EP3235399B1 - Method and device for selectively applying a cover varnish - Google Patents

Description

The invention relates to a method according to the preamble of claim 1 for electroplating, in particular chrome plating, a, in particular three-dimensional, plastic molded part, preferably a plastic injection molded part, a covering lacquer being applied to the component and then the component being metallized.

Furthermore, the invention relates to a system according to claim 8, comprising a metallization device and a device for selectively applying a covering lacquer to an application surface of a component to be galvanized, in particular three-dimensional, designed as a molded plastic part. The system is designed and designed to carry out the method according to the invention. Plastic parts, especially plastic injection molded parts, mostly made of ABS (acrylonitrile-butadiene-styrene copolymer) or ABS-PC plastics are provided with a mostly multi-layer electroplating, i.e. electrochemically coated, for a wide variety of applications, especially for the automotive industry. An upper electroplating metal layer is usually formed by a chrome layer. For many purposes, it is necessary to omit certain areas of the plastic part from the metallization, ie not to metallize these areas. In order to achieve this, it has become known to electrically isolate the cut-out area from the surface area that is electrically contacted, to be coated or metallized, with the aid of a so-called masking varnish (selective paint or stop varnish), which usually paints around the cut-out area in a ring shape, that is to say closed becomes. In an alternative procedure, particularly in the case of small-area recess areas the entire area to be left out is protected with the masking varnish. It is known to apply the masking varnish by hand. The problem with this, however, is that the masking lacquer trace is often not applied reliably, ie varies with regard to the application width and / or layer thickness, which can lead to failures due to electrical breakdowns or flashovers in the subsequent electroplating process.

The EP 1 302 564 A2 describes a method for metallizing metal surfaces. It is known from the publication to apply a large area of a photoresist coating by dipping, spray painting, mechanical brushing or dipping.

The DE 44 38 799 A1 deals with mask technology in connection with the production of automatic cards or printed circuit boards. The WO 2015/041831 A1 describes a method for applying lubricant to pipe ends for torque reduction.

On the basis of the aforementioned prior art, the object of the invention is to provide an alternative, reliable process for the selective application of a covering lacquer layer to a component to be electrochemically metallized in a later process step. Furthermore, the object is to provide a system for the process-reliable selective application of masking lacquer in advance of, in particular electrochemical, metallization of a component, which is suitable and intended for carrying out the method according to the invention.

This object is achieved with regard to the method with the features of claim 1.

With regard to the system, the object is achieved with the features of claim 8.

Advantageous developments of the invention are specified in the subclaims. All combinations of at least two of the features disclosed in the description, the claims and / or the figures fall within the scope of the invention. To avoid repetition, features disclosed according to the device should also be considered disclosed according to the method and be claimable. Likewise, features disclosed in accordance with the method should also be considered as disclosed in accordance with the device and should be capable of being claimed.

The invention leads to a method for, preferably galvanic (electrochemical) metallization, in particular chrome plating, of a plastic component, the, in particular electrochemical, further preferably at least one, preferably uppermost, chromium layer comprising metallization or the metallization process, a cover lacquer application method according to the invention which is explained below is connected upstream.

The invention is based on the idea of applying the covering lacquer to the component selectively, ie not covering the entire surface, to prevent the subsequent metallization of the partial area covered by the covering lacquer (application surface) and / or a recess area surrounding the covering lacquer, ie the application surface provided with covering lacquer not (more) manually but automatically, using a brush, whereby according to the invention automatic, ie by means of at least one, in particular electrical (Pneumatic or hydraulic) drive-driven relative movement means are provided, with the aid of which a relative movement is automatically generated between the brush and the component during the application of the covering lacquer to the component, so that the application area, that is to say, with the brush in contact with the component to cover the partial surface of the component to be provided with the masking lacquer. It is essential that the brush is supplied, in particular continuously, from a masking material reservoir via a masking agent supply line while the masking lacquer is being applied. In contrast to a manual application, in the automated application according to the invention it is therefore not necessary to interrupt the application process for immersing the brush in a supply of masking lacquer. The automated generation of a relative movement of a brush and the component supplied with masking varnish, in particular continuously, can ensure process-reliable application of the masking varnish to areas of the component which is preferably made of plastic, in particular ABS, ABS-PC, PA 6.6, or PP . In addition, the method according to the invention and the device according to the invention enable the automated, process-reliable application of masking lacquer to three-dimensional components or surfaces that extend along three perpendicular spatial axes of a Cartesian spatial coordinate system. For this purpose, the relative movement means only have to be designed such that they allow a relative movement along all three spatial axes. The automated application of the topcoat by means of a brush supplied with topcoat, a multi-bristle arrangement has surprisingly proven to be particularly effective and reproducible in terms of the coating or application result.

