EP1072318B1 - Spray head for electrostatic rotary atomizing spray device - Google Patents

Abstract

The spray head has an atomiser head (2) on a rotating shaft (4) and a nozzle (8) for the coating material in the interior (9) of the head. Several outlet openings (13) are arranged at an axial distance apart on the periphery of the atomiser head with atomising edges (14) for the coating material. A porous body is used to form the outlet openings and atomising edges.

Description

The invention relates to a spray head for an electrostatic rotary atomizer, the electrostatic charge of the coating agent to be applied works according to the preamble of claim 1. Such Spray head is known from US 3,572,589.

Usually the coating agent, which is color or Lacquer and the like is inside a driven hollow shaft fed to a stationary nozzle. The coating agent comes from the nozzle on the fast rotating, usually bell-shaped atomizer head and is finally released from its atomizer edge. These features are shown in German utility model 92 17 458 and described. So that radially flung away from the atomizer edge Paint particles must get onto a workpiece to be painted the atomized paint can be moved forward in the axial direction. To in addition to the electrostatic forces acting in this direction, also a steering air flow is usually used. It emerges from one Wreath of holes behind the rotating bell atomizer and then acts on the atomized paint particles in the axial direction.

Depending on the diameter of the bell-shaped atomizer and At its speed, the spray patterns have a diameter of around 500 up to 700 mm. Radial centrifugal forces, also radial, from the rotating atomizer initiated air flows and axially acting steering air flows overlap in such a painting process.

The said lead in particular when atomizing metallic paints Framework conditions for a significantly different training of the achieved Metallic effect than when applying metallic varnish with a conventional, air atomizing spray gun.

This different formation of metallic effects has the consequence that in practice, the second layer of metallic paints usually does not use electrostatic Atomize, but with conventional, air atomizing Spray guns are applied, resulting in significantly higher paint losses leads.

It is also the case with automatic, electrostatic paint atomization difficult with bell-shaped atomizers, spray pattern diameter too achieve that are smaller than 400 mm. This problem arises, for example when painting narrow profile strips or when the paint is in undercuts, Wells or other, so-called Faraday cages should arrive.

In principle, it is possible to use spray patterns with less Achieve diameter when the diameter of the bell atomizer is chosen significantly smaller than usual. But it is also connected a reduction in the length of the atomizer edge and thus a reduction the atomizing capacity, so that only a considerably lower Amount of paint per unit of time with such a bell-shaped rotary atomizer can be processed.

The invention has for its object a spray head to create with the help of which it is possible to create spray patterns with the smallest possible diameter while still having a large amount of paint to generate per unit of time and with comparable atomization quality as in the case of a larger diameter rotary atomizer.

To achieve this object, the invention provides that the spray head has the features of claim 1.

The invention has the result that one for generating a small spray pattern suitable atomizer head despite its small diameter is able to atomize the same amount of paint as before well-known atomizer head with a large diameter. It is essential that Outlet openings with atomizer edges in sufficient numbers on the atomizer head are provided, these outlet openings expediently several atomizer edges arranged one behind the other in the axial direction form. The achievable with such an atomizer head Spray pattern has the desired, small diameter and is nevertheless able to process a large amount of paint per unit of time. Finally, there is also the metallic effect when processing metallic paints an appearance like when using an air atomizing Spray gun. Also penetration of the atomized and electrostatic charged varnish in forms with the effect of a Faraday Cages can be realized better.

Further features of the invention are related to the subclaims with the description and the drawing.

Fig. 1:

Teile eines Rotationszerstäubers im Schnitt;

Fig. 2:

einen Zerstäuberkopf im Schnitt sowie abgebrochen und in größerem Maßstab mit einer gerändelten Zerstäuberkante gemäß Fig. 5;

Fig. 3:

einen Schnitt längs der Linie III - III in Fig. 2, jedoch mit einer glatten Ringfläche neben der Zerstäuberkante;

Fig. 4:

eine Ansicht einer Einzelheit einer Zerstäuberkante mit einer Punktreihe;

Fig. 5:

eine Einzelheit wie in Fig. 4 von einer gerändelten Zerstäuberkante;

Fig. 6:

eine Zerstäuberscheibe im Schnitt mit einer gerändelten Zerstäuberkante;

Fig. 7:

im Schnitt sowie abgebrochen eine abgewandelte Zerstäuberscheibe;

Fig. 8:

im Schnitt sowie abgebrochen eine weitere, abgewandelte Zerstäuberscheibe;

Fig. 9:

einen Schnitt wie in Fig. 2 durch das Halte- und Trageelement des Zerstäuberkopfes.

