US3636743A - Rolling mill control system - Google Patents

Rolling mill control system Download PDF

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Publication number
US3636743A
US3636743A US46320A US3636743DA US3636743A US 3636743 A US3636743 A US 3636743A US 46320 A US46320 A US 46320A US 3636743D A US3636743D A US 3636743DA US 3636743 A US3636743 A US 3636743A
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United States
Prior art keywords
rolling mill
gage
proportional
signal
leaving
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Expired - Lifetime
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US46320A
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English (en)
Inventor
James B Murtland Jr
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Allegheny Ludlum Corp
Pittsburgh National Bank
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Allegheny Ludlum Industries Inc
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Assigned to ALLEGHENY LUDLUM CORPORATION reassignment ALLEGHENY LUDLUM CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). 8-4-86 Assignors: ALLEGHENY LUDLUM STEEL CORPORATION
Assigned to PITTSBURGH NATIONAL BANK reassignment PITTSBURGH NATIONAL BANK SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ALLEGHENY LUDLUM CORPORATION
Assigned to PITTSBURGH NATIONAL BANK reassignment PITTSBURGH NATIONAL BANK ASSIGNMENT OF ASSIGNORS INTEREST. RECORDED ON REEL 4855 FRAME 0400 Assignors: PITTSBURGH NATIONAL BANK
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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
    • B21B37/18—Automatic gauge control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B1/30—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a non-continuous process
    • B21B1/32—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a non-continuous process in reversing single stand mills, e.g. with intermediate storage reels for accumulating work

