Abstract:
A meat grinding reclamation system is disclosed herein. The system uses a plate having a plurality of holes through which meat is processed, and a smaller number of waste material indentations that feed waste material away from the meat into separate uniform curved openings. The center of the plate is provided with a shaft opening, which allows use of a center drive shaft across the plate.

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 14/059,524 filed Oct. 22, 2013, and titled Perforated Plate for Meat Grinding Reclamation System, the disclosure of which is incorporated in its entirety by reference. 
     
    
     TECHNICAL BACKGROUND 
       [0002]    The present invention relates, in general, to a meat grinding reclamation system and, more particularly, to a system for grinding and reclaiming meat in a two-stage coaxial process. 
       BACKGROUND OF THE INVENTION 
       [0003]    Modern meat grinding systems not only grind meat, but also separate meat from undesirable material, such as gristle, hard fat, connective tissue, sinew, and bone. Such systems typically provide the unprocessed meat to a pump or screw system, which delivers the unprocessed meat to a knife rotating against a perforated plate. The knife cuts the meat into smaller pieces as the pump or screw forces the meat through the perforated plate. Centrifugal force generated by the pump or rotating screw drives the meat toward the perimeter of the plate and concentrates the undesirable material near the center of the plate. The plate typically contains an opening into a pipe that directs the undesirable material to a storage container. Once enough of the undesirable material has been collected, the undesirable material is fed through a second meat grinding system to further separate any remaining meat from the undesirable material in a reclamation process similar to that described above. The meat reclaimed from the undesirable material is then added back to the meat ground in the initial pass and the further resulting undesirable material is discarded or otherwise processed separately. 
         [0004]    One drawback associated with such prior art devices is the use of large troughs or indentations in the plate to direct waste material to the collection passage, once the waste material is separated from the meat. It would be desirable to reduce the size of the indentations, to increase the number of holes in the plate available to process the meat. 
         [0005]    Another drawback associated with such prior art devices is the placement of the waste material curved opening at the center of the plate, preventing use of the drive shaft to drive beyond the plate. It would be desirable to relocate the curved opening to allow use of the drive shaft beyond the plate. The difficulties encountered discussed here and above are substantially eliminated by the present invention. 
       SUMMARY 
       [0006]    A system for grinding and reclaiming meat is provided with a first meat grinder and a second meat grinder. Each meat grinder is provided with a perforated plate and a screw. A drive shaft is coupled to the screw of the first grinder, passed through the first perforated plate, and is coupled to the screw of the second grinder. A first rotating knife is coupled to the drive shaft near the first perforated plate, and a second knife is coupled to the drive shaft near the second perforated plate. The first perforated plate is provided with an outlet that sends undesirable material from the first grinder into the second grinder. An outlet is coupled to the second perforated plate to remove undesirable material from the second grinder. A pressurized system is coupled to the outlet of the second grinder to adjust the backpressure of the undesirable material on the meat in the second grinder. 
         [0007]    One aspect of the meat grinding assembly is the use of a single drive shaft to power the first screw, the second screw, the first knife, and the second knife. 
         [0008]    Another aspect of the meat grinding assembly relates to outlets being provided around the drive shaft in fluid communication with the second grinder. 
         [0009]    Another aspect of the meat grinding assembly is the coaxial orientation of the first meat grinder and the second meat grinder. 
         [0010]    These and other aspects will be more readily understood by reference to the following description and figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention will now be described, by way of example, with reference to the accompanying drawings in which: 
           [0012]      FIG. 1  illustrates a front perspective view of the meat grinding assembly of the present invention; 
           [0013]      FIG. 2  illustrates an exploded view of the rear of the meat grinding assembly of  FIG. 1 ; 
           [0014]      FIG. 3  illustrates an exploded view of the front of the meat grinding assembly of  FIG. 1 ; 
           [0015]      FIG. 4  illustrates a front perspective view of a first perforated plate of the meat grinding assembly of  FIG. 1 ; 
           [0016]      FIG. 5  illustrates a rear perspective view of the first perforated plate of the meat grinding assembly of  FIG. 1 ; 
           [0017]      FIG. 6  illustrates a front perspective view of the second grinder housing of the meat grinding assembly of  FIG. 1 ; 
           [0018]      FIG. 7  illustrates a front perspective view of a first stud pin of the meat grinding assembly of  FIG. 1 . 
