WO2003026969A1

WO2003026969A1 - Packaging of particulate materials

Info

Publication number: WO2003026969A1
Application number: PCT/NZ2002/000191
Authority: WO
Inventors: David Aucamp; Scott Edward Leaning; Colin Brian Buckley
Original assignee: Xero Ltd
Current assignee: Xero Ltd
Priority date: 2001-09-25
Filing date: 2002-09-24
Publication date: 2003-04-03
Anticipated expiration: 2004-03-25

Abstract

A packaging machine for the controlled packing of particulate material into gabs has an openable vaccum chamber (2), a vacuum pipe (11) connected to the chamber and to a vacuum source, means for delivering a bag (9) to adapter head (4) within the vacuum chamber (2), means (8) for clamping the bag (9) to the adapter head (4) so that the interior of the bag (9) is isolated from the rest of the chamber (2), the adapter head (4) having at least one fill pipe and at least one vent pipe (6). A weigh hopper (14) is positioned above the adapter head (4) and connectable to the fill pipe by means of collar (18) and isolating valves (16) and (17). In operation a bag (9) is clamped to the adapter head (4) by complementary clamps (8), the chamber is closed and vacuum is drawn on the chamber, at the same time the pressure within the bag (9) is controlled to keep a desired relative pressure with respect to the chamber (2). The weigh hopper (14) containing a pre-determined amount of powder is connected to the fill pipe, the valves (16) and(17) are opened and powder is pulled into the bag 8)9 by gravity and optionally the pressure differential between the atmospheric pressure in the hopper (14) and the vacuum in the bag (9=. Valves 16) and (17) are closed. Any entrained air in the bag (9) is removed by suction via the vent pipe (6). The bag (9) is sealed within the vacuum chamber (2). The chamber (2) can be opened and the bag (9) expelled.

Description

Packaging of Particulate Materials

TECHNICAL FIELD OF THE INVENTION

This invention relates to the packaging of particulate materials into a flexible container. It has particular application to the packaging of powders or granules of food grade material or materials of a sensitive or hazardous nature, or materials which have traditionally been difficult to package.

BACKGROUND

Particulate materials often present problems during handling processes. Typically they may need to be aerated to stimulate flow, or tend to naturally aerate when flowing, and the lighter weight particles particularly, become airborne and difficult to contain. Sites where particulate materials are handled are often completely shrouded in dust released during handling operations. The packaging of this type of material is therefore particularly difficult, as one is attempting to contain a mass of the material into a confined space.

Some particulate materials are packaged into rigid containers because of these handling difficulties. However rigid containers are often more expensive, and flexible containers such as bags, sacks, pouches can reduce cost, and improve handling characteristics.

In prior art packaging arrangements, particulate materials like cement, dairy products such as milk powder, plastics products such as vinyl resin beads, are filled into bags from gravity feed hoppers, in an open factory environment, resulting in poorly compacted bags and a great deal of contamination from dust and particulate material in the factory and surrounding environment.

Many particulate materials entrain a large volume of air or gases when packaged, which increases the packaged volume, causing increased shipping and storage costs. Dust which settles on the outside of the bag may also lead to sealing problems when the bags are subsequently heat-sealed. Further handling problems may result in that the dust may reduce friction between stacked bags or contaminate workers or other equipment.

Contamination can work in two directions. In some cases it is important to prevent the particulate material from contaminating people or equipment in the surrounding environment, but in other cases it is important to prevent contaminants from the surrounding environment entering the particulate material. And in some cases, like the handling of pharmaceutical products, it is important to prevent contamination in both directions at the same time.

The Occupational Safety and Health issues when packaging materials which may be harmful to ones health have often been inadequately addressed by simply providing protective clothing and breathing apparatus. But if the material has contaminated the working environment there remains the possibility that workers can still be contaminated by not always wearing the often uncomfortable protective equipment, or being contaminated in a secondary way when removing protective equipment, or from touching a contaminated surface or breathing contaminated air when protective equipment has been removed. Preventing the escape of the particulate material in the first instance would provide a more robust safety approach.

Some particulate materials like wood dust or flour can produce an explosive mixture when airborne in high concentrations. For this type of material it is therefore particularly important to reduce the escape of dust particles during packaging.

Another problem with prior art bag filling machines is that a particulate material filled under atmospheric pressure will entrap a considerable amount of air witiiin the bag. This tends to increase the packaged volume, and to fluidise the material within the bag, allowing the bag to slump, or to move, when stored on a pallet. Typically 25kg bags of food grade powders such as milk powder are stored one on top of the other on pallets, and there is a considerable risk of movement of the bags, which could result in the bag falling off a pallet with the possibility of bag failure and product loss.