Definitions

  • MOTOR CONTROL 39 V I E 32 28 0 I 26 24 Q E? M IST INTER- A T0 0 A To 0 VAL coy v CONVERTER CONVERTER DELAY '53 44 40 f COMPUTE a 2d w 7 22? GATE z V2624 BY "1 OPERATOR 42 7a 62 v, REGISTER 68 v r r I V .SUBTRACTOR V/REG/S'TER INVENTOR.
  • Transport distances of 5 feet or more are common in many prior art rolling mill control systems, meaning that such systems are not capable of detecting an error until 5 feet of material has passed from the bite of the mill rolls.
  • the corrective signal is then transmitted to the mill screwdown; but the measuring gage does not detect the result of this action until 5 feet more of the material has passed through the mill.
  • a high gain system of this type a natural frequency of oscillation results; and if this oscillation is left to exist without any attempt to control it, the results are undesirable. That is, for material entering the mill with fairly noticeable changes in gage, the system described would cause wide variations in output gage and in all probability would eventually result in tearing of the ship.
  • gage control system based on the constant volume princi ple wherein the gage of the strip material is, in :efi'ect, measured directly at the bite of the rolls.
  • a gage control system is shown', for example, in U.S. Pat. No. 3,015,974 and copending application Ser. No. 723,121, filed Apr.- 22, 1968, now U.S. Pat. No. 3,564,882, both being assigned to the Assignee of the present application.
  • Control systems of this type are based on the concept that the volume, V,, of material coming out of the mill must be equal to the volume, V,, entering the mill.
  • the input gage, 6, is measured at a' point ahead of the roll bite each time the strip passes through an interval, such as one inch or less.
  • These gage measurements are advanced through a memory unit'such'as a shift register and are used to derive an error signal for the rolling mill screwdown when the gage fed into the computing circuitry is that of the strip which is then at the bite of the rolls. In this manner, the undesirable transport time and sensing time mentioned above are eliminated.
  • V,.and V are the entering and exit velocities of the strip material; respectively.
  • the error signal may be applied to either a rolling mill screwdown, a tension controlling device for the strip material.
  • FIG. 1 is a schematic diagram of one embodiment of the invention wherein actual input length is compared with calculated input length to derive an error signal;
  • FIG. 2 is a schematic illustration of another embodiment of the invention wherein actual input velocity of the strip material is compared with calculated input strip velocity to derive an error signal;
  • FIG. 3 is a schematic diagram of a further embodiment of the invention wherein actual output length of material leaving the rolling mill is compared with calculated output length of material leaving the rolling mill;
  • FIG. 4 is a schematic illustration of still another embodiment of the invention wherein actual output velocity of strip material leaving the rolling mill is compared with calculated exit velocity to derive an errorsignal.
  • a single stand rolling mill including an outer housing 12 which supports upper and lower rolls l4 and 16, the spacing or gap between the rolls being controlled by means of a screwdown mechanism generallyindicated by the reference numeral 18.
  • the screwdown mechanism 18 is controlled by means of a screwdown control which conventionally includes a drive motor mechanically connected to the screwdown mechanism itself, together with electrical controls for the drive motor.
  • the gap between the rolls can be controlled by a wedge or other similar device for varying the spacing between the rolls 14 and 16.
  • the material being reduced in the mill is identified by the reference numeral 22 and ordinarily comprises strip material which is unwound fromcoil 24 and rewound on coil 26.
  • strip material on coil 24 passes over idler roll 28, thence through the roll bite defined between rolls 14 and 16, and then over idler roll to the coil 26.
  • the takeup reel for coil 26 is driven by means of motor 32 controlled by motor control circuit 34 for the purpose of keeping the strip under tension as it is being rolled.
  • the gage of the strip material can be varied by either varying the spacing between the rolls l4 and 16, by varying the tension on the strip provided by means of motor 32, or by both.
  • the mill shown in FIG. 1 is of the reversing single stand .type, meaning that during one pass the strip moves from right to left while during the succeeding pass the mill is reversed and the strip moves from left to right.
  • the function of the reels for the two coils 24 and 26 is reversed with the reel for coil 24 acting as the tension reel and the reel for coil 26 acting as a payoff reel.
  • the reel for coil 24 is also provided with a drive motor, not shown. In the following description, it will be assumed that the strip is moving from left to right and that the coil 26 maintains tension on the strip.
  • a thickness gage 36 which measures the actual input gage of the strip material entering the mill.
  • a second thickness gage 38 which is used to measure the input gage of the strip material when the mill is reversed.
  • the gage 38 may be used to monitor the desired gage as selected by an operator as will hereinafter be explained in detail.
  • the two gages 36 and 38 are typically of the X-ray type
  • the output of the gage is an analog signal on lead 41, for example, proportional to the gage, 6,, of the entering strip material.
  • This analog signal is applied to a binary digitizer or analog-to-digital converter 40 wherein the gage signal is converted to a plurality of ON or OFF signals representing bits in a binary number.
  • These signals are then applied through gate 42 to the input of a shifi register 44 which advances gage measurements taken, for example, at l-inch intervals along the strip 22 to computation circuitry, generally indicated by the reference numeral 46 in FIG. 1.
  • the idler roll 28 is connected to a tachometer pulse generator 48 which will produce an output pulse each time the strip travels through a predetermined distance.
  • the generator 48 will produce a pulse each time the strip passes through a small fraction of an inch such that during l foot of travel of the strip 22, a large number of pulses is generated by the generator 48.
  • These pulses are applied to an interval counter 50 which will produce an output pulse on lead 52 each time the strip passes through a predetermined distance, say 1 foot.
  • the output pulses from the interval counter 50 are used as shift pulses for the shift register 44 and are also applied through a delay circuit 53 to the gate 42.
  • a pulse on lead 52 will initially be applied to the shift register 44 to advance the gage measurements stored therein to the next succeeding storage cores in the shift register while advancing the oldest gage measurement stored in the register 44 to the computing circuitry 46.
  • the delay circuit 53 opens the gate 42 to enter a new gage reading into the first core of the shift register.
  • the cores of the shift register 44 are first shifted to advance information to the computing circuitry 46, followed by the introduction of new information into the unit from gage 36.
  • the shift register 44 serves to store and advance successive entry gage measurements from gage 36 in synchronous correlation with the movement of the strip 22. That is, each time the gate 42 enabled by the interval counter 50, it feeds the instantaneous entry gage measurement to the first core of the shift register 44 which progressively advances these instantaneous measurements from one end of the shift register to the other. The time required to advance from one end of the shift register 44 to the other is equal to the time required for the strip 22 to travel from the gage 36 to the bite of the rolls l4 and 16.
