JP4732890B2 - Application device - Google Patents

Abstract

A curtain coater for applying liquid to paste-like media (especially aqueous pigment suspensions) to a running sheet of paper, cardboard etc. has, in addition to an air boundary layer-abatement device on the coating side, another such device on the other side of the sheet near the point of impact of the curtain. A device for applying a liquid to paste-like medium, especially an aqueous pigment suspension (I), to one side of a running sheet of paper, cardboard or other fibrous material during its production and/or finishing. This comprises a curtain applicator (5) by means of which (I) is delivered directly onto the coating side (1a) of the sheet (1) in a free-falling, closed curtain (6) under the action of gravity, with the curtain impinging at a point (P) on an open section of sheet or on a part supporting the other side (1b) of the sheet, and with a device (2) for weakening or removing the air boundary layer, which is dedicated to the coating side (1a) and installed in the running direction (L) in front of the curtain (6). The system also has another air boundary layer abatement device (10) for air boundary layers (LG) flowing with the fibrous sheet (1), which is located on the other side (1b) of the sheet near the impact position (P) of the curtain (6).

Description

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

  Machines for the production and / or finishing of paper, cartons or other fibrous webs recently have a width of more than 10 m for economic reasons. During the coating of this wide fibrous web with a curtain applicator (curtain coater), the curtain released by the applicator is in a closed form, without the influence of harmful air inclusions. In order to ensure a uniform coating result over the width of the web, it must be kept stable over its entire width.

This requirement is even more difficult for a fibrous web to advance rapidly in a machine. Furthermore, it also depends on the quality of the fibrous web and the application medium.

  The curtain applicator is placed at a predetermined distance from the side of the fibrous web to be coated, for example a pigmented coating color as a curtain moving substantially under gravity from a machine-width channel nozzle The application medium comprising Coating with this applicator (curtain coater) is performed without excess media. This means that just as much of the media is released, it is applied to the fibrous web and finally remains on it. The curtain made by the applicator is therefore not very large and is particularly sensitive to the boundary layer of the flowing air.

  The subsequent publication (US Pat. No. 5,637,097) addresses the problem of the detrimental effects of the boundary layer of air flowing towards the applicator with a high speed fibrous web.

In the invention of the above-mentioned Patent Document 1, the air boundary layer reduction or attenuation device is arranged upstream of the applicator in the traveling direction of the moving fibrous web. An additional device (also referred to as a removal device) is provided around the coating side of the applicator or applicator nozzle so that the effect of the air boundary layer can be further reduced. These devices are here configured in the form of strips and, as described above, assigned to the side of the web to be coated. Furthermore, a structure is described that can shield the entire applicator or its parts or curtains against the influence of the air boundary layer.

  However, in the past, damage to the released curtain has nevertheless often been observed.

DE 103 58 508.7

The object of the present invention is therefore to eliminate these damages or at least further minimize such that a curtain applicator on a moving fibrous web can provide a more uniform application result during manufacturing and / or finishing. It is to specify an improved application device to be used.

  The object of the invention is achieved by the exemplary features of claim 1.

  In accordance with the present invention, an air boundary layer mitigation device for an air boundary layer flowing with a fibrous web is prepared to be placed on the side of the web facing the coating. This mitigation device is assigned to the longitudinal web section through which the moving web passes, in which the curtain collision point is located on the opposite side of the web.

  It is the applicant's achievement to recognize that the air boundary layer also adversely affects the fibrous web on the side of the web opposite the coating side. Thus, the web is prone to sag, bend, wrinkle or even break. The above-mentioned influence has a very detrimental effect on the opposite and upper side of the web, in particular on the curtain located at its point of impact.

  The proposed air boundary layer mitigation device can be manufactured as a structural unit with a support body and airflow wiping strips placed on it and acting in the direction of the underside of the web. Here, it is very convenient if the wiping strip is flexible. Ideally they touch the fibrous web slightly or not at all.

  In one refinement of the invention, this mitigation device can be arranged to be arranged as a collecting device for the curtain below the fibrous web. As a result, the device is more compact.

