GB2239450A - Apparatus for and method of denesting containers - Google Patents

Abstract

An apparatus for denesting a stack of containers 132, the apparatus comprising a first container engaging means 36, 36, a second container engaging means 54, 54, each of these means being a pair of opposed plates which is spaced from the first container engaging means in a direction which is, in use, substantially aligned with the stack, and drive means in the form of a cam arrangement 70 for selectively and alternately moving the first and second container engaging means into and out of engagement with the stack whereby the first and second engaging means alternately hold an end container of the stack thereby to release a previous end container from the stack. An air blast supplied via 114 may assist denesting, further air-blasts from 112 and nozzles 108 conveying the denested containers away as shown. <IMAGE>

Description

"APPARATUS FOR AND METHOD OF DENESTING CONTAINERS".

The present invention relates to an apparatus for denesting containers and to a method of denesting containers.

In the food processing industry it is well known to package food in plastics containers which prior to the packaging step can be nested together into a stack thereof for ease of transportation and storage. Currently, manual denesting of the stacks of containers is employed and this is time-consuming and labour intensive. There is a need for a reliable and inexpensive automatic denesting apparatus for denesting the stacks of containers prior to the packaging of foodstuffs thereinto.

The present invention aims to fulfill that need.

Accordingly the present invention provides an apparatus for denesting a stack of containers, the apparatus comprising a first container engaging means, a second container engaging means which is spaced from the first container engaging means in a direction which is, in use, substantially aligned with the stack, and drive means for selectively and alternately moving the first and second container engaging means into and out of engagement with the stack whereby the first and second engaging means alternately hold an end container of the stack thereby to release a previous end container -from the stack.

The present invention also provides a method of denesting a stack of containers, the method comprising the steps of: (a) providing first and second container engaging means, the second engaging means being spaced from the first engaging means in a direction substantially aligned with the stack; and (b) selectively and alternately moving the first and second container engaging means into and out of engagement with the stack whereby the first and second engaging means alternately hold an end container of the stack thereby to release a previous end container from the stack.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is an elevational sectional view of two nested containers for use in an apparatus for denesting containers in accordance with the present invention; Figure 2 is a plan view, partly in phantom, of an apparatus for denesting containers in accordance with the present invention; Figure 3 is an elevational sectional view on line A-A of the apparatus of Figure 2; Figure 4 is an elevational sectional view on line B-B of the apparatus of Figure 2; Figures 5 and 6 are schematic representations of the top plates and pneumatic piston assembly of the apparatus of Figure 2 in two alternative configurations; Figures 7 and 8 are schematic representations of the bottom plates and pneumatic piston assembly -of Figure 2 in two alternative configurations;; Figure 9 is a sectional elevational view, similar to Figure 3, illustrating the denesting operation; and Figure 10 is an enlarged plan view of a top plate of the apparatus of Figure 2.

Referring to Figure 1, there is shown two nested plastics containers 2 each of which comprises a pot having an upper peripheral annular rim 6 for receiving a seaming lid (not shown) after foodstuffs have been deposited into the container 2. One container 2 is partially received within the other container 2 and in practice there is provided a stack of nested containers 2.Each pot includes a. base 8; a lower pot portion 10 which is radially outwardly flared whereby the radius of the top of the lower pot portion 10 is greater than the radius of the bottom of the lower pot portion 10 in the region of the base 8; an intermediate pot portion 12 of substantially constant radius which is greater than that of the lower pot portion 10 thereby forming an outwardly-directed shoulder 14 between the intermediate pot portion 12 and the lower pot portion 10; and an upper pot portion 16 between the seaming rim 6 and the intermediate pbt portion 12, which upper pot portion 16 has a substantially constant radius which is intermediate the radii of the sealing rim 6 and the intermediate pot portion 12 thereby forming an inner shoulder 18 beneath the sealing rim 6.When the containers 2 are nested together, the outer shoulder 14 of an upper container 2 rests on the inner shoulder 18 of the adjacent lower container 2 thereby spacing the base 8 of the upper container 2 from the base of the lower container 2 by a distance substantially equal to the height of the intermediate pot portion 12.

Referring to Figures 2 to 8 of the drawings, there is shown an apparatus 20 for denesting a stack of nested containers such as the containers 2 shown in Figure 1. The apparatus 20 comprises a magazine 22 for receiving a nested stack of containers (not shown) which may be upright, each container 2 preferably being in an upside down configuration with its rim lowermost. However, the apparatus may be set-up to denest a stack in a different orientation. The magazine 22 comprises an annular array of equally-spaced upright rods 24 which are held by a surrounding support ring 26. Although not shown for clarity, the rods 24 extend upwardly to a substantial distance above the remainder of the apparatus so as to enable an elongate stack of a large number of containers 2 to be held in the magazine 22.This is preferably achieved by providing a detachable part of the magazine 22 which is detachably mounted above the rods 24 shown in the Figures.

