EP3034175A1 - Rotary nozzle for an atomiser head - Google Patents

Abstract

A nozzle head for a rotary atomizer for applying a coating material to an object comprises a rotatable around a rotation axis bell cup having a spoiler edge and an outflow surface to which the coating material can be fed such that the coating material is thrown off the trailing edge of the bell cup. Coating material can be fed to the outflow surface via a flow path. The flow path is divided in a discharge region in partial paths, each with a to the axis of rotation of the bell cup eccentrically arranged discharge opening, from which the coating material can be dispensed, which passes from there to the discharge surface. In addition, a rotary atomizer is specified with such a nozzle head.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

1. a) einem um eine Rotationsachse drehbaren Glockenteller mit einer Abrisskante und einer Abströmfläche, welcher das Beschichtungsmaterial derart zuführbar ist, dass das Beschichtungsmaterial von der Abrisskante des Glockentellers weggeschleudert wird, und
2. b) einem Strömungsweg, über welchen das Beschichtungsmaterial der Abströmfläche zuführbar ist.

The invention relates to a nozzle head for a rotary atomizer for applying a coating material to an article with:

1. a) a rotatable about an axis of rotation bell cup having a trailing edge and an outflow surface to which the coating material is supplied such that the coating material is thrown off the trailing edge of the bell cup, and
2. b) a flow path, via which the coating material can be fed to the outflow surface.

Moreover, the invention relates to a rotary atomizer for applying a coating material to an article with a nozzle head.

2. Description of the Related Art

Rotary atomizers equipped with a nozzle head of the type mentioned above are used, for example, in the automotive industry to paint or coat articles such as parts of vehicle bodies with a protective material.

The bell-shaped plate thereby serves to atomize the coating material, by means of which he in operation at very high rotational speeds of 10,000 to 100,000 min ^-1 U a pneumatic or electric drive is rotated about its axis of rotation.

The rotating bell cup is supplied with the selected coating material. Due to centrifugal forces, which act on the coating material, it is driven on the bell cup as a film to the outside, until it reaches a radially outer spoiler lip of the bell cup. There, such high centrifugal forces act on the coating material that it is thrown tangentially in the form of fine coating material droplets.

This produces droplets of different sizes, which extend over a relatively large size range. Larger droplets are thrown radially further outward than smaller droplets. With nozzle heads and rotary atomizers of the type mentioned so a relatively wide spray is generated, which is conical in the ideal case and has a relatively large cone angle.

It is desirable that the size of the droplets is relatively uniform and that the droplet spectrum related to the size extends only over the smallest possible area. In addition, the droplets should be as small as possible, since with smaller droplets a more homogeneous coating result is achieved. The aim is to create a so-called paint mist. Mist is generally referred to as a mixture of air and finely divided solid or liquid particles. In order to ensure the application of the coating material to the article to be coated, a weeping mist with a minimum droplet size is Range 20 to 40 microns necessary. Good results can be achieved with a droplet size mean of 100 microns, the deviation is ideally ± 50 microns.

The slower the bell cup is rotated, the larger are the droplets on average, which are thrown off the trailing edge. Accordingly, at higher rotational speeds of the bell cup smaller average droplets are generated at the trailing edge of the bell cup. For this reason, the bell cup is usually operated at high speeds, which is associated with a corresponding high energy consumption. At the same time, the radial spread of the spray at higher speeds is again greater than at lower speeds, so that measures must be taken to focus this spray on the objects to be coated.

For this purpose, known rotary atomizers work electrostatically, for example. In this case, the coating material to be applied is charged, whereas the object to be coated is grounded. In this case, an electric field is formed between the rotary atomizer and the object, through which the charged coating material is applied to the object in a directionally directed manner. However, this only works with electrically conductive objects.

Alternatively or in addition to the electrostatic operation steering air devices have established in known rotary atomizers. With these, a mostly ring-shaped shaping air flow is directed onto the spray jet in such a way that it is bundled and the droplets of different sizes are directed onto the object to be coated. Partially For this purpose, however, strong steering air flows are necessary, the generation of which is relatively complicated.