           [0019]      FIG. 8   a  illustrates a rear elevation of a second drive shaft and flights of the meat grinding assembly of  FIG. 1 ; 
           [0020]      FIG. 8   b  illustrates a front elevation of the second drive shaft and flights of the meat grinding assembly of  FIG. 1 ; 
           [0021]      FIG. 8   c  illustrates a side elevation of the second drive shaft and flights of the meat grinding assembly of  FIG. 1 ; 
           [0022]      FIG. 9  illustrates a side elevation of the second stud pin of the meat grinding assembly of  FIG. 1 ; 
           [0023]      FIG. 10  illustrates a rear elevation of the second perforated plate of the meat grinding assembly of  FIG. 1 ; and 
           [0024]      FIG. 11  illustrates a front perspective view in partial cutaway of the meat grinding assembly of  FIG. 1 . 
       
    
    
     DESCRIPTION 
       [0025]    A meat grinding assembly is shown generally as  10  in  FIG. 1 . The embodiments of the invention described below are illustrative only and are not to be interpreted by limiting the scope of the present invention. 
         [0026]    The meat grinding assembly  10  has a first meat grinder  12  and a second meat grinder  14 . As shown in  FIG. 2 , the first meat grinder  12  is provided with a first grinder housing  16  provided with interior rifling  18  of the lands  20  and grooves  22  ( FIGS. 1-3 ). Coupled to the first grinder housing  16  is a hopper  24 , which is preferably provided with a capacity of between 1-5000 kg, more preferably between 10-2000 kg, and most preferably between 750-1250 kg. Provided within the first grinder housing  16  and hopper  24  is a first drive shaft  26  provided with a plurality of flights  28 . The first drive shaft  26  is coupled to a motor  30 . The motor  30  may be of any type known in the art and may be single speed, multiple speed, or variable speed. 
         [0027]    The first drive shaft  26  is provided with a center slot  32  into which is provided a compression spring  34 . Provided in the center slot  32  over the compression spring  34  is a first stud pin  36 . A first knife blade holder  38 , having four arms  37 , is provided with a center opening  39  only slightly larger than the diameter of the first stud pin  36 . The knife blade holder  38  may, of course, be provided with any desired number of arms  37 , or any desired configuration. The center opening  39  of the first knife blade holder  38  is provided over the first stud pin  36 , and the arms  37  of the first knife blade holder  38 , fit into mating engagement with slots  41  provided in the end of the first drive shaft  26 . The slots  41  are preferably provided slightly larger than the arms  37  of the first knife blade holder  38  to prevent undesired play between the first knife blade holder  38  and the first drive shaft  26 . 
         [0028]    Provided in the first knife blade holder  38  are four knife inserts  40 . The first knife blade holder  38  and knife inserts  40  are preferably slightly longer than prior art blades to provide a more desirable cutting stroke when used in association with the present invention. Additionally, the first knife blade holder  38  and knife inserts  40  are recessed from a first perforated plate  42  provided over the knife blade holder  38  and knife inserts  40  and retained to the first grinder housing  16  by a first ring nut  44  screwed onto mating engagement with first threads  46  provided on the exterior of the first grinder housing  16 . 
