EP1502656B1 - Method and paint supply system for an electrostatic coating station and coupling system therefore - Google Patents

Abstract

The method for the supply of colour to an electrostatic coating device (3) involves coating material flowing from a container (12A,12B) in a potential isolating unit (1) connected to a colour supply unit (10) lying on an earth potential to the coating device via a connecting line arrangement (2). The container is connected directly to the colour supply valve (10A,10B) of the colour in use. The container is movable back and forth by an automatic drive unit between the colour supply valves and a colour extraction valve (14A,14B) to which is connected the connecting line (2A,2B) leading to the coating device. Independent claims are also included for the following: (a) a unit for the supply of colour to an electrostatic coating device; and (b) a connecting device for the aforesaid colour supply unit.

Description

The invention relates to a method for ink supply of an electrostatic coating device with coating material of alternating color according to the preamble of claim 1 and in particular according to EP 1 369 183 A2 ( DE 102 23 498 ). Furthermore, the invention relates to a suitable electrical isolation unit and a coupling device for this purpose.

In particular, it is the electrostatic serial coating of workpieces such as vehicle body with water paint frequently changing color or other coating material of similar high electrical conductivity, in which the problem of potential separation between the direct charging of the material to high voltage potential spray head of the coating device forming atomizer and grounded Part of his supply system occurs. In the EP 1 369 183 A2 In order to solve this problem described in detail there, a modular potential separation unit is proposed in which at least two paint reservoirs and one container each for a rinsing agent or for material to be disposed can be moved back and forth between high voltage and ground potential positions to form electrical insulating paths. The paint reservoirs are hereby docked in A / B operation on the one hand to the atomizer leading piggable connecting lines and on the other hand to the output channels of conventional color change valve assemblies (color changer) of the supply system. This mechanical electrical isolation has the advantage of maximum safety because of the reliable adjustment of the required insulation distances by air gaps. Compared to the potential isolation by means of damaged line sections ( EP 1 270 083 . EP 1 314 483 ) It also has the advantage that the coating material does not have to be reprinted during a color change or refilling process.

From the EP 1 245 295 is a color change system for a coating system of the type considered here is known, which instead of the hitherto common color change valve blocks (see, eg EP 0 979 964 and DE 198 46 073 ) consists of an arrangement of ink supply valves to which a connected to the atomizer valve is directly coupled. For mutual positioning, the ink supply valves and the atomizer-side valve are displaceable relative to each other linearly or in a circular motion. The media couplings formed by the valves can be shut off on one or both sides and can be piggable, especially when designed as a ball valve. The realization of a color changer by docking of the atomizer-side coupling part to a respective color associated coupling valves of the paint supply system has inter alia the advantage of a shortening of all colors common color line in the color changer whose length can be independent of the number of selectable colors, and thus a reduction in color and detergent losses in the color changer. However, the known system has the disadvantage that in many cases desired filling of the system with a predetermined and limited, for example, for the coating of a workpiece or workpiece area ink volume can be realized only within the leading to the atomizer hose, which not only with appropriate tax expense is connected, but also requires a correspondingly sized tube volume.

The invention has for its object to provide a method or a potential separation unit and a coupling device for this, with little effort and especially within the coating machine space-saving supply line arrangement enable a secure electrical isolation between the coating device and its grounded ink supply device. This should be achieved with minimal ink and detergent losses, especially during a color change.

This object is solved by the features of the claims.

The invention is based on the finding that in meaningful combination of in the EP 1 369 183 proposed paint supply system with the from EP 1 245 295 known color change system to take advantage of their respective advantages and achieve significant additional benefits.

