EP4286160A1 - Embossing roll - Google Patents

Abstract

A method for engraving a roller blank (1) is therefore proposed, wherein material is removed from the roller blank (1) using laser light, with a distance (4) of the focus (5) of the laser light from the longitudinal axis (L) of the roller blank (1 ) is set depending on an optical distance measurement. Furthermore, a method for reprocessing a roller (18) is proposed, wherein after an outer layer (23) of the roller (18) has been removed, a method according to the invention for engraving a roller blank (1) is carried out. It is also proposed to use a roller (18) produced by a method according to the invention to emboss a material (see FIG. 1).

Description

The invention relates to a method for engraving a roller blank.

The invention further relates to a method for reprocessing a roller.

The invention further relates to the use of a roller produced by a method according to the invention for embossing a material.

Such rollers can be used in particular in embossing processes. For this purpose, the roller must have an appropriate profile. This profile can be produced, for example, using an etching process. However, such rollers can also be engraved.

It is the object of the invention to improve manufacturing processes for such rollers.

To solve the stated problem, the features of claim 1 are provided according to the invention. In particular, in order to solve the stated problem in methods of the type described at the outset, it is proposed according to the invention that material is removed from the roller blank using laser light, with a distance of the focus of the laser light from the longitudinal axis of the roller blank being adjusted as a function of an optical distance measurement.

The use of laser light has the advantage over previous methods using etching processes in that a greater resolution of the embossed profile can be achieved. When using laser light, it is important to focus the laser light on the area to be engraved, for example the surface of the roller blank. The position of the focus of the laser light can be defined by the distance from the longitudinal axis of the roller blank. This has the advantage that the position of the focus remains constant during the engraving when the roller blank rotates around the longitudinal axis.

Determining the position of the focus using an optical distance measurement has the advantage that this determination can be carried out without contact. This determination can also be repeated during engraving so that the focus distance can be checked regularly and adjusted if necessary.

In an advantageous embodiment it can be provided that the optical distance measurement is carried out using laser light.

This means that coherent light can be used for optical distance measurement. It is conceivable to use the same laser source as for engraving for optical distance measurement. Here, for example, a different intensity of the laser beam can be selected so that no engraving is carried out during the distance measurement.

In an advantageous embodiment it can be provided that the roller blank is made of a metal. Alternatively or additionally, it can be provided that the roller blank is made of a metal-containing material. This can be steel, for example.

This makes it possible, for example, to engrave steel rollers or rollers of great hardness. This has the advantage that the profile applied in this way, for example the embossed profile, is more stable against mechanical wear than is the case with rollers made of softer material. Depending on the material to be processed or embossed with the roller, the use of rollers made of harder materials may be advisable.

In an advantageous embodiment, it can be provided that the pattern to be engraved, i.e. the engraving pattern, is provided as an image file. This image file can preferably contain grayscale. In addition, it can be provided that the gray levels are used to determine the engraving depth. The gray levels can also be used to determine the intensity of the laser light.

This makes it possible to provide the patterns to be embossed as an image file. At the same time, information about the engraving depth or the intensity of the laser light can be contained in this image file. The natural language of the graphic designers or artists who provide the engraving pattern can therefore be used in the form of image files.

In an advantageous embodiment it can be provided that transitions between different profile structures are provided with curves with a defined minimum radius of curvature.

Thus, depending on the material to be processed with the roller, a different minimum curvature radius can be used, which prevents the material from breaking or otherwise being accidentally damaged during processing, for example embossing.

In an advantageous embodiment, it can be provided that the engraving is carried out by moving the focus of the laser light perpendicular to the direction of the laser light over the surface of the roller blank. In addition, it can be provided that the roller blank is rotated about its longitudinal axis.

Thus, for example, at a certain rotational position, the entire length of the roller blank can first be engraved before the roller blank is rotated further to the next one Insert engraving section. It can be engraved line by line, so to speak. This can increase the efficiency of engraving.

In an advantageous embodiment, it can be provided that the engraving is carried out in several engraving steps.

Performing multiple engraving steps allows for more precise depth adjustment of the engraving. The engraving depth does not have to be adjusted exclusively by adjusting the intensity of the laser light, but can also be done by engraving multiple times in the same place.