         [0029]    The first perforated plate  42  is provided with a first plurality of holes  48  ( FIGS. 3 and 4 ). While the holes may be of any desired number and diameter, in the preferred embodiment, the number of holes is between 2-10,000, more preferably between 1,000-8,000, and most preferably between about 2,000 and 7,000. In the preferred embodiment, the first perforated plate  42  is about 4 inches to 24 inches in diameter, and more preferably 11 inches in diameter and provided with a center threaded hub  50  having a drive shaft opening  52  and curved openings such as curved opening  54  and other supplemental curved openings  54  as illustrated in  FIG. 4 . While the curved openings  54  may be of any suitable dimensions and need not necessarily be curved, in the preferred embodiment, the curved openings  54  are three elongated kidney-shaped openings having a width preferably between 1-100 times the largest diameter of the holes  48 , more preferably between 2-10 times the largest diameter of the holes  48 , and most preferably between 3-5 times the largest diameter of the holes  48 . 
         [0030]    As shown in  FIG. 5 , the first perforated plate  42  is provided with an indentation  56  and other supplemental indentations  56 , each of which may be constructed with a flat, curved, sloped, or inclined surface  59  that leads to one of the curved openings  54 . The first perforated plate  42  is provided with a plate surface  57 . While the indentations  56  may be of any number or design, in the preferred embodiment, the indentations  56  are generally straight and/or elongate and extend from the edges of the curved openings  54  toward the outer edge or circumference  58  of the first perforated plate  42 . Extending the indentations  56  only partially to the perimeter of the first perforated plate  42  allows the first perforated plate  42  to be provided with more holes  48  near the perimeter. While the indentations  56  may be of any suitable configuration, as shown in  FIG. 5 , the indentations  56  preferably do not extend to within 25%, more preferably do not extend to within 40%, even more preferably do not extend to within 50%, even more preferably do not extend to within 60%, and more preferably do not extend to within 66%, of the radial distance to the perimeter of the plate  42  as measured from the center of the plate  42  to the perimeter of the plate  42 . 
         [0031]    The rotary action of the flights  28  of the first drive shaft  26 , and the knife inserts  40 , working in concert with the difference in density between the meat  136  and the undesirable material causes the undesirable material to migrate towards the axis of rotation of the first drive shaft  26  before the meat  136  and the undesirable material arrive at the first perforated plate  42 . Meat  136  approaching the outer region of the first perforated plate  42 , more than ⅓ of the radius from the center, is void of undesirable material. As such, extending the indentations  56  to the perimeter first perforated plate  42  is not required. The indentations  56  need only extend outward as far as the undesirable material is distributed when the meat  136  and the undesirable material arrives at the first perforated plate  42 . Preferably the indentations  56  extend no more than halfway, and more preferably no more than one third of the way to toward the perimeter of the first perforated plate  42 . 
         [0032]    Once at the first perforated plate  42 , the balance of the migration of the undesired material relative to the meat  136  occurs along the face of the first perforated plate  42 . With each of the indentations  56  in direct communication with one or more curved opening  54 , the distance of travel of undesirable material is minimized, allowing for less total friction and preventing plugging of the interior rifling  18 , of the indentations  56  and of the holes  48  and the stalling of collection of the undesirable material. 
         [0033]    As shown in  FIG. 2 , the first grinder housing  16  is provided with a first inlet  60  in fluid communication with the hopper  24 , a first outlet  62  defined by the holes  48  in the first perforated plate  42 , and a second outlet  64  defined by the curved openings  54  in the first perforated plate  42 . As shown in  FIG. 2  and  FIG. 4 , the first stud pin  36  extends through the drive shaft opening  52  in the first perforated plate  42 . A second grinder housing  66  is threaded onto the threaded hub  50  provided on the first perforated plate  42 . The threaded hub  50  is a left hand ACME thread. The left hand threading of the hub in the application, specifically where the grinder is performing a final grind operation and reversing the direction of auger rotation is not available, is self tightening. Preferably, the ACME threads are provided with an increased lead angle. Higher lead angle means that the torque provided by the rotation of the first drive shaft  26  cannot over tighten the second grinder housing  66 . Over a period of grinding, vibration and grinding torque causes UNC threaded connections associated with the prior art to overtighten resulting in a connection difficult to separate. The lead angle is preferably 5-20 times, more preferably 8-14 times and most preferably 11 times. This increased lead angle prevents the wedge of the threads from over tightening, resulting in a connection that is tight but easily undone after hours of grinding. 
