Manipulating Apparatus For A Container Forming Machine

Abstract

A manipulating apparatus for a machine adapted successively to form containers from container blanks, having selectively facingly engageable side panels and construction flaps, utilizing coacting mandrel and die assemblies. The manipulating apparatus has a lever assembly pivotally mounted on the mandrel assembly and a cam interconnects the lever assembly and machine for pivotal movement of the lever assembly into edgeward engagement with the flaps correctly to position the flaps relative to their respective side panels during formation of the container from the blank by the machine.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a manipulating apparatus for a container forming machine and more specifically to such an apparatus which is adapted automatically and precisely to position the construction flaps of a container forming blank with precision in engagement with selected side panels of the blank during formation of the container thereby insuring that the containers formed by such a machine are consistently of the precise desired configuration.

While container forming machines currently in use operate adequately to form containers of a variety of types, a frequently encountered deficiency resides in the fact that such machines operate with some variation in positioning construction flaps in adhesive facing engagement with side panels of the blanks from which such containers are formed. Normally in such machines the construction flaps are designed to be folded inwardly for precise overlapping, adhesive engagement by selected side panels to form the container. However, structural resistance of the blank to folding and variation in the operation of the machine frequently result in the formation of containers in which outer corners of the flaps protrude from the container. These protrusions interfere with mechanized packing of the containers as well as offer resistance to the sealing of the containers subsequent to packing. This may lead to jamming of packing and sealing machines. Perhaps more importantly, such an improperly constructed container is of impaired strength which can result in collapse or rupture of the container during such activities as stacking, shipping, and storing.

Such deficiencies, of course, result in losses of commercial significance. Damage to equipment, the expense of repairs, production delays, and the damage to or complete loss of the products deposited in such containers are not only aggravating but also economically unacceptable. Such losses can be particularly acute in the case of perishable items such as vegetables and fruits.

Therefore, it has long been recognized as desirable to have a manipulating apparatus adapted for use on container forming machines to insure that all containers formed by such machines are of a dependably consistent configuration and strength. It has also been recognized as desirable to have such a manipulating apparatus which is of simplified construction requiring no auxiliary mechanical sources of power or dependence on manual operation.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a manipulating apparatus for use on container forming machines.

Another object is to provide such an apparatus which insures that containers produced by container forming machines are of a consistently uniform and useable configuration.

Another object is to provide such an apparatus which operates automatically during normal operation of the forming machine accurately to position the construction flaps of container blanks in facing engagement with the side panels thereof.

Another object is to provide such an apparatus which does not require manual or auxiliary power for operation.

Another object is to provide such an apparatus which operaties cooperatively with a container forming machine without interfering with it.

Another object is to provide such an apparatus which is of simplified construction for reliable operation and ease of maintenance.

A further object is to provide such an apparatus which is adjustable for use in the formation of a variety of types of containers on a variety of types of forming machines.

Still further objects and advantages are to provide improved elements and arrangements thereof in an apparatus for the purposes described which is dependable, economical, durable and fully effective in accomplishing its intended purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary side elevation of a container forming machine showing the manipulating apparatus of the present invention mounted thereon.

FIG. 2 is a perspective view of the machine shown in FIG. 1 mounting the manipulating apparatus.

FIG. 3 is a plan view of a container forming blank.

FIG. 4 is a fragmentary perspective view of the manipulating apparatus showing the first form of pressure arms thereof in their operative relationship with respect to the blank shown in FIG. 3 during formation into a container.

FIG. 5 is a plan view of a second form of container forming blank.

FIG. 6 is a fragmentary horizontal section of the manipulating apparatus showing a second form of pressure arm therefor in its operative relationship with respect to the blank shown in FIG. 5 during formation into a container.

FIG. 7 is a fragmentary vertical section taken from a position indicated by line 7--7 in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The applicant is the patentee of several patents on container forming machines and portions thereof. Among these are U.S. Pat. Nos. 3,590,700; 3,611,885; and 3,618,792.

Referring more particularly to the drawings, the manipulating apparatus of the present invention is generally indicated by the numeral 10 in FIG. 1. The manipulating apparatus is shown mounted on a fragmentarily represented container forming machine 11. It will become apparent that the apparatus of the present invention is adapted for use on a wide variety of types of container forming machines. The specific machine fragmentarily shown in the drawings and described herein is employed for illustrative convenience. The machine has a frame 12 having spaced, substantially parallel, transversely extending frame members 13.

