NZ541001A - A vacuum packing machine - Google Patents

Abstract

A vacuum packing machine includes a rotatable platform (11). A plurality of individual vacuum packing chambers defined by hoods (23) are carried by the platform. A central hub (15) is connectable to a vacuum source. The hub has a vacuum distribution head (31) rotatable about the hub. The distribution head has a plurality of vacuum supply chambers each vacuum supply chamber being coupled via a vacuum port (44) to one of the vacuum packing chambers. A plurality of conduits extend within the hub, each conduit being coupled to a respective vacuum supply chamber. The conduits are coupled via a valve to the vacuum source.

Description

No: Date: 541001 30 June 2005 NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION A VACUUM PACKING MACHINE WE, MERCER TECHNOLOGIES LIMITED a New Zealand company of 7 Corban Avenue, Henderson, Auckland, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- SPEC 1837 IPONZ -3 JUL 2006 JUNE 2006 t 1 TITLE OF THE INVENTION A Vacuum Packing Machine BACKGROUND OF THE INVENTION This invention relates to a vacuum packing machine.

Machines for the vacuum packing of products, more particularly foodstuffs, are well known. One such machine that has been very successful is the BETAVAC® produced by Mercer Stainless Limited. This machine incorporates a lid which, when in the closed position, forms 10 a chamber in which one or more bags of product (the number depending on the size and configuration of the machine) can be placed via a conveyor. A vacuum is then drawn in the chamber following which the bag(s) is/are sealed. The bag(s) can then be removed by the conveyor once the lid has been moved to an open position. The BETAVAC® was designed for packing large uniformly shaped product such as 20kg blocks of cheese.

The rate at which product can be vacuum packed is dependent on the cycle time of the vacuum packing machine. Hence for higher throughputs it has been necessary to run more than one vacuum packaging machine. Not only does this give rise to increased cost of capital plant in the vacuum packing machine but also in ancillary equipment such as 20 conveyors, weighing equipment, bagging apparatus etc.

SUMMARY OF THE INVENTION Consequently, there is a need for a vacuum packaging machine that has the advantages of a 25 chamber vacuum packaging machine but which provides a faster throughput, and ability to pack irregular shaped product. An object of the present invention is thus to provide such a machine.

Broadly according to one aspect of the present invention there is provided a vacuum packing 30 machine including a rotatable platform, a plurality of individual vacuum packing chambers IPONZ -3 JUL2006 T 2 carried by the platform, a hub connectable to a vacuum source, the hub having a vacuum distribution head rotatable thereabout, the distribution head having a plurality of vacuum supply chambers, each vacuum supply chamber being coupled to a respective one of the vacuum packing chambers and a plurality of conduit means extending within the hub, each 5 conduit means being coupled to a respective one of the vacuum supply chambers, said conduit means being coupled via a valve means to the vacuum source.

In a preferred form of the invention the hub includes bearing means via which the platform can be rotatably supported by the hub.

In a preferred form of the invention a custom engineered electrical commutator carried by bearing means on the hub and rotatable with the platform, for timing sequentially the electrical supply to respective seal bar arrangements of the sealing means of the vacuum packing chambers.

In a preferred form of the invention an air distribution head is mounted with the hub and is coupled through a conduit extending within the hub to a pressurised air source.

Preferably the air distribution head includes means for timing the supply of pressurised air 20 to air operated linear actuators associated with the respective vacuum packing chambers.

In a preferred form of the invention at least one linear actuator is operatively coupled with a hood which with the platform forms a vacuum packing chamber and is movable from open and closed positions by the linear actuator(s).

In a preferred form of the invention the vacuum packing chamber includes bag sealing means the bag sealing means being operatively coupled to one or more of said air operated linear actuators.

BRIEF DESCRIPTION OF THE DRAWINGS In the following more detailed description of the invention according to its preferred form reference will be made to the accompanying drawings in which:- Figure 1 is a perspective view of the packing machine, Figure 2 is an underside perspective view, Figure 3 is a top plan view, Figure 4 is a cross-section elevation view taken on line A-A of Figure 3, Figure 5 is perspective view of the central hub of the packaging machine as shown in Figures 1-4, Figure 6 is an elevation view of the central hub, Figure 7 is an enlarged cross-sectional view taken on line B-B of Figure 6, Figure 8 is a top plan view of the central hub, Figure 9 is a bottom plan view of the central hub, Figure 10 is an exploded view of the central hub, Figure 11 is an exploded view of the atrium assembly, 4 Figure 12 is an exploded view of a pneumatic valve assembly suitable for use with the invention.

