US3537285A - Prestressed rolling mill and control - Google Patents

Prestressed rolling mill and control Download PDF

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Publication number
US3537285A
US3537285A US515128A US51512865A US3537285A US 3537285 A US3537285 A US 3537285A US 515128 A US515128 A US 515128A US 51512865 A US51512865 A US 51512865A US 3537285 A US3537285 A US 3537285A
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United States
Prior art keywords
signal
preload
rolling
mill
circuit
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Expired - Lifetime
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US515128A
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English (en)
Inventor
Anne Kiggell
Dennis Stubbs
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Davy Loewy Ltd
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Davy Loewy 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
    • 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
    • B21B37/58—Roll-force control; Roll-gap control
    • 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
    • B21B37/58—Roll-force control; Roll-gap control
    • B21B37/64—Mill spring or roll spring compensation systems, e.g. control of prestressed mill stands

Definitions

  • the invention relates to a control scheme for a prestressed rolling mill, in order that the mill shall roll constant gauge.
  • a preload is applied to the housing, but not to the rolls of the mill.
  • the total s tress in the housing due to both the preload and the rolling load is continuously measured, as is the value of the preload. From the measurements, a continuous indication is given of the variations in the roll gap due to variations in the preload and rolling load and the preload is controlled by that indication to keep the gap constant.
  • This invention relates to rolling mills and is more particularly concerned with control systems aimed at maintaining constant gauge of strip and other elongate material issuing from a rolling mill.
  • Variations in the gauge of strip leaving a rolling mill emanate from the elastic nature of the components of the mill stand; the work between the work rolls of the stand produces a separating force which elastically deforms the chocks and housing of the stand.
  • the separating force, or rolling load varies, due to changes in the incoming strip, the deformation of the stand components and hence the roll gap between the working surfaces of the rolls changes, with the result that the gauge of the outgoing strip is no longer constant.
  • the present invention is directed to an automatic system for compensating for variations in the deformation of stand components due to variations in the rolling load, and broadly resides in preloading those parts of the mill, the deformation of which causes changes in the roll gap, under variations of the rolling load, with the exception of the rolls themselves, measuring the load to which those parts are subjected, deriving therefrom a control signal representing variations in the roll gap due to changes in the loads to which those parts and the rolls are subjected during rolling, and controlling the preloading automatically by the control signal to maintain substantially constant the roll gap, regardless of variations of the rolling load.
  • Another aspect of the present invention resides in the combination of a rolling mill having two roll assemblies, between which the material to be rolled is passed and preloading means for preloading those parts of the mill, the deformation of which causes changes in the roll gap under variations of the rolling load, the preloading means applying no preload to the rolls; and control system comprising means for continuously measuring the total load to which said parts are subjected during rolling, means for deriving therefrom a control signal representing variations in the roll gap due to changes in the loads to which said parts and the rolls are subjected during rolling and means for controlling the preloading means by the control signal to maintain substantially constant "ice the roll gap, regardless of variations of the rolling load.
  • a rolling mill comprises a mill frame, an upper and a lower roll assembly, each with a chock mounted in the frame, means disposed between the chocks of the two assemblies for preloading at least some of the chocks and the mill frame, means for generating a first signal representing the load to which the chocks and mill frame are subjected, means for generating a second signal dependent on the deformation of the rolls, and control means for controlling the preloading means automatically to maintain the sum of the first and second signals constant.
  • FIG. 1 schematically illustrates the mill and system
  • FIG. 2 shows a modification of the control system.
  • the mill stand has a pair of parallel housings, one of which is shown at 12.
  • Each housing has a window 13 in which an upper back-up roll chock 14 and a lower back-up roll chock 15 are slidably disposed.
  • the necks of the back-up rolls 16 are journalled in chocks 14, 15.
  • the upper and lower chocks 17, 18 for the work rolls 20 are nested in recesses in the backup roll chocks 14, 15 respectively.
  • the lower back-up roll chock 15 is supported on a pad 21 seated on the bottom of the window 13 while a screw 22, which can be driven by a screwdown motor not shown, engages the upper back-up roll chock 14 through a loadcell 23 and a pad 24.
  • In each housing there are a pair of hydraulic rams 25 acting between the upper and lower back-up chocks 14, 15.
  • the rams 25 are employed to apply a preload force to the chocks 14, 15 and to the housing 12, while the mill is rolling strip.
  • the rams 25 of both housings are supplied from a source 26 of liquid under pressure through a pressure regulating valve 27 and the lines 28, and the valve 27 is automatically controlled by an automatic control system.
  • This control system employs as the detector elements the loadcell 23, which measures the total force to which the chocks 14, 15 and the housing 12 are subjected, and a pressure transducer 29, which is subjected to the pressure of the liquid in line 28 and which supplies an electrical signal in accordance with that pressure.
  • the :signal from loadcell 23 is applied to an adding circuit 30 and also to a differencing circuit 31, to which the pressure signal from transducer 29 is also applied.
  • the difference signal from circuit 31 is applied through a modifying circuit 32 to the adding circuit 30.
  • the output from circuit 30 is applied to a comparing circuit 33.
  • a reference signal on line 34 is obtained from a reference generator 35, which can be adjusted by hand and which is also adjusted automatically by the output on line 36 from an integrating circuit 37.
  • Circuit 37 has applied to it the output from a direct acting thickness gauge 38, which output is proportional to the difference between the detected gauge of the outgoing strip and the required gauge.
  • the screws 22 are coupled to a potentiometer or other transducer 40 which gives a signal representing the mean position of the screws.
  • This signal and the signal on line 34 are diflerenced in the subtracting circuit 41, the difference signal being applied to the circuit 33 in which it is compared with the signal from adding circuit 30.
  • the difference signal from circuit 33 is applied to the pressure regulating valve 27.
  • the preload is augmented by the rolling load W, so that the housing 12 and the chocks 14, 15 are now subject to forces P+ W; however, the rolls 16, 20 are subject only to the rolling load W.
