WO2005058509A2

WO2005058509A2 - Method for single-sided or double-sided curtain application or bloom application on the surface of a running web of material, in particular paper or cardboard

Info

Publication number: WO2005058509A2
Application number: PCT/EP2004/053491
Authority: WO
Inventors: Bernd Bohnenkamp; Benjamin Méndez-Gallon; Manfred Ueberschär
Original assignee: Voith Paper Patent Gmbh
Priority date: 2003-12-18
Filing date: 2004-12-15
Publication date: 2005-06-30
Also published as: DE10359677A1; WO2005058509A3

Abstract

The invention relates to a method for the single-sided application or double-sided application of a fluid or a pasty application medium, by means of at least one machine comprising an application system, to the surface of a running web of material, in particular, paper or cardboard. According to the invention, the web of material is inserted into the machine prior to starting the application and is brought to at least an initial running speed and/or is brought to the web of material which is already inserted for running at least at the initial running speed, such that an inflow of the application medium is initiated prior to starting the application. The application system or a discharge part thereof and an associated medium collector are located in a relative collecting position or inserted therein, wherein the medium collector collects the discharged application medium and the application is started such that the application system or the discharge part and the medium collector are displaced from a relative collecting position into a relative application position wherein the application medium hits the running basecoat in the form of the curtain and/or bloom.

Description

Process for applying curtains or veils on one or both sides to the surface of a running material web, in particular made of paper or cardboard

description

The invention relates to a method for one-sided or two-sided application of a liquid or pasty application medium by means of a machine having at least one application unit to the surface of a running material web, in particular made of paper or cardboard; where the commissioned work the order medium from a

Dispensing opening arrangement, in particular slot nozzle, directly or through the mediation of at least one guide surface, in the form of a curtain or veil moving under the influence of gravity and / or under the influence of further forces, with a direct application the running surface being the surface of the material web and in the case of indirect application, the running substrate is the surface of a transfer element, preferably a transfer roller, which then transfers the application medium to the surface of the material web; wherein a medium catcher, possibly a collecting trough or collecting trough, assigned to the application work or to a delivery part of the order work having the delivery opening arrangement, is used in connection with starting or / and ending the application or / and in

Interrupt business interruption phases from the dispensing opening arrangement dispensed.

The invention particularly relates to an embodiment of this method in connection with starting or / and ending the application or / and with business interruption phases.

Machines for one-sided or two-sided application of a liquid or pasty application medium, which have at least one application unit for application have on the surface of a running material web, space restrictions in the running direction and height direction must often suffice. In particular, a limited installation space is available under the "curtain nozzle" that is usually provided. This is aggravated when media with a high solids content, for example up to 45% and with high viscosities, for example greater than 500 mPas, have to be collected and removed by the respective medium collector , because such a medium requires a sufficient gradient for a safe drainage. The provision of a sufficient gradient can be problematic, in particular in view of the available installation space, if over a large working width, ie over wide material webs, for example with a width of 3 meters or wider, the application medium is to be removed.

In the case of direct application, the installation space situation can be somewhat mitigated by applying to a material web section that rises or falls in the running direction and that the application medium is at least initially discharged with or against the web running direction. Nevertheless, when designing the machine, an attempt will usually be made to make optimum use of the available installation space, that is to say to arrange the various components closely together. Insofar as components are adjusted absolutely or relatively to one another in relation to the starting, stopping or interrupting of the application, the task arises of coordinating the adjusting processes favorably, so that no additional installation space has to be kept free to ensure the adjustability, or the additional space for this space to be kept free is at least relatively small.

Furthermore, there is generally the task of starting and stopping the application or interrupting the application in such a way that

Contamination of the machine by the application medium can be avoided, that material web lengths of poor order quality are avoided or are at least minimized and that high order quality is generally ensured in continuous operation.

In order to at least partially solve at least one of the mentioned tasks, it is proposed with regard to the method mentioned at the outset that the material web is drawn into the machine before the application is started and at least brought to an initial running speed or the material web that has already been drawn in is at least made to run to the initial running speed that before the start of the application an inflow of application medium to the dispensing opening arrangement is switched on, whereby the application unit or the dispensing part on the one hand and the medium catcher on the other hand are in a relative catch position or are brought into this position, in which the medium catcher from the Delivery opening arrangement fields delivered order medium; and that the application is started by moving the application work or the dispensing part on the one hand and the medium catcher on the other hand from the relative catch position to a relative order position in which the application medium dispensed from the dispensing opening arrangement meets the running surface in the form of the curtain or veil.

A distinction must be made between online application and coating machines and offline application and coating machines with regard to drawing in and bringing the material web into operation. In the case of an online coating machine which is part of a paper machine producing the material web, the so-called “web feeding” takes place approximately at operating speed. In the case of an offline machine, however, the web can be drawn in comparatively slowly, at a significantly lower speed than the production speed.

Since in an online machine the web speed is essentially predetermined by the speed at which the material web is produced, that is, it is emitted from the manufacturing section of the machine there is practically no scope for the web speed at which application actually begins. It is different with an offline machine. One can start the application on the edge of the material at a running speed, the mentioned "initial running speed", which is lower than that

Operating run speed or production run speed is. However, it is also entirely possible to start the application at a running speed of the material web which corresponds to the operating running speed or production running speed. Furthermore, it is also possible to first bring the material web to a greater initial running speed than the operating running speed, then to start the application and then to lower the running speed again to the operating running speed.

