US3404550A - Workpiece shape and thickness control - Google Patents

Workpiece shape and thickness control Download PDF

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Publication number
US3404550A
US3404550A US546220A US54622066A US3404550A US 3404550 A US3404550 A US 3404550A US 546220 A US546220 A US 546220A US 54622066 A US54622066 A US 54622066A US 3404550 A US3404550 A US 3404550A
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United States
Prior art keywords
force
roll
strip
control
thickness
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Expired - Lifetime
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US546220A
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English (en)
Inventor
Richard G Plaisted
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CBS Corp
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Westinghouse Electric Corp
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Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Priority to US546220A priority Critical patent/US3404550A/en
Priority to DE1588943A priority patent/DE1588943B2/de
Priority to FR104785A priority patent/FR1521251A/fr
Priority to AT404267A priority patent/AT274149B/de
Application granted granted Critical
Publication of US3404550A publication Critical patent/US3404550A/en
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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
    • B21B37/28—Control of flatness or profile during rolling of strip, sheets or plates
    • B21B37/38—Control of flatness or profile during rolling of strip, sheets or plates using roll bending

Definitions

  • the present invention relates in general to the control of workpiece strip thickness leaving a rolling mill, and more particularly to the control of the workpiece strip thickness through control of the roll shape in an effort to provide a desired delivery workpiece strip thickness and shape.
  • the present invention involves automatically regulating the delivery workpiece strip shape and thickness by controlling the shape or bending of the work roll to compensate for operational factors such as the width and thickness of the strip, the desired reduction, the alloy material, the temperature of the mill and of the workpiece and the operational speed of the mill by applying a bending force to the work rolls such that there results a correction in the measured shape error of the workpiece strip and then compensating any measured workpiece strip thickness. error in relation to the bending of the work rolls to provide a desired automatic strip thickness control operation.
  • FIGURE 1 is a cross-section showing of a typical roll member having a crown shape
  • FIG. 2 illustrates the involved forces in accordance with the teachings of the present invention when a workpiece passes between the opposed rolls of a rolling mill
  • FIG. 3 diagrammatically illustrates the operation of one embodiment of the present invention
  • FIG. 4 is a curve illustrating the operation of the prior art apparatus in relation to roll force automatic strip thickness control
  • FIG. 5 is a curve illustrating the different operational conditions present in a roll force strip thickness control system in accordance with the teachings of the present invention
  • FIG. 6 is a diagrammatic showing of the control apparatus in accordance with one embodiment of the present invention.
  • FIG. 7 is a schematic showing of a suitable control circuit arrangement for providing the compensation desired in accordance with the present invention.
  • FIG. 1 there is shown a typical roll member for a rolling mill, which is ground to have a larger diameter at the center as compared to the ends of the roll. This is called a crowned roll and is utilized for more uniformly reducing the entering cross-section of the workpiece strip during a rolling operation.
  • FIG. 2 there is generally shown an upper roll 10 and a lower roll 12 having screwdown mechanism forces B applied to the ends of the rolls.
  • a resulting force A is in eifect applied to the center of the rolls 10 and 12 as shown due to the compression of the workpiece 14.
  • the separating forces due to the reduction of the workpiece 14 are distributed along the faces of the respective rolls 10 and 12. Equilibrium of metal reduction and roll deflection results in more deflection of the rolls 10 and 12, and consequently less reduction of the workpiece strip, at the center of the workpiece strip 14 as compared to the edges of the workpiece strip 14.
  • the delivery shape of rolled strip from hot mills and cold mills be controlled in reference to shape and flatness.
  • the desired reduction in thickness should be across the whole width of the strip.
  • the provision of a predetermined crown to the rolls is generally proper for one setting of rolling conditions only, and requires costly roll changes and a considerable supply of available and varied crowned rolls to enable any given rolling mill to properly roll a variety of workpiece sizes.
  • the elfective crown of any given roll can be varied in accordance with the present teachings by a controlled bending. of the roll during the actual rolling mill operation, by applying suitable bending forces to the work rolls or to the backup rolls as' may be preferred. It is contemplated that a crown change of several thousandths of an inch can be provided in this way.