The support ring 26 is mounted on upright supports 28 which extend upwardly away from a mounting plate 30 having a circular hole 32 therethrough and which is mounted above a denester assembly 34 of the apparatus. The upright rods 24 of the magazine 22 extend downwardly into the denester assembly 34.

The denester assembly 34 comprises a series of plates which are disposed in a vertical array. At the bottom of the denester assembly 34 is a pair of opposed bottom plates 36, each of which is substantially rectangular and each of which includes a substantially semi-circular orifice 38 therein which is disposed along a longitudinal edge 40 of the respective bottom plate 36, the two orifices 38 being configured so that when the two bottom plates 36 are adjacent to each other along the adjacent longitudinal edges 40 the two orifices 38 together define a substantially circular orifice 42. The bottom plates 36 are horizontally and slidably supported by a pair of opposed plate support members 44 which are disposed at opposed ends of the bottom plates 36. Each bottom plate 36 also includes cut-outs 46 extending away from the respective orifice 38 through each of which cut-outs 46 extends a respective upright rod 24 of the magazine 22. In a manner which will be described hereinbelow, the two bottom plates 36 can be simultaneously moved horizontally towards and away from each other between an engaged position, at which the bottom plates 36 engage each other along the engaged longitudinal edge 40 which extend between the plate support members 44, and a separated position at which the bottom plates 36 are separated from each other.Each bottom plate 36 is provided along the longitudinal edge 40 with a pair of semi-circular holes 48 on opposing sides of the orifice 38, the arrangement being such that when the bottom plates 36 are in the engaged position the holes 48 of the bottom plates 36 define two opposed circular holes 50 along the adjacent longitudinal edges 40 of the bottom plates 36. The bottom plates 36 are each also provided with a pair of cam slots 52 on opposing sides of the orifice 38. The cam slots 52 receive cylindrical upper cam-members, which will be described hereinbelow, and which act to move the bottom plates 36 between the engaged and separated positions.

A pair of top plates 54 is slidably and horizontally supported above the bottom plates 36 by the plate support members 44. The top plates 54 have a similar construction to the bottom plates 36. Thus each top plate 54 is provided along a longitudinal edge 56 with a substantially semi-circular orifice 58, with the orifices 58 being configured so that the orifices 58 define a common substantially circular orifice 60 when the top plates 54 are engaged in an engaged position along the adjacent longitudinal edges 56 which extend between the plate support members 44.

The orifices 58 are also provided with extending cut-outs 62 for receiving the upright rods 24 of the magazine 22 which extend therethrough. The top plates 54 are each also provided with a pair of opposed semi-circular orifices 64 along the longitudinal edges 56 which, when the top plates 54 are in the engaged position, define a pair of opposed circular orifices 66. Finally, the top plates 54 are each also provided with a pair of cam slots 68 which are each adapted to receive a respective cylindrical lower cam member, which lower cam members are described hereinbelow.

A pair of cam support members 70 is located between the pair of top plates 54 and the pair of bottom plates 36. Each cam support member 70 comprises a plate which has mounted on the upper surface thereof a pair of cylindrical upper cam members 72 each of which is slidably disposed in a respective cam slot 68 of a respective top plate 54. The upper cam members 72 which are mounted on each respective cam support member 70 are disposed in the cam slots 68 of both top plates 54. Each cam support member 70 is pivotally supported by a respective pivot member 74 which extends through, in turn, a respective circular orifice 50 between the bottom plates 36, a respective cam support member 70 and a respective circular orifice 66 between the top plates 54. The pivot members 74 extend upwardly from a base member 76 of the apparatus 20.On each cam support member 70 the upper cam members 72 are equidistant from the respective pivot member 74 and each upper case member 72 can slide in the repective cam slot 68, with the cam slots 68 of the two top plates 54 being displaced relative to each other. Accordingly, when the cam support members 70 are rotated about the respective pivot members 74, the upper cam members 72 slide in the respective cam slots 68 and cause the top plates 54 to move under the camming action either towards or away from each other between the engaged and separated positions. The plate support members 44 prevent outward longitudinal movement of the top plates 54 and the bottom plates 36.

The cam support members 70 are each pivotally attached by a pivot 77 at a respective end thereof to a slider member 78 which is itself attached to the free end 80 of a piston 82 of a pneumatic piston/cylinder assembly 84 which is mounted at its cylinder end 86 to the body 88 of the apparatus 20.

