EP1502658B1 - Spraying device comprising a colour changer for coating series of work pieces - Google Patents

Abstract

The spraying device for coating material for series-wise coating of workpieces which are mounted on a robot or another multi-axis manipulating machine, has at least one spray head and a colour change valve assembly (3) for the selective connecting of the spray head to lines feeding coating material of different colour. A dosing pump (24) for dosing of the coating material is located between the colour change valve assembly and spray head. The dosing pump is a valve-less plunger pump, the plunger of which during each travel movement is rotated around its axis extending in the direction of travel.

Description

The invention relates to a mounted on the hand axis of a robot or other multi-axis manipulator machine or mountable spray device according to the preamble of claim 1, for example a possibly electrostatic atomizer for coating material for serial coating of vehicle bodies or other workpieces. Such a spray device is known from US 605 0 498 ,

In the currently used coating systems, the robots or other programmatically movable machines, if necessary exchangeably mounted atomizers, are connected to the required color change and metering systems of the system by external hose lines. The color changers usually consist of a number of modular valve units corresponding to the selectable colors, which are joined together to form a block with a common, generally straight collection channel and which can each be connected to a ring line for the relevant color ( EP 0 979 964 ). Color changers of this type are also known, which, for space reduction, comprise a spiral groove arranged at right angles to the longitudinal axis of the color change block instead of the usual straight collecting channel ( DE 43 39 301 ), which is less aerodynamic. Such color changers basically allow a quick change between the available colors during the painting operation. Although it is known that they should be arranged as close as possible to the ink application device, the color change valve arrangements were previously in practice always outside of the atomizer. For color dosing volumetrisch working Zahnraddosierpumpen or Kolbendosiereinrichtungen (dosing) are used, which in modern systems gemolchten color lines upstream or downstream ( DE 100 33 987 . DE 101 57 966 . DE 101 57 938 etc.). Instead, the dosage is also known with ink quantity control loops, which consist essentially of an electronic universal controller as a control element, serving as an actuator color pressure regulator and a flow measuring device for actual value detection and serving as a shut-off main needle valve upstream of the usual atomizer (Dürr / Behr Technical Handbook 02 / 1994 "Farbmengenregelung"; DE 101 42 355 ).

It is already known, for example, to incorporate dosing pumps or piston dosing devices designed as gear pump into the atomizer ( DE 101 15 463 ; DE 101 36 720 ; EP 0 693 319 ).

Because of principle disadvantages of relatively long hose connections between the external color change valve arrangements and the atomizer, such as color or time losses or cleaning problems during color change, attempts have also been made to install color change systems in the atomizer, for example with several hollow needle valves permanently assigned to one color ( WO 97/24189 ) or with a plurality of pivotable about a common axis containers which are docked in one position to the spray head and in another position to terminals of an external color change valve arrangement ( EP 0 792 695 ). These systems are relatively bulky and hardly usable for small atomizers, such as those required for coating, for example, interiors or other narrow workpiece areas. Also known are atomizers with exchangeably mounted ink cartridges, which are emptied, for example, by a metered liquid drive located on or in the painting robot outside the atomizer ( EP 0 967 016 ). Such systems have the principal Disadvantage of the loss of time caused by the cartridge change in the color change.

In the DE 102 12 601 A coating system has also been proposed, whose color changer formed in the usual way from color valves can be located in the atomizer. However, the nebulizer is intended to include a metering valve forming the main needle valve of the nebulizer as a controlled flow rate effluent of the coating material which replaces a metering pump or other volumetric doser.

At the US 6050498 known spraying device of the type mentioned is an atomizer containing a gear metering pump and an arrangement of several connected to color lines for different colors color valves. The outputs of the paint valves and a purge valve are connected via respective output lines and check valves to a plenum at the pump inlet, with the color channels at the plenum being grouped around the purge channel to reduce the space within the pump.

Out EP 1 000 667 A2 Furthermore, a painting robot is known, whose atomizer is supplied by an accommodated in the robot arm arrangement of a conventional color changer and the color changer downstream metering pump.

