ROLLING CONTROL DEVICE, ROLLING CONTROL METHOD, AND COMPUTER READABLE MEDIUM STORING ROLLING CONTROL PROGRAM
BACKGROUND
1. Field of the Invention
The present invention relates to a rolling control device, a rolling control method, and a computer readable medium storing a rolling control program.
2. Description of the Related Art
In tandem rolling mills, thickness control linking directly to the product quality of rolled material and tension control indispensable to the stability of operation are important. Particularly as for the thickness control, detectors, such as thickness gauge for detecting a thickness deviation or strip speed meters for detecting the speed of rolled material, are installed so as to perfonif ^.higir^accaTacy control.
However, those detectors are costly, and the number of detectors is preferably reduced as much as possible in order to reduce equipment investment costs. Furthermore, if the number of detectors increases, maintenance work required for the increased number of detectors increases. In view of this, preferably, the number of detectors is minimized.
On the other hand, the mass flow constant law, which is the basic formula of rolling control, is built on the premise that the volume of the rolled material entering a rolling mill is equal to the volume of.,:,;.the:.a>r©liled material exiting therefrom, which can be expressed by the^ following formula (1) using entry thickness H, entry strip speed Ve, exit thickness h, and exit strip speed Vo of a roll stand.
H • Ve = h • Vo (1)
This relationship is established in each stand of a tandem

rolling mill, and also established when a plura-lity of roll stands are regarded as a single roll stand. For example, when there are four stands #1 to #4, such relationship is also established between the volume of the rolled material entering the #1 stand and the volume of the rolled material exiting from the #4 dtand (for example, see Japanese Published Unexamined Patent Application No. Hei 11-33612) .
As disclosed in"the Japanese Published Unexamined Patent Application No. Hei 11-33612, when control is performed according to the mass flow constant law with a plurality of roll stands regarded as a single roll stand, intermediate sensors can be omitted, thereby allowing a reduction in the number of detectors as described above.
However, even if a plurality of roll Stands are collectively regarded as a single roll stand, the plurality of |:oll stands are actually incltidfed and -therefore, control is required accordingly.
For example, when control based on the mass flow constant law is performed for a single roll stand, the control is applicable without particular regard to timing on the exit and entry sides. On the other hand, when a plurality of roll stands are collectively regarded as a single roll stand, it is necessary to take into account the influences on the other roll stands dufe to a change in the control state of one roll stand, resulting in complicated control.
SUMMARY
Accordingly, the present invention has been made in order to address the above-described program, and an object of the present invention is to provide excellent control in the case of performing rolling control on the basis of the states of a rolled material on the entry and exit sides of the whole of a plurality of roll

stands.
• According to an aspect of the present invention, there is provided a rolling cpntrol device which controls a tandem rolling mill that rolls a rolled material with a plurality of roll pairs, wherein detection results of the state of the rolled material entering the most upstream roll pair disposed on the most upstream side and the state of the rolled material exiting from the most downstream roll pair disposed on the most downstream side of the plurality of roll pairs arranged in succession with respect to the rolled material are obtained, and on the basis of the obtained two detection results, the 'roll speed of the roll pair other than the most upstream roll pair of the plurality of successively-arranged roll pairs is controlled so that the entry rate of the rolled material into the most upstream roll pair is coincident with the exit rate of the rolled material from the most downstream roll pair.
With the-pre'sent" invention, it is possible to provide excellent control in the case of performing rolling control on the basis of the states of a rolled material on the entry and exit sides of the whole of a plurality of roll stands.
BRIEF DESCRIPTION OF THE DRAWINGS
Non-limiting and non-exhaustive embodiments of the present embodiments are described with reference to the following figures, wherein like reference signs refer to like parts throughout the various views unless otherwise specified.
FIG. 1 =.iShQWS,.,,,tsiie.t.overall configuration of a tandem rolling mill according to an embodiment of the present invention,
FIG. 2 shows a rolling phenomenon of the tandem rolling mill.
FIG. 3 shows successive control of a tandem rolling mill according to the related art.
FIG. 4 shows a speed setting method of the tandem rolling