  The configuration can be done in various ways.

  For example, in one variation, the applicator operating aspect and / or web breakage to be configured simultaneously to collect the media portion of the curtain outside the width of the fibrous web, i.e., as an air boundary layer removal device. In this case, it is possible to prepare a current collecting device provided for collecting the discharged side edges of the curtain. The collecting device has a side wall that acts as a guide wall, so that during the operation phase of the application device, the inflowing air boundary layer can be removed and turned outward to a harmless position It is.

  The entire collection device is designed to swivel.

  In a further variant, a height-adjustable wiping strip can be prepared to be arranged on the supply side of the collecting device (the side on which the fibrous web advances towards it). The distance of the upper edge of the wiping strip can also be adjusted by a motor and manually.

  In a variant called the first, a further advantageous solution is to construct a considerable height saddle-shaped collecting device. As a result, it can be formed in a simple manner with respect to the flow so that the supply side (also the side where the fibrous web travels towards it) can serve as a guide surface for changing the direction of the air boundary layer It is. Furthermore, the collecting device has an upper edge or upper peripheral surface that continues substantially parallel to the moving fibrous web. This upper edge is very close to the fibrous web, i.e. at a distance of between about 0 and 3 mm. In this case, contact with the web or “penetration” (up to about −1 mm) is possible.

  As a result, it is possible to prevent the air boundary layer from being reformed over a specific range.

  The collector is located in the area between the two bodies supplying the fibrous web to the applicator and it is taken away from the applicator again and if appropriate it is redirected in the process. It is advantageous. Especially for small distances a, the fibrous web undergoes a certain amount of support in the area of the curtain applicator. In this arrangement, at least one side wall of the collecting device must reach at least one of the body or the guide body as much as possible, which has a particularly good influence on the progress of the web in the area of the guide body. Thus, the air boundary layer cannot be pushed between the guide body and the web, and still has a positive effect on the progress of the fibrous web in the further travel path through the manufacturing and / or finishing machine.

With regard to the progress behavior of the web, it is advantageous if the body or guide body is in each case formed as a rotating roll. The distance between the axes set from each other is 400 to 2000 mm, preferably 500 to 1200 mm. The bodies formed as guide rolls can be adjusted with respect to each other so that a guide for the lowering or raising of the fibrous web is obtained when the angle α is between 10 ° and 40 °. Such a slope (+/−) has proven to be particularly effective when depositing curtains on a fibrous web. The rising web guide has an advantage on the coating side in terms of preventing the ingress of the flowing air boundary layer, while the descending web guide has the effect of additional stretching of the curtain as it accumulates on the fibrous web. And thus has the effect of improving the quality of the applied layer.
A relatively large sized guide roll arranged upstream of the curtain already serves as a barrier for the air boundary layer in this case.

  Instead of a rotatable guide body constructed as a roll and possibly a suction roll, it is possible to prepare at least one guide body to be constructed as a stationary element. Suitable for this purpose are the well-known air turns for non-contact guide and fibrous web reorientation.

  One advantageous embodiment may consist of a collecting device with air boundary layer wiping strips that are foldable and face the flowing air boundary layer. Such a design can be produced even more simply than the production of side walls that are specifically formed as deflection walls.

  The entire collection device and the wiping strip can be designed to be turned as described above. This is convenient for maintenance purposes. In particular, a space is also created if a new web is introduced in this area, i.e. has to be transported.

  Further advantageous improvements emerge from the further dependent claims.

  In the text that follows, the invention will be described in more detail using exemplary embodiments.

  In the figures, elements or components that function identically or identically have the same name and are described only to the extent that changes with respect to other figures.

  In FIG. 1, it is shown how the fibrous web 1 moves in the direction of travel L and from the above progress to the first body 2 for web guidance and orientation change. In section 3 descending at an angle α of about 15 °, the web 1 then proceeds to the second body 4 from which the web 1 is further processed such as drying, smoothing, further coating, winding up, etc. Proceed downward.