  • a reference to the involved forces shown in FIG. 2 will illustrate the forces on the work roll.
  • the force A at a distance b from the center of the screw mechanism force B can be considered to be the equivalent force and the equivalent distance for any width workpiece strip being rolled. Any such strip being rolled will produce a torque equal to A b.
  • the illustrated torque Ca is equal to the torque Ab.
  • the values of A and B above are really incremental values when the roll itself is ground thicker in the center than at the ends. Only after this builtin contour has been utilized and .found to be inadequate, do the forces B and C start to be generated to oppose the force A beyond which the roll shape will not compensate to produce the desired shape or profile workpiece strip.
  • a plurality of equations can be very generally evolved in accordance with the force equilibrium conditions shown in FIG. 2 as follows:
  • an initial desired or referenced roll force is determined by a conventional automatic gauge control system, and the changes in the applied roll force relative to this reference roll force will be considered to be a AB control signal.
  • a typical reference roll force signal could be calculated by a screwdown controlling computer as desired for the next pass of the work strip through a particular stand of the rolling mill, and the changes away from the reference roll force that are effected throughout the length of the work strip as it passes through the mill stand .would be sensed and utilized to provide the incremental AB Control Signal,
  • FIG. 3 there is illustrated one control concept of the present invention, wherein the upper roll 10 and the lower roll 12 are operative with the workpiece 14 and a screwdown mechanism 16 applies the force B through a roll force sensing device 18 to effect the desired reduction in the workpiece 14.
  • Suitable shape control apparatus 20 is operative to sense the roll force signal provided by the inductive device 18 for controlling the bending shape of the rolls 10 and 12 as will be later described.
  • a force device 22 such as a hydraulic fluid cylinder apparatus or electric motor driven screw mechanism, is operative to supply the bending force C through a force sensing device 24 to the outer end of the neck 26 of the work roll 10 and to the outer end of the neck 28 of the work roll 12.
  • the bending force C applied by the force device 22 is sensed by the force sensing device 24 and a suitable signal is applied to the shape control apparatus 20.
  • the forces B and C applied to the Work roll 10 are compared by the shape oontrol apparatus 20 and a suitable control signal is thereby supplied to a force control device 30 for determining the operation of the force device 22 in opposition to the screw mechanism 16.
  • the roll force signal provided by the force sensing device 18 is applied through a compensation circuit 21 to a conventional roll force gauge control 23, with the compensation circuit 21 being responsive to a control signal from the shape control apparatus 22 for determining the operation of the compensation circuit 21 as will be later described.
  • FIG. 4 there is shown a curve illustrating the operation of a typical prior art roll force automatic strip thickness control system.
  • An equation can be drawn forthe well-known straight deformation line as follows:
  • the curve of FIG. 5 illustrates the changed operating conditions when the roll bending control is utilized in accordance with the teachings of the above referenced copending patent application. It can be seen that forces B and A in this context appear after roll bending control is employed. Since, in the roll bending region only a portion of the screwdown force B appears on the strip to effect reduction, the housing deformation line as seen by the strip suddenly assumes a smaller slope so that considerably more travel of the screws is required to pr'oducethe same gauge correction as before. The present invention takesinto account this. change in slope so that the automatic gauge control system can still function as desired.
  • an incremental position regulating control is used to move the screw mechanism the correct distance to take out the sensed gauge error. It is proposed in accordance with the present invention to multiply the gauge error signal used to determine the screw movement by to compensate for the lowered slope of the roll force line as applied to the strip.
  • FIG. 6 there is shown a right side roll force transducer 60 and a left side roll force transducer 62 connected to a roll force difference circuit 64 for providing a signal in accordance with the difference between the right roll force and the left roll force for the purpose of leveling the roll in the mill.
  • a first control circuit 66 which senses when the right roll force is greater than the left roll force, with suitable circuits to perform this function being well known in this particular art, and which first control circuit 66 when operative applies an output signal to open a gate '68 for then allowing the difference signal from the circuit 64 to be applied to the left screw mechanism 70 for increasing the left roll force as necessary to level the mill.