On the one hand ensures the inventive mechanical separation of potential air gaps in a simple manner and with maximum certainty the required high voltage insulation of working with direct charging of the coating material atomizers, the desired filling of the system with, for example, according to the workpieces to be coated amounts of paint as in the mentioned proposed system in the inside the potential separation unit movable paint reservoir can be realized. Also results in a similar simple system with a preferably outside the paint booth mountable mountable application module as potential separation unit, which makes it possible to avoid high color and detergent losses in numerous leading to the atomizers and correspondingly long color lines in a color change. If only a paint hose or for the known and, inter alia, because of short color change times and in the interest of a continuous painting operation preferred A / B operation only two paint hoses For example, by laying a painting robot, this simplifies the high-voltage insulation, so that the robot's hand axis can be easily set to earth potential. The color hoses mentioned can be useful gemölcht. Since the tubing volume does not need to be adapted to the amount of material sized to coat a workpiece, high voltage insulated tubing and small diameter tubs can be installed. Since no 2-pig technology for potential separation is required, less complex pig stations with lower dead volume and correspondingly lower color change losses result. By simplifying the tube guidance in the robot and by relocating components of the potential separation system that are otherwise to be mounted on the robot arm to a position outside the cabin and also by using small and light atomizers, the dynamics of movement are improved.

On the other hand, by means of the system with color storage containers moved for color change, the colors of common long connecting channels in the color changer are avoided and correspondingly small color change losses of coating and rinsing media are made possible. Furthermore, when refilling the paint reservoir neither a pig ride nor the flushing of interfaces required.

As a result, the present invention solves the potential separation problem in a simple manner without losses of coating material and detergent caused by the potential separation. Incidentally, the system described here is characterized not only by low investment costs, but also by good maintenance properties. It is particularly advantageous that maintenance and repair of components hardly lead to interruptions of the coating operation when a large part of the application components not in the spray booth but easily accessible in an easily exchangeable isolation module outside the cab.

A potential isolation module according to the invention can be accommodated expediently in a housing which is highly voltage-insulated, preferably readily accessible outside the painting booth and possibly ventilated in a manner known per se in an explosion-proof manner. The module contains at least one, but preferably as an A / B system, two paint reservoirs connected to associated metering systems. For metering the coating material, piston dispensers installed outside the booth may be provided, or the paint reservoirs themselves may be designed as piston dispensers, but in many cases conventional gear or other metering pumps are preferred, which, especially when installed close to or in the atomizer, have the advantage of high metering accuracy and short dispensing response times to have. Further, for each selectable color, the module contains at least one paint supply system serving as a media coupling, which may be grounded. In the from the EP 1 245 295 known per se, these color supply valves can be arranged in one or two-dimensional groups, for coupling the ink reservoir these and / or the valve groups parallel to the plane of the valve assembly and slidably on reaching the Ankuppelposition for docking to each other can be moved. Furthermore, the potential separation module may include means for potential separation for a diluting or flushing medium as well as for an associated return line, for example with their own valves can be coupled to associated valves or only with movable coupling parts. Within the module there may be pig tracks which connect the paint reservoir (s) with connection points for the hose lines leading to the atomiser and in the manner known per se utilize the line located in the line Allow residual paint by "pushing out" to the atomizer and recovering unused paint by "reflow". Optionally, the potential isolation module may further include a high voltage generator and / or other components that may be needed, such as optoelectronic transducers for speed measurement, interrogation of the main needle position in the atomizer, and other sensors.

A full color change system according to the present invention includes, in addition to the potential isolation module described above, at least one or preferably two high voltage isolated battered hoses for the coating material, and preferably one high voltage isolated dilution and recycle tubing for A / B operation. These four hoses make the connection from the potential separation module to the atomizer as a hose package. The pig target stations are preferably located close to or in the atomizer. Optionally, in the spray booth a Zerstäuberwechselvorrichtung for in a conventional manner changeable atomizer are.

The according to another aspect of the invention not only, but in particular suitable for the described electrical isolation system coupling device has the particular advantage that it is possible with their pig body scrap paint residues in the clutch leak-free and completely without residues of the coupling channels.

Fig. 1

eine vereinfachte Darstellung eines Farbversorgungssystems mit einer Potenzialtrenneinheit;

Fig. 2

eine zweckmäßige Ausführungsform für einen Behälter des Systems nach Fig. 1;

Fig. 3

eine für die Potenzialtrenneinheit des Systems nach Anspruchs 1 geeignete Kupplungsanordnung; und

Fig. 4

eine andere mögliche Kupplungsanordnung.