There is a clearly a need to provide a method and apparatus for filling bags with a particulate material which will reduce; the packaged volume, the loss of material, or the contamination of the material from the surrounding atmosphere. OBJECT

It is an objection of the invention to provide an improved method and apparatus for packaging particulate materials into a flexible bag which will reduce the packaged volume or significantly reduce the loss of material, or reduce the contamination of the material from the surrounding atmosphere, or one which will at least provide the public with a useful choice.

STATEMENT OF INVENTION

In one aspect the invention provides a packaging machine suitable for completing the packaging of particulate materials (often hereinafter referred to as "product") contained in a flexible container such as a bag, sack, pouch or the like (hereinafter referred to as a "bag"), wherein a plurality of filled bags are provided for delivery to an enclosed environment (hereinafter referred to as a "vacuum chamber"), means are provided for holding a bag or bags in a substantially vertical position within the vacuum chamber, means are provided for controlling the atmosphere whether it be to reduce or increase the pressure, temperature, or humidity, or to alter the makeup of the gases, or any combination of these (often hereinafter referred to as "controlling the atmosphere") within the vacuum chamber and separately within the bag.

Preferably the means for holding the bag in a vertical position includes an adapter head, wherein the adapter head is shaped to fit within the neck of the bag, and has clamping means capable of fully surrounding the bag and clamping it to the adapter head so that the interior of the bag is isolated from the exterior of the bag, and the adapter head has an aperture or apertures for the movement of gases into and out of the bag, allowing sealing of the bag within a controlled atmosphere.

The invention may broadly be said to consist of an apparatus for the packaging of particulate material into bags, having;

a vacuum chamber, at least one door on the vacuum chamber for the insertion and ejection of a bag or bags.

at least one adapter head positioned within the vacuum chamber,

a means for delivering a bag to the adapter head, a means of sealing the bag within the vacuum chamber,

the arrangement and construction being that a bag may be delivered to and held in a substantially vertical position within the vacuum chamber to achieve a controlled environment packaging completion process.

Preferably the adapter head is capable of receiving an opened bag wherein the adapter head is shaped to fit within the neck of the bag, and has clamping means capable of fully surrounding the bag and clamping it to the adapter head so that the interior of the bag is isolated from the exterior of the bag, and the bag is held in a substantially vertical position within the vacuum chamber.

Preferably the adapter head is a substantially symmetrical boat shape, having tapered ends capable of being engaged tightly with the clamping means.

Preferably the adapter head has at least one aperture for the connection of the interior of the bag to at least one vacuum or controlled atmosphere source.

Preferably the apparatus has a means for controlling the atmosphere separately in the interior of the bag and in the interior of the vacuum chamber

Preferably a filter or filters are positioned between the bag interior and any controlled atmosphere source, allowing gases but not product to exit the bag.

Optionally the filter, or filters, between the bag interior and any vacuum or controlled atmosphere source, may extend below the adapter head into the interior of the bag, to more efficiently extract and/or replace gases from all parts of the interior of the bag and be withdrawn if necessary to allow for bag sealing.

In each case, the filter preferably has a perforated filter surface, having apertures small enough to allow the passage of gas, whilst trapping the bulk of the particulate material.

Preferably the means for sealing the bag when it is filled with product, is contained within the vacuum chamber, the means being thermal, pressure or adhesive sealing, closure of self locking features of the bag, or the like, (hereinafter referred to as sealing the bag). Optionally the apparatus contains a means of severing excess material created after sealing the bag.

Preferably means are provided for ejecting the filled bag from the vacuum chamber.

Accordingly in another aspect, the invention may broadly be said to consist in a method of packaging comprising the steps of:

• manoeuvring, opening and holding a bag in a position within a vacuum chamber,

• clamping the neck of the bag to an adapter head,

• adjust the vacuum or control the atmospheres within the bag and the vacuum chamber, by extracting gases from the bag, varying the relative pressures between the inside of the bag and the vacuum chamber, changing gases, or any other desired modification to the atmosphere to suit the product or the packaging process,

• releasing the bag from the adapter head and sealing the opening, or sealing the bag opening first and then releasing the bag from the adapter head,

• restoring the pressure within the vacuum chamber to local atmospheric pressure,

• removing packaged product from the vacuum chamber.

Preferably any gas inserted into the bag is a controlled atmosphere suited to the product, and at a pressure to suit the packaging process and adjusted if required to suit density requirements for the final packaged product.

Optionally the bag may be vibrated to assist with air or gas extraction.

Optionally additional time may be allowed prior to bag sealing to allow the desired de-aeration vacuum level to be achieved.

