CA2360641A1 - Fruit tray denesting apparatus - Google Patents

Abstract

An apparatus is described for supplying contoured packing trays, such as molded pulp apple trays, from a nested stack of trays onto an associated conveyer. The apparatus includes receptacles for holding nested stacks of trays, and sensors which protect the operator while he/she is reloading the receptacles. Rails are positioned above the receptacles which extend to a position above the conveyer. A slidable carriage moves on the rails from a first position over the nested stack of trays to a second position above the conveyer, and the movement of the carnage is pneumatically driven. The carriage includes a system of manifolds, which deliver low vacuum to soft, flexible suction cups provided on the carriage. The use of large surface area suction cups and low vacuum helps to control one at a time delivery of trays from the nested stacks.

Description

FRUIT TRAY DENESTING APPARATUS
FIELD OF THE INVENTION
The invention relates to an apparatus for supplying fruit packing trays from nested stacks to a fruit packing operation such as a conveyer belt.
BACKGROUND OF THE INVENTION
Fruit is often packed into molded pulp or plastic fruit handling trays for shipping, storing and displaying the fruit. Apple-packing trays, which are commonly made of molded pulp fiber, are rectangular in shape and have integrally-formed "pockets" for holding apples. The surface topology of the trays is irregularly-shaped due to the fruit-holding pockets and other structural features such as reinforcing ribs and the like which strengthen and rigidify the trays.
In an apple packing facility, the trays are received in nested stacks. To be filled, the trays are denested from the nested stacks and placed one at a time onto conveyer belts. On the conveyer belts, the trays are filled with apples. Thereafter, the trays filled with apples are packed into shipping boxes for delivery.
1 S In most fivit packing operations, denesting of the trays and loading the trays onto a conveyer belt to be filled with fruit is an automated operation. Machines for accomplishing this are known in the prior art. See, for example, U.S. Pat. 4,305,691 (Mayer);
U.S. Pat. 4,789,291 (Allan); and U.S. Pat. 5,876,180 (Suns).
There is a need in the art for an improved manner of operation, improved reliability and improved safety in a tray dispensing machine.
SUMMARY OF THE INVENTION
An object of the invention is to provide an apparatus which reliably and easily separates packing trays from a nested stack for one-at-time delivery of the trays to a conveyer belt for loading with fruit.
It is a further object of the invention to provide an apparatus which can deliver more than one tray at a time to the conveyer in a side-by-side manner, while providing the trays in the correct orientation for packing on the conveyer.
It is a further object of the invention to provide an apparatus which can be safely reloaded with nested stacks of trays without shutting down the apparatus.
With these objectives in mind, the invention comprises an apparatus for loading trays, such as molded pulp fruit packing trays, from a nested stack (or stacks) of trays onto a conveyer belt. In this apparatus, the trays are loaded from beside of the conveyer, rather than from above the conveyer as done in many prior art machines.
The apparatus includes a main frame which accommodates tray hoppers to hold nested stacks of packing trays. Positioned on the main frame above the nested stacks of packing trays are slide rails, which extend from above the tray stacks to above the conveyer, and define the path over which the trays move as they are denested from the stacks and released above the conveyer belt. On the slide rails is mounted a slidable carriage, which is moveable from a tray pick-up position, above the tray stacks, to a tray drop position, above the conveyer belt.
1 S Adjacent to the main frame of the apparatus is a conveyer belt onto which the trays are dropped.
The carriage assembly comprises a number of tray-grasping suction cups, which hold the trays during delivery from the nested stacks to the conveyer belt. Vacuum is delivered to the suction cups using a series of manifolds. From a source of vacuum, vacuum is delivered to a central manifold positioned in the carriage. From the central manifold, vacuum is supplied to front and rear sub-manifolds, which sub-manifolds are moveable vertically relative to the carnage for lifting a tray from a stack of nested trays. The suction cups are provided on the sub-manifolds. As explained further in the detailed description, the front and rear sub-manifolds are independently actuatable, so that a first end of a tray may be lifted using one sub-manifold, followed by lifting of the other end of the tray by the other submanifold.
The vacuum used is a low vacuum source, such as a centrifugal blower. The suction cups used to pick up the trays have a large surface area and are formed of a very flexible material (e.g.
soft rubber such as latex). This combination of low vacuum and large, flexible suction cups has been found to reduce the tendency of the vacuum suction to lift more than one tray at a time from a nested tray stack.
In operation, the carriage picks the top tray from the nested stack of trays in the tray hopper(s). After a tray (or trays) has been picked up by the carriage, the carriage moves to its tray drop position above the conveyer belt. Sensors positioned in association with the conveyer -5 belt detect the correct position of the tray above the conveyer belt for release. At the correct tray drop position, vacuum to the manifolds is stopped, the tray is released from the carriage, and the tray is allowed to drop onto the conveyer. Release of the tray can be assisted by separate push-off means provided on the carnage. Upon release of the trays onto the conveyer, the carriage returns to the tray pick-up position, thereby completing a cycle of tray pick-up/tray release operation.
A further aspect of the invention is to allow reloading of the tray hoppers in the machine safely and without shutting down the machine. To accomplish this, a light curtain is provided across an area through which an operator must pass when loading trays into the hoppers. The sensing function of the light curtain can control movement of the carriage.
When the carriage is in a safe position, an operator may break the light curtain for purposes of reloading, and the carriage will remain in a safe position until the interruption of the light curtain ceases.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevational view of an embodiment of the apparatus of the invention.
Figure 2 is a top plan view of the embodiment of Figure 1.
Figure 3 is an enlarged side view partially broken away showing one of the carriage components of this apparatus holding an apple packing tray.
Figure 4 is a top plan view of the carriage component shown in Figure 3.
Figure 5 is a front view of the carriage component shown in Figures 2 and 3.
Figure 6 is a detailed view of a form of denesting blade used in a preferred embodiment to help regulate the release of trays one at a time from the nested stacks of trays.
Figure 7 is a schematic cross-sectional view showing how the soft suction cup can conform to the contour of the fruit tray.