In addition, it can be provided that the surface of the roller blank is engraved in an engraving step at a constant distance of the focus of the laser light from the longitudinal axis of the roller blank. Alternatively or additionally, it can be provided that the surface of the roller blank is engraved with variable intensity of the laser light in an engraving step.

This means that the focus of the laser light cannot be readjusted during an engraving step. The engraving depth can be adjusted by changing the intensity of the laser light. This can increase the efficiency of engraving.

In an advantageous embodiment, it can be provided that the distance of the focus of the laser light from the longitudinal axis of the roller blank is changed between two engraving steps. It can be provided here that the distance of the focus of the laser light from the longitudinal axis of the roller blank is reduced between two engraving steps.

This means that a roll blank can be processed from the outside to the inside. This means that the focus distance can be changed with each engraving step of the laser light to the longitudinal axis of the roller blank can be reduced in order to engrave deeper structures.

In an advantageous embodiment, it can be provided that the roller blank is brushed between two engraving steps.

This means that material that has been detached from the roller blank, possibly oxidized, can be removed from the roller blank so that it does not stand in the way of a further engraving step. Otherwise, it could be that material that has already been detached from the roller blank but not yet completely removed is again treated with laser light in further engraving steps, and the surface of the roller blank is not treated or is not treated sufficiently. This means the quality of the engraving can be increased. This also has the advantage that the engraving depth can be increased. Brushing can be done mechanically.

In addition, it can be provided that metal brushes are used. Alternatively or additionally, it can be provided that a lubricant is used.

Thus, the efficiency of the removal of the third party by the laser on dissolved material can be increased. This results in an increase in the quality of the lasered roller.

In an advantageous embodiment, it can be provided that the roller blank is brushed using at least two brushes of different hardness. It can be provided that softer brushes are used as the engraving depth increases.

With greater engraving depth, the use of softer brushes leads to better removal of the material burned off or dissolved by the laser. So can initially Harder brushes are used, which lead to better removal of the loosened material in the area close to the surface. As the depth increases, softer brushes can be used, which can better penetrate deeper structures in order to remove material there.

In an advantageous embodiment it can be provided that an engraving depth is more than 1 mm. This can preferably be more than 2 mm. This can particularly preferably be more than 3 mm.

This means that a particularly wide range of profiles can be incorporated into the roller blank. These engraving depths can be achieved, for example, by advantageously adjusting the distance of the focus of the laser light from the longitudinal axis of the roller blank, by using brushes with advantageous properties and/or by advantageously choosing several engraving steps, in particular as described above.

In an advantageous embodiment, it can be provided that the material is removed using pulsed laser light. In addition, it can be provided that the laser pulses are directed alternately onto two parallel paths. Two laser beams can be used here.

This can increase the efficiency and quality of the profile introduced into the roll blank.

Alternatively or additionally, in order to solve the stated problem, the features of the independent claim directed to a method for reprocessing a roller are provided according to the invention. In particular, in order to solve the stated problem, the invention involves a method for reprocessing a roller of the type described at the outset proposed that after removing an outer layer of the roller, a process as described above is carried out.

This means, for example, that worn rollers that only provide low embossing quality can be reprocessed and reused. For this purpose, the outer, old profile of the roller is removed. A new profile is then introduced using a procedure as previously described. This means that the advantages already described can also be used with remanufactured rollers.

In an advantageous embodiment, it can be provided that the outer layer of the roller is removed by grinding. Alternatively or additionally, it can be provided that the outer layer of the roller is removed using laser light.

Any requirements for the removal of the outer layer of the roller, for example due to the engraving pattern contained there or the roller material, can thus be met and the method for removing the material can be chosen advantageously. It is possible, for example, to carry out selective material removal using laser light and, for example, to take into account the profile existing on the roller.

In an advantageous embodiment, it can be provided that before the outer layer of the roller is removed, an existing engraving is recorded and processed in the subsequent engraving process. This detection can be done optically, for example.

This means that an existing engraving can be reproduced without, for example, having to submit the image files on which the existing engraving is based.

