Roll With Rotating Shell

Abstract

The invention relates to a rolling mill roll with a rotating shell consisting of a tubular shell ( 1 ) rotatably mounted on a plurality of pads ( 3 ) holding the shell ( 1 ), whereby a hydrodynamic lift effect is created by introducing a lubricating fluid between the bering face ( 31 ) of the pad ( 3 ) and the internal face ( 13 ) of the shell ( 1 ). According to the invention, the bearing face ( 31 ) of each pad is provided with three hydrostatic pockets, one middle pocket ( 5 ) and two upstream ( 7 ) and downstream ( 6 ) lateral pockets, respectively, which are fed with the same fluid under a pressure sufficient to allow an additional oil flow to be introduced into the dragged out film ( 4 ) with a local pressure increase, in order to broaden—in the upstream and downstream direction—the hydrodynamic lift angular sector ( 4 ) while maintaining, throughout the length thereof, the fluid quantity required for the desired lift effect.

1 . Roll with a rotating shell consisting of:
 a stationary support ( 11 ) in the form of an elongated beam,   a tubular shell ( 1 ) having an internal face ( 13 ) and a cylindrical external face, surrounding the support beam ( 11 ) and rotatably mounted on said beam around a rotation axis, said shell being subjected to thrust forces distributed along an external face and directed virtually along a bearing plane (P),   a plurality of pads ( 3 ) holding the shell ( 1 ), intercalated between the internal face ( 13 ) of said shell and a bearing face of the support beam ( 11 ) and distributed, side by side, across the shell length, each pad ( 3 ) being shiftable along a radial direction passing through the rotation axis and comprising a cylindrical bearing face ( 31 ) having a radius nearly equal to that of the internal face ( 13 ) of the tubular shell ( 1 ) and extending over a large aperture angular sector,   means of individually adjusting the position and thrust of the pads ( 3 ) comprising, for each pad ( 3 ), at least one hydraulic cylinder ( 2 ) intercalated between the beam and the pad ( 3 ) and connected to a first pressurized fluid feeding circuit ( 20 ),   at least one hydrostatic pocket ( 5 ) provided in a middle part of the bearing face ( 31 ) of the pad and connected to a second pressurized fluid feeding circuit ( 50 ),   means of introducing, in a gap between the bearing face ( 31 ) of the pad ( 3 ) and the internal face ( 13 ) of the shell ( 1 ), a lubricating fluid forming a continuous film dragged out by the rotation of the shell ( 1 ) whereby a hydrodynamic lift effect is created in a pressure area ( 4 ) extending over a large aperture angular sector and comprising, in the direction of rotation of the shell ( 1 ), an upstream part (A) for gradually increasing the fluid pressure from pad entry, a maximum pressure central part B covering an angular sector substantially corresponding to the middle pocket ( 5 ), and a downstream part (C) for quick decrease in pressure up to pad exit,   
     characterized in that the bearing face ( 31 ) of each pad is provided with two lateral pockets, upstream ( 7 ) and downstream ( 6 ), opening on each side of the middle pocket ( 5 ) and supplied with fluid under a pressure sufficient to allow an additional oil flow to be introduced into the dragged out film with a local pressure increase, in order to broaden—in the upstream ( 4 ) and downstream direction—the hydrodynamic lift angular sector ( 4 ) by maintaining, throughout the length thereof, the fluid flow rate required for the desired lift effect. 
   
   
       2 . Roll with a rotating shell as claimed in  claim 1 , characterized in that each pocket ( 5 ,  6 ,  7 ) of each pad ( 3 ) is associated with a means of calibrating the flow introduced through the relevant pocket, the pressure in said pocket being adjusted at a value at least sufficient to cause the calibrated flow to be discharged at the corresponding level of the fluid film ( 4 ), up to a maximum value of the thrust exerted by the pad ( 3 ) on the shell ( 1 ). 
   
   
       3 . Roll with a rotating shell as claimed in  claim 2 , characterized in that the fluid introduced under pressure through the two lateral pockets ( 6 ,  7 ) determines thrust forces centered on two radial planes (P 1 , P 2 ) inclined on each side of the bearing plane (P) and likely to maintain the pad stability. 
   
   
       4 . Roll with a rotating shell as claimed in  claim 1 , characterized in that the hydrodynamic lift zone ( 4 ) of the pad includes a high pressure central pressure stage extending over an angular sector substantially corresponding to the middle pocket ( 5 ), and two lateral pressure stages corresponding to the two lateral pockets ( 7 ,  6 ) respectively, one upstream pressure stage ( 41 ) in the upstream pressure increase part (A) and one downstream pressure stage ( 42 ) in the downstream part (C) for pressure decrease in the lift zone ( 4 ). 
   
   
       5 . Roll with a rotating shell as claimed in  claim 4 , characterized in that the upstream lateral pocket ( 7 ) is fed at a pressure lower than the pressure in the middle pocket ( 5 ) and that the downstream lateral pocket ( 6 ) is fed at a pressure between middle pocket ( 5 ) and upstream pocket ( 7 ) pressures. 
   