DESCRIPTION OF THE PREFERRED EMBODIIVVIENTS
The apparatus of the invention finds particular applicability for dispensing molded pulp fruit trays, such as apple packing trays. In particular, the large surface area suction cups and low vacuum used to lift the trays is particularly important in the case of molded pulp articles.
Molded pulp articles are porous, and vacuum can penetrate through the depth of the tray, reaching the next tray in a nested stack. Thus, the need to avoid picking up multiple trays with the suction cups is particularly important when using molded pulp trays.
However, it should be apparent that the apparatus as described will be operable in connection with trays made of various other, nonporous materials, such as plastic.
Referring to the drawings, a main frame 10 is shown in Figure 1. The main frame forms generally an interior in which a stack of trays 11 is positioned in tray hoppers. The trays are stacked in upright position in the hoppers, that is, with the fruit-contacting surface of the trays facing upwards. As seen in Figure 1, the hoppers holding the tray stacks are associated with tray lifts 12, which bias the stacks of trays upwardly. The hoppers include a laterally-moving escapement bar 52, which biases the tray stack sideways against stationary registration bar 52a.
In the illustrated embodiment having three tray stacks lla, llb and llc (see Figure 2), the stacks are positioned adjacent to one another inside the main frame. In operation, a tray from each of these stacks, or a tray from less than each of the stacks, can be delivered at the same time to the conveyer belt. This is useful where, for packing, the trays must be fed to the conveyer in different orientations or combinations for loading, such as when using certain count sizes of apple packing trays. For that reason, contml over the delivery of trays from stacks lla, l lb and l lc is independently controlled. For example, a first cycle may comprise delivery of three trays (11 a; l l b, l l c), and alternate cycles may deliver only two trays (11 a, l l b). Positioning of apple trays for proper packing of different sizes of apples is well-known to those who work in the art.
~ Positioned in association with the main frame 10 of the apparatus is a conveyer belt 13. In operation, trays are removed from the nested stacks and placed onto the conveyer to be delivered to a packing station, to be filled with fruit.
Positioned above the conveyer belt 13 and above the nested stacks of trays 11 are slide rails 14 and 14a. As shown in Figures 1 and 2, the slide rails 14 and 14a are positioned to extend from above the nested stacks of trays to above the conveyer belt. In the embodiment having three stacks of nested trays, the slide rails are associated with the carriage as shown in Figure 2.
A carriage 20 is slidably positioned' on the slide rails and extended and retracted by a pneumatic drive. For example, one of the slide rails comprises a servo-pneumatic, rodless cylinder 14a , and the piston of the rodless cylinder is affixed to the carriage by bracket 21.
As best seen in Figure 2, the carriage can comprise three identical carriage components shown as 20a , 20b and 20c. In the embodiment shown, the three carnage components 20a , 20b and 20c move together on the slide rails from the tray pick up position to the tray drop position, although each carnage component need not necessarily pick up and carry a tray during every cycle.
As shown in Figure 1, the carriage 20 is moveable from a first tray pick-up position 18 on the slide rails above the nested stacks of trays, to a second tray drop position 19 on the slide rails above the conveyer belt. In the first position, the carriage is positioned to accept a tray from the top of the nested stacks. Carrying the tray, the carriage moves into the second position, above the conveyer belt, where the tray is dropped from the carnage and deposited onto the conveyer.
The movement of the carnage 20 on the slide rails is pneumatically controlled.
It has been found that, using pneumatic control, the movement of the carriage on the slide rails can be more carefully controlled, for example, to decelerate the carriage as it approaches its terminal positions above the tray stacks and above the conveyer belt. In this way, undesirable slamming and jarring of the machine is avoided.
