GB2335175A

GB2335175A - Spreading device

Info

Publication number: GB2335175A
Application number: GB9805523A
Authority: GB
Inventors: David Robert Seaward; Peter John Whitlock
Original assignee: Molins Ltd
Current assignee: Mpac Group PLC
Priority date: 1998-03-13
Filing date: 1998-03-13
Publication date: 1999-09-15
Also published as: GB9805523D0

Abstract

An apparatus for use in manufacturing packaging containing a flowable material comprises a feeder tube 12 which has a longitudinal axis 13. In use, a tubular web is formed around the feeder tube 12. Two pairs of rotatable spreader arms 20 are provided for spreading the tubular web. The spreader arms of each pair are diametrically opposed and mounted such that their free ends 20a project beyond the downstream end of the feeder tube. Two rack 34 and pinion 32 arrangements are provided for driving respective drive shafts 22 of the spreader arms. The arrangement is such that rotation of the drive shafts 22 causes the free ends 20a of the spreader arms to move along respective curved paths defined in a plane which is transverse, preferably perpendicular, to the longitudinal axis 13. The apparatus is particularly suitable for use in the manufacture of tetrahedral packages.

Description

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37 2335175 MB/3814-P Spreading Device The invention relates to spreading devices for use in the manufacture of flexible packaging for flowable materials and particularly, but not exclusively, to such devices for use in the manufacture of tetrahedral packages.

Various apparatus for forming tetrahedral packages have been proposed: for example, the apparatus described in GB 2256415B and WO 95/01907 which are concerned With the manufacture of tetrahedral bags for tea, i.e. socalled tea bags. In each apparatus, tea is inserted into a vertical feeder tube around which a web of paper material is formed into a tube. Doses of the tea are dropped into the tubular web. Synchronously with the deposition of each dose, the web is seated transversely to form compartments which each contain an individual dose. The seals are formed alternately between two pairs of heated sealing jaws which are arranged at right angles to one another. To assist in flattening the tubular web as R comes between the sealing jaws and thereby minimise the risk of creasing the web material at the seals, spreading devices are provided.

The spreading device disclosed in WO 95101907 has been found to work well. The device comprises respective pairs of spreader arms for the pairs of sealing jaws, the pairs of spreader arms also being arranged at right angles to one another. The upper ends of the arms are pivotally mounted within an annular space defined at the downstream end of the feeder tube with the arms protruding from that end. The pivot mountings each have a follower roller which is received in a continuous cam track. The cam track is defined by a collar which is rotatably mounted within the aforementioned annular space and has an internal ring gear which meshes with a pinion carried by a drive shaft. The drive shaft extends upwardly within the feeder tube and protrudes beyond the upstream end of the tube.

Rotation of the drive shaft causes the collar to rotate and results in pivotal movement of the spreader arms under the influence of the cam track. The pivotal movement of the arms is about a horizontal axis and causes their free ends to reciprocate along a curved path defined in a vertical plane which passes through the longitudinal axis of the feeder tube. At the innermost position of their respective paths, the ends of the arms are located adjacent the feeder tube axis whilst at the outermost 2 8 9 11 12 13 is 16 17 18 19 22 23 24 26 27 28 29 31 32 33 34 36 38 MB/3814-P position of the paths the ends of the arms are disposed radially outwardly of the tube circumference such that the arms point away from the tube axis. The movements of the spreader arms are synchronised with the sealing jaws so that the free ends of each pair of spreader arms are at their outermost positions and thereby flatten the tubular web just as the jaws of the respective pairs of sealing jaws close to form a seal.

The collar and the pivot mountings occupy a significant amount of space at the downstream end of the feeder tube thereby potentially restricting the flow of product to the bag being formed below. To improve operating speeds and for the packaging of product consisting of larger pieces of less densely packed material, for example crisps, it is desirable to reduce this flow restriction.

