Abstract:
A cradle system for a fragmenting machine, where the cradle system holds fragmentation stock against a drum. A frame holds a screen that can be selectively released from the frame without modification, such that the screen can be placed in different positions on the frame and aligned in different orientations on the frame. A wear plate can be selectively released from the frame without modification, such that the wear plate can be placed in different positions on the frame and aligned in different orientations on the frame.

Description:
[0001]    This application claims rights and priority on prior pending U.S. provisional patent application Ser. No. 62/152,936 filed 2015 Apr. 26. This invention relates to the field of fragmenting machines. More particularly, this invention relates to a cradle system for a fragmenting machine. 
     
    
     FIELD 
     INTRODUCTION 
       [0002]    Fragmenting machines, such as grinders and chippers, splinter, shred, grind, chip, or otherwise fragment waste or other stock for purposes such as disposal or recycling. Generally, such fragmenting machines include a grinding chamber defined by a grinding drum and screens. The screens, which are seated into a supporting frame, contain and force the stock into contact with the grinding drum during operation. During use, tremendous forces are generated at the point of impact when the stock strikes the screens. Particularly dimensioned openings in the screen allow fragments of the stock that have been reduced to a particular piece size to exit the grinding chamber. 
         [0003]    Such conventional screens and the wear plates that are typically disposed at the inlet to the grinding chamber (and possibly elsewhere) are not designed to be user serviceable. The wear plates may have ridges (hard facing such as weld beads) running across the top faces of the wear plates from end to end. After the ridges wear down due to repeated contact with the stock, the body of the wear plate is subject to wear from contact with the stock. When a screen becomes compromised, the lot is at risk of being ruined by an excessive amount of large piece size fragments bypassing the properly dimensioned openings through the damaged portions of the screen. 
         [0004]    Due to the high cost and inconvenience of replacing conventional screen and wear plate assemblies, some fragmentation machine operators have resorted to makeshift repair protocols to extend the usable life of the screen and wear plate assemblies. While these makeshift repair protocols allow fragmentation machine operators to defer purchasing new screens and wear plates, making repairs has a measurable cost in terms of productivity. When a screen becomes compromised or the ridges of the wear plate are worn down, operation of the fragmentation machine is stopped and at least one of the screen and the wear plate is repaired. 
         [0005]    This makeshift repair process is time consuming. Generally, the screens must first be removed and the wear plate cut or otherwise removed from the frame. The weight of conventional screens necessitates the use of a hoist or other device to lift the damaged screen off of the frame and transport it to a repair area. Typically many people are required to manipulate the damage screen due to its size and weight. 
         [0006]    The actual screen repair involves welding patch plates onto the screen to cover the enlarged openings. Once repaired, the patched screen is transported back to the frame using the hoist. Finally, the patched screen is re-seated into the frame. Instead of removing the screens, the entire frame can be moved to the repair location. However, this repair option requires heavier equipment and more room for the repair. 
         [0007]    In the case of worn ridges on the wear plate, technicians must rebuild the weld beads on the wear plates. While worn ridges do not risk contamination of the finished fragmented lot of stock, continuing to operate the fragmentation machine with worn ridges results in direct damage to the cradle and increases the frequency with which cradles must be replaced. Thus, repairing worn ridges is often performed at the end of a shift or during stoppages for screen repair. 
         [0008]    The downtime incurred when making repairs reduces the effective throughput of the fragmentation machine. In addition, each solid patch plate that is welded onto the screen restricts flow and further reduces the effective throughput of the fragmentation machine. While financially beneficial to some degree in the short run, the repairs also contribute to the degradation of the screens and the frame due to heating and cooling occurring during the welding process. 
         [0009]    Ultimately, repair or replacement of conventional screens and wear plates is time consuming and costly for the fragmentation machine owner. 
         [0010]    What is needed, therefore, is a fragmentation system that reduces issues such as those described above, at least in part. 
