Installation and method for curtain-coating panel-shaped components

Abstract

The present invention relates to a device 10 and a method for curtain-coating of panel-shaped components 60 as well as components which have been manufactured by such a method. The device comprises a device 40 for generating a liquid curtain 42 of coating material, an input transport device 20 and an output transport device 30, wherein the output transport device 30 and/or the input transport device 20 can be height-adjusted.

Claims

1. A device for curtain-coating of a panel-shaped component, comprising: a device for generating a liquid curtain of coating material; and an input transport device and an output transport device to guide the component to be coated through the curtain, wherein a gap is provided between the input transport device and the output transport device, through which surplus coating material may be led away; wherein at least one of the output transport device or the input transport device is height-adjustable and the device further comprises actuating means which is adapted to carry out a relative height-adaption of at least one of the input transport device and the output transport device automatically during the coating operation depending on a position of the component to be coated, wherein the actuating means is adapted to carry out at least one of raising an inlet area of the output transport device, or lowering an outlet area of the input transport device before an end section of the component to be coated leaves the input transport device, and wherein the actuating means is adapted to automatically adjust the inlet area of the output transport device at a higher level than the outlet area of the input transport device.

2. The device for curtain-coating according to claim 1, wherein the actuating means is adapted to automatically carry out at least one of lowering the inlet area of the output transport device, or raising the outlet area of the input transport device before a front section of the component to be coated comes into contact with the output transport device.

3. The device for curtain-coating according to claim 2, wherein the actuating means is adapted to automatically adjust the inlet area of the output transport device at a lower level than the outlet area of the input transport device.

4. The device for curtain-coating according to claim 1, wherein the device includes at least one of: the output transport device being rotatably supported at an outlet area order to effect a height adaption of at least the inlet area of the output transport device by rotation, or the input transport device being rotatably supported at an inlet area in order to effect a height adaption of at least the outlet area of the input transport device by rotation.

5. The device for curtain-coating according to claim 1, in combination with a plurality of panel-shaped components, wherein the panel-shaped components are rectangular and comprise a length which corresponds to a multitude of a thickness of the components, wherein the ratio of the length to the thickness (L/d) is at least 150.

6. The device for curtain-coating according to claim 5, wherein the ratio of the length to the thickness (L/d) is at least 240.

7. The device for curtain-coating according to claim 5, wherein the ratio of the length to the thickness (L/d) is at least 300.

8. The device for curtain-coating according to claim 1, wherein the input transport device and the output transport device are adapted to transport the panel-shaped components to be coated with a speed of at least 50 m/min through the curtain during operation of the device.

9. The device for curtain-coating according to claim 8, wherein the input transport device and the output transport device are adapted to transport the panel-shaped components to be coated with a speed of at least 100 m/m in during operation of the device.

10. The device for curtain-coating according to claim 8, wherein the input transport device and the output transport device are adapted to transport the panel-shaped components to be coated with a speed of at least 110 m/min during operation of the device.

11. The device for curtain-coating according to claim 1, wherein a raising speed of the actuating means during the raising is in the range of 1 cm/s to 10 cm/s.

12. The device for curtain-coating according to claim 11, wherein the raising speed of the actuating means is in the range of 1.5 cm/s to 7 cm/s.

13. The device for curtain-coating according to claim 11, wherein the raising speed of the actuating means is in the range of 2 cm/s to 6 cm/s.

14. The device for curtain-coating according to claim 11, wherein the raising speed of the actuating means is in the range of 3 cm/s to 5 cm/s.

15. The device for curtain-coating according to claim 1, wherein the input transport device and the output transport device comprise transport belts.

16. The device for curtain-coating according to claim 1, wherein the device further comprises means for the detection of the position of the components to be coated on the transport devices.

17. The device for curtain-coating according to claim 16, wherein the means for the detection of the position of the components to be coated is in communication with the actuating means.

18. The device for curtain-coating according to claim 1, wherein the device for generating a liquid curtain of coating material comprises a dispenser which generates the free-falling curtain.

Description

4. DESCRIPTION OF PREFERRED EMBODIMENTS

(1) In the following, the present invention will be explained in more detail with reference to the accompanying figures. Herein shows:

(2) FIG. 1 a curtain-coating device according to the prior art;

(3) FIG. 2 a schematic view of a device for curtain-coating, which is improved according to the invention;

(4) FIG. 3-10 the device of FIG. 2 in different operation conditions;

(5) FIG. 11 a schematic view of an alternative device according to the invention; and

(6) FIG. 12 a further alternative device according to the invention.

(7) Referring to the schematic views of FIGS. 2-12, the person skilled in the art recognizes that these Figures only show the basic components and are not true to scale. For instance the transport devices are in reality significantly longer than the components to be coated and the components to be coated are significantly thinner with respect to their length. In an existing prototype device both transport devices are each for instance more than 4 meters long and the components to be coated are boards made of wood material for the manufacturing of floorings in particular laminate floorings with a length of more than 2 meters at a thickness of just 6-10 mm. The gap between the two transport devices of the prototype is about 50 cm.