   
       6 . Roll with a rotating shell as claimed in  claim 4 , characterized in that the fluid introduced at the level of the upstream pressure stage ( 41 ) causes the hydrodynamic pressure to increase more rapidly as a result of the increased quantity of dragged out fluid and determines a longitudinal and transverse widening of the high pressure central pressure stage ( 40 ) by leak rate compensation in this region. 
   
   
       7 . Roll with a rotating shell as claimed in  claim 6 , characterized in that the fluid introduced in the region of the downstream pressure stage ( 42 ) causes the hydrodynamic lift zone ( 4 ) to widen as a result of the increased quantity of fluid dragged out up to pad ( 3 ) exit. 
   
   
       8 . Roll with a rotating shell as claimed in  claim 2 , characterized in that each middle pocket ( 5 ) is fed individually by a pump delivering a calibrated flow rate. 
   
   
       9 . Roll with a rotating shell as claimed in  claim 8 , characterized in that the lateral pockets ( 6 ) ( 7 ) of all pads ( 3 ) arranged on the same side of the middle pocket ( 5 ) are supplied in parallel from a common pipe connected to one single pump on which a plurality of individual fed pipes for each pocket are connected in parallel, each fitted with a device ( 62 ) ( 72 ) for calibrating the fluid flow injected through said pocket into the dragged out film. 
   
   
       10 . Roll with a rotating shell as claimed in  claim 2 , characterized in that it comprises at least three units (E 3 , E 1 , E 2 ) consisting of the pockets arranged on all the pads ( 3 ) in the same position relative to the bearing plane (P), lateral upstream ( 7 ), middle ( 5 ) and lateral downstream ( 6 ), respectively, and the pockets of each unit (E 3 , E 1 , E 2 ) are fed in parallel from a joint pipe ( 71 ,  51 ,  61 ) provided along the support beam ( 2 ) and on which a plurality of individual pipes feeding each pocket of the unit (E 3 , E 1 , E 2 ), are connected in parallel, each fitted with an individual device ( 72 ,  52 ,  62 ) for calibrating the flow rate in the corresponding pocket ( 7 ,  5 ,  6 ). 
   
   
       11 . Roll with a rotating shell as claimed in  claim 10 , characterized in that the two lateral pocket units (E 3 , E 2 ), upstream ( 7 ) and downstream ( 6 ) respectively, are fed in parallel from a common pipe ( 60 ) and that the fluid feed circuit consists of two branches, a first branch feeding all middle pockets ( 5 ) via a first common pipe ( 50 ) and a second branch feeding all lateral pockets ( 6 ,  7 ) via a second common pipe ( 60 ). 
   
   
       12 . Roll with a rotating shell as claimed in  claim 11 , characterized in that each pocket unit ( 75 ,  55 ,  65 ) is associated with an open-circuit controlled feeding system, comprising one pumping device ( 83 ) for feeding the circuit with a global flow rate under a common pressure, said flow rate and said pressure being adjusted to levels at least sufficient to cause the calibrated flow rates to be discharged through all the pockets of the unit up to a maximum value of the thrust force exerted by the shell ( 1 ). 
   
   
       13 . Roll with a rotating shell as claimed in  claim 2 , characterized in that the calibrated flow rates introduced through the two lateral pockets ( 6 ,  7 ) of each pad ( 3 ) are nearly equal and that the calibrated flow introduced through the middle pocket ( 5 ) is nearly twice as high as the flow in each lateral pocket ( 6 ,  7 ). 
   
   
       14 . Roll with a rotating shell as claimed in  claim 1 , in which the tubular shell ( 1 ) rotates, during operation, in a single direction relative to support beam ( 2 ), characterized in that the middle pocket ( 5 ) of each pad ( 3 ) is centered in a radial plane slightly angularly shifted downstream, in the direction of rotation, with respect to the bearing plane (P). 
   
   
       15 . Roll with a rotating shell as claimed in  claim 14 , characterized in that the downstream lateral pocket ( 6 ) covers an angular sector of the bearing face ( 31 ) nearly twice as large as the sector covered by the upstream lateral pocket ( 7 ). 
   
   
       16 . Roll with a rotating shell as claimed in  claim 15 , characterized in that the lateral pocket ( 7 ) arranged upstream, in the direction of rotation of the shell ( 1 ) covers a sector of approx. 10° centered in a radial plane inclined at about 20° relative to the bearing plane (P) and that the lateral pocket ( 6 ) arranged downstream covers a sector of approx. 20° centered in a plane inclined at about 30° relative to the bearing plane (P). 
   
   
       17 . Roll with a rotating shell as claimed in  claim 1 , characterized in that the bearing face of each pad ( 3 ) covers an angular sector of about one quadrant, up to 100°-110°. 
   
   
       18 . Roll with a rotating shell as claimed in  claim 1 , characterized in that it is operated hydrostatically from stop to a maximum shell rotation speed, the fluid flow injected through each of the three pockets ( 5 ,  6 ,  7 ) of each pad ( 3 ) being adjusted so as to maintain a continuous oil film throughout the surface of the pad, considering that said oil is dragged out by the rotating shell ( 1 ). 
   
   
       19 . Roll with a rotating shell as claimed in  claim 1 , characterized in that it constitutes at least one of the back-up rolls in a rolling stand for metallic strip.