  • a control circuit 72 senses when the left roll force is greater than the right roll force and when operative opens the gate 74 for allowing the roll force difference signal to be applied from the circuit 64 to the right screw mechanism 76 for increasing the right screwdown force for the purpose of leveling the mill.
  • the right side bending force transducer 78 and the left side bending force transducer 80 are connected to an average bending force determining circuit 82, which provides an average bending force signal to a bending force difference circuit 84 in conjunction with a reference bending force signal from a circuit 86 for providing a bending force difference or error signal AC to a signal ratio circuit 88.
  • the reference bending force signal from the circuit 86 would be zero and the signal AC is the same as the signal C.
  • the output signal from either one of the roll force transducers 60 or 62, with the right roll force transducer 60 being chosen for the purpose of illustration, is supplied through a connection 89 to a roll force thickness error circuit 90 for comparison with the reference roll force signal from a suitable circuit 92 for providing a roll force difference of error signal AB to the signal ratio circuit 88.
  • the control signal from the signal ratio circuit 88 is applied to a control signal source 94 and a bending force control device 96 for applying an appropriate bending force to the rolls 10 and 12 as described in the above referenced copending patent application.
  • the function of the so far described circuit portions of FIG. 6 is to provide the desired roll crown and workpiece strip shape as delivered from the rolling mill, with the so far described circuit portion being adapted to function to maintain a predetermined and desired ratio for the change in roll force signal relative to the change in roll bending signal by varying the applied bending pressure such that any change in the applied roll force causes a corresponding change in the applied bending force.
  • a conventional roll force operative automatic strip gauge control system is provided in conjunction with the illustrated bending control apparatus, such that the thickness of the work strip delivered from the mill is maintained substantially constant throughout its length by the provided automatic gauge control equipment, and in conjunction there is additionally provided a shape or profile control through the operation of the so far described circuit portion illustrated in FIG. 6 such that any differences in the applied roll force between left and right ends of the work rolls is initially corrected through the roll leveling control shown in FIG. 6 and then additionally the gauge control apparatus applies the required changes in the roll force to compensate by a corrective bending of the rolls for providing the desired delivery workpiece strip shape.
  • FIG. 6 An operational amplifier 98 responsive to the roll force thickness error signal from the circuit 90 for determining the operation of a conventional automatic gauge or screwdown control system 100. Any changes in the operation of the screwdown mechanism motor 102 are sensed through the screw travel feedback circuit 104 for providing a corresponding feedback signal through one of two paths.
  • a first path is provided through a normally open gate circuit 106 responsive to the provision of a bending control signal by the control signal source 94 and is operative such that a screw travel feedback signal normally passes directly to the operational amplifier 98 through the gate 106 when no bending control signal is provided.
  • the gate 106 Upon the provision of a bending control signal by the control signal source 94 to the bending force control circuit 96, the gate 106 is closed such that the screw travel feedback signal from the circuit 104 must now pass through a predetermined bending compensation circuit 108 before being fed to an input of the operational amplifier 98.
  • FIG. 7 there is shown in greater detail the bending compensation circuit 108 and the operational amplifier 98 relative to the automatic gauge control or screwdown control circuit 100.
  • the right roll force transducer 60 and the left roll force transducer 62 supply roll force signals to an average roll force circuit 61, which in turn provides an average roll force signal to the roll force thickness error circuit 90 for comparison with a reference roll force signal from a suitable circuit 92, and any resulting and determined thickness error signal is supplied to one input of an operational amplifier 98 for application to the screwdown control for determining the corrective operation of the screwdown motor 102
  • the resulting movement of the screwdown motor 102 adjusts the position of potentiom eter arm to provide a corresponding screw travel feedback signal through the operational amplifier 122 to the bending compensation circuit 108 including the gate 106.
  • a bending control signal is applied by the control signal source 94 this causes the gate 106 to not be conductive.
  • the gate 106 could be a normally closed relay or a suitable switching device which has a normal low impedance path, and upon receipt of the bending control signal from the control signal source 94 is opened and thereby assumes a very high impedance condition to be not conductive.
