US3603124A - Computer control system for rolling metal strips using feed-forward and prediction - Google Patents

Computer control system for rolling metal strips using feed-forward and prediction Download PDF

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Publication number
US3603124A
US3603124A US822433A US3603124DA US3603124A US 3603124 A US3603124 A US 3603124A US 822433 A US822433 A US 822433A US 3603124D A US3603124D A US 3603124DA US 3603124 A US3603124 A US 3603124A
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United States
Prior art keywords
stand
rolling
alteration
roll
change
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Expired - Lifetime
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US822433A
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English (en)
Inventor
Tohru Arimura
Masamoto Kamata
Morio Saito
Terumi Okamoto
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JFE Engineering Corp
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Nippon Kokan Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/16—Control of thickness, width, diameter or other transverse dimensions
    • B21B37/24—Automatic variation of thickness according to a predetermined programme
    • B21B37/26—Automatic variation of thickness according to a predetermined programme for obtaining one strip having successive lengths of different constant thickness

Definitions

  • FIG. 7 Ah5 OJmm 61 d2 63 6.4 6.5 d6 of? 0 8 0 9 lb sec Lb I [5 I A PATENTEU SEP 7 WI sum 0? HF 1 mQI PATENTED SEP 7 ISTI sum 09 0F 11 PATENTED SEP 7 I97! SHEET 10 CF 11 PATENTED SEP 7 12m SHEET 11 HF 11 COMPUTER CONTROL SYSTEM FOR ROLLING METAL STRIPS USING FEED-FORWARD AND PREDICTION
  • This invention relates to a control system for rolling metal and more particularly for rolling thin metal strips wherein altering the thickness of the strip during the rolling operation is achieved freely and safely.
  • An object of the present invention is to provide a control system where it is possible to freely and stably alter the strip size, particularly the thickness, without adversely affecting the production line.
  • Another object of the present invention is to provide a control system where it is possible to produce a continuous rolling coil having a precise thickness, even when the pass schedule is altered at will during the rolling operation.
  • a further object of this invention is to provide a control system where it is possible to completely utilize the prior AGC system.
  • a still further object of this invention is to provide a control system where it is possible to use the largest slabs or coils at all times if it is within the capacity of the employed mill without giving any consideration to said size changes.
  • FIG. 1 shows a block diagram of a prior art control system in an ordinary tandem cold-reducing mill
  • FIG. 2 shows diagrams illustrating the variation with outgoing thickness and forward tension of each stand in FIG. 1 under uncontrolled conditions
  • FIG. 3 shows the control pattern of rolling speed at the first stand
  • FIG. 4 shows the control pattern of rolling speed at the second stand
  • FIG. 5 shows the control pattern of rolling speed at the third stand
  • FIG. 6 shows the control pattern of rolling speed at the fourth stand
  • F IG. 7 shows the control pattern of rolling speed at the fifth stand
  • FIG. 8 shows the control pattern of rolling speed at all stands
  • FIG. 9 shows a block diagram of a program control system according to this invention.
  • FIG. I is a block diagram of an embodiment of the present invention using an interstand tension meter
  • FIG. 11 is a block diagram of an embodiment of the present invention using an interstand thickness meter.
  • FIG. 12 is a block diagram of an embodiment of the present invention using a mixed control system.
  • a metal strip is uncoiled by uncoiler l and is rolled through the first rolling stand 2, the second stand 3, the third stand 4, the fourth stand and the fifth stand 6. It is then coiled on tension reel 7.
  • the relationship between roll opening and peripheral speed of said roll obeys the flow-constant law wherein the product of outgoing thickness of the strip the rolling speed is constant. Both the thickness and the speed at each stand are determined by the flow-constant law.
  • the rolls are driven by the above-mentioned Ward-Leonard system and is controlled by means of speed regulators 56, 55, 54, 53 and S1 accompanied by a set of Motor-Generator systems 37-38, 40-41, 43-44, 46-47 and 49-50 respectively.
  • the rotational speeds of the motors 37, 40, 43, 46 and 49 are respectively detected by rotation meters 36, 39, 42, 45 and 48, and the appropriate feedback signal is sent to the above speed regulators.
  • This AGC system usually consists of two kinds of local feedback devices.
  • One of said feedback devices is for the first stand, for making the roll opening change in accordance with the deviation Ahl of the outgoing strip thickness, which is detected by an X-ray thickness meter, from the predetermined thickness.
  • a signal which is proportional to the rotational speed of motor 21, detected by rotation meter 23 and the other signal from the above thickness meter are fed back together into the screw down autocontrol device 19 so that the optimum reduction rate is easily obtained. While this is a rough control for obtaining the required thickness, a precise control is provided at the final stand, the fifth stand in FIG. 1.
  • Both the signal, which is the deviation A from the predetermined thickness, detected by an X-ray thickness meter 9 and the other signal, which is a function of the rotational speed of the motor 49, are together fed back into the rolling speed regulator 51. In this case, the signal fed back is transmitted through the automatic tension regulator 52. While the Motor-Generator system 49-50 is so adjusted that the tension between No. 4 and No. 5 stands is changed and the above deviation Ah 5 becomes zero, sufficient accuracy of finished thickness is easily obtained.
