AU604468B2 - Foam applicator - Google Patents

Description

C0!1MON1TTEAXLTF OF AtJ7rPTLIA Form Reu lation 1312) PATENTS ACT, 1952 COrIPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE!.4 4 Short Title, Int. CiA 3o/q6 P-pliczition 1urber.

Lcc(ged.

Complete f-oeci ficatio-Loriged, Accepted* Lased; PuhlishecO? Priority.

This document contains the amendments made under Section 49 and is correct for printin! 3 !-ccated Art- TO BE CO2PLETED BY ?T-PUC;:'T Na~re of PApplicant; Acdress of Applicant: Actual Inventori Pd.dress for Service: Cte DEVELOPMENT FINANCE CORPORATION OF NEW ZEALAND DEVELOPMENT FINANCE CENTRE, CORNER OF GREY AND FEATHERSTON STREETS, WELINGTON, NEW ZEALAND NIGEL PAUL MAYNARD ARTHUR S. CAVr CO.I Patent and Trade Mark Attorneys, 1 Alfred Street, Sydney, New1 South Wales, Atistralia, 2000.

Complete Specification or the invention entitle6: EOk% APPLICATOR The follovin;rcT statement is a full description of this invention, including the best metho,.1 of performing it ].-nomn to me,,- 2 This invention relates to an apparatus for evenly spreading fluids on surfaces. More particularly it relates to an apparatus for use in coating or impregnating flat surfaces but is not limited thereto. This is an addition to Australia patent specification number 25915/84.

In the sawmilling industry freshly milled timber can be subjected to unsi.ghtly staining owing to the presence of sapstain fungi. These fungi can be controlled by spreading fungicides on the wood surface immediately after sawing usually by dipping but sometimes by spraying.

However, this adds to the costs of preparing sawn timber and it is desirable to be able to apply the minimum amount of fungicide to achieve cost effective treatment. There are also problems with adopting certain effective treating agents because of chemical corroo0000 siveness or stability in the dip/spray systems.

U0oo0 00 00 o 0 0 It is known in the horticultural industry that insecticides and 000o 0o oo other protective sprays may be most effectively applied through the o 00 use of controlled droplet application. By this method droplets of 0 00 0000 substantially the same diameter are dispersed by spraying nozzles of a centrifugal design. This method improves targetting efficiency and 0 0 000 avoids drift.

0 00 0 20 It has unexpectedly been found that a variation of this principle can provide similar improvements in performance in the prophylactic 0"o""o treatment of sawn timber. By preparing a foam and spreading the foam 0o°° evenly over a surface to be treated control of sapstain can be 0000 .oa.oo achieved using minimal quantities of chemical and with no wastage into the environment.

It is an object of this invention to go some way towards achieving S-3these desiderata or at least to offer the public a useful choice.

Accordingly, in one aspect the invention may be said broadly to consist in a device for generating a foam to be applied to an article, said device comprising; a closed foam chamber in the form of a six-sided parallelepiped, one of said sides being a porous layer through which a foamed liquid can pass with all other sides of the chamber being substantially impermeable to said foamed liquid; means to supply a liquid to be foamed into said chamber or direct to ooo000010 said porous layer; and 00ooo00 0Oo°°o means to supply a pressurised gas to said chamber separately to said 0000 o0 o liquid, 000coo0 0 the arrangement being such that when said liquid is supplied into 0 0 o, said chamber or to said porous layer and said gas is supplied to said chamber a foam is created, said foam being forced out of or through said porous layer by the pressure of the gas in said chamber.

000oo 0o 0 In preferred embodiments, the porous surface is formed from a foamed 0 oo o a plastics material having substantially uniform pore size.

o0 o In a particularly preferred aspect, said porous layer is a first porous layer and said chamber includes a second porous layer opposed tu oo said first porous layer, said second porous layer being of a porosity o Go sufficient to allow gas to flow therethrough but to block liquid flow.

In another embodiment the invention may be said broadly to consist in apparatus for coating a surface of an article with a foamed liquid comprising a foam generating device as defined above and means for conveying said article to be coated to a point at or adjacent that at which the foamed liquid issues from said device.

-4- Although the invention is broadly as described above, it will be appreciated that it also includes constructions of which the following gives examples.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings in which Figure 1 is a side elevational view (partly broken away) of an embodiment of the device according to the invention.

