Abstract:
A tilt roller grader for grading solid objects, such as shrimp. The grader has grading rollers obliquely arranged across a tilted grading bed. Jacks in cross members supporting the bed are used to jack up the grading bed across its width to adjust the flatness of the bed for uniform grading gaps between the grading rollers and the bed.

Description:
BACKGROUND 
       [0001]    invention relates generally to apparatus for grading or sorting solid objects and more particularly to grading apparatus having gauging passages between a tilted bed and a set of parallel grading rollers obliquely arranged across the bed. 
         [0002]    Tilted graders having oblique grading rollers are used to sort objects into different sizes, or grades. Solid objects that are graded include food products such as fruits, vegetables, nuts, shellfish, portions of meat, poultry, and fish, and non-food products, such as bearings, castings, and aggregates. One kind of grader often used to grade shellfish, such as raw shrimp, comprises a grading bed tilted from a higher upstream end to a lower downstream end. Shrimp are fed onto the bed at its higher upstream end. Aided by gravity and water, the shrimp slide down the declining bed. Parallel grading rollers extend obliquely across the width of the bed. The rollers are separated from the bed by gaps, which are successively smaller from the upstream-most grading roller to the downstream-most roller. The gaps define consecutive gauging passages. Shrimp too large to fit through the gap at a grading roller are augered along the obliquely arranged roller by a helical ridge on the roller&#39;s periphery and dropped off the side of the grader into a container or onto a conveyor. The smaller shrimp pass under the grading roller to the next grading roller, whose gap is smaller. Thus, each roller sorts shrimp of a certain grade off the side of the grader. 
         [0003]    For accurate grading, the grading bed, which is typically a sheet of metal, should have a flat upper surface without bumps and dips, especially in the vicinity of the grading rollers, to maintain a uniform gap along the entire length of each grading roller. 
       SUMMARY 
       [0004]    A grader embodying features of the invention and providing uniform gauging passages and other advantages comprises a grading bed that declines from an upstream infeed end to a lower downstream end. The grading bed extends in width from a first side to a second side and provides a top grading surface and an opposite bottom surface. A support underlies the grading bed across a space. Biasing means bias the grading bed toward the support. Grading rollers having axes of rotation extend axially across the width of the grading bed oblique to the first and second sides. The grading rollers are spaced above the grading bed across gaps. Jacks extend from the support and through the space between the support and the grading bed generally along lines parallel to and proximate to the grading rollers and into contact with the bottom surface of the grading bed. The jacks are adjustable in height in the space between the support and the grading bed to maintain the top grading surface flat proximate the grading rollers for a uniform gap at each roller. 
         [0005]    Another version of a grader comprises a grading bed that declines from an upstream infeed end to a lower downstream end and extends in width from a first side to a second side. Grading rollers extending across the width of the grading bed are spaced above the grading bed across gaps. The grading rollers have axes of rotation oblique to the first and second sides. A gap-height adjuster is coupled to an end of each grading roller to adjust the height of the gap between the grading roller and the grading bed. The gap-height adjuster has a display displaying a measure of the height of the gap. 
         [0006]    Yet another version of a grader comprises a grading bed declining from an upstream infeed end to a lower downstream end and extending in width from a first side to a second side. across gaps. The grading rollers have axes of rotation oblique to the first and second sides and one or more helical grooves recessed into the rollers&#39; peripheries. 
