Tray forming machine - Patent Review 4936815

Claims

What is claimed is:

1. A tray forming machine for folding a blank of corrugated plastic into a generally upright configuration to form a tray and for securing said tray in said upright configuration, said blank being cut from a sheet of corrugated plastic to define a bottom wall panel and a pair of opposing side wall panels and a pair of opposing end wall panels, said side wall panels and said end wall panels being hingedly connected to said bottom panel along scored fold lines, said tray forming machine comprising:

a frame structure;

an infeed station defined by said frame structure for receiving the blank of corrugated plastic and having a transfer mechanism for conveying the blank of corrugated plastic along a generally linear transfer path, the blank of corrugated plastic defining a plane as the blank moves along said transfer path;

a blank receiving station defined by said frame structure for receiving the blank from said infeed station as the blank is conveyed along said transfer path by said transfer mechanism;

a tray forming ram, said tray forming ram being mounted on said frame structure above said blank receiving station for movement along a generally linear stroke path between a raised position and a lowered position, said stroke path being generally perpendicular to and extending through said plane defined by the blank of corrugated plastic moving along said transfer path;

a forming tool frame, said forming tool frame being mounted on said frame structure, said forming tool frame being positioned beneath said blank receiving station and being generally vertically aligned with said tray forming ram, said forming tool frame defining an opening such that said tray forming ram passes through said opening as said tray forming ram traverses said stroke path;

a plurality of tray forming members, each said tray forming member being connected to said frame structure and extending inwardly relative to said opening of said forming tool frame to obstruct at least a portion of said opening;

clamping means movably mounted on said frame structure and positioned beneath said forming tool frame on opposing sides thereof, said clamping means being mounted to move in a generally horizontal direction between a retracted position displaced from said tray forming ram when in said lowered position and an extended position displaced from said retracted position and disposed proximate to said tray forming ram when in said lowered position; and

fastening means for securing each of the end wall panels to at least one of the side wall panels in the generally upright configuration, said fastening means being mounted in a position such that said fastening means is adjacent to the tray forming ram when the tray forming ram is in the lowered position and when the fastening means if securing one of the end wall panels to one of the side wall panels,

whereby the blank is selectively placed in the infeed station and conveyed by the transfer mechanism to the blank receiving station, at which time the tray forming ram moves downward along the stroke path through the opening of the forming tool frame to the lowered position, the tray forming ram thereby contacting and carrying the blank downward through the opening in the forming tool frame and against the plurality of tray forming members, such that the tray forming members fold the end wall panels and the side wall panels of the blank into the generally upright configuration, the clamping means being in the extended position and the blank being disposed between and contacting both the tray forming ram and the clamping means, the clamping means exerting pressure against the blank in order to clamp the blank against the ram and maintain the blank in the upright configuration as the fastening means secures the end wall panels and side wall panels in the generally upright configuration, the clamping means then moving to the retracted position and the tray forming ram returning to the raised position such that the tray falls downwardly from the tray forming ram.

2. The tray forming machine of claim 1 wherein the opening of the forming tool frame is generally rectangular and the plurality of tray forming members includes a pair of side forming bars and a pair of end forming bars, said side folding bars being connected to the forming tool frame and disposed such that at least a portion of each of the side wall panels contacts one of said side forming bars as the blank is carried downward through the opening in the forming tool frame, said end folding bars being connected to the forming tool frame and disposed such that at least a portion of each of the end wall panels contacts one of said end forming bars as the blank is carried downward through the opening in the forming tool frame, whereby the side forming bars fold the side wall panels into the upright configuration, and the end forming bars fold the end wall panels into the upright configuration.

3. The tray forming machine of claim 2 wherein the side forming bars and the end forming bars are positioned such that at least a portion of each of the end forming bars contacts the end wall panels before the side forming bars contact the side wall panels.

