DE102011052535A1 - Method for manufacturing roll e.g. gravure roll, involves bending roll using pulling device which is arranged at radial distance from rotational axis - Google Patents

Abstract

The method involves providing roll (200) having a rotational axis (D) which is bent against a curvature. The bending process is performed using pulling device (209) arranged at a radial distance from the rotational axis. An independent claim is included for roll.

Description

The invention relates to a method for producing engravings on gravure rollers, which have radially projecting plateau surfaces from the engraving base, in which the gravure roller is rotated about its axis of rotation and the engraving is produced in several engraving operations.

Gravure rolls for the thermobonding of nonwovens regularly have a surface which consists of truncated cones or truncated pyramids, that is to say of three-dimensional structures whose cross-section, viewed in the radial direction of the roll, increases to the base of the engraving.

When thermobonding a nonwoven layer is supplied with still unconsolidated, thermoplastic material comprising filaments a nip, which is formed between a gravure roll and a counter roll with a smooth surface. Both the gravure roll and the counter roll are usually heated, wherein the heating power of the gravure roll is selected so that the contact of the plateau surfaces with the filaments for welding them in the area of the system leads to the plateau surfaces.

Thus, the filaments do not stick to the plateau surfaces during the welding process, which would lead to destruction of the nonwoven layer or even to a dangerous roll winding, in which the nonwoven layer wound by the gravure roll and blocked by the rapid increase in size of the roll winding the nip, the plateau surfaces have as smooth a surface as possible. Engraving rollers are therefore subjected during and after the production of the engraving grinding processes, which should also guarantee the most accurate cylinder shape and the most accurate concentricity.

The production of the engraving can be done, for example mechanically with the help of a Molette, thermally by means of a laser or chemically by etching with acid, the plateau surfaces are covered in advance with paint, or by grinding or milling. Also, in the manufacture of the engraving, several of the aforementioned methods can be used in successive engraving operations.

• – Eine zuvor möglichst exakt zylindrisch geschliffene Walze wird mit Lack beschichtet.
• – Anschließend wird mit Hilfe eines Lasers entsprechend der Vorgabe und des Rapportes Lack in den Bereichen weg gebrannt, in welchen ein Materialabtrag stattfinden soll.
• – Durch Ätzen im Säurebad erhält die Walzenoberfläche in Bereichen, in denen zuvor der Lack weg gebrannt worden ist, entsprechende Vertiefungen.
• – Eine erste Molette, die auf den maximalen Durchmesser der Walze abgestimmt ist, wird angedrückt und über die Oberfläche der Walze abgerollt. Dabei befindet sich die Molette im formschlüssigen Eingriff mit den bereits vorhandenen, durch Ätzen im Säurebad eingearbeiteten Vertiefungen.
• – Durch Quetschen und Verdichten bildet sich das Gravurmuster auf der Walze weiter aus. Lack befindet sich schließlich im Wesentlichen nur noch auf den Plateauflächen der Gravur.
• – Erforderlichenfalls wird die Walze einer weiteren Ätzbehandlung im Säurebad unterzogen. Sofern notwendig, muss die Lackschicht auf den Plateauflächen zuvor erneuert werden.
• – Ist eine weitere, mechanische Bearbeitung der Walze mit Hilfe einer Molette erforderlich, so wird eine zweite Molette, die dem sich geänderten Rapport angepasst worden ist, erneut über die Oberfläche der Walze abgerollt. Erfahrungsgemäß sind je nach Gravurtiefe und Design bis zu drei verschiedene Moletten erforderlich, um die Plateauflächen nur gering in ihrer Lage verschieben zu müssen.
• – Insbesondere aufgrund des Quetschens des Walzenmaterials bei der Behandlung mit einer Molette entstehen an den Plateauflächen der Gravur vorstehende Grate. Diese müssen in einem Vermessungsschliff abgetragen werden, um die Plateauflächen und die Gravurtiefe messtechnisch genau erfassen zu können.

For example, a typical method of making engravings on gravure rolls includes the following steps:

• - A previously exactly exactly cylindrical ground roller is coated with lacquer.
• - Subsequently, with the help of a laser according to the specification and the repeat lacquer in the areas burned away, in which a material removal should take place.
• - By etching in an acid bath, the roll surface receives in areas where previously the paint has been burned away, corresponding recesses.
• - A first Molette, which is tuned to the maximum diameter of the roll is pressed and unrolled over the surface of the roll. In this case, the molette is in positive engagement with the already existing, incorporated by etching in the acid bath wells.
• - By squeezing and compressing the engraving pattern on the roller continues to form. Finally, paint is essentially only on the plateau surfaces of the engraving.
• - If necessary, the roller is subjected to a further etching treatment in an acid bath. If necessary, the varnish layer on the plateau areas must first be renewed.
• - If a further, mechanical processing of the roll by means of a Molette required, a second Molette, which has been adapted to the changed repeat, unrolled again over the surface of the roll. Experience has shown that depending on the engraving depth and design up to three different molettes are required to move the plateau surfaces only slightly in their position.
• - Especially due to the squeezing of the roll material in the treatment with a Molette arise on the plateau surfaces of the engraving protruding burrs. These must be removed in a survey grind in order to capture the plateau surfaces and the engraving depth metrologically accurate.

