Patent Publication Number: US-3878703-A

Title: Rolling mills

Description:
United States Patent 1 1 Mills et al.  
 1 1 Apr. 22, 1975 [541 ROLLING MILLS [75] Inventors: Leslie Ernest Mills, Newbridge;  
 Anthony Ernest Thomas, Merthyr Tydfil. both of Wales [73] Assignee: British Steel Corporation, London.  
 England [22] Filed: Sept. 28, 1973 [21] Appl. No.: 401,644  
 [52] US. Cl 72/238; 72/245 [51] Int. Cl B2lb 31/08 [58] Field 01 Search 72/238. 239, 245  
 [56] References Cited UNITED STATES PATENTS 2.095.448 10/1937 McBane 72/245 X 3.373.589 3/1968 O&#39;Brien 72/238 3.498.098 3/1970 Bournez et a1 72/245 X 3.699.791 10/1972 Eibe 72/201 X mil 3.733.875 5/1973 Steimcr 72/21 X Primary E.\&#39;mninerMilton S. Mehr Attorney. Agent. or F irmBacon &amp; Thomas [57] ABSTRACT A rolling mill comprises at least one pair of work rolls mounted for rotation on chocks supported on the mill frame. the chocks being provided with recesses having spaced abutment surfaces against which hydraulically operated actuators mounted independently of the chocks bear. The actuators tend to separate the work rolls to maintain the required spacing at the nip between the rolls and by their independent mounting enable the rolls and chocks to be changed without disengagement of the hydraulic actuators. The actuators may be mounted so that they can be swung out of.  
 contact with their abutment surfaces on the work roll chocks.  
 6 Claims. 2 Drawing Figures PATENTEUAPRZZIQYS SHEET 1 0f 2 FIG. 7.  
 PATEHTED ZZ 3,878,703 snmznr FIG. 2.  
 ROLLING MILLS This invention relates to rolling mills and is concerned wtih the balancing of mill rolls.  
  In a conventional rolling mill the work rolls must be accurately positioned to produce at the nip between the rolls a gap appropriate tothe gauge of the material being rolled. The required roll separation is conventionally achieved by the interaction of two opposed forces operating on each roll; one such force is provided by a screwdown mechanism tending to close the gap and acting directly on the work rolls or indirectly by way of back up rolls. The second opposing force generally is provided by a mechanism usually incorporated in and acting against the chocks in which the mill rolls are supported for rotation. ln practice such a mechanism consists of a plurality of hydraulic actuators, each of which comprises a cylinder part machined into and forming a part of one chock. together with a piston part co-operating with the cylinder and arranged to bear against a suitable abutment surface on the opposed roll chock. A releasable connection to the cylinder chamber is provided on the chock itself to enable hydraulic fluid to be applied at the selected pressure.  
  In one arrangement the cylinders in the form of sleeved bores are provided in these chocks forming a support for the lower of the work rolls so that the pistons act on the chocks of the upper work roll to provide balancing pressure acting against the screwdown mechanism. This arrangement displays considerable disadvantages; for example in the case where work rolls require frequent changing. hydraulic connections to the chock cylinders require uncoupling and coupling for each roll change and makes this procedure both timeconsuming and expensive. ln addition. the uncoupling and coupling of hydraulic connections requires in most cases an electrical shut down of the mill and this additionally increases expense requiring the use of skilled personnel.  
  ln an alternative arrangement. the actuator cylinders are provided in the bottom back-up roll chocks with the pistons acting against the upper chocks of the work rolls. The opposed abutment surfaces are. in this case. provided by nesting the work roll chocks within recesses in the chocks for the back-up rolls. While this alternative arrangement avoids some of the disadvantages of the arrangement in which the actuators are incorporated in the work rolls only. it does introduce other difficulties. For example. the individual work roll and back-up roll chocks are not interchangeable; the nesting of the chock not only provides a smaller area into which the actuator cylinder can be bored but also makes a more massive mill frame necessary.  
  Both arrangements display disadvantages in the event of actuator failure. If this is due to defects in actuator components either both work rolls or back up rolls, depending upon which system has been employed will have to be removed from the mill for repair and this results in further expense and mill down time.  
