FI115407B - Paper / cardboard machine drawer coating unit - Google Patents

Description

115407

Paper / board machine curtain coating unit

The present invention relates to a paper / board machine curtain coating unit for coating a web of material, which curtain coating unit 5 includes a curtain coater located above the material web, from which the coating material can be fed in a curved stream to the surface of the material web.

One common structure and function of a curtain coating unit 10 for use in paper or board machines is known, for example, from FI 19991863, wherein the curtain coating unit consists of an elongated nozzle beam arranged transversely to the direction of the web of material to be coated. The coating agent is applied through a wide nozzle member or similar feed member such as a Kal-15 Teva plane as a curved stream onto the surface of the web of material moving below the nozzle to the point of impact (the web on which the curtain drips).

In addition, separate boundary layer exhaust means from the nozzle portion are provided in the region of the material web in front of the point of impact. These include a suction surface adapted to the coated surface of the material web, which: y; Through the 20, the air layer on the surface of the material web is sucked into the exhaust ducts, ie the air scraper between the suction surface and the point of impact.

The problem with such a curtain coating unit is the control of the straightness of the support frame and thus the foot beam in a changing loading environment. Even slight deflection of the nozzle unit affects the size of the nozzle gap and thus the feed rates of the coating material to be fed. Nowadays the problems have been solved ready. · By providing sufficiently rigid nozzle beams. Such structures are large, difficult: · to fabricate and hence expensive to fabricate. Although the external mechanical: loads are generally substantially constant, the nozzle portion is brought about by: a moderately unstable thermal load and the actual thermal expansion of the nozzle portion; and air flows further problems in controlling the linearity and thus the amount of coating material to be fed. The temperature fluctuations are due to the heat of 2,115,407 which, in material terms, is brought into the curtain coating unit. At present, the problems caused by temperature changes have been eliminated or at least reduced by equilibrating the environment of the curtain coating unit by placing the unit in a so-called calibration room. The calibration room is a large 5 room or room that maintains the optimum ambient conditions suitable for paving, particularly with respect to the support frame and nozzle bar. Such a solution is time consuming and expensive.

It is an object of the present invention to provide a curtain coating unit 10 which eliminates or can substantially reduce the aforementioned disadvantages.

To accomplish the aforementioned purpose, the present invention is characterized in that the curtain coating unit includes a body element, the boundary layer exhaust means together form a cover for the curtain coating.

: Y: 20 • *: The curtain coating unit construction of the invention partially or completely avoids the application of external loads and other coating material: the effects of adverse factors (temperature changes and air flows) which: otherwise directly apply to the curtain coating or to the coating material to be applied. At the same time, the structure of the unit is reduced to a smaller, more compact space, whereby the height of the coating material web is also more easily desired.

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

The invention will now be described with reference to the accompanying drawings in which: I »3 115407

Figure 1 is a cross-sectional view of a curtain wrapper assembly according to the invention, and

Figure 2 shows another embodiment of a curtain coating unit according to the present invention.

Thus, Figure 1 illustrates a curtain coating unit according to the present invention, designated by reference numeral 1. The curtain coating unit 1 is substantially disposed above the web of web material advancing. The Ver-10 silver coater unit 1 includes a curtain coater 4, or application bar. By means of a substantially wide web W-shaped nozzle portion of the Appli cation beam 4 or a similar feed portion such as a sloping plane, the coating material is formed into a web-wide W web curtain 20 which is applied to the impact point 21 at a predetermined height.

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The applicator beam 4 is tracked by a bracket which is connected to the frame element 2 of the curtain coating unit 1, for example in connection with the frame element 2. The Run test element 2 is elongated in the width direction W of the material web. The body element 2 is preferably C-shaped in cross-section so that it is open 20 on one side and its curved walls define space 10. Thus, the cross-sectional shape allows the application beam 4 to be fitted at least partially through the open side into space 10. As in the pattern • ·. 1, the body element 2 is partially enclosed between the lower material web W and the application beam 4. Hereby, the body element 2 itself forms a cover for the appliqué beam 25, which substantially prevents the harmful air currents and heat entrained in the web W from being transmitted to the applicator beam 4. The applicator beam 4 is disposed in space 10 with its nozzle portion therewith, the coating material 20 can be applied past the wall forming the space 10 and further to the impact point of the moving web of material 30 nanowatt 21. The material of the body element 2 is generally 'steel'. The body element 2 may also be coated or coated with a heat insulating material to enhance heat isolation.