4. The tray forming machine of claim 2 wherein each of the end forming bars has a top and each of the side forming bars has a top, said top of the end forming bars being displaced a distance vertically upward relative to said top of the side forming bars, such that said top of the end forming bars is closer to the raised position of the tray forming ram than said top of the side forming bars.

5. The tray forming machine of claim 2 wherein each of the side forming bars has a pair of opposing ends and each of the end forming bars has a pair of opposing ends, each of the side forming bars being mounted between a pair of side forming brackets, one of said side forming brackets being connected to each of the opposing ends of the side forming bar, said side forming brackets being connected to and extending inwardly from the forming tool frame into and partially obstructing the opening, each of the end forming bars being mounted between a pair of side forming brackets, one of said end forming brackets being connected to each of the opposing ends of the end forming bar, said end forming brackets being connected to and extending inwardly from the forming tool frame and partially obstructing the opening.

6. The tray forming machine of claim 5 wherein the tray has a peripheral top edge when folded to the upright configuration, and wherein each of the side forming brackets has an inwardly projecting lower lip, each said lower lip extending inwardly into the opening sufficiently such that a portion of the peripheral top edge of the tray is engagingly received under said lower lip, whereby each said lower lip exerts pressure downwardly on said peripheral top edge of said tray as the tray forming ram moves to the raised position to strip the tray off the tray forming ram.

7. The tray forming machine of claim 1 further comprising:

means for stripping the tray from the tray forming ram as the tray forming ram moves upward to the raised position.

8. The tray forming machine of claim 7 wherein the tray has a peripheral top edge when folded to the upright configuration, and wherein the means for stripping the tray from the tray forming ram comprises:

a plurality of brackets, said brackets extending from and connected to said forming tool frame, each said bracket including an inwardly projecting lower lip, each said lower lip extending inwardly into the opening sufficiently such that a portion of the peripheral top edge of the tray is engagingly received under said lower lip, whereby each said lower lip exerts pressure downwardly on said peripheral top edge of said tray as the tray forming ram moves to the raised position to strip the tray off the tray forming ram.

9. The tray forming machine of claim 1 wherein the end wall panels each have a pair of opposing side edges, and the blank further includes two pair of end foldover panels, each said end foldover panel extending from and being hingedly connected to one of said side edges of one of said end foldover panels along scored fold lines, said tray forming machine further comprising:

a plurality of end foldover forming bars, each of said end foldover forming bars extending inwardly from a being connected to the forming tool frame and partially obstructing the opening, the end foldover forming bar contact at least a portion of the end foldover panels as the blank is carried through the opening by the tray forming ram such that the end foldover forming bars fold each of the end foldover panels into the generally upright configuration.

10. The tray forming machine of claim 9 wherein the end foldover forming bars and the end forming bars are positioned such that the end foldover panels begin to be folded to the upright configuration by the end foldover forming bars prior to the end panels beginning to be folded to the upright configuration by the end forming bars, and the end panels begin to be folded to the upright configuration by the end forming bars prior to the side panels beginning to be folded to the upright configuration by the side forming bars.

11. The tray forming machine of claim 9 wherein the forming tool frame has a pair of opposing lengthwise sides and a pair of opposing widthwise sides, and wherein the side forming bars are connected to and extend inwardly from said lengthwise sides of the forming tool frame, and the end forming bars and end foldover forming bars are connected to and extend inwardly from said widthwise sides of the forming tool frame.

12. The tray forming machine of claim 9 wherein the forming tool frame has a pair of opposing lengthwise sides and a pair of opposing widthwise sides, and wherein the side forming bars are connected to and extend generally parallel to said lengthwise sides of the forming tool frame, the end forming bars are connected to and extend generally parallel to said widthwise sides of the forming tool frame.