Because, according to the invention, the inflow of application medium to the dispensing opening arrangement is first switched on and the resulting curtain or veil is caught first by the medium catcher, it is possible to stabilize the curtain or veil sufficiently and, if necessary, to pass through any air bubbles that may initially occur wait until it is actually applied to the material web. This means that a high order quality (coating quality) can be achieved right from the start of the application.

At least one thermal drying device is regularly used to dry the material web provided with the application medium. In this context, it is proposed that the drying device be switched on before starting the application, in such a way that it is adjusted to the drawing in or to the running of the material web, that the drying device only achieves its operating drying performance when the material web has at least a minimum running speed, possibly the initial running speed, running. For high order quality, the machine will generally have a device for influencing or reducing or removing an air boundary layer which is carried along by the material web and which acts on the material web in front of the application point. It can be provided that before or after the start of the application, such a device, which is present in the direction of travel of the material web for influencing or reducing or removing an air boundary layer carried along by the material web, in the following

Air boundary layer influencing device called, activated and / or brought into an operating position. It is certainly possible that the air boundary layer influencing device is constantly in its operating position or cannot be adjusted at all between different positions, so that this device can only be activated and deactivated, that is to say switched on and off.

A preferred embodiment is characterized in that the web is first listed (drawn in or made to run), then the device mentioned is brought into operation and the ink application or medium application is then started.

An air-cut, for example, can be used as the addressed device. This can be permanently installed and thus be in the operating position from the start. The function of the air-cut can be started, for example, by one or more blowing nozzles to reduce the air boundary layer activated, or / and that a suction device is switched on to reduce the air boundary layer, or / and that one or more corona electrodes are switched on to reduce the air boundary layer, or / and that one or more charging electrodes are switched on to reduce the air boundary layer, or / and that a mechanical air boundary layer scraper is pivoted or started, to name just a few examples. Another possibility is that the Air-Cut is adjustable, but is already in the operating position when the web is being run. The prerequisite is that there is sufficient space for the web performance. The function of the air cut can then be started in the manner mentioned above which mentions various possibilities.

Furthermore, it may be that, when the air cut is in the operating position, there is insufficient space for threading and for the medium to catch the application medium in the catch position. In this case, the air cut is brought into the operating position only at a later point in time or in the course of other processes, for example translationally or in the manner of a pivoting. In addition, the measures mentioned above with regard to various possibilities for activating the air cut may be necessary.

If an adjustment of the air boundary layer influencing device (the so-called “air cut”) is provided, it is preferred that before starting the application or before starting the adjustment to the order position with an adjustment of the

Air boundary layer influencing device is at least started from a rest position into the operating position. In a further development, it is proposed that the air boundary layer influencing device reaches the operating position before starting the application or before the start of the adjustment to the application position.

However, as already implicitly mentioned, it is also entirely possible that after starting the application or after the start of the adjustment to the order position, the air boundary layer influencing device is adjusted from a rest position to the operating position. In general, it can be provided that the air boundary layer influencing device reaches the operating position after starting the application or after the start of the adjustment to the order position.

According to an expedient embodiment of the method, it is provided that the application work or the delivery part and / or the medium catcher reaches an operating position assumed in the relative application position before the air boundary layer influencing device assumes its operating position. Alternatively, it can be provided that the application unit or the delivery part and / or the medium catcher reaches an operating position assumed in the relative application position after the air boundary layer influencing device assumes its operating position. It should be noted that the application can begin before the application work or the delivery part or before the medium catcher has reached the end position or end positions corresponding to the order. Application can take place after the start of the

'' Start the adjustment when the components mentioned are adjusted so far relative to each other that the curtain or veil is no longer caught by the medium catcher.

A power supply to the air boundary layer influencing device or / and a gas supply to the air boundary layer influencing device or / and a gas extraction of the air boundary layer influencing device is preferably switched on before the application is started.

Problems with installation space can be dealt with better or better if a vertical adjustability for the dispensing part (in particular the so-called dispensing nozzle) is provided. In particular, namely in the case of very wide machines, the medium catcher has, in particular, the so-called Starting trough, often of great height. On the other hand, the distance of the dispensing nozzle above the web is usually specified technologically, since this determines the height of the curtain or veil. However, the medium catcher must be able to move under the dispensing nozzle relative to it without a collision. For this purpose, it can be provided that the dispensing nozzle is moved from its vertical operating position into a higher standby position in order to enable the medium catcher to pass through the dispensing nozzle or to take up the collecting position relative to it.

In general, it can be provided that the dispensing part is adjusted between a higher standby vertical position and a lower vertical operating position in connection with the starting or / and ending of the application or / and with the start or / and end of an operational interruption phase. In this context, it is primarily considered that the dispensing part is moved to the standby vertical position in the course or beforehand of an adjustment of the medium catcher and the dispensing part to the receiving position or / and that the dispensing part is adjusted in the course or subsequently of an adjustment of the medium catcher and the Dispensing part is moved into the catch position in the order position in the operational vertical position. It can be provided that the delivery of the application medium to the running surface begins in the form of a curtain or veil before the delivery part has reached the vertical operating position. The coating process can therefore be started before the dispensing nozzle is in the operating position. For example, the dispensing nozzle only moves into the operating position, the operating vertical position mentioned, after the coating process has been started. Accordingly, the dispensing nozzle must be raised again before the medium catcher can again assume the relative catch position to the nozzle or the nozzle and the medium catcher can be adjusted accordingly relative to one another. Depending on the available space and realizable relative movements, it is also possible that the delivery of the application medium to the running surface begins in the form of a curtain or veil after the delivery part has reached the vertical operating position.

