Abstract:
An apparatus connectable to a robotic arm for selecting, positioning, and loading a pallet for use in manufacturing and warehouses. The apparatus being made of a frame with opposing pallet gripping arms with hooks to engage and transport a pallet. The frame also having a suction assembly, which can select and transport a top loading sheet for placement on top of a pallet. The frame further comprising a carriage sub-assembly which aligns, stabilizes, and secures articles, including different sized and amorphous bagged materials. The frame further comprising opposing bag gripping arms, which lift and carry the articles to the pre-positioned pallet and stack them.

Description:
REFERENCE TO RELATED APPLICATION 
       [0001]    The application claims priority to U.S. Provisional Application entitled “Multi-function Manipulator for Palletizing Bagged Material,” Ser. No. 60/794,655, filed Apr. 25, 2006, which is incorporated herein by reference in its entirety. 
     
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to materials handling apparatus, and more specifically to a machine designed to arrange and prepare a pallet and to stack articles having a non-rigid form on the pallet. 
       DESCRIPTION OF THE PRIOR ART 
       [0003]    A host of automated devices for moving, stacking, indexing, palletizing, or otherwise manipulating materials are described in the patent literature. See, for example, U.S. Pat. Nos. 7,137,234; 6,658,816; 6,524,058; 6,238,173; 6,000,904; 5,984,621; 5,848,867; 5,807,065; 5,791,867; 5,695,313; 5,690,464; 5,421,698; 5,411,304; 5,310,306; 5,190,430; 5,141,274; 5,088,877; 5,088,783; 5,066,189; 5,030,055; 4,836,731; 4,674,238; 4,592,692; 4,082,194; 4,055,261; 4,005,782; 3,884,363; and 3,697,112. 
         [0004]    None of these devices, however, are adept at palletizing diverse materials, such as the pallets themselves, sheet materials, and especially bagged materials. A vast array of goods are transported in bags for ultimate sale to the consumer, ranging from food destined for human and animal consumption (e.g., grains, flour, sugar, formulated livestock feeds and feed additives, pet food, etc.), agricultural products (e.g., seeds for planting, fertilizer, mulch, herbicides, pesticides, etc.), construction materials (plaster, concrete mix, sand etc.), and consumer products such as kitty litter, water-softener salt, and the like. To transport these goods from the manufacturer to the distributor and/or retail seller, the bagged material is palletized for ease of loading and unloading the shipment. 
         [0005]    Bagged materials, however, present distinct challenges for automated handling equipment due to the flexible nature of the packaging material from which the bags are fabricated and the ability of the contents of each bag to shift. Thus, for example, a manufacturer may sell its powdered goods in two different quantities: 100 lb. bags and 50 lb. bags. It is often the case, however, that the same bag is used for both sizes; the 100 lb. bag is simply filled twice as full as the 50 lb bag. This scenario presents troubles for conventional automated handling equipment because the 50 lb bag, while having roughly the same outer dimensions as the 100 lb bag, is far more flaccid that the 100 lb. bag. 
         [0006]    Often, customers would be required to purchase different machines to palletize different sized bulk loads. Additional machines were also required to position and prepare empty pallets. These machines require manual placement of top sheets. Recently, fully automatic palletizers were introduced that integrated the manual placement of top sheets as an automatic function of the machine. See U.S. Pat. Nos. 5,672,045 and 6,658,816. 
         [0007]    These prior art approaches use separate, distinct, and complex mechanical devices to perform the operations of picking and positioning the empty pallet, feeding the individual top sheets, and stacking the bulk articles onto the pallets. The present invention eliminates the need for multiple machines to prepare a pallet and stack different sized bags on the pallet. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is directed to a multi-function manipulator for palletizing a bulk load comprising a frame dimensioned with a top, bottom, front, rear, left side, and a right side, pallet gripping arms, opposingly affixed to the frame, an article grasp, a pressure sensitive carriage assembly, and a suction assembly; wherein the article grasper further comprises a plurality of opposing grasper arms which are movably mounted on the bottom of the frame and dimensioned and configured to selectively engage and disengage a work-piece; wherein the pressure sensitive carriage assembly is mounted between the plurality of opposing grasper arms on the bottom of the base frame; and wherein the suction assembly is dimensioned and configured for transporting a work-piece. 
