EP4058206A1

EP4058206A1 - Nebuliser and associated operating method

Info

Publication number: EP4058206A1
Application number: EP20804503.9A
Authority: EP
Inventors: Bernhard Seiz; Sascha Hermann; Eduard FRÜHSORGER
Original assignee: Duerr Systems AG
Current assignee: Duerr Systems AG
Priority date: 2019-11-13
Filing date: 2020-11-10
Publication date: 2022-09-21
Also published as: MX2022005776A; WO2021094278A1; CN114728299A; US11919022B2; US20230148199A1; DE102019130612A1; KR20220097390A; JP2023502060A

Abstract

The invention relates to a nebuliser (1) for the application of a multicomponent coating, having a base connection (4), a curing agent connection (7), a mixer (11), a curing agent line (12) which leads in the nebuliser (1) from the curing agent connection (7) to the mixer (11), a base line (10) which leads in the nebuliser (1) from the base connection (4) to the mixer (11), and a main valve (HN1) for controlling the dispensing of the coating, wherein the main valve (HN1) is arranged downstream of the mixer (11) and controls the flow of the multicomponent coating to an application element (3), more particularly to a rotatable bell plate (3). The nebuliser (1) according to the invention is characterised by a first return line connection (22) for returning the multicomponent coating from the nebuliser (1) to a return. To this end, the nebuliser (1) has a first return line (23) which in the nebuliser (1) branches off between the mixer (11) and the main valve (HN1) and leads into the first return connection (22). The invention further relates to a corresponding operating method.

Description

DESCRIPTION

Nebulizer and associated operating procedure

The invention relates to an atomizer (e.g. rotary atomizer) for applying a multi-component paint and an associated operating method.

In modern painting systems for painting motor vehicle body parts, rotary atomizers are usually used as application devices, which in one design can also apply a multi-component paint that is mixed together in the rotary atomizer from a base paint and a hardener. Such a painting system is known, for example, from DE 102015010158 A1.

The problem here is the collection of paint residues that occur, for example, when changing colors.

One possibility for this is the use of so-called wet washes. The multi-component reactive paint material brought into the wet wash is filtered out of water using suitable chemicals (e.g. flocculation, floatulation), whereby the filter residue then has to be disposed of as hazardous waste, which is extremely time-consuming.

Another possibility is the use of so-called dry washes. The multi-component reactive paint material must not be applied directly into the paint booth. For this purpose, separate installations are currently required, such as collecting funnels flushed with solvent or collecting containers with filter mats, which require a high level of maintenance and cleaning.

With all solutions currently available, among other things, volatile organic components (VOC: Volatile Organic Compounds) are introduced into the paint booth. These organic constituents may then have to be cleaned from the exhaust air in a further process step. In the event of a color change with the associated rinsing and pressing processes, the rotary atomizer is arranged, for example, over a rinsed collecting funnel or a collecting container, whereupon the residue of the multicomponent paint from the rotary atomizer can be rinsed out into the collecting funnel or collecting container. However, this requires the rotary atomizer to travel to the collecting container or collecting funnel, which is associated with an additional expenditure of time and leads to a high loss of cycle time, ie the time required for a lacquer change extends the cycle time required for the painting system.

Another disadvantage of this rinsing out of the multicomponent lacquer in a collecting funnel or a collecting container is that parallel cleaning of the outer surfaces of the atomiser is not possible when the lacquer is changed. As a result, these process steps have to be carried out one after the other, which in turn requires additional time. For example, the rotary atomizer can first be moved into a collecting funnel or collecting container in order to rinse out paint residues of the multicomponent paint. The rotary atomizer can then be moved into a cleaning device in order to clean the outer surfaces of the rotary atomizer.

Furthermore, DE 10 2009 020064 A1 discloses a painting system for painting one-component paint, a return valve actuated by its own medium enabling the return of color foam when there is a color change.

The invention is therefore based on the object of creating a correspondingly improved atomizer and a corresponding operating method.

This object is achieved by an atomizer according to the invention according to claim 1 or by a corresponding operating method according to the independent claim.