The spreader device of the apparatus disclosed in GB 2256415B comprises fingers carried on arms which extend upwardly through a vertical feeder tube. The arms are connected to a yoke disposed above the upstream end of the tube and the fingers are received in an annular space defined at the downstream end of the tube. The yoke is reciprocated causing the arms to be pushed upwardly and then downwardly in the lengthwise direction of the feeder tube. At the end of the downward stroke, the fingers protrude from the end of the feeder tube and the resilience of the material causes the fingers to pivot outwardly of the tube about a horizontal axis to assume a web spreading position. The pivotal movement of the fingers caused by the reciprocal movement of the yoke causes the free ends of the fingers to reciprocate along a curved path defined in a vertical plane which passes through the longitudinal axis of the feeder tube.

US 4589247 discloses an apparatus for manufacturing packaging for a flowable material. The type of pack formed by this apparatus is the socalled pillow pack. A web is formed into a tube around a vertical feeder tube and transverse seals are formed in the tubular web to define compartments for the flowable material. Doses of the flowable material are dropped through the feeder tube in synchronisation with the sealing operation so that each compartment contains a required amount of material. In order to prevent creasing during the forming of the transverse seals the apparatus is provided with a single pair of spreader or 'butterfly arms' which are arranged to pivot about a horizontal axis. These arms are operated by a pulling action from the top of the feeder tube by means of a bar or wire. The arrangement is such that the arms MB/3814-P 1 2 3 4 5 6 7 8 9 10 11 12 13 14 is 16 17 18 19 22 23 24 25 26 27 28 32 33 34 36 37 38 pivot between their open and closed positions. The arms pivot about a horizontal axis with their free ends reciprocating along a curved path which is defined in a vertical plane passing through the longitudinal axis of the feeder tube.

The invention provides apparatus for use in manufacturing packaging containing a flowable material, said apparatus comprising feeder tube means having a longitudinal axis and around which, in use, a tubular web is formed, at least one arm means for spreading said tubular web and comprising two arms which are mounted at diametrically opposed positions such that a free end of each arm projects beyond a downstream end of said feed tube means, and respective rotatably mounted drive shafts connected with said arms for causing rotation of said arms about respective axes of rotation which extend substantially parallel to said longitudinal ayis.

The invention also includes apparatus for use in manufacturing packaging containing a flowable material, said apparatus comprising feeder tube means having a longitudinal axis and around which, in use, a tubular web is formed, at least one arm means for spreading said tubular web and comprised of two arms which are mounted at diametrically opposed positions such that a free end of each said arm projects beyond a downstream end of said feeder tube means, and drive means for said arms, the arrangement being such that said drive means causes said free ends of said arms to move along respective curved paths defined in a plane which is transverse to said longitudinal axis.

The invention also includes apparatus for use in manufacturing packaging containing a flowable material, said apparatus comprising feeder tube means having a longitudinal axis and around which, in use, a tubular web is formed, at least one spreader means for spreading said tubular web beyond the tube, and means for cyclically moving said spreader means between a retracted and an outwardly-extending position by angular movement of the or at least one said spreader means about an axis substantially parallel to said longitudinal axis.

In order that the invention may be well understood, an embodiment thereof, which is given by way of example only, will now be described with reference to the drawings in which:

Figure 1 is a plan view of apparatus for use in manufacturing tetrahedral packaging containing a flowable material; Figure 2 is an enlargement of the central portion of Figure 1 4 1 2 3 4 7 11 12 13 14 16 17 19 20 21 22 23 26 27 28 31 32 33 36 37 38 MB/3814-P illustrating the movement of spreader arms of the apparatus; and Figure 3 is a section on line 111-111 in Figure 2.

Referring to Figures 1 to 3, an apparatus 10 for use in the manufacture of tetrahedral packages containing a flowable material will be described in connection with the manufacture of tetrahedral tea bags in the manner disclosed in W095101907, the content of which is incorporated herein by reference. However, it is to be understood that the spreader device incorporated in this apparatus is equally suitable for use in the manufacture of tetrahedral packages for any type of product (for example rice or snack foods such as crisps) and could readily be adapted for the manufacture of other forms of packaging which require the forming of transverse welds in a tubular web such as, for example, pillow packs.