In general, in the conventional coating machines with nebulizers of the type considered here considerable disadvantages such as color change losses caused by the components, relatively long color change times, high Andrückverluste when changing color, in the case of Farbmengenregelung low reaction times compared to a metering pump, high installation and maintenance and / or other problems due to the spatially separated arrangement of the color changing and metering devices.

The invention has for its object to avoid the disadvantages of the known systems and to provide a spray device of the type considered, which allows the lowest possible color change losses and at the same time shorter color change times. Preferably, this should be achieved with a small footprint.

This object is solved by the features of the claims.

The invention has due to the short line connection between the color change valve assembly and the spray inside of the spray device forming atomizer the essential advantage of extremely low Farbund time losses in a color change and at the same time allows a very favorable rinsing arrangement, which may be sufficient, the small between color changer and Rinse paint tube nozzle of the atomizer remaining paint residue through the nozzle as in the usual Kurzspülvorgang. For the same reasons, there are slight color losses and defined conditions when pressing the paint to the paint tube. The number of required components of the system is reduced to a minimum, which can be dispensed with otherwise usual function valves such as scavenging blocks. By using long-proven components, simple construction and highest reliability result. It is also advantageous that essentially the entire application technique can be laid in the atomizer and no application components have to be arranged more in the robot or the other application machine.

In addition, special advantages arise when, in a further development of the invention, suitable metering and / or color changing devices with a particularly small footprint are selected especially for installation in atomizers.

Preferably, this is used as a metering pump in the DE 102 13 270 ( EP 1 348 487 ) described valveless piston pump whose piston is rotated at each stroke about its axis extending in the stroke direction, and which is characterized by many significant advantages. These advantages include, among other things, the very low dead volume of the pump with the result correspondingly low color and detergent losses during color change, the fast and effective purging of the pump head with the result of high productivity and process reliability when coating workpieces and the high dosing accuracy (<0.2%) without pulsation and dynamic problems. In addition to these properties, however, the low weight and the small size of the pump are particularly important, so that it also fits into small atomizers, as they are especially desirable for painting robots for coating narrow and difficult to access workpiece areas including interiors and with good dynamic properties. Further, because of its low torque requirement, this pump can handle small and light drives while, on the other hand, allowing for high delivery pressure, which may be required, for example, for some high viscosity coating materials. In addition, the pump has the advantage of simple and less maintenance-intensive design with little moving parts, in particular only one easily producible with minimal tolerance piston in the flow space. When dispensing with these advantages, the invention can also be realized with known per se other volumetric dosing pumps, for example with a small constructed as possible gear pump.

The spray device according to the invention may be, for example, an electrostatic, external and / or internal charging of the coating material or in special cases also working without charging rotary atomizer, as are customary, for example, for the exterior painting of vehicle bodies, but the invention is not limited thereto. For example, the above-mentioned valveless piston metering pump could be arranged particularly advantageously, inter alia with regard to the required material pressure, in an air-assisted airless atomiser directly in front of the atomizer nozzle. The airless atomizing effect is known to be based on the pressure of the coating material to be sprayed, for example the seam sealing material for vehicle bodies.

• die der Oberfläche des Ventilsitzes gegenüberliegende Dichtfläche der Ventilnadel vorzugsweise einschließlich der Stirnfläche der Nadelspitze und/oder die Oberfläche des Ventilsitzes besteht aus einem elastomeren Werkstoff;
• die Feder hat eine degressive Kennlinie;
• der Kolben hat an der von dem Druckmedium beaufschlagten Oberfläche einen nicht kreisrunden, beispielsweise flachen, rechteckigen oder ovalen Querschnitt;
• das Druckmedium wird von einer Druckquelle mit einem Druck von mehr als 10 Bar, vorzugsweise mindestens 20 Bar zugeführt;
• die Antriebseinrichtung zur Beaufschlagung des Kolbens mit dem Druckmedium enthält mindestens zwei längs der Kolbenbewegungsachse hintereinander angeordnete, jeweils von dem Druckmedium beaufschlagte Kolbenflächen;
• die Antriebseinrichtung enthält einen Kraftwandler zur Verstärkung der Kraft des Druckmediums; und/oder
• die Antriebseinrichtung, der das Druckmedium zugeführt wird, befindet sich außerhalb der Ventileinheit und ist mit dieser durch ein vorzugsweise flexibles mechanisches Antriebselement verbunden.