The invention encompasses the general technical teaching of flushing paint residues of the multicomponent paint not in the direction of the application element (eg bell cup) from the rotary atomizer, but into a separate return. This offers the advantage that two process steps can take place simultaneously with a color change, namely on the one hand rinsing out residues of the multicomponent paint from the atomizer and on the other hand cleaning the outside of the atomizer. This enables the cycle time of the painting system to be shortened, ie the working speed is increased. The nebulizer according to the invention has various correspondence with the known nebulizers, as they are known per se from the prior art.

The atomizer according to the invention also has a base paint connection for supplying a base paint and a hardener connection for supplying a hardener.

In addition, there is also a mixer in the atomizer according to the invention for mixing the base paint with the hardener to form the multi-component paint. Such a mixer is usually designed as a static mixer (e.g. lattice mixer, helical mixer).

In this case, a hardener line runs in the atomizer from the hardener connection to the mixer. Furthermore, a master paint line runs in the atomizer from the master paint connection to the mixer.

Furthermore, the atomizer contains a main valve known per se for controlling the paint dispensing, the main valve being arranged downstream behind the mixer and controlling the flow of the multicomponent paint to an application element (e.g. bell plate).

The atomizer according to the invention thus takes up hardener and base paint on the inlet side, mixes these paint components in the mixer to form a multi-component paint and then applies the multi-component paint to the component to be coated via the application element (e.g. bell plate).

The atomizer according to the invention is now characterized by a first return connection in order to return the multicomponent paint from the atomizer to a return, which takes place, for example, when a paint is changed, as will be described in detail below. A first return line runs in the atomizer and branches off in the atomizer between the mixer and the main valve and opens into the first return connection. When there is a color change, the main valve is then usually closed so that no more multi-component paint is dispensed via the application element. The residues of the multicomponent paint still in the atomizer can then be passed via the first return line into the first return connection, which is usually connected to a return.

It should be mentioned here that the atomizer also has several main needle valves and several 2K May have returns.

In general, it should be mentioned that the atomizer according to the invention is preferably a rotary atomizer which has a bell plate as an application element, as is well known per se from the prior art. In principle, however, the invention can also be implemented with other types of atomizers, such as, for example, air atomizers.

In a preferred embodiment of the invention are in the first Rückführlei device in the atomizer one behind the other a downstream controllable first return valve and an upstream controllable second return valve, which can preferably be controlled independently of each other. This offers the possibility of flushing medium being enclosed between the two return valves in the first return line in order to prevent a reaction between different mixed paint systems or to reduce it to a tolerable level.

In addition, the nebulizer according to the invention preferably has a first flushing connection in order to supply thinner (flushing agent) and / or pulsed air. In practice, pulses of air and thinner are alternately supplied in order to achieve the best possible flushing effect. A first flushing line runs in the atomizer, which starts from the first flushing connection and opens downstream into the first return line behind the downstream first return valve. The return line provided according to the invention can therefore be flushed via this first flushing connection and the first flushing line proceeding therefrom. For this purpose, a first flushing valve is preferably arranged in the first flushing line in order to control the inflow of the diluent or the pulsed air from the first flushing connection into the first return line.

In addition, the atomizer according to the invention preferably has at least one controllable hardener valve which is arranged in the hardener line and controls the flow of hardener. In the same way, at least one controllable base paint valve is preferably provided, which is arranged in the base paint line and controls the inflow of the base paint.

In addition, the atomizer according to the invention preferably has a second return connection in order to return the base paint separately from the hardener before it is mixed with the hardener. In this case, a second return line runs in the atomizer, which branches off from the base paint line upstream in front of the base paint valve and into the second return connection flows out. In this second return line, a controllable third return valve is preferably arranged, which controls the return flow of the base paint through the second return connection. When the base paint is returned, the base paint valve is usually closed while the third return valve is open, so that the base paint supplied on the input side is returned to the second return line.