  • Tension meters 10, ll, 12 and I3 shown in FIG. 1 indicate the interstand tension and the tension is kept to a suitable value in accordance with the rolling resistance and force of the strip. If the tension value is too high, the strip will be broken. 0n the other hand, if the tension is too low, the strip may be folded due to looping of the strip. Consequently, it is possible that a roll will be broken by instantaneously striking the folded strip. Even if the strip passes through the rolling mill, it is impossible to produce a strip having the required thickness.
  • the altering pattern of the roll peripheral speed for each of stands must be measured and utilized for control.
  • Each of stands has a different altering pattern in accordance with the mill facilities employed. Accordingly, when an altering order of strip size is computed on the basis of said altering pattern respectively, the size change is immediately dealt with and a fluctuation in the interstand tension is simultaneously compensated for. Then, the normal rolling operation is easily effected.
  • the most important feature of the present invention lies in the details of the dynamic manner in which the conditions of each mill stand actually employed are measured, and in the manner in which a suitable computer memory is used for alter ing the pattern of the roll peripheral speed. That is, the roll peripheral speed, which is altered in response to the adjustment of roll opening brought about by a gauge alteration in rolling, must be altered without fail.
  • the interstand tension is kept constant and the rolling operation is stably carried out.
  • V is the roll peripheral speed
  • i is the stand number
  • I1 is the outgoing thickness of the ith stand
  • T is the time (seconds) which strip is transferred from the ith stand to the i-Hth stand; and A,, B,, C, and D, are constants decided by the incoming thickness, outgoing thickness and tension, material properties, type of lubricant, rolling speed and construction of the rolling mill.
  • FIG. 2 shows that the alteration of the tension between No. 2 and No. 3 stands and between No. 4 and No. 5 stands is larger. concretely speaking, the preset value of interstand tension, which is [5.4 kg./mm. between No. 2 and N0, 3 stands and l4.l kgjmm. between No. 4 and No.
  • FIG. 8 shows a typical control pattern employed in the above example.
  • the abscissa represents the time (seconds) and the ordinate represents the rate of alteration of the roll peripheral speed when the outgoing thickness of each stand is altered by a unit amount (0.l mm.
  • An amount of alteration of said roll peripheral speed at each stand corresponding to the amount of alteration of roll opening as shown in table II is adjusted based on the control pattern of FIG. 8.
  • FIGS. 3, 4, 5, 6 and 7 show an actual alteration pattern of the roll peripheral speed concerned with the above Tables I and II.
  • the abovementioned pattern provides completely predicted control, ie a feed-forward system, and it is possible to easily prevent the interstand tension from changing. It will be understood that an online computer is necessary in order to realize the above system.
  • a gauge alteration in rolling is required, first the command for altering the roll opening is issued from said computer, which is computed on the ground of the memorized control pattern.
  • Another command for altering the roll peripheral speed is issued so that the interstand tension is stably and continuously kept constant. It is an important fea ture of this invention that such alteration commands are given to the next succeeding stand in order, before the strip reaches said next succeeding stand.
  • FIG. 9 a program control system is recommended. This system is very effective for any rolling speed and a block diagram thereof is shown in FIG. 9 by way of example.
  • the mechanism of FIG. 9 is made up of a command device 76 concerned with gauge alteration, online computer 75 and signal converter 77, which is additionally provided with the facilities of FIG. 1.
  • the computer 75 given a command of gauge alteration, first calculates a new pass schedule and determines the required altering amount of roll opening and of roll peripheral speed. After such calculated values are converted into analog values by converter 77, the former signal is transmitted to the roll-opening regulators 19, 24, 27, 30 and 33 and the latter signal to roll peripheral speed regulators 56, 55, 54, 53 and 51, respectively.
  • Each of the above command signals is applied to an ordinary AGC system, e.g. as shown in FIG. I.
  • the forecasting control as mentioned above can make the interstand tension always constant without a breakage of the strip or damage to the rolls.
  • Such a feed-foreward control system was extremely effective for not only gauge altering in rolling, but also for use with welded coils having different thicknesses.
  • FIG. shows another example of the present invention.
  • the mechanism of FIG. 10 is characterized by positive utilization of ordinary interstand tension meters 10, ll, 12 and I3 as shown in FIG. I.
  • the response of the control system which utilizes such tension meters is inferior to that of the program control system of FIG. 9.
  • the above system if applied to cases where the rolling speed is comparatively slow, is able to exhibit sufficient effects.
  • a change of interstand tension does not occur independently.
  • the change is subject to the roll peripheral speed in front and in the rear of said tension meters, outgoing thickness of strip and rear stand tension. Accordingly, the basic computation expression of the above process becomes a formula that is a variant of said equation I.
