GB2050987A - Apparatus and method for redistributing material within a pouch - Google Patents

Abstract

Apparatus for uniformly redistributing material, such as powder, granular material or moist material, in a pouch comprises a plurality of roller pairs 2a, 2b, 4a, 4b, 6a, 6b, 8a and 8b arranged in a series, rollers 2b, 4b, 6b and 8b being driven at a faster speed than the other rollers. This results in the pouch being flexed repeatedly and squeezed as it is transported through the nips of the roller pairs with consequential uniform redistribution of the material within the pouch. The rollers may all run at constant speed but it is also envisaged that the speeds of rollers may be varied cyclically. At least one roller of each pair may be spring biased towards the other roller of the pair. <IMAGE>

Description

SPECIFICATION Apparatus and method for redistributing material within a pouch This invention relates to apparatus and a method for making more uniform the distribution of a material contained within a pouch. The term "pouch" is used herein to refer to any type of substantially flat flexible package.

Pouches are used to contain materials which to some extent are flowable or deformable, such as powders, granular materials, and wet or moist materials. When the pouch is filled with material, normally there will be a greater bulk of material at one end of the pouch than at the other and it is desirable for the material then to be redistributed within the pouch so as to be more uniform, to facilitate handling of the pouch by packaging equipment.

This is normally done by passing the pouch through a pair, or several pairs, of driven rollers, the pouch being oriented so that that end containing the greater bulk of material enters the rollers first. This is not by any means ideal, because one is trying to move the material in the plane of the pouch by applying pressure perpendicular to that plane and to achieve redistribution in this rather indirect manner, the pressure that has to be employed may be high enough to cause damage to the pouch orto the product in it, or both; The invention seeks to provide an improved apparatus and method for redistributing material within a pouch.

From one aspect, the invention provides apparatus for making more uniform the distribution of a material contained within a pouch, comprising at least one pair of rollers and means adapted to drive one roller of the pair at a different speed from the other but in the same peripheral direction at their nip. It should be appreciated that in this specification references to the speeds of rollers orto differences between the speeds of rollers refer to their peripheral speeds, unless of course the context demands otherwise.

As the pouch passes between the differentially driven rollers, it is to some extent flexed, as well as squeezed, and it is believed that the flexing facilitates movement of the material in the plane of the pouch and this enables reduction of the maximum pressure to which the pouch need be subjected.

Preferably, a plurality of roller pairs are provided, arranged in a series such that a pouch can simultaneously passthroughthe nips of at least two of said roller pairs, and means adapted to drive one roller of each of said plurality of roller pairs at a different speed from the other roller of that pair, with the faster of the rollers in successive ones of said plurality of roller pairs being on opposite sides of the path of the pouch. It is feasible that guide means may be provided between successive ones of these roller pairs to help guide the pouch along its path and such guide means may be in the form of additional rollers or roller pairs positioned between the differentially driven roller pairs.

In one form of the invention, all the rollers are driven at constant speeds.

In another form, one set of rollers comprising those which lie alternately one side, then the other, of the path in successive ones of said roller pairs, is driven at constant speed and the other such set of rollers is driven at a speed which cyclically varies from above to below that of said one set.

In a further form, one set of rollers comprising those which lie alternately one side, then the other, of the path in successive ones of said roller pairs, is driven at a cyclically varying speed, and the other such set of rollers is driven at a speed which cyclically varies in opposite phase from that ofthe first set.

The invention also envisages various geometrical arrangements for the rollers, which preferably are provided with stop means for setting the maximum gaps at their nips. In one arrangement, the maximum gaps at the nips of the rollers of each pair are equal. It has been found that this arrangement is particularly desirable when operating on pouches containing a wet or moist product.

in a different arrangement, the maximum nips of the roller pairs form a uniformly converging path for the pouch. This can be achieved, using rollers of equal diameter, by arranging for the axes of an upper set of rollers, when at the maximum nip, to lie in a plane which is at an angle to the plane containing the axes of a lower set of rollers, the axes of all the rollers being parallel to each other. It has been found that this arrangement is particularly suited for redistributing materials which are difficult to move, such as certain fine powders.