  According to one aspect of the present invention. a rolling mill comprises at least a pair of work rolls which are supported for rotation in suitable chocks retained in a mill frame, together with actuators which are supported directly or indirectly on the mill frame independently of the roll chocks and are arranged to bear against abutment surfaces on the chocks whereby in use to tend to increase the gap at the nip.  
  In a preferred embodiment of the invention the actuators are hydraulic actuators and adjacent chocks of opposed rolls are recessed so as to define a cavity in which the actuators can be accommodated. In this case the upper surface of the cavity in the upper chock and the lower surface of the cavity in the lower chock act as the abutment surfaces for engagement with the actuators. It will be appreciated that by this method of construction. hydraulic connections to the actuators become independent of the roll chocks and need not be disturbed for roll changing.  
  Advantageously. each hydraulic actuator. which may be of any conventional piston and cylinder type is mounted on a support permitting the actuator to be independently moved into and out of contact with its abutment surfaces on the roll chocks. A convenient arrangement is for each actuator to be mounted for rotation upon a suitable guide which is spaced from the adjacent chocks and extends along the direction of roll adjustment. In this case the actuator may in addition be resiliently mounted upon its guide. for example. upon a collar freely slidable on the guide between the opposed ends of two springs. This arrangement provides a self-centering action for the actuator between its abutment surfaces and prevents unbalanced movement of the piston relatively to the cylinder.  
  The present invention is adaptable during roll changing to avoid the uncoupling and recoupling of hydraulic connections. not only to the actuators but also to the feeder lines supplying fluid for roll bearing and other mill lubrication. In this case hydraulic inlets to the feeders may be provided on the chock abutment surfaces with mating supply outlets being provided on the engaging surfaces of the actuators. Lubricating fluid can accordingly be applied by way of the actuators suitably adapted with passageways enabling a releasable hydraulic connection to be provided on the actuator body rather than on the mill chocks.  
  In one suitable arrangement. four actuators are symmetrically disposed around the chocks of the two work rolls. Actuators may however be suitably provided on the back-up rolls in addition to or as an alternative to those acting directly on the work rolls.  
  An embodiment of the invention will now be particularly described by way of example with reference to the accompanying drawings in which:  
  FIG. 1 is a sectional side veiw ofa hot rolling mill embodying the hydraulic actuator arrangement of the invention, and  
  PK]. 2 is a plan view of one of the mill rolls of FIG. 1 showing the disposition of hydraulic actuators.  
  Referring to FlG. l, the rolling mill. which is a hot strip rolling mill. includes. in addition to back-up rolls (not shown) two work rolls 2, 4 which define in the nip 6 between the rolls. a gap for adjustment to the gauge ofstrip being worked. Equilibrium of the work rolls 2, 4 at the selected spacing is maintained by opposed forces derived respectively from a conventional screwdown arrangement (not shown) acting. in this embodiment. on the back-up rolls. and a plurality of hydraulic actuators indicated generally at 8.  
  Work rolls 2. 4 are supported for rotation on stub axles enclosed within force or packed lubricated bearings held respectively in chocks l0, 12 which are supported within the mill frame in any of the conventional ways well known in the art.  
  In accordance with the present invention. the vertical radial faces of the chocks l0, 12 are each recessed substantially at their interface so as to form a cavity l3 effective to accommodate the hydraulic actuators 8. Each cavity in this embodiment extends horizontally along the whole width of the chock so that four actua tors can be symmetrically arranged at the four corners respectively of the chocks l0. 12 in the manner shown in FIG. 2.  
  The upper and lower faces of each cavity form abutment surfaces for engaging the working faces of the actuators. ln this embodiment each actuator is single acting and comprises a central cylinder 14 having a piston 16 projecting from the end for engagement with the upper chock on abutment surface 18. Similarly the cylinder 14 engages with the abutment surface 18 on the lower chock 12.  
  The actuator cylinder 14 is integral with the actuator body which extends into an arm 20 mounted upon a guide rod 22 lying along the direction of roll adjustment. Arm 20 contains a hydraulic inlet connection 24 which is coupled to the cylinder chamber by way of suitable passageways within the arm. ln this way the hydraulic connection to the actuator 8 is maintained inde pendently of the roll chocks l0, l2 and need not be uncoupled and recoupled for roll changing.  
