Patent Publication Number: US-2023141239-A1

Title: Pallet centering device

Description:
BACKGROUND 
     The present invention relates to pallet handling equipment associated with packaging systems, particularly equipment designed for packaging bags of particulate material stacked on the pallets, and more specifically to an improved device for centering loaded pallets on a conveyor line for film-wrapping. 
     Particulate materials, including building materials such as cement, plaster, mortar, drywall joint compound and the like, are conventionally packaged in paper bags ranging in weight from 25 to 100 pounds. Conventionally, the bags of a particular product and size are stacked together on a pallet. The size and shape of the pallet changes according to the type and size of bag, and the desired bag stack weight. To reduce damage from shipping or exposure to environmental moisture, the stacked pallets are wrapped in plastic film. A suitable pallet wrapping apparatus is manufactured by BEUMER Maschinenfabrik GmbH &amp; Co. KG based in Beckum, Germany. The film wrapping apparatus, sold under the trademark BEUMER stretch Hood®, is designed so that optimal results are achieved when the stacked pallet being wrapped is centered on the respective conveyor table or line. 
     As bagged product changes, either by the size of the bag or the contents, the respective pallets carrying such stacked bags will behave differently on the conveyor line. Thus, a pallet centering device needs the capability to adjust the centering action for different sizes and weights of pallets. In some factories, production lines of various sized bags and pallets are fed from respective, product-exclusive feeder conveyors to a central conveyor that feeds the bags to the film wrapping apparatus. 
     While devices are known for mechanically centering stacked pallets on conveyor tables, in many cases, the stacked pallets of paper bags of the above-described particulate building materials often weigh at least as much as 4,000 pounds. Operators have experienced the inability of existing pallet centering devices to accommodate various sizes, weights and/or shapes of stacked pallets. In addition, operators have also noted equipment failure of conventional pallet centering devices after extended exposure to such heavy pallets. 
     Accordingly, there is a need for an improved pallet centering device that is configured for reliably handling relatively heavy pallets for transmitting the pallets to a film wrapping apparatus. 
     SUMMARY 
     The above-listed need is met or exceeded by the present pallet centering device, which features an enhanced support system for accommodating relatively heavy pallets. Included in the device is a frame to which are mounted opposed, first and second pallet pusher units, each preferably extending the length of a special section of conveyor rollers located on an upper surface of the device. Preferably, the conveyor rollers are oriented transverse to the direction of travel of the pallet down a conveyor line towards pallet film wrapping apparatus. Each of the pallet pusher units includes a support plate located beneath the conveyor rollers, and has depending bearing mounts that hold preferably flanged roller bearings within at least one, transverse “U”-channel rail. The at least one “U”-channel rail is located on the support frame below the conveyor rollers. Also associated with the device is a drive system for reciprocally moving the first and second pallet pusher units towards and away from a subject pallet located on the conveyor rollers. Each of the first and second pallet pusher units is connected, as by a depending foot, to a respective power transmission member such as a drive belt or chain. The direction of rotation of a motor pulley to which the transmission members are attached causes the pallet pusher units to move towards or away from each other. 
     As such, as the pallet pusher units move towards each other, in the act of centering a subject pallet on the conveyor rollers, the respective pallet pusher units travel along the “U”-channel rail, which readily supports the heavy weight of the pallets. By using flanged roller bearings, the alignment of the roller bearings within the channel rail is maintained. 
     Another feature of each of the pallet pusher units is a biased control flap constructed and arranged so that once the subject pallet contacts the control flap, the flap is pressed against a corresponding pallet pusher member, which generates a signal sent to a control unit which is also connected to the motor controlling movement of the pallet pusher units. Preferably, each of the pallet pusher units has a plurality of such control flaps. 
     More specifically, a pallet centering device for use with a pallet conveyor line that is connected to a pallet film wrapping apparatus is provided, the pallet centering device includes, a support frame with an upper surface upon which is mounted a plurality of conveyor rollers, the support frame including a pallet entry end, an opposite pallet exit end, a first side and an opposite second side, the conveyor rollers being mounted transverse to a direction of pallet travel from the pallet entry end to the pallet exit end. 
     A first pallet pusher unit is associated with the first side of the support frame for reciprocal movement transverse to the direction of pallet travel, and a second pallet pusher unit is associated with the second side of the support frame for reciprocal movement transverse to the direction of pallet travel. The first and second pallet pusher units each have pallet pusher members configured for engaging respective sides of a pallet located on the conveyor rollers. At least one transverse U-channel rail is mounted to the support frame beneath the conveyor rollers and defining a channel track. 
     Each first and second pallet pusher unit has at least one depending bearing mount constructed and arranged for alignment with the channel track, and each bearing mount is provided with a track bearing rotatably engaging the channel track. 
     A drive assembly is associated with the support frame and is connected to the first and second pallet pusher units for moving the units reciprocally relative to the direction of travel for centering the pallet located on the conveyor rollers. 
     In an embodiment, each pallet pusher unit has a pair of depending bearing mounts having track bearings for engaging the channel track, and preferably, each track bearing has a flanged end for enhancing alignment in the channel track. 