From the DE 43 30 602 A1 For example, a rotary atomizer for electrostatic coating with a static nozzle assembly having a plurality of coating material nozzles communicating with respective coating material sources via different channels is known. Each nozzle and the connected channel are used to supply only a particular coating material.

This requires a very complex internal structure of the rotary atomizer and thus increased production costs. Furthermore, there is a risk that coating material, which is in the single channel for a longer period of time, forms deposits on the channel walls. When the channel is used again, these deposits can become detached and lead to an unusable coating result.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a nozzle head and a rotary atomizer of the type mentioned, with which an energy-efficient operation is possible with a possible homogeneous and focused spray.

• c) der Strömungsweg sich in einem Abgabebereich in Teilwege mit jeweils einer zur Rotationsachse des Glockentellers exzentrisch angeordneten Abgabeöffnung aufteilt, aus welcher das Beschichtungsmaterial abgebbar ist, das von dort zur Abströmfläche gelangt.

This object is achieved with the nozzle head of the type mentioned in that

• c) the flow path is divided into a delivery area in partial paths, each with a to the axis of rotation of the bell cup eccentrically arranged discharge opening, from which the coating material can be dispensed, which passes from there to the discharge surface.

In the case of a central feed of the coating material to the deflecting body via a coaxially arranged channel, depending on the viscosity of the coating material, the latter may have too low a velocity in the radial and in the circumferential direction in order to form the desired material film on the outflow surface.

The invention is based on the recognition that, when the coating material is passed through a plurality of partial paths through a discharge region with radially offset delivery openings with respect to the axis of rotation, a more uniform delivery to the outflow surface is possible than with a single central supply channel.

In particular, it can be provided that the discharge openings are rotatably mounted about the rotation axis. In this case, the coating material undergoes an additional acceleration in the radial and in the circumferential direction by a rotational movement of the discharge openings about the rotation axis, so that it impinges on the deflection body with the corresponding additional speed components and reaches the outflow surface. This additional kinetic energy is also available to the coating material when flowing along the outflow surface in the direction of the spoiler edge. As a result, the coating material can detach from the tear-off edge at a greater speed without the operating rotational speed of the rotary atomizer having to be increased.

By dividing the flow path into partial paths, a smaller cross section becomes effective in each partial path. If the total cross section of the partial paths is smaller than the cross section of the flow path, the flow rate increases proportionally due to the conservation of mass in the case of an incompressible coating material. As a result, the absolute speed of the coating material can be further increased.

In this way, the generated droplet size can be effectively reduced without having to increase the rotational speed of the rotary atomizer.

Preferably, the discharge area has at least two discharge openings, which are arranged on a circle coaxial with the axis of rotation. In order to prevent a periodicity being visible in the coating result, which is coupled to the operating speed, it is expedient to distribute the partial paths with the discharge openings evenly around the circumference. It can thereby be achieved that, during the rotation of the bell cup on the outflow surface, a coating material film which is continuous in the circumferential direction can form, so that droplets can be ejected per unit of time from as large a peripheral area as possible.

In one embodiment, it is provided that the flow path comprises a coaxial central channel, which is arranged in the flow direction of the coating material in front of the delivery area.

It is advantageous if at least the coaxial central channel is received in a drive shaft with which the bell cup is coupled.

The coating material emitted by the discharge openings can reach the outflow surface by being guided onto a deflecting body. The deflecting body is preferably arranged coaxially to the axis of rotation and immovably connected to the bell cup. Furthermore, the deflecting body is rotationally symmetrical and comprises a baffle surface, which is opposite to the discharge openings, and an outer lateral surface, which extends substantially parallel to the outflow surface of the bell cup.

Thus, the deflecting body is formed as easily as possible, it is preferably designed as a hollow truncated cone.