With regard to the specific design of the relative movement means or the specific execution of the relative movement, there are three different design variants. According to a first embodiment variant, both the brush and the component are actively (simultaneously or in succession) adjusted by the relative movement means during the application process, as a result of which, in particular, very complex component geometries are comparatively easily possible with masking lacquer, in particular along a predetermined application track or line, in particular circumferentially is. Alternatively, it is feasible to arrange the brush in a fixed position and to adjust only the component with the aid of suitable relative movement means relative to the fixed brush, in particular along three spatial axes. The third alternative is particularly preferred - according to this, the component is arranged in a stationary manner, in particular is held in a workpiece carrier, while the brush is actively adjusted relative to the fixed component, in particular along a predetermined and / or predeterminable (parameterizable by the user) relative movement path. As will be explained later, it is particularly advantageous for the last-mentioned variant if the movement means comprise a robot arm which can be pivoted, in particular about at least one joint, preferably about several joints, and which carries the brush. It is particularly advantageous if the robot arm is designed as a collaborative robot arm, which enables an employee to work without blocking and / or other security measures, in particular for loading a workpiece carrier directly next to the robot arm, especially in its working area or range allow. The variant with an actively adjustable brush relative to a fixed component, in particular by means of a robot arm, also has the advantage that several components are arranged in a workpiece carrier around the robot arm and these are processed one after the other by the robot arm or cover varnish on the latter can be applied, so that components that have already been processed or that have been selectively coated or coated with masking lacquer can be exchanged either automatically or with components that are still to be provided with masking lacquer.

As mentioned, it is provided according to the invention that the relative movement means, in particular the robot arm, are designed or controlled such that they execute the relative movement in such a way that the brush is related to the component (by actively adjusting the brush and / or the component) along a predetermined and / or predeterminable trajectory is guided and remains in contact with the component. The trajectory coordinates or the course can either be predefined or what is preferred can be predefined, i.e. can be varied, in particular can be parameterized, very particularly preferably via a corresponding input mask or via a corresponding control file, which is or is created, for example, on the basis of CAD data of the component.

A particularly preferred embodiment variant of the method is one in which the volume of masking lacquer supplied to the brush is varied or can be varied during application, in particular in order to adapt the application behavior or application to a relative speed between the brush and the component, in particular to a brush travel speed and / or to a component geometry. The covering volume flow is preferably controlled and / or regulated in such a way that the layer thickness and / or an application track width increases during the covering lacquer application; especially the paint trail, despite changing relative speed and / or application area changed. In other words, the covering volume flow is controlled in such a way that a layer thickness is specified and / or application track width is maintained, in particular in such a way that a layer thickness and / or application track width remains constant.

In a further development of the invention, it is advantageously provided that the relative movement of the brush takes place in a pulling direction, that is, such that a longitudinal axis of the brush with a relative movement direction in which the brush is relative to the component, in particular by actively adjusting the brush by means of the relative movement means is inclined or includes an angle of less than 90 °, in particular between 70 ° and 88 °, even more preferably between 75 ° and 88 °, very particularly preferably between 80 ° and 85 °, with the relative movement direction (movement vector). The direction of relative movement changes during the application of the resist, whereby the brush inclination, i.e. the angle between the longitudinal axis of the brush, along which the bristles of the brush extend and the direction of relative movement is tracked in order to maintain the aforementioned angle of inclination to the direction of relative movement. It is preferred if the longitudinal axis of the brush is oriented perpendicular to an axis which is arranged at a right angle in the contact area of the brush with the component, ie on the component surface to the direction of relative movement.

