Abstract:
Methods and apparatus for sealing pallets of fresh produce inside enclosures and for filling the interiors of the sealed enclosures with a modified gaseous atmosphere moves pallets loaded with fresh produce to a squeeze station where the packages as a unit are gripped between opposing walls on two opposing sides and between additional opposing squeeze members on two other opposing sides.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to the field of enclosing product units on a production line, and in particular to methods and apparatus for enclosing agricultural produce pallets in preparation for modifying the atmosphere surrounding the produce inside the enclosure with a gas or gas mixture to retard ripening and spoilage, or to otherwise promote freshness and extend the shelf life of such produce. See, in particular, the disclosures, drawings and claims of U.S. Pat. No. 5,046,302, issued Sep. 10, 1991, and entitled “Method and Apparatus for Bagging Product Units”; of U.S. Pat. No. 5,111,639, issued May 12, 1992, and entitled “Method and Apparatus for Bagging Product Units”; and of U.S. Pat. No. 5,314,286, issued May 24, 1994, and entitled “Apparatus for Bagging Product Units”. These disclosures are incorporated herein as though fully set forth here.  
       SUMMARY OF THE INVENTION  
       [0002]     This invention provides methods and apparatus for enclosing pallets of fresh produce in sealed enclosures and furnishing the interiors of the sealed enclosures with a modified gaseous atmosphere for preserving such produce. Pallets loaded with fresh produce are transported from cooling tunnels to an input conveyor. The input conveyor moves the pallets automatically one at a time to an in-line squeeze station. When a pallet is positioned on the squeeze station, the conveyor stops automatically. These methods and apparatus deposit a plastic sheet lining onto the pallet base while the produce load is suspended above the pallet base. The plastic sheet lining is deposited onto the pallet base while the produce load is suspended above it.  
         [0003]     These methods and apparatus deposit a plastic sheet lining onto the pallet base while the produce load is suspended above the pallet base. The plastic sheet lining is deposited onto the pallet base while the produce load is suspended above it.  
         [0004]     Typically, a bulk roll of plastic sheet lining is located adjacent to the in-line squeeze station. Once the produce load is suspended above the pallet base, the downwardly movable floorplate, and the pallet base resting thereon, descends. The pallet drops into a position substantially equidistant from the squeeze sidewalls. At that time, a pair of gripping members grasp the leading edge of plastic sheet lining from the bulk roll and guide the plastic sheet lining over the pallet deck surface resting below the suspended produce load. The Doorplate is raised to its former level to bear the weight of the loaded pallet. The pallet is unsqueezed and the plastic sheet lining is then severed from the supply. The loaded pallet then continues along the conveyor to the enclosing stations.  
         [0005]     These apparatus comprise gripping interior surfaces on opposed vertical walls (squeeze sidewalls) at a squeeze station. Pneumatically operated “stops” at the squeeze station ensure precise alignment of the produce load with the gripping surfaces of the vertical walls when engaged.  
         [0006]     Before, concurrent with or after the squeezing of the load between two opposed vertical walls, additional squeeze members, such as foot plates, engage and squeeze two additional opposing sides of the load. Such additional squeeze members are positioned adjacent to, and engage, the load on surfaces other than the load surfaces engaged by the opposed vertical squeeze walls. In some embodiments, one, two or more additional squeeze members engage and squeeze the produce load on one of the opposing two sides, and one, two, or more additional squeeze members engage and squeeze the produce load on an opposing side. In some embodiments, these squeeze members are positioned to engage a load at specific, adjustable locations along the horizontal plane of the load.  
         [0007]     In some embodiments, these additional squeeze members are plates or blades, and are square or rectangular in shape. Each preferably has a surface area in the range of about 0.5 to about 16 square feet. Rectangular plates or blades may have their longer sides aligned with the vertical plane of the load, and their shorter sides aligned with the horizontal plane of the load. These plates or blades may be attached to members, such as rods or arms, that move the plates or blades toward, and into engagement with, and away from, and out of engagement with, the produce load. Such members may be air-actuated, hydraulically-actuated or mechanically-actuated. Such members may be positioned to engage a load below its vertical midpoint and above the pallet carrying the load. These squeeze members may squeeze a load of cartons stacked in a pattern where the carton strong points do not necessarily align within the horizontal plane of the load stack.  
         [0008]     In some embodiments, at least some of such plates or blades are the same size and shape. Such plates or blades may include features such as protrusions, e.g. pointed, rounded or otherwise, from the surface of the plate, that penetrate, upon engagement, into the load. In some embodiments, the plates or blades are moveable laterally with respect to the load and with respect to one another.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The various features and advantages of the present invention will become apparent in light of the following detailed description taken together with the accompanying drawings, in which:  
         [0010]      FIG. 1  is a perspective view of an embodiment of the apparatus of this invention showing the structure of the squeeze station;  
         [0011]      FIG. 2  is an exploded view of one side of the squeeze station shown in  FIG. 1 ;  
         [0012]      FIG. 3  is an exploded view of the opposite side of the squeeze station in  FIGS. 1-2 ;  
         [0013]      FIG. 4  shows a palletized load of produce in the squeeze station shown in  FIGS. 1-3 , with squeeze members engaging opposing sides of the load;  
         [0014]      FIG. 5  is a top perspective view of the apparatus shown in  FIGS. 1-4 , and shows additional squeeze members engaging the load;  
         [0015]      FIG. 6  is an overall end view of the squeeze station of  FIGS. 1-5 ;  
         [0016]      FIG. 7  is a top plan view of a six down pattern of boxes of produce on a pallet;  
         [0017]      FIG. 8  is a top plan view of a five down pattern of boxes of produce on a pallet; and  
         [0018]      FIG. 9  is a schematic plan view of the layout of a squeeze station, and of a related pallet enclosing and sealing system.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     By way of example, the method and apparatus are described in terms of pallets loaded with strawberries. Minor modifications may be appropriate for other types of produce. A plurality of strawberry packages is stacked onto the upper surface of a pallet. A fully loaded pallet may contain 18 tiers of 6 trays in each tier and an overall height of about 88 inches. Each tray may contain 8 one-pound packages of strawberries, so that a fully loaded pallet has 108 boxes containing 8 one-pound packages of strawberries (see  FIG. 7 ). Alternatively, a fully loaded pallet may contain 18 tiers of 5 trays in each tier, and may have an overall height within the range of about 90 inches to about 100 inches (See  FIG. 8 ).  