The machine 11 is adapted successively to deliver container forming blanks to a predefined planar position therein, subsequently to be described. As will be seen, the manipulating apparatus 10 is adaptable for use with a variety of types and configurations of blanks depending, of course, upon the type of container to be produced. The blank shown in FIGS. 1 through 4 is of the type used in the formation of a container known in the trade as a "tray". The blank is generally indicated by numeral 14. The blank is of one-piece construction having scored fold lines 15 bounding a substantially rectangular bottom wall 16. The blank has oppositely, sidewardly extending side panels 17 and oppositely endwardly extending end panels 18. As best shown in FIG. 3, the side and end panels are of substantially rectangular configuration. The blank has scored fold lines 19 to define construction flaps 20 extending endwardly from each of the end panels as shown in FIG. 3. The side and end panels 17 and 18 respectively have outer edges 21. The flaps have outer edges 22 which are aligned with the outer edges 21 of the end panels, as shown in FIG. 3.

The forming machine 11 has a die assembly 25 on the frame 12. As best shown in FIG. 2, the die assembly has upper die plates 26 mounted on the transverse frame members 13 substantially normal thereto. The die assembly also has corresponding lower die plates 27 mounted on the transverse frame members in spaced, substantially parallel relation to the upper die plates so as to define an interior 28 for the die assembly. The interior of the die assembly serves as a forming position for the machine. A pair of rod assemblies 29 interconnect corresponding upper and lower die plates bounding the interior of the die assembly so as rigidly to maintain the plates in spaced, substantially parallel relation.

A pair of return bent upper flap plow members 30 are secured on the frame 12 laterally adjacent to the upper die plates 26. Similarly, a pair of lower flap plow members 31 are affixed on the frame laterally adjacent to the lower die plates 27. The plow members are mounted in predetermined positions extending outwardly from the die assembly in spaced relation. The die plates 26 are upwardly bent adjacent to the plow members 30 to form end panel folding portions 32. Similarly, the lower die plates 27 are downwardly bent to form end panel folding portions 33. Two pair of side panel folding assemblies 34 are affixed on the frame 12, the assemblies of each pair being mounted individually adjacent to their respective upper or lower plow members 30 and 31, as shown in FIG. 2. Each of the assemblies has an inner folding surface 35.

The frame 12 of the forming machine 11 mounts a pair of support members 40 in spaced, substantially parallel relation in alignment with the interior 28 of the die assembly 25. A guide rail 41 is borne by each of the support members extending longitudinally thereof. Each of the guide rails has a forwardly extending end 42 in proximity to the die assembly and a substantially flat upper surface 43.

A mandrel assembly 50 is mounted for reciprocal movement in the guide rails 41 of the forming machine 11. The mandrel assembly includes a pair of slide members 51 individually, slidably mounted in the guide rails 41 for reciprocal movement therealong. Each of the members has an upwardly extending back portion 52 having an upper edge 53 and a forwardly extending end 54 adjacent to the die assembly 25 of the machine. An upright, substantially rectangular forming wall 55, having an interior surface 56, is secured on the back portion 52 of each slide member at the forwardly extending end thereof. A pair of cross bars 57 rigidly interconnect the forming walls in spaced, substantially parallel relation in vertical alignment with the ends 54 of the slide members, as perhaps best shown in FIG. 2. The forming walls and cross bars have forwardly extending edges 58 defining a contact portion for the mandrel assembly of a rectangular configuration substantially corresponding to the configuration of the bottom wall 16 of the container blank 14. A cylindrical connection rod 59 is mounted on the forming walls so as to extend therebetween substantially parallel to the cross bars.

A sleeve 65 is rotationally mounted on the connection rod 58. A power arm 66 is secured on the sleeve and extended to a suitable source of power, not shown, borne by the forming machine 11 for controlled reciprocal movement of the power arm. As shown in FIGS. 1 and 2, the planar position to which the container blank 14 is delivered by the machine is between the mandrel assembly 50 and die assembly 25.