  • the roll gap S i.e., the separation of the working surfaces of the work rolls 20 when the preload P and the rolling load W are zero, is set by the screws 22 and measured by the potentiometer 40.
  • the roll gap increases when the hydraulic pressure is applied to the rams 25 to where M; is the spring modulus of the housings and chocks and to S-
  • This expression represents the thickness of the material rolled and the control system operates to maintain constant the function (P+W)/M +W/M,-, regardless of variations in the rolling load W, and thus maintains constant thickness of rolled material.
  • the loadcell 23 is subject to the sum of the preload and rolling load (P+W) and its electrical output is proportional to this sum.
  • pressure transducer 29 has an output proportional to the preload P so that the dilferencing circuit 31 gives an output proportional to the rolling load W, only.
  • the signal W from circuit 31 is multiplied in the modifying circuit 32 by a corrective function considered for illustrative purposes to be a. simple constant of proportionality K.
  • the modifying circuit 32 which may be a potentiometer or like device, may be adjusted to give varying values of K, by hand or automatically or may be a non-linear function generator.
  • the sum output from adding circuit 30 is then the sum of the signals from loadcell 23 and the modifying circuit 32, i.e.
  • the modifying circuit 32 is set to give a value K equal to M /M so that the output from circuit 30 now represents the enlargement of the roll gap due to the preload and rolling load.
  • the generator 35 is set by hand to the required gauge (h'), so that the difierencing circuit 41 applies the reference signal (h-S) to the comparing circuit 33.
  • the value for the enlargement of the roll gap is maintained constant by comparing it with this reference signal in the comparing circuit 33 and employing the error signal to control the preload P, by means of the pressure regulating valve 27. Invthis way, the roll gap is kept constant, regardless of variations in rolling load, due to variations in the characteristics of the strip entering the mill and as a result, the gauge of the outgoing strip is held substantially constant.
  • changes in gauge can be made by manual adjustment of generator 35, while any adjustment of the screws 22 is automatically introduced by the potentiometer 40.
  • the thickness gauge 38 gives an output representing the departure of the outgoing strip thickness from the required value (h') and this departure is indicated on a meter 42 and applied to the integrating circuit 37. If the control circuit before described operates entirely satisfactorily, the thickness gauge 38 will of course have zero output. If, however, there should be a 4 residual gauge error, there will be a signal from the gauge 38, the time integral of which will be produced on line 36 to modify the reference signal supplied by generator 35 and thus cause the roll gap to be maintained constant at a value, differing from that previously held but more suitable for the required output gauge.
  • FIG. 2 illustrates a modification of the control system of FIG. 1, like elements in both figures being given the same reference numerals.
  • the gauge error is then In FIG. 2, the signal from pressure transducer 29 is applied to modifying circuit 32 which introduces the factor l/M 'Ihe modified signal is now applied to difierencing circuit 50, to which is also applied the signal on line 51 from loadcells 23 via a modifying circuit 52 which introduces the factor l/M.
  • the diflference signal proportion to (P+W)/M-P/M is fed to comparing circuit 33, to produce the gauge error signal which controls valve 27, as before.
  • the preload is applied between the two roll assemblies on opposite sides of the pass line
  • the invention may be applied equally to other forms of prestressed mill, such as that in which there are adjustable spacers between the two roll assemblies and thepreload is applied at the location of the pad 21 to force the roll assemblies towards one naother.
  • the loadcell 23 is located in the spacers, so as to give an output signal representing the diiference between the preload forceand the rolling load.
  • the thickness of the rolled material which equals the roll gap modified by the compression of the spacers and the deformation of the rolls, is
  • the camber control equipment may be automatically controlled by the signal from the difierencing circuit 31, since roll bending arises from, and is dependent on, the rolling load. Dependent on the manner in which the camber control is applied, this may demand a complete revision of the control equations above, and hence the detailed control equipment.
  • a method of automatically controlling a rolling mill to maintain substantially constant the thickness of rolled material comprising preloading parts of the mill, the deformation of which causes changes in the roll gap under variations in the rolling load, said parts not including the rolls, continuously measuring the total load to which those parts are subjected due to the rolling load and the preload, continuously measuring the value of the preload, deriving a control signal representing variations in the roll gap due to changes in said total load and said preload, and controlling the preloading automatically by said control signal to maintain substantially constant the roll gap, regardless of variations of the rolling load.
  • a method in which a first signal is obtained representing said total load to which said parts are subjected, a second signal is derived from said total load and said preload representing the rolling load, and said first and second signals are combined together to obtain said control signal.
  • a method in which a first signal is obtained representing said total load to which said parts are subjected, a second signal is obtained representing said preload, and first and second signals are combined together to obtain said control signal.
  • the means for generating the second signal comprises a detector for detecting the preload and means for dilferencing the first signal and the preload.
  • the measuring means are arranged to generate a first signal representing the total load to which said parts are subjected, and in which there are additionally a detector for generating a second signal representing the preload, and means for combining the first and second signals together to derive the control signal.
  • a rolling mill having a plurality of rolls rotatively mounted about substantially parallel axes, bearing means for supporting the rolls, means supporting the bearing means for constraining the separating forces imparted to the rolls by the product being rolled, means mounted on the supporting means and acting on at least one roll to set the separation between the rolls, adjustable actuator means acting on the supporting means directly through the bearing means to apply a force which coacts With a separating force to oppose the force constrained by the supporting means, means to derive a control signal from the force constrained by the supporting means and the force applied by the adjustable actuator means, and actuator varying means responsive to the control signal to vary the force applied by the adjustable actuator means to maintain the work roll separation.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Metal Rolling (AREA)
US515128A 1964-12-22 1965-12-20 Prestressed rolling mill and control Expired - Lifetime US3537285A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB52116/64A GB1127926A (en) 1964-12-22 1964-12-22 Rolling mills
BE674206A BE674206A (de) 1964-12-22 1965-12-22