Overall, the above-mentioned inclined position or pulling movement of the brush relative to or in the direction of relative movement produces an optimized, non-running brush or masking paint application image.

The invention also leads to a system which is preferably designed and intended to carry out a method previously described in detail. The system comprises a metallization device for the galvanic metallization of a, preferably three-dimensional Plastic molded part (component), in particular a plastic injection molded part and a device for applying masking lacquer to the component before metallizing. It is essential that the device comprises a brush for applying the covering varnish to the application surface and a covering varnish supply line, with which the brush can be supplied with covering varnish from a covering varnish reservoir during application. Furthermore, the device according to the invention comprises automatic relative movement means, ie driven with at least one drive and connected to control means in a signal-conducting manner, for generating a relative movement between the brush and the application surface of the component. It is very particularly preferred if the brush is moved relative to a fixed component, in particular along a predefined and / or predeterminable movement path in order to generate a defined application lacquer trace. It is possible and preferred to use a robot arm, in particular a collaborative one. Alternatively, it is possible to actively move both the component and the brush relative to each other or only the component relative to the fixed brush. For the preferred case of providing a brush, in particular one that can be adjusted by means of a robot arm, it is preferred if a plurality of workpiece receptacles are arranged around the relative movement means, which in particular are moved in succession by the robot arm or the brush to produce a respective covering lacquer application.

It has turned out to be particularly advantageous if the control means can be used to control volume flow setting means with which the covering volume flow supplied to the brush can be varied during the application, in particular as a function of a relative speed between the brush and the component and / or a component geometry known to the control means. It is particularly expedient if the volume flow setting means have a proportional valve, in particular in the Cover varnish supply line, the opening cross-section being varied depending on at least one parameter, for example the relative speed between the brush and the component or the component geometry for setting the volume flow. It is particularly preferred if the masking varnish pressure applied to the proportional valve is constant, at least within predefined limits, or is kept within predefined limits, which is possible, for example, with a feed pump or can preferably be achieved by the reservoir for masking varnish being preferably constant or fluctuating delivery gas pressure, in particular air pressure, is supplied. If a delivery pump is provided instead of the static pressure delivery previously explained, it is possible to control the delivery pump to adjust the volume flow. It is also conceivable to assign conveying pressure setting means to the cover reservoir in order to vary the conveying pressure (gas pressure) as a function of the relative speed and / or component geometry.

It is particularly expedient if the brush is detachably attached to a holder, in particular a bayonet connection or a Luerlok connection, in particular known from medical technology. This holder is preferably formed by the relative movement means, in particular a robot arm. The exchange can be done for cleaning and / or replacement purposes of the brush. It is also possible in this way to use brushes with different geometries for different applications with the same relative adjustment movement means.

As mentioned at the beginning, the brush is a multi-bristle arrangement. It preferably comprises a large number of bristles comprehensive brush bristles of different lengths and / or thicknesses and / or of different materials.

It has turned out to be particularly expedient if an outlet opening for covering lacquer, which is connected to the supply line in a manner that covers the covering lacquer, is set back in relation to a front brush end (contact end to the component), in particular a brush tip. The outlet opening is preferably located in an area within the bristles, in particular in a bristle center and / or behind the bristles, and opens out, for example, in a distributor space for masking lacquer arranged behind the bristles.

In order to realize the brush inclination mentioned in advance, i.e. the angle between the longitudinal axis, in particular the longitudinal central axis, the brush and the relative movement direction that changed during the covering lacquer application, it is preferred if the relative movement means track the brush or the brush inclination accordingly, so that the inclination angle is the same or at least in the preferred angular range remains, at least less than 90 °, in order to realize a continuous pulling movement of the brush.