Optionally a specified gas or mixture of gases can be inserted into the bag to suit the packaged material. In yet another aspect the invention provides apparatus suitable for the packaging of particulate materials into an empty bag, within a vacuum chamber, wherein a plurality of bags, or material for constructing bags are provided for delivery to the vacuum chamber, means are provided for holding the bag in a fill position within the vacuum chamber, means for controlling the atmosphere within the bag, and separately within the vacuum chamber, and supply means for delivering the particulate material to the bag.

a fill hopper,

a vacuum chamber adjacent to or preferably below the fill hopper, at least one door on the vacuum chamber for the insertion and ejection of a bag or bags.

an adapter head positioned within the vacuum chamber,

a means for delivering an opened bag to the adapter head,

a conduit means for delivering product to the bag from the fill hopper.

a means for closing the delivery conduit,

a means of sealing the bag,

the arrangement and construction being that a bag may be delivered to and held in the fill position within the vacuum chamber to achieve a controlled environment packaging process.

Preferably the fill hopper is a weigh hopper so that a predetermined dose of product can be stored ready for delivery to the bag.

Preferably the pre-weigh fill hopper is physically isolated from the adapter head and vacuum chamber during the weighing process.

Optionally the means for physically isolating the fill hopper from the fill head consists of two telescoping pipes, the passageway between the exterior of the inner pipe and the interior of the outer pipe being sealed by a pneumatically or hydraulically expanded seal, or the like, the seal being relaxed or diminished during the weighing operation.

Optionally the means for physically isolating the fill hopper from the adapter head may be achieved using two telescoping pipes, the passageway between the exterior of the inner pipe and the interior of the outer pipe being sealed by a low friction seal, made of polytetraflouroethylene or the like.

Optionally the means for physically isolating the fill hopper from the adapter head may be two pipes connected using a light bellows arrangement.

Preferably the fill hopper has a shut-off valve in the fill pipe upstream of the mechanical isolation means.

Preferably the conduit means for delivering product to the bag from the fill hopper connects to at least one aperture in the adapter head, and the conduit means has at least one valve which can be closed to isolate the interior of the bag from the atmosphere in the hopper.

Preferably the adapter head is capable of receiving an opened bag wherein the adapter head is shaped to fit within the neck of the bag, and has clamping means capable of fully surrounding the bag and clamping it to the adapter head so that the interior of the bag is isolated from the exterior of the bag, and the bag is held in a filling position within the vacuum chamber, and the adapter head has an aperture or apertures for the delivery of product to the interior of the bag,

Preferably the adapter head has as least one additional aperture for the connection of the interior of the bag to at least one vacuum or controlled atmosphere source.

Optionally a form chamber is situated within the vacuum chamber to control the shape of the bag as it is filled.

Preferably the apparatus has a means for controlling the atmosphere separately in the interior of the bag and in the interior of the vacuum chamber before, during and after the filling process Preferably a filter or filters are positioned between the bag interior and any controlled atmosphere source, allowing gases but not product to exit the bag.

Optionally the fill hopper may be vented and contain a filter within the vent to prevent product leaving the hopper, or to prevent contaminants entering the hopper, or the hopper may have its atmosphere controlled by the introduction of inert or preservative gases or the like.

In each case, the filter preferably has a perforated filter surface, having apertures small enough to allow the passage of gas, whilst trapping the bulk of the particulate material and or powder associated with the filling operation.

Preferably the means for sealing the bag when it is filled with product, is contained within the vacuum chamber.

Optionally the apparatus contains a means of severing excess material created after sealing the bag.

• loading the fill hopper,

• manoeuvring, opening and holding a bag in a fill position within a vacuum chamber,

• clamping the bag to an adapter head,

• adjusting the level of vacuum or otherwise controlling the atmospheres inside the bag and inside the vacuum chamber,

• introducing product into the bag, • isolating the interior of the bag from the fill hopper,

• during and after delivery of the product into the bag, continuing to alter the vacuum or control the atmospheres within the bag and the vacuum chamber, by extracting gases from the bag, varying the relative pressures between the inside of the bag and the vacuum chamber, changing gases, or any other desired modification to the atmosphere to suit the product or the packaging process,

• restoring the pressure within the vacuum chamber to local atmospheric,

• removing the packaged product from the vacuum chamber.

Preferably product is introduced to the bag via a pipe or pipes in the adapter head and gases are passed into or out of the bag via a vent pipe or pipes also in the adapter head.

Preferably product travels rapidly into the bag by means of differential pressure, the product being held in the hopper at or near atmospheric pressure, and a vacuum being applied to the interior of the bag so that the product is delivered into the bag more rapidly than is possible by gravity alone.

