Abstract:
A mechanism for transporting a hub is provided. Particularly, a transport mechanism for a pelletizer knife hub is disclosed. The mechanism comprises a clamp for selectively engaging and releasing the shaft of the pelletizer knife hub. The clamp is connected to a support bar. The support bar, in turn, has a hoisting connector for being raised, lowered, and maneuvered by a hoisting system. According to the mechanisms of the present invention, the clamp is rotatable relative to the hoisting system. In one embodiment, a counter-balance to the hub is provided. In another arrangement, the hoisting system supports the hub above the hub for balancing the system.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application Serial No. 60/360,344, filed Feb. 28, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention pertains to an apparatus for transporting a hub, including, for example, a mechanism for transporting a pelletizer knife hub.  
           [0004]    2. Description of the Related Art  
           [0005]    Many containers and other items are manufactured from plastics. Examples include motor oil containers, fruit juice containers, trash bags, tool covers, and many other items too numerous to list. These items are often manufactured through a molding, extrusion, or blowing process. The raw material typically used in the manufacturing process is provided in the form of pellets manufactured from a polymer, such as polyethylene.  
           [0006]    Certain processes for manufacturing the pellets themselves involve the use of a pelletizer system. In many such systems, a melted plastic resin is forced through an extruder at high temperatures and pressures. The resin is forced through a die plate having up to 600 extrusion holes, with the resin being forced at pressures in excess of 600 psi. The extruded resin passes through the extrusion holes into an underwater chamber. The resin is then cut into small pieces by a series of knives which are rotated within the underwater chamber against the face of the die plate. As the resin is cut, it is cooled by circulated water, causing hardening of the material into numerous individual pellets. The pellets are then carried from the chamber downstream by the circulated water for drying and transport to customers.  
           [0007]    [0007]FIG. 1 and FIG. 2 depict a known knife hub which is rotated within a pelletizer system. FIG. 1 presents a side view of a knife hub  50  as sold under the mark KOBE™. The knife hub  50  carries a plurality of knives  52  around its outer circumference. Each knife  52  has a blade surface  53  which rides closely along the die plate (not shown) in order to cut the resin. The blades are secured to the hub  50  by bolts  55  secured through the hub  50 . Typically, 16 to 24 knives  52  are radially disposed about the outer circumference of the hub  50 .  
           [0008]    The hub  50  is rotated about a shaft  56 . The shaft  56  typically comprises an outer polygonal surface  54  which mates to a rotary motor shaft (not shown). The shaft  56  is more fully seen in the perspective view of the hub  50  in FIG. 2.  
           [0009]    The hub  50  also comprises a collar  58 . The collar  58  is offset from a body  57  of the hub  50 , leaving a gap between the collar  58  and the hub body  57 . The portion of shaft  56  residing within the gap is shown in FIG. 2 at  56 ′. Shaft  56 ′ is generally circular in cross-section in order to receive a clamp (shown in FIG. 3) for aid in transporting.  
           [0010]    It is periodically necessary to remove the knife hub  50  in order to inspect, repair, or replace the knives  52 . A pelletizer knife hub transport mechanism  10  is used to maneuver a pelletizer knife hub  50  into and out of service with a plastic resin pelletizer system.  
           [0011]    [0011]FIG. 3 presents a perspective view of a known transport mechanism  10  as is used for transporting a pelletizer knife hub, such as hub  50  shown in FIG. 2. The known transport mechanism  10  provides an elongated rail  15 . At one end of the rail  15  is a clamp  30 . The clamp  30  includes opposite clamping members  32 ,  34  which are selectively opened and closed. T-bolt  38  aids in securing and releasing the opposite clamp members  32 ,  34  in order to open and close the clamp  30 .  
           [0012]    The clamp  30  is configured to engage the shaft  56 ′ of the pelletizer knife hub  50 , such as the hub  50  shown in FIGS.  1 - 2 . To aid in transport, a hoisting system is needed. To this end, the known transport mechanism  10  provides a hoisting connector  24 . The hoisting connector  24  defines a durable member fastened to the elongated rail  15  between the opposite ends. The hoisting connector  24  typically includes an eyelet  26  or other opening configured for receiving a hook  300 . The hook  300  is connected to a hoisting system (not shown) such as a bridge crane, an arm crane, or even a stationary block and tackle for providing a mechanical advantage in maneuvering the transport mechanism  10 . One or more cables  310  connect the hoisting hook  300  to the hoisting system.  