In an advantageous embodiment, it can be provided that the smallest repeat unit of the engraving is determined and from this the smallest possible thickness of the material layer to be removed is determined, so that the engraving pattern of the reprocessed roller merges into itself.

Rollers can be advantageously manufactured if the engraving pattern on them merges into itself, so that no interruption in the embossed pattern is visible after any embossing of a material. In order to achieve this effect, after removing an outer layer, it is necessary to reduce the size of the existing and, if necessary, optically recorded engraving pattern, or to shorten it while maintaining the same size of the engraving pattern. It is advantageous if the engraving pattern on it merges back into itself even with the reprocessed roller, which will have a smaller circumference than the non-reprocessed roller. To do this, at least the smallest repeat unit must be removed from the engraving pattern. In order to remove only as little material as necessary, it is advantageous to remove only the smallest repeating unit and not several of these repeating units from the engraving pattern. Once this smallest repeat unit has been determined, the thickness of the layer of material to be removed can be determined. This information can then be used during the removal of the material layer. This minimizes the necessary removal of the outer layer of the roller to be remanufactured.

A preferred application of the invention provides that a roller produced by a method according to the invention, in particular as described above, is used to emboss a material.

The advantages mentioned can thus be realized with embossing rollers For example, high accuracies, resolutions of the embossing profile, engraving depths, and the avoidance of unwanted damage to the embossed material can be used here.

In an advantageous embodiment it can be provided that a profile roller interacts with a counter-profile roller.

Thus, for example, two corresponding rollers can be produced using a method according to the invention, in particular as described above. This can increase the quality of the embossing. Alternatively or additionally, it can be provided that a profile roller interacts with an elastic roller. This means that other materials are also available for engraving, for example softer materials such as cellulose. It is advantageous to emboss softer materials using an elastic roller.

The elastic roller can in particular be an unprofiled roller. Therefore, only the production of a profile roller using the method according to the invention is necessary. This can be used advantageously for savings.

In an advantageous embodiment, it can be provided that a defined distance is maintained between the profile roller and the counter-profile roller. Instead of the counter-profile roller, this can also apply to the more elastic and/or the unprofiled roller.

This means that the material can be embossed in a defined manner.

In an advantageous embodiment it can be provided that the material is a metal. Alternatively or additionally It can be provided that the material is a metal-containing material.

In an advantageous embodiment it can also be provided that the material is cellulose tissue. Alternatively or additionally, it can be provided that the material is plastic.

Depending on the requirements, a wide variety of materials can therefore be embossed with an embossing roller produced using a method according to the invention. The roller can be tailored to the requirements of the respective material. For example, the hardness of the material can be taken into account. Further parameters can be elasticity or plasticity of the material to be embossed.

The invention will now be described in more detail using an exemplary embodiment, but is not limited to the exemplary embodiment. Further exemplary embodiments result from combining the features of individual or several claims with one another and/or with individual or several features of the exemplary embodiment.

Figur 1

eine schematische Darstellung eines erfindungsgemäßen Verfahrens zur Gravur eines Walzenrohlings,

Figur 2

eine schematische Darstellung zweier Gravurtiefen,

Figur 3

eine schematische Darstellung dreier Lasermodi,

Figur 4

eine schematische Darstellung des Querschnitts einer Walze,

Figur 5

ein beispielhaftes Gravurmuster.

It shows:

Figure 1

a schematic representation of a method according to the invention for engraving a roller blank,

Figure 2

a schematic representation of two engraving depths,

Figure 3

a schematic representation of three laser modes,

Figure 4

a schematic representation of the cross section of a roller,

Figure 5

an exemplary engraving pattern.

In Figure 1 the application of the method according to the invention for engraving a roller blank 1 is shown, with material being removed from the roller blank 1 using laser light. The laser light is emitted in the form of a laser beam 2 by a laser diode 3. Here, a distance 4 of the focus 5 of the laser light from the longitudinal axis L of the roller blank 1 is set as a function of an optical distance measurement. The optical distance measurement is also carried out using laser light with a laser beam 7 emitted by a laser diode 6, which is reflected on the roller blank 1 and registered by a photodiode 8.