As a color change valve arrangement is preferably in EP 1 502 659 A1 (corresponding DE 103 34 410.1 ) used in which a plurality of pin or needle valves in star design to be distributed around a straight central collecting channel or, in other words, at least some of the valve units can be arranged side by side with parallel needle levels. The central collecting channel can be arranged parallel to and expediently coaxially with the central longitudinal axis of the atomizer, in the case of a rotary atomizer, ie the axis of rotation. The valves preferably have a piston connected to the valve needle and acted on by a pressure medium for driving thereof, and a device formed in particular by a spring which exerts a force directed counter to the pressure of the pressure medium on the valve needle. In addition to the space-saving star construction in the longitudinal direction of the collecting channel, at least one or more of the following features may be expedient for further miniaturization of the color changer:

• the surface of the valve seat opposite sealing surface of the valve needle, preferably including the end face of the needle tip and / or the surface of the valve seat is made of an elastomeric material;
• the spring has a degressive characteristic;
• the piston has a non-circular, for example flat, rectangular or oval cross-section on the surface acted upon by the pressure medium;
• the pressure medium is supplied from a pressure source with a pressure of more than 10 bar, preferably at least 20 bar;
• the drive device for acting on the piston with the pressure medium contains at least two piston surfaces arranged one behind the other along the piston movement axis and in each case acted on by the pressure medium;
• the drive means includes a force transducer for amplifying the force of the pressure medium; and or
• the drive device, which is supplied with the pressure medium, is located outside the valve unit and is connected thereto by a preferably flexible mechanical drive element.

Realization possibilities of these features are in the already mentioned EP 1 502 659 A1 ( DE 103 34 410.1 ).

If the choice between many shades should be possible, so that a color changer would be too large for all these shades within the atomizer and / or correspondingly many hose lines can no longer be laid by the wrist of the manipulator machine, there is the possibility of the color changer in the atomizer to restrict to a few, especially often required colors (high-runner) and provide for the other colors only at least one connected to an additional external color changing arrangement valve unit.

At least for rarely needed shades (low-runner) can also be provided two alternately operating in A / B operation valve units. Within the scope of the invention, however, it is also possible to provide only two valve units as a color change valve arrangement within the atomizer, for example after that in the WO 97/00731 can be arranged and operated described A / B principle. The ink supply lines of the color change valve arrangement can be suitably gemolcht in a conventional manner. In particular, when using the pigging technique, it may also be appropriate to arrange two operated according to the A / B principle color changer next to or behind each other in the atomizer.

To reduce the space requirement of the color changer and its usually pneumatic control lines, there is also the possibility in the from the EP 1 205 256 known manner as valves of the color change valve assembly provided by a solenoid valve or a different type of electric valve pilot operated pneumatic valves, which are connected by an included in the valve assembly electrical connection arrangement with an electronic control system or connectable. In this case, in the leading into the central collection channel of the color changer ink or detergent paths each pneumatic valves are opened and closed by compressed air or another compressed gas from a leading through the color changer to all valves common compressed gas line, and within the color changer is in each case a solenoid valve switched into the compressed gas path of the pneumatic valve. The color changer may provide a data bus for digital control data coupled to the solenoid valves via an electronic circuit. It thus accounts for the previously required numerous Steuerluftschläuche the color changer.

Problems with respect to the implementation of the connection lines of the color changer by the hand axis of the manipulator machine can by the way in the EP 1 285 733 described rotational decoupling can be solved. In this solution is an inner part of the atomizer on which the color changer and his Are mounted line arrangement, rotatably mounted for decoupling from the rotational movements of the wrist relative to the atomizer side flange.

Fig. 1

die schematische Darstellung eines Zerstäubers mit einem Farbwechsler und einer Dosierpumpe;

Fig. 2

eine abgewandelte Ausführungsform des Zerstäubers, der hier am Handgelenk eines Lackierroboters montiert ist;

Fig. 3

einen Fig. 2 entsprechenden, aber abkuppelbar montierten Zerstäuber;

Fig. 4

eine bevorzugte Dosierpumpe; und

Fig. 5

eine bevorzugte Bauform des Farbwechslers.

