GB2354723A

GB2354723A - Electrostatic spray gun

Info

Publication number: GB2354723A
Application number: GB0021606A
Authority: GB
Inventors: David Campbell
Original assignee: EUROTEC FINISHING SYSTEMS Ltd
Current assignee: EUROTEC FINISHING SYSTEMS Ltd
Priority date: 1999-09-03
Filing date: 2000-09-04
Publication date: 2001-04-04
Anticipated expiration: 2020-09-04
Also published as: GB2354723B; GB0021606D0; GB9920781D0

Abstract

An electrostatic applicator comprising a body part 1 accommodating high voltage generation means 3 and electrode means 7 for electrostatically charging the material to be applied, and a material conveying duct having a spray nozzle 13 at one end and having the material to be applied supplied at its other end, wherein the material conveying duct is releasably connected with the body part 1 and has an aperture 11 to receive the electrode means 7 in a position projecting into the duct.

Description

2354723 TITLE: Electrostatic Applicator

DESCRIPTION

The present invention relates to an electrostatic applicator for food flavourings but without limitation to same.

Dry powder food flavourings have been applied to food in automatic production line processes for many years. Typical applications include potato crisps, biscuits, com snacks etc.

It is common to use an electrostatic charge to both aid the application of the powder to the surface of the food product and to control the dust.

Methods of powder delivery include rotating paddles that throw the powdered flavouring at the food product through an electrostatic charging zone. Also volumetric screw feeders that drop the powdered flavourings onto the food through an electrostatic charging zone created by fine discharge wires connected to a high voltage supply (in a similar way to a photocopier).

An alternative method which has been used for many years is to pneumatically convey the powdered food flavouring through a delivery hose to a conventional electrostatic powder coating spray gun and spray the charged powder onto the food.

A typical powder coating spray gun comprises a high voltage generator and spraying apparatus generally comprising a duct in a body for conveying gas bome 2 powder to be applied to a substrate past means disposed in the duct for electrostatically charging the powder to a spray nozzle at the end of the duct. Typically a corona discharge needle is used to charge the powder. The high voltage generator closely associated with the duct and usually disposed in a housing thereof or attached thereto. The duct and the electrostatic discharge needle are formed as an integral unit The gas borne powder is delivered to one end of the duct and the spray nozzle is attached to the other end of the duct.

The powder coating spray guns are originally designed for applying paint powder onto metal products and generally require various modifications to make them suitable for applying food flavourings. These modifications include increasing the diameter of the powder passage through the spray gun, modifying the spray nozzle to prevent excessive wear and blockages and making the whole spray gun water tight so that it can be hosed down with high pressure water jets without affecting the electrostatic components.

The cleaning may be required frequently to maintain hygiene standards and also to enable the same spraying apparatus to be used for a range of different flavourings. The cleaning is time consuming and it would be advantageous if spraying apparatus could be developed which is more suited to the application of flavourings to food or other applications where it is desirable to minimize the time involved in cleaning the apparatus.

Accordingly the present invention aims to provide a solution.

Accordingly, the present invention provides an electrostatic applicator comprising a body part accommodating high voltage generation means and 3 electrode means for electrostatically charging the material to be applied, the applicator further comprising a material conveying duct having a spray nozzle at one end and having the material to be applied supplied at its other end, and wherein the material conveying duct is releasably connectable with the body part and has an aperture to receive the electrode means in a position projecting into the duct.

A hose carrying the material to be applied may connect directly with the nozzle to form the material conveying duct. The hose may be a flexible hose which is releasably connectable to the nozzle by suitable connection means such as a sliding ring locking device. The gas bome material to be applied, be it food flavouring or otherwise, is conveniently conveyed to the applicator in the usual way, e.g. utilizing compressed air.

In a preferred embodiment the body part has an aperture to receive the spraying nozzle and a locking element is provided to secure the nozzle with respect to the body part. in one embodiment the aperturing to receive the electrode means is provided in the nozzle. Where the nozzle is inserted into the body part in the longitudinal direction of the nozzle the aperturing extends from the tip of the nozzle in the longitudinal direction thereof. Alternatively where the nozzle is inserted in a direction perpendicular to the direction of flow through the material conveying duct, the aperture may comprise a discrete hole into which the discharge electrode is inserted on assembly of the nozzle to the body.

The electrostatic generator forms the main body of the spray gun and is fully sealed against dust and high-pressure water jets. The electrostatic charging 4 electrode is built into the main body and sealed so there are no external parts which may become detached and drop into the food and no electrical contacts which may be affected by contamination or water ingress.

The nozzle of the spray gun is fitted to the end of theconveying/delivery hose and simply locates through the body in such a way that it is held firmly in position relative to the charging electrode. The nozzle contains no electrical parts or obstructions which can wear or clog and may be simply removed from the body of the gun for cleaning when necessary complete with the delivery hose without disturbing the rest of the spray gun.

A further feature is a specially designed swivel clamp in which the applicator is mounted that will allow the nozzle to be angled in virtually any position and which locks with the turn of a simple collar.

The provision of the quickly detachable self contained nozzle which is kept completely separate from the charging components leads to an advantageous construction.

Where several different materials are to be applied using the same applicator, separate nozzle and conveying tube assemblies can be provided for each material. Charging between the different materials simply requires the delivery direct assemblies to be swapped over.