(8) In the following, the general construction of the device according to the invention is explained in view of FIG. 2. The schematic views of the FIGS. 3-12 are mostly the same, so that during the explanation of these further figures, always just the respective differences will be mentioned.

(9) FIG. 2 shows a preferred embodiment of a device 10 according to the invention for curtain-coating of panel-shaped components. The device 10 comprises an input transport device 20, which comprises a revolving transport belt 22, which is guided by corresponding drums 24. The input transport device 20 is arranged by means of a rigid frame 26 in a stationary manner. At the upper side of the input transport device 20 a first panel-shaped component to be coated, which is a panel and respectively a board 60, is transported in the direction of the arrow. In transport direction in front of the panel 60 a further panel 61 is located, which is already located on an output transport device 30 and is transported by it. The output transport device 30 also comprises a revolving belt 32, which is guided by drums 34. Contrary to the input transport device 20, the output transport device 30 is not rigidly fixed to a frame, but is supported at its outlet area via a hinge 35 in a rotatable manner. At the opposite side, so at the inlet area, the output transport device 30 is adapted in that its height may be adapted by means of a hydraulic cylinder 36. In a raising movement of the hydraulic cylinder 36, thus the transport belt 32 rotates in general around the hinge 35, as it is indicated by the double arrow at the hinge 35. In practice, for a length of the output transport device 30 of 4.5 meters, the raising height is just a few centimeters, for instance 5-6 cm as a maximum. In the figures, the raising movement is not true to scale, but is shown larger as it is in reality. A control unit 37 is provided, which is assigned to the hydraulic cylinder 36, wherein the control unit 37 is in communication via a data line 13 with a light barrier 12. The light barrier 12 serves as a means for the detection of the position of the components to be coated on the transport devices. The light barrier 12 detects for instance, where the front border of the panel 60 is located, so that together with the information about the transport speed the position of the panel 60 may be calculated and may be determined in relation to the further parts of the device. Alternatively, of course also other means for the detection of the position of the components to be coated are possible like for instance camera systems or laser and the like. The person skilled in the art knows from the prior art several means for the detection and supervision of the position and respectively of the way of such components to be coated so that herein a detailed explanation of such systems is omitted.

(10) Reference sign 40 indicates a schematically shown dispenser, which is filled with a coating material 41. The coating material 41 flows downwards through a corresponding spill gap as a liquid curtain 42. The coating material may be for instance a lacquer or resin, but in particular a primer layer for an ornamental print, which is applied afterwards. The method, how the coating-curtain is generated, is not relevant for the present invention and the person skilled in the art knows several possible methods for generating such a curtain. Between the two transport devices 20 and 30 a gap is provided, which comprises in reality a length of about 50 cm. In this gap, a funnel-shaped collecting container 45 is provided, in which the liquid curtain falls, when no component to be coated is located beyond the curtain 42. The funnel-shaped collecting container 45 is connected via a pump 46 and corresponding pipes (not shown) with the dispenser 45, in order to pump the surplus coating material back into the dispenser 45. Also these parts of the device are known to the person skilled in the art for curtain-coating devices so that a more detailed explanation thereof is omitted.

(11) FIG. 2 shows the ideal case, wherein the panels 60, 61 to be coated do not comprise any significant curvatures and wherein they also do not bend downwards due to their own weight, when they are guided over the gap between the transport devices. However, in reality it often happens that the panels to be coated comprise a curvature along their longitudinal axis and respectively are such thin that they slightly bend downwards due to their own weight, when they leave the input transport device. This case is schematically shown in FIG. 3 (in the FIGS. 3 to 12, means 12, 13 for the detection of the position of the panels are omitted for the sake clarity). Referring to FIG. 3, it can be seen that the panels 62, 63 to be coated comprise along to their longitudinal axis a slight convex curvature. The curvature is exaggeratedly shown in the figures so that it can be recognized therein. Due to the curvature, the front border of the panel 62 hits at position 91 against the output transport device 30, wherein a slight hit is generated. This leads at the panels at a corresponding area 71 to a coating mistake.

(12) FIG. 4 shows a further example of a possible coating mistake, which may be generated by uneven panels to be coated and respectively by very thin panels. In FIG. 4 the end section of the panel 65 just has left the input transport device. Due to the curvature of the panel 65 the end section of the plate swings a little bit downwards so that a short-term curtain break occurs at the position 90 and thus a coating mistake occurs. In reality, already a swinging downwards of the end section of the panel 65 of about 1 to 2 cm is sufficient to generate a coating mistake. In the FIGS. 5-10 it is schematically shown how the coating mistakes can be avoided, which have been described above with reference to the FIGS. 3 and 4 in an exemplary manner. In FIG. 5 the output transport device 30 is lowered by means of the hydraulic cylinder in relation to the input transport device 20. According to the invention the lowering of the output transport device was already carried out before the panel 66 and respectively a front section of this panel comes into contact with the output transport device 30. By doing so, the undesired hits, which are shown in FIG. 3, may be avoided.