  • the screw travel feedback signal from the operational amplifier 122 is now caused, with the gate 106 open and not conductive, to pass through the bending compensation circuit 108 which includes a predetermined set potentiometer eenrgized by a reference voltage source 110 for providing a predetermined ratio compensation to the screw travel feedback signal.
  • the parameters of the potentiometer 112 in combination with the voltage source 110 and the setting position of the potentiometer arm are such that a desired compensation factor is introduced into the screw travel feedback signal such that an additional travel of the screwdown motor 102 is required to balance the roll force signal and desired strip correction.
  • the roll force error signal from the roll force thickness error circuit 90 is an incremental memory of the change in required roll force B produced by a change in the hardness of the workpiece strip. This produces a movement of the screwdown motor 102 and this screw movement produces a voltage on the output of the operational amplifier 122 proportional to screw travel. The system is so scaled that this movement will produce enough additional roll force to correct the output strip guage to the desired reference value.
  • the gate 106 When the roll bending control system requires a bending force C then the gate 106 will open to insert the ratio compensation factor into the circuit path of the screw travel feedback signal from the operational amplifier 122, thereby reducing the effective feedback value of the screw travel feedback signal supplied to an input of the operational amplifier 98 and causing the screwdown control 100 to provide a greater actual travel of the screwdown motor 102 to balance the roll force error or correction signal from the roll force thickness error circuit 90.
  • first force sensing means positioned relative to said rolling mill to sense a first force between said rolls relative to a central portion of said strip for providing a first control signal in accordance with said first force
  • second force sensing means positioned relative to said rolling mill to sense a second force between said rolls relative to an edge portion of said strip for providing a second control signal in accordance with said second force
  • roll shape control means responsive to said first and said second control signals for applying a roll shape correction force to at least one of said rolls in accordance with a predetermined comparison of said first and second control signals
  • strip thickness sensing means operative with said rolling mill for providing a thickness error signal relative to a desired strip thickness
  • strip thickness control means being operative with said roll shape correction force and responsive to said error signal for controlling the thickness of said strip in accordance with said error signal.
  • the apparatus of claim 1 for controlling the thickness of a workpiece strip passing between the rolls of a rolling mill, with said first force sensing means being sensitive to a first force in effect provided between said rolls relative to a central portion of said strip for providing a first control signal in accordance with said first force, and with said strip thickness control means being responsive to a predetermined factor of said error signal when said roll shape correction force is present, with said predetermined factor being related to the distance between said first force and said second force and the distance between said second force and said roll shape correction force.
  • the apparatus of claim 1 for controlling the thickness of a workpiece strip passing between the rolls of a rolling mill including a screwdown mechanism, with said first force sensing means being operative to sense a first force between said rolls at a first location relative to a central portion of said strip, with said second force sensing means being operative to sense a second force provided between said rolls by said screwdown mechanism and relative to an edge portion of said strip, with said roll shape control means applying a work roll shape correction third force to at least one of said rolls external to said second force, and with said strip thickness control means being responsive to said roll shape correction force for being operative with a predetermined factor of said error signal, with said predetermined factor being a ratio of a first distance between the first force and the second force and a second distance between the second force and the third force.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Metal Rolling (AREA)
US546220A 1966-04-29 1966-04-29 Workpiece shape and thickness control Expired - Lifetime US3404550A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US546220A US3404550A (en) 1966-04-29 1966-04-29 Workpiece shape and thickness control
DE1588943A DE1588943B2 (de) 1966-04-29 1967-04-26 Einrichtung zur Regelung der Dicke und der Querschnittsform eines zu walzenden Bandes
FR104785A FR1521251A (fr) 1966-04-29 1967-04-28 Commande de l'épaisseur et de la forme d'une bande laminée
AT404267A AT274149B (de) 1966-04-29 1967-04-28 Regelanordnung zur über die Bandbreite kontinuierlichen Dicken- bzw. Querschnittsformkonstanthaltung eines Bandes in einem Bandwalzgerüst