The manipulating apparatus 10 of the present invention is mounted on the mandrel assembly 50. The apparatus has a pair of mechanisms or lever assemblies 75 which are individually mounted on the slide members 51 of the mandrel assembly. Each of the lever assemblies has an outer mounting plate 76 and an inner mounting plate 77. As perhaps best shown in FIG. 2, the mounting plates of each lever assembly are mounted on opposite sides of the back portion 52 of their respective slide member by a bushing assembly 78 extending through the back portion and plates. The bushing assemblies mount the lever assemblies at corresponding positions spaced from the forwardly extending ends 54 of the slide members. A guide plate 79 is affixed on each outer mounting plate 76 in edgeward engagement with the upper edge 53 of the back portion of its respective slide member so as to define a space of predetermined width between the guide plate and the inner mounting plate. A spring connection bolt 80 is fastened on the back portion of each slide member in spaced relation to the mounting plates, as shown in FIG. 2.

Each of the lever assemblies 75 has a lever arm 85 mounted in the space defined by the guide plate 79 and inner mounting plate 77. Each of the lever arms has an upper portion 86, a central or pivot portion 87 and a trailing portion 88. The pivot portion of each arm has a bushing hole 89. Each lever arm is mounted on its respective bushing assembly with the assembly extending through the bushing hole so as to mount the lever arm for pivotal movement between the guide plate and inner mounting plate about the bushing assembly. The upper portion of each lever arm has a plurality of mounting bores 90 aligned so as to extend longitudinally of the upper portion. The upper portion of each lever arm has a spring connection bore between the mounting bores and the pivot portion of the arm. A cam follower, wheel or roller 92 is borne by the remote end of the trailing portion 88 of each lever arm extending inwardly for engagement with the upper surface 43 of its respective guide rail 41, as best shown in FIG. 2. A rest roller 93 is mounted in predetermined position on the trailing portion of each lever arm extending outwardly therefrom for rested engagement with the upper edge 53 of the back portion 52 of its respective slide member. A tension spring 94 interconnects the upper portion of each lever arm and its respective slide member by individual fastening at its opposite ends with the spring connection bolt 80 and connection bore 91 resiliently to maintain the rollers 92 and 93 in engagement with the upper surface 43 and upper edge 53 respectively.

A guide 100 is mounted on the interior surface 56 of each forming wall 55 in a position substantially centrally thereof. Each of the guides defines a passage 101 extending therethrough defining a path of travel substantially parallel to that of the slide member 51. A guide bar 102, having opposite ends 103, is pivotally mounted on the upper portion 86 of each lever arm 85 by means of a bushing assembly 104 extending through the guide bar and a selected one of the mounting bores 90. The other end of each guide bar is extended for reciprocal movement through the passage of its respective guide so as to be retained in substantially parallel relation to its respective slide member. The bushing assembly is adapted releasably to mount the guide bar in any one of the mounting bores for purposes subsequently to be described. Each guide bar has a longitudinally extending slot 105 intermediate the opposite ends thereof.

A first form of pressure arm 110, having opposite ends 111 and a plurality of mounting holes 112 extending in alignment longitudinally of the arm intermediate the opposite ends, is mounted on each of the guide bars 102. Pressure arm 110 is specifically adapted for use on a container forming machine 11 designed to use the container blanks 14. Each of the pressure arms is mounted in spaced, substantially parallel relation to its respective guide bar by a pair of bolt assemblies 113 extending through the slot 105 of the guide arm and selected holes of the pressure arm. The bolt assemblies thus retain the pressure arm on the outside of the forming wall 55 of the mandrel assembly 50, as best shown in FIG. 2. A laterally extending pressure plate 114 is secured, as by welding, on the end of the pressure arm adjacent to the planar position of the machine 11. A pair of control or cam plates 115 are individually affixed in upstanding relation on the upper surface 43 of each guide rail 41 in corresponding predetermined positions adjacent to the forwardly extending ends 42 thereof. Each of the cam plates has a sloped upwardly extending cam way 116 of a specialized configuration for purposes subsequently to be described.