         [0007]    Another version of a grader comprises a grading bed declining from an upstream infeed end to a lower downstream end and extending in width from a first side to a second side. Grading rollers extending across the width of the grading bed are spaced above the grading bed across gaps. A bearing assembly at an end of each of the grading rollers includes a cylindrical bearing and a bearing holder rotatably receiving the cylindrical bearing. The cylindrical bearing includes two bearing portions having confronting faces together defining a radial hole that receives one of the ends of the grading roller. A play remover biases one of the bearing portions against the other in the bearing holder to reduce play in the end of the grading roller. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    These aspects and features of the invention, as well as its advantages, are described in more detail in the following description, appended claims, and accompanying drawings, in which: 
           [0009]      FIG. 1  is a view of a tilt grader embodying features of the invention from a bottom perspective; 
           [0010]      FIG. 1A  is an enlarged view of the roller bearing portion of the grader of  FIG. 1 ; 
           [0011]      FIG. 2  is a partly cutaway view of the grader of  FIG. 1  from another perspective; 
           [0012]      FIG. 2A  is an enlarged view of the roller and roller-drive portion of the grader of  FIG. 2 ; 
           [0013]      FIG. 3  is an exploded view of a gap-height adjuster usable in a grader as in  FIG. 1  at an end of each grading roller and having an adjustment display; 
           [0014]      FIG. 4  is an exploded view of a gap-height adjuster usable in the grader of  FIG. 1  with a play remover; 
           [0015]      FIG. 5  is an unexploded view of the gap-height adjuster of  FIG. 4  showing its connection to a grading roller; 
           [0016]      FIG. 6  is an enlarged view of a lubrication system usable in a grader as in  FIG. 1 ; 
           [0017]      FIG. 7  is an exploded view of an idler pulley assembly usable in a grader as in  FIG. 1 ; 
           [0018]      FIG. 8  is a partly cutaway view of the grader of  FIG. 1  taken from another perspective; 
           [0019]      FIG. 8A  is an enlarged view of the grading bed of the grader of  FIG. 8 ; and 
           [0020]      FIG. 9  is a cross section of the grading bed and the support in the grader of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    A grader embodying features of the invention is shown in  FIG. 1 . The grader  20  comprises a grading pan, or bed  22 , supported on a slant in a frame  24 . The grading bed  22  extends from an upstream infeed end  26  to a lower downstream end  27 . Shrimp or other products to be graded are fed or deposited onto the grading bed at the infeed end  26 . A fluid pipe  28  at the infeed end flows a liquid, such as water, onto the grading bed  22  to help urge shrimp down the declining bed with the help of gravity. 
         [0022]    A plurality of grading rollers  30 —in this example, eight rollers forming eight grading zones—extend obliquely across the width of the grading pan  22  from a first side  32  to a second side  33 . The grading rollers  30  rotate on parallel axes of rotation  34  that form oblique angles a with the first and second sides  32 ,  33  of the grading bed. Each of the grading rollers  30  has an associated gap-height adjustment mechanism  36  for adjusting the gap  38  between each roller and the grading bed  22  by simultaneously raising or lowering both ends of the roller. The gauging gaps  38  decrease from upstream to downstream so that larger shrimp are sorted off the grader before smaller shrimp. Shrimp that do not fit under a given roller&#39;s gap are guided by the oblique roller towards its lower end on the second side  33  of the grader and into a container (not shown) or onto a takeaway conveyor (not shown). Narrow helical ridges  40  formed on or helical grooves  42  ( FIG. 2 ) recessed in the peripheries of the grading rollers  30  engage the shrimp that are too large for the gap and auger them along the roller and off the second side of the bed. 
         [0023]    As shown in  FIG. 1A , each grading roller  30  has an axle  44  at each end. At the first side  32  of the grader, the gap-height adjustment mechanism has a gap-height adjuster  36  with a vertically adjustable bearing assembly  48  that rotatably supports the axle  44 . The bearing assembly is fluid- or water-lubricated by a lubrication tube  50  connected to a fluid source at one end and to the bearing assembly through an adapter  52  that forms a fluid passage into the assembly. 
         [0024]    As shown in  FIGS. 2 and 2A , each grading roller  30  is rotated from a motor-driven drive shaft  54  that extends below and generally along the centerline of the grading bed. Drive pulleys  56  are arranged on the drive shaft, each drive pulley associated with one of the grading rollers. Each roller has a roller pulley  58  mounted to it near the first end  32  of the grading bed  22 . Two associated idler pulleys  60 ,  61 , supported in the frame  24  as shown in  FIG. 6 , are positioned between the drive pulley and the roller pulley. A belt  63  is trained around the drive pulley, the pair of idler pulleys, and the roller pulley to transmit the drive rotation from the drive shaft to the grading roller. The drive shaft is located somewhat distant from the roller pulley requiring a long belt length. The long belt, especially when somewhat stretchable, accommodates a range of gap-height adjustments without tightening or loosening the belt too much around the pulleys. A twisted urethane belt, such as one of those sold by DuraBelt, Inc. of Hilliard, Ohio, U.S.A., is one example of a suitable belt. 