     In a preferred embodiment, each pallet pusher member has a control flap constructed and arranged so that upon impact with the pallet, the flap depresses against the pallet pusher member, generating a signal indicating pallet contact. The device preferably further includes a control unit connected to the pallet pushers and to the drive assembly and configured for controlling movement of the pallet pusher units for achieving centering of the pallet on the conveyor rollers. 
     In an embodiment, the pallet pusher units each have openings for accommodating the conveyor rollers so that the pallet pusher units are movable transversely relative to the conveyor rollers. Also, the conveyor rollers are arranged in groups, with spaces defined between the groups in the direction of pallet travel, and the pallet pusher units are provided with supports extending in the spaces. Preferably, the supports are connected to a pusher support plate disposed beneath the conveyor rollers. 
     In a preferred embodiment, the drive assembly includes a motor associated with the support frame and connected to first and second power transmission members, each of which is associated with one of the first and second pallet pusher units, so that energization of the motor causes the reciprocal movement of the pallet pusher units relative to the conveyor rollers. Preferably, the power transmission member is one of an endless belt and a chain, and the first and second pallet pusher units each have a foot secured to the respective power transmission member. 
     In another embodiment, a pallet centering device is provided for use with a pallet conveyor line that is connected to a pallet film wrapping apparatus, and includes a support frame with an upper surface upon which is mounted a plurality of conveyor rollers, the support frame including a pallet entry end, an opposite pallet exit end, a first side and an opposite second side, the conveyor rollers being mounted transverse to a direction of pallet travel from the pallet entry end to the pallet exit end. 
     A first pallet pusher unit is associated with the first side of the support frame for reciprocal movement transverse to the direction of pallet travel, and a second pallet pusher unit associated with the second side of the support frame for reciprocal movement transverse to the direction of pallet travel. The first and second pallet pusher units each have pallet pusher members configured for engaging respective sides of a pallet located on the conveyor rollers. At least one transverse U-channel rail is mounted to the support frame beneath the conveyor rollers and defines a channel track. 
     Each first and second pallet pusher units have at least one depending bearing mount constructed and arranged for alignment with the channel track, and each bearing mount is provided with a track bearing rotatably engaging the channel track. The pallet pusher units each have a pusher support plate disposed beneath the conveyor rollers, and supports associated with the support plate and extending between spaces separating the conveyor rollers. 
     In an embodiment, a drive assembly is associated with the support frame and is connected to the first and second pallet pusher units for moving the units reciprocally relative to the direction of travel for centering the pallet located on the conveyor rollers. The drive assembly includes a motor connected to first and second power transmission members, and each pallet pusher unit includes a foot configured for attachment to the respective power transmission member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a front view of a pallet conveyor line extending to a prior art pallet film wrapping apparatus; 
         FIG.  2    is a fragmentary, top perspective view of a pallet with stacked bags entering the prior art pallet film wrapping apparatus; 
         FIG.  3    is a top side perspective view of the present pallet centering device; 
         FIG.  4    is an overhead plan view of the pallet centering device of  FIG.  3   ; 
         FIG.  5    is a front view of the present pallet centering device; 
         FIG.  6    is a schematic, fragmentary vertical cross-section of the present pallet centering device; and 
         FIG.  7    is a front view of the present pallet centering device showing a centered, stacked pallet. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS.  1  and  2   , a known arrangement of a pallet  10  bearing a stack  12  of loaded cartons ( FIG.  1   ) and bags ( FIG.  2   ), such as of the type filled with particulate material, such as construction material, such as wallboard joint compound, cement, plaster, mortar or the like, is shown traveling down a conveyor table or line  14  feeding to a film wrapping apparatus  16 . Other types of bagged particulate products are contemplated. A suitable pallet wrapping apparatus  16  is manufactured by BEUMER Maschinenfabrik GmbH &amp; Co. KG based in Beckum, Germany. The film wrapping apparatus  16 , sold under the trademark BEUMER stretch Hood®, is configured for stretching a protective plastic film over the stack  12  to prevent impact or moisture damage to the stack during shipping and storage. Further, the apparatus  16  is designed so that optimal results are achieved when the stacked pallet  12  being wrapped is centered on the respective conveyor line  14 . Included on the conveyor line  14  is a motor drive  18  that powers a series of rollers  19  suitable for moving the pallets  10  as desired. 
     Referring now to  FIGS.  3 - 5   , a pallet centering device is generally designated  20 , and is constructed and arranged to center pallets  10  travelling down the conveyor line  14  so that the film wrapping apparatus  16  works most effectively. Included on the device  20  is a support frame  22  dimensioned to have a common height with the conveyor line  14  to avoid disruption of the flow of pallets  10 . It is preferred that the support frame  22  is made of heavy duty steel or the like, preferably ½ inch thick, and is positioned along the conveyor line  14  in fairly close proximity to the film wrapping apparatus  16  to maintain the alignment of the pallet  10  once the pallet is centered. An upper surface  24  of the support frame  22  has a plurality of conveyor rollers  26  and includes a pallet entry end  28  an opposite pallet exit end  30 , a first side  32  and an opposite second side  34 . The conveyor rollers  26  are mounted transverse to a direction of pallet travel “A” ( FIG.  3   ) from the pallet entry end  28  to the pallet exit end  30 . In the preferred embodiment, the conveyor rollers  26  are disposed in groups of three rollers, with relatively wider spacing between the groups in the direction of pallet travel “A” ( FIG.  3   ). 
