Abstract:
A saddle for a backing assembly in a rolling mill has non-cylindrical bearing surfaces that accommodate wear by allowing the saddles to self-align. The non-cylindrical bearing surfaces help prevent the needle bearings from being pinched and driven into the gear rings. The non-cylindrical bearing surfaces are provided in different locations such as intermediate the eccentric and eccentric ring or intermediate the eccentric ring and the saddle ring.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority from U.S. Provisional Patent Application Ser. No. 60/400,573 filed Aug. 2, 2002; the disclosures of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention generally relates to metal-working rolling mills and, more particularly, to improved saddles that support the backing assemblies that support the second intermediate rolls of the mills. Specifically, the present invention relates to a saddle for a backing assembly in a cluster mill or a Z-mill wherein the saddle includes improved bearing surfaces that accommodate adjustments to reduce wear. 
   2. Background Information 
   Rolling mills such as cluster mills, 20-high cluster mills, and Z-high mills are known in the art for cold rolling metal strips. Exemplary mills are disclosed in U.S. Pat. Nos. 2,169,711; 2,187,250; 2,479,974; 2,776,586; 4,289,013; 5,471,859; and 5,481,895. These mills are commonly known as “Sendzimir” mills, “Z” mills or “Sendzimirs.” 
   A prior art cluster mill is depicted in  FIGS. 1-5  of the present patent application.  FIGS. 1-5  were originally described in U.S. Pat. No. 5,471,859 and substantial portions of this description are repeated herein for the benefit of the reader. A schematic view of a cluster mill  2  is shown in  FIG. 5 . Cluster mill  2  generally includes a pair of work rolls  12  that are supported by a set of four first intermediate rolls  13  which are in turn supported by a set of six second intermediate rolls including four driven rolls  15  and two non-driven idler rolls  14 . A strip of metal  8  passes back and forth between work rolls  12  in order for metal strip  8  to be cold rolled. 
   The second intermediate rolls  14 , 15  are supported in turn by eight backing assemblies (identified as A, B, C, D, E, F, G, and H). Each backing assembly includes a plurality of roller bearings  30  mounted upon a shaft  18 . Shaft  18  is supported at intervals along its length by saddles  19 . Each saddle  19  includes a ring  31  and a shoe  29 . Shoes  29  are mounted to a mill housing  10 . An example of mill housing  10  may be found in U.S. Pat. No. 3,815,401. Saddles  19  also include eccentrics or eccentric rings  23  that are keyed to shaft  18  with a key  24 . Each ring  23  includes a bearing surface at its outside diameter. As described below, the outer bearing surface of each ring  23  either directly engages the inner surface of saddle ring  31  or indirectly engages the inner surface of saddle ring  31 . This arrangement provides radial motion of shaft  18  when shaft  18  or ring  23  is rotated. 
   The art generally labels backing assemblies A-H and the components of backing assemblies A-H as shown in  FIG. 5 . In  FIG. 5  (the operator&#39;s side or front of mill  2 ), the left most upper assembly is labeled “A” and working clockwise around mill  2 , the remaining assemblies are labeled “B” through “H.” This labeling convention is generally followed in the art and will be followed in this specification such that the labels A-H are applied to backing assemblies and the parts of each backing assembly. 
   In the case of backing assemblies A, D, E, F, G, and H, saddles  19  are known as “plain saddles” and rings  23  mount directly within saddle rings  31  and slide within rings  31  as shafts  18  are rotated. In these plain saddles, the outer bearing surface of ring  23  directly and frictionally engages the inner bearing surface of saddle ring  31 . The direct frictional engagement between ring  23  and saddle ring  31  creates high frictional forces and does not allow shafts  18  to be adjusted under load (during rolling of metal strip  8 ). Rings  23 A,  23 D,  23 E, and  23 H are known as “side eccentrics.” Rotation of these side eccentric rings and these side eccentric shafts is used to adjust the radial position of their bearings ( 30 A,  30 D,  30 E, and  30 H) to take up wear on rolls  12 - 15 . 
   Rings  23 F and  23 G are known as the “lower screwdown eccentrics.” Rotation of shafts  18 F and  18 G (along with rings  23 F and  23 G) can be used to take up for roll wear as described above, but is more frequently used to adjust the level of the top surface of lower work roll  12 . This is known as “adjusting the pass line height” or “pass line adjustment.” 
