GB2169884A - Marshalling apparatus - Google Patents

Abstract

A marshalling unit for presenting a series of filled packs (10) to a station at which the packs require to be precisely located, whilst not allowing them to touch each other at any time, comprises a series of freely-rotatable, overlapping star wheels (30, 32) arranged on axis lying in a common plane parallel to the conveyor (12) carrying the packs. The star wheels engage the packs by camming action, each pack always being engaged by two star wheels. Over-run is prevented by suitable dampers associated with individual star wheels. <IMAGE>

Description

SPECIFICATION Marshalling apparatus This invention relates to marshalling apparatus for arranging an initially-random group of generally similar articles in equal spacing in file or line-ahead array.

Such apparatus will typically, in known forms, take the form of a conveyor moving between side guides which constrain the articles into their line-ahead formation, either as they pass on to the conveyor from a deadplate or from another conveyor, or while the articles are already being carried alone by the same conveyor. In another form of such marshalling apparatus, the articles are carried along a runway comprising fixed side and bottom guides, being propelled by gravity or by a suitable moving element. This moving element, which is driven by some propulsion means such as a motor, may for example be a friction belt or a plurality of belts, or a cord or cable, or a chain carrying pusher dogs which engage the articles.

Marshalling apparatus of these known kinds requires that the articles may not be prevented from touching each other. In the case where they are propelled along by pusher dogs, these dogs may be so spaced that the articles are thereby held apart from each other. Nevertheless, where pusher dogs are employed there will normally be, between the front or working face of each dog and the rear of the next dog in front of it, a gap longer than the article, so that the articles, although kept apart from each other, are free to move forward through this gap. Such an arrangement is not satisfactory if the articles are sufficiently fragile to require protection against mechanical damage, or if there is a requirement for the articles to be located in precise positions relative to each other in the file, typically in positions in which they are exactly equally spaced from each other.

This last-mentioned requirement applies where, for example, the articles are marshalled in line-ahead formation because they are then to be picked up, one by one or in batches, by a machine such as a robotic handling device, or because some other operation is to be performed on the articles while they are in this formation. In order to satisfy this requirement of precise, predetermined positioning, some additional means, such as a stop element or a series of stop elements, will normally need to be provided at the station at which the operation is to be performed.

According to the invention, marshalling apparatus, for arranging an initially-randnm group of generally similar articles in equal spacing in file, comprises a train of star wheela rotatable at equal speeds about axes lying in a common plane, each star wheel having arms each of which is adapted to engage two of the articles simultaneously so as to define a spacing between the articles, the axes being so spaced that, after joining the train, each article always engages two adjacent star wheels simultaneously, and means being provided for advancing the articles along a path such that the file of articles is parallel to said common plane.

This arrangement providea a means for automatically keeping the articles separated from each other at all times, while also ensuring that at any time during their passage along the marahalling apparatus, as well as in their final position, each article is precisely located by the star wheel arms without the freedom to move forward or backward except when impelled to do so by the star wheels.

The star wheels are preferably freely rotatable, so as to be driven by the articles behind them while offering to the latter the smallest possible resistance. In this case, each star wheel is provided with damping means to prevent over-run prior to an article behind the star wheel coming into engagement with it.

On the other hand, the star wheels may in suitable circumstances be driven from a suitable power source. In that event the star wheels may themselves constitute the sole means for advancing the articles.

The articles themselves may take any form such that they are capable of being marshalled by the apparatus. The apparatus is in fact particularly suitable for handling articles susceptible to superficial damage, since besides its capacity to hold the articles in predetermined positions relative to each other, it can readily be designed so as to treat the articles gently at all times. This latter feature is related to the fact that each star wheel arm, as it comes into contact with an article (and again as it later relinquishes that contact) is moving at a velocity having a component in the direction of motion of the articles which is of the same magnitude as the forward velocity of the article itself.

A typical example of articlea suitable to be handled by apparatua according to the invention consists of packaging containers. These may be empty or full of a product. In the latter case the containers may be closed, i.e.

the articles may be complete filled packs. The containers may be of any shape found in the packaging industry, however, particularly appropriate applications for the invention are those where the articles, being filled packs, have peripheral portions which can rather easily be damaged if they are allowed to come into contact with eah other. An example of such a pack is a pot of thin plastics material having a closure which consists of a thin diaphragm, sealed over the open mouth of the pot by being bonded to an outwardly-projecting end flange of the pot. The peripheries of these flanges constitute the extremeties of the pots, so that if the packs are allowed to col lide with each other, the extreme edges of the diaphragm closures can easily become damaged.