Furthermore, the atomizer according to the invention preferably has a second flushing line which originates from a second flushing connection or from the first flushing connection and opens downstream into the main paint line downstream of the base paint valve. In this case, a second flushing valve is preferably provided, which is arranged in the second flushing line and controls the flow of flushing agent into the main paint line. In addition, a third flushing line is preferably provided, which emanates from a third flushing connection or from the first flushing connection or the second flushing connection and opens into the hardener line downstream behind the hardener valve. In this third flushing line, a third flushing valve is preferably arranged, which controls the flow of flushing agent into the hardener line.

In the atomizer according to the invention, the hardener line and the base paint line can preferably be flushed independently of one another, the flushing agent supply being controlled in each case by a flushing valve.

In addition, the nebulizer according to the invention can have a short flush line which leads downstream behind the main valve to the application element and from the first flush connection or from the second flush connection or from a third flush connection or from a further fourth flush connection goes out. In this short-rinse line is preferably a controllable short-rinse valve that controls the flow of detergent through the short-rinse line.

It should also be mentioned that the atomizer according to the invention preferably contains a paint tube that contains the mixer and the upstream second return valve. It should be mentioned here that the paint tube preferably also contains the main valve, which can be designed as a main needle valve and has a displaceable valve needle. Here there is the possibility that the valve needle of the main needle valve is designed as a static mixer (eg lattice mixer, spiral mixer), ie the valve needle fulfills two functions here. For one, it serves the valve needle as a valve element to control the material flow. On the other hand, the valve needle also forms the static mixer.

In the preferred embodiment, the upstream second return valve is designed as a diaphragm needle valve. This means that the diaphragm needle valve has a valve seat and a displaceable valve needle which, depending on its position, releases or blocks the valve seat. In addition, such a diaphragm needle valve is characterized by a valve diaphragm which surrounds the valve needle in a ring shape and serves to drive the valve needle and / or for sealing. Such diaphragm needle valves are known, for example, from WO 2009/019036 A1, so that the content of this patent application of the present description with regard to the structural design and the functioning of a diaphragm needle valve is to be fully attributed.

The valve seat of the second return valve can consist of steel, while the Ventilna del of the second return valve can pass through a sealing washer made of plastic and can be made of titanium, for example. Furthermore, the mixer can open out on the outlet side into a distributor, which forwards the mixed multi-component paint and consists at least partially of metal.

It has already been explained above what is meant in the context of the invention with a diaphragm needle valve. In the preferred exemplary embodiment, the main valve, the first return valve, the second return valve, the hardener valve and / or the master paint valve are also designed as membrane needle valves of this type.

In addition, it should be mentioned that the invention not only claims protection for the above generally described atomizer according to the invention. Rather, the invention also claims protection for a corresponding operating method for such an atomizer, in which the base paint and hardener are supplied and mixed in the atomizer to form the multi-component paint, and then finally applied, for example via a rotating bell plate.

The operating method according to the invention is characterized in that the multicomponent paint is fed back through the first return line when a color change occurs, which is between the Mixer and the main valve branches off. In contrast to the well-known rotary atomizer, the residues of the multi-component paint are not released via the application element.

The main valve (e.g. main needle valve) of the atomizer (e.g. rotary atomizer) is preferably closed during the return of the multi-component paint.

In the event of a color change, the following steps are preferably carried out in this order to press the atomizer with new paint:

Closing the main valve,

Opening the first return valve and the second return valve,

Opening the master paint valve to fill the master paint line with the master paint, opening the hardener valve to fill the hardener line with the hardener,

Returning the old multi-component paint and part of the remaining detergent and the new multi-component paint through the first return line into the first return, and

Close the master paint valve, the hardener valve, the first return valve and the second return valve in this order. The sequence in which the valve closes ensures that the paint medium / solvent mixture in the first return line is hermetically sealed. In addition, a reaction with air humidity can thus be prevented.

In the context of the operating method according to the invention, the following steps are preferably carried out to rinse the atomizer during a color change:

Open the second flush valve and flush the master paint line,

Open the third flush valve and flush the hardener line,

Opening the first return valve and the second return valve and rinsing out the old multi-component paint and the detergent through the first return line,

Filling the master paint line and the hardener line and the first return line with the detergent, and

Closing the first return valve and the second return valve when the first return line is filled with the flushing agent.