           [0013]    To further aid in the transport of a pelletizer knife hub  50 , a counter-weight  20  is provided. The counter-weight  20  is normally positioned proximate to the hoisting connector  24  when the transport mechanism  10  is not carrying a hub  50 . However, the counter-weight  20  is slidable along the elongated rail  15  to the end opposite the clamp  30  when the clamp  30  engages the shaft  56 ′ of the hub  50 . In this way, the transport mechanism  10  is balanced.  
           [0014]    A counter-weight connector  22  is provided in order to connect the counter-weight  20  to the elongated rail  15 . The connector  22  is slidable along the elongated rail  15  in order to permit adjustment of the longitudinal position of the counter-weight  20 . However, known counter-weight connectors  22  do not swivel relative to the elongated rail  15 . Likewise, the hoisting system connector  24  does not swivel about the longitudinal rail  15 .  
           [0015]    Disadvantages have been encountered with use of the known transport mechanisms  10 . First, it is necessary during the removal and maneuvering of a knife hub  50  to rotate the knife hub  50  from its operational vertical position to a horizontal position. In this respect, knife hubs are serviced and maintenanced while they are on a work stand in the horizontal position. This typically requires that the knife hub be placed manually onto the ground in the horizontal position for subsequent transport to a maintenance area. However, as noted, the known transport mechanisms  10  have no swiveling parts, making rotation of the knife hub  50  into a horizontal position difficult.  
           [0016]    Those of ordinary skill in the art will further appreciate that the manipulation of a knife hub  50  is extremely difficult. In this respect, the knife hub typically weighs in excess of 100 pounds and cannot easily be manipulated by a single individual, even when supported by a transport mechanism  10 . Use of the currently known transport mechanisms  10  necessarily requires at least some manual manipulation of the hub  50 .  
           [0017]    Other disadvantages have been encountered in connection with known transport mechanisms  10 . For example, once a hub  50  has been removed from a pelletizer system and lowered to the ground, the clamp  30  must be removed. A crew removing a hub  50  will place the hub  50  on the ground in a horizontal position, with the clamp  30  on top of the hub  50 . The hub  50  is then typically rotated manually 180 degrees in order to set the hub  50  within a transportation box or to perform maintenance on the hub. Additional manual manipulation is required during maintenance, including subsequent manual rotation of the hub  50  in order to reattach the hub to the clamp  30  after knives  52  are installed.  
           [0018]    Examples of patents generally pertaining to apparatus that provide leverage for handling a device include U.S. Pat. Nos. 2,925,300; 4,759,674; and 5,088,610; French Patent Nos. 1,498,313; and 2,403,281. In particular U.S. Pat. No. 2,925,300, U.S. Pat. No. 5,088,610; and FR 1,498,313 disclose a material handling device which is transported through an overhead conveyance system. However, a device including a clamp which will suitably engage a pelletizer knife hub in a sufficiently secure fashion to enable transport and manipulation of the hub is not suggested.  
           [0019]    Thus, there is a need for an improved transport mechanism for a pelletizer knife hub. A need further exists for a pelletizer knife hub transport mechanism capable of rotating and otherwise manipulating a clamp while engaging the hub. Further, a need exists for a knife hub transport mechanism that swivels relative to the hoisting system.  
         SUMMARY OF THE INVENTION  
         [0020]    Mechanisms and methods for transporting a hub are provided. For example, transport mechanisms for a pelletizer knife hub are disclosed. The mechanism first comprises a clamp for selectively engaging and releasing the shaft of the pelletizer knife hub. The clamp is connected to a support bar. The support bar, in turn, has a hoisting connector for being raised, lowered, and maneuvered by a hoisting system.  
           [0021]    In certain embodiments of the present invention, the clamp is rotatable relative to the hoisting connector. In one embodiment, a counter-balance to the hub is provided. In another arrangement, the hoisting system supports the hub normally above the hub for balancing the system. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    So that the manner in which the above recited features are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof, which are illustrated in the appended drawings (FIGS.  4 - 8 ). It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
         [0023]    [0023]FIG. 1 is a side elevation view of a pelletizer knife hub. Visible in this view is the plurality of knives radially disposed about the outer circumference of the body of the hub.  
         [0024]    [0024]FIG. 2 presents a perspective view of the knife hub of FIG. 1. More fully seen in this view is the shaft arrangement for the hub.  
         [0025]    [0025]FIG. 3 presents a perspective view of a pelletizer knife hub transport mechanism of the prior art.  