13. The tray forming machine of claim 9 wherein the tray forming ram has a pair of opposing sides, each said opposing side being positioned proximate to and in close confronting contact with one of the side wall panels of the blank as the blank is carried toward the lowered positioned on the tray forming ram, each said side of the tray forming ram defining a pair of recesses, said recesses each receiving one of the end foldover panels when the blank is folded to the upright configuration and carried on the tray forming ram.

14. The tray forming tool of claim 1 wherein the blank has a rear edge, and wherein a second like blank having a rear edge is positioned in the infeed station subsequent to the blank being conveyed to the blank receiving station by the transfer mechanism, and the transfer mechanism for conveying the blank from the infeed station to the blank receiving station comprises:

an infeed hook, said infeed hook mounted for reciprocal movement along a linear track, said track extending from the rear of blank when the blank is positioned in the infeed station to a position generally proximate to the blank receiving station, said infeed hook extending upwardly such that a portion of the infeed hook contacts and pushingly engages the rear edge of the blank when the blank is in the infeed station; and

a rodless cylinder, said rodless cylinder being mounted to the frame and connected to said infeed hook, said rodless cylinder responsively moving said infeed hook along said track to push the blank from the infeed station subsequently returning said infeed hook along said track such that said infeed hook engages the rear edge of the second blank.

15. The tray forming machine of claim 1 further comprising:

conveyor belt means for carrying the tray after the tray has been folded and secured in the upright configuration, said conveyor belt means being disposed beneath the opening of the forming tool frame and the lowered position of the tray forming ram such that when the tray falls downwardly from the tray forming ram the tray drops onto the conveyor belt means and is carried therewith.

16. The tray forming machine of claim 1 wherein the forming tool frame has a pair of opposing sides and the tray forming ram has a pair of opposing lengthwise sides, and wherein the clamping means comprises:

a pair of side clamps, each said side clamp being positioned adjacent to one of the opposing sides of the forming tool frame and on opposing sides of the tray forming ram when the tray forming ram is in the lowered position, each said side clamp being movably mounted to move inwardly and outwardly in a generally horizontal direction relative to the forming tool frame such that the side clamps each contact and press one of the side panels of the blank into clamping contact with the lengthwise sides of the tray forming ram.

17. The tray forming machine of claim 16 wherein the end wall panels each have pair of opposing side edges, and the blank further includes two pair of end foldover panels, each said end foldover panel extending from and being hingedly connected to one of said side edges of one of said end foldover panels along scored fold lines and being folded across said scored fold lines in close confronting contact with one of said side wall panels, and wherein the fastening means comprises:

a plurality of sonic welding devices, each said sonic welding device having at least one welding tip, said sonic welding devices being moveable between an extended position proximate to and closely confronting the tray forming ram when the tray forming ram is in the lowered position and a retracted position displaced from the tray forming ram, said sonic welding devices being capable of sonicly welding the end foldover wall panels to the adjacent and closely confronting side panel with at least one sonic weld when the sonic welding devices are in the extended position.

18. The tray forming machine of claim 17 wherein each of the side clamps defines at least one aperture, said aperture being positioned such that at least a portion of the welding tip of one of the sonic welding devices may be received through the aperture when the sonic welding devices are moved to the extended position proximate to the tray forming ram.

19. The tray forming machine of claim 16 wherein the end wall panels each have an outer planar surface when the blank is folded to the upright configuration, and each of the side clamps has a pair of opposing ends, the side clamps further comprising:

a pair of end clamp members, each end clamp member being connected to and extending inwardly from one of the ends of the side clamp, said end clamp members each contacting and closely confronting the planar outer surface of one of the end wall panels, said end clamp members exerting a clamping pressure on the end wall panels to retain the end wall panels in the upright configuration.

20. The tray forming machine of claim 16 wherein each of the side clamps has a bottom edge, the side clamps further comprising:

a lower side ledge, each lower side ledge being connected to and extending inwardly from the bottom edge of the side clamp, said lower side ledge contacting and closely confronting the base panel of the blank, said lower side ledge exerting pressure upwardly on the base panel to retain the base panel in contact with the tray forming ram.

