FI90740C - Device for coating a moving web of paper or paperboard - Google Patents

Abstract

The metering mechanism positioned against a counter-roller and located behind, with respect to the running direction of the material web, a pre-coating facility features a slit 14 on the feed side of a balancing chamber 1 formed on a front wall 4 to the counter-roller 2 and extending over the width of the web. The front wall 4 is provided with discharge channels 10 extending in the manner of a slit across the width of the web, which can be throttled by a rotary disc valve 7. In this way, an outflow from the balancing chamber 1 can only occur through the discharge channels 10, while only the coating material from the material web can be introduced through slit 14 into the balancing chamber but no coating slip emerges from the balancing chamber. <IMAGE>

Description

90740 APPLIANCE FOR MOVING PAPER OR PAPERBOARD -ORDING FOR BESTRYKNING AV EN RORLIG PAPER- ELLER CARTON BANA 5

The invention relates to a device according to the preamble of claim 1.

Such a device has become known from DE-OS 15 46 10 312. Here the coating mass enters the leveling chamber through the inlet slot and fills it completely. Part of the coating mass exits the smoothing chamber, adheres to the paper web on the discharge side between the scraper element and the paper web. The second part, namely the excess, leaves the leveling chamber again on the inlet side and counter-15 in relation to the incoming brush mass therein. The inflow gap then has two flows that occur in opposite directions to each other.

These opposite currents always lead to problems. Namely, the quality of the pre-pressure 20 deteriorates in this countercurrent. Deterioration can usually no longer be smoothed out with a scraper element.

There are numerous other solutions, for example, a nozzle application device with a machine-width slit nozzle from which a jet of 25 pulp flows per paper web. There is also a hardworking overwork. Tailin again has an excess of corrugation zone between the two lips of the slit on the inlet side of the paper web. The excess must therefore also flow again against the direction of travel of the paper web. The consequences are as unfavorable as in the previously described device with a smoothing chamber.

In the following, the prior art has been further evaluated by means of the apparatus initially disclosed in U.S. Pat. No. 4,250,211, which is based on the principle that the pulp chamber in the opposite direction. The problem is that with the paper web traveling dry to the coating zone, due to the roughness of the web 2, a very large amount of air passes to the coating zone.

Correspondingly, in FI patent application 844151, the inlet side 5a of the web has a blade scraping the web as well as a transition point towards the blade below the coating zone. In this case, the excess coating mass is passed directly through this transition point.

In the solution according to FI patent application 861663, the plate with more than 10 germ points is formed in such a way that it forms a long constriction gap in the material web.

GB patent application 2,173,718 has a transition plate forming a choke gap with a web of material, raised in use 15 so as to be in contact with the web of material. In addition, at least one opening is formed in the plate of the transition point in excess of the baling mass. In this case, the plate of the transition point scrapes the web of material in an unfavorable manner.

U.S. Pat. No. 4,396,648 discloses an apparatus depending on the basic principle already described, in which a mainly rotating rod is placed in different positions and in fact controls the excess baling material flowing from the coating zone through the constriction gap of the transition plate.

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The object of the invention is to provide a device according to the preamble so as to avoid flow and countercurrent gaps in the area of the inlet of the equalization chamber.

30 In this task, the main requirement is solved with the features of novelty.

The invention is described in more detail in connection with the drawings. They set out in detail:

Figure 1 is a cross-sectional side view of the device.

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3,90740

Figure 2 shows another embodiment with only the essential elements in cross-section.

Figure 3 shows a top view of the embodiment of Figure 2.

Figure 4 and

Figure 5 shows other embodiments 10 of the invention in the same side view and also in cross section.

In the embodiment shown in Figure 1, the paper web surrounds the support roll rotating the paper web, as shown by the dotted line. The paper web is coated with a coating composition 18 applied by a roll application device (not shown) including a dipping roll. The lubricant 18 is applied in excess.

A smoothing chamber 1 is further seen, which - viewed in the direction of travel of the paper web-20 (see arrow) - is delimited on the inlet side by the front wall 4 and on the outlet side by a scraper 3.