With reference to Figure 2, the components of the currently preferred embodiment of the carriage 20 will be described in detail. Initially, it can be noted that, in this embodiment, carriage components 20a, 20b and 20c are structurally identical. Reference will be made to component 20a as being exemplary of each of the like carriage components 20a, 20b and 20c.
The carnage comprises a main carriage frame 25 to which the various structural components of the carriage are mounted. Affixed to the main carriage frame, and running the length of the three carriage components substantially along the center of the entire carriage, is central manifold 2Z. Central manifold 22 is connected to a source of low vacuum (only slightly lower than atmospheric pressure), such as a centrifugal pump (not shown).
Importantly, the central manifold is divided into discrete zones 22a, 22b and 22c, which are actuated independently, or optionally together, by the vacuum source. This allows for control over the tray delivery, such that trays can be delivered from each, or from less than all, of the nested stacks during a given cycle of operation.
Provided at the front and rear, respectively, of each of the carriage zones is a front sub-manifold 23 and a rear sub-manifold 24 (see Figure 2). The front and rear sub-manifolds are connected to the main carriage frame by guided cylinders 26. The guided cylinders permit the sub-manifolds to be raised and lowered with respect to the main carnage frame, for example, to drop down and pick up a tray from the nested stack. As explained in more detail herein, it is important that front sub-manifold 23 and rear sub-manifold 24 are also independently actuated, and can be raised and lowered relative to the main carriage frame in a separate, controlled timing sequence.
As seen in Figures 2-4, in each carriage component the central manifold 22 is provided with vacuum portals 27 and 28. In the embodiment shown, the portals 27 supply vacuum to the front sub-manifold, and independently thereof, the portals 28 supply vacuum to the rear sub-manifold.
A detailed side view of the currently preferred sub-manifolds is shown in Figures 3 and 5.
Sub-manifold connectors 30, 31 receive vacuum supplied from the central manifold 22. More particularly, the portals 27, 28 on the central manifold are connected to the sub-manifold connectors 30, 31, which may be conventional PVC tube joints. Vacuum is supplied by the sub-manifold connectors to sub-manifold main chamber 32. Suction cup stem 33 is affixed to the.
main chamber 32, and cup stem 33 receives cup rod 34, to which is attached suction cup 40. The suction cup holding arrangement as described is held in place on the sub-manifold by clamp 35.
The suction cup 40, attached to cup rod 34, is biased downwardly (Figures 3 and 5) by spring 36. The biasing action of the spring allows the suction cup rod 34 to be displaced upwardly by contact with the tray, for example, to help accommodate the irregular shapes or warpage that can occur in molded pulp packing trays.
While only two suction cup holding arrangements are shown in Figure 3, the other suction cups are arranged and connected to vacuum source in a similar fashion.
The number of suction cups on each sub-manifold can vary. In the illustrated embodiment, there are four suction cups 40a provided on the rear sub-manifold, and four suction cups 40b provided on the front sub-manifold, as shown in Figures 4 and 5.
An important aspect of the invention involves the use of soft, flexible, high surface area suction cups 40. As noted above, when lifting molded pulp trays from a nested stack of trays, there can be a tendency for a vacuum suction applied to a top tray to pass through the porous material to pull through the top tray onto underlying trays, such that the vacuum picks up more than one tray at a time. Applicants have found that this problem can be minimized or avoided by reducing the vacuum, and using high surface area suction cups for grasping the trays. Using a larger suction cup contact area 42, which contacts a larger surface area of the tray surface during lifting of the tray, the use of a lower vacuum is possible. The necessary vacuum can be supplied to the suction cups by a source of low vacuum such as a centrifugal blower or fan. A satisfactory vacuum has been found to be about 1-3 psi below atmospheric pressure. For comparison, denesting machines using smaller suction cups normally supply a vacuum of about 7-8 psi below atmospheric pressure.