  The two bodies 2 and 4 are guide bodies for the fibrous web 1. They can be constructed as so-called stationary air turns, illustrated in FIGS. However, in the example of FIG. 1, a rotating roll with a diameter between 400 and 800 mm is provided for this purpose. Due to their diameter, these, in particular, the first roll 2 are already suitable for serving as a device for reducing or removing the air boundary layer on the coating side 1a.

  The coating side 1a is arranged in the section 3 of the curtain applicator 5 of machine width (matching the width of the fibrous web), releasing the curtain 6 which freely and vertically descends onto the coating side 1a. The This curtain 6 collides with the fibrous web at the position P of the collision point or the collision line, and is deposited as a coating layer of the required thickness there. Destructive air boundary layer penetration in the direction of the curtain 6 is prevented or minimized so that this layer can be deposited as uniformly and defect-free as possible over the required web width or the required coating width. Various devices are provided. This is because if the curtain 6 is not stable and does not form a uniform, completely self-contained covering (no air ingress), the applied layer is also not uniform. These devices are upstream or downstream of the curtain 6 in the direction of travel L of the fibrous web 1 and are assigned to the web side, ie the coating side 1a. These so-called air boundary layer attenuation or removal or mitigation devices are constructed in the form of a first roll 2 and at least one sealing strip 7 arranged downstream of the first roll 2. After the curtain, on the same side as the web 1a, it is provided with a protective wall 8 which stands vertically and represents approximately the length of the curtain 6, for example with a destructive air boundary layer brought about by the pumping effect of the fibrous web. Again, prevent.

  For the sake of completeness, a collecting basket is shown which can be moved into or out of the curtain 6 in the direction of the double arrow, shown for the starting or stopping phase of the applicator 5. The starting kite is located above the second guide body 4 as it moves out.

  On the opposite web 1b side in section 3, a further air boundary layer damping or mitigation device 10 is in the region of the collision point P.

  In FIG. 1, in order to collect the side edges of the curtain 6 which are substantially discharged outside the width of the fibrous web 1 onto its side wall 11a on the supply side, this is wiped in an articulated manner. It is shown attached to a bowl-shaped collecting device 11 in the form of a piece 10a. The dotted lines and double arrows are intended to illustrate the folding down of the wiping strip 10a and also the entire ridge 11.

  FIG. 1 also shows that the side wall 11b on the exit side of the collecting basket 11 matches the contour of the body 4, i.e. roll 4, and together with its upper edge 11c facing the 1b side of the fibrous web, It extends over a long distance to the pocket 12 that exists between the 1b sides of the web. As a result, the pocket 12 is protected against the incoming air boundary layer LG, which improves the advancement behavior of the fibrous web 1 and further progresses the web to further processing steps shown downwards. Can be implemented without interruption.

  However, especially in the region of impingement at the point P, the curtain 6 is stable and thus ensures the high quality of the coating layer 13 deposited on the fibrous web.

  FIG. 2 likewise shows the fibrous web 1 coming from above and proceeding again towards the first body or roll 2 to guide and turn the web. Similarly, the curtain applicator 5 is disposed above the fibrous web 1 and the web 1a side. Dotted lines and arrows indicate that the applicator can move its position horizontally and / or vertically.

  Therefore, in addition to being able to move for operational purposes, in particular the collision angle β of the curtain 6 on the fibrous web 1 can be adjusted.

  Contrary to the view shown in FIG. 1, the fibrous web 1 advances towards the second guide body or second roll 4 over the section 3 rising at an angle α of about 30 °. As shown in FIG. 1, the two rolls 2 and 4 are made with a relatively large diameter and the size is about 400-800 mm. The first roll 2 can thus reliably keep the air boundary layer LG from flowing over the curtain on the coating side 1a. When the applicator 5 is disposed above the roll 4, the second roll 4 has an appropriate rotation speed so that the side edges of the curtain discharged outside the web width cannot contaminate the surface of the roll 4. It is preferable that the air cushion LP can be formed on the surface of the roll 4. The side edges of the curtain are lowered onto the air cushion LP and are brought along with the air cushion, especially into the collecting basket.