During operation, a negative pressure is created in the inner region of the bell cup, so that there is a risk that coating material will be sucked from the spoiler edge to the center of the bell cup. This in turn affects the geometry of the spray. In order to prevent the coating result from deteriorating as a result, it is advantageous if through the deflecting bodies defining the baffle surface continuous air passage bores are provided which ensure pressure equalization.

The deflection body is accommodated in the space defined by the outflow surface of the bell cup, which also has the shape of a truncated cone. It is advantageous if the diameter of the deflecting body is less than 60% of the demolition edge diameter. Particularly advantageous is a Umlenkkörperdurchmesser, in about one third the demolition edge diameter is. The demolition edge diameter can be in a range between 20 and 90 mm, whereby with a larger spoiler edge correspondingly more outflow surface is available. This can form a thin coating agent film, causing smaller and more uniform droplets.

In order to save energy, it is expedient to design the rotating components as easily as possible. The nozzle head can be formed from a bell part, which comprises the bell cup and the delivery area, and from a conical side wall such that a cavity is created between the bell part and the side wall. The side wall and the bell part can be connected to each other immobile example by gluing, welding, screwing, riveting or shrinking.

It is advantageous if a material with a low density is used as the material for the bell part, the side wall and the deflection body, so that the masses to be moved are kept as small as possible. Depending on the coating material and abrasion by particles in the coating material, suitable materials are, for example, titanium, aluminum or alloys such as Ti-6Al-4V, 6Al-4V or 6Al-25N-4Zr-2Mo.

Furthermore, it can be provided that the outflow surface has grooves in an annular region, in particular radial grooves. In particular, it can be provided that the grooves are arranged in a radially outermost annular region of the outflow surface which terminates in the tear-off edge. This creates initial spots for droplet formation.

Alternatively or additionally, in an annular region, an angle between the outflow surface and the rotation axis in the direction of the tear-off edge may become smaller. It is particularly advantageous if the angle changes continuously in a radially outermost annular region of the outflow surface. Due to the deflection of the coating material, a droplet detaching from the trailing edge undergoes a reduced acceleration in the radial direction, so that the maximum radius of the spray jet can be reduced.

In addition, it can be provided that the angle between the outflow surface and the axis of rotation changes several times in the direction of the spoiler edge, wherein different annular regions of the outflow surface each have different constant angles in a range of 50 ° to 85 °. By means of such steps, regions with different flow conditions can be produced on the outflow surface in which the coating material experiences different acceleration components. For a uniform droplet size distribution, laminar flow of the coating material is desirable. To ensure this, the transitions between the ring areas are as steady as possible to carry out with continuously changing angle.

Furthermore, it can be provided that a shaping air device is used for bundling the spray jet. This preferably has a plurality of steering air units, which are designed as nozzle rings. These are arranged coaxially with the axis of rotation on the housing of the rotary atomizer outside the nozzle head and may have nozzle openings of different sizes. Here, a flow rate of 200 to 350 L min ^{-1 has} proved to be useful.

For further focusing of the spray, the coating material can be directed by means of an electric field to the object to be coated. It can be provided that the coating material itself is directly charged by means of a high voltage generator to high voltage of 20 to 50 kV, preferably 30 kV, within the flow path and the object to be coated is grounded.

Alternatively, the electrostatic charge may be externally provided by needle electrodes mounted radially around the bell and at negative DC potential. The voltage is in the range between -40 kV and -100 kV. The electrons produced by the ionization of the air in front of the needle tips can negatively charge the droplets so that they move in the direction of the grounded article to be coated, whereby the coating efficiency can be increased.

In order to remove soiling on the rotary atomizer, which results from coating material not reaching the object to be coated, a rinsing agent spraying device may be provided. This can be arranged on the side wall of the bell part and clean it if necessary.

When changing the coating material, the entire flow path is flushed with solvent to avoid mixing. To express remnants of the coating material from the feed lines or to clean them of the solvent, a reciprocating pig can be used, which when passing through the Line section whose inner surface freed from the fluid.