The apparatus 10 comprises a vertically extending feeder tube 12 which has a longitudinal axis 13 (Figure 3). In use, a web of heat sealable paper material is fed along a transverse plane onto the feeder tube around which the web is formed into a tube. The edges of the tubular web are sealed together by heated sealing jaws (not shown) to form a seam extending in the lengthwise direction of the feeder tube. Such a process will be familiar to those skilled in the art of packaging and is fully described in WO 95101907, GB 2256415 and US 4589247.

A second tube 14 which has an outer diameter substantially the same as the inner diameter of the feeder tube is disposed internally of that tube so as to form a lining for it. The lining tube 14 has two lengthwise extending flat sides 15 (Figure 2) which are disposed at diametrically opposed positions. The flat sides co-operate with the inner surface of the feeder tube to define respective D-section passageways 16. The passageways 16 extend along the entire length of the feeder tube 12. The lining tube 14 projects above the upper end of the feeder tube and in use, doses of tea are dropped, or pumped, down the lining tube so as to fall into the tea bags being formed downstream of the tubes 12, 14.

Two pairs of spreader arms 20 are rotatably mounted at the lower ends of the tubes 12, 14. The arms 20 of each pair are mounted at diametrically opposed positions. Each arm has a lower, or free, end 20a and an upper end 20b. The arms are curved along their entire length.

There is a drive shaft 22 (Figure 3) for each spreader arm 20. The drive shafts 22 are rotatably mounted in respective bushes 24 disposed r 1 2 3 4 5 6 7 8 9 11 12 13 14 15 16 17 18 19 21 22 23 24 25 26 29 32 34 36 37 M13/3814P at the upper and lower ends of the passageways 16. The bushes 24 are mounted in collars 26 which are fitted into the ends of the passageways 16. The lower ends of the drive shafts project beyond the lower ends of the tubes 12, 14 and are connected to the upper ends 20b of the respective spreader arms via intermediate shafts 28.

The pairs of spreader arms are radiaily offset with respect to one another about the axis 13. The angle of the offset is 350. Thus, one drive shaft connected with one arm from each of the pairs of spreader arms can be received in each passageway. The drive shafts in each passageway 16 are aligned such that their respective axes of rotation both fie in a plane which is parallel to the plane of the adjacent flat side 15.

The upper ends of the drive shafts 22 project beyond the upper end of the feeder tube 12 and carry a relatively short extension shaft 30. Each extension shaft 30 has a spur gear or pinion 32 fixed to it.

Respective straight toothed racks 34 are mounted adjacent the upper ends of the passageways in engagement with the pairs of pinions 32. Each rack 34 is carried on a support arm 36. The support arms 36 are disposed perpendicular to the longitudinal axis 13 of the vertical feeder tube 12 and in parallel spaced apart relationship with the upstream end of the lining tube 14 positioned between them.

The support arms 36 are carried by two guide blocks 38 which permit planar sliding movement of the support arms. The guide blocks 38 are arranged in parallel spaced apart relationship about the longitudinal axis 13 of the feeder tube 12 and each has two through-bores 40 defined therein. The through-bores 40 are sized to receive the support arms 36 and are arranged in aligned pairs, one pair for each support arm.

Respective drive means 50 are provided for causing reciprocal movement of the support arms 36. The drive means are identical and therefore for ease of reference only one will be described.

The drive to a support arm 36 from the drive means 50 is provided by means of two pneumatic cylinders 52, 54 arranged back-to-back. The cylinder 52 is fixed to one end of a plate 56. The other end of the plate 56 has a bush 58 fitted to ft. The bush 58 is clamped to a guide rod 60 which protrudes from the adjacent guide block 38. The cylinder 54 is fixed to a plate 62, one end of which is connected to the adjacent support arm 36. A bush 64 is fitted to the opposite end of the plate 62 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 21 22 24 28 31 MB/3814-P and this bush is slidably mounted on the guide rod 60.

