Method and rolling stand for cold rolling rolled stock

Abstract

The invention relates to a method and a rolling stand ( 100 ) for cold rolling rolled stock. The rolling stand ( 100 ) comprises at least one upper and one lower backup roll ( 110 - 1, 110 - 2 ) and also an upper and a lower work roll ( 120 - 1, 120 - 2 ), which define a roll gap ( 128 ). Optionally, a lower and an upper intermediate roll ( 130 - 1, 130 - 2 ) may also be provided between the work rolls and the backup rolls. In order to ensure an absolutely equal circumferential speed of the upper and lower work rolls when cold rolling in skin-pass mode, it is proposed according to the invention to decouple the upper or lower work roll from its associated drive device.

1 . A method for operation of a rolling stand ( 100 ) for cold rolling rolled stock ( 200 ), wherein the rolling stand comprises at least one upper and one lower backup roll ( 110 - 1 ,  110 - 2 ) and also an upper and a lower work roll ( 120 - 1 ,  120 - 2 ), which define a roll gap ( 128 ), and optionally also an upper and lower intermediate roll ( 130 - 1 ,  130 - 2 ), and wherein the rolling stand optionally can be operated in a reducing operation operating mode for reducing the thickness of the rolled stock ( 200 ) or in a skin-pass mode; characterized in that neither the upper back-up roll ( 110 - 1 ) nor the lower back-up roll ( 110 - 2 ) are driven during the skin-pass operation, and the upper or the lower work roll ( 120 - 1 ,  120 - 2 ) is decoupled from its drive unit ( 124 ,  124 - 1 ,  124 - 2 ). 
     
     
         2 . The method according to  claim 1 , characterized in that for the skin-pass mode the upper backup roll ( 110 - 1 ) is lifted off the upper work roll ( 120 - 1 ), or, if present, off the upper intermediate roll ( 130 - 1 ); and in that the application and the adjustment of a rolling force (F) ensues due to the action of upper bending cylinders ( 140 ) on the upper work roll ( 120 - 1 ), or, if present, on the upper intermediate roll ( 130 - 1 ). 
     
     
         3 . The method according to  claim 2 , characterized in that the thickness of the rolled stock ( 200 ) in skin-pass mode is adjusted to a predetermined constant target thickness with the aid of a skin-pass level control circuit ( 150 ), by suitable variation of the strip tension of the rolled stock or of the rolled stock speed as manipulated variables. 
     
     
         4 . The method according to  claim 3 , characterized in that the bending force (F) applied from the bending cylinders ( 140 ) onto the rolled stock ( 200 ) with the aid of a rolling force control circuit ( 160 ) and/or preferably also the adjusting position of the work rolls ( 120 - 1 ,  120 - 2 ) is/are kept constant with the aid of a position control circuit ( 170 ). 
     
     
         5 . The method according to  claim 2 , characterized in that the flatness of the rolled stock is controlled with the aid of a flatness control circuit ( 180 ) by measuring the actual flatness at the rolling stand outlet and by suitable action on actuating mechanisms in accordance with a flatness control deviation as difference between a predetermined target flatness and the measured actual flatness. 
     
     
         6 . The method according to  claim 1 , characterized in that the lubricant is prefiltered after its use and prior to its reuse. 
     
     
         7 . The method according to  claim 1 , characterized in that only a minimal quantity of pure lubricant is used in skin-pass mode. 
     
     
         8 . The method according to  claim 1 , characterized in that the rolled stock ( 200 ) involves nonferrous metal strip or ferrous metal strip. 
     
     
         9 . The method according to  claim 8 , characterized in that rolling oil is used as lubricant during skin-pass rolling of nonferrous metal strip as rolled stock. 
     
     
         10 . The method according to  claim 1 , characterized in that skin-pass rolls with surface roughening are used as work rolls ( 120 - 1 ,  120 - 2 ) in skin-pass mode; and that the skin-pass rolls are preferably cleaned by high-pressure spraying with a lubricant and/or with the aid of brushes during work breaks of the skin-pass mode. 
     
     
         11 . A rolling stand ( 100 ) for cold rolling rolled stock, comprising: one upper and one lower backup roll ( 110 - 1 ,  110 - 2 ); one upper and one lower work roll ( 120 - 1 ,  120 - 2 ), which are supported between the backup rolls and define a roll gap ( 128 ); optionally also one upper and one lower intermediate roll ( 130 - 1 ,  130 - 2 ) which are supported between the work rolls and backup rolls; at least one drive unit ( 124 ,  124 - 1 ,  124 - 2 ) for driving the work rolls; and one torque transfer device ( 120 ′,  120 ″) for transferring a torque from the at least one drive unit to the work rolls, wherein the rolling stand is designed as combined reducing roll stand and rerolling stand with the alternative reducing operating modi for the thickness of the rolled stock, or for skin-pass mode; characterized in that the torque transfer device ( 120 ′,  120 ″) comprises at least one coupling device ( 126 ,  126 - 1 ,  126 - 2 ) and one associated control unit ( 127 ) for decoupling the upper or the lower work roll from the at least one drive unit ( 124 ,  124 - 1 ,  124 - 2 ) during the skin-pass mode during which both back-up rolls ( 110 - 1 ,  110 - 2 ) are not being driven. 
     