In a further arrangement, the maximum nips of the roller pairs form a path for the pouch which converges at a progressively reducing angle of convergence. This is referred to in more detail below, and has been found well suited where the material within the pouch is a relatively free-flowing powder or granular material.

Preferably the position of the stop means is adjustable to enable the maximum nip gap to be adjusted.

Preferably at least one roller of each said roller pair is resiliently biassed towards the other, and it is further preferred that the resilient biassing means should be adjustable for adjusting the biassing force.

It is desirable to have some biassing force applied when the rollers are in contact with each other so that if an empty and consequently substantiallVflat pouch arrives it will be gripped by the rollers and properly transported through them and not becorne undesirably lodged or jammed at some point in the roller mechanism. However, it may be desirable for this biassing force to be less than that desired for material-redistribution.

To deal with this, in accordance with a feature of the invention, at least one roller of each said pair is provided with two-stage resilient biassing means providing a relatively lower biassing force towards the other roller when the gap between the rollers is less than a predetermined size and a relatively higher biassing force towards the other roller when the gap between the rollers is greater than a predetermined size. The lower biassing force normally keeps the rollers lightly pressed together so that they will grip an empty pouch which is presented to them, and it will therefore be transported through the apparatus properly.The predetermined gap size will be selected such that when a full pouch arrives it will push the rollers apart until the gap is greater than the predetermined size whereupon the relatively higher biassing force becomes available to provide the pressure on the pouch necessary to redistribute the material in it, the stop means eventuallycoming into play to positively limitthe nip gap if the pouch is thick enough.

Preferably also means for adjusting at least the relatively higher biassing force of each roller pair is provided.

From a further aspect, the invention provides a method of making more uniform the distribution of a material contained in a pouch comprising passing the pouch between one or more pairs of rollers which are arranged and driven so asto simultane ouslytransport, flex and squeeze the pouch as it passes between them.

In order that the invention may be more clearly understood, some embodiments thereof will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows apparatus in accordance with the invention having two sets of rollers arranged parallel to each other, and illustrating a differential speed drive arrangement; Figure 2 shows in a more complete way an apparatus according to the invention having input and output conveyors, and to which the drive arrangement in Figure 1 may be applied; Figure 3 shows a plan view of a guide used in the Figure 2 apparatus; Figure 4 shows a further alternative roller arrangement; and Figure 5 illustrates a manner in which any of the rollers may be mounted so as to achieve two-stage biassing thereof.

In the apparatus shown in Figure 1, four pairs of rollers 2a, 2b; 4a, 4b; 6a, 6b; and 8a and 8b are arranged in series and are driven in the directions indicated by the arrows so that a pouch presented to the rollers 2a, 2b, thick end first, will be transported in succession through the nips of the four roller pairs and delivered from rollers 8a, 8b. The rollers are shown with their nip gaps at maximum values set by stop means which will be described below with reference to Figure 2.

In order to facilitate the redistribution of material within a pouch in accordance with the invention, the four rollers having the suffix a, that is rollers 2a, 4a, 6a and 8a are all driven at one constant speed while the four rollers having the suffix, that is rollers 2b, 4b, 6b and 8b, are all driven at a constant but different speed, which may be either higher or lower.

Consequently the two rollers of every pair are being driven at different speeds from each other and this tends to make the pouch flex as it passes between the pair of rollers, in addition to the squeezing force being applied to the pouch by the rollers. The direction of flexing changes as the pouch passes from each pair of rollers to the next because the direction of the speed differential changes. Consequently as a pouch passes through it is simultaneously flexed back and forth and squeezed, to achieve the desired improved uniformity of the material in it.

The arrangement employed for driving the rollers is shown schematically to include a motor, such as a constant-speed electric motor, 10, which drives the input of a gear box 12 having forward and reverse outputs 14 and 16. The two different outputs are employed to achieve rotation of the upper set of rollers anti-clockwise, and the lower set of rollers clockwise. Any suitable form oftransmission, which may include gears, belts, chains or a combination of these, connects the forward output gear 14 of gear box 12 to two toothed pulley wheels 18 and 20. The transmission is indicated at 22, and has two branches, one leading to each of the wheels 18 and 20. Wheels 18 and 20 have equal numbers of the teeth.

