Carton panel folding mechanism.

0001This invention relates to a folding mechanism for fold­ing certain panels of a carton blank during a packaging operation. The invention is particularly concerned with the folding of reinforcing panels provided in the upper parts of a wraparound type carton in which such reinforcing panels are folded into and secured in overlapping relationship with adjacent areas of the carton blank to strengthen the carton.

0002Wraparound cartons which comprise a sleeve of paper­board wrapped and secured about a group of articles such as bottles are well known. During the packaging operation the carton may become wetted by moisture formed as condensation on the bottles to be packaged which ultimately can weaken the paperboard material or cause it to stretch thereby producing an unsatisfactory package. Reinforcing panels provided at appropriate locations on a carton blank to be folded to form a double ply thickness of material can be provided to minimise this problem and/or also allow the use of smaller caliper paperboard material for producing such carton.

0003One aspect of the present invention provides a mech­anism for folding reinforcing panels of a wraparound carton blank into superposed relationship with other parts of the blank adjacent thereto as the blank is advanced along a feed path, said mechanism comprising a plurality of folder elements each of which move in an endless path, a part of which path has a working reach adjacent said blank feed path in which the folder elements and the blank are moved together during the folding process, each of said folder elements including pivotal arms to engage and fold the reinforcing panels by executing a pivotal movement characterised in that common cam means is provided to effect pivoting of the pivotal arms of a plurality of leading folder elements predominantly in opposition to the direction of feed of the blank and in that further common cam means is prov­ided to effect pivoting of the pivotal arms of a plur­ality of of trailing folder elements predominantly in the direction of feed of the blank.

0004Another aspect of the invention provides a method of folding reinforcing panels of a wraparound carton blank into superposed relationship with other parts of the carton blank adjacent thereto, which method comprises advancing the blank along a feed path, causing a plur­ality of folder elements to be moved in synchronism with the blank, causing each of said folder elements to pivot into the feed path from a position adjacent one face of the blank and fold a reinforcing panel during the pivotal action into superposed relationship with a part of the opposite face of the blank, characterised in that a plurality of leading folder elements are caused to pivot predominantly in opposition to the direction of feed of the blank and in that a plurality of trailing folder elements are caused to pivot pre­dominantly in the direction of the feed of the blank.

0005A mechanism embodying the invention will now be des­cribed by way of example, with reference to the accom­panying drawings, in which:- <ul id="ul0001" list-style="none"><li>FIGURES 1 and 1a are plan views of portions of a carton blank which is compatible with a mechanism according to the invention, as seen from the underside;</li><li>FIGURES 2, 3 and 4 are similar plan views of a part of the mechanism showing the mounting arrangement of the folder elements;</li><li>FIGURE 5 is a side view of a part of the mechanism showing a pivotal arm of one of the folder elements;</li><li>FIGURE 6 is a cross-sectional view through a part of the mechanism along the line X-X in Figure 5, showing mounting and constructional detail of one of the folder elements;</li><li>FIGURE 7 is a schematic side view of the mechanism showing a side plate assembly; and</li><li>FIGURE 8 is a schematic side view of the mechanism as seen at the centre cam plate and showing one of the folder elements in a number of sequential positions.</li></ul>

0006Referring first to Figures 1 and 1a of the drawings, a carton blank of the wrap-around type (only a portion 10 of which is shown) comprises a top panel 12 to opposite side edges of which are hinged side wall panels 14 and 16 along fold lines 18 and 20 respectively. The carton blank is specifically adapted to be wrapped about a group of bottles arranged in two parallel rows of five bottles each. Apertures 'A' are formed at spaced locations along fold lines 18 and 20 to receive top portions of the bottle necks and their closures.