As previously noted, the container blank 14 shown in FIG. 3 is of a design commonly employed in the construction of containers referred to in the trade as trays. Another form of container blank is shown in FIGS. 5 through 7 and generally referred to by the numeral 124. This blank is of one-piece construction having scored fold lines 125 defining a central, substantially rectangular bottom wall 126 having oppositely extending side panels 127 and end panels 128. The blank has scored fold lines 129 defining laterally extending construction flaps 130, as described in regard to container blank 14. The construction flaps have outer edges 131. Bland 124 differs from blank 14 in that it has scored fold lines 132 which define integral laterally extending lid panels 133, as best shown in FIG. 5.

In order to permit the use of the manipulating apparatus 10 of the present invention with container forming machines 11 utilizing container blank 124, a second form of pressure arm 140 is adapted to be mounted on each of the guide bars 102 in place of the first form of pressure arm 110. In this form of machine, the forming walls 55 of the mandrel assembly 50 are preferably constructed so as to provide a rectangular opening 141 extending from the trailing edge thereof in the direction of the planar position of the machine substantially centrally thereof, as right-angularly shown in FIG. 7. The pressure arm is right-angurarly bent so as to form a flange portion 142 and a central portion 143. The flange portion has a rectangular passage 144 therein of dimensions equal to or slightly larger than the cross sectional dimensions of the guide bar 102. Integrally extended from the end of the central portion of the pressure arm remote from the flange portion are a pair of spaced pressure plates 145 defining a plane substantially parallel to the flange portion, as best shown in FIG. 6. The pressure plates are spaced a distance equal to or slightly greater than the width of the guide bar. Each pressure arm is mounted on its respective guide bar with the bar extended through the rectangular passage 144 of the flange portion and the arm retained in position by a spring loaded mounting assembly 146 extending through the slot 105 of the guide bar and adapted to urge the pressure plates 145 laterally from the guide bar, as best shown in FIG. 6.

OPERATION

The operation of the described embodiment of the subject invention is believed to be clearly apparent and is briefly summarized at this point. As previously noted, the manipulating apparatus 10 of the present invention operates automatically during normal operation of the container forming machine 11 on which the apparatus is mounted. In the case of a machine employing container blanks 14, the blanks are delivered at successive intervals to the planar position, as shown in FIG. 2. Normally, an adhesive is applied to the construction flaps 20 and/or side panels 17 of the blank immediately prior to delivery of the blank to the planar position. The machine operates in the conventional fashion to motivate the power arm 66 toward the forming position. Such movement of the power arm drives the mandrel assembly 50 in the direction of the container blank in the planar position. In the conventional manner the mandrel assembly contacts the container blank to engage the bottom wall 16 of the blank to thrust the blank toward the forming position in the die assembly 25. The extended configuration of the upper and lower flap plow members 30 and 31 respectively, insures that the construction flaps 20 are first folded along fold lines 19 during continued movement of the mandrel assembly. Shortly thereafter, the side panel folding assemblies 34 and the upper and lowr end panel folding portions 32 and 33 fold their respective side and end panels 17 and 18 respectively of the blank. Thus, the panels are folded about the mandrel assembly in the conventional fashion with the construction flaps positioned inwardly of the container during formation with respect to the side panels, as shown in FIG. 4.

Continued movement of the mandrel assembly 50 into the die assembly 25 causes the container blank 14 to be folded into the configuration shown in FIG. 4 in the forming position. As previously discussed, such movement of the mandrel assembly within the die assembly frequently leaves the outer edges 22 of the construction flaps 20 protruding from the outer edges 21 of the side panels as shown in FIG. 4 due to resistance of the blank to folding and variation in the operation of the machine. This is undesirable for the reasons noted particularly in that it creates a container of substantially weakened construction and can interfere with the operation of other container handling machines.

The manipulating apparatus 10 of the present invention is adapted to alleviate this problem where it occurs by forcing the protruding outer edges 22 of the construction flaps 20 inwardly of the container to the desired position. This is accomplished automatically during movement of the mandrel assembly 50 into the die assembly 25. As can perhaps best be seen in FIG. 1, movement of the mandrel assembly in the direction of the die assembly causes the lever assemblies 75 correspondingly to be motivated in the direction of the die assembly with the cam rollers 92 thereof in engagement with the upper surfaces 43 of the guide rails 41. During continued movement of the mandrel assembly, the cam rollers 92 are drawn upwardly along the cam ways 116 of the cam plates 115. This causes the lever arms 85 to be pivoted in a clockwise direction, as viewed in FIG. 1, about their bushing assemblies 78 against tension of the springs 94. The guide bars 102 are thus motivated longitudinally through their respective guides 100 in the direction of the die assembly. As a result, the pressure arms 110 mounted thereon are motivated in the same direction. As the mandrel assembly approaches its most extended position, the pressure plates 114 of the pressure arms are brought into engagement with the protruding outer edges 22 of the construction flaps 20, as best shown in FIG. 4. Thus, during the remainder of the movement of the mandrel assembly, the pressure plates force the construction flaps fully within the interior of the newly formed container where the adhesive retains the construction flaps in the precise configuration desired. It will be noted that in the conventional fashion the forming walls 55 of the mandrel assembly maintain pressure against the construction flaps so as to insure proper adhesive bonding of the construction flaps to the side panels.