The described nozzle head is part of a paint sprayer for coating objects which can have many color sources of up to 50 different colors. The paint spray device may comprise a plurality of spray booths, which are supplied with coating material with associated distribution lines. In each spray booth, there may be a plurality of robots or handling means carrying rotary atomizers.

Furthermore, there are one or more color change valves, so that there is always only one color between color changer and atomizer in the line. There may be additional dosing and storage container between color changer and atomizer, the exact arrangement of the storage container and color changer is not relevant. The above object is achieved in a rotary atomizer of the type mentioned in that a nozzle head with some or all of the above mentioned features is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Figur 1

einen Axialschnitt eines ersten Ausführungsbeispiels eines Düsenkopfes mit einer Vollwelle als Antriebswelle;

Figur 2

einen Radialschnitt eines Abgabebereichs des Düsenkopfes nach Figur 1, in welchem Teilwege des Strömungswegs verlaufen;

Figur 3

einen Axialschnitt eines zweiten Ausführungsbeispiels eines Düsenkopfes mit einer Hohlwelle als Antriebswelle;

Figur 4

einen Radialschnitt des Abgabebereichs des Düsenkopfes nach Figur 3, in welchem Teilwege des Strömungswegs verlaufen;

Figur 5

einen Axialschnitt eines dritten Ausführungsbeispiels eines Düsenkopfes mit einer Hohlwelle als Antriebswelle;

Figur 6

einen Radialschnitt des Abgabebereichs des Düsenkopfes nach Figur 5;

Figur 7

einen Axialschnitt eines vierten Ausführungsbeispiels eines Düsenkopfes, bei dem ein Einsatzteil in einer Zentralbohrung des Abgabebereichs angeordnet ist;

Figur 8

einen Radialschnitt des Abgabebereichs des Düsenkopfes nach Figur 7.

Embodiments of the invention will be explained in more detail with reference to the drawings. In these show:

FIG. 1

an axial section of a first embodiment of a nozzle head with a solid shaft as the drive shaft;

FIG. 2

a radial section of a discharge region of the nozzle head after FIG. 1 in which partial paths of the flow path run;

FIG. 3

an axial section of a second embodiment of a nozzle head with a hollow shaft as the drive shaft;

FIG. 4

a radial section of the discharge area of the nozzle head after FIG. 3 in which partial paths of the flow path run;

FIG. 5

an axial section of a third embodiment of a nozzle head with a hollow shaft as the drive shaft;

FIG. 6

a radial section of the discharge area of the nozzle head after FIG. 5 ;

FIG. 7

an axial section of a fourth embodiment of a nozzle head, wherein an insert member is disposed in a central bore of the discharge area;

FIG. 8

a radial section of the discharge area of the nozzle head after FIG. 7 ,

DESCRIPTION OF PREFERRED EMBODIMENTS 1. Basic structure of the rotary atomizer.

In the figures, 10 designates a total of a rotary atomizer, of which only a head portion with a housing 12 and a nozzle head 14 is shown. By means of the rotary atomizer 10 coating material, in particular paint, can be applied to a not specifically shown item.

The nozzle head 14 comprises a bell member 24 which is rotatable at high speed about a rotation axis 16 and for this purpose is coupled to a drive shaft 18.

At the in FIG. 1 shown nozzle head 14, the drive shaft 18 is designed as a solid shaft. The drive shaft 18 is mounted in the housing 12 via sealed radial bearings 22 and can be driven for example by means of an electric motor or pneumatically by means of a compressed air turbine. In operation, the bell portion 24 rotates with rotational speeds of 10,000 to 100,000 min ^-1 to its axis of rotation 16th

The bell member 24 includes a bell cup 42 and a bell plate 42 radially outwardly adjoining side wall 26 which are immovably connected to each other and together enclose a cavity. As a result of this embodiment of the bell part 24, its mass inertia can be kept low, so that drive energy can be saved.

