1. A rolling control apparatus for controlling a tandem rolling mill which rolls a strip (1 57) by a plurality of roll pairs (16 1 : F 1 - F7), comprising: a delivery side thickness obtaining unit (1 13) for obtaining a result of a thickness measurement which is performed by a thickness meter (164) arranged on a delivery side of the roll pair (F7) arranged at a final stage of rolling order among the plurality of roll pairs; a thickness calculating unit (1 13) for calculating a thickness on an entry side of the roll pair on the basis of a thickness on the delivery side of the roll pair in accordance with such a rule that a product of a conveying speed and the thickness of the strip which is inserted into the roll pair and a product of a conveying speed and the thickness of the strip which is fed out fiom the roll pair are constant; and an error compensating unit (1 13) for compensating an error of a calculation result of the entry side thickness of each roll pair within a range fiom the roll pair (F2) arranged just after the head roll pair (Fl) in the rolling order among the plurality of roll pairs to the roll pair (F7) arranged at the final stage, wherein, the thickness calculating unit calculates the entry side thickness of the roll pair (F7) arranged at the final stage on the basis of the obtained thickness measurement result, uses a calculation result as a thickness of the strip which is fed out from the roll pair (F6) arranged just before the roll pair (F7), and repeats the calculation according to the rule, thereby calculating an entry side thickness of the roll pair 0;l) arranged at the head, I the error compensating unit calculates an error between the entry side thickness of I I the roll pair (Fl) arranged at the head which was calculated by repeating the calculation I I according to the rule and an entry side thickness of the roll pair (Fl) arranged at the head which I was obtained by a different method and compensates the error of the calculation result of the I entry side thickness of each roll pair on the basis of the calculated error.

2. The apparatus according to claim 1, wherein on the basis of a ratio of the entry side thickness of the roll pair as a correction target to the entry side thickness of the roll pair (Fl) arranged at the head which was calculated I by repeating the calculation according to the rule, the error compensating unit (1 13) determines a value which is applied to correct the calculation result of the entry side thickness of each roll pair in the calculated error.

3. The apparatus according to claim 2, wherein the error compensating unit (1 13) sets an amount according to the ratio of the entry side thickness of the roll pair as a correction target to the entry side thickness of the roll repeatini7he calculation according to the rule in an amount of the calculated error into the value which is applied to correct the calculation result of the entry side thickness of each roll pair.

4. The apparatus according to claim 1, wherein the error compensating unit (1 13) distributes the calculated error to the calculation result of the entry side thickness of each roll pair, thereby compensating the error of the calculation result of the entry side thickness of each roll pair.

5. The apparatus according to claim 1, wherein the error compensating unit (1 13) determines a correction amount of the calculation result of the entry side thickness of each roll pair based on the calculated error in accordance with a distribution of a rolling amount to the plurality of roll pairs (161: F1 - F7).

6. The apparatus according to claim 1, wherein the error compensating unit (1 13) calculates an error between a thickness of a rolling result in a rough rolling process for rolling the strip (1 57) prior to the rolling by the plurality of roll pairs (161: F1 - F7) and the entry side thickness of the roll pair (Fl) arranged at the head which was calculated by repeating the calculation according to the rule.

7. The apparatus according to claim 6, hrther comprising a rough rolling result obtaining unit (1 12) for obtaining a rolling result in the rough rolling process, and wherein the rough rolling result obtaining unit operates in such a manner that: in the rolling process just before the strip (157) is inserted into the plurality of roll pairs (161: F1 - F7), that is, in the final rough rolling process for conveying once a portion in a range from a top end to a tail end of the strip to the role pair for rough rolling which is used for the rough rolling process, start timing when the strip has been inserted to the role pair for rough rolling and the rolling has been started is obtained; in the final rough rolling process, arrival timing when the strip fed out ftom the role pair for rough rolling has reached a predetermined conveying position is obtained; by integrating a peripheral speed as a speed of a rolling surface of the role pair for rough rolling for a period of time from the start timing to the arrival timing, a predetermined interval rough rolled length serving as a length in which the role pair for rough rolling performed the rolling for a period of time during which, in the final rough rolling process, the strip is conveyed from the role pair for rough rolling to the predetermined conveying position is calculated; a forward slip ratio in the final rough rolling process is calculated on the basis of a * , "P T T R $ Pt,t i h 5 \ t i 'L ,---T#a "? 2 4 0 EC ,6924 e, - 29 - I - ratio between an interval from the position of the role pair for rough rolling to the predetermined conveying position and the predetermined interval rough rolled length; completion timing when a tail end of the strip has been rolled by the role pair for rough rolling and the rolling has been completed in the final rough rolling process is obtained; by integrating the peripheral speed as a speed of the rolling surface of the role pair for rough rolling for a period of time from the start timing to the completion timing, a whole length in which the role pair for rough rolling performed the rolling in the final rough rolling process is calculated; a whole length after the rough rolling as a whole length of the strip rolled by the rough rolling process is calculated on the basis of the calculated whole length and the forward slip ratio; and a thickness of the strip rolled by the rough rolling process is calculated on the basis of dimensions of the strip before it is subjected to the rough rolling process and the calculated whole length after the rough rolling, and wherein the error compensating unit (1 13) uses the calculated thickness of the strip rolled by the rough rolling process as a thickness of a rolling result in the rough rolling process and calculates the error.

8. The apparatus according to claim 7, wherein: the rough rolling process is a process for rolling the strip (1 57) by repetitively inserting the strip to the roll pair which is used in the rough rolling process; and the final rough rolling process is an end of the repetition of the insertion of the strip to the roll pair which is used in the rough rolling process.

9. The apparatus according to claim 1, hrther comprising a rolling force calculating unit (1 14) for calculating an estimation value of a rolling force to the roll pair on the basis of the corrected entry side thickness of the roll pair and a calculation result of the delivery side thickness, and wherein the rolling force calculating unit corrects a calculating expression of the estimation value of the rolling force by the rolling force calculating unit on the basis of a difference between the calculated estimation value of the rolling force and an actual value of the rolling force in the roll pair.

10. A rolling control method of controlling a tandem rolling mill which rolls a strip (157) by a plurality of roll pairs (161: F1 - F7), comprising the steps of obtaining a result of a thickness measurement which is performed by a thickness meter (164) arranged on a delivery side of the roll pair (F7) arranged at a final stage of rolling (d-. knx7AcaT~P' k1: b j - i ~ 2 4 OEC 2013 - . ~ 6 9 2 4 - 30 - LYf td? order among the plurality of roll pairs; calculating a thickness on an entry side of the roll pair on the basis of a thickness on the delivery side of the roll pair in accordance with such a rule that a product of a conveying speed and the thickness of the strip which is inserted into the roll pair and a product of a conveying speed and the thickness of the strip which is fed out from the roll pair are constant; and using a calculation result of the entry side thickness of the roll pair as a thickness of the strip which is fed out from the roll pair arranged just before the roll pair and repeating the calculation according to the rule, thereby calculating an entry side thickness of the roll pair (Fl) arranged at a head; calculating an error between the entry side thickness of the roll pair (Fl) arranged at the head which was calculated by repeating the calculation according to the rule and an entry side thickness of the roll pair (Fl) arranged at the head which was obtained by a different method; and compensating an error of a calculation result of the entry side thickness of each roll pair within a range from the roll pair (F2) arranged just after the head roll pair (Fl) in the rolling order among the plurality of roll pairs to the roll pair (F7) arranged at the final stage on the basis of the calculated error.

11. A rolling control program for controlling a tandem rolling mill which rolls a strip (1 57) by a plurality of roll pairs (161 : F1 - F7), wherein the program allows an information processing apparatus to execute the steps of obtaining a result of a thickness measurement which is performed by a thickness meter (164) arranged on a delivery side of the roll pair (F7) arranged at a final stage of rolling order among the plurality of roll pairs; calculating a thickness on an entry side of the roll pair on the basis of a thickness on the delivery side of the roll pair in accordance with such a rule that a product of a conveying speed and the thickness of the strip which is inserted into the roll pair and a product of a conveying speed and the thickness of the strip which is fed out from the roll pair are constant; and using a calculation result of the entry side thickness of the roll pair as a thickness of the strip which is fed out from the roll pair arranged just before the roll pair and repeating the calculation according to the rule, thereby calculating an entry side thickness of the roll pair (Fl) arranged at a head; calculating an error between the entry side thickness of the roll pair (Fl) arranged - q ~ l p @ - L 2 4 OEC 2013 ~ 6 9 2 4 &I "d j k - 31 - at the head which was calculated by repeating the calculatio side thickness of the roll pair (Fl) arranged at the head which was obtained by a different method; and compensating an error of a calculation result of the entry side thickness of each roll pair within a range from the roll pair (F2) arranged just after the head roll pair (Fl) in the rolling order among the plurality of roll pairs to the roll pair (F7) arranged at the final stage on the basis of the calculated error.