       SUMMARY 
       [0011]    The above and other needs are met by a cradle system for a fragmenting machine, where the cradle system holds fragmentation stock against a drum. A frame holds a screen that can be selectively released from the frame without modification, such that the screen can be placed in different positions on the frame and aligned in different orientations on the frame. A wear plate can be selectively released from the frame without modification, such that the wear plate can be placed in different positions on the frame and aligned in different orientations on the frame. 
         [0012]    In various embodiments, the frame defines a leading grinding edge at one end of the frame, and the wear plate can be selectively retained on the frame in a first orientation where a first edge of the wear plate is toward the leading grinding edge, and a second orientation where the first edge of the wear plate is away from the leading grinding edge. In some embodiments, the frame defines a leading grinding edge at one end of the frame, and a trailing grinding edge at another end of the frame, and the wear plate can be selectively released from the frame at the leading grinding edge of the frame and selectively retained on the frame at the trailing grinding edge of the frame. 
         [0013]    In some embodiments, the frame can selectively retain a plurality of screens in a plurality of different positions on the frame, and any one of the screens can be placed and selectively retained in any one of the positions on the frame. In some embodiments, the screen is selectively retained to the frame by hooks connected to a shaft that is rotatably mounted to the frame, where the hooks selectively engage and disengage a retaining bar mounted to the screen as the shaft is rotated, and the screen is selectively released from and retained on the frame by rotating the shaft. 
         [0014]    In some embodiments, the wear plate is selectively retained to the frame by posts mounted on a back surface of the wear plate, which posts engage retaining sockets fixedly mounted to the frame. In some embodiments, the wear plate is sized to be carried by one person without assistance. In some embodiments, the screen is sized to be carried by one person without assistance. 
         [0015]    According to another aspect of the invention there is described a cradle system for a fragmenting machine, where the cradle system holds fragmentation stock against a drum. A frame has a leading grinding edge and a trailing grinding edge. Retaining sockets are fixedly mounted to the frame in a first position proximate the leading grinding edge and a second position proximate the trailing grinding edge. Shafts are rotatably mounted to the frame, where each shaft has a series of hooks that rotate with the shaft as the shaft rotates. The system includes screens, where each screen has at least one mounting rod, and each of the screens can be selectively placed into any one of different positions on the frame. The screens are selectively retained on and released from the frame by rotating the shafts such that the hooks selectively engage and disengage the mounting rods. A first wear plate has retaining posts that releasably engage the retaining sockets in the first position, and a second wear plate also has retaining posts that releasably engage the retaining sockets in the second position. The first and second wear plates are swappable between the first position and the second position. 
         [0016]    In various embodiments according to this aspect of the invention, each of the wear plates have a first edge, and the wear plates can both be rotated such that the first edge of each wear plate is selectively disposed toward one of the leading grinding edge and the trailing grinding edge. In some embodiments, each of the wear plates is sized to be carried by one person without assistance. In some embodiments, each of the screens is sized to be carried by one person without assistance. 
     
    
     
       DRAWINGS 
         [0017]    Further advantages of the invention are apparent by reference to the detailed description when considered in conjunction with the figures, which are not to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein: 
           [0018]      FIG. 1  depicts a side elevation view of a portion of a fragmenting machine with a cradle system according to an embodiment of the present invention. 
           [0019]      FIG. 2  depicts a front elevation view of a cradle system according to an embodiment of the present invention. 
           [0020]      FIG. 3  depicts a rear elevation view of a cradle system according to an embodiment of the present invention. 
           [0021]      FIG. 4A  depicts a rear elevation view of a wear plate according to an embodiment of the present invention. 
           [0022]      FIG. 4B  depicts a side elevation view of a wear plate according to an embodiment of the present invention. 
           [0023]      FIG. 4C  depicts a perspective view of a wear plate according to an embodiment of the present invention. 
           [0024]      FIG. 4D  depicts a perspective view of a wear plate attached to a frame according to an embodiment of the present invention. 
           [0025]      FIG. 5  depicts a latch mechanism used to releasably secure the screens to the cradle according to an embodiment of the present invention. 
           [0026]      FIG. 6A  depicts a side elevation view illustrating various aspects of the screen according to an embodiment of the present invention. 
