US3477592A - Denester - Google Patents

Description

Nov. 11, 1969 R. M. KUHLMAN 3,477,592

DENESTER Filed March 27, 1968 3 Sheets-Sheet 1 `NOV. 11, 1969 R,.M, KUHLMAN 3,477,592

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Fina/(Jn, .Sawfzf/ 5 UnitedStates Patent O U.S. Cl. 214-85 5 Claims ABSTRACT OF THE DISCLOSURE An apparatus for successively denesting individual articles from the bottom of a stack of articles arranged in nested relation. The stack initially rests upon a poweractuated indexing means when the latter is in an extended position. While the stack is so disposed, it is resiliently engaged and retained in said position by a power-actuated stack-holding means.` Simultaneous with the stack being resiliently engaged by the stack-holding means, a projecting portion of a stripper element is positioned between the peripheries of the two lowermost articles in the stack. The indexing means is then retracted so as to be spaced laterally from the bottom of the stack, whereupon the stripper element projecting portion is moved downwardly relative to the stack-holding means causing thelowermost article to become denested from the remainder of the stacked articles.

BACKGROUND OF THE INVENTION In the packaging industry it is common practice when handling, storing, or shipping in bulk a large number of empty cartons (e.g. molded pulp egg cartons) to nest the cartons together when the latter are in fully open condition. Once a predetermined number of the cartons are arranged in nested relation so as to form a stack, the stack is then subjected to compressive force of predetermined magnitude so as to compact the stack to a convenient size. Frequently the stack is then overwrapped so as to preserve and protect the cartons.

When the cartons are to be used, the overwrap is removed from the stack and then the individual cartons are removed from the stack for lling. Because of the configuration of the stacked cartons, the inherently roughened surface of molded pulp, and the compressive force utilized to compact the stack, denesting of the cartons from the stack, frequently becomes a dilcult and awkward manipulation.

In commercial egg packing plants, it is customary for the denesting operation to be performed'by automatic equipment. Various forms of such equipment have heretofore been produced; however, because of certain design characteristics they are beset with one or more of the following shortcomings: (a) the equipment is of costly, complex and bulky construction, (b) the equipment iS subjected to frequent breakdown or jamming, (c) the equipment often tears or mutilates the cartons, (d) the operation of the equipment is slow, (e) the equipment is not readily capable of accommodating cartons varying in size and shape over a wide range.

SUMMARY OF THE INVENTION Thus, it is 1an object of this invention to provide a denester which avoids the shortcomings associated with prior equipment of this general type.

It is a further object of this invention to provide a denester which may be readily integrated with conveyor systems and the like presently found in commercial egg packing plants.

It is a further object of this invention to provide a denester the cycle of operation of which may be inter- 3,477,592 Patented Nov. 11, 1969 rupted at anytime without adversely etecting the apparatus or vthe cartons being handled thereby.

It is a still further object of this invention rto provide a denester which is capable of handling a wide variety of nested articles with but a minimum of change-over time involved to accommodate the various articles.

It is a still further' object of this invention to provide a denester which has high capacity with but a minimum of power requirements.

Further and additional objects will appear from `the description, accompanying drawings and appended claims.

In accordance with one embodiment of this invention a denester is provided which includes an indexing means mounted for movement between an extended position wherein it engages the bottom of a stack of nested articles, and a retracted position wherein it is later-ally spaced from the bottom of the stack. The denester also includes an adjustably mounted stack-holding means disposed above the indexing means. The stack-holding means, when in one position of adjustment resiliently engages the stack of nested articles and retains same in a predetermined position when the indexing means assumes the retracted position. When the stackholding means assumes a second position of adjustment, it is spaced from the stack whereby the latter, due to its own weight, moves downwardly a predetermined distance. An adjustable stripper element is also provided which, when in a rst position of adjustment, has a portion thereof disposed adjacent the underside of the stack-holding means and projecting between the peripheries of the two lowermost articles of the stack when the latter is being resiliently engaged by the stackholding means. The stripper element, when actuated from the rst position of adjustment to a second position of adjustment, causes the projecting portion thereof to contact the periphery of the lowermost article in 'the stack and move said article downwardly past the indexing member while the latter is in the retracted position, and effect denesting of the said article from the remaining articles of the stack. The denester is also provided with control means for etecting adjustment of said indexing means, said stack-holding means, and said stripper means in a predetermined time sequence.