         [0034]    The second grinder housing  66  may be of any desired configuration but is preferably provided with a cylindrical portion  68  that opens to a frusto-conical portion  70 . As shown generally in  FIG. 3 . 
         [0035]    As shown in  FIG. 6 , the interior of the second grinder housing  66  is provided with a plurality of recesses forming flutes  72  that allow the flights  74  provided on the second drive shaft  76  to move meat through the second grinder housing  66 . As shown in  FIG. 7 , the first stud pin  36  is provided with a key  78  that locks into a keyway  80  provided in the first drive shaft  26 . The first stud pin  36  is also provided with a narrower diameter shaft  82  on to which is frictionally fit the first knife blade holder  38  ( FIGS. 2, 3 and 7 ). The first stud pin  36  is also provided with a square drive  84  that fits into a square slot  88  provided in the second drive shaft  76  ( FIGS. 2, 3, 7 and 8   b ). In the preferred embodiment of the present invention, the drive shaft is constructed of the first drive shaft  26 , the first stud pin  36 , the second drive shaft  76 , and a second stud pin  92 . Alternatively, the drive shaft may be monolith, or constructed of any desired number of pieces. 
         [0036]    As shown in  FIGS. 8   a - c , the second drive shaft  76  is provided with a first set of flights  74 , and a second set of flights  75 . The pitch of the flights  74  and  75  decreases as the flights  74  and  75  extend from the rear of the second drive shaft  76  to the front of the second drive shaft  76 . The first set of flights  74  and the second set of flights  75  combine to maintain the correct pressure and centrifugal force on meat moving through the second grinder housing  66  to motivate the meat toward the exterior and concentrate undesirable material toward the center. The double wrap flighting and conical shape of the second drive shaft  76  yields better meat flow control and separation of undesirable material. The pitch of the flights  74  is constant. To generate a reduction in screw volume, the flights  75  emerge from the second drive shaft  76 . The aspect ratio between the flight thickness and the void between the flights  74  and  75  is ⅜″ thickness to 1.5″ pitch. When the flights  75  emerge from the second drive shaft  76 , the volume of the second drive shaft  76  is reduced to 50% of the original volume. This geometry functions as a choke point that limits the amount of meat and undesirable material that can be transferred through the second meat grinder  14  and causes an increase in velocity and hydrodynamic pressure. Under such conditions, the undesirable material dislodges from the meat. Immediately following the choke point, the volume of the second drive shaft  76  increases rapidly due to the conical shape of the flights  74  and  75 . The increase in volume decreases the velocity and hydrodynamic pressure and causes the dislodged undesirable material to precipitate out of the desirable meat under centrifugal force. 
         [0037]    The front end of the second drive shaft  76  is provided with a square opening  86  to accommodate the square drive  90  of the second stud pin  92 . As shown in  FIGS. 3 and 9 , the second stud pin  92  is provided with a cylindrical stop  94  and a square drive  93  to accommodate a second knife holder  98  which fits onto the square drive  93  of the second stud pin  92 . As shown in  FIG. 3 , a set of knife blades  100  is also provided over the second stud pin  92  and into engagement with the second knife holder  98 . While in the preferred embodiment, the set of knife blades  100  is monolith, the knife blades  100  may be separate and individually coupled to the second knife holder  98  either permanently, or replaceably, if desired. 