In the exemplary embodiment, the roller blank 1 is made of steel, a metal-containing material. Furthermore, the image file contained in grayscale for engraving pattern 25 was provided. In the exemplary embodiment, the gray levels are used to determine the engraving depth 13, 16, partly based on the intensity of the laser light. A defined minimum curvature radius, on the basis of which the transitions between different profile structures are provided with curves, is taken into account.

In the exemplary embodiment, the engraving is carried out by moving the focus 5 of the laser light perpendicular to the direction 10 of the laser light over the surface 11 of the roller blank 1. Here, the roller blank 1 is rotated about its longitudinal axis L.

The engraving is carried out in several engraving steps, with the surface 11 of the roller blank 1 being engraved in one engraving step at a constant distance 4 of the focus 5 of the laser light from the longitudinal axis L of the roller blank 1 and with a variable intensity of the laser light.

In addition, the distance 4 of the focus 5 of the laser light to the longitudinal axis L of the roller blank 1 is changed between two engraving steps, namely reduced.

Between two engraving steps, the roller blank 1 is brushed using two brushes 12, 14 of different hardness and using a lubricant (not shown). Here, a metal brush 12 is first used and, as the engraving depth 13 increases, a softer brush 14 is used. The engraving depth 13 is more than 3 mm here.

In Figure 2 the engraving depth 13 of an engraving 24 is shown in a section 15 of the roller blank 1. Once the processing of the roller blank 1 has been completed, a greater engraving depth 16 of the engraving 24 can result in a section 17 of the engraved roller 18. This is the case, for example, if the engraving 24 takes place in several steps. As part of the method according to the invention, an engraved roller 18 is produced from a roller blank 1. Here, a roller blank 1 can also be made from an engraved roller 18.

In Figure 3 Three different laser modes are shown schematically. The material can be removed, for example, by means of a laser light 19 that is emitted constantly over time or with pulsed laser light 20. Here, the laser pulses can be directed alternately onto two parallel paths 21, 22 and can also emerge from two laser beams, which can be emitted by two laser diodes.

Figure 4 shows an example of the cross section of a roller 18 to be reprocessed. As part of the method according to the invention for reprocessing a roller 18, an outer layer 23 of the roller 18 is removed and then a method according to the invention for engraving a roller blank 1 formed by the removal is carried out. The removal of the outer layer 23 of the roller 18 can be carried out, for example, by grinding and/or using laser light. In this case, before the outer layer 23 of the roller 18 is removed, an existing engraving 24 can be detected, for example, optically and further processed in the subsequent preliminary process. Figure 5 shows an example of the engraving pattern 25 corresponding to the engraving 24. This engraving pattern 25 merges into itself as an engraving 24 on the roller 18. As part of the method according to the invention for reprocessing a roller 18, the engraving 24 and thus the engraving pattern 25 are recorded and their smallest repeat unit 26 is determined. This detection can also be done using an optical method. From this, the lowest possible thickness 9 of the material layer to be removed, for example the outer layer 23, is determined, so that the engraving pattern 25, here in the form of the engraving 24, also merges into itself on the reprocessed roller 18. The engraving pattern 25 can be found as an engraving 24 on the roller 18 after the method according to the invention has been completed.

The roller 18 can be used to emboss a material after the process according to the invention has been completed. Here, for example, the engraving pattern 25 can be embossed into the material. The roller 18 can be used as a profile roller or counter-profile roller. Profile roller and counter-profile roller can work together. The profile roller can also cooperate with an elastic, for example unprofiled, roller. A defined distance can be maintained between the profile roller and the counter-profile roller. The material can be, for example, a metal, a metal-containing material, a cellulose fabric or a plastic.

A method for engraving a roller blank 1 is therefore proposed, wherein material is removed from the roller blank 1 using laser light, a distance 4 of the focus 5 of the laser light from the longitudinal axis L of the roller blank 1 being set as a function of an optical distance measurement. Furthermore, a method for reprocessing a roller 18 is proposed, wherein after an outer layer 23 of the roller 18 has been removed, a method according to the invention for engraving a roller blank 1 is carried out. It is also proposed to use a roller 18 produced by a method according to the invention to emboss a material.

