GB2471014A

GB2471014A - Coating apparatus with article inverter

Info

Publication number: GB2471014A
Application number: GB1009593A
Authority: GB
Inventors: Peter King
Original assignee: Spice Application Systems Ltd
Current assignee: Spice Application Systems Ltd
Priority date: 2009-06-08
Filing date: 2010-06-08
Publication date: 2010-12-15
Anticipated expiration: 2030-06-08
Also published as: GB201009593D0; GB2470971A; GB0918004D0; GB2471014B; GB0909703D0

Abstract

The present invention relates to an improved apparatus 30 and method for delivering a coating substance such as a powder, liquid, or suspension coating. The article to be coated is preferably a snack food such as potato crisps or corn chips which are usually coated with flavouring. It is generally desirable to be able to achieve a uniform and controllable coating over the entire surface of a product. The apparatus comprises two enclosed coating stations 33, 34 connected by a conveyor 39 and a flipping or inverting device between the two enclosures. The flipping device may be a drop between conveyors, a cascade system (figure 3a) or a plough share like flipper or curvilinear plate (figure 3b). The inversion of the article between the two coating enclosures ensures even coating on both sides of the article.

Description

COATING DELIVERY METHOD AND APPARATUS

Field of the Invention

The present invention relates to an improved apparatus and method for delivering a coating substance using gas assistance and more particularly, though not necessarily, to an improved apparatus for delivering a powder, liquid, or suspension coating using gas assistance.

Backci round There exists a wide variety of products that require to be coated with a substance (e.g. powder, liquid, suspension, etc) during their preparation.

For example, snack foods such as potato crisps and corn chips are usually coated with flavouring. It is generally desirable to be able to achieve a uniform and controllable coating over the entire surface of a product.

A traditional method used for coating snack foods involves the use of a rotating drum, having a 2 -3m length and a diameter of 0.5 -1.5m, which has its axis generally aligned with the horizontal, but with a slight tilt. Products introduced into one end of the drum tend to travel to the other end as the drum rotates. Flavouring in the form of a powder is delivered via an inclined chute to a location within the drum so that the flavouring is sprinkled onto the products to be coated. This technique tends to result in a non-uniform coating of products, with flavour concentration varying between product pieces and across the surfaces of individual pieces.

It has been recognised that coating uniformity may be improved by placing a charge on the powder, using for example a needle electrode located in the transit path of the product. If the product delivery mechanism, e.g. a rotating drum, is grounded, the products to be coated will also tend to be grounded as they pass under the powder delivery mechanism. The charged powder will be attracted to the products in a generally uniform manner, in turn resulting in a generally uniform coating.

An alternative electrostatic coating apparatus comprises a venturi tube through which the coating substance is forced by a pressurised gas. Upon emerging from an exit nozzle, the substance passes a charging electrode.

Figure 1 illustrates an apparatus for coating a product as described in GB 2,385,810. The apparatus comprises an inclined chute 1 for conveying a coating substance 2, with an exit end 3 and an entry end 4. A gas jet nozzle 5 and a needle electrode 6 are located beneath the exit end 3 of the chute 1. The pressurised gas stream becomes charged as it passes through the electric field created by the charged needle electrode. The charged gas then impacts on the falling coating, dispersing it and imparting a charge to it, and will be attracted to the product in contact with the grounded drum surface, being at ground potential.

As described in GB 2,385,810, the chute 1 used to convey the coating substance is narrow, with a width of 75mm or less, and the coating tends to continue moving in the (longitudinal) direction of the chute (as shown by the arrows in Figure 1) after exiting from the chute, such that the coating is only applied within a narrow region beneath it.

Notwithstanding the above, the percentage of snack foods that are produced without full double-sided coating is high, with a significant number of typical snack foods being coated on only one side, being of the order of 93%. The drum is of a conductive material and is at ground potential relative to the spray discharge electrode, whereby the charged flavouring particles are attracted to the food product, in contact with drum. Vanes are employed on the inside surface of the drum whereby to cause them to turn, whilst not guaranteeing the product to be exposed on both sides to the falling flavouring, are liable to damage product; large products such as crisps are easily damaged; this can damage the reputation of a brand.