The suction cups preferably have contact areas 42 which are about 2-4 inches, most preferably about 3 inches, in diameter. Since the surface of most trays is irregularly contoured, it is preferred to form the suction cups of a soft, flexible material, such as latex rubber, to allow the cups to conform to the contour of the tray surface, to form a tight seal regardless of the particular surface topology of the tray. In a currently preferred embodiment, the soft, flexible suction cups are very thin, having a thickness of about 10-50 thousandths of an inch. In a currently most preferred embodiment, the suction cups are about 3 inches in diameter, are formed of soft latex rubber, and are about 20 thousandths of an inch thick. Flexibility of the suction cups is important, since the different commercial brands of packing trays have different three-dimensional surface patterns of grooves, ridges and the like. The use of the described embodiment, wherein the suction cups have a large, flexible contact surface, and in which the cups are spring-mounted to provide further flexibility, and in which only low vacuum is applied, has been found to considerably facilitate the reliable, one-at-a-time denesting of all of the various commercial brands of apple tray, irrespective of surface configuration. Any of the various available styles of packing tray can be loaded into this apparatus, and no change to the apparatus is needed when one brand of tray is replaced with another brand in the tray stacks 11. Similarly, different count sizes of trays having the same length and width dimensions can be loaded into the hoppers for denesting with no change to the equipment being needed to accommodate the different sizes.
Control over the release of a single tray at a time from the stacks is further facilitated by a denesting blade arrangement 50, as shown in Figure 6. The denesting blade arrangement 50 is positioned adjacent to each stack of trays, near the top of the stack, from where the uppermost tray in the stack is removed during each cycle. In the tray hoppers, the trays are biased such that tray edges 51 are pressed against stationary bar 52a. Blade piston 53 is held by mounting bracket 54 close to the tray stack. Denesting blade 55 is held to the piston by connector 56. The denesting blade 55 consists, for example, of a thin metal strip. By action of the piston 53, the denesting blade is moveable from a withdrawn position (shown in Figure 6) to an engaged position as shown in phantom outline, where the blade moves into contact with the edges of the top few trays in the tray stack. This provides additional resistance against more than one tray becoming disengaged from the stack at a time.
As shown in Figure 1, the conveyer belt 13 is narrower than the tray being held by the carriage. Photoeyes 60 can sense the presence of a tray on the conveyer. When a tray is not sensed, a signal is generated which deactivates the vacuum to the sub-manifolds and releases trays onto the conveyer. Release of the trays from the carnage can be further assisted by push-off cylinders 70 (Figures 3, 4) which by mechanical action, air j et or the like push the tray off the carriage when the vacuum is cut, thereby overcoming any residual attachment of the tray to the suction cups and forcing the tray to drop onto the conveyer belt.
In another aspect of the invention, the tray hoppers can be safely refilled with fresh trays without shutting down or significantly interrupting the operation of the apparatus. To accomplish this, a sensing zone such as a light curtain is provided across an area of the main frame of the apparatus, as shown at 80 in Figure 1. In the illustrated embodiment, the machine is loaded from area 80, and an operator cannot reload the tray hoppers without entering, and breaking, the light curtain. The system is configured such that breaking of the light curtain without prior user activation of an appropriate reload sequence will shut down operation of the machine, including all movement of the carriage. To permit refilling without stopping the overall operation, however, means are provided to initiate an appropriate reload sequence when the hoppers are in need of refilling.
To initiate the reload sequence, a signal from the operator allows entry into the light curtain, but only if the carriage position is appropriate for operator entry.
