EP3112177B1 - Coating device and associated coating method - Google Patents

Description

The invention relates to a coating device for coating, in particular painting of motor vehicle body components. Furthermore, the invention relates to a corresponding coating method.

FIG. 1 shows a cross-sectional view through a conventional paint shop for painting automotive body components. Here, the vehicle body components to be painted are transported on a conveyor 1 at right angles to the plane through a painting booth 2, in which the vehicle body components are then painted by painting robots 3, 4 in a conventional manner. The painting robots 3, 4 have a plurality of pivotable robot arms and each lead via a multi-axis robot hand axis an application device, such as a rotary atomizer, an air atomizer or a so-called airless device.

A disadvantage of these known application devices, however, is the non-optimal application efficiency, so that a designated as overspray part of the sprayed paint does not land on the vehicle body part to be painted and must be removed with the cabin air from the spray booth 2. Therefore, a so-called plenum 5, is introduced from the air through a ceiling 6 of the spray booth 2 down in the direction of arrow in the paint booth 2 above the spray booth 2. The cabin air then passes with the contained therein overspray down from the spray booth 2 in a below the spray booth 2 located leaching 7, in which the overspray is removed again from the cabin air and bound to water.

This wastewater with the overspray contained therein must then be re-processed in a complex process, the resulting paint sludge is a hazardous waste and must be disposed of consuming.

In addition, the Luftsinkgeschwindigkeit in the spray booth 2 must be at least in the range of about 0.3-0.5 m / s in order to quickly remove the resulting during painting overspray from the spray booth 2.

Further, the resulting when painting overspray can temporarily and locally create a potentially explosive atmosphere, so that the relevant legal ATEX product policies (ATEX: At phere ex plosible) must be observed.

On the one hand cause the known application devices so because of their unsatisfactory order efficiency and the resulting overspray high investment costs for the required leaching and the necessary explosion protection.

On the other hand, the known application devices are also associated with high operating costs due to the paint losses and the disposal costs for disposal of the overspray due to the resulting in operation overspray.

The invention is therefore based on the object to provide a corresponding improvement.

EP 1 449 667 A1 discloses an ink jet printer for generating image pixels having different gray levels. For this purpose, two adjacent print heads are provided in various embodiments, each containing a plurality of arranged in a row nozzles of different sizes to produce correspondingly different sized ink drops. In one embodiment, the nozzles of one printhead are larger than the nozzles of the other printhead, while in a second embodiment, both printheads alternately contain large and small nozzles, each large and small nozzles being adjacent the row in the transverse direction. In order to achieve desired gray values of the individual pixels, drops from both print heads are mixed with each other.

JP H09-164706 A discloses a further inkjet printer for printing lines of paper with the individual pixels, for example of letters, with several rows of nozzles of different sizes producing dots of different sizes which can superimpose respective desired gray values in the individual rows.

The above object is achieved by a coating device according to the invention and a corresponding coating method according to the independent claims.

The invention comprises the general technical teaching of using an application device with such a high degree of application efficiency that leaching can be dispensed with, in which convention the overspray is washed out of the cabin air. An advantage of the coating device according to the invention is therefore in the preferred embodiment is that can be dispensed with a separate leaching. However, the invention is not on Limited painting, which have no leaching at all. Rather, by the use of application equipment with a higher order efficiency, the possibility of a smaller dimensioning of the leaching, if a complete waiver is not possible.

Preferably, the application device is a printhead, as used in similar form, for example in inkjet printers. For example, it may be a bubble jet printhead or a piezo printhead. However, the invention is not limited to Bubble Jet printheads and piezo printheads in terms of the technical principle of the printhead used, but in principle also with other ejection mechanisms feasible.

Furthermore, it is within the scope of the invention, the possibility that the print head ejects the coating agent pneumatically. For example, the individual coating agent drops can be ejected by short air pulses, which the coating agent drops in the direction of the coated Speed component, whereby the painting distance can be increased.

It should also be mentioned that the print head can eject the coating agent optionally in individual coating agent droplets or continuously. In addition, within the scope of the invention, it is possible that a part of the coating agent nozzles of the print head continuously ejects the coating agent, whereas another part of the coating agent nozzles of the print head ejects the coating agent in individual coating agent droplets.

According to the invention, the print head is positioned by a multi-axis robot, wherein the robot preferably comprises a plurality of pivotable robot arms and a multi-axis robot hand axis to which the print head is mounted.

In contrast to the conventional printheads, which are used for example in inkjet printers, the printhead in the coating device according to the invention preferably has a much larger surface coating performance, preferably greater than 1m ² / min., 2m ² / min., 3 m ² per minute or 4m ² / min. is.

In contrast to conventional inkjet printers, the printhead in the coating device according to the invention must also be able to apply liquid lacquers which contain solid lacquer constituents, such as, for example, pigments and so-called metallic flakes (Mika's). The individual coating agent nozzles of the print head are therefore preferably adapted in terms of their size to the solid paint components, so that the print head can also apply paints with the solid paint components.

