JPH0299160A - Coating apparatus - Google Patents

Abstract

PURPOSE: To make it possible to form a uniform coating layer by constituting a coating cylinder of a stationary yoke and a rotatably born roller cover disposed concentrically with this yoke and hydraulic supporting means disposed between both. CONSTITUTION: This device is provided with the coating roller 1 rotating in a coating material sump 4, a counter cylinder 2 forming a coating gap 6 of a prescribed width with the cylinder 1 and a doctor blade 10 connected behind the gap 6. The coating cylinder 1 or the counter roller 2 is constituted as a sag-compensating roller. Namely, the coating roller comprises the stationary yoke 12, the rotatable cylinder cover 13 disposed concentrically around the yoke 12 and the hydraulic supporting means disposed between the two and consisting of, for example, pressure chambers or hydraulic supporting device 14 lined up in one row. Consequently, the press gap may be exactly maintained constant over the entire width of the press roller and the formation of the coating layer uniform over the entire part is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coating device according to the preamble of claim (1).

[Prior art and problems to be solved by the invention] This type of coating device is
Fur Papier fabrication) J
1979, pages 137 et seq., FIG. 4.

Achieving a uniform application of paint requires extreme precision both in the area of application and in the area of scraping. Accuracy requirements are within 1/100 of a millimeter. In contrast, interfering effects caused by various operating conditions, such as temperature fluctuations, among others, vary in millimeters.

The ultimate challenge here is to keep the width of the gap between the applicator roller and the counter roller constant. This gap must have the correct size for the given usage situation, and this size must be observed as precisely as possible over the entire length of the gap, ie the width of the web.

If this does not work, leveling with a scraper is no longer completely possible.

Various measures have been taken to achieve this objective, ie to maintain a constant gap width across the width of the web. One of them is to give the application roller a bulge.
Ru. This compensates for roller droop, which becomes more important as the overall length of the roller increases. Furthermore, attempts have also been made to solve this problem by using a structure with particularly high bending rigidity.

All of these treatments ultimately were not completely satisfactory. It became clear again and again that the gap could not be exactly defended.

The problem underlying the invention is to design a coating device of this type in such a way that the gap between the coating roller and the counter roller is always kept constant.

[Means and effects for solving the problem] This problem is solved by the features described in the characterizing part of the claims.

The inventor has obtained the following recognition. That is, the applicator roller rotates in a pool of paint, this pool creates a buoyant force acting on the applicator roller, this buoyant force being dependent on various quantities.
Among these quantities are, inter alia, the specific gravity of the paint and the various rotational speeds of the applicator roller, with the recognition that the specific gravity of the paint depends on the concentration of the paint.

It is certainly effective to use so-called floating rollers instead of swelling rollers in the case of presses.

For presses this has a special meaning. The bulge of the press roller increases the pressing force of the press gap by the web width (=
(gap length) must be kept as constant as possible over the entire length. If the pressing force is constant, this requirement can be achieved by setting a constant bulge in accordance with the pressing force.

However, if the pressing force changes, a different bulge is required to keep the pressing force constant across the width of the web. Floating rollers have an advantage over bulging rollers in this respect. This is because floating rollers can take into account pressing forces of various magnitudes.

In the case of presses, as is known, the two press rollers involved are in contact with each other in the region of the press gap, unless a paper web or the like is guided through the press gap.

On the other hand, in the coating device, no contact occurs between the cylindrical surface of the application roller and the cylindrical surface of the opposing roller. Rather, there is a gap of limited width between these two sleeve surfaces.

At first, it was difficult to explain why the gap width deviated from the recompression target value despite the bulge.

Only with the above recognition - the influence of buoyancy - was it possible to solve this problem. Without this recognition, there would have been no reason to move from a normal bulge coating roller to an expensive deflection compensation roller with a complicated structure.

〔Example〕

The present invention will be explained in more detail with reference to the drawings.

The applicator shown in FIG. 1 includes as main components 1 an applicator roller 1, a counter roller 2 and a scraping means 3. The applicator roller 1 rotates in a reservoir 4 of paint. The reservoir has an inlet and an overflow 5, not shown here.

The applicator roller 1 and the counter roller 2 form an applicator gap 6, so that when the rollers are at rest, i.e., not in operation, there is a distinct distance between the cylindrical surfaces of the rollers 1 and 2. A paper web 7 is wound around the opposing roller 2 and moves in the direction of the arrow, and the two rollers 1 and 2 also rotate in the direction of the arrow.

During rotation of the roller, the applicator roller 1 carries paint from the reservoir 4 into the applicator gap 6, where it is transferred to the paper web 7. A small portion of the paint remains on the cylindrical surface of the coating roller 1 and is returned to the reservoir 4 as a reflux 8. The paper web 7 together with the coating layer 9 thereon then reaches the scraping means 3. A scraping tool 10 serving as a scraping means levels the coating layer 9. The paper web 7 then leaves the opposing roller 2 with the leveled coating layer on it, while the surplus of paint 1
1 is scraped off by a scraping tool 10.