A coating material to be applied is supplied from the side of the drive shaft 18 to the nozzle head 14 via a flow path 28. In FIG. 1 For this purpose, a line 30, eccentric with respect to the axis of rotation 16, guides the coating material to a coaxial channel 32, which in the present embodiment is annular and is bounded radially inwardly by the solid shaft 20 and externally by the housing 12. In the axial direction, the channel 32 is bounded on one side by the radial bearing 22 and opens on the opposite side in a direction of rotation 16 coaxial cylindrical dispensing portion 34 of the bell member 24. Here, a free end of the drive shaft 18 via a hub 36, for example immovably connected by means of an adhesive bond or an interference fit with the delivery region 34 of the bell member 24. As a result, the rotational movement of the drive shaft 18 is transmitted to the bell part 24.

In the delivery region 34, the flow path 28 is divided into a plurality of partial paths 38, which in the exemplary embodiments are configured as through-bores which run parallel to the axis of rotation 16. At the in FIG. 1 In the embodiment shown, six partial paths 38 open into discharge openings 40, which are arranged coaxially on a circle about the axis of rotation 16. The arrangement of the partial paths 38 is in the radial section AA in the FIG. 2 shown.

The bell cup 42 has a frusto-conical shape and adjoins the dispensing area 34, wherein it is also arranged coaxially with the axis of rotation 16. The bell cup 42 may also have deviating geometries as they are known per se in bell cups from the prior art. The bell cup 42 has a frusto-conical inner surface 44, which serves as a discharge surface 46. At the outer edge which is remote from the drive shaft 18, the outflow surface 46 ends in a peripheral tear-off edge 48. The outflow surface 46 encloses an angle α with the rotation axis 16. This is about 45 °, in particular angles in a range of 40 ° to 85 ° in question. As favorable a bell cup diameter has been found in a range of 20 mm to 90 mm, with larger bell cup diameters generally the coating material flows as a thinner film, whereby smaller droplets are formed at the trailing edge.

The inner circumferential surface 44 of the bell cup 42 surrounds a frusto-conical volume in which a deflecting body 50 is arranged. This is accommodated coaxially to the axis of rotation 16 of the nozzle head 14 in an end remote from the drive shaft 18 end of the discharge area 34. Here, in the present embodiment, a nozzle 52 of the deflecting 50 is immovably connected to the discharge region 34 of the bell member 24; This can be done for example by means of an adhesive connection or a press fit. Thus, the deflecting body 50 follows the rotational movement of the bell part 24.

The outer circumferential surface of the nozzle 52 of the deflection body 50 terminates in an annular baffle 54, which in turn merges into a frusto-conical outer surface 56, which ends in a circumferential end edge 58. In the present embodiment, the baffle 54 extends substantially in a plane perpendicular to the axis of rotation 16.

Due to the rotation of the bell member 24 and the deflecting body 50, this coating material flows on the baffle surface 54 as a film radially outward and to the inside outflow surface 46 of the bell cup 42nd On this, the coating material continues to flow to the tear-off edge 48, where the film dissolves in the form of jets or lamellae from the bell-shaped plate 42, from which droplets are formed. As mentioned above, it is desirable to produce small droplets.

Depending on the speed of the bell cup, in a rotary atomizer, the average size of the droplets that are thrown away from the bell cup 42 varies. The lower the rotational speed of the bell cup 42, the larger the droplets generated. At the same time, however, it is desirable to rotate the bell cup 42 at low speeds to save energy.

By dividing the flow path 28 in partial paths 38 in the discharge area 34, the undesired effect is counteracted that larger droplets are thrown away from the bell plate 42 at lower speeds. Due to their eccentricity, the partial paths 38 act as radially arranged drivers and can transmit additional rotational energy to the coating material. As a result, all of the coating agent will exit the discharge ports 40 at a higher absolute speed than if it were only centrally supplied. Such accelerated coating material thus impacts the baffle 54 and then the outflow surface 46 with higher kinetic energy, and then flows to the tear-off edge 48 in a thinner film, resulting in the formation of smaller, more uniform droplets.