The shape of most packaging containers, and of many other articles, is such that it is necessary for each star wheel to overlap the one or ones next to it. Preferably, therefore, alternate star wheels are axially displaced from each other, their axes being so spaced that the respective loci described by the tips of the arms of adjacent star wheels overlap each other.

If each pot, or other article, is not of uniform cross-section over its height, then the profiles of the arms of overlapping alternate star wheels will preferably be different from each other so that each star wheel, contacting the articles at a different level from the next star wheel, will nevertheless maintain between the articles a predetermined spacing which is substantially uniform throughout the train of articles. The transverse widths of the arms of the alternate star wheels are then preferably different from each other, the shapes of the profiles of all the star wheels being the same as each other.

The apparatus typically has star wheel support means defining a datum for the level at which each star wheel is located. In this case the star wheels can be easily removed, replaced and changed for star wheels of different profiles. Preferably each star wheel has a central body portion extending by unequal amounts axially with respect to the arms of the wheel, whereby the level at which the arms of the wheel are located can be selected with respect to the datum according to which of the unequal parts of the body portion is uppermost or lowermost. Each of the two unequal parts of the body portion is preferably the same for each star wheel.

This arrangement renders the apparatus quite versatile in terms of the cross-sectional and elevational shapes of articles that it can handle. This versatility can be further increased by providing that at least every alternate star wheel is mounted on the support means with removable spacing means therebetween so that by adding or subtracting said spacing means, the axial distance between the arms of adjacent star wheels can be varied whereby to adapt the apparatus for handling different groups of articles of non-uniform cross-section in which the cross-section varies from one group of articles to another.

Each star wheel arm is preferaby profiled so as to guide esch article by camming action along a path between a first position in which the arm, engaging the article next ahead of it, lies perpendicular to the common plane of the star wheel axes, and a second position in which the same article is engaged by an arm of the next star wheel lying perpendicular to the said plane, the path being such that the transverse position of the article with respect to the file is the same in the second position as in the first position.

The marshalling apparatus of the invention, when used for the handling of packs or containers, will normally be part of a packaging line, so that'the apparatus constitutes a feeder for a machine for performing repetitive operations with successive contsiners. Such a machine may for instance be a robotic transfer device for placing the packs on packaging trays or in boxes prior to despatch. It may equally be, for example, a closing apparatus for applying closures to the filled containers; or the filling machine or filler which delivers the product into the containers, or a sterilising device for sterilising the containers before they are filled.Where sterilising is employed, the steriliser, filler and closing apparatus may all be part of an integrated aseptic packaging line having a common conveyor for presenting the containers successively at the sterilising, filling, closing and final packing stations of the line.

Such a common conveyor may comprise the star wheel marshalling apparatus of the invention over its entire length. In such a case the initial arrangement of the containers may not be random, for example if they are received by the marshalling apparatus from a stack of containers nested one within the other. It is accordingly to be understood that, while the apparatus of the invention is suitable for use where the articles initially constitute a random group, such a grouping is not essential to its operation.

A marshalling apparatus in one embodiment according to the invention will now be described, in the context of one typical application for the handling of filled and closed containers, all by way of example only and with reference to the drawings of this application, in which: Figure 1 is a diagrammatic plan illustrating an installation for placing the packs in open trays to be shrink-wrapped for despatch from the packing station, the installation including the marshalling apparatus, Figure 2 is a side elevation showing part of the marshalling apparatus, partly broken away and partly in section; and Figure 3 is a sectional plan view taken on the line 111-Ill in Figure 2.

Referring to Figure 1, a filling and closing machine (not shown) for packing cream in plastic pots and for closing the pots, to form packs 10, delivers the packs on to a discharge conveyor 12 which is driven in the forward direction indicated by the arrow A. In this example, the packs 10 initially, at any given moment, constitute a random group on the conveyor, as indicated at 14. This may arise, for example, due to the packs being circulated through a holding conveyor system, or held in a holding store between the filling and closing machine and the discharge con veyor 12. The latter may receive the outputs of several filling and closing machines not synchronised with each other, and this can be another cause of initial randomness in the grouping of the pots on the discharge conveyor.

At the downstream end of the discharge conveyor there is a robotic transfer machine indicated diagrammatically at 16. The transfer machine picks up the leading three packs from the discharge convegor 12 and places them on open cardboard trays 18 which are arranged on a second conveyor 20. In a typical scheme of operation, the working head 22 of the transfer machine picks up a group of packs from the discharge conveyor while the latter is stationary, the latter then indexing forward to bring a further group of three packs into position, ready to be picked up, during the interval while the transfer machine is placing the previous group of packs on a tray 18.

