EP0831973B1 - Supporting system for the metering component of a coating device - Google Patents

Abstract

PCT No. PCT/EP97/02166 Sec. 371 Date Nov. 21, 1997 Sec. 102(e) Date Nov. 21, 1997 PCT Filed Apr. 26, 1997 PCT Pub. No. WO97/41967 PCT Pub. Date Nov. 13, 1997A support strip is braced against a doctor blade for coating a web and consists of spring steel sheet subdivided by slits into tongues. The tongues are securely clamped at their ends facing away from the dosage element and the continuous frontal edge is supported between guide strips so as to be movable in the direction of the dosage element. Adjustment elements engage at the tongues to cause them to bend perpendicularly with respect to the span of the tongues to control the force applied to the doctor blade.

Description

Technical field

The invention relates to a support system for the metering element of a coating device, especially for the doctor blade of a coating device for paper or Cardboard webs, according to the preamble of claim 1.

The known coating devices for paper or cardboard webs have an application unit (Roller or nozzle applicator) with which the coating material, for. B. Coating color, is applied in excess to the web. One following the commissioned work arranged metering system with a metering element scrapes the excess down to the desired coat weight. The coating weight is set using the contact pressure of the dosing element to the web in this area by a counter roller is supported.

State of the art

Production-related fluctuations occur when coating paper or cardboard webs in the cross section of the webs, which make it necessary, the contact pressure of the metering element locally different across the working width to ensure a uniform Get dash. When using a scraper knife as a dosing element, this becomes supported by a support bar on the back below its tip, which is flexible within limits and by means of tension and pressure screws along the support line can be adjusted, depending on whether the coat weight on the corresponding Set too high or too low (DE-C 28 25 907).

From WO93 / 05887 a generic support system is known in which the doctor knife is supported by a flat bar that is in the area of her on the doctor knife adjacent front edge is continuous and a series of longitudinal slots has so that it is sufficiently flexible to different pressures on the doctor blade to be able to adjust. On each tongue between two slits one grips of a pneumatic bellows operated lever with which this area of the support bar can be individually deformed in the direction of the scraper knife by a certain contact pressure adjust.

Presentation of the invention

The invention has for its object to improve a generic support system so that simply set different local contact pressures against a dosing element can be.

To solve this problem, the contact pressure of the metering element is generated by means of a series of pressure chambers in the support system . Each pressure chamber is connected via a line which can be closed by means of a valve to a common pressure vessel which is connected to a compressed air supply via a controllable valve, in particular a proportional valve.

In the structurally simple solution according to claim 2 , the support bar consists of a spring plate which has a series of longitudinal slots. The tongues formed in this way are clamped on their side facing away from the metering element, while the continuous front edge is movably supported between guide strips in the direction of the metering element. Pressure chambers act as adjusting elements on the tongues, which cause bending perpendicular to the plane of extension of the tongues. Bending a tongue perpendicular to its plane of extension leads to a change in the effective length, which, due to the clamping on one side and guidance on the other side, has the effect of changing the course of the leading edge at the corresponding point. The contact pressure of the support bar on the dosing element can be changed in this area.

The further subclaims contain preferred, since particularly advantageous, embodiments of the invention.

Brief description of the drawing

Fig. 1

zeigt einen Längsschnitt durch ein Abstützsystem nach der Erfindung.

Fig. 2

zeigt eine Draufsicht auf das Abstützsystem nach Figur 1.

Fig.3

zeigt einen Längsschnitt durch ein Abstützsystem mit einer Wegmeßeinrichtung für jede Stellzunge.

Fig.4

zeigt einen vergrößerten Ausschnitt von Figur 3.

Fig. 5

zeigt das Prinzip des Steuersystems zur Steuerung des Anpreßdrucks.

The drawing serves to explain the invention on the basis of simplified exemplary embodiments:

Fig. 1

shows a longitudinal section through a support system according to the invention.

