EP1593493A1 - Apparatus for engraving cells in printing cylinders by means of laser light - Google Patents

Abstract

Device for engraving cups in printing cylinders comprises a removal element (20) arranged in the region (18) of a contact site (19) of the laser light (14) onto the cylinder. The melt ejection of material of the printing cylinder forming a burr is continuously removed or removed directly after its production. Preferred Features: The removal element is arranged in the region of the contact site of the laser light on the cylinder in the rotary direction of the cylinder. The laser light source (13) and the outlet (15) of the laser light are moved along the cylinder in the axial direction.

Description

The invention relates to a device for engraving Wells in pressure cylinders for gravure printing, comprising at least one laser light source, by means of the laser light for the formation of the wells on the thereby driven in rotation Pressure cylinder is directed, with an output the laser light source in dependence of the rotation of the printing cylinder along the printing cylinder in the axial direction is constantly moved or in each case after Completion of a complete rotation of the printing cylinder in each case by a predetermined amount in the axial direction is moved.

A device for engraving wells for gravure printing is known (unpublished European patent application 04 004 470.3). Both at the engraving of Printing cylinders for gravure printing by means of a mechanical Engraving organ, for example. A diamond stylus, as also when engraving printing cylinders for gravure printing By means of laser light arises in the course of training of Wells in the edge region of the wells to the impression cylinder in which the cups are formed, ridge Forcibly on each mechanically engraved well resulting Burr is either after completion of the complete Engraving the printing cylinder in a separate operation by flat deburring of the entire Pressure cylinder circumference, formed on the wells were removed, and this is then possibly still polished, or a removal device runs in one certain distance subsequently offset to the engraving organ, possibly synchronized with this with respect to the axial Movement of the engraving element along the printing cylinder with, so that at a certain distance in the axial direction to the mechanical engraving organ in the course of the rotation of the Pressure cylinder acted upon by the Abtragorgan Deburring surface of the printing cylinder.

These methods of deburring by means of mechanical Engraving of trained wells on or from printing cylinders are known in the art and are used in This form is continually being used by experts for this purpose executed.

This type of deburring the impression cylinder after training the well is described in the foregoing Shape only possible with a mechanical engraving of the wells.

In the engraving of wells in pressure cylinders by means of Laser light fails the method described above deburring. This is essentially because that a cell made by means of laser light due to the liquefaction of the material and its evaporation in the course of the application of the surface of Printing cylinder, at least in the surface area Metal exists in the edge area of the laser light trained wells always a certain edge bead is formed over the actual surface of the metallic pressure cylinder protrudes, and arising by melting the metal and evaporating of the metal in the center of the laser light beam. Of the Edge area is due to the beam profile of the laser beam just melted, so that there is a Part of the molten metal in the center of the beam profile accumulates, namely the part that does not evaporate becomes.

As with the high-resolution laser engraving, at the on the same area of the printing cylinder, on the previously one single cell which can be created by mechanical engraving could be formed, a variety of wells, For example, 50 and more wells are formed need to find the tracks in which the laser light around the perimeter of the printing cylinder around to form the high-resolution variety of wells much denser in the axial direction of movement of the laser light along the Pressure cylinder abut, would be in a laser engraving after engraving in a track around the printing cylinder around at the beginning of the next track the neighboring, finished engraved track through the above Meltdown of the following track impaired be that engraving in the previous track would be useless, as previously in the previous Trace trained wells by the Schmelzaufwurf the following track partially closed again, at least but so affected in relation to the cup contour would that engraved so with laser light Print cylinder would provide poor print results.

Many attempts have been made in this connection have, for example, the Strählprofil of the laser light in such a way to focus and limit by aperture that the said enamel is no longer so serious. But that had i.d.R. as a result of that, too the effectively emitted power of the laser light at the point of impact was limited to the printing cylinder, so that the possible by means of the laser light itself and also aspired high-resolution laser engraving again in view on the thus achieved good engraving results was significantly limited again.