Atoothed belt 24 passes round pulley 18 and round pulleys 26 which are respectively mounted coaxiallywith rollers 26 and 6b. To maintain belt 24 under tension while at the same time allowing rollers 2b and 6b to move up and down against their biassing means (which will be described below in relation to Figure 2) an idler pulley 28 is biassed into contact with one rtin of the belt 24 by means of a biassing spring 30, idler pulley 28 being mounted at the end of an arm 32 supported at its other end on a fixed pivot 34.

A further belt 36 passes in a similar manner round toothed pulley 20 and toothed pulleys 38 coaxial with rollers 4a and 8a and is tensioned by a similar tensioning arrangement 40. Consequently, the four top rollers are all driven in the same direction. However a difference in speed is imposed between rollers 2b and 6b on the one hand and rollers 4a and 8a on the other hand, by having different numbers of teeth on the pulleys 26 on the one hand, and the pulleys 38 on the other hand. For example, pulleys 26 may have twenty-one teeth while pulleys 38 have twenty-two teeth.

The rollers of the lower set are driven in exactly the same manner from the reverse output 16 of the gear box 12. The arrangement will not be described in detail because its components correspond with those of the arrangement for driving the upper rollers and they have been given the same reference numerals, plus one hundred.

The result isthatone rollerofeach of the roller pairs is driven at a different speed from the other roller of that pair, with the faster rollers in the successive pairs i.e. the rollers 2b,4b,6b and 8b being on opposite sides of the path of the pouch through the apparatus. It will be appreciated that other forms of drive arrangements may be used to achieve this result. For instance, the arrangement shown could be modified by having equal numbers of teeth on the pulleys 26,38, 126, and having identical numbers of teeth on pulleys 18 and 118 which are different from, instead of the same as, the numbers of teeth on pulleys 20 and 120, the latter of course being the same as each other.

As just described, although the speed of the two rollers of a pair differ from each other, each of the rollers runs at a constant speed.

In a modified arrangement, one "staggered" plurality of rollers such as the rollers with the suffixes a may be driven at a constant speed while the other plurality, i.e. those with suffixes b, are driven as a speed which is cyclically varied from the above to below that speed. This may be achieved, for example, by incorporating into the branches ofthe transmission 22 and 122 through which the suffix b rollers are driven special gear boxes such as are schematically shown at 42 and 142. These are commercially available and involve non-circular meshing gears whose effective ratio changes cyclically as they rotate.It is preferred that the speed of the rollers should cycle at a rate sufficient to give two or three reversals in the direction of speed differential during the passage of a single pouch between a particular pair of rollers and this can be arranged by having suitable gearing ratios present in the transmission on the output side and on the input side of the gear boxes 42 and 142.

In a further modification, the speeds of the rollers with suffix a and the rollers with suffixb are both cycled between higher and lower values, but out of phase with each other, so that again the direction of the speed differential between a pair of rollers alternates. This can be achieved by adding further nonconstant ratio gear boxes into the branches of the transmissions 22 and 122 which drive the rollers having suffix a, as illustrated in Figure 1.

The speed differential, or peak speed differential, between the rollers of a pair may be up to 15%, preferably up to 10%, and more preferably around 5%.

In the apparatus shown in Figure 2, four roller pairs 2a, 2b; 4a, 4b; 6a,6b; and 8a, 8b are again shown, with additional details of their mounting arrangements, but without the drive mechanism being shown, for the purpose of clarity. The drive mechanism may in fact be the same as that shown in Figure 1, with or without the modifications which have been referred to.

In Figure 2, an input conveyor 46 is provided in the same plane as the lower set of rollers and is driven in the same direction. This conveyor will receive filled pouches from a previous piece of equipment, which can be arranged to dispositthe pouches on the conveyor with their thick ends facing approximately towards the nip of the first pair of rollers 2a, 2b. To fully align the pouches as they approach the first pair of rollers, a pair of side guides 48 are provided, which are shown in plan view in Figure 3.To help ensure that each pouch is drawn into the nip of the first pair of rollers 2a, 2b as it arrives at the nip, an upper belt 50 is provided, driven in the same direction as the upper set of rollers, and positioned so as to contact the top of an incoming pouch and, together with conveyor 46, push it into the nip of the rollers 2a, 2b.

