EP2512692A1

EP2512692A1 - Curtain application mechanism

Info

Publication number: EP2512692A1
Application number: EP10793209A
Authority: EP
Inventors: Christoph Henninger
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2009-12-16
Filing date: 2010-12-10
Publication date: 2012-10-24
Also published as: WO2011073094A1; CN102655947A; DE102009054737A1

Abstract

The invention relates to a curtain application mechanism (1) for coating a running paper, cardboard or other fiber material web (2), comprising a curtain application head (1) disposed above the fiber material web (2) and extending substantially across the width (BB) of the fiber material web (2) for dispensing at least one liquid to paste-like application medium in the form of a single or multiple layer curtain (5) that falls down onto the fiber material web (2) substantially due to gravity at a desired application width (AB), wherein a curtain holder (6) is provided at least on one side edge (5a, 5b) of the curtain (5) extending in the transverse direction (QD) or the longitudinal direction (MD) of the application mechanism (1) for guiding the curtain (5) at least over a portion of the falling path (FW) thereof. According to the invention, the curtain holder (6) is associated with a protective element (7), wherein the protective element (7) is upstream of the curtain holder (6) as seen in the running direction (L) of the fiber material web (2).

Description

Curtain application work

The invention relates to a curtain coater for coating a running paper, board or other fibrous web, comprising a curtain applicator head arranged above the fibrous web and extending substantially across the width of the fibrous web for dispensing at least one liquid to pasty application medium in the form of a curtain single-layer or multi-layered curtain, which falls down to the desired width on the fibrous web substantially in accordance with gravity, wherein a curtain holder is provided on at least one side edge of the curtain extending transversely or longitudinally of the applicator head for guiding the curtain over at least a portion of its length Fall way away. A generic curtain applicator is known from DE -A1 102 32 949. It was proposed that the curtain delivered by the curtain applicator be stabilized or guided by means of curtain holders.

With the known curtain applicators both a single coating layer and at the same time several layers are deliverable. An embodiment of a curtain applicator, which also has curtain holder (here referred to as edge strip) is described and illustrated inter alia in the post-published DE 10 2008 040 409. This embodiment according to the figure 1 is referred to in professional circles as "Slide Die", ie Gleitschichtdüse. This so-called sliding layer nozzle contains at least two application medium chambers from which the medium in each case reaches a sliding surface of the sliding layer nozzle via a feed gap, which in turn merges in each case into a slot-shaped outlet nozzle. The application medium emerging from the at least two outlet nozzles arranged in parallel one behind the other overlaps one another. At a tear-off edge or also as a detachment line to be designated edge of the nozzle, this multilayer separates and falls down as a multilayer curtain in a set fall path. The fall path can either be up to one in the curtain in pushed guide plate or even from the guide plate to the substrate to be coated or to the surface of the current fibrous web rich. Often the fall path extends from the trailing edge to the substrate to be coated or to the surface of the moving fibrous web.

The fall path in height approximately corresponding edge strips are often adjustable in the width direction of the curtain, ie in the transverse direction of the commissioned work or application head. However, other embodiments of applicator heads are known in which a slot die for producing a single-layer application or multiple slot dies for delivering a multiple layer down toward the underlying fibrous web. In this case, the tear-off edge is formed by one of the slot die lips or, in a variant, by the end of a sliding face arranged between dispensing nozzle and counter surface or fibrous web. Reference is made to the already mentioned DE ... 409, where in the local figure 3 a single-layer order is shown and described. In addition, reference is made to the subsequently published DE 10 2007 000 778, in which a curtain multilayer coating is disclosed. Also in the latter invention, curtain holders or edge elements are provided, which are movable in the machine direction MD.

In the case of single-layer as well as multi-layer application with the curtain coater, the coating width can be equal to or less than the width of the fibrous web, which is referred to as the "inboard" method.

In the case of the so-called "overboard" method, on the other hand, the curtain width is greater than the width of the fibrous web and the curtain edges falling beyond the web edges are collected. Especially in the inboard driving style curtain holder, as they are disclosed in the first-mentioned document, necessary. These curtain holders guide the curtain, which is often approx. 200m long, close to the fibrous web. In most cases, they are arranged in pairs in parallel. That is, such a curtain holder is located on the so-called leader side and a curtain holder opposite on the so-called drive side of the coating machine or the commissioned work.

This in-board driving style is becoming increasingly important, especially because paper manufacturers want an uncoated edge. Disadvantage of today's edge guides or curtain holder is their long narrow design. In addition, they have functional parts, which are often provided with adjustment mechanisms.

