1. Field of the Invention
Pallet tier cap forming apparatus for forming into a pallet tier cap a horizontal planar paperboard blank including a generally rectangular center panel having four edges, and four flaps connected by fold lines with said center panel edges, respectively. A blank transport device initially displaces the blank laterally in a first diagonal direction to break simultaneously downwardly a first pair of flaps. The blank is then displaced laterally in the opposite diagonal direction, and the forming steps are repeated to fold downwardly simultaneously a second pair of flaps.
2. Brief Description of the Prior Art
Tier sheets are used between layers of palletized products to distribute the load and prevent cases from an upper layer from concentrating their force and crushing cases on a lower layer. Examples of apparatus and methods for forming and handling such pallet tier sheets are shown by the patents to Winski et al U.S. Pat. No. 5,336,042, Lerner et al U.S. Pat. No. 4,955,177, and Iwaki et al U.S. Pat. No. 4,400,929, and the Ouellette et al patent application publication No. US 2008/0122160.
Often cases do not have lids as a lid is redundant product protection if a tier sheet covers the layer. When lidless cases are palletized a tier cap sheet is often used to stiffen the edges of a tier sheet and prevent upper layer cases from bending the edge of a tier sheet down into a lower level case. A cap tier sheet must have its flaps broken down or up and those flaps must remain broken less than 180 degrees to provide rigidity to the edge of the tier sheet. For an automated palletizing machine, the flaps must be automatically bent.
One method for bending the flaps is to hold a single tier cap from the top in a suspended position, actuate a plate to hold the tier cap up just inside the intended break line, then actuate a plate to come down and break the flap downwardly. This operation is repeated on all four sides to the tier cap until all four flaps are bent down and enough memory remains that they do not spring back to 180 degrees. This method and apparatus is time consuming and requires expensive actuators. The resulting bend angles from this method and apparatus are marginal as the bending action does not initially force the bend to less than approximately 60 degrees and when the flap bends back out it often goes back to almost 180 degrees. The time this method and apparatus takes is often unacceptable for an automated palletizing cell. Palletizing cells are typically designed to keep up with case production plus a safe margin to ensure the palletizing cell is not the bottleneck in the production line. The additional time for bending four flaps on a tier cap at every layer slows the overall processing time down considerably.
Therefore, the prior art machines have the drawbacks that a tier cap sheet on an automated palletizing cell can be very expensive to implement, provide inadequate bending of the flaps, and may take too much time to allow for full automation.
Accordingly, a primary object of the present invention is to provide apparatus for forming into a pallet tier cap a horizontal planar paperboard blank including a generally rectangular center panel having four edges, and four flaps connected by fold lines with said center panel edges, respectively, use being made of a blank transport device that initially displaces the blank laterally in a first diagonal direction to break simultaneously downwardly a first pair of flaps. The blank is then displaced laterally in the opposite diagonal direction, and the forming steps are repeated to fold downwardly simultaneously a second pair of flaps.
According to a more specific object of the invention, a magazine containing an open-topped chamber is provided for receiving a vertical stack of the blanks, and a trip ledge arrangement is arranged concentrically above said chamber, including a rectangular arrangement of a plurality of planar orthogonally-arranged vertical drag walls having coplanar horizontal upper edges, and a plurality of coplanar horizontal fold walls extending outwardly from said drag wall upper edges, respectively, said drag walls and said fold walls cooperating to define a plurality of right-angled junctions, respectively. The blank transport means successively vertically elevates the uppermost one of said blanks from the stack toward a position within the space defined between said drag walls, initially displaces said one blank simultaneously laterally in a first diagonal direction for simultaneous engagement with a first orthogonally arranged pair of said drag walls, and vertically upwardly toward a position in which the blank center panel is at a slightly higher elevation than that of said horizontal fold walls, thereby to break downwardly about the associated fold lines a first pair of adjacent flaps of said one blank. The blank is subsequently displaced laterally further in said first diagonal direction, thereby to reversely fold back said first pair of flaps about the associated junctions toward an acute angle relative to the blank center panel. The blank is then displace diagonally in the opposite direction, and the steps are repeated to simultaneously fold downwardly a second pair of flaps by a second pair of orthogonally arranged drag walls and the associated fold walls.