Figures 5 and 6 show the configuration of the top plates 54 in the separated and engaged positions. In the separated position which is shown in Figure 5, the piston 82 is retracted and the upper cam members 72 which are disposed in the cam slots 68 are relatively distant from the central longitudinal line between two top plates 54. Accordingly, the two top plates 54 are separated from each other. In the engaged position which is shown in Figure 6, the piston 82 is extended and the upper cam members 72 are relatively near to the central longitudinal line between the two top plates 54 and the two top plates 54 engage each other along their longitudinal edges 56.It will be seen from Figures 5 and 6 that in the separated position the top plates 54 define therebetween a relatively large central orifice 90 whereas in the engaged position the relatively small substantially circular orifice 60 is defined between the top plates 54.

Each cam support member 70 is also provided with a pair of lower cam members 92 which depend downwardly therefrom, each lower cam member 92 being received in a respective cam slot 52 in a respective bottom plate 36. When the cam support members 70 are rotated in the manner described hereinabove about the pivot members 74, the lower cam members 92 slide in the cam slots 52 thereby moving the bottom plates 36 between an enaged position and a separated position. This is shown in Figures 7 and 8, Figure 7 showing the engaged position and Figure 8 showing the separated position. In the engaged position, the piston 82 is in a retracted position and in the separated position the piston 82 is in an extended position.

It will be apparent from Figures 5 to 8 that the pair of top plates 54 and the pair of bottom plates 36 are operated to move between their respective engaged and separated positions by the action of the single piston/cylinder assembly 84. The pair of top plates 54 and the pair of bottom plates 36 move out of phase with each other whereby when the piston 82 is retracted the pair of top plates 54 is in the separated position and the pair of bottom plates 36 is in the engaged position and when the piston 82 is extended the pair of top plates 54 is in the engaged position and the pair of bottom plates 36 is in the separated position. The operation of the top and bottom plates 54,36 in relation to the denesting operation will be discused hereinafter.

The denester assembly 34 additionally includes a cover plate 94 which is disposed above the top plates 54. The cover plate 94 is supported by the plate support members 44 and receives the upper ends of the pivot members 74. The cover plate 94 includes a central circular orifice 96 which is substantially aligned with the corresponding central orifices 60,42 in the pair of top plates 54 and the pair of bottom plates 36, the central orifice 96 being sufficiently large so as to permit containers 2 to pass through unhindered. The cover plate 94 also includes an annular array of small circular holes 98 around the central orifice 96, each of which holes 98 has a respective upright rod 24 of the magazine 22 extending therethrough.

The bottom of the denester assembly 34 exits onto the upper surface of a substantially arcuate array of horizontally oriented guide rods 100 which are adapted to support a container 2 as it is conveyed by air pressure in the manner described hereinbelow away from the bottom of the denester assembly 34. The guide rods 100 consist of three lower guide rods 102 which are disposed in a row in a common horizontal plane and a pair of upper guide rods 104, each of which is on a respective opposing side of the row of the three lower guide rods 102, the upper guide rods 104 acting to support the sides of a container 2. The guide rods 100 are supported by the body 88 of the apparatus 20. The central guide rod 102 of the row is hollow and is connected at one longitudinal end thereof to a valve head 106 which is itself connected to a source of compressed air (not shown) and the other longitudinal end of the central guide rod 102 is closed. A series of inclined slots 108 is provided in the upper surface of the central guide rod 102. When compressed air is fed through the central guide rod 102, air exits through the inclined slots 108 and, as will be described hereinbelow, when the exiting air is blown against a container 2 which is supported on the guide rods 100, the container 2 is blown by the air in a direction away from the denester assembly 34. The valve head 106 is also provided with a tube 110 which is connected thereto and has an exit end 112 which is disposed beneath the denester assembly 34 and above the central guide rod 102.Compressed air from the tube 110 is blown against the far inner surface of a container 2 exiting from the denester assembly 34 and this causes the container 2 to be blown forwards under the action of the jet of air. The valve head 106 is also provided with air connection means 114 which connect to opposed hollow upright rods 24 of the magazine 22 which are disposed substantially along the central line between the pairs of top and bottom plates 54,36. These hollow upright rods 24 are provided with downwardly-inclined slots 116 which are directed inwardly towards the centre and the bottom of the denester assembly 34 and can act to cause radially inwardly and downwardly directed jets of air to assist in the denesting operation.