         [0009]    The present invention is further directed to a multifunction manipulator for palletizing a bulk load comprising a frame dimension with a top, a bottom, a front, a rear, a left side, and a right side, pallet gripping arms opposingly affixed to the frame, an article grasper further comprising a plurality of opposing grasper arms movably mounted on the bottom of the frame and dimensioned and configured to selectively engage and disengage a work-piece, a pressure sensitive carriage assembly mounted between the plurality of opposing grasper arms on the bottom of the frame, and a suction assembly mounted on a side of the frame wherein the assembly is dimensioned and configured for transporting a work-piece; further comprising at least one cylinder connected to the frame dimensioned and configured to operate the pallet gripping arms, the article grasper, the pressure sensitive carriage assembly, and the suction assembly; further comprising a linkage rotationally attached to the pallet gripping arms, wherein the linkage is dimensioned and configured so that each pallet gripping arm moves in conjunction with an opposing pallet gripping arm; further comprising a linkage attached to the frame wherein the linkage is dimensioned and configured to releasably attach the frame to a robotic arm. 
         [0010]    The invention is a manipulator that is capable of handling and palletizing both bagged materials and sheet materials. The manipulator is, for example, capable of stacking the pallets themselves (so that the pallets may be easily transported). The manipulator is also capable of palletizing any type of sheet material, from paper, to card board, to tiles, to wood products, dry wall products, sheet insulation, and the like. 
         [0011]    In particular, the device is novel in that it includes a cooperating, three-function assembly that employs (1) arms for gripping pallets; (2) a vacuum-implemented array for gripping sheet material; and (3) a pair of pressure-sensitive carriage plates (that can move both independently and in tandem). The pressure-sensitive carriage plates work in conjunction with the tines to ensure that the bagged material is gripped sufficiently firmly to move the load with authority, but not so firmly as to damage the bag itself. The carriage plates also function as a chute that directs the bag to the desired location when the plates release their grip on the bag being moved. 
         [0012]    This aspect of the invention is important because, unlike rigid packaging, where each “building block” is inherently stiff and retains a fixed shape, a bag can and will assume odd, irregular shapes. This adds a level of complexity when designing a machine to stack bags into an ordered array, such as when palletizing them. By forcing the bags to retain, if only for a moment, a slightly compressed profile, and then dropping the bag without any pitch, yaw, or roll, the bags are made to maintain a uniform geometric profile from bag-to-bag. This allows the bags to be palletized in ordered arrays that are stable and can be transported without worries that the stacked bags will collapse. 
         [0013]    Thus, in a more specific version, the invention is directed to an apparatus for palletizing a load of bagged material. The apparatus comprises a frame having a top, a bottom, a front, a rear, a left side, and a right side. Pallet gripping arms are opposingly affixed to the frame and dimensioned and configured to reversibly engage a pallet. The pallet gripping arms are movable between a disengaged position, an engaged position, and a stowed position. The pallet gripping arms are pivotally movable between these three positions. When in the stowed position, the pallet gripping arms are substantially parallel with the frame. When in the engaged position, the pallet gripping arms are substantially perpendicular to the frame and positioned to grasp a pallet therebetween. When in the disengaged position, the pallet gripping arms are positioned to release a pallet (or to be disposed outside the perimeter of a pallet just prior to engaging it). Each of the pallet gripping arms further comprises a gripping portion dimensioned and configured to reversibly engage the pallet. The device also includes an article grasper comprising a pair of opposing grasper arms movably mounted to the bottom of the frame and dimensioned and configured to selectively engage and disengage a bag work piece. The grasper arms are movable between an open and a closed position. A pressure-sensitive carriage assembly is mounted between the opposing grasper arms. The pressure-sensitive carriage assembly comprises first and second horizontal guide plates positioned substantially parallel to one another. Opposing pressure-sensitive switches are attached to the first and second horizontal guide plates. These pressure-sensitive switches are dimensioned and configured to halt inward motion of the guide plates when the bag work piece is centered between the guide plates. Thus, the switches function to ensure that the bag to be manipulated is properly oriented so that can be securely grasped by the device. A suction assembly is mounted on a side of the frame. The suction assembly is dimensioned and configured for transporting a sheet work piece, such as a tier sheet, top sheet, bottom sheet, and the like. 