As already mentioned, it is particularly preferred if the relative movement means of the brush and / or the component are designed or adjusted along three perpendicular spatial axes of a 3D-Katesic coordinate system. For this purpose, it is preferred to provide a more than three-axis, in particular five- or even more preferably six-axis, robot arm which, in addition to a translatory adjustment movement of the brush and / or the component along three spatial axes arranged at right angles to one another, the rotation or pivoting of the brush by at least one of the spatial axis, preferably around at least two of the Space axes, very particularly preferably around three of the space axes. The relative adjustment movement means are preferably designed such that not only the aforementioned angle of inclination, that is to say the angle between the longitudinal central axis of the brush and the relative movement direction, is kept in the desired angular range, in particular at the desired angular dimension, but also an angle between the longitudinal axis, in particular the longitudinal central axis of the brush and an axis that meets the direction of movement in the contact area of the brush with the component, in particular surface axis.

As mentioned, it is preferred if the relative movement means track the inclination angle of the brush or of its longitudinal axis or adapt it to the changing relative movement direction. In the simplest case, this can be realized or programmed by moving the movement means, in particular a robot arm, in a so-called teach mode (learning mode) along a movement path to be specified along the component, and setting or respectively setting or tilting the brush at a plurality of points to be stored is specified manually. Alternatively, it is conceivable to automatically calculate the inclination on the basis of CAD data and to control the relative movement means accordingly. A regulated tracking is also fundamentally conceivable, it being necessary to determine the respective angular position of the brush, for example using sensor means, such as a camera.

An embodiment of the device or of the method implemented thereby is very particularly preferred, in which the device has suction means for suctioning off emissions resulting from the coating application, in particular solvent vapors, with which the corresponding emissions can be extracted or extracted in order to increase the occupational safety for operators.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawings.

Fig. 1:

eine bevorzugte Ausführungsform einer nach dem Konzept der Erfindung ausgebildeten Vorrichtung zum selektiven Auftragen eines Abdecklacks, wobei die an sich bekannte Metallisierungseinrichtung des erfindungsgemäßen Systems nicht gezeigt ist,

Fig. 2:

ein Detail der Vorrichtung gemäß Fig. 1, welches den Pinsel mit Dosierventil und abschnittweise einer Versorgungsleitung zeigt, wobei die Einheit an einem Roboterarm festlegbar ist,

Fig. 3:

einen als Druckbehälter ausgebildeten Vorratsbehälter für Abdecklack,

Fig. 4:

eine exemplarische Darstellung eines bei einem erfindungsgemäßen Verfahren und bei einer erfindungsgemäßen Vorrichtung zum Einsatz kommenden, automatisiert verstellbaren (Auftrags-) Pinsels für Abdecklack, wobei im Rahmen des Verfahrens das Bauteil nach Aufbringen des Abdecklacks elektronisch (galvanisch) metallisiert wird, und

Fig. 5

eine schematische Darstellung des Pinsels beim Abdecklackauftragvorgang, wobei der Pinsel bzw. dessen Längsmittelachse zu einer Relativbewegungsrichtung, in der der Pinsel relativ zu dem mit Abdecklack zu lackierenden Bauteil bewegt ist, geneigt ist.

These show in:

Fig. 1:

1 shows a preferred embodiment of a device for the selective application of a covering varnish designed according to the concept of the invention, the known metallization device of the system according to the invention not being shown,

Fig. 2:

a detail of the device according to Fig. 1 which shows the brush with dosing valve and sections of a supply line, the unit being attachable to a robot arm,

Fig. 3:

a reservoir for masking lacquer designed as a pressure vessel,

Fig. 4:

an exemplary representation of an automatically adjustable (application) brush for masking lacquer used in a method according to the invention and in a device according to the invention, the component being electronically (galvanically) metallized after application of the masking lacquer, and

Fig. 5

is a schematic representation of the brush during the masking process, the brush or its Longitudinal central axis is inclined to a relative movement direction in which the brush is moved relative to the component to be coated with a resist.

In the figures, the same elements with the same function are identified with the same reference symbols.