mill according to the related art.
FIG. 5 shows successive control of the tandem rolling mill according to the embodiment of the present invention;
FIG. 6A and 6B show the load balance of the tandem rolling
mill. . ■ ' '
FIG. 7 shows the configuration of an entry rate calculating device according to the embodiment of the present invention.
FIG. 8 shows the configuration of an exit rate calculating device according to the embodiment of the present invention.
FIG. 9 shows the outline of operation of an exit thickness control device according to the embodiment of the present invention.
FIG. 10 is the overall configuration of a tandem rolling mill according to a comparative example of the present invention.
FIG.. 11 shows the configuration of an information processing device according to the embodiment of the present invention.
DETAILED DESCRIPTION
In this embodiment, an aspect in which, in a tandem rolling mill, a plurality of roll stands are assumed as a single roll stand ■ and mass flow control is performed based on the states of a rolled material on the entry and exit sides of the whole plurality of rolling mills assumed as a single rolling mill will be described. Thus, since detectors are only provided on the entry and exit sides of the whole plurality of rolling mills assumed as a single rolling mill and intermediate detectors can be omitted, a minimum detector configuration-'Gan fee achieved.
Further, in the rolling mill according to this embodiment, a :roll stand disposed on the most upstream side of the plurality of rolling mills assumed as a single rolling mill is defined as a master stand, and control for eliminating the deviation caused by an upstream rolling stand is applied to a downstream roll stand.

This ,is one of th6 main points of. this .embodiment.
Here, upstream refers to the side of the tandem rolling mill on which the rolled material is supplied, and downstream refers to the side of the tandem rolling mill on which the rolled material is., discharged as a product. Furthermore, the term detector refers to a
device capable of detecting the entry rate (thickness x strip speed) of the rolled material into a roll stand and a device capable of detecting strip speed, such as a thickness meter and strip speed meter or a roll with a pulse oscillator.
In this embodiment, description will be made using, as an example, a four-stand tandem rolling mill configured from four roll stands 11 to 14 as shown in FIG. 1. As shown in FIG. 1, roll gap control devices 31 to 34 for operating roll gap and roll speed control devices ,21 to 24 for operating roll speed are installed in the roll stands 11 to 14, respectively.
Furthermore, 'the-roiling mill according to this embodiment allows proper rolling control with a minimum necessary sensor configuration. As shown in FIG. 1, in the rolling mill according to this embodiment, the #l'roll stand 11 is provided with a #l-stand exit thickness meter 41 and a #l-roll-stand exit strip speed meter 81.
Also, the #4 roll stand 14 is provided with a #4-stand exit thickness meter 44 and a #4-roll-stand exit strip speed meter 84. Further, inter-stand tension meters 51 to 53 are provided between the adjacent stands.
,. important■■i.i£Q,£.»£Qlling mills are the thickness of rolled material, which links directly to the product quality, and the tension, which is required for the stability of rolling operation. In the rolling mill according to this embodiment, a #l-stand exit AGC 61 operates the #1 roll gap control device 31 according to a detection result of the #l-stand exit thickness meter 41.

