US 3907161 A
In a denesting apparatus there is provided a magazine in which thin-walled packaging trays - each having at least one cup-shaped depression - are held as a nested stack and a suction gripper which moves into engagement with the outermost tray for removing the same from the stack through an opening in the magazine. The suction gripper includes a gripper head which has at least one cavity conforming to the outer configuration of the tray. The side walls of the cavity are inwardly concave, so that when vacuum is applied to the cavity, the side walls of each depression of the outermost tray nesting in the gripper head bulge outwardly, whereby they are separated from the side walls of each depression of the next-to-the-outermost tray in the stack.
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Description (OCR text may contain errors)
1451 Sept. 23, 1975 1 1 APPARATUS FOR DENESTING STACKED PACKAGING TRAYS  Inventor: Eberhard Martin, Wehrda near Marburg, Germany Dr. Ing. Kaupert KG, Erndtebruck, Westphalia, Germany  Filed: Nov. 27, 1973  Appl. No.2 419,295
 Foreign Application Priority Data 3,485,393 12/1969 Wilder 214/8.5 D X 3,511,395 5/1970 Brown, Jr. 3,606,960 9/1971 Butterworth 221/211 Primary ExaminerRobert B. Reeves Assistant ExaminerCharles A. Marmor Attorney, Agent, or Firm-Spencer & Kaye  ABSTRACT In a denesting apparatus there is provided a magazine in which thin-walled packaging trays each having at least one cup-shaped depression are held as a nested stack and a suction gripper which moves into engagement with the outermost tray for removing the same from the stack through an opening in the magazine. The suction gripper includes a gripper head which has at least one cavity conforming to the outer configuration of the tray. The side walls of the cavity are inwardly concave, so that when vacuum is applied to the cavity, the side walls of each depression of the outermost tray nesting in the gripper head bulge outwardly, whereby they are separated from the side walls of each depression of the next-to-the-outermost tray in the stack.
6 Claims, 3 Drawing Figures VACUUM SOURCE US Patent Sept. 23,1975 Sheet 2 of2 3,907,161
APPARATUS FOR DENESTING STACKED PACKAGING TRAYS BACKGROUND OF THE INVENTION z This invention relates to an apparatus for denesting thinwalled packaging trays which are stacked in a magazine and which have cup-shaped depressions for receiving the articles to be packaged. The apparatus is of the type that includes projections to engage the edge portions of the outermost tray in the magazine and a controlled suction-type gripper oriented towards the magazine to grasp the outermost tray and draw the edge portions off the projections. Subsequent to the removal of the outermost tray from the stack the gripper forwards the tray to a packaging conveyor or a packaging machine.
In US. Pat. No. 3,401,831 there is disclosed a denester which, in addition to the suction grippers, includes nozzles which blow pressurized air between the outermost tray and the tray immediately succeeding it, in order to facilitate their separation. I
In Swiss Pat. No. 394,930 there is disclosed a denester in which two grippers having suction heads engage the inner face of the lateral walls ofa bowl shaped container. Subsequent to the suction step, the grippers are withdrawn in such a manner that the lateral walls of the outermost bowl separates from those of the successive bowl in the stack, and simultaneously, the peripheral bowl edge is pulled away from the magazine projections that retain the stack. Thereafter the separated bowl, by means of a mechanical lifting device, may be removed from the magazine and deposited on a conveyor belt.
With the aforeoutlined known apparatus, however, only packaging members of relatively simple structure may be denested rapidly and in an operationally safe manner.
SUMMARY OF THE INVENTION It is an object of the invention to provide a denesting apparatus of the aforedescribed type with which even packaging trays having a great number of depressions or inserts for tubular bag packages in which the outer edge is pulled down at all sides, can be denested in a satisfactory manner.
This object and others to become apparent as the specification progresses, is accomplished by the invention, according to which, briefly stated, the suction gripper includes a gripper head which conforms like a patrix to the contour of the outermost packaging tray oriented theretoward. Those faces of the gripper head that are oriented towards the lateral walls of the depressions are inwardly concave. 1
The above-outlined structure according to the invention ensures that when vacuum is applied to the gripper head in its operative position (that is, when the gripper head ncstingly accommodates the outermost tray in the magazine), the side walls of the depressions of the outermost tray will bulge to conform to the concave surfaces.
