Patent Application
20140023790
The present invention relates to an applicator arrangement comprising base support arrangement, a supply unit for supply of coating liquid/slurry, an applicator device, and a metering device.
The so called blade coating technique is a prior art method for the coating of running webs. This technique that exists in lots of varieties is based on the principle that a coating medium (colour, starch for example) surplus is supplied at a surplus to the web at a position prior to a final dosing metering means. Said final dosing and metering means may be composed of structure combined with thin flexible blades, rigid blades or rods that, similar to puttying, doses out and applies the amount of coating medium, see for example WO 2007/061378 which is herewith incorporated by reference. The dosing and coating means are comprised in an applicator arrangement, which for instance comprises means for handling the surplus of the coating medium, which is returned for circulation and reuse by the arrangement. Prior art applicator arrangements present several disadvantages, e.g. having a bulky and relatively complex structure.
In US 2001/0008118 a coating device for directly or indirectly applying a coating medium onto a running paper- or boardweb is shown. The device includes nozzle lips of which at least one is being formed by a blade element. By applying an elastic nozzle lip, the nozzle gap can be enlarged. The coating device includes a mechanism for adjusting the height of the nozzle gap. A disadvantage with this design is that it designed as a separate unit implying difficulties in achieving a compact design of the whole application arrangement.
A related problem within the field of dosing and coating arrangements is that the coating medium mostly has to be supplied at a temperature that is different (normally higher) compared to ambient temperature, in combination with the fact that the total applicator arrangement is relatively large, i.e. extends over the cross machine width. As consequence there may result temperature gradients causing bending of the applicator arrangement, which may result in coat weight variations. According to prior art this problem is commonly handled by costly and bulky temperature control structures, e.g. as shown in EP 0 931 878. This prior art document describes a fountain coating applicator presenting an alternative manner of handling the latter problem, i.e. the tendency of heated coating to cause a temperature gradient is counteracted by cantilevering the applicator head on arms from a support beam through which a temperature-controlling fluid is circulated.
It is an object of the present invention to overcome or at least minimize at least one of the drawbacks and disadvantages described above, which is achieved by means of an arrangement and method according to the appended claims.
Thanks to a solution according to the invention there is provided an applicator arrangement which is very compact and does not require as much space as prior art technique does. Investment costs may be smaller and the accessibility of the arrangement makes maintenance and reparations easier and cheaper. According to a preferred embodiment this achieved by an applicator arrangement wherein means for distribution of coating medium and scraping off a surplus of coating medium are in the form of integrated units.
According to one aspect of the invention the applicator arrangement according to the invention comprises a supply unit for supply of coating liquid/slurry, an applicator device and a metering device, wherein said supply unit forms a support for at least one of said applicator device and/or metering device, and wherein at least one of said applicator device and/or metering device is directly or indirectly attached to said supply unit. Preferably said supply unit comprises a distribution pipe which in its turn is supported by a support body by means of a bearing arrangement arranged to enable axial expansion and contraction of said distribution pipe.
It is to be understood that said supply unit forms a support body for said applicator device and/or metering device in the sense that it receives forces transmitted from said applicator device and/or metering device upon operation. This means according to the invention at least a majority of the forces applied from the applicator device and/or metering device upon use are arranged to be spread to and distributed within the body which constitutes said supply unit.
Positive effects of synergy are obtained thanks to an applicator arrangement according to the invention, among others that a shorter flow passage is acquired between the supply unit and the mouth of the applicator device, i.e. in addition to the compactness of the arrangement also the radially shorter flow passage contributes to acquire an even flow of the coating medium.
According to another aspect of the invention the applicator device of the applicator arrangement comprises nozzle lips forming the gap for outlet of the coating medium.
According to yet another aspect of the invention both of said applicator device and said metering device are attached to said supply unit, which provides a very compact and easily maneuvered applicator arrangement.
According to still another aspect of the invention said supply unit is in the form of a distribution pipe or tube, preferably a circular tube of a metallic non welded design, more preferred a standard tube, which provides a much more cost-efficient pressure vessel than traditionally used supply vessels.
According to another aspect of the invention said supply unit is supported by a support body, wherein preferably said support body is made in a much cheaper material than the supply unit, e.g. a low alloy steel. Hereby manufacturing costs for an applicator arrangement according to the invention can be cut.
According to another aspect of the invention said supply unit is supported on the support body by means of bearing arrangement arranged to enable axial expansion and contraction of said supply unit, thereby eliminating the need of sophisticated tempering means to avoid bending of the body.