• On the other hand; ^a #4-stand exit AGC 64 operates the-#4-stand roll speed control device 24 according to a detection result of the #4-stand exit thickness meter 44. It should be noted that the #4-stand roll speed control device 24 according to this embodiment is controlled by multiplication by various control inputs, in addition to the operation by the #4-stand exit AGC 64.
As for tension control, a #l-#2 inter-stand tension control 71 detects the tension between the #1 roll stand 11 and the #2 roll stand 12 with the #l-stand exit tension meter 51 and operates the #2-roll-stand roll gap control device 32.
Furthermore, a #2-#3 inter-stand tension control 72 detects the tension between the #2 roll stand.12 and the #3 roll stand 13 with the #2-stand exit tension meter 52 and operates the #3-roll-stand roll gap control device 33.
Moreover, a #3-#4 inter-stand tension contrO|l 73 detects the tension between the #3 roll stand 13 and the #4 roll stand 14 with the #3-stand exit tension meter 53 and operates the #4-roll-stand roll gap control device 34.
Further, in the rolling mill according to this embodiment, on the basis of detection results of the #l-roll-stand exit strip speed meter 81 and the #4-roll-stand exit strip speed meter 84, the control based on the mass flow constant law is performed on the assumption that the #2 roll stand 12, the #3 roll stand 13, and the #4 roll stand 14 are a single rolling mill. Therefore, the #2 roll stand 12 is used a_s the most upstream roll pair and the #4 roll •Agt'Bind. 14 is-«&ed-a'S the most downstream roll pair. Such control is implemented by the functions of an entry rate calculating device 101 and an exit rate calculating device 102.
Thickness gauge and strip speed meters are costly, and equipment investment costs amount to an enormous sum. Also, those meters need frequent maintenance work for maintaining the accuracy

.of measurement, and therefore, a minimum detector configuration is preferable. In the example of FIG. 1 according to this embodiment, since the plurality of roll stands are assumed as a single roll stand as described above, it is enough to provide the thickness meter and strip speed meter only on entry and exit sides thereof. Thus, the above-described minimum detector configuration can be achieved.
FIG. 2 shows a rolling phenomenon of the #2 roll stand 12 to the #4 roll stand 14 in the tandem rolling mill. When #2-stand entry thickness represents H2; #2-stand entry strip speed, Ve2; #4-stand exit thickness, H4; and #4-stand exit strip speed, Vo4, the following formula (2) is established based on the mass flow constant law.
H2 -^Vez = h4 • Vo4 (2)
In this case, the above formula (2) is the relational expression- wherfa- portion of the rolled material having entered the #2 roll stand 12'at some point moves from the #2 roll stand 12 to the #4 roll stand 14 to exit from the #4 roll stand 14.
On the other hand, in rolling control, the roll speed of the roll stands accelerate or decelerate according to the control. Therefore, if roll speed is changed, the #4-roll-stand roll speed when the rolled material enters the #2 roll stand 12 is different from the #4-roll-stand roll speed when the foiled material having entered the #2 roll stand 12 exits from the #4 roll stand 14.
As a result, the above formula (2) is not applicable to sensor .outp.ut<.'.©f ea-ch part as it is. If the entry thickness H2 and entry strip speed Ve2 of the #2 roll stand 12 have a deviation from their setting values, when, with H2, Ve2, and V04 of the above formula (2) as setting values, the entry thickness deviation represents AH2 and the entry strip speed deviation represents AVe2, the relation with exit strip speed adjustment value AV04 that is to

be "adjusted for maintaining target thickness h4 is expressed- by the following formula (3) based on the above formula (2).
(H2 + AH2) • (Ve2 + AVe2) = h^ • (Vo4 + AVo4) (3)
Furthermore, when the above formula (3) is developed, the following formula (4) is obtained.
H2 • Ve2 + AH2 • Ve2 + H2 • AVe2 + AH2 • AVe2
= h4 • Vo4 + h4 • AVo4 (4)
Further, when the above formula (4) is rearranged using the relation of the above formula (2), the following formula (5) is obtained.
(5) In the above formula (5) , the strip speed is, shown by a ratio to the setting "Speed, and therefore the formula (5) can be used even while the tandem rolling mill is accelerating and decelerating.
Out of the parameters of the above formula (5), AH2 and AVe2 can be detected by the #l-stand exit thickness meter 41 and the #1-
roll-stand exit strip speed meter 81. Furthermore, AV04 can be detected by the #4-roll-stand exit strip speed meter 84. Therefore, when the roll speed of the #4 roll stand 14 or the #2 roll stand 12 is operated so that the above formula (5) is established, the exit thickness h4 can be made constant.
Here, the left-hand side of the above formula (3) is the entry rate o-f'"a'»"^-Gl-led material into the #2 roll stand 12 at some point, and the right-hand side is the entry rate into the #4 roll :stand 14 at the point in time when it was transferred to the #4 roll stand 14. Therefore, there is a time lag between the left-hand side and the right-hand side of the above formula (3), and that timing must be considered in the case of controlling the roll speed

