EP1685909B1 - Rotary atomizer for saving rinsing agent - Google Patents

Abstract

Rotational sprayer has a symmetrical bell-shaped body (1) with nose part (2), cover part (3) with divergent surface (8) and steering gas ring (7) with at least one steering gas nozzle (13,13'). The divergent cover has a shoulder (11) between nose and cover part, which extends ring-like around the nose part and denotes an angle of at least 90[deg] of the exterior surface to the spray device. The nozzle is arranged so that its spray (14) hits the cover part inside the shoulder.

Description

The invention relates to a rotary atomizer with the features of the preamble of claim 1. Such a rotary atomizer can be used commercially, for example, for the automatic painting of automobile bodies in the mass production of automobiles.

Such rotary atomizers usually have a rotatable bell body which has a hub part for connection to a drive motor and a jacket part for spraying the coating material. The drive motor is, for example, a compressed-air motor, with the aid of which the bell-shaped body can be rotated at very high speed (a few 10000 revolutions per minute). The resulting centrifugal forces act on the liquid coating material to be atomized, which is introduced into the bell body, and accelerate it in the shell part in the direction of a spray edge, where it leaves the bell body in the form of a mist of small droplets (spray), is entrained by a gas stream and accelerated in the form of a Zerstäuberstrahls towards a substrate to be coated.

In such Rotationszerstäubern the problem may occur that parts of the coating material undesirable to settle on the outer surface of the shell portion of the bell body, for example due to splashes or Rückspritzern. These deposits or residues may become detached from the shell portion during subsequent coating operations and adversely affect the quality of the coating. This problem is particularly evident when the coating material is a paint of a certain color and in a subsequent coating process a paint of a different color is used. If residues of a preceding coating process dissolve in a subsequent coating process, the subsequently applied paint may contain particles of the first paint having a different color. Such a coated substrate may be unusable.

This problem is already known in the art. From the European Patent EP 0 715 896 B1 For example, a rotary atomizer with a bell body, in which a rinsing agent can be passed through special holes and channels within the bell body on its lateral outer surface, so that it can be cleaned between two coating operations. The rinsing agent is thereby moved by the centrifugal forces due to the rotation of the bell body through the holes or channels. It passes into a U-shaped annular space which lies on the outer surface of the bell body in the region of the transition between the hub part and the shell part and surrounds the hub part annularly. The opening of the U of the U-shaped annular space is facing away from the interior of the bell body. As a result of the centrifugal forces, the rinsing agent flows via the radially outer edge delimiting the annular space to the outer surface of the casing part of the bell body and is distributed over it. The rotary atomizer also points Air nozzle rings, the jet of which meets the shell part of the bell body outside the U-shaped annular space. The rotary atomizer has a relatively complicated construction. Furthermore, there is a risk that deposits in the U-shaped annulus coating material, so for a satisfactory cleaning result relatively much detergent must be used, which adversely affects the operating costs.

The term "cleaning result" is understood to mean the completeness of the removal of coating material residues on the outer surface of the shell part of the bell body. The less disturbing coating material residues remain on the outside surface of the jacket after a cleaning process, the better the cleaning result.

From the U.S. Patent 6,341,734 B1 Another rotary atomizer with a bell body emerges. The outer surface of the skirt portion of the bell body has no recess, such as the above-mentioned U-shaped annulus, in which coating material could settle. In the bell body bores or channels are provided for a rinsing agent, which open directly to the outer surface of the shell part in the region of the transition between the hub part and the shell part. In the area of the mouths, the lateral surface has a flattened shoulder area. Furthermore, steering gas nozzles are provided, the nozzle jets outside of the shoulder region, radially spaced meet the shell part to the mouths. The rotary atomizer has a simpler construction, but the distribution of the rinsing agent on the outer surface of the lateral surface of the bell body is unsatisfactory, so relatively much detergent must be used to achieve a good cleaning result.