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Further, the body element 2 is provided with means 5, 3 for removing boundary layer air A, preferably located at a point preceding the point of impact 21 with respect to the direction of travel of the material web W. The boundary layer air A is an air layer formed on the surface of the material web W that moves with the advancing material web W. The means for removing boundary layer air A includes a suction box 5 or the like, which has a suction surface facing the material web W. For example, openings are formed in the suction surface through which the boundary layer air moves from the surface of the material web W to the suction box 5. The suction box is further connected to the suction passage 3 through which the boundary layer air A is removed from the material web W and the The suction passage is arranged in connection with the outer surface of the wall of the frame element 2, i.e. on the opposite side of the application beam 4 from the wall. In this embodiment, the suction duct 3 is preferably formed of a curved wall 30 of the body element 2 and a curved duct element 30 disposed at a distance from the outer surface of the wall which substantially surrounds the outer surface of the body element 2. The suction duct 3 is thus formed in the space between the body element 2 and the duct element. In addition, in order to enhance the removal of air, preferably an elongated scraper member 5b is disposed adjacent the suction box 5 in front of the impact point 21 and is disposed transversely to the direction of travel of the material web W.

With this arrangement, boundary layer air A can be removed in a controlled manner from the surface of the material strip. At the same time, air A in the suction duct 3 and duct elbow-

·· '·,' ment contributes to both insulating and carrying away the otherwise material web W

* · - 25 to the frame element 2 and further to the application beam 4. Furthermore, the suction duct 3 is formed so long that the air A flowing therein compensates for possible transverse temperature differences of the material web W. Thus, the heat that may be transmitted to the frame element 2 and the application beam 4 is as smooth as possible in the transverse direction of the frame element 2 and the application beam 4. The applicator beam 4 and the boundary layer A exhaust means 5, 3 'are arranged in the same protective frame structure according to the invention, thereby providing a compact structure in which the various functions providing the various functions can be located in their optimum position. For example, the height of the coating material web 20 is more easily desired.

Figure 2 schematically illustrates another preferred embodiment of the invention. Here again, the curtain coating unit 1 consists of a frame element 2 according to the first embodiment, which is partially disposed between the material web W and the applicator beam 4, and in which the applicator beam 4 is at least partially located in the space 10 formed by the walls. In addition to the suction duct 3, other means for treating air 10 are provided in connection with the body element 2, the structure and operation of which are explained in more detail below.

The behavior of the coating material web 20 in the area of the impact point 21 is controlled by means of stabilizing air C, which is supplied to the area of the impact point 21 through blowing means 7, 7a, 7b and removed from the impact area 21 by the discharge means 6, 6a, 6b.

The blowing means for the stabilizing air C includes a blowing duct 7a through which the stabilizing air C is supplied to the curtain coating unit 1 from the blowing duct 7a. · ·. 20 stabilization air C is supplied to the distribution channel 7. The distribution channel 7 is formed. · ·. a space between the inner surface of the curved wall 2 of the body element (the side of the application bar 4) and the curved duct element, which is tracked from the inner surface a distance 70 mm. The other end of the distribution duct 7 forms a nozzle part 7b of the blowing means C, which is arranged to guide the stabilizer: · '·. *. 25 stabilizing air C with suitable force over the area of impact point 21 throughout the coating

hon 20 in width. The actual blowing channel 7a may be arranged by means of an elongated distribution channel 7 formed in connection with the body element 2, such that it is so far from the material web W that the material web W

ambient heat does not substantially affect the temperature of the inflatable stabilizer-30 ti-air.

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The stabilization air C is thus discharged by the exhaust means 6, 6a, 6b, which include a suction channel 6b which is arranged in the immediate vicinity of the nozzle part 7b in front of the impact point 21. An extension of the suction channel 6b is a transducer transfer channel 6. The transfer channel 6 is formed in accordance with the transfer channel 3 shown in connection with the first embodiment. In other words, the transport channel 6 is formed in the space between the outer surface of the frame element 2 and the second channel element 60, which is tracked from the frame element 2. At the end of the transfer duct 6 is provided an actual transverse web outlet duct 6a through which the stabilizing air C is discharged from the curtain coating unit 1. Like the blow duct 7a, the outlet duct 6a is located as far away from the material web W as possible. compact.

In another preferred embodiment of the invention, in addition to the aforementioned passages 15, means 5, 3, 3a for removing boundary layer A and blowing means 8, 8a, 8b for support air B are also provided in connection with the body element 2.

