Apparatus for automatically closing L-slide lock cartons
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to improvements in apparatus for closing foldable cartons or cases, and more particularly relates to an apparatus for automatically closing a top flap of an L-slide lock case. 
     2. Description of Background Art 
     There is much prior art on apparatus for setting up as well as closing cartons and the like utilizing various members to contact carton flaps and tuck or insert them for closing purposes. U.S. Pat. Nos. 2,660,012 and 3,002,432 are exemplary of such prior art. 
     Cartons having L-slide locks are commercially available from Stone Container Corp. Such cartons or cases are used by Frito-Lay, Inc. to package bags of snack foods such as potato chips, corn chips, and the like, for shipment. The L-slide locks on the cartons make them easy to close by just inserting the opposite ends of an upstanding flap into the lock slots. L-slide lock cases are used for shipment of snack bags because they are re-usable and can be closed without the use of glue, staples, tape, or other destructive closure means. When the cases are emptied, they are collapsible as set forth in U.S. Pat. Nos. 3,960,313 and 4,007,869, for ease in shipment back to the factory to be refilled. Prior to the present invention, the L-slide lock cases were manually closed after the bags of product were packed into the case. The obvious drawbacks to manual closing are that it is a labor-intensive, time-consuming and hence extremely expensive. 
     There is need in the art for an automatic case closing apparatus for L-slide lock cartons. This need has existed for some time until the present invention. 
     SUMMARY OF THIS INVENTION 
     This invention provides an apparatus for automatically closing L-slide cases in which cases are travelling laterally of their longitudinal axis and intermittently. Folding means form a longitudinal fold in an upstanding open closing flap of the case, the flap having a free longitudinal edge extending laterally across the direction of travel. The fold is formed while the case is held stationary, so that the free longitudinal edge of the closing flap is positioned at about a level with the top of the case, and opposite free end corners of the closing flap are positioned adjacent respective L-slide lock slots in the top of the case. Means for tucking the opposite free end corners of the closing flap into respective L-slide lock slots close the case while it is held stationary by guiding the longitudinal fold of the closing flap to a position at about a level with a top level of the case. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an L-slide lock case with the closing flap in the open position. 
     FIG. 2A is a side elevation view of a case and an automatic closing apparatus according to this invention. 
     FIG. 2B is a front elevation view of the carton and the automatic closing apparatus of this invention. 
     FIG. 3 is a side elevation view similar to FIG. 2A showing the apparatus in an intermediate stage of operation wherein the open flap is folded. 
     FIG. 4 is a perspective view similar to FIG. 1 wherein the open case flap is folded prior to closing. 
     FIG. 5 is a side elevation view similar to FIG. 2A showing the apparatus in the final stage of operation wherein the carton is closed. 
     FIG. 6 is a side elevation view of an automatic closing apparatus according to a second embodiment of this invention. 
     FIG. 7 is a front elevation view of the apparatus shown in FIG. 6. 
     FIG. 8 is a side elevation view with portions broken away of the apparatus shown in FIGS. 6 and 7 at an intermediate case closing stage. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a case 10 of the L-slide lock type commercially available from Stone Container Corp. has previously been packed and needs to be closed. The case travels on a conveyor 12 of any suitable type such as belt, roller, chute or the like in the direction of arrow 14 in FIG. 2A which, as can be seen, is transverse to the longitudinal axis or the long direction of case 10. Conveyor 12 is provided to move the cases 10 intermittently and transverse to their longitudinal axes to a predetermined stationary position relative to the apparatus of this invention, stop the case at that predetermined position and hold the case stationary at that position during the closing operation. 
     In the closing position the case top 16 has extending from a long side thereof an open closing flap 18. See FIG. 1. Top 16 also includes three other flaps 17, 19a and 19b which have previously been placed in the closed position shown in FIG. 1 by means not shown. During the closing operation, the outer free longitudinal edge 20 of open closing flap 18 has its opposite free end corners 21a and 21b tucked into the respective L-slide lock slots 23a and 23b of closed side flaps 19a and 19b respectively. 
     Prior to this invention, such operation of tucking the corners 21a and 21b of the open flap 18 into respective L-slide slots 23a and 23b was a manual operation. This invention automates what was previously a manual operation. 