         [0020]     A strawberry pallet is generally 48 inches by 40 inches. Other produce pallets may also be 48 inches by 40 inches, or have different dimensions. The strawberries are cooled to around 33 degrees F., which is about 4 degrees above the freezing point of the strawberries, depending on their sugar content. The gassing operation is usually done on produce which has been cooled to its optimum storage temperature.  
         [0021]      FIG. 9  is a schematic plan view of the layout of enclosing apparatus  10 . An infeed portion  12  of apparatus  10  comprises a conveyor line using metal rollers  100  which are actuated by a belt drive. Multiple pallets are brought by forklift and unloaded at infeed  14  of the conveyor line. When a loaded pallet reaches pallet squeeze station  16 , the drive mechanism for the conveyor line is shut off.  
         [0022]     Pallet squeeze station  16  comprises a moveable pair of opposed vertical walls above a moveable floorplate. Vertical squeeze walls are positioned clear of the loaded pallet as the loaded pallet moves into the squeeze area. When the loaded pallet is in position, the vertical walls, which are mounted with a counterweight, move downward, to a horizontal position, bringing the two opposing squeeze walls to positions adjacent to the forward and back vertical surfaces of the loaded pallet. These walls approach each other by a distance calculated to squeeze the pallet load a sufficient amount to support it against the force of gravity. The floorplate on which the loaded pallet normally rests is moved downward to allow placement of a plastic lining sheet onto the pallet. The sheet is generally flat and its edge margins extend several inches beyond the edges of the pallet. The Doorplate is then raised to its original position to support the pallet load, the plastic sheet underlying the stack is cut away from the plastic feed roll, the pallet load is unsqueezed, the opposed squeeze walls rotate upward, and out of the path of the loaded pallet, and the loaded pallet is moved to pallet bagging station  18 .  
         [0023]      FIGS. 1-6  show an embodiment of pallet squeeze station  16 . Metal rollers  100  convey a loaded pallet to the area between wall  103 , which is located near the front of a loaded pallet, and wall  102 , which is located near the back of a loaded pallet. When loaded pallet  104  reaches squeeze station  16 , rollers  100  are shut off.  
         [0024]     Palletized load  104  is squeezed between opposing vertical walls  102  and  103 , which move downward to horizontal positions near the forward-facing and rearward-facing vertical surfaces of loaded pallet  104 . Walls  102  and  103  move toward each other by a distance calculated to squeeze the pallet load a sufficient amount to support it against the force of gravity.  
         [0025]     Before, concurrently, or thereafter, squeeze plates  50 ,  51 ,  52 , and  55  engage loaded pallet  104  on two additional opposing sides. Squeeze plates  50 ,  51 ,  52 , and  55  are carried on hydraulically-actuated arm members such as arms  60  and  61  (see  FIG. 5 ) which move the plates into, and out of engagement with palletized load  104 . Squeeze members  50 ,  51 ,  52  and  55  include a plurality of protrusions, such as protrusions  53 ,  54 ,  58  and  59  that penetrate into loaded pallet  104  to reinforce engagement with the pallet. Squeeze members  54 ,  55 ,  50  and  51  travel on hydraulically moveable arms such as arms  60  and  61 .  
         [0026]     After walls  102  and  104 , and squeeze plates  50 ,  51 ,  52 , and  55 , have all engaged pallet load  104 , the floor plate on which loaded pallet  104  rests in squeeze station  16  is moved downward to allow placement of a plastic lining sheet onto the pallet. The Doorplate is then raised to its original position to support the pallet load, and the plastic sheet underlying the stack is cut away from the plastic feedroll. The plastic load is unsqueezed, the opposed squeeze walls  102  and  103  rotate upward and out of the path of the loaded pallet. The opposed squeeze plates  50 ,  51 ,  52 , and  55  move out of engagement with and out of the path of loaded pallet  104 , and loaded pallet  104  is moved to pallet bagging station  18 . U.S. Pat. No. 5,314,286, issued May 24, 1994, and entitled “Apparatus for Bagging Product Units”, describes a preferred embodiment of pallet bagging station  18  and of the remaining structure and features of apparatus  10 .  
         [0027]      FIGS. 7 and 8  show a six down pattern and a five down pattern of stacked boxes of produce that may constitute palletized load  104 , respectively. In  FIG. 7 , palletized load  104  comprises 18 tiers with six trays in each tier. In  FIG. 8 , palletized load  104  comprises 18 tiers with five trays in each tier.  
         [0028]     The above-described embodiments are furnished as illustrative of the principles of the invention, and are not intended to define the only embodiments possible in accordance with our teaching. Rather, the invention is to be considered as encompassing not only the specific embodiments shown, but also any others falling within the scope of the following claims.