US3807206A - Strip gage change during rolling in a tanden rolling mill - Google Patents

Strip gage change during rolling in a tanden rolling mill Download PDF

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Publication number
US3807206A
US3807206A US00293618A US29361872A US3807206A US 3807206 A US3807206 A US 3807206A US 00293618 A US00293618 A US 00293618A US 29361872 A US29361872 A US 29361872A US 3807206 A US3807206 A US 3807206A
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Prior art keywords
stand
gage
speed
stands
roll gap
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US00293618A
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English (en)
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J Connors
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AEG Westinghouse Industrial Automation Corp
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Individual
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Priority to US00293618A priority Critical patent/US3807206A/en
Priority to JP48108586A priority patent/JPS5226512B2/ja
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Assigned to AEG WESTINGHOUSE INDUSTRIAL AUTOMATION CORPORATION reassignment AEG WESTINGHOUSE INDUSTRIAL AUTOMATION CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: WESTINGHOUSE ELECTRIC CORPORATION
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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

  • a method for changing the gage of strip material being rolled in a multi-stand tandem rolling mill wherein the roll gap setting and speed of the first stand are initially changed to change the gage of the strip material issuingfrom the first stand. Thereafter, in timed sequence, the roll gap settings and speeds of succeeding stands are changed until all roll gap settings and speeds of the stands in the mill have been changed to accommodate a new gage.
  • the roll gap setting and speed of each stand following the first is changed after a change in the immediately preceding stand .following a time interval substantially equal to the time required for the strip to travel to each stand from its immediately preceding stand. In this manner, the length of the strip material over which a transition in gage occurs is minimized.
  • the points at which a transition in gage occurs can be automatically 2 J panying drawings which form a part of this specification, and in which:
  • FIG. 1 is a block schematic diagram of one embodiment of the invention.
  • FIG. 2 is a plot of time versus strip speed and thickness for each of five stands in a tandem mill showing the manner in which the gage and speed are changed in each stand.
  • the system shown includes a five-stand tandem rolling mill including stands S1, S2, S3, S4 and S5.
  • Each stand comprises a pair of work rolls and 12 between which strip material being rolled passes, together with a pair of backup rolls, not shown.
  • the strip issuing from the last stand S5 is wound on a coiler 16, the direction of strip movement being from left to right as indicated by the arrow 18 in FIG. 1.
  • each stand is driven by means of drive motors M1, M2, M3, M4 and M5 each controlled by a speedcontrol circuit C1, C2, C3, C4 and C5, respec tively.
  • the speed control circuits C1-C5, in turn, are connected to a master speed controller 20 which establishes a nominal or desired speed for each of the stands in the mill to achieve adesired gage reduction.
  • the speed of the material issuing from any stand must be greater than that entering the stand in accordance with the constant volume principle. Accordingly, the speed of stand S2 must be greater that of stand S1; the speed of stand S3 must be greater than that of stand S2, and so on the speed of stand S5 beinggreatest.
  • interstand tension is sensed and used to control the roll gap of a succeeding stand.
  • a tensiometer between the first and second stands will immediately sense a change in tension and will, through an appropriate control loop, change the gap of the second stand to accommodate the new gage. This occurs automatically as the gage changes at the outpu t of each stand without requiring any sequencing circuitry. It is, however, necessary to provide sequencing circuitry to change the speed of succeeding stands such that the change in gage occurs at essentially the same point or location on the strip as it travels through the tandem mill.
  • the accomcontroller 20 includes a motor operated rheostat, the
  • rheostats being identified as R1, R2, R3, R4 and R5,
  • rheostat R1 With reference to rheostat R1, for example, it includes a motor 22 connected to a movable tap 24.
  • the motor 22 is connected to a gage change sequencer 26, the purpose of which will hereinafter be explained. It will be understood, of course, that as the taps 24 on the rheostats Rl-RS are varied, the speeds of the stands 51-85 will also be varied from that speed initially established by the master speed controller 20.
  • the chocks supporting the rolls in each stand are loaded by means of hydraulic cylinders H1, H2, H3, H4 and H5, respectively. That is, the hydraulic cylinders I-Il-I-IS provide the necessary roll force to reduce the strip 14 in thickness; and while only one cylinder is shown for each stand in the schematic illustration of FIG. 1, it will be understood that in an actual rolling mill there are hydraulic cylinders on opposite sides of the mill loading each of the chocks at the opposite ends of the rolls. It is, of course, possible to use a mechanical screwdown mechanism or a wedge-type control to effect somewhat the same results; however hydraulic cylinders are preferred because of their speed of operation.
  • gage of strip material passing through the first stand S1 is measured by means of an X-ray gage 28 or the like.
  • Gage 28 produces an electrical signal proportional to the actual gage between stands S1 and S2; and this signal is applied to a gage control circuit 30 where it is compared with an electrical signal proportional to desired exit gage from stand S1.
  • This reference signal
  • the gage control circuit 30 If the actual gage at the output of stand S1 does not match the desired gage as determined by the position of tap 36 on potentiometer 34, then the gage control circuit 30, through appropriate hydraulic controls, not shown, either increases or decreases the pressure on cylinder H1 to increase or decrease the roll force and- /or roll gap and thereby vary the gage of material issuing from stand S1 until it matches the desired gage.
  • tensiometers T1, T2, T3 and T4 which measure tension in the strip between each set ofstands.
  • the tensiometer T1 measures the tension in the strip material 14 between stands S1 and S2 and produces an electrical signal proportional thereto.