The incoming pouches will in practice differ in thickness and to accomodate this the second roller 52 of conveyor 50 is mounted at each end in a vertically slidable mounting block 54, arranged to slide between guides 56 on a frame of the apparatus. The upper limit of movement of mounting block 54 and hence the maximum nip gap (all nip gaps are illustrated at their maximum values) is set by a threadedly mounted and consequently adjustable stop 58 and it is biassed down towards the opposite roller 2a by means of a spring 60 in compression between the mounting block 54 and a frame portion of the machine.As a full pouch enters under con veyor50,the conveyorcan rise againstthe bias of spring 60 to accommodate it, and at the same time the mounting block 54 will carry with it the first upper roller 2b, which is mounted between the same mounting blocks, thereby preparing the nip of the first pair of rollers to accept the incoming pouch.

As can be seen, the second, third and fourth pairs of material-redistributing rollers are mounted on mounting blocks 62 similar to block 54, which slide between similar vertical guides and which are also provided with adjustable stops 64 and biassing springs 66. An output conveyor 68 carries the pouches away form the final pair of rollers 8a, Sb.

Whereas in Figure 1 the two roller sets were parallel with each other, in Figure 2 the stops 58 and 64 are adjusted so that the fully displaced positions of the upper set of rollers are on a curve indicated by the broken line 70. Consequently the nips between the rollers provide a path for the pouches which converges, but converges to a decreasing extend as the pouches pass through the succession of rollers.

It has already been mentioned that this is found to be particularly suitable where the material in the pouches is a relatively free-moving material such as a coarse powder or granular material.

Figure 4 illustrates how the fully displaced positions ofthe upper rollers may be set in a plane angled relative to the plane of the lower rollers so as to provide a uniformly converging path for the pouches between the nips of the rollers. As already mentioned, this has been found to be effective for fine powders which are difficult to move.

Referring now to Figure 5, there is shown an arrangement for two-stage biassing of a roller, which could be employed instead ofthe biassing arrangements shown in Figure 2. Here, a shaft 72 provided with a shoulder 74 extends upwardly from the roller mounting block 62 and slides freely in a guide aperture 76 in a frame part 78 of the apparatus.

A relatively weak spring 80 extends in compression between the block 62 and the underside of frame part 78 so as to bias the mounting block 62 and its roller lightly downwards, in practice into contact with a lower roller. When a pair of rollers are maintained in light contact in this manner, they will grip and transport even an empty pouch which may be presented to them. However, a full pouch will raise the roller and mounting block 62 sufficiently for shoulder 74 to contact a bush 82 which slides freely on shaft 72. This introduces the extra, and greater, bias of a further compression spring 84 which extends between the upper side of bush 82 and the lower surface of frame part 78, which is formed with a projection to locate the end of the spring 84.A filled pouch is therefore subjected to a force which may be at a level suitable forthe materialredistributing process, and which reaches a maximum when the upper end of shaft 72 contacts an adjustable stop 85 threadedly mounted in a bracket 87. When a pouch has passed and mounting block 62 returns downwards, the downward movement of bush 82 is limited by a flange 86 projecting inwardly from the lower end of a tube 88 whose upper end is securely fixed in any suitable manner to the frame part 78.

In Figure 2 the upper rollers are shown as being - independently and individually spring loaded, which is most desirable because it enables the degree of spring loading to be adjusted independently for each roller either by interchanging the biassing springs or providing an adjustable stop for one end of each spring. This may be done by having the upper end of springs 60,66 in Figure 2, or spring 84 in Figure 5 located against an annular ring threadedly and therefore adjustably mounted in frame part78, instead of against a fixed part of frame part 78. It is also possible to mount the whole of the upper roller set on a common spring-loaded mounting block. Although in the described embodiment the rollers of the lower set are fixed, they also may be spring loaded if desired.

The characteristics of different materials within pouches are different, and they may require different treatment to achieve satisfactory uniformity. This is facilitated by the provision in the embodiment which has been described of means for adjusting the nips of the roller pairs independently, and the ability to adjust or change the loading on each of the roller pairs independently, and additionally of course it is possible to incorporate speed adjustment means of many kinds into the roller drive arrangement so that the roller speeds and differentials between roller speeds, can be adjusted to optimum values for different materials.