Here, the means for extracting boundary layer air A includes a suction box 5 or the like, which is arranged in the immediate vicinity of the suction channel 6b in the forward direction of the material web W 20 in front of the suction channel 6b. The suction box 5 has the extension • ·. · *. the boundary layer air transport channel 3. In this case, the transport channel 3 is ..,; formed from the aforementioned frame element 2 at a distance • •:. a second channel element 60 and a third channel element 30. The third channel element 30 'thus forms a comparator. ·, 25 the outer surface or cover of the silver coating unit 1, which partially insulates the material web of the nozzle bar 4 from the heat released. At the end of the transfer duct 3, as far away from the material web W as possible, is provided an actual transverse channel duct 3a through which the boundary layer air A is removed from the curtain coating unit 1.

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Further, in connection with the exhaust air exhaust means 5, 3, 3a there are provided: blowing means 8, 8a, 8b of the support air B, by means of which the spring B of the material web W is blown under low pressure on the surface of the material web W. Typically, the blowing pressure is 5 to 10 Pascal, but can be different. The support air B blowing means 8, 8a, 8b includes a blowing duct 8a through which the support air B is supplied to the curtain coating unit 1. The blowing duct 8a is located 5 here adjacent to the suction duct 3 delimited by the second duct element 60 and the third duct element 30 '. The extension 8a is provided with a distribution duct 8 into which support air B from the blowing duct 8a is supplied. The channel elements 60 and 30 'are spaced apart so that the distribution channel 8 can be located in a transmission channel 3 delimited by channel elements 10 and 30'. In Figure 2, the distribution channel 8 is a channel 8 between dashed elements 80, wherein the suction channel 3 surrounded by it. The end of the distribution channel 8 forms a nozzle part 8b, which is preferably arranged in connection with the suction box 5 in the vicinity of the material web W. Through the nozzle part 8b, the support air B is directed over the entire width of the web 15 to the surface of the material web W.

The present invention is not limited to the embodiments shown, but can be applied within the scope of the claimed claims.

Claims (8)

8, 115407 A paper / board machine curtain coating unit (1) for coating a material web (W), wherein the curtain coating unit (1) comprises a curtain coating (4) located above the material web 5 (W), from which the coating material (20) can be fed to the web (21), as well as means (5, 3, 3a) for removing boundary layer (A) air, characterized in that the curtain coating unit (1) comprises a frame element (2) and means (5, 3, 3a) for removing boundary layer (A). 10 and at least a portion of the frame element (2) and the boundary layer (A) exhaust means (5, 3,3a) are disposed between the material web (W) and the curtain wrapper (4), wherein the frame element (2) and the boundary layer (A) 5,3,3a) together form a cover for the curtain wrapper (4). Curtain coating unit (1) according to Claim 1, characterized in that the frame element (2) is arranged to support the curtain coating (4). Curtain coating unit (1) according to claim 1 or 2, characterized in that the walls of the frame element (2) define a space (10) which receives at least a portion of the curtain coating (4). A curtain wrapper unit (1) according to any one of the preceding claims 1-3, characterized in that the walls of the frame element (2) are covered with • 25 insulating materials (A, B, C) partially or completely. A curtain wrapper unit (1) according to any one of the preceding claims 1-4, characterized in that support means (8), blowing means (8, 8a, 8b) are provided in connection with the body element (2), the support air (B) blown through it forms a non-contact support of the material web (W) in the forward direction of the material web (W) in front of the point of impact (21). 115407 Curtain wrapper unit (1) according to one of claims 1 to 5, characterized in that means (7, 7a, 7b) for blowing the stabilizing air (C) through which the blowing stabilized air is blown are arranged in connection with the frame element (2). (C) forming a net formed by the coating material (20) in the region of the impact point (21). Curtain wrapper unit (1) according to one of the preceding claims 1 to 6, characterized in that means (6, 6a, 6b) for removing the stabilizing air (C) are provided in connection with the body element (2), through which (C) is removable from the impact point (21) of the curtain formed from the coating material (20). Curtain wrapper unit (1) according to one of the preceding claims 3 to 7, characterized in that the heat insulating material is air (A) moving in the means (5, 3, 3a) for removing the boundary layer air 15 (A), supporting air (B). air (B) moving in the blowing means (8, 8a, 8b), moving air (C) in the blowing means (7, 7a, 7b) and / or exhaust means (6,6a) in the stabilizing air (C), 6b) moving air (C). 10155407