FI115546B - Procedure for changing the driving conditions and arrangements of a curtain paver applying this procedure - Google Patents

Description

115546

A method for changing the operating conditions of a curtain wrapper and an arrangement applying the method

The present invention relates to a method of altering the run-5 properties of a curtain wrapper, the method of changing the impact angle between a plane passing through a web of paper / board web and a plane passing through a web of impact of a paper / board web.

A further object of the present invention is to provide an arrangement for changing the driving properties of a curtain wrapper, wherein the angle of impact between the direction of travel of the web formed from the paper / board web and the direction of travel of the coating web striking the paper / board web.

15 Curtain coaters used in paper and board machines are applied to the surface of the paper / board web to be coated, a coating composition, a paste or other suitable coating material. The coating composition is fed through a wide nozzle, inclined plane or similar feed member formed in the curtain coater, from which the coating composition falls as a curtain to the surface of a wide web of material moving below the nozzle of the curtain.

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In current devices, the application of the coating mixture is highly controlled by the coating-> », ·; by modifying the properties of the batch formulation, whereby quality is not always achieved

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* ·. goals. The driving conditions can also be controlled, as is known, through the speed ratio of the coating composition 25 to the web to be coated. However, in such cases, the composition and properties (such as viscosity, density) of the coating composition impose restrictions on the running speed. At high speeds, especially at the point of impact between the curtain formed from the coating composition and the web (the point on the web where the curtain drips), air may become trapped between the coating layer. 30 quality of the coated product. In addition, so-called "impact points" may form at the impact point.

The heel, i.e. the coating composition striking the web, may tend to extend in a direction opposite to the running direction of the web 2 115546. The curtain can also be broken before it hits the web.

There are devices for removing air entrained with the surface of the paper / board web as disclosed in patent application FI 19991863. It shows a scraper located in front of the point of impact with respect to the direction of web travel and intended to remove air passing through the surface of the web to improve the impact of the curtain. However, this does not eliminate the problems in the coating step due to the properties of the coating composition, especially when it is desired to coat the coating composition and the web to be coated at different speed ratios, for example for different paper grades.

It is an object of the present invention to provide an invention which eliminates or substantially reduces the aforementioned disadvantages.

To accomplish this, the method of the present invention is characterized in that the paper / board web is supported by the overhead support members at a position above the paper / board web before the impact point, *! 'with the free export of paper / cardboard between the support points,

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. and that the direction of the course is changed to change the angle of impact. ; adjust the position of the lower support members to ensure free movement in the area.

Further for this purpose, the arrangement according to the present invention is characterized in that the arrangement comprises upper support means for supporting the paper / board web from above the paper / board web at a point * before impact, the supporting members below the paper: - *: / board web. to support the post-impact point below, where- ·. The 30-ball impact point is within the free export area of the paper / board web 3 115546 between the support points, and that the lower support members are adjustable to change the angle of impact.

An advantage of this method and arrangement is that the simple arrangements 5 provide a modified angle of impact and thus advantageously influence the behavior of the curtain as it falls onto the web. In particular, so-called heel formation can be prevented from forming in the coating mixture at the point of impact. Thus, as the web-curtain velocity ratio increases or decreases (i.e., mainly as the web web speed increases or decreases), the same coating composition 10 can be used without compromising on quality objectives. Also, the composition of the coating composition can be changed without changing the web speed or at least the web speed changes compared to the prior art are considerably smaller.

Preferred embodiments of the present invention are set forth in the dependent claims.

The present invention will now be explained in more detail with reference to the accompanying figure, which schematically illustrates an embodiment of the invention.

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The figure thus shows a principle view of an arrangement according to the invention,. which applies the process of the invention. The actual curtain wrapper 1 is disposed here above a movable web (web, direction indicated by an arrow) of a paper / board web W. From the paper or board web 25, the term material web is hereinafter used. The widthwise applicator nozzle 1a of the material web W is disposed at a distance from the material web W (the so-called drainage distance) so that it can be applied or ": drain the coating composition onto the surface of the moving web W. 30 is substantially wider than the width of the web W. However, the width of the curtain F may be slightly wider than the web W, whereby a wet edge is formed on the web to be coated. The width of the curtain F may also be formed narrower than the web W, At the end of the free fall, the curtain F strikes the surface of the material web W in the direction of the first plane P at a so-called impact point I, from which the curtain F rotates in the direction of travel of the material web W to form a covering es germinated here in a direction substantially parallel to the vertical plane P, but this may of course depart from this. The material web W is made of paper or paperboard.

