DE102010056263A1 - Apparatus and method for coating an article with a medium - Google Patents

Abstract

A device (10) for coating an object with a medium has an outlet opening (24) from which the medium emerges, which is then atomized into a spray jet with a main direction of movement and a jet profile. The jet profile of the spray jet can be shaped with a pair of stationary jet shaping units (34) which are diametrically opposite with respect to the outlet opening (24) and which direct a shaping fluid onto the spray jet via at least one shaped fluid opening (40, 42). In order to change the angular orientation of the jet profile around the main direction of movement of the spray jet while maintaining the precision required for automated painting, at least one further pair of diametrically opposed jet shaping units (34) is provided in a different angular position with respect to the axis of the outlet opening (24), the jet shaping units thereof can be controlled independently of the beam shaping units (34) of the first pair.

Description

• a) einer Austrittsöffnung, aus der das Medium austritt, das dann zu einem Sprühstrahl mit einer Hauptbewegungsrichtung und einem Strahlprofil zerstäubt wird,
• b) einem Paar von bezüglich der Austrittsöffnung diametral gegenüberliegenden, stationär angeordneten Strahlformeinheiten, die über mindestens eine Formfluidöffnung ein Formfluid auf den Sprühstrahl richten, wodurch das Strahlprofil des Sprühstrahls formbar ist.

The invention relates to a device for coating an article with a medium, with

• a) an outlet opening from which the medium emerges, which is then atomized to a spray jet having a main movement direction and a jet profile,
• b) a pair of jet-forming units arranged diametrically opposite to the outlet opening and directing a shaping fluid onto the spray jet via at least one shaping fluid opening, whereby the jet profile of the spray jet can be shaped.

The invention further relates to a method for coating objects, in which a device of the above type is used.

A beam profile is understood here to mean the profile which the spray jet generates in a cross-sectional area perpendicular to its main direction of movement, wherein the beam profile is set at a distance from the outlet opening which corresponds approximately to the working distance of the device to an object to be coated.

Such devices are used in particular in the automotive industry in the form of spray guns for the automated painting of vehicle bodies or vehicle parts. The spray guns are attached to arms of painting machines or robots, which guide the spray guns on a predetermined pattern of movement on the surfaces of the objects to be painted.

From the market known spray guns of the type mentioned have with respect to the outlet opening of the spray gun on two diametrically opposed beam forming units from the openings compressed air, the so-called mold air, can escape, which is directed on both sides of the spray. As a result, the spray jet can be shaped into a fan-shaped flat jet with a substantially strip-shaped jet profile. Such a flat jet makes it possible to apply the paint layer by layer on a larger surface, such as the roof of a vehicle body, whereby an optimal paint distribution is achieved.

In order to paint different geometries of the objects optimally, is changed in these known spray guns and painting depending on the coating phase by simultaneously turning on and off the diametrically opposed beam forming units between a rotationally symmetrical spray and a fan-shaped flat jet. However, since the beam profile of the flat jet, in contrast to the rotationally symmetrical spray jet has a preferred direction, the angular orientation of the spray gun must be rotated and adjusted for the main direction of movement of the spray with respect to the web direction, for example in the web-shaped painting. In particular, when changing from one side of the workpiece to the other a reorientation of the flat jet is often necessary.

Such a reorientation of the beam profile could in principle be achieved by means of a further joint or rotation axis at the front end of the robot arm, but this would lead to an overall larger and more expensive painting robot. Therefore, so far, the beam profile of a flat jet is brought into a different angular orientation that complicated and extensive Verwindungsbewegungen be performed using the existing joints and axes of rotation of the painting robot.

The disadvantage of this method is that the complicated twisting of the painting robots to reorient the beam profile require time, which is not insignificant reflected on the Gesamtlackierzeit a vehicle body. In addition, the complicated robot movements drills the supply hoses and electrical connections so that any twisting motion eventually has to be followed by an opposite twisting motion to prevent complete twisting of the hoses. Also, the hoses are more stressed by the torsions, so that increased wear occurs and thus increased maintenance is necessary.

