Abstract:
A turntable that can be used with a machine for wrapping loads with packaging material includes a turntable assembly having a first support assembly and a load support surface supported for rotation on the first support assembly. A second support assembly contacts a floor surface, and a plurality of load cells disposed between the first and second support assemblies space the first support assembly and the load support surface above the floor surface. In use, the load cells sense a weight of a load on the load support surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the filing benefit of U.S. Provisional Patent Application Ser. No. 61/430,724 filed on Jan. 7, 2011, which is incorporated by reference herein in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to methods and apparatus for wrapping loads with packaging material, and more particularly to apparatus for determining the weight of load wrapped by a wrapping machine. 
       BACKGROUND 
       [0003]    Various packaging techniques have been used to assemble a load of unit products and subsequently wrap them for transportation, storage, containment and stabilization, protection and waterproofing. Products are often stacked as a load on a pallet to simplify handling of the products. The pallet load is commonly wrapped with stretch wrap packaging material. One system uses stretch wrapping machines to stretch, dispense, and wrap stretch packaging material around a load. Stretch wrapping can be performed as an inline, automated packaging technique that dispenses and wraps packaging material in a stretched condition around a load on a pallet to cover and contain the load. Pallet stretch wrapping, whether accomplished by a turntable, a rotating arm, or a vertical rotating ring, typically covers the four vertical sides of the load with a stretchable film, such as polyethylene film. In each of these arrangements, relative rotation is provided between the load and the packaging material dispenser to wrap packaging material around the sides of the load. 
         [0004]    It is often desirable to determine the weight of a loaded pallet that is to be wrapped with packaging material. For example, it may be desired to determine the weight of each loaded pallet that will be placed into a truck for shipment. Conventional methods for determining the weight of a loaded pallet involve moving the loaded pallet to a scale, generally with a forklift or other equipment, and then weighing the loaded pallet. After the loaded pallet has been weighed, the load can then be moved to an appropriate stretch wrapping machine for wrapping with packaging material. Alternatively, the loaded pallet can be weighed after wrapping, by moving the wrapped load from the wrapping machine to a scale and weighing the wrapped, loaded pallet. Accordingly, weighing of the load, either before or after wrapping, requires additional processing steps that necessarily increase the time, manpower, and equipment resources needed to prepare a loaded pallet for shipping. 
         [0005]    A need therefore exists for apparatus and methods that overcome drawbacks of conventional methods and apparatus for determining the weight of a loaded pallet prior to shipment, such as those described above. 
       SUMMARY 
       [0006]    The present invention overcomes the foregoing and other shortcomings and drawbacks of convention apparatus and methods used to determine the weight of a loaded pallet prior to shipment. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications, and equivalents as may be included within the spirit and scope of the present invention. 
         [0007]    According to one aspect of the present invention, a turntable assembly for use with a wrapping machine includes a load support surface, a drive assembly for rotating the load support surface, and a first support assembly supporting the drive assembly and the load support surface. A plurality of load cell assemblies support the first support assembly and determine a value indicative of a weight of a load on the load support surface. 
         [0008]    In another aspect of the present invention, an apparatus for wrapping a load with packing material includes a turntable assembly having a first support assembly and a load support surface supported for rotation on the first support assembly. A second support assembly contacts a floor surface, and a plurality of load cell assemblies disposed between the first and second support assemblies space the first support assembly and the load support surface above the floor surface. In use, the load cell assemblies sense a weight of a load on the load support surface. Rolling elements may be disposed between the load support surface and the first support assembly to facilitate rotational movement of the load support surface relative to the first support assembly. The first support assembly may be constrained relative to the second support assembly for movement in a direction substantially parallel to a rotational axis of the load support surface. 
         [0009]    In another aspect of the invention, the apparatus for wrapping a load may further include a packing material dispenser for dispensing packing material to a load supported on the load support surface during rotation of the load support surface. The apparatus for wrapping a load may further include a display indicating the weight of the load on the load support surface based on the weight sensed by the load cell assemblies. 
         [0010]    The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention. 
           [0012]      FIG. 1  is a perspective view of an exemplary apparatus for wrapping a load, including an exemplary turntable in accordance with the principles of the present disclosure. 
           [0013]      FIG. 2 . is a perspective view of the turntable of  FIG. 1 , with a load supporting surface removed. 
           [0014]      FIG. 3  is an enlarged detail view of a portion of the turntable of  FIG. 2 . 