For rinsing the first return line while the multi-component paint is being applied the first flushing valve is then preferably closed and flushing agent is introduced into the first return line. Preferably, solvent and pulsed air are alternately supplied in order to achieve a good cleaning effect. At the end of the flushing process, solvent is then preferably added in order to partially fill the first return line with the flushing agent.

The design of the nebulizer according to the invention enables the following steps to be carried out simultaneously or at least overlapping in time:

External cleaning of the atomizer, in particular by spraying the atomizer with a solvent, and

Color change in the atomizer, in particular with rinsing the atomizer into the first return line and pressing the atomizer with the new master paint and the new hardener.

The invention offers various advantages which can be summarized as follows.

• When changing colors, no more material is applied via the paint nozzle.

• This means that the external cleaning of the atomizer can be carried out in parallel with the paint change. In this way, the lacquer change can be carried out in a usual cycle gap of 15 seconds without losing cycle time. This increases the capacity of the paint shop.

• Cost savings through the elimination of the receiving funnel or collecting container. In this context, the time-consuming cleaning and maintenance of these installations is no longer necessary.

• Significant reduction in complexity by eliminating the following process steps or concepts:

Positioning of the receiving hoppers or collecting containers in the painting booth Movement drives (programming of the teach programs)

Safety concept (software protection for switching off the high voltage)

• With the invention and the elimination of the flushed receiving funnel, significantly fewer VOCs are introduced into the booth and solvents are saved. This may mean that there is no need for or a reduction in exhaust air purification.

• When using wet scrubbing, the use of chemicals can be significantly reduced.

• The mixture of multi-component reactive paint material and solvent collected via the new recycling system is collected in a central point and can be returned to the manufacturer for recycling. This helps reduce the cost as well Environmental protection.

Other advantageous developments are characterized in the subclaims or are explained in more detail below together with the description of the preferred exemplary embodiment of the invention with reference to the figures. Show it:

1 shows a schematic representation of a rotary atomizer according to the invention on an arm of a painting robot,

2A shows a cross-sectional view through a flake needle valve according to the invention with an integrated return,

FIG. 2B shows the flake needle valve from FIG. 2A with the return duct open,

3A and 3B show a flow chart to illustrate the operating method according to the invention.

FIG. 1 shows a schematic representation of a rotary atomizer 1 according to the invention, which is mounted on a robot arm 2 of a conventional painting robot with serial robot kinematics. The robot arm 2 is the distal robot arm of the painting robot, which is also referred to as "arm 2" in accordance with the customary technical terminology.

The rotary atomizer 1 is used to apply a multi-component paint over a rotating bell cup 3, as is known per se from the prior art.

To supply a base paint, the rotary atomizer 1 has a base paint connection 4, the base paint connection 4 of the rotary atomizer 1 being supplied with the desired base paint by a color changer 5 in the robot arm 2.

Between the color changer 5 and the master paint connection 4 of the rotary atomizer 1, a metering pump 6 is arranged here at, which pumps the master paint with the desired paint flow. The metering pump 6 can be bypassed by a bypass valve Byl connected in parallel. In addition, the rotary atomizer 1 has a hardener connection 7 in order to supply hardener. The hardener is supplied by a valve unit 8 with a hardener valve Hl and a thinner valve VH via a metering pump 9.

In the rotary atomizer 1, a base paint line 10 emanates from the base paint connection 4, which opens via a base paint valve SL1 into a static mixer 11, which in the preferred embodiment is designed as a helical mixer, as in FIGS. 2A and 2B is shown.

A hardener line 12, in which a hardener valve Hl is arranged, in order to control the inflow of the hardener, extends accordingly from the hardener connection 7. The hardener line 12 also opens into the mixer 11, so that the mixer 11 mixes the base paint with the hardener.

Downstream behind the mixer 11 there is a main needle valve HN1 which controls the flow of the multicomponent paint from the mixer 11 to the bell cup 3, the structure and mode of operation of the main needle valve HN1 being shown in FIGS. 2A and 2B and being described separately.