According to one embodiment of the invention, the magazine side walls have coplanar horizontal upper edges, and the trip ledge arrangement includes a plurality of linear trip ledge members parallel with, and connected with the upper edges of, said magazine side walls, respectively, each of said trip ledge members including a vertical first wall defining said drag wall, and a horizontal second wall connected with the upper edge of said vertical wall defining said fold wall. Preferably, the trip ledge members are adjustably connected for lateral horizontal adjustment relative to the associated side wall of the magazine.
According to a second embodiment, the drag walls are integral with said magazine side walls, respectively.
According to a further object, a horizontal guide wall is provide in spaced relation above each of the horizontal fold walls, thereby to define a slot for receiving the corresponding folded tab portion of the blank. Preferably, the height of the guide wall may be adjusted relative to the associated fold wall.
Basically, the present apparatus of the present invention uses the controlled motions of a lifting device to exert forces to the tier cap sheet against a flap folding apparatus. The apparatus is mounted above a magazine which is filled a stack of unbroken tier cap sheets. The lifting device enters the magazine and attaches to the top tier cap with vacuum cups mounted on the bottom of the lifting device end of arm tool. The lifting device lifts the top tier cap several inches to allow the top tier cap to separate from the tier cap sheets below the top one. The lifting device then moves upwardly and diagonally towards one corner of the flap folding apparatus. As the tier cap moves upwards towards the corner, the flaps encounter resistance on two adjacent sides closest to the target corner. The resistance, coupled with the lift from the end of arm tool, cause the flaps on the two adjacent sides to break downwardly as the lifting device continues to lift. The lifting device continues this trajectory until the broken edges of the tier cap are above the folding edge of the bending apparatus. The lifting device then moves the cap tier in a horizontal plane diagonally directed towards the corner. As the tier cap is forced over the corner, the flaps continue to bend to a smaller angle. The apparatus may have a top guide which forces the top edge of the tier cap downward to further decrease the angle of the bend and prevent the tier cap from lifting up due to the increasing energy in the bent flaps which are being forced to a smaller angle. The final motion of the lifting device for a bend is to press straight down and bend the flap all the way to 0 degrees. The lifting device then traverses horizontally towards the opposite corner. Once the bent corner of the tier cap is no longer restrained by the bending apparatus, the lifting device moves the tier cap down and towards a point at the opposite corner from the first bending operation took place. Once at that point, the lifting device moves the tier cap in the same motions as described for the first two flaps in order to fold the remaining two flaps with the other bending apparatus.
Tier sheets tend to bow on their edges when they are lifted, unless a flap is bent to eliminate the likelihood of bending, in which event the edge of the tier sheet at the break becomes very straight. A lightweight tier sheet may bow so much that the force to bend the flap is not enough to overcome the force the bow produces for preventing the tier sheet to break at the score line. This situation often occurs when one flap is bent at a time. Two adjacent sides of a tier sheet cannot both bow. Once one side bows, the other side will stay straight and bent down, and cannot bow. As such, if two adjacent sides are simultaneously bent with the apparatus described above, the side which bows will be bent at the break line which will lift the other side and reduce the bow enough to bend it at the break line. Simultaneous bending operations taking place on two adjacent sides is often necessary to properly break a light weight tier sheet which bends as it is lifted.
Once the bending operation has been completed on the two corners and the four flaps are bent, the lifting device precedes to placing the tier cap sheet on the layer of boxes.
Other objects and advantages of the invention will become apparent from a study of the following specification, when viewed in the light of the accompanying drawing, in which:
a and 1b are top and side elevation views, respectively, of a pallet tier blank of the prior art in the initial flat, unfolded condition, and
a and 2b are top and side elevation views, respectively, of a pallet tier blank of the present invention in the initial unfolded condition, and
elevation view of the blank of
a-4c are detailed sectional views illustrating the steps for forming a pallet tier cap using the apparatus of
a-5c are detailed sectional views illustrating the steps for forming a pallet tier blank by the use of a second embodiment of the invention; and
a-6c are detailed sectional views illustrating the steps for forming a pallet tier blank by the use of a third embodiment of the invention.
Referring first more particularly to
Referring now to
As shown in
A robotic vacuum-type blank transport mechanism 90 is provided for lifting the uppermost blank 30 from the stack, and for displacing the blank during the flap folding steps. The transport mechanism includes four suction cups 92 (shown schematically in
In operation, as shown diagrammatically by
The blank is then transported diagonally in the opposite direction (as shown by the arrowhead 108 in
In the second embodiment shown in
According to a third embodiment shown in
While in accordance with the provisions of the Patent Statutes the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that changes may be made without deviating from the invention described above.