of the #4 roll stand 14 on the basis of the calculation of the above formula (5).
Here, V^i is expressed by the following formula (6) in consideration of backward movement ratio b2.
Ve2 = VR2 • (1 + b2) (6)
Furthermore, Vo4 is expressed by the following formula (7) in consideration of forward movement ratio f^.
Ve4 = VR4 • (1 + f4) (7)
It is difficult to predict the exit strip speed Vo4 of the #4 roll stand 14 because it also changes according to the rolling phenomenon. Therefore, it is appropriate to set the #4-roll-stand exit strip speed Vo4 as a control element for thickness control.
FIG. 3 shows an aspect of the roll speed setting of roll stands in a common tandem rolling mill. As shown in FIG. 3, the roll speed of each roll stand is determined by the product of a master roll speed" i-nstruction MRH and a stand roll speed instruction SSRHi
Acceleration or deceleration is performed by raising or lowering the speed of the whole tandem rolling mill using the MRH. The speed balance among the roll stands is determined by the SSRH, and determined from the entry and exit thickness of each stand according to the mass flow constant law.
In tandem rolling mills, successive control is performed so as to prevent a change in the roll speed of one roll stand from affecting the other roll stands. FIG. 4 shows successive control in a common tandeffi...A.r,Qllixj.g mill.
As shown in FIG. 4, the thickness control using a detection value of a #4-stand exit thickness meter is performed in such a manner that the roll speed of a #4 roll stand serving as the final stand in the tandem rolling mill does not fluctuate. Therefore, although the roll speed of a #3 roll stand is adjusted, in order to

prevent a change in- the rolling state -of a further previous roll stand due to such adjustment, the roll speed of the further previous roll stand is also adjusted. This control is the successive control.
Furthermore, the stand in which roll speed fluctuation is to be prevented at the time of outputting the thickness control is referred to as the master stand. In this case, the master stand corresponds to the #4 roll stand 14. The wording "roll speed fluctuation is to be prevented" implies prevention of the roll speed fluctuation when control output is issued, and of course, when the tandem rolling mill is accelerated/decelerated, the roll speed of the #4. roll stand 14 also fluctuates.
If the master stand is the #4 roll stand 14 in the same manner as the related art, when the thickness control operates the roll speed of the #3 roll stand 13, the roll speed,of the #2 roll stand 12 and 'the #l""roll stand 11 are also operated under the successive control. Therefore, the above-described entry strip speed deviation AVe2 of the #2 roll stand 12 also fluctuates.
On the other hand, when the control according to the above formula (5) is performed with the #4 roll stand 14 as the master stand, the control element is the entry strip speed Ve2 of the #2 roll stand 12. Here, there is a time lag in rolling phenomenon between the #4 roll stand 14 and the #2 roll stand 12, and the #4 roll stand 14 is later one in time series.
Therefore, the detected rolling state in the #4 roll stand 14 cannot be-'di-r-est-iy used for the rolling control at the same point of the rolled material in the #2 roll stand 12. Furthermore, at the time of controlling the #2 roll stand 12, it is also necessary to consider the fluctuation in the entry strip speed
deviation AVe2 of the #2 roll stand 12 which is caused by the successive control as described above, leading to complicated
10