Figure 2 is a schematic diagram illustrating the device of Figure 1 as part of an apparatus for applying liquids to work 0000 °10 pieces.

00 .0 o 0 Figure 3 is a side view of a further embodiment of the apparatus 000 0000 according to the invention.

o 00 00 000 The present invention relates to apparatus for evenly spreading a oo a 000 foamed liquid over surfaces and in particular to a foam generating device for use as part of said apparatus. The device includes a closed foam oo0o chamber in the form of a six-sided parallelepiped, at least one side of the chamber being a porous layer. The remaining siC defining the 00 0 chamber are formed from materials which are at least relatively 0 00 °°00 impermeable to both gas and liquid as compared to the porous layer.

Preferably, these remaining sides are substantially impermeable to both S000ooo gas and liquid.

0 "000 Although the chamber can be of any appropriate size and parallelepiped jhape, it is preferably substantially rectangular in cross-section so as to provide a relatively wide flow path of foam.

A preferred form of a device according to the invention is shown in Figures I and 2. As illustrated, the device 11 is disposed in a recess having sides 12 and a base 13 provided in an apparatus for conveying articles with surfaces to be coated. The sides 12 and base 13 of the recess are formed from materials which are substantially impermeable with respect to both gas and liquid.

Although the device is capable of working where the chamber has only a single porous layer as will be described in more detail in relation to Figure 3, in the presently preferred embodiment shown in Figures 1 and 2, two of the layers 14, 16 defining sides of tie chamber are porous, the renaining sides of the chamber being non-porous.

As can be seen from Figures 1 and 2, it is oooo 0 ooo preferred that the horizontal area of each porous layer 14 and 16 o o o-1 o 0 0 oo substantially corresponds to the horizontal area of the base 13 of the oooo 0 0oo recess.

0 0 oooo 0 0 It is also preferred that porous layers 14 and 16 are of a uniform shape and thickness. However, it will be apparent to those persons skilled in the art that other shapes and dimensions for porous layers 000 0o000 14 and 16 may also be usefully employed.

oooo 0oo0 ,Conveniently, porous layers 14 and 16 are formed from a porous 00, 1 S0substance having a substantially uniform pore size, such as an appropriate foamed plastics material. It will however be appreciated that the porous layers used in the invention can be formed from any 44 porous substance having the requisite permeability to both gas and liquid.

In the most preferred form of the embodiment of the invention shown in Figures 1 and 2, the pores of lower porous layer 16 are of a smaller size than those of upper porous layer 14. In this manner, the i

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-6free flow of gas through lower porous layer 16 is permitted while the flow of liquid is blocked, whereas in upper porous layer 14 the flow of both gas and liquid in the form of a foam is relatively unrestricted.

The interior of the chamber may comprise either a single canpartment (Figure or, as is presently preferred, a plurality of capartments.

This preferred arrangement is again shown in Figure 1.

As shown, between between layers 14 and 16 there are provided a plurality of compartments 17 which are substantially identical to each other. Each campartment 17 is formed by a pair of parallel opposed sides 18 of substantially equal dimensions joined at either end thereof by a o pair of parallel opposed end plates 20. Both sides 18 and end plates 000 r are also formed from a material which is substantially impermeable the entry of liquid as described below, gas or liquid may pass inlto and out of the interior of each ccnpartnent 17 only through porous layers 14 and 16.

0 0 oOO Also shown in Figures 1 and 2 is foam tank 28 which is forme 4 oo within the confines of the recess above upper porous layer 14.

The device of the invention is further provided with means 0 0 capable of supplying liquid to the container. The device may have only a single liquid supply means or alternatively a plurality of such means may be provided. Preferably the liquid supply means comprises a source of liquid in communication with the interior of the chamber which extends substantially across the entire width of the chamber and which has a plurality of evenly spaced liquid outlets therefrom.

In this way, liquid is supplied evenly to all areas of the interior of 1 i i 7 the chamber.

In alternative embodiments, the liquid supply means may comprise a source of liquid in communication with the interior of the chamber through opposite ends thereof or a source of liquid in cancunication with a central bore within the porous surface. Again, in these embodiments the liquid outlets are provided in such a manner as to enhance the even delivery of liquid over the entire width of the chamber.