Optionally the process that causes the bag to inflate prior to filling, is due to the controlled pressure differential between the bag and the vacuum chamber.

Optionally the bag may be vibrated to assist with air or gas extraction.

Optionally additional time may be allowed prior to bag sealing to allow the desired de-aeration vacuum level to be achieved. Optionally a specified gas or mixture of gases can be inserted into the bag to suit the packaged material.

In another aspect the invention provides a method of cleaning filters during the packaging of particulate material in a vacuum chamber.

Preferably each filter has an associated means for supplying gas to the filter in the reverse direction, typically air, so that the gas can pass through the filter, or be pressure pulsed through the filter, to dislodge particulate material. To achieve this cleaning process, it is preferred that the vent pipe outlet has a valve, which can be closed during the cleaning process.

Optionally each filter has an associated mechanical scraper which is capable of being moved over the surface of the filter to remove dust or particulate material.

Preferably, in the case of a filter associated with the fill hopper, the cleaning process can take place prior to delivery of material to the interior of the bag, so that any dislodged material can be sucked into the bag.

In the case of the filters associated with the adapter head, the cleaning process can take place while the bag is in place, so that dislodged material will remain in the bag.

These and other aspects of this invention, which should be considered in all its novel aspects, will become apparent from the following description, which is given by way of example, only, with reference to the accompanying drawings in which:

DRAWINGS

Figure 1 : Is a side elevation of a schematic view of the bag and chamber

Figure 2: Is an end elevation cross-section of a schematic view of the bag and chamber

Figure 3 : Is a plan view of adapter head and bag clamps

Figure 4: Is a cross section of adapter head and clamps Figure 5: Is a cross section of schematic showing the relationship of the hopper and isolation valves to the chamber

Figure 6: Is a cross-section of a schematic view of the bag and chamber, with bag positioned about the adapter head.

Figure 7: Is a cross-section of a schematic view of the bag and chamber, showing the action of clamping the bag to the adapter head.

Figure 8: Is a cross-section of a schematic view of the bag and chamber, showing the bag clamped to the adapter head.

Figure 9: Is a cross-section of a schematic view of the bag and chamber, showing the bag readied, prior to filling.

Figure 10: Is a cross-section of a schematic view of the bag and chamber, showing product entering the bag and gas being vented off.

Figure 11: Is a side elevation of the filter system during the filling operation.

Figure 12: Is a side elevation of the filter system during filter clearing operation.

Figure 13: Is a side elevation of the plunge filter system shown with the filter withdrawn.

Figure 14: Is a side elevation of the plunge filter system during the bag filling and de- aeration operation.

Figure 15: Is a cross-section of a schematic view of the bag and chamber, with bag filled and being de-aerated.

Figure 16: Is a cross-section of a schematic view of the bag and chamber, with a preservative gas or desired air pressure being introduced into the product.

Figure 17: Is a cross-section of a schematic view of the bag and chamber, showing removal of the clamps. Figure 18: Is a cross-section of a schematic view of the bag and chamber, showing the bag being withdrawn from the adapter head.

Figure 19: Is a cross-section of a schematic view of the bag and chamber, showing the bag being sealed.

Figure 20: Is a cross-section of a schematic view of the bag and chamber, showing the sealing bars being retracted.

Figure 21: Is a cross-section of a schematic view of the bag and chamber, showing the pressure in the chamber being restored to atmospheric prior to release of the bag from the chamber.

Figure 22 Is a plan view of two preferred filling machines about a bag loader and an out- feed conveyor.

Figure 23 Is an end view of one of those filling machines.

Figure 24: Is a front view of one of those filling machines.

DETAILED DESCRIPTION

The invention may also broadly be said to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of the said parts, elements or features, and where elements or features are mentioned herein and which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as individually set forth

EXAMPLE 1:

This example deals with the placement of an empty bag within a chamber and filling the bag within the chamber under a controlled atmosphere.

Figures 1-21 show only a bag within a chamber to illustrate schematically the filling operation. Figures 22-24 illustrate a full-scale pilot plant embodying this invention. The sequence of events, the timing, the use of vacuum, the use of other gases- or otherwise controlled atmospheres will depend on the product being packaged and the environment in which it is to be packaged. The following provides a typical sequence for packaging a dairy product like whey protein concentrate powder.

Referring now to Figure 1, the apparatus is provided with a vacuum chamber (2) containing an optional form cavity (3), an adapter head (4), a fill pipe (5), a vent pipe (6), a seal bar (7) and a clamp bar (8).

Referring now to Figure 2, the apparatus is provided with a vacuum chamber (2) containing an optional form cavity (3), an adapter head (4) incorporating a fill pipe (5) and a vent pipe (not shown), seal bars (7) and clamping bars (8). The bag (9) is shown presented to the adapter head (4).