From the EP 0 463 742 A2 is a rotary atomizer with a rotationally symmetrical bell body is known in which air is guided parallel to a lateral surface of the bell body from several gas nozzles substantially parallel. Furthermore, additional nozzles are provided, which are directed approximately radially against a substantially cylindrically shaped hub region. A purge passage is directed to a diverging portion of the bell body.

From the US 5,914,153 goes out a rotary atomizer with a bell body, which manages without a steering gas jet. For cleaning the bell is provided to spray a spraying liquid from directed against a lateral surface of the bell spray nozzles.

Furthermore, from the JP 06218301 A a rotary atomizer is known in which a plurality of gas jets are directed onto a lateral surface of the bell.

Against this background, it was an object of the present invention to provide a rotary atomizer, which has a simple construction and in which for the cleaning of the outer surface of the shell part of his bell body little detergent must be used to achieve a good cleaning result.

The o. G. Task is solved by the object defined in the main claim. Preferred embodiments are defined in the subclaims.

The subject of the present invention is accordingly a rotary atomizer with a rotationally symmetrical bell body, which has a hub part for connection to a drive motor, and a jacket part for spraying a coating material in the form of a spray, wherein the discharge direction is parallel to the axis of rotation, further comprising a steering gas ring which is arranged around the hub part symmetrical to the axis of rotation and which comprises a plurality of spray gas nozzles aligned in the discharge direction and forming at least one nozzle ring for shaping the spray, wherein the shell portion has a diverging outer surface extending from the transition between the hub portion and the shell portion to a spray-off edge of the shell portion, further comprising at least one outer scavenging passage for guiding a flushing agent to the diverging outer surface. According to the invention, the diverging outer surface at the transition between the hub part and the jacket part has a shoulder region which extends annularly around the hub part, and in the tangent to the outer surface with the spray direction enclose an angle of at most 90 °. Here are the gas nozzles arranged so that its jet jet hits the shell part within the shoulder region.

In this case, the at least one outer scavenging duct opens into the at least one nozzle ring. Thereby, the rinsing agent can be distributed in a cleaning process by the steering gas flow on the outer surface of the shell part. In fact, in the context of the present invention, it has been shown that a very uniform distribution of rinsing agent can be achieved, so that only a small amount of rinsing agent has to be used in order to achieve a good cleaning result. Furthermore, there is the possibility of performing a rinsing process with a good cleaning result and low consumption of detergent even at a standstill, i. without the bell body being rotated, in particular if more than one gas turbine nozzle is provided. In addition, the possibility opens up to clean the gas nozzles with detergent, since the coating material can spray back under unfavorable circumstances up to the shaping air nozzles and can be distracting there.

The spraying direction does not reflect the trajectory of individual droplets of the spray, but the direction of the entire atomizing jet or spray cone.

The coating material is preferably a paint in question.

Air is preferably used as the steering gas, since air is the cheapest and most easily available and manageable gas. However, it is also conceivable that other gases are used as a steering gas, for example an inert or inert gas, when air-sensitive coating materials are atomized.

The term "rinsing agent" in the context of the present invention also encompasses solvents, cleaning agents and other liquid agents which are suitable for removing coating material residues.

The jet of the gas nozzles meets according to the invention within the shoulder region on the shell part. Since a nozzle jet generally has no hundred percent defined extent, insignificant parts of the jet, which are arranged in its edge region, inadvertently also hit the shell part outside of the shoulder region. It is crucial that the center and the essential parts of the jet meet within the shoulder area on the shell part.

The rotary atomizer according to the invention with bell body has a simple construction. Due to the nozzle jet of the gas-jet nozzles striking the jacket part in the shoulder region, a steering gas flow which engages closely and well on the outer surface of the jacket part is produced which, in conjunction with the rotation, produces a spray jet that is particularly well aligned in the direction of discharge. As a result, very little or even no coating material spatters or splashbacks are produced, which are distracting on the outer surface of the jacket part and have to be removed by cleaning and applying detergent. Furthermore, the washing agent used by the improved rinsing agent is distributed more evenly on the outer surface to be cleaned. Both causes flushing for the cleaning of the outer surfaces of the skirt portion of the bell body can be saved without the cleaning result deteriorates. In addition, the well-aligned and concentrated atomizer jet produces little overspray, so that coating material can be saved and the painting result improved. Due to the simple construction, the production costs for the rotary atomizer according to the invention are relatively low.