It has already been pointed out that the delivery of the application medium to the running surface in the form of a curtain or veil begins before the application or the delivery part, on the one hand, and the medium receiver, on the other hand, have reached their relative order.

As a rule, it will be expedient if the running speed of the material web is increased further after starting the application until a

Operating speed is reached. Furthermore, one can advantageously provide that after the start of the application of the inflow

Application medium to the dispensing opening arrangement is continuously increased until a desired order weight corresponding to a ¹ relating to a / the operating running speed of the material web

Operating inflow is set. In this context, it is further developed that the running speed of the material web and the inflow of application medium are increased in a coordinated manner in order to avoid an initial excess order and / or to keep the initial order weight in a target range or the initial order weight to the desired order weight at least approximate.

When the coating process is started, the volume flow of the application medium can therefore be less than the volume flow required for

Reaching the target weight at operating speed is necessary. After starting the coating process, the volume flow can then be turned off the nozzle is continuously increased until the application weight is reached at operating speed. In this context, reference is made to design options of the machine or the process, which is filed in the German patent application filed on October 22, 2003, official file number 103 49 119.8, with the title: “Curtain application process and curtain application machine for application to a running material web "are included, the disclosure of which is fully incorporated by reference into the disclosure of the present application.

According to another aspect, it is further developed that, in the case of direct application, at least one shielding element arranged above the material web in the area of one of its edge strips for catching the application medium for the purpose of shielding the edge strip against medium application in connection with starting application from a standby position into the edge strip the shielding shielding position is adjusted and the shielding position is only reached when the application work or the delivery part, on the one hand, and the medium catcher, on the other hand, have been adjusted from the catch position towards the order position, preferably have reached the order position. The relative adjustment of the dispensing nozzle and the medium catcher to one another is not hindered by the shielding element or the shielding elements.

For other auxiliary elements, it is preferred that they are brought into their operating position before the start of the application. In this context, for example, auxiliary elements such as those described and shown in DE 100 47 167 A1 are considered, the disclosure of which is fully incorporated by reference into the disclosure of the present application. Such auxiliary elements also fulfill their function if they are only brought into their operating positions immediately after the start of the confirmation process. According to the above, it is preferred that, in the case of direct application, at least one deflecting element deflecting an edge strip of the material web from the material web plane thereof beforehand or in the course of starting application from a ready position to a deflection position acting on the edge strip in the sense of deflection becomes.

It can be provided that the medium catcher is arranged in a stationary manner and that the application work or the delivery part is adjusted between a first position corresponding to the order position and a second position corresponding to the catch position.

Another possibility is that the application work or the delivery part is arranged stationary and that the medium catcher is adjusted between a first position corresponding to the order position and a second position corresponding to the catch position.

The medium catcher can expediently be designed as a collecting trough or gutter. The * medium catcher mentioned above can also be only a component of a medium collecting and discharging arrangement. For example, the preferably flat medium catcher can be adjustably arranged on a stationary receiving trough or receiving channel and can be adjusted between a first position corresponding to the order position and a second position corresponding to the catch position.

In the context mentioned, it should also be pointed out that it can make sense if, in the course of the relative adjustment of the commissioned work or the dispensing part on the one hand and the medium catcher on the other hand, both the commissioned work or the dispensing position as well as the Medium catcher between a respective first position and one respective second position can be adjusted. Problems with installation space can thus be dealt with particularly expediently.

One could consider stopping or stopping application by simply stopping the supply of application medium to the dispensing opening arrangement. However, this can result in an undefined loading of the material web with the application medium. In contrast, it is preferred that the application is interrupted or ended by moving the application work or the dispensing part on the one hand and the medium catcher on the other hand from the relative order position to the relative catch position.

It can be provided that the medium catcher has at least one receiving and releasable part which can be detachably attached to a medium catcher main part and which, when the application is started, the curtain or veil by relative adjustment together with the medium catcher main part to the curtain or veil of one over the running surface or an edge extending over the running surface for movement towards the running surface or / and which when interrupting or ending the application by relative adjustment together with the medium catcher main part to the curtain or veil with a / the enters the curtain or veil over the running surface or with one or more edges and at least initially receives it and keeps it from the running surface. In this way, two competing conditions can easily be fulfilled simultaneously. On the one hand, it can be achieved that the curtain is released as low as possible above the running surface for starting the application or for interrupting or ending the application. Local excess application due to a curtain contracting due to the surface tension can thus be avoided. On the other hand, in Corresponding design of the medium catcher main part, a large flow of application medium is collected, held and discharged, for example by providing a sufficiently high boundary wall for the receiving and releasing part. It is possible to provide that the application medium caught on the receiving and release part in the course of the interaction with the curtain simply remains there and is not discharged to the medium catcher main part or to the edge of the web. In this context, it is further developed that before the start of the application the receiving and release part or at least one receiving and release part of several assigned reception and release parts is attached to the medium catcher and / or before the start of the application or after the start of the Applying while the job is in progress, before the termination or interruption of the job, the receiving and releasing part or the receiving medium holding or adhering to the ordering medium, and the or at least another receiving and releasing part, in particular cleaned or freed from the order medium, is attached to the medium receiver again ,

With regard to the interruption or termination of the order, it is proposed as particularly preferred that, in connection with the interruption or termination of the order, the components adjusted in connection with the start of the order are returned to their original positions or positions assumed before the start of the order , In this context, it is primarily thought that - insofar as a coordinated adjustment of several components is provided in connection with the start of the application - the adjustment of the components to the respective original position or position takes place accordingly, but in reverse order. The invention is explained in more detail below on the basis of exemplary embodiments with reference to the figures, exemplary embodiments and components used therein.