         [0026]    [0026]FIG. 4 presents a perspective view of a pelletizer knife hub transport mechanism. The elongated rail and accompanying connection parts have been replaced with an elongated bar and associated parts which permit ready rotation of the clamp and counter-weight relative to the hoisting system.  
         [0027]    [0027]FIG. 5 presents a perspective view of the transport mechanism of FIG. 4. The transport mechanism has been rotated 90 degrees relative to the hoisting system.  
         [0028]    [0028]FIG. 6 presents an enlarged view of a locking pin as might be used for fixedly positioning the counter-weight along the transport mechanism of FIG. 4.  
         [0029]    [0029]FIG. 7 presents a side view of an alternate arrangement for a pelletizer knife hub transport mechanism.  
         [0030]    [0030]FIG. 8 is a perspective view of the transport mechanism of FIG. 7. 
     
    
     DETAILED DESCRIPTION  
       [0031]    [0031]FIG. 4 presents a perspective view of a transport mechanism  100  of the present invention. The transport mechanism  100  is designed and configured to transport a knife hub  50  for a plastic resin pelletizer system (not shown) or other tool having a hub.  
         [0032]    The transport mechanism  100  shown in FIG. 4 first comprises an elongated bar  110 . In the arrangement of FIG. 4, the elongated bar  110  defines a tubular body having an essentially circular cross-section. The bar  110  is preferably fabricated from steel or other durable metal alloy composition. It is understood that the bar  110  must have sufficient strength to bear the moment of a knife hub  50  that weighs in excess of 100 pounds.  
         [0033]    The transport mechanism  100  further comprises a hoisting connector  114 . The hoisting connector resides on the elongated bar  110  intermediate to opposite ends of the bar  110 . The hoisting connector  114  is configured to receive a hook  300  or other connector from a hoisting system (not shown). It is understood that the hoisting system includes one or more cables, chains, or ropes, likely drawn through a block-and-tackle or other system for obtaining a mechanical lifting advantage. In the arrangement of FIG. 4, a cable  310  is shown. It is understood, however, that the transport mechanism  100  is not limited by any particular type of hoisting system.  
         [0034]    Various configurations for a hoisting connector  114  may be employed. In the arrangement shown in FIG. 4, a bushing  114  is used as the hoisting connector. The bushing  114  is concentrically disposed about the elongated bar  110 . At the same time, the bushing  114  is configured to be able to rotate about the bar  110 . Optional retaining rings  118  are placed on either end of the bushing  114  in order to maintain the longitudinal position of the bushing  114  along the bar  110 . An optional grease zerk (not shown) may also be disposed on the outer surface of the bushing  114  in order to provide lubricant to the inner surface of the bushing  114 . An eyelet  116  is connected to the bushing  114 . The eyelet  116  is shown welded to the outer surface of the bushing  114 . The eyelet  116  is shown receiving a hook  300  from a hoisting system. While a bushing  114  and eyelet  116  arrangement is presented as the hoisting connector, it is understood that any other arrangement is within the scope of the present invention so long as the hoisting connector permits the bar  110  to rotate, or “swivel” about the radial axis of the elongated bar  110 .  
         [0035]    The transport mechanism  100  of the present invention further comprises a counter-weight  120 . The counter-weight may be of any configuration or substance, so long as it is of sufficient mass to counter-balance the knife hub  50 . In this respect, the counter-weight  120  is disposed along the bar  110  on an end of the bar  110  opposite to where the hub  50  will be engaged. In the preferred embodiment, the counter-weight  120  defines a compact cylindrical body. The weight is preferably approximately 100 pounds with the mass evenly distributed across the body  120 .  
         [0036]    In order to serve the counter-balancing function, the counter-weight  120  must be slidable along the longitudinal axis of the bar  110 . To accomplish this purpose, a counter-weight connector  124  is provided. In the depiction of FIG. 4, the counter-weight connector  124  defines a tubular bushing. The bushing  124  is radially disposed about a portion of the bar  110 . To accommodate the movement of the bushing  124  along the bar  110 , the bushing  124  preferably employs a highly polished inner surface. In one arrangement, the inner surface (not shown) defines a Teflon coating. As with the hoisting connector  114 , the counter-weight connector  124  is dimensioned to rotate about the elongated bar  110 .  
         [0037]    As noted, the counter-weight  120  is designed to slideably move along the bar  110 . To aid in this manipulation, an optional handle  128  is provided. In the depiction of FIG. 4, the handle  128  is disposed on the bushing  124 . However, it is understood that the handle  128  may be connected to the counter-weight  120  itself. Further, the handle  128  may be of any configuration.  