In the embodiments illustrated in the drawings, the invention is explained in detail. Show it

Fig. 1

a simplified representation of a paint supply system with a potential separation unit;

Fig. 2

a suitable embodiment for a container of the system according to Fig. 1 ;

Fig. 3

a clutch assembly suitable for the potential isolation unit of the system of claim 1; and

Fig. 4

another possible coupling arrangement.

This in Fig. 1 shown color supply system includes a potential separation unit 1, to which a piggable conduit assembly 2 is connected to the ink supply of an atomizer 3, which can be mounted as a coating device, for example, on the wrist of a painting robot (not shown).

The potential separation unit 1 consists essentially of a paint supply unit 10, a container unit 12 and a color removal unit 14. The paint supply unit 10 has two groups of color supply valves 10A and 10B. The individual ink supply valves can be connected, for example, to a respective ring line for one of the selectable colors of the coating material, wherein the valve units 10A and 10B can be supplied with the same colors. The tank unit 12 includes two paint tanks 12A and 12B each provided with a port valve 13 for docking the tank 12A to each of the corresponding ink supply valves 10A and the tank 12B to each of the paint supply valves 10B. Similarly, the containers 12A and 12B can dock with their connection valve 13 to a respective color removal valve 14 provided in the ink extraction valve 14A and 14B, which are connected within the unit 14 each with a pig station 15A and 15B. From each of these pig stations leads one of the two pipe line 2 forming pig pipes 2A and 2B of the Potential separation unit 1, which may be arranged as a module outside a paint booth, into the cabin and, for example, by the robot arm to each one preferably located in the atomizer 3 pig target station 30A and 30B.

In the illustrated example, containers 12A and 12B may be reciprocated between valves 10A or 10B and 14A or 14B between stationary units 10 and 14, but embodiments are contemplated wherein the paint supply unit 10 may instead be docked and / or docked. or the color removal unit 14 and / or their clutch valves are moved. If the high voltage of the atomizer 3 is switched off when docking the container to the ink supply valves, a permanent connection between the containers 12A, 12B and the pig stations 15A, 15B is conceivable. For coupling the ink containers to the paint supply valves of the unit 10 and possibly other valves, only a relative movement between the containers and the valves is necessary per se.

An expedient arrangement of the paint supply valves 10A and 10B and their training as or with lockable media couplings is per se from the EP 1 245 295 known and therefore needs no detailed description here. In particular, the valves 10A and 10B may each be arranged in a straight row or even in a matrix of several parallel straight rows or instead on one or more arcs and from the containers 12A and 12B, respectively, with corresponding one or two dimensional linear movements and / or be approached on circular paths. For this purpose, the containers are initially moved parallel to the plane of the valve arrangement by drive devices (not shown) controlled automatically by a stored program of the coating installation. After reaching the respective desired color valve, the containers are then coupled to this by the movement perpendicular to the plane of the valve assembly and disconnected again after filling. Suitable servo drives are available for the movements of the containers and the couplings. Similarly, the containers may be coupled to and disconnected from the paint extraction valves 14A and 14B.

The entire ink supply unit 10 may be firmly earthed, whereby the ink containers are placed when connecting to ground potential. Since the containers 12A and 12B are separated from the paint extraction valves 14A and 14B by sufficiently large air gaps when coupled to the valves 10A and 10B, respectively, the required electrical isolation of the unit 10 from the high voltage potential connected to the valves 14A, 14B Atomizer 3 taken care of. When the containers 12A and 12B are again disconnected and removed from the valves 10A and 10B after filling and then coupled to the paint extraction valves 14A and 14B, respectively, to supply the atomizer 3 and consequently to the high voltage potential of the atomizer, the necessary electrical isolation occurs Air gap between the containers 12A, 12B and the ink supply unit 10. Since one of the two containers can be refilled in the manner described, while the other container is connected to the atomizer, this A / B operation allows a continuous supply of the atomizer. To reduce the cycle times in the series coating of workpieces, A / B / C operation could also be realized by a third system of ink supply valves, container and ink extraction valve.