When used under "harsh" industrial conditions, particularly in board making, high impact pulses occur in the case of web breaks resulting from the high basis weights or multiple layers of the web and can destroy the said curtain holders (which may also be used as edge guides or edge restrictors, edge guides, etc.) be referred to similarly).

In the case of web breaks, fiberballs are usually formed, which, in combination with ever-increasing machine speeds, likewise or additionally cause a destruction of the curtain holders. Often there is also an accidental contact with the curtain holder, for example, during cleaning, whereby the curtain holder can be damaged. It is therefore an object of the invention to provide a curtain applicator, which no longer has the disadvantages of the prior art.

The object of the invention is achieved with a curtain applicator with the features of claim 1.

According to the invention it is provided that the curtain holder is associated with a protective element, wherein the protective element in the running direction of the fibrous web seen upstream of the curtain holder.

It is expedient if the protective element extends with its side facing the curtain holder to near the surface of the moving fibrous web. Between the protective element and the running web a distance of approx. 1 - 10mm should be kept. The protective element may be formed as a stable rod, but also as a plate. As a solid component, it acts as it were as a crash protection or bumper especially against incoming and / or building scraps of paper in the event of a web break. As a result, the known curtain holder in "rough" industrial use can not be damaged or destroyed.

The protective element (that is, each curtain holder is associated with at least one protective element) extends in the vertical direction above the web, at least partially covering the curtain holder, but also covering it. It can also be shorter and narrower than the curtain holder.

It should be mentioned that in the order area, ie where the curtain impinges on the surface of the fibrous web, the web can be guided both horizontally, but also rising or falling. The web can run on a curtain but also supported on a roller. The applicator according to the invention is therefore very flexible.

In most cases, the curtain holders are arranged in pairs. In this case, there is such a curtain holder on the so-called leader and a curtain holder on the so-called drive side of the coating machine. Therefore, it is advantageous if the protective element is also arranged once on the driver side and once on the drive side of the machine or respectively associated with the curtain holder in the upstream direction -related to the direction of the fibrous web.

In the following, therefore, refer to the appropriate embodiments also on paired protective elements. In a development of the invention it can be provided that the protective element is arranged statically. It is possible that the protective element is attached to a wall of the curtain applicator head. For example, the frontal wall, or a side wall, but also the underside of the applicator head come into consideration. In principle, however, other supporting or supporting elements of the commissioned work, such as the supporting machine frame may be selected for the attachment of the protective element. In the latter example, independence from any Abschwenkbewegungen other assemblies and a particularly high stability is achieved.

In addition, the protective element (s) may also be attached to an existing so-called aircut, i. Air boundary layer fighting device to be attached. This device is always located in front of the falling curtain during operation of the machine or the commissioned work and therefore very suitable for the arrangement of the protective elements.

In the event that the curtain holder is made adjustable depending on the desired application width in the transverse direction, and the protective element should be adjustable in this direction. It can be achieved with any order widths always the desired protection of sensitive components.

It is also advantageous if the protective element is movable in the vertical direction on the fibrous web. This is done in such a way that in the case of demolition of the web, the protective element can deflect the web downwards. It is particularly advantageous if this is automated. As a result, the curtain holder and other complicated built commissioned components are not "wrapped" by the fibrous web and / or damaged.

As a possibility for movement of the protective element is both a manual movement and movements via actuators, such as pneumatic cylinders into consideration. The movements can, as I said, automate. In certain cases, it may also be expedient if the protective element is movable together with the curtain holder. This saves additional components for individual movements. In a further variant it can be provided that the protective element in the running direction of the fibrous web or in the machine direction, on the curtain holder, is movable. This can be done until both components abut each other. Together they create a stable "bulwark" against the incoming fibrous web in the event of demolition, so that the web can be very effectively diverted or deflected and the curtain holder is protected against damage or destruction.

The protective element itself may, for example, have a quadrangular, oval, triangular or polygonal cross section. The material used for the protective element is mainly steel or stainless steel. The protective element can also be made of a lightweight material, such as aluminum, a composite material or plastic or partially clad.

An advantage in terms of reducing the susceptibility to fouling is when the protective element is provided with a non-stick coating, such as PTFE.

A further advantageous embodiment of the protective element is obtained when the protective element is double-walled or provided with channels. This makes it possible for a coolant, for example cooling water, to flow through the protective element. Deposits on the surface of the protective element can thus be avoided.

The commissioned work with the at least one curtain holder and the associated protective element according to the invention can be embodied both in the form of a sliding layer nozzle (slide die) and in the form of a slot die or in the form of a twin or tandem die. With these named commissioned works is like if desired, a single-layer or multi-layered curtain can be produced, depending on how many feed gaps and discharge nozzles of the applicator unit are to be subjected to corresponding coating media of the same type or also different in rheology or composition.