Also in the case of the coating device according to the invention, the application device is preferably arranged in a painting booth in which the components are coated with the coating agent. Such paint booths are known from the prior art and therefore need not be described in detail.

However, it has already been mentioned above that the printheads used in the context of the invention as application devices have a much greater application efficiency than conventional application devices, such as rotary atomizers. The leaching located below the spray booth can therefore be dimensioned substantially smaller than in conventional spray booths with rotary atomizers as application devices. In one embodiment of the invention, the high degree of application efficiency of the printheads used as application devices even allows a complete elimination of leaching or other complex filtering measures, such as dry separation or the like. below the paint booth. Sufficient are in In this case, simple filters that are replaced or cleaned cyclically (eg weekly, monthly, semi-annual or yearly).

Furthermore, the high degree of application efficiency of the printheads used as application devices in the invention makes it possible to dispense with explosion protection measures in accordance with the relevant statutory ATEX directives, since less overspray is generated and therefore no potentially explosive atmosphere arises during operation. In one embodiment of the invention, therefore, no explosion protection is provided in the paint booth.

However, in the case of the coating device according to the invention, it is also preferable to provide an air extraction system which sucks the cabin air out of the painting booth, with the suction preferably taking place downwards. The cabin air is in this case preferably sucked off by an air filter which filters the overspray from the cabin air, wherein the air filter may be formed, for example, as a filter cover, which is arranged at the bottom of the paint booth, so that the cabin air sucked through the filter cover from the paint booth down becomes.

Due to the greater order efficiency of the printheads used in the invention as application devices and the lower overspray, the air sink rate in the spray booth can be lower than in conventional spray booths, which use, for example, rotary atomizers as application devices. In the paint shop according to the invention, the air sink rate in the paint booth can therefore be less than 0.5 m / s, 0.4 m / s, 0.3 m / s, 0.2 m / s or 0.1 m / s.

In one variant of the invention, at least one color changer is associated with the print head, which is connected on the output side to the print head and supplied with various coating agents on the input side, so that the color changer selects one of the coating agents and feeds the print head with the selected coating agent.

In addition, the color changer on the input side can be supplied with various effect coatings, such as special paints, metallic paints or mica paints.

In one embodiment of the invention, the color changer outputs on the output side each a group of several coating agent nozzles with the same coating agent, wherein the coating agent nozzles can be arranged, for example, in a row, for example in a row or a column.

It is also possible for the color changer on the input side to be preceded by a color mixer, which is supplied on the input side with differently colored coating agents in the primary colors of a color system (for example CMYK color system). The color mixer can then mix together a desired color tone from the different primary colors of the respective color system and provide it to the color changer for selection. In addition, the color changer in this embodiment is preferably supplied with at least one effect varnish, for example a mica varnish, a metallic varnish and / or a special varnish. The color changer can then either select the color shade mixed together by the color mixer or access one of the effect colors.

It has already been mentioned above that the coating agent nozzles in the print head can be arranged in rows, for example, in rows and columns. Preferably, the coating agent nozzles are thus arranged in the form of a matrix in the printing head.

In the context of the invention, it is possible that all coating agent nozzles of the print head or at least a large part thereof are connected together to a single coating agent feed line and therefore apply the same coating agent.

Alternatively, within the scope of the invention, it is possible that a part of the coating agent nozzles of the print head is connected to a first coating agent feed line, while a second part of the coating agent nozzles of the print head is connected to a second coating agent feed line, so that the print head can apply two different coating agents. Preferably, the coating agent nozzles in the individual rows of nozzles (rows or columns) are in this case connected alternately with the one coating agent supply line or with the other coating agent supply line.

In one embodiment of the invention, the print head has at least one separate coating agent nozzle, which applies only effect paint with effect particles contained therein. In addition, the print head then preferably has at least one further coating agent nozzle which applies normal paint which contains no effect particles. The various coating agent nozzles can then be adjusted accordingly.

It is also conceivable that in the color mixing process described above, the effect particles (eg metallic, mica, etc.) with a separate Beschichtungsmitteldüse on the object be applied. As a result, effects can be applied specifically to the object with local differences. Also under certain circumstances effects can be generated that are unthinkable today. With the new inkjet technology, it is possible to place effect particles only on the surface of the layer, for example.

Furthermore, it is a major advantage of the invention that it is possible for the first time ever to coat a complete body with sufficient area performance with the solution according to the invention, but also to selectively print details and graphics.

It has already been mentioned above that the coating agent nozzles in the print head are preferably arranged in matrix form in a plurality of rows and columns. In this case, the adjacent rows of nozzles can be arranged offset from each other in the longitudinal direction, in particular by half a nozzle width, which allows a maximum packing density of the coating agent nozzles in the nozzle head. In addition, the individual rows of nozzles are preferably aligned transversely, in particular at right angles to the feed direction of the nozzle head.