A further alternative coating apparatus comprises the use of a pressurized gas and a product delivery system such as a vibratory chute with an outlet; the gas acts as a dispersant (gas knife) below the outlet whereby to agitate the product and enable the powder to be dispersed prior to settling under gravity onto product upon a conveyor such as a vibratory conveyor or a belt conveyor. This type of system creates a cloud of coating powder which can leave a considerable amount of overspray upon neighbouring machinery; product may easily clump together. Once product has been placed in a bag for sale, then this powder can easily fall off. Double sided coating can be performed by a variety of means.

Another problem that arises with prior art systems is that, through the use of a rotating drum system or other conveyor systems is that there can be tremendous wastage of coating material, the rotating drum is open at both ends and the coating material will tend to form an aerosol powder which can permeate the whole atmosphere of a manufacturing facility; this can also result in a contamination of coating materials, for example, flavours between manufacturing lines. Indeed, any gas introduced to assist in dispersion of the coating material will encourage such permeation into the atmosphere about the machinery. This requires flavouring machinery to be placed several metres away from each other if different flavourings are to be applied by adjacent machinery. This can also have an effect on the proximity of packaging systems; packages may not be effectively sealed due to contaminants, if packaging systems are placed too close to drum coating systems.

A still further problem associated with the rotating drum system is that, in the event of a change in the application of a flavour to a snack, then there is a considerable downtime taken to clean the apparatus; the system operable to flavour the snacks can take 30 minute -60 minutes to clean; the drums of im or more in diameter, having a length of 2 -4 m need to be carefully cleaned; the flavour of products must be uniform or otherwise a snack brand will lose customer loyalty. In terms of an industrial process, this corresponds to a loss of 1/48th -1/24th manufacturing time in a 24/7 manufacturing facility which is additionally due to cleaning. This can be significant. In short this leads to manufacturing facilities working at less than full efficiency; which means idle machinery for at least part of the time and a reduced return on investment.

A further aspect to consider is that of flavouring product being wasted to the atmosphere; not only to be considered in terms of the financial loss directly due to loss of product, but also the loss arising from the extra cleaning necessary, not only of the manufacturing machinery adjacent the flavouring application machine, but also of the office machinery, telephones and the like; the vapour particles of flavouring will settle anywhere and everywhere. Indeed, personnel do not appreciate wearing masks to avoid inhalation of unwanted powders and aerosols. Further, such personnel do not appreciate the requirement for cleaning areas adjacent a coating machine.

As will be appreciated, many systems have been developed over the years whereby to enable the coating of flavourings. Despite advances in coating systems, the percentage of snack food products that are not coated uniformly or only on one side remains high, with a significant number of everyday snack-foods being coated on one side being of the order of 7% or more.

Object to the invention The present invention seeks to overcome or ameliorate at least some of the disadvantages described above: the present invention seeks to provide a system that can enable flavouring to be applied in a more uniform fashion than has heretofore been possible. The present invention seeks to provide a system for applying flavouring to snack foods and the like reliably and evenly across the entire surfaces of the snack or at least on two sides of a snack.

Summary

The present invention is applicable in particular to the coating of snack food products with a dry, powdered flavouring. The invention may also be used to coat products with substances other than dry powdered substances including, for example, liquids and suspensions.

According to a first aspect of the present invention there is provided an apparatus for delivering a coating substance towards a product to be coated including a pressurised gas supply, the apparatus comprising a first coating station, an inverting station, a second coating station and conveyor to convey product through said apparatus: Wherein said conveyor is operable to convey product upon a surface thereof to said first coating station to enable coating using gas assistance upon an exposed surface of said product toward the inverting station; Wherein the inverting station is operable to invert product such that, prior to product being transported by the conveyor to said second station where product is arranged such that an uncoated surface thereof is exposed; Wherein said conveyor is operable to convey product upon a surface thereof through and out of said second coating station to enable coating using gas assistance upon a second exposed surface of said product as it passes therethrough; each said coating station comprising an enclosure whereby application of the coating substance is contained within a confined volume above the conveyor, whereby coating product pollution with regard to the atmosphere is substantially absent.

In the event that electrostatic coating methods are employed, it is advantageous that the conveyor supporting product is grounded. In such circumstances, the conveyor is conveniently a vibratory conveyor made of a conductive material, although conductive belt conveyors can also be employed. By the use of an electrostatic means to apply a coating to a product, the charged powder is attracted to ground potential which assists in maintenance of an effectively clear atmosphere outside of the enclosure, since coating material that does not reach product can be collected by removing from components at ground potential.