In one embodiment of the rotary atomizer according to the invention, the steering gas ring has at least one nozzle ring, wherein at least the nozzles of the nozzle ring with the smallest radial distance from the hub are arranged so that their jet jet strikes the jacket part within the shoulder region. The gas nozzles are preferably equidistant distributed on a radius around the hub part around arranged. As a result, an even more improved stream of steering gas can be generated with acceptable complexity of the device, resulting in even less coating material residues that need to be removed by washing up, and consequently also the distribution of the rinsing agent is even more uniform and thus detergent-saving.

In a further development, the steering gas ring has at least one further, outer nozzle ring, the nozzles of which have a greater radial distance from the hub than the nozzles of the inner nozzle ring and whose jet nozzle strikes the casing part outside the shoulder region. As a result, an even better atomized spray jet can be generated.

In a further development of the steering gas ring is integrally formed with the bell body. As a result, the radial distance between the gas nozzles and the hub part is fixed so that no misalignment can take place. As a result, a deterioration of the steering gas flow can be prevented by misalignment, so that a consistent quality of the coating result, a consistently small amount of coating material residues and a consistently good distribution of the detergent is guaranteed.

In one embodiment of the rotary atomizer according to the invention include tangents to the outer surface in the shoulder region with the discharge direction an angle of 70 to 90 °. Such a trained shoulder area, in cooperation with the rotation and / or the steering gas flow supports the uniform distribution of detergent on the outer surface of the shell portion of the bell body and contributes thus to improve the cleaning result and to save detergent.

In a further embodiment of the rotary atomizer according to the invention, the outer surface of the shell part is bell-shaped. This is a flow-dynamic favorable form, which supports the formation of a tight-fitting stream of steering gas for the optimal distribution of detergent on the shell part and thus contributes to reducing the need for flushing.

In a further development of the bell body is formed so that adjacent to the shoulder region with respect to the axis of rotation curved outward area. This geometric shape has been found to be particularly favorable in terms of flow dynamics in order to bring about a closely fitting stream of steering gas.

The bell body may further comprise at least partially, preferably in the region of the outer surface, a coating with an anti-adhesive agent. The non-stick agent provides low adhesion of coating material splashes or re-spatters, so less or even no flushing agent must be used to remove coating residue. In this case, the coating material splashes or back splashes adhere poorly or not on the bell body, but still flow during the coating process, for example due to rotational centrifugal forces, substantially completely. If the bell body has such a non-stick coating, fewer outer rinsing channels may possibly be provided. If no rinsing agent is needed at all to remove the coating material splashes or back splashes, because these drain, for example, completely, it may possibly even be completely dispensed with external rinsing channels.

The antiblocking agent may be a nanoparticulate composition. The use of nanoparticles has the advantage that surfaces can be created with tailor-made properties, in particular with particularly low free energy, at which very little coating material splashes or back splashes adhere, so that their removal requires very little flushing agent.

Suitable anti-adhesive agents can be purchased, for example, from the company NANO-X GmbH, namely u.a. as coating agents which impart so-called "easy-to-clean" and non-stick properties to a surface treated therewith, and as additives for coating compositions, paints and inks. A suitable non-stick agent of this company is, for example, x-clean® EC 4008.

In a preferred embodiment of the rotary atomizer according to the invention, the at least one outer scavenging duct opens onto the outer surface at the transition between the hub part and the jacket part. This has proven to be particularly advantageous with regard to the most uniform distribution of detergent on the outer surface of the shell part.