         [0038]    The counter-weight  120  must be connected to the counter-weight connector  124 . In the arrangement shown in FIG. 4, connection is made by welding the metal tools  120 ,  124 . However, any means of connection is within the scope of the present invention. Further, it is within the scope of the present invention to not employ a separate connection device. In this respect, the counter-weight connector could define simply a bore fabricated along the length of the counter-weight  120  itself (arrangement not shown), so long as the bar  110  is able to rotate within the bore. In such an arrangement, the bore itself would serve as the counter-weight connector.  
         [0039]    It is desirable to be able to selectively fix the position of the counter-weight  120  longitudinally along the elongated bar  110 . To aid in this selective positioning, an optional stop member  134 ′ may be fabricated into the elongated bar  110 . The stop member  134 ′ may be of any arrangement, such as a simple groove machined into the bar  110  in order to provide frictional or gravitational resistance to movement of the counter-weight  120 . In the arrangement of FIG. 4, the stop member  134 ′ defines a through-opening machined into the bar  110 . The through-opening is configured to receive a locking pin  126 . The locking pin  126  may be positioned anywhere upon either the counter-weight  120  or the counter-weight connector  124 , so long as the locking pin  126  is able to access the corresponding through-opening  134 ′ within the bar  110 . In the arrangement shown for a transport mechanism  100  of FIG. 4, the locking pin  126  is disposed upon an end of the counter-weight  120 .  
         [0040]    [0040]FIG. 6 presents an enlarged view of a locking pin  126  as might be used as part of the connector for connecting the counter-weight  120  to the bar  110 . The locking pin  126  first comprises a pin member  126 ′. The pin member  126 ′ is supported by a mounting bracket  22 . The mounting bracket  22  has a back surface  28  welded to the end of the counter-weight  120 . A spring  26  is positioned around the pin member  126 ′ intermediate opposing ends of the mounting brackets  22 . More specifically, the spring  26  is held in compression between a mounting bracket spring stop  25  and a pin member spring stop  27 . The spring  26  biases the pin member  126 ′ upward into engagement with the elongated bar  110 . The locking pin arrangement  126  includes a lower spring cap  24 L to aid in applying further compression to the spring  26  during pin  126 ′ release. The locking pin  126  also includes an upper cap  24 U disposed on the pin member  126 ′. The upper cap  24 U serves as a shoulder for the pin member  126 ′ once it is received within a through-opening, e.g.,  134 ′.  
         [0041]    It is understood that other arrangements for a locking pin  126  may be provided. The locking pin  126  presented in FIG. 6 is merely exemplary. Any arrangement which allows the counter-weight  120  to be selectively fixed in longitudinal position along the elongated bar  110  is within the scope of the present invention.  
         [0042]    [0042]FIG. 4 presents more than one through-opening  134 ′,  134 ″ for receiving the pin member  126 ′ of the locking pin  126 . The number and placement of through-openings  134 ′,  134 ″ will vary depending upon the weight of the knife hub  50 . In the preferred embodiment, a first through-opening  134 ′ is position proximate to the hoisting connector  114 . A second through-opening  134 ″ is positioned proximate to the end of the bar  110  opposite of where the hub  50  is to be engaged. The first  134 ′ and second  134 ″ through-openings are radially offset by approximately 90 degrees to permit rotation of the transport mechanism  100  and attached hub  50  during servicing or other handling of the pelletizer knife hub  50 .  
         [0043]    [0043]FIG. 5 presents a perspective view of the transport mechanism  100  of FIG. 4. In this view, the bar  110  has been rotated 90 degrees. In addition, the counter-weight  120  has been moved along the bar  110  to its second end position. The locking pin  126  is now engaged with the second through-opening  134 ″.  
         [0044]    It can be seen from FIG. 5 that the bar  110  and attached connectors  114 ,  124  are able to swivel. This swiveling feature is one of the novel aspects of the transport mechanisms of the present invention. To aid in this swiveling, an optional handle  144  is shown attached to an end of the bar  110 . The handle  144  may be of any configuration.  
         [0045]    The hub mechanism  100  of FIGS. 4 and 5 further comprises a hub clamp  130 . The clamp includes opposing clamp members  132 ,  134 . The clamp members  132 ,  134  are connected at a proximate end by a pin or bolt  136 . A separate T-bolt  138  is used to fix the position of the clamp members  132 ,  134  when they engage the shaft  56 ′ of the knife hub  50 . In this respect, those of ordinary skill in the art will understand that the clamp  130  selectively opens and closes in order to engage and release the shaft  56 ′ of the pelletizer knife hub  50 .  