In the presently preferred embodiment of the invention as shown in I Figure 1 where the interior of the chamber is divided into a plurality of separate campartments 17, each separate compartment 17 is provided with a liquid supply means. One of each pair of end plates 20 is provided with an inlet aperture 22 which serves to allow the ingress of liquid into the interior of each canpartment 17. Each liquid inlet aperture 22 is connected to a source of liquid (not shown).

Preferably, the inlet aperture 22 of each compartment is situated on the same side 12 of the recess. Alternatively, a proportion of the inlet apertures 22 are situated on opposite sides 12 of the recess. As still a further alternative, inlet apertures 22 may he provided in both end plates 20 of each compartnent 17.

The source of liquid to which each inlet aperture 22 is connected contains the substance which is to be applied to a surface of an article.

Preferably the source of liquid comprises a source of a suspension, emulsion or concentrated solution of a fungicide or contact insecticide suitable for anti-sapstain treatment although it is in no way limited to such substances.

The device of the invention is further provided with means

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(7 \Kvr cy L I_ 8 capable of supplying gas to the chamber. Preferably the gas supply means comprises a source of gas under pressure communicating with the interior of the chamber. The gas supply means may comprise at least one gas inlet to the chamber which supplies gas under pressure directly into the interior of the chamber. Alternatively, where the chamber is provided with a bottom porous layer, the gas supply means may be in the form of a gas reservoir supplied from a source of gas under pressure (not shown), the gas being supplied to the interior of the chamber by permeating through the pores of the bottom porous layer. This latter form of gas supply means is presently preferred and 0 0 ooo, is shown in Figures 1 and 2. As shown, between porous layer 16 and 0 0 0 o o o oo0 base 13 of the recess there is formed a gas reservoir 0 0 0000 0ono 24. Reservoir 24 is provided with a gas inlet 26 which is connected to oo o 000 0 o o0 a source of gas under pressure (not shown). Of course, more than one 0000 gas inlet 26 may be provided.

The source of gas under pressure may comprise any gas appropriate o° 9 for the purpose for which it is to be used. Preferably, the gas o000 oo'0 source is a source of air, carbon dioxide, nitrogen or other inert ogas.

In Figure 2, there is illustrated the device of Figure 1 as part of an apparatus for coating articles, the apparatus including means for a0 conveying articles to be treated over foam tank 28. The conveying apparatus as shown is a conveying track 30 along which a work piece 32 passes from right to left in the direction of the arrow.

The operation of the preferred device shown in Figures 1 and 2 will now he described.

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-9- O 00 o '3 o 0i o '3 o '3 oa 0 0 4~i 4'; Liquid, preferably anti-sapstain solution, is injected into each campartment 17 through 'nlet aperture 22. Simultaneously therewith, a gas is supplied under pressure to gas reservoir 24 via gas inlet 26. The gas diffuses through lower porous layer 16 into the interior of each compartment 17, causing the liquid in each ccmparhnent 17 to foam. The gas supplied to reservoir 24 is at a pressure sufficient to cause the foam thus formed to be forced through upper porous layer 14 into foam tank 28.

A further and separate embodiment of the invention is illustrated in Figure 3. In this embodiment, the device 11 is again shown as disposed in a recess in an apparatus for conveying articles to which foam is to be applied. The chamber of this embodiment is formed by base 13 of the recess, walls 12, and porous layer 40. At the top of the recess above porous layer 40 there is provided a mesh or screen 44, between which and porous layer 40 there is formed a foam tank 46.

Device 11 is further provided with liquid inlets 48 situated at opposite ends of the chamber,' Liquid inlets 48 are each connected to a source of liquid under pressure (not shown).

In base 13 there are provided a large number of controlled gas inlets 50 which are preferably evenly dispersed over the area of base 13. Preferably, each of controlled gas inlets 50 is of an equivalent size. Gas inlets 50 are connected to a source of gas under pressure (not shown).

In operation of the device of this embodiment, liquid under pressure is supplied to the chamber through inlets 48 until the interior of the chamber' is filled. Gas under pressure is supplied t from the gas source to each of the gas inlets 50. The gas upon entering the chamber creates a foam within the liquid in the chamber, this foam upon formation being forced through porous layer into foam tank 46 by the pressure of the gas. Foam from foam tank 46 emerges through the apertures in mesh or screen 44 to be applied to the surface of a work piece 32 passing thereover.

It will of course be appreciated that the apparatus of the invention may be used to apply a foam to more than one surface of a work piece 32. Preferably there are two devices 11, positioned to apply foam to both the bottom and the top of a work piece 32. In further embodiments, additional devices 11 may be provided to apply foam to all surfaces of a work piece 32.