The coating apparatus can comprise one or more of a powder feed, a slurry feed, a liquid feed, a vibratory feed and an electrostatic feed.

The inverter apparatus can comprise one of adjacent, stepped conveyor belts, a cascade inverter system, or a curvilinear plate system.

The enclosures are arranged whereby to cover the first and second coating stations, the enclosures defining an internal space above each coating device, for example an electrostatic device, spray device or otherwise to enable each coating device to operate whereby a coating via spraying, the generation of an electrostatic vapour, mist, or cloud can be performed and a coating such as a food flavouring can be deposited upon product passing through the enclosure, whilst being transported upon a conveyor. Each enclosure has sides that depend below an operational height of the conveyor and are spaced a minimum distance laterally therefrom. Further, each enclosure has a front and rear edge portion which extend transversely above the conveyor, having depending edges which lie sufficiently adjacent above the conveyor to enable passage of product being transported upon the conveyor -so that passage of product upon a conveyor transporting product from an entrance part to an exit part of the enclosure can be enabled. These first and second edges are conveniently adjustable relative to a conveyor surface whereby to allow passage of different types of product thereunder. Accordingly, the enclosure minimises the possibility of coating product passing from the enclosure other than as a coating upon product, especially reducing aerosol and airborne coating materials.

An internal gutter may be provided to prevent any accumulated coating, which may nonetheless adhere to an inside of the enclosure, from dropping in a clump-like fashion upon product to be coated. In the event that the coating system is an electrostatic system, it is preferable that the enclosure is at the same potential as the charged coating whereby charged coating is encouraged to pass to oppositely charged product.

The conveyor may comprise a single unit, but depending upon the type of inverter employed, may comprise three separate units, for passing through the first coating unit; for inverting the product; and for passing through the second coating unit. Where electrostatics are not employed, rubber or other non-conductive materials can be used for the conveyor.

The present invention thus provides a system of positively coating products such as snack food products and the like in a three stage process, whereby a minimal loss of coating product is encountered and coating of both sides of double-sided snacks is 99% or more effective, which is a significant improvement over known processes. In a first stage of the process, a first side of a product is coated; the product is then inverted and then a second surface of the product is coated.

A significant advantage to the present invention is the lack of waste product in unison with a substantially uniformity on coverage of both sides of a two-sided snack product. As will be appreciated, the present invention is applicable to non-planar snack and non-snack products, although one limitation to the shape of product is provided by the inverting device. As is known, there are a number of inverting apparatus, some of which are not too dissimilar to mouldboard ploughs; other systems rely upon a fall from one conveyor to another to cause inversion.

Conveniently, a packing station is provided adjacent an output from the second coating station. This can reduce the chances of contamination from any airborne contaminants.

According to a second aspect of the present invention there is provided a method of delivering a coating substance towards a product to be coated in a coating procedure operating on two distinct phases, whereby in conjunction with the application of an effective flipping unit can effectively coat at least two sides of a product.

Specifically, in accordance with a further aspect of the invention, there is provided a method for coating a product with a coating substance employing an apparatus comprising a first coating station, an inverting station, a second coating station and conveyor to convey product through said apparatus: the method comprising the steps of conveying a product upon a conveyor through a first coating station, the coating station enshrouding the area to be sprayed with an enclosure, the enclosure being placed in close proximity to the conveyor, and coating the coating substance on a first exposed surface of said product as it passes through the first coating station toward the inverting station; conveying the product to an inverting station; inverting the product by means of the inverting station whereby to expose a second surface of the product; conveying the product to a second coating station inverting station; the coating station enshrouding the area to be sprayed with an enclosure, the enclosure being placed in close proximity to the conveyor, and coating the coating substance on a second exposed surface of said product as it passes through the second coating station; whereby, upon exit from the second coating station the product is coated on two faces and whereby coating product pollution with regard to the atmosphere is substantially absent.