A bracket 68 extends from the mid-region of the back-to-back cylinders 52, 54 and carries at its distal end a bush 70 which is slidably mounted on a stop rod 72. The stop rod 72 has respective sleeves 76 fixed at each end. One sleeve 76 is slidably received in a through-bore in the plate 56 and the other is slidably received in a through-bore in the plate 62. The sleeves 76 each have a stop in the form of a disc 78 fitted at their outer ends and these discs each carry an annular rubber pad on their inboard faces to act as cushions for the respective plates 56, 62.

As indicated above, the drive means 50 are identical. In use, they operate synchronously so that the respective support arms are driven simultaneously at the same rate, but in the opposite direction.

In the condition shown in Figures 1 and 2, the cylinders 52, 54 both have their piston rods extended and consequently the racks 34 are at one end of their range of movement. The arms 20 are radially oriented on their respective drive-shafts 22 such that the diametrically opposed arms of one of the pairs of arms have their free ends 20a disposed at a radially outermost position with respect to the longitudinal axis 13 of the feeder tube whilst the free ends 20a of the arms of the other pair of diametrically opposed arms lie at their radially innermost positions: these radially outermost positions lie on a circumference 80 and the radially innermost positions lie on a circumference 82, which circumferences are indicated in Figure 2.

The pair of sealing arms having its free ends disposed on the circumference 80 is positioned to stretch the web to prevent creasing and at the same time, two sealing jaws (not shown) having their sealing faces disposed parallel to the diameter 84 delimited by the free ends 20a positioned on the circumference 80 will be in the process of coming together and forming a transverse seal in the web.

As the sealing jaws move apart, the respective piston rods of the cylinders 54 are caused to gradually retract thereby pulling the plates 62 away from the feeder tube 12. The movement of the respective plates 62 causes the support arms 36 to slide in opposite directions causing the racks 34 to be moved to the mid-point of their range of movement. The movement of the racks 34 causes simultaneous movement of the pairs of arms. The arms initially having their free ends 20a disposed on the circumference 80 rotate about the respective axes of their drive-shafts 22 causing those ends to move inwardly of the circumference 80 along a r 1 7 1 2 3 4 5 6 7 8 9 10 11 13 14 is 17 18 21 22 23 24 25 26 27 28 29 32 33 34 35 36 37 38 MB/3814-P curved path indicated by the dashed lines 90 (Figure 2). The arms initially having their free ends 20a disposed on the circumference 82 rotate likewise but in the opposite direction causing those free ends to move outwardly of the circumference 82 along a curved path indicated by the dashed lines 92 (Figure 2).

With the racks 34 at the mid-point of their travel, the free ends 20a of all four arms lie on a common diameter 94 (Figure 2) which is substantially the same as the inner diameter of the lining tube 14. Both sets of arms are thus effectively in neutral positions allowing the free passage of tea down the feeder tube 12 and into the bag below and of the tubular web over the tube 12.

The arms 20 are held in the neutral position for sufficient time to allow the required dosage of tea to be fed into the bag below and then the cylinders 52 are activated. As the respective piston rods of the cylinders 52 retract, the plates 62 are drawn further away from the feeder tube 12. As the plates 62 move away from the feeder tube, the respective bushes 64 move towards the bushes 58 until contact between the pairs of bushes is made. This marks the opposite end of the range of travel the racks 34.

In this condition, the positions of the pairs of spreader arms will have reversed so that the free ends 20a originally disposed on the circumference 80 will be disposed on the circumference 82 and vice versa. The arms now having their free ends 20a disposed on the circumference 80 stretch the web along a line (corresponding to the diameter 98 in Figure 2) which is at right angles to the diameter 84. This substantially coincides with the closure of a second set of sealing jaws (again not shown) which have their sealing faces disposed generally parallel to the diameter 98.

