Painting method and painting facility for producing a decorative coating

Abstract

A method for painting a component, in particular for painting a motor vehicle body component, with a decorative layer is provided. The decorative layer may be a decorative strip, a graphic element, a contrast surface or a pattern. The method includes applying a base coat layer, applying a decorative layer, which is within a decorative region with a limited surface area, to the component, and drying a limited drying region of the component, which drying region comprises at least part of the decorative region.

Claims

1. A method for painting a component and providing a decorative layer, the component having an exterior, the method comprising: applying a base coat layer onto the exterior of the component; applying a paint layer onto the exterior of the component; drying the exterior of the component before application of the decorative layer, applying the decorative layer onto the component in an overspray free manner without the use of a mask, the decorative layer defining a limited area decorative region smaller than the exterior region of the component; drying a limited portion of the component using a robot having a drying unit at a drying region, the drying region at least partially encompassing the decorative layer, the drying region being smaller than the exterior region of the component, the drying region covering merely a peripheral edge of the decorative region, the drying region after drying the limited portion having a lower residual moisture level than a remainder of the decorative region; and applying a clear coat layer onto the paint layer and the decorative layer, including applying the clear coat layer to the drying region having the lower residual moisture level than the remainder of the decorative region and applying the clear coat layer to the remainder of the decorative region; wherein the drying region covering the peripheral edge of the decorative region prevents running of the decorative region at the peripheral edge.

2. The method according to claim 1, wherein the drying region and the decorative region coincide areally.

3. The method according to claim 1, wherein the decorative region is larger than the drying region.

4. The method according to claim 1, wherein the paint layer is dried in an intermediate drying process to a first residual moisture level.

5. The method according to claim 1, wherein the drying of the limited portion of the component at the drying region includes, irradiating the component by electron bombardment.

6. The method according to claim 1, wherein the component is dried with a drying unit, and the drying unit is convex.

7. The method according to claim 6, wherein the drying unit is moved together with an applicator along a painting path over the component.

8. The method according to claim 7, wherein, while moving together on the painting path, the drying unit dries the component and the applicator applies the decorative layer.

9. The method according to claim 7, wherein the drying unit dries the component in a first movement over the painting path and the applicator applies the decorative layer in a second movement over the painting path.

10. The method according to claim 7, wherein the applicator applies the decorative layer in a first movement over the painting path and the drying unit dries the component in a second movement over the painting path.

11. The method according to claim 1 wherein the decorative layer is dried with a diffuser.

12. The method according to claim 1 wherein the drying of the limited portion is through radiation and a shield masks the exterior surface to only allow radiation to dry the decorative region.

13. The method according to claim 1 wherein the drying is directed through a diffuser.

14. The method according to claim 1 wherein the base coat is intermediate dried with air drying have a temperature between 60 Celsius and 80 Celsius.

15. A method for painting a component and providing a decorative layer, the component having an exterior, the method comprising: applying a base coat layer onto the exterior of the component; applying a paint layer onto the exterior of the component; drying in a first drying operation only a drying region of the exterior of the component with a robot prior to an application of the decorative layer, the drying region defining a limited area smaller than the exterior of the component, the first drying operation using a robot, the first drying operation leaving a first residual moisture level; applying the decorative layer onto the component in an overspray free manner without the use of a mask at the drying region, the decorative layer defining a limited area decorative region smaller than the exterior region of the component, the decorative layer being applied by the robot; drying a limited portion of the component in a second drying operation, the limited portion covering merely a peripheral edge of the decorative region, the second drying operation leaving a second residual moisture level at the peripheral edge of the decorative region that is lower the first residual moisture level and lower than a moisture level at a remainder of the decorative region; and applying a clear coat layer onto the paint layer, the peripheral edge of the decorative region of the decorative layer having the second residual moisture level, and the remainder of the decorative region having the moisture level.