Figure 13 is an exploded view of a second embodiment of pneumatic valve 5 assembly, Figure 14 is a view similar to Figure 4 but showing the pneumatic valve assembly of Figure 13, and Figure 15 is a view of detail D of Figure 14.

DETAILED DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION The vacuum packing machine as shown in Figures 1-4 consists of four packing chambers 15 mounted on a circular turntable. This is by way of example. Other designs can be readily achievable according to the present invention where there are more than four packing chambers.

The packing machine 10 includes a circular turntable 11 that is mounted for rotation on a 20 support frame 12. This support frame 12 carries ancillary equipment such as a motor 13, the output shaft of which has a toothed wheel, which enables drive via a chain (not shown) to be transferred to a toothed drive sprocket 14 attached to a central hub 1 5.

The drive sprocket 14 is fixed to an electrical commutator 16 which is in contact with an 25 electrical brush assembly 17. The drive sprocket 14 is carried by a table mount hub 18 that has a flange 19 to which the table 11 is fastened.

Fixed to and supported by suitable mounting 20 carried by the support frame 12 is a shaft comprising a lower half assembly 21 and an upper half assembly 22 as hereinafter will be described. As will also hereinafter be described this central hub assembly provides the means for transferring vacuum, compressed air and electrical current to the rotating turntable during use of the machine.

In accordance with known vacuum chamber packing each packing station on the turntable 11 includes a hood 23 that can be lowered onto the turntable to form a packing chamber. Thus vacuum can be applied to bagged product located in the chamber to carry out vacuum packing within the chamber in a conventional manner.

Each hood 23 is mounted by a hinge 24 at the rear thereof adjacent the central hub 1 5. The hood seals onto the turntable using a rubber seal attached to a seal flange extending about the peripheral edge of the hood 23. While a hinged hood is shown, the hood could be mounted and be operable to raise and lower straight up and down relative to the platform.

The hood 23 is raised and lowered about hinge 24 using a pneumatic cylinder 26 (see Figures 2 and 4) mounted to the underside of the turntable 11. The piston rod of the pneumatic cylinder 26 is connected via a crank 27 to the rear of the hood whereby the hood 23 can be raised and lowered. Thus, as the piston rod retracts it causes the hood 23 to raise while extension of the piston rod moves the hood to the closed position.

The turntable (which is preferably formed from stainless steel plate) also provides a base for seal bars 28 and associated seal bar pneumatic cylinders 29. The seal bar assembly 28 consists of sealing element bar with heating element. This is in accordance with known technology as is an anvil assembly mounted in the hood 23. Accordingly a detailed description of the seal bars 28 will not be required for the purposes of describing the present invention.

In the preferred form of the invention the sealing bar assembly 28 is raised and lowered by two pneumatic cylinders 29 mounted under the turntable 11. The mouth of the bag, in 6 which product is located, is clamped between the sealing bar and the anvil. The sealing bar is designed to be a quick-release type, and has the two elements thereof sandwiched between layers of heat resistant Teflon® tape and kept under tension by tensioners. During sealing, the sealing bar is raised until it presses the bag against the spring-loaded anvil.

The anvil assembly is mounted inside the hood 23 and consists of the aforementioned spring-loaded anvil bar with anvil rubber, trimming knife and piercing blade assembly. The anvil assembly is attached to four bosses (welded into the hood 23) by means of four knurled thumbscrews for quick removal.

A piercing knife assembly (not shown) moves down with the hood 23 as it closes and consists of a spring-loaded clamp bar which compresses the bag mouth against a guide rail and piercing knives puncture the bag as the hood continues to close to allow air in the bag to escape during the vacuum cycle. During sealing the seal bar presses against the anvil 15 causing it to retract. As the anvil retracts further a fixed trimming knife cuts through the bag.

The electrical commutator 16 is used to distribute electrical current to each sealing bar assembly 28 in turn as it enters the "sealing sector" of the turntable's rotation. As previously 20 described the commutator assembly 16 is attached to the turntable hub 18 and, therefore, rotates with the turntable 11.

