Tray separator method and apparatus

A method and apparatus for separating a stack of trays, each tray being comprised of a plurality of spaced apart containers arranged in rows and columns and interconnected by webs located at their upper, open ends, the containers of each tray in the stack being nested within the containers of an adjacent tray, the space between the tops of adjacent containers in a row or column and the space between adjacent webs forming linear pathways through the stack. The apparatus includes a magazine for holding a stack of the trays. The magazine includes a plurality of first and second support fingers located at the first and second ends of the stack. First and second support linear actuators cause the support fingers to be extended to a stack support location during a non-separation mode of operation, and cause the support fingers to retract to a non-stack support location during the separation mode of operation. A plurality of separator fingers are positioned in alignment with opposing linear pathways formed between the lowermost tray in the stack and the tray adjacent thereto. A separator linear actuator cause the separator fingers to retract to a location out of contact with the stack during a non-separation mode of operation, and to cause the separator fingers to be substantially fully inserted into the linear pathways during a separation mode of operation. The separator fingers are configured to expand the distance between adjacent webs during insertion to cause the lowermost tray to detach from the tray adjacent thereto.

BACKGROUND OF THE INVENTION

The present invention relates to a method of separating nested trays of containers from a stack thereof, and an apparatus for carrying out the method.

Plastic containers, such as those made by injection molding high density polyethylene, are widely used for a variety of purposes, such as for holding plant cuttings and seedlings, packing berries, etc. A typical such array of containers is shown inFIG. 1and consists of a plurality of containers joined together at their upper edges to form a tray of containers. Such trays are stacked together with the exterior of the containers of an upper tray nesting inside the containers in the tray immediately below, as seen inFIG. 2. During shipping the nested containers tend to become tightly compacted. The nursery man or berry packer must separate or “de-nest” the individual trays for use, which currently is done manually. Since the containers have thin walls, it is easy for the person attempting to separate the trays to damage some of them. Typically up to 25% of the trays are damaged during separation. The damaged trays must be discarded, leading to a large amount of wastage.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method and apparatus for separating container trays from a stack of such trays which minimizes or eliminates damage to the trays.

The separator apparatus of the present invention for separating a stack of trays. Each tray is comprised of a plurality of spaced apart containers arranged in rows and columns and interconnected by webs located at their upper, open ends. The containers of each tray in the stack is nested within the containers of an adjacent tray. The space between the tops of adjacent containers in a row or column and the space between adjacent webs form linear pathways through the stack.

The apparatus includes a magazine for holding a stack of the trays. The magazine includes a plurality of first and second support fingers located at the first and second ends of the stack. First and second support linear actuators cause the support fingers to be extended to a stack support location during a non-separation mode of operation, and cause the support fingers to retract to a non-stack support location during the separation mode of operation.

A plurality of separator fingers are positioned in alignment with opposing linear pathways formed between the lowermost tray in the stack and the tray adjacent thereto. A separator linear actuator cause the separator fingers to retract to a location out of contact with the stack during a non-separation mode of operation, and to cause the separator fingers to be substantially fully inserted into the linear pathways during a separation mode of operation. The separator fingers are configured to expand the distance between adjacent webs during insertion to cause the lowermost tray to detach from the tray adjacent thereto.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1shows a rectangular container tray10consisting of a plurality of interconnected containers12arranged in rows and columns. Tray10is formed by any suitable plastic forming process, such as injection molding. Each container12is connected to adjacent containers12at their upper edges by webs14.

For purposes of illustration tray10is shown containing three rows of five containers, or five columns of three containers, for a total of fifteen containers per tray. However, the separator method and apparatus of the present invention may be used with container trays containing a different number of containers so long as they are arranged in rows and columns with space in between forming linear pathways.

As seen inFIG. 2, a plurality of container trays10are nested together to form a stack20for shipment to a customer. For purposes of illustration, stack20is shown as containing twenty-one nested container trays10. Although the containers12of one tray are nested within the containers12of an adjacent tray, there is a small space between adjacent webs14, as shown by spacing arrows16inFIG. 10as well as a small space between the tops of adjacent containers12. The space between adjacent webs14and between the tops of adjacent containers12form linear pathways through stack20.

An overall view of the tray separator apparatus100of the present invention is shown inFIG. 3. Tray separator100has a horizontal table top102attached to a plurality of vertical legs104and stabilizing cross-members106, only one of which is shown inFIG. 3. Legs104may have wheels108attached to their lower ends to allow for easy movement of tray separator100.

Table top102has a rectangular opening110located at the rearward end thereof, as best seen inFIGS. 5-8. Rectangular opening110has a length and width that is slightly larger than the length and width of tray10. Vertically disposed tray support members112extend upwardly from the corners of opening110a distance adapted to hold an inverted stack20of trays10. Tray support members112are L-shaped in cross-section, and together with bottom cross-members114form a stack feed magazine adapted to receive a stack20of trays10.

A chute116is located below opening110to deliver a separated tray10away from separator apparatus100in the direction shown by arrow118inFIG. 3.

As seen inFIG. 4, a separator pneumatic linear actuator120comprising cylinder122and piston124is located at the forward end of table top102with the longitudinal axis thereof being substantially perpendicular to the forward edge of opening110and substantially at the midpoint thereof. Although a pneumatic linear actuator is preferred, a hydraulic linear actuator other linear actuator could be employed. A horizontally disposed separator finger holder bar126is perpendicularly attached to the outer end of piston124. The proximal ends of a plurality of separator fingers130are perpendicularly attached to holder bar126and extend substantially to the forward edge of opening110when piston124is in its fully retracted configuration. The number of separator fingers130are equal to the number of openings between containers12in tray10facing separator fingers128which, the case of tray10illustrated inFIG. 1, would be four openings resulting in the use of four fingers.