  • the gate 42 opens and the instantaneous gage measurement, in binary form, is fed into the first storage core of the shift register 44. After the strip has traveled another foot, this first gage measurement is shifted to the second storage core and the gate 42 will then open to feed the second instantaneous gage measurement into the shift register. This process continues until 6 feet of material has passed from the gage 36 to the bite of the rolls, at which time the gage measurement at the output of shift register 44 is that taken from a point on the strip which is directly at the bite of the rolls 14 and 16. Thus, length of velocity calculations are made in accordance with the constant volume principle given above, not after the fact, but directly at the bite of the rolls.
  • a second pulse generator 54 Connected to the idler roll 30 is a second pulse generator 54 which, like generator 48, will produce a pulse each time the strip 22 travels through a predetermined distance. For a given length of material, both generators will produce the same number of pulses.
  • the pulses from generator 54 are applied to an L, counter 56 which has stored therein a number of pulses proportional to the length of the strip material 22 passing out of the mill.
  • the pulses generated by generator 48 will-be less in number than those generated by generator 54 since the strip material, in passing between the rolls l4 and 16, 5
  • the counters 58 and 56 while being shown herein as reset each time a new gage measurement is taken, need not necessarily be reset over the same time interval. If they are not reset over the same time interval, a second interval counter will be required.
  • the output of the L counter in digital form, is applied to the computing circuitry 46 along with the binary signal, 6,, from shift register 44 representing the gage of the material directly at the bite of the rolls 14 and 16. Also applied to the computing circuitry 46 is a signal, G from circuit 62 which is proportional to the desired exit gage of the strip material 22 as determined by the mill operator.
  • the computing circuitry 46 may, for example, comprise part of a general purpose computer or may comprise a separate hardware component for computing the equation:
  • G desired output gage as determined by the operator.
  • the electrical signal proportional to 17, may be applied to a binary register 64 and compared or subtracted in subtractor 66 from the stored value of L, in counter 58 to derive an error signal on lead 68.
  • This error signal is applied back to the screwdown control or, alternatively, to the tension motor control circuit 34 to vary the gage of the strip material 22.
  • the actual output gage as measured by gage 38 can be compared with the gage, G selected by the operator in comparison circuit 70 to derive a correction signal for the computing circuitry 46. That is, if the actual output gage is not equal to the desired gage selected by the operator, it is known that the product at the output of the computation circuitry 46 is incorrect or that possibly the L, counter is not registering correctly. This can be corrected by the error signal from comparator 70.
  • FIG. 2 a control system is shown which is similar to that of FIG. 1 except that input and output velocity measurements are taken rather than length measurements. Accordingly, elements corresponding to those shown in FIG. 1 are identified by like reference numerals.
  • entry gage measurements after being converted into binary form in digitizer 40, are passed through gate 42 and entered into shift register 44 where they are advanced in synchronous correlation with the movement of the strip 22 from the gage 36 to the bite of the rolls I4 and 16.
  • a tachometer 72 is connected to idler roll 28 along with pulse generator 48. The tachometer generator 72 will produce an analog signal on lead 74 proportional to the velocity of the entering strip material.
  • VG 1 2112a is calculated from a consideration of the quantity G, from the shift register 44, V, from the analog digital converter 84 and G from circuit 62 as detennined by the operator.
  • the quantity 7, comprising calculated input strip velocity, is applied to a second register 88 and subtracted in subtractor to provide an error signal on lead 68 which is fed back to the screwdown control 20 or tension motor control circuit 34.
  • velocity measurements can be used equally as well as length measurements since velocity appears on either side of the constant volume formula and, consequently, the time element cancels out.
  • FIG. 3 another embodiment of the invention is shown which again is similar to that of FIG. 1 except that in this case actual output length, L3, is compared with computed exit length, I ⁇ .
  • L3 actual output length
  • I ⁇ computed exit length
  • FIG. 4 still another embodiment of the invention is shown which is similar to that of FIG. 2 and wherein elements corresponding to those of FIG. 4 are identified by like reference numerals.
  • the output of the analog-to-digital converter 76 is connected to the computation circuitry 86'; whereas the output of the analog-to-digital converter 84, comprising a signal proportional to the exit velocity, V is applied to register 78'.
  • Computation circuit 86' in this case, computes:
  • the output of the computation circuitry 86' comprising a signal proportional to V is applied to register 88' and compared with the actual value of V in register 78' to produce an error signal on lead 68.
  • a system for controlling a rolling mill based on the principle of constant volume of material entering and leaving the mill, the combination of means for producing a first electrical signal proportional in magnitude to the desired output gage of strip material leaving the rolling mill, means for producing a second electrical signal which varies as a function of the actual gage of strip material entering the rolling mill, means for producing a third electrical signal which varies as a function of the length of strip material entering the mill over a predetermined period of time, means for producing a fourth electrical signal which varies as a function of the length of strip material leaving the mill over said predetermined period of time, means responsive to said first, second and one of said third and fourth signals for deriving a fifth electrical signal proportional to a calculated value of a quantity which varies as the length of material on one side of the mill varies over said predetermined time interval, and means for comparing said fifth electrical signal with one of said third and fourth electrical signals to derive an error signal for controlling said rolling mill.
  • said first signal is proportional to G the desired output gage of said material leaving the rolling mill; said second signal is proportional to 0,, the actual gage of the material entering the rolling mill; said third and fourth signals are proportional to L, and L,, the actual lengths of material entering and leaving the rolling mill, respectively, over said predetermined period of time; and said fifth signal is proportional to and is compared with said third signal L, to derive an error signal.
  • said first signal is proportional to G the desired output gage of strip material leaving the rolling mill; said second signal is proportional to G the actual gage of material entering the rolling mill; said third and fourth signals are proportional to V and V the actual velocities of the strip material entering and leaving the rolling mill, respectively; and said fifth electrical signal is proportional to BE Es-1.
  • said first signal is proportional to G the desired output gage of strip material leaving the rolling mill; said second electrical signal is proportional to 6,, the actual gage of material entering the rolling mill; said third and fourth signals are proportional to V and V,, the actual velocities of strip material entering and leaving the rolling mill, respectively; and said fifth electrical signal is proportional to and is compared with said fourth electrical signal to derive an error signal.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Metal Rolling (AREA)
US46320A 1970-06-15 1970-06-15 Rolling mill control system Expired - Lifetime US3636743A (en)