control.
■ Further, an influence corresponding to the above formula (3) is exerted on the fluctuation in the entry strip speed deviation
AVe2 of the #2 roll stand 12 which is caused by the successive control. Therefore, the influence must be corrected at timing when the rolled material reaches the #4 roll stand 14.
While AVe2 varies according to the #2-stand backward movement ratio b2, which is a rolling phenomenon, in addition to the roll speed of the #2 roll stand 12 as expressed by the above formula (6), what can be eliminated as a, disturbance must be eliminated as much as possible.
Such problem is addressed by setting the #2 roll stand 12 as the master stand in the rolling control according to this embodiment. In this case, as shown in FIG. 1, the output destination of the exit-side thickness control 74 of the #4 roll stand 14 is set ■'fco=trh€''#4-'roll stand 14.
FIG. 5 shoWs a successive control method with the #2 roll stand 12 as the master stand. The roll speed of the #3 roll stand 13 and the #4 roll stand 14 is corrected so that the roll speed of the #2 roll stand 12 does not change.
Referring again to FIG. 1, a method for controlling the tandem rolling mill according to this embodiment will be described. The entry rate calculating device 101 calculates the amount of correction in the #4 roll stand 14 using the above formula (5).
The exit rate calculating device 102 performs processing for transferring ..tiie,JS'.oli®d.-»material at the time of the entry rate calculation in the #2 roll stand 12 to the #4 roll stand 14 and outputs control output to the #4 roll stand 14. Here, the transfer processing is processing such that, when the state of the rolled material is detected at some point, a delay period until the rolled material in the detection position reaches the position to perform
11

■ the control corresponding to the detection result is provided. In
the case of the exit rate calculating device 102, there is provided
a delay period until a portion of the rolled material rolled in the
#2 roll stand 12 reaches the #3 roll stand 13 or the #4 roll stand
14. , ' ■ ■'
FIG. 6A shows the rolling load of each roll stand set in accordance with a predetermined exit thickness for each roll stand. Therefore, the rolling load is in a normal condition when it is almost coincident with the setting value as shown in FIG. 6A.
Here, when only the roll speed of the #4 roll stand 14 is operated by the exit rate calculating device 102, unfortunately, a situation occurs as shown in FIG. '6B, in which the rolling load of the.#4 roll stand 14 deviates from the setting value, and the rolling load of the #3 roll stand 13 also changes accordingly.
It is therefore necessary to operate not only the #4 roll stand 14, but •als5""the #3 roll stand 13 while monitoring the distribution of the rolling load among the stands. With consideration to this, the exit rate calculating device 102 determines control output to the #3 roll stand 13 and the #4 roll stand 14.
The outline of the operation of the entry rate calculating
device 101 is shown in FIG. 7. As shown in FIG. 7, a transfer
processing unit 110 transfers a detection signal of the #l-stand
exit thickness meter 41 from the thickness meter position to the #2
roll stand position to set the #2-roll-stand entry thickness
'deviation'•AH2.' ■-■■'^'■^'
Furthermore, a strip speed ratio calculating unit 111 : determines AVe2/Ve2 from a detection signal of the #l-roll-stand exit strip speed meter 81, and also determines the strip speed ratio AV04/V04 on the exit side of the #4 roll stand 14 using the above formula (5) . This strip speed ratio AV04/V04 is used as an index
12

value for Gontrolling the roll speed of the downstream roll pair • ■ according to the mass flow constant law.
The outline of the operation of the exit rate calculating device 102 is shown in FIG. 8. As shown in FIG. 8, a transfer processing unit 121 transfers the strip speed ratio AV04/V04 calculated in the entry rate calculating device 101 to the #3 roll stand 13 to determine a strip speed ratio (AV04/V04) #3 directly under the #3 roll stand 13.
Furthermore, a transfer processing unit 122 further transfers the strip speed ratio (AV04/V04) #3 to determine a strip speed ratio (AV04/V04) #4 directly under the #4 roll stand 14.
Then the exit rate calculating device 102 multiplies the
above-described strip speed ratio (AV04/V04) #3 by a control gain G3 to output control output (1 + AVR3/VR3) CNT to the #3 roll stand 13.
Furthermore, as for the #4 roll stand 14, the above-described strip "speed ratrio'tAVof/Vo^y if4 is multiplied by a control gain G4, and, a speed insttuction calculating unit 123 determines a roll
speed manipulated variable AVR4 of the #4 roll stand 14 according to the following formula (7) using a measurement result VO4FB of the #4-roll-stand exit strip speed meter 84.
• It should...i3eivEbQ4ii©di.that.. the control gain G4 is (1 - G3) . In
the first place,, the strip speed ratio AV04/V04 is the value determined according to the mass flow constant law on the assumption that the #2 to #4 roll stands 12 to 14 are a single roll stand. Therefore, basically, it is enough to apply the control value only on the #4 roll stand 14.
13