Referring now to Figure 3, showing a cross section of the adapter head (4) and the relationship with the clamping bars (8). The adapter head (4) is shown with a central fill pipe (5), flanked by two vent pipes (6). The fill pipe (5) communicates with a fill hopper or other supply means. The adapter head is substantially a symmetrical boat shape, and is sized to fill the neck of the bag allowing it to be tightly clamped around the adapter head and yet hold the bag open enough to allow for the ingress of powder or the like.

Referring now to Figure 4, the clamping bars (8) can be brought into contact with the adapter head (4) to provide a seal between the bag (not shown) and the adapter head (4). This allows the vacuum or atmosphere witib n the bag to be controlled separately from that of the vacuum chamber. The clamping arrangement also allows the exterior surface of the bag to remain substantially clean and uncontaminated by the product.

Referring now to figure 5, a fill hopper (14), and adapter head (4), separated by isolating valves (16) and (17). In between the isolating valves there is a disconnection means, for the purpose of physically isolating the hopper during the weighing process. The disconnection means comprises a flanged collar (18) containing an airtight seal formed by inflating a ring or collar about the outlet of the hopper. By inflating this collar (18), an airtight seal can be formed between the adapter head (4) and the base of the hopper (14). By deflating the collar (18), the hopper is physically separated from the adapter head (4) as required for the pre-weighing process.

Referring now to Figure 6, a bag (9) is delivered to the adapter head (4). The bags may be provided from a stack of pre-made bags stored in a magazine, or be made from a roll of tube material, or other similar means. In the preferred embodiment, at the start of a cycle, the chamber is open, bags are picked up from the bag loader and moved into the bag filling position, in which a bag is positioned below a respective weigh hopper, and is connected to the adapter head (4). Delivery of the bag is by means of suction pads and mo eable arms, so that a bag can be picked up from a supply of bags, moved into position, and then opened sufficiently so that it can be inserted over the adapter head (4).

Referring now to Figure 7, clamp bars (8) surrounding the bag (9) move to meet the bag (9), forming a tight seal between the adapter head (4) and the bag (9).

Referring now to Figures 8 and 9, a low level of vacuum is drawn on the vacuum chamber (2) evacuating atmosphere from the vacuum chamber (2), and air is allowed to travel from the fill pipe (5) and or the vent pipe (6) into the bag (9). By controlling the relative pressure within and outside the bag, it is possible to inflate the bag so that it is ready for delivery of product, and yet the bag can be maintained at a much lower pressure than atmospheric, so that there is a significant pressure differential between the atmospheric pressure within the weigh hopper, and the residual pressure within the bag. Consequently the pressure differential will allow the material to be pushed into the bag much faster than if it were to fall into the bag simply under the influence of gravity. By way of example a 25kg bag can be filled with particulate material within about three seconds using the process of this invention, compared with a fill time of about ten seconds for a typical gravity hopper.

Referring now to Figure 10, a predetermined amount of product (10) is released into the fill pipe (5). Gas removal from the bag (9) is assisted by applying vacuum to the vent pipe (6). Once the bag has been filled, and this can be sensed by the emptying of the weigh hopper, the weigh hopper can be disconnected from the bag by means of an isolating valve (refer back to Figure 5, valve (16)) so that the bag is no longer exposed to hopper internal pressure.

Figures 11-14 provide an illustration of the filter system in the adapter head. Referring now to Figure 11, throughout the filling process the relative pressure between the bag (9) interior and the vacuum chamber (2) is maintained by extracting air from the bag through the vent pipe (6) and from the vacuum chamber vent pipe (not shown). A filter (12) in the vent pipe (6) prevents product leaving the bag (9) via the vent pipe (6). The use of the vacuum in combination with the adapter head creates the airflow in the chamber and bag as indicated by the arrows. By evacuating the bag in this manner, and or inserting a controlled amount of a selected gas into the interior of the bag via vent pipe (6), the density and to some extent the shape of the bag can be controlled. For example by sealing the bag under a controlled vacuum, and by using a substantially gas impermeable material for the inner pouch of the bag, whether the exterior of the bag is made of Kraft paper, a plastics material, or some composite, the bag maintains a higher density, and a much firmer shape than a bag filled under atmospheric pressure.

Referring now to Figures 13 & 14, an optional or additional filter (12) can be of an optional form as a plunge type filter, which can be driven into the particulate material (10) within the bag (9) to more efficiently extract gases from all parts of the particulate material (10). In this case a rigid filter is desired, e.g. a sintered metal type.