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US4632070A 1970-06-15 1970-06-15

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US (1) US3636743A (enExample)
JP (1) JPS549141B1 (enExample)
CA (1) CA919803A (enExample)
DE (1) DE2129629A1 (enExample)
FR (1) FR2095254B1 (enExample)
GB (1) GB1341059A (enExample)
SE (1) SE383612B (enExample)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5053262A (enExample) * 1973-09-12 1975-05-12
US20060123861A1 (en) * 2002-07-20 2006-06-15 Michael Pampel Dynamic thickness correction
US8381559B2 (en) 2009-03-10 2013-02-26 Converteam Gmbh Method for operating a mill train, in particular in a cold rolling mill
CN111250540A (zh) * 2020-01-22 2020-06-09 武汉科技大学 一种基于直流电流辅助的硅钢冷轧工艺

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE151675T1 (de) * 1981-04-29 1986-02-27 Kawasaki Steel Corp., Kobe, Hyogo Verfahren zur automatischen steuerung der dickenabnahme in einem walzwerk.
DE3925104A1 (de) * 1988-08-12 1990-02-15 Siemens Ag Vorrichtung zur banddickenregelung bei eingeruestigen kaltwalzgeruesten
DE4141742A1 (de) * 1991-12-13 1993-06-17 Licentia Gmbh Verfahren zur dickenregelung von bandfoermigem walzmaterial in bandstrassen
DE19962183A1 (de) * 1999-12-22 2001-07-12 Siemens Ag Regeleinrichtung für ein- oder mehrgerüstige Walzstrassen
EP2823901A1 (de) 2013-07-11 2015-01-14 Siemens Aktiengesellschaft Reversierwalzwerk mit frühestmöglicher Aktivierung einer Dickenregelung

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5053262A (enExample) * 1973-09-12 1975-05-12
US20060123861A1 (en) * 2002-07-20 2006-06-15 Michael Pampel Dynamic thickness correction
US7185520B2 (en) * 2002-07-20 2007-03-06 Aluminium Norf Gmbh Dynamic thickness correction
US8381559B2 (en) 2009-03-10 2013-02-26 Converteam Gmbh Method for operating a mill train, in particular in a cold rolling mill
CN111250540A (zh) * 2020-01-22 2020-06-09 武汉科技大学 一种基于直流电流辅助的硅钢冷轧工艺

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Publication number Publication date
FR2095254A1 (enExample) 1972-02-11
SE383612B (sv) 1976-03-22
FR2095254B1 (enExample) 1975-02-21
CA919803A (en) 1973-01-23
JPS549141B1 (enExample) 1979-04-21
GB1341059A (en) 1973-12-19
DE2129629A1 (de) 1971-12-23

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AS Assignment

Owner name: ALLEGHENY LUDLUM CORPORATION

Free format text: CHANGE OF NAME;ASSIGNOR:ALLEGHENY LUDLUM STEEL CORPORATION;REEL/FRAME:004779/0642

Effective date: 19860805

AS Assignment

Owner name: PITTSBURGH NATIONAL BANK

Free format text: SECURITY INTEREST;ASSIGNOR:ALLEGHENY LUDLUM CORPORATION;REEL/FRAME:004855/0400

Effective date: 19861226

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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. RECORDED ON REEL 4855 FRAME 0400;ASSIGNOR:PITTSBURGH NATIONAL BANK;REEL/FRAME:005018/0050

Effective date: 19881129