     
         12 . The rolling stand ( 100 ) according to  claim 11 , characterized in that the drive unit for driving the upper work roll is provided in form of an upper drive unit ( 124 - 1 ); and the torque transfer device ( 120 ′) comprises the coupling device in form of an upper coupling device ( 126 - 1 ), one upper drive spindle ( 122 - 1 ) and optionally one upper transmission gear ( 129 - 1 ) for transfer of a torque from the upper drive unit ( 124 - 1 ) onto the upper work roll ( 120 - 1 ), wherein the upper drive spindle ( 122 - 1 ) is arranged between the upper work roll and the upper drive unit ( 124 - 1 ) and the optional transmission gear ( 129 - 1 ) is arranged between the upper drive spindle and the upper drive unit; and wherein the upper coupling device ( 126 - 1 ) is arranged between the upper work roll and the upper drive spindle and/or between the upper drive spindle and the upper transmission gear and/or between the upper transmission gear and the upper drive unit and/or is designed as no-load position of the upper transmission gear ( 129 - 1 ). 
     
     
         13 . The rolling stand ( 100 ) according to  claim 12 , characterized in that the drive unit alongside the upper drive unit ( 124 - 1 ) also comprises one lower drive unit ( 124 - 2 ) for driving the lower work roll ( 120 - 2 ); and the torque transfer device ( 120 ′) furthermore comprises one lower coupling device ( 126 - 1 ), one lower drive spindle ( 122 - 2 ) and optionally one lower transmission gear ( 129 - 2 ) for transfer of a torque from the lower drive unit ( 124 - 2 ) onto the lower work roll ( 120 - 2 ), wherein the lower drive spindle ( 122 - 2 ) is arranged between the lower work roll and the lower drive unit ( 124 - 2 ) and the optional lower transmission gear ( 129 - 2 ) is arranged between the lower drive spindle and the lower drive unit; and wherein the lower coupling device ( 126 - 2 ) is arranged between the lower work roll and the lower drive spindle and/or between the drive spindle and the lower transmission gear ( 129 - 2 ) and/or between the lower transmission gear and the lower drive unit ( 124 - 2 ) and/or is designed as no-load position of the lower transmission gear. 
     
     
         14 . The rolling stand according to  claim 11 , characterized in that the torque transfer device ( 120 ″) alongside the coupling device ( 126 ) comprises one upper and one lower drive spindle ( 122 - 1 ,  122 - 2 ) and a pinion stand gear drive ( 129 ) for transfer of a torque from the drive unit ( 124 ) onto at least one of the work rolls ( 120 - 1 ,  120 - 2 ), wherein the pinion stand gear drive is connected on its moment input with the sole drive unit ( 124 ); wherein the upper drive spindle ( 122 - 1 ) is arranged between the upper work roll and the upper moment output of the pinion stand gear drive, the lower drive spindle ( 122 - 2 ) is arranged between the lower work roll and the lower moment output of the pinion stand gear drive and the pinion stand gear drive is arranged between the drive spindles ( 122 - 1 ,  122 - 2 ) and the drive unit ( 124 ); and wherein the coupling device ( 126 ) is arranged between the upper work roll and the upper drive spindle and/or between the upper drive spindle and the upper moment output of the pinion stand gear drive and/or between the lower work roll and the lower drive spindle and/or between the lower drive spindle and the lower moment output of the pinion stand gear drive and/or is designed as no-load position of the pinion stand gear drive. 
     
     
         15 . The rolling stand ( 100 ) according to  claim 11 , characterized by at least upper bending cylinders ( 140 ) for application and adjustment of a rolling force (F) in the roll gap ( 128 ) by action on the upper work roll ( 120 - 1 ) or, if present, on the upper intermediate roll ( 130 - 1 ). 
     
     
         16 . The rolling stand ( 100 ) according to  claim 11 , characterized in that the rolling stand ( 100 ) comprises one skin-pass level control circuit ( 150 ) for controlling the thickness of the rolled stock in the skin-pass mode operational mode, one rolling force control circuit ( 160 ) for keeping the rolling force constant during the skin-pass mode, one position control circuit ( 170 ) and/or one flatness control circuit ( 180 ) for ensuring the flatness of the rolled stock. 
     
     
         17 . The rolling stand ( 100 ) according to  claim 11 , characterized in that the rolling stand ( 100 ) is designed to be operated pursuant to the method according to one of the  claims 1  to  10 . 
     
     
         18 . The rolling stand ( 100 ) according to  claim 11 , characterized by a spray bar ( 195 ) for rolling oil in the inlet of the rolling stand for skin-pass rolling of nonferrous metal strip as a rolled stock.