The publication DE 692 27 907 T2 shows a hand-operated paint spray gun, in which two diametrically opposed beam forming units are arranged on an air cap. By rotating the air cap relative to a blocking plate arranged behind it, the jet shaping units can be rotated by 90 ° about the outlet opening, which leads to a corresponding reorientation of the beam profile. In an intermediate position of the air cap, the supply to the jet forming units is blocked, creating a rotationally symmetric jet profile.

However, such an approach is less suitable in the automated painting with the help of painting robots, since the beam shaping influencing parts are moved, which can lead to inaccuracies in the beam shaping. However, for optimal painting during a program-controlled painting process, it is crucial that the spray jet emitted always has a precisely defined spray profile. Therefore, spray guns are used for automated painting, the jet-forming units manufactured with high precision have, which are arranged stationary with respect to the gun body and the outlet opening.

It is therefore an object of the invention to provide a device and a method of the type mentioned, in which the angular orientation of the beam profile can be changed by the main direction of movement of the spray while maintaining the necessary precision for automated painting.

This object is achieved, as far as the device is concerned, according to the invention by a device of the type mentioned above, in which at least one further pair of diametrically opposed beamforming units is provided in a different angular position with respect to the axis of the outlet opening, the beamforming units of which can be controlled independently of the beamforming units of the first pair are.

According to the invention, the angular orientation of the beam profile can be changed by the independent control of the at least one further pair of diametrically opposed beam shaping units despite a stationary arrangement of the beam shaping units with respect to the outlet opening or the gun body.

If four jet forming units are used, the two diametrically opposite pairs are preferably crosswise, i. H. arranged offset by 90 °. As a result, for example, an originally rotationally symmetrical spray jet can be formed by pressurizing two opposing jet forming units with molding fluid in a first direction into a flat jet. By switching off the first two beam shaping units and turning on the other two beam shaping units, the rotationally symmetrical spray jet can then be shaped into a flat jet in a second direction, which is perpendicular to the first.

As the coating medium, it is possible to use all substances which wetting or covering a surface, such as various paints of various functions, such as protective lacquers, colored lacquers, wet lacquers or powder lacquers. However, the medium to be applied may also be a liquefied wax, a plastic or an adhesive which has to be applied to an object as a protective layer or functional layer.

As a molding fluid usually compressed air is used. For special applications, however, other fluids such as inert gases, such as nitrogen, are conceivable as a molding fluid.

According to the embodiment according to claim 2 it is provided that a plurality, in particular at least four pairs, of jet forming units is provided.

A plurality of beamforming units allow a small step change in the orientation of the beam profile. In this case, an even number of beamforming units will usually be selected, such as 8, 12, 16 or 24, wherein the beamforming units are arranged in pairs diametrically opposite one another. However, it may also be provided an odd number of beam forming units. Or some beam forming units may be present without a paired arrangement. Preferably, the jet-forming units are arranged on a circular path coaxial with the outlet opening around the outlet opening. Furthermore, if the shaping fluid openings of the individual beam shaping units are configured identically, then the beam shaping units act symmetrically on the spray jet, which simplifies their control.

According to the embodiment according to claim 3 it is provided that the beam forming units, at least in groups, in particular in pairs, are independently controllable.

By controlling in groups can be switched between different beam profiles or angular orientations of a beam profile. In particular, the diametrically opposite pairs with respect to the outlet opening can be controlled independently of the other pairs, so that a flat jet can be rotated by switching between different pairs. However, in order to form a triangular beam profile, for example, the beamforming units can also be interconnected in a corresponding group with 3-symmetry.

After the development according to claim 4 is provided that all beam forming units are individually controlled.

This gives the greatest possible freedom in the choice of the beam profile. For example, a semicircular beam profile can also be formed.

According to the embodiment according to claim 5 it is provided that the jet forming units are assigned controllable shut-off valves for the molding fluid.

By means of shut-off valves, with which the supply of the molding fluid to the jet forming units can be interrupted in groups, in pairs or individually, an at least partially independent control of the jet forming units is possible, so that the jet profile can be changed depending on the state of the shut-off valves.

After the development according to claim 6 it is provided that a distributor element is provided with distribution channels for the molding fluid.