In the described embodiments, four roller pairs are employed, and this has been found to be satisfactory in practice. However, in principle, any number of rollerpairs may be employed to carry out the method of the present invention. It is desirable, though, for a pouch to be simultaneously treated by two pairs of rollers, so that preferably at least two pairs should be provided. In practical apparatus in accordance with the invention, the four pairs of rollers have been of 45 mm diameterwith their axes spaced 50 mm apart, and this apparatus has been used satisfactorily with pouches having a length of between 120 mm and 150 mm so that a pouch is always simultaneously between two roller pairs and may just be between three.

A possible disadvantage of simultaneously contacting the pouch with two or more roller pairs is that contact of one side of the pouch with two or more rollers having different speeds might in some cases cause scuffing of the finish on the pouch. This possibility is avoided by spacing the roller pairs sufficiently that a pouch is contacted only by one pair at a time and if necessary including guide means for the pouches, between the roller pairs.

Claims (20)

1. Apparatus for making more uniform the dis tribution of a material contained within a pouch, comprising at least one pair of rollers and means adapted to drive one roller of the pair at a different speed from the other but in the same peripheral direction at their nip.

2. Apparatus according to claim 1 comprising a plurality of roller pairs arranged in a series such that a pouch can simultaneously pass through the nips of at least two of said roller pairs, and means adapted to drive one roller of each of said plurality of roller pairs at a different speed from the other roller of that pair, with the faster of the rollers in successive ones of said plurality of roller pairs being on opposite sides of the path of the pouch.

3. Apparatus as claimed in claim 2 wherein the rollers are driven at constant speeds.

4. Apparatus as claimed in claim 2 wherein one set of rollers comprising those which lie alternately one side, then the other, of the path in successive ones of said roller pairs is driven at constant speed and the other such set of rollers is driven at a speed which cyclically varies from above to below that of said one set.

5. Apparatus as claimed in claim 2 wherein one set of rollers comprising those which lie alternately one side, then the other, of the path in successive ones of said roller pairs, is driven at a cyclically vary ing speed, and the other such set of rollers is driven at a speed which cyclically varies in opposite phase from that of the first phase.

6. Apparatus as claimed in any one of claims 2 to 5, wherein the maximum gaps at the nips of the rol lersofeach pair are equal.

7. Apparatus as claimed in any one of claims 2 to 5, wherein the maximum nips ofthe roller pairs form a uniformly converging path for the pouch.

8. Apparatus as claimed in any one of claims 2 to 5, wherein the maximum nips of the roller pairs form a path for the pouch which converges at a progres siveiy reducing angle of convergence.

9. Apparatus as claimed in any preceding claim wherein at least one roller of each said pair is resiliently biassed towards the other.

10. Apparatus as claimed in claim 9, wherein means for resiliently biassing said at least one roller is adjustable to adjust the biassing force.

11. Apparatus as claimed in ciaim 9 or claim 10 comprising stop means providing a predetermined maximum gap between the rollers of the roller pairs.

12. Apparatus as claimed in claim 11 wherein the position ofthe stop means is adjustable.

13. Apparatus as claimed in any of the preceding claims wherein at least one roller of each said pair is provided with two-stage resilient biassing means providing a relatively lower biassing force towards the other roller when the gap between the rollers is less than a predetermined size and a relatively higher biassing force towards the other roller when the gap between the rollers is greater than said predetermined size.

14. Apparatus as claimed in claim 13 comprising means for adjusting at least the relatively higher biassing force of each roller pair.

15. A method of making more uniform the distribution of a material contained in a pouch comprising passing the pouch between one or more pairs of rollers which are arranged and driven so as to simultaneously transport, flex and squeeze the pouch as it passes between them.

16. Apparatus for re-distributing material within a pouch substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

17. Apparatus for re-distributing material within a pouch substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings.

18. Apparatus for re-distributing material within a pouch substantially as hereinbefore described with reference to Figure 1 or Figures 2 and 3, as modified in Figure 4 of the accompanying drawings.

19. Apparatus for redistributing material with a pouch as claimed in any of claims 20 to 23 and including the modification hereinbefore described with reference to Figure 5 of the accompanying drawings.

20. A method of re-distributing material within a pouch, substantially as hereinbefore described.