As already mentioned, the potential separation unit 1 can also (not shown) means for potential separation for a flushing medium (usually thinner of the coating material) as well as for recycling to dispose of the flushing medium. For example, two further containers may be provided for this purpose, which, like the ink containers 12A and 12B, may be coupled on the one hand to corresponding valves of the paint supply unit 10 and on the other hand to the ink extraction unit 14. If the high voltage is switched off in the rinsing and recycling processes, which is possible in the series coating of workpieces such as vehicle bodies, in particular in the interval between two consecutive workpieces ("body gap"), in this case can also be dispensed with the electrical isolation.

The ink containers 12A and 12B may be, for example, as shown in FIG Fig. 2 is represented by a flushable cylinder 210 may be formed with a piston 211. The piston 211 may be driven by a motor (not shown) for filling and emptying the container or, instead, may be moved by a pressure medium such as compressed air or possibly by a relaxing compression spring when filled by the pressure of the supplied medium and emptying. The cylinder 210 is connected for filling and draining via a line 212 with an attached valve assembly 213 having a paint port F for coupling the container to one of the valves 10A, 10B, 14A or 14B, a connection V / PL for thinner and pulse air and a further connection RF for the feedback contains. These connections can consist of valves. Next to the container are valves such as 10A and 14A in Fig. 1 illustrated, to which it can be coupled with its color port F. With the connections V / PL and RF, the container can be docked to corresponding (not shown) coupling valves associated lines in the potential separation unit 1.

It is also conceivable, the ink containers 12A and 12B in a conventional manner ( DE 103 20 147 ) to operate as a metering cylinder for metering the atomizer 3 supplied coating material. In the paint supply system described here, however, it may be preferable to arrange a conventional or other metering pump directly on or preferably in the atomizer 3 for metering the coating material.

In the context of the invention, there are further possibilities for the realization of the ink containers 10A and 10B, such as the use of a molded hose spiral with a tube volume corresponding to the desired filling quantity.

In Fig. 3 and 4 2 schematically shows two different embodiments of media couplings, not only, but in particular for the realization of the ink supply valves 10A and 10B, the connection valves 13 and the paint extraction valves 14A and 14B of the ink supply system Fig. 1 can be used and both have the advantage that they are virtually dead space and allow easy disconnection of the coupling parts, for example, without leakage of the possibly in operation passed under pressure paint or other medium. If no color change takes place, but, for example, the container 12A or 12B is only refilled with the same color, these couplings do not have to be purged, or at least not at every coupling operation, so that the otherwise occurring time and flushing losses are avoided.

In the Fig. 3 The coupling device shown essentially consists of two separable and mergeable coupling parts 41 and 42. The one coupling part 42 includes a first channel 43, which may be connected via a connecting channel 46, for example, to a ring line for the color in question when the coupling part 42 for the realization of one of the paint supply valves 10A, 10B in Fig. 1 serves. The other coupling part 41 may be located in the considered case on the container 12A and includes a second channel 44 which is connected to a leading to the container 12A (and thus indirectly to the atomizer 3) leading channel 47. The two channels 43 and 44 expediently consist of cylindrical chambers which are exactly aligned with one another in the case of merged coupling parts and are enclosed in the connecting plane of the coupling parts 41 and 42 as shown by a sealing ring 48. For the merger, a (not shown) centering device is present. For example, on the opposite side to the channel 47 of the channel 44, this can also be connected to a flushing channel 49 for thinner and possibly pulse air. The channels 46, 47 and 49 are preferably provided with automatically controlled needle or other shut-off valves whose valve seat is disposed directly on the channels 43 and 44, respectively.