In addition, the rotary atomizer 1 has a return connection 13 in order to be able to return the base paint to a return (not shown). For this purpose, a return line 14 runs in the rotary atomizer 1, which branches off from the base paint line 10 between the base paint connection 4 and the base paint valve SL1 and opens into the return connection 13. In this return line 14 is a return valve RF1 / SL1, which controls the flow in the Rückfüh tion.

The rotary atomizer also has a rinsing connection 15 for rinsing the base paint line 10. A rinsing line 16 extends from the rinsing connection 15 and opens downstream behind the master paint valve SL1 into the master paint line 10. A rinsing valve V / PL is located in the rinsing line 16 for rinsing the base paint line 10.

In the robot arm 2 of the painting robot there is a valve unit 17 with a thinner valve V and a pulsed air valve PL, whereby the valve unit 17 can optionally supply thinner (rinsing agent) or pulsed air to the rinsing connection 15. The rotary atomizer 1 also includes a rinsing connection 18 for rinsing the hardener line 12. A rinsing line 19 emanates from the rinsing connection 18 and opens into the hardener line 12, with the rinsing line 19 a flush valve V / Hl is arranged.

Furthermore, the rotary atomizer 1 has short rinsing connections 20, 21 for short rinsing of the rotary atomizer 1, as is known per se from the prior art and therefore does not have to be described in more detail. It is only to be mentioned that the rotary atomizer 1 contains short-rinse valves KSL, KS for Kurzspü len.

The rotary atomizer 1 is now characterized by a return connection 22, which enables the multicomponent paint to be fed back into a return (not shown). For this purpose, a return line 23 branches off in the rotary atomizer 1 between the mixer 11 and the main needle valve HN1 and opens into the return connection 22. In the return line 23 there are two return valves RF4, RF41 one behind the other, the upstream return valve RF4 also being shown in FIGS. 2A, 2B and being described separately.

For flushing the return line 23, the rotary atomizer 1 has a further flushing connection 24, which can be supplied with thinner or pulsed air from the valve unit 17. From the flushing connection 24, a flushing line 25 extends in the rotary atomizer 1, which opens into the return line 23 via a flushing valve V2 / PL2 and enables flushing of the return light.

The valves in the robot arm 2 and in the rotary atomizer 1 are partially designed as conventional needle valves without a separating membrane, which can be seen from the corresponding hatching, as indicated in the legend. However, some of the valves are designed as needle valves with a separating membrane, as are known per se from WO 2009/019036 A1.

FIGS. 2A and 2B will now be described below, which illustrate the structure and function of the main needle valve HN1, the mixer 11 and the return valve RF4. FIG. 2A shows a closed state of both the main needle valve HN1 and the return valve RF4. In the illustration according to FIG. 2B, the main needle valve HN1 is also closed while the return valve RF4 is open.

The drawings show a paint tube 26, which is the main needle valve HN1, the mixer 11 and the return valve RF4 accommodates, the paint tube 26 also leading to the bell cup 3, as is known per se from the prior art.

A needle seat 27 adjoins the paint tube 26, a sealing disk 28 made of POM (POM: polyoxymethylene) being arranged between the paint tube 26 and the needle seat 27.

Finally, behind the needle seat 27, a distributor 29 is arranged, which also consists of POM and contains a paint line 30 which leads to the bell cup 3.

The paint tube 26, the sealing washer 28 and the needle seat 27 contain an axially continuous Boh tion 31 which opens into the paint line 30.

In the bore 31 a valve needle 32 is displaceable in the direction of the double arrow, the Ven tilnadel 32 has two functions.

On the one hand, the valve needle 32 is designed as a spiral mixer and thus forms the mixer 11 for mixing the base paint and the hardener.

On the other hand, the valve needle 32 is used in a conventional manner as a valve element for controlling the paint flow into the paint line 30. For this purpose, the valve needle 32 has a valve head 33 which either releases or closes a corresponding valve seat.

The return valve RF4 is arranged in a further axial bore 34 and has a valve needle 35 which is displaceable in the bore 34 in the direction of the double arrow. The valve needle 35 of the return valve RF4 also has a valve head 36 which either closes a valve seat (as in FIG. 2A) or releases (as in FIG. 2B).