According to another aspect of the invention said supply unit is arranged to function without the use of any cooling housing, that otherwise would participate in the expansions/contractions of the supply unit, which makes the arrangement significantly less expensive and more easy to control.
According to another aspect of the invention said support body/base support arrangement is in the form of a tube, preferably made in a low cost steel material, which further leads to improve cost-efficiency.
According to another aspect of the invention said support body is arranged to contain circulating tempering liquid. Hereby is achieved a very efficient way of keeping an even temperature around and along the entire support body leading to that excellent precision is acquired when operating the coating machine.
According to another aspect of the invention the space for the circulation liquid within the support body is delimited by means in a body positioned within the interior of the support body to form said space between the inner surface of the support body and the exterior surface of the inner body. Hereby the needed volume of tempered medium is substantially reduced, and thereby also the total weight.
According to another aspect of the invention said delimited space is provided with sealing members enabling spiraling circulation which improves tempering within the support body.
According to another aspect of the invention said base support comprises a pivot arm arranged to enable pivoting between an active and inactive position of the applicator arrangement and wherein the active pivot axis of said pivoting arm is positioned within an area defined by the vertical tangents of the roll onto which the applicator arrangement is fixed, which improves the compactness.
According to yet another aspect of the invention, and thanks to the compact and space-saving arrangement according to the invention two applicator arrangements may be positioned at the periphery of one and the same roll, directly after each other. As a result of this a very well-covering coating of the surface of the running web may be achieved.
The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
The following detailed description, and the examples contained therein, are provided for the purpose of describing and illustrating certain embodiments of the invention only and are not intended to limit the scope of the invention in any way.
In
The applicator arrangement will now be described referring mainly to
Further, the distribution pipe 62 is supported by a support body 3 by means of a bearing arrangement 31 arranged to enable axial expansion and contraction of said distribution pipe 62. The support body 3 is mounted on a holding bracket comprising a pivot arm 8 which is pivotally arranged about a pivot axis 80, of a pivot axis 81, whereby said supply unit 6 may be moved towards or away from the backing roll 2. A cylinder 9 is arranged to make the holding bracket 8 movable. Together said holding bracket 8 and said cylinder 9 forms said base support arrangement 8, 9. The cylinder 9 may be affixed in many different ways. The pivot arm 8 is arranged to enable pivoting between an active and inactive position of the applicator arrangement 1, and the active pivot axis 80 of said pivoting arm 8 is positioned within an area defined by the vertical tangents of the roll onto which the applicator arrangement 1 is fixed. Thanks to arranging the pivot axis 80 of the bracket 8 in a region preferably underneath the roll 2, the lever arrangement and the whole movable unit becomes less space consuming.
In the example of
In
A support body 3, that supports the distribution pipe 62, forms a fixed stable structure together with distribution pipe 62 implying that there is no need of a temperature control arrangement to eliminate undesired tensions due to temperature changes (which can otherwise lead to bending=uneven coating). The support structure 3 may not be eliminated by making the distribution pipe 62 “self-supportive” due to the extremely expensive material thereof, which is needed due to the extreme demands, e.g. depending on the desire to minimize fall off of coating ejected from the nozzle gap 55, which is achieved by having the coating 4 supplied at high pressure. However, thanks to the novel concept the support body may be made in any suitable material/form that fulfills the desired need of providing stabile support, e.g. a standard low alloy steel tubing, which facilitates low cost production. Low alloy steel may be defined as a steel having a total of alloying elements, e.g. Ni, Cr and Mb, below 10%, preferably below 8%, and more preferred below 5%.
According to one embodiment, the distribution pipe 62 is slidable arranged in relation to the support structure 3, e.g. by providing a support base 30 with a bearing 31, which bearing 31 is arranged with a first low friction interface 310 arranged on the support base 30 and a second, mating, low friction interface 311 on the bottom part of the supply tube 62, to allow the distribution pipe 62 to freely slide due to heat expansion/contraction, thereby in an easy, cost-efficient and safe way safeguard a tension-free supply tube 62, i.e. eliminating the need of a cooling arrangement and eliminating a complex support structure 3.
As is illustrated in
Said applicator device 5 and/or metering element 7 are attached to the supply unit 6 directly or indirectly, meaning that at least a major portion of the forces created upon the metering element 7 being brought into contact with the underlying running surface are transmitted to and spread within the body of the distribution pipe 62. This leads to improved ability of withstanding applied stress and thereby also to an elongated life time of the equipment.