           [0027]      FIG. 6B  depicts a front elevation view illustrating various aspects of the screen according to an embodiment of the present invention. 
           [0028]      FIG. 6C  depicts a perspective view of a portion of the rear of the cradle system illustrating various aspects of the screen and the latch mechanism according to an embodiment of the present invention. 
           [0029]      FIG. 7  depicts a side elevation view illustrating aspects of a latch hook according to an embodiment of the present invention. 
           [0030]      FIG. 8  depicts a perspective view of a portion of the rear of the cradle system depicting various aspects of a latch mechanism engaging a latch bar so as to secure a screen to a cradle according to an embodiment of the present invention. 
           [0031]      FIG. 9  depicts a perspective view of a portion of the cradle system, viewed from the front, depicting various aspects of the latch mechanism installed in the cradle with the screens removed for clarity according to an embodiment of the present invention. 
           [0032]      FIG. 10  depicts a perspective view of a portion of the cradle system, viewed from the side, illustrating various aspects of the latch mechanism according to an embodiment of the present invention. 
           [0033]      FIG. 11  depicts a perspective view of a portion of the cradle system, viewed from the side, illustrating various aspects of the actuator and lock of the latch mechanism according to an embodiment of the present invention. 
           [0034]      FIG. 12  depicts a front elevation view illustrating aspects of the cradle according to an embodiment of the present invention. 
       
    
    
     DESCRIPTION 
       [0035]    A cradle system  100  for use with fragmenting machines  102  is described herein and illustrated in the accompanying figures. 
         [0036]      FIG. 1  is an illustration of an embodiment of the cradle system  100  in a representative fragmentation machine  102 . In the illustration, the representative fragmentation machine  102  is a horizontal grinder. The horizontal grinder  102  includes a rotating drum  104  having multiple teeth  106 . A conveyor  108  feeds a stock  110 , such as asphalt shingles or wood scraps, to the horizontal grinder  102  at an entry point  112  to the fragmentation chamber. The stock  110  has a nominal starting piece size that is generally larger than a target piece size. As the drum  104  spins, the teeth  106  break the larger pieces of the stock  110  into smaller pieces. 
         [0037]    The cradle system  100  partially surrounds the drum  104  to contain the stock  110  during fragmentation. The space between the cradle system  100  and the drum  104  generally defines the fragmentation chamber. The cradle system  100  includes a cradle  114 , one or more wear plates  116 , and one or more screens  118 . The cradle  114  provides a supporting framework for the screens  118 . The wear plates  116  are located at one or both ends  120  of the cradle  114 . In particular, one wear plate  116  is located at the end  120  of the cradle  114  associated with the entry point  112  into the horizontal grinder  102 . 
         [0038]    The screens  118  include a plurality of openings that allow pieces of the stock  110  that have been reduced to the target piece size (or smaller) to pass through to a collector. For example, the collector may include additional conveyors that carry the reduced stock  110  to a storage location (a storage pile or container), or an exchangeable container that catches finished fragments and is exchanged with another container when full. Generally, the finished fragments are collected into a lot measured in a selected unit (tons or cubic yards). 
         [0039]    The cradle system  100  is not meant to be limited to use with one particular fragmentation machine  102 , including the horizontal grinder described herein. Instead, the cradle system  100  has utility with any comminuting or fragmenting machine  102  using a powered rotary drum  104  designed to reduce stock  110  to a desired particle size measured by a filtering screen  118 . 
         [0040]      FIG. 2  is a front elevation view of one embodiment of the cradle system  100  for use with fragmentation machines  102 . The wear plates  116  and the screens  118  cover the cradle  114  and serve to insulate the cradle  114  from direct contact with the stock  110 . In the illustrated embodiment, the cradle  114  is shown with six screens  118 . Over time, repeated contact with the stock  110  results in wear on the wear plates  116  and the screens  118 . The wear plates  116  tend to experience wear on the front edge and the inner face (the side facing towards the drum  104 ). The screens  118  tend to experience wear on the surface facing the drum  104  and at the edges of the openings through the screen  118 . With highly abrasive stock  110 , such as asphalt shingles, the wear on the wear plates  116  and the screens  118  is particularly accelerated. 