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US546220A US3404550A (en) 1966-04-29 1966-04-29 Workpiece shape and thickness control

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DE (1) DE1588943B2 (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4415976A (en) * 1981-04-28 1983-11-15 Westinghouse Electric Corp. Method and apparatus for automatic mill zero correction for strip width
US4700312A (en) * 1978-12-27 1987-10-13 Hitachi, Ltd. Method and apparatus for controlling snake motion in rolling mills
US4938045A (en) * 1987-10-31 1990-07-03 Rosenstock Hans G Method of ascertaining the magnitude of forces acting upon rolls in rolling mills
US20070145615A1 (en) * 2005-12-28 2007-06-28 Konica Minolta Opto, Inc. Optical film, optical film manufacturing method and optical film manufacturing device

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3158049A (en) * 1961-09-21 1964-11-24 Rank Precision Ind Ltd Automatic gauge control systems
US3171305A (en) * 1961-05-03 1965-03-02 United Eng Foundry Co Rolling mill
US3177346A (en) * 1959-11-06 1965-04-06 United Steel Companies Ltd Apparatus for use in controlling a rolling mill
US3194036A (en) * 1958-01-02 1965-07-13 Westinghouse Canada Ltd Material thickness control apparatus
US3250105A (en) * 1958-08-25 1966-05-10 United Eng Foundry Co Method of and apparatus for processing metal strip
US3318124A (en) * 1964-12-10 1967-05-09 Westinghouse Electric Corp Workpiece shape control

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3194036A (en) * 1958-01-02 1965-07-13 Westinghouse Canada Ltd Material thickness control apparatus
US3250105A (en) * 1958-08-25 1966-05-10 United Eng Foundry Co Method of and apparatus for processing metal strip
US3177346A (en) * 1959-11-06 1965-04-06 United Steel Companies Ltd Apparatus for use in controlling a rolling mill
US3171305A (en) * 1961-05-03 1965-03-02 United Eng Foundry Co Rolling mill
US3158049A (en) * 1961-09-21 1964-11-24 Rank Precision Ind Ltd Automatic gauge control systems
US3318124A (en) * 1964-12-10 1967-05-09 Westinghouse Electric Corp Workpiece shape control

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4700312A (en) * 1978-12-27 1987-10-13 Hitachi, Ltd. Method and apparatus for controlling snake motion in rolling mills
US4415976A (en) * 1981-04-28 1983-11-15 Westinghouse Electric Corp. Method and apparatus for automatic mill zero correction for strip width
US4938045A (en) * 1987-10-31 1990-07-03 Rosenstock Hans G Method of ascertaining the magnitude of forces acting upon rolls in rolling mills
US20070145615A1 (en) * 2005-12-28 2007-06-28 Konica Minolta Opto, Inc. Optical film, optical film manufacturing method and optical film manufacturing device
US7803292B2 (en) * 2005-12-28 2010-09-28 Konica Minolta Opto, Inc. Optical film, optical film manufacturing method and optical film manufacturing device

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DE1588943A1 (de) 1970-10-08
AT274149B (de) 1969-09-10
DE1588943B2 (de) 1975-06-26

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