Curtain coating device

Abstract

A curtain coating device for paper and board machines has a nozzle beam (10) with a nozzle lip (12) with an edge strip (11) for feeding the coating color curtain and edge guides (20) located along each edge of the nozzle lips (12) controlling the width of the coating color curtain. The edge guide (20) has upper and lower ends. Flow surfaces (22) extend in a substantially vertical direction parallel and next to each other. The edge guide has a lubrication feed (24), additional lubrication feeds (26) and a suction opening (27). The flow surfaces (22) are inclined toward each other forming a flow guide recess (25) which extends in a vertical direction such that the form of the flow surfaces (22) with the flow guide recess (25) is concave. A protrusion (21) extends within the recess in the direction of the flow guide recess (25).

Claims

1. A curtain coating device for paper and board machines comprising: a nozzle beam; wherein on the nozzle beam are two edge strips which are positioned to contain a coating color curtain as the coating color curtain flows to a nozzle lip of the nozzle beam; wherein the nozzle lip has first and second edges between which the coating color curtain is contained; an edge guide located below each of the first and second edges of the nozzle lip so as to control the width of the coating color curtain after the nozzle lip; wherein each edge guide comprises: an upper end, and a lower end; flow surfaces extending downward between the upper end and the lower end in a substantially vertical direction; wherein the flow surfaces are next to each other and inclined toward each other so as to form a concave surface and to define a concave flow guide recess extending between the flow surfaces, and concave with respect to the coating color curtain, the concave flow guide recess extending in the substantially vertical direction; a protrusion extending in the substantially vertical direction of the flow guide recess and on the concave surface, wherein the protrusion defines two sides of the concave surface between which is positioned the protrusion; a lubrication liquid feed and additional lubrication liquid feeds arranged to supply lubrication liquid onto the concave surface; and a suction opening arranged to receive the lubrication liquid supplied by the lubrication liquid feed and the additional lubrication liquid feeds.

2. The curtain coating device of claim 1 wherein the upper end of each edge guides touches the nozzle lip of the nozzle beam.

3. The curtain coating device of claim 1 wherein the upper end of each edge guide is located 0.5-2 mm from the nozzle lip of the nozzle beam.

4. The curtain coating device of claim 1 wherein the lubrication liquid feed is located at a boundary formed by the edge strip and the upper end of each edge guide between the edge strip and the flow surfaces of each edge guide.

5. The curtain coating device of claim 1 wherein at a distance spaced from the upper ends of each edge guide is located at least one of the additional lubrication feeds on at least one of the two sides of the protrusion.

6. The curtain coating device of claim 1 wherein two of the additional lubrication feeds are spaced a distance from the upper end of each edge guide and are located on both of the two sides of the protrusion.

7. The curtain coating device of claim 1 wherein the edge guides are mounted inclinable so as to adjust the substantially vertical direction of the edge guides and so control the width of the coating color curtain after the nozzle lip.

8. The curtain coating device of claim 7 wherein the inclination angle of the edge guide is adjustable during coating.

9. The curtain coating device of claim 8 wherein the protrusion has an arched form.

10. The curtain coating device of claim 1 wherein the suction opening of each of the edge guides is located at a lowermost point of the lower end of each edge guide.

11. The curtain coating device of claim 1 wherein an edge strip of the two edge strips of the nozzle beam extends over the nozzle lip of the nozzle beam and is connected to the edge guides smoothly by a curved form.

12. The curtain coating device of claim 11 wherein each of the edge guides is mounted inclinable by a hinge located on the upper end of the edge guide, the hinge opening about a centerline; wherein a curved form is defined by a radius and a center point of the radius; and wherein the center point is on the centerline of the hinge.

13. The curtain coating device of claim 10 wherein the suction opening is formed by one suction hole which has a circular cross section.