In one embodiment of the invention, for example, nozzle rows with large coating agent nozzles and rows of nozzles with small coating agent nozzles may be arranged alternately in the print head. It may be useful if the nozzle rows are arranged offset with the larger coating agent nozzles relative to each other, in particular by half a nozzle width.

In another variant of the invention, the print head is rotatably mounted and rotates during the coating. Again, the printhead different sized coating agent nozzles , wherein the smaller coating agent nozzles are preferably arranged closer to the axis of rotation of the print head than the larger coating agent nozzles.

In another variant of the invention, a plurality of print heads are provided, which are guided jointly by a multi-axis robot and are pivotable relative to one another, which allows adaptation to curved component surfaces.

It has already been mentioned above that, for example, a special lacquer, a metallic lacquer or a mica lacquer can be used as the effect lacquer.

Furthermore, it may be advantageous to at least partially provide the surface areas of the print head (eg lines) which come into contact with the coating agent with a wear-reducing coating, such as, for example, a DLC coating (DLC: diamond-like carbon), a diamond coating, a hard metal or a material combination of a hard and a soft material. Furthermore, the surface areas of the print head which come into contact with the coating agent can be coated with titanium nitride, titanium oxide or chemical nickel or with another layer which is PVC (Physical Vapor Deposition) in the CVD process (CVD: Chemical Vapor Deposition ) or in the anodizing process (anodizing: electrolytic oxidation of aluminum) or provided with an "easy-to-clean" coating.

Further, to improve the application efficiency of the printhead, electrostatic coating agent charging and / or compressed air assist may be provided.

Another possibility is a position detection which detects the spatial position of the print head and / or the component surface to be coated and controls or regulates the positioning of the print head accordingly.

Currently, there are also efforts to mix automotive coatings directly in the paint shops from 6-10 base pastes. For this purpose, the pastes are mixed in a conventional manner in mixing stations and adjusted the color tones. From these pastes all, used in the automotive industry paints (uni, metallic and mica or effect paints) can be produced. It is conceivable that these pastes are mixed directly in the atomizer or an upstream device. This has the advantage that only the required amount is provided fully automatically directly before or during the application. The dosage of the individual components can be done with the known dosing techniques (pressure regulator, dosing pumps, gear measuring cells, flow cells, piston dispensers, ...). The "mixing space" may be a mixing chamber, a piece of tubing or a mixing system (e.g., Keenix mixer). The problem is the very precise dosage of the individual components to make the exact color. Therefore, a color sensor for controlling the metering unit may be useful.

However, the dosing technique can also be inkjet technology. In this case, the required amount of individual droplets that are dependent on the opening time of the nozzle and the pressure can be generated. These inkjet nozzles in turn mix the color in a mixing room.

Furthermore, it is within the scope of the invention, the possibility that a sensor is provided, the course of a guideway detected to position the print head with respect to the guideway.

In a preferred embodiment, the sensor is mounted on the printhead or on the robot, but in principle other constructions are possible. For example, the sensor can detect the preceding painting track, so that the current painting track can be applied in a specific relative position relative to the preceding painting track. Thus, it is generally desirable that the current coating path is applied at a certain distance parallel to the preceding coating path, which is possible by the sensor detection described above.

In the preferred embodiment, the sensor is an optical sensor, but in principle, other types of sensors are possible.

The aforesaid guideway may also be a separate web which is applied only for guidance purposes and may comprise, for example, a normally invisible color which is visible to the sensor only when illuminated with ultraviolet (UV) or infrared (IR) light.

In this context, there is also the possibility of using a laser measuring system, as is known per se from the prior art. Such a laser measuring system can also detect the distance to the surface of the component to be coated and keep it constant within the scope of a regulation.

In this variant of the invention, a robot controller is provided, which is connected on the input side to the sensor and on the output side to the robot, the robot controller controlling the Printhead positioned as a function of the course of the guideway.

In one variant of the invention, the printhead has an enveloped stream nozzle which emits an enveloping stream of air or another gas, the enveloping stream enveloping the coating medium stream emitted from the coating compound nozzle in order to atomize or delineate the coating agent droplets. In addition, this envelope flow in the form of an air curtain can direct the resulting overspray on the component surface, whereby the order efficiency is improved.

In one embodiment of the invention, the printhead has a plurality of coating agent nozzles juxtaposed with respect to the web direction, with the outer coating agent nozzles delivering less coating agent than the inner coating nozzles, resulting in a corresponding layer thickness of the pitch transverse to the web direction. It is not necessarily arranged nozzles in a row. It can be controlled for each nozzle and each pixel, the amount of color. By different amounts of color z. B. also controlled the hue intensity. In this case, there is the possibility that the layer thickness distribution is a Gaussian normal distribution. Alternatively, there is the possibility that the amount of coating agent dispensed from the individual coating agent nozzles is selected such that the layer thickness distribution is a trapezoidal distribution. Such a trapezoidal layer thickness distribution is advantageous because the adjacent coating center webs can overlap one another such that the superimposition of the trapezoidal layer thickness distributions of the adjacent coating center webs leads to a constant layer thickness.

