Predictive gauge control method and apparatus with automatic plasticity determination for metal rolling mills

Claim 2

A gauge control system for a rolling mill having at least one rolling stand with a screwdown controlled roll opening through which a workpiece is transported, said system comprising means for detecting roll force at the rolling stand, means for detecting the rolling stand screwdown position, means for determining roll force error on the basis of detected roll force and screwdown position values and predetermined roll force and screwdown position reference values, means for determining screwdown movement to provide for correct gauge, said screwdown movement determining means including means for predictively determining the amount of screwdown movement needed for correcting determined roll force error in accordance with a predetermined relationship with predetermined online variables including stand entry and delivery gauges, said screwdown movement determining means further including means responsive to predetermined mill variables for making online determinations of stand entry and delivery gauges at least during a portion of the workpiece rolling period, and means for controlling screwdown position to effect corrective screwdown movement.

Claim 3

A gauge control system for a rolling mill having at least one rolling stand with a screwdown controlled roll opening through which a workpiece is transported, said system comprising means for detecting the rolling stand screwdown position, means for making an error determination representative of workpiece gauge error, means for determining screwdown movement to provide for correct gauge, said screwdown movement determining means including means for predictively determining the amount of screwdown movement needed for correcting said error determination in accordance with a predetermined relationship with predetermined online variables including stand entry and delivery gauges, said screwdown movement determining means further including means responsive to predetermined mill variables for making online determinations of stand entry and delivery gauges at least during a portion of the workpiece rolling period, and means for controlling screwdown position to effect corrective screwdown movement.

Claim 4

A gauge control system for a rolling mill having at least one rolling stand with a screwdown controlled roll opening through which a workpiece is transported, said system comprising means for detecting the rolling stand screwdown position, means for making an error determination representative of workpiece gauge error, means for determining screwdown movement to provide for correct gauge, said screwdown movement determining means including means for predictively determining the amount of screwdown movement needed for correcting said error determination in accordance with a predetermined relationship with predetermined online variables including stand entry and delivery gauges, said screwdown movement determining means further including means responsive to predetermined mill variables for making online determinations of stand entry and delivery gauges at least during a portion of the workpiece rolling period, and means for controlling screwdown position to effect corrective screwdown movement.

Claim 5

A gauge control system for a rolling mill having at least one rolling stand with a screwdown controlled roll opening through which a workpiece is transported, said system comprising means for detecting roll force at the rolling stand, means for detecting the rolling stand screwdown position, means for determining roll force error on the basis of detected roll force and screwdown position values and predetermined roll force and screwdown position reference values, means for determining screwdown movement to provide for correct gauge, said screwdown movement determining means including means for predictively determining the amount of screwdown movement needed for correcting determined roll force error in accordance with a predetermined relationship with determined roll force error and predetermined values of workpiece plasticity and the stand spring constant, said screwdown movement determining means including means responsive to predetermined mill variables for making online determinations of the workpiece plasticity at least during a portion of the workpiece rolling period, and means for controlling screwDown position to effect corrective screwdown movement.

Claim 6

A gauge control system for a rolling mill having at least one rolling stand with a screwdown controlled roll opening through which a workpiece is transported, said system comprising means for detecting roll force at the rolling stand, means for detecting the rolling stand screwdown position, means for determining roll force error on the basis of detected roll force and screwdown position values and predetermined roll force and screwdown position reference values, means for determining screwdown movement to provide for correct gauge, said screwdown movement determining means including means for predictively determining the amount of screwdown movement needed for correcting determined roll force error in accordance with a predetermined relationship with determined roll force error and predetermined values of workpiece plasticity and the stand spring constant, said screwdown movement determining means including means responsive to predetermined mill variables for making online determinations of the workpiece plasticity at least during a portion of the workpiece rolling period, and means for controlling screwDown position to effect corrective screwdown movement.

Claim 7

A gauge control system as set forth in claim 3 wherein said workpiece plasticity determining means operates in response to stand roll force and stand entry and delivery gauge determinations, and means for making said entry and delivery gauge determinations from corresponding screwdown position and roll force data.

Claim 8

A gauge control system as set forth in claim 3 wherein said workpiece plasticity determining means is operative substantially throughout the workpiece rolling period.

Claim 9

A gauge control system as set forth in claim 3 wherein the rolling mill is a tandem mill having a plurality of roll force gauge controlled stands, at least one of each of said detecting means is provided for each of the roll force gauge controlled stands, said roll force error and screwdown movement determining means determine roll force error and predictively determine roll force corrective screwdown movement for each of the roll force gauge controlled stands, said plasticity determining means makes online plasticity determinations for each of the roll force gauge controlled stands, and said screwdown controlling means makes corrective screwdown movement at the corresponding roll force gauge controlled stands.

Claim 10

A gauge control system as set forth in claim 3 wherein said determining means include a digital computer system, said computer system having an input coupled to said detecting means and an output coupled to said screwdown controlling means, and means for operating said computer system to make the roll force error and workpiece plasticity and screwdown movement determinations.

Claim 11

A gauge control system as set forth in claim 4 wherein roll force corrective screwdown movement is determined from roll force error and the quantity where P equals the workpiece plasticity in units of force divided by units of distance and K equals the stand spring constant in units of force divided by units of distance, the workpiece plasticity being determined during said workpiece rolling period portion in accordance with the equation where F equals the stand roll force and He equals the stand entry gauge and Hd equals the stand delivery gauge.

Claim 12

A gauge control system as set forth in claim 8 wherein the quantity He is equal to and Hd is equal to where So(N-1) and So(N) are the screwdown positions and F(N-1) and F(N) are the roll forces and K(N-1) and K(N) are the spring constants associated respectively with a next previous workpiece rolling operation (N-1) and the present workpiece rolling operation N.

Claim 13

A gauge control system as set forth in claim 8 wherein said determining means include a digital computer system, said computer system having an input coupled to said detecting means and an output coupled to said screwdown controlling means, and means for operating said computer system to determine the plasticity P and to determine roll force corrective screwdown movement form the product of determined roll force error and the quantity .

Claim 16

A gauge control system as set forth in claim 2 wherein screwdown movement for correcting said error determination is determined from quantities including a quantity corresponding to the quantity where P equals the workpiece plasticity in units of force divided by units of distance, the workpiece plasticity being determined in accordance with the equation where F equals the stand roll force and He equals the stand entry gauge and Hd equals the stand delivery gauge.

Claim 21

A programmed digital computer operating method as set forth in claim 14 wherein the roll force corrective screwdown movement determining step includes determining screwdown movement from roll force error and the quantity where P equals the workpiece plasticity in units of force divided by units of distance and K equals the stand spring constant in units of force divided by units of distance, determining workpiece plasticity during the workpiece rolling period portion in accordance with the equation where F equals the stand roll force and He equals the stand entry gauge and is equal to where Hd equals the stand delivery gauge and is equal to where So(N-1) and So(N) are the screwdown positions and F(N-1) and F(N) are the roll forces, and where K(N-1) and K(N) are the spring constants associated respectively with a next previous workpiece rolling operation (N-1) and the present workpiece rolling operation N.