On the other hand, in the rolling mill control■according to this embodiment, the control value is distributed between the #3 roll stand 13 and the #4 roll stand 14 by the gains G3 and G4. Thus, a deviation in rolling load can be prevented in each roll stand. That is, in this embodiment, the #2 roll stand 12 is set as the master stand, and the roll speed control based on the mass flow constant law is performed for the roll pairs other than the #2 roll stand 12 as the master stand out of the #2 to #4 roll stands 12 to 14 assumed as a single roll stand.
Then the exit rate calculating device 102 outputs control output (1 + AVR4/VR4) CNT to the #4 roll stand 14 on the basis of the roll speed manipulated variable AVR4 determined by the above formula (7).
The control output determined in this manner is multiplied by a stand roll speed instruction SSRH to be output tp each roll stand roll speed contT'ol device. It should be noted that, in this case, as for the control output to the #3 roll stand 13, successive control for a #4 roll stand roll speed instruction is performed.
Furthermore, in this case, a #4-roll-stand exit-side thickness control 74 operates as shown in FIG. 9. Thus, the influences due to errors of the transfer processing units 121 and 122 in the exit rate calculating device 102 can be eliminated. With the above-described configuration, it is possible to suppress a fluctuation in #4-roll-stand exit thickness according to the mass flow constant law of the #2 to #4 roll stands 12 to 14.
Here, -«?s.«a'«»5Somparative example according to this embodiment, a case where a control configuration shown in FIG. 10 is employed ■will be described. FIG. 10 shows the configuration in which thickness diameters are provided only on the exit side of the #1 roll stand 11 and the #4 roll stand 14 in the same manner as the example of FIG. 1 according to this embodiment, and the mass flow
14

control according to this embodiment in which -the plurality of .• stands are assumed as a single stand is not employed.
In the example of FIG. 10, the exit thickness of the #2 roll stand 12 and the #3 roll stand 13 cannot be detected. Therefore, there is a problem in that the opportunities for thickness control decrease, leading to deterioration in thickness accuracy. There is also a problem in that, because the rolling reduction of the #2 roll stand 12 and the #3 roll stand 13 is unknown, the rolling load and electromotor load are biased to a particular roll stand or the ratio between roll stands is deteriorated.
More specifically, when the rolling state of each roll stand is as originally expected, the thickness accuracy is not drastically deteriorated even if the exit thickness of the #2 roll stand 12 and the #3 roll stand 13 cannot be detected. In the same manner, the load of each roll stand is not biased.
On the other-'haTid, for example when disturbances occur in the rolling state of the #2 roll stand 12, the disturbances have influences on the #3 roll stand 13 and the #4 roll stand 14. In the example of FIG. 10, attempts to eliminate such influences are made by operating the #3 roll stand 13 using the #4-stand exit AGC 64, resulting in the occurrence of the above-described problems.
In the rolling mill according to this embodiment, the control based on the mass flow constant law is performed in a rolling state that can be detected under the condition where detectors are limited as shown in FIG. 10, that is, on the entry
side-.of. the #2.,.f£oli:.=..Sitand 12 and on the exit side of the #4 roll
stand 14. In that case, the #2 roll stand 12 on the upstream side is set as the master stand, and the controlled variable of a downstream roll stand is operated in order to maintain the exit thickness.of the #4 roll stand 14 which is the final stage.
In this aspect, for example when disturbances occur in the

