is started. AIso, the mode determination timing in the present embodiment is determined by the setup calcul-ation unit 105 according to the change control of the line speed by the speed change unit 107. t004Bl The "preset sheet thickness change timing" is a signal showing timing when the roll, gap control unj-t 111 changes the direction for changing the preset sheet thickness for calculating ---3JlJ.!l I tt L9 --Jut t.,t l- I r I HH-1037-rN (PCT) Ah used in the feedback control, and is controlled by the draft change specification calculation unit 108. As shown in Fig. 4, the draft change specification cal-culation unit 108 shows the preset sheet thickness change timing by signals showing the timing for changing. to the positive direction from the reference val-ue and the timing for changing to the negative direction. [004e] This preset sheet thickness change timing is obtained by dividing the respective periods of the deceleration period, the acceleratlon period and the stationary period of the l-ine speed by four as shown in Fig. 4. More specifically, four periods of a first period for changing to the positive direction so as to be the maximum preset sheet thickness from the original preset sheet thickness, a second period for changing to the negative direction so as to be the original preset sheet thickness from the maxj-mum preset sheet thickness, a third period for changing to the negative directlon so as to be the minimum preset sheet thickness from the original preset sheet thickness, and a fourth period for changing to the positive direction so as to be the original creset sheet thickness from the minimum preset sheet thickness are obtained by dividing each of the deceleration period, the acceleration period and the stationary period by four. t 00s0 l In other words, the draft change specification cal-culation unit 108 according to the present embodiment presets four periods of the first period of thickening the preset sheet thickness from the standard preset sheet thickness, the second period of returning from the preset sheet thickness thi-cker than the 20 l" HH-1037-rN (PCT) standard one to the s-uandard preset sheet thickness, the third period for thlnning the preset sheet thickness from the standard preset sheet thickness, and the fourth period of returning from the preset sheet thickness thinner than the standard one to the standard preset sheet thickness j-n each of the accel-eration period, the deceleration period and the ordinary period. t 00s1 l The "preset sheet thickness change amount" j-s a signal showing a change amount of the preset sheet thickness according to the "preset sheet thickness change timing" described above and is controlled by the preset sheet thickness change unlt 109. The preset sheet thickness change unit 109 shows the preset sheet thickness change amount by a slgnal showing the change amount in the positive direction and the change amount in the negative directlon from the original- preset sheet thickness as shown in Fig. 4. The preset sheet thickness change unit 109 acquires the "preset sheet thickness change timing" and the change rate of the draft from the draft change specification calculation unit 108, and calculates the "preset sheet thickness change amount". t 00s2 l Further, althougi iour roll stands 1 are included in the rolling mill 10 as ciescribed above, the "preset sheet thickness change amount" shown i-n Fig. 4 is applied to the roll- gap control for each rol-1 stand 1 at same timing according to the "preset sheet thickness change timing" preset based on the change of the line speed as shown i-n Fig. 4 . t0 0 s3l The "integrator reset timing" is a reset signal showing 2! LI l..Lr ll-l--.---. I I HH-1037-rN (PCr) timing at which the integrator reset unii 110 resets the i-ntegration perj-od by the rol-l gap control uni-t \7-7, and is controll-ed by the integrator reset unit 110. The integrator reset unit 110 refers to the "preset sheet thickness change amountrr inputted by the preset sheet thickness change unj-t 7O9, and outputs a reset si-gnal at timing at which the change rate of the "preset sheet thickness change amount" changes, that is timing at which the "preset sheet thickness change amount" changes to a crank shape. t 00s4 l The "parameter calculation timing" is a signal showing the period when the friction coefficient cal-culation unit 702 and the deformation resistance calcul-ati-on unit 103 calculate the friction coefflcient lr and the deformation resistance k, and is controlled by each of the friction coefficient calculation unit 702 and the deformation resistance calcul ation unit 103. As shown in Fig. 4, the "parameter calculation timing" according to the present embodiment is preset with the acceleration period, the stationary period and the deceleration period being made one vJ vlu . t 00ss l The "ro1ling load model- calculation --iming" is a signal showing the timing at which the rol-ling' Ioad cal-culation unit 104 cal-culates the rolling model- based on the parameters cal-culated by the friction coefficient calcul-ation unit L02 and the deformation resistance calculatj-on unit 103, and is controll-ed by the rolling load calculation unit L04. t0 0s 6l 22 ill' I l,l HH-1037-TN (PCT) To acquire the information of he to ha, P1 to Pq, RVi tc F,Va under vari-ous rolling conditions by executing rolling operation whil-e changlng the preset sheet thj-ckness according to each of the acceleratlon peri-od, the stationary period and the decel-eration period of the line speed and to cal-culate the parameters as shown in Fig. 4 are the points according to the present embodiment. AIso, in the present embodiment, Iearnj-ng when the product is produced, that is, during actual rolling operation, is made the premise. Therefore, rolling is executed so that the exit side sheet thickness of the fourth roll stand 1 that is the rearmost stage becomes the target sheet thickness. Accordj-ngly, the "preset sheet thickness change amount" shown in Fig. 4 is not applied to the fourth roII stand 1, and the ordinary preset sheet thickness is applied to the fourth ro11 stand 1. | 00s7 l However, the entry side sheet thlckness of the fourth ro11 stand 1 is in a state roll,ed according to the "preset sheet, thickness change amount" of Fig. 4 by the third roll stand i. In order to cope with such sheet thickness change, the j-ntegirator reset unit 110 outputs a reset signal at predetermined ti-rc'i-ng:or the feedback control- for the fourth roll- stand 1 also. The predetermined timing is timing when a portion where the sheet thickness of the rolled material- changes to a crank shape by being rolled accordj-ng to the "preset sheet thickness change amount" of Fig. 4 by the third roII stand 1 arrives at the fourth rol} stand 1. 