The present invention will now be described further by way of example only with reference to the accompanying drawings; in which:

Figure 1 is a cross sectional side view of an electrostatic applicator in accordance With the invention in its assembled condition, Figure 2 is a cross sectional view on 1-1 of Figure 2 with the conveying hose omitted, and Figure 3 is a partial side sectional view of the electrostatic applicator showing the body part and conveying duct prior to assembly.

Referring to the drawings, a body part of the electrostatic applicator is shown at 1 and is a generally cylindrical component which is bored out to receive an electrostatic generator 3 that inserted into the bore by way of a sealable end opening 5. A cable gland shown at 6 seals the cable entry to the body part 1. An electrostatic corona discharge electrode 7 is sealably mounted in the body part as shown at 9 and projects into a cylindrical aperture 11 formed in the body part. It has its axis disposed perpendicular to the cylindrical axis of the body part in the illustrated embodiment. A cylindrical nozzle 13 is dimensioned to be received in the aperture 11. Allocating collar 15 engages with a corresponding face 17 of the body part. A forward end of the nozzle converges to an opening 19. The side wall of the nozzle is cut away at 21 (seen more clearly in Figure 2). The opposite end of the nozzle has a split sleeve 23 whose inner bore 25 is dimensioned to receive a flexible conveying hose 28. A sliding ring hose locking element 27 is carried on the footsleeve 23 is used for securing the flexible conveying hose with respect to the nozzle as illustrated in Figures 1 and 3.

The nozzle defines a delivery duct and is releasably securable with the body part 1. The illustrated embodiment assembly of the two parts is achieved by moving the nozzle 13 in the direction of arrow A to enter the aperture 11. The recess 21 in the end of the spraying nozzle accommodates the discharge 6 electrode 7 so that in use the discharge electrode is disposed upstream of the delivery end of the spray nozzle as shown more clearly in Figure 1. A nozzle locking knob 29 is inserted in an aperture in the body I and is co-operable, with a recess 31 in the nozzle 13 to secure the nozzle With respect to the body part 1.

Also shown in the drawings is a mounting clamp for the body I which incorporates a swivel mechanism 35. The mounting clamp has a bore to receive the body 1 and a further bore to receive a mounting bar 33. Releasing the swivel clamp mechanism 33 allows the body 1 and hence the nozzle to be angled in virtually any desired position and locked with the turn of the locking collar 35. Alternative clamping mechanisms may be employed.

Claims

7 CLAIMS

An electrostatic applicator comprising a body part accommodating high voltage generation means and electrode means for electrostatically charging the material to be applied, and a material conveying duct having a spray nozzle at one end and having the material to be applied supplied at its other end, wherein the material conveying duct is releasably connected with the body part and has an aperture to receive the electrode means in a position projecting into the duct.
2. An electrostatic applicator as claimed in claim 1, comprising a hose carrying the material to be applied, which is connected directly with the nozzle to form the material conveying duct.
3. An electrostatic applicator as claimed in claim 2, wherein the hose is a flexible hose, which is releasably connectable to the nozzle by suitable connection means.
4. An electrostatic applicator as claimed in claim 3, wherein the suitable connection means is a sliding ring locking device.

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5. An electrostatic applicator as claimed in any one of claims 1 to 4, wherein the gas borne material to be applied is conveyed to the applicator by suitable means.
6. An electrostatic applicator as claimed in claim 5, wherein the gas borne material to be applied is conveyed to the applicator by way of utilising compressed air.
7. An electrostatic applicator as claimed in any one of claims 1 to 6, wherein the body part has an aperture to receive the spraying nozzle.
8. An electrostatic applicator as claimed in any one of claims 1 to 7, wherein a locking element is provided to secure the nozzle with respect to the body part.
9. An electrostatic applicator as claimed in any one of claims 1 to 8, wherein aperturing to receive the electrode means is provided in the nozzle.
10. An electrostatic applicator as claimed in claim 9, wherein the aperturing to receive the electrode means extends from the tip of the nozzle in the longitudinal direction of the nozzle.

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11. An electrostatic applicator as claimed in claim 9, wherein the aperture to receive the electrode means comprises a discrete hole into which the discharge electrode is inserted on assembly of the nozzle to the body.
12. An electrostatic applicator as claimed in any one of claims 1 to 11, wherein the electrostatic generator forms the main body of the spray gun and is fully sealed against dust and high-pressure water jets.
13. An electrostatic applicator as claimed in any one of claims I to 12, wherein the electrostatic charging electrode is built into the main body and sealed therein.
14. An electrostatic applicator as claimed in any one of claims 2 to 13, wherein the nozzle of the spray gun is fitted to the end of the conveying I delivery hose and simply locates through the body in such a way that it is held firmly in position relative to the charging electrode.
15. An electrostatic applicator as claimed in any one of claims 2 to 14, wherein the nozzle contains no electrical parts or obstructions, which can wear or clog.
16. An electrostatic applicator as claimed in any one of claims 2 to 15, wherein the nozzle and delivery hose can be removed from the body of the gun for cleaning when necesssary, without disturbing the rest of the spray gun.
17. An electrostatic applicator as claimed in any one of claims 1 to 16, comprising a swivel clamp in which the applicator is mounted that allows the nozzle to be angled in virtually any position.
18. An electrostatic applicator as claimed in claim 17, wherein the swivel clamp may be locked with the turn of a collar.
19. An electrostatic applicator substantially as hereinbefore described with reference to the accompanying drawings.