Fig. 1 shows an example of a coating machine for double-sided application to a web of paper or cardboard, and serves to explain the application of an embodiment of the method according to the invention.

2 illustrates in the partial figures 2a) and 2b) a possibility for collecting the application medium by means of an adjustable medium catcher in connection with starting, interrupting or ending the curtain application.

3 shows a further possibility for collecting the application medium by means of an adjustable medium catcher in connection with starting, interrupting or ending the curtain application.

Fig. 4-7 show further expedient design options of the coating machine of Fig. 1 relating to the medium catcher and its function when starting, interrupting and ending the curtain application.

8 shows a further example of a coating machine, to which an embodiment of the method according to the invention can be applied.

9 shows a further example of a coating machine to which an exemplary embodiment of the method according to the invention can be applied. 10 shows a timing diagram for various processes when starting and ending the curtain application by means of a curtain coating machine, and serves to explain an exemplary embodiment of the invention.

Fig. 1 shows schematically two curtain applicators 10-1 and 10-2 in a coating machine, which are used for direct curtain application on the two sides of a material web 12 made of paper or cardboard. The material web guided over a plurality of deflection rollers 14 or 14 ', 16 and 18, which according to FIG. 1, for example, is fed from above to the deflection roller 14 or - alternatively - from the right to the deflection roller 14' (dashed line) first runs below a web Curtain applicator head 18-1 of the first curtain applicator 10-1 through, for coating the first surface of the material web. The curtain applicator head has in the usual way a distribution chamber running in the transverse direction to the running direction of the material web and a slot nozzle running in the same direction, which releases the curtain or veil from the application medium, in particular coating color. The curtain or curtain 24-1 strikes a section 12-1 of the material web 12 that slopes in the running direction and is therefore inclined with respect to the horizontal, which is held by the deflection rollers 14 or 16 or 14 'and 16.

When the coating machine is started up or in the event of brief interruptions in operation, for example in the event of a web break, and in connection with the end of the application, the application medium curtain or curtain is caught by a movably mounted medium catcher 26-1, which is in a catch position in FIG. 1 is shown in which he catches the curtain 24-1. The curtain is shown in dashed lines but extended to the material web section 12-1 to show the order position. FIG. 2 shows the area of the curtain applicator 10-1 for both positions of the medium catcher 26-1, namely in FIG. 2a) the medium catcher 26-1 in the catch position 1 and in FIG. 2b), the medium catcher 26-1 in an order position in which it is shifted in the direction of travel of the material web with respect to the catch position, so that the curtain 24-1 meets the inclined material web section 12-1.

The medium catcher 26-1 consists of a collecting plate 40-1, which extends over the entire width of the curtain in the direction transverse to the running direction of the material web, which extends essentially parallel to the inclined material web section 12-1, that is to say is likewise inclined with respect to the horizontal, and one adjoining receiving and discharge channel 42-1, which extends in the transverse direction to the material web running direction and has a gradient in this direction in order to discharge the application medium supplied to it by the collecting plate in the transverse direction. The collected application medium is thus discharged on the collecting plate 40-1 first in the direction of travel of the material web and then in the groove 42-1 in the direction transverse to the direction of travel. The receiving and discharge trough 42-1 is arranged next to a vertically running material web section 12-2 or the web deflector holding it and formed by the deflecting rollers 16 and 18, essentially at the same height as the deflecting roller 16, so that there is sufficient installation space in the vertical direction is available. It is therefore also possible to take up and discharge large quantities of application medium, as may be necessary, for example, in the case of very large material web widths, and a comparatively large discharge gradient can also be provided in the transverse direction to the direction of travel, as is required, for example, for highly viscous application media, in particular coating colors is. Typical coating colors for curtain application have a viscosity of 50 to 500 mPs (= cP, Centipoise) to give reference values. In contrast, highly viscous coating colors have a viscosity greater than 500 mPs (= cP, centipoise), for example up to 2000 mPs (= cP, centipoise), again in order to give only a reference value. The formation of the medium catcher corresponding to the medium catcher 26- 1 is particularly well suited for highly viscous coating colors or the medium catcher can be optimally designed for highly viscous coating colors, namely with regard to the absorption capacity of the receiving and discharge channel 42-1, with regard to the gradient of this channel in the transverse direction to the running direction of the material web and with regard to the gradient of the collecting plate 40-1 in the direction of travel of the material web.

Due to the deflection by the web deflection formed by the deflection rollers 16, 18, the other (second) material web side is now accessible from above for a medium application. In a corresponding manner, the second curtain applicator 10-2 has a curtain applicator head 18-2 which delivers a curtain 24-2 to a further material web section, designated 12-3, which in turn is inclined with respect to the horizontal and in the direction of travel Material web falls. Again, a medium catcher 26-2 is provided, which is diverted between a catch position in which the curtain 24-2 meets a catch plate 40-2 and via the catch plate and a receiving and discharge channel 42-2, and an order position, in that the curtain meets the material web section 12-3, distributable. The explanations and explanations for the catcher 26-1 with reference to FIG. 2 apply correspondingly to the catcher 26-2.