In Fig. 1 A device 1 for the selective application of masking lacquer on, in particular electrochemically, components to be metallized, in particular made of plastic, such as ABS, ABS-PC, PA 6.6, PEI, or LCP, is shown. The device 1 comprises relative movement means 2 in the form of a collaborative robot arm which carries a brush 3 at the end, as is shown, for example, in FIG Fig. 4 is shown in detail. The robot arm can be automatically adjusted around several swivel joints by means of appropriate drives, in order to thus traverse software trajectories by means of the brush while the brush is in contact with the component. Various workpiece carriers 4 are located around the relative movement means 2, each for receiving a component to be provided with a resist, which is not shown for reasons of clarity. The components can be processed one after the other or provided with masking lacquer and then exchanged manually or automatically.

Control means 5 are assigned to the relative movement means 2 in order to carry out the relative movement in accordance with the specification and, as will be explained later, to vary a volume of masking lacquer during the application.

During the application, the brush 3 is supplied with masking lacquer via a masking lacquer supply line 6 which connects the masking lacquer to a masking lacquer reservoir 7 designed as a pressure container is. A metering valve 8, which can be controlled via the control means 5 and is designed as a proportional valve, is provided for varying the volume of masking lacquer.

The reference number 9 denotes an exhaust air line for removing any solvent vapors from the covering lacquer.

In Fig. 2 is part of the device according to Fig. 1 shown. An attachment 10 can be seen for fixing to the robot arm. The brush 3 is held at the end of the attachment 10 and is continuously supplied with masking lacquer via the masking lacquer reservoir 7 shown in sections. In the attachment 10 there is also the metering valve 8, which can alternatively also be arranged in the region of a connection element 11, which can be fixed via clamps 12 to an arm section of the robot arm of the relative adjustment means 2.

Fig. 3 shows the top coat reservoir 7, which is connected to the brush 3 via the top coat supply line 6 in a paint-conducting manner. The covering lacquer reservoir 7 is supplied with a substantially constant delivery pressure via a compressed gas line, in particular a compressed air line, under manometer control. Instead of such gas pressure delivery, a delivery pump, for example with a screw conveyor, can also be used to generate a delivery pressure. Such a feed pump can be combined with a metering valve designed as described and / or can itself be controlled to vary the volume flow, for example speed-controlled, stroke-controlled, etc.

Fig. 4 shows a possible embodiment of a brush 3 designed according to the concept of the invention. This includes a plurality of elongated bristles 13 which are fixed in a holding section 14. In In an area centered on the radial extent within the bristles 13 there is an outlet opening 15 for masking lacquer. This is supplied with masking lacquer via a supply duct 16 forming part of the supply line. It can be seen that the outlet opening 15 is set back in relation to a front end 18 of the bristles 13 or of the brush 3. The brush 3 includes fixing means 17 on the side facing away from the bristles 13, here in the form of a Luerlok connection for releasable fixing to the relative adjusting means 2.

In Fig. 5 a situation during operation of the device according to the invention is shown. The brush 3 can be seen with a longitudinal axis L (here, for example, the longitudinal central axis). This is not exactly vertical on a component 20 to be coated with masking lacquer 19 (which will later be metallized, in particular galvanized later in the process) - rather, the longitudinal axis L of the brush 3 is inclined to a relative movement direction R in which the brush 3, here pulling, is adjusted or pulled along the component surface or component 20 by relative adjustment movement means. This relative adjustment movement direction changes during the application process in which the brush 3 is moved along a movement path. The angle α between the longitudinal axis L and the relative movement direction R is tracked or kept in the value range from 80 to 85 ° in the exemplary embodiment shown during the covering lacquer application. An angle β is preferably maintained at the same time between an axis A (surface axis) oriented in the contact area of the brush 3 with the component 20 perpendicular to the direction of relative movement R.

Reference numerals

1

contraption

2nd

Relative means of movement

3rd

brush

4th

Workpiece carrier

5

Tax funds

6

Masking paint supply line

7

Masking reservoir

8th

Dosing valve (proportional valve)

9

Exhaust duct

10th

Essay

11

Connecting element

12th

Clamps

13

Bristles

14

Holding section

15

Outlet opening

16

Supply channel

17th

fixer

18th

front end of the brush

19th

Masking varnish

20

Component

L

Longitudinal axis

R

Relative direction of movement

A

axis

Claims (15)