It is therefore an object of the present invention to provide a Device of the type mentioned above to sowaffen, with which also by means of laser engraving a high-resolution Engraving with the highest standards of sufficient printing results the engraved printing cylinder is possible and also after completion of the laser engraving elaborate Entgratungsmaßnahmen the finished engraved printing cylinder omitted, so that the finished engraved printing cylinder factual immediately after completion of the engraving process for the subsequent printing process is ready, so that the production cost of the finished printing cylinder for printing compared to previous processes for its production can be significantly reduced, the device in principle should be easily executable and also in the prior art known devices appropriate retrofitting i.s: the invention Device can be configured.

Solved the task gem. the invention in that in the area of the impact of the laser light on the Pressure cylinder a removal element is arranged such that with this of the loading of the printing cylinder with laser light for forming the cup, a ridge forming Schmelzaufwurf the material continually and immediately after its creation Will get removed.

The advantage of the solution according to the invention consists essentially in that by means of the Abtragelementes the Engraving trace of all sides of the cup resulting Enamel blasting virtually immediately after its engraving is removed, here track is defined such that this either runs helically around the impression cylinder, or running strictly radially around the impression cylinder and after completing a full turn of the printing cylinder by a corresponding width of the track in the axial direction of the printing cylinder offset one new track is started, etc. Since gem. the invention of Melt-throw immediately after the engraving of the cup in the axial direction of the pressure cylinder on all sides of the Cup is removed, is at a new, finished Engraving track adjacent engraving track of the enamel the first finished engraving track on which the cups the first engraving track are no longer a hindrance.

After completion of the engraving of the entire printing cylinder is the entire impression cylinder thus from the melt-down, i. from the ridge, freed, so that the printing cylinder factually no post-processing for its intended printing function can be used.

In fact, the Abtragelement constructively needs only be assigned to the track, in the course of the engraving process using laser light just provided with wells is or in which the wells are formed. It but are also embodiments of the device possible where multiple laser beams simultaneously apply several tracks parallel to the formation of the wells. To make sure that it is per track per enamel resulting enamel Aufwurf no obstruction causes the adjacent track in the aforementioned sense and thus produced insufficiently engraved wells are, it is advantageous, the Abtragelement directly in the area of the impact of the laser light on the impression cylinder in the direction of rotation of the impression cylinder to be arranged below, so that in fact immediately after the emergence of the cup by means of laser light the Melting-up can be removed.

In principle, any laser light source can be subject to the proviso that this is a sufficiently high laser energy for Execution of the engraving according to the invention is capable of delivering, for the purposes of the invention be sent. In this case, the laser light source For example, deducted from the area of the impact of the laser light be arranged on the printing cylinder, wherein the generated laser light, for example, via a light guide to a Optics for focusing the laser light and possibly also for collimating the laser light can be passed, the immediately in the region of the location of the laser light is arranged on the printing cylinder. The light guide can also be active in this construction Fiber lasers are designed to absorb the energy of the laser light at the point of impact of the laser light on the Increase pressure cylinder.

With regard to the object initially stated, namely to build up the device simply and effectively can, it is beneficial, the laser light source not offset from the area of the impact of the laser light on the printing cylinder deposited form, but at least the light source and the output of the laser light, He is. of the foregoing said the optics of Laser device comprises, summarized along the Form pressure cylinder movable in the axial direction, i.e. advantageously the output of the laser light and to combine the laser light source in one unit, on a support parallel to the axis Rotary axis of the printing cylinder in the axial direction and is movable forth. This embodiment has the advantage that the entire unit in case of malfunction and maintenance exchanged and replaced with a new one can, so that an interruption of the engraving process by means of this advantageous embodiment of the device can be reduced to a minimum and maintenance and maintenance of the laser unit greatly simplified can be.

As the Abtragelement to eliminate the Schmelzaufwurfs locally with the place of origin, i. the place of education the cup by Laserlichtbeaufschlagung, correlated, it is advantageous to drive-coupled the Abtragelement along with at least the output of the Laser light along the printing cylinder movable to design, so that a separate drive of the Abtragelementes in this advantageous embodiment of the device and thus also a separate control of the Abtragelementes with regard to its movement in the axial Direction to the printing cylinder can be omitted. in principle But it is also possible, the movement of the Abtragelementes along the printing cylinder from the movement to decouple the laser light along the printing cylinder, i.e. provided with its own drive.