Since there is no intermediate drying between the curtain applicators, but only the web deflection, which touches the second web surface that is not coated by the first curtain applicator 18-1, the material web section 12-3 in front of the applicator head 18-2 is touching the deflection roller 18 and after the curtain application head 18-2 are held contactlessly by an air turn 44, which is part of the guide arrangement and cooperates with a further air turn 46, around the material web first through a first contactless drying device 48 and then through a second contactless drying device 50 respectively. The drying facilities 48 and 50 can be designed, for example, as infrared drying devices or hot air drying devices.

A device 19-1 or 19-2 for removing or weakening an air boundary layer carried along by the material web, for example a boundary layer suction or a boundary layer scraper, can advantageously be provided in front of the application head 18-1 or 18-2.

It should be pointed out that it is not imperative that the medium catcher 40-1 or 40-2 be adjustable and the application head 18-1 or 18-2 is stationary. Fig. 3 illustrates a variation of the coating machine, in which the respective application head, in Fig. 3 specifically the first application head 18-1 ', is adjustable between a catch position in which the curtain delivered hits the catch plate of the stationary medium catcher 26-1' (Fig. 3a), and an order position in which the curtain meets the material web section 12-1 falling in the running direction (Fig. 3b). The same can be provided for the curtain applicator head and the medium catcher of the second applicator 10-2.

It should also be pointed out that FIGS. 1 to 3 do not represent the optimal solution with regard to the arrangement of the collecting plate of the medium catcher. The collecting plate of the medium catcher, or at least its edge running in the transverse direction to the running direction of the material web, which to a certain extent cuts through the curtain when the curtain application is ended by adjusting the application head and / or the medium catcher, and which at the start of the order by correspondingly opposing adjustment of the application head or / and the medium catcher to a certain extent releases the curtain should - as a deviation from the schematic representations in FIGS. 1 to 3 - be arranged as low as possible above the material web section to be coated. Instead of adjusting the entire medium catcher, only one adjustment of a receiving plate 41-1 "'of the medium catcher can advantageously be provided, as illustrated in Fig. 4. Of the receiving plate 41-1'", which can also be appropriately described as a medium catcher (below Designation of component 26-1 "'as a" collecting trough "or the like), the collected application medium runs onto the collecting plate 40-1'" and from this into the receiving and discharge channel 42-1 '". The receiving plate 41-1 "'can be designed with a specially designed cutting edge for cutting through or releasing the curtain in order to minimize accumulation areas on application medium as a result of the curtain being contracted by the surface tension.

Other configurations of the medium catcher are conceivable. FIG. 5 shows in the partial figures 5a) and 5b) a modification of the arrangement according to FIG. 4, in which the receiving plate 41-1 is fixedly arranged on the collecting plate 40-1 and together with the medium catcher 26-1 between a collecting position and an order position is adjustable relative to the stationary application head 18-1. The receiving plate 41-1 can be detachably attached to the medium catcher 26-1, and can be detachable from the medium catcher, for example, for cleaning purposes or for replacement if necessary by an unpolluted receiving plate. The receiving plate 41-1 can also be regarded as part of the medium catcher.

6 shows in part 6a) the possibility that the receiving plate 40-1 "', which is adjustable relative to the stationary medium catcher 26-1"', does not itself release or cut through the curtain, but is equipped with a separate receiving and release part 120 , which is or is detachably arranged on the receiving plate. The receiving and releasing part 120, which can be regarded as part of the medium catcher, is, for example, on a free edge or on a free edge of the Receiving plate suspended. The receiving and release part is optimized to release the curtain when starting the application or to cut through the curtain when the application is ended or interrupted in such a way that undefined exposure of the material web to the application medium is avoided or at least minimized. In this way it can be ensured that the edge that cuts or releases the curtain is arranged very low above the surface of the material web and that the curtain does not run off or wet the surface of the medium catcher when it is cut or released, with the risk of undefined exposure to the surface of the material web with application medium, for example with dripping application medium. The design of the receiving and releasing part is such that the application medium detaches itself perfectly from an edge of the receiving and releasing part without expiration on the surface of the receiving and releasing part as a result of surface tension and adhesion effects ("teapot effect"), and that when the curtain is cut it does not hit flat surface sections of the receiving and releasing part.

To achieve these functions, it can be accepted that the receiving and releasing part receives order medium which cannot be removed from the receiving and releasing part, but remains on the receiving and releasing part until it is replaced or cleaned. As indicated in dashed lines in FIG. 6a), the receiving and releasing part in the catching position takes up a position beyond the curtain, so the curtain falls in the catching position on the receiving plate 41-1 "'and runs over this onto the collecting plate 40-1 When the receiving plate 41-1 is moved between the order position in which the curtain falls on the surface of the material web and the catch position in which the curtain falls on the receiving plate, the application medium falls So only for a short time on the receiving or release part 120, and the amount of application medium received by it can be the receiving and releasing part 120 remain. In relation to an order cycle (starting the curtain application until the end of the curtain order), it is preferred to free the receiving and release part from the collecting medium at the end of the cycle, that is to say after the receiving plate 41-1 '"has been returned to the receiving position. by removing and cleaning the receiving and releasing part from the receiving plate, or by replacing it with another receiving and releasing part without application medium.

Such a receiving and releasing part can also be arranged directly on the collecting plate 40-1 of the adjustable medium catcher 26-1 (FIG. 6) or stationary medium catcher, in order to perform the same functions there as in the example of FIG. 6a).