In another embodiment of the invention, the components to be coated are conveyed along a conveying path, which is known per se from the prior art of paint shops and therefore need not be described in detail. In this embodiment, a portal spans the conveying path, wherein on the portal numerous print heads are mounted, which are directed to the components on the conveying path and coat these components.

Finally, the invention also includes a corresponding coating method, as already apparent from the above description.

The technology according to the invention can also be used for the targeted coating of cut edges of pre-coated sheets, stamped sheets or for the efficient sealing of seams and edges

Figur 1

eine Querschnittsansicht durch eine herkömmliche Lackieranlage zur Lackierung von Kraftfahrzeugkarosseriebauteilen,

Figur 2

eine Querschnittsansicht durch eine erfindungsgemäße Lackieranlage zur Lackierung von Kraftfahrzeugkarosseriebauteilen mit Druckköpfen als Applikationsgeräte,

Figur 3

eine Düse des Druckkopfs mit einem Farbwechsler und der zugehörigen Beschichtungsmittelversorgung,

Figur 4A

eine Düsenreihe mit mehreren Beschichtungsmitteldüsen und einem zugeordneten Farbwechsler

Figur 4B

eine Abwandlung von Figur 4A, wobei der Farbwechsler eingangsseitig nur eine einzige Sonderfarbversorgung aufweist,

Figur 5

eine Abwandlung von Figur 4A, wobei der Farbwechsler eingangsseitig mit einem Farbmischer verbunden ist, der mit den Grundfarben eines Farbsystems versorgt wird,

Figur 6

eine Düsenreihe des Druckkopfs, wobei vier benachbarte Beschichtungsmitteldüsen über einen Farbmischer mit einem gemischten Farbton versorgt werden, während die fünfte Beschichtungsmitteldüse über einen Farbwechsler einem Effektlack versorgt wird,

Figur 7

mehrere Düsenreihen des Druckkopfs, die gemeinsam über einen Farbmischer mit einem Mischfarbton versorgt werden,

Figur 8

mehrere Düsenreihen des Druckkopfs, die gemeinsam über einen Farbwechsler und einen Farbmischer mit dem zu applizierenden Beschichtungsmittel versorgt werden,

Figur 9

mehrere Düsenreihen des Druckkopfs, die gemeinsam über eine einzige Beschichtungsmittelzuleitung versorgt werden,

Figur 10

ein Schema zur Verdeutlichung der Lackierung einer scharfen Kante mit dem erfindungsgemäßen Druckkopf,

Figur 11

einen rotierenden Druckkopf,

Figur 12

eine Druckkopfanordnung mit mehreren verschwenkbaren Druckköpfen zur Anpassung an gekrümmte Bauteiloberflächen,

Figur 13

ein schichtförmig aufgebautes Pixel mit mehreren Schichten in den Grundfarben eines Farbsystems und einer obersten Schicht aus einem Metalliclack,

Figur 14

eine schematische Darstellung einer erfindungsgemäßen Beschichtungseinrichtung mit einem mehrachsigen Roboter, der einen Druckkopf und einen Sensor führt, um den Druckkopf zu positionieren,

Figur 15

eine schematische Darstellung einer erfindungsgemäßen Beschichtungseinrichtung, bei der mehrere Komponenten zu einem Gemisch zusammengemischt werden, wobei der Druckkopf dann das Gemisch appliziert,

Figur 16

eine schematische Darstellung eines erfindungsgemäßen Druckkopfs, der mehrere Komponenten unabhängig voneinander appliziert, wobei die Mischung auf der Bauteiloberfläche erfolgt,

Figur 17

eine schematische Darstellung eines erfindungsgemäßen Druckkopfs mit einer Hüllstromdüse,

Figur 18

eine schematische Darstellung eines erfindungsgemäßen Druckkopfs, bei dem die Beschichtungsmitteltropfen pneumatisch ausgestoßen und beschleunigt werden,

Figur 19

eine schematische Darstellung eins Druckkopfs, der eine trapezförmige Schichtdickenverteilung erzeugt,

Figur 20

eine schematische Darstellung einer erfindungsgemäßen Beschichtungseinrichtung, bei der zahlreiche Druckköpfe an einem Portal angebracht sind,

Figur 21

eine Düsenanordnung mit einer maximalen Packungsdichte der einzelnen Düsen.

