EP0715896B1 - A rotary atomiser with a rotating bell - Google Patents

Description

The invention relates to a rotary atomizer with a Bell body according to the preamble of claim 1. Such Atomizers are known to work in electrostatic Color coating systems, for example for series painting used by vehicle bodies.

DE 43 06 799 A1 describes a rotary atomizer with a Bell body known to be coaxial from behind in the Bell body inserted fixed central tube construction for the material supply rotates one of the color channel contains a separate channel through which a detergent (which in particular means a color solvent) enters the interior of the bell body. Because of the Color channel separate detergent channel of the central tube construction is a flushing of the bell plate and one in the distributor or deflection part used in the bell cup possible without the need to first choose the color for this remove the color channel and accept the loss have to. The separate channels of the pipe construction Conveniently open in a fastened to the deflecting part Ring body with which the deflecting part can be removed into the bell body is inserted, as known from DE-GM G 93 19 555.9 is.

The problem with the known atomizers is that in operation on the bell circumference, more or less conically diverging outer surfaces of the bell body Color particles can precipitate out again solve and especially after a color change the one to be coated Can contaminate the object. It is therefore necessary a way to clean this outside surface too create.

A known solution from DE-GM G 86 07 841.0 of the above Problem is one removed from the central paint tube arranged in the radially outer region of the atomizer housing to provide your own detergent channel that connects to an external one Detergent source is connected and in on the conical Outer surface of the bell body directed nozzles opens. Radial outside the detergent nozzles there is a ring of axially parallel ones Steering air nozzles, their radial distance from the axis of rotation approximately the largest radius of the outer surface of the Spray bell should correspond, and its purpose usually a shape control of the sprayed from the atomizer bell Coating material. For the detergent supplied from the outside will have its own control system including valve, Valve drive and program control required. The same with other known rotary atomizers (DE-A-3 912 700) have previously been spraying the outside surface with rinsing liquid The main disadvantage of externally opening nozzles is that among other things through rebound effects of the atomizers also outside the surface to be cleaned, for example axially behind points lying on the bell body and / or on external electrodes for charging the coating material moistened and can be contaminated. With relatively good conductivity Flushing liquids also cause high-voltage insulation problems on.

While it is known to arise from inside the bell body to provide channels leading the outside, but the purpose have unscheduled or after a cleaning process in the Drain the rinsing liquid collecting the interior outwards. On It is therefore not possible to rinse the outer surface as scheduled.

The invention is therefore based on the object of a rotary atomizer specify which enables the lateral outer surface of the bell body without the usual spraying and preferably also with less effort than before clean.

This object is characterized by that in claim 1 Rotary atomizer released.

The invention has the advantage that the more or more less conical forward diverging outer surface of the bell body through that from inside the bell body coming to the axially rear edge of this outer surface flowing detergent effectively and reliably without that unwanted wetting of other atomizer areas cleaned becomes. It becomes an even, simultaneous and splash-free Actuation of the outer surface of the bell plate reached. At preferred embodiments can also be cleaned with be controlled in the same system as in normal Operation for regular brief or intermediate rinsing of the bell plate and optionally the central distributor or deflection part is needed, i.e. without its own valve and without additional tax expense by branching from the usual Short flush valve.

On an embodiment shown in the drawing the invention is explained in more detail. The drawing shows the Bell body of the rotary atomizer and schematically one steering air ring mounted on the rotary atomizer.

The bell body 1 is used to spray coating material such as. water-soluble or other colored lacquer, which flows over the overflow surface 2 to the spray edge 3, and is with its hub part 4 in a known manner in the open End of a (not shown) hollow shaft of the drive motor of the rotary atomizer. This mounting structure enables a small, compact and light bell unit and a relatively short paint tube 7 around which the bell body 1 rotates. Through the front end of the Coaxially arranged to the axis of rotation of the color tube 7 becomes spraying coating material passed into the bell body. When changing colors, it usually flows instead a detergent through the paint channel of the paint tube 7.

The paint tube 7 is part of a fixed tube body 8, due to the additional eccentrically parallel to the paint tube Guide axial bores 9. Through these axial bores 9 outside of the color tube 7 you can see the interior of the bell unit rinse without using the paint tube 7 and e.g. Paint loss or having to accept larger amounts of detergent. This can be useful if regular cleaning not only necessary when changing colors, but for other reasons is. The paint tube 7 and the holes 9 open in Interior of an annular body 13 fastened to the deflection part 10, with which the deflection part can be removed into the bell body 1 is plugged in. Through the deflecting part 10 is to be atomized Coating material divided into partial flows, of which the a partial flow on the back of the deflecting part to the overflow surface 2 flows while the other partial flow through one Center opening on the front of the deflecting part and from there reaches the overflow surface 2.