0007In order to reinforce portions of the carton, fold­able reinforcing panels P1, P2, P3 and P4 are provided and which extend across the blank so that portions of the top panel and adjacent portions of the side wall panels can be strengthened. Panels P1 and P4 are prov­ided at opposite side edges of the blank and panels P2 and P3 are provided intermediate the end edges to strengthen a central handle panel H which is flanked on either side by hand gripping apertures G1 and G2. The mechanism described below is adapted to fold the reinforcing panels P1-P4 into superposed relationship with adjacent areas of the blank as shown in stippling in Figures 1a while the blank is conveyed through a packaging machine and the reinforcing panel may be glued to those areas. Referring specifically to Figure 1a, if it is assumed that the carton blank is moved along a feed path in a packaging machine from left to right then the leading edge panel P1 and the leading handle panel P2 are both folded from right to left i.e. against the direction of feed whereas the trailing edge panel P4 and the trailing handle panel P3 are both folded from left to right i.e. with the direc­tion of feed.

0008Referring to Figure 7, a panel folding mechanism 30 is mounted at the infeed end of a packaging machine only a part 32 of the machine being shown. Carton blanks are fed one after the other by suitable feed means in a forwardly and downwardly directed feed path 'F' and each blank is supported immediately below the lower face 30a of the mechanism above the tops of bottles to be wrapped by a known paperfeed conveyor (not shown). The paperfeed conveyor generally comprises an endless chain having a series of spaced upstanding lugs which push the blank along the machine feed path by engage­ment with the trailing edge of the blank.

0009The mechanism comprises a number of folder elements e.g. element 'E' which are mounted in tandem on a series of endless chains 'C' as will now be described in greater detail with reference to figures 2 to 6.

0010Mechanism 30 comprises a pair of similar parallel flank plates 34, 36 spaced apart so as to accommodate between them a bank of six parallel endless chains 'C' mounted in two sets 38, 40, 42 and 44, 46, 48 of three chains each on either side of a central cam plate 50. At one end of the mechanism, the chain sets are entrained about upper coaxial driven sprocket sets 52, 54, 56 and 58, 60, 62 respectively and lower idler sprocket sets indicated by axis 64 (Figure 7) and at the other end of the mechanism about intermediate idler sprocket sets indicated by axis 66 (Figure 7).

0011Folder elements E1-E4 extend transversely between the flank plates 34 and 36 each of the folder elements being of similar construction (Figures 2-4). With reference to Figure 6, folder element E1 is described in more detail. The folder element E1 comprises an elongate bar 68 which is located at each of its oppo­site ends by studs or rollers 70, 72 engaged in guide tracks 74, 76 formed in guide plates 78, 80 respect­ively. The guide plate 78, 80 are attached to the internal juxtaposed faces of the respective flank plates 34 and 36 of the mechanism.

0012The folder element E1 carries a pivotal body 82 in a central aperture 84 of the bar, the pivotal body being of generally H-shaped cross-section and being pivotable about a rod 86. The ends of the rod are received in recesses 88, 90 formed in the bar 68 at opposite ends of the central recess 84 and are retained by removable fasteners 92, 94 respectively. The pivotal body comp­rises a pair of like parallel guidearms 96, 98 extend­ing in one direction from the aperture 84 and a pair of like parallel folder arms 100, 102 extending in the opposite direction from the aperture 84. One of the guide arms carries a cam follower 104 which is located in a cam track 106 formed in one face of the central cam plate 50. The opposite face of the cam plate 50 also is formed with a cam track 108 of different configuration to that of cam track 106 and in which a follower of another of the folder elements engages as described later. Folder body 82 is spring loaded within central aperture 84 by a helical spring 110 to ensure positive engagement between the follower and its associated cam track. The opposed folder arms 100, 102 of the folder body each carry a folder head 112, 114 respectively which engage a reinforcing panel P of the carton blank during the folding process to be desc­ribed. The other folder elements are of like construction.

0013Folder element E1 is connected to chain 38 at one of its ends and also connected to chain 44 intermediate its ends by connecting numbers 116, 118 respectively. These connections are illustrated diagramatically in Figures 2, 3 and 4 by references a, b respectively. Folder elements E2 and E3 are both connected inter­mediate their ends to chains 40 and 46 as indicated by references c, d and e, f respectively. Folder element E4 is connected to chain 42 at one of its ends and also connected to chain 48 intermediate its ends as indi­cated by reference g, h respectively. These connec­tions provide for relative adjustment of the folder elements as will be described later.