A peculiarity of in Fig. 3 represented dead space and flushable coupling according to the invention is that when merging coupling parts 41 and 42, a pig body 45 between the two channels 43 and 44 back and forth and here rests with its sealing edges or wiper lips close to the channel walls. The pig body 45, moving in the manner of a piston, is fastened to a piston rod 50 driven by an automatically controlled motor (not shown) for this purpose. Preferably, it is as a chamber or Tandemmolch or double-lip piston in the EP 1 172 153 respectively. EP 1 252 936 formed in the annular space 53 between the both end portions provided with sealing edges thinner, for example, is passed through a purge passage 54 which is provided with an associated valve. With this thinner, the pig flushes its walls through the channels 43 and 44 as it moves. At the location of the flushing channel 54, where the pig body 45 can be filled with diluent, there is also a return channel 55 which can also be closed by a valve.

The piston rod 50 and its mechanical drive are preferably in the atomizer-side coupling part, here in the container unit 12, since in contrast to the ink supply unit 10 only a single pig with associated drive is required and not one pig per color. To seal the piston rod guide a seal 51 is provided on the coupling part.

For example, to explain the operation of this clutch, suppose that the paint container 12A is to be coupled to one of the ink supply valves 10A for refueling with the same color Fig. 3 After the merging of the two coupling parts 41 and 42 with mutual sealing of the pig 45 is first from the coupling part 41 in his in Fig. 3 pushed lowest position in the coupling part 42. Behind the pig can be nachgeschoben by the channel 47 color from the container 12 A, so that the channels 43 and 44 are filled without air. Then, the color valve of the connecting channel 46 is opened at the coupling part 42 connected to the ring line, so that the relevant color flows into the coupling. After filling the container 12A, the paint valve is closed again and the pig 45 is driven by the piston rod 50 back into the other coupling part 41, wherein the interior of the coupling by the in the space 53 of the Molch located thinner and rinsed cleaned. In the case of a color change, the channels 43 and 44 can be rinsed and dried from the channel 49 prior to separation of the coupling parts 41, 42 or after their later re-merging with thinner and pulse air, the pig body 45 can perform similar movements as when refueling.

Also in Fig. 4 shown two-stage operated dead space-free media coupling consists of two separable and centered merge coupling parts 61 and 62. The coupling member 61 is also here, for example, on the container 12A, while the other coupling part 62 similar to the part 42 in Fig. 3 arranged in the ink supply unit 10 and connected via the connecting channel 63 to the relevant ring line. Between the two coupling parts 61 and 62 is a seal 64th

In the coupling part 61 is sealed to the outside at 65 a hollow needle 70 along a central axis 66 of the clutch preferably slidably mounted (or possibly also fixed). The interior of the hollow needle 70 is connected via a channel leading through the coupling part to the container 12A and by a coaxially arranged in the hollow needle, along the axis 66 displaceable valve needle 71 closed at the front end of the hollow needle 70 formed valve seat 72 when the coupling parts separately are.

In the coupling part 62 is shown a coaxial with a coupling to the central axis 66 cylindrical channel 75, which initially conically narrows to the perpendicular or transverse to the axis 66 extending parting plane 68 of the coupling parts and then up to the parting plane 68 funnel-like again extended. The funnel-like Extension 76 is based on the two coupling parts 61, 62 common parting plane 68 so deep that it receives over the parting plane projecting tip of the hollow needle 70 and forms a seat for the hollow needle tip. At the hollow needle point and / or at its seat on the wall of the extension 76, a further seal 77 is provided, so that the interior of the hollow needle 70 is sealed to the channel 75 is connected.

In the channel 75, a further valve needle 80 is coaxially arranged, the conical tip 81 rests with separate coupling to the adjacent to the extension 76 conical inner wall 82 of the channel 75 to close the channel to the outside. The valve needle 80 is slidably mounted in the coupling part 62 and opens the channel 75 in the direction of the coupling part 61 when coating material from the connecting channel 63 is to flow into the hollow needle 70, the interior of which is opened for this purpose by coaxial displacement of the inner valve needle 71, while the hollow needle rests tightly in the extension 76 on the coupling part 62.