To assure proper positioning of the carriage , the position of the carriage is continuously sensed by sensing means (e.g. proximity sensors, not shown) positioned on or associated with the slide rails. Pneumatic power to the carnage is controlled by the slide rail sensing means, such that movement of the carnage can be stopped when appropriate control signals are sensed.
Thus, in another significant aspect, the invention concerns an apparatus for supplying fruit trays to a conveyer, wherein a slidable carriage is moveable from a position over the tray stacks to over the conveyer, and where an opening area is provided for the operator to refill trays into the apparatus hoppers. A sensor associated with the opening area detects the unsafe presence of an operator in the opening area (i.e. while reloading is being done) and limits or stops movement of the carriage during reloading. The specific sequence of control over the carriage can be accomplished in any of a number of ways, the objective in each instance being to protect the operator from injury caused by movement of the carriage.
For example, when a timer is activated, the light curtain may be breached for a specific, predetermined period of time (e.g 45 seconds) to permit refilling of the hoppers. Activation of the timer need not itself stop movement of the carriage. Rather, the system may be coordinated such that, after activation of the timer, the light curtain may only be breached without deactivation of the machine if the carriage is sensed to be in a safe position, that is, moving away from the operator. If both conditions are met (timer activated, carriage moving in a safe direction) the operator may enter the light curtain without shutting down the machine, and return movement of the carriage is suspended. When the light curtain is reestablished, the carnage can resume its cycle. The action can be repeated during the duration of the timed interval.
Alternatively, the operation could be such that the initial timer activation holds the carriage in a safe position until the operator withdraws.
In this manner, safe refilling of the hoppers is permitted with only minimal disruption to the operation, and no need for complete shut-off of the machine during reloading.
In operation, one or more nested stacks 11 of packing trays are loaded into the tray hoppers. The tray lifts 12 serve to bias the stacks upwardly towards engagement with the suction cups on the carriage. The topmost tray is removed by pulling it through escapement mechanisms 52, 52a and 55.
To remove the top tray, the sub-manifolds lower from the carriage main frame such that the suction cups associated with the sub-manifold contact the tray surface and grasp the top tray in the stack. To break the seal between trays more reliably, one of the sub-manifolds (e.g. the rear sub-manifold) is raised just prior to the other, to break the vacuum between the top tray and the next tray in the stack. Thereafter, the other sub-manifold is raised, and at that point, both sub-manifolds are in the raised position, and the tray is ready for delivery.
Thereafter, the carriage 20 moves across the slide rails 14 and 14a to the tray release position above the conveyer. In the tray-release position, the vacuum pressure to the suction cups on the sub-manifolds is discontinued. At the same time, push off cylinders 70 apply force to disconnect the tray from the suction cups and allow it to fall onto the conveyer. The tray moves down the conveyer into a packing operation, to be filled with fruit, and the carriage returns on the guide rails to the tray pick-up position, to initiate the next cycle of operation.
The operation of the apparatus as described has been found to load fruit trays quickly and reliably. For example, using the embodiment having 3 tray stacks, it has been found that about 40-45 trays per minute can be loaded onto the conveyer.
The skirts 41 of suction cups 40 are very pliable so as to allow the skirt to closely contact the contour surfaces of the fruit trays, as shown in Figure 7.
The various components of which the apparatus is formed are conventional mechanical equipment. For example, various types of sensing devices are commercially available and can be formatted to accomplish the manner of operation described above.
While the invention has been described in its currently preferred form, various modifications of these specific embodiments will be apparent to those in the art.