To complete a cycle of the machine 11, the mandrel assembly 50 is withdrawn from the die assembly 25 by the power arm 66. During such withdrawal, the cam rollers 92 are drawn downwardly along the cam ways 116 of the cam plates 115. Thus, the guide bars 102 and pressure arms 110 mounting the pressure plates 114 are motivated to the retracted position shown in full lines in FIG. 1. The tension springs 94 insure that the cam rollers are maintained in engagement with the cam ways or upper surfaces 43 of the guide rails 41. With one cycle completed, the container forming machine 11 again operates to deliver a container blank 14 to the planar position shown in FIGS. 1 and 2 for folding into a container, as described above.

Where the container forming machine 11 is utilizing the container blanks 124, the manipulating apparatus operates substantially as previously described except with respect to the second form of pressure arm 140. The blanks 124 are delivered to the planar position shown in FIGS. 1 and 2 with respect to container blank 14 and the mandrel assembly 50 is motivated toward and into the die assembly 25 to fold the blank into substantially the configuration shown in FIG. 4 except that the lid panels 133 of blank 124 are forwardly extended as shown in FIG. 7. As the pressure arms are moved toward the die assembly by the mandrel assembly and as a result of pivotal movement of the lever assemblies 75, the pressure plates 145 may contact the extended lid panels of the container. Where this occurs, the spring loaded mounting assembly allows the pressure plates to be inwardly deflected by the lid panels and thence to pass inwardly thereof as shown in FIG. 6. Damage to the lid panels is thereby precluded. As can best be seen in FIG. 7, the tension of the mounting assemblies 146 maintains the pressure plates 145 in sliding engagement with the lid panels during movement toward the protruding outer edges 131 of the construction flaps 130. Thus, the pressure plates are directed against the flaps to force them into the desired position described above.

It will be seen that the guide bars 102 are adapted selectively to be vertically and/or longitudinally repositioned on the upper portions 86 of the lever arms 85. Similarly, the pressure arms 110 and 140 are adapted to be longitudinally repositioned on the guide bars 102. Such adjustment permits the manipulating apparatus 10 to operate on a container forming machine utilizing container blanks of a wide variety of configurations. As previously noted, a rectangular opening 141 is preferrably provided in each of the forming walls 55 when container blanks 124 are employed in the machine. Such an opening acts to accommodate endward movement of the pressure arms 140 where the forming walls of the machine are particularly wide and similarly to accommodate longitudinal adjustment of the pressure arms for the handling of containers of relatively shallow depth. It will also be seen that the apparatus can be converted from handling blanks 14 to handling blanks 124 by simply removing pressure arm 110 and replacing it with pressure arm 140.

The manipulating apparatus of the present invention is adapted for use on virtually all types of container forming machines automatically to insure that such machines operate with dependable consistency to form containers of uniform preselected configuration having maximum strength. The apparatus is of simplified construction requiring no auxiliary sources of power while being adjustable to handle containers of a wide variety of configurations.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the illustrative details disclosed.

Claims

I claim:

1. In a container forming machine having means for the delivery of a container blank which has integral side panels and construction flaps to a planar position and including coacting mandrel and die means operable concurrently to thrust the blank along a substantially rectilinear path of travel to fold selected panels and flaps of the blank into facing engagement to form a container in a forming position; a manipulating apparatus comprising a pressure plate; a mechanism borne by the mandrel mounting the plate form movement relative to said mandrel and to and from the forming position; and cooperative cam means mounted on the mechanism and machine and engageable during movement of the plate to and from the forming position to operate the mechanism to urge said plate relative to the mandrel into edgeward engagement with the flaps upon thrusting of the blank to the forming position to position said flaps relative to the side panels.