Embodiments for explaining the invention are shown in the drawing. Show it

Fig. 1

the schematic representation of an atomizer with a color changer and a metering pump;

Fig. 2

a modified embodiment of the atomizer, which is mounted here on the wrist of a painting robot;

Fig. 3

one Fig. 2 corresponding, but detachable mounted atomizer;

Fig. 4

a preferred metering pump; and

Fig. 5

a preferred design of the color changer.

The in Fig. 1 schematically illustrated rotary atomizer 1 contains the spray head 2 forming, for example, in a known manner driven by an air turbine rotating bell, a color change valve arrangement designated 3, hereinafter referred to as color changer and arranged between the color changer 3 and the spray head 2 metering pump 4, the spray head the to be sprayed coating material via a controlled valve assembly 5, which contains, for example, the usual main needle valve. The color changer 3 consists essentially of a number of color valve units F1, F2 ... Fn and possibly one or more Spülventileinheiten, the input side to associated color supply lines L1, L2 and Ln for each a different hue are connected and open into a central straight, common to all valve units collecting channel SK. The collecting channel can be arranged coaxially with the axis of rotation of the atomizer 1 and is connected at its output to the metering pump 4. The arrangement of the modular and formed from needle valves valve units F1, F2, etc. on the collecting channel SK, for example, from the EP 0 979 964 correspond to known construction, the paint supply can have return lines in the manner of a loop for constant color circulation, but does not have to have. The collecting channel SK can be flushed in a likewise known manner. To drive the metering pump 4, for example, one of a located outside of the atomizer 1 motor driven flexible shaft 6 may be provided.

Fig. 2 also schematically shows a rotary atomizer 21 extending from the Fig. 1 differs in that its built-metering pump 24 is reversible, so it can promote in the direction back to the color changer 3. The valve assembly 25 of the atomizer may include a valve 26 for detergent, for example, to rinse the Sammelkanäls the color changer 3.

According to Fig. 2 For example, the atomizer may be mounted on the wrist 27 of a painting robot 20 in which the arm 28 carrying the wrist may be the motor M which drives the metering pump 24, for example via the flexible shaft 6.

According to Fig. 3 can an atomizer 21 ', the rest of the embodiment according to Fig. 1 or Fig. 2 may also be removably and interchangeably arranged on the wrist 27. In this case, there is a coupling arrangement 32 on the mounting flange 30 of the atomizer and on the mounting flange 31 of the wrist known type, which may include in particular also quick-change couplings for connected to the color changer 3 hose and other lines including required in the case of electrically pilot operated pneumatic valves electrical control lines.

The atomizer 21 'may be manually or preferably automatically decoupled from the manipulator machine. Automatic atomizer change systems are known per se, for example from the EP 1 245 296 ,

As a metering pump 4 and 24 of the embodiments according to Fig. 1 to Fig. 3 can for the reasons explained in the beginning expedient in Fig. 4 schematically shown valveless piston pump 40 may be used. Like in the DE 102 13 270 is described in more detail, it consists in the main of a displaceable in a cylinder bore 42 along its axis cylindrical piston 43 and a direction indicated by the arrow 44 at the drive motor which moves the piston and at the same time rotates according to the arrow 45. Coaxially opposite bores, which serve as outlet opening 41 and inlet opening 48, lead into the cylinder bore 42. According to the known working principle of this valveless piston pump rotates once per reciprocating motion of the piston 43 once around its own axis. When retracting the piston, the flat part 46 opens the inlet opening 48 at the front end of the piston. As a result, the colored lacquer to be delivered and dispensed is sucked in and the pumping chamber 49 filled. When the piston continues to rotate upon complete filling of the pumping chamber, the inlet port 48 is closed by the piston 43, and with the opening of the outlet port 41, the discharge stroke begins.