  If there is no air cushion or if the air cushion is inadequate, the side edges of the curtain must be deposited on the roll 4 and scraped off by the blade element.

  Just as in FIG. 1, the collecting device 11 is arranged below the fibrous web 1 and the web 1b side. This collecting device 11 is in such a way that it simultaneously serves as an air boundary layer mitigation device 10 for the air boundary layer LG flowing with the fibrous web 1 on the 1b side of the web not facing the curtain 6. Built.

  Here also, the collecting device 11 is bowl-shaped with an upper edge 11c that runs substantially parallel to the moving fibrous web 1. The upper edge 11c forms a distance of 0 to 3 mm from the 1b side of the web. The device 11 can thus contact the web 1 or even penetrate into the latter in the range of minus about 1 mm without the occurrence of scratches, abrasion dust or electrification on the web.

  From FIG. 2 in exactly the same way as from FIG. 1, the collecting device 11 guides the fibrous web 1, here also in the region between the two bodies / rolls 2 and / or 4 that are redirected, ie in the section 3. Among them, it is known to be disposed below the collision point P of the facing curtain 6. At least one side wall of the collecting device 11, specifically the outer side wall 11b to which the doctor sheet 11d is attached, extends to the pocket 12 between the roll 4 and the 1b side of the fibrous web.

  The double arrows drawn vertically on the collector are for the purpose of showing that the vertical adjustment is possible. Furthermore, although this is not shown separately, it is possible to pivot the device 11 downward.

  Incidentally, the collecting device 11 is dimensioned longer than the width of the web 1. In addition, the height of the collecting device 11 substantially corresponds to the size or diameter of the second body 4.

  It should also be mentioned that the interaxial distance between the two guides or deflection bodies 2 and 4 is about 400-2000 mm.

  The height of the two bodies can be set such that the lowering guide of the fibrous web 1 shown in FIG. 1 or the rising guide shown in FIG. 2 can be achieved.

  FIG. 2 also shows a side plate 14 arranged above the coating side 1a. This is on both sides of the machine and is likewise used to prevent the air boundary layer LG from flowing in the direction of the curtain 6. Its end facing the curtain 6 has been moved from the curtain 6 to a distance b of about 30 mm. The lower side of the web facing the 1a side is at a distance c of 0 to 3 mm. These dimensions ensure that the air boundary layer does not reform and thus contribute to the curtain being able to descend onto the fibrous web 1 without being affected by harmful effects.

  FIG. 3 shows that the air boundary layer mitigation device 10 is made as a separate component from the collection device 11. A flexible wiping strip 10a that is ideally not in contact with the lower side 1b of the fibrous web is disposed on the side where the web enters and exits. The device 10 can also additionally comprise a bleed device not shown.

  4 and 5 show an example in which the wiping strip 10a is arranged on the collecting device 11, that is, on the supply side of the collecting basket. The double arrows are for the purpose of indicating that the height can be adjusted.

  FIG. 4 shows the operating position of the wiping strip, while FIG. 5 shows a detailed view when the collecting device 11 with the wiping strip 10a is pivoted or moved down. The swiveling of the combined components 10 and 11 and the adjustment of the height of the wiping strip 10a can be performed both by the motor and manually.

  FIG. 6 as a whole represents all possible variations just before and immediately after coating by the curtain applicator 5 located above the fibrous web 1, for the path or direction L of the fibrous web 1. It is intended to show gender. These possibilities can also be used in the variants according to FIGS. A so-called air turn is shown in FIG. 6 as a guide body representative of all possible design variations of the guide and deflection elements. As a result of these feed gases or impinging jets in the direction of the web to be guided, the fibrous web 1 is guided without contact.