Furthermore, FIGS. 2A and 2B show a line section of the return line 23, which is optionally released or blocked by the return valve RF4.

The following describes the flowchart in FIGS. 3A and 3B, which explains the operating method according to the invention.

In a first step S1, an initial situation is initially shown. In this initial situation, the main channel is filled with flushing medium, while the Rückführlei device 23 between the return valves RF4, RF41 is filled with flushing agent. In this initial situation the return valves RF4, RF41, RF1 / SL1 are closed. The main needle valve HN1, the main paint valve SL1 and the hardener valve Hl as well as the flushing valves V / PL, V / Hl and V2 / PL2 are also closed.

Step S2 now shows the pressing of the rotary atomizer 1 with a new paint.

The main channel is filled with the new paint. The return valves RF4, RF41 are open, while the return valve RF1 / SL1 and the main needle valve HN1 are closed. The master paint valve SL1 and the hardener valve Hl, however, are open, while the flushing valves V / PL, V / Hl and V2 / PL2 are closed.

At the end of this pressure, the master paint valve SL1 and the hardener valve Hl are then first closed. Next, the return valve RF41 is closed. Finally, the return valve RF4 is then closed. This sequence of closing the valves when pressing ensures that the paint medium / solvent mixture in the atomizer return is hermetically sealed. In addition, a reaction with air humidity can thus be prevented.

In a step S3, painting with the new paint then takes place. The return valves RF4, RF41, RF1 / SL1 are closed, while the main needle valve HN1, the master paint valve SL1 and the hardener valve Hl are open. The flushing valves V / PL, V / Hl and V2 / PL2 are also closed during painting. At the end of the painting process, the main needle valve HN1, the hardener valve Hl and the master paint valve SL1 are then closed.

In a next step S4, after the end of the painting process, the rotary atomizer 1 is rinsed. The return valves RF4, RF41 are opened, while the return valve RF1 / SL1, the main needle valve HN1, the master paint valve SL1 and the hardener -Valve Hl are closed while the flushing valves V / PL and V / Hl are open.

In a next step S5, the filling with rinsing agent then takes place, the main channel and the rinsing line 23 between the rinsing valves RF4 and RF41 being filled with rinsing agent. The valve position of the various valves is indicated in step S5. Finally, in a step S6, the return flow is flushed according to the invention, the return line 23 being able to be flushed during the painting process described above. The main needle valve HN1, the master paint valve SL1, the hardener valve Hl are open to enable painting. The flushing valves V / PL and V / Hl, on the other hand, are closed, which also applies to the return valves RF4, RF41. The flushing valve V2 / PL2, on the other hand, is open, the flushing valve V2 / PL2 being closed again at the end of the flushing process.

The invention is not restricted to the preferred exemplary embodiment described above. Rather, a large number of variants and modifications are possible which also make use of the inventive concept and therefore fall within the scope of protection. In particular, the invention also claims protection for the subject matter and the features of the subclaims independently of the claims referred to in each case and in particular also without the features of the main claim. The invention thus comprises various aspects of the invention that are protected independently of one another.

List of reference symbols:

1 rotary atomizer

2 robot arm ("Arm 2")