It is further preferred if at least two outer rinsing channels are provided. As a result, detergent can already fairly evenly distributed on the outer surface of the casing part be applied before it is further distributed there, without increasing the design effort for the rotary atomizer beyond measure.

In a likewise preferred embodiment of the rotary atomizer according to the invention, at least two outer rinsing channels are provided, of which at least one first opens out at the transition between hub part and jacket part onto the outer surface and at least one second opens into at least one nozzle ring. Thereby, the advantages of the two embodiments disclosed above can be combined.

In a further development, at least two first outer rinsing channels are provided. As a result, rinsing agents can be applied evenly distributed evenly on the outer surface of the shell part before it is further distributed there without the design effort for the rotary atomizer increases beyond the measures.

In a variant of the rotary atomizer according to the invention, the spray-off edge has at least one guide element for the coating material. This promotes the formation of particularly small drops of coating material. It has been found that the smaller the coating material droplets, the lower the risk of coating material spatters or reverse spatters. The smaller the droplets of coating material, the less coating material splashes or back splashes have to be removed so that it is expensive to wash.

The at least one guide element can be formed as grooves, which is technically particularly easy to implement, for example by milling of channels. The grooves may also be radially aligned with respect to the axis of rotation, be inclined in or against the direction of rotation, be formed as cross grooves or the like. Through the grooves, the coating material is passed to the spoiler edge to the outside. As a result, the coating material is clean on the inner surface of the shell part and leaves the trailing edge in a precisely defined manner as a channeled droplet jet. This prevents turbulence at the trailing edge, which could lead to coating material splashes or back splashes.

Fig. 1

einen Ausschnitt aus einer Ausführungsform eines gattungsgemäßen Rotationszerstäubers;

Fig. 2

einen Ausschnitt aus einer Ausführungsform eines erfindungsgemäßen Rotationszerstäubers;

Fig. 3

einen Glockenkörper eines erfindungsgemäßen Rotationszerstäubers mit Leitelement;

Fig. 4

einen Zerstäuberstrahlen (a) eines erfindungsgemäßen Rotationszerstäubers; (b) eines herkömmlichen Rotationszerstäubers.

The invention will be explained in more detail with reference to the concrete embodiments shown in the figures and the accompanying description. Show

Fig. 1

a section of an embodiment of a generic rotary atomizer;

Fig. 2

a detail of an embodiment of a rotary atomizer according to the invention;

Fig. 3

a bell body of a rotary atomizer according to the invention with guide element;

Fig. 4

an atomizing jet (a) of a rotary atomizer according to the invention; (b) a conventional rotary atomizer.

Fig. 1 shows an embodiment of a generic rotary atomizer. Schematically illustrated is a section of a cross section through a generic rotary atomizer. The rotary atomizer has a rotationally symmetrical bell body (1) with a hub part (2) for connection to a drive motor (not shown), a shell part (3) for spraying a coating material in the form of a spray and a transition (4) between the hub part (2) and Sheath part (3). Furthermore, the axis of rotation (5) is illustrated. The spraying direction is illustrated by the arrow (6). Fig. 1 further shows a part of a steering gas ring (7), which is arranged symmetrically around the hub part (2). The casing part (3) has an outer surface (8) which diverges in the discharge direction (6) and which extends from the transition (4) of the hub part (2) over the casing part (3) to the spray-off edge (9). extends. On the outer surface (8) may be applied an anti-adhesive agent (not shown).

The bell body (1) has an outer rinsing channel (10), through which a rinsing agent can be conducted from a supply line (not shown) in the interior of the hub part (2) onto the outer surface (8). The outer rinsing channel (10) opens at the transition (4) to the outer surface (8). Shown is only an outer rinsing channel (10); however, the rotary atomizer may have two or more outer rinsing channels (10).

At the transition (4) between the hub part (2) and the casing part (3), the bell body (1) has a shoulder region (11) in which tangents (12) to the outer surface (8) with the discharge direction (6) parallel to the axis of rotation (5) is an angle α of about 85 °. The shoulder region (11) extends annularly around the hub part (2).