0014The folder elements are therefore conveyed in end­less path by the respective chain and sprocket sets so that each folder element moves through a working reach in which the folder heads of the folder element execute a panel folding action in the feed path 'F' and moves through a return path R (Figures 7 and 8) remote from the feed path.

0015The guide plates 78, 80 which include the guide tracks 74, 76 and the central cam plate 50 having opposed cam tracks 106, 108 are provided at the lower end of the mechanism so that the folding elements cooperate with these components of the mechanism only during their movement through the working reach.

0016Referring to Figure 8, one of the folder elements is shown at a number of successive positions about its path of travel and it will be seen by arrows a¹ and a² that the folder heads of the folder element execute a forward and upward pivotal action in relation to the carton blank feed path F. Thus, the folder heads of the element illustrated pivot with the direction of flow and therefore show the action of folder element E4 or E3 which are responsible for folding the trailing edge panel P4 and the trailing handle panel P3 respect­ively of the carton blank. In order to achieve the necessary folding action, first the folder heads strike the reinforcing panel P3 or P4 to be folded at approx­imately folder element position f1 at which location the folder heads pivot the reinforcing panel downwardly out of the plane of the blank and forwardly in the feed direction 'F' of the blank while the folder element itself is moving in the feed direction through the working reach. Of course, the pivotal action is trans­mitted to the folder arms of the pivotal body by the cam follower which moves in a path dictated by the con­tour of the cam track 108. At position f2 the cam track 108 is formed with a trough or valley 108a which causes a forward and upward pivotal action of the associated reinforcing panel P3, P4 so that it is again returned substantially into the plane of the blank but this time into superposed relationship with and secured to the undersurface of the blank i.e. as shown by the stippled areas in Figure 1. The cam track 108 is cont­oured so as to then retract the folder heads from con­tact with the blank by causing the folder arms to pivot downwardly and backwardly as shown by arrow a³ i.e. against the feed direction 'F', to the positions shown at location 'F3' whereafter it then moves out of the work­ing reach and into the return reach of the mechanism.

0017The folder elements E1 and E2 which are responsible for causing the folding of the leading edge reinforcing panel P1 and the leading handle reinforcing panel P2 respectively both have a guide arms whose cam follower is engaged with and constrained to follow the opposed cam track 106 in the central cam plate 50. As prev­iously mentioned, reinforcing panels P1 and P2 are folded against the feed direction 'F' of the carton blank. This entails pivotal movement of the folder arms of elements E1 and E2 which is predominantly rear­ward, relative to the carton feed and upwardly and the contour of cam track 106 is therefore appropriately formed to produce such pivotal action.

0018Referring again to Figures 2, 3 and 4, Figure 2 shows leading and trailing edge panel folder elements E1 and E4 separated by distance 'X' and leading and trailing handle panel folder elements E2 and E3 separated by distance 'Y'. In order to allow other sized carton blanks to be compatible with the mechanism and the dis­tance between leading folder element E1 and trailing folder element E4 is made adjustable as is the distance between folder element E1 and the handle panel folder element E2 and between the folder element E4 and handle panel folder element E2. The distance between the two adjacent handle panel folder elements is not made adjustable since this dimension 'Y' remains constant between the carton panels P2, P3. Figures 2 and 3 show distance Y = Y1 but distance X1 > X.

0019In order to provide for this relative adjustability, reference is now made specifically to Figure 4 which shows folder elements E1-E4 in random relative locations for illustration only and which do not corre­spond to relative spacings for a carton. As prev­iously referred to, handle panel folder elements E2 and E3 are both fixed to the same chains i.e. chains 40 and 46 which are entrained about sprockets 54 and 58 resp­ectively.

0020Further folder element E1 is fixed to chains 38 and 44 which are entrained about sprockets 52 and 58 resp­ectively and folder element E4 is fixed to chains 42 and 48 which are entrained about sprockets 56 and 62 respectively. These sprocket pairs are made adjustable relative to one another by coaxial shaft assembly 'S' which incorporates a spring clutch 'T' to allow the sprocket pairs to rotate together as required in use or alternately to rotate relative to one another as required for adjustment in the distance between the folder elements.