16. The method according to claim 15 wherein the base coat is dried.

17. The method according to claim 15, wherein the drying region and the decorative region coincide areally.

18. The method according to claim 15, wherein the decorative region is larger than the drying region.

Description

DRAWINGS

(1) The present disclosure is described below in greater detail with reference to the drawings, in which:

(2) FIGS. 1-7 each show an implementation of a painting method according to the present disclosure in the form of a flow diagram, respectively,

(3) FIGS. 8A-8E each show an implementation of a drying unit according to the present disclosure for drying the component, respectively,

(4) FIGS. 9A-9E each show a different cross-sectional view through a coated component with the drying region and the decorative region, respectively,

(5) FIG. 10 shows a schematic representation of a drying unit according to the present disclosure for radiative drying with a shield for masking the drying region,

(6) FIG. 11 shows a schematic representation to illustrate the spacing of the drying unit,

(7) FIGS. 12A-12E each show a schematic representation of a different implementation of a drying unit, respectively,

(8) FIG. 13 shows a schematic representation of a drying unit according to the present disclosure,

(9) FIGS. 14A-14E each show a different graphical representation of the reduction of the residual moisture level with the drying, respectively,

(10) FIGS. 15A-15D each show a different schematic representation of an for air drying unit, respectively,

(11) FIG. 16 shows a schematic representation of a robot with a drying unit and an applicator, and

(12) FIG. 17 shows a schematic representation of a robot for applying the decorative layer and a further robot for drying the component surface.

DESCRIPTION

(13) FIGS. 1-7 show different implementations of a painting method for decorative coating, according to the principles of the present disclosure, each in the form of a flow diagram. These exemplary implementations differ essentially in the sequence of their steps. Therefore, first the individual steps of these implementations according to FIGS. 1-7 will be described.

(14) In a step BC (BC: base coat), a base coat layer is applied to the component surface of the component to be coated (e.g. motor vehicle bodywork component). In some implementations, the base coat layer is single-layered and, in other implementations, there are two base coat layers (BC1+BC2). The base coat layer may be wet paint or powder paint. The base coat layer is, in some implementations, applied in a conventional manner, e.g., with a rotary atomiser or an air atomiser which is guided by a multi-axis painting robot.

(15) In a step ZTR (intermediate drying), the entire component surface is then intermediate-dried. For example, this intermediate drying can take place with air drying, for example, with an air temperature of +60 C. to +80 C. It should be mentioned that, in each case, in the context of the intermediate drying, the entire component surface is dried, for which purpose, the component to be dried can be introduced, for example, into a drying chamber, as is known from the prior art.

(16) In a step DC (DC: decor coat), a decorative layer (e.g. decorative stripe, graphic, contrast surface or pattern) is applied to the component, wherein the decorative layer is areally limited to a particular decorative region and does not extend over the entire component surface.

(17) In a step PTR (partial drying), a limited area (partial) drying takes place within a drying region which at least partially encompasses the decorative layer. This limited area drying can take place, for example, with air drying or by irradiation of the component surface.

(18) In a step CC (CC: clear coat), a clear coat layer is then applied. The clear coat layer may be single-layered or multi-layered. The clear coat may be a single-component clear coat or a two-component clear coat.

(19) In the field of automobile serial-production painting, components are typically dried or baked with a suitable apparatus following the final painting stepincluding the application of a clear coat layer is described, provided air-drying lacquers (e.g. two-component lacquers) are not used.

(20) Finally, some implementations also comprise a further step TR (drying) in which the entire component surface is completely dried. This drying takes place, for example, by air drying with a relatively high air temperature of +130 C. to +150 C. During the drying in the step TR, the air temperature is thus substantially higher than during the intermediate drying in the step ZTR.

(21) The implementations shown in FIGS. 1-7 differ in the sequence of the above-described steps, as follows:

(22) FIG. 1: BC.fwdarw.ZTR.fwdarw.DC.fwdarw.PTR.fwdarw.CC.