         [0041]    The fundamental consequence of wear on the screens  118  is that openings through the screen  118  become enlarged. Enlargement of the openings is typically due to mechanical failure of the material between one or more openings as a result of factors including, but not limited to, the intense forces generated by the grinding drum  104  applied when the stock  110  strikes the screens  118 , and the abrasiveness of the stock  110  that is engaging the screens  118 . This results in the separate and specifically dimensioned openings that were once defined to be joined into a larger opening. 
         [0042]    The larger opening allows pieces of the stock  110  that are bigger than the target piece size to pass through to the collector  120 . Allowing too many fragments that are bigger than the target piece size to reach the collector  120  is often problematic. For example, in a commercial transaction, the entire lot may be rejected by a buyer or the purchase price reduced when a selected percentage of the finished fragments in a lot have an average piece size that exceeds the target piece size. Similarly, in a disposal scenario, the lot may be refused at a waste disposal site or the disposer may be assessed additional fees or penalties. 
         [0043]      FIG. 3  is a rear elevation view of an embodiment of the cradle system illustrating various aspects of an embodiment of the present invention. In contrast to the conventional screen  118  and frame  114  assemblies, the wear plates  116  and the screens  118  of the cradle system  100  are designed to be readily serviceable by an individual, and thereby to reduce or minimize downtime. Accordingly, the cradle  114  includes latch mechanisms  300  that releasably secure the screens  118  to the cradle  114 . The cradle  114  also includes a number of a mounting sockets  302  used to releasably mount the wear plates  116  to the cradle  114  using non-permanent fasteners  304 . 
         [0044]      FIGS. 4A to 4D  illustrate aspects of the wear plate  116 . The wear plate  116  includes a set of mounting studs  402  extending outwardly from the rear face  404  of the wear plate  116 . In use, the mounting studs  402  are aligned with the corresponding mounting sockets  302  on the cradle  114 , and are selectively secured in place by inserting the fastener  304  through the mounting sockets  302  and into the mounting studs  402 . Examples of suitable non-permanent (removable), but secure, fasteners include, without limitation, locking pins and threaded bolts. In the illustrated embodiment, the mounting studs  402  are internally threaded with female threads receiving a threaded bolt  304 . The mounting sockets  302  are optionally threaded. Alternatively, the mounting stud  402  is a threaded bolt that passes through an unthreaded mounting socket  302  and is secured using a threaded nut  304  or similar fastener. 
         [0045]    As previously mentioned, the leading edge or side of the wear plates  116  (the edge receiving the rotational direction of the drum  104  or facing the conveyor  108 ) generally wears faster than the opposite edge or side. The mounting studs  402  are symmetrically arranged on the mounting plate  116  so the spacing is identical regardless of the orientation of the wear plate  116 . Similarly, the mounting sockets  302  are symmetrically arranged on the cradle  114 . This allows the wear plates  116  to be rotated such that the trailing edge or rear side becomes the leading edge or front side of the wear plate  116 , thereby extending the usable life of the wear plate  116  (nominally doubling the usable life) without requiring any repair of the wear plate  116 . 
         [0046]    The number of mounting studs  402  and mounting sockets  302  vary from one embodiment to another, in order to provide for a secure mount for the wear plate  116 . However, using the minimum number of mounting studs  402  and mounting sockets  302  to secure each wear plate  116  to the cradle  114  facilitates faster removal and remounting of the wear plates  116 . The number of mounting studs  402  is typically equal to the number of mounting sockets  302  on the cradle  114 , but equal numbers are not required. 