  • Ah is the reduction alteration amount in the ith stand
  • AV is the alteration amount of the roll peripheral in the ith stand
  • A', B',, C',,,, D,, E, and F', are constants determined by rolling conditions as mentioned in connection with equa tion I.
  • This equation 3 becomes the control pattern memorized within the online computer in place of that of equation I.
  • a command for gauge alteration is given to the system of FIG. 10, a change of Ah, is automatically determined.
  • an altering value of the front stand tension meters 10, 11, I2 and I3 to the converter 77 and simultaneously a value of roll peripheral speed is transmitted from each rollrotating meter 36, 39, 42, 45 and 48 to the converter 77.
  • This signal is converted into a digital value and is transmitted to the computer 75.
  • an altering amount of the roll peripheral is obtainedv
  • the required altering value is converted into an analog value and this value is fed-forwarded to the roll peripheral speed regulators 56, 55, 54, 53 and 52 respectively.
  • the gauge alteration in rolling may be detected by a thickness meter arranged at the delivery side of each stand. It is well known that an X-ray gauge may be employed as such a thickness meter.
  • FIG. 11 is an example of the above process. when such a thickness meter is used, the gauge alteration con trol is possible to be brought to practice by the altering pattern of the roll peripheral speed in accordance with equation I.
  • the outgoing strip thickness at each stand is directly measured by X-ray gauges 8, 57, 58. 59 and 9 and simultaneously the roll peripheral speed is measured by rotating meters 36, 39, 42, 45 and 48 respectively.
  • the obtained values are transmitted to computer 75 through converter 77 and the required alterations are computed.
  • the computed values are fed-forward to next stand in order. While such a control system has slower responsiveness than that of the above program control system, there is still sufiicient possibility of stable gauge alteration for rolling mills having a lower rolling speed.
  • FIG. 12 shows a control system wherein an ordinary rolling force meter is employed.
  • the rolling force detected by each load-cell 60, 61, 62, 63 and 64 and an output signal of each roll-rotating meter 36, 39, 42, 45 and 48 is transmitted to the computer '75.
  • W. C. F. Hessenbergs works, that the relationship between the amount of alteration of strip thickness and that of rolling force is exhibited as follows:
  • Ah is the amount of alteration of thickness
  • AS is the moving amount of the screwdown
  • AP is the amount of alteration of rolling force
  • AM is the mill spring value.
  • control system i.e. program, tension meter, thickness meter and rolling force meter
  • program tension meter
  • thickness meter i.e. program, tension meter, thickness meter and rolling force meter
  • These systems can be independently employed. It is, however, true that there is some limit in their application. That is, according to many experiments, the system of FIG. 12 was unable to deal with an alteration of the interstand tension based on other causes except with the command of the gauge alteration by the computer in rolling. It is, on the other hand, confirmed that each system of FIGS. 10, II and 12 has an ability of dealing with the above alteration. By contrast, the responsiveness of these systems is inferior to that of the system of FIG. 9. Accordingly, combinations of suitable systems from the above-mentioned systems are recommended as an actual control process.
  • FIG. 13 is an example of such a combination system.
  • This combination includes the program control system of FIG. 9, the interstand tension meter system of FIG. 10, and the rolling force meter system of FIG. 12.
  • the main part of the combination system in FIG. I3 is the program control system having an alteration pattern concerned with roll peripheral speed.
  • the alteration pattern of roll peripheral speed must be based on the following equation 5, besides the above-mentioned pattern concerned with equation I (FIG. 9).
  • Ah is the alteration error of thickness based on other causes except a normal alteration command.
  • the alteration pattern is comparatively simple. Accordingly, it is not necessary to be transmitted to the online computer 75.
  • minor loop devices having amplifiers 65, 66. 67, 68, 69, 70 and 7I are used, a fine alteration of the interstand tension is compensated with ease. And furthermore, the responsiveness of such minor loop devices is higher than that of the online computer system of FIG. 10.
  • the combination system as shown in FIG. 13 has excellent merits in that the faults of the basic control systems are eliminated and the advantages thereof are utilized. Such combination systems may be freely selected from the above four systems in consideration of mill conditions actually employed.
  • the gauge alteration processes of the present invention are effective to not only cold tandem mills. but also to reversing mills or to continuous hot-rolling mills.
  • a method of maintaining the interstand tension constant by predicting and automatically controlling the amount of gauge alteration at each stand during a rolling operation comprising:
  • a method as set forth in claim 1 wherein said change in the roll opening is detected by measuring interstand tension with an interstand tension meter 4.
  • a method as set forth in claim 1 wherein said change in roll opening is detected by measuring the thickness of the strip with a thickness meter at the delivery side ofa rolling stand.
  • a method as set forth in claim 1 wherein said change in roll opening is detected by the combination of a predetermined fixed program, measuring interstand tension. and measuring rolling force at a stand.