(23) FIG. 2: BC.fwdarw.PTR.fwdarw.DC.fwdarw.ZTR.fwdarw.CC.

(24) FIG. 3: BC.fwdarw.PTR.fwdarw.DC.fwdarw.PTR.fwdarw.CC.

(25) FIG. 4: BC.fwdarw.PTR.fwdarw.DC.fwdarw.CC.

(26) FIG. 5: BC.fwdarw.ZTR.fwdarw.CC.fwdarw.PTR.fwdarw.DC.fwdarw.TR.

(27) FIG. 6: BC.fwdarw.ZTR.fwdarw.CC.fwdarw.TR.fwdarw.DC.fwdarw.PTR.

(28) FIG. 7: BC.fwdarw.CC.fwdarw.ZTR.fwdarw.DC.fwdarw.PT.

(29) FIGS. 8A-8E show different implementations of a drying unit 1 for drying a coating on a component 2, wherein the drying unit 1 can emit, for example, an air stream onto the component surface of the component 2.

(30) The individual figures herein differ in the shaping of the component and the correspondingly adapted shaping of the drying unit. The drying unit 1, on one side, and the component 2, on the other, therefore have complementary matching forms.

(31) Thus, the component 2 in FIG. 8A is planar, so that the drying unit 1 is also essentially planar.

(32) In the implementation of the present disclosure according to FIG. 8B, the component 2 is convex, so that the drying unit 1 is formed correspondingly concave.

(33) In the exemplary implementation according to FIG. 8C, however, the component 2 is concave, so that the drying unit 1 is formed correspondingly convex.

(34) In the implementation according to FIG. 8D, the component 2 has a component edge projecting upwardly in the drawing, so that the drying unit 1 is formed correspondingly adapted.

(35) Finally, the drying unit 1 in the exemplary implementation according to FIG. 8E has a projecting edge, which extends perpendicularly to the drawing plane.

(36) FIGS. 9A-9E show different cross-sectional views of a component 2 with a base coat layer 3 and a decorative layer 4 applied onto the base coat layer 3 within a decorative region. The drawings also show schematically a drying region 5, wherein the base coat layer 3 is dried in a limited area within the drying region 5.

(37) In the exemplary implementation according to FIG. 9A, the decorative region of the decorative layer 4 and the drying region 5 match one another exactly coincidingly.

(38) In the exemplary implementation according to FIG. 9B, the drying region 5 is larger than the decorative region of the decorative layer 4 and fully encompasses the decorative region.

(39) The exemplary implementation according to FIG. 9C, however, shows that the drying region 5 covers only part of the decorative region of the decorative layer 5, specifically the peripheral edge of the decorative layer 4.

(40) The exemplary implementation according to FIG. 9D partially corresponds to the exemplary implementation according to FIG. 9A. However, the drying depth of the drying region 5 is herein less than in the exemplary implementation according to FIG. 9A.

(41) The exemplary implementation according to FIG. 9E is also partially in accordance with the exemplary implementation according to FIG. 9A. However, the drying depth of the drying region 5 is herein larger and extends through the base coat layer 3 as far as the component 2.

(42) FIG. 10 shows a schematic representation of a drying unit 1 according to the present disclosure, which dries the decorative layer 4 by irradiation, for example with infrared radiation.

(43) Herein, a shield 6 is also shown which masks the component surface and only allows through the radiation serving for drying purposes in the region of the decorative layer 4, so that the drying unit 1 dries the component surface in a limited area within the decorative region.

(44) FIG. 11 shows a further implementation including a spacing a between the drying unit 1 and the component surface.

(45) FIGS. 12A to 12E show different types of drying units 1.

(46) In the exemplary implementation according to FIG. 12A, the drying unit 1 exclusively emits electromagnetic radiation (e.g. infrared radiation) for drying the component surface.

(47) In the exemplary implementation according to FIG. 12B, the drying unit 1 exclusively emits an air stream for drying the component surface.