In the coupling part 61 opens radially outside the hollow needle 70, but within the seal 64 provided with a further valve channel 85 for thinner and pulse air in the parting plane 68. For example, at a corresponding point on the radially opposite side of the hollow needle 70 opens a return channel 86th for the thinner. In the case of merged coupling parts 61 and 62, the inner space of the coupling surrounding the hollow needle tip and, with the corresponding position of the hollow needle 70 and the valve needle 80, can thereby also be flushed and dried the interiors opened thereby.

For example, if paint is to be refilled by this media coupling, the two coupling parts 61 and 62 are brought together for coupling the ink container 12A to one of the ink supply valves and sealed together by means of the seal 64. Then, the hollow needle 70 is operated in two stages, i. its tip is pressed against the inner wall of the extension 76 and opened by parallel displacement of the inner valve needle 71. By displacement of the valve needle 80, the ink path is released from the connecting channel 63 into the interior of the hollow needle 70 and from there to the paint container. After filling the container, the hollow needle 70 is moved back again, wherein a possibly remaining, due to the illustrated design but in any case very small color residue can remain in the coupling member 62. If necessary, after certain time intervals via the valves of the channels 85 and 86, an intermediate flushing of the coupling parts take place. In any case, the clutch is flushed in a color change in this way.

With regard to the described color change system and the media couplings, the invention is not limited to potential separation systems, but for example, suitable for non-electrostatic coating systems, for example with air atomizers. On the other hand, the potential separation unit described is not limited to color change systems, but more generally advantageous wherever two lying at different potential parts of a material supply system to be connected and disconnected.

Claims (18)