The steering gas ring (7) is substantially rotationally symmetrical, with the axis of rotation (5) as the axis of symmetry. It has two nozzle rings, which are formed by forty inner gas nozzles 13 (inner nozzle ring) and forty outer gas nozzles (13 ') (outer nozzle ring), wherein the gas nozzles (13, 13') of a nozzle ring arranged distributed equidistantly on a radius are. For reasons of clarity, however, only four gas nozzles are shown, of which only two are designated (13, 13 '). The steering gas nozzles (13, 13 ') are aligned in the discharge direction (6) in order to form a spray of sprayed coating material. In this case, the guide gas nozzles (13) of the inner nozzle ring are arranged so that their jet (14) in the shoulder region (11) on the casing part (3). The nozzle jets (14 ') of the steering gas nozzles (13') of the outer Nozzle crowns meet outside the shoulder area (11) on the shell part (3). For the sake of clarity, only two jets (14, 14 ') are representative of all jets of the gas nozzles (13, 13').

The outer surface (8) is bell-shaped. In this case, adjacent to the shoulder region (11) adjoins an area in which the jacket part (3) is curved outwardly with respect to the axis of rotation (5). This is adjoined by another area in which the casing part (3) widens conically outward.

Further details of a rotary atomizer are known in principle to the person skilled in the art. They are therefore not shown for reasons of clarity.

Fig. 2 shows an embodiment of the present invention. Schematically illustrated is a section of a cross section through a rotary atomizer according to the invention. The rotary atomizer is constructed similar to the rotary atomizer Fig. 1 , However, has the following differences: bell body (1) and steering gas ring (7) are integrally formed; External rinsing channels (10, 10 ') are provided, which open into the inner nozzle ring or inner steering gas nozzles (13) so that rinsing agents are conducted from a supply line (not shown) in the interior of the hub part (2) into the steering gas nozzles (13) can, from where it can be applied by means of the flow of steering gas on the outer surface (8) and can be evenly distributed there. Only two outer rinsing channels (10, 10 ') are shown, but the rotary atomizer can have more outer rinsing channels. Not shown are further Außenspülkanäle that at the transition (4) between the hub part (2) and the shell part (3) open onto the outer surface (8), as they may be provided in a further embodiment of the present invention.

Fig. 3 shows the rotary atomizer Fig. 1 which has a conductive element (15) for the coating agent to promote the formation of particularly small coating agent droplets. The guide element is mounted along the spray-off edge (9) and in the form of longitudinal grooves (16) which are milled into the spray-off edge (9). Of the longitudinal grooves (16) seventeen are shown, wherein the sake of clarity, only one, is representative of all, provided with a reference numeral.

Fig. 4 Figure 2 shows a comparison between simulated trajectories of coating agent droplets in (a) a rotary atomizer according to the invention and (b) a prior art rotary atomizer not according to the invention. It can be clearly seen that the steering air flow from the steering gas ring (7) in the case of the rotary atomizer according to the invention (a) fits tightly against the bell body (1) and thereby forms a clean, well-aligned and bundled atomizing jet (18) in which only very few coating agent residues such as splashes or back splashes are to be feared. In contrast, in the case of the rotary atomizer (b) not according to the invention, the steering air flow is unclean, so that a diffuse atomizing jet (18) forms, in which many coating agent residues, in particular from the secondary jet (17), are to be feared, the solvents must be removed expensively ,

The comparison thus shows that in the simply constructed rotary atomizer according to the invention for the cleaning of Outside surface (8) only a small amount of detergent must be used to achieve a good cleaning result.