For a more complete understanding of the invention, reference should be made 'to the drawings wherein:

FIG. 1 is a fragmentary perspective view of one form of the improved denester shown in combination with a horizontally disposed conveyor;

FIG. 2 isa fragmentary enlarged front elevational view of the denester of FIG. 1 and showing the indexing means in an extended position and the stack-holding means in a release position;

FIG. 3 is similar to FIG. 2` but showing the indexing means and stack-holding means in changed positions and the stripper element in a denesting position;

FIG. 4 is a fragmentary left end elevational view of the denester shown in FIG. 2; and

FIG. 5 is a schematic diagram of a control system for the illustrated denester.

Referring now to the drawings and more particularly to FIG. 1, one form of the improved denester or denesting appartus 10 is shown. The denester as illustrated is adapted for use in successively removing or denesting a molded pulp egg carton C lfrom the lower end of a stack or bundle S of similar egg cartons arranged in nested relation. The denested carton, due to the force of gravity, is caused to be deposited upon a horizontally disposed conveyor 11 positioned beneath the denester.

The illustrated egg cartons C are of a type commonly referred to as a 2 X `6 style. Such cartons (see FIG. 4) normally comprise a cellular tray section C1 and a cover section C2 which is integral with and hingedly connected to the back wall of the tray section. The cartons in ques- 3 tion may be of the style disclosed in Lambert U.S. Patent 2,978,162. As will be hereinafter discussed the denester 1G is not limited for use with this particular type article but may be readily adjusted to accommodate other types of egg cartons, as well as trays for fragile articles, filler flats, or other nestable articles of comparable design.

The cartons C are nested when in a fully open position so that the respective tray and cover sections will nest within one another. Because of the cellular configuration of the tray sections, sticking therebetween oftentimes becomes acute.

The stack S is held in a stabilized upright position by a suitable guide member 12, see FIGS. l and 2, which is mounted on a frame member 13. The height and size of the frame member will depend upon the height and size of the conveyor 11 utilized to move the denested carton to a predetermined egg loading station, not shown. The guide member 12 may be an optional accessory and is open at the top for loading one or more bundles of cartons therein. The bundle is positioned within the guide member so that the underside of the carton tray section C1 faces downwardly.

The lower end of the guide member 12 is also open and is disposed adjacent to an assembly 14 which is shown more clearly in FIGS. 2-4. The assembly 14, as illustrated, comprises basically a stack-holding unit 15, a stripper element 16, and an indexing member 17. There are, in fact, two assemblies 14 which are of like construction and are disposed on opposite sides of the stack S. It should be noted, however, that by reason of having two independent assemblies 14 which operate in opposition to one another in a manner to be hereinafter described, each assembly may be adjusted separately so that the assemblies can be self-aligning with respect to the configuration of the stack accommodated therebetween. For convenience only one of the assemblies is illustrated and will be described in detail hereinafter.

The stack-holding unit 15 includes a clamping plate or jaw 18 which is pivotally connected at its upper end 18a to a xed extension 13a of the frame 13. The inner face, or the `face of the plate which is adjacent the side of the stack S is covered with a resilient soft shoe or pad 2G which engages certain cartons in the stack S at predetermined intervals during the cycle of operation of the denester which will be described more fully hereinafter. Slidably connected to the backside of plate 18 is the stripper element 16. To permit a sliding motion of element 16 with respect to plate 18, an elongated vertically disposed slot 21 is formed in the element. Disposed within the slot 21 are a pair of vertically spaced studs 22 which are threaded into the backside of plate 18. An Unthreaded shank portion 22a of each stud is disposed within the slot 21. The outer or exposed end of each shank portion terminates in an enlarged head 22b which because of its dimension is impassable through the slot.

In FIGS. 2-4 it will be noted that there is formed on the upper end of the element 16 an outwardly extending nub 23. To the outer distal end of nub 23 are pivotally connected at 24 the upper ends of a pair of link members 25, see FIG. 4. The lower end of each member 25 is pivotally connected at 26 to one arm 27a of a corresponding one of a pair of bell-crank levers 27. Each lever 27 in turn is pivotally connected at 28 to a bracket 29 affixed to the frame extension 13a. The second arm 27b of each lever 27 depends from pivotal connection 28.