The loaded trays, subsequently carried forward to a wrapping station, not shown, by the convegor 20, are there shrinkwrapped for subsequent despatch.

The packs 10 must be presented in single file to the working head of the transfer machine 16; and must always stop in the same predetermined positions so that the latter will correctly engage them. In addition, the packs are such that they must not touch each other if the possibility of damage is to be avoided.

To ensure that these requirements are met, there is associated with the discharge conveyor 12 a marshalling unit 24 for arranging the packs 10 in equal spacing in file. The marshalling unit 24 will now be described with reference to Figures 2 and 3.

The marshalling unit has a fixed frame including a main beam 26 which extends parallel to the discharge conveyor 12, and which may be made adjustable as to the vertical distance between the beam 26 and the upper surface of the conveyor 12. In this example the conveyor 12 is shown as a conventional endless belt.

A series of vertical mounting pillars 28 are secured to the main beam 26 so as to project upwardly from the latter. Each mounting pillar carries a respective one of a train of star wheels, and comprises a boss portion 29 secured to the beam 26 and a mounting stem 54 extending upwards from the boss portion.

The boss portion 29 has an upper surface 52 which serves as a datum determining the vertical position of the star wheel mounted on the pillar.

The star wheels comprise what may be described as upper and lower star wheels 30 and 32 respectively, The star wheels 30 are arranged alternately with the star wheels 32.

All the star wheels are freely rotatable on their respective mounting pillars 28, and are therefore capable of being rotated at equal speeds about their axes. The axes of the star wheels lie in a common plane parallel with the path along which the packs 10 are advanced by the conveyor 12.

Each star wheel is provided with a damping device 34 which may take any suitable form, but which in this example comprises a compression spring 36 mounted on the associated mounting pillar 28 so as to apply an axial damping force to the star wheel. This spring force is adjustable by means of a nut 38, so that it may be set to a value such as to prevent over-run of the star wheel prior to a pack 10 behind the star wheel coming into engagement with it, during operation of the apparatus which will be described hereinafter.

The star wheels are made of a suitable, preferably lightweight, material such as a nylon or aluminium. Each has four equally-spaced radial arms 40, the four arms of each wheel being substantially identical to one another. The arms 40 radiate from a central boss comprising two boss portions 42 and 44 of unequal length. The short boss portions 42 of all the star wheels 30 and 32 are of the same length as each other, as are the long boss portions 44. The beam 26 and a mounting stem 54 extending upwards f rom the boss portion.

The boss portion 29 has an upper surface 52 which serves as a datum determining the vertical position of the star wheel mounted on the pillar.

The star wheels comprise what may be described as upper and lower star wheels 30 and 32 respectively. The stsr wheels 30 are arranged alternately with the star wheels 32.

All the star wheels are freely rotatable on their respective mounting pillars 25, and are therefore capable of being rotated at equal speeds about their axes. The axes of the star wheels lie in a common plane parallel with the path along which the packs 10 are advanced by the conveyor 12.

Each star wheel is provided with a damping device 34 which may take any suitable form, but which in this example comprises a compression spring 36 mounted on the associated mounting pillar 28 so as to apply an axial damping force to the star wheel. This spring force is adjustable by means of a nut 38, so that it may be set to a value such as to prevent over-run of the star wheel prior to a pack 10 behind the star wheel coming into engagement with it, during operation of the apparatus which will be described hereinafter.

The star wheels are made of a suitable, preferably lightweight, material such as a nylon or aluminium. Each has four equally-spaced radial arms 40, the four arms of each wheel being substantially identical to one another. The arms 40 radiate from a central boss comprising two boss portions 42 and 44 of unequal length. The short boss portions 42 of all the star wheels 30 and 32 are of the same length as each other, as are the longs boss portions 44. The star wheels 30 are mounted with their short boss portions 42 uppermost, while the star wheels 32 have their short boss portions 44 uppermost. The arms of the upper wheels 30 thus lie at a level above that of the arms of the lower wheels 32, so that the wheels are, in effect, axially displaced from each other.The mounting pillars 28, are so spaced that the locus of the tips of the arms 40 of each wheel 30 overlaps the corresponding locus described by the adjacent wheels 32. In other words, as seen in Figures 2 and 3, the arms of adjacent star wheels themselves overlap each other over part of a revolution.

Each pack 10 in this example comprises a thin plastics pot 46, which may for instance have been made by a thermoforming process and be extremely vulnerable to denting if subjected to radial forces of too great a magnitude. Alternatively it may be injection moulded. Each pot is filled with cream, f or example by an aseptic filling device upstream of the portion of the delivery conveyor 12 seen in Figure 1. The pot 46 is closed by a flexible diaphragm 48 which extends over the whole of the top of the pot, the periphery of the diaphragm, at 50, defining the greatest circumference of the pack 10.