12. A rolling control apparatus, substantially as herein described with reference to accompanying drawings and examples.

13. A rolling control method, substantially as herein described with reference to accompanying drawings and examples.

14. A rolling control program, substantially as herein described with reference to accompanying drawings and examples. n Dated this 24th day of December 2013 Agent for the Applicant

BACKGROUND OF THE INVENTION
The invention relates to a rolling control apparatus, a rolling control method, and
a rolling control program and, more particularly, to a realization of a high accuracy of an
I
estimation value of an inter-stand thickness by a constant mass-flow rule.
1
1
I 5 There is such a tandem rolling mill that by arranging a plurality of rolling stands,
I
I a strip is rolled a plurality of number of times to thereby obtain a desired thickness. In such a
I
1
i tandem rolling mill, there is a case where such mass-flow thickness control that a strip speed of a
i
I strip which is rolled is detected, a thickness estimation value just under the rolling mill
(hereinbelow, referred to as "mass-flow estimation thickness") is obtained, and thickness control
10 is made is performed.
In order to stabilize a rolling at the time when a top end of a steel strip
(hereinafter, referred as "strip") serving as a material to be rolled is bitten into each rolling stand
and obtain a high accurate rolling result at a top end of the strip, that is, desired thickness and
width, it is necessary to set a rolling force of each rolling stand, that is, instruction values of a
15 rolling position (or a roll gap) and a roll speed to proper values. If the rolling force is improper,
since the thickness of the top end of the strip is not equal to a target value, a defective quality
occurs. On the other hand, if a roll speed is higher than a roll speed of a downstream rolling
stand, a loop of the strip occurs between the rolling stands and the rolling becomes unstable.
On the contrary, if the roll speed is low, the strip is pulled between the current rolling stand and
20 the downstream rolling stand and an excessive tension is generated. Thus, a width and a
thickness are reduced, thereby causing a quality of the strip to deteriorate.
In order to estimate the rolling force of each rolling stand, values of thicknesses
on the entry side and the delivery side of the rolling stand are necessary. The roll speed of each
rolling stand is calculated on the basis of such a rule that a product of the thickness and the speed
25 is constant on the entry side and the delivery side of the rolling stand (hereinbelow, referred to as
"constant mass-flow rule"). In ordinary hot rolling equipment, a thickness meter is provided
only for the delivery side of the final rolling stand. Therefore, it cannot help estimating a
thickness between the rolling stand and the rolling stand (hereinbelow, referred to as "inter-stand
thickness"). The improvement of a prediction accuracy of the inter-stand thickness is an
30 important subject as in the past.
As a conventional method of improving the prediction accuracy of the inter-stand
thickness, for example, the following method has been proposed. That is, an actual value of a
forward slip ratio showing a ratio between a roll peripheral speed and a delivery side speed is
obtained from information of time when the strip passes through each rolling stand, a forward
slip ratio calculation model is learned, a thickness of the top end of the strip and the roll
5 peripheral speed of each rolling stand are simultaneously detected on the final rolling stand
delivery side, and the thickness of each rolling stand is calculated by the constant mass-flow rule
from the detected thickness, the detected roll peripheral speeds, and the calculated forward slip
ratio (for example, refer to JP-A- 10- 1 5606).
The following method has also been proposed. That is, am inter-stand speed is
10 actually measured by a looper rotation detector attached between the stands and a thickness
between the rolling stands is estimated on the basis of the constant mass-flow rule from the
thickness detected by a thickness meter on the final rolling stand delivery side and - the inter-stand
speed (for example, refer to JP-A-5-3 05 3 20).
15 SUMMARY OF THE INVENTION
However, in the method disclosed in JP-A- 10- 15606, although the time when the
strip passes through each stand is determined in correspondence to a leading change of the
rolling force detected in each rolling stand, that is, a rolling force response at the time when the
top end of the strip has been bitten into the rolling stand, since a predetermined time is necessary
20 for the leading change itself, there is such a problem that it is difficult to decide the passing time
at a high accuracy. Further, as compared with a uniform distance between the rolling stands of
about 5m, the strip speed increases as the strip approaches the downstream rolling stand, so that
a decision accuracy of the passing time deteriorates as the strip approaches the downstream
rolling stand. In the method of JP-A-10-15606, since nothing is considered with respect to such
25 a point, there is such a problem that a decision accuracy of the passing time varies. In the
method of JP-A-5-305320, there is such a problem that costs for disposing the looper rotation
detector and costs for maintenance are high.
The invention intends to solve the problems as mentioned above and it is an
object of the invention to estimate an inter-stand thickness at a high accuracy without adding any
30 special hardware.
According to an aspect of the invention, there is provided a rolling control
apparatus for controlling a tandem rolling mill which rolls a strip by a plurality of roll pairs,
wherein:
a measurement result of a thickness on a delivery side of the roll pair arranged at
a final stage of rolling order among the plurality of roll pairs is obtained;
a thickness on an entry side is calculated on the basis of the obtained delivery side
thickness in accordance with a constant mass-flow rule;
a calculation result of the entry side thickness of the roll pair is used as a
5 thickness of the strip which is fed out from the roll pair arranged just before and the same
calculation is repeated, thereby calculating an entry side thickness of the roll pair arranged at the
head;
an error between the calculated entry side thickness of the roll pair arranged at the
head and a thickness on the entry side of the roll pair arranged at the head which is obtained by a
10 different method is calculated; and
an error of a calculation result of the entry side thickness of each roll pair within a
range from the roll pair arranged just after the roll pair arranged at the head of the rolling order
among the plurality of roll pairs to the roll pair arranged at the final stage is compensated on the
basis of the calculated error.
15 According to another aspect of the invention, there is provided a rolling control
method of controlling a tandem rolling mill which rolls a strip by a plurality of roll pairs,
wherein:
a measurement result of a thickness on a delivery side of the roll pair arranged at
a final stage of rolling order among the plurality of roll pairs is obtained;
20 a thickness on an entry side is calculated on the basis of the obtained delivery side
thickness in accordance with a constant mass-flow rule;
a calculation result of the entry side thickness of the roll pair is used as a
thickness of the strip which is fed out from the roll pair arranged just before and the same
calculation is repeated, thereby calculating an entry side thickness of the roll pair arranged at the
25 head;
an error between the calculated entry side thickness of the roll pair arranged at the
head and a thickness on the entry side of the roll pair arranged at the head which is obtained by a
different method is calculated; and
an error of a calculation result of the entry side thickness of each roll pair within a
30 range from the roll pair arranged just after the roll pair arranged at the head of the rolling order
among the plurality of roll pairs to the roll pair arranged at the final stage is compensated on the
basis of the calculated error.
According to still another aspect of the invention, there is provided a rolling
control program for controlling a tandem rolling mill which rolls a strip by a plurality of roll
pairs, wherein the program allows an information processing apparatus to execute the steps of:
obtaining measurement result of a thickness on a delivery side of the roll pair
arranged at a final stage of rolling order among the plurality of roll pairs;
calculating a thickness on an entry side on the basis of the obtained delivery side
5 thickness in accordance with a constant mass-flow rule;
using a calculation result of the entry side thickness of the roll pair as a thickness
of the strip which is fed out fiom the roll pair arranged just before and repeating the same
calculation, thereby calculating an entry side thickness of the roll pair arranged at the head;
calculating an error between the calculated entry side thickness of the roll pair
10 arranged at the head and a thickness on the entry side of the roll pair arranged at the head which
is obtained by a different method; and
compensating an error of a calculation result of the entry side thickness of each
roll pair within a range from the roll pair arranged just after the roll pair arranged at the head of
the rolling order among the plurality of roll pairs to the roll pair arranged at the final stage on the
15 basis of the calculated error.
According to the present invention, an inter-stand thickness can be estimated at a
high accuracy without adding any special hardware.
Other objects, features and advantages of the invention will become apparent
from the following description of the embodiments of the invention taken in conjunction with the
20 accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a diagram showing a whole construction of a rolling mill and a rolling
control apparatus according to an embodiment of the invention;
25 Fig. 2 is a diagram showing a state of a rough rolling according to the
embodiment of the invention;
Fig. 3 is a flowchart showing the calculating operation of a forward slip ratio of
the rough rolling according to the embodiment of the invention;
Fig. 4 is a flowchart showing the estimating operation of a roughing bar thickness
30 according to the embodiment of the invention;
Fig. 5 is a flowchart showing the estimating operation of an inter-stand thickness
according to the embodiment of the invention;
Fig. 6 is a flowchart showing the learning operation of a rolling force according to
the embodiment of the invention;
Fig. 7 is a flowchart showing the setup operation according to the embodiment of
the invention;
Fig. 8 is a diagram showing a draft schedule table according to the embodiment of
the invention;
5 Fig. 9 is a diagram showing a speed pattern table according to the embodiment of
the invention;