A pair of elongate guide members 118 is disposed above the array of guide rods 100. The guide members 118 each consist of a horizontal portion 120 which extends substantially from the denester assembly 34 to the free ends 122 of the guide rods 100 which are remote from the denester assembly 34 and an integral curved portion 124 which is curved downwardly in a substantially semi-circular configuration thereby to have a free end 126 which is disposed substantially below the said free ends 122 of the guide rods 100. The curved free ends 126 of the guide members 118 are disposed above a conventional conveyor (not shown). The guide members 118 are supported by guide member supports 128, one of which also supports a drip tray 130 which is located beneath the piston/cylinder assembly 84. The piston/cylinder assembly 84 is connected to a source of compressed air (not shown).

The operation of the apparatus shown in the Figures will now be described, with particular reference to Figure 9.

In operation, a stack 132 of containers 2 is held in the magazine 22, with the bases 8 of the containers 2 being upwardly oriented. In an alternative non-illustrated embodiment the containers may be fed into the magazine by a carousel system. The stack 132 of containers is held in position by the upright rods 24 of the magazine 22. In the normal stationary position of the apparatus, the piston 82 is in an extended position. However, in this description, the operation is described with the piston 82 initially in the retracted position whereby the bottom plates 36 are in the engaged position and thus the top plates 54 are in the separated position.In this configuration, the central orifice 42 in the bottom plates 36 is of slightly smaller dimensions than the peripheral rim 6 of the containers 2 whereby the bottom container 2 of the stack 132, and thereby also the remaining containers 2 in the stack 132, are supported by the bottom plates 36. The central orifice 60 in the top plates 54 is of larger dimensions than the peripheral rim 6 of the containers whereby the top plates 54 do not engage the stack 132 of containers 2. The piston 82 is then operated under pneumatic control and is moved to the extended position whereby the bottom plates are moved from the engaged position to the separated position under the camming action of the lower cam members 92 and the cam slots 52 in the bottom plates 36.This causes the central orifice 42 in the bottom plates to be enlarged to a dimension greater than the peripheral rim 6 whereby the bottom container 2 drops under the action of gravity and is blown down by a-ir jets from slots 116 out of the denester assembly 34. Simultaneously, the top plates 54 are moved from the separated position to the engaged position under the camming action of the upper cam members 72 in the cam slots 68.This causes the central orifice 60 in the top plates to be closed to a dimension which is smaller than the peripheral rim 6 of the containers 2 and this closing movement is performed sufficiently rapidly so that that container 2 which was above the bottom container 2 which drops out of the denester assembly 34 is engaged by the top plates 54 and supported, together with the remainder of the stack 132, by the action of the top plates 54 bearing against the peripheral rim 6. The resultant configuration is shown in Figure 9.

As the bottom container 2 drops out of the denester assembly 34, air jets issuing from the slots 116 in the hollow upright rods 24 impact the outer surface of the container 2 thereby assisting in the denesting operation. The container 2 falls onto an angle below the denester assembly 34 and the air jet issuing from the tube 110 blows against the bottom inner edge of the container 2 thereby to convey the container 2 forwardly. This is shown in Figure 9. The air jet from the tube 110 then assists in cleaning the interior of the container 2. This air jet also acts to impel the container 2 along the apparatus away from the denester assembly 34. The air jets issuing from the inclined slots 108 in the central guide rod 102 also assist in the cleaning operation and drive the container 2 to the far end of the apparatus 20.

The container 2 then reaches the curved portions 124 of the guide members 118. The container 2 in the upside down orientation is conveyed by centrifugal force around the curved portions 124 to land upright, i.e. with the base 8 lowermost, on the conveyor. The conveyor then conveys the container to a foodstuffs filling station.

The pneumatic piston 82 is returned to its retracted position under pneumatic control whereby the top plates 54 are moved from the engaged position to the separated position and the bottom plates 36 are simultaneously moved from the separated position to the engaged position. This causes the new lowermost container 2 to be released from engagement by the top plates 54 and to be engaged by the bottom plates 36 at the end of the cycle.

The cycle of retraction and extension of the piston 82 is periodically repeated at a desired speed so as to deliver a succession of containers onto the conveyor. The rate at which containers 2 are delivered can easily be varied simply by adjustment of the pneumatic control system of the piston/cylinder assembly 84. The system can be adjusted so as to deliver up to about 150 containers per minute.

Optionally, in order to assist the denesting operation, the thickness of the top plates 54 may be marginally greater than the distance between the top of the rim 6 of the bottom container 2 and the bottom of the upper pot portion of the upper container 2 nested therewith. Accordingly, when the top plates 54 move inwardly to engage the upper container 2, the top plates 54 are caused to bear against the top of the rim 6 of the bottom container 2 thereby pushing it downwardly and assisting in the denesting operation.