  FIG. 6 a shows a web guide corresponding to “U” with the bottom open or its inverse. The fibrous web 1 coming from below and first traveling upwards towards the guide body 2 is redirected by the guide body and then fed almost horizontally or up or down to the further guide body 4 and The latter can be turned downward again. The guide bodies 2 and 4 are both arranged below the fibrous web in this case, and an air boundary layer removal device 10 and a collection device 11 are also arranged between them, for reasons of clarity they are shown in FIG. Shown with arrows only inside. Above the fibrous web 1 is an applicator 5 that has already been described in FIG.

  Fig. 6b shows basically the same structure as the device of Fig. 6a, but this web guide is finally a "U" with the web proceeding upward again. The guide bodies 2 and 4 are here assigned to the coating side 1a.

  Figures 6c and d each show an S-shaped web guide.

In FIG. 6 c, the fibrous web 1 coming from above is redirected to a substantially horizontal direction, and the area with the curtain applicator 5 disposed above the web 1 is shown in the curtain 6 as in other figures. The direction is again turned downward after a substantially horizontal or ascending or descending web section that coincides with the collision point P.

In the case of the first change of direction, the first guide body 2 is located above the web, i.e. towards the coating side 1 a, and the second guide body 4 is located below the web 1. The web guide shown here also corresponds to the guide of FIGS. 1 to 5 and is a preferred variant.

  In FIG. 6d, the web and guide are shown inverted with respect to the variant according to FIG. 6c.

  Overall, the device according to the invention is characterized by its compactness and uncomplicated device modification with various air boundary layer removal or mitigation devices 10.

  Despite the additional accessories with additional modifiable equipment, curtain coating can be done in many ways. It can optionally be performed both with and without support. In this case both variable impact angles and various collection possibilities during start / stop operations and during application can be performed.

1 shows a schematic view from the side of a first embodiment of an application device according to the invention with a descending web guide. 2 shows a schematic view from the side of a second embodiment of an application device according to the invention with a rising web guide. Fig. 4 shows a schematic view from the side of a further embodiment of an application device according to the invention with a descending web guide. Fig. 4 shows a schematic view from the side of a further embodiment of an application device according to the invention with a descending web guide. Fig. 4 shows a schematic view from the side of a further embodiment of an application device according to the invention with a descending web guide. (a)-(d) shows the various examples before and behind the coating of the course of the web guide for fibrous webs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fibrous web 2 First body 3 Lowering section 4 Second body 5 Curtain applicator 6 Curtain 7 Seal strip 8 Protective wall 9 Start / stop rod 10 Air boundary layer reducing device 10a Wiping strip 11 Collecting device 11a Supply side wall 11b Outlet side wall 11c Upper edge 12 Pocket 13 Coating layer A Axis distance a Distance L Traveling direction LG Air boundary layer P Collision position or point α angle

Claims (17)