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  • Mechanical Engineering (AREA)
  • Control Of Metal Rolling (AREA)
US822433A 1968-05-09 1969-05-07 Computer control system for rolling metal strips using feed-forward and prediction Expired - Lifetime US3603124A (en)

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US (1) US3603124A (enrdf_load_stackoverflow)
AT (1) AT294256B (enrdf_load_stackoverflow)
BE (1) BE732832A (enrdf_load_stackoverflow)
CA (1) CA920692A (enrdf_load_stackoverflow)
DE (1) DE1923788A1 (enrdf_load_stackoverflow)
FR (1) FR2008166A1 (enrdf_load_stackoverflow)
GB (1) GB1269267A (enrdf_load_stackoverflow)
NL (1) NL157817B (enrdf_load_stackoverflow)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3722244A (en) * 1970-03-07 1973-03-27 Nippon Kokan Kk Method of controlling continuous rolling of metal strips
US3727441A (en) * 1970-03-16 1973-04-17 Hitachi Ltd Thickness control apparatus for rolling mill
US3750437A (en) * 1970-03-07 1973-08-07 Nippon Kk Method and apparatus for controlling continuous tandem rolling mills
US3760621A (en) * 1970-08-26 1973-09-25 Nippon Kokan Kk Control method of tension in rolling mills (1)
US3762195A (en) * 1970-03-09 1973-10-02 Hitachi Ltd Thickness control apparatus for rolling mill
US3766762A (en) * 1970-08-29 1973-10-23 Nippon Kokan Kk Control method of tension in rolling mills (2)
US3786661A (en) * 1972-04-12 1974-01-22 Reynolds Metals Co Rolling mill control system
US3807206A (en) * 1972-09-29 1974-04-30 J Connors Strip gage change during rolling in a tanden rolling mill
EP1010478A4 (en) * 1997-09-05 2002-02-06 Kawasaki Steel Co METHOD FOR CHANGING THE THICKNESS OF A SHEET THROUGH A TANDEM COLD ROLLING MILL
CN114453427A (zh) * 2022-01-06 2022-05-10 首钢京唐钢铁联合有限责任公司 一种平辊可逆板带轧机控制方法、装置及计算机设备
CN114929463A (zh) * 2020-01-09 2022-08-19 松下知识产权经营株式会社 辊压装置以及控制装置