The central hub 15 preferably includes at its upper end a pneumatic rotary valve 30. As will hereinafter be described the rotary valve 30 distributes compressed air supply (fed up the 25 centre of the shaft 21, 22) to the pneumatic actuators 26 and 29, in sequence. As herein described this programmed sequence can be achieved by the length and position of slots in a port plate of a rotary valve 30 of one embodiment as herein described. 7 Mounted on and rotatable about the central shaft 21, 22 is a vacuum atrium 31. The function of the atrium 31 is to distribute vacuum from the central shaft 21, 22 to each of the four packing chambers. Flexible vacuum hoses (not shown) connect each packing chamber to a corresponding vacuum atrium chamber as will hereinafter become apparent.

In the preferred form of the invention the main drive systems consist of a VSD- controlled motor and gearbox assembly 13. In the illustrated form of the invention and by way of example only, the motor and gearbox has a 28 RPM output speed at 50Hz. In such an arrangement the turntable has a chain drive using a 6:1 reduction ration. The turntable 10 speed (and therefore the production rate) can be selected on an operator interface screen. The VSD controls the speed of the main drive.

An unloading arm (not shown) is, in the preferred form of the invention, driven by a chain drive with a 3:1 reduction off the same gearbox output shaft. In this way the unloading arm 15 position is synchronised to the position of the turntable.

While the arm is not illustrated in the accompanying drawings a shaft 32 on which the unloading arm is mounted is shown. This shaft 32 is journalled in bearings 32a mounted by spaced apart mounting plates 33 carried by the support frame 12. The chain drive from the 20 output shaft of the motor M engages with a drive sprocket 34 mounted on the shaft 32. This drive sprocket 34 is located between the spaced apart plates 33.

Accordingly, in the aforementioned synchronised manner the unloading arm can remove (e.g. in a sweeping action across the turntable) a vacuum packed product from the turntable 25 11 onto an adjacent conveyor so that it can by conveyed away from the packing machine 10.

In addition to the support frame 12 supporting the central hub 15 it also supports other ancillary equipment such as an electrical cabinet, pneumatics cabinet and a vacuum/vent manifold. In the electrical cabinet will be housed a programmable logic controller (PLC) and 8 the variable speed drive (VSD), sealing transformer and other electrical components required to control the machine's operations.

The pneumatics cabinet (not shown) will in a preferred for of the invention be a Himel 5 polycarbonate cabinet which houses pneumatic control valves which operate vacuum and vent valves.

The vacuum/vent manifold (not shown) will in a preferred form of the invention be a vacuum vessel where vacuum is switched using 2" "Norgen" compact valves to each of the vacuum 10 ducts (hereinafter described) in the central column. One vacuum valve and one vent valve is required per packing chamber to control cross-venting vacuum and venting functions.

Cross venting from a chamber that has completed its sealing cycle into a chamber that has just closed to commence a vacuum cycle, will save vacuum energy costs. Cross venting is 15 carried out by opening the vacuum valves of the two chambers so that the two chambers are linked to each other thereby equalising the pressure. Each chamber vents via its vent valve into a common vent manifold to which an air filter/silencer is fitted. Air is drawn through the filter and into the chamber to return the chamber to ambient pressure.

As a stand-alone unit or supported from the support frame 12 there will be an operator interface screen. This will provide the foliowing:- (a) A display of current operating parameters such as turntable speed or sealing time, and the facility to change these. (b) An alarm message in the event of a fault, assisting the operator to diagnose the fault. 9 (c) A Production Information screen for parameters such as number of bags packed and running hours.

To further describe the invention reference will now be made to the sequence of operation of 5 the machine. This description is facilitated by considering the turntable as being divided into four logical sectors (not necessarily all equal), which are fixed relative to the machine. The sectors are loading, vacuum, sealing and unloading. Each chamber passes, as the turntable rotates, through each of these sectors in sequence to thereby complete a packing cycle. At any point in time each of the chambers can be in a separate sector.

At the loading station an empty raised hood 23 will move toward the operator. The operator places a bag with product under the hood with the mouth of the bag over the seal bar guide rails. As an alternative to this manual operation an auto-loader can be installed for automatic loading of the bagged product. The hood 23 closes down fully onto the surface of 15 the turntable to form the vacuum chamber at the end of the loading sector.

As the chamber moves into the closed position, the spring-loaded clamp bar mounted on the anvil assembly in the hood presses the bag mouth against the seal bar guide rail. As previously described, piercing knives pierce the clamp bag mouth to allow venting of air 20 from the bag during the vacuum cycle.

When the hood is closed the vacuum in the chamber that has just completed its packing cycle is cross-vented (as previously described) into the chamber that has just closed. The vacuum valve of the chamber opens and the main vacuum supply rapidly increases the 25 vacuum from the cross-vented level down to a few mbar.