Fig. 10 is a diagram showing a construction of a speed instruction correcting unit
according to the embodiment of the invention;
Fig. 11 is a flowchart showing the extracting operation of a top end value
10 according to the embodiment of the invention;
I
I Fig. 12 is a flowchart showing the extracting operation of a stabilized value
I
! 1
according to the embodiment of the invention;
Fig. 13 is a diagram showing values which are stored by a top end value storing
unit and a stabilized value storing unit according to the embodiment of the invention;
15 Fig. 14 is a flowchart showing the speed instruction correcting operation
according to the embodiment of the invention;
Figs. 15A and 15B are diagrams showing states of the speed instruction correcting
operation according to the embodiment of the invention;
Fig. 16 is a flowchart showing the speed instruction balancing operation
20 according to the embodiment of the invention;
Fig. 17 is a diagram showing a state of the speed instruction balancing operation
according to the embodiment of the invention; and
Fig. 18 is a diagram showing a hardware construction of the rolling control
apparatus according to the embodiment of the invention.
25
DESCRIPTION OF THE EMBODIMENTS
An embodiment of the invention will be described in detail hereinbelow with
reference to the drawings. In a rolling system according to the embodiment, a rough rolling in
which a slab serving as a raw material is reciprocatingly rolled until a thickness is equal to an
30 inter-stand thickness and a finish rolling in which a rough-rolled strip is tandem-rolled at a high
accuracy so that the thickness is equal to a target thickness are performed. In the finish rolling,
the inter-stand thickness obtained by the constant mass-flow rule is compensated on the basis of
an error between the thickness on the entry side of a head rolling stand obtained by the constant
mass-flow rule and a thickness on the entry side of the head rolling stand which is obtained by a
different method. Thus, high accuracy of an estimation value of the inter-stand thickness can
be realized. Consequently, the rolling of the strip top end can be stabilized and the strip of a
high quality can be produced.
Fig. 1 is a block diagram showing a functional construction of a rolling control
apparatus according to the embodiment of the invention. A control apparatus 100 of a hot
tandem rolling mill receives various kinds of signals from a controlled object 150, that is, a
rolling mill including a rougher rolling stand and a finisher rolling stand and outputs a control
signal to the controlled object 150. First, a construction of the controlled object 150 will be
described. In the embodiment, the controlled object 150 is a hot rolling mill having a rougher
mill 15 1 and a finisher mill 160. In the example shown in the diagram, the rougher mill 15 1 is
constructed by a vertical rolling mill 152 and a horizontal rolling mill 153.
The finisher mill 160 is constructed by a plurality of rolling stands. In the
embodiment, the finisher mill 160 is constructed by continuously arranging seven rolling stands
161 (F1 to F7). In Fig. 1, the strip serving as a material to be rolled is moved from the left to
the right and a reciprocating rolling is performed by the rougher mill 15 1 to a slab 154 of a high
temperature extracted from a heating hrnace corresponding to a further precedent step than the
rougher mill 15 1. The rolling of one time is called a "pass" and the rolling of about 3 to 7
passes is ordinarily performed.
In the rougher mill 15 1, the slab is reciprocated. In the vertical rolling mill 152,
such a rolling as to align a width of slab is performed. In the horizontal rolling mill 153, such a
rolling as to reduce a thickness of slab is performed. In the rougher mill 15 1, the slab 154 is
finally worked to a roughing bar 157 having a thickness of about 30 mm and is sent to the
finisher mill 160. There is a case where the roughing bar 157 is also called by a name such as
rough bar, incoming bar, transfer bar, or the like.
In the finisher mill 160, the roughing bar 157 is sequentially worked so as to be
thin by the rolling by each rolling stand 161 and is threaded as a strip having a final target
thickness, for example, as a strip 163 of about 1 to 15 mm on the F7 delivery side. In the
rougher mill 15 1 and the finisher mill 160, devices which directly roll the slab 154, roughing bar
157, and strip 163 are the horizontal rolling mill 153 and a workroll 162 provided for each
rolling stand 161. In the invention, "roll speed denotes a peripheral speed of the workroll 162.
In the embodiment, as a detector to grasp states of the slab 154, roughing bar 157,
and strip 163, a strip width meter 155 to measure a width of slab is provided on the entry side of
the rougher mill 15 1. A strip width meter 156 to measure a width of roughing bar 157 and an
HMD (Hot Metal Detector) 158 to detect an arrival of the roughing bar 157 are provided on the
delivery side of the rougher mill 15 1. Further, a multigauge 164 to measure a thickness and a
width of the strip 163 is provided on the delivery side of the final rolling stand (F7) of the
finisher mill 160.
Although omitted in the embodiment, actually, as a detector to grasp states of the
slab 154, roughing bar 157, and strip 163, the following various kinds of detectors are provided
at respective positions in accordance with necessity: that is, a thermometer; a shape meter to
measure a flatness of the strip; a crop profile gauge to measure shape images of a top end and a
tail end of the roughing bar 157; a surface damage meter to detect a surface damage of the strip
163; and the like.
Subsequently, a construction of the control apparatus 100 of the hot tandem
rolling mill will be described. In the control apparatus 100 of the hot tandem rolling mill, a
setup unit 101 receives information necessary for rolling such as steel grade, target thickness,
target width, and the like from a host computer 50 with respect to each strip to be rolled. The
setup unit 101 calculates a rolling force, a rolling position (or roll gap) of the workroll 162, a roll
speed of the workroll 162, and the like with respect to each rolling stand 161 with reference to a
draft schedule table 102 and a speed pattern table 103.
An actual value collecting unit 110 collects a rolling actual value from the
controlled object 150 and a control instruction value which was actually outputted to the
controlled object from the control apparatus 100 of the hot rolling mill. A rough rolling
forward slip ratio estimating unit 11 1 estimates a forward slip ratio in the rolling of the final pass
in the rougher mill 15 1 by using data collected by the actual value collecting unit 11 0. A
roughing bar thickness estimating unit 112 estimates a thickness of the roughing bar 157 from
the data collected by the actual value collecting unit 110 and an output of the rough rolling
forward slip ratio estimating unit 11 1. An inter-stand thickness estimating unit 1 13 estimates a
thickness of the strip between the rolling stands 161 (hereinbelow, referred to as an inter-stand
thickness) of the finisher mill 160 from the data collected by the actual value collecting unit 110.
Further, the inter-stand thickness estimating unit 11 3 estimates a final inter-stand thickness by
correcting the estimated inter-stand thickness by using the thickness of the roughing bar 157
estimated by the roughing bar thickness estimating unit 112.
"forward slip ratio" mentioned here denotes a value corresponding to a ratio
between the peripheral speed of the workroll and the delivery side speed of the strip which is
rolled by the workroll. The forward slip ratio is obtained by the following equation (1).
f = F(H7 h, R', &, fb, tf) . . . (1)
where,
H: Entry side thickness
h: Delivery side thickness
R' : Deformed workroll radius
KP: Deformation resistance
tb: Entry side tension
tf: Delivery side tension
By using the data collected by the actual value collecting unit 110 and the
thickness estimated by the inter-stand thickness estimating unit 11 3, a rolling force learning unit
114 calculates a learning coefficient which is used when a rolling force is calculated. A speed
instruction correcting unit 120 corrects the roll speed calculated by the setup unit 101 with
respect to a strip which is rolled next time. A speed instruction balancing unit 121 fetches an
output of the speed instruction correcting unit 120 and limits a speed correction amount to each
rolling stand 161 so as to lie within upper and lower limits in consideration of a balance between
the rolling stands.
A speed control unit 122 makes speed control in response to an instruction of a
final roll speed. A rolling position control unit 130 controls an actual rolling position by using
a signal showing a difference (thickness deviation) between the actual thickness measured by the
multigauge 164 and a target thickness or the like in response to a rolling position instruction
outputted from the setup unit 10 1.
The operation of each unit will be described in detail hereinbelow. Fig. 2 shows
a detailed construction of the rougher mill 15 1. In the rougher mill 15 1, the slab 154 is
sequentially worked by the reciprocating milling so as to become thin. Further, in parallel with
it, width control is made by the vertical rolling mill 152 so that the roughing bar 157 has a
predetermined width. In the rolling of the final pass of the rougher mill 15 1, the roughing bar
157 is fed to the finisher mill 160.
To a peripheral speed V, in the rolling of the final pass of a workroll 201 provided
for the horizontal rolling mill 153, a speed V, of the roughing bar 157 rolled by the workroll 201
is obtained by the following equation (2) by using the forward slip ratio.
v, = (l+f) .v, . . . (2)
where,
f Forward slip ratio
Although the speed V, of the roughing bar 157 is higher than the peripheral speed
V, of the workroll 201 by (l+f) times, f cannot be directly detected. Therefore, a case of
estimating f by using an actual value of the rolling is now considered.
The final pass in the rough rolling is a rolling process just before the strip is
inserted to the finisher mill 160 in order to perform the finisher rolling and corresponds to a final
rough rolling process for conveying the strip within a range from the top end to the tail end to the
rougher mill 15 1 one time.
5 Fig. 3 shows a process in which the rough rolling forward slip ratio estimating
unit 11 1 estimates a forward slip ratio. Time when the horizontal rolling mill 153 has started
the rolling of the final pass is assumed to be tl, time when the mill 153 has finished the rolling of
the final pass is assumed to be t3, and a peripheral speed of the workroll 201 between tl and t3 is
assumed to be VXt). Further, time when the roughing bar 157 has reached the HMD 158 is
10 assumed to be t2 and a distance between the horizontal rolling mill 153 and the HMD 158 is
assumed to be Lhmd
Although the arrival of the HMD 158 is used as a reference point of the distance
calculation in the embodiment, it is necessary that the roughing bar 157 reaches the distance