(48) The exemplary implementation according to FIG. 12C combines a drying with an air stream and by electromagnetic radiation (e.g. infrared radiation).

(49) In the exemplary implementation according to FIG. 12D, the drying unit 1 additionally has a negative pressure bell 7 which is guided over the component surface in order to dry the component surface with negative pressure. Furthermore, the drying unit 1 herein also emits electromagnetic radiation (e.g. infrared radiation) to the component surface. This exemplary implementation also combines a negative pressure drying with a radiative drying.

(50) Finally, FIG. 12E shows a pure negative pressure drying.

(51) FIG. 13 shows a schematic plan view of a drying unit 1 according to the present disclosure for limited area drying of a component 2, wherein the drying unit 1 is transported in the arrow direction (in other cases, the component 2 could also be transported). The drying unit 1 is herein situated over the component 2 to be dried, so that a dried region 8 of restricted width is dried behind the drying unit 1.

(52) FIGS. 14A-14E show different patterns of a residual moisture level F in the base coat layer 3 along the width b in FIG. 13. The values b=b1 and b=b2 herein mark the edges of the drying region 8 in FIG. 13. The value F1 signifies the residual moisture level which is achieved with the limited area drying according to the present disclosure. The value F2 however characterises the residual moisture level which is achieved with a conventional component drying, for example, in a drying chamber.

(53) FIG. 14A shows a implementation of the present disclosure wherein the residual moisture level F1 achieved in the limited area drying is substantially higher than the residual moisture level F2 achieved in the conventional unlimited area drying. The residual moisture level F1 is typically too high for faultless application of a clear coat layer, although the residual moisture level F1 is sufficiently lower for the application of the decorative layer.

(54) FIG. 14B shows a implementation of the present disclosure wherein the residual moisture level F1 achieved with the limited area drying is equal to the residual moisture level F2 achieved in the conventional unlimited area drying.

(55) FIGS. 14C and 14D show modifications of the FIGS. 14A and 14B with a less sharp-edged transition of the residual moisture level F at the edges b=b1 and b=b2.

(56) Finally, FIG. 14E shows a implementation in which the edge sharpness of the residual moisture level can be varied.

(57) FIGS. 15A-15D show different implementations of drying units 1 for air drying.

(58) In the exemplary implementation according to FIG. 15A, the drying unit 1 emits an air stream 9 with a diffuser 10. The diffuser 10 therefore provides that the air stream 9 is diffuse.

(59) In the exemplary implementation according to FIG. 15B, however, the air stream 9 is emitted via numerous air nozzles 11, wherein the air nozzles 11 are oriented parallel to one another and perpendicularly to the surface of the component 2.

(60) In the exemplary implementation according to FIG. 15C, however, the air nozzles 11 are oriented slightly obliquely to the surface of the component 2.

(61) Finally, the air nozzles 11 in the exemplary implementation according to FIG. 15D are differently oriented. At the edge of the drying region, the air nozzles 11 are oriented obliquely inwardly. In the centre of the drying region, however, the air nozzles are oriented perpendicularly to the component surface.

(62) FIG. 16 shows a schematic representation of a painting robot 12 according to the present disclosure with a plurality of robot arms and a highly manoeuvrable robot hand axis, wherein the painting robot 12 carries both an applicator 13, e.g. of the aforementioned type, and also a drying unit 1. The applicator 13 serves herein to apply the decorative layer and can also be used to apply the base coat layer if no other applicator, for example, a rotary atomiser is to be used. The drying unit 1, by contrast, serves for limited area drying of the base coat layer or of the decorative layer.

(63) FIG. 17 shows a modification wherein the painting robot 12 carries only the applicator 13, whereas the drying unit 1 is guided by an additional multi-axis robot 14.

(64) The present disclosure is not restricted to the above-described exemplary implementations. Rather, it should be understood that this disclosure is exemplary in nature, i.e. that additional variants and modifications are possible which also make use of the teachings of the present disclosure.