Each pot 46 is, in this example, of generally downwardly-convergent conical form. Accordingly, since the arms 40 of the star wheels 30 are at a higher level than those of the star wheels 32, the former are generally wider than the latter, as seen in Figure 3, so as to maintain equal spacing between adjacent packs 10.

If the pots 46 are of upwardly convergent conical form, the positions of the star wheels can be reversed, so that the wheels 32 become the upper star wheels and the wheels 30 the lower. This is achieved simply by inverting each star wheel so that the relative positions of the long and short boss portions, 44 and 42 respectively, are reversed. Should it be required that the marshalling apparatus handle a batch of conical pots having a different cone angle from those shown (whether upwardly or downwardly convergent), the vertical positions of either the star wheels 30, or that of the star wheels 32, or all of them, may be adjusted for example by placing washers of suitable thickness below the lower boss portion of the appropriate star wheels, thus raising them with respect to the datum surface 52.Alternatively washers may be inserted between the boss portions 29 of the mounting pillars and the main beam 26 to achieve the same effect without the need to dismantle the associated clamping device. To raise or lower all of the star wheels with respect to the conveyor, the main beam 26 may, as already mentioned, be made capable of being itself raised or lowered.

As can be seen from Figure 3, each star wheel arm is adapted to engage two of the packs 10 simultaneously, so as to define a spacing between the two packs. Furthermore each pack is always in engagement with two adjacent star wheels simultaneously. Thus any forward movement of the packs has to be accompanied by rotation of the star wheels, and by corresponding forward movement of the other packs on that part of the delivery conveyor 12 alongside the marshalling unit 24. With the dampers correctly adjusted, this avoids the possibility of a pack moving in an uncontrolled manner forward or backward so as to tend to close the gap between it and either of the next adjacent packs. The possibility of the peripheral edges 50 of the closure diaphragms touching each other, with the accompanying danger of damage at the edges, is thereby prevented.

If the packs are of uniform cross-section, for example if the pots 46 are cylindrical or square in cross-section instead of tapered, all of the star wheels will be identical. It will be realised that with a set of star wheels of each of two sizes, such as a set of the wheels 30 and a set of the wheels 32, together with a set of washers for varying the height at which at least every alternate star wheel is set, a wide variety of shapes of pack or other articles can be handled by the marshalling unit within the limitations as to the dimensions of the articles (measured in the direction of motion of the articles) set by the longitudinal spacing between the star wheel axes to allow each article to be spaced from its neighbours.

Despite the dimensional differences between the star wheels 30 and the star wheels 32, the profile of the arms 40 is generally the same. Each arm has a camming portion 56 which is symmetrical about the radial midplane of the arm, the camming portions of adjacent arms being joined by an arcuate edge 58. This profile is such that each pack 10 is guided by camming action of the arm 40 behind it along a path, generally indicated by the straight arrows in Figure 3, between a first position (such as 60 in Figure 3) in which the same arm 40, engaging the pack 10, lies perpendicular to the common plane of the axes of the star wheels, and a second position (62 in Figure 33 in which the same article is engaged by an arm 40 of the next star wheel lying perpendicular to the same common plane. The transverse position of the pack 10 with respect to the file of packs on the conveyor 12 is the same in the second position as in the first position.

The direction of rotation of the star wheels is indicated by curved arrows in Figure 3. In operation, the discharge conveyor 12 is indexed forward in intermittent movement controlled by the transfer machine 16, in such a manner that there will always be a file of three packs 10 in position and stationary at the downstream end of the discharge conveyor ready to be picked up by the machine 16. The star wheels are so arranged that when the conveyor 12 is stationary, they are orientated as shown in full lines in Figure 3, e. with the radial centre planes of two arms of each star wheel disposed perpendicular to the path of the packs 10. When the conveyor 12 commences to move forward after a stationary period, the star wheel 32 which is seen immediately to the left of the position 60 is rotated by the next pack 10 behind it.This star wheel pushes the pack ahead forward as indicated in phantom lines at 60', at about which point this pack becomes engaged by an arm 40' of the next star wheel 30. This arm 40 is shown in contact with the pack at a further position indicated in phantom lines at 60.

It will be observed from the foregoing that the pack is first engaged from behind by the arcuate portion 58 of a star wheel and tends to roll along this arcuate portion until, at the position (at which the discharge conveyor 12 stops after the pack has moved forward through a distance equal to three times the pitch of the star wheel axes) shown in full lines in Figure 3, the pack is in substantially point contact with the camming portions 56 of the star wheels between which it is held.