calculation reference point during the rolling in the horizontal rolling mill 153. That is, it is
15 necessary that t2 < t3. Generally, as an apparatus which can detect the arrival of the roughing
bar 157, the strip width meter 156 which outputs a "strip presence detection signal", the crop
profile gauge which outputs a "strip arrival signal" and measures the shape of the top end of the
roughing bar 157, and the like are provided between the rougher mill 15 1 and the finisher mill
160. If the HMD 158 is not disposed at the proper position, it is also considered to use those
20 signals as a reference point of the distance calculation.
As shown in Fig. 3, first, the rough rolling forward slip ratio estimating unit 11 1
fetches a load-on signal of the horizontal rolling mill 153 (S301) and obtains tl. Subsequently,
the rough rolling forward slip ratio estimating unit 11 1 fetches a signal showing that the HMD
158 has detected the top end of the roughing bar 157 (S302) and obtains tz. The rough rolling
25 forward slip ratio estimating unit 11 1 calculates a rotational peripheral length L,I of the
workroll 201 by the following equation (3) by an integration of the peripheral speed of the
workroll 201 for a period of time from the load-on of the horizontal rolling mill 153 to the
detection of the top end by the HMD 158 (S303).
L,, = p vr (4 dt . . .
30 When the rotational peripheral length L,1 is calculated, the rough rolling forward
slip ratio estimating unit 11 1 calculates a value of the average forward slip ratio for a period of
time from the load-on of the horizontal rolling mill 153 to the detection of the top end by the
HMD 158 (S304). An estimation value fea of the forward slip ratio can be obtained by the
- 10-
following equation (4).
fest = LhmdILwr . . . (4)
Fig. 4 shows a process of the roughing bar thickness estimating unit 112. As
shown in Fig. 4, the roughing bar thickness estimating unit 112 fetches a thickness, a length, and
5 a width of the slab 154 (S401). As those values, generally, values which were previously
measured in the pre-step are transmitted from the host computer 50, in the embodiment, the slab
width can be measured by the strip width meter 155. With respect to the items which are
detected by the detectors as mentioned above, they may be rewritten by values fetched fiom the
controlled object 150 and values of a highest accuracy are used.
10 The roughing bar thickness estimating unit 112 fetches a value of the width of the
slab 154 measured by the strip width meter 155 from the controlled object 150 (S402). In the
final pass of the rougher mill 15 1, a peripheral length I-2 of the workroll 201 for a period of
time from the start of the rolling of the horizontal rolling mill 153 to the end thereof (S403). As
shown by the following equation (5), the peripheral length is obtained by integrating a value of
15 the peripheral speed Vdt) for a period of time from the rolling start time tl of the horizontal
rolling mill 153 to the rolling end time t3.
When the roughing bar thickness estimating unit 112 obtains the peripheral length
Lwr2 of the workroll 201 by the equation (5), as shown by the following equation (6), a length Lb
20 of the roughing bar 157 is obtained by multiplying L,2 by the forward slip ratio fea.
Lb = fest x Lwrz . . . (6)
When the roughing bar thickness estimating unit 112 obtains the length Lb of the
roughing bar 157 by the equation (6), by paying an attention to a fact that volumes are preserved
in the slab 154 and the roughing bar 157 which has been rolled by the rougher mill 15 1, the unit
25 112 estimates a thickness tb of the roughing bar by the following equation (7) by using the
following items. That is, the roughing bar thickness estimating unit 112 functions as a rough
rolling result obtaining unit.
tb = (ts x Ws x Ls)/(Wb x Lb) . . . (7)
where,
30 t,: Slab thickness
W,: Slab width
Ls: Slab length
Wb: Width of roughing bar
Length of roughing bar
Fig. 5 shows a process which is executed by the inter-stand thickness estimating
unit 113. With respect to the relevant strip 163 whose rolling has been completed, the interstand
thickness estimating unit 113 estimates an inter-stand thickness on the basis of the rolling
5 actual value. As shown in Fig. 5, the inter-stand thickness estimating unit 113 fetches a value t7
of the thickness measured by the multigauge 164 on the delivery side of a final rolling stand (F7)
(S501).
On the entry side and the delivery side of F7, what is called a constant mass-flow
rule in which the product of the thickness and the speed is constant is satisfied. The inter-stand
10 thickness estimating unit 113 estimates a thickness on the delivery side of F6 by the following
equation (8) in accordance with the constant mass-flow rule (S502).
tfj = t7 X v7 X (1+f7)/(v6 X (l+f6)) . . . (8)
where,
t7: Measured delivery side thickness of F7
15 V7: Peripheral speed of the F7 workroll
f7: Forward slip ratio of F7
V6 : Peripheral speed of the F6 workroll
fii: Forward slip ratio of F6
That is, the inter-stand thickness estimating unit 113 hnctions as a delivery side
20 thickness obtaining unit to obtain the value t7 of the thickness measured by the multigauge 164
and also hnctions as a thickness calculating unit to calculate a delivery side thickness of each
stand on the basis of the constant mass-flow rule.
As forward slip ratios f6 and f7, values calculated by the setup unit 101 prior to the
rolling of the relevant strip are used. Although the calculation is performed by using the
25 foregoing equation (I), since it is a calculation by the estimation using a numerical expression,
the value contains a predetermined error and an error has also been superimposed in the interstand
thickness which was estimated on the basis of such a value. A compensation of the error
is executed in S505 and S506, which will be described hereinafter. This is one of the gists of
the embodiment.
30 By repeating a process similar to that shown by the foregoing equation (8), the
inter-stand thickness estimating unit 113 estimates a delivery side thickness of each rolling stand,
that is, an inter-stand thickness in the tandem rolling in order of F5, F4, F3, F2, and F1 (S503).
In this manner, the inter-stand thickness estimating unit 113 executes the arithmetic operation to
obtain the thickness on the stand entry side from each forward slip ratio and the thickness on the
rolling stand delivery side in order from the downstream rolling stand. Further, the inter-stand
thickness estimating unit 113 estimates a thickness tb - ,t of the roughing bar 157 by a similar
process by using the following equation (9).
tb-est = tl X V1 X (l+fl)Nb . . . (9)
5 where,
tl: Estimated delivery side thickness of Fl
V1: Peripheral speed of the F 1 workroll
fi: Forward slip ratio of F 1
Vb: Speed of the roughing bar 1 57
10 The inter-stand thickness estimating unit 11 3 calculates a deviation Atb between
the thickness tb of the roughing bar 157 estimated by the roughing bar thickness estimating unit
112 and the estimated thickness tb - ,t of the roughing bar (S505). Further, by using the
following equation (lo), the inter-stand thickness estimating unit 113 corrects the estimation
value of the inter-stand thickness by using Atb and calculates an inter-stand thickness which is
15 used in the calculation in the rolling force learning unit 114 and the speed instruction correcting
unit 120 (S506).
ti-& = ti x Atb X (ti/tb-&) . . . (lo)
where,
ti : Delivery side thickness of the Fi stand estimated in S502 and S503
20 That is, the inter-stand thickness estimating unit 113 functions as an error
compensating unit.
As mentioned above, in the embodiment, by executing the calculation according
to the constant mass-flow rule on the basis of the measurement result of the thickness meter
provided on the delivery side of the rolling stand arranged at the final stage of the tandem rolling
25 mill, the thickness on the entry side of each stand is calculated. Since the thickness on the entry
side which was calculated in this manner is a delivery side thickness of the rolling stand arranged
just before, by repeating the calculation according to the constant mass-flow rule, the delivery
side thickness of the rolling stand at each stage, that is, the inter-stand thickness can be obtained
in order.
30 The error of each inter-stand thickness obtained in accordance with the constant
mass-flow rule is compensated on the basis of the error between the entry side thickness of the
rolling stand disposed at the head of the tandem rolling mill which was obtained by repeating the
calculation according to the constant mass-flow rule and the thickness of the roughing bar 157
obtained by the method described in Fig. 2, that is, the entry side thickness of the tandem rolling
mill. A point that the prediction accuracy of the inter-stand thickness is improved by such a
process is one of the gists of the embodiment.
In the embodiment, when each inter-stand thickness obtained in accordance with
the constant mass-flow rule is corrected, a correction value to correct each inter-stand thickness
is determined on the basis of the error between the entry side thickness of the tandem rolling mill
obtained in accordance with the constant mass-flow rule and the entry side thickness of the
tandem rolling mill obtained by another method. At this time, as shown by the above equation
(lo), a correction value is calculated by multiplying the error by a ratio of the thickness of the
correction target to the entry side thickness of the tandem rolling mill obtained according to the
constant mass-flow rule. That is, a portion of Atb x (ti/tb - &) in the numerical expression
included in the equation (10) is a portion showing the correction value. By such a process, the
correction value of each inter-stand thickness can be preferably obtained.
When the correction value to be applied to each inter-stand thickness is calculated
on the basis of the error between the entry side thickness of the tandem rolling mill obtained as
mentioned above in accordance with the constant mass-flow rule and the entry side thickness of
the tandem rolling mill obtained by another method, such a method that the error is distributed to
each inter-stand thickness is also considered besides the method as mentioned above. As a
distributing method, in addition to the method of uniformly distributing the error, the correction
value can be also decided on the basis of rolling ratio in each rolling stand.
Since the prediction accuracy of the inter-stand thickness is improved by such a
process, an accuracy of the subsequent process using the inter-stand thickness can be improved.
The subsequent process will be described hereinbelow. Fig. 6 shows a process of the rolling
force learning unit 114. The rolling force learning unit 114 estimates a rolling force of each
stand from actual values of a rolling temperature and a roll speed fetched from the controlled
object 150, estimation values of the thicknesses on the entry side and the delivery side of the