If the color changer 3 connected to a paint supply with too much fluctuating form and none for compensation small pressure peaks sufficient dynamic control is provided, for example, a separate color pressure regulator can be provided for each color. Instead, a control loop can also be used in the DE 101 42 355 be described type, whose switched to the color printing line color pressure regulator consists of a pneumatically or electrically driven needle valve, or in which, according to a development instead of the color changer downstream separate color pressure regulator, the color control valves of the color changer are each formed as an actuator, for example in the form of a needle valve.

Another embodiment of the embodiments according to Fig. 1 to 3 is to provide as a drive of the valve needle of the aforementioned main needle valve of the atomizer a proportional solenoid for very short reaction times, as also in the DE 101 42 355 is described.

As a color changer 3 of the embodiments according to Fig. 1 to 3 can for the reasons explained in the beginning expedient in Fig. 5 shown color changer are used, which also in the mentioned EP 150 2 659 A1 (corresponding DE 103 34 410.1 ) is described. It is accordingly a color changer miniaturized for the purposes of this example in the longitudinal direction of the common collecting channel 101 common to all valve units 101, which is composed of a number of modules 102 successively arranged along the collecting channel, each of which comprises four valve units distributed in a star shape at uniform angular intervals around the collecting channel 103 and 103 'included, the needle axes are in the illustrated example in a common plane perpendicular to the collecting channel 101. If the valve units are to open in a conventional manner with a different angle of 90 ° of their needle axes in the collecting channel 101, are at least the centers of the valve seats of the four valves in a common plane transverse to the collecting channel.

To further save space, the valve units of adjacent sections 102 of the color changer are shown offset from one another in each case such that the valve units 103 of the one plane lie in the circumferential direction of the collecting channel 101 in each case in the middle between the adjacent valve units 103 'of the other plane.

In the Fig. 5 shown arrangement of four arranged in a star pin valves in each level of the modular terminal block of the color changer is in many cases an optimum in particular with regard to color change losses, which among other things also depend on the required diameter of the collecting channel. If, nevertheless, an even flatter design is preferred, a larger number of valves can also be distributed in a plane around the collecting channel, for example six or eight valve units. Not only, but especially in this case unwanted color change losses can be avoided by other measures such as by reducing the collecting channel cross-section through a central inner body (see. DE 102 12 601 ).

As in the mentioned EP 150 2 659 A1 is described, the color changer can be connected via a quick-change coupling arrangement to its connecting lines including the supply and control lines.

The basis of Fig. 5 explained possibility of shortening the required length of the common collecting channel by the angular offset arrangement of the valve units 103 and 103 'is not on the example described in each Level is limited to a plurality of valve units distributed around the collecting channel, but can be generalized to reduce the space required transversely to the collecting channel to the arrangement of only two valve units or even only one valve unit at each level. For example, in the latter case, along the collecting channel, a single row of valve units may be arranged, in which adjacent valve units are offset from one another by an appropriately selected angle, for example by approximately 45 °, along the collecting channel, such that two interleaved groups each extend longitudinally the collecting channel aligned valve units are formed. On the one hand, the offset angle should be as small as possible in order to save space in the direction transverse to the collecting channel and transversely to the two valve groups, but on the other hand must be chosen such that the distance of the needle axes measured in the longitudinal direction of the collecting channel is smaller than that also in this longitudinal direction measured maximum diameter of the valve units, although a space saving in the longitudinal direction of the collecting channel to be achieved. The mutual distance of the needle longitudinal axes of the adjacent valve units should therefore be smaller than the minimum distance they would have to have the same outer dimensions of the valve units, if the adjacent valve units would be aligned with each other without angular displacement as in known color changer.