The application roller 1 shown in FIG. 1 is a deflection compensation roller. This applicator roller has as its main elements a fixed yoke 12 which is non-rotatably journaled, a rotatably journaled roller jacket 13 and a coating distributed over the length of the roller (-the width of the paper web 7). It includes a large number of support tanks 14 arranged therein. In order to take into account the deflection of the yoke, both ends of the yoke 12 are equipped with bearings 15 having a spherical shape.
It is supported by a bearing. Bearings 16 are provided at both ends of the sleeve 13.
is supported by.

The support troughs 14 are arranged uniformly over the entire length of the roller and in the region of the application gap 6 of the roller 1. The support tank includes a piston 17 provided in a cylindrical recess 18 of the yoke 12. The piston 17 is in contact with the inner sleeve surface of the sleeve 13. When the sleeve 13 rotates, the end surface of the piston 17 slides on the inner sleeve surface of the sleeve 13. The cylindrical recesses 18 each have an inlet 19 for pressure medium.

The applicator roller 1 rotates in a paint reservoir 4 during operation, as shown in Figure 1. At this time, the application roller's own weight acts downwardly on the application roller 1 on the one hand, and the buoyancy of the reservoir acts upwardly on the other hand. The resulting curvature depends on a large number of factors, the effects of which cannot be calculated individually and accurately in advance.

These factors include the weight of the entire length of the roller, as well as the section modulus of the roller, the number of rotations of the roller, the specific gravity of the paint in the reservoir, and others.

By generating a suitable pressure in the cylindrical notch 18 via the pressure medium introduction part 19, the curved line of the sleeve 13 can be adjusted accurately. This also allows the width of the coating gap 6 to be grasped at the same time. The result appears in the shape of the thickness of the scraped coating layer on the paper web after leaving the opposing roller 2.

The shape of this thickness, ie the thickness of the coating layer measured across the width of the paper web 7, can thus be taken as a measured variable and used as a setting variable, for example for the adjustment of the individual pistons 17. Alternatively, it is also conceivable to use the width of the gap 6 directly as a measured quantity.

The roller 1 is not provided with just one row of support tanks 14, but is also provided with a second row (not shown here) which is offset by 180° in the circumferential direction with respect to the first row. It can also be effective.

This makes it possible to obtain greater stability and smoother running of the applicator roller I. Furthermore, this makes it possible to better understand the starting and stopping of the sheath 13 of the coating roller 1, and it is possible to reliably compensate for the opposing forces of self-weight and buoyancy. It goes without saying that the present invention also makes it possible to compensate for the deflection of the opposing roller.

Instead of the application roller, it is also possible to configure the counter roller 2 as a deflection compensation roller.

However, applicator rollers are more suitable for this because of their smaller diameter.

〔Effect of the invention〕

As mentioned above, according to the invention, the press gap can always be kept very precisely constant over the entire width of the press roller, and thus a very uniform coating layer can be formed over the entire width of the web.

[Brief explanation of drawings]

FIG. 1 is a side view of a coating device comprising a coating roller, an opposing roller and scraping means, and FIG. 2 is an enlarged axial sectional view of the distal end portion of the coating roller 1 of FIG. ■・・・Applying roller 2・・・・Opposing roller 3
...Scraping means, 4.. Reservoir, 5.. Hot liquid, 6.. Application gap, 7.. Paper web, 8.
... Reflux, 9... Application layer, lO... Scraping tool, rt... Surplus, 12... Yoke, 13...
...Cylinder, 14...Support tank, 15.16...Bearing, 17...Piston, 18...Notch, 1
9...Introduction.

Claims (4)

[Claims] (1) A coating apparatus having a coating roller that rotates in a paint reservoir, an opposing roller that forms a coating gap of a predetermined width together with the coating roller, and a scraping section connected after the coating gap. ) or the opposing roller is configured as a deflection compensation roller, i.e. a fixed yoke (12), a roller sleeve (13) arranged concentrically with the yoke and rotatably journaled, and both of these rollers. A coating device characterized in that it is constituted by pressurizing support means, for example consisting of a line of pressure chambers or support vessels, provided between them. (2) Claim (1) characterized in that the pressure support means are arranged in the region of the application gap (6).
The coating device described in . (3) at least two support means are provided, which support means, viewed in cross section perpendicular to the axis, support the yoke (12);
The coating device according to claim 1 or 2, characterized in that the coating devices are offset from each other by a certain angle around . (4) One or more support means are applied to the application gap (6)
according to claim 3, characterized in that one or more supporting means are arranged offset by 180° with respect to said supporting means. coating equipment.