stand, and the like and calculates a rolling force correction coefficient for correcting the rolling
force estimation values on the basis of a comparison with the actual rolling force of each stand
fetched from the controlled object 150. That is, the rolling force learning unit 114 fknctions as
a rolling force calculating unit.
As shown in Fig. 6, the rolling force learning unit 114 fetches rolling force actual
values of F1 to F7 in the rolling from the controlled object 150 (S601). Subsequently, the
rolling force learning unit 114 executes an estimation arithmetic operation of the rolling force
every stand by using a rolling force predicting expression fetched from the controlled object 150
(S602).
The rolling force is a force necessary to thin the entry side thickness so as to
become the delivery side thickness. The larger the entry side thickness is and the smaller the
delivery side thickness is and the larger a deformation resistance is, the rolling force is set to a
larger value. The more the values of the entry side thickness and the delivery side thickness are
5 accurate, the rolling force can be estimated at a higher accuracy. The rolling force predicting
expression is obtained by using, for example, the following items by the following equation (1 1).
P = g(w, &, Qp, tf, tb, R', K, h, P) . . . (11)
where,
w: Wldth
10 Kp: Deformation resistance
QP : Rolling force function
P: Friction coefficient
In the equation (1 l), the value of ti - estimated in the equation (10) is used as an
entry side thickness H and a delivery side thickness h. Naturally, ti - ,a is also used as an entry
15 side thickness of the (i+l) stand. Actual values fetched from the controlled object 150 are used
as a backward tension tb and a forward tension tf. Calculations of the deformed workroll radius
R', the deformation resistance Kp, and the rolling force function Qp are also executed by using
actual values or the values calculated from the actual values.
The rolling force learning unit 114 calculates a rolling force correction coefficient
20 & from an actual rolling force and an estimation rolling force by the following equation (12).
(Zp)i = (Pxt)iJ(Pest)i . . . (12)
where,
Actual rolling force of the i-th stand of the finisher mill 160 fetched from the
control
25 target 150
(Pest)i: Estimation rolling force of the i-th stand calculated in the equation (1 1)
(Zp)i : Rolling force correction coefficient of the i-th stand
In the setup unit 101, (Z,); is used in an estimation calculation of a rolling force
for the strip 163 to be rolled next time.
30 Fig. 7 shows a process which is executed by the setup unit 101. ARer
information necessary to roll such as steel grade, target thickness, target width, and the like was
received from the host computer 50, the setup unit 101 calculates control instructions about a
rolling position, a roll speed, and the like for the strip to be rolled from now on. Although the
setup unit 101 inherently executes such arithmetic operations to the rougher mill 15 1 and the
finisher mill 160, in the embodiment, the arithmetic operation to the rougher mill 15 1 is omitted
and only the contents of the setup arithmetic operation to the finisher mill 160 serving as a range
where the invention is applied are disclosed.
In the finisher mill 160, since a top end of the strip 163 is rolled in response to the
5 control instruction outputted from the setup unit 101, in order to obtain a desired strip thickness
fiom the top end, it is necessary to properly set the rolling force and the rolling position of the
workroll 162. In order to stabilize a behavior at the time when the strip is bitten to the
downstream stand, it is necessary to set the roll speed of each stand to a speed according to an
instruction of a good balance so as not to disturb the mass-flow of the strip 163.
10 As shown in Fig. 7, fiom the items corresponding to the draft schedule table 102,
the setup unit 101 fetches a draft schedule serving as information showing to which extent the
roughing bar 157 and the strip 163 are thinned by each of the rolling stands 161 of Fl to F7
(S701). Fig. 8 shows an example of a construction of the draft schedule table 102. Avalue
showing the thickness of the roughing bar 157 which is rolled by each rolling stand 161 to a
15 difference between the thicknesses of the roughing bar 157 and the strip 163 has been stored in
the draft schedule shown in the example of Fig. 8 as a percentage to the thickness difference.
Each draft schedule has been classified with respect to the steel grade, thickness, width, and the
like of the strip which is rolled.
For example, the roughing bar 157 of 35 mm in which a steel grade is SS400, a
20 target thickness is 2.5 mm, and a target width is 900 mm is now considered. A class in which
the target thickness is equal to 2.0 to 3.0 mm and the target width is equal to or less than 1000
mm corresponds to such a strip. Since the roughing bar 157 of 35 mm is rolled to the strip 163
of 2.5 mm, this means that with respect to the thickness difference of 32.5 mm, in the rolling
stand of F 1, 24% of the thickness is rolled, and in F2, 16% is rolled. That is, in F1, the rolling
25 shown by the following equation (13) is performed and the roughing bar of 35 mm is rolled so as
to become a thickness of 27.2 mm (= 35 mm - 7.8 mm).
32.5 mm x 241100 = 7.8 mm . . . (13)
Similarly, in F2, since 16% is rolled, the rolling shown by the following equation
(14) is performed and the strip of 27.2 mm is rolled so as to become a thickness of 22.0 mm (=
30 27.2 mm - 5.2 mm).
32.5 mm x 161100 = 5.2 mm . . . (14)
As for a certain class, the sum of numerical values of the rolling stands of the
draft schedule is equal to 100. By repeating a similar calculating procedure, a delivery side
thickness of F7 as a final stand becomes 2.5 mm serving as a target thickness. In this manner,
- 16-
in S701, the setup unit 101 searches the relevant class position in the draft schedule table 102 on
the basis of information about a steel grade, a thickness, and a width of the strip (which is rolled
next) received from the host computer 50 and fetches a rolling amount of each rolling stand.
Subsequently, the setup unit 101 fetches a speed pattern from the speed pattern
table 103 (S702) and calculates the roll speed of each rolling stand. Fig. 9 shows a construction
of the speed pattern table 103. Values of the following speeds have been stored every class in
the table 103 for the steel grade, target thickness, and target width of the strip 163: that is, a
threading speed at the time when the top end of the strip 163 is threaded from F7 as a final
rolling stand, that is, an initial speed; thereafter, a first acceleration; a second acceleration; a
maximum speed; a deceleration at the time of decelerating from the maximum speed to a tailing
speed at the time of rolling the tail end of the strip 163; and the tailing speed.
The setup unit 101 discriminates the steel grade, thickness, and width of the strip
163 and extracts the corresponding speed pattern from the speed pattern table 103. For
example, when the steel grade is SS400, the thickness is 2.0 to 3.0 mm, and the width is 1000
mm or less, it is shown that the following values are set: that is, the initial speed is 650 mpm; the
first acceleration is 2 mprn/sec; the second acceleration is 12 mpdsec; the maximum speed is
1 100 mpm; the deceleration is 6 mpdsec; and the tailing speed is 900 mpm.
Subsequently, the setup unit 101 estimates a rolling temperature (S703).
Temperatures of the roughing bar 157 and strip 163 are estimated by combining a value detected
by a thermometer and a temperature prediction calculation which is performed in consideration
of a heat radiation, a heat transfer, and the like. As for a temperature estimating method, since a
number of methods have been introduced in literatures of thermodynamics and the like, a
detailed description is omitted here.
The setup unit 10 1 calculates a deformation resistance as a value corresponding to
hardness of the strip which is rolled by each rolling stand (S704). The deformation resistance
has been disclosed in various literatures and is obtained by the following equation (1 5) by using
an estimated strip temperature T upon rolling as a typical calculating expression.
kf = K~"(dJd~)"exp(A/T) . . . (15)
where,
E: Strain
(dddt) : Strain speed
K, n, m, A: Constants which are determined every steel grade
Subsequently, the setup unit 101 calculates a roll speed of each rolling stand
(S705). Since the speed pattern fetched in S702 is a speed on the delivery side of F7, the
delivery side speed of each rolling stand is calculated as follows on the basis of it. First, the
delivery side speed of each rolling stand is calculated by the following equation (16).
Vsi = V, x hill17 . . . (16)
where,
Vsi : Delivery side speed of the i-th stand
hi: Delivery side thickness of the i-th stand
h7: Delivery side thickness of the seventh stand (final rolling stand)
Subsequently, the setup unit 101 calculates a roll speed of each rolling stand from
the delivery side speed of each rolling stand by using the forward slip ratio. When the forward
slip ratio is used, there is a relation between the roll speed and the delivery side speed as shown
by the following equation (1 7).
V, = Vsilfi . . . (17)
where,
V,: Roll speed of the i-th stand
fi: Forward slip ratio of the i-th stand
The setup unit 101 calculates a forward slip ratio every rolling stand and obtains a
roll speed of each rolling stand. Further, the setup unit 101 calculates a rolling force (S706).
The rolling force is calculated by the equation (11). Finally, the setup unit 101 calculates a
rolling position (or roll gap) of the workroll 162 (S707). A hndamental portion of the
calculation of the rolling position is expressed by the following relational equation (1 8), actually,
various kinds of correction terms are added in order to raise a calculation accuracy.
S = h - Plk . . . (18)
where,
S: Rolling position
P: Rolling force
K: Mill spring constant
The setup unit 101 outputs the roll speed and rolling position calculated as
mentioned above as control instructions in correspondence to the strip to be rolled next time.
Since such a process is executed on the basis of the inter-stand thickness of the high accuracy as
mentioned above, a rolling result at the top end of the strip obtained for a period of time until an
actual rolling phenomenon, particularly, feedback control becomes stable can be made to
approach a desired target value.
Fig. 10 shows a construction of the speed instruction correcting unit 120 in detail.
The speed instruction correcting unit 120 is constructed by: a top end value extracting unit 1001
for extracting rolling data of a top end portion of the previously-rolled strip 163 fiom the data
collected from the controlled object 150 by the actual value collecting unit 110; a top end value
storing unit 1003 for storing the value extracted by the top end value extracting unit 100 1; a
stabilized value extracting unit 1002 for extracting the roll speed, rolling force, and rolling