14. The curtain coating device of claim 1 wherein the angle between the two flow surfaces of an edge guide is 170-176.

15. A curtain coating device for paper and board machines comprising: a nozzle beam having a nozzle lip having first and second edges; wherein on the nozzle beam are two edge strips positioned to contain a coating color curtain as the coating color curtain flows to the nozzle lip; an edge guide located below each of the first and second edges of the nozzle lip so as to control the width of the coating color curtain; wherein each edge guide comprises: an upper end, and a lower end; two flow surfaces extending downward between the upper end and the lower end in a substantially vertical direction, wherein the two flow surfaces are inclined toward each other at an angle of from 170-176 so as to define a concave flow guide recess extending between the two flow surfaces, and being concave with respect to the coating color curtain, the concave flow guide recess extending in the substantially vertical direction; a protrusion extending in the substantially vertical direction of the flow guide recess and between the two flow surfaces; and a lubrication liquid feed at the upper end of the edge guide and an additional lubrication liquid feed located on each of the two flow surfaces which lubricates the coating color curtain from each side in a thickness direction of the coating color curtain; a suction opening arranged to receive the lubrication liquid supplied by the lubrication liquid feed and the additional lubrication liquid feeds.

16. The curtain coating device of claim 15 wherein the upper end of each edge guide is located 0-2 mm from the nozzle lip of the nozzle beam.

17. The curtain coating device of claim 15 wherein the lubrication liquid feed is located at a boundary formed by the edge strip and the upper end of each edge guide between the edge strip and the two flow surfaces of each edge guide.

18. The curtain coating device of claim 15 wherein an edge strip of the two edge strips of the nozzle beam extends over the nozzle lip of the nozzle beam and is connected to the edge guides by a smooth curved form, wherein lubrication liquid is fed from inside the smooth curved form.

19. The curtain coating device of claim 15 wherein each of the edge guides is mounted inclinable by a hinge located on the upper end of the edge guide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following the invention will be explained more closely by reference to the accompanying drawings.

(2) In FIG. 1 is schematically presented one advantageous example of an edge guide of a curtain coating device in accordance with the invention.

(3) In FIG. 2 is schematically presented the upper part of the edge guide of the example of FIG. 1.

(4) In FIG. 3 is schematically presented the lower part of the edge guide of the example of FIGS. 1 and 2.

(5) In FIG. 4 is schematically presented the flow surfaces of the edge guide of the example of FIGS. 1-3.

(6) In FIGS. 5A-5C is schematically presented examples of the flow guide recess of the edge guide of a curtain coating device in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) During the course of the following description of FIGS. 1-5C like numbers and signs will be used to identify like elements, parts and part components unless otherwise mentioned. In the figures some references sign have not been repeated for clarity reasons. In the following the examples are described mainly by reference to an edge guide of a curtain coating device of a fiber web in view of simplifying the disclosure but it should be noted that instead of this example any type of an edge guide of a curtain coating device can have similar features and properties in accordance with the invention.

(8) In the example of FIG. 1 an edge guide 20 of a curtain coating device is attached to the nozzle beam 10 of the curtain coating device. The coating color curtain is formed by nozzles of the nozzle beam 10 and guided via the nozzle lip 12 toward the fiber web. The width of the coating color curtain is controlled by edge guides 20, of which one is shown in FIG. 1. The edge guide 20 is located below the edge strip 11 of the nozzle beam 10. A second edge guide, not shown, is spaced from the first at the opposite edge of the curtain beneath a second edge strip, not shown. The edge strip 11 guides the curtain to the edge guide 20. The edge guide 20 is connected to the nozzle beam 10 by a hinge 23, by which the inclination of the edge guide 20 in respect of the vertical direction is controllable even during coating. The inclination is advantageously 1-3. Between the edge strip 11 and the upper end of the edge guide 20 is located a lubrication liquid feed 24, shown in FIG. 2, which feeds lubrication liquid between the edge guide 20 and the edge strip 11. The curtain edge is guided downwards by the flow surfaces 22 of the edge guide 20. As shown in FIG. 1, the flow surfaces 22 form a flow guide recess 25 in the middle and the flow surfaces 22 with the flow guide recess 25 are in concave form. In the flow guide recess 25 is located a protrusion 21 extending in the direction of the flow guide recess 25, which protrusion 21 guides the edge of the coating color curtain in the flow guide recess 25. The protrusion is advantageously shaped so that its form fits inside a half-circle, which has a maximum radius of 7.5 mm. Additional lubrication feeds 26 are located at a distance from the upper end of the edge guide providing lubrication liquid to both sides of the curtain edge in the thickness direction of the curtain. At the lower end of the edge guide in the bottom corner is located a suction opening 27 for removing excess lubrication liquid and for necking the curtain to the fiber web.