1. A method for the electro-metallization, in particular chromium plating, of a component realized as a plastic molded part, a covering varnish being applied to the component and the component being metallized afterwards,
   the covering varnish being applied to the application surface by means of a brush (3),
   characterized in that
   a relative movement between the brush (3) and the application surface of the component is realized by means of automatic relative movement means (2) in order to apply the covering varnish and that a covering varnish reservoir (7) supplies the brush (3) via a covering varnish supply line (6) during the application, in particular in a continuous manner, and that the relative movement means (2) realize the relative movement in such a manner that the brush (3) and/or the component is/are guided along a defined and/or definable movement path.
2. The method according to claim 1,
   characterized in that,
   in order to realize the relative movement, the brush (3) and the component are actively moved, or the component is actively moved relative to the stationary brush (3) or the brush (3) is actively moved relative to the stationary component, the brush (3) thus being guided on the application surface.
3. The method according to any one of the preceding claims, characterized in that
   the relative movement means (2) displace the brush (3) and/or the component along three perpendicular axes of a 3D Cartesian coordinate system.
4. The method according to any one of the preceding claims, characterized in that
   the relative movement means (2) comprise an, in particular collaborating, robotic arm.
5. The method according to any one of the preceding claims, characterized in that
   a covering varnish volume flow which is supplied to the brush (3) is varied during the application.
6. The method according to claim 5,
   characterized in that
   the covering varnish volume flow is controlled and/or regulated in such a manner that, irrespective of a changing brush travel speed and/or a geometry of the component which changes along the application surface, the layer thickness and/or the application track width of the covering varnish application remains constant.
7. The method according to any one of the preceding claims, characterized in that,
   in order to apply the covering varnish (19), the brush (3) is displaced relative to the component (20) in a relative movement direction (R) which changes during the application and the brush is and/or remains inclined relative to the relative movement direction (R) in such a manner that a longitudinal axis of the brush and the relative movement direction (R) confine an angle (a) of less than 90°.
8. A system for performing a method according to any one of claims 1 to 7, comprising a metallization device for the electro-metallization, preferably chromium plating, of an, in particular three-dimensional, component realized as a plastic molded part and a device for the selective application of a covering varnish to an application surface of the component to be electro-metallized, comprising a brush (3) for applying the covering varnish to the application surface, a covering varnish supply line (6) for supplying covering varnish from a covering varnish reservoir (7) to the brush (3) during the application and automatic relative movement means (2) connected to control means (5) in a signal-conducting manner for realizing a relative movement between the brush (3) and the application surface of the component, and that the control means are realized so as to control the relative movement means (2) in such a manner that said relative movement means (2) realize the relative movement in such a manner that the brush (3) and/or the component is/are guided along a defined and/or definable movement path, preferably each along a 3D movement path.
9. The system according to claim 8,
   characterized in that
   the relative movement means (2) are realized as a handling facility which guides the brush (3) along a defined and/or definable, in particular three-dimensional, movement path.
10. The system according to claim 8 or 9,
    characterized in that
    volume flow adjustment means which are connected to the control means (5) in a signal-conducting manner are provided in order to vary the covering varnish volume flow during the relative movement.
11. The system according to any one of claims 8 to 10, characterized in that
    the brush (3) is fixed to a support in a detachable manner.
12. The system according to any one of claims 8 to 11, characterized in that
    the brush (3) comprises a plurality of bristles (13), preferably of different lengths and/or thicknesses and/or materials.
13. The system according to any one of claims 8 to 12, characterized in that
    an outlet opening (15) for covering varnish is set back in relation to a front end of the brush.
14. The system according to any one of claims 8 to 13, characterized in that
    the relative movement means are realized so as to align the brush (3) in such a manner that, in order to apply the covering varnish (19), said brush (3) is displaced relative to the component in a changing relative movement direction (R) during the application and is and/or remains inclined relative to the relative movement direction (R) in such a manner that a longitudinal axis (L) of the brush, in particular a longitudinal central axis (L) of the brush and the relative movement direction (R) confine an angle of less than 90°.
15. The system according to any one of claims 8 to 14, characterized in that
    the device has extraction means for extracting emissions resulting from the covering varnish application.

Images