5 position of each rolling stand 161 after the precedent rolling of the strip 163 reached a stabilized
state; a stabilized value storing unit 1004 for storing the value extracted by the stabilized value
extracting unit 1002; and a speed correction value calculating unit 1010 for fetching the contents
in the top end value storing unit 1003 and the stabilized value storing unit 1004 and correcting
the roll speed calculated by the setup unit 101 to the strip to be rolled next time.
10 Fig. 11 shows a process of the top end value extracting unit 100 1. The top end
value extracting unit 1001 fetches, every rolling stand, values of the rolling position, rolling
force, and roll speed at the time when the top end of the strip 163 from the output of the actual
value collecting unit 110. In the embodiment, it is assumed that with respect to the rolling
position and the rolling force, the actual values are fetched, and with respect to the roll speed, the
15 set value outputted by the speed control unit 122 is fetched.
As shown in Fig. 11, the top end value extracting unit 100 1 discriminates whether
or not a threading length (rolled length) of the strip 163 in each rolling stand has reached a
predetermined length (S 1101). Generally, the rolled length is included in the signal fetched
fiom the controlled object 150. By using the relation of the equation (17), the rolled length is
20 calculated by integrating the speed of the strip 163 estimated from the roll speed of each rolling
stand by using the forward slip ratio. In the embodiment, an attention is paid to the rolled
length and the data of the top end portion is extracted.
If it is determined in S 11 01 that the threading length of the strip 163 does not
reach the predetermined length (NO in S 1 10 l), the top end value extracting unit 100 1 repeats the
25 process of S 1101. If it is determined that the threading length has reached the predetermined
length (YES in S 1 101), the top end value extracting unit 1001 fetches the roll speed, rolling
position, and rolling force of the relevant rolling stand from the actual value collecting unit
(S1102).
The top end value extracting unit 1001 discriminates whether or not the process
30 has been finished with respect to all rolling stands (S1103). If the process has not finished (NO
in S1103), the process from SllOl is repeated with respect to the rolling stand in which the
process is not finished. At a point of time when the fetching of the roll speed, rolling position,
and rolling force of the top end of the strip has been finished with respect to all of the rolling
stands (YES in S 1 103), the process of the top end value extracting unit 1001 to the strip 163 is
finished.
Fig. 12 shows a process of the stabilized value extracting unit 1002. The
stabilized value extracting unit 1002 fetches the values of the rolling position, rolling force, and
roll speed at the same time of each rolling stand at the time when the rolling has reached the
5 stabilized state from the output of the actual value collecting unit 110. As shown in Fig. 12, the
stabilized value extracting unit 1002 discriminates whether or not the F7 threading length (rolled
length) of the strip 163 has reached the predetermined length (S1201). Generally, the rolled
length is included in the signal fetched from the controlled object 150. By using the relation of
the equation (17), the rolled length is calculated as a result of integrating the speed of the strip
10 163 estimated from the roll speed of F7 by using the forward slip ratio in the case where the F7
load-on timing is set to a start point.
When the rolled length of F7 is small, the rolling is in a transient state just afler
the strip 163 was bitten. However, when the rolled length is large, the rolling becomes stable.
By paying an attention to such a point, in the embodiment, the stability of the rolling is
15 discriminated by paying an attention to the rolled length, and the stabilized data is extracted. If
it is determined that the F7 threading length of the strip 163 does not reach the predetermined
length (NO in S 1201), the stabilized value extracting unit 1002 repeats the process from S 120 1.
If it is determined that the F7 threading length of the strip 163 has reached the predetermined
length (YES in S1201), the stabilized value extracting unit 1002 fetches the roll speed, rolling
20 position, and rolling force of each rolling stand in a lump from the actual value collecting unit
(S 1202).
Fig. 13 shows a construction of the top end value storing unit 1003 and the
stabilized value storing unit 1004. The values of the rolling position, rolling force, and roll
speed which were extracted and outputted by the top end value extracting unit 1001 in
25 correspondence to the timing when each rolling stand had rolled the top end of the strip have
been stored in the top end value storing unit 1003. For example, the following data has been
stored: that is, the rolling position of Fl is 30.40 mm; the rolling force is 2364 ton; and the roll
speed is 27 mpm.
The values of the rolling position, rolling force, and roll speed of each rolling
30 stand which were outputted by the stabilized value extracting unit 1002 in correspondence to the
timing when the rolling had reached the stabilized state have been stored in the stabilized value
storing unit 1004. For example, the following data has been stored: that is, the rolling position
of Fl is 29.78 mm; the rolling force is 2380 ton; and the roll speed is 26.4 mpm.
Fig. 14 shows a process which is executed by the speed correction value
calculating unit 1010. As shown in Fig. 14, first, the speed correction value calculating unit
1010 fetches the rolling position, rolling force, and roll speed of a front coil top end portion
corresponding to each rolling stand from the top end value storing unit 1003 (S1401).
Subsequently, the speed correction value calculating unit 10 10 fetches the rolling position,
rolling force, and roll speed of a front coil stabilized portion corresponding to each rolling stand
from the stabilized value storing unit 1004 (S 1402).
Subsequently, the speed correction value calculating unit 1010 calculates a
correction amount of the speed instruction every rolling stand (S1403). A calculating method
will now be described in detail with reference to Figs. 15A and 15B. Figs. 15A and 15B
illustrate behaviors of a strip top end and the rolling stand in the stabilized state with respect to
the j-th stand (Fj) as an example. Fig. 15A illustrates the behavior of the strip top end and
shows the following data: that is, the rolling force, rolling position, and roll speed just after a
strip top end 1503 was rolled are equal to Pb-tq, Sa.top, and Vsd, and a delivery side thickness of
the Fj stand is h, respectively.
Fig. 15B illustrates the behavior after the rolling reached the stabilized state.
The strip top end 1503 is located on the delivery side of F7 (final rolling stand). All of the
rolling stands were performing the rolling and are balanced. Fig. 15B shows the following
data: that is, the rolling force, rolling position, and roll speed at this time are Sact-*, and
V-b, and the thickness of the Fj stand is h, respectively. Since a product (mass-flow) of the
thickness and the speed is constant, if an inherent roll speed of the top end is derived from the
balance state, the following equation (1 9) is obtained.
Vtop-est. (Ifftop) . (Stop + Ptom) = Vstab. (l+Etab) ' (Sstab + PstadM) . . . (19)
where,
Vtop-e~t Inherent roll speed at the time when the strip top end has been rolled
ftW: Forward slip ratio at the time when the strip top end portion has been rolled
sop: Rolling position at the time when the strip top end portion has been rolled
PtT: Rolling force at the time when the strip top end portion has been rolled
M: Mill constant
Vstab: Roll speed at the time when the strip stabilized portion has been rolled
fstab : Forward slip ratio at the time when the strip stabilized portion has been rolled
S*: Rolling position at the time when the strip stabilized portion has been rolled
Pstab: Rolling force at the time when the strip stabilized portion has been rolled
In the equation (1 9), V . (l+f) corresponds to the speed and (S+P/M) corresponds
to the thickness. Now, assuming that 1 + ftop% 1 + fstab, the following equation (20) is satisfied.
Vtop-est ' (Stop + PtodM) = Vstab . (Sstab + PstadM) . . . (20)
Therefore, the following equation (21) is satisfied.
Vtop-est = Vstab ' (Sstab + PstadM)/(Sstab + PstadM + Stop - Sstab + (Ptop - Pstab)m
= Vstab • h/(h + Stop - Sstab + (Ptop - Pstab)/M) . . . (21)
5 (Sstab - pstam = h)
Similarly, the following equation (22) is satisfied with respect to F7 (final rolling
stand).
V7top-est = V7stab • hd(h7 + S7top - S7stab + (P7top - P7stab)M) . . . (22)
In the final rolling stand, at the start point of the speed control, since the roll
10 speed does not change during the rolling, the following equation (23) is satisfied.
V7stab = V7set . . . (23)
The start point of the speed control can be also set to another stand. A speed
correction coefficient a, of each rolling stand is a ratio between a speed instruction set to the strip
163 which was rolled last time and an inherent speed instruction calculated from the roll speed in
15 a state where the rolling has been balanced. The inherent speed instruction is obtained by a
method whereby in each stand, the roll speed in the state where the rolling has been balanced is
converted into the roll speed of the strip top end in accordance with the constant mass-flow rule
by using the strip thickness at this time and the strip thickness at the time when the strip top end
has been rolled.
20 That is, the speed correction coefficient ai can be calculated by the following
equation (24).
ai = (Vi.top-estNi.set) ' (V7.setN7.top-est )
= (Vi.act-stadVi.set) ' hi/{(hi f Si.act-top - %.act-stab + Pi.acLtop - Pi.act-stab)mi) '
{(h7 + S7.act_top- S7.act-stab + P7.act_top- P7.act-stab)m7)/h7 . . . (24)
25 where,
Vi.top-est: Inherent rolling speed at the time when the i-th stand is rolled the strip top end
portion
V7top-est: Inherent rolling speed at the time when the 7-th stand is rolled the strip top end
portion
30 Vi.h - stab: Roll speed at the time when the i-th stand has rolled the strip stabilized portion
Vi,set: Roll speed set value at the time when the i-th stand has rolled the strip top end
hi : Delivery side thickness of the i-th stand
Si.ac-top: Rolling position at the time when the i-th stand has rolled the strip top end portion
Si.acLstab: Rolling position at the time when the i-th stand has rolled the strip stabilized
portion
Pi.act_top:
Pi.act-stab:
Mi:
5 v7.act stab:
portion
v7.set:
h7:
s7.act-top:
10 portion
S7.ad-stab:
Rolling force at the time when the i-th stand has rolled the strip top end portion
Rolling force at the time when the i-th stand has rolled the strip stabilized portion
Mill constant of the i-th stand
Roll speed at the time when the seventh stand has rolled the strip stabilized