The axially parallel in the ring body 13 of the deflecting part 10 ending Bores 9 are fed by a detergent channel 9 ' separated from the color channel of the color tube 7 in a radial extended part 8 'of the tubular body 8 is located. With axial Distance between the radial front face 12 of part 8 'and the rear end face 17 of the ring body 13 is an annular space 29 surrounding the tubular structure formed at its radially outer end in the inner wall of the bell body is enlarged and at this point can be axially expanded trough-like. In this area on outer periphery of the annular space 29 open one or more connecting channels 20, the annular space 29 with the detergent channel 9 'connect. The one or more connecting channels 20 run radially outwards and / or starting from the detergent channel 9 ' as shown inclined forward against the radial direction.

As can be seen from the drawing, the outer circumference of the bell body 1 by a diverging forward, at the continuously considered conical outer surface 5, between the spray edge 3 and a rear, collar-like edge 6 facing away from spray edge 3 extends. Located radially inward on the edge 6 itself in the back of the bell body 1 between the conical Outer surface 5 and the axially front region of the hub part 4 a cross section, for example approximately U-shaped, axially more open to the rear, i.e. part of the outer surface of the Annulus 15 forming bell body.

At the radially inner end of the radially extending floor or Inner surface 16 of the annular space 15 open out with uniform External flushing channels distributed around the axis of rotation 18, starting radially from the circumference of the annular space 29 inclined outwards and against the axial direction through the hub part 4 of the bell body 1. For cleaning the conical outer surface 5 can therefore be used for this Solvent or detergent from the detergent channel 9 'of central tube construction. It flows in rotating bell due to the centrifugal effect of the Connection channel 20, the annular space 29 and the channel 18, about the bottom or inner surface 16 and the radially outer side wall of the annular space 15 and finally over the rear edge 6 of the bell body 1, from where it is over the conical outer surface 5 distributed. This advantageously happens at the same time a flushing process for cleaning the openings in and on the deflection part 10 and the overflow surface 2 through that from the axial bores 9 escaping detergent, i.e. automatically and without own tax expense. A practical rounded bell edge 6 favors the splash-free transition from the inside to the outside surface.

The annular space 29 has a larger one (on its outer circumference) Diameter than that between the hub part 4 and the fixed one Pipe construction formed gap 25. This can Prevent the rinsing liquid from getting through Centrifugal force collects on the outer circumference of the annular space 29, emerges from the bell body through the gap 25 and e.g. in rear bearing arrives. In addition to or instead of in the gap 25 also prevents the detergent from escaping dynamic seal 26 may be provided.

Deviating from the schematic representation of the drawing the annular space 15 can also have a different shape, for example with a radially outward inclined or curved outer side wall. The shape of the annular space 15 can in particular depend on the number of external rinsing channels 18 available. If only one or only for constructive simplification few external rinsing channels are provided, it can be useful in the radially outer wall of the annular space 15 e.g. in the Near its bottom is a relatively small, circular collecting trough train (not shown) or the bottom (at 6) to be moved radially inwards to collect the detergent.

It is useful to use the rotary atomizer behind the rotating one Bell body 1 in the radially outer region is a ring part 30 mounted, which distributed around the circumference, to a compressed air source contains connected axially opening air nozzles 31, which Flushing detergent or solvent with steering air flowing over the outer surface 5 act upon. These axial air nozzles have the shown Example a radial distance from the axis of rotation, which is approximately equal to half the diameter of the conical Outer surface 5 near its rear end and thus is only slightly larger than half the diameter of the edge 6. It is also possible to have several air nozzle rings with different ones Diameters and / or mouth directions can be provided.

It was found that by being relatively far radially inside, that is, on the rear end of the outer surface 5 Steering air in the axial direction immediately afterwards a high one Negative pressure is generated, which is even, possibly decreasing, over the entire outer surface 5 to the largest area Diameter extends at the spray edge 3. Through this The solvent flowing over the edge 6 is placed under negative pressure firmly on the entire outer surface 5, thereby the cleaning effect is significantly improved.

A cleaning of the outer surface can also be done without the achieve described steering air effect, because that over the edge 6 flowing solvents due to their natural adhesive effect adheres to the outer surface 5. This adhesive effect can be determined more clearly the larger the rounding radius is selected at edge 6. The degree of rejuvenation of the conical outer surface 5 affects how well that Solvent applied.

The invention is not based on the embodiment described above limited. In particular, the detergent or solvent not necessarily branched off from the central tube construction but it can also be done in another way inside the Bell body or to be cleaned radially within the one External area or, if available, in a the space corresponding to the annular space 15 or a corresponding one axial depression and from there laminar to the flow on the outer side of the bell. For this can a separate control valve can be provided with which the External rinsing process can be controlled separately.