21. The tray forming machine of claim 16 wherein the side wall panels of the tray and the end panels of the tray angle outwardly at an angle relative to vertical when secured in the upright configuration, and wherein the forming ram has a pair of opposing lengthwise sides and a pair of opposing widthwsise sides, each of said opposing lengthwise sides and said widthwise sides being angled relative to vertical approximately equal to the angle of the side wall panels and the end panels, and wherein the side clamps are angled relative to vertical approximately equal to the angle of the side wall panels.

22. The tray forming machine of claim 21 wherein the side clamps move between the retracted position and the extended position in a vertical direction at an angle relative to horizontal equal to the angle that the side clamps are angled relative to vertical.

23. A tray forming machine for folding a blank of corrugated plastic into a generally upright configuration to form a tray and for securing said tray in said upright configuration, said blank being cut from a sheet of corrugated plastic to define a bottom wall panel and a pair of opposing side wall panels and a pair of opposing end wall panels, said side wall panels and said end wall panels being hingedly connected to said bottom panel along scored fold lines, said he end wall panels each having a pair of opposing side edges, said blank further including two pair of end foldover panels, each said end foldover panel extending from and being hingedly connected to one of said side edges of one of said end foldover panels along scored fold lines and being folded across said scored fold lines in close confronting contact with one of said side wall panels, said tray forming machine comprising:

a frame structure;

an infeed station defined by said frame structure for receiving the blank of corrugated plastic and having a transfer mechanism for conveying the blank of corrugated plastic along a generally linear transfer path, the blank of corrugated plastic defining a plane as the blank moves along said transfer path;

a blank receiving station defined by said frame structure for receiving the blank from said infeed station as the blank is conveyed along said transfer path by said transfer mechanism;

a tray forming ram, said tray forming ram being mounted on said frame structure above said blank receiving station for movement along a generally linear stroke path between a raised position and a lowered position, said stroke path being generally perpendicular to and extending through said plane defined by the blank of corrugated plastic moving along said transfer path;

a forming tool frame, said forming tool frame being mounted on said frame structure, said forming tool frame being positioned beneath said blank receiving station and being generally vertically aligned with said tray forming ram, said forming tool frame defining an opening such that said tray forming ram passes through said opening as said tray forming ram traverses said stroke path;

a plurality of tray forming members, each said tray forming member being connected to said frame structure and extending inwardly relative to said opening of said forming tool frame to obstruct at least a portion of said opening;

clamping means movably mounted on said frame structure and positioned beneath said forming tool frame on opposing sides thereof, said clamping means being mounted to move in a generally horizontal direction between a retracted position displaced from said tray forming ram when in said lowered position and an extended position displaced from said retracted position and disposed proximate to said tray forming ram when in said lowered position;

fastening means for securing each of the end wall panels to at least one of the side wall panels in the generally upright configuration, said fastening means including a plurality of sonic welding devices, each said sonic welding device having at least one welding tip, said sonic welding devices being capable of sonicly welding the end wall panels to the adjacent and closely confronting side wall panel with at least one sonic weld, said sonic welding devices being connected to and carried with the clamping means and moveable between an extended position proximate to and closely confronting the tray forming ram when the tray forming ram is in the lowered position and a retracted position displaced from the tray forming ram.

24. The tray forming machine of claim 27 wherein the tray forming ram has a plurality of corners, each said corner having at least one backup pin attached thereto and aligned with one of the welding tips of one of the sonic welding devices when the tray forming ram is in the lowered position and the sonic welding devices are in the extended position.

25. The tray forming machine of claim 18 wherein the backup pins are movably mounted on the tray forming ram such that the distance between each of the backup pins and the tip of each of the confronting sonic welding devices when the sonic welding devices are in the extended position may be selectively altered.