Fig. 2

shows a plan view of the support system of Figure 1.

Figure 3

shows a longitudinal section through a support system with a displacement measuring device for each positioning tongue.

Figure 4

shows an enlarged section of Figure 3.

Fig. 5

shows the principle of the control system for controlling the contact pressure.

Ways of Carrying Out the Invention

The coating device has a driven counter roll 1, of which the material web 2-a paper or cardboard web of a width of 8 m and more is deflected. On the web 2 was coated by a coating unit, not shown Excess applied, preferred by a metering system with a metering element an elastically bendable scraper knife 3, doctored down to the desired coating weight becomes. The scraper knife 3 is with its foot in a direction towards the counter roller 1 Slidable clamping bar 4 clamped and is facing away from the counter roller 1 Side below the scraper knife tip from one towards the counter roller 1 supported in elastic resilient support bar 5. By a relative Displacement of the clamping bar 4 to that extending over the entire web width Support bar 5, the contact pressure of the doctor knife 3 can be adjusted to the counter roller 1.

The support bar 5 is the essential part of the support system, which is on top of a in a known manner pivotally mounted to the counter roller 1 scraper bar 6 is in which the clamping bar 4 with the doctor knife 3 is mounted. The support bar 5 consists of a thin spring plate of 0.5 mm-1.5 mm, preferably of approximately 1 mm, Thickness and 200 mm-400 mm, preferably about 300 mm, width that in its length over the total working width, i.e. the maximum web width is sufficient. The support bar 5 is comb-shaped with a continuous front edge 7 of 10 mm-70 mm, preferably approx. 40 mm, Width and a series of tongues 8 separated by longitudinal slots, the The number and spacing from one another is selected such that every 50 mm-150 over the working width mm a tongue 8 is present as an actuator. The tongues 8 preferably have a width of approx. 80 mm and are arranged at a distance of approx. 20 mm from each other. With this construction, the front edge 7 is towards the scraper knife 3 (arrow 9 in Fig. 2) sufficiently flexible to move a tongue 8 in this direction to be elastically deformed.

The fastening and adjustment mechanism for the support bar 5 is in Figures 1 and 3 shown in more detail for two embodiments:

In both embodiments, there is an over the entire working width on the scraper bar 6 extending lower clamping plate 9, which is somewhat in its central region is lowered - towards the scraper bar 6-. Above the clamping plate 9, a second clamping plate 10 is arranged, which is approximately opposite in its central region to the lower clamping plate 9 is curved, so that a cavity between the plates 9, 10 are formed, in which a number of adjusting elements are arranged can.

The support bar 5 is arranged between the two clamping plates 9, 10 so that the Tongues 8 through the cavity to the ends of the scraper knife 3 facing away Extend clamping plates 9, 10. At this end, the clamping plates 9, 10 run parallel one above the other and thus form two terminal strips between which the ends of the tongues 8 are stuck. Run on the opposite side near the doctor knife 3 the clamping plates 9, 10 also parallel and thus form guide strips 11, 12 for the front edge 7 of the support bar located in this area. The guide rails 11, 12 are held by set screws 13 at a distance from each other, which is slightly larger than the thickness of the support bar 5, so that the something protruding from the guide bars 11, 12 Front edge 7 of the support bar in the direction of the scraper knife 3 and back is movable between them.

In the central area between the clamping plates 9, 10, an adjusting element engages on each tongue 8 with which the respective tongue 8 is perpendicular to its plane of extension bends. A bend of a tongue perpendicular to the plane of extension (in the Figures 1 and 3 up or down) leads to a change in the effective length that itself as a change due to the clamping on one side and guidance on the other side affects the course of the front edge 7 at the corresponding point; d. H. the Contact pressure of the support bar 5 on the scraper knife is changed in this area.