In principle, any suitable and suitable shaped Abtragelemente to solve the inventive Task be provided. It has proved to be beneficial proved, the Abtragelement at his to the impression cylinder to train directed end in the form of a scraper, and in the same way as these in the span lifting Machining of metal parts used by cockroaches become.

Normally, the removal element is always included the processing of the printing cylinder by means of laser light for forming the cups on the impression cylinder, and although by means of a suitably adjusted force, the et al also on the regular metallic material of the Shut down pressure cylinder in which formed the wells become. Since the Abtragelement but in the course of his Abtragtätigkeit worn, it is advantageous, the Abtragelement controlled to form an abutment on the impression cylinder, so that during the engraving of the Printing cylinder of wear are taken into account can and constantly controlled with consistent Pressure can rest on the printing cylinder. To the Replacing and adjusting it can be beneficial to the Abtragelement also develop such that it from the Pressure cylinder can be moved away.

In a further advantageous embodiment of the device the ablation element is supported by a Spring force on the surface of the printing cylinder sliding via a support element, which takes into account the circumstance can be worn that the Abtragelement For example, as a result of wear during the intended Operation as well as the possibly accompanying change the Schabewinkel not uncontrolled to Can move surface of the printing cylinder and this as a result would damage if necessary.

To prevent the support element itself the surface Impact of the impression cylinder, it may be advantageous be, the support surface of the support element of a Hard material with good sliding properties form or to form the support surface of diamond.

It can be useful in principle, the appropriate Areas of the surface of the impression cylinder that are straight have been engraved, and their Schmelzaufwurf by the Abtragelement has been eliminated according to the invention, subsequently to grind, i. the original goodness the surface of the impression cylinder before execution of the At least restore engraving. A grinding element can thus directly to the area of the Abtragelementes arranged downstream in the direction of rotation of the printing cylinder be that the area of the eroded Schmelzaufwurfs grinds. At a highly different advantageous Embodiment of the invention is the removal element itself formed in the form of a grinding element, i. of the Melt-throw is removed by grinding, whereby a separate additional grinding process after the removal process can be omitted.

Fig. 1

in stark schematisierter Form eine Vorrichtung zur Gravur von Näpfchen in Druckzylindern mittels Laserlicht zur Ausbildung von Näpfchen und ein Abtragelement, das den als Schmelzaufwurf entstehenden Grat nach der Ausbildung der Näpfchen entfernt,

Fig. 2

eine Einheit, bestehend aus Laserlichtquelle und einem Ausgang, über den das Laserlicht austritt, das zur Ausführung der Gravur von Näpfchen auf den Druckzylinder gerichtet ist,

Fig. 3

in Form eines Blockschaltbildes eine. Einheit, mittels der Laserlicht erzeugt und auf den Druckzylinder gerichtet wird,

Fig. 4

eine schematisierte Vorrichtung zur Gravur von Näpfchen in der Seitenansicht, wobei eine Lasereinheit und ein Abtragelement auf einem radial und axial bewegbaren Trägerelement, das nach Art eines Supports ausgebildet ist, angeordnet sind,

Fig. 5

in der Seitenansicht das Abtragelement im Zusammenwirken mit dem Druckzylinder in vergrößerter Darstellung,

Fig. 6

eine Darstellung des Abtragelementes im Zusammenwirken mit dem Druckzylinder gemäß Fig. 5, jedoch in der Draufsicht,

Fig. 7

eine Darstellung des Abtragelementes und eines Stützelementes im Zusammenwirken mit dem Druckzylinder in der Draufsicht,

Fig. 8

ein typisches Gravierraster mit einer Mehrzahl von mittels der hochauflösenden Lasergravur erzeugten Näpfchen und

Fig. 9

eine vergrößerte Darstellung der Fig. 4 mit parallel verlaufend angedeuteten Gravierspuren zur Erläuterung der Erfindung.