Roll speed set value at the time when the seventh stand has rolled the strip top end
Delivery side thickness of the seventh stand
Rolling position at the time when the seventh stand has rolled the strip top end
Rolling position at the time when the seventh stand has rolled the strip stabilized
portion
P7.act-tq: Rolling force at the time when the seventh stand has rolled the strip top end
portion
15 P7,actstab: Rolling force at the time when the seventh stand has rolled the strip stabilized
portion
M7: Mill constant of the seventh stand
That is, the correction value to correct the roll speed calculated by the setup unit
can be calculated from the roll speed, rolling force, and rolling position at the time when the top
20 end of the strip which was rolled last time has been rolled and from the roll speed, rolling force,
and rolling position after the rolling of the strip reached the stabilized state. Or, a method
whereby the calculation is performed as shown by the following equation (25) in order to
simplify the calculation is also considered.
CG = (Vi.tq-,stmiset) . (V7.setN7.top-est )
25 = (Vi.act - stadVi.set) hi/((hi + Si.acLtop - Si.act-stab + Pi.acLtop - Pi.act_stab)/Mi) . . . (25)
The speed correction value calculating unit 101 0 calculates a correction amount
of the speed instruction every rolling stand by such a calculation. A speed instruction
correction amount a7 of F7 (final rolling stand) is equal to 0 since this stand is a rolling stand
serving as a start point of the speed instruction. The speed correction value calculating unit
30 1010 discriminates whether or not the calculation of the speed correction amount has been
finished with respect to all of the rolling stands (S1404). If it is not finished (NO in S1404), the
process from S 1401 is repeated. If the calculation of the speed correction amount has been
finished with respect to all of the rolling stands (YES in S1404), the process is finished.
Fig. 16 shows a process which is executed by the speed instruction balancing unit
121. The speed instruction balancing unit 121 fetches the speed instruction correction amount
of each rolling stand outputted from the speed instruction correcting unit 120. If the rolling
stand in which the correction amount exceeding the upperllower limits has been calculated
exists, the speed instruction balancing unit 12 1 execute a process for restricting the correction
amount to a value within the limits and, subsequently, balancing the correction amounts of other
rolling stands. As shown in Fig. 16, the speed instruction balancing unit 121 discriminates
whether or not the rolling stand in which the speed instruction correction amount exceeds the
upperllower limits exists (S 160 1).
If the rolling stand in which the correction amount exceeds the upperllower limits
does not exist (NO in S 1601), the speed instruction balancing unit 121 finishes the process. If
the rolling stand exceeding the upperllower limits exists (YES in S 160 I), the speed instruction
balancing unit 12 1 executes a process for restricting the speed instruction correction amount of
such a rolling stand to a value within the upperllower limits in S1602 and subsequent steps.
First, the speed instruction balancing unit 121 specifies the rolling stand in which an absolute
value of the speed instruction correction amount is maximum, divides an upperllower limit value
a~ of the speed instruction correction amount by the maximum value of the absolute value of the
speed instruction correction amount as shown by the following equation (26), and calculates a
speed correction balance amount ao (S 1602).
ao = a r l l k l . . . (26)
where,
ao: Speed correction balance amount
a ~ : Upperllower limit value of speed correction balance amount
~ X : Maximum value of absolute value of the speed correction amount
Subsequently, the speed instruction balancing unit 121 calculates a correction
amount after the balance by multiplying the correction amount of each rolling stand by ao as
shown by the following equation (27) (S 1603).
ai-b = 0 ao' ai . . . (27)
where,
U,-I,: Speed correction amount after the balance
Fig. 17 schematically shows contents of the process of the speed instruction
balancing unit 121. In the diagram, an upper limit 1703 and a lower limit 1704 are provided for
the speed correction amount so as to have a width of a=. By a correction amount 1701 before
the balance, the speed instruction correction amount of the first stand (Fl) becomes maximum
and exceeds a value of the upper limit 1703 together with the speed instruction correction
amount of the second stand (F2). The speed correction balance amount Q is obtained by
dividing a~ as an upperllower limit value by a,,. A correction amount 1702 after the balance
(black circle in the diagram) is obtained by dividing the speed correction amount before the
balance (white circle in the diagram) by the speed correction balance amount Q.
The rolling position control unit 130 corrects a rolling position instruction
received from the setup unit 10 1 by reflecting a change in actual value of the rolling force and a
difference between the actual thickness detected by the multigauge 164 and the target thickness
and outputs a value after the correction to the controlled object 150. The control of the rolling
position is called AGC (Automatic Gauge Control) and various methods such as Bisra AGC,
Monitor AGC, Gauge meter AGC, and the like have been known. When the rolling position
changes, the values of the mass-flow of the entry side strip and the delivery side strip change.
In order to compensate it, the roll speed of the stand in which the rolling position changed and
the roll speed of the upstream stand when seen from such a stand are changed.
The speed control unit 122 sets the value obtained by adding the speed correction
amount outputted by the rolling position control unit 130 to the speed instruction outputted by
the speed instruction balancing unit 121 into an instruction value and makes the speed control of
the workroll 162. A speed control system is constructed by a control system of proportion and
integration generally called ASR (Automatic Speed Control).
Although the absolute values of the upper limit value and the lower limit value of
the speed instruction correction amount have been set to the same value in the embodiment, even
if they are different values, by defining b, by a ratio between ai and the upperllower limit
value, the process can be executed by a similar idea. Such a construction that the speed
instruction balancing unit 121 is omitted and the speed control unit 122 operates in accordance
with the speed instruction outputted by the speed instruction correcting unit 120 is also
considered.
Although the data of the stabilized portion has been extracted by paying an
attention to the rolled length in the embodiment, it is also possible to construct in such a manner
that the values of the rolling position, rolling force, and roll speed are directly used, when they
do not change by a predetermined amount or more, it is determined that the rolling is stable, and
such a case is used as a condition for extracting the stabilized data.
Further, although the setup unit 101 has started the calculation from the draft
schedule and calculated the rolling force, rolling position, and roll speed in Fig. 2, a method
whereby the calculation is started from a force balance is also known. The invention can be
also similarly applied to such a case.
Although the peripheral speed of the workroll 162 has been set to the correction
target of the speed instruction in the invention, even to a correction target such as rotational
speed of a main motor for driving the workroll, speed instruction of a main drive, or the like, the
invention can be also realized by an equivalent process.
5 The control apparatus 100 described in Fig. 1 is realized by a combination of
software and hardware. The hardware to realize the fbnctions of the control apparatus 100
according to the embodiment will be described with reference to Fig. 18. Fig. 18 is a block
diagram showing a hardware construction of an information processing apparatus constructing
the control apparatus 100 according to the embodiment. As shown in Fig. 18, the control
10 apparatus 100 according to the embodiment has a construction similar to that of a general
information processing terminal such as server, PC (Personal Computer), or the like.
That is, in the control apparatus 100 according to the embodiment, a CPU
(Central Processing Unit) 10, a RAM (Random Access Memory) 20, a ROM (Read Only
Memory) 30, an HDD (Hard Disk Drive) 40, and an interface (W) 55 are connected through a
15 bus 80. An LCD (Liquid Crystal Display) 60 and an operation unit 70 are connected to the T/F
55.
The CPU 10 is an arithmetic operating unit for controlling the whole operation of
the control apparatus 100. The RAM 20 is a volatile storage medium idfrom which
information can be read and written at a high speed. The RAM 20 is used as a work area when
20 the CPU 10 processes information. The ROM 30 is a read only nonvolatile storage medium.
A program such as firmware or the like has been stored in the ROM 30.
The HDD 40 is a nonvolatile storage medium idfrom which information can be
read and written. An OS (Operating System), various kinds of control programs, application .
programs, and the like have been stored in the HDD 40. The I/F 55 connects the bus 80 to
25 various kinds of hardware, a network, and the like and controls them. The I/F 55 is also used as
an interface for allowing respective apparatuses to transmit and receive information or to input
information to the rolling mill.
The LCD 60 is a visual user interface for allowing the operator to confirm the
state of the control apparatus 100. The operation unit 70 is a user interface such as keyboard,
30 mouse, or the like for allowing the operator to input information to the control apparatus 100.
In such a hardware construction, a program stored in the ROM 30, HDD 40, or a recording
medium such as an optical disk (not shown) or the like is read out and stored into the RAM 20
and the CPU 10 executes an arithmetic operation in accordance with the program, so that a
software control unit is constructed. By a combination of the software control unit constructed
in this manner and hardware, the fbnctions of the control apparatus 100 according to the
embodiment are realized.
In the foregoing embodiment, the case where all of the hnctions are contained in
one information processing apparatus has been described as an example. In this manner, all of
5 the fbnctions may be realized in one information processing apparatus or the fbnctions may be
distributed to a larger number of information processing apparatuses and realized.
It should be hrther understood by those skilled in the art that although the
foregoing description has been made on embodiments of the invention, the invention is not
limited thereto and various changes and modifications may be made without departing from the
10 spirit of the invention and the scope of the appended claims.