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6010810B2 (ja) * 1975-08-25 1985-03-20 株式会社日立製作所 圧延機の板厚制御方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3036480A (en) * 1957-07-10 1962-05-29 Electron Machine Corp Automatic control of multi-stand rolling mills
US3169421A (en) * 1960-10-24 1965-02-16 Allis Chalmers Mfg Co Automatic gauge control
US3174317A (en) * 1961-09-29 1965-03-23 United States Steel Corp Gage-control system for strip mill
US3186201A (en) * 1961-06-21 1965-06-01 Steelworks Automation Ltd Production of metal strip
US3212310A (en) * 1962-05-31 1965-10-19 Armco Steel Corp Automatic gauge and tension control system
US3332263A (en) * 1963-12-10 1967-07-25 Gen Electric Computer control system for metals rolling mill
US3457747A (en) * 1965-12-28 1969-07-29 British Iron Steel Research Rolling mills
US3508425A (en) * 1968-03-07 1970-04-28 Gen Electric Tension limit modification control

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3036480A (en) * 1957-07-10 1962-05-29 Electron Machine Corp Automatic control of multi-stand rolling mills
US3169421A (en) * 1960-10-24 1965-02-16 Allis Chalmers Mfg Co Automatic gauge control
US3186201A (en) * 1961-06-21 1965-06-01 Steelworks Automation Ltd Production of metal strip
US3174317A (en) * 1961-09-29 1965-03-23 United States Steel Corp Gage-control system for strip mill
US3212310A (en) * 1962-05-31 1965-10-19 Armco Steel Corp Automatic gauge and tension control system
US3332263A (en) * 1963-12-10 1967-07-25 Gen Electric Computer control system for metals rolling mill
US3457747A (en) * 1965-12-28 1969-07-29 British Iron Steel Research Rolling mills
US3508425A (en) * 1968-03-07 1970-04-28 Gen Electric Tension limit modification control

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3722244A (en) * 1970-03-07 1973-03-27 Nippon Kokan Kk Method of controlling continuous rolling of metal strips
US3750437A (en) * 1970-03-07 1973-08-07 Nippon Kk Method and apparatus for controlling continuous tandem rolling mills
US3762195A (en) * 1970-03-09 1973-10-02 Hitachi Ltd Thickness control apparatus for rolling mill
US3727441A (en) * 1970-03-16 1973-04-17 Hitachi Ltd Thickness control apparatus for rolling mill
US3760621A (en) * 1970-08-26 1973-09-25 Nippon Kokan Kk Control method of tension in rolling mills (1)
US3766762A (en) * 1970-08-29 1973-10-23 Nippon Kokan Kk Control method of tension in rolling mills (2)
US3786661A (en) * 1972-04-12 1974-01-22 Reynolds Metals Co Rolling mill control system
US3807206A (en) * 1972-09-29 1974-04-30 J Connors Strip gage change during rolling in a tanden rolling mill
EP1010478A4 (en) * 1997-09-05 2002-02-06 Kawasaki Steel Co METHOD FOR CHANGING THE THICKNESS OF A SHEET THROUGH A TANDEM COLD ROLLING MILL
CN114929463A (zh) * 2020-01-09 2022-08-19 松下知识产权经营株式会社 辊压装置以及控制装置
CN114453427A (zh) * 2022-01-06 2022-05-10 首钢京唐钢铁联合有限责任公司 一种平辊可逆板带轧机控制方法、装置及计算机设备
CN114453427B (zh) * 2022-01-06 2024-02-09 首钢京唐钢铁联合有限责任公司 一种平辊可逆板带轧机控制方法、装置及计算机设备

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Publication number Publication date
FR2008166A1 (enrdf_load_stackoverflow) 1970-01-16
NL6907101A (enrdf_load_stackoverflow) 1969-11-11
CA920692A (en) 1973-02-06
AT294256B (de) 1971-11-10
DE1923788A1 (de) 1970-06-11
NL157817B (nl) 1978-09-15
BE732832A (enrdf_load_stackoverflow) 1969-10-16
GB1269267A (en) 1972-04-06

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