Figure 13 shows the plunge filter (12) withdrawn as it would be while a new bag (9) is installed onto the adapter head (4)

Figure 14 shows the plunge filter (12) extended into the particulate material (10) as it would be during the filling process, while the gases are being extracted via the vent pipe (6). The filter is then retracted prior to bag closure and sealing. The plunge filter (12) can be mechanically scraped by a scraper ring during retraction of the filter.

At the conclusion of the filling process or at intervals during the filling process the filter (12) may become partially blocked due to build up of the particulate material on its surface, and a plunge type filter may become attached to the particulate material in the bag. This build up or attachment is alleviated by providing each filter with an associated means for supplying gas, most commonly air, to the filter in the reverse direction. This is best illustrated in Figure 12. The arrows illustrate the flow of air in the system. As can be seen the flow of air down the vent pipe (6) blows the particulate material (10) away from the filter (12). The reversal in airflow can be undertaken without interrupting the filling process.

The filter may also have a valve controlling the airflow in the filter outlet. This valve can then be closed during the cleaning process so the air can be applied in a singly continuous supply or in pulses to allow effective dislodging of the particulate material.

It will be apparent to those skilled in the art that the same arrangement can be applied to the filters located at the adapter head and the fill hopper. In the case of the filter associated with the fill hopper it is particularly advantageous to clean the filter prior to delivery of the material into the interior of the bag so any dislodged material will be sucked into the bag. With respect to the filter associated with the adapter head the cleaning may take place during filling of the bag or at the end of the filling process while the bag is still in place so that any dislodged material will remain in the bag.

Referring now to Figure 15, the fill pipe (5) is sealed, the pressure in the vacuum chamber (2), the bag (9) and the product (10) can be altered to further assist the de-aeration process.

Referring now to Figure 16, air or a controlled atmosphere such as Carbon Dioxide or Nitrogen, or a gas such as a preservative, may be introduced to saturate the product (10) through the vent pipe (6). The desired bag (9) internal pressure or gas volume is achieved. Gas or air may also be added or removed via vent pipe (11) so that the desired vacuum chamber (2) internal pressure is achieved.

Referring now to Figure 17, the clamp bars (8) are released from the bag (9), allowing it to be removed from the adapter head (4).

Referring now to Figure 18, the bag (9) is drawn away from the adapter head (4) by lowering the form chamber or platform on which the bag rests, and the top of the bag is extended by moveable arms, stretching the bag (9) closed.

Referring now to Figure 19, the seal bars (7) extend to meet and seal the bag (9). The preferred sealing method is thermal sealing, but other means such as pressure or adhesive sealing, or closure of self locking features of the bag, or the like may be employed. Referring now to Figure 20, the seal bars (8) retract after the bag (9) is sealed.

Referring now to Figure 21, the vacuum chamber (2) interior pressure is restored to local atmospheric pressure . The bag is then moved to the out-feed conveyor, clearing the chamber (2) for the next bag filling operation.

Figures 22 and 23 show the layout of a plant comprising two chambers situated about an external bag loader (19) and an out-feed conveyor (20). Each plant has means for delivering powder from an upper hopper (22), via augers (21) to separate pre-weigh hoppers (14), each being connected by a fill pipe (5) to the adapter head within each chamber.

As shown in Figure 24, the upper hopper (22) stores the bulk material for example a powder such as milk powder, vinyl resin, or other granular or dusty material. This is delivered by the augers (21) to a pair of pre-weigh hoppers (14). Each pre-weigh hopper has an appropriate load cell or cells so that a predetermined amount of product is stored in each weigh hopper prior to the bag filling operation. The product travels via the fill pipe (5) in to the bag (not shown) contained within the vacuum chamber (2). This figure also shows the location of the bag loader (19) situated between the two vacuum chambers (2).

Preferably the operation is fully automatic, so the bag filling operation is repetitive, and essentially dust free.

This type of machine can be used to fill bags typically from 5kg to 50kg. For example a 25kg cement bag may be packed using this type of machine, or a 25kg dairy bag can be filled with milk powder or other dairy products.

EXAMPLE 2:

This example deals with the placement of a filled bag within a chamber and removing gas and optionally further modifying the atmosphere within it, and sealing it within a controlled environment.

Figures 1 to 4, 6 to 7 and 10 to 21 show a bag within a chamber to illustrate schematically the filling operation described in Example 1. These same figures can also be used to describe this second example where a filled bag (9) is introduced to the vacuum chamber (2). But it is important to note that the fill pipe (5) shown in these figures will be permanently closed or be removed completely in this second example. The sequence of events, the timing, the use of vacuum, the use of other gases or otherwise controlled atmospheres will depend on the particulate material and the environment in which it is to have its packaging completed. The following provides a typical sequence for completing the packaging of a dairy product like whole milk powder.