           [0015]      FIG. 4  is a partial elevation view of an exemplary display used with the apparatus of  FIG. 1 . 
           [0016]      FIG. 5  is a partial perspective view of a portion of another embodiment of a turntable in accordance with e principles of the present disclosure. 
           [0017]      FIG. 6  is a partial perspective view of the turntable of  FIG. 5 , from another angle. 
           [0018]      FIG. 7  is a partial cross-sectional view of the turntable of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Reference will now be made to the present embodiments of the disclosure, examples of which are illustrated in the accompanying figures. Wherever possible, the same reference numbers will be used throughout the figures to refer to the same or like parts. 
         [0020]    As shown in  FIG. 1 , a wrapping apparatus  10  includes a packaging material dispenser  12  configured to dispense packaging material  13  onto a load  16 . Packaging material dispenser  12  may be configured to travel substantially vertically up and down a support column  14  (partially shown in  FIG. 4 ) while dispensing the packaging material  13 . The vertical movement of packaging material dispenser  12  and the relative rotation between load  16  and packaging material dispenser  12  provides for wrapping of load  16  with the packaging material  13  in a spiral fashion, as would be apparent to one skilled in the art. 
         [0021]    Relative rotation between packaging material dispenser  12  and load  16  may be provided by a turntable assembly  100 , shown in  FIGS. 1-3 . Turntable assembly  100  may include a load support surface  102  upon which load  16  rests. In  FIGS. 2 and 3 , load support surface  102  has been removed to expose turntable assembly components underneath. As shown in  FIG. 2 , turntable assembly  100  includes a pulley  104 . A central portion  106  of load support surface  102  may be coupled to pulley  104  such that load support surface  102  may rotate as pulley  104  rotates. An outer portion  108  of load support surface  102  engages first rolling elements such as bearing assemblies  110 . Bearing assemblies  110  are configured to rotatably support outer portion  108  of load support surface  102 . 
         [0022]    A belt  112  operatively couples pulley  104  and a drive mechanism  114 . Belt  112  is in tension, and engages portions of pulley  104  and drive mechanism  114 . The drive mechanism  114  may include, for example, a motor (not shown) configured to engage and drive belt  112 . Belt  112 , pulley  104 , and the drive mechanism  114  may form a drive assembly. When belt  112  is driven, belt  112  causes rotation of pulley  104 , load support surface  102 , and load  16 . 
         [0023]    Pulley  104  is rotatably supported by an inner support assembly  116  of turntable assembly  100 . Bearing assemblies  110  are positioned around a lip portion  118  of inner support assembly  116 . Inner support assembly  116  is supported a selected distance above a floor surface  120  by an outer support assembly  122 . Inner support assembly  116  is coupled to outer support assembly  122  by load cell assemblies  124 . It is contemplated that inner support assembly  116  may be coupled to outer support assembly  122  by up to three load cell assemblies  124 , as shown in  FIG. 2 , or more than three load cell assemblies  124  if desired. 
         [0024]    As shown in  FIGS. 3 and 7 , load cell assembly  124  includes a rectangular element  126 . A first end  128  of rectangular element  126  rests on a pin  127  that, in turn, rests on outer support assembly  122 , as shown in  FIG. 7 . A force of the weight of load  16 , when applied to load support surface  102 , is transmitted to pins  127 . A second end  130  of rectangular element  126  is coupled to inner support assembly  116  by, for example, one or more bolts  132 . Bolts  132  may attach second end  130  to a cantilevered support  134  extending from lip portion  118  of inner support assembly  116 , as shown in  FIG. 3 . Thus, rectangular element  126  is substantially rigid with inner support assembly  116 . It will be appreciated that other types of load cell assemblies and configurations may alternatively be used as long as they are suitable for meeting space requirements and have sufficient capacity for the types of forces experienced. 
         [0025]    Each load cell assembly  124  is configured to take a weight measurement when load  16  rests on load support surface  102 , and load support surface  102  is not rotating. This helps to ensure that forces associated with rotating load support surface  102  do not reduce the accuracy of the weight measurements. The weight measurements may be combined to determine a weight of load  16 . For example, while load  16  is resting on load support surface  102 , the weight of load  16 , load support surface  102 , pulley  104 , bearing assemblies  110 , inner support assembly  116 , belt  112 , and tie bar assemblies  142  may exert a force on rectangular elements  126  of load cell assemblies  124 , causing stress on rectangular elements  126 . Each of load cell assemblies  124  may transform their respective stress levels into a signal. The signals may be sent to a controller  136 , as shown in  FIG. 4 . Controller  136  may convert the signals into weight measurements, and may add the weight measurements together, while subtracting out known weight values for load support surface  102 , pulley  104 , bearing assemblies  110 , inner support assembly  116 , belt  112 , and tie bar assemblies  142 , for example, to determine the weight of load  16 . The weight of load  16  may be displayed on a display  156 . 