After the required vacuum level has been reached the sealing operation commences. In this sector the pneumatic actuators 29 of the seal bar assembly 28 are actuated by the pneumatic rotary valve 30. The seal bar moves up, compressing the bar against the anvil.

An impulse seal electric current to the sealing element is switched on by a contactor for between 1 and 2 seconds, whilst the hood incorporating the seal bar arrangement is in the respective sealing sector of the commutator depending on the predetermined packaging material.

As the seal bar continues to move upward the trimming knife (which is fixed to the top of the hood) cuts through the bag, trimming off the excess. The electric current to the sealing element is then switched off and this seal bar remains clamped to the anvil to allow the seal to cool. The vacuum in the chamber is then cross-vented to the chamber that is next 10 starting the vacuum operation. The pressure in the chamber is equalised to atmosphere by opening the vent valve of the chamber.

The unloading operation can now commence. Providing that there is no vacuum in the chamber, the pneumatic rotary valve 30 causes operation of the chamber lift cylinder 26 to 15 occur thereby raising the hood 23. As the open chamber moves to the unloading station the unloading arm sweeps the sealed product off the table and onto a conveyor. The open chamber then moves around to the loading station where the packing cycle recommences.

As previously described the central hub 15 houses supply services such as vacuum, 20 compressed air and electrical power through a stationery column to the rotating table 11. The central shaft 21, 22 acts as the housing for the individual vacuum supply conduits and a compressed air supply conduit. The pneumatic rotary valve 30 distributes the compressed air supply to the pneumatic actuators 26 and 29 in sequence as programmed by the length and position of slots in the port plate (as hereinafter described).

The shaft upper half assembly 22 comprises a cylindrical section 35 closed at one end by a wall 36. Spaced at different positions along the length of the chamber 35 and at different spatial locations are a plurality of ports 37. With a four-chamber arrangement as described herein the ports 37 are located at 90° apart. 11 Vacuum supply conduits 38 extend through the cylindrical portion 35 each conduit 38 being coupled to a respective one of the ports 37. Thus in Figure 7 the left hand conduit 38 extends to and is connected to the lowermost port 37 whereas the right hand conduit 38 is 5 longer and extends to and is coupled to the port 37 which is 180" away from the position of the first mentioned port 37.

These conduits 38 extend through an alignment bush 39 to extend through the shaft lower half assembly 21 to a manifold 40. This manifold is coupled to the vacuum valves and 10 vacuum supply.

Each port 37 opens into a separate section of the atrium assembly 31. The atrium assembly 31 is made up of individual annular sections 41, which slide onto the upper shaft assembly 22. Each annular section 41 is aligned with a port 37. These individual sections 41 are 15 flanged with the adjacent flanges of adjacent sections 41 bolted together.

Referring to Figures 5-7 it will be seen that the parts that make up the atrium assembly 31 are a bottom bearing housing 42 with associated bearing 42a and seal 43b, the atrium segments 41 and a top bearing housing 43 with associated bearing 43a and seal 43b. In the 20 preferred form of the invention each of the atrium segments 41 have a shaft seal 41a with backing O-ring 41b for sealing between adjacent atrium segments. Each atrium segment 41 also has a sized vacuum port 44 for connection of the hose (not shown) from the associated packing chamber.

The atrium assembly 31 thus rotates with the turntable 11 (the assembly rotating about the upper shaft assembly 22) and therefore provides the separate vacuum supply to the vacuum chambers.

Figure 12 shows one embodiment of a pneumatic rotary valve 30 suitable for use with the invention. The valve 30 consists of four main components namely a valve base 50, a pneumatic port plate 51, an outlet plate 52 and a stub shaft 57.

The valve base 50 effectively acts as a housing into the open top of which the port plate 51 is engaged. O-ring seals 53 fit into grooves 53a in the peripheral surface of the port plate 51 and create a seal between the peripheral surface of the port plate 51 and the internal wall surface of the valve base 50.

The valve base 50 incorporates four drive pins 54 that engage into correspondingly spaced bores (not shown) in the underside of the port plate 51. The port plate 51 is thus fixed in angular position relative to the valve base 50.

Extending through the drive pins 54 are cap bolts 55. These extend through the underside of the valve base 50 to pass through openings 56 in the flange of a stub shaft 57. The threaded ends of the bolts 55 engage in threaded openings 36a in the end plate 36. An O-ring 58 provides a seal between the valve base 50 and the stub shaft 57.