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

FIG. 1

a cross-sectional view through a conventional paint shop for painting automotive body components,

FIG. 2

a cross-sectional view through an inventive paint shop for painting automotive body components with printheads as application devices,

FIG. 3

a nozzle of the print head with a color changer and the associated coating agent supply,

FIG. 4A

a row of nozzles with several coating agent nozzles and an associated color changer

FIG. 4B

a modification of FIG. 4A , wherein the color changer has on the input side only a single spot color supply,

FIG. 5

a modification of FIG. 4A in which the color changer is connected on the input side to a color mixer which is supplied with the primary colors of a color system,

FIG. 6

a nozzle row of the printhead, wherein four adjacent coating agent nozzles are supplied with a mixed color tone via a color mixer, while the fifth coating agent nozzle is supplied with an effect varnish via a color changer,

FIG. 7

several nozzle rows of the print head, which are supplied together via a color mixer with a mixed color,

FIG. 8

several nozzle rows of the print head, which are supplied together via a color changer and a color mixer with the coating agent to be applied,

FIG. 9

several nozzle rows of the print head, which are supplied together via a single coating agent feed line,

FIG. 10

a scheme for clarifying the coating of a sharp edge with the printhead according to the invention,

FIG. 11

a rotating printhead,

FIG. 12

a printhead assembly having a plurality of pivotable printheads for conforming to curved component surfaces;

FIG. 13

a layered pixel with several layers in the primary colors of a color system and a top layer of a metallic paint,

FIG. 14

a schematic representation of a coating device according to the invention with a multi-axis robot, which leads a printhead and a sensor to position the print head,

FIG. 15

1 is a schematic representation of a coating device according to the invention in which a plurality of components are mixed together to form a mixture, wherein the print head then applies the mixture,

FIG. 16

a schematic representation of a printhead according to the invention, which applies several components independently, wherein the mixture takes place on the component surface,

FIG. 17

a schematic representation of a printhead according to the invention with a jacket nozzle,

FIG. 18

a schematic representation of a printhead according to the invention, in which the coating agent drops are ejected and accelerated pneumatically,

FIG. 19

a schematic representation of a printhead, which generates a trapezoidal layer thickness distribution,

FIG. 20

a schematic representation of a coating device according to the invention, in which numerous print heads are mounted on a portal,

FIG. 21

a nozzle assembly with a maximum packing density of the individual nozzles.

The cross-sectional view in FIG. 2 shows a painting according to the invention, which partially with the initially described and in FIG. 1 In order to avoid repetition, reference is made to the above description, the same reference numerals being used for corresponding details.

A special feature of the painting plant according to the invention consists firstly in that the painting robots 3, 4 as application device no rotary atomizers lead, but printheads 8, 9, which have a much larger order efficiency of more than 95% and therefore produce significantly less overspray.

On the one hand, this offers the advantage that in accordance with the conventional paint shop FIG. 1 existing leaching 7 can be dispensed with.

Instead, located in the paint shop according to the invention under the spray booth 2, an air suction 10, which sucks the cabin air through a filter cover 11 down from the spray booth 2. The filter cover 11 filters out the excess air in the cabin air overspray out without the leaching 7 is required as in the conventional painting.

The printheads 8, 9 operate in this embodiment as conventional printheads according to the piezo principle, however, the surface coating performance of the printheads 8, 9 compared to conventional printheads substantially larger, so that the motor vehicle body components can be painted with a satisfactory operating speed.

FIG. 3 shows a coating agent nozzle 12, which is arranged in each case in the print heads 8, 9 in addition to numerous other coating agent nozzles, wherein the coating agent nozzle 12 is supplied by a color changer 13 with the coating agent to be applied. On the input side, the color changer 13 is connected to a total of seven coating agent supply lines, of which the color changer 13 can select one for coating agent supply of the coating agent nozzle 12. Four coating agent supply lines of the color changer 13 are used to supply different colored coating agents in the basic colors C (cyan), M (magenta), Y (yellow = yellow) and K (key = black). The other three coating agent supply lines of the color changer 13 on the other hand serve to supply a metallic lacquer, a mica lacquer and a special lacquer.

In this embodiment, the desired hue of the coating agent is mixed on the vehicle body component to be coated, with either temporal or local mixing being possible.

In a temporal mixture, for example, successively coating agent droplets in the primary colors C, M, Y and K are applied in the desired color ratio, so that the coating agent droplets then mix on the motor vehicle body component to be coated.

In a local mixture, on the other hand, coating agent droplets of a specific base color C, M, Y or K are applied from the coating agent nozzle, which then mix on the vehicle body components to be coated with other coating agent droplets which are applied by another coating agent nozzle not shown here.

FIG. 4A shows a group of coating agent nozzles 16.1-16.5, which are connected together with the output of a color changer 17 and therefore apply the same coating agent in operation.

The color changer 17 is connected on the input side to seven coating agent supply lines, four of the coating agent supply lines supplying the primary colors C, M, Y, K of the CMYK color system, while the other three coating agent supply lines a metallic paint, a mica varnish or a special paint.

The embodiment according to FIG. 4B is largely consistent with that described above and in FIG. 4A illustrated embodiment, so reference is made to avoid repetition of the above description, wherein the same reference numerals are used for corresponding details.