         [0026]    As shown in  FIGS. 2 and 3 , inner support assembly  116  also includes cantilevered arm assemblies  138  extending in a cantilevered fashion from lip portion  118  over outer support assembly  122  to limit tilting of inner support assembly  116 . Arm assemblies  138  may be spaced apart from a top surface  154  of outer support assembly  122  by a selected distance. Second rolling elements such as wheel assemblies  140  rotatably mounted on arm assemblies  138  may rotatably support outer portion  108  of load support surface  102 . For example, when load  16  is deposited on load support surface  102  by a vehicle (not shown) (e.g., a forklift, pallet truck, or the like), the vehicle may impart intense and/or irregular forces on load support surface  102 . Wheel assemblies  140  help to ensure that those forces do not cause load support surface  102  to deflect into contact with outer support assembly  122  such as by engaging at least a portion of the load support surface  102  when a load thereon exceeds a predetermined amount. 
         [0027]    Tie bar assemblies  142  may be coupled to inner support assembly  116  and outer support assembly  122 . A first portion  144  of tie bar assembly  142  may be rotatably coupled to outer support assembly  122 , with the axis of rotation  144   a  of first portion  144  extending substantially perpendicularly from top surface  154  of outer support assembly  122 . A second portion  146  of tie bar assembly  142  may be rotatably coupled to inner support assembly  116 , with the axis of rotation of second portion  146  extending substantially perpendicularly from cantilevered support  134  extending from lip portion  118 . With this arrangement, tie bar assemblies  142  may prevent relative rotation between inner support assembly  116  and outer support assembly  122  when pulley  104  is driven by belt  112 , and may prevent tension forces exerted on pulley  104  by belt  112  from shifting inner support assembly  116  relative to outer support assembly  122 . As such, tie bar assemblies  142  may isolate load cell assemblies  138  from stresses produced by driving belt  112  and/or tension of belt  112 . It will be appreciated, however, that tie bar assemblies  142  may alternatively be coupled to inner support assembly  116  in various other ways to prevent relative rotation between inner support assembly  116  and outer support assembly  122 . 
         [0028]      FIGS. 5 and 6  depict another exemplary embodiment of a turntable assembly  200  similar to turntable assembly  100  shown and described above, wherein similar components have been similarly numbered. For example, turntable assembly  200  may include an inner support assembly  216  spaced above a floor surface, an outer support assembly  222 , bearing assemblies  210 , and a controller (not shown) similar to controller  136 . The steps for determining a weight of a load on turntable assembly  200  may be similar to the steps described above for turntable assembly  100 . 
         [0029]    One difference between turntable assembly  200  and turntable assembly  100  is that load cell assemblies  224  of turntable assembly  200  may each include a rectangular element  226  having a fixed end  248  bolted to a cantilevered portion  234  of inner support assembly  216 , and a free end  250  configured to engage a support portion  252  on outer support assembly  222 . The engagement between free end  250  and outer support assembly  222  may be through a pin (not shown), similar to the arrangement shown in  FIG. 7 . Support portion  252  may include supports, or stops,  260  configured to limit transverse movement of rectangular element  226  that may be caused by relative rotation between inner support assembly  216  and outer support assembly  222 . 
         [0030]    Another difference between turntable assembly  200  and turntable assembly  100  is that arm assemblies  238  of turntable assembly  200  are coupled to outer support assembly  222 , and extend toward inner support assembly  216 , engaging a lip portion  218  of inner support assembly  216  with wheel assemblies  240 . Arm assemblies  238  may serve to reduce or prevent relative radial movement between inner support assembly  216  and outer support assembly  222  (depicted by arrow  262  in  FIG. 6 ), caused, for example, by forces associated with at least one of a vehicle traversing turntable assembly  200  when depositing or picking up a load, or by movement of and/or tension in belt  212 . Supports  260  and arm assemblies  238  of turntable assembly  200  may perform functions similar to tie bar assemblies  142  in turntable assembly  100 . 
         [0031]    While the present invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features shown and discussed herein may be used alone or in combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of Applicants&#39; general inventive concept.