The invention is described below with reference to exemplary embodiments, which is illustrated in the drawing. Show:

Fig. 1:

Parts of a rotary atomizer in section;

Fig. 2:

an atomizer head in section and broken off and on a larger scale with a knurled atomizer edge according to FIG. 5;

Fig. 3:

a section along the line III - III in Figure 2, but with a smooth ring surface next to the atomizer edge.

Fig. 4:

a view of a detail of an atomizer edge with a row of dots;

Fig. 5:

a detail as in Figure 4 of a knurled atomizer edge.

Fig. 6:

an atomizer disk in section with a knurled atomizer edge;

Fig. 7:

in section and broken off a modified atomizer disc;

Fig. 8:

on average and broken off another modified atomizer disc;

Fig. 9:

a section as in Fig. 2 by the holding and carrying element of the atomizer head.

1 comprises an atomizing head 2, that in a housing 3 in a generally known manner on a shaft 4 is stored. The shaft 4 is a hollow shaft. Located inside there is a feed pipe 5 with holes 6 and 7 for paint or detergent. The holes 6 and 7 lead to a nozzle 8 at the free end of the Feed pipe 5. According to Fig. 2 is also during the Painting process stationary nozzle 2 inside 9 of the atomizer head Second

The drive for the hollow shaft 5 and the supply of the holes 6 and 7 in the feed tube 5 do not differ from known rotary atomizers. The nozzle 8 also serves to guide and dispense the liquid Coating agent or a cleaning agent in principle known way. However, it is useful if the nozzle 8 or their Openings are designed so that there is not a cylindrical spray results, but a fan-shaped beam or a beam in the form of a cone.

The atomizer head 2 comprises an outside according to the embodiment cylindrical holding and carrying element 10, which at the same time for attachment serves at the free end 11 of the shaft. The nozzle 8 is then approximately in the middle of the atomizer head 2.

In the axial direction in front of or in Fig. 2 to the left of the nozzle 8 is a multi-part Atomizer element 12 arranged according to a first embodiment.

The atomizer head 2 has several in the area of the atomizer element 12 arranged circumferentially and at an axial distance from one another Outlet openings 13 for the coating agent or for a cleaning agent on. Each of the outlet openings 13 extends over the entire circumference of the atomizer element 12 or the atomizer head 2. According to the embodiment, there are nine on the atomizer head 2 annular outlet openings 13 are provided.

Each outlet opening 13 includes two circumferentially extending, circular atomizer edges 14. Corresponding to the nine Outlet openings 13, the atomizer head 2 has twice the number of atomizer edges 14 at an axial distance from each other.

For every two atomizer edges 14 there is at least one feed surface 15 and / or at least one feed channel 16 for the liquid to be processed intended.

A plurality of disks 17 are used to form the atomizer edges 14 In the exemplary embodiment, the disks 17 are ring-shaped. The outside diameter all disks 17 are the same according to the embodiment. center bores 18 arranged in the disks 17 are from disk to Disc graduated in such a way that a disc 19 adjacent to the nozzle 8 a hole with the largest diameter and a cover plate 20th or a disk 21 closest to it has the smallest bore diameter have.

The cover plate 20 has a centrally arranged according to the embodiment Exit opening 20 '. This outlet opening 20 'has one Shape and shape similar to a Laval nozzle. Part of the nozzle 8 liquid supplied to the atomizer element 12 emerges from the central one Exit opening 20 'and passes through the centrifugal force over the exposed End face 20 "to the atomizing edge 14 '

All disks 17 and, according to the exemplary embodiment, also the end disk 20 have an annular elevation on their side facing the nozzle 8 or an annular collar 22. The outside diameter of a each annular collar 22 is less than the outside diameter the disc 17. The inner diameter of the collar 22 is larger than that Diameter of the holes 18 in the disks 17. In the assembled Condition are thus slot-shaped grooves 23 on the circumference of the atomizer element 12 and form the outlet openings 13 with the Atomizer edges 14 ..

Many radially directed supply channels lead to each atomizer edge 14 16. They have a triangular one in the area of each federal 22 Cross-section on how this is mainly from the illustration in Fig. 2 in the area the central axis 24 emerges. The area of each federal government 22 Feed channels 16 which are triangular in cross section are in the region of the radially outside lying, annular feed surfaces 15 only notches or grooves shallow depth. The outer, annular feed surfaces 15 are therefore according to the embodiment shown in Figures 2, 5 and 6 knurled.