         [0014]    The objects and advantages of the invention will appear more fully from the following detailed description of the preferred embodiment of the invention made in conjunction with the accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a front elevation of a preferred embodiment of the manipulator. 
           [0016]      FIG. 2  is a top plan view of the manipulator in  FIG. 1 . 
           [0017]      FIG. 3  is a left elevation of the manipulator in  FIG. 1 . 
           [0018]      FIG. 4  is a top plan view of the linkage sub-assembly for the carriage plate assembly. 
           [0019]      FIG. 5  is a front elevation of the carriage plate assembly. 
           [0020]      FIG. 6  is a side elevation of the bag gripper assembly 
           [0021]      FIG. 7  is a front elevation of the bag gripper assembly and the sliding brake sub-assembly. 
           [0022]      FIG. 8   a  is a bottom plan view of the robotic arm linkage. 
           [0023]      FIG. 8   b  is a side elevation of the robotic arm linkage. 
           [0024]      FIG. 8   c  is a top plan view of the robotic arm linkage. 
           [0025]      FIG. 9   a  is a top plan view of the tine assembly. 
           [0026]      FIG. 9   b  is a side elevation of the tine assembly. 
           [0027]      FIG. 9   c  is a front elevation of the tine weldment sub-assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    The invention is a multifunction manipulator  100  useful for placing bulk objects on a pallet. The preferred embodiment of the invention can be attached to an articulated robotic arm (conventional, not shown), which moves the manipulator  100  around a manufacturing floor. In the preferred embodiment, the manipulator  100  has four pallet gripping arms  104  each positioned at the corners of the frame  102 . Each pallet gripping arm  104  opposes another pallet gripping arm. Each pallet gripping arm  104  is movable from a disengaged position to an engaged position and to a stowed position. In the disengaged position, each pallet gripping arm is positioned substantially perpendicular to the frame. As shown in  FIG. 1 , in the stowed position  104   a , each gripping arm  104  is folded in parallel with the frame  102 , as well as the other pallet gripping arms  104 . Opposite the point of connection  103  to the frame  102 , each pallet gripping arm  104  has a pallet hook  105 . When the manipulator  100  is placed over a pallet, the pallet gripping arms  104  are positioned outside the perimeter of the pallet. The pallet gripping arms are urged from the disengaged position  104   c  to the engaged position  104   b , thereby securing the pallet hooks  105  to the pallet. At this point the robotic arm and manipulator  100  can move the pallet securely to a desired position, at which time the gripping arms  104  are urged into the open position and the pallet is released. In order to begin stacking bagged articles, the pallet gripping arms  104  are folded out of the way to the fully enclosed position, substantially parallel to the frame  102 . 
         [0029]    With the pallet in place, the manipulator  100  places a top sheet onto the pallet through the use of the vacuum sub-assembly  151 . The vacuum sub-assembly  151  includes a plurality of flexible, accordion-like suction cups  153  that serve to releasably grip sheet material via reduced air-pressure. The suction cups  153  are positioned on the side of the frame with the opening of the suction cups  153  oriented substantially parallel to the frame  102 . In operation, the manipulator  100  is rotated into a position parallel with the surface of the sheet material (not shown) to be manipulated, and the suction cups  153  are then brought into contact with the surface of the sheet material. A negative pressure is created by a vacuum pump (not shown), which causes the suction cups to grip the sheet material very tightly, such that the entire manipulator  100 , with the sheet material attached, may then be moved (via a robotic arm, not shown). When the sheet material is in the desired location, the vacuum within the suction cups is released, thereby releasing the sheet material from the manipulator  100 . 