A bellows 14 is arranged below each tongue 8 in the central region of the clamping plates 9, 10, which is supported on the lower clamping plate 9 and with a feed 15 Compressed air can be applied so as to bend the tongue 8 upwards cause. Each tongue 8 is pressed onto the bellows 14 assigned to it by a compression spring 16 pressed down against the bellows 14, which is attached to the upper clamping plate 10.

In the embodiment according to FIG. 1 there is a holding plate at the lower end of the spring 16 17 attached, which presses against the tongue 8. The compressive stress of the spring 16 can be by means of an adjusting screw 18.

Since the tongues 8 are bent perpendicular to their plane of extension, the adjustment element (bellows 14, spring 16) can also be a mirror image of the plane of extension to be ordered. The bellows 14 are then above, the springs 16 below the tongues 8.

In the embodiment according to FIG. 3, the guide strips 11, 12 are separate components formed by the clamping plates 9, 10 and screwed to this. The compression springs 16 press directly against the tongues 8 without an intermediate holding plate. Additionally is for each tongue 8 in the area between the adjusting element (bellows 14, spring 16) and continuous front edge 7 each have a displacement measuring device, of which the movement the respective tongue 8 from a reference position in the direction of the doctor knife 3 and back is measured. The path measuring devices are preferred in the area of two guide rails 11, 12 arranged where the tongues 8 secured against bending are guided and is measured close to the front edge 7. Measure the measuring devices at this point, the displacement of the leading edge is unaffected by hysteresis effects 7 towards the scraper knife 3.

In the embodiment according to FIG. 3 and FIG. 4, the path measuring devices are inside the guide strips 11, 12 in a extending across the working width Cavity 24 is arranged through which the tongues 8 are guided. There is one on each tongue 8 Measuring bolt 25 is screwed extending vertically upwards, so in the event of a shift the tongue 8 is moved with. The measuring pin 25 has the doctor knife on it 3 facing away from the back (left in Figure 4) on a flat side surface the axially displaceably mounted measuring pin 26 pressed with its end face by a spring becomes. The measuring pin 25 thus transmits a movement of the tongue 8 to the measuring pin 26. The measuring pin 26 moves with its end facing away from the measuring pin 25 in one Solenoid 27 and thus changes its inductance depending on its position.

With the position measuring devices 25, 26, 27, the position of each tongue 8 can thus be immediate in front of the front edge 7 of the support bar 5 and thus the position of the front edge 7 itself can be determined and reproduced in the respective setting range. For example, at a Restart the coating device once a position has been found to be advantageous adjust the support bar 5 in the individual areas of its front edge 7 again.

Before the coating is started, the pressure system is preferably set so that everyone Bellows 14 against the force of the associated spring 17 its tongue 8 to half the vertical Adjustment path pushes up. This, drawn in Figure 3 with solid lines Position allows each tongue 8 to either push up further pull the front edge 7 of the support bar 5 away from the doctor knife 3 in this area, or lower the pressure in the bellows 14 so that the compression spring 17 the tongue 8 down presses and in this area presses the leading edge 7 towards the doctor knife 3, so that the contact pressure increases in this area. If there is an uneven coating Cross profile in the coat weight, so by changing the pressures in the corresponding bellows 14 the contact pressure of the support bar 5 against the cockroach 3rd be increased or decreased in the appropriate areas until a uniform Line profile is present.

4 schematically shows the control system with which the desired pressure can be set in each baig 14 with a minimum number of control elements. This system can be used not only in the support system described above , but also in other systems in which a number of pressure chambers are to be subjected to different pressures. In particular, its use is also advantageous in coating devices with a metering system which contains a doctor rod as the metering element, which is supported by a pressure hose which is divided into individual pressure chambers across the working width. Such a coating device is described in DE-PS 43 41 341.

The control system consists of a common compressed air tank 19, which is controllable Valve 20, preferably a proportional valve, is connected to a compressed air supply 21 is. A desired pressure can be set in the container 19 via the valve 20.