rolling state- of the #2 roll stand 12, the disturbances are incorporated in the mass flow control as the entry thickness deviation AH2 or the entry strip speed deviation AVe2 to be employed as the control over the #3 roll stand 13 and the #4 roll stand 14 as described above.
In that case, since the #2 roll stand 12 on the upstream side is set as the master stand, the disturbances having occurred in the #2 roll stand 12 can be applied to the #3 roll stand 13 and the #4 roll stand 14 on a feed-forward basis by the functions of the transfer processing units 121 and 122 described in FIG. 8. Therefore, with the rolling mill control according to this embodiment, appropriate control for performing the rolling control based on the states of the rolled material on the entry and exit sides of the whole plurality of roll stands can be provided.
It should be noted that although in the abovp-described embodiment, the description is in terms of the four-stand tandem rolling mill, it is applicable to a tandem rolling mill with an optional number of stands in the same manner. Furthermore, although in the above-described embodiment, the description is in terms of the case where detectors are installed on the exit side of the #1 roll stand 11 and on the exit side of the #4 roll stand 14, it is applicable in the same manner even when detectors are installed on the exit side of other optional stands.
Furthermore, although in the above-described embodiment, the case where the strip speed meters are installed on the exit side of .-;t-ke'"#l rol'l.-®fe£»id 11 and the #4 roll stand 14 has been described,
any means can be used if the strip speed of the rolled material can ■■■''■be detected. For Example, the rolled material strip speed between stands may be determined by measuring the rotational roll speed of the roll in contact with the rolled material or alternatively, by estimating a forward movement ratio from the measurement result by

a thickness diameter. Any-other methods can -be used if the strip ■ speed of the rolled material can be obtained.
Furthermore, the entry rate calculating device 101 shown in FIG. 7 or the exit rate calculating device 102 shown in FIG. 8 are realized by the combination of software and hardware. Here, the hardware for implementing each function of an information processing device, such as the entry rate calculating device 101 or the exit rate calculating device 102 according to this embodiment, will be described with reference to FIG. 11. FIG. 11 is a block diagram showing the hardware configuration of the information processing device according to this embodiment. As shown in FIG. 11, the information processing device according to this embodiment has the same configuration as that of a general server, PC (Personal Computer) or the like.
That is, in the operation processing device according to this-'^embodiment:,''a-'G-PU . (Central Processing Unit) 201, a RAM (Random Access Memory) 202, a ROM (Read Only Memory) 203, an HDD (Hard Disk Drive) 204, and an I/F 205 are connected via a bus 208. Furthermore, an LCD (Liquid Crystal Display) 206 and an operating unit 207 are connected to the I/F 205.
The CPU 201 serves as calculating means for controlling the operation of the whole operation processing devices. The RAM 202 is a volatile storage medium capable of high-speed reading and writing of information, and used as a working area when the CPU 201 processes the information. The ROM 203 is a read-only nonvolatile storage mediumt..i^n.-'irfhich programs, such as firmware, are stored.
The HDD 204 is a nonvolatile storage medium capable of reading and writing of information, in which an OS (Operating System), various kinds of control programs, application programs, etc. are stored. The I/F 205 connects and controls the bus 208 and various kinds of hardware, networks, etc. The I/F 205 is also used

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as an interface for the information processing device to exchange• information or input information to the rolling mill.
The LCD 206 is a visual user interface for an operator to check the state of the information processing device. The operating unit 207 is a user interface, such as a keyboard or mouse, for an operator to input information into the devices. In such hardware configuration, the CPU 201 carries out an operation according to the program stored in the ROM 203 or the program read by the RAM 202 from a recording medium, such as the HDD 204 or an optical disk which is not illustrated, thereby constituting a software control unit. The functions of the entry rate calculating device 101 and the exit rate calculating device 102 according to this embodiment are realized by the combination of the software control unit configured in this manner and the hardware.
It should be noted that, although in the aboye-described embodiment, the""case where the entry rate calculating device 101 and the exit rate calculating device 102 are configured as separate devices has been described as an example, those devices may be configured as a single device having the functions of the both, or the functions may be further divided into a plurality of devices.