         [0030]    The robotic arm then positions the manipulator  100  over a conveyor belt to begin stacking bags. The robotic arm places the manipulator  100  in position over a conveyor belt, which transports bagged material. The manipulator  100  has a carriage assembly  121  with two parallel guide-plates  128 . The guide-plates  128  are designed with pressure-sensitive switches which provide feedback to a controller device. When a bag of material has reached a predetermined point on a conveyor belt between the two guide-plates  128  of the carriage assembly  121 , the guide-plates are urged together. The guide-plates  128  serve two functions. The first is orienting the bag in a proper position. For example, if the bag is slightly askew coming down the conveyor belt, the guide-plates  128  will align the bag so that it is squarely between the guide-plates. This action helps create a more regular stacking of the bags upon the pallet. The second action is compressing the material contained within the bag. By slightly compressing the bag, the guide-plates  128  level the contents of the bag, thereby making all of the bags more uniform in shape. After the bag is aligned and secured by the carriage assembly  121 , the bag grasper  139  engages the bag. 
         [0031]    In the preferred embodiment, the bag grasper  139  is comprised of two opposing grasper arms  173 . The two grasper arms  173  are movably mounted to the bottom of the frame  102 . Each individual grasper arm  173  is secured laterally to a guide-plate  128  of the carriage assembly. Thus, the entire carriage assembly  121  is attached to the frame  102  between the two bag grasper arms  173 . Opposite the pivot point  103 , each bag grasper arm  173  has a plurality of tines  186  attached perpendicularly to the grasper arm. The bag grasper arms  173  are movable between an open position and a closed position. In the closed position, the bag grasper arm  173  is positioned substantially perpendicular to the frame  102  of the manipulator  100 . In the open position, the bag grasper arm  173  is positioned substantially parallel to the frame  102 . The tines  186  are sufficiently long to support a bag or other object between them when they are in the closed position. In operation, once the carriage assembly  121  has aligned and secured the bag, the bag grasper arms  173  move from an open position to a closed position. In the closed position, the tines  186  affixed to the bag grasper arms slide underneath both the carriage assembly  121  and underneath the bag. Because there are two opposing bag grasper arms  173 , the bag is supported by tines  186  on either side. 
         [0032]    The opposing bag grasper arms  173  move substantially in tandem with one another, which means the arms move from the open to closed position simultaneously and reverse positions simultaneously. After the bag gripper arms  173  have moved into the closed position and the tines are sufficiently supporting the bagged article, the robotic arm lifts the entire manipulator  100  with the bag secured between the gripper arms  173  and positions it over the pre-positioned pallet. The robotic arm arranges the bag gripper  139  at an appropriate position over the pallet, several inches above the pallet. The bag gripper arms  173  quickly move to the open position and drop the bag into the pre-determined position on the pallet. Dropping the bag from several inches above the position causes the bag to vertically compress and settle into a secure position. This process is repeated until the pallet is stacked to a pre-determined height in a pre-determined pattern. 
         [0033]    Reference will now be made to the attached drawings, where the same reference numerals are used throughout the various views. 
         [0034]    As shown in  FIG. 1  the manipulator  100  includes a frame assembly  102 . The frame assembly  102  is the support structure for the manipulator and is fabricated from extruded aluminum. Extruded aluminum is preferred because it supplies the required mechanical strength and rigidity, while being extremely lightweight. Other suitable materials may also be used for the frame, including other metals and alloys (e.g., steel), composite materials, or suitably rigid polymeric materials. Pallet gripper arms  104  are movably mounted to the frame assembly  102 . In the preferred embodiment of the manipulator  100 , two sets of two pallet gripper arms  104  are opposingly attached  103  to the perimeter of the frame assembly  102 . In this configuration, the pallet hooks  105  on each pallet gripper arm  104  oppose each other. The pallet hooks  105  rotate in the direction shown in the arrows and are urged either to open or close by the action of pistons  107  and cylinders  109 . The cylinders  109  are attached to the frame assembly  102  at the cylinder mount  106 . The mechanical sub-operations, attached to the frame assembly  102 , are generally protected by the manipulator frame cover  108 . A robot arm linkage  111  is affixed to the top of the frame assembly  102  via the robot arm linkage attachment plate  112 . The robot arm linkage attachment plate  112  is secured to the frame assembly  102  by the linkage center support block  110 . Each set of opposing pallet gripping arms  104  are joined by a pallet arm linkage rod and spacer  124 . The piston  107  urges one of the opposing pallet gripping arms  104  and the linkage rod  124  urges the opposing pallet gripper arm  104  to move in the same direction, either in the open or closed position. The structural rigidity of the manipulator  100  is further increased by a lateral frame plate  114 . The lateral frame plate  114  also protects mechanisms on the left side of the manipulator  100 . 