In the present exemplary embodiments, the baffle 54 is formed substantially perpendicular to the axis of rotation 16. Also conceivable is an inclined impact surface 54.

The baffle surface 54, as mentioned above, in the frustoconical outer surface 56 on. This closes with the rotation axis 16 an angle α one, which is the same size as the angle which the outflow surface 46 of the bell cup 42 includes with the rotation axis 16. Thus, the outer circumferential surface 56 and the outflow surface 46 are parallel to each other. If, at lower speeds, coating material also flows along the outer lateral surface 56 of the deflecting body 52, this is dispensed at the end edge 58 at the latest and strikes the outflow surface 46 of the bell cup 42. A diameter of the end edge 58 which has proven to be less than 60% is favorable. the diameter of the bell cup is.

The deflection body 50 is designed as a hollow truncated cone in order to reduce the mass inertia of the nozzle head 14 as a whole. In order to reduce the suction effect of the cavity formed thereby, 54 air passage holes 60 are arranged in the baffle surface. These provide pressure equalization and thus enhance the distribution of the coating material that has been thrown off the trailing edge 48. In the FIG. 1 two such air passage holes 60 are shown, which are designed such that the unimpeded passage of coating material can be prevented. For this purpose, these have only a small diameter and also have a slope of the outer circumferential surface 56 opposite inclination.

Another way to influence the geometry of the spray jet generated by the nozzle head 14 is through the use of a not specifically shown steering air unit. For example, an annular collar 62, which partially covers the nozzle head 14, may be arranged on a housing collar. This directs shaping air to the spray jet generated in order to limit it in the radial direction. Further Possibilities for the design of the steering air unit are the DE 10 2012 010 610 A1 refer to.

In order to remove residues of coating material on the side wall of the nozzle head 14, a not specifically shown Spülmittelsprüheinrichtung may be provided. This can be arranged on the side wall of the bell part and clean it if necessary with a solvent.

When changing the coating material, the flow path 28 is completely rinsed with solvent to avoid mixing of different materials. For this purpose, a non-specifically shown, reciprocable pig can be provided in the supply lines to the nozzle head 14, which frees the walls of the feed lines from the inside of coating material residues.

2. Other embodiments of the nozzle head

The FIG. 3 shows a further embodiment of the nozzle head 14, in which the drive shaft 18 is designed as a hollow shaft 64. The coating material is supplied through the hollow shaft 64 via the coaxial channel 32 to the discharge region 34 of the bell member 24. The coaxial channel 32 is formed in the present embodiment as a central bore 66 in the bell member 24 and is located between the hub 36, which receives the hollow shaft 64, and the discharge region 34, in which the partial paths 38 extend.

The central bore 66 has the same diameter as the outer circle, which is formed by the radially outermost points of the eccentrically arranged partial paths 38. As a result, the inflow of the coating material from the coaxial Channel 32 facilitates the partial routes 38. In this embodiment, four partial paths 38 open into the discharge openings 40, which are arranged on a circle about the axis of rotation 16. The arrangement of the partial paths 38 is in the radial section AA in the FIG. 4 shown.

In the present embodiment, the deflecting body 50 and the dispensing area 34 can again be connected to each other by way of example by means of an adhesive connection or a press fit or alternatively by means of a screw connection not specifically shown. For this purpose, the end portion of the nozzle 52 protrude into the central bore 66 and carry a thread that can connect the deflecting body 50 and the delivery area 34 immovable in conjunction with a threaded nut.

The FIG. 5 FIG. 3 illustrates a third embodiment of the embodiment of FIG FIG. 3 is ajar. In contrast to this, here the deflecting body 50 has no neck, but is connected via pins 68 coaxial with the axis of rotation 16 immovably connected to the discharge area 34. Like the radial section AA in the FIG. 6 shows three pins 68 are arranged on a circle about the axis of rotation 16. In this embodiment, three partial paths 38 open into the three discharge openings 40, which are also arranged on a circle about the axis of rotation 16. As the air passage hole 60 is a centrally disposed in the baffle 54 through hole, as in the FIG. 5 shown.