         [0038]    Provided over the front of the second grinder housing  66  is a second perforated plate  102  ( FIGS. 3 and 10 ). The second perforated plate  102  is held in place by a second ring nut  104  screwed into mating engagement with second threads  106  provided on the exterior of the second grinder housing  66 . While the second perforated plate  102  may be of any type known in the art, in the preferred embodiment, the second perforated plate  102  is a standard 5⅛″ perforated grinder plate having a plurality of holes  108  and a center threaded hub  110  defining a discharge hole  112 . The second stud pin  92  is provided with a helical groove  96  as shown in  FIG. 9  that acts as an auger to move undesirable material through the discharge hole  112 . As shown in  FIG. 3 , threaded on to the threaded hub  110  is a discharge tube  114 , preferably at least 3″ long. In this arrangement, the portion of the second grinder housing  66  provided over the curved openings  54  of the first perforated plate  42  forms an inlet  116  into the second grinder housing  66 . As shown in  FIG. 10 , holes  108  in the second perforated plate  102  provide a first outlet  118  from the second grinder housing  66  and the discharge hole  112  provides a second outlet  120  from the second grinder housing  66 . 
         [0039]    Also provided on the second perforated plate  102  are three receiving walls  150  that define three curved openings  152 . As shown in  FIG. 10 , the three receiving walls  150  are simply the interior walls of the three curved openings  152 . The curved openings  152  are similar to those described above in reference to the first perforated plate  42 . Like the first perforated plate  42 , the second perforated plate  102  is provided with a plurality of indentations  154 . As the curved openings  152  and indentations  154  are similar to one another, description will be limited to a single indentation  154  with it being understood that supplemental curved openings  152  and supplemental indentations  154  are preferably of a similar construction. 
         [0040]    The indentation  154  of the second perforated plate  102  is provided with a bottom face  158  and end wall  160 . As opposed to the semi-circular cross-sections of the indentations  56  of the first perforated plate  42 , as shown in  FIG. 10 , the cross-section of the indentation  154  of the second perforated plate  102  is rectangular, formed by a pair of opposing sidewalls  156  and the bottom face  158 . As shown in  FIG. 10 , a surface  162  of the second perforated plate  102  is coupled to the end wall  160  to define a first angle  164  there between. Similarly, the end wall  160  is coupled to the bottom face  158  to define a second angle  166  therebetween, and the sidewall  156  and the bottom face  158  define an angle  168  therebetween. The curved opening  152  is in communication with the indentation  154 . The bottom face  158  is coupled to the receiving wall  150  of the curved opening  152  to define a third angle  170  therebetween. 
         [0041]    As shown in  FIGS. 2-3 , a flexible hose  122  is secured over the discharge tube  114  with a hose clamp  124 . The flexible hose  122  preferably discharges into a waste bin  126 . As shown, an air compressor  128  is coupled via a hose  130  to straight or angled inlet  132  provided on the discharge tube  114 . Provided along the hose  130  is a valve  134 , such as those known in the art, to regulate the flow of air from the air compressor  128  into the discharge tube  114 . 
         [0042]    When it is desired to operate the meat grinding assembly  10  of the present invention, a quantity of meat  136 , which is preferably more than 500 kg, is provided into the hopper  24 . As the motor  30  turns the first drive shaft  26 , the flights  28  grab the meat  136  and move the meat  136  forward from the hopper  24  into the first inlet  60  of the first grinder housing  16 . The rifling  18  on the interior of the first grinder housing  16  co-acts with the flights  28  of the first drive shaft  26  to move the meat  136  forward, as opposed to simply spinning the meat  136  in place. The first drive shaft  26  forces the meat  136  at least partially into the holes  48  in the first perforated plate  42 . The knife inserts  40  cut and grind the meat  136  into smaller portions that the first drive shaft  26  continues to push through the holes  48  in the first perforated plate  42 . The remainder of the meat  136 , including gristle, hard fat, connective tissue, sinew, bone, and foreign contaminants are too big to fit through the holes  48  in the first perforated plate  42 . As the undesirable material is of a lower density than the meat  136 , the combination of forces from the first drive shaft  26  and knife inserts  40  imparts centrifugal forces to the meat  136  and undesirable material, pushing the undesirable material toward the center of the first perforated plate  42 . 