Brief Description of the Drawings

Reference shall now be made to the figures as shown in the accompanying drawing sheets, wherein: Figure 1 illustrates a known coating delivery apparatus; Figure 2 is a simple perspective view of a coating delivery apparatus according to an embodiment of the present invention; Figure 3 is a side view of a coating delivery apparatus according to an embodiment of the present invention; Figure 3a shows a first inverting apparatus; Figure 3b shows a second inverting apparatus being a plan view of the chute of the coating delivery apparatus of Figure 2; and Figure 4a and 4b show side and plan views of a spray enclosure.

Detailed Description of the Preferred Embodiments

There will now be described, by way of example only, the best mode contemplated by the inventor for carrying out the present invention. In the following description, numerous specific details are set out in order to provide a complete understanding to the present invention. It will be apparent to those skilled in the art, that the present invention may be put into practice with variations of the specific.

Figure 2 shows in perspective view a first embodiment of the invention, which shall be discussed in detail with reference to a simplified diagrammatic side view in Figure 3. The coating machine 30 comprises two coating stations 31, 32, enclosed by hoods or enclosures 33, 34, each having an umbilical line 35 operable to provide, for example, input gas, electrostatic leads and coating powder or slurry. The enclosure is conveniently manufactured from a plastics material, such as polypropylene, but is not necessarily made from such material. Incoming product is received on a vibratory conveyor element 36. The apparatus is arranged on two levels, between the first and second coating stations; with product being output on a second vibratory conveyor 37, the middle portion 39 comprising a inclined chute or flipper station operable to flip a generally planar product from a first side as it is received from a coating station onto its second side such that at a second coating station a second side to the product is exposed for receiving a coating within the second coating station. The coating and flipping stations are supported on a framework 38, conveniently made from an industrial grade stainless steel, such as 304 or 316.

The flipper unit 39 can comprise adjacent conveyor belts with a fall and relative speed sufficient to cause planar product to flip over, a cascade system, a plough-share-like flipper or other means of effecting a 180° flip to 99%+ of product. Different food products will need slightly different machinery settings, dependent upon average size, weight, density etc. Figure 3a shows a first simple example of a flipper unit 300 comprising two conveyors 302, 303 spaced apart in height from one another. Step elements 304 are placed immediately below the first conveyor, whereby, upon product 301 (shown to be round and generally planar) on the upper conveyor belt reaching the end of the belt, then it is liable to fall upon the step, whereby to ensure that product arrives upon the lower conveyor belt 303 in an inverted position relative to the first orientation. The relative speeds of the conveyors, the height of the drops in the steps, the average size of product, for example, are taken into account to achieve efficient flipping of product 301.

In the case of Figure 3b, a basic curvi-planar inverter apparatus is shown: product 301 on a first side, with a side A uppermost, arrives via a conveyor belt 306 towards a channel-like system 308 leading towards curvi-planar inverting elements 307 -which are somewhat similar to upturned ploughshares. Judicious use of product speed, orientation and size of the rounded inverting elements 307 enable product 301 to be effectively turned so that they then lie on a different die, with side B uppermost.

The conveyors are conveniently of a standard width, typically being: 30, 40, 50, 60, & 90cm within Europe. With reference to Figure 4, at either end of the coating system 40 in accordance with the present invention, there are coating units, which comprise an enclosure or hood 33, 34 which defines an enclosed space with sufficient volume to enable a coating to be applied. The enclosure or hood 33 can conveniently be hinged at 41 whereby, upon opening, for inspection or otherwise, a weight associated with the hood is borne by the apparatus, through a pivot element. The hood has side elements 42 which depend either side of the conveyor 43 below each side of a conveyor 44, which conveyor can conveniently comprise a vibratory conveyor 36.

With reference to Figures 4a and 4b, one type of powder dispensing system shall be discussed in detail: powder feed 47 comprises a chute with sides 471, 472 either side of a longitudinal axis being substantially at right angles to a flat bottom surface 473; the sides of the chute 471, 472 extending from a closed end 474 of the chute to an open end of the chute 475 comprising an edge which is arranged above an air nozzle 48, which provides a jet of electrostatically charged air by virtue of needle electrode 49 whereby to evenly dispense coating product 480 across the width of the conveyor, the air pressure being typically at 1.5 bar, the needle electrode 49 set at a high voltage, for example 85,000V. In Figure 4b, the view is from above, with a cut-out in the hood 33, whereby to show features of the electrostatic coating apparatus. The chute is inclined downwardly and is vibrated at a rate dependent upon, for example, the rate of dispensing required, the angle of inclination, width of the chute and the nature of the product to be dispensed. The chute is fed by a hopper, not shown at the closed end of the chute indicated at 475; this entry end may have a sloped wall to assist in the reception of coating material. The chute and vibratory device are mounted upon, resilient legs and mounted upon a frame for the conveyor apparatus, although other means of support can be provided. Conveniently, the vibrator is a caused to vibrate by mechanical or electrical pulses as is known.

