GB2331031A

GB2331031A - An improved spray nozzle

Info

Publication number: GB2331031A
Application number: GB9723535A
Authority: GB
Inventors: Paul Lawrence Garlick
Original assignee: ITW Ltd
Current assignee: ITW Ltd
Priority date: 1997-11-05
Filing date: 1997-11-05
Publication date: 1999-05-12
Also published as: JPH11197551A; EP0914871A3; GB9723535D0; EP0914871A2; CA2252318A1

Abstract

A spray nozzle comprises a fluid tip (1), an air cap (2) seated on the body of the fluid tip (1) to form a fluid tip/air cap assembly (1, 2), and an annular passage (4) between the fluid tip (1) and the air cap (2). A plurality of tangentially arranged passages (3) are angled to the exterior of the fluid tip/air cap assembly (1, 2). They extend from the exterior of the fluid tip/air cap assembly (1, 2) to the annular passage (4) and are located in the region of the connection between the air cap (2) and the fluid tip (1).

Description

1 AN IMPROVED SPRAY NOZZLE 2331031 This invention relates to an improved

spray nozzle and more particularly to an air-aton-iised round spray.

In industries such as the ceramics and food processing industries, there has been a need for some time for a spray set-up capable of producing a large diameter full-cone round spray pattern. In the past this requirement has been partially satisfied with either small fan-shaped patterns or by the use of electrostatic equipment.

An aim of the present invention is to provide an improved spray nozzle to spray large round spray patterns without the need for electrostatic technology.

According to the present invention there is provided a spray nozzle comprising a fluid-tip and an aircap, wherein a plurality of tangential slots angled to the outer circumference of the nozzle are located at the interface between the fluid-tip and aircap.

Preferably, the tangential slots are formed in the fluid-tip and mate with a cone shaped face on the air cap, In an alternative construction the tangential slots may be formed in the aircap, and mate with a cone-shaped face on the fluid tip.

In a further construction a ring-shaped member interfaces with the fluidtip and aircap, the tangential slots being formed in the interface between the ring-shaped member and one of the nozzle members. Conveniently, the tangential slots are formed in the ring shaped member.

The ring-shaped member or indeed the aircap, may be made of a relatively soft material, i.e., moulded from acetal.

The interface between the fluid-tip and aircap may be cone-shaped. In a modified construction the interface between the fluid-tip drid aircap is formed by a ball and cone mating surfaces.

Embodiments of an improved spray nozzle will now be described, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a side elevation of a spray nozzle according to a first embodiment of the present invention; Figure 2 is an end view of the spray nozzle shown in Figure 1, with the aircap, removed; Figure 3 is an axial cross-section taken along the line A-A of Figure 1; 1 1 2 Figure 4 is a view similar to Figure 1 showing a second embodiment of the invention; and invention.

Figure 5 is a view similar to Figure 3, but showing a third embodiment of the The spray nozzle comprises a fluid tip 1 and an aircap 2 which can be fitted onto any suitably threaded conventional or HVLP (High Volume Low Pressure) spray gun (not shown). The interior of such a spray head has atomising-air flow passages which are blanked-off by the back face 8 on the fluid tip 1, and the total air flow is directed through what would normally be the fan-air section.

At the interface between the fluid tip 1 and the aircap 2 the air-flow is directed through tangential slots 3 angled to the outer circumference of the nozzle. The air-flow emerges from the slots 3 as a spinning vortex into the inside surface 4 of the aircap 2. This spinning vortex is accelerated towards the aircap exit 5 by the decreasing crosssectional area in the path of the air-flow.

At the nozzle face 6 the Equid jet is broken up -and is flung outwards by the spinning air jet. It is the radial air velocity component that produces a large diameter round spray pattern.

In the embodiment shown in Figures 1 to 3 the fluid tip 1 is formed with the tangential slots 3 and the aircap 2 has a male cone 7. However in a modification of the improved nozzle, shown in Figure 4, the tangential slots 3 are formed in the aircap 2 and the male cone 9 is formed on the fluid-tip 1. This is believed to aid production of the no-Zzle- In a third embodiment of the nozzle, shown in.t?igure 5, a ring-shaped member 11 which interfaces with the fluid-tip 1 and the aircap 2 has the tangential slots 3 located on either side of the ring-shaped member which slots mate with a smooth cone-shaped face. In the view shown in Figure 5, the tangential slots 3 are shown mating with the air cap. The interfacing member of the three piece nozzle may be manufactured from a relatively soft mouldable material such as acetal.

A further modification of the nozzle would be to replace the cone-to-cone mating surfaces with ball and cone mating surfaces.

In operation the typical air-aton-dsed round spray pattern would be approximately 8 inches (203 mm) in diameter when the spray gun nozzle is held at a distance of 7 to 8 3 inches (178-203 mm) ftom the workpiece. Prototypes of the improved spray nozzle have sprayed patterns of up to 9 inches (229 mm) in diameter when the spray gun nozzle is held at a spraying distance of 12 inches (305 mm) from the workpiece.

It will be obvious that with adjustment of the dimensions of the tangential slots it will be possible to produce round patterns of a larger diameter than 9 inches (229 mm).

1 1 I- -- 4

Claims

CLAIMS 1. A spray nozzle comprising a fluid-tip and an aircap, wherein a

plurality of tangential slots angled to the outer circumference of the nozzle are located at the interface' region between the fluid-tip and aircap.
2. A spray nozzle as claimed in claim 1, wherein the tangential slots are formed in the fluid-tip and mate with a cone-shaped face on the aircap.
3. A spray nozzle as claimed in claim 1, wherein the tangential slots are formed in the aircap and mate with a cone-shaped face on the fluid tip.
4. A spray nozzle as claim in claim 1, wherein the ring-shaped member interfaces 10 with the fluid-tip and aircap, the tangential slots being formed in the interface between the ring-shaped member and either the fluid tip or the aircap.
5. A spray nozzle as claimed in claim 4, wherein the tangential slots are formed in the ring-shaped member.
6. A spray nozzle as claimed in claim 4, wherein the tangential slots are formed in the fluid-tip.
7. A spray nozzle as claimed in claim 4, wherein the tangential slots are formed in the aircap.
8. A spray nozzle as claimed in any of claims 4 to 7, wherein the ringshaped member and/or the aircap is made of a relatively soft material.
9. A spray nozzle as claimed in claim 8, wherein the ring-shaped member andlor the aircap is moulded from acetal.
10. A spray nozzle as claimed in claims 1 or 2, wherein the interface between the fluid-tip and aircap is cone-shaped.
11. A spray nozzle as claimed in any of claims 4 to 9, wherein the interface between the tangentially slotted member and its mating surface is cone-shaped.
12. A spray nozzle as claimed in claims 1 or 2, wherein the interface between the fluid tip and aircap is formed by a ball and cone.
13. A spray nozzle as claimed in any of claims 4 to 9, wherein the interface between the tangentially slotted member and its mating surface is formed by a ball and cone.
14. A spray nozzle substantially as hereinbefore described with reference to the accompanying drawings.