Thus, in accordance with the invention there is provided an apparatus ,which applies a uniform amount of a foamed liquid generated by a foam generating device to any one some or all of the surfaces of a work piece.

The device of the invention also has the advantages that it can be installed as a removable cartridge which allows exchange or cleaning, and that it can be produced in any required width without significant cost increase or engineering difficulty. The siting of the foam generating device in a recess in conveying means also reduces the problems of wear and impact associated with known devices.

In the preferred use, the apparatus of the invention is used to apply liquid in the form of a concentrated suspension of fungicide for the control of sapstain funqi to work pieces In the form of freshly sawn pieces of timber. Although this is the preferred use, it will be 11 appreciated by those skilled in the art that this is but a single application of the general principle of the invention. The invention may also be used for the spreading of liquids for such diverse purposes as painting with primer or final coats or for a large range of other applications.

It will appreciated that the above description is provided by way of example only and that the scope of the invention is limited only by the following claims.

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Claims (10)

1. A device for -generating a foam to be applied to an article, said device comprising; a closed foam chamber in the form of a six-sided parallelepiped, one of said sides being a pc ous layer through which a foamed liquid an pass with all other sides of the chamber being substantially impermeable to said foamed liquid; means to supply a liquid to be foamed into said chamber or direct to sai poreus layer; and means to supply a pressurised gas to said chamber separately to said liquid, the arrangement being such that when said liquid is supplied into said chamber or to said porous layer and said gas is supplied to said chamber a foam is created, said foam being forced out of or through said porous layer by the pressure of the gas In said chamber.

2. A device according to claim 1 wherein said porous layer is formed from a porous substance having a substant 4 1lly uniforo pore size.

3. A device according to either claim 1 or claim 2 wherein said porous layer i s f ormed f rom a foamed pl asti cs materi al

4. A device according to any one of the preceding claims wherein the chamber is substantially rectangular in cross-section. A device according to any one of the preceding claims wherein said means to supply liquid to said chamber is a source of liquid in communlicationl with said chamber.

6. A device in accordance with any one of claims. 1 to 4 wherein said means to supply liquid to said chan6be comprises a source of

13- liquid in communication with a central bore within said porous layer. 7. A device according to any one of the preceding claims wherein the chamber defines a single interior compartment. 8. A device according to any one of claims 1 to 6 wherein the chamber defines a plurality of interior compartmenLs, each of said compartments being supplied with liquid by said liquid supply means and gas from said gas supply means. 9. A device according to any one of claims 5 to 8 wherein said source of liquid comprise- a source of suspension, emulsion or concentrated solution oo 0 0 0.00 10 of a fungicide or contact insecticide. 0 0 o0o 10. A device according to any one of the preceding claims wherein said 0 a 0 0o means to supply gas to said chamber comprises a source of gas under pressure in communication with said chamber. co o 11. A device as claimed in claim 10 wherein said source of gas is a source of air, carbon dioxide, nitrogen or other inert gas. 12. A device according to any one of the preceding claims wherein said occe o° porous layer is a first porous layer and said chamber includes a second porous layer opposed to said first porous layer, said second porous layer being of a porosity sufficient to allow gas to flow therethrough but to block liquid flow. 13. A device according to claim 12 wherein said means to supply gas to said chamber includes a reservoir of gas under pressure in communication with said second porous layer.

14. Apparatus for coating a surface of an article with a foamed liquid comprising a foam generating device as claimed in any one of the preceding claims and means for conveying said article to be coated to a point at or adjacent that at which the foamed liquid issues from said device. L1 is i i. .*^**mstaetiwt^mSionwaC^ s, 14 Apparatus according to claim 14 wherein said device is in cartridge form and is installed in a recess in said conveying means.

16. Apparatus according to claim 15 wherein said recess is covered by a screen or mesh having apertures through which the foam created by said device can pass.

17. A device for generating a foamed liquid substantially as herein described with reference to the accompanying drawings.

18. Apparatus for coating a surface of an article with a foamed liquid substantially as herein described with reference to the accompanying drawings. DATED this 15th day of August, 1990. DEVELOPMENT FINANCE CORPORATION OF NEW ZEALAND By Its Patent Attorneys ARTHUR S. CAVE CO. 'n 4