The gas jet nozzle and needle electrode are located beneath the exit edge 474 of the chute 47. The gas jet nozzle can drive a 145° spray angle; being situated slightly below and to the rear of the chute, this has been found to provide a good degree of uniformity in scattering of the powder.

For relatively narrow conveyor applications, a simple chute, with a straight exit edge at right angles to the chute axis may be employed.

Notwithstanding this there will be limits, dependent upon the type of product and overall size. However, such determination would be well within the capability of the skilled man; a typical width of conveyor is 60cm; however the distance may be more than double this, and equally may be less than this. It will be realised that other coating methods may be deployed within the enclosure; for example two narrow vibratory chute electrostatic coating apparatus may be employed; simple gravity effect sprayers or other types of coating apparatus.

The system, as a whole comprises two of the coating enclosure units with an inverter apparatus positioned between them, whereby to ensure that product is inverted. In processes that require the application of a coating across a wide area, the apparatus described here can provide simple and reliable coating systems which can be easily and quickly cleaned, whereby to reduce overall manufacturing cost sand also enable a quick changeover of flavourings, for example in a snack factory.

By using a simple conveyor system, in relation to prior rotating drum equipment, not only is the overall quality improved, with increases in percentage of product being flavoured on both sides I at least two sides from typically 93% to 99%, through a reduction in wastage (including an increase in reclamation of product which can be collected about the machinery, rather than being allowed to escape into the atmosphere about the application machinery. Additionally the equipment, since it is smaller, with an overall length being smaller than a comparable 2 -3 metre rotating drum on its own, the equipment will readily fit into an existing production line.

The product quality will be higher -there will be less over flavouring to make up for unevenly coated products from prior units. Damage due to breakage from the rotation of a drum will be absent, with no warts on finished products and no lumps on the production line. The system can also be utilized with liquid slurries.

A significant advantage of the system is that the system can occupy a much smaller floor space and enable closer spacing between adjacent equipment, irrespective of the different types of flavouring. This has significant benefits in the planning of a workspace environment, wherein conveying equipment between need not be so lengthy. It is to be remembered that when a production line is stopped, for flavoured products that have not been wrapped, then the whole conveying apparatus need to be cleaned. This is expensive not only in cleaning materials but also in the amount of downtime of a particular plant.

By virtue of the enclosure or hood, in accordance with the present invention, there is no significant escape of flavouring into the atmosphere about a flavouring apparatus. This means that the production line system apparatus can be more closely spaced without fear of cross contamination of product; there is less floor space to clean; there is less conveying plant.

This extra plant is both costly to purchase, install and maintain and requires further floor space and needs to be cleaned, adding extra cleaning time to downtimes upon change of flavourings. The production line can be significantly shorter meaning that cross contamination of flavourings from neighbouring lines does not arise.

A particularly notable advantage of the present invention is that the coating system can be provided in close proximity to a bagging unit, whereby products can be bagged in, for example sealed plastics bags, a short distance from the system which has applied flavour, whereby to reduce possible contamination and ensure freshness. This means that packaging of product can be accomplished adjacent to the flavouring apparatus, whereby seals in wrapping agents are not contaminated; that is to say airborne product does not deteriorate thermal sealing unites, adhesive sealing units etcetera.

It will be appreciated by the person of skill in the art that various modifications may be made to the above described embodiments without departing from the scope of the present invention. For example, the electrical equipment can be manufactured from 1P65 fittings, as is expected and all electrostatic standards can be easily adhered to.

Standard control units, that can be interfaced with standard automation and drives control techniques. Apart from the conveyors, there are no moving items of machinery -other than control equipment such as compressors for the gas feed (typically this will be normal filtered atmospheric air, unless there is a contra-indication with a particular product to be dispensed.