Reference symbol list

1

Roll blank

2

laser beam

3

Laser diode

4

Distance

5

focus

6

Laser diode

7

laser beam

8th

photodiode

9

thickness

10

Direction

11

surface

12

metal brush

13

Engraving depth

14

brush

15

Section

16

Engraving depth

17

Section

18

roller

19

Laser light

20

Laser light

21

path

22

path

23

layer

24

engraving

25

Engraving pattern

26

repeat unit

L

Longitudinal axis

Claims (21)

Method for engraving a roller blank (1), characterized in that material is removed from the roller blank (1) by means of laser light (19, 20), with a distance (4) of the focus (5) of the laser light (19, 20) from the Longitudinal axis (L) of the roller blank (1) is adjusted depending on an optical distance measurement. Method according to the preceding claim, characterized in that the optical distance measurement is carried out using laser light (19, 20). Method according to one of the preceding claims, characterized in that the roller blank (1) is made of a metal and/or metal-containing material, preferably steel. Method according to one of the preceding claims, characterized in that the engraving pattern (25) is provided as an image file preferably containing gray levels, in particular wherein the gray levels are used to determine the engraving depth (13, 16) and/or intensity of the laser light (19, 20). . Method according to one of the preceding claims, characterized in that transitions between different profile structures are provided with curves with a defined minimum radius of curvature. Method according to one of the preceding claims, characterized in that the engraving is carried out by moving the focus (5) of the laser light perpendicular to the direction (10) of the laser light (19, 20) over the surface (11) of the roller blank (1), in particular wherein the roller blank (1) is rotated about its longitudinal axis (L). Method according to one of the preceding claims, characterized in that the engraving is carried out in several engraving steps, in particular in one engraving step the engraving of the surface (11) of the roller blank (1) at a constant distance (4) of the focus (5) of the laser light (19 , 20) to the longitudinal axis (L) of the roller blank (1) and / or with variable intensity of the laser light. Method according to one of the preceding claims, characterized in that the distance (4) of the focus (5) of the laser light (19, 20) to the longitudinal axis (L) of the roller blank (1) is changed, in particular reduced, between two engraving steps. Method according to one of the preceding claims, characterized in that the roller blank (1) is brushed between two engraving steps, in particular by means of a metal brush (12) and/or using a lubricant. Method according to one of the preceding claims, characterized in that the roller blank is brushed using at least two brushes (12, 14) of different hardness, preferably with softer brushes (12, 14) being used as the engraving depth (13, 16) increases. Method according to one of the preceding claims, characterized in that an engraving depth (13, 16) is more than 1 mm, preferably more than 2 mm, particularly preferably more than 3 mm. Method according to one of the preceding claims, characterized in that the material is removed by means of pulsed laser light (20), in particular wherein the Laser pulses are alternately directed onto two parallel paths (21, 22), preferably two laser beams (2, 7) being used for this purpose. Method for reprocessing a roller (18), characterized in that after removal of an outer layer (23) of the roller (18), a method according to one of the preceding claims is carried out. Method according to the preceding claim, characterized in that the outer layer (23) of the roller (18) is removed by means of grinding and/or using laser light (19, 20). Method according to one of the two preceding claims, characterized in that before the outer layer (23) of the roller (18) is removed, an existing engraving (24) is preferably detected optically and is processed in the subsequent engraving process. Method according to the preceding claim, characterized in that a smallest repetition unit (26) of the engraving (24) is determined and from this the lowest possible thickness (9) of the material layer to be removed is determined, so that the engraving pattern (25) of the reprocessed roller (18) is in passes over oneself. Use of a roller (18) produced by a method according to one of the preceding claims for embossing a material. Use according to the preceding claim, characterized in that a profile roller cooperates with a counter-profile roller and/or an elastic, in particular unprofiled, roller. Use according to one of the preceding claims, characterized in that a defined distance is maintained between the profile roller and the counter-profile roller. Use according to one of the preceding claims, characterized in that the material is a metal and/or metal-containing material. Use according to one of the preceding claims, characterized in that the material is a cellulose fabric and/or a plastic.

Images