In this manner, the lateral walls of the outermost tray are separated from those of the successive tray and, at the same time, the edge zones of the outermost tray are pulled out of the retaining projections of the magazine, so that the tray which is thus separated from the magazine and adhering to the suction gripper, may be advanccd thereb to a further handling station by virtue of the gripper control. Because of the particular configuration of the suction gripper, additional pneumatic or mechanical devices with which it has been heretofore attempted to facilitate the separation of the outermost tray from the stack, are no longer necessary.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional fragmentary view of a magazine loaded with a stack of packaging trays and a preferred embodiment of a suction gripper disposed therebelow ,in an idle position.
FIG. 2 is a view similar to FIG. 1, showing the suction gripper in its operative, tray-engaging position.
FIG. 3 is a schematic side elevational view of the entire denesting apparatus, including an inverting mechanism and a conveyor.
DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIGS. 1 and 2, in a magazine housing 3 there is supported a stack 1 which is formed of nested, thin-walled packaging trays made of thin synthetic sheets. The trays have conical cup-shaped depressions 10 each defined by a base and side walls 12 for receiving the articles tobe packaged and have an outer peripheral wall surface 2 which extends downwardly approximately to the height level of the bases 10:: of the depressions 10. At the outlet opening of the magazine, there are provided displaceable abutments 4 which retain the stack 1 in the magazine by engaging the free edge of the peripheral wall 2 of the outermost packaging tray. The outermost tray can be taken out from the magazine housing 3 ina direction of removal indicated by the arrow A and in amanner described below.
The suction gripper head 5 hasa configuration which generally corresponds to that of the underside of the packaging trays except that the cavities 5a provided in the head 5 are slightly larger than the outer dimension of a depression 10 in the packaging tray. Further, the side walls 6 of each cavity 5a bounded by internal webs 11 and an outer peripheral web 13 have a concave shape when viewed from the. inside of the cavity (that is, the walls 6 are inwardly concave. The external face 7 of the peripheral web 13 is depressed to a slightly greater extent than the distance by which the abutments 4, arranged approximately at the middle of the magazine housing 3, project into the magazine opening. Stated differently, the outer surface 7 of the web 13 is outwardly concave about a line that is substantially par allel to the direction of tray removal (arrow A). A vacuum source (only symbolically shown) communicates with the inside of the cavities 5a by means of a conduit 8 attached to the gripper head 5; Pneumatic communication between all the cavities 5a is ensured by ports 9 passing through the webs 11. Channels 17 extending in the base of the cavities 5a ensure that the vacuum source communicates with each side wall 6. Ports 9 also pass through the peripheral webs 13 for the purpose of establishing communication between the vacuum source and the external o utwardly concave surfaces 7 of the peripheral webs l3.
The apparatus according to the invention operates as follows:
By means of a mechanism conventional by itself, the suction gripper head 5 is moved from its position shown in FIG. 1 towards the magazine 3 to assume an operative position as illustrated in FIG. 2. In this position the webs 11 and 13 project into spaces 14 and 15 adjacent the depressions 10 and thus each cavity a receives the walls a and 12 defining a depression 10 of the outermost packaging tray in the stack 1. Stated differently, the gripper head 5 nestingly accommodates the outermost tray. The vacuum applied through the conduit 8 to the spaces between the walls 6 of each cavity 50 and the outer faces of the side walls 12, causes the latter to resiliently bulge outwardly and to thus conform to the concave wall surfaces 6. As it is well observable in FIG. 2, the side walls of the outermost packaging tray are now separated from those of the next-to-the-outermost tray. Further, the vacuum also causes the generally outwardly extending outer walls 2 of the outermost packaging tray to be drawn inwardly into the outwardly concave face 7 of the webs 13, whereby the free outer edge of the walls 2 is disengaged from the retaining member 4. In order to ensure that the vacuum has a rapid effect on the walls 2, the marginal face of the gripper base plate 16 is so designed that in the operative position it lies tight against an edge face surrounding the magazine opening and forming part of the magazine housing 3. For this purpose it is expedient to provide the base plate 16, at least along the afore-noted marginal face, with a rubber-like layer having sealing properties.