         [0025]    As shown in  FIG. 2 , the gap-height adjustment mechanism  36  associated with each of the grading rollers  30  includes a handle  62  at each end. The handle  62  is attached to a sprocket  64  and a gap-height adjuster  66 ,  67  at each of the first and second sides  32 ,  33  of the grader. As shown in  FIGS. 3-5 , each gap-height adjuster  66 ,  67  has a threaded shaft  68 ,  69  attached at a top end to the center of the sprocket  64 . The threaded shafts are received in threaded holes  70  in the bearing assemblies  48 ,  49 . Rotation of the sprockets  64  rotates the threaded shafts, which causes the bearing assemblies to ride up or down along the shaft. 
         [0026]    As shown in  FIG. 3 , the bearing assembly  48  at the first side  32  of the grader includes a cylindrical bearing  72  that is rotatably received in a recess  74  in a bearing holder  76 . A hitch pin  78  retains the bearing  72  in the holder  76 . The bearing  72  has a radial hole  80  that receives the axle at the end of the associated grading roller. Slots  82  on diametrically opposite sides of the bearing form lubrication channels that admit lubricating fluid injected into the bearing holder  76  through the adapter  52  into the recess  74  and the bearing holder. The gap-height adjuster  66  is optionally outfitted with a display unit  84  that provides a visual indication of the size of the grading gap. The display is shown, in this example, as a counter coupled to the threaded shaft  68 . 
         [0027]    The gap-height adjuster  67  at the other side of the grader is shown in  FIGS. 4 and 5 . It is shown without a gap-height display. But it has a threaded shaft  69  that rotates with the sprocket  64 . The bearing assembly has a bearing housing  77 , which is threadedly coupled to the threaded shaft  69  to travel up and down the shaft as the sprocket  64  is rotated. Also threadedly coupled to the shaft  69  is a play remover  84  that has a hole  86  opening onto the bottom of an arm  88  that extends perpendicularly away from the shaft. The play remover travels along the shaft at the same rate as the bearing assembly. A spring  90  is seated at one end in the hole  86 . The opposite end of the spring penetrates a hole  92  in the top of the bearing holder  77  and sits on a flat surface  94  formed on the periphery of a bearing  73 . A slot  83  extends diametrically through the cylindrical bearing  73  and intersects the radial hole  80  for the roller&#39;s axle. The slot splits a portion of the bearing&#39;s length into two portions, such as legs  95 ,  95 ′, with confronting faces that define the radial hole  80 . The spring  90  exerts a compressive force against the slotted bearing  73 , pressing one of the legs toward the other. The compressive force results in a hinge action in the bearing. As the bearing wears, the hinge action maintains surface contact between the grading roller&#39;s axle and the bearing and reduces play in the end of the roller. Instead of being a one-piece split bearing joined at a hinge, the two legs  95 ,  95 ′ could be separate bearing portions of a two-piece bearing pressed toward each other by the compressive force of the spring  90  against one of the pieces and the stable backing provided to the other piece by the bearing holder  77 . The hitch pin  78  retains the bearing  73  in the holder  77 . The bearing  73  is made of polyether ether ketone (PEEK), but could be made of other plastic materials or of metal. A toothed belt or a chain  96  is trained around the sprockets  64  on the gap-height adjuster  66 ,  67  at opposite sides of the grader. In this way, the gap height can be adjusted from either side. 
         [0028]    A lubricating fluid, such as water, is supplied to the idler pulleys  60 ,  61  as shown in  FIG. 6 . The fluid is fed from a lubrication manifold  98  mounted along the side of the grader via distribution tubes  100 - 103 . The two idler pulleys  60 ,  61  associated with each grading roller are fed fluid via tubes  100 ,  101  that couple to an adapter  104 . The two gap-height-adjuster bearing holders  76 ,  77  ( FIGS. 3 and 4 ) are fed fluid via tubes  102 ,  103  that couple to the adapters  52 ,  52 ′. The four tubes for each grading-roller zone are connected to the manifold  98  by adapters  106 . (Only the tubes for one grading zone are shown in  FIG. 6  to simplify the drawing.) 