By virtue of the aforementioned construction the pneumatic port plate 51 is attached to the main shaft 21, 22 and remains stationary relative to the turntable 11.

The outlet plate 52 is fastened to the stub shaft 57 by a bolt 59 thrust washer 60 and thrust bearing 61. Projecting arms 62 bolted to the upper face of the outlet plate 52 enable the outlet plate 52 to be connected to the turntable 11 so that the outlet plate 52 rotates with the turntable.

Extending through the outlet plate 52 is four sets of ports 64. There are three ports 64 in each set each being connected via flexible conduits (not shown) to the respective pneumatic 13 cylinders 26 and 29 of a chamber. Thus for the packing machine as described herein there are four sets of ports 64, each set for a respective vacuum chamber.

Machined in the upper face of the port plate 52 is a series of semicircular slot segments 63. 5 The outlet plate 52 is attached to the top of the port plate 51 via the central bolt 59 so as to seal off the slots 63 in the port plates 51. As the turntable rotates the outlet plate 52 the ports 64 track with the slot segments 63 in the port plate 51. The slot segments 63 form "active" and "exhaust" segments, the latter being vented to an exhaust port 65 in the side of the valve base 50. The "active" and "exhaust" slot segments 63 are isolated from each other.

The port plate 51 channels compressed air into "active" circular slot segment 63. The start and end points of the compressed air "active" slot segment will determine at which angular position compressed air will pass through the corresponding port 64 to energise a pneumatic device 26 or 29. Alongside the "active" slot is an "exhaust" slot to provide a 15 return path for the return air from the pneumatic device.

Thus, the rotary valve 30 distributes compressed air supply fed up the centre of the shaft 21, 22 in conduit 66 to pneumatic actuators 26, 29 in sequence as programmed by the length and position of the slots 63 in the port plate 51. Consequently, a simple mechanical arrangement is used for the supply and timing of supply of compressed air to the pneumatic actuators.

It will be appreciated by those skilled in the art that other means of timing supply of compressed air to the pneumatic actuator can be used. A second embodiment is thus shown 25 in Figures 13 to 1 5. The component parts are shown more particularly in Figure 13.

This second embodiment of rotary pneumatic valve assembly includes a housing 71 which has a floor 72 with openings 73. The housing 71 is mounted to the top bearing housing 43 via fasteners 73a (see Figure 15) extending through openings 73. The floor 72 includes an 14 opening 72a which engages over the upper end of the cylindrical section 35 so that the cylindrical section 35 terminates within the confines of the housing 71.

A spigot 74 has a base 75 which is fastened to the external surface of the wall 36. the 5 spigot 74 therefore projects upwardly and is coaxial with conduit 66.

The upper or distal end 76 of the spigot 74 is of reduced diameter (see Figure 1 3). This reduced diameter portion 76 engages in a sleeve or boss 77 of an inner cam plate 78 and through a boss or sleeve 79 in an outer cam plate 80. This can be seen more clearly in 10 Figure 1 5.

As is also evident from Figure 15 the sleeve or boss 79 of the outer cam plate 80 engages over the sleeve or boss 77 of inner cam plate 78. A retaining nut 81 is able to be threaded on the end of the sleeve 77 which projects beyond the end of sleeve 79 so as to fix the two 15 cam plates 78 and 80 together. The distal end of the reduce diameter portion 76 of the spigot 74 extends beyond the nut 81 and onto this is threaded a nut 82 which engages with the end of the sleeve 77 to thereby fasten the inner cam plate 78 onto the spigot 74. Accordingly, the cam plate 78 and 80 are fixed to the spigot 74 which is in turn fixed to the non-rotatable column 22/35. The housing 71, however, is able to rotate by virtue of its 20 fixing to the top bearing housing 43.

Mounted within the housing 71 are pairs of roller trip valves 83 and 84. As can be seen from Figure 13 there are four pairs of trip valves 83 and 84 which are coupled by fasteners 85 which are additionally engaged through elongate slots 86 in the wall of housing 71. The 25 use of the elongate slots 86 enable the position of the trip valves 83/84 in the housing to be readily adjusted relative to the cam plates 78 and 80.

The rollers 87 of the trip valves 83 and 84 engage with profiled cam faces 88 and 89 of the inner 78 and outer 80 cam plates.

It will be appreciated by those skilled in the art that the roller trip valves 83 and 84 are plumbed to the compressed air supply feed up the centre of the shaft 21, 22 in conduit 66 and to the pneumatic actuators 26, 29. Thus the rotary valve 70 distributes compressed air 5 supply to pneumatic actuators 26, 29 in sequence as programmed by the length, position and profile of the cam surfaces 88 and 89 of the cam plates 78 and 80. Consequently, this arrangement provides for supply and timing of supply of compressed air to the pneumatic actuators.