   In the case of backing assemblies B and C, saddles  19 B and  19 C are known as “roller saddles.” In small mills that do not have a crown adjustment, the construction of backing assemblies B and C is the same as for the plane saddles, with the exception that a single row of rollers (similar to those shown at  37  in  FIG. 3 ) is interposed between the outside of each ring  23  and the inside of the mating saddle ring  31 . The addition of rollers  37  enables the shafts  18 B and  18 C and rings  23 B and  23 C to roll within saddle rings  31 B and  31 C. Rollers  37  reduce the friction sufficiently for adjustment to be made under load. This adjustment is known as the “upper screwdown” or “screwdown” and is used to adjust the roll gap (the gap between work rolls  12 ) under load. The adjustment is made by using double racks (not shown), one engaging gears  22  on shafts  18 B and  18 C at the operator&#39;s side, and one engaging gears  22  on shafts  18 B and  18 C at the drive side (see  FIG. 4 ). Each double rack is actuated by a direct acting hydraulic cylinder, and a position servo is used to control the position of the hydraulic pistons, and so control the roll gap. 
   For larger mills and other newer small mills, provision is made for individual adjustment of the radial position of shaft, bearings, and eccentric rings at each saddle position. This type of adjustment is known in the art as “crown adjustment” and the prior art construction used to achieve “crown adjustment” is generally shown in  FIGS. 1-4 . On the B and C saddles, saddle rings  31  are provided with a larger diameter bore  32 , so that a second set of rollers  33  and a ring  34  (the outside diameter of which is eccentric relative to its inside diameter) can be interposed between saddle ring  31  and rollers  37 . Rings  34  are known as “eccentric rings” or “crown adjust rings.” A gear ring  38 , having gear teeth  40 , is mounted on each side of each eccentric ring  34  and rivets  39  are used to retain gear rings  38 , eccentric  23 , eccentric ring  34 , saddle ring  31 , and shoe  29 , with two sets of rollers  33  and  37 , together as one assembly, known as the saddle assembly  19 . 
   As shown in  FIGS. 1 and 2 , a double rack  41  is used at each saddle location to engage with both sets of gear teeth  40  on each gear ring  38  on both B and C saddle assemblies  19 . A hydraulic cylinder, or motor drive jack (not shown), is used at each saddle location in order to translate rack  41 . In the example of  FIG. 4 , seven individual drives are provided with one drive positioned at each saddle location. These drives are known as “crown adjustment” drives. If one drive is operated, its respective double rack  41  moves in a vertical direction, rotating the associated gear rings  38  and eccentric rings  34 . This causes radial movement of eccentrics  23  on shafts  18 B and  18 C at the saddle location on which the eccentric rings  34  rotate, and a corresponding change in the roll gap at that longitudinal location. When this occurs, shafts  18  bend to permit the local adjustment. 
   Cluster mills of the type described above and depicted in  FIGS. 1-5  were designed to slowly shape metal strip  8  by passing strip  8  back and forth between work rolls  12  many times. In today&#39;s environment of international price competition, the cluster mills are being pushed beyond their design limits so that the shaping of metal strip  8  may be achieved with fewer passes through work rolls  12 . For instance, cluster mill  2  may be designed to adjust the shape of metal strip  8  2% with each pass through work rolls  12 . The industry is now running cluster mill  2  to change the shape up to 7% with each pass through work rolls  12 . Using cluster mill  2  in this manner increases the wear on the elements of saddles  19  requiring the owners of cluster mills  2  to replace the parts of mill  2  on a frequent maintenance schedule. Specifically, rollers  37  and  33  (also referred to as needle bearings) are pinched by the large adjustments and driven against gear rings  38 . When this type of wear occurs, the owner of cluster mill  2  must replace gear rings  38  and grind the appropriate bearing surfaces so that larger needle bearings (rollers  33  and  37 ) may be retrofit into saddle  19 . In addition to worn gear rings and rollers  33  and  37 , saddle shoes  29  become warped and must be replaced. This type of undesirable wear is likely to increase as the industry requires faster and faster mill times. The industry will continue to push existing cluster mills to perform shaping operations beyond the original design limitations of the mill creating more and more wear on saddles  19 . The art thus desires a saddle configuration that accommodates this type of cluster mill operation in order to reduce wear. Such a saddle configuration must be able to be retrofit into existing cluster mills when the saddles are being repaired. 
   BRIEF SUMMARY OF THE INVENTION 
   The invention provides a self-aligning saddle for a backing assembly in a cluster mill having improved bearing surfaces that accommodate wear. In one embodiment, the invention provides non-cylindrical bearing surfaces that prevent point stresses when a crown adjustment is made. The non-cylindrical bearing surfaces help prevent the rollers from being pinched and driven into the gear rings. 