As is shown in detail in Figure 10, the semi-circular orifice 58 of each top plate 54 has two different radiis whereby the orifice 58 is substantially semi-elliptical i.e.

flattened in the region remote from the longitudinal edge 56.

Thus the orifice 58 is defined by two central portions 136 of relatively small radius which bear against the side of the container 2 which is supported by the top plates 54 when the top plates 54 are in the engaged position. The orifice 58 is also defined by two side portions 134 of relatively large radius (and having an axis displaced from that of the radius of the central portions 136) on either side of the central portions 136 which are relatively distant from the central longitudinal line between the two top plates 54 thereby to permit the container 2 reliably to fall down through the top plates 54 when the top plates 54 are in the separated position.

The air supply is preferably filtered so as to ensure that the containers are not contaminated. If desired, water jets may be used to clean the containers along the first part of travel along the guide rods. The water jets may, if desired, issue from orifices in the guide rods. The containers are then dried but the propelling air jets along a downstream section of the guide rods.

In an alternative embodiment, the cams may be operated by an electric motor and cam drive rather than a pneumatic piston/cylinder assembly.

It will be apparent to those skilled in the art that the dimensions of the various parts of the apparatus, including the top and bottom plates, may be varied to suit a particular container size. The present invention is applicable to the denesting of any containers with a nesting feature.

Claims (20)

CLAIMS.

1. An apparatus for denesting a stack of containers, the apparatus comprising a first container engaging means, a second container engaging means which is spaced from the first container engaging means in a direction which is, in use, substantially aligned with the stack, and drive means for selectively and alternately moving the first and second container engaging means into and out of engagement with the stack whereby the first and second engaging means alternately hold an end container of the stack thereby to release a previous end container from the stack.

2. An apparatus according to claim 1, wherein the drive means is adapted simultaneously to move the first and second container engaging means out of phase with each other.

3. An apparatus according to claim 1 or claim 2, wherein the first and second container engaging means each comprise a pair of adjacent plate members, each pair being adapted selectively to support a container therebetween.

4. An apparatus according to claim 3, wherein the drive means includes cam means which is adapted to translate each pair of adjacent plate members towards and away from each other between a container engaging position and a container releasing position.

5. An apparatus according to claim 4, wherein the cam means is operated by a pneumatic piston/cylinder assembly.

6. An apparatus according to any foregoing claim further comprising a first air jet means for blowing air towards a previous end container as it is released from the stack.

7. An apparatus according to any foregoing claim further comprising a conveying device for receiving the denested previous end container and conveying the said container away from the stack.

8. An apparatus according to claim 7, wherein the conveying device comprises a plurality of guide rails and a second air jet means for impelling the said container along the guide rails.

9. An apparatus according to claim 8, wherein the second air jet means comprises an air jet tube and a series of air outlets in at least one of the said guide rails, which air jet tube and air outlets are adapted to blow air into the interior of the container thereby to propel the container along the guide rails.

10. An apparatus for denesting containers substantially as hereinbefore described with reference to the accompanying drawings.

11. A method of denesting a stack of containers, the method comprising the steps of: (a) providing first and second container engaging means, the second engaging means being spaced from the first engaging means in a direction substantially aligned with the stack; and (b) selectively and alternately moving the first and second container engaging means into and out of engagement with the stack whereby the first and second engaging means alternately hold an end container of the stack thereby to release a previous end container from the stack.

12. A method according to claim 11, wherein in step (b) the first and second container engaging means are simultaneously moved out of phase with each other.

13. A method according to claim 11 or claim 12 wherein each container engaging means comprises a pair of adjacent plate members between which a container is selectively supported.

14. A method according to claim 13, wherein in step (b) the respective plate members of each respective container engaging means are moved towards and away from each other by a camming action.

15. A method according to any one of claims 12 to 14 further comprising the step of blowing air towards a previous end container as it is released from the stack thereby to assist the denesting operation.

16. A method according to any one of claims 12 to 15 further comprising receiving the denested previous end container in a conveying device and conveying the said container away from the stack.

17. A method according to claim 16, wherein the said denested container is conveyed by means of air jets.

18. A method according to claim 17 wherein a plurality of air jets are blown into the interior of the container thereby to propel the container away from the stack.

19. A method according to any one of claims 16 to 18 further comprising depositing the denested container in an upright position onto a conveyor for conveying the container to a filling station.

20. A method of denesting containers substantially as hereinbefore described with reference to the accompanying drawings.