Claims (11)

1. An atomiser for coating material for serially coating workpieces, which is mounted or adapted to be mounted to a robot or another multi-axis manipulator and comprises at least one spray head (2)
   as well as a colour change valve arrangement (3) for selectively connecting the spray head (2) to lines (L1, L2, Ln) supplying coating material of different colours,
   with a pump (4, 24) being disposed in the spraying device (1, 21) between the colour change valve arrangement (3) and the spray head (2) which meters the coating material, characterized in that the colour change valve arrangement (3) consists of a number of modular pin or needle valve units (F1, F2, Fn) which open into a central straight collecting channel (SK) and are distributed around the collecting channel in adjacent planes along the collecting channel (SK).
2. The atomiser according to claim 1, characterized in that the metering pump (4, 24) is a valveless piston pump whose piston (43) is rotated at each piston stroke around its axis extending in the direction of the stroke.
3. The atomiser according to claim 1 or 2, characterized in that the colour change valve arrangement (3) contains valve units (103) for the selectable colours, each of which having

   - an outlet aperture for the coating material flowing in the direction of the application device, which forms a valve seat;

   - a valve needle displaceably mounted in the valve unit (103), said valve needle having a sealing surface abutting the valve seat when the valve is closed;

   - at least one piston connected to the valve needle, which is pressurised with a pressure medium to drive the valve needle;

   - and a device constituted, in particular, by a spring, which exerts a force on the valve needle that is directed opposite to the pressure of the pressure medium,

   wherein a drive unit is provided to pressurize the piston with the pressure medium;
   wherein the valves open into a common collecting channel (101);
   and wherein at least two valve units (103) having valve needle planes which are parallel to each other are arranged side by side along the collecting channel (101).
4. The atomiser according to claim 3, characterized in that there are provided means for increasing the force exerted by the drive unit on the piston and/or for reducing the necessary force directed in the opposite direction, which the drive unit has to overcome.
5. The atomiser according to claim 4, characterized in that the colour change valve arrangement (3) presents at least one or more of the following features:

   a) the sealing surface of the valve needle opposite the surface of the valve seat, preferably including the end face of the needlepoint and/or the surface of the valve seat, consists of an elastomeric material;

   b) the spring has a degressive characteristic line;

   c) the piston has a non-circular cross-section, for example a flat, rectangular or oval cross-section, on the surface pressurized by the pressure medium;

   d) the pressure medium is fed from a pressure source at a pressure of more than 10 bar, preferably at least 20 bar;

   e) the drive unit contains at least two piston surfaces which are disposed behind one another along the axis of movement of the piston and are each pressurised by the pressure medium;

   f) the drive unit contains an energy converter to increase the force of the pressure medium;

   g) the drive unit to which the pressure medium is supplied is located outside the valve unit (103) and is connected thereto by a preferably flexible mechanical drive element.
6. The atomiser according to any one of the preceding claims, characterized in that at least two valve units (103, 103') of the colour change valve arrangement (3), whose outlet apertures lie in a plane running transverse to the longitudinal axis of their common collecting channel (101) are disposed around the longitudinal axis of the collecting channel.
7. The atomiser according to any one of the preceding claims, characterized in that at least two valve units (103, 103') adjacent in the longitudinal direction of the collecting channel (101) are arranged offset around the collecting channel (101) at an angular distance of their needle axes of less than 90°, and the distance of the needle axes measured in the longitudinal direction of the collecting channel (101) is smaller than the maximum diameter of the valve units (103, 103') also measured in this longitudinal direction.
8. The atomiser according to claim 7, characterized in that at least two valve units (103), whose outlet apertures lie in a common first plane (102) running transverse to the longitudinal axis of the collecting channel (101) are arranged around the longitudinal axis of the collecting channel (101), and that at least two additional valve units (103'), whose outlet apertures lie in a second plane parallel to the first plane, are arranged around the longitudinal axis of the collecting channel in such a manner that the valve units (103) of the one plane lie in the circumferential direction of the collecting channel between the valve units (103') of the other plane.
9. The atomiser according to any one of claims 6 to 8, characterized in that at least three valve units (103, 103') in each case are disposed at equal angular distances around the longitudinal axis of the collecting channel (101).
10. The atomiser according to any one of the preceding claims, characterized in that the colour change valve arrangement (3) has a pressure line common to all valve units (103) from which the pressure medium can be fed to the valve units (103) and that each valve unit (103) has an electrically controlled valve interposed between its drive unit and the common pressure line.
11. The atomiser according to any one of the preceding claims, characterized in that the colour change valve arrangement (3) is provided with a quick-release coupling arrangement at least for the connecting lines of the valve units (103).

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