BACKGROUND OF THE INVENTION

This invention relates generally to machines used to fold a blank into an upright tote container, and particularly to a machine for automatically folding a blank constructed from double-faced corrugated plastic into an upright tray and securing the tray in that upright configuration.

Various machines for folding and securing cartons and tote containers are known to the art. These machines will generally comprise a plurality of stations for feeding a cut blank into a forming area, forming the blank into an upright container by folding certain panels of the blank upwardly and inwardly, and securing those panels together with fasteners, glue, or various tab and slot structures. Some forming machines perform the dual functions of cutting the blank from a roll of sheet material, prescoring the blank at the infeed station, and forming the upright tote container.

These machines operate in a variety of manners depending upon particular design of the type of container being constructed, the type of material from which the blank is formed, and the relative expense of the machine compared to the rate at which it can produce finished containers.

Some machines used predominantly with fiberboard cartons will convey the blank along between a series of assembly stations, with various panels being folded or secured at each step of the process.

Another type of machine commonly referred to as a tunnel-forming type machine has an infeed system which lifts a blank from a stack on a pallet, transfers it laterally to a position over a forming tunnel, and then a mandrel will carry the blank through the tunnel which various components perform folding and sealing operations, with the finished containers being nested at a loading station.

A third type of forming machine, used more extensively with shallow trays formed from rigid materials which are seamed together at the edges, incorporates a female forming die and a mandrel to press the blank into the forming die, and various stripping means to remove the tray from either the mandrel or the forming die.

Several distinct problems with forming corrugated plastic containers have resulted in many containers being folded and secured manually. The blanks may be cut and scored to form individual and hingedly connected panels by an automated die cutting machine, with the blank then being folded by hand and stapled or thermally welded in an upright configuration. Because double-faced corrugated plastic is generally very resilient and has memory properties which resist folding even when deeply scored, unlike fiberboard, it is difficult to manage the steps of folding and holding a container in its upright configuration while securing the panels together.

This resiliency also makes corrugated plastic difficult to use with standard forming tools, because the resistance encountered in carrying the blank through the forming die can cut or tear the planar plys, again with a deleterious effect on the finished container.

The process of producing sonic welds to fasten the panels thermally or physically bonds the three plys of the corrugated plastic sheet material to the three plys in the adjacent and confronting panels. The quality of the sonic weld depends upon the accuracy and uniformity of the gap between the welding head and the backup plate, with poor quality welds resulting in tearing of the generally planar plys and an overall weakening of the tray being formed. Placement of the welds relative to the edges of the panels and the corrugated intermediate ply is also of concern, factors which are difficult to control in both manual and automated tray forming and securing procedure.

Conventional container and tray forming machines encounter significant speed restraints when processing corrugated plastics, and the complex or heavy duty machines capable of running corrugated plastic may often be too complex, expensive, or difficult to repair and maintain to be practical in certain applications.

Another common drawback with several designs of forming machines is their inability to process corrugated plastic blanks having any significant measure of longitudinal or lateral warp, such a warp interfering with the loading or infeeding operations of the blank, or causing the machine to jam or bind during the forming operation. While fiberboard blanks are generally flat, corrugated plastic blanks may develop a warp in excess of 10% of their longitudinal span due to heat and humidity variations. Because the corrugated plastic sheet material is more expensive than fiberboard, and because it is usually easier to visually detect damaged or inferior fiberboard, it is desirable that the tray forming machine be capable of running corrugated plastic blanks having a substantial measure of warp.

While many of the obstacles may be controlled to some degree in a carefully monitored production environment using skilled operators and technicians, these machines will not perform satisfactorily or reliably in situations involving relatively unskilled operators or in the absence of qualified technical help and repair or maintenance equipment. As such, these machines are not suitable for institutional or training use, such as in correctional facilities of trade schools.