Referring now to Figure 1, the apparatus is provided with a vacuum chamber (2) containing an optional form cavity (3), an adapter head (4), a vent pipe (6), a seal bar (7) and a clamp bar (8).

Referring now to Figure 2, the apparatus is provided with a vacuum chamber (2) containing an optional form cavity (3), an adapter head (4) incorporating a vent pipe (not shown), seal bars (7) and clamping bars (8). The bag (9) is shown presented to the adapter head (4).

Referring now to Figure 3, showing a cross section of the adapter head (4) and the relationship with the clamping bars (8). The adapter head (4) is shown with two vent pipes (6). The adapter head is substantially a symmetrical boat shape, and is sized to fill the neck of the bag allowing it to be tightly clamped around the adapter head.

Referring now to Figure 4, the clamping bars (8) can be brought into contact with the adapter head (4) to provide a seal between the bag (not shown) and the adapter head (4). This allows the vacuum or atmosphere within the bag to be controlled separately from that of the vacuum chamber.

Referring now to Figure 6, a bag (9), filled elsewhere with a particulate material, is delivered to the adapter head (4).

Referring now to Figure 10, gas removal from the bag (9) is accomplished by applying vacuum to the vent pipe (6).

Figures 11-14 provide an illustration of the filter system in the adapter head. Referring now to Figure 11, the relative pressure between the bag (9) interior and the vacuum chamber (2) is maintained by extracting air from the bag through the vent pipe (6) and from the vacuum chamber vent pipe (not shown). A filter (12) in the vent pipe (6) prevents product leaving the bag (9) via the vent pipe (6). The use of the vacuum in combination with the adapter head creates the airflow in the chamber and bag as indicated by the arrows. By evacuating the bag in this manner, and or inserting a controlled amount of a selected gas into the interior of the bag prior via vent pipe (6), the density and to some extent the shape of the bag can be controlled. For example by sealing the bag under a controlled vacuum, and by using a substantially gas impermeable material for the inner pouch of the bag, whether the exterior of the bag is made of Kraft paper, a plastics material, or some composite, the bag maintains a higher density, and a much firmer shape than a bag filled under atmospheric pressure.

Referring now to Figures 13 & 14, an optional or additional filter (12) can be of an optional form as a plunge type filter, which can be driven into the particulate material (10) within the bag

(9) to more efficiently extract gases from all parts of the particulate material (10). In this case a rigid filter is desired, e.g. a sintered metal type.

Figure 13 shows the plunge filter (12) withdrawn as it would be while a new bag (9) is installed onto the adapter head (4).

During the gas removal process the filter (12) may become partially blocked due to build up of the particulate material on its surface, and a plunge type filter may become attached to the particulate material in the bag. This build up or attachment is alleviated by providing each filter with an associated means for supplying gas, most commonly air, to the filter in the reverse direction. This is best illustrated in Figure 12. The arrows illustrate the flow of air in the system. As can be seen the flow of air down the vent pipe (6) blows the particulate material

(10) from the filter (12). The filter may also have a valve controlling the airflow in the filter outlet. This valve can then be closed during the cleaning process so the air can be applied in a singly continuous supply or in pulses to allow effective dislodging of the particulate material.

Referring now to Figure 15, the pressure in the vacuum chamber (2), the bag (9) and the product (10) can be further altered to assist the de-aeration process, which can take some time.

Referring now to Figure 19, the seal bars (7) extend to meet and seal the bag (9). The preferred sealing method is thermal sealing, but other means such as pressure or adhesive sealing, or closure of self locking features of the bag, or the like may be employed.

Referring now to Figure 20, the seal bars (8) retract after the bag (9) is sealed.

Referring now to Figure 21, the vacuum chamber (2) interior pressure is restored to local atmospheric pressure. The bag is then moved to the out-feed conveyor, clearing the chamber (2) for the next bag filling operation.

EXAMPLE 3:

Typical for the packaging of a particulate material such as Sodium Caseinate using the apparatus and method described in Example 1 ;

• Fill weight 20kg • Cycle time 40 seconds per bag.

• Volume reduction approximately 23%

• Vacuum level 45%

ADVANTAGES OF THE PREFERRED EMBODIMENT

Advantages of packaging per Examples 1 or 2 include greater packing density and a more compact pack. By controlling the vacuum within the bag it is possible to control the packed product density and the "softness" or "hardness" of the resulting pack.