   The invention provides the improved bearing surface in the plain saddles as well as the roller saddles. In the plain saddle embodiment, the non-cylindrical bearing surfaces are provided directly between the eccentric and the saddle ring. The non-cylindrical bearing surface may be curved concavely or convexly with respect to the eccentric. In the roller saddle embodiment, the non-cylindrical bearing surfaces are provided intermediate the eccentric and eccentric ring or intermediate the eccentric ring and the saddle ring. 
   In one embodiment, the invention replaces cylindrical roller  33  or  37  with a concave, hour glass-shaped roller that engages complementary convex surfaces formed at the outer surface of the eccentric and the inner surface of the eccentric ring or the outer surface of the eccentric ring and the inner surface of the saddle ring. The invention also provides an embodiment wherein cylindrical roller  33  or  37  of the prior art saddle is replaced with a barrel-shaped bearing having convex outer surfaces that engage a complementary concave surface formed at the outer surface of the eccentric and a curved inner surface formed at the inner surface of eccentric ring or the outer surface of the eccentric ring and the inner surface of the saddle ring. 
   Another aspect of the invention is the use of gear rings having raceways that receive cylindrical portions of the rollers. A further aspect of the invention is the use of abutment walls to retain position of the rollers. 
   The invention also provides a cluster mill that incorporates the saddles having the non-cylindrical bearing surfaces. One embodiment provides an embodiment wherein the non-cylindrical bearing surfaces are spherical bearing surfaces. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a fragmentary elevation view, partially in cross-section, of prior art backing assemblies B and C of a prior art cluster mill. 
       FIG. 2  is a fragmentary cross-sectional view taken along section line  2 - 2  of  FIG. 1  showing engagement of one crown adjusting rack and its respective gears. 
       FIG. 3  is a cross-sectional view of a typical B and C saddle assembly according to the prior art. 
       FIG. 4  is a longitudinal cross-sectional view of a typical prior art B or C backing assembly having six bearings and seven saddles. 
       FIG. 5  is a fragmentary, schematic, elevational view showing a typical prior art cluster mill, viewed from the operator&#39;s side, and showing naming terminology for the backing assemblies. 
       FIG. 6  is a perspective view of a saddle made in accordance with the concepts of the present invention. 
       FIG. 7  is a longitudinal cross-section view of a B or C backing assembly showing three saddles supporting a portion of the shaft carrying two backing assemblies. 
       FIG. 8  is an enlarged sectional view of a portion of one of the saddles of  FIG. 7 . 
       FIG. 8A  is an enlarged section view of the roller of  FIG. 8 . 
       FIG. 8B  is an enlarged section view of a portion of the gear ring of  FIG. 8 . 
       FIG. 8C  is an enlarged section view of a portion of the eccentric of  FIG. 8 . 
       FIG. 8D  is an enlarged section view of a portion of the eccentric ring of  FIG. 8 . 
       FIG. 8E  is a view similar to  FIG. 8  showing an alternative embodiment of the saddle. 
       FIG. 9  is a view similar to  FIG. 8  showing an alternative embodiment of the invention. 
       FIG. 9A  is a view similar to  FIG. 9  showing an alternative arrangement of the abutment walls. 
       FIG. 9B  is a view similar to  FIG. 9  showing an alternative embodiment of the saddle. 
       FIG. 9C  is a view similar to  FIG. 9B  showing an alternative arrangement of the abutment walls. 
       FIG. 10  is a view similar to  FIG. 8  showing a saddle made in accordance with the concepts of the present invention for a plain saddle. 
       FIG. 10A  is a view similar to  FIG. 10  showing an alternative configuration for the plain saddle. 
       FIG. 11  is an elevation view of the showing the notch that allows the rollers to be loaded into the assembly. 
   

   Similar numbers refer to similar parts throughout the specification. 
   DETAILED DESCRIPTION OF THE INVENTION 
   One exemplary saddle made in accordance with the concepts of the present invention is indicated generally by the numeral  100  in  FIG. 6 . Saddle  100  is used to support shaft  118  as depicted in  FIG. 7 . As will be described in more detail below, each saddle  100  is configured to reduce frictional wear within saddle  100  during crown adjustments. 
   Each saddle  100  generally includes a saddle shoe  129  that is connected to a saddle ring  131 . The connection between saddle shoe  129  and saddle ring  131  may be made by an appropriate bolt or other connection arrangement as is known in the art. Each saddle  100  further includes an eccentric  123  that is connected to shaft  118 . The connection between eccentric  123  and shaft  118  may be made by an appropriate connector such as the key  124  used an example in the drawings. 