100581 23 ----lr4]-L, I HH-1037-rN (PCT) Here, the period after a certain portion is rolled by the third ro11 stand until- arriving at the fourth roll- stand can be obtained by calcul-ation. Therefore, the integrator reset unit 110 outputs an integration reset signal for the feedback control for the third rol-l- stand 1, and thereafter outputs a reset signal for the feedback control for the fourth rol-I stand 1 delaying by the period obtained by the cal-culation described above. t00s9l Calculation of the "preset sheet thickness change timing" and the "preset sheet thickness change amount" shown in Fig. 4 is one of the points according to the present embodiment. Referring to Fig. 5 (a) to (c), the calculation form of the "preset sheet thj-ckness change timing" and the "preset sheet thickness change amount" will be described. Fig. 5 (a) to (c) are functi-on bl-ock diagrams showj-ng calcul-ation forms of the "preset sheet thickness change timing" and the "preset sheet thickness change amount" by the setup calculation unit 105 and the draft change specification calculation unit 108. [0060] Fiq. 5 (a) is a drawing showing a calculation form of the "preset sheet thickness change timing" and the "preset sheet thickness change amount" in the acceleration period of the line speed. As shown in Fig. 5 (a), the accel-eration rate, the maximum rolling speed and the maximum draft change amount are inputted from the setup calcul-ation unlt 105 to the draft change specification calculation unit 108. AIso, to the draft change specification calculation unit 108, the measured val-ues RV1 to RV4 of the l-ine speed are inputted as the present line speed from the 24 .l '- I r l HH-1037-rN (PCT) rolling state monitoring unit 101 as shown in pig. 1. [0051] A]so, as described J-n Fig. 4, the calculation timing for the rolling l-oad moder in the present embodiment is the period when the line speed drops to the cut speed. Therefore, the measured values RV1 to RVq of the line speed inputted to the draft change specification calculation unit 108 as the present tine speed from the rolling state monitoring unit 101 are the cut speed. t00621 fn the draft change specification calculation unit 108, the time required for accel-eration of the line speed, which is the accereration period described in Fig. 4, is cal-culated based on the present rine speed, the acceleratlon rate and the maximum rorling speed out of the inputted information described above, the time is divided by four as described in Fig. 4, and thereby the "preset sheet thickness change timing" is calculated. That is, the acceleration rate and the maximum rolling speed shown in Fig. 5 (a) are the information for presetting the time-sequential change of the transportation speed of the roll-ed material, and the setup calculation unit 105 functions as a transportation speed presetting unit. t00631 Also, the draft change specification cal_culation unj_t 108 cal-cul-ates the "preset sheet thickness change amount" based on the maximum draft change amount inputted by the setup calcul-ation unit 105, the predetermined draft change rate and the "preset sheet thickness change timing" carcurated. That is, the draft change speciflcation calculation unit 108 functions as a preset 25 i ..-; .'1 -. . a, ,/ , r/ rll 1-r_l rr l, r ,1.".t HH-1037-rN (PCT) sheet thickness change presetting unit that presets the timesequenti- a1 change of the preset sheet thickness. t00641 Here, the predetermined draft change rate will be described referrj-ng to Eig. 6. As described above, in the first-third roll stands 7, by executing such learning rolling as shown in Fig. 4, that is rolling while the preset sheet thickness is changed, the rolled materi-al whose sheet thickness changes j_n a crank shape according to the position 1n the transporting direction comes to be fed to the fourth roll- stand 1. However, since the premise of the l-earning rolling according'to the present embodiment is to enable the learning rolling even in producing, it is necessary to achieve the product sheet thickness in the fourth roll stand 1. t006sl Fig. 6 is a drawing showing an example of the change of the entry side sheet thickness and the exit side sheet thickness when such the feedback control as the expression (2) above is executed. As shown in Flg. 6, when the entry side sheet thickness changes in a crank shape, in the exit side sheet thickness, the deviation g according to the change rate of the entry side sheet thickness occurs at the change point of the crank shape. This occurs inevitably as far as control by such integral calculation as the expression (2) is executed. t 00661 When the devlation g shown in Fig'. 6 is in a level exceeding the allowable range of the product sheet thickness, off-gage occurs, and the specification as the product does not come to be satisfied. Therefore, with respect to the change rate of the 26 l1,l HH-1031-rN (PCT) entry sj-cie sheet thickness, the deviation g is required not to exceed the allowab.l-e range as the product sheet thickness. Accordingly, the draft change rate preset in the draft change specification cal-cul-ation unit 108 i-s such the change rate of the exit side sheet thickness of the third rolt stand 1 that the offgage does not occur in the exit side sheet thickness of the fourth roll stand 1. i00671 AIso, the maximum draft change amount inputted from the setup cafculation unit 105 is a threshold preset by the setup cal-culation unlt 105 in order to avoid occurrence of a s1ip. rn rolJ-ing in respective rol-l stands L, the stlp occurs between the work rolls and the rolled material_, and the product quality is seriously affected even when the draft is excessively high or excessj-vely }ow. fn order to avoid such situation, the setup calculation unit 105 presets a threshold in the change amount of the draft as the maxi-mum draft change amount, and prevents occurrence of the slip. t0 0 681 Fig. 7 is a drawi-ng showing a form of obtaining the "preset sheet th- c