On the opposite side of the counter roll 2, the leveling chamber 1 is delimited by the support walls 29 of the support beam and the Tension piece 25 attached thereto 25. The sliding blade 3 is attached to the tension piece 25 by means of a tension lever 28. Of the front wall 4 is maintained in the direction of the double arrow to the mobile kannatusseinåsså 29 (tåsså not shown in detail in the Detail).

30 As can be seen, the front wall 4 is formed in a special way. the edge portion 6 forms a wedge-shaped inlet wedge with respect to the support roll 2. in its front wall a discharge channel 10 is seen, which - viewed in the flow direction - consists of a part 8 having a relatively large flow-through cross-section and a part having a relatively small flow-through cross-section. Part 8 includes a cylindrical rotary slide 7.

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The rotating slide 7 has a plurality of openings 9, which - viewed in the direction of the longitudinal axis of the rotating slide 7 - are arranged side by side. Likewise, a number of outlet channels 10 are arranged over the entire width of the machine, as can be seen, for example, in Fig. 3 with regard to the second option 5 (openings 10 '). In this case, the length of the rectangular cross-section of the outlet openings 10 can also be substantially longer. It is theoretically possible - with a relatively small machine width - that only a single slit-like discharge channel is arranged, which extends over the entire width of the machine and, on the other hand, several rotating slides.

The alternative of the invention shown in Figures 2 and 3 illustrates only its front wall and cross-section (Figure 2) and the side from which the paper web comes (Figure 3).

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The front wall 24 then has exhaust channels 20 and the number of these channels is distributed over the entire width of the machine. The outlet ducts 20 are provided with a sliding strip 15 with a window 16. The number of windows 16 is exactly the same as the number of outlet ducts 20. The discharge channels can be opened more or less by pushing the sliding strip 15 against the direction of travel of the paper web, respectively, whereby the discharge channels are released more or less.

The amount of pre-dosing 25 applied in a large overdose is now transferred to the leveling chamber 1 through a gap 14 formed in the web. Preferably, the chamber may also be closed by retractable sidewalls 22 at the edges 30 of the web. A gap with a smaller gap width 14 is now obtained by displacing the front wall 4. The circulating slide 7 or the throttling slide 15 is then obtained so that the excess coating mass exits only through the discharge channels 10 or 20, but not at all or not in a significant amount through the gap 14. in the area as uniform as possible flow conditions in the smoothing chamber 1 including slot 14 and ii 5 90740 flawless coating without creases, orange peel formation, film unevenness or the like.

The alternative shown in Fig. 4 is substantially similar in structure to that shown in Fig. 1, except that the only difference is that the slide 7 and the discharge channels of the leveling chamber 21 are not located in the front wall 6 but in the rear wall 12 supporting the scraper 3.

In the embodiment shown in Fig. 5, the discharge channels 10 are located lower, i.e. in the wall 49 of the leveling chamber 31 further away from the counter roll 2 or from the material web.

15 The leveling chamber is preferably closed by side wall walls or sealing walls 17, 27, 37. 2 there is a 20 wax gap of 1-2 mm. These dam walls are preferably held in place by holding devices formed by extensions 33 of the walls of the leveling chamber. They can thus be adapted alternately and to different positions of the leveling chamber. This is shown in particular in detail in Figure 3.

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Claims (5)

Apparatus for coating a movable paper or cardboard web running around a rotatable support roll (2), said device being provided with a pre-coating device for applying coating material (18) with an excess, an equalization chamber (1.21). , 31) which is provided on the entrance side with a wall (4) which at the coated web has an open inlet gap (14) and on the output side is provided with a scraper element (3), characterized in that the leveling chamber (1,21,31) is provided with one or more outlet ducts (10,20,40,50) and the outlet ducts (10,20,40,50) are provided with throttling means (7.15) for controlling the the amount and / or pressure of the leaving coating mass. Device according to claim 1, characterized by outlet ducts (8,10,20) in the same wall (6) forming the inlet gap (14). 20 Device according to claim 1, characterized in that the outlet ducts (40,50) are located in at least one other of the equalization chamber (21,31) on the inlet side of the wall (24,26,34). 25 Device according to any one of claims 1 to 3, characterized in that the throttle body (7,15) is arranged inside the walls in question or constructively in immediate connection with them. 30 Device according to any one of claims 1 to 4, characterized in that the throttle member is made of one or more slides (15) or rotating slides (7).