     A first pallet pusher unit  36  is associated with the first side  32  of the support frame  22  for reciprocal movement transverse to the direction of pallet travel “A”, and a second pallet pusher unit  38  is associated with the second side of the support frame for reciprocal movement transverse to the direction of pallet travel. Each of the first and second pallet pusher units  36 ,  38  have respective pallet pusher members  40 ,  42  configured for directly engaging respective sides of a pallet  10  located on the conveyor rollers  26  and exerting sufficient force on the pallet  10  to center the pallet on the conveyor rollers. 
     Each of the pallet pusher units  36 ,  38  have openings  44  ( FIG.  3   ) for accommodating the conveyor rollers  26  so that the pallet pusher units are movable transversely relative to the conveyor rollers. Also, it is preferred that the pallet pusher units  36 ,  38  extend substantially the entire length of the support frame  22  in the direction of travel “A”. In the preferred embodiment, the pallet pusher units  36 ,  38  are provided with supports  46  extending in the spaces. The supports  46  are each connected to a pusher support plate  48  which is part of the pallet pusher unit  36 ,  38  and is disposed beneath the conveyor rollers  26 . 
     Referring now to  FIG.  5   , at least one transverse U-channel rail  50  is mounted to the support frame  22  beneath the conveyor rollers  26  and defining a channel track  52 . The “U”-channel rail  50  is attached to, and extends horizontally between, the sides  32 ,  34  of the support frame  22 , and is preferably of the type sold by PBC Linear of Roscoe, Ill. under the trademark Hevi-Rail® channel rail or equivalent as is available in the art. Each of the first and second pallet pusher units  36 ,  38  have at least one depending bearing mount  54  constructed and arranged for alignment with the channel track  52 , and each bearing mount is provided with a track bearing  56  rotatably engaging the channel track  52 . 
     As seen in  FIGS.  5  and  6   , each pallet pusher unit  36 ,  38  has a pair of depending bearing mounts  54  having the track bearings  56  for engaging the channel track  52 . In the preferred embodiment, the track bearings  56  are cam roller bearings having a flange  58  on one end for maintaining rolling alignment in the channel track  52  ( FIG.  6   ). Also, the track bearings  56  are secured to the bearing mounts with fasteners such as bolts or the like. In a preferred embodiment, the bearings  56  are 2¾ inch size, however the size may vary to suit the application. It has been found that the use of multiple roller track bearings  56  for each pallet pusher unit  36 ,  38  significantly enhances the load-carrying capability of the pallet pusher unit, and facilitates centering of relatively heavy pallets  10 . 
     Referring now to  FIGS.  5  and  7   , a drive assembly  60  is associated with the support frame  22  and is connected to each of the first and second pallet pusher units  36 ,  38  for moving the units reciprocally relative to the direction of travel “A” and for centering the pallet  10 ′ located on the conveyor rollers  26 . Preferably, the drive assembly  60  includes a motor  62 , such as an electric motor of the type used in the conveyor art, associated with the support frame  22  and connected to first and second power transmission members  64 ,  66 , each of which is associated with one of the first and second pallet pusher units  36 ,  38 . In the preferred embodiment, the power transmission members  64 ,  66  are endless belts or chains and are connected to a dual pulley  68  associated with the motor  62 , so that energization of the motor  62  causes the reciprocal movement of the pallet pusher units  36 ,  38  relative to the conveyor rollers  26  depending on the rotational direction of the motor. Also, each of the pallet pusher units  36 ,  38  has a foot  70  that connects each unit to the respective power transmission member  64 ,  66  via fasteners. As shown in  FIG.  5   , various configurations are contemplated for the foot  70  as long as the pallet pusher unit  36 ,  38  is secured to the power transmission member  64 ,  66  for common movement. 
     Each pallet pusher member  40 ,  42  has a control flap  72  constructed and arranged so that upon impact with the pallet  10 ′, the flap depresses against the pallet pusher member, generating a signal indicating pallet contact. A control unit  74  ( FIG.  7   ) is connected to the pallet pusher units  36 ,  38  and to the drive assembly  60  and is configured for controlling movement of the pallet pusher units for achieving centering of the pallet  10 ′ on the conveyor rollers  26 . Also, the control unit  74  is optionally connected to a motor drive  76  ( FIG.  3   ) provided for powering the conveyor rollers  26 . Alternately, the motor drive  76  is independently controlled. It is contemplated that the control unit  74  is constructed and arranged for moving the pallet pusher units  36 ,  38  towards each other in unison for impacting and centering the subject pallet  10 ′, or alternately the pallet pusher units are movable sequentially as needed for centering the subject pallet on the conveyor rollers  26 . 
     While a particular embodiment of the present pallet centering device has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.