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The arrangement of the curtain wrapper 1 comprises upper support members 2 and lower support members 3 for supporting the material web W. The upper support members 2 are disposed at a point prior to the point of impact I with respect to the direction of travel of the web W. The upper support members 2 include a surface facing the material web W 15 formed as a suction surface to provide sufficient support. The point closest to the point of impact I on the suction surface is arranged as close as possible to the point I of impact. The upper support members may consist of other elements such as a pivoting box. Fans are provided on its surface to form an air mattress between the surface and the material web W.

! : 20: The upper support members 2 at the same time break up the material web over W. air layer. In addition, it helps to disperse and remove the air layer. *,: arranged in connection with upper support members 2 or upper support members 2. · '. deaeration means 4, 4a comprising an elongate scraper member 4 in the width direction 25 of the material web W; an elongated scraper member 4 disposed transversely to the upper support members 2 transversely to the running direction of the web W; · 'In front of the bulge I on a surface facing the material web W at a short distance from the impact point I. This distance corresponds substantially to the distance between the upper support members 2 and the impact point I. In the distance corresponding to this distance. 30, there is no time to form a new layer of air on the surface of the material web W.

• Typically this distance is about 3 to 8 cm, for example about 5 cm. The required distance of 5 115546 depends on the speed of the material W and the surface quality. Further, the brewing member 4 includes a duct which is connected to a suction duct 4 through which the air layer over the material web W is removed.

The lower support members 3 are disposed at a point after the point of impact I with respect to the direction of travel of the web W. The lower support members 3 may be a roll 3 on whose support plane formed by the sheath the web W of material is supported from below (i.e., the uncoated side) as shown in the example. The lower support members 3 may be another support plane or the like, which includes web supporting members 10, for example a turning box as previously described.

Since the support roll W 3 is disposed in the propagation direction of the web W after the point of impact I, between the upper support members 2 and the lower support members 3 there is a free area A of the free web material longer than the upper exhaust members 4 or 15. The distance between point I and the point of impact. Thus, the impact point I is in the free-export region A. In the free-export region A, the material web W is tensioned, which dampens any harmful vibration that might otherwise occur.

As can be seen from the figure below, the curtain F drips to the impact point I on the material web W through the free passage area A of the material web W: relative to the direction of travel of the second plane Q at an angle β. This angle β: is the so-called impact angle. By changing the position of the support members 3 below, * *; * '; it is possible to change the direction of travel of the material web W and thus adjust the impact angle β. To this end, the lower support members 3 are provided with a li; · Connecting means 5 for moving the lower supporting members 3. Preferably, these actuating members 5 include: a plunger cylinder 5 or more plunger cylinders operably connected to one another, with lower support members 3 attached to the end of the piston rod.

As the piston rod is moved, the lower support elements also move at the end of the 3 piston rod. The piston cylinder 5 can be arranged to be pivotable about its attachment, for example around the pivot axis of the track, whereby the position of the lower support members 3 can be better adjusted. The actuating members 5 are attached to a body part of the curtain coating arrangement not shown in the figure. Naturally, members or apparatus of different construction, for example screw guides, may be provided for moving the lower support members 3.

The figure schematically shows an example of adjusting the angle of impact β. The Is angle angle β can be adjusted in the region between the minimum angle βι and the maximum angle β2 by moving the position of the lower support members 3 by means of the movement means 5.

10 Adjustment can also be made while driving. The position of the lower support member 3 drawn in a solid line corresponds to the smallest angle of impact βι, whereby the direction of propagation of the material web W is preferably substantially laterally inclined. The minimum angle βι provided by the curtain coating arrangement of the invention is less than or equal to 90 degrees, preferably between 25 and 90 degrees. In Example 15, this angle βι is about 73 degrees. The position of the lower support member 3 drawn with a dashed line corresponds to a maximum angle β2, whereby the direction of propagation of the material web W is preferably substantially laterally downward. The maximum angle β2 provided by the curtain coating arrangement is then greater than or equal to 90 degrees, preferably 90 to 155 degrees. In the example, this angle β2 is about 130 degrees.

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By altering the impact angle β, the behavior of the coating composition can be affected. ; as it touches the surface of the material web W. For example, when used. ·, | large amounts of coating and / or low web speeds of web W are formed at the impact point I and its region more easily by a "bearing" (not shown) formed by the coating composition as the coating composition tends to extend in the opposite direction to the web direction. In this case, it is preferable to adjust the travel direction of the web W downwardly in the previously taught manner, or at least to adjust the impact angle β between the above-mentioned planes P and Q so that the coating mixture is better guided in the travel direction of the web.