3 bell plates

4 trunk paint connection

5 color changers

6 Dosing pump for base paint

7 Hardener connection

8 Valve unit with hardener valve Hl and thinner valve VH for hardener

9 Dosing pump for hardener

10 trunk paint line

11 mixer

12 Hardener line

13 Return connection for the return of base paint

14 Return line for base paint

15 Rinsing connection for rinsing the base paint line

16 Flushing line for flushing the base paint line

17 Valve unit with pulsed air valve PL and thinner valve V for base paint

18 Rinsing connection for rinsing the hardener line

19 Rinsing line for rinsing the hardener line

20, 21 short flush connections

22 Return port

23 Return line

24 Feedback connection

25 Rinsing line for rinsing the return

26 paint tube

27 needle seat

28 POM sealing washer

29 distributors made of POM

30 paint line to the bell plate

31 Hole for valve needle

32 valve needle as a spiral mixer

33 Valve head of the valve needle 34 Hole for recirculation valve RF4

35 Valve needle of the return valve RF4

36 Valve head of the return valve RF4

Byl bypass valve for dosing pump

H 1 Flärter valve

SL1 master paint valve

RF1 / SL1 return valve for base paint

V / PL flush valve for flushing the main paint line

V / H 1 flush valve for flushing the Flärter line

HN1 main needle valve

RF4, RF41 return valves in the return line

V2 / PL2 flush valve for flushing the return line

KS, KSL short flush valves

Claims

EXPECTATIONS

1. Atomizer (1), in particular rotary atomizer, for applying a multi-component paint, with a) at least one base paint connection (4) for supplying a base paint, b) at least one hardener connection (7) for supplying a hardener, c) at least a mixer (11) for mixing the master paint with the hardener to form the multi-component paint, d) at least one hardener line (12) which leads in the atomizer (1) from the hardener connection (7) to the mixer (11) , e) at least one main paint line (10) which leads in the atomizer (1) from the main paint connection (4) to the mixer (11), f) at least one main valve (HN1) for controlling the paint dispensing, the The main valve (HN1) is arranged downstream behind the mixer (11) and controls the flow of the multicomponent paint to an application element (3), in particular to a rotatable bell plate (3), characterized by g) a first return connection (22) to the multi-component paint from the atomizer (1) in a return, and h) a first return line (23) which branches off in the atomizer (1) between the mixer (11) and the main valve (HN1) and opens into the first return connection (22).

2. Atomizer (1) according to claim 1, characterized in that in the first return line

(23) a downstream controllable first return valve (RF41) and an upstream controllable second return valve (RF4) are arranged one behind the other.

3. Atomizer (1) according to claim 2, characterized by a) a first flushing connection (24) for supplying diluent and / or pulsed air, b) a first flushing line (25) leading from the first flushing connection (24) goes out and downstream downstream of the downstream first return valve (RF41) opens into the first return line (23), c) a first flushing valve (V2 / PL2) which is arranged in the first flushing line (25) and the inflow of the diluent and / or the pulsed air from the first flushing connection (24) into the first return line (23 ) controls.

4. Atomizer (1) according to one of the preceding claims, characterized by a) at least one controllable hardener valve (Hl) which is arranged in the hardener line (12) and controls the inflow of the hardener, and b) at least one controllable Base paint valve (SL1), which is arranged in the base paint line (10) and controls the flow of the base paint.

5. atomizer (1) according to any one of the preceding claims, characterized by a) a second return connection (13) for returning the base paint, b) a second return line (13), the upstream of the base paint valve (SL1) from the Main paint line (10) branches off and opens into the second return connection (13), c) a controllable third return valve (RF1 / SL1) which is arranged in the second return line (13) and the return flow through the second return -Connection (13) controls.

6. Atomizer (1) according to one of the preceding claims, characterized by a) a second flushing line (16) which starts from a second flushing connection (15) or from the first flushing connection and downstream behind the main paint valve (SL1 ) opens into the main paint line (10), b) a second flushing valve (V / PL), which is arranged in the second flushing line (16) and controls the flow of detergent into the main paint line (10) , c) a third flushing line (19), which emanates from a third flushing connection (18) or from the first flushing connection or the second flushing connection and downstream behind the hardener valve (Hl) into the hardener line (12) opens, d) a third flush valve (V / Hl) which is arranged in the third flush line (19) and controls the flow of flushing agent to the hardener line (12).

7. atomizer (1) according to any one of the preceding claims, characterized by a) a short rinsing line which leads downstream behind the main valve (HN1) to the application element (3) and from the first rinsing connection or from the second rinsing Connection or from a third flushing connection (20) or from a fourth flushing connection (21), b) a controllable short-rinse valve (KS, KSL) which is arranged in the short-rinse line and controls the flow of the detergent through the short-rinse line.

8. Atomizer (1) according to one of the preceding claims, characterized by a paint tube (26) which contains the mixer (11) and the upstream second return valve (RF4).