Other ways of attaching the holding body 56 are also possible, for instance by means of an interconnecting member (not shown) fixedly arranged on the pipe 62 which in its turn provides a fastening location for said foot 59. Such an interconnecting member may be attached onto the pipe 62 for instance by means of screwing, thereby replacing the need for producing said groove 63.
The coating medium 4 leaves the equalization chamber 53 through a gap 55 and is applied on the surface of a web W or a transfer roll or a gravure roll 22 (as will later be described). The nozzle lips 54, 56 form the gap 55 for outlet of the coating medium. By means of a flexible pressure member 561 and a hinge portion 560 the size of the gap 55 may be continuously controlled. According to one embodiment the holding body 56 is made in one piece and consists of an elastic material which leads to that it can be made to flex about the hinge portion 560 towards or away from an underlying surface, for instance by means of said flexible pressure member 561.
The holding body 56 is provided with a metering element 7 (see WO 2007/061378 where the use of the metering element 7 is described) arranged on the upper portion of said holding body 56. Said metering element 7 comprises a circular body which is pivotally arranged about its length axis. The metering element 7 is further provided with a ridge-formed metering portion 70 having a first meeting side 71, said side 71 being continuously curved, and a rear side 73 comprising an upright edge thereby forming an edge 72 between the meeting side 71 and the rear side 73.
In an arrangement using this metering element 7 the advantage is obtained that when no contact is wanted between the metering element 7 and the web or roll the metering element 7 is turned so that no contact longer exists between the metering portion 70 and the web or roll 1. This means that the supply unit 6 as a whole may remain in its position.
The embodiment shown in
In
The support structure 3 is delimited by means of a body 32 (e.g. an inner tube member) positioned within the interior of the support base 30 to form a space 38 between the inner surface of the support base tube 30 and the exterior surface of the inner body 32, said space 38 being arranged to provide for a flow of tempering liquid for acquiring an even temperature along and around the support base 30. In one embodiment said delimited space 38 may be provided with sealing members 37 enabling spiraling circulation within the support body 3 which further contributes to said acquiring of an even temperature without any temperature gradients. The sealing members 37 may for instance form a structure between the inner surface of the support base tube 30 and the exterior surface of the inner body 32 arranged to guide the passing flow of tempering liquid through the delimited space 38. For example such structure may be in the form of a helix extending along the support base 30 surface arranged to enable said spiraling circulation. According to one embodiment the sealing members 37 comprise O-ring members arranged around the circumferential inner surface of the support base tube 30 to form said helix surface structure leading to that a passing flow of tempering medium will be urged to circulate around the tube 30 while passing through the support unit 3.
Also in
In the embodiment illustrated in
Preferably the thickness t of the distribution pipe 62 wall is even around the pipe circumference, preferably between 5-30 mm, even more preferred between 10-20 mm. In a preferred embodiment the wall thickness t is at least large enough for allowing fastening of said holding body 56 which, as previously described, may be attached onto the supply unit 6 by means of a groove 63 at the surface of the distribution pipe 62.
Mixture of a fine plate-like mineral, typically clay or particulate calcium carbonate; coloring agents, typically titanium dioxide for a white sheet; and a binder which may be of the organic type or of a synthetic composition. Another type of coating medium may be an aqueous solution comprising e.g. starch used in sizing applications.
As will be understood by those skilled in the present field of art, numerous changes and modifications may be made to the above described and other embodiments of the present invention, without departing from its scope as defined in the appending claims. For example a metering rod can be used instead of the metering element 7.
It is understood that the objects of the present invention set forth above, among those made apparent by the detailed description, shall be interpreted as illustrative and not in a limiting sense. Within the scope of the following claims the set-up of various alterations of the present invention may be possible, for instance that said holding body 56 may be attached onto the supply unit 6 via an interconnecting member (not shown) that may be attached onto the distribution pipe 62 surface, e.g. by means of screwing. Further it is evident for the skilled person that many other forms (than tubular) and material (than low alloy steel) may be used to design the support body 3, e.g. in the form of traditional beams, e.g. I-beam, etc. and by using other materials, e.g. plain carbon steel (with or without lining), polymeric materials (e.g. with reinforcement), concrete (e.g. with reinforcement), etc.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1150194-7 | Mar 2011 | SE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/SE12/50243 | 3/3/2012 | WO | 00 | 10/4/2013 |