Publications (1)

Publication Number Publication Date
US3537285A true US3537285A (en) 1970-11-03

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US515128A Expired - Lifetime US3537285A (en) 1964-12-22 1965-12-20 Prestressed rolling mill and control

Country Status (7)

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US (1) US3537285A (de)
BE (1) BE674206A (de)
DE (1) DE1427872A1 (de)
FR (1) FR1461159A (de)
GB (1) GB1127926A (de)
NL (1) NL6516760A (de)
SE (1) SE305428B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4979556A (en) * 1989-04-04 1990-12-25 Hunter Engineering Company, Inc. Thickness control for a continuous caster

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE789573A (fr) * 1971-10-07 1973-03-29 Wean United Inc Commande de laminoir
US4415976A (en) * 1981-04-28 1983-11-15 Westinghouse Electric Corp. Method and apparatus for automatic mill zero correction for strip width
CA1184794A (en) * 1982-02-11 1985-04-02 William I. Deversterre Load-transfer mechanism
CN109226276A (zh) * 2018-11-13 2019-01-18 中国重型机械研究院股份公司 一种辊压机控制方法
CN111842504B (zh) * 2020-07-15 2022-06-07 上海宝立自动化工程有限公司 一种新型冷连轧机热带软启动厚度控制方法及系统

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2903926A (en) * 1956-01-11 1959-09-15 Baldwin Lima Hamilton Corp Method and apparatus for controlling the contour of rolls in a rolling mill
GB955164A (en) * 1963-04-10 1964-04-15 Loewy Eng Co Ltd Improvements in and relating to rolling mills
US3159063A (en) * 1961-09-29 1964-12-01 Thomas A Fox Rolling mill structures
US3247697A (en) * 1962-12-06 1966-04-26 Blaw Knox Co Strip rolling mill
US3285049A (en) * 1962-02-15 1966-11-15 Karl J Neumann Rolling mill with closed frames and with a control system for continuously and rapidly adjusting the roll gap
US3315507A (en) * 1962-12-24 1967-04-25 Siegener Maschb G M B H Method and apparatus for controlling thickness of elongated workpieces

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2903926A (en) * 1956-01-11 1959-09-15 Baldwin Lima Hamilton Corp Method and apparatus for controlling the contour of rolls in a rolling mill
US3159063A (en) * 1961-09-29 1964-12-01 Thomas A Fox Rolling mill structures
US3285049A (en) * 1962-02-15 1966-11-15 Karl J Neumann Rolling mill with closed frames and with a control system for continuously and rapidly adjusting the roll gap
US3247697A (en) * 1962-12-06 1966-04-26 Blaw Knox Co Strip rolling mill
US3315507A (en) * 1962-12-24 1967-04-25 Siegener Maschb G M B H Method and apparatus for controlling thickness of elongated workpieces
GB955164A (en) * 1963-04-10 1964-04-15 Loewy Eng Co Ltd Improvements in and relating to rolling mills
US3327508A (en) * 1963-04-10 1967-06-27 Loewy Eng Co Ltd Rolling mills

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4979556A (en) * 1989-04-04 1990-12-25 Hunter Engineering Company, Inc. Thickness control for a continuous caster

Also Published As

Publication number Publication date
FR1461159A (fr) 1966-12-02
BE674206A (de) 1966-04-15
GB1127926A (en) 1968-09-18
DE1427872A1 (de) 1968-10-31
SE305428B (de) 1968-10-28
NL6516760A (de) 1966-06-23

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