Even in processes for producing engravings in which more material is removed thermally, for example by a laser, or mechanically by grinding or milling, the engraving progress must always be measured. This requires the previously mentioned survey cut of the roll, which can only be made on an at least substantially cylindrical roll.

This is a significant problem in practice because the roll curves during engraving due to strain hardening of the roll material and / or disturbances in the overall stress balance. The roller must therefore be repeatedly directed between the engraving steps, which takes place thermally in the known methods by local heating.

For this purpose, certain, previously determined by estimation flash points are regularly heated by means of a gas flame, the Heat input is also estimated from experience. This thermal straightening method is very complicated and time-consuming. Because it is always necessary to wait until the roll body again has room temperature in order to check whether the thermal, local treatment has led to the desired orientation of the roller. Due to the ever-present uncertainty of success, the engraving process is almost incalculable.

The invention is therefore based on the object to provide an improved method for producing engravings on gravure rolls, in particular for the thermobonding.

This object is achieved by the reproduced in claim 1 engraving.

In the method according to the invention for producing engravings on gravure rolls, the roll is ground at least substantially cylindrically in a first grinding process before the first engraving process. In a further step, after the first grinding operation, the roller is subjected to at least the first or further engraving process. This may in particular be a thermal or chemical engraving process of the type described above, or else any other or even different engraving processes carried out successively. In order to record the engraving progress, the plateau surfaces and the engraving depths must be measured, for which purpose - as described above - a survey grind must first be carried out by means of a grinding tool. Since the roll has become regularly curved due to the work hardening or the disturbance of the overall stress balance, the method according to the invention provides for guiding the grinding tool at least approximately along the envelope formed by the plateau surfaces during the measuring cut.

In order to be able to guide the grinding tool at least approximately along the envelope of the gravure roll, in a first, preferred embodiment the gravure roll can be pre-stressed before the grinding process such that its envelope has at least approximately a cylindrical shape. The grinding tool is then displaced parallel to the axis of rotation of the gravure roll.

The bias voltage can be initiated for example by means of a arranged at a radial distance from the axis of rotation pulling device. Such a pulling device can be used in particular when the gravure roller peripheral, d. H. Having spaced apart from the axis of rotation arranged longitudinal bores. The pulling device is then introduced into the peripheral bore, which extends as close as possible along the largest, concave curvature of the gravure roll. The pulling force exerted by the pulling device is then selected so that the curvature of the roller is at least substantially eliminated. If necessary, several drawbars can be used in different peripheral holes. Also, the drawbars, if not for the further treatment or use of the gravure roll, be left in the holes so as to be able to direct the engraving roll, if necessary, after further treatment steps or use. In this case, can be dispensed with an otherwise regularly required, thermal closing, since the roller usually bends after removing the tie rods.

If the gravure roll have a central longitudinal bore, then the bias can also be generated with a bending device arranged in the central bore of the gravure roll. This may be, for example, a bending device, taken by itself from the DE 198 19 663 A1 is known.

In the preferred embodiments described above, the grinding tool is thereby guided at least approximately along the lateral surface of the gravure roll, since the gravure roll is at least approximately brought into a cylindrical shape before the grinding process.

In a second, preferred embodiment of the method according to the invention, however, no specific stress is exerted on the gravure roll for compensating the curvature. Instead, the concentricity deviations of the envelopes are measured before or during grinding, the measured values are stored spatially resolved with respect to the envelope, and the grinding tool is displaced with the aid of the stored measured values during the grinding process in such a way that it substantially follows the lateral surface. With this embodiment of the method according to the invention, in particular, such gravure rolls can be processed particularly advantageously in the sense of a plateau surface size which is as constant as possible, which not only have a simple curvature, but also those which, for example, have an "S-curvature" or, in the course of a round, a "double impact" , Also, the gravure roll can be preloaded and measured to improve the grinding accuracy on.

In principle, in order to improve the accuracy of the engraving method, it is desirable to record the measured values of the lateral surface in as narrow a grid as possible. In practice, it will be sufficient in most cases, if - as preferred - measured values of the distance of the lateral surface of the axis of rotation of the gravure roll in the roll longitudinal direction about every 5 cm to 20 cm and recorded in the direction of rotation with an angular distance of about 5 ° to 20 ° and stored.

The invention also extends to a gravure roll, in particular one intended for thermobonding nonwovens, which has been processed by an engraving process of the type described above.