     An apparatus according to this invention includes means for folding the open closing flap 18 to form a longitudinal fold 25 in the closing flap 18 at a predetermined position between the top 16 of the case and the free longitudinal edge 20 of flap 18. Preferably, flap 18 has been previously scored by the manufacturer along the line at the position where fold 25 is formed. 
     According to one embodiment, the closing flap folding means comprises fold support rods 22 and 24 which may be piston rods of cylinders 26 and 28 respectively which cylinders are rigidly mounted on suitable supports 30. See FIGS. 2A and 2B. Support rods 22 and 24 are selectively positionable to and from a position adjacent the inside surface of the open flap 18 when the open flap extends upwardly, and parallel to the edge of the carton. The reference to &#34;inside&#34; with regard to flap 18 means on the side of the flap toward the center of the carton as distinguished from the &#34;outside&#34; which is the side of the flap away from the center of the carton. 
     The closing flap folding means includes a flap fold guide rod 32 which is connected at each end to levers 34 and 36, the guide rod 32 being positioned to contact the outside surface of the open closing flap 18. Each of these levers is pivoted about stationary pivots 38a and 38b. A driving cylinder 40 is attached to the end of rod 34, the cylinder being pivotedly supported from a support 42. Actuation of the cylinder 40 moves rod 32 to drive the flap fold guide rod 32 over the top of the support rods 22 and 24 to fold the flap in the position shown in FIG. 3, wherein the longitudinal edge 20 of closing flap 18 is positioned at about a level with the top of the case, and opposite free end corners 21a and 21b of flap 18 are positioned adjacent respective L-slide lock slots 23a and 23b. See FIGS. 3 and 4. 
     Means are provided for tucking the opposite free end corners 21a and 21b of closing flap 18 into respective L-slide lock slots 23a and 23b while the case is held stationary. The tucking means is positioned to contact an outside surface of the closing flap, the tucking means including means for guiding the longitudinal fold 25 of closing flap 18 to a position at about a level with the top of the case to cause each of the free end corners to enter the respective L-shaped slots due to the resiliency of the folded top flap, thereby completely closing the case. 
     According to one embodiment, the flap tucking means includes a tucking member in the form of rod 44, the ends of which are connected to links 46 and 48. See FIG. 2A. Each of these links 46 and 48 pivots about stationary pivots 50a and 50b. Link 46 is driven by cylinder 52 pivoted to stationary support 54. See FIG. 3. Actuation of cylinder 52 drives rod 44 to guide the fold flap and close the case as shown in FIG. 5. 
     In operation of the invention the start position is with cylinders 26, 28, 40 and 52 retracted so that the conveyor 12 can move the carton 10 into the position shown in FIG. 2A with flap 18 open and extending vertically upwardly from the top 16 of the carton in its position shown. 
     In the first step of the flap closing operation cylinder 26 and 28 extend moving fold support rods 22 and 24 to the inside surface of flap 18 above the level of the top of the carton a predetermined and predesired distance which will determine where the flap 18 is to be temporarily folded. See FIG. 2B. 
     The next step in the cycle is the extension of cylinder 40 and this is as shown in FIG. 3. With cylinder 40 extended the fold flap guide rod 32 will contact the outside of the open flap 18 and move the flap top edge 20 downwardly and inwardly toward the center of the carton temporarily folding it about a longitudinal fold line 25 defined by the level of the guide rods 22 and 24 with guide rods 22 and 24 supporting the fold. Extension of the cylinder 40 moves the flap fold guide rod 32 to the position of FIG. 3 so that the edge 20 of the flap 18 is at the top surface 16 and heading downwardly just outside the L-shaped slots in the top as shown in FIG. 4. 
     The next step is shown in FIG. 5 in which cylinders 26 and 28 retract moving fold support rods 22 and 24 out of the way and at the same time cylinder 52 extends causing the flap tucking rod 44 to contact the back edge of the folded flap and move it downwardly and inwardly as shown in FIG. 5. This causes the corners of the top edge 20 of the open flap 18 to be tucked into the L-shaped slots quickly, efficiently, and automatically. 