9. atomizer (1) according to any one of the preceding claims, characterized in that a) that the second return valve (RF4) is designed as a diaphragm needle valve with the following components: a1) a valve seat, a2) a displaceable valve needle (35), which in Depending on its position, the valve seat releases or blocks, a3) a valve membrane which surrounds the valve needle in a ring and serves to drive the valve needle and / or for sealing, b) that the valve seat of the second return valve (RF4) is preferably made of steel , c) that the valve needle (35) of the second return valve (RF4) preferably passes through a sealing disk (28) made of plastic, d) that the valve needle (35) of the second return valve (RF4) is preferably made of titanium, e) that the mixer (11) on the outlet side preferably opens into a distributor (29) which forwards the mixed multi-component paint and which is at least partially made of metal.

10. Atomizer (1) according to one of the preceding claims, characterized in that the following valves are designed as membrane needle valves and each have the following components: a valve seat, a displaceable valve needle that releases or blocks the valve seat depending on its position, and one Valve membrane, which surrounds the valve needle in a ring shape and serves to drive the valve needle and / or for sealing, a) the main valve (HN1), b) the first return valve (RF41), c) the second return valve (RF4), d ) the Flärter valve (Hl), and / or e) the master paint valve (SL1).

11. Operating method for an atomizer (1) according to one of the preceding claims, a) supplying at least one base paint to the atomizer (1) at the base paint connection (4) of the atomizer (1), b) forwarding the base paint in the atomizer (1) through the base paint line (10) to the mixer (11) ), c) supplying at least one hardener to the atomizer (1) at the hardener connection (7) of the atomizer (1), d) forwarding the hardener in the atomizer (1) through the hardener line (12) to the mixer

(11), e) Mixing the master paint with the hardener to form the multi-component paint by the mixer

(11), f) controlling the paint release from the mixer (11) to the application element (3) by means of the main valve (HN1), and g) applying the multicomponent paint by means of the application element (3), h) returning the multicomponent paint when there is a color change the first Rückführlei device (23), which branches off between the mixer (11) and the main valve (HN1).

12. Operating method according to claim 11, characterized in that the main valve (HN1) is closed during the return of the multi-component paint.

13. Operating method according to claim 11 or 12, characterized by the following steps for

Pressing the atomizer (1) with new paint in the event of a color change: a) closing the main valve (HN1), b) opening the first return valve (RF41) and the second return valve (RF4), c) opening the main paint valve (SL1) to fill the master paint line (10) with the master paint, d) open the hardener valve (Hl) to fill the hardener line (12) with the hardener, e) return the old multi-component paint and part of the remaining paint Rinsing agent and the new multi-component paint through the first return line (23) into the first return, and f) closing the master paint valve (SL1), the hardener valve (Hl), the first return valve (RF41) and the second return Valve (RF4) in this order.

14. Operating method according to one of claims 11 to 13, characterized by the following

Steps for rinsing the atomizer (1) in the event of a color change: a) Opening the second rinsing valve (V / PL) and rinsing the main paint line (10), b) opening the third flushing valve (V / Hl) and flushing the hardener line (12), c) opening the first return valve (RF41) and the second return valve (RF4) and flushing out the old multi-component paint and of the detergent through the first Rückführlei device (23) in the first return, d) filling the main paint line (10) and the Flärter line (12) and the first Rückführlei device (23) with the detergent, e) closing the first Return valve (RF41) and the second return valve (RF4) when the first return line (23) is filled with the flushing agent. 15. Operating method according to one of claims 11 to 14, characterized by the following

Step for rinsing the first return line (23) during the application of the multi-component paint:

Opening the first flushing valve (V2 / PL2) and introducing flushing agent into the first return line (23), in particular alternating solvent and pulsed air, with solvent preferably being supplied at the end of the flushing process, partially with the first return line (23) to fill the detergent.

16. Operating method according to one of claims 11 to 15, characterized in that the following steps are carried out simultaneously or at least overlapping in time: a) external cleaning of the atomizer (1), in particular by spraying the atomizer (1) with a solvent, and b) Color change in the atomizer (1), in particular with the following steps: bl) rinsing the atomizer (1) into the first return line (23), b2) pressing the atomizer (1) with the new master paint and the new hardener.