   Turning first to  FIG. 8  wherein saddle  100  is a roller saddle. In the  FIG. 8  embodiment, roller saddle  100  includes a plurality of rollers  133  adapted to engage the inner surface of saddle ring  131 . Rollers  133  are depicted as being cylindrical rollers in  FIG. 8 . Rollers  133  are disposed between the inner surface of saddle ring  131  and the outer surface of a “crown adjust ring” or eccentric ring  134 . Rollers  133  and the outer surface of eccentric ring  134  are substantially similar to prior art elements  33  and  34  described above. 
   In accordance with the objectives of one of the embodiments of the present invention, the inwardly facing bearing surface  135  of eccentric ring  134  is non-cylindrical. In the embodiment of the invention depicted in  FIG. 8 , bearing surface  135  is convex such that the thickness of ring  134  is greater at its middle than in its end portions. A plurality of rollers  137  are disposed between eccentric ring  134  and eccentric  123 . The outer surface of each roller  137  is complementary to surface  135 . As such, in the embodiment of the invention depicted in  FIG. 8 , the outer surface of each roller  137  is non-cylindrical and concave. The non-cylindrical shape of roller  137  also requires the outer bearing surface  150  of eccentric  123  to be complementary to the outer surface of roller  137 . As such, outer bearing surface  150  of eccentric  123  is convex. The curvature of roller  137  as indicated by the R arrow in  FIG. 8  may be substantially equal to the outer diameter of eccentric  123  to form a spherical bearing surface. 
   Gear rings  138  are used in a manner similar to gear rings  38  described above and are thus used to retain eccentric  123 , eccentric ring  134 , saddle ring  131 , shoe  129 , and rollers  133  and  137  together as one assembly. The inner portions of gear rings  138  do not directly contact eccentric  123 . This spacing is used to accommodate pivotal movement of eccentric  123  with respect to saddle ring  131 . 
   Each gear ring  138  defines a roller raceway  152  that receives an end  154  of roller  137 . Gear ring  138  maintains the position of roller  137  when roller  137  is aligned with the notch  139  formed in eccentric  123 . In one embodiment of the invention, each end  154  has cylindrical portions  156  that are received in raceways  152 . 
   An alternative embodiment of the invention is depicted in  FIG. 8E  wherein rollers  133  are provided with the non-cylindrical bearing surface. 
   Although roller  137  is depicted as having a concave outer surface in  FIG. 8 , the inventor contemplates that roller  137  may have a convex outer surface with bearing surfaces  135  and  150  being changed to be concave to complement the outer surface of roller  137 . This embodiment is indicated generally by the numeral  200  in  FIG. 9 . 
   In this embodiment, each saddle  200  generally includes a saddle shoe  229  that is connected to a saddle ring  231 . The connection between saddle shoe  229  and saddle ring  231  may be made by an appropriate bolt or other connection arrangement as is known in the art. Each saddle  200  further includes an eccentric  223  that is connected to shaft  218 . The connection between eccentric  223  and shaft  218  may be made by an appropriate key  224 . 
   Roller saddle  200  includes a plurality of rollers  233  adapted to engage the inner surface of saddle ring  231 . Rollers  233  are depicted as being cylindrical rollers in  FIG. 8 . Rollers  233  are disposed between the inner surface of saddle ring  231  and the outer surface of a eccentric ring  234 . Rollers  233  and the outer surface of eccentric ring  234  are substantially similar to prior art elements  33  and  34  described above. 
   In accordance with the objectives of one of the embodiments of the present invention, the inwardly facing bearing surface  235  of eccentric ring  234  is non-cylindrical. In the embodiment of the invention depicted in  FIG. 8 , bearing surface  235  is concave such that the thickness of ring  234  is greater at its ends than in its middle portions. A plurality of rollers  237  are disposed between eccentric ring  234  and eccentric  223 . The outer surface of each roller  237  is complementary to surface  235 . As such, in the embodiment of the invention depicted in  FIG. 9 , the outer surface of each roller  237  is non-cylindrical and convex. The non-cylindrical shape of roller  237  also requires the outer bearing surface  250  of eccentric  223  to be complementary to the outer surface of roller  237 . As such, outer bearing surface  250  of eccentric  223  is concave. The curvature of roller  237  may be substantially equal to the outer diameter of eccentric  223 . 