Application equipment for applying viscous media, especially liquids with aqueous pigment suspensions, to one side of a moving paper, carton or other fibrous web during its manufacture and / or finishing. And
Dispensing the application medium as a free-falling self-contained curtain (6) moving directly under gravity substantially on one web side or coating side (1a) of the moving fibrous web (1) And the curtain (6) impinges at a position (P ) on the section (3) into a region supporting the other web side (1b) of the fibrous web (1). (5)
Assigned to the coating side (1a), and a said curtain attenuation or removal device of the air boundary layer which is disposed upstream of (6) (2) in the direction of travel (L) of the fibrous web (1) In the application device ,
A further air boundary layer mitigation device (10) is provided for the boundary layer (LG) of the air flowing with the fibrous web (1), the air boundary layer mitigation device (10) being the impingement of the curtain (6). Assigned to the web side (1b) opposite the coating side (1a) in the region of position (P) ,
For collecting the application medium in the event of a break in the fibrous web (1) during the operating phase of the applicator (5) and / or of the curtain (6) released Provided for side edges,
Air boundary layer mitigation device for the boundary layer (LG) of the air that the collecting device (11) flows with the fibrous web (1) on the web side (1b) not facing the curtain (6) 10) An application device characterized in that it is constructed by a method that plays a role simultaneously . The collecting device (11) is bowl-shaped with an upper edge (11c) running substantially parallel to the moving fibrous web (1), and in operation the upper edge (11c) is said fibrous Application device according to claim 1, characterized in that it is at a distance between 0 and 3 mm from the web (1) . The collecting device (11) is arranged in a region between two bodies (2, 4) guiding the fibrous web, and at least one side wall (11b) of the collecting device (11) is not in particular contact. 2. The device according to claim 1 , wherein the body extends to at least one of the bodies (2, 4), and the body is suitable for imparting a change of direction to the fibrous web (1). Item 3. The application device according to Item 2. The application device according to any one of claims 1 to 3, wherein the collection device (11) and the air boundary layer mitigation device (10) are height-adjustable and / or pivotable. . 5. The collecting device (11) according to any one of claims 1 to 4 , characterized in that its longitudinal dimension is larger than the width of the fibrous web (1) . Application device. Each of the bodies (2, 4) is formed as a rotating roll having an interaxial distance (A) between 400 and 2000 mm, preferably between 500 and 1200 mm, and said fibrous web (1) 6. Application according to claim 5 , characterized in that the heights can be adjusted relative to each other in such a way that a guide that descends or rises at an angle (α) of 10 to 40 ° is obtained. apparatus. To claim 3 wherein the air boundary layer reduces device (10) is equal to or wider than the fibrous web (1) and / or the body which guides the fibrous web (2, 4) Application device described. The height of the collection device (11) and / or the air boundary layer mitigation device (10) approximately corresponds to the size or diameter of the second body (4) . The application apparatus as described in any one . Application device according to claim 3 , characterized in that at least one of the two bodies (2, 4) is stationary, i.e. does not rotate . 5. Application according to any one of the preceding claims , characterized in that after the fibrous web (1) has passed through the last body (4), it takes a downward path (L). apparatus. The position of the applicator (5), and thus the impact position (P) of the curtain (6), can be adjusted over the longitudinal direction of the web over the region that supports the fibrous web (1). The application device according to any one of claims 1 to 4, wherein Application equipment for applying viscous media, especially liquids with aqueous pigment suspensions, to one side of a moving paper, carton or other fibrous web during its manufacture and / or finishing. And
Dispensing the application medium as a free-falling self-contained curtain (6) moving directly under gravity substantially on one web side or coating side (1a) of the moving fibrous web (1) And the curtain (6) impinges at a position (P) on the section (3) into a region supporting the other web side (1b) of the fibrous web (1). (5)
An air boundary layer attenuation or removal device (2) assigned to the coating side (1a) and arranged upstream of the curtain (6) in the direction of travel (L) of the fibrous web (1) In the application device,
A further air boundary layer mitigation device (10) is provided for the boundary layer (LG) of the air flowing with the fibrous web (1), the air boundary layer mitigation device (10) being the impingement of the curtain (6). Assigned to the web side (1b) opposite the coating side (1a) in the region of position (P),
For collecting the application medium in the event of a break in the fibrous web (1) during the operating phase of the applicator (5) and / or of the curtain (6) released Provided for side edges,
Application device characterized in that the collecting device (11) comprises a foldable and / or height-adjustable air boundary layer wiping strip (10a) as the air boundary layer mitigation device (10) . Application device according to claim 12 , characterized in that the wiping strip (10a) is flexible . 14. Application device according to claim 13 , characterized in that the collecting device (11) is dimensioned so that its longitudinal dimension is larger than the width of the fibrous web (1) . To claim 12 or claim 13, characterized in that approximately corresponds to the size or diameter of the collecting device (11) and / or the air boundary layer reducing apparatus (10) of the height the second body (4) Application device described. 16. Application according to any one of claims 12 to 15, characterized in that after the fibrous web (1) has passed through the last body (4), it takes a downward path (L). apparatus. The position of the applicator (5), and thus the impact position (P) of the curtain (6), can be adjusted over the longitudinal direction of the web over the region that supports the fibrous web (1). The application apparatus according to any one of claims 12 to 16, wherein the application apparatus is characterized in that:

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