Upon levers 27 being pivoted as a unit about connection 28 in a counterclockwise direction so as to assume the position shown in FIG. 3, the stripper element 16 is caused to move downwardly relative to the stack-holding unit 15 and effect denesting of the lowermost carton in the stack. The denesting operation of stripper element 16 will be discussed more fully hereinafter.

The bell-crank levers 27 are biased in a clockwise direction to the positions shown in FIG. 2 by a coil spring 30, which has one end thereof atixed to frame extension 13a and the other end aixed to a pin 31 which interconnects the lever arms 27a of the pair of bell-crank levers 27.

Spaced below nub 23 and aflxed to stripper element 16 is a U-shaped member 32, see FIGS. 2 and 3. The leg portions of member 32 have the ends thereof connected to element 16 and the bail or central portion 32a of the member is spaced from the adjacent portion of the element in which the elongated slot 21 is formed. Portion 32a functions as a bumper piece against which one end 33a of piston rod 33 engages when said piston is moving to its extended position as shown in FIG. 3. The piston comprises a part of an air-actuated piston-cylinder unit 34. The cylinder 35 of the unit is aflixed to the frame extension 13a, see FIGS. 2 and 3. The means of controlling the actuation of piston rod 33 will be described in detail hereinafter.

Disposed between the exposed end 33a of piston rod 33 and the cylinder 35 or frame extension 13ay and in encircling relation with a portion of the rod is a coil spring 36. The function of spring 36 is to cause the exposed end of the rod to engage the bumper piece 32a of member 32 and actuate the plate 18 into stack-holding position, once air pressure in cylinder 35 has been released.

A second piston-cylinder unit 37 is provided which is positioned beneath unit 34, see FIGS. 2 and 3. The piston rod 38 of unit 37 has the outer end thereof aixed to an upright ange 40, the latter comprising a portion of the indexing member 17. In addition to flange 40, the indexing member 17 comprises an elongated base 41 which is slidably supported by an unpstanding leg 13b carried by the frame 13.

When rod 38 assumes a fully extended position with respect to cylinder 42 of unit 37, see FIG. 2, the base 41 is disposed within the path of movement of the stack S and is adapted to be engaged by the lowermost carton in the stack. When the stack is engaging base 41, the lowermost carton in the stack is properly indexed with respect to a stripper blade 43, the latter forming a part of the element 16, see FIG. 2.

When piston 38 is in its fully retracted position with respect to cylinder 42, as seen in full lines in FIG. 3, the base 41 is spaced laterally from the lowermost carton of the stack. While the base 41 remains in this retracted position, the lowermost carton in the stack is free to be moved downwardly therepast by the stripper element.

It will be noted in FIGS. 2, 3 and 5 that unit 37 is actuated in both directions by air pressure whereas unit 34 is actuated in only the direction towards retraction by air pressure. It is to be understood of course that the invention is not limited to this precise arrangement. With the illustrated arrangement, however, an advantage to be gained thereby is that any failure of air pressure will result in the stack S being automatically gripped between the stack-holding units 1S disposed on oposite sides of the stack.

It will be observed in FIG. 2 that the blade 43 which is positioned adjacent the lower side of element 16 is also disposed adjacent the underside of the plate 18 and shoe 20. In such position the blade 43 is spaced a predetermined distance X above extended base 41 of indexing member 17. This spacing or distance X may vary and will depend upon the height of the tray section of the lowermost carton in the stack. Where, for example, the spacing X is to be reduced in order to accommodate an article of lesser height, such as a iller flat, this may readily be accomplished by mounting adapted blocks, not shown, on the upper, or contacting, surface of base 41. If, on the other hand, the spacing X is to be increased from that shown in FIGS. 2 and 3, such may be readily accomplished by removing the suporting leg 13b and substituting a shorter one therefor and loosening the connection between the end of piston 38 and ange 40. Because of an elongated slot 40a, see FIG. 4, formed in ange 40, the base 41 and ange 40 may be lowered as a unit until the base engages the substituted supporting leg, whereupon the connection between the end of the piston and the ange can once again be tightened.

Once the proper spacing X has been determined, the inwardly projecting edge 43a of the blade 43 is aligned between the adjacent peripheral portions of the two lowermost cartons in the stack. Upon the clamp plate 18, which carries stripper element 16, being moved to a stack-holding position such as shown in FIG. 3, the projecting edge 43a of the blade 43, shown in dotted lines in FIG. 3, moves toward the stack and becomes disposed intermediate the peripheral portions of the two 1owermost cartons of the stack. Subsequent to the blade edge 43a being so positioned, the stripper element 16 is then actuated downwardly independently of clamp plate 18 causing the lowermost carton to be denested from the bottom of the stack.