     The next step is a return to the original start position in which cylinders 40 and 52 retract and the conveyor 12 moves the box away from the apparatus and allows another box to enter to be positioned for automatic closing. 
     The height of the closing apparatus above the conveyor can be made adjustable for closing cases of different heights. 
     In another embodiment, means are provided for automatically closing all four top flaps of an L-slide lock carton. According to this embodiment, an upstanding flap 17 is closed first, and both of upstanding flaps 19a and 19b are then closed before the folding and closing of closing flap 18. See FIGS. 1 and 4. An apparatus according to this embodiment is shown in FIGS. 6, 7 and 8. 
     According to this embodiment, conveyor 112 moves a case 10 with all flaps open into the position shown in FIG. 6, wherein the box is stopped by a bar 101 extending transversely across and slightly above conveyor 112. Rotary cylinder 105 then moves pivoting arm 102 up behind case 10 to the position shown in FIGS. 6 and 7, to hold the case in place against bar 101 for closing. 
     It can be seen in FIG. 6 that flap 17 of case 10 is partially closed by boot 103 when case 10 is moved into position against bar 101 for closing. 
     Boot 103 is rotatably connected to bar 133 by means of leg 104 and bearing 109. With arm 102 and bar 101 in the position shown in FIGS. 6 and 7, boot 103 pivots rearwardly to the position shown in FIG. 7 to completely close flap 17. Rearward movement of boot 103 is accomplished by means including lever 106 connecting leg 104 with piston rod 107 and cylinder 108, which cylinder is mounted on a suitable support (not shown). 
     With flap 17 closed, flap slappers 200 and 201 close flaps 19a and 19b respectively, over flap 17. See FIG. 7. Flap slappers 200 and 201 are driven from the upstanding vertical position shown in FIG. 6 to the horizontal position shown in FIG. 7 by rotary cylinders 202 and 203, respectively, the rotary cylinders being mounted on suitable supports (not shown). The case is now ready for the closing of flap 18. 
     According to this embodiment, the closing flap folding means comprises fold support rods 122 and 124 which may be piston rods of cylinders 126 and 128 respectively, which cylinders are rigidly mounted on suitable supports (not shown). As can be seen in FIG. 6, the position of the rods 122 and 124 is just inside of the open closing flap 18 when the open flap extends upwardly, and parallel to the edge of the carton. The reference to &#34;inside&#34; with regard to flap 18 again means on the side of the flap toward the center of the carton as distinguished from the &#34;outside&#34; which is the side of the flap away from the center of the carton. 
     The closing flap folding means includes a pair of flap fold guide shoes 132a and 132b fixedly attached to pivot bar 133 by means of levers 134 and 136, respectively. A driving cylinder 140 is attached to an end portion of bar 133 by means of piston rods 135 and lever 137, the cylinder being supported by a suitable support (not shown). Actuation of the cylinder 140 moves rod 132 to the position shown in FIG. 8, wherein the longitudinal edge 20 of closing flap 18 is positioned at about a level with the top of the case, and opposite free corners 21a and 21b of flap 18 are positioned adjacent respective L-slide lock slots 23a and 23b. See FIGS. 4 and 8. 
     Shoes 132a and 132b provide the means for tucking the opposite free end corners 21a and 21b of closing flap 18 into respective L-slide lock slots 23a and 23b. Shoes 132a and 132b guide the longitudinal fold 25 of closing flap 18 to a position at about a level with the top of the case to cause each of the free end corners to enter the respective L-shaped slots due to the resiliency of the folded top flap, thereby completely closing the case. This is accomplished by continued downward and inward movement of shoes 132a and 132b from the position shown in FIG. 8 in the direction of arrow 210 under the power of cylinder 140. 
     When the case is completely closed, bar 101 drops down by retraction of rod 220 by cylinder 221, the cylinder being mounted on a suitable support (not shown). Pivoting arm 102 is returned to its downward position, conveyor 112 moves case 10 along, and the other components of the apparatus move to the position shown in FIG. 6 in preparation for closing another case. 
     While embodiments of this invention have been shown and described in some detail, it will be understood that this description and the accompanying drawings are offered merely by way of example, and are not to be construed as limiting.