- 27 -
CLAIMS:
1. A rolling control apparatus for controlling a tandem rolling mill which rolls a strip
(1 57) by a plurality of roll pairs (16 1 : F 1 - F7), comprising:
a delivery side thickness obtaining unit (1 13) for obtaining a result of a thickness
measurement which is performed by a thickness meter (164) arranged on a delivery side of the
roll pair (F7) arranged at a final stage of rolling order among the plurality of roll pairs;
a thickness calculating unit (1 13) for calculating a thickness on an entry side of
the roll pair on the basis of a thickness on the delivery side of the roll pair in accordance with
such a rule that a product of a conveying speed and the thickness of the strip which is inserted
into the roll pair and a product of a conveying speed and the thickness of the strip which is fed
out fiom the roll pair are constant; and
an error compensating unit (1 13) for compensating an error of a calculation result
of the entry side thickness of each roll pair within a range fiom the roll pair (F2) arranged just
after the head roll pair (Fl) in the rolling order among the plurality of roll pairs to the roll pair
(F7) arranged at the final stage,
wherein, the thickness calculating unit calculates the entry side thickness of the
roll pair (F7) arranged at the final stage on the basis of the obtained thickness measurement
result, uses a calculation result as a thickness of the strip which is fed out from the roll pair (F6)
arranged just before the roll pair (F7), and repeats the calculation according to the rule, thereby
calculating an entry side thickness of the roll pair 0;l) arranged at the head,
I the error compensating unit calculates an error between the entry side thickness of
I
I the roll pair (Fl) arranged at the head which was calculated by repeating the calculation
I
I according to the rule and an entry side thickness of the roll pair (Fl) arranged at the head which
I
was obtained by a different method and compensates the error of the calculation result of the
I entry side thickness of each roll pair on the basis of the calculated error.
2. The apparatus according to claim 1, wherein
on the basis of a ratio of the entry side thickness of the roll pair as a correction
target to the entry side thickness of the roll pair (Fl) arranged at the head which was calculated
I
by repeating the calculation according to the rule, the error compensating unit (1 13) determines a
value which is applied to correct the calculation result of the entry side thickness of each roll pair
in the calculated error.
3. The apparatus according to claim 2, wherein
the error compensating unit (1 13) sets an amount according to the ratio of the
entry side thickness of the roll pair as a correction target to the entry side thickness of the roll
repeatini7he calculation according to the
rule in an amount of the calculated error into the value which is applied to correct the calculation
result of the entry side thickness of each roll pair.
4. The apparatus according to claim 1, wherein
the error compensating unit (1 13) distributes the calculated error to the calculation
result of the entry side thickness of each roll pair, thereby compensating the error of the
calculation result of the entry side thickness of each roll pair.
5. The apparatus according to claim 1, wherein
the error compensating unit (1 13) determines a correction amount of the
calculation result of the entry side thickness of each roll pair based on the calculated error in
accordance with a distribution of a rolling amount to the plurality of roll pairs (161: F1 - F7).
6. The apparatus according to claim 1, wherein
the error compensating unit (1 13) calculates an error between a thickness of a
rolling result in a rough rolling process for rolling the strip (1 57) prior to the rolling by the
plurality of roll pairs (161: F1 - F7) and the entry side thickness of the roll pair (Fl) arranged at
the head which was calculated by repeating the calculation according to the rule.
7. The apparatus according to claim 6, hrther comprising
a rough rolling result obtaining unit (1 12) for obtaining a rolling result in the
rough rolling process, and wherein
the rough rolling result obtaining unit operates in such a manner that:
in the rolling process just before the strip (157) is inserted into the plurality of roll
pairs (161: F1 - F7), that is, in the final rough rolling process for conveying once a portion in a
range from a top end to a tail end of the strip to the role pair for rough rolling which is used for
the rough rolling process, start timing when the strip has been inserted to the role pair for rough
rolling and the rolling has been started is obtained;
in the final rough rolling process, arrival timing when the strip fed out ftom the
role pair for rough rolling has reached a predetermined conveying position is obtained;
by integrating a peripheral speed as a speed of a rolling surface of the role pair for
rough rolling for a period of time from the start timing to the arrival timing, a predetermined
interval rough rolled length serving as a length in which the role pair for rough rolling performed
the rolling for a period of time during which, in the final rough rolling process, the strip is
conveyed from the role pair for rough rolling to the predetermined conveying position is
calculated;
a forward slip ratio in the final rough rolling process is calculated on the basis of a
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ratio between an interval from the position of the role pair for rough rolling to the predetermined
conveying position and the predetermined interval rough rolled length;
completion timing when a tail end of the strip has been rolled by the role pair for
rough rolling and the rolling has been completed in the final rough rolling process is obtained;
by integrating the peripheral speed as a speed of the rolling surface of the role pair
for rough rolling for a period of time from the start timing to the completion timing, a whole
length in which the role pair for rough rolling performed the rolling in the final rough rolling
process is calculated;
a whole length after the rough rolling as a whole length of the strip rolled by the
rough rolling process is calculated on the basis of the calculated whole length and the forward
slip ratio; and
a thickness of the strip rolled by the rough rolling process is calculated on the
basis of dimensions of the strip before it is subjected to the rough rolling process and the
calculated whole length after the rough rolling,
and wherein the error compensating unit (1 13) uses the calculated thickness of the
strip rolled by the rough rolling process as a thickness of a rolling result in the rough rolling
process and calculates the error.
8. The apparatus according to claim 7, wherein:
the rough rolling process is a process for rolling the strip (1 57) by repetitively
inserting the strip to the roll pair which is used in the rough rolling process; and
the final rough rolling process is an end of the repetition of the insertion of the
strip to the roll pair which is used in the rough rolling process.
9. The apparatus according to claim 1, hrther comprising
a rolling force calculating unit (1 14) for calculating an estimation value of a
rolling force to the roll pair on the basis of the corrected entry side thickness of the roll pair and a
calculation result of the delivery side thickness, and wherein
the rolling force calculating unit corrects a calculating expression of the
estimation value of the rolling force by the rolling force calculating unit on the basis of a
difference between the calculated estimation value of the rolling force and an actual value of the
rolling force in the roll pair.
10. A rolling control method of controlling a tandem rolling mill which rolls a strip
(157) by a plurality of roll pairs (161: F1 - F7), comprising the steps of
obtaining a result of a thickness measurement which is performed by a thickness
meter (164) arranged on a delivery side of the roll pair (F7) arranged at a final stage of rolling
(d-. knx7AcaT~P' k1: b j - i ~
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order among the plurality of roll pairs;
calculating a thickness on an entry side of the roll pair on the basis of a thickness
on the delivery side of the roll pair in accordance with such a rule that a product of a conveying
speed and the thickness of the strip which is inserted into the roll pair and a product of a
conveying speed and the thickness of the strip which is fed out from the roll pair are constant;
and
using a calculation result of the entry side thickness of the roll pair as a thickness
of the strip which is fed out from the roll pair arranged just before the roll pair and repeating the
calculation according to the rule, thereby calculating an entry side thickness of the roll pair (Fl)
arranged at a head;
calculating an error between the entry side thickness of the roll pair (Fl) arranged
at the head which was calculated by repeating the calculation according to the rule and an entry
side thickness of the roll pair (Fl) arranged at the head which was obtained by a different
method; and
compensating an error of a calculation result of the entry side thickness of each
roll pair within a range from the roll pair (F2) arranged just after the head roll pair (Fl) in the
rolling order among the plurality of roll pairs to the roll pair (F7) arranged at the final stage on
the basis of the calculated error.
11. A rolling control program for controlling a tandem rolling mill which rolls a strip
(1 57) by a plurality of roll pairs (161 : F1 - F7), wherein the program allows an information
processing apparatus to execute the steps of
obtaining a result of a thickness measurement which is performed by a thickness
meter (164) arranged on a delivery side of the roll pair (F7) arranged at a final stage of rolling
order among the plurality of roll pairs;
calculating a thickness on an entry side of the roll pair on the basis of a thickness
on the delivery side of the roll pair in accordance with such a rule that a product of a conveying
speed and the thickness of the strip which is inserted into the roll pair and a product of a
conveying speed and the thickness of the strip which is fed out from the roll pair are constant;
and
using a calculation result of the entry side thickness of the roll pair as a thickness
of the strip which is fed out from the roll pair arranged just before the roll pair and repeating the
calculation according to the rule, thereby calculating an entry side thickness of the roll pair (Fl)
arranged at a head;
calculating an error between the entry side thickness of the roll pair (Fl) arranged
- q ~ l p @ - L 2 4 OEC 2013 ~ 6 9 2 4 &I
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- 31 -
at the head which was calculated by repeating the calculatio
side thickness of the roll pair (Fl) arranged at the head which was obtained by a different
method; and
compensating an error of a calculation result of the entry side thickness of each
roll pair within a range from the roll pair (F2) arranged just after the head roll pair (Fl) in the
rolling order among the plurality of roll pairs to the roll pair (F7) arranged at the final stage on
the basis of the calculated error.
12. A rolling control apparatus, substantially as herein described with reference to
accompanying drawings and examples.
13. A rolling control method, substantially as herein described with reference to
accompanying drawings and examples.
14. A rolling control program, substantially as herein described with reference to
accompanying drawings and examples. n
Dated this 24th day of December 2013
Agent for the Applicant