In the context of the invention, preference is given to a single-layer or multi-layer curtain which is narrower than the width of the fibrous web.

The invention will be explained in more detail with reference to an embodiment.

In a schematic representation:

FIG. 1: a schematic representation of the curtain according to the invention

Auftragwerkes in the side view

Figure 2: a schematic and compared to Figure 1 rotated by 90 °

Representation of a side region of the invention

Curtain applicator of Figure 1 in plan view with a curtain holder defining a curtain width which is smaller than the web width (inboard),

Figure 3: a schematic cross-sectional view of the protective elements according to the invention

Figures 4 and 5: embodiments of the representation shown in Figure 2

In the figures, the same components are provided with the same reference numerals.

FIG. 1 shows a curtain applicator 1 for coating a running paper, board or other fibrous web 2 with a liquid to pasty application medium in a side view. The curtain applicator 1 includes, in addition to some not shown here units such as air boundary layer control device, start-stop-Auffangeinrichtungen or -Tannen, measuring devices, supply lines, etc. a above the fibrous web 2 and spaced from her and only roughly indicated curtain application head 3. This application head 3 is formed in the example as a so-called slot (slot). The application head 3 has a tear-off edge 4, which is formed by the inner edges of a nozzle outlet gap not shown here. From this trailing edge 4, the application medium delivered by the application head 3 - for example pigment-containing coating color - passes as curtain 5, essentially following gravity, in the desired application width AB to the fibrous web 2 moving underneath in the machine direction MD or running direction L. The fibrous web 2 is in the example a board web having a basis weight of about 180 to 550 g / m ² .

In the figure 1, this curtain is shown only in dashed lines, since it is covered by curtain holders 6 in the side view. These curtain holders 6 are arranged on at least one side edge 5a and / or 5b of the curtain 5 extending in the transverse direction QD (see the following figure 2).

Such a curtain holder 6 extends in the vertical direction over the fall path FW of the curtain 5 and extends approximately from the exit slit or from the tear-off edge 4 to near the surface of the fibrous web 2.

The curtain holder 6 serves in principle to give the curtain 5 formed in the transverse direction QD the necessary support and stability and to prevent the curtain from being inserted. This significantly increases the order quality. As can also be seen in FIG. 1, the curtain holder 3 is assigned a protective element 7. That is, it is seen in the direction L of the fibrous web 2 upstream of the curtain holder 6 and arranged upstream.

In the example shown, the protective element 7 is fastened to a side wall 8 of the curtain application head 3. The protective element 7 is movable downwards in the vertical direction, as arrow V1 shows. Thus, in the case of the demolition, the board web 2 shown here can be deflected downwards, see dashed lines 2 '. As a result, the curtain holder 6 from damage by the incoming train or Paper scraps P protected.

The protective element 7 extends, as shown in Figure 1, in the vertical direction as well as the curtain holder 6 almost to the surface of the moving fibrous web 2. However, it should a gap in the order of Imm to 10mnn remain to the web surface. In the example shown, the protective element 7, with its side surface 7.1 facing the curtain holder 6, essentially covers the curtain holder 6 located behind it and is thus capable of acting as a "bumper", so that the curtain holders 6 are no longer damaged or even damaged in rough industrial use destroyed.

As can be seen in FIG. 2, a representation of the plan view of the applicator unit 1 rotated by 90 ° with respect to FIG. 1, the curtain applicator head 3 extends in the transverse direction QD and extends here across the width BB of the fibrous web 2. For reasons of clarity, however, only the left side edge region of the fibrous web 2 is shown in FIG. 2, in the example it is the leader side FS. The opposite drive side TS is only hinted at.

Incidentally, the application head 3 can be designed both for a multi-layer application and for a single-layer application.

The present curtain holder 6 defines a width of the curtain 5 and thus an application width AB on the fibrous web 2, which is less than the web width BB in the example. Therefore, the operation of the commissioned work is referred to as inboard-driving, in which an uncoated edge Ru remains on the fibrous web 2.

The curtain holder 6 serves to guide and also limit the format of the usually about 200 mm long single or multilayer curtain 7 at its side edges 5a and 5b in the fall path FW between the trailing edge 4 and the surface of the fibrous web. 2

The curtain holder 6 is in dependence on the desired application width AB in Width direction of the curtain 5 and in the transverse direction QD adjustable (see arrow V2), as well as in the transverse direction QD, the protective element 7 is adjustable, as indicated by the horizontal arrows V3. Incidentally, the protective element 7 is manually movable, but can also be moved over a not drawn with actuator, such as pneumatic cylinder, swivel cylinder, etc. In principle, an automated movement is also conceivable.