The downward independent movement of the stripper element 16 is effected upon movement of the indexing member 17 from its extended position to its retracted position. For approximately the first half of the retracting movement of member 17, the stripper element 16 is unetected. However, upon the upper edge of flange 40 engaging the depending arms 27b of the pair of bell-crank levers 27, the latter are caused to pivot in a counterclockwise direction about point 28 as member 17 coninues its retracting. The counterclockwise motion of the bell-crank levers 27 is transformed into downward linear motion of stripper element 16 through link members 25 pivotally connected to the other arms 27a of levers 27.

As aforenoted, bell-crank levers 27 are biased by coil spring 30 in a clockwise direction and as a result, stripper element 16 will automatically assume its up position, as seen in FIG. 2, when the indexing member 17 resumes its extended position.

A control system for actuating the stack-holding units and the index members in a predetermined timed sequence is shown schematically in FIG. 5. Included within the system is an air supply 44, a plurality of cam-operated valve switches 45, 46 and 47, a cam 48, suitable piping 50 interconnecting the air supply 44 to switches 45, 46 and `47 and further piping 51, 52 and 53 which effects the following respective interconnections: switch 45 to ports 42a of piston-cylinder units 37; switch 46 to ports 42b of units 37; and switch 47 to ports 35a of pistoncylinder units 34.

An input port 45a of switch 45 is normally open and thus, air pressure is normally exerted on the piston 38 of each unit 37 causing said piston to assume an extended position, which, in turn, causes base 41 of the indexing member to assume the stack-supporting position shown in FIG. 2. Switch 45 is provided with an elongated follower arm 45h, which when moved in a clockwise direction from that shown in FIG. 5, causes the input port 45a to be closed. How such clockwise motion is imparted to arm 45b will be described more fully hereinafter.

An input port 46a of switch 46 is normally closed and thus, ports 42b of units 42 are not under pressure and cooperate with ports 42a to permit the pistons 38 to readily assume their normal extended positions. Switch 46 also is provided with an elongated follower arm 46b, the movement of which controls the opening and closing of port 46a. Arm 46b is biased so that a roller 46c mounted on the distal end of arm 46b is in constant contact with the periphery of cam 48. It should also be noted that arm 45h of switch 45 is also biased so that a roller 45C carried on the end of the arm is in constant contact with the periphery of roller 46c. Thus, by reason of this arrangement, closing of input port 45a of switch 45 occurs simultaneously with the opening of input port 46a of switch 46.

In switch 47, an input port 47a is provided which is normally closed so as to enable the clamp plates 18 and associated shoes 20 of the units 15 to normally assume a stack-holding position by reason of the pistons 33 of units 34 being biased by springs 36 to be extended and engaging the bumper pieces 32a of members 32, the latter being carried by clamp plates 18. As in the case of switches 45 and 46, switch 47 is `also provided with an elongated follower arm 47b, which, when actuated in a counterclockwise direction from the position shown in FIG. 5, causes input port 47a to be opened whereupon air pressure is introduced into input ports 35a of cylinders 35 and effect retraction of pistons 33. Once pistons 33 are retracted, coil springs 30 come into play causing the clamp plates 18 to automatically move to a release position, see FIG. 2.

The peripheral configuration of cam 48, as seen in FIG. 5, includes a pair of nodes `48a which are arranged in diametric relation. Each node spans a sector of approximately 30-40 and thus effects the desired sequence of operation of switches 45-47 when the latter are disposed in the relative positions as shown. Obviously the peripheral shape of the cam 48 and the relative disposition of the switches may be varied without departing from the scope of the invention. In the illustrated embodiment of the cam 48, the peripheral shape thereof is substantially symmetrical and thus, interruption of the operation of the denester may occur at anytime without adversely affecting the sequence of operation of the denester when operation thereof is resumed.

As seen in FIG. 4, the clamp plates 18 and associated shoes 20, the stripper elements 16 and the indexing members 17 are shown of such a size as to contact and operate on only the tray sections C of the nested cartons C of the stack S. The reason for this particular arrangement is that with this particular article, the jamming or stacking problem is only of concern in the tray sections because of the plurality of posts and pockets formed therein. In instances, however, where the stacking problems involve both the tray and cover sections or the article as a whole, such as in the case of a ller llat, the shape and size of the denester components may be readily varied to meet the peculiarities of the articles to be denested without departing from the scope of the disclosed invention.