(9) In FIG. 2 is presented the upper part of the edge guide 20 of the example of FIG. 1. As indicated by the arrow R, the uppermost part of the edge guide 20 at the upper end of the edge guide has a curved form with a radius R1 that corresponds to the center line of the hinge 23. The edge strip 11 connects to the upper end of the edge guide 20 smoothly. The lubrication liquid is fed by the lubrication feed 24 from between the edge strip 11 and the upper end of the edge guide 20. The upper end of the edge guide 20 is either touching or located at a small distance, for example 0.5-2 mm, from the edge strip 11. At a distance D, for example 5-50 mm from the upper end of the edge guide 20 the additional lubrication feeds 26 are located.

(10) In FIG. 3 is presented the lower part of the edge guide 20 of the example of FIGS. 1 and 2. The curtain edge is guided downwards by the flow surfaces 22 of the edge guide 20. The flow surfaces 22 form a flow guide recess 25 in the middle and the flow surfaces 22 with the flow guide recess 25 are in concave form. At the lower end of the edge guide 20 in the bottom corner is located suction opening 27 for removing excess lubrication liquid.

(11) In FIG. 4 is presented the flow surfaces 22 of the edge guide 20 of the example of FIGS. 1-3. The flow surfaces 22 form a flow guide recess 25 in the middle and the flow surfaces 22 with the flow guide recess 25 are in concave form. The flow surfaces 22 are inclined toward the middle and toward the flow guide recess 25 and the inclination angle A is advantageously 2-5. In the middle of the flow surfaces 22 is formed the flow guide recess 25 with a protrusion 21.

(12) In FIGS. 5A-5C are presented some examples of flow guide recess 25 with the protrusion 21 of the edge guide 20. In FIG. 5A the form of the protrusion 21 is outwards arched and in FIGS. 5B and 5C angular. In the example of FIG. 5B the protrusion 21 has an additional inwards arched groove 28. In FIG. 5B the cross section is shown at the location of the additional lubrication feeds 26, which are located on each side of the protrusion thus lubricating the curtain from each side in thickness direction. The flow surfaces 22 are inclined toward the middle and toward the flow guide recess 25 and the inclination angle A of each flow surface 22 is advantageously 2-5. The angle A can be measured with respect to a plane which passes through the two lines where the protrusion 21 intersects the flow surfaces 22. Hence the angle between the two surfaces 22 is advantageously 170-176.

(13) In the following some main points of the example of the FIGS. 1-4 are further explained. The curtain coating device comprises a nozzle beam 10 with a nozzle lip 12 with an edge strip 11 for feeding the coating color curtain and edge guides 20, which are located along each edge of the feeding slot/the nozzle lip 12 to control the width of the curtain. The upper end of the edge guide 20 is at a small distance from the nozzle lip 12 of the nozzle beam 10. The edge strip 11 of the nozzle beam 10 is extended over the nozzle lip 12 of the nozzle beam 10, whereby the coating color flows over the edge strip 11 without disturbances. The edge strip 11 is connected to the edge guide 20 smoothly by a curved form. Lubrication liquid is fed to the connecting surface area by lubrication feed 24 from inside onto the surfaces 22. Additional lubrication liquid is fed from additional lubrication feeds 26 at a distance D from the upper end of the edge guide 20 downstream of the curtain on each side of the curtain in the thickness direction of the curtain. The flow surfaces 22 with the flow guide recess 25 of the edge guide 20 are in its form concave toward the curtain. Advantageously the edge guide 20 is inclined from the vertical direction about 1 to 3 and the edge guide 20 has means for adjusting the inclination angle even during coating. The means for adjusting the inclination angle are advantageously the hinge 23 located near the upper end of the edge guide 20 and the center point of the radius R is on the center line of the hinge 23. The suction opening 27 for the lubrication liquid removal is located at the bottom corner of the edge guide at the curtain edge area. Advantageously the suction opening 27 is one suction hole, which has a circular cross section.

(14) In the previous only one advantageous example of the invention is described. Many modifications and alterations are possible in view of the invention.