         [0035]    In the preferred embodiment, the mechanical movements of the manipulator  100  are operated by pneumatic cylinders attached to the frame assembly  102 , for example the gripper arm cylinder  109 . The pneumatic power source (not shown) provides positive and negative airflow to the manipulator  100  via pneumatic tubes (not shown). The air manifold (not shown) is attached to the manifold mounting bracket  116  from which the pneumatic tubes (not shown) can feed the various subassemblies. 
         [0036]    The suction subassembly  153  is preferably on the left side of the manipulator  100 . The suction subassembly  151  is further comprised of a plurality of suction cups  153 . When the manipulator  100  is lowered onto a stack of top sheets (not shown) a proximity indicator (not shown) is used to control the speed and location of the manipulator  100 . The chosen proximity indicator is attached to the manipulator  100  in the proximity indicator bracket  118 . Typical examples of proximity indicators use infrared technology. The carriage of the subassembly  121  and the bag gripper subassembly  139  are movably affixed to the bottom of the manipulator  100 . The carriage subassembly  121  includes two opposing carriage plates with spring actuators  128 . The carriage plates  128  are rotatably movable from an open position to a closed position. In the open position, each carriage plate  128  abuts a carriage stop end plate  122 . The carriage plates  128  are urged into a closed position, which is substantially perpendicular to the frame assembly  102 , by pneumatic pressure. Although pneumatic pressure is preferred, other examples of power include hydraulic or electric motors. The carriage plates  128  are attached to a carriage plate weldment  136  which is pivotally attached to the frame assembly  102 . 
         [0037]    The bag gripper subassembly  139  is comprised of two tine-support weldments  132  pivotally attached to the frame assembly  102  by a bag gripper bearing  138 . The two tine-support weldments  132  oppose one another and are attached the frame assembly  102  slightly outside the carriage subassembly  121 . Thus, the two opposing carriage plate weldments are positioned between the two opposing tine-support weldments  132 . The two tine-support weldments  132  move between and open position (substantially parallel with the frame assembly  102  and a closed position (substantially perpendicular to the frame assembly  102 ). The opposing tine-support weldments  132  move substantially in tandem with the addition of a sliding brake subassembly  130 . Each tine-support weldment  132  also includes a clevis pin modification  126  which facilitates the tandem movement. Each tine-support weldment  132  has a plurality of tines  186 , which in the closed position are substantially parallel to the frame assembly  102 . A pneumatic cylinder is attached to the bag gripper guided search cylinder bracket  134 . Furthermore, a pneumatic cylinder for the pallet gripper arms is connected to the pallet guided search cylinder bracket  120 . 