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Further, when small amounts of coating and / or high web speeds of web W are used, air penetration between web W and the coating composition is more likely. In this case, it is advantageous to adjust the direction of travel of the web W in an upwardly inclined manner, or at least to adjust the impact angle β between the aforementioned planes P and Q to reduce air penetration. Of course, the angles βι-β2 used generally in the arrangement of the invention also depend on the web speeds of the web W used and the properties of the coating composition. Naturally, the direction of travel of the web W can also be horizontal.

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Furthermore, it should be noted that the drainage distance between the nozzle Ib of the feeder 1 and the material web W is not substantially changed due to the adjustment of the stroke angle β. In part, this makes it easier to control, adjust or change the coating conditions.

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The present invention is not limited to the above example but may be applied within the scope of the claims.

Claims (16)

A method for changing the driving characteristics of a ridgeline coating (1), in which the method of impact angle (β) between a plane (Q) extending in the direction of travel of the paper / cardboard web 5 (W) and a The downward point of the tongue web (W) (I), the descending coating ridges (F), running direction extending plane (P), characterized in that the paper / cardboard web (W) is supported with an upper support member (2) from the top of the paper / cardboard web (W). in a position before the impact point (I), and the paper / cardboard web 10 (W) is supported with lower support means (3) in a position after the impact point (I), which impact point (I) is located within the area (A) of the paper / The free guide of the cardboard web (W) is positioned between the supporting positions and, in order to change the angle of impact (β), the running direction of the web within the area (A) of the free guide is changed by controlling the position of the lower supporting members (3). 15 2. A method according to claim 1, characterized in that the upper layer of the paper / cardboard web (W) upper side is removed with air discharge means (4, 4a) in connection with the upper support means (2). • ♦ * • · * • ·: * ·. 20 Method according to Claim 1 or 2, characterized in that the angle of impact (β) is 25 degrees -155 degrees. A method according to any of the preceding claims 1 - 3, characterized in that the direction of travel of the paper / paperboard (W) within the area (A) of the free casing is horizontal, obliquely oblique. or sloped down. Method according to any of the preceding claims 1 - 4, characterized in that the position of the lower support means (3) is controlled by displacement means (5) arranged in connection with the lower support means (3). 30 115546 Method according to any of the preceding claims 1 - 5, characterized in that the web is supported against the upper support means (2) by means of suction. Process according to any of the preceding claims 1-6, characterized in that the air layer on the upper side of the paper / cardboard web (W) is removed with suction ducts (4,4a) arranged in connection with the upper support means (2). Arrangement for changing the driving characteristics of a ridgeline coating (1), in which arrangement the angle of impact (β) between a plane (Q) formed in the running direction of the web / paper web (W) and a paperboard The downward point (I) of the descending coating ridges (F) of the / cardboard web (W) running direction extending plane (P), characterized in that the arrangement comprises upper support means (2), which support the paper / cardboard web (W) from the paper / cardboard web ( W) upper side in a position before the impact point (I), and lower support means (3) in a position after the impact point (I) for support of the paper / cardboard web (W) from below, the impact point (I) being located within the area (A) for the free movement of the paper / cardboard web (W) located between the support positions and the lower support members (3) being adjustable. ·. to change the angle of impact (β). 20 Arrangement according to claim 8, characterized in that the upper: supporting means (2) are provided with air discharge means (4,4a) for removing in the air layer on the upper side of the paper / cardboard web (W). * »'» Arrangement according to Claim 8 or 9, characterized in that the wine 1 (β) between the impact point (I) and the paper / cardboard web (W) can be changed between 25 degrees and 155 degrees. * 11. Arrangement according to any of the aforementioned claims 8-10, characterized in that the running direction of the paper / cardboard web (W) in the area "(A) of the free guide can be changed in the right direction, obliquely up or obliquely down . 115546 Arrangement according to any of the aforementioned claims 8-11, characterized in that the lower support means (3) can be controlled by means of displacement means (5). 5 Arrangement according to claim 12, characterized in that the displacement means (5) are piston cylinders. Arrangement according to any of the aforementioned claims 8-13, characterized in that the distance between the impact point (I) and the upper support means (2) or the air discharge means (4,4a) closest to the impact point (I) is less than the path of the paper / cardboard web (W) running, under which an air layer is formed on the surface of the paper / cardboard web (W). 15. Arrangement according to any of the aforementioned claims 8-14, characterized in that the upper support means (2) have a suction surface for supporting the paper / cardboard web (W). . ·. Arrangement according to any of the previously mentioned claims 8-15, characterized in that the air discharge means (4, 4a) consist of suction ducts. * · • «'I • · • • • t • - · •> • · • ·» »' I