A distributor element allows multiple jet forming units to be connected in groups or pairs to a single shut-off valve so that fewer shut-off valves are necessary to pressurize the jet forming units with the forming fluid. Different distribution channels can be connected on the inlet side with different shut-off valves. Preferably, the distributor element is arranged close to the mold fluid openings, so that only at the end of the entire feed path for the molding fluid does a branch to the individual beam shaping units take place.

After the development according to claim 7 it is provided that a controllable diverter valve is provided with a valve spool for the molding fluid.

A controllable diverter valve has a valve spool with which different paths through the valve can be selected. Thus, each of the other beamforming units or groups of jetforming units can be selectively connected to one or more feed channels of the molding fluid so that switching between different configurations of the exiting molding fluid can be achieved without having to have a shutoff valve for each molding unit or group of beamforming units. This allows existing mold fluid supply systems to remain largely unchanged and to provide switching between different jet forming units by means of the mold fluid diverter valve.

According to the embodiment according to claim 8 it is provided that the valve slide has a distribution channel to the jet forming units, which is selectably connectable with differently arranged inlet and / or outlet channels.

By such a distribution channel on the valve spool can be realized various switching states of the changeover valve. The valve spool may also have a plurality of distribution channels, which are connectable at the same time or alternately with corresponding stationarily arranged inlet and / or outlet channels.

After the development according to claim 9 it is provided that the valve spool is annular and rotatable.

In the device according to the invention, an annular valve spool with distribution channels, which can be connected by rotation of the valve spool selectable with different jet forming units and Formfluidzuführkanälen, particularly advantageous. This allows the integration of the diverter valve in the device and thus a compact and reliable design.

After the development according to claim 10 it is provided that a drive is provided for driving the distributor valve.

Such a drive allows an automated switching of the acted upon with shaping fluid beam forming units. The drive, which can be done pneumatically, piezoelectrically or via an electric motor, for example, can be integrated into the program sequence of the painting robot and be controlled accordingly, for example, if a rotation of the flat jet is necessary. In an annular valve slide an internal toothing can be provided, in which engages an electric motor with a drive pinion.

According to the embodiment according to claim 11, it is provided that a proportional valve is provided for at least one independently controllable beam forming unit.

Via a proportional valve, the amount of the molding fluid delivered to the jet forming unit can be controlled. Thus, for example, in the case of diametrically opposed pairs of beamforming units can be controlled by appropriate throttling, how much the beam profile is to be deformed to a flat jet. Among other things, the spray jet can be acted upon to different degrees by means of proportional valves of different jet forming units with molding fluid. If proportional valves are used, they may be provided in addition to or instead of the shut-off valves.

According to the embodiment according to claim 12, it is provided that a jet forming unit comprises a plurality of shaping fluid openings.

Multiple mold fluid openings on a jet forming unit, which may have a different size or a different angle of attack with respect to the spray jet, allow a precise definition of the total flow generated by the jet forming unit and directed along the spray jet. The forming fluid openings belonging to a jet forming unit are always acted upon together with shaping fluid and direct this from essentially the same direction onto the spray jet.

With regard to the method, the object is achieved in that a Device according to one of the above claims is used.

After the development according to claim 14 it is provided that the device is fixed to a painting robot and the beam profile is changed by switching between different beam forming units, in particular its angular orientation is changed by the main movement direction.

This method has the advantage that the painting robot has to perform fewer movements to rotate the beam profile. Also, the accessibility of certain areas of a body, such as the hinge area, tank pits or air intakes, can be improved. In particular triangular beam profiles may be advantageous in certain wells. The beam profile can therefore be adapted to the surface area to be coated, so that the overspray is significantly reduced.

The invention will be explained in more detail by means of embodiments with reference to the drawings. In these show:

1 an end portion of a painting robot arm with a spray gun according to the invention, which has an air cap with four beam forming units;

2 a perspective view of the air cap according to a first embodiment;

3 an axial section through the air cap of 2 ;

4 a perspective view of the air cap according to a second embodiment;

5 an axial section through the air cap of 4 ;

6 an axial section through the air cap of 4 and a subsequent distributor element;

7 a section through the distributor element of 6 according to the local line VII-VII;

8th a circuit diagram of a mold fluid supply system, via which the jet forming units are acted upon with molding fluid;

9 an axial section through the head portion of the spray gun of the second embodiment, wherein instead of the simple distributor element, a controllable changeover valve is provided;

10a a section through the diverter valve of 9 along the line XX with an annular valve spool in a first position;

10b a section through the diverter valve of 9 corresponding to the line XX with the annular valve spool in a second position.