1. A method of supplying an electrostatic coating device (3) with coating material of varying colours,
   in which the coating material coming from a receptacle (12A, 12B) in an electrical isolation unit (1), which is connected to a paint supply unit (10) at earth potential, flows through an in particular piggable connecting line arrangement (2) to the coating device (3),
   and in which the coating material in the connecting line arrangement (2) is pushed in particular by a pig towards the coating device (3) and/or back towards the paint supply unit (10),
   a receptacle (12A, 12B) being coupled in the electrical isolation unit (1) to the paint supply unit (10) and filled, while it is uncoupled from a connection line (2A, 2B) leading to the coating device (3) and is separated therefrom, so forming electrical insulating clearance, and being coupled for emptying to the connection line (2A, 2B), while it is uncoupled from the paint supply unit (10) and separated therefrom, so forming electrical insulating clearance,
   wherein the paint supply unit (10) has a respective paint supply valve (10A, 10B) for each of the different selectable colours,
   characterized in that the receptacle (12A, 12B) is coupled directly to the paint supply valve (10A, 10B) for the colour used in each case.
2. The method according to claim 1, characterized in that the receptacle (12A, 12B) is moved to-and-fro by an automatically controlled drive apparatus between the paint supply valves (10A, 10B) and a paint withdrawal valve (14A, 14B), to which the connection line (2A, 2B) leading to the coating device (3) is connected.
3. The method according to claim 1 or claim 2, characterized in that the coating device (3) is supplied from a first receptacle (12A) coupled to the paint withdrawal valve (14A) of a first connection line (2A) while a second receptacle (12B) is coupled to one of the paint supply valves (10B) and filled, and in that the second receptacle (12B) is then coupled to the paint withdrawal valve (14B) of a second connection line (2B) leading to the coating device (3).
4. The method according to any one of claims 1 to 3, characterized in that, for coupling to the paint supply valves (10A, 10B) arranged in a common plane, the receptacle (12A, 12B) is moved parallel to this plane in straight directions positioned transversely of one another or on at least one circular path.
5. An apparatus for supplying an in particular electrostatic coating device (3) with coating material of different colours
   having a paint supply unit (10), which comprises at least one paint supply valve (10A, 10B) for each of the different selectable colours,
   having at least one connection line (2A, 2B) connected or connectable to the coating device (3),
   having at least one receptacle (12A, 12B), which is provided with a coupling means (13) for coupling to the paint supply unit (10) and/or to the connection line (2A, 2B),
   and having an automatically controlled drive apparatus for relative movement between the receptacle (12A, 12B) and the paint supply valves (10A, 10B) and/or the connection line (2A, 2B),
   characterized in that the receptacle (12A, 12B) is provided with a connecting valve (13), with which it can be coupled directly to each of the paint supply valves (10A, 10B) for the different colours and on the other hand to a paint withdrawal valve (14A).
6. The apparatus according to claim 5, characterized in that the receptacle (12A, 12B) is connected to an automatically controlled drive apparatus, with which it can be moved parallel to a plane, in which the paint supply valves (10A, 10B) are arranged, in straight directions positioned transversely of one another or on at least one circular path.
7. The apparatus according to claim 5 or claim 6, characterized in that the receptacle (12A, 12B) can be moved to-and-fro between the paint supply valves (10A, 10B) and a paint withdrawal valve (14A, 14B) of the connection line (2A, 2B).
8. The apparatus according to any one of claims 5 to 7, characterized in that the connection line (2A, 2B) is piggable, and in that the paint withdrawal valve (14A, 14B) of the connection line is arranged at a pig station (15A, 15B).
9. The apparatus according to any one of claims 5 to 8, characterized in that the paint supply valves (14A, 14B), the receptacle (12A, 12B) and the paint withdrawal valve (14A, 14B) of the connection line (2A, 2B) are accommodated in a housing of an electrical isolation module (1) mountable for example outside a spray booth.
10. The apparatus according to claim 9, characterized in that the electrical isolation module (1) contains lines for a flushing medium and electrical isolation means for these lines.
11. The apparatus according to any one of claims 5 to 10, characterized in that the coupling means of the receptacle (12A, 12B) preferably takes the form of an automatically controllable shut-off valve (13).
12. A coupling means for the apparatus according to any one of claims 5 to 11 having two coupling parts (41, 42) capable of being separated and brought together,
    wherein the one coupling part (42) includes a first central duct (43) connected or connectable to a line (46) for coating material, whereas the other coupling part (41) includes a second central duct (44), which is connected or connectable to a line (47) leading to a coating device (3) or to a receptacle (12A, 12B) connected to the coupling part (41) and is aligned with or oriented on the same axis as the first duct (43) when the coupling parts (41, 42) have been brought together,
    characterized in that a pig body (45) is provided which, when the coupling parts (41, 42) have been brought together, can be moved to-and-fro between the two central ducts (43, 44) and here rests with its sealing edges or scraping lips tight against the duct walls.
13. The coupling means according to claim 12, characterized in that the pig body (45) has an annular interspace (53) at its circumference between the sealing edges or scraping lips, which annular interspace can be filled with a flushing medium from a flushing duct (54) opening in the inner wall of one of the two central ducts (44).
14. The coupling means according to claim 12 or claim 13, characterized in that one of the coupling parts (41) includes a flushing duct (49) for introducing a flushing medium into the central ducts (43, 44) outside the pig body (45).
15. The coupling means according to any one of claims 12 to 14, characterized in that the pig body (45) is fastened to a mechanically driven piston rod (50).
16. The coupling means according to the preamble of claim 12, characterized in that one or both of the coupling parts (61, 62) in each case include an automatically actuatable valve needle (71, 80) arranged displaceably in its central duct (70, 75), with which valve needle the duct (70, 75) can be closed towards the outside of the coupling part forming the separation plane (68) of the coupling parts (61, 62).
17. The coupling means according to claim 16, characterized in that the valve needle (71) of the one coupling part (61) is arranged in a hollow needle (70) forming the central duct,
    in that the tip of the hollow needle (70) including the valve seat (72) for the valve needle (71) projects beyond the separation plane (68) of this coupling part (61),
    and in that the other coupling part (62) has a widened portion (76) of its central duct (75) forming a seat for the tip of the hollow needle (70).
18. The coupling means according to claim 16 or claim 17, characterized in that a duct (85) provided with a valve opens in the separation plane (68) of one of the coupling parts (61), which duct (85) is connected or connectable to a source for a flushing medium.

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