Fig. 7 shows schematically yet another embodiment of the medium catcher. According to FIG. 7, this has a known, spoon-like receiving and release part in cross-section, which is pivoted relative to the collecting plate 40-1 in order to be able to pick up and release the curtain very low above the surface of the material web and, on the other hand, the applied application medium to the collecting plate To let 40-1 expire. This receiving and releasing part can also be designed to be exchangeable.

6, it should be pointed out that the detachably mounted or exchangeable receiving and releasing part shown there is particularly expedient if the medium catcher is designed with boundary walls rising high above the material web surface, as in FIG. 8 and 9.

Fig. 8 shows schematically a curtain applicator 10 in a coating machine, which is used for direct curtain application on a material web 12 made of paper or cardboard. The over a pulley 14 and 16th Comprehensive guide arrangement guided material web 12 runs beneath a curtain applicator head 18 of the applicator. The curtain application head has in the usual way a distribution chamber 20 running in the transverse direction to the running direction of the material web and a slot nozzle 22 running in the same direction, which delivers the curtain or veil 24 from application medium, in particular coating color. The curtain or veil 24 meets a horizontally extending section 12 ′ of the material web 12.

When the coating machine is started up or in the event of brief interruptions in operation, for example in the event of a web break, the application medium curtain or curtain is caught by a movably mounted collecting channel 26, which is shown in solid lines in FIG. 8 in a catching position in which it Curtain 24 catches, but is optionally mechanically adjustable in an order in which it does not catch the curtain 24, so that the horizontally extending material web section 12 'is coated in the usual way. In Fig. 8 the gutter 26 is also shown in dashed lines in its order position. , -. , _s

In the usual way, the commissioned work

Application pretreatment device, for example a so-called aircut, air boundary layer scraper or an air boundary layer suction device, which is denoted by 19 and acts on the material web 12 in the region of the deflection roller 14.

In the embodiment according to FIG. 9, the medium catcher 26a is arranged in a stationary manner and integrated with the application pretreatment device 28a to form a structural unit. In order to be able to catch the application medium curtain 24 when starting up the coating machine or during brief interruptions in operation, the curtain application head 18a is between a collecting position shown in solid lines in FIG. 9, in which the curtain is caught by the medium catcher 26a, and one in FIG 9 Machine-adjustable order position shown in broken lines, in which the application head 18a applies to a material web section 12 'rising in the running direction of the material web 12. In contrast to the example in FIG. 8, the application medium collected by the medium collector is initially not discharged in the transverse direction to the direction of travel of the material web, but rather in the opposite direction to the direction of the arrow M, towards a symbolically represented medium outlet 30a or several corresponding medium outlets.

If the receiving and release part 120 were not attached to the medium catcher 26 or 26a, when the curtain was released to the material web surface in the course of starting the application and cutting the curtain to end the curtain application, the application medium would run off the outer wall of the medium catcher and drip uncontrollably onto the material web surface. This is prevented by the special design of the receiving and release part with the release and cutting edge protruding at an angle in the order in the direction of the curtain. In addition, this cutting and releasing edge is arranged significantly lower above the surface of the material web than the upper edge of the medium catcher, so that the contraction of the released curtain due to the surface tension to drips and the like is prevented or at least minimized.

The coating machines of the above examples each have a control unit (control unit 100 in FIG. 1) which controls the coating process, especially when recording the coating or when interrupting or ending the coating. In particular, the control unit 100 controls an actuator arrangement which adjusts the respective application head 18-1 or 18-2 or 18a or / and the respectively assigned medium catcher or its receiving plate in order to start the application with the curtain for delivery to the surface of the material web to release or to Complete the application to catch the curtain through the interceptor. When starting the application, a stable curtain is preferably set first while it falls onto the catcher. If a stable curtain is reached and the coating machine is otherwise in its target state (desired running speed of the material web, operating temperature of the drying devices), the control unit then adjusts the medium catcher or its receiving plate or / and the application head so that the curtain then hits the material web surface ,

In a corresponding manner, the control unit interrupts or ends the application by adjusting the medium catcher or its receiving plate and the respective application head in such a way that the curtain is caught again by the catcher.

When the curtain is released in the start phase of the application and when the curtain is cut off in the end phase of the application, accumulation areas on the application medium can arise as a result of a contraction of the curtain caused by the surface tension. In order to reduce or control their effects *, a respective coating machine, for example the coating machine of FIG. 1, can have at least one doctor device controlled by the control unit (in the case of FIG. 1, two doctor devices 102-1 and 102-2), which are brought into interaction with the material web side which is deleted by the curtain application unit 10-1 or by the curtain application unit 10-2 during a start phase of the application or during an end phase of the application. The two squeegee devices are only briefly adjusted with the material web in squeegee engagement, namely shortly before releasing the curtain to free fall on the material web surface by relocating the curtain application head and the medium catcher or its receiving plate relative to each other or just before the curtain through appropriate counter adjustment of these components the curtain is caught again by the medium catcher.