The enclosure and coating apparatus are relatively compact compared to a drum; the equipment is easily and simply cleansed, reducing downtime when coatings and or flavourings are changed on a coating station. Since the provision of an enclosure over the powder distribution area enables a considerably reduced wastage of coating product, a further benefit is that less material needs to be removed as waste product, further simplifying any cleaning process. Additionally, the wastage that will occur will not readily enter the atmosphere surrounding the equipment, thereby considerably improving the working environment for personnel.

Claims

Claims: 1. Apparatus for delivering a coating substance towards a product to be coated, the apparatus comprising a first coating station including a pressurised gas supply, an inverting station, a second coating station and conveyor to convey product through said apparatus: wherein said conveyor is operable to convey product upon a surface thereof to said first coating station to enable coating using gas assistance upon an exposed surface of said product toward the inverting station; wherein the inverting station is operable to invert product such that, prior to product being transported by the conveyor to said second station where product is arranged such that an uncoated surface thereof is exposed; wherein said conveyor is operable to convey product upon a surface thereof through and out of said second coating station to enable coating using gas assistance upon a second exposed surface of said product as it passes therethrough; each said coating station comprising an enclosure whereby application of the coating substance is contained within a confined volume above the conveyor of each respective coating station, whereby coating product pollution with regard to the atmosphere is substantially absent.
2. Apparatus according to claim 1, wherein the enclosure comprises a hood which extends along a portion of conveyor, having depending edges which lie closely above the conveyor, yet doe not interfere with passage of product as it passes along the conveyor.
3. Apparatus according to claim 2 wherein the edges of the hood are adjustable relative to a conveyor surface whereby to allow passage of different types of product thereunder.
4. Apparatus according to claim 1 wherein the hood has sides that depend below an operational height of the conveyor about the hood.
5. Apparatus according to any one of claims 1 -5 wherein the coating apparatus comprise one or more of a powder feed, a slurry feed, a liquid feed, a vibratory feed and an electrostatic feed.
6. Apparatus according to any one or more of claims 1 -5 wherein the inverter apparatus comprises one of adjacent, stepped conveyor belts, a cascade inverter system, a curvilinear plate system.
7. Apparatus according to any one or more of claims 1 -6 wherein a packing station is provided adjacent an output from the second coating station.
8. Apparatus according to Claim 5 wherein the coating system comprise an electrostatic chute feeder with gas assist.
9. Apparatus according to claim 8 wherein the gas assist is provide by a gas jet nozzle located substantially immediately beneath an exit of said electrostatic chute feeder.
10. Apparatus according to Claim 5 wherein the coating system comprise an electrostatic vibratory feeder with gas assist.
11. Apparatus according to claim 10 wherein the gas assist is provide by a gas jet nozzle located substantially immediately beneath an exit of said vibratory feed.
12. Apparatus according to any one of claims 1 -11 wherein a gutter is disposed upon an internal surface of the enclosure, whereby to prevent any adhered accumulated coating from dropping in a clump-like fashion upon product to be coated.
13. Apparatus according to any one of claims 1 -11 wherein the coating apparatus comprises an electrostatic feed and the enclosure is at the same potential as the charged coating whereby charged coating is encouraged to pass to oppositely charged product to be coated.
14. A method for coating a product with a coating substance employing an apparatus comprising a first coating station including a pressurised gas supply, an inverting station, a second coating station and conveyor to convey product through said apparatus, each coating station having an area to be coated enshrouded with an enclosure: the method comprising the steps of conveying a product upon a conveyor through a first coating station, the enclosure being placed in close proximity to the conveyor, and, using gas assistance, coating the coating substance on a first exposed surface of said product as it passes through the first coating station toward the inverting station; conveying the product to an inverting station; Inverting product by means of the inverting station whereby to expose a second surface of the product; conveying the product to a second coating station inverting station, the enclosure being placed in close proximity to the conveyor, and, using gas assistance, coating the coating substance on a second exposed surface of said product as it passes through the second coating station; whereby, upon exit from the second coating station the product is coated on two faces and coating product pollution with regard to the atmosphere is substantially absent.
15. A method according to claim 14 wherein the coating system is an electrostatic coating system, the steps of coating in each coating process including the steps of energising the coating substance with a raised electrostatic potential and of placing the product to be coated at a different electrostatic potential whereby to enable charged coating substances to be electrostatically attracted to the product.