         [0038]      FIG. 2  illustrates the top plan view of the manipulator  100 . Each opposing pallet gripper arm  104  is secured to the frame assembly  102  via a pallet arm shaft  144 . In the preferred embodiment, the manipulator  100  has two pallet arm shafts  144 , one on the left and one on the right side of the frame assembly  102 . Each pallet arm shaft  144  is directly attached to the frame  102  via a pallet arm shaft support  140 . The linkage subassembly  142  connects the carriage subassembly  121  to the manipulator  100 . The linkage subassembly  142  allows the dual opposing carriage plates  128  to move independently of one another. The carriage stop angle block  146  prevents the carriage subassembly  121  from coming too close together in the closed position. The lock washer  148  maintains stability of any cylinder attached to the cylinder mount block  150 . For the preferred embodiment, in which pneumatic actuators are used, a Y-connector  156  allows for distribution of air.  FIG. 2  also illustrates the suction cup bracket  152  and the extended suction cup bracket  154 , the difference being the distance from the center of the frame assembly  102 . The top view of the bag gripper subassembly  139  is visible showing its means of attachment to the frame assembly  102 . A DRYLIN® brand floating carriage provides lateral movement to any attached wires or pneumatic tubes not shown. The floating carriage  158  glides through an IGUS® brand rail. Both the floating carriage of  158  and the rail  160  are available from Igus Inc., East Providence, R.I. 
         [0039]      FIG. 3  illustrates the suction subassembly  151  from a side elevation. The manipulator frame cover  108  is positioned at the top of the manipulator  100  for reference. In this preferred embodiment the extended suction cup bracket  154  extends above the manipulator  100  and the manipulator frame cover  108 . Also illustrated in  FIG. 3  is a side view of the bag gripper subassembly  139 . The tine rack weldment  164  is configured with a plurality of tines  186 , which as shown in  FIG. 3  are aligned substantially parallel with the frame assembly  102 . If a proximity indicator is used for the bag gripper subassembly  139 , the indicator is attached to the bag gripper prox mount  166 . A support shaft  168  is attached to each set of bag gripper arms  173  on each side of the manipulator  100 . The support shaft  168  rests in a shaft collar  162  on each bag gripper arm  173 . 
         [0040]      FIG. 4  illustrates a dissected view of the linkage subassembly  142  for the carriage plate subassembly  121 . The linkage subassembly  142  is actuated by a trunion mount cylinder  171  preferably operated by pneumatic forces. The trunion mount cylinder  171  is attached to the frame assembly  102  at the trunion mount  170  in the carriage plate cylinder mounting block  172 . 
         [0041]      FIG. 5  illustrates an elevation view of the carriage subassembly  121  in relation to the linkage subassembly  142 . The linkage subassembly  142  is attached to the frame  102  via a linkage rod  124  secured to the linkage center support block  110 . The linkage subassembly  142  is positioned relatively below the robot arm of the linkage attachment plate  112  and the linkage attachment bolt  113 . 
         [0042]      FIG. 6  illustrates the bag gripper subassembly  139  in a side elevation. The bag gripper arms  173  are shown attached to the tine-support weldment  132 , shown here in the closed position. An opposing bag gripper arm  174  is also shown. The bag gripper subassembly  139  uses a pancake cylinder  176  connected to a brake clamp  184  to maintain a chose position. When the pancake cylinder  176  is activated, preferably by pneumatic action, the brake clamp  184  creates pressure along the brake slide bar  182  and slows or stops the bag gripper arm  173 . The bag gripper arms  173  are secured to the frame assembly  102  via a shoulder bolt attachment  178  fitted with an IGUS® brand sleeve bushing  159  and an IGUS® brand bushing  161 . (Igus, Inc., East Providence, R.I.). The brake slide bar  192  is connected to the cylinder  176  via the brake cylinder mount bar  180 . 
         [0043]      FIG. 7  illustrates a side elevation of the brake system for the bag gripper subassembly  139 . The juxtaposition of the brake slide bar  182  relative to the opposing tine-support weldments  132  is illustrated. The brake system including the brake cylinder mount bar  180  and the brake clamp  184  floats between the opposing tine weldments  132 . 
         [0044]      FIG. 8  illustrates the robot arm linkage  111  of the preferred embodiment. Any number if attachment apertures on the top or the bottom of the robot arm linkage could be used. 
         [0045]      FIG. 9  illustrates the orientation of the plurality of tines  186  using the bag gripper subassembly  139 . The individual tines  186  are joined to the tine-support weldment  132 , which is then connected to the bag gripper arm  173 . 
         [0046]    It is understood that the invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.