In order to influence the geometry of the spray jet produced by the nozzle head 14, the present invention changes Embodiment of the angle α between the rotation axis 16 and the outflow surface 46. In particular, the angle α in the direction of the tear-off edge 48 is smaller. As a result of the fact that the coating material film is deflected, its velocity component in the axial direction is increased at the expense of the velocity component in the radial direction. At the trailing edge 48, the coating material thus undergoes a reduced acceleration in the radial direction, so that the maximum radius of the spray jet can be reduced.

Another embodiment is in the FIG. 7 shown. Here, the drive shaft 18 is also designed as a hollow shaft 64, however, the axial bore, which forms part of the flow path 28, eccentric to the axis of rotation 16. The coming out of the hollow shaft 64 coating material passes through the coaxial channel 32 to the discharge area 34th Der Coaxial channel 32 extends in this embodiment also in a central bore 66 of the bell member 24, in which case a socket 70 inserted into the central bore 66 forms the wall of the coaxial channel 32. Thus, the diameter of the coaxial channel 32 is adjusted to the diameter at which the eccentric axial bore in the hollow shaft has its radially outermost point, which contributes to the reduction of dead space in the flow path 28.

The coating material passes from the coaxial channel 32 into the partial paths 38 of the delivery region 34. In this exemplary embodiment, the partial paths 38 are formed by inserting an insert 74 in a central delivery bore 72 passing through the delivery region 34. The insert 74 has a cylindrical basic shape and contributes its peripheral surface three axial grooves 76, which together with the wall of the central discharge bore 72 form the partial paths 38 for the coating material. The arrangement of the partial paths 38 is in the radial section AA in the FIG. 8 shown. The three partial paths 38 open into three discharge openings 40.

Claims (10)

A nozzle head for a rotary atomizer for applying a coating material to an article comprising: a) around a rotation axis (16) rotatable bell cup (42) having a tear edge (48) and an outflow surface (46) to which the coating material can be fed such that the coating material from the tear-off edge (48) of the bell cup (42) is thrown , and b) a flow path (28), via which the coating material can be fed to the outflow surface (46),
characterized in that c) the flow path (28) in a discharge region (34) in partial paths (38) with each one to the rotation axis (16) of the bell cup (42) eccentrically arranged discharge opening (40) divides, from which the coating material can be dispensed, from there reaches the discharge surface (46). Nozzle head according to claim 1, characterized in that the discharge openings (40) about the rotational axis (16) of the bell cup (42) are rotatably mounted. Nozzle head according to one of the preceding claims,
characterized in that the dispensing area (34) has at least two dispensing openings (40) arranged on one are arranged to the rotation axis (16) coaxial circle. Nozzle head according to one of the preceding claims,
characterized in that the flow path (28) comprises a coaxial central channel (32), which is arranged in the flow direction of the coating material in front of the discharge area (34). Nozzle head according to claim 3, characterized in that the delivery area (34) is formed in an extension of the central channel (32), in which an insert part (74) is inserted such that the flow path (28) splits. Nozzle head according to claim 3 or 4, characterized in that at least the coaxial central channel (32) is received in a drive shaft (18) with which the bell cup (42) is coupled. Nozzle head according to one of the preceding claims,
characterized in that the dispensed from the discharge openings (40) coating material passes to the discharge surface by being on a deflecting body (50) feasible. Nozzle head according to one of the preceding claims,
characterized in that the outflow surface (46) in an annular region grooves (76), in particular radial grooves having. Nozzle head according to one of the preceding claims,
characterized in that in an annular region an angle between the outflow surface (46) and the axis of rotation (16) becomes smaller in the direction of the tear-off edge (48). Rotary atomizer for applying a coating material to an article with a nozzle head (14), characterized in that a nozzle head (14) according to one of claims 1 to 9 is provided.

Images