         [0043]    The speed of the motor  30  and pitch of the flights  28  are preferably such that rotation of the first drive shaft  26  leverages centrifugal force to drive meat  136  toward the perimeter of the first perforated plate  42  and undesirable material toward the interior of the first grinder housing  16 . The first drive shaft  26  and knife inserts  40  continue to drive the undesirable material inward until the undesirable material contacts the indentations  56  provided in the first perforated plate  42 , whereafter the pressure from meat  136  driven by the flights  28  and riffling  18  presses the undesirable material  138  along the indentations  56  and into the curved openings  54 . Because the holes  48  of the first perforated plate  42  are smaller than the undesirable material  138 , the undesirable material  138  cannot pass through the holes  48  of the first perforated plate  42 . However, since the curved openings  54  are larger than the undesirable material  138 , the undesirable material  138  exits the first grinder housing  16  through the second outlet  64  of the curved openings  54 , while the meat  136  exits the first grinder housing through the first outlet  62 . 
         [0044]    The system is designed to induct enough separated desirable meat through the curved openings  54  to ensure that all of the undesirable material is pushed through the curved openings  54 . Failure to push some desirable separated meat through the curved openings  54  along with the undesirable material allows a portion of the undesirable material to accumulate in the first grinder  12  until pressures escalate and undesirable material begins to be ground by the first grinder  12 . 
         [0045]    Exiting the first grinder housing  16  through the first perforated plate  42 , the ground meat  140  falls into a catch hopper  142  ( FIGS. 1 and 11 ). The processed material, including some desirable meat and the undesirable material  138  moves through the curved openings  54  into the second grinder housing  66  where the flights  74  and  75  coupled to the second drive shaft  76  co-act with the flutes  72  to drive the processed material  138  forward. As the flights  74  and  75  continue to contact the processed material  138 , the flights separate reclaimed meat  144  from waste material  146 , pushing the reclaimed meat  144  toward the perimeter of the second perforated plate  102  and concentrating the undesirable material  146 , and some fat as the carrier of the undesirable material  146 , toward the interior. 
         [0046]    Processed material rich in undesirable material flowing into the second grinder is moved forward by flights  74  and  75 . The geometry of the flights  74  and  75  functions as a throat, limiting the amount of processed material flowing to the second perforated plate  102 , and causes a pressure rise that aides in the separation of meat and undesirable material and helps drive the undesirable material out of the discharge tube  114 . As the flights  74  and  75  move the reclaimed meat  144  and undesirable material  146  forward, the second set of knife blades  100  cuts the reclaimed meat  144  into small enough pieces to pass through the holes  108  in the second perforated plate  102  and drives the undesirable material  146  along indentations  148  provided in the second perforated plate  102  and out the discharge hole  112  ( FIGS. 10 and 11 ). Accordingly, reclaimed meat  144  exits the second grinder housing  66  through the first outlet  118  of the holes  108  in the second perforated plate  102  while the waste material, substantially devoid of protein, with fat as the carrier, exits the second grinder housing  66  through the second outlet  120  which is the discharge hole. From the holes  108  of the second perforated plate  102 , the reclaimed meat falls into the catch hopper  142  and is processed along with the ground meat  140  as known in the art. The undesirable material  146 , however, exits the discharge hole  112  into the discharge tube  114 . As the flights  74  and  75  connected to the second drive shaft  76  continue to put pressure on the undesirable material  146 , the undesirable material  146  moves through the discharge tube  114  into the flexible hose  122  and into the waste bin  126 . In the event that the undesirable material  146  becomes stuck in the flexible hose  122 , the valve  134  is actuated to move air from the air compressor  128  into the flexible hose  122  to continue the movement of the undesirable material  146  toward the waste bin  126 . If desired, the valve  134  may be set with a predetermined amount of air pressure to keep the undesirable material  146  moving continuously into the waste bin  126  or intermittently as desired. 
         [0047]    Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited, since changes and modifications can be made therein which are within the full, intended scope of this invention, as defined by the appended claims.