Claims (7)

1. An apparatus for supplying contoured packing trays from a nested stack of trays onto an associated conveyer, the apparatus comprising:
at least one receptacle for holding a nested stack of packing trays;
slide rails positioned above the receptacle and extending to a position above the conveyer;
a slidable carriage positioned on the slide rails so as to be moveable from a first position over the nested stack of trays to a second position above the conveyer;
soft, flexible suction cups provided on the carriage, positioned for contact with the top tray of the nested stack when the carriage is in the first position; and a high flow source of low vacuum to the suction cups.

2. The apparatus of claim 1, wherein the carriage comprises a central vacuum manifold and front and rear sub-manifolds.

3. The apparatus of claim 2, wherein vacuum is provided to the central vacuum manifold and distributed to the front and rear sub-manifolds.

4. The apparatus of claim 1, wherein the suction cups are formed of thin, flexible rubber.

5. The apparatus of claim 4, wherein the suction cups have a diameter of 2-4 inches.

6. The apparatus of claim 1, further comprising loading hoppers into which nested stacks of trays are loaded, and sensors associated with the loading hoppers to sense the presence of an operator loading trays into the loading hoppers.

7. The apparatus of claim 6, wherein the movement of the slidable carriage is controlled by the sensors associated with the loading hoppers.

9. An apparatus for loading molded pulp fruit trays from nested stacks onto a conveyer, comprising:
at least one receptacle for holding a stack of molded pulp fruit trays in a position proximate to the conveyer;
a moveable carriage positioned on a slide rail to move from a first, tray pick-up position to a second, tray drop, position to deliver trays from the receptacles to the conveyer; and a pneumatic drive which moves the carriage back and forth from the said first position to the said second position.

10. The apparatus of claim 10, comprising three tray receptacles positioned side by side proximate to the conveyer, and in which the carriage moves into the first position above each of the stacks of trays simultaneously.

11. The apparatus of claim 10, wherein the carriage comprises suction cups for grasping the trays, and further comprises a system of manifolds for delivering vacuum from a vacuum source to the suction cups.

13. The apparatus of claim 11, wherein the suction cups are formed of soft, flexible material, have a surface area of about 2-4 inches, and are mounted to the manifolds by flexible spring-biased connections.

14. The apparatus of claim 11, wherein the manifold system comprises a front sub-manifold and a rear sub-manifold mounted on a central manifold frame, and wherein the front sub-manifold and the rear sub-manifold can be independently raised and lowered relative to the central manifold frame.

15. An apparatus for supplying packing trays from a nested stack of trays onto an associated conveyer, the apparatus comprising:
at least one receptacle for holding a nested stack of packing trays;
an opening area associated with each receptacle through which an operator must pass to load trays into the apparatus;
a slidable carriage moveable between a position over the tray receptacles to a position over the conveyer; and a sensor associated with the opening area which detects the unsafe presence of an operator in the opening area and restricts movement of the slidable carriage if the presence of an operator is detected.

16. The apparatus of claim 15, wherein the sensor is a light curtain.

17. The apparatus of claim 16, further comprising additional sensors which detect the position of the slidable carriage.

18. The apparatus of claim 17, wherein the movement of the slidable carriage is accomplished with a pneumatic drive.

19. The apparatus of claim 1, further comprising a denesting blade positioned to facilitate separation of the trays from the nested stack.