Movement of the spreader arms back to the position shown in Figures 1 and 2 is achieved by reversal of the above-described operation of the cylinders 52, 54: i.e. by extension of the pistons from their cylinders 52, 54 with a dwell period being provided whilst the spreader arms 20 are in the neutral position in order to permit tea to be fed into the bag below. As indicated in Figure 1, contact between the rubber discs carried by the discs 78 and the respective plates 52, 62 limits the extension of the pistons from the cylinders 52, 54.

Thus each of the pairs of spreader arms 20 can be reciprocated between respective positions in which their free ends lie on a 8 1 2 3 4 6 7 8 9 11 12 13 14 16 17 19 21 22 23 24 26 27 28 29 31 32 33 34 36 37 38 MB/3814-P circumference which is co-axial with and greater than the circumferential extent of the feeder tube 12 in order to stretch the web during formation of a transverse seal by means of the associated sealing jaws and positions in which their free ends are disposed directly below the feeder tube and adjacent its longitudinal axis in order to permit the sealing jaws associated with the other pair of spreader arms to close and form a seal.

It will be appreciated that as the pairs of spreader arms 20 rotate, their free ends 20a move along respective curved paths 90, 92 which are defined in a plane which is transverse to the longitudinal axis 13 of the feeder tube. In the embodiment the curved paths are planar and lie in a plane which is perpendicular to the longitudinal axis 13.

The apparatus disclosed in WO 95/01907, GB 2256415B and US 4589247 are socalled vertical, form, fill and sealing machines (VFFS). Although spreader devices according to the invention are particularly suitable for such apparatus, they may also be used on devices in which, for example, a horizontally aligned feeder tube is provided. It will be understood that only one pair of spreader arms is required in a spreader device for a VFFS machine, for example such as that disclosed in US 4589247, which has only one pair of sealing jaws.

It is to be understood that although the combination of a drive means comprising pneumatic cylinders and a rack and pinion arrangement for actuating the spreader arms is preferred for reasons of simplicity, the pinions could be driven by means of a reciprocating ring gear. As an alternative, the drive shafts could be driven by a system of belts and pulleys.

It will be appreciated that by arranging for the spreader arms to rotate about respective axes which are parallel to the longitudinal axis of the feeder tube, it is possible to reduce the restriction of the flow of product through the feed tube as compared with a device such as that shown in W095/01907.

It is emphasised that the application of the apparatus 10 to the manufacture of tetrahedral tea bags has been given by way of example only. It will therefore be appreciated that the apparatus can also be used in the manufacture of packages from a heat sealable plastics web or in applications where the seals are cold formed.

For the avoidance of any doubt, the word 'pair' is used herein to specify two like and associated parts but does not connote that those parts are identical.

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Claims

1. Apparatus for use in manufacturing packaging containing a flowable material, said apparatus comprising feeder tube means having a longitudinal axis and around which, in use, a tubular web is formed, at least one arm means for spreading said tubular web and comprising two arms which are mounted at diametrically opposed positions such that a free end of each arm projects beyond a downstream end of said feeder tube means, and respective rotatably mounted drive shafts connected with said arms for causing rotation of said arms about respective axes of rotation which extend substantially parallel to said longitudinal axis.

2. Apparatus as claimed in claim 1, wherein each said arm curves for at least a portion of the length thereof.

3. Apparatus as claimed in claim 2, wherein each said arm is curved along its entire length.

4. Apparatus as claimed in claim 1, 2 or 3, wherein said rotation of the arms causes said free ends to move along respective curved paths which are defined in a plane which is transverse to said longitudinal axis.

5. Apparatus as claimed in any one of the preceding claims, comprising drive means for said drive shafts, said drive means being arranged to cause reciprocating rotational movement of said drive shafts.

6. Apparatus as claimed in claim 5, wherein said drive means comprises respective spur gears connected to said drive shafts and gear means for driving said spur gears.

7. Apparatus as claimed in claim 6, wherein said gear means comprises a plurality of straight toothed racks.

8. Apparatus as claimed in claim 7, comprising two said arm means and two said racks, the arrangement being such that each rack drives two of said spur gears so as to cause movement of two said arms, one from each of said arm means.