1 shows a spray gun 10 working on a tool holder 12 a partial painting robot arm shown 14 is attached.

The spray gun 10 includes a gun body 16 , on the outlet side, a replaceable air cap 18 is arranged.

Such an air cap 18 according to a first embodiment is in the 2 and 3 shown.

The disc-shaped air cap 18 , whose exit side front 20 in 2 pointing up and its back 22 in 2 pointing down, facing centrally in the face 20 a framed by a frusto-conical recess outlet 24 on, from which a medium intended for coating can emerge. The outlet opening 24 is this with an axial medium supply channel 26 (please refer 3 ) connected to the back 22 the air cap 18 leads and which is applied with a medium, usually paint, with the example, a vehicle body or parts of such can be coated.

As from the cut in 3 can be seen, is the outlet opening 24 from a radially outwardly inclined bevel 28 surrounded, in the evenly distributed over the circumference ten Zerstäubungsfluidöffnungen 30 are arranged. The atomizing fluid openings 30 are via sputtering fluid channels 32 also on the back 22 the air cap 18 lead, with a sputtering fluid, usually compressed air fed. This may cause the spray gun to operate during operation 10 from the atomizing fluid openings 30 Compressed air escape, due to the sloping bevel 28 on the area in front of the outlet 24 is directed and causes a sputtering of the emerging there medium or at least supported.

Radially further out are at the front 20 the air cap 18 four jet forming units 34 provided, each as an exit side (in the 2 and 3 to the top) protruding horn-like projection 36 are formed. The jet forming units 34 are uniform in the circumferential direction around the outlet opening 24 distributed so that they are arranged crosswise at 90 ° to each other and thus with respect to the outlet opening 24 diametrically opposite in pairs.

Every lead 36 has a radially inwardly facing inclined surface 38 on, which rises obliquely radially outward.

The inclined surface 38 every projection 36 each has two mold fluid openings 40 and 42 on, with the appropriate Formfluidkanälen 44 and 46 are connected. The mold fluid channels 44 . 46 also end on the back 22 the air cap 18 , Due to the inclination of the inclined surfaces 38 show the mold fluid openings 40 . 42 during the operation of the spray gun 10 be fed with a molding fluid, usually compressed air, in the direction of the above the outlet opening 22 formed spray, whereby it is formed.

The 4 and 5 show an air cap 118 according to a second embodiment, characterized by the air cap 18 of the previous embodiment distinguishes that the beam forming units 134 are not formed as projections.

Instead, the mold fluid openings 140 . 142 each beam forming unit 134 directly in the flat front 120 the air cap 118 arranged. Nevertheless, to exiting mold fluid on the spray in front of the outlet opening 124 to straighten, the Formfluidkanäle run 144 . 146 leading to the molding fluid openings 140 . 142 lead, at least just before leaving the front 120 the air cap 118 with respect to the main direction of movement of the spray from radially outward and rearward to radially inward and forward.

As in 6 exemplified for the air cap 118 without protrusions 136 shown, the spray gun has a disc-shaped distributor element 150 for the molding fluid, which is a front side 152 and a back 154 Has. The distributor element 150 is so behind the air cap 118 arranged it with his front 152 right at the back 122 the air cap 118 is applied.

The distributor element 150 itself has an axial passage in the middle 156 on that with the medium supply channel 126 the air cap 118 is aligned and used to supply the medium.

Furthermore, the distributor element 150 at its front 152 coaxial around the passage 156 a circular ring channel 158 up to the air cap 118 pointing is open. The diameter of the ring channel 158 is chosen so that the Zerstäubungsfluidkanäle 132 the air cap 118 aligned with him, so that this from the annular channel 158 can be fed. From the back 154 of the distributor element 150 A feed hole leads here 160 to the ring channel 158 ,

For the distribution of the molding fluid to the individual beam forming units 134 has the distributor element 150 at its front 152 four wells 162 on, corresponding to the four beam forming units 134 are arranged and have such a large diameter that they each with the two Formfluidkanälen 144 and 146 connected to the molding fluid openings 140 . 142 to lead.