         [0047]      FIG. 5  is a plan view illustrating aspects of the latch mechanism  300  that is used to releasably secure the screens  118  to the cradle  114 . The latch mechanism  300  includes a shaft  502  that carries one or more hook-shaped latches  504 . The illustrated embodiment of the shaft  502  includes optional alignment tabs  506  that extend outwardly from the shaft  502 . The alignment tabs  506  ensure that the latches  504  are properly aligned, and serve to hold the latches  504  in the proper orientation during operation. A latch actuator  508  is used to rotate the latches  504  via the shaft  502  to selectively bring the latches  504  into engagement with the screens  118  for securing the screens  118  to the cradle  114 , and to selectively disengage the latches  504  from the screens  118 , allowing the screens  118  to be removed from the cradle  114 . 
         [0048]      FIGS. 6A to 6C  illustrate aspects of the screens  118  according to the depicted embodiment. Each screen  118  generally has a concave shape facing into the drum  104 , and includes one or more latch bars  602  (shown in phantom in  FIG. 6A ) attached to the rear  604  of the screen  118 . The latch bars  602  are engaged by one or more of the latch hooks  504  to secure the screen  118  to the cradle  114 . The latch bars  602  are held away from the rear of the screen  604  by a set of arms  606  to provide clearance for the latches  504 . In the illustrated embodiment, the screen  118  has two latch bar assemblies. 
         [0049]    Furthermore, each screen  118  defines multiple particularly dimensioned openings  608  allowing the screen  118  to filter fragments of stock  110  based on piece size. As the size of the stock  110  is reduced by interaction with the drum  104 , fragments small enough to fit through the dimensions of the openings  608  pass through the screen  118  and exit the fragmentation chamber as finished fragments. Larger fragments continue to be contained within the fragmentation chamber by the screen  118  and are further reduced. As previously mentioned, a major exception to this general principle of operation occurs when the screen  118  is damaged and openings become enlarged, which allows fragments bigger than the target piece size to escape the fragmentation chamber. 
         [0050]    As with the wear plates  116 , the screens  118  are also subject to uneven wear by virtue of the rotational movement of the stock  110 . The shape of the screens  118  and the arrangement, positioning, and symmetrical nature of the latch bars  602  and the latch mechanism  300  allows the screens  118  to be rotated to extend the life to the screens  118 . 
         [0051]      FIG. 7  is a side elevation view illustrating aspects of the latches  504  according to the depicted embodiment. The body of each latch hook  504  defines a through opening  702  through which the shaft  502  of the latch mechanism  300  passes. When so installed, the shaft  502  serves as the rotation axis for the latch  504 . The through opening  702  includes a keyway  704  that registers with the alignment tab  506  on the shaft  502  to properly align the latch  504  and prevent rotation of the latch  504  about the shaft  502 . The end of the latch defines a hook  706  that captures the latch bar  602 , as show in the illustrated embodiment, when the shaft  502  is rotated by the latch actuator  508  to bring the latch hook  504  into engagement with the latch bar  602 . 
         [0052]    In the illustrated embodiment, the latch actuator  508  is a locking nut. Such an actuator  508  provides a relatively low profile, but generally requires an external tool, such as a wrench or a ratchet (hand or powered), to generate sufficient force to rotate the shaft  502 . Various embodiments of the latch actuator  508  include a handle or a gear arrangement that provide a mechanical advantage, and allow the shaft  502  to be rotated without resorting to an external tool or a motor driven actuator  508  that provides sufficient torque to rotate the shaft  502 . 
         [0053]      FIG. 8  is a perspective view depicting aspects of the latch mechanism engaging the latch bar  602  in order to secure the screen  118  to the cradle  114 . 
         [0054]      FIG. 9  is a perspective view depicting aspects of the latch mechanism installed in the cradle  114  with the screens  118  removed for clarity. Various embodiments of the cradle  114  include sides  902 , ribs  904 , and cross-members  906  that provide structural support for multiple screens  118 . In the illustrated embodiment, the two ribs  904  and the two central cross-members  906  divide the cradle  114  into six regions, with each region supporting a separate screen  118 . 
