Patent Application
20140056684
The application generally relates to a tray denesting apparatus. The application relates more specifically to an apparatus for automatic denesting or separation of stacked trays used for storage and shipping of food items.
During packaging operations, products may be placed in trays and further processed downstream from the packaging machine. Product trays are typically made of Styrofoam® or similar material. The trays are shipped and stored in nested stacks in which each of the trays conform to and are placed in contact with one another for shipping and handling. During the packaging process each tray must be separated individually from the adjacent tray of the stack prior to filling the tray with a product. Different types of mechanical assemblies have been developed to separate individual trays from a stack of trays for packaging. It is desirable that a tray denester be able to quickly and reliably separate trays from a stack to increase the packaging throughput of a facility.
Current available tray denesters are arranged to present trays to a conveyor system so that the tray is facing upward, in a position to receive product for wrapping. This means that the stacks of trays are placed in the current systems with the useable side facing up. As a result debris, e.g., Styrofoam material from the trays, may collect within the usable area of the tray. Further, such an arrangement does not allow the system to position the trays using the top side of the upper lips on the trays.
Currently tray denesters are configured to separate trays by either capturing the bottom side of the upper lips using a rotary screw conveyor mechanism, or by capturing the bottom of the upper lip using a pivoting rod mechanism. These existing methods are unreliable for denesting most Styrofoam trays because the thickness of the tray lip is not maintained at close tolerances during manufacturing. As a result, the separation mechanism may fail to separate the trays consistently. This does not permit consistent separation location regardless of Styrofoam manufacturing inconsistencies.
Intended advantages of the disclosed systems and/or methods satisfy one or more of these needs or provide other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs.
A tray denesting apparatus, presents stacks of trays placed upside down within a storage area to a picker head mechanism, and separates single trays from the stack of trays. Pneumatically and electrically controlled actuators and slides are employed for handling of the stacked trays. A pneumatic separating device, e.g., a Bernoulli Effect suction pad, may be used to pick and remove individual trays from the tray stack. The Bernoulli principle operates by generating a differential pressure to draw in an object, e.g., a tray, in a materials handling system. The differential pressure can be generated by transporting air through one or more passages in the suction pad to decrease pressure in a chamber. The decreased pressure in the chamber pulls the object towards the pad. After picking up the individual tray an electrically driven rotary device inverts the tray places the tray onto a tray conveyor located beneath the denesting apparatus.
One embodiment relates to an apparatus for automatically positioning trays from a nested stack of trays onto a conveyor includes a tray denester system. The tray denester system includes a stack holder for holding at least one nested stack of trays. The stack holder includes a column wherein the stack holder maintains the nested stack of trays in a face down alignment and biased towards a bottom end of the column. Separation elements are disposed adjacent a bottom end of the stack holder. The separation elements are operable to separate a bottom tray from the nested stack of trays. Pins are disposed beneath the bottom tray and are operable to controllably release the bottom tray. A rotary inverter unit is disposed below the tray denester system. The rotary inverter unit includes suction elements and a drive system arranged to position one of the suction elements at a time below the tray denester system and to receive the bottom tray released from the tray denester. The rotary inverter rotates the received tray to an inverted position and releases the received tray in an inverted position to a conveyor in a face up alignment.
Another embodiment relates to an apparatus for inverting trays for positioning onto a conveyor includes suction elements and a drive system. The drive system position the suction element below a tray denester system to receive a bottom tray released from the tray denester and rotates the received tray to an inverted position. A suction element of the apparatus releases the received tray in an inverted position to a conveyor in a face up alignment.
Still another embodiment relates to a tray handling system which includes a tray denester system, a rotary inverter and a conveyor. The tray denester system positioned above the rotary inverter for iteratively discharging a single tray from a nested stack of trays. The rotary inverter is positioned to receive the single tray, invert and discharge the single tray to the conveyor. The rotary inverter is positioned above the conveyor. The tray denester system including a stack holder for holding at least one nested stack of trays. The stack holder includes a column wherein the stack holder maintains the nested stack of trays in a face down alignment and biased towards a bottom end of the column. Separation elements are disposed adjacent a bottom end of the stack holder. The separation elements are operable to separate a bottom tray from the nested stack of trays. Pins are disposed beneath the bottom tray and are operable to controllably release the bottom tray. The rotary inverter unit disposed below the tray denester system. The rotary inverter unit is disposed below the tray denester system. The rotary inverter unit includes suction elements and a drive system arranged to position one of the suction elements at a time below the tray denester system and to receive the bottom tray released from the tray denester. The rotary inverter rotates the received tray to an inverted position and releases the received tray in an inverted position to a conveyor in a face up alignment. The conveyor is operable to receive a plurality of the received trays one at a time and transport the received tray away from the rotary inverter.
Certain advantages of the embodiments described herein include the stacks are presented inverted—i.e., with the usable topside facing downward—so that the denester may utilizes the fixture topside of the tray and mechanically separate trays with pneumatic cylinders and wedge blocks at a position relative to the fixture inverted top edge.
Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.
Referring to
Prior art tray denesters are configured to separate trays either by capturing the bottom side of the upper lip of the trays using a screw mechanism, or by capturing the bottom of the upper lip using a pivoting rod mechanism. Both methods are unreliable as the thickness of tray lips is not maintained at high tolerances during the tray manufacturing process. As a result, a separation mechanism may fail to separate the trays consistently.
Denester system 10, with stacked trays 18 presented in an inverted position utilizes the fixture topside 26 of tray 18 to mechanically separate adjacent trays through the operation of cylinders 28 connected to separation elements, e.g., wedge blocks 32 at opposing sides of stack holder 20. In one embodiment cylinders 28 may be pneumatically operated, although alternate embodiments may include hydraulic and electrically operated linear displacement actuators. Trays 18 are biased towards a bottom end of column 16. Wedge blocks 32 are positioned adjacent to the fixture or tray inverted top edge 24. Wedge blocks 32 inserted between top edges 24 of adjacent trays 18 provide consistent separation location regardless of dimensional inconsistencies due to the manufacturing of the trays. Pins 34 on opposing sides of stacked trays 18 are retracted to release a single tray at a time. Cylinders 36 control movement of pins 34 for releasing trays 18. After releasing a tray pins are returned to the extended position to retain the trays stack in position for releasing the next tray. Pneumatic cylinders 28 retract wedge blocks 32 to lower the stack of trays 18. When wedge blocks are in the retracted position, the stack descends and is positioned against pins 34. Pneumatic cylinders 28 then extend wedge blocks 32 into the space between peripheral edges 24 of the lowest two adjacent trays 18, to separate the bottom two trays and allow the lowest tray 18 to release during the next cycle.
Referring next to
Inverter unit 30 includes four suction pads 40 attached to and driven by a drive system, e.g., a drive belt 44 in an endless loop. Suction pads 40 may be spaced approximately equidistantly along an exterior side of drive belt 44 and are advanced by drive belt 44 between four positions 45, 46, 47 and 48. At first position 45 suction pad is positioned with the tray receiving surface 38 facing stack holder 20. Drive belt 44 advances suction pads in one direction, which direction is indicated by arrow 42. Drive belt 44 in the exemplary embodiment is a toothed belt that meshes with splines on three idler rollers 52 and a drive roller 54. Drive roller 54 may be, e.g., a servo-motor driven pulley. Teeth 56 and splines 58 provide traction from rollers 52, 54 for moving belt 44. Other belt drive arrangements may be substituted for the toothed belt, including tensioned belts, chain- and wire mesh-driven belts or other power transmission arrangements within the scope of the appended claims. From the first position 45, belt 44 advances suction pad 40 from first position 45 to a second position 46, rotating tray 18 90° to a vertical position in which tray 18 is maintained via suction air. From second position pad 40 is next advanced to the third position 47 by drive belt 44, which causes tray 18 to be rotated an additional 90° to the inverted, or upward facing direction. In third position 47 suction pad tray receiving surface 38 is facing downward, i.e., the direction opposite that of first position 45.
At third position 47, suction pad 40 is controlled by a pneumatic controller 60 to release tray 18 by removing air flow that creates the Bernoulli suction effect. In one embodiment controller 60 may be a pneumatic quad path rotary union which distributes the air to suction pads 40. Each port (not shown) is operated independently through individual solenoid values located remotely. Rotary unions provide a rotating connection feeding pressure to fixtures while allowing full rotation of the union with or without pressure. A machine or independent indexer may be used to accomplish the position indexing. When tray 18 is released at third position 47, tray 18 falls onto a moving conveyor 50 (
In one embodiment, all four suction pads 40 perform operations simultaneously in sequence at their respective positions, e.g. one pad 40 is picking a tray when positioned at first position 45, while the adjacent pad 40 is holding a tray at second position 46, the next adjacent pad is releasing a tray at third position 47, and the fourth pad 40 is idling without a tray at fourth position. In alternate embodiments, the inverter unit 30 may be modified to perform inversion of trays with only one pad 40 advancing through each of the four positions, or with two pads 40 positioned at 180° and advancing through each of the four positions.
It should be understood that the application is not limited to the details or methodology set forth in the following description or illustrated in the figures. It should also be understood that the phraseology and terminology employed herein is for the purpose of description only and should not be regarded as limiting.
While the exemplary embodiments illustrated in the figures and described herein are presently preferred, it should be understood that these embodiments are offered by way of example only. Accordingly, the present application is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims. The order or sequence of any processes or method steps may be varied or re-sequenced according to alternative embodiments.
It is important to note that the construction and arrangement of the tray denesting apparatus as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present application. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present application.
It should be noted that although the figures herein may show a specific order of method steps, it is understood that the order of these steps may differ from what is depicted. Also two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. It is understood that all such variations are within the scope of the application. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.