The invention will be further clarified below with reference to the purely schematic drawings. Show it:

1 a engraving method according to the prior art;

2 a gravure roll with a arranged at a radial distance from the axis of rotation pulling device for effecting a bias and

3 - Partial - the contour of an engraving structure in the section during engraving and in the final state.

1 illustrates how for the purpose of grinding a curved after an engraving gravure roll 1 rotatable in a storage facility 2 stored and rotationally driven in the direction of the arrow P1 with drive means not shown in the drawing about the rotation axis D. The curvature of the gravure roll 1 opposite to the axis of rotation D is in 1 and 2 for exaggeration shown.

Would now also the curved envelope 3 with the help of a grinding tool 4 which rotates around a rotation axis R which is parallel to the axis of rotation D rotating grinding wheel 5 comprises, ground by displacement of the same parallel to the axis of rotation D, the in 1 area blackened areas of the gravure roller shown 1 further than the other ground down. Due to the curvature of the roller 1 and the associated run - out errors would have in the area that is in 1 is shown at the top center, the engraving structures 6 (please refer 3 ), each forming the shape of an engraving reason 8th towards increasing truncated cone, larger plateau surfaces and a lower engraving depth than in the other areas.

The same applies to the in 1 below flat engraving structures shown in black.

To prevent these different depths of the engraving structures, is in the in 2 illustrated gravure roll shell in an only indicated peripheral bore on the concave side a tension element 9 used with which a tension FF is exerted at a distance from the roll center, which exerts on the roll shell a symbolized by the arrows M bending moment, which leads in the sense of a straight direction of the curved roll shell.

As in 3 is schematically shown, Meßschleifvorgänge between engraving steps are required because due to during engraving at the edge of the plateau surfaces 7 forming ridges 10 neither the areas A of the plateau areas 7 , nor the depths X of the engraving can be measured with the required precision. In this figure are with 11 a grinding process, with Kg the contour during engraving and with Kf the contour of the finished contour.

LIST OF REFERENCE NUMBERS

1

 engraved roll

2

 Storage facility

3

 envelope

4

 grinding tool

5

 grinding wheel

6

 engraved structures

7

 plateau areas

8th

 engraved reason

9

 tension element

10

 ridge

11

 grinding

a

 distance

A

 surfaces

D

 axis of rotation

F-F

 tension

kg

 Contour during engraving

kf

 Contour of the finished engraving

M

 arrow

P1

 arrow

R

 axis of rotation

X

 deep

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19819663 A1 [0015]

Claims (9)

Method for the production of engravings that are radial from the engraving ground ( 8th ) above plateau areas ( 7 ), on gravure rollers ( 1 ), in which the gravure roll ( 1 ) is rotated about its axis of rotation (D) and the engraving is produced in several engraving processes, characterized in that the gravure roll ( 1 ) is ground at least substantially cylindrically before the first engraving process in a first grinding operation, that the engraving roll ( 1 ) is subjected after the first grinding operation at least the first or further engraving operations, and that the plateau surfaces ( 7 ) after the first and / or further engraving operations in at least one second or further grinding operations ( 11 ) by means of at least one grinding tool ( 4 ), the grinding tool ( 4 ) at least approximately along that of the plateau surfaces ( 7 ) envelopes ( 3 ) to be led. Engraving method according to claim 1, characterized in that the gravure roll ( 1 ) is biased before the engraving process such that its envelope ( 3 ) has at least approximately a cylindrical shape and that the grinding tool ( 4 ) parallel to the axis of rotation (D) of the gravure roll ( 1 ) is relocated. Engraving method according to claim 2, characterized in that the gravure roll ( 1 ) with a arranged at a radial distance from the axis of rotation pulling device ( 9 ) is biased. Engraving method according to claim 3, characterized in that the traction device ( 9 ) comprises one or more tie rods which in one or more peripheral bores of the gravure roll ( 1 ) is arranged. Engraving method according to claim 4, characterized in that the one or more tie rods remains in the peripheral or the peripheral bores. Engraving process according to one of Claims 1 to 5, in which the gravure roll ( 1 ) comprises a central longitudinal bore, characterized in that the gravure roll ( 1 ) with one in the central bore of the gravure roll ( 1 ) arranged bending device is biased. Engraving method according to claim 1 or 2, characterized in that the concentricity deviations of the envelope ( 3 ) are measured before the grinding process that the measured values relative to the lateral surface ( 3 ) are stored spatially resolved, and that the grinding tool ( 4 ) is shifted with the aid of the stored measured values during the grinding process such that it follows the envelope at least substantially. Engraving method according to claim 7, characterized in that measured values of the distance in the lateral surface ( 3 ) from the axis of rotation of the gravure roll ( 1 ) are recorded and stored in the roll longitudinal direction about every 5 cm to 20 cm and in the direction of rotation with an angular distance of about 5 ° to 20 °. Gravure roll ( 1 ) processed by an engraving method according to any one of claims 1 to 8.

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