The two wells 162 that is a diametrically opposite pair of beamforming units 134 are each assigned via connection channels 164 and 166 connected. For ease of manufacture, the connection channels are 164 . 166 from the front 152 forth open and guided so that they are closed areas of the back 122 the air cap 118 be covered.

Each one of the wells 162 of a couple is about a feed hole 168 with the back 154 of the distributor element 150 connected.

As in 8th for the embodiment of 4 to 7 shown are the feed holes 168 of the distributor element 150 connected to a molding fluid supply system, which in 8th in total with 170 is designated.

The mold fluid delivery system 170 includes a first and a second proportional valve 172 and 173 , which are connected with their input-side connection to a compressed air source, not shown.

On the output side is the first proportional valve 172 with a first shut-off valve 174 and the second proportional valve 173 with a second shut-off valve 176 connected. The first shut-off valve 174 is the output side with the supply hole 168 of the first pair of beamforming units 134 connected. The second shut-off valve 176 whereas, with the supply hole 168 the second, offset by 90 °, couple connected.

The spray gun works as follows:
The over the medium channel 126 supplied medium is at the outlet opening 124 by means of the sputtering fluid, which at the Zerstäubungsfluidöffnungen 130 exits, atomises and forms in front of the outlet 124 a spray from.

As long as the two shut-off valves 174 and 176 are closed, the spray jet can form uninfluenced rotationally symmetric and used for coating.

Is in a special coating phase, for example, for coating a larger surface area, a flat jet with a desired strip-shaped beam profile, so for example, the first shut-off valve 174 be opened to open, so that the molding fluid from the mold fluid openings 140 . 142 at the two diametrically opposed beam forming units 134 of the first pair can escape. The obliquely impinging on the spray from opposite sides of the molding fluid presses this together, so that a flat jet is formed. With the help of the first proportional valve 172 the degree of flattening can be determined. The further the proportional valve 172 opened, the flatter the spray profile.

If a different angular orientation of the flat jet around the main movement direction is required in the course of the painting process, the first shut-off valve becomes 174 closed and the second shut-off valve 176 , which with the second pair of diametrically opposed beam forming units 134 connected, open. Since the two pairs are at 90 ° to each other, the flat jet is "rotated" by 90 °. For example, the orientation of the flat jet can be changed from vertical to horizontal without the robot arm 14 must perform elaborate twisting movements. Via the second proportional valve 173 The degree of flattening can also be adjusted in this orientation, thereby controlling the proportional valves 172 . 173 a variety of beam profile shapes is adjustable.

An advantageous modification of the form fluid supply is in the 9 and 10a , b shown.

Instead of the non-switchable distributor element 150 in connection with individual switching valves 174 and 176 used, which are opened or closed accordingly, can be a controllable diverter valve 278 be used.

The diverter valve 278 includes a disk-shaped valve seat 280 that works like the distributor element 150 a central passage 256 as well as a ring channel 258 for feeding the outlet opening 224 or the Zerstäubungsfluidöffnungen 230 having.

Unlike the distributor element 150 has the valve seat 280 however, from its front 252 her an annular circumferential countersinking 282 in which a complementary annular valve slide 284 rotatable.

The valve spool 284 shows the pits 168 of the distributor element 150 corresponding through holes 286 which in turn are configured such that they each have the molding fluid channels 244 and 246 a mold unit 234 can provide. The valve spool 284 however, has only two such through-holes 286 on, which are arranged diametrically opposite and over only one connecting channel 288 are connected, which is arcuate along the valve spool 284 extends.

The valve spool 284 also has internal teeth at its inner edge 290 on, in which the output pinion 292 an electric motor 294 intervenes. By driving the electric motor so the valve spool 284 along the surrounding subsidence 282 to be turned around.

Regarding the central passage 256 offset by 90 ° are a first supply hole 296 and a second feed hole 298 at the valve seat 280 provided the lowering 282 with the back 254 of the valve seat 280 connect. There are the feed holes 296 . 298 connected to shut-off valves or proportional valves of a molding fluid supply system.