A special feature of this exemplary embodiment consists firstly in that the color changer 17 is connected on the output side to a total of six coating agent nozzles 16.1-16.6, which thus apply the same coating agent.

Another special feature of this embodiment is that the color changer 17 is connected on the input side only with five coating agent supply lines, four of the coating agent leads the primary colors C, M, Y, K of the CMYK color system, whereas the fifth coating agent supply line supplies a special paint.

The embodiment according to FIG. 5 partially in accordance with the embodiment FIG. 4A to avoid repetition, reference is made to the above description, wherein like reference numerals are used for corresponding details.

A special feature of this embodiment is that the color changer 17 is connected on the input side to a color mixer 18, wherein the color mixer 18 is connected on the input side to four coating agent supply lines, which supply the four primary colors C, M, Y, K of the CMYK color system. The color mixer 18 can therefore from the four basic colors C, M, Y, K mix any color and perform the color changer 17.

Furthermore, it can be seen from the drawing that the color changer 17 can optionally supply the coating agent nozzles 16.2, 16.3 and possibly also further coating agent nozzles, which are not shown in the drawing.

A special feature of the embodiment according to FIG. 6 The paint mixer 25 is supplied on the input side with the primary colors C, M, Y, K of the CMYK color system and mixes a desired hue in accordance with the control , which is then applied by the coating agent nozzles 16.1-16.4. On the other hand, the adjacent coating agent nozzle 16.5 is connected via the color changer 17 to three further coating agent supply lines which supply a metallic lacquer, a mica lacquer or a special lacquer.

A special feature of the embodiment according to FIG. 7 is that the individual rows of nozzles 19.1-19.4 are not supplied with different primary colors, but with a mixed-together coating agent, which is mixed together by a color mixer 26 of the primary colors C, M, Y and K.

FIG. 8 shows a further embodiment of a nozzle arrangement in the print heads 8, 9, wherein here four nozzle rows 28.1-28.4 are shown, each having numerous coating agent nozzles 29. All coating agent nozzles 29 and all coating agent series 28.1-28.4 are supplied together by a color changer 30 with the same coating agent.

On the input side, the color changer 30 is connected to three special color supply lines via which three special paints S1, S2, S3 are supplied.

In addition, the color changer 30 is connected on the input side to a color mixer 31, which mixes a desired color tone from the primary colors C, M, Y, K and makes it available to the color changer 30 for selection.

The embodiment according to FIG. 9 partly in agreement with the one described above and in FIG. 8 illustrated embodiment, so reference is made to avoid repetition of the above description, wherein the same reference numerals are used for corresponding details.

A special feature of this embodiment is that all coating agent nozzles 29 are connected in all nozzle rows 28.1-28.4 to a common coating agent supply line 31, via which the same coating agent is supplied.

FIG. 10 shows a scheme for painting a sharp edge 39. It can be seen that the edge 39 is composed of different sized coating agent surfaces 40, 41, 42, wherein the different sized coating agent surfaces 40-42 are produced by correspondingly different sized coating agent nozzles.

When printing a graphic, larger areas of a hue are printed with the large coating agent nozzles, whereas Areas that require a certain edge sharpness, be refined with small coating agent nozzles. This process is particularly useful for two-tone finishes (two-tone finish, eg the threshold area of a body in contrasting color). The illustration shows a border zone that is printed with three different nozzle sizes.

FIG. 11 schematically shows a rotatable printhead 43 with four large coating agent nozzles 44 and numerous smaller coating agent nozzles 45, wherein the larger coating agent nozzles 44 are arranged outside with respect to the axis of rotation of the printhead 43, while the smaller coating agent nozzles 45 are inside with respect to the axis of rotation of the printhead 43.

Further shows FIG. 12 a printhead assembly 46 having a total of four print heads 47-50 which are pivotable relative to each other to allow a better fit to the surface of a curved member 51.

FIG. 13 FIG. 5 shows a pixel 52 which can be printed on a component 53 by means of a printing head using the coating method according to the invention, the pixel 52 being shown individually in the drawing for the sake of simplicity. In practice, however, numerous pixels 52 are applied.

The pixel 52 consists of several layers 54-57, which are arranged one above the other.

The three lower layers 55-57 consist of the primary colors red, green and blue of the RGB color system. Alternatively, however, there is also the possibility that the lower layers consist of the primary colors of another color system, such as the CMYK color system. The superimposed layers 55-57 then produce a specific hue by subtractive color mixing.

The top layer, on the other hand, consists of a semi-transparent metallic lacquer to achieve a metallic effect.

FIG. 14 shows in greatly simplified form a coating device according to the invention with a multi-axis robot 58, which moves a print head 59 along predetermined coating medium paths over a component surface 60, wherein the robot 58 is controlled by a robot controller 61. The robot controller 61 controls the robot 58 in this case in such a way that the print head 59 is guided along the component surface 60 along predetermined coating middle paths, the coating middle webs lying next to one another in a meandering manner.