In the course of starting or interrupting or ending the application, further auxiliary components can also be activated and / or adjusted between a standby position and an operating position, for example so-called “air cuts” (see components 19-1, 19-2, 1 and 8 and 9. In this context, components that act to stabilize the material web and components that serve to provide edge strips of the material web that are free of application medium are also considered be brought into the operating position before the actual start of the application, or these components are only brought into the operating position after the actual start of the application.If necessary, a coordinated, at least partially simultaneous adjustment of several components can be provided, for example an adjustment of the air cut closer to the application point on the material web simultaneous to the adjustment of the medium catcher in the order position. 10 is a timing diagram that exemplarily shows various operations performed at the start of the application and at the end of the application in a relative timing. Partial diagram A represents the drawing in and bringing the material web up to running speed in or in a coating machine in a period from to to. Before the time ti or - as shown in FIG. 10 - after the time ti, the supply of application medium to the dispensing nozzle (application head) is started (part diagram B). The application head and the medium catcher are in the catch position (partial diagram C). In the example shown, the supply of application medium begins at time t ₃ . After a stable curtain has set in, as shown in partial diagram C, a relative adjustment of the medium catcher and the application head to the order position begins at the time. At time t is Order reached. The actual application to the surface of the material web will usually have started somewhat earlier, namely after the curtain has been released by an edge or the like of the medium catcher. During this relative adjustment or after this, a vertical adjustment of the application head can be provided, to which the partial diagram D relates. In the example, the order header is adjusted in the order from tg to tu.

Partial diagram E relates to an adjustment of the air cut, which in the example overlaps with the adjustment between the initial position and the order placement in the time t ₅ to tg. The partial diagrams F and G relate to the adjustment of other auxiliary elements in a respective operating position beforehand or overlapping with the adjustment between the initial position and the order position (times t ₂ to tβ) or. following the adjustment to the order (times t ₇ to tio). A planned termination of the application can take place in the reverse chronological order, correspondingly coordinated with one another, as shown in FIG. 10. The corresponding start and end times are denoted by t -n, t -ιo, ... t -o, which results in an assignment to the start and end times to, ti to tu when starting the application. The exchange or cleaning of a receiving and releasing part can expediently take place after the time t -, that is to say after the resetting of the catch position, but preferably only after the time t -o.

In the event of an unplanned termination of the order, for example due to a web break, deviations from the sequence shown, which serves only as an example, may be expedient or necessary.

Claims

Expectations

1. Method for one-sided or two-sided application of a liquid or pasty application medium by means of a machine having at least one application unit (10) to the surface of a running material web (12), in particular made of paper or cardboard; in which the application unit delivers the application medium from a dispensing opening arrangement, in particular a slot nozzle (22), directly or through the intermediary of at least one guide surface, in the form of a curtain or veil (24) moving under the influence of gravity and / or under the influence of further forces towards a running underground , with direct application the running substrate is the surface of the material web (12) and with indirect application the running substrate is the surface of a transfer element, preferably a transfer roller, which then transfers the application medium to the surface of the material web; wherein a medium catcher (26), possibly a collecting trough or collecting trough, associated with the commissioned work or a delivery part (18) of the commissioned work, is used in connection with the starting or / and ending of the order or / and in business interruption phases from the Dispensing opening arrangement (22) to collect dispensed order medium; characterized in that, before starting the application, the material web (12) is drawn into the machine and at least brought to an initial running speed or the material web that has already been drawn in is made to run at least to the initial running speed, that before the start of the application, an inflow of application medium to the dispensing opening arrangement (22) is switched on, the application unit or the dispensing part (18-1; 18-2; 18; 18a) on the one hand and the medium catcher (26-1; 26-2 ; 26; 26a) on the other hand, are in a relative catch position or are brought into this position, in which the medium catcher catches the order medium delivered from the dispensing opening arrangement; and that the application is started by the application unit or the delivery part (18-1; 18-2; 18; 18a) on the one hand and the medium catcher (26-1; 26-2; 26; 26a) on the other hand from the relative catch position in a relative order is placed in which the order medium delivered from the delivery opening arrangement meets the running surface in the form of the curtain or veil.

2. The method according to claim 1, characterized in that at least one thermal drying device (48, 50) is used to dry the material web provided with the application medium, and that the drying device is switched on before starting the application, so matched to the drawing in or to get the material web running so that the drying device only reaches its operational drying capacity when the material web runs at least at a minimum running speed, possibly the initial running speed.

3. The method according to claim 1 or 2, characterized in that before or after starting the application a device present in the direction of travel of the material web the device (19-1; 19-2; 19; 19a) for influencing or reducing or removing one of the air boundary layer dragged along with the material web, hereinafter called the air boundary layer influencing device, is activated and / or brought into an operating position.

4. The method according to claim 3, characterized in that before starting the application or before the start of the adjustment in the order position with an adjustment of the air boundary layer influencing device (19) from a rest position to the operating position is at least started.

5. The method according to claim 4, characterized in that the air boundary layer influencing device (19) reaches the operating position before starting the application or before the start of the adjustment in the order position.

6. The method according to claim 2, characterized in that after the start of the application or after the start of the adjustment in the order position with an adjustment of the air boundary layer influencing device (19) is started from a rest position to the operating position.

7. The method according to claim 4 or 6, characterized in that the air boundary layer influencing device ⁵ (19) reaches the operating position after starting the application or after the start of the adjustment in the order position.

8. The method according to any one of claims 4, 6 and 7, characterized in that the applicator or the delivery part (18) and / or the medium catcher reaches an operating position assumed in the relative order position before the air boundary layer influencing device (19) assumes its operating position.

9. The method according to any one of claims 4 to 7, characterized in that the order work or the delivery part (18) and / or the medium catcher one in the relative order assumed operating position reached after the air boundary layer influencing device (19) assumes its operating position.