An enlarged view of the distal end of a single separator finger130is shown inFIG. 9, all of the separator fingers130having identical configurations. The rearward portion132of finger130is substantially circular in cross-section. The upper and lower surfaces of the outer tip of separator finger130located at the distal end thereof are flattened and slope downwardly toward the tip to form a wedge portion134. A spreader fin136extends downwardly from the bottom of separator finger130with its forward end being adjacent the rearward end of wedge portion134. Spreader fin136is higher at its rearward end than at its forward end, i.e., slopes downwardly from front to rear.

Wedge portion134is of a size and shape that allows insertion into the space formed between adjacent containers12in the rows of containers of lowermost tray10of stack20and the space16formed between webs14of lowermost tray10and the webs14of the tray adjacent thereto; seeFIG. 10. The spaces formed between adjacent containers12in the rows of containers of lowermost tray10of stack20and the spaces16formed between webs14of lowermost tray10and the webs14of the tray adjacent thereto form linear pathways through stack20. The height of each linear pathway is the distance between web14of the lowermost tray10and the web of the tray adjacent thereto, and the width of each linear pathway is the distance between adjacent containers in the lowermost tray.

A first stack support pneumatic linear actuator140comprising cylinder142and piston144is located adjacent the left side of opening110with the longitudinal axis thereof being perpendicular thereto. A horizontally disposed stack support finger holder bar146is perpendicularly attached to the outer end of piston144. The proximal ends of a plurality of stack support fingers148are perpendicularly attached to holder bar146and extend inwardly a distance into opening110adapted to support the left end of a stack20of trays10placed in the stack holder magazine when piston144is in its fully extended configuration. The number of support fingers148are equal to the number of openings between containers12in tray10facing support fingers148which, the case of tray10illustrated inFIG. 1, would be two openings resulting in the use of two fingers. Stack support fingers148are preferably circular in cross-section, but can be of any size and shape adapted to support one end of a stack20of trays.

A second stack support pneumatic linear actuator140′ is located adjacent the right side of opening110, and is identical to first actuator140.FIGS. 5-8show the components of stack support pneumatic linear actuator140′. Stack support pneumatic linear actuator140′ is comprised of cylinder142′ and piston144′, and is located adjacent the right side of opening110with the longitudinal axis thereof being perpendicular thereto. A horizontally disposed stack support finger holder bar146′ is perpendicularly attached to the outer end of piston144′. The proximal ends of a plurality of stack support fingers148′ are perpendicularly attached to holder bar146′ and extend outwardly into opening110a distance adapted to support the right end of a stack20of trays10placed in the stack holder magazine when piston144′ is in its fully extended configuration. The number of support fingers148′ are equal to the number of openings between containers12in tray10facing support fingers148′ which, the case of tray10illustrated inFIG. 1, would be two openings resulting in the use of two fingers. Stack support fingers148are preferably circular in cross-section, but can be of any size and shape adapted to support one end of a stack20of trays.

First and second stack support pneumatic linear actuators140,140′ act in synchronization, i.e., they advance and retract support fingers148and148′ at the same time. Although pneumatic linear actuators are preferred, hydraulic linear actuators other linear actuators could be employed

Separator pneumatic linear actuator120and stack support pneumatic linear actuators140and140′ are connected to a compressed air source (not shown) via a valve150and conduits (not shown) extending between valve150and actuators120,140, and140′. In a first, non-separation mode, separator pneumatic piston124and separator fingers130are in their fully retracted position, and the pistons144,144′ and support fingers148,148′ of stack support pneumatic linear actors140and140′ are in their fully extended position, as shown inFIG. 4. Upon placing valve150into separation mode, separator pneumatic linear actuator120extends separator fingers130outwardly and support pneumatic linear actuators140,140′ retracts stack support fingers148,148′, as shown inFIGS. 5 and 6. After separation of the lowermost tray10in stack20, valve150is placed into its non-separation mode which retracts separator fingers130inwardly and extends support fingers148,148′ outwardly, as shown inFIGS. 7 and 8. The cycle is repeated until all of the trays10in stack20have been separated.

In operation, a stack20of trays10are inverted and placed into the stack feed magazine of separator apparatus100, as seen inFIGS. 1 and 4. Stack20is supported over opening110by support fingers148,148′. Valve150is placed into separation mode causing separator fingers130to be advanced towards the opposing linear pathways located between the lowermost tray10and the tray adjacent thereto. Wedge portion132located at the outer end of each separator finger130penetrates its opposing linear pathway, entering space16between the webs14of the lowermost tray10in stack20and the webs14of the tray adjacent thereto. As separator finger130penetrates deeper into the space16, wedge portion132pushes adjacent webs14apart and allows spreader fin134to enter an enlarged space16and push the adjacent webs14farther apart, as shown by space16′ inFIG. 11. Upon complete insertion of separator finger130into space16, the lowermost tray10is completely separated or detached from stack20and drops down chute116in the direction of arrow118, as shown inFIG. 3. The separated tray10can be manually removed, or dropped onto a conveyor belt (not shown) for removal downstream.

Valve150is then placed into non-separation mode, and separator fingers130are retracted and support fingers148and148′ are extended to provide support for the remaining trays10in stack20. The cycle is then repeated until all of the trays10have been separated from stack20.

Valve150has been described as being manually operated. However, it could be operated by a computer to provide automatic cycling between separation and non-separation configurations.