  The actuator 8 is enabled to slide axially within the counterbores as shown in FIG. 1 and is centralised by the arm 20 secured between the opposed ends of two springs 26, 28 which have their other ends located by the collars 30 adjustably mounted on the rod 22.  
  The actuator 8 when operating can thus centre itself automatically within the cavity 13 by compression and relaxation of the springs so that it assumes an equilibrium position providing substantially equal excursion of the pistons 16 when hydraulic pressure is applied.  
  Similarly the pistons 16 are returned within the cylinders 14 by the compression of springs 26 and 28. In the case of roll changing this arrangement avoids the need for the back-up and bottom work roll to be removed. in the case of actuator repair, as the piston and seals may be changed with the mill in the expanded condition and this results in considerable savings being made.  
  In the embodiment illustrated the guide rod 22 is secured to the mill frame by way of recesses in the backup roll chocks 32 34. The guide rod 22 together with the other guide rods may. however. be secured by any other means which are independent of the chocks on which the complementary actuators operate.  
  It will be appreciated that the arrangement of the invention can be used also to supply fluid for work roll and other force lubrication without the need to provide releasable hydraulic connections on the chocks 10, 12. In this case lubricating connections similar to inlet 24 can be provided also on the body of the actuator 8 which is adapted to include independent passageways connecting with inlet glands on the working end faces of pistons 16. The glands are adapted for engagement with complementary glands provided in co-operating abutment surfaces of the chocks l0. l2 and coupled to the lubrication feeder lines. The glands are such as to make sealing contact when the actuator is at working pressure and enable the lubricating fluid to be applied by way of the actuator body. This arrangement also avoids the uncoupling and recoupling of lubrication connectors when the rolls are changed and results in additional savings while avoiding many of the disadvantages of previous systems.  
 We claim:  
  1. A rolling mill comprising at least a pair of work rolls which are supported for rotation in suitable chocks retained in a mill frame. a plurality of actuators which are arranged to bear against spaced abutment surfaces on the chocks whereby in use to tend to increase the gap at the nip, support means for the actuators enabling the actuators to be supported independently ofthe work roll chocks, each said support means comprising a guide spaced from the adjacent work roll chock and extending along the direction of roll adjustment. each actuator including a collar freely slidable on its guide so that each actuator is movable on its guide to an equilibrium position, each actuator being rotatable on its guide. and resilient means acting on the collar of each actuator biasing its actuator to said equilibrium position.  
  2. A rolling miss according to claim 1 in which the actuators are of a piston-cylinder type. the cylinder of each actuator carrying its respective collar, and in which the piston of each actuator is adapted to use to act in an upward direction and the cylinder in a downward direction.  
  3. A rolling mill according to claim 1 having back-up roll chocks and in which the back-up roll chocks have a plurality of opposed recesses for receiving end portions ofthe guides. the end portions of each guide being slidably located in opposed recesses in the back-up roll chocks.  
  4. A rolling mill according to claim 1 in which the resilient means of each actuator comprises two springs located on the guide on opposite sides of the collar.  
  5. A rolling mill according to claim 1 in which the adjacent chocks of opposed work rolls are recessed so as to define a cavity in which the actuators are accommodated. and the upper surface of the cavity in the upper chock and the lower surface of the cavity in the lower chock act as abutment surfaces for engagement with the actuators.  
  6. A rolling mill comprising at least a pair of work rolls which are supported for rotation in suitable chocks retained in a mill frame, a plurality of actuators which are arranged to bear against spaced abutment surfaces on the chocks whereby in use to tend to increase the gap at the nip, support means for each of said actuators enabling the actuators to be supported independently of the work roll chocks and to be movable to an equilibrium position between said abutment means. each said support means comprising a guide spaced from the adjacent work roll chock and extending along the direction of roll adjustment. each actuator including a collar mounted on its guide. each actuator being rotatable between an operative position disposed between said abutment means and an inoperative position removed from between said abutment means, and resilient means acting on the collar of each actuator biasing its actuator to said equilibrium position.