The guide member 12, as seen more clearly in FIG. l, includes a channel-shaped element 12a, and a pair of ilange pieces 12b which are xedly secured to and are disposed in front of the flange portions 12C of element 12a. The spacing between the element flange portions 12C and the ange pieces 12b as well, corresponds closely to the lengths of the nested cartons. On the other hand, the spacing between the base portion of the channel-shaped element and ilange pieces 12b corresponds substantially to the distance of each of the nested cartons from the front wall of the tray section thereof to the iront wall of the cover section, when the cover section is in its fully opened position as seen in dotted lines in FIG. 4. Thus by reason of these aforenoted spaced dimensions of the guide member 12, the stack S may readily slide downwardly within the guide member as the lowermost carton is denested from the bottom end of the stack. Where the articles to be denested differ in shape and size from those illustrated in the drawings, the guide member configuration may be varied accordingly.

In certain instances it might be desirable for the stack S of cartons to be inverted from that shown-that is to say, the open sides of both the tray and cover sections face downwardly. When such is the case, however, the space X between base 41 and blade 43 will be reduced substantially from that shown in a manner as previously suggested. Furthermore, base 41 should be retracted to a greater extent than that -shown in FIG. 3 or the base 41 should be provided with a slot of suitable dimensions through which the blade can pass, so that in either case there will be no interference between the blade 43 and the base 41 when the blade is moved downwardly relative to the lower side of the stack-holding unit 15 to effect denesting of the lowermost carton.

Thus, it will be seen that an improved denester has been provided which is simple in construction, eifective in operation, and may be readily incorporated and used in combination with existing conveyor and loading equipment Furthermore the improved denester is adapted to readily accommodate articles varying over a wide range in both size and shape.

I claim:

1. An apparatus for successively denesting individual articles from the bottom of a stack of articles arranged in nested relation, said apparatus comprising indexing means mounted for movement between an extended position wherein a portion thereof subtends and engages the bottom of the'stack, and a retracted position, wherein said portion is laterally spaced from the stack bottom; lirst power means for effecting movement of said indexing means between said extended and retracted positions; stack-holding means mounted above said indexing means for movement between a first position wherein said holding means resiliently engages opposite sides of the stack without engaging the lowermost article thereof and retains .the stack in a predetermined elevated position with respect to the indexing means portion, and a second position wherein said holding means is out of contact with the stack and the latter is free to move downwardly a predetermined distance due to its own weight; second power means for effecting movement of said stack-holding means; adjustable stripper elements carried by said stackholding means, each element having a projecting portion disposed adjacent the underside of said holding means and positioned between the peripheral edges of the two lowermost articles in the stack when the latter is being retained by said holding means in said predetermined elevated position, said stripper elements, while said holding means is in said first position, being movable independently thereof to an extended position relative to the underside of said holding means whereby the lowermost article of the stack is moved thereby to a denested position with respect to the remainder of the stack; means engaging said st1ipper elements and operable by said rst power means for effecting independent movement of said stripper elements to said extended position only when said first power means is moving said indexing means to said retracted positions; and control means operatively engaging said rst and second power means for effecting independent actuation of same in a predetermined time sequence.

2. The apparatus of claim 1 wherein said first and second power means are pneumatically actuated piston-cylinder assemblies.

3. The apparatus of claim 2 wherein said control means includes a movable cam, and a plurality of switches adjustably mounted adjacent the periphery of said cam and actuated by the latter upon movement thereof, said switches being operatively connected to said piston-cylinder assemblies.

4. The apparatus of claim 1 including guide means for stabilizing the stack of nestedV articles when released by said stack-holdingy means.

5. The apparatus of claim 1 wherein said stack-holding means is biased to assume a stack-holding position with respect to the stack of nested articles and said stripper element projecting portion is biased to assume a position adjacent the underside of said stack-holding means.

References Cited UNITED STATES PATENTS 2,974,828 3/1961 Matteson 221-297 X 3,297,201 l/l967 Burt 221-221 3,379,346 4/1968 Frederick 221-221 X 3,403,816 10/ 1968 Verrinder.

GERALD M. FORLENZA, Primary Examiner GEORGE F. ABRAHAM, Assistant Examiner U.S. Cl.v X.R.

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