In a first position is one of the two through holes 286 of the valve spool 284 with the first feed hole 296 connected, so supplied molding fluid to the corresponding diametrically opposed beam forming units 234 can be directed.

Will the valve spool 284 rotated by 90 °, so is one of the two through-hole 286 with the second feed hole 298 and the other jetforming unit pair is supplied with molding fluid.

In an intermediate position, the valve spool 284 completely suppress the form fluid supply, so that the spray jet generated by the spray gun has a rotationally symmetrical beam profile. If the two pairs of beamforming units 234 should only be used alternately, therefore, can be dispensed with separate shut-off valves.

In a particularly preferred, not shown modification, a plurality of jet forming units may be provided, which rotate around the outlet opening and can be acted upon by corresponding shut-off, proportional and / or Umstellventile at least in pairs independently with form of fluid. For example, the angular orientation of the beam profile can be changed in small increments around the main movement direction. Through the use of proportional valves different jet forming units can be acted upon with different amounts of molding fluid, which allows various configurations of the beam profile.

In a further modification, instead of several atomizing fluid openings 30 to the outlet opening 24 be provided for the medium and an annular circumferential sputtering fluid opening.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 69227907 T2 [0009]

Claims (14)

Contraption ( 10 ) for coating an article with a medium, having a) an outlet opening ( 24 ; 124 ; 224 ) from which the medium exits, which is then atomized into a spray jet having a main direction of movement and a jet profile, b) a pair of with respect to the outlet opening (FIG. 24 ; 124 ; 224 ) diametrically opposed, stationarily arranged beam shaping units ( 34 ; 134 ; 234 ), which via at least one mold fluid opening ( 40 . 42 ; 140 . 142 ; 240 . 242 ) direct a shaping fluid onto the spray jet, whereby the spray profile of the spray jet can be shaped, characterized in that c) at least one further pair of diametrically opposed jet forming units ( 34 ; 134 ; 234 ) in a different angular position with respect to the axis of the outlet opening ( 24 ; 124 ; 224 ) is provided, the beam shaping units ( 34 ; 134 ; 234 ) independently of the beamforming units ( 34 ; 134 ; 234 ) of the first pair are controllable. Apparatus according to claim 1, characterized in that a plurality, in particular at least four pairs, of beam forming units ( 34 ; 134 ; 234 ) is provided. Apparatus according to claim 1 or 2, characterized in that the beam shaping units ( 34 ; 134 ; 234 ) at least in groups, in particular in pairs, are independently controllable. Device according to one of the preceding claims, characterized in that all beam forming units ( 34 ) are individually controllable. Device according to one of the preceding claims, characterized in that the beam shaping units ( 134 ) controllable shut-off valves ( 174 . 176 ) assigned. Device according to one of the preceding claims, characterized in that a distributor element ( 150 ) with distribution channels ( 164 . 166 ) is provided for the molding fluid. Device according to one of the preceding claims, characterized in that a controllable diverter valve ( 278 ) for the molding fluid with a valve spool ( 284 ) is provided. Apparatus according to claim 7, characterized in that the valve slide ( 284 ) a distribution channel ( 286 . 288 ) to the beam forming units ( 234 ), which is selectable with differently arranged inlet and / or outlet channels ( 296 . 298 . 244 . 246 ) is connectable. Apparatus according to claim 7 or 8, characterized in that the valve slide ( 284 ) is annular and rotatable. Device according to one of claims 7 to 9, characterized in that a drive ( 290 . 292 . 294 ) for controlling the changeover valve ( 278 ) is provided. Device according to one of the preceding claims, characterized in that for at least one independently controllable beam forming unit ( 134 ) a proportional valve ( 172 . 173 ) is provided for the molding fluid. Device according to one of the preceding claims, characterized in that a beam shaping unit ( 34 ; 134 ; 234 ) a plurality of mold fluid openings ( 40 . 42 ; 140 . 142 ; 240 . 242 ). Method for coating objects, in which a device ( 10 ) is used according to one of the preceding claims. Method according to claim 13, characterized in that the device ( 10 ) on a painting robot ( 14 ) and the beam profile by switching between different beam shaping units ( 34 ) is changed, in particular whose angular orientation is changed by the main movement direction.

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