  • This tension signal from tensiometer T1 is compared in tension control circuit TC2 with a tension reference signal on lead 40 propor tional to desired tension; and if the two are not the same, then the tension control circuit TC2, through appropriate hydraulic controls, not shown, will vary the pressure exerted by cylinder H2 for stand S2, thereby varying the roll gap opening and/or roll force of stand S2.
  • Each t'ensiometer measures the interstand tension and compares it with a tension reference signal; and if the two are not the same, then the roll gap opening for the succeeding stand is varied.
  • potentiometer 46 has a movable tap 48 connected to a drive motor 50, the motor 50 being connected to the gage change sequencer 26. If the actual output gage does not match the desired gage as established by the tap 48 on potentiometer 46, then the gage control circuit 44 will apply an error signal to the speed control circuit C' to either increase or decrease the speed of motor M5 in stand S5 to correct for a variation from desired gage. Alternatively, the output error signal from the gage control circuit 44 can be applied to the tension control .circuit TC5 to either increase or decrease the roll gap of the last stand S5. In most cases,
  • mills of this type normally operate by rolling a continuous length of strip on a coil to ,a single specified thickness or gage along the entire length of the strip.
  • a gage change is effected during rolling by initially changing the roll gap setting and speed of the first stand S1 to change the gage of the strip material issuing from the first stand. Thereafter, in timed sequence, the roll gap settings and speeds of succeeding stands are changed until all roll gap settings and speeds of the stands in the mill have been set to accommodate a new gage.
  • the roll gap opening of the stands following the first stand is automatically varied by means of the tension control circuits TC2-TC5.
  • the gage change sequencer circuit 26 will initially drive motor 38 for rheostat 34 and motor 22 for rheostat R1 to decrease the roll gap of stand S1 and increase its speed. As the roll gap is decreased, the speed must be increased in accordance with the constant volume principle. Following the change in roll gap setting and speed of stand S1, and after a time interval approximately equal to the time required for a point on the strip to travel from stand S1 to stand S2, the gage change sequencer 26 will drive the motor 22 0f potentiometer R2 to increase the speed of stand S2.
  • gage change sequencer may take various forms well known to those skilled in the art and is essentially a timing device. Pushbuttons, a computer or'the like can be utilized to initiate the sequencing of circuit 26 to effect a change in gage.
  • FIG. 2 it represents a plot of time versus strip speed and thickness for each of the five stands in a tandem mill.
  • the stands are shown in simplified form to facilitate understanding and the time calibration is not necessarily constant from left to right.
  • FIG. 2 portrays a situation where delivery gage is to be increased in thickness.
  • Table I shows the original rolling schedule while Table II shows the revisedrolling schedule:
  • H represents the output gage at the respective stands, 5,, represents the output speed at the respective stands, D is the draft in each stand is defined as the difference between input and output thickness; and D, is the total draft of the mill. All of this is based upon the constant volume principle, assuming constant width wherein:
  • the sequence is as follows: At time 13,, it is decided I to change the gage of thestrip that is at that instant in stand S1.
  • the stand speed is reduced as shown in FIG. 2 and the set-point for the gage is changed. This occurs, with reference to FIG. 1, by changing the positions of the movable taps on rheostats 34 and R1.
  • the thickness H 'of strip issuing from the stand S1 increases and the speed S of stand S1 decreases.
  • stand S2 tension regulator TC2 operates on the stand S2 cylinder H2 to maintain tension.
  • transitional strip is off-gage strip and is shown in FIG. 2 as A H,, A H and so on.
  • the tension regulators will maintain set tension during the time this transitional strip is being rolled.
  • the strip tracking system established by the gage change sequencer 26 indicates that the gage change point is in stand S2. Therefore, it initiates a stand speed change by moving the tap on potentiometer R2. This causes a tension change and stand S3 tension regulator TC3 operates on stand S3 to maintain set tension.
  • the strip exiting the stand is at the correct gage and the stand drive is at the correct speed.
  • the transition strip A H however, is now longer than it was at stand S1. This is a result of the reduction taken in stand S2 and is illustrated in FIG. 2.
  • Stand S4 tension controller TC4 now functions to maintain set tension between stands S3 and S4.
  • the gage change point is at stand S4.
  • the cylinder H5 of stand S5 now responds to maintain interstand tension between stands'S4 and S5 as previously described.
  • an additional control signal may be involved on stand S5 speed. That is, the delivery thickness gage 42 operates into the stand S5 speed controller C5 and maintains set gage by varying the speed of stand S5. Therefore, at time t.,, the strip thickness reference to the gage control is changed to the revised value. This will, for the situation shown in FIG. 2, reduce the speed of stand S5, the effect being shown by the dotted line 40 in FIG. 2.
  • Table III tabulates a case where input strip thickness changes from*4.0 MM to 4.4 MM, but the delivered thickness remains constant at 1 MM.
  • the revised speeds for each stand are calculated based on maintaining the draft of each stand constant.
  • the roll gap setting and speed of each stand in timed sequence changing the roll gap setting and speed of succeeding stands until all roll gap settings and speeds of the stands in the mill have been changed to accommodate a new gage, the roll gap setting and speed of each stand intermediate the first and last stands being changed following a change in the immediately preceding stand after a time interval substantially equal to .the time required for the strip to travel to each stand from its immediately preceding stand, and the speed of the last stand being changed when the speed of the next to the last stand is changed.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Metal Rolling (AREA)
US00293618A 1972-09-29 1972-09-29 Strip gage change during rolling in a tanden rolling mill Expired - Lifetime US3807206A (en)