10. The method according to any one of claims 3 to 9, characterized in that a power supply to the air boundary layer influencing device (19) and / or a gas supply to the air boundary layer influencing device (19) or / and a gas extraction of the air boundary layer influencing device (19) is switched on before the application is started ,

11. The method according to any one of claims 1 to 10, characterized in that the dispensing part (18) in connection with the start or / and termination of the application and / and with the beginning or / and end of a business interruption phase between a higher standby vertical position and a lower operating vertical position is adjusted.

12. The method according to claim 11, characterized in that the dispensing part (18) is adjusted in the course or beforehand of an adjustment of the medium catcher (26) and the dispensing part in the catch position in the ready vertical position or / and that the dispensing part (18) in During or after an adjustment of the medium catcher (26) and the delivery part into the catch position into the order position into the vertical operating position.

13. The method according to claim 12, characterized in that the delivery of the application medium to the running surface in the form of the curtain or veil begins before the delivery part (18) has reached the vertical operating position.

14. The method according to claim 12, characterized in that the delivery of the application medium to the running surface begins in the form of the curtain or veil after the delivery part (18) has reached the vertical operating position.

15. The method according to any one of claims 1 to 14, characterized in that the delivery of the application medium to the running surface in the form of the curtain or veil begins before the application or the delivery part (18), on the one hand, and the medium catcher (26 ), on the other hand, have reached their relative order.

16. The method according to any one of claims 1 to 15, characterized in that the running speed of the material web (12) after starting the application is further increased until an operating running speed is reached.

17. The method according to any one of claims 1 to 16, characterized in that after the start of the application, the inflow of application medium to the dispensing opening arrangement (22) is continuously increased until a desire related to a / the operating speed of the material web (12) - Order weight corresponding operating inflow is set.

18. The method according to claim 16 and 17, characterized in that the running speed of the material web (12) and the inflow of application medium are increased in a coordinated manner in order to avoid an initial excess order and / or to keep the initial order weight in a target range or at least approximate the initial order weight to the desired order weight.

19. The method according to any one of claims 1 to 17, characterized in that in the case of direct application, at least one shielding element arranged above the material web in the region of one of its edge strips for catching the application medium for the purpose of shielding the edge strip against medium application in connection with starting the application a standby position is shifted into a shielding position shielding the edge strip and the shielding position is only reached when the application work or the delivery part, on the one hand, and the medium catcher, on the other hand, have been moved from the catch position towards the order position, preferably have reached the order position.

20. The method according to any one of claims 1 to 19, characterized in that in the case of direct application, at least one deflecting element deflecting an edge strip of the material web from its material web plane beforehand or in the course of starting the application from a standby position to one on the edge strip in In the sense of deflection acting deflection position is adjusted.

21. The method according to any one of claims 1 to 19, characterized in that the medium catcher (26-1 "; 26a) is arranged in a stationary manner and that the application work or the dispensing part (18-1 ', 18a) between a first corresponding to the order Position and a second position corresponding to the catch position is adjusted.

22. The method according to any one of claims 1 to 19, characterized in that the application unit or the dispensing part (18-1; 18) is arranged stationary and that the medium catcher (26-1, 26- 2; 26) is adjusted between a first position corresponding to the order position and a second position corresponding to the catch position.

23. The method according to claim 22, characterized in that the medium collector (26) is designed as a collecting trough or gutter.

24. The method according to claim 22, characterized in that the preferably flat medium catcher (41-1 "') is adjustably arranged on a stationary receiving trough or receiving channel (26-1'") and between a first position corresponding to the order position and one of the Catch position corresponding second position is adjusted.

25. The method according to any one of claims 1 to 24, characterized in that in the course of the relative adjustment of the application work or the delivery part on the one hand and the medium catcher on the other hand between the order and the catch position both the order work or the delivery part and the medium catcher between one respective first position and a respective second position.

26. The method according to any one of claims 1 to 25, characterized in that the application is interrupted or terminated by the fact that the application work or the dispensing part (18-1; 18-2; 18; 18a) on the one hand and the medium catcher (26-1 ; 26-2; 26; 26a), on the other hand, are brought from the relative order position into the relative catch position.

27. The method according to any one of claims 1 to 26, characterized in that the medium catcher at least one detachably a medium catcher main part (41-1 '";26-1;26; 26a) attachable receiving and release part (41-1; 120), which when starting the application the curtain or veil by relative adjustment together with the medium catcher -Main part to the curtain or veil from an edge extending over the running surface or an edge extending over the running surface for movement towards the running surface or / and which when interrupting or ending the application by relative adjustment together with the medium catcher Main part of the curtain or veil with an edge that extends over the running surface or with an edge that extends over the running surface enters the curtain or veil and at least initially receives it and keeps it from the running surface.

28. The method according to claim 27, characterized in that the reception and release part (120) or at least one reception and release part of several assigned reception and ^» release parts is attached to the medium catcher or / and that before the start of the application of the application or after the start of the application in the ongoing order operation, before the termination or interruption of the application, the receiving and release part having the application medium holding or adhering to the application medium and removing or removing at least one other, in particular cleaned or freed from application medium, from the medium receiver Reception and release part is attached to the medium catcher again.

29. The method according to any one of claims 1 to 28, in any case according to claim 26, characterized in that in connection with the interruption or termination of the application In connection with the start of the application, components which have been misaligned are returned to their original positions or positions which were assumed before the start of the application.

30. The method according to claim 29, characterized in that - in so far as a coordinated adjustment of several components is provided in connection with the start of the application - the adjustment of the components into the respective original position or position takes place accordingly, but in reverse order.