A special feature here is that an optical sensor 62 is additionally attached to the print head 59, which detects the position and the course of the preceding coating middle web in operation so that the current coating middle web can be aligned exactly on the preceding coating middle web.

FIG. 15 shows in greatly simplified form a variant of a coating device according to the invention with three separate coating agent feeds 63-65, each supplying a component of the coating agent to be applied.

The coating agent feeders 63-65 are connected on the output side to a mixer 66 which mixes the individual components to form a coating agent mixture, which is then mixed a printhead 67 is supplied. The mixture of the various components of the coating agent is thus carried out before application by the print head 67.

FIG. 16 on the other hand shows in simplified form a print head 68, which applies three different components of a coating agent separately from each other on the component surface, wherein the mixture of the individual components takes place only on the component surface.

FIG. 17 shows in schematic form a print head 69 for application of coating agent drops 70 on a component surface 71st

The print head 69 in this case has a coating agent nozzle 72, from which the individual coating agent drops 70 are ejected pneumatically or in any other way.

In addition, the print head 69 has an envelope flow nozzle 73 which annularly surrounds the coating agent nozzle 72 and emits an annular envelope flow surrounding the individual coating agent drops 70.

On the one hand, this serves for atomization or delimitation of the individual coating agent drops 70.

On the other hand, the sheath flow discharged by the sheath current nozzle 73 deflects any overspray in the direction of the component surface 71 and thereby improves the application efficiency.

FIG. 18 also shows in greatly simplified form a printhead 69 according to the invention, which partly coincides with the printhead 69 according to FIG. 27, so that reference is made to the above description to avoid repetition with the same reference numerals being used for corresponding details.

A peculiarity of this embodiment is that the individual coating agent drops 70 are pneumatically ejected from the coating agent nozzle 72, wherein the coating agent drops 70 are pneumatically accelerated, whereby the maximum possible Lackierabstand is increased because the individual coating agent drops 70 due to the pneumatic acceleration correspondingly greater genetic energy to have.

FIG. 19 shows in a highly simplified form a printhead 74 in the application of two adjacent coating paths, wherein the position of the print head 74 is designated in the current Lackierbahn without apostrophe, whereas the position of the print head 74 'is marked in the previous Lackierbahn with an apostrophe.

The printhead 74 has a plurality of coating agent nozzles 75 juxtaposed transversely to the web direction, with the outer coating agent nozzles 75 delivering less coating agent than the inner coating nozzles 75. As a result, the printhead 74 creates a trapezoidal layer thickness distribution 76 on the component surface the trapezoidal layer thickness distribution 76 is then superimposed with the likewise trapezoidal layer thickness distribution 76 'of the preceding coating path, which leads to a constant layer thickness.

FIG. 20 shows in simplified form a coating device according to the invention, in which the components to be coated 77 along a linear conveying path 78 through a paint booth be transported, which is known per se from the prior art and therefore need not be described in detail.

The conveying path 78 is in this case spanned by a portal 79, wherein on the portal numerous print heads 80 are mounted, which are directed to the components 77 on the conveying path 78 and coat them with a coating agent.

FIG. 21 shows an embodiment of a nozzle assembly 37 with five parallel rows of nozzles 38.1-38.5 with relatively large nozzle openings and four nozzle rows 39.1-39.4 with relatively small nozzle openings. Here, the special feature is a large packing density of the individual coating agent nozzles.

The invention is not limited to the preferred embodiments described above. Rather, a variety of variants and modifications is possible.

Claims (22)

1. Coating device for coating motor vehicle body parts with a multi-axis robot (3,4) having a multi-axis robot hand axis on which an application device is mounted applying the coating agent as area having an edge area defined by a coating edge (39),
   characterised in that the application device is a print head (8, 9) which discharges the coating agent from a plurality of coating agent nozzles, and the coating agent nozzle arrangement comprises differently sized coating agent nozzles such that a sharp course of the coating edge (39) is achieved, the smaller coating agent nozzles applying correspondingly small coating agent areas (40, 41) at the coating edge (39) of the edge area.
2. Coating device in accordance with claim 1, characterised in that coating agent nozzles are provided having three different nozzle sizes.
3. Coating device in accordance with claim 1 or 2,
   characterised in that
   the print head (74) includes a plurality of coating agent nozzles (75) which are arranged next to each other in relation to the path direction,
   and the outer coating agent nozzles (75) emit less coating agent than the inner coating agent nozzles (75).
4. Coating device in accordance with any one of the preceding claims, characterised in that the print head (74) applies a coating agent path with a layer thickness distribution (76) transversely to the path direction which is a trapezoidal distribution or a Gaussian normal distribution.
5. Coating device in accordance with any one of the preceding claims, characterised in that the coating agent nozzles are arranged in a row or a plurality of rows.
6. Coating device in accordance with any one of the preceding claims, characterised in that the coating agent nozzles of the print head (8, 9) are jointly connected to a coating agent supply line via which the coating agent to be applied is supplied.
7. Coating device in accordance with any one of the preceding claims, characterised in that the print head (8, 9) exhibits an area coating performance of at least 1 m²/min, 2 m²/min, 3 m²/min, 4 m²/min or 5 m²/min.
8. Coating device in accordance with any one of the preceding claims with a painting cabin, characterised in that during operation the air downdraft speed in the painting cabin (2) is less than 0.3 m/s, 0.2 m/s, 0.1 m/s, 70 cm/s or 50 cm/s.
9. Coating device in accordance with any one of the preceding claims, characterised in that
   the coating agent is fluid paint and contains pigments, metallic flakes or other solid paint components,
   and the coating agent nozzles of the print head (8, 9) are large enough to apply the paint containing the solid paint components.
10. Coating device in accordance with any one of the preceding claims, characterised in that