The packing machine according to the present invention is open to modification as will be apparent to those skilled in the art. For example, while the packing machine is described herein as a vacuum packing machine it could equally incorporate gas flushing. This can be achieved by providing two atrium sections on the central hub, one functioning for vacuum supply and the other for supply of gas to the packing chamber. 16

Claims (18)

CLAIMS:-

1. A vacuum packing machine including a rotatable platform, a plurality of individual vacuum packing chambers carried by the platform, a hub connectable to a vacuum 5 source, the hub having a vacuum distribution head rotatable thereabout, the distribution head having a plurality of vacuum supply chambers, each vacuum supply chamber being coupled to a respective one of the vacuum packing chambers and a plurality of conduit means extending within the hub, each conduit means being coupled to a respective one of the vacuum supply chambers, said conduit means being coupled via a valve means to 10 the vacuum source.

2. The vacuum packing machine as claimed in claim 1 wherein the hub includes bearing means via which the platform can be rotatably supported by the hub. 15

3. The vacuum packing machine as claimed in 1 or 2 wherein an air distribution head is mounted with the hub and is coupled through a conduit extending within the hub to a pressurised air source.

4. The vacuum packing machine as claimed in claim 3 wherein the air distribution head 20 includes means for timing the supply of pressurised air to air-operated linear actuators associated with the respective vacuum packing chambers.

5. The vacuum packing machine as claimed in claim 4 wherein at least one linear actuator is operatively coupled with a hood which, with the platform, forms a vacuum packing 25 chamber and is movable from open and closed positions by the linear actuator(s).

6. The vacuum packing machine as claimed in claim 4 or 5 wherein each vacuum packing chamber includes bag sealing means, the bag sealing means being operatively coupled to one or more of said air operated linear actuators. 17

7. The vacuum packing machine as claimed in claim 6 wherein an electrical commutator is carried by bearing means on the hub and rotatable with the platform for timing/sequential electrical supply to respective seal bar arrangements of the bag 5 sealing means of the vacuum packing chambers.

8. The vacuum packing machine as claimed in claim 5 wherein each hood is pivotally coupled to the platform and a linear actuator is operatively connected to the hood to pivotally raise and lower the hood. 10

9. The vacuum packing machine as claimed in claim 5 wherein each hood is mounted to be movable between a position sealingly engaged on the platform and a position raised above the platform, one or more of said linear actuators being operatively coupled to the hood to effect raising and lowering of the hood between said positions. 15

10. The vacuum packing machine as claimed in any one of the preceding claims further including cross venting means for linking a vacuum packing chamber (first chamber) that has completed a sealing cycle to a vacuum packing chamber (second chamber) to next carry out a packing cycle to vent vacuum of the first chamber into the second chamber. 20

11. The vacuum packing machine as claimed in claim 10 wherein the cross venting means includes a vent manifold coupled via vent valves of the first and second chambers.

12. The vacuum packing machine as claimed in any one of the preceding claims wherein the 25 vacuum distribution head includes a plurality of annular sections mounted on the hub and coupled together such that relative movement between the hub and annular sections can occur, each annular section defining a said vacuum supply chamber into which opens a part in the hub, the part being coupled to a said conduit means. 18

13. The vacuum packing machine as claimed in claim 13 wherein each of the annular sections communicating with a post includes vacuum part connected by a conduit to a packing chamber. 5

14. The vacuum packing machine as claimed in claim 12 or 13 wherein each conduit means within the hub is a tubular element which extends to a manifold coupled via vacuum control valves to the vacuum source.

15. The vacuum packing machine as discussed in claims 12, 13 or 14 wherein the hub is a 10 hollow shaft on which is rotatably engaged a mount hub coupled to the platform and to a drive transfer means.

16. The vacuum packing machine as claimed in claim 15 wherein the mount hub is fixedly mounted to a support frame to which a drive motor is mounted and drivingly coupled to 15 the platform via the drive means.

17. The vacuum packing machine as claimed in any one of the preceding claims further including an unloading arm mounted for synchronised by control means for movement across the platform when a packing chamber is in an open position at completion of a 20 vacuum packing cycle.

18. A vacuum packing machine as claimed in claim 1 substantially as herein described with reference to the accompanying drawings. IPONZ