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9. Apparatus as claimed in claim 7 or 8, wherein said drive means comprises pneumatic cylinder means arranged to cause reciprocating movement of said racks.

10. Apparatus as claimed in any one of claims 5 to 9, wherein said means is arranged to hold said arms in a neutral position for a predetermined period.

11. Apparatus as claimed in claim 10, wherein said neutral position is substantially at the mid-point of said reciprocating movement.

12. Apparatus as claimed in claim 10 or 11, wherein said arms are arranged such that in said neutral position, the radial distance between said free ends and said longitudinal axis is substantially the same as the radial extent of said feeder tube means.

13. Apparatus as claimed in claim 10, 11 or 12 when dependent on claim 9, wherein said pneumatic cylinder means comprises respective pairs of pneumatic cylinders for said racks.

14. Apparatus as claimed in claim 13, wherein the cylinders of each said pair are disposed back-to-back such that the pistons theleof extend in opposed directions.

15. Apparatus as claimed in claim 13 or 14, wherein said neutral position is defined when the piston of one cylinder of each pair is extended and the piston of the other cylinder of the pair is retracted.

16. Apparatus as claimed in any one of the preceding claims, wherein said feeder tube means comprises an outer tube around which said tubular web is formed and an inner tube through which said flowable material is fed, said outer tube and said inner tube defining a plurality of lengthwise extending passages for said drive shafts.

17. Apparatus as claimed in claim 16, wherein said outer tube and said inner tube define two said passages and said inner tube has two diametrically opposed flat sides such that said passages each have a substantially D-shaped transverse cross-section.

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18. Apparatus as claimed in any one of the preceding claims, wherein said feeder tube means extends vertically.

19. Apparatus for use in manufacturing packaging containing a flowable material, said apparatus comprising feeder tube means having a longitudinal axis and around which, in use, a tubular web is formed, at least one arm means for spreading said tubular web and comprised of two arms which are mounted at diametrically opposed positions such that a free end of each said arm projects beyond a downstream end of said feeder tube means, and drive means for said arms, the arrangement being such that said drive means causes said free ends of said arms to move along respective curved paths defined in a plane which is transverse to said longitudinal axis.

20. Apparatus as claimed in claim 19, wherein said plane is perpendicular to said longitudinal axis.

21. Apparatus as claimed in claim 19 or 20, wherein said arms are curved in the lengthwise direction thereof.

22. Apparatus as claimed in claim 19, 20 or 21, wherein said drive means comprises respective drive shafts for said arms.

23. Apparatus as eJaimed in claim 22, wherein said drive shafts each have an axis of rotation which axis extends substantially parallel to said longitudinal axis.

24. Apparatus as claimed in claim 23, wherein each said arm rotates about the axis of its drive shaft.

25. Apparatus as claimed in claim 22, 23 or 24, wherein said drive shafts are driven so as to cause reciprocating rotational movement of said arms.

26. Apparatus as claimed in claim 25, wherein each said drive shaft is connected with a spur gear and comprising a plurality of straight toothed rack means for engaging said spur gears and causing reciprocal rotation thereof.

12 MB/3814-P 1

27. A vertical, form, fill and seal machine comprising apparatus as claimed in any one of the preceding claims.

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28. A machine as claimed in claim 27, including a first sealing means comprising two opposed sealing jaws, a second sealing means comprising two opposed sealing jaws mounted mutually transversely to said first sealing means, a first said arm means associated with said first sealing means and a second said arm means associated with said second sealing means, said sealing means and said arm means being arranged for the manufacture of tetrahedral packages.

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29. Apparatus for use in manufacturing packaging containing a flowable material, said apparatus comprising feeder tube means having a longitudinal axis and around which, in use, a tubular web is formed, at least one spreader means for spreading said tubular web beyond the tube, and means for cyclically moving said spreader means between a retracted and an outwardly-extending position by angular movement of the or at least one said spreader means about an axis substantially parallel to said longitudinal axis.

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30. Apparatus for use in manufacturing packaging containing a flowable material substantially as hereinbefore described with reference to the drawings.

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