Economic Benefit of packaging as per Example 1 or 2:

• Skim Milk Powder

• Current container loading 540 x 25kg bags. (13,500kg)

• Possible with the system of Examples 1 or 2 = 720 x 25kg bags. (18,000kg)

• Payload increase = 4500kg per container. (33% more mass can be shipped)

This equates to a 25% saving in freight costs (1000 containers at 13,500kg is the same payload mass as 750 containers at 18,000kg)

A further advantage of the first example is that by controlling the delivery of the dusty powder or granular material into the bag whilst the bag is maintained within a vacuum chamber, the differential pressure in delivering the powder to the bag will minimise the escape of dust, or product, reducing contamination of the bag exterior, and reducing contamination of the machinery and atmosphere surrounding the machinery. This is particularly important where escaping product may create a health, fire or explosive hazard. For example packing of flour, and certain industrial products, may create a significant fire hazard, and in some cases may result in an explosion. Other products such as cement powder can be very abrasive, and it is preferable that such powder is not allowed to escape, or contaminate the machinery. Many particulate materials can be harmful to human health particularly when inhaled as would be typical in a dust filled environment. Since the packaging method described in the first example is an essentially closed system, it is possible to significantly reduce contamination of the product from the surrounding environment. For example a packaged food or pharmaceutical product which can be degraded by oxygen or bacteria will benefit greatly from this packaging machine and method.

Similarly, since the process is essentially closed it is possible to significantly reduce the loss of product during packaging. This saving could be significant when one considers that during the lifetime of a machine many millions of tons of product may be packaged.

This invention can be used with any form of open top bag. It is not necessary for the bag to have a separate valve or opening, as the pressure differential between the hopper and the interior of the bag is sufficient to allow for speedy filling of the product, with minimal contamination by dust or the like.

Although the invention has been designed for use with flowable material such as powders, and granules, it will be possible to adapt this invention to allow for the filling of liquids, pastes or slurries in addition to powders. However, the primary advantage of the invention is in the use of filling open top bags with dusty powders or granules. Moreover the bag can be sealed within the vacuum chamber, and any residual powder dust or granules trapped within the vacuum chamber can be collected, with minimal contamination to the atmosphere when the filling machine is open.

VARIATIONS

It will be appreciated that Figures 1-21 show a schematic view of the filling operation. Mention is made there of a form chamber. A form chamber may be used in some cases where the bag needs to be pre-configured to a particular shape. However, we have found that in most cases such a form chamber is not necessary. The design of the bag itself, and perhaps vibration or shaking of the bag prior to sealing is sufficient to form the filled bag into the desired shape.

Figures 22-23 show one bag filling operation per chamber. It will be possible to make use of this invention with multiple bag filling operations per chamber.

Although not shown, a number of vacuum chambers may be arranged side by side to form parallel paths for packaging, or completing the packaging of, bags at an increased rate. Finally, it will be appreciated that various other alterations or modifications may be made to the foregoing without departing from the scope of this invention.

Claims

1. A packaging machine suitable for packaging a particulate material in a bag (as herein defined), wherein a plurality of bags are provided for delivery to a vacuum chamber (as herein defined), means are provided for holding a bag or bags in a substantially vertical position within the vacuum chamber, means are provided for controlling the atmosphere (as herein defined) within the vacuum chamber and separately within the bag.

2. A packaging machine as claimed in claim 1, wherein the means for holding a bag in a substantially vertical position includes an adapter head, wherein the adapter head is shaped to fit within the neck of a bag, and has clamping means capable of fully surrounding the bag and clamping it to the adapter head so that the interior of the bag is isolated from the exterior of the bag, and the adapter head has apertures for the movement of gases into and out of the bag, allowing sealing of the bag within a controlled atmosphere.

3. A packaging machine as claimed in claim 2, further including means for supplying the particulate material to the bag under a pressure differential, said means including a fill pipe passing through the adapter head.

4. A packaging machine as claimed in claim 3, wherein it has a pre-weigh fill hopper mounted on load cells, and is connectable to the fill pipe.

5. A packaging machine as claimed in claim 4, wherein the fill pipe from the fill hopper to the adapter head has at least one valve which can be closed to isolate the interior of the bag from the atmosphere in the hopper.

6. A packaging machine as claimed in claim 4, wherein the connection between the fill hopper and the fill pipe can be physically isolated to facilitate a per-weighing process.

7. A packaging machine as claimed in claim 1, wherein a filter or filters are used between the packaged material and the controlled atmosphere or vacuum source.

8. A packaging machine as claimed in claim 7, wherein at least one of the filters between the packaged material and the vacuum or controlled atmosphere source, is capable of being positioned within the bag and removed from the bag prior to sealing.

9. A packaging machine as claimed in claim 1, wherein means are provided for sealing the bag, within the vacuum chamber.

10. A sealed bag containing a particulate material having a higher density than a similar sealed bag packaged in an open environment.