The outermost packaging tray which thus over a major portion of its outer surface is held by the suction effect of the gripper, is pulled away from the remainderof the tray stack in the direction of removal A by moving the gripper head 5, together with the outermost tray adhering thereto, parallel to itself away from the magazine 3 by the guide bar 18. Then the removed tray is brought by an additional pivotal motion of the gripper head 5 into a horizontal position, as illustrated in FIG. 3. By switching the conduit 8 to ambient atmosphere or introducing thereinto pressurized air, the removed packaging tray is separated from the gripper head 5, whereupon it drops onto an eccentrically located inverter bar 19 held in the upper third of a funnel-shaped inverter 20. Within the latter, the tray tips and falls edgewise on a conveyor 21 through an aperture which is provided in the lower portion of the funnel member and which is oriented towards the travelling direction of the conveyor 21. The bar 19 extends trans versely to the travelling direction of the conveyor 21. The conveyor 21, by virtue of its frictional engagement with the edge of the tray, turns the latter face up, so that the open side of the depressions in the tray are oriented upwardly.
It is to be understood that the invention is not limited to the above-described embodiment. Suction gripper heads of various designs may be used to fit the shape of'the particular packaging trays stacked in the magazine. For this purpose it is advantageous to exchangeably mount the suction gripper head on the base plate It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.
1. In an apparatus for denesting thin-walled packaging trays each having at least one cup-shaped depres sion defined by side and base walls of the tray and a pcripheral wall extending from the height of the top of the depressions down to approximately the height of the base walls, the apparatus being of the type that has a magazine accommodating the trays in a nested stack, the magazine has an outlet opening through which the outermost tray of the stack is adapted to be removed in a direction of removal, and. a retaining means projecting into the outlet opening of the magazine for supporting the nested stack by engaging the outermost tray, the apparatus further includes a suction gripper orientable towards the magazine opening and movable into an operative position to grasp the outermost tray by means of vacuum, the suction gripper having a gripper head including means defining at least one cavity for nestingly accommodating the walls of the depression of the outermost tray when said suction gripper is brought into the operative position, the improvement comprising:
a. abutments supported by the magazine and arranged approximately centrally thereof, said abutments constituting said retaining means;
b. a peripheral web forming part of said gripper head and having an outwardly concave outer surface disposed to adjoin the peripheral wall of the outermost tray when said suction gripper is brought into its operative position, said outer surface being concave about a line substantially parallel to said direction of removal; and
c. means for generating a vacuum between said outer surface of said peripheral web and the adjoining peripheral wall of the outermost tray when said suction gripper is in its operative position for drawing the peripheral wall of the outermost tray into said concave outer surface of said peripheral web to disengage edge portions of the peripheral wall of the outermost tray from said abutments.
2. An apparatus as defined in claim 1, wherein said cavity has inwardly concave lateral surfaces; the improvement further comprising means for generating a vacuum between said lateral surfaces and the side walls of the depression in the outermost tray for drawing the side walls into said concave lateral surfaces of said cavity to separate the side walls of the depression of the outermost tray from those of the next-to-the-outermost tray in the nested tray stack.
3. An apparatus as defined in claim 2, wherein said cavity has a bottom and wherein said means for generating a vacuum between said outer surface of said peripheral web and the adjoining peripheral wall of the outermost tray and said means for generating a vacuum between said lateral surfaces and the side walls of the depression in the outermost tray together comprise a vacuum source, a conduit connecting said gripper head to said vacuum source; means defining a channel in the bottom of said cavity, said channel communicating with said conduit; and means defining a port passing through said peripheral web for maintaining communication between said outer surface of said peripheral web and said vacuum source through said channel and said conduit.
4. An apparatus as defined in claim 3, wherein said gripper head includes webs defining a plurality of cavi ties similar to said at least one cavity, port means passing through said webs to maintain communication between saidcavity and said vacuum source.
5. An apparatus as defined in claim 1, wherein said magazine has an edge face surrounding the magazine opening, said gripper head includes an edge face surrubber-like surface for providing a sealing engagement with the edge face of said magazine in said operative position of said suction gripper.