Claims (15)

1. Rotary atomiser with a bell body (1), which is mountable on a rotating shaft of a drive motor and from whose interior the material to be atomised flows onto an outer flow surface (2) on the front end of the bell body (1) and leading to the spray edge (3), and which has an outer side surface (5) on the bell periphery extending from the spray edge (3), and with a conduit (9), from which a solvent or washing agent flows onto the outer side surface (5) of the bell body (1) to remove coating material deposits, characterised in that the washing agent flows under centrifugal action from a position (15, 29) in the bell body (1) supplied by the washing agent conduit (9) onto the outer side surface (5) for the prupose of washing and cleaning the outer side surface (5) and is distributed over the outer surface (5).
2. Rotary atomiser as claimed in Claim 1, characterised in that the position supplied by the washing agent conduit (9) is situated in a space (29, 15) defined in the bell body (1) or in an axial recess in the bell body (1).
3. Rotary atomiser as claimed in Claim 1 or 2, characterised in that the washing agent flows under centrifugal action around a rear, annular edge (6() of the outer surface (5) and is distributed uniformly from there over the entire surface (5) between the edge (6) and the spray edge (3).
4. Rotary atomiser as claimed in Claim 1, characterised in that one or more outer washing passages (18), which are distributed around the axis of rotation, lead from an internal space (29) in the bell body (1) into an outer annular space (15), which is situated at a position on the bell body (1), directed away from the front end, between a rear wall (6) of the outer surface (5) and a boss portion (4) of the bell body (1) and from which the washing agent flows over the rear edge (6) onto the outer surface (5).
5. Rotary atomiser as claimed in one of the preceding claims, characterised in that the annular space (15), which adjoins the rear wall (6), is open rearwardly to the atmosphere.
6. Rotary atomiser as claimed in Claim 4 or 5, characterised in that the outer washing passages (18) discharge at the radially inner end of a generally radially extending inner surface (16) of the annular space (15).
7. Rotary atomiser as claimed in Claim 4, 5 or 6, characterised in that there is a collecting depression for the washing agent in the radially outer side wall of the annular space (15).
8. Rotary atomiser as claimed in one of the preceding claims, whose bell body (1) rotates about a fixed central tube construction (7, 8) for supplying the material, which is inserted coaxially into a rear opening directed away from the flow surface (2) and which includes a passage (9, 9'), through which a washing agent flows axially into the internal space of the bell body (1), characterised in that one or more outer washing passages (18), which are distributed about the axis of rotation, connect the washing agent passage (9, 9') of the central tube construction (7, 8) with a position (16) on the outer surface of the bell body (1) from which the washing agent flows over the outer side surface (5) of the bell body (1) leading to the spray edge (3).
9. Rotary atomiser as claimed in one of the preceding claims, particularly with a bell body (1) whose outer surface (5) leading to the spray edge (3) diverges at least approximately conically, characterised in that air nozzles (31), which are connectable to a source of compressed air and discharge onto the outer surface (5), apply deflecting air to the washing agent flowing over the outer surface (5).
10. Rotary atomiser as claimed in one of the preceding claims, characterised in that a reduced pressure is produced at the outer surface (5) which draws the washing agent against this surface by air nozzles (31) distributed around the axis of rotation.
11. Rotary atomiser as claimed in one of the preceding claims, characterised in that the outer washing passage(s) (18) start from the outer periphery of a coaxial inner annular space (29), which is situated in the rear portion of the bell body (1) and which is connected to the washing agent conduit (9, 9') by a connecting passage (20).
12. Rotary atomiser as claimed in Claim 11 with a central deflector portion (10) which is coaxially arranged in the bell body (1) within the flow surface (2) and by means of which the material to be atomised is split up into component flows, of which one component flow flows on the rear surface of the deflector portion (10) to the flow surface (2) whilst the other component flow flows through a central opening (25) onto the front surface of the deflector portion (10).
13. Rotary atomiser as claimed in one of Claims 8 to 12, characterised in that provided between the tube construction (7, 8, 8') and the boss portion (4) of the bell body (1) there is a seal (26) which prevents the undesired discharge of washing agent from the bell body (1).
14. Rotary atomiser as claimed in one of Claims 8 to 13, characterised in that the inner annular space (29) has a larger diameter than the gap (25) situated between the boss portion (4) and the fixed tube construction (7, 8, 8').
15. Rotary atomiser as claimed in one of Claims 11 to 14, characterised in that the connecting passage (20) is radially outwardly aligned and leads from the washing agent passage (9') in the central tube construction (7, 8) to the annular space (29).

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