2. The apparatus of claim 1 in which the mandrel is mounted for reciprocal movement to and from the forming position, the pressure plate is mounted on the mechanism extending laterally of the mandrel and the cam means includes a cam way mounted on the machine and a cam follower mounted on the mechanism engageable during movement of the mandrel to the forming position to operate the mechanism to advance said plate to the forming position relative to the mandrel.

3. The apparatus of claim 2 in which a guide member interconnects the mechanism and the mandrel to guide movement of said plate relative to the mandrel along a path substantially parallel to that of the mandrel.

4. The apparatus of claim 1 in which a side panel of the container blank mounts a laterally extending lid panel foldable with said side panel in the forming position so as to extend parallel to said rectilinear path of travel and the pressure plate is resiliently mounted in laterally extending relation on the mechanism and deflectable inwardly by said lid panel during movement into engagement with the flaps.

5. The apparatus of claim 4 in which an opening is provided in the mandrel to accommodate longitudinal movement of the pressure plate relative to the mandrel.

6. In a container forming machine having means for the delivery of a container blank which has integral side panels and construction flaps to a planar position and including coacting mandrel and die means wherein the mandrel has a blank contact portion and is mounted on the machine for reciprocal movement and the mandrel and die means are operable concurrently to thrust the blank along a substantially rectilinear path of travel to fold selected panels and flaps of the blank into facing engagement to form a container in a forming position; a manipulating apparatus comprising a pair of pressure plates; a pair of lever assemblies mounted on the mandrel and borne thereby along predetermined paths of travel during movement of said mandrel, each of said assemblies mounting one of the pressure plates for edgeward engagement with selected flaps of the blank in the forming position and including a lever arm pivotally mounted on the mandrel in trailing relation to said contact portion of the mandrel and wherein each lever assembly includes a guide bar pivotally mounted on its respective lever arm and has a remote portion reciprocally mounted on the mandrel for movement relative and substantially parallel to said mandrel; and control means including a pair of cam ways individually mounted on the machine in predetermined positions within said paths of travel of the lever assemblies and further including a cam wheel mounted on each lever asemblies and further including a cam wheel mounted on each lever arm spaced from the pivotal connection thereof at a position operably engageable with its respective cam way as said contact portion of the mandrel approaches the forming position to urge its pressure plate into edgeward engagement with the flaps upon thrusting of the blank to the forming position to position said flaps relative to the side panels.

7. The apparatus of claim 6 in which the lever assembly further includes a pressure arm secured on each of the guide bars individually mounting the pressure plates in laterally extending relation in predetermined positions spaced from the contact portion of the mandrel.

8. The apparatus of claim 7 in which the side panels of the container blank individually mount laterally extending lid panels foldable with said side panels in the forming position so as to extend parallel to the path of travel of the mandrel and the pressure arms are resiliently mounted in laterally extending relation from their respective guide bars inwardly deflectable by said lid panels during movement into engagement with the flaps.

9. The apparatus of claim 8 in which openings are provided in the mandrel to accommodate longitudinal movement of the pressure arms relative to the mandrel.

10. A manipulating apparatus for a container forming machine having a frame mounting a die assembly and a reciprocal mandrel assembly, having a contact portion borne by a pair of slide members, and adapted to deliver a container blank, having flap and panel portions, to a predetermined position for cooperative folding by the die and mandrel assemblies of selected flap and panel portions of the blank into engagement to form a container, the apparatus comprising a pair of lever arms individually pivotally mounted on the slide members of the mandrel assembly spaced from the contact portion thereof; a pair of cam members affixed on the frame in individual alignment with the lever arms; a pair of guide members, having opposite end portions, individually pivotally secured on the lever arms at one of their end portions and mounted for reciprocal movement on the mandrel assembly adjacent to the contact portion thereof at the other of their end portions; a pressure plate affixed in predetermined position on each of the guide members and extending laterally from their respective guide members; and cam means borne by each arm and individually engageable with the cam members during reciprocal movement of the mandrel assembly to motivate the pressure plates into engagement with selected flaps to position said flaps relative to their respective panels during folding of the container.