(13) FIG. 6 shows the same panel 66, after it is transported a little bit further through the device 10. After the front section of the panel 66 came into contact with the transport belt 32 of the output transport device 30, the output transport device and respectively the inlet area thereof is again raised by the hydraulic cylinder so that the transport devices 20 and 30 are again at the same height. In FIG. 7 the panel 66 was still guided a little bit further through the device 10 and the output transport device 30 has been raised still a little bit further so that at least the inlet area of the output transport device 30 is raised to a higher level than the outlet area of the input transport device 20. The panel 66 is thus guided slightly inclined through the curtain 42, which surprisingly leads to in particular homogenous coatings, in particular for slightly curved panels. FIG. 8 shows the same panels 66, short after the end section of the panel has left the input transport device. The output transport device is shown in FIG. 8 in its highest position. The panel 66 is also guided with its end section inclined through the curtain 42. By doing so, the coating mistakes, which have been explained in the context of FIG. 4, may be effectively avoided. A whipping down of the end section of the panel as it is shown in FIG. 4 is avoided in that the panel 66 is carefully lifted by the raising movement, at least carefully in view of an uncontrolled whipping down, which occurs when the input- and output transport devices comprise the same height.

(14) In FIG. 9, the panel 66 has left the curtain 42 and is completely coated without any mistakes. The next panel 67 is still located completely on the input transport device 20 and the curtain 42 falls into the collecting container 45 so that the surplus coating material may be pumped by means of the pump 46 again back into the dispenser. In the operating condition, which is shown in FIG. 9 (it should be mentioned that the panels 66 and 67 move with a speed of about 100 meters per minute), the actuating means (i.e. for instance the hydraulic cylinder 36 and the control unit 37) effect that the output transport device 30 is again lowered in order to receive the succeeding panel 67. It can be seen in FIG. 10 that the output transport device 30 and respectively the inlet area thereof was lowered in relation to the input transport device 20 and was adjusted to a lower level than the height of the outlet area of the input transport device 20. The panel 67 may be thus received without any hit by the transport belt 32 of the output transport device 30 and may be transported further through the device 10, as it is shown in FIG. 5.

(15) The configuration, which is shown in the FIGS. 5 and 10 of the output transport device 20 should be preferably adjusted in the beginning of the coating proceeding, i.e. before a front section of a panel to be coated and respectively a board to be coated comes into contactand thus possibly in combination with a hitwith the output transport device.

(16) As already explained with reference to the figures, the control of the relative vertical position of the output transport device 30 is carried out automatically depending on the position of the components to be coated, like for instance of the panels, which are shown in the figures. When the means for the detection of the position detect for instance that the front section of a component is close to the curtain, this position information is transmitted to the actuating means, which then automatically effect a lowering of the output transport device 30 to the position, which is shown in the FIGS. 5 and 10. In a similar manner an automatic raising of the output transport device 30 may be effected, if the detection of an end section of a component indicates that the component is short before it leaves the output transport device 30.

(17) The gap between the two transport devices 20, 30 extends as it is known from the prior art perpendicularly to the transport direction of the components to be coated and the length of the gap should at least correspond to the length of the curtain so that the curtain may be completely received by the collecting container 45. It is also clear to the person skilled in the art from the schematic figures that the shown and claimed device as well as the method is not suitable to process sheet-like material like for instance paper sheets.

(18) Due to its very homogeneous interruption-free coating by means of the curtain-coating methods according to the invention, the coated panels are suited very well to be printed with an ornament by means of a digital printer device. The device, which is described herein is thus in particular generally suitable to be used in a facility for the manufacturing of directly printed flooring panels. In such a device, for instance the shown device for the curtain-coating may be provided in front of a digital printer device, in order to print an ornament directly onto a surface of the coated components by digital print. The print images, which are generated in such manner, comprise a significantly higher quality than digital print images, which are printed onto a surface coating, which was applied by means of common drum coating methods. In FIG. 11 an alternative device 10 is shown, wherein the output transport device 30 is arranged at both ends via two (or more) hydraulic cylinders 36 in a height adjustable manner. In FIG. 12, schematically an exemplary alternative device 10 is shown, wherein the input transport device 20 is arranged by means of hydraulic cylinder 36 in a height adjustable manner. It is generally preferred that only the output transport device is arranged in a height adjustable manner and this is preferably realized by means of a hinge, as it is shown in the figures, since this effects the lowest effort in construction matters and leads to sufficient results. However, it is also conceivable, just to provide the input transport device with a corresponding height adjusting ability or both transport devices, as it is shown in FIG. 12.

(19) The automatic height adjustability of the transport devices does not just allow the avoidance of coating mistakes due to irregular component surfaces or very thin, bending panels, but also in general allows surprisingly a more homogeneous coating due to the possibility to transport the components in an inclined manner through the coating curtain.