A coordinated with the curtain holder 6 movement of the protective element 7 is conceivable.

FIG. 3 shows possible embodiments of the cross-sectional shapes of the protective element 7 as follows:

Figure a) shows a quadrangular shape,

Figure b) a circular or oval shape,

Figure c) a semicircular shape,

Figure d) an isosceles triangular shape

Figure e) a right triangular shape. The curves and corners, indicated as surface 7.2 in FIG. 3, point in the transverse direction QD towards the opposite protective element on the other side of the web.

As a material for the protective element 7 stainless steel is provided in the example.

FIGS. 4 and 5 are intended to indicate that, for example, the protective element 7 can be moved in the direction of the curtain holder 6. As can be seen in the two figures with the adjustment arrow V4, the protective elements 7 and / or the curtain holder 6 have already been moved so far relative to each other that both components 6 and 7 adjoin one another. The rounded shape shown in FIG. 4 and the triangular shape for the protective element 7 selected in FIG. 5 can very effectively act against the force and the mass of the incoming fibrous web 2 in the case of demolition. LIST OF REFERENCE NUMBERS

1 curtain commissioned work

2 fibrous web

3 curtain application head

4 outlet gap or tear-off edge

5 curtain

5a, 5b side edge of the curtain

6 curtain holder

7 protective element

7.1, 7.2 side surface

AB order width

BB web width

L web running direction

MD machine direction

QD transverse direction

FS guide page

FW fall way

TS drive side

Ru uncoated railway edge

V1, V2, V3, V4 adjustment arrow

Claims

claims

1 . Curtain coater (1) for coating a running paper, board or other fibrous web (2), comprising a curtain applicator head (1) arranged above the fibrous web (2) and extending substantially across the width (BB) of the fibrous web (2) ) for dispensing at least one liquid to pasty application medium in the form of a monolayer or multi-layer curtain (5) substantially following gravity in the desired application width (AB) on the fibrous web (2) falls, wherein at least one side edge (5a, 5b ) of the curtain (5) extending in the transverse direction (QD) or in the longitudinal direction of the applicator (1), a curtain holder (6) is provided for guiding the curtain (5) over at least a part of its fall path (FW);

characterized in that

the curtain holder (6) is associated with a protective element (7), wherein the protective element (7) seen in the running direction (L) of the fibrous web (2), the curtain holder (6) is arranged upstream.

2. curtain applicator according to claim 1,

characterized in that

the protective element (7) is arranged such that it extends approximately to the surface of the moving fibrous web (2) and at least partially covers the curtain holder (6).

3. curtain applicator according to claim 1 or 2,

characterized in that

the protective element (7) is arranged statically.

4. curtain applicator according to at least one of the preceding claims, characterized in that

the protective element (7) on a wall of the curtain application head (3) is arranged.

5. curtain applicator according to at least one of the preceding claims, characterized in that

the protective element (7) and the curtain holder (6) are adjustable as a function of the desired application width in the transverse direction (QD).

6. curtain applicator according to at least one of the preceding claims, characterized in that the

Protective element (7) in the vertical direction, in particular in the direction of the fibrous web (2) is movable.

7. curtain applicator according to at least one of the preceding claims, characterized in that

the protective element (7) is manually movable.

8. curtain applicator according to at least one of the preceding claims, characterized in that

the protective element (7) via an actuator, such as pneumatic cylinder, is movable.

9. curtain applicator according to at least one of the preceding claims, characterized in that

the protective element (7) can be moved by automated means.

10. curtain applicator according to at least one of the preceding claims, characterized in that

the protective element (7) is coordinated with the curtain holder (6) is movable.

1 1. Curtain coater according to at least one of the preceding claims, characterized in that

the protective element (7) is movable in the direction of the curtain holder (6).

12. curtain applicator according to at least one of the preceding claims, characterized in that

the protective element (7) has, for example, a quadrangular, circular, oval, triangular or polygonal cross-section.

13. curtain applicator unit according to at least one of the preceding claims, characterized in that

the protective element (7) is made of steel or stainless steel and / or of a lightweight material, such as aluminum, a composite material or plastic.

14. curtain applicator unit according to at least one of the preceding claims, characterized in that

the protective element (7) is provided with a non-stick coating, for example PTFE.

15. Curtain commissioned after at least one of the previous

Claims,

characterized in that

the protective element (7) is double-walled and can be acted upon with coolant.