In such situations, it is also critically important to build in the greatest degree of safety and operator protection, to minimize the opportunities for the machine to be operated improperly or tampered with, to facilitate simple and rapid repair of even the more complicated features, and to minimize the number of potential technical problems which might result from variations in the consistency of the sheet material, environmental conditions, and the like.

BRIEF SUMMARY OF THE INVENTION

It is therefore one object of this invention to design a tray forming machine which utilizes a tray forming ram and forming tool frame which permits a tunnel-like forming procedure, but which requires only a minimal ram stroke distance and machine cycling period.

It is an additional object of this invention to design the tray forming machine of this invention such that the infeeding of blanks may be operated manually, or the machine may be converted for automated blank feeding.

It is a related object of this invention to design the above tray forming machine such that a blank magazine situated above the infeed station may be utilized rather than a vertical lift type blank feeding apparatus.

It is another object of this invention to design the above tray forming machine so as to utilize a minimum number of moving parts, to consolidate the functions and timing of those parts, and to simplify the operation and maintenance of the machine, while increasing the overall reliability and performance characteristics of that machine.

It is thus a related object to design the above tray forming machine so as to provide for the automatic stripping of individual trays from the ram and forming frame without separate stripping arms or extending the ram stroke, and to output those trays individually from the machine onto a conveyor system.

It is yet another object of this invention to design the above tray forming machine so as to enhance the accuracy and reliability in positioning and aligning the ram, forming tool, and clamping means, and to increase the uniformity of the sonic welds used to secure the tray in its upright configuration.

It is a distinct object of this invention to design the above tray forming machine such that the cycling of the machine may be keyed to the disposition of the ram, and such that certain types of piece-in-place sensors and obstruction interrupts may be utilized in automating the cycling of the machine, to provide for greater operator safety and minimize potential faults or problems in the operation of the machine.

It is a related object of this invention to design the above tray forming machine such that blanks of slightly varying sizes, warps, or consistencies may be utilized in the machine, or may be detected and the cycling of the machine interrupted prior to an unsuccessful attempt to process the defective blank.

Briefly described, the tray forming machine of this invention comprises an infeed station for accepting a blank of corrugated plastic, and a transfer mechanism which automatically conveys the blank along a plane into a blank receiving station between a tray forming ram and a forming tool frame. The tray forming ram moves downward along a vertical path carrying the blank through the forming tool frame, during which the blank is folded into a generally upright tray configuration by a series of vertically displaced side and end forming bars and brackets. The tray forming ram and blank emerge from the forming tool frame and are received in a clamping and welding assembly which holds the blank in position while it is secured by sonic welds into the upright tray. The clamping assembly releases while the tray forming ram returns to its raised position, and the tray is stripped off the tray forming ram by the bottom of the forming brackets. The tray falls due to gravity onto a conveyor beneath the forming tool frame, and the trays are individually removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the tray forming machine of this invention;

FIG. 2 is a cross sectional view of the tray forming machine of FIG. 1 taken lengthwise through line 2--2 in FIG. 1;

FIG. 3 is a cross sectional view of the tray forming machine of FIG. 1 taken widthwise through line 3--3 in FIG. 1;

FIG. 4 is a cross sectional view of the tray forming machine of FIG. 1 taken from above through line 4--4 of FIG. 1;

FIG. 5 is a cross sectional view of the tray forming machine of FIG. 1 taken lengthwise through line 5--5 in FIG. 4;

FIG. 6 is a cross sectional view of the tray forming machine of FIG. 1 taken widthwise through line 6--6 in FIG. 5 showing the side clamps in the extended clamping position;

FIG. 7 is a cross sectional view of the tray forming machine of FIG. 1 taken widthwise through line 6--6 in FIG. 5 showing the side clamps and ram retracting;

FIG. 8 is a partial perspective view of the corner of the ram and forming tool of FIG. 1 showing the corner of a blank in position for folding;

FIG. 9 is a cross sectional view of the convoluted ply embodiment of the double-faced corrugated plastic sheet material from which the blank is cut and folded;

FIG. 10 is a cross sectional view of the beam member embodiment of the double-faced corrugated plastic sheet material from which the blank is cut and folded;

FIG. 11 is a cross sectional end view of the tray forming machine of this invention showing the blank magazine and retractable gripping means;

FIG. 12 is a side elevation view of the bag magazine with a gripping member gripping the bottom blank;

FIG. 13 is a perspective view of the blank folded into the generally upright tray configuration.