The star wheel, by the arcuate portion of which the pack is first engaged from behind, is of course the same star wheel with which the leading part of the pack has been engaged in the previous position in which two of the star wheel arms are perpendicular to the path of the packs. Thus, at the position 60, the leading part of the pack is engaged by an arm 40' of the star wheel 30, the arms 40 and 40' of this wheel being both indicated in phantom in respect of the position 60'. In this position, the tip 57 of the arm 40' is still in contact with the next pack ahead, but this represents the instant at which the arm 40' ceases to be in contact with it.Similarly the tip 57 of the particular arm of the previous star wheel 32 that is indicated at 40 (though not shown in Figure 3 in respect of the position 60") is on the point of ceasing to be in contact with the pack which is at position 60.

From this it will be seen that each pack is always in contact with two star wheels simultaneously.

Although in the above example the star wheels sre freely rotatable and are entirely driven by the packs which are themselves carried forward by a moving conveyor, the star wheels may themselves be driven directly from a power source. In that case they will be driven by a common drive, being coupled together by, for example, a train of gears cr a common belt or chain drive. If the star wheels are driven from a power source, the driven moving conveyor may be absent, so that the star wheels themselves constitute the sole means for advancing the pots 10 or other articles, along a deadplate or other suitable idle support means.

Claims (13)

1. Marshalling apparatus, for arranging an initially-random group of generally similar articles in equal spacing in file, the apparatus comprising a train of star wheels rotatable at equal speeds about axes lying in a common plane, each star wheel having arms each of which is adapted to engage two of the articles simultaneously so as to define a spacing between the articles, the axes being so spaced that, after joining the train, each article always engages two adjacent star wheels simultaneously, and means being provided for advancing the articles along a path such that the file of articles is parallel to said common plane.

2. Apparatus according to Claim 1, wherein the star wheels are freely rotatable, each star wheel being provided with damping means to prevent over-run prior to an article behind the star wheel coming into engagement with it.

3. Apparatus according to Claim 1 or Claim 2, wherein alternate star wheels are axially displaced from each other, their axes being so spaced that the respective loci described by the tips of the arms of adjacent star wheels overlap each other.

4. Apparatus according to Claim 3, for handling articles of non-uniform cross-section, wherein the profiles of the arms of overlapping alternate star wheels are different from each other, so that each star wheel, in contacting the articles at a different level from the next star wheel, will nevertheless maintain between the articles a predetermined spacing which is substantially uniform throughout the train of articles.

5. Apparatus according to claim 4, wherein the transverse widths of the arms of alternate star wheels are different from each other, the shapes of the profiles of all the star wheels being the same as each other.

6. Apparatus according to any one of the preceding claims, having star wheel support means defining a datum for the level at which each star wheel is located, each star wheel having a central body portion extending by unequal amounts axially with respect to the arms of the wheel, whereby the level at which the arms of the wheel are located can be selected with respect to the datum according to which of the unequal parts of the body portion is uppermost or lowermost.

7. Apparatus according to Claim 6, wherein each of the two unequal parts of the body portion is the same for each star wheel.

8. Apparatus according to Claim 3 or Claim 4, having star wheel support mseans defining a datum for the level at which each star wheel is located, at least every alternate star wheel being mounted on the support means with removable spacing means therebetween so that by adding or subtracting said spacing means, the axial distance between the arms of adjacent star wheels can be varied whereby to adapt the apparatus for handling different groups of articles of non-uniform cross-section in which the cross-section varies from one group of articles to another.

9. Apparatus according to any one of the preceding claims, wherein each star wheel arm is profiled so as to guide each article by camming action along a path between a first position in which the arm, engaging the article next ahead of it, lies perpendicular to the common plane of the star wheel axes, and s second position in which the same article is engaged by an arm of the next star wheel lying perpendicular to the said plane, the path being such that the transverse position of the article with respect to the file is the same in the second position as in the first position.

10. Apparatus according to any one of the preceding claims, wherein the star wheels themselves constitute the sole means for advancing the articles.

11. Apparatus according to any one of the preceding claims, when part of a packaging line, the articles being filled or unfilled containers and the apparatus constituting a feeder for a machine for performing repetitive operations with successive containers.

12. Marshalling apparatus for arranging an initially-random group of generally similar articles, the apparatus being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, Figures 2 and 3 of the drawings of this application.

13. Apparatus according to Claim 12, arranged in an aseptic filling line substantially as hereinbefore described with reference to, and as illustrated in, Figure 1 of the drawings of this application.