         [0055]    The separate screens  118  are smaller and, therefore, lighter than the conventional screens currently used with fragmentation machines. Further, the configuration of the latch arm assemblies also makes them available for use as handles when a person is carrying the screen  118 . These features facilitate ease of maintenance because the reduced weight generally eliminates the need for a hoist to lift and move a screen  118 , and reduces the number of people needed to manipulate the screen  118 . The reduced size and weight allows a single person to remove a damaged screen  118  and replace it or manipulate it to make repairs. The latch mechanism  300  allows screens  118  to be readily removed and attached without the need to resort to time consuming and destructive techniques, such as welding. As a result, the cradle system  100  vastly improves the effective productivity of the fragmentation machine  102  by facilitating rapid replacement or repair of damaged parts with less downtime. Furthermore, the symmetry of the parts allows them to rotated or reversed to even out wear, thereby extending the useful life the components of the cradle system  100  well beyond that obtainable with a conventional screen welded to a frame. 
         [0056]    The cradle system  100  typically includes a latch mechanism  300  for each latch bar assembly provided by the screens  118 . The latch mechanisms  300  extend across the width of the cradle  114  and through the neighboring regions. Thus, in the illustrated embodiment, there are two latch mechanisms for the bottom three regions and two additional latch mechanisms for the upper three regions. A number of latch hooks  504  are deployed within each region along the shaft  502 . The number of latch hooks  504  deployed in each region may vary based on factors, such as and without limitation, the size of the screen  118 , the weight of the screen  118 , and the forces generated by the fragmenting machine. 
         [0057]    Some embodiments orient the latch hooks  504  on the two latch mechanisms within the same region with the open ends of the hooks  706  facing in opposite directions. The opposing forces increase the tension on the screen  118 , which tends to hold the screen  118  more securely. However, facing the latch hooks  504  in opposite directions is not a requirement for suitable operation of the cradle system  100 . 
         [0058]      FIG. 10  is a perspective view of a portion of the cradle system  100  illustrating aspects of the latch mechanism according to the depicted embodiment. The latch mechanism  300  includes a lock plate  1002  that defines a pin opening  1004 . The lock plate  1002  is fixedly connected to and rotates with the shaft  502 . 
         [0059]    The outside face of the side  902  of the cradle  114  defines one or more receptacles  1006  at the same radial distance from the rotation axis defined by the shaft  502  as is the pin opening  1004 . In other words, the receptacles  1006  lie along the radial path traveled by the pin opening  1004 . At least one of the receptacles  1006  is positioned at the point where rotation of the shaft  502  brings the latch hooks  504  into operative engagement with the latch bars  602  of the screens  118 . Aspects of the latch mechanism  300  include the use of a stop  1008  that is configured to make contact with or otherwise engage the latch actuator  508  or the lock plate  1002  to limit the travel (rotation) of the shaft  502  in one or both directions, typically the direction that disengages the latch hook  504  from the latch bar  602 . 
         [0060]      FIG. 11  illustrates the latch mechanism locked into place. For example, when the latch hooks  504  are placed into engagement with the latch bars  602  of the screens  118 , the pin opening  1004  is aligned with one of the receptacles  1006 . A pin  1102  is inserted into and secured within the aligned pin opening  1004  and receptacle  1006  thereby preventing further rotation of the shaft  502  until the pin  1102  is removed. This secures the latch mechanism  300  from becoming unintentionally disengaged. 
         [0061]    In some embodiments, the pin  1102  is a threaded fastener, such as a bolt or screw, that passes through the pin opening  1004  and the receptacle  1006  is a female threaded receptacle that couples with the threaded fastener  1102 . Optionally, the pin opening  1004  may be threaded and operatively engage the pin  1102  as well. Other suitable fastening arrangements include, without limitation, a locking pin such as spring biased pin or a cotter pin used without a threaded receptacle  1006  or pin opening  1004 . Similarly, a separate fastener part, such as a wing nut or bolt, may be used to secure a threaded fastener without requiring the receptacle  1006  or pin opening  1004  to be threaded. 
         [0062]      FIG. 12  is a view of an embodiment of the cradle  114  without other components of the cradle system providing a clear view of the cradle  114  skeleton and illustrating various aspects of the cradle  114 . 
         [0063]    The foregoing description of embodiments for this invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide illustrations of the principles of the invention and its practical application, and to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.