    a) the print head (8, 9) is arranged in a painting cabin (2) in which the components are coated with the coating agent,

    b) no wash-out (7) is arranged under the painting cabin (2), which in conventional painting installations washes overspray out of the cabin air in the painting cabin (2),

    c) the coating device is not protected against explosion,

    d) an air extractor (10) is provided which extracts the cabin air from the painting cabin (2) downwards and/or through side channels, and /or

    e) an air filter (11) is provided which is arranged upstream of the air extractor (10) and filters the overspray from the cabin air, and the air filter (11) is designed as a filter ceiling which is arranged on the base of the painting cabin (2) so that the cabin air is extracted from the painting cabin (2) downwards through the filter ceiling (11).
11. Coating device in accordance with any one of the preceding claims, characterised in that the joint coating agent supply line is supplied by a colour changer.
12. Coating device in accordance with any one of the preceding claims, characterised in that

    a) the print head (8, 9, 43) is rotatably mounted about an axis of rotation and rotates during coating or between consecutive coating sessions, and/or

    b) the print head (8, 9, 43) has coating agent nozzles of different sizes, and/or

    c) the smaller coating agent nozzles (45) are arranged closer to the axis of rotation of the print head (8, 9, 43) than the larger coating agent nozzles (44).
13. Coating device in accordance with any one of the preceding claims, characterised in that a plurality of application devices are provided which are designed as print heads,
    and/or to coat curved component surfaces several print heads (47-50) are provided which preferably can swivel with regard to each other.
14. Coating device in accordance with any one of the preceding claims, characterised by an electrostatic coating agent charger and/or compressed air support to improve the application efficiency of the print head (8, 9).
15. Coating device in accordance with any one of the preceding claims, characterised by a position detection system for detecting the spatial position of the print head (8, 9) and/or the component surface to be coated.
16. Coating device in accordance with any one of the preceding claims, characterised by
    a sensor (62) which is positioned together with the print head (59) by the robot (58) and which detects the course of a guide path on the component to be coated (60), and
    a robot controller (61), which on the input side is connected to the sensor (62) and on the output side to the robot (58), whereby the robot controller (61) positions the print head (59) as a function of the course of the guide path.
17. Coating device in accordance with claim 16,
    characterised in that
    the sensor (62) is an optical sensor,
    and/or the guide path is a previously applied coating agent path,
    or the guide path contains a coating agent that is only visible when illuminated with UV light or IR light.
18. Coating device in accordance with any one of the preceding claims, characterised in that
    the print head (69) has a sheath flow nozzle (73), the sheath flow nozzle (73) emits a sheath flow of air or another gas, and
    the sheath flow encompasses the coating agent emitted from the coating agent nozzle.
19. Print head of the coating device in accordance with any one of the preceding claims, characterised in that the print head (8, 9) discharges the coating agent from a plurality of coating agent nozzles and the arrangement of the coating agent nozzles is modified with differently sized coating agent nozzles such that a sharp course of a coating edge (39) is achieved.
20. Coating method for coating motor vehicle body parts, the coating agent being applied by a print head (8, 9) which is mounted on the multi-axis robot hand of a multi-axis robot (3, 4) and applies the coating agent from a plurality of coating agent nozzles as area having an edge area defined by a coating edge (39),
    characterised in that the nozzle arrangement comprises differently sized coating agent nozzles with which a sharp course of the coating edge (39) is generated, the smaller coating agent nozzles applying correspondingly small coating agent areas (40, 41) at the coating edge (39) of the edge area.
21. Coating method in accordance with claim 20,
    characterised in that the coating agent nozzles of the print head (8, 9) are jointly connected to a coating agent supply line via which the coating agent to be applied is supplied.
22. Coating method in accordance with claims 20 or 21,
    characterised by the following steps:

    a) detecting of the spatial position of the print head (8, 9) and/or the component surface to be coated,

    b) control and/or regulation of the spatial position of the print head (8, 9) as a function of the detected position.

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