The notches belonging to the feed channels 16 run radially on the inside 16 'on the respective end face of the disks 17 and 20 on the nozzle side before reaching the holes 18 gradually.

For fastening the disks 17 including those arranged on the end face End plate 20 serve fastening means 25, for example, in shape of screws. They pass through holes 26. These holes 26 are expediently in the region of the collar 22 of the disks 17th

Fastening the disks 17 to one another or to the holding and supporting element 10 is also due to other fastening techniques such as gluing, Clamps etc. possible.

With the fastening means 25 or screws, the disks 17, 20 fixed to the holding and carrying element 10. The holding and carrying element 10 is sleeve or ring-shaped. It is cylindrical on the outside according to FIG. 2 and deposited several times inside, so that it is on the free end 11 of the Shaft 4 is attachable.

The annular disks 17 serving as atomizing disks effect due to the different bore diameters that the liquid flowing from the nozzle 8 into the spaces between the disks 17 distributed. There the liquid is then radially the atomizer edges 14 fed. The variety of atomizer edges available 14 or their total length according to the number of disks 17 enables even with a small diameter of the disks 17 high quality processing of large quantities of paint per unit of time.

In Fig. 3 is a section along the line III - III in Fig. 2, but of one modified atomizer head 2a shown. Basically the same parts have the same reference numbers and index a.

The atomizer head 2a differs from the atomizer head 2 only in that the annular, radially outer feed surface 15a between the collar 22a and the atomizing edge 14a of each disc 17a is not knurled. It is a smooth ring surface.

The detail shown in Fig. 4 relates to a modified disc 17b, which instead of a smooth feed surface 15a is close to the atomizer edge 14b has dotted feed surface 15b.

Further modifications of the discs shown in Figures 2 and 6 17 emerge from FIGS. 7 and 8. So the disc 17c is on the nozzle side provided with an annular cutting edge 27c delimiting the bore 18c. The ring cutting edge 27c radially guides the impinging liquid flow outward onto the adjacent annular surface 28c. Comparable ring areas 28c (FIG. 3) have all disks.

As is also apparent from FIG. 7, a disk 17c can also face one the disc plane 30c angled, the atomizer edge 14c have supporting outer edge 31c. The frustoconical, angled Outer edge 31c directs the liquid flowing radially outward around, reducing their radial acceleration and accelerating tangentially becomes. The feed surface 15c can be smooth or knurled according to FIG. 7 his.

Fig. 8 shows a detail of another disk 17d, which is complete or partially domed. Its feed surface 15d can also be smooth or in accordance with Fig. 8 knurled and knurled grooves 32d like the others Have washers.

The nozzle 8 at the free end of the feed tube 5 produces a conical Liquid flow or a liquid flow in a fan-shaped Shape. This is shown in FIG. 9.

Claims (9)

1. Spray head (2) for an electrostatic rotary atomiser (1) with a nozzle (8) for the feed of a coating medium, particularly a paint or a lacquer, and with several discs (17, 20) which are arranged axially one behind the other and which form atomiser edges (14) at the circumference, wherein the discs (17, 20) each have a respective centrally arranged bore, characterised in that the concentric bores of the discs (17, 20) form an axial distributor channel which is connected with the nozzle (8) and that the diameters of the bores of the discs (17, 20) are reduced in steps from the disc (17) at the nozzle end to the disc (20) remote from the nozzle.
2. Spray head according to claim 1, characterised in that the narrowest bore in the closure disc (20) remote from the nozzle is formed as a central outlet opening (20') in the form of a Laval nozzle.
3. Spray head according to claim 1 or 2, characterised in that the discs (17) have at one end face thereof or at both sides an annular collar (22) for mutual contacting.
4. Spray head according to one of claims 1 to 3, characterised in that the discs (17) have feed surfaces (15, 28) and feed channels (16).
5. Spray head according to one of claims 1 to 3, characterised in that the discs (17c) are bent over in frusto-conical manner in the region of the atomiser edge (14c).
6. Spray head according to one of claims 1 to 5, characterised in that the discs (17d) are curved at least in part.
7. Spray head according to one of claims 1 to 6, characterised in that the discs (17c) have at the nozzle side an annular cutting edge (27c) bounding the bore (18c).
8. Spray head according to one of claims 1 to 7, characterised in that the discs (17) have notches at the end face.
9. Spray head according to one of claims 1 to 8, characterised by a variable number of the discs (17).

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