WHAT. IS CLAIMED IS:
1. A rolling control device which controls a tandem rolling
mill that rolls a rolled material with a plurality of roll pairs,
wherein detection results of the state of the rolled material entering the most upstream roll pair disposed on the most upstream side and the state of the rolled material exiting from the most downstream roll pair disposed on the most downstream side of the plurality of roll pairs arranged in succession with respect to the rolled material are obtained, and
on the basis of the obtained two detection results, the roll speed of the roll pair other than the most upstream roll pair of the plurality of successively-arranged roll pairs is controlled so that the entry rate of the rolled material into the most upstream roll pair is coincident with the exit rate of the rolled material from the most downstream roll pair.
2. The rolling control device according to Claim 1,
comprising:
an entry rate calculating unit that calculates an entry rate of the rolled material into the most upstream roll pair on the basis of the detection result of the state of the rolled material entering the most upstream roll pair; and
an exit rate calculating unit that outputs a control value for controlling the rolling speed of the roll pair other than the most upstream roll pair so that the thickness of the rolled material exitifig,,.,££Qm..the most downstream pair is maintained to be a set value, on the basis of the detection result of the state of the rolled material exiting from the most downstream roll pair and a value corresponding to the calculated entry rate of the rolled material entering the most upstream roll pair.
3. The rolling control device according to Claim 2, wherein

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the entry rate calculating- unit calculates an index value for • ■ controlling the roll speed of the most downstream roll pair so that the thickness of the rolled material exiting from the most downstream roll pair is maintained to be a set value, on the basis of the detection result of the state of the rolled 'material entering the most upstream roll pair, and
the exit rate calculating unit outputs a control value for controlling the roll speed of the rolled pair other than the most upstream roll pair on the basis of the index value.
4. The rolling control device according to Claim 3, wherein the exit rate calculating unit, at the time of outputting the control value, outputs the control value at timing when the detection position of the rolled material where the detection result used for the calculation of the index value as the basis for outputting the control value is detected reaches t^e roll pair to which the control value is to be output.
5. The rolling control device according to Claim 3, wherein the exit rate calculating unit outputs in a distributed manner the control value determined on the basis of the index value to a plurality of the roll pairs other than the most upstream roll pair of the plurality of successively-arranged roll pairs.
6. The rolling control device according to Claim 2, wherein the roll speed of the most downstream roll pair is controlled by a value obtained by combining the control value of the roll speed of the most downstream roll pair output by the exit rate calculating unit-with-t-he-*soH-ferol value of the roll speed of the most downstream roll pair calculated on the basis of the detection
;;-;^:'-; result of the state of the rolled material exiting from the most downstream roll pair.
7. A rolling control method for controlling a tandem rolling
mill that rolls a rolled material with a plurality of roll pairs.

the method comprising:
obtaining detection results of the state of the rolled material entering the most upstream roll pair disposed on the most upstream side and the state of the rolled material exiting from the, most downstream roll pair disposed on the most downstream side of the plurality of roll pairs arranged in succession with respect to the rolled material; and
on the basis of the obtained two detection results, controlling the roll speed of the roll pair other than the most upstream roll pair of the plurality of successively-arranged roll pairs so that the entry rate of the rolled material into the most upstream roll pair is coincident with the exit rate of the rolled material from the most downstream roll pair.
8. A computer readable medium storing a rolling control program, the rolling control program causing an information processing device "t"0" execute a process for controlling a tandem rolling mill that rolls a rolled material with a plurality of roll pairs, the process comprising the steps of:
obtaining detection results of the state of the rolled material entering the most upstream roll pair disposed on the most upstream side and the state of the rolled material exiting from the most downstream roll pair disposed on the most downstream side of the plurality of roll pairs arranged in succession with respect to the rolled material; and
on the basis of the obtained two detection results, controlling tiie.ri£Q.li...speed of the roll pair other than the most upstream roll pair of the plurality of successively-arranged roll pairs so that the entry rate of the rolled material into the most upstream roll pair is coincident with the exit rate of the rolled material from the most downstream roll pair.