         [0046]    The clamp  130  is fixed at an end of the elongated bar  110  opposite the counter-balance  120 . When the clamp  130  is dormant, i.e., not supporting a pelletizer knife hub  50 , the counter-weight  120  is in its first position proximate to the hoisting connector  114 . The locking pin  126  is inserted into the first stop member  134 ′ in order to fix the position of the counter-weight  120  proximate to the hoisting connector  114 . However, when the clamp  130  engages and supports the hub  50 , the counter-weight  120  is slid longitudinally along the bar  110  to its second position. To accomplish this repositioning, the locking pin  126  is released from the first stop member  134 ′, and is inserted into the second stop member  134 ″ proximate the end of the bar  110 . In this way, the transport mechanism  100  remains dynamically balanced.  
         [0047]    An alternate arrangement for a pelletizer knife hub transport mechanism  200  is shown in FIG. 7. FIG. 7 presents a side view of a separate transport mechanism  200 . FIG. 8 presents the transport mechanism  230  of FIG. 7, in perspective view.  
         [0048]    The transport mechanism  200  of FIGS. 7 and 8 share certain components with the transport mechanism  100  of FIGS. 4 and 5. First, transport mechanism  200  includes a clamp  230 . As with clamp  130 , clamp  230  presents opposing clamp members  232 ,  234 , which swivel about a bolt or pin  236 . A locking T-bolt  238  is provided in order to selectively fix the clamp members  232 ,  234  in a closed position.  
         [0049]    Transport mechanism  200  also includes an optional handle  244  opposite the clamp  230 . As with handle  144 , handle  244  aids in the rotational movement of the clamp  230 .  
         [0050]    The transport mechanism  200  further comprises an arcuate support bar  220 . The support bar  220  is fabricated from a material of sufficient strength to support both the transport mechanism  200  and an engaged pelletizer knife hub  50  (not shown in FIGS. 7 and 8). Preferably, steel or other strong metal alloy is employed. The support bar  220  is preferably configured to define a 90-degree arc.  
         [0051]    At an upper end  222  of the support bar  220  is disposed a hoisting connector  226 . The connector  226  is configured to receive a hook (not shown) from a hoisting system. For example, a simple through-opening  222  may be employed. In the arrangement of FIG. 7 and FIG. 8, a separate shackle  240  is utilized. In this respect, the shackle  240  is supported within a through-opening  222  of the arcuate support bar  220 , and is configured to receive a hook from the hoisting system (not shown).  
         [0052]    At a lower end  224  of the support bar  220  is a clamp connector  214 . The clamp connector  214  serves to connect the support bar  220  with the transport clamp  230 . In the arrangement of FIGS. 7 and 8, the clamp connector  214  defines a tubular bushing. The tubular bushing  214  rotates about a shaft  210 . The clamp  230  is connected to the shaft  210  at one end, while the optional handle  244  is attached to the shaft  210  at the opposite end.  
         [0053]    The bushing  214 -and-shaft  210  arrangement allows the clamp  230  to be rotated relative to the arcuate support bar  220 . In this respect, the support bar  220  is of sufficient radial dimension to permit an engaged knife hub  50  to be rotated within the circumference of the support bar  220 .  
         [0054]    In order to provide further stability to the transport mechanism  230 , the upper hoisting connector  226  is preferably disposed above the center of the shaft of the pelletizer knife hub  50  when the clamp  230  engages the shaft  56 ′. In this way, the transport mechanism  200  is provided greater stability and balance.  
         [0055]    As can be seen, an improved transport mechanism for a pelletizer knife hub has been disclosed. More specifically, various embodiments for a transport mechanism enjoying advantages and features over the transport mechanism of the prior art have been presented. It is preferred that the transport mechanisms  100 ,  200  disclosed herein and their legal equivalents, will operate to transport a KOBE™ brand pelletizer knife hub. However, the transport mechanisms of the present invention are not limited in their utility and application to any one particular style or brand of pelletizer knife hub. Further, the transport mechanisms  100 ,  200  are not limited in their utility by the number of knives  52  on the hub  50 . Further, the transport mechanisms have utility in transporting any wheel system having a shaft. It is, therefore, understood that the particular arrangements presented here and described herein arc not limiting of the scope of the invention, but are merely for example and explanation. Moreover, all patents and other documents cited herein, including priority documents, are incorporated by reference herein.