Abstract:
A pallet-handling device includes a support service adapted to supporting a pallet and at least one grasping arm. The at least one grasping arm grasps a portion of a pallet when in a pallet-grasping state. The pallet-handling device further includes an actuator. The actuator is responsive to a pallet at the support plate to cause the at least one grasping arm to be in the pallet grasping state.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from U.S. provisional patent application Ser. No. 60/481,606, filed on Nov. 6, 2003, the disclosure of which is hereby incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF INVENTION  
       [0002]     The present invention is directed to a material-handling system and, in particular, to a material-handling system for handling pallets. Such pallets are used to support one or more articles in a load.  
         [0003]     Pallets are designed primarily to be handled by forklift trucks. Thus, there are typically openings for the truck forks to engage the pallet from any side of the pallet. One such pallet, known as a “GMA” style pallet, is illustrated in  FIG. 5 . Pallet  50  includes a plurality of deck boards  52 , which are fastened to vertical stringers  54 . The bottoms of the stringers are joined by bottom slats  58 . In order to engage the GMA style pallet from the side, a pair of cutouts  56  is provided for receiving the forks of the truck.  
         [0004]     Automated material-handling systems are available that handle pallet  50  without the use of forks. In a known automated material-handling system  110 , pallet  50  is supported in a rest position by blocks, or rails,  60  ( FIG. 5 ). By way of example, in an automatic storage and retrieval system (ASRS), a carriage (not shown) includes a pair of blocks  60 , which supports the pallet in a rest position. A pallet-handling device  112  is supported by a pair of supports  15  of system  110  and includes a pallet support plate  114  which is used to lift the pallet and transport the pallet, such as to a location on a rack. Another pair of blocks or rails  60  is at each location in the rack in order to, again, supports the pallet when in storage in the rack.  
         [0005]     A difficulty with the pallet-handling device  112  in  FIG. 5  is that, because of the presence of cutouts  56 , a pivot point P exists between the pallet support plate  114  and the deck board  58  closest to the cutout. Thus, an uneven load having a center of gravity outside of point P may cause the entire pallet and load to pivot about point P and thereby tip and dump the articles on the pallet. While solutions have been proposed to this vexing problem, none have been entirely satisfactory.  
       SUMMARY OF INVENTION  
       [0006]     A pallet-handling device, which is capable of stably transporting a pallet loaded with articles, is provided according to the invention. According to an aspect of the invention, a pallet-handling device includes a support service adapted to supporting a pallet and at least one grasping arm. The at least one grasping arm grasps a portion of a pallet when in a pallet-grasping state. The pallet-handling device further includes an actuator. The actuator is responsive to a pallet at the support plate to cause the at least one grasping arm to be in the pallet grasping state.  
         [0007]     In this manner, a pallet is securely grasped by the pallet-handling device, both while being raised and lowered and during transportation thereby significantly reducing the likelihood of spillage of the articles being supported by the pallet.  
         [0008]     These and other objects, advantages and features of this invention will become apparent upon review of the following specification in conjunction with the drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0009]      FIG. 1  is a side elevation of a pallet containment system, according to an embodiment of the invention;  
         [0010]      FIG. 2  is an end elevation of the pallet containment system in  FIG. 1 ;  
         [0011]      FIG. 3  is a bottom plan view of the pallet containment system in  FIG. 2 ;  
         [0012]      FIG. 4  is the same view as  FIG. 2  with the pallet being grasped by the pallet containment system; and  
         [0013]      FIG. 5  is the same view as  FIG. 4  of a prior art pallet-handling device. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]     Referring now specifically to the drawings, and the illustrative embodiments depicted therein, a pallet containment system  10  includes a pallet-handling device  112 , which is supported by a load-handling device  13  ( FIGS. 2 and 4 ). The load-handling device includes a pair of supports  15 . Examples of load-handling devices with which the pallet-handling device  112  is compatible include, without limitation, automatic storage and retrieval systems (ASRS), automatic-guided vehicles (AGVs), forklift trucks, and the like. In the illustrative embodiment, the load-handling device is an ASRS having a pair of supports  15  which are multiple extendable members as is well known in the art. Pallet-handling device  112  includes a pallet support plate  14 , which is carried by supports  15  of load-handling device  13 . Pallet support plate  14  includes a support surface  16 , which carries the pallet  50  during transport of the pallet.  
         [0015]     Pallet-handling device  112  includes an actuator assembly  20  and one or more grasping arms  18 . Actuator assembly  20  includes a plunger  22  and a clamp plate  24  which are interconnected by shafts  26 . Shafts  26  ride in linear bearings  28  such that shafts  26  are capable of vertical reciprocation. A compression spring  30  on each shaft  26  provides an energy bypass mechanism to absorb any impact applied to grasping arms  18 .  
         [0016]     Grasping arms  18  are pivotally supported by a shaft  40 , which is supported by pillow block bearings  41 . As can been seen in  FIG. 3 , grasping arms  18  may be grouped together in multiple assemblies, which, in the illustrative embodiment, includes four assemblies of grasping arms, each supported by a shaft and a pair of pillow block bearings. Each grasping arm  18  includes a grasping finger  44 , which is a general L-shape, and a cam surface  42  opposite finger  44 . Grasping arms  18  are biased in a non-grasping state. As illustrated in  FIG. 2 , by an extension spring  36  extending between opposing sets of grasping arms, other techniques, such as weights or other spring arrangements, may also be utilized to bias grasping arms in a non-grasping state.  
         [0017]     One or more compression devices, such as gas springs  32 , are used to bias actuator assembly  20  in a non-actuated position. In the illustrative embodiment, the non-actuated position of actuator assembly  20  is with plunger  22  elevated above support surface  16 .  
         [0018]     In operation, the load-handling device positions pallet-handling device  112  under a pallet  50 . Upward movement of load-handling device  13  applies the weight of the pallet to actuator assembly  20 . Further upward movement of the load-handling device causes plunger assembly  20  to move downwardly. The downward movement causes clamp plate  24  to engage cam surfaces  42  of grasping arms  18  thereby moving grasping fingers  44  towards each other. Such movement also extends expansion spring  36 . This inward movement of fingers  44  causes the fingers to extend above bottom slats  58  of the pallet. This causes the grasping arm to grasp a bottom portion of the pallet in the grasping state illustrated in  FIG. 4 . The grasping arms will remain in the grasping state until the pallet is positioned on one or more rails or blocks  60 . As the weight of the pallet and its contents are borne by rails  60 , further downward movement of load-handling device  13  allows compression springs  32  to bias the actuator assembly upwardly. This allows the energy stored in expansion spring  36  to move grasping arms  18  to the non-grasping position illustrated in  FIG. 2 . This allows the pallet-handling device to move freely below the pallet and thereby be retracted by the load-handling device from the pallet.  
         [0019]     The illustrated embodiment is a fully mechanical implementation of the invention. This is especially useful for certain applications, such as attachments to ASRS, where the utilization of hydraulic hoses, electrical cables, or the like, would be difficult to accommodate with the wide range of motion of the support carriage with respect to the rest of the apparatus. Other applications may allow an embodiment wherein some or all of the actuation of the grasping arms is accomplished by hydraulic sensing of the pallet and actuation of the grasping arms or by electrical sensing of the pallet and actuation of the grasping arms, or some combination of both of these. Such implementation, in light of the teachings of the invention as provided herein, would be well within the skill of those knowledgeable in the art.  
         [0020]     Changes and modifications in the specifically described embodiments can be carried out without departing from the principles of the invention which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.