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US00293618A US3807206A (en) 1972-09-29 1972-09-29 Strip gage change during rolling in a tanden rolling mill
JP48108586A JPS5226512B2 (US07754267-20100713-C00021.png) 1972-09-29 1973-09-28

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4011743A (en) * 1976-04-20 1977-03-15 Westinghouse Electric Corporation Stand speed reference circuit for a continuous tandem rolling mill
WO1997027012A1 (en) * 1996-01-23 1997-07-31 Siemens Aktiengesellschaft System and method for rolling slabs
EP0936002A2 (de) * 1998-02-14 1999-08-18 Sms Schloemann-Siemag Aktiengesellschaft Walzverfahren für ein Band, insbesondere ein Metallband
CN109692874A (zh) * 2018-12-11 2019-04-30 燕山大学 Esp精轧机组逆流在线换辊与动态变规程同时进行的方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3603124A (en) * 1968-05-09 1971-09-07 Nippon Kokan Kk Computer control system for rolling metal strips using feed-forward and prediction
US3727441A (en) * 1970-03-16 1973-04-17 Hitachi Ltd Thickness control apparatus for rolling mill

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3603124A (en) * 1968-05-09 1971-09-07 Nippon Kokan Kk Computer control system for rolling metal strips using feed-forward and prediction
US3727441A (en) * 1970-03-16 1973-04-17 Hitachi Ltd Thickness control apparatus for rolling mill

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4011743A (en) * 1976-04-20 1977-03-15 Westinghouse Electric Corporation Stand speed reference circuit for a continuous tandem rolling mill
WO1997027012A1 (en) * 1996-01-23 1997-07-31 Siemens Aktiengesellschaft System and method for rolling slabs
EP0936002A2 (de) * 1998-02-14 1999-08-18 Sms Schloemann-Siemag Aktiengesellschaft Walzverfahren für ein Band, insbesondere ein Metallband
EP0936002A3 (de) * 1998-02-14 2001-01-03 SMS Demag AG Walzverfahren für ein Band, insbesondere ein Metallband
CN109692874A (zh) * 2018-12-11 2019-04-30 燕山大学 Esp精轧机组逆流在线换辊与动态变规程同时进行的方法
CN109692874B (zh) * 2018-12-11 2020-03-03 燕山大学 Esp精轧机组逆流在线换辊与动态变规程同时进行的方法

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Publication number Publication date
JPS4993253A (US07754267-20100713-C00021.png) 1974-09-05
JPS5226512B2 (US07754267-20100713-C00021.png) 1977-07-14

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Owner name: AEG WESTINGHOUSE INDUSTRIAL AUTOMATION CORPORATION

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:WESTINGHOUSE ELECTRIC CORPORATION;REEL/FRAME:005424/0551

Effective date: 19900313