         [0029]    The idler pulley assembly  60 ,  61  is shown in more detail in  FIG. 7 . Water is fed through the adapter  104 , which is mounted on a bracket  108  attached to the grader frame. A pulley shaft  110  acts as an axle for an idler bushing  112  to ride on. Ports  114  through the shaft  110  deliver lubricating fluid to the bushing&#39;s inner contact surface  116 . An idler pulley wheel  118  has a central bore  120  that receives the bushing  112 . Set screws  122  attach the pulley wheel to the bushing. A sheave  124  on the periphery of the pulley wheel receives the drive belt ( 63 ,  FIG. 2A ). A shaft cap  126  fastened by a screw  128  captures the bushing  112  and the pulley wheel  118  in the pulley assembly  60 ,  61 . 
         [0030]    The grading bed  22  is leveled with features shown in  FIGS. 8 ,  8 A, and  9 . The grading bed  22  is supported by a support comprising a group of parallel cross members  130 . Each grading roller  30  is associated with one of the cross members  130 . Like the grading rollers, the cross members are aligned oblique to the first and second sides  32 ,  33  of the grader  20  and positioned under the grading bed generally just below the rollers. An interstitial space  132  between the bottom surface  134  of the grading bed  22  and the cross member  130  permits the grading bed to be adjusted flat. A countersunk hole  136  extends through the grading bed  22  from the top grading surface  133  to the bottom surface  134 . A flat-head screw  138  extends through the countersunk hole and into an aligned hole  140  in the supporting cross member  130 . The flat-head screw  138  has a threaded shaft  142 . An adjustment nut  144 , such as an aircraft nut, on the distal end of the screw confines a spring  146  on the shaft between the nut and a bottom face  148  of the cross member  130 . In this way, the flat-head screw, adjustment nut, and bolt serve as biasing mean biasing the grading bed  22  toward the cross member  130  across the interstitial space  132 . 
         [0031]    A jack  150  extends into the interstitial space  132  in close proximity to the flat-head screw  138 . The jack  150  comprises a jacking screw  152  and a jacking nut  154 , which is preferably a self-locking nut. The jacking nut  154  is affixed to the cross member  130  with a flange portion  156  sitting in the interstice  132  atop the cross member. A barrel portion  158  of the jacking nut extends down into the cross member. The barrel includes a threaded bore  159 . The jacking screw  152  has a threaded shaft  160  that is threadedly received in the threaded bore  159  and that extends through the jacking nut and into the interstitial space  132 . The head  162  of the jacking screw resides below the cross member for easy access. The distal tip  164  of the jacking screw is raised and lowered by adjusting the screw head  162 . As the jacking screw  150  is tightened, its tip advances through the space  132  and into contact with the bottom surface  134  of the grading bed  22 . Further tightening of the jacking screw pushes the grading bed away from the cross member against the bias of the spring  146 . The self-locking jacking nut  154  prevents vibrations from tightening or loosening the jacking screw  152  from its set position. 
         [0032]    As shown in  FIGS. 8 and 8A , the flat-head screws  138  and the jacks  150  are arranged generally in a line  166  along each cross member  130 . (The line of jacks does not have to be perfectly straight: the positions of the jacks could deviate from a straight line. So the term “line” is not restricted to the meaning “straight line.”) The line of jacks and flat-head screws is generally parallel to the axis of the associated grading roller  30 . In this way, the jacks can be adjusted to keep the grading bed flat in the vicinity of the grading roller to maintain a uniform grading gap between the roller and the top grading surface of the grading bed. The line  166  of flat-head screws is preferably positioned slightly downstream of the rollers to position the countersunk screw heads out of the grading gap. Thus, each oblique grading roller  30  is associated with a single oblique cross member  130  and a single oblique line of jacks  150  and hold-down springs  146  to enable the grading bed to be adjusted flat at each grading roller for a uniform grading gap and accurately graded product.