LIST OF REFERENCE NUMBERS

1

bell body

2

hub part

3

jacket part

4

Transition between hub part and shell part

5

axis of rotation

6

Absprührichtung

7

Steering gas ring

8th

Outer surface of the shell part

9

spray edge

10, 10 '

Außenspülkanäle

11

shoulders

12

tangent

13, 13 '

Steering gas nozzles

14, 14 '

jets

15

vane

16

longitudinal groove

17

secondary beam

18

Zerstäuberstrahl

Claims (16)

1. A rotary atomizer with a rotationally symmetrical bell body (1) that features a hub part (2) for producing a connection with a driving motor, as well as a shell part (3) for ejecting a coating material in the form of a spray, wherein the ejecting direction extends parallel to the rotational axis (5), with a steering gas ring (7) that is arranged around the hub part (2) symmetric to the rotational axis (5) and features several steering gas nozzles (13, 13') that are aligned in the ejecting direction and form at least one nozzle collar in order to produce the spray, wherein the shell part (3) features a diverging outer surface, and with at least one outer rinsing channel (10, 10') for guiding a rinsing medium onto the diverging outer surface, wherein the diverging outer surface features a shoulder region (11) at the transition between the hub part (2) and the shell part (3), wherein this shoulder region extends annularly around the hub part and tangents on the outer surface include an angle of no more than 90° with the ejecting direction (6) in said shoulder region, and wherein the steering gas nozzles (13, 13') are arranged in such a way that their jet impacts on the shell part within the shoulder region (11), characterized in that the diverging outer surface extends from the transition between the hub part (2) and the shell part (3) up to an ejecting edge (9) of the shell part, wherein the at least one outer rinsing channel (10, 10') leads into the at least one nozzle collar.
2. The rotary atomizer according to Claim 1, characterized in that at least the nozzles of the nozzle collar with the smallest radial distance from the hub (2) are arranged in such a way that their jet impacts on the shell part (3) within the shoulder region (11).
3. The rotary atomizer according to Claim 2, characterized in that the steering gas ring (7) features at least one additional outer nozzle collar, the nozzles of which are arranged at a greater radial distance from the hub (2) than the nozzles of the inner nozzle collar and the jets of which impact on the shell part (3) outside the shoulder region (11).
4. The rotary atomizer according to one of Claims 1 to 3, characterized in that the steering gas ring (7) is realized in one piece with the bell body (1).
5. The rotary atomizer according to one of Claims 1 to 4, characterized in that tangents on the outer surface include an angle between 70 and 90° with the ejecting direction in the shoulder region (11).
6. The rotary atomizer according to one of Claims 1 to 5, characterized in that the outer surface of the shell part (3) is realized in a bell-shaped fashion.
7. The rotary atomizer according to one of Claims 1 to 6, characterized in that a region that is curved outward referred to the rotational axis (5) borders on the shoulder region (11).
8. The rotary atomizer according to one of Claims 1 to 7, characterized in that at least sections of the bell body (1) feature a non-stick coating.
9. The rotary atomizer according to Claim 8, characterized in that the non-stick coating consists of a composition that contains nanoparticles.
10. The rotary atomizer according to one of Claims 1 to 9, characterized in that the at least one outer rinsing channel (10, 10') leads onto the outer surface at the transition between the hub part (2) and the shell part (3) .
11. The rotary atomizer according to Claim 10, characterized in that at least two outer rinsing channels (10, 10') are provided.
12. The rotary atomizer according to one of Claims 1 to 9, characterized in that at least two outer rinsing channels (10, 10') are provided, wherein at least one first outer rinsing channel leads onto the outer surface at the transition between the hub part (2) and the shell part (3) and at least one second outer rinsing channel leads into at least one nozzle collar.
13. The rotary atomizer according to Claim 12, characterized in that at least two first outer rinsing channels are provided.
14. The rotary atomizer according to one of Claims 1 to 13, characterized in that the ejecting edge (9) features at least one guide element for the coating material.
15. The rotary atomizer according to Claim 14, characterized in that the at least one guide element (15) is realized in the form of grooves.
16. The rotary atomizer according to Claim 15, characterized in that the grooves are aligned radially referred to the rotational axis, inclined in or opposite to the rotating direction or realized in the form of cross-grooves.

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