   Gear rings  238  are used in a manner similar to gear rings  38  described above and are thus used to retain eccentric  223 , eccentric ring  234 , saddle ring  231 , shoe  229 , and rollers  233  and  237  together as one assembly. The inner portions of gear rings  238  do not directly contact eccentric  223 . This spacing is used to accommodate pivotal movement of eccentric  223  with respect to saddle ring  231 . 
   As may be seen in  FIG. 9 , eccentric  223  provides abutment walls  252  that are disposed adjacent the end walls of rollers  237  to prevent rollers  237  from moving longitudinally with respect to eccentric  223 . The use of abutment walls  252  prevents rollers  237  from being forced into gear rings  238 . In an alternative embodiment of the invention, abutment walls  252  are connected to eccentric ring  234  as shown in  FIG. 9A . 
   An alternative embodiments of the invention are depicted in  FIGS. 9B and 9C  wherein rollers  233  are provided with the non-cylindrical bearing surface. 
   The invention allows the eccentric to pivot with respect to the saddle ring without creating excessive frictional forces in the saddle. When the operator of the cluster mill using the saddles makes a crown adjustment, the eccentric rings are rotated which causes radial movement of the eccentrics. The radial movement of the eccentric bends the shaft causing the eccentric to pivot with respect to the saddle ring. In prior art arrangements, this pivoting motion would pinch the roller and drive it into the gear ring. In the invention depicted in  FIGS. 8 and 9 , the pivoting movement simply causes eccentric  123 , 223  to pivot or slide with respect to rollers  137 ,  237 . Rollers  137 , 237  are thus not pinched and is not driven into gear ring  138 , 238 . In the invention depicted in  FIGS. 8E and 9B , the pivoting movement simply causes eccentric  123 , 223  to pivot or slide with respect to rollers  133 ,  233 . Rollers  133 , 233  are thus not pinched and is not driven into gear ring  138 , 238 . These arrangements substantially reduce wear and allow the cluster mill using saddle  100 , 200  to be adjusted for more bending of the metal strip being worked by the cluster mill. The arrangement also transfers less force to saddle shoes  129 , 229  and prevents shoes  129 , 229  from warping. 
     FIG. 10  depicts a plain saddle embodiment made in accordance with the concepts of the present invention. In the plain saddle embodiment, the saddle is indicated generally by the numeral  300 . Saddle  300  includes eccentric  323  having an outer bearing surface  302  that is non-cylindrical and may be a spherical bearing surface. Outer bearing surface  302  of eccentric  323  engages the inner bearing surface  304  of saddle ring  331 . Bearing surface  304  complements bearing surface  302 . In the embodiment depicted in  FIG. 10 , bearing surface  302  is convex with bearing surface  304  being concave. In another embodiment of the invention shown in  FIG. 10A , bearing surface  304  may be convex (with respect to ring  331 ) with bearing surface  302  being concave (with respect to eccentric  323 ). The curvature of bearing surfaces  302  and  304  reduce wear between eccentric  323  and saddle ring  331  in a manner similar to that described above. 
   As also shown in  FIG. 10 , saddle ring  331  is formed from two pieces that are connected together around eccentric  323 . In the exemplary embodiment, saddle ring  331  is split at its centerline into a first ring  350  and a second ring  351 . Each ring  350  and  351  defines a connector opening  352  that cooperate and are coaxial when rings  350  and  351  are assembled. Openings  352  are configured to receive a connector that holds rings  350  and  351  together. The connector may be any of a variety of connectors known in the art such as bolts, screws, pins, keys, and the like. The split of ring  331  may extend across the entire radial thickness of ring  331  or only a portion of the radial thickness as shown in the drawing. The split allows eccentric  323  to be sandwiched between rings  350  and  351  during assembly of saddle  300 . In the alternative embodiment shown in  FIG. 10A , eccentric  323  is formed from two rings  360  and  361  with connector openings  362 . 
   In the roller embodiments, the rollers having the curved bearing surfaces may be installed through a notch such as notch  139  ( FIG. 11 ) defined by eccentric  123  or  223 . Notch  139  is positioned away from the majority of the load-bearing rollers so that the rollers positioned at notch  139  are not subjected to a full load during crown adjustment or mill operation. Notch  139  is sized to allow each roller to slip into place and then be rotated into position. In other embodiments of the invention, the notch is provided in other elements of the mill as required by the position of the non-cylindrical roller. The loading of the rollers through this notch (shown in  FIG. 11 ) provides a new method of assembling a saddle. 
   In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
   Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.