FIG. 14 is a partial side elevation view showing the blank being pressed through the forming tool and folding the end panels upward and end fold-over panels inward;

FIG. 15 is a partial side elevation view showing the blank being pressed further through the forming tool; and

FIG. 16 is a partial side elevation showing the blank received in the area below the forming tool and adjacent the side clamps.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The tray forming machine of this invention is shown in FIGS. 1-13 and referenced generally therein by the numeral 10.

The embodiment of the tray forming machine 10 shown is particularly adapted to be used with a blank 12 having a base panel 14, a pair of opposing side panels 16, 18, a pair of opposing end panels 20, 22 with each of the end panels 20, 22 having a pair of end foldover panels 24, 26 extending therefrom, as shown in FIG. 1. The blank 12 is constructed by cutting and scoring a generally planar sheet of double-faced corrugated plastic 28 to form the various panels 14, 16, 18, 20, 22, 24, 26.

The side panels 16, 18 and end panels 20, 22 may respectively be hingedly connected along the lengthwise and widthwise edges of the base panel 14 by prescored fold lines 30, and the end foldover panels 24, 26 may be hingedly connected to the side edges of the end panels 20, 22 by prescored fold lines 32. It may also be desirable, particularly in some applications where a more rigid or stiff blank 12 is preferred, to leave the blank 12 unscored or only score those fold lines 32 connecting the end foldover panels 24, 26 to the respective end panels 20, 22, and permit the tray forming machine 10 to form the hinged fold lines 30 between the lengthwise and widthwise edges of the base panel 14 and the side panels 16, 18 and end panels 20, 22.

The end foldover panels 24, 26 are folded upwardly relative to the end panels 20, 22 of the flattened blank 12 across the fold lines 32 until the end foldover panels 24, 26 are generally perpendicular to the end panels 20, 22. The end panels 20, 22 may then be folded upwardly relative to the base panel 14 across fold lines 30, with the end foldover panels 24, 26 being pivoted inwardly across the fold lines 30 relative to the base panel 14, until the end panels 20, 22 form an angle .beta. with the base panel 14 somewhat greater than 90.degree.. The side panels 16, 18 are then folded upwardly relative to the base panel 14 across the fold lines 30, until the inner planar surface of each side panel 16, 18 contacts the outer planar surface of one of the end foldover panels 24, 26 connected to each of the end panels 20, 22. In this manner, the blank 12 is folded to the upright tray configuration 36 as shown in FIG. 13. The side panels 16, 18 may then be fastened to the end foldover panels 24, 26 such as by a plurality of sonic welds 38 to secure the tray 36 in this generally upright configuration. It is noted that the end edges of side panels 16, 18 are cut at an angle .differential. relative to the fold lines 30 between the side panels 16, 18 and the base panel 14 substantially equal to the angle .beta. between the end panels 20, 22 and base panel 14 when the end panels 20, 22 are folded into position in the generally upright tray configuration 36. Similarly, the side edges of each end panel 20, 22 are cut at an angle .phi. relative to the fold lines 32 between the end panels 20, 22 and the end foldover panels 24, 26 substantially equal to the angle .beta., such that the side panels 16, 18 and end panels 20, 22 each have a generally tapered, outward slant when folded into position in the generally upright tray configuration 36.

In folding the tray 36 into the generally upright configuration using an automated tray forming machine 10 of the type of this invention, it may sometimes be unnecessary or undesira