From the container 19 branches to each pressure chamber to be pressurized with air, in the present case Example for each bellows 14, a line from 22, in which a simple on / off valve 23 is arranged. By opening a valve 23, the associated pressure chamber (bellows 14) set a pressure corresponding to the container 19.

The setting of the individual pressures in the bellows 14 is now carried out in such a way that initially over the proportional valve 20 in the container 19, the average pressure (z. B. 3 bar) is set, wherein the valves 23 to the bellows 14 are open. In each bellows 14 arises thus also the mean pressure at which each tongue 8 is half its maximum Adjustment path is bent upwards. The front edge 7 of the support bar is thus with a medium contact pressure on the doctor knife 3. Then the Valves 23 between the container 19 and the bellows 14 closed.

If the coat weight in individual areas of web 2 is too low, it must be in these areas the contact pressure of the support bar 5 can be reduced against the doctor blade 3, if the scraper knife 3 works in the so-called Ridgid Blade mode. This is done in such a way that first the pressure in the container 19 is increased to such an extent that a corresponding Pressure in a bellows 14 cause the required deflection of a tongue 8 upwards would. Then the valves 23 of the bellows 14 in the areas with too low Line weight opened. The increased pressure in the corresponding bellows 14 leads to a deflection of the corresponding tongues 8 upwards and thus to a lowering the contact pressure of the doctor knife 3 in these areas, since the tongues 8 at a Movement upwards pull the leading edge 7 of the support bar 5 away from the scraper knife 3. If the coat weight in other areas is too high, the pressure in the Container 19 lowered to the required value. Then by opening the corresponding valves 23 the pressure in the desired bellows 14 to the lower Lowered value in container 19. The lower pressure in a bellows 14 causes the Compression spring 17, the respective tongue 8 down and thus the front edge 7 of the support bar 5 pushes in the direction of the scraper knife 3. This leads to an increased contact pressure the scraper knife 3 and thus to a lower coating weight in this area.

Claims (7)

1. Supporting system for the metering element (3) of a coating device containing a series of pressure chambers (14) which produce a locally differing contact pressure of the metering element, characterized in that each pressure chamber (14) is connected via a line (22), which can be shut off by means of a valve (23), to a common compressed-air container (19) which is connected to a compressed-air supply (21) via a controllable valve (40), in particular a proportional valve.
2. Supporting system according to Claim 1, characterized in that it contains, as supporting element, a flat supporting strip (5) which consists of spring steel plate, is of continuos design in the region of its front edge (7) and has a series of longitudinal slots,

   the tongues (8) between the slots being clamped in place at their end facing away from the metering element (3),

   the continuous front edge (7) between guide strips (11, 12) being mounted movably in the direction of the metering element (3), and

   pressure chambers (14) acting on the tongues (8) and causing a deflection perpendicular with respect to the plane of extent of the tongues (8).
3. Supporting system according to Claim 2, characterized in that a respective, pneumatically actuable bellows (14) is arranged below or above a tongue (8) as an adjusting element.
4. Supporting system according to Claim 2 or 3, characterized in that a spring (16) presses the tongue (8) against the bellows (14).
5. Supporting system according to one of Claims 2 to 4, characterized in that a respective distance-measuring device (25, 26, 27) for determining the position of the front edge (7) in the particular adjustment region is arranged in the region of each tongue (8).
6. Supporting system according to Claim 5, characterized in that the distance-measuring devices (25, 26, 27) are in each case arranged between the adjusting element (14, 16) and the continuous front edge (7), in particular in the region of the guide strips (11, 12).
7. Device for coating a material web (2), in particular a paper or cardboard web, having a mating roll (1) which supports the web (2) and a ductor beam (6) in which a metering element, in particular a ductor blade (3), is mounted in a manner such that it can be pressed against the web (2), characterized in that a supporting system according to one of claims 1-6, for supporting the metering element (3), is secured on the ductor beam (6).

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