The invention will be described below with reference to the figures with reference to an embodiment in detail. Show:

Fig. 1

in a highly schematized form, a device for engraving wells in printing cylinders by means of laser light for the formation of wells and a removal element which removes the burr formed as a melt throw after the formation of the wells,

Fig. 2

a unit consisting of a laser light source and an output, through which the laser light emerges, which is directed to the execution of the engraving of wells on the printing cylinder,

Fig. 3

in the form of a block diagram one. Unit by means of which laser light is generated and directed onto the printing cylinder,

Fig. 4

a schematic device for engraving cups in the side view, wherein a laser unit and a removal element are arranged on a radially and axially movable support element, which is designed in the manner of a support,

Fig. 5

in side view, the removal element in cooperation with the printing cylinder in an enlarged view,

Fig. 6

5 shows an illustration of the removal element in cooperation with the impression cylinder according to FIG. 5, but in plan view,

Fig. 7

a representation of the Abtragelementes and a support element in cooperation with the pressure cylinder in plan view,

Fig. 8

a typical engraving grid with a plurality of cells produced by the high-resolution laser engraving and

Fig. 9

an enlarged view of FIG. 4 with parallel indicated engraving tracks to explain the invention.

First, reference will be made to the illustration of Fig. 1, in cross section, a device 10 for engraving of wells 11 in a pressure cylinder 12 for the Gravure shows. In the device 10 is a laser light source 13 provided by means of the laser light 14 for Training the wells 11 is generated. The printing cylinder 12 is by means not shown here drive means drivable and is at its intended Rotation at the intended speed of rotation in the direction of arrow 22, the direction of rotation indicates the printing cylinder 12, rotated. The axis 16 the impression cylinder is suitably by means of here not shown bearing in the device 10th held. The basic structure of such Device 10 is known in the art, so that does not need to be discussed further.

In the embodiment of the device shown in Fig. 1 10, the laser light source 13 is offset from the Arranged in the region of the impact location 19 of the laser light 14, wherein the connection of the laser light source 13 with the output 15, from the laser light 14, appropriately focused and collapses, exits, via a light guide 29, the example. As a fiber laser or as a simple light guide (Laser fiber) may be formed with the output 15 can, can be done.

In the area 18, i. in the immediate vicinity of the place of arrival 19 of the laser light 14 on the printing cylinder 12, an ablation element 20 is arranged, whereupon further below in detail in connection with the function of Abtragelementes 20 is received.

Unlike shown in Fig. 1, and the Laser light source 13 and the output 15 of the laser light be summarized in a unit 23, cf. Figs. 2 and 3, so that not, as in Fig. 1, only the output the laser light source in dependence of the rotation of the printing cylinder 12 along the printing cylinder in the axial direction 17, cf. Also Fig. 5, to be moved but the whole unit 23. To move in axial direction 17 of the output 15, as shown in Figure 1, or to move the unit 23 in which the Output 15 of the laser light 14 and the laser light source 13 are summarized, a support member 110 is after Provided type of support that carries this, wherein the carrier element 110 in the axial direction 17 along the Pressure cylinder 12 is moved. The movement of the exit 15 or the unit 23 takes place in dependence of the rotation of the printing cylinder 12 along the printing cylinder 12th in the axial direction 17 either by means of a constant feed, so that from a helical Engraving track 27, which will be discussed further below is, cf. also Fig. 9, results, or it takes place after completion of a complete rotation of the Cylinder 12 a feed in the axial direction 17 to a predetermined amount corresponding to the width of the Lane 27, whereby each full circle engraving traces 27th be formed.

In Fig. 4, starting from the representation of Fig. 1, which is based essentially on the representation of the laser light source 13 and the exit of the laser light 14 off the output 15, in a highly schematic Form the device 10 again in side view shown. The laser light source 13 is here as a unit 23 trained. The unit 23 is on a support element 100 arranged, the kind of a support is trained. The carrier element 100 is in both axial direction 17 as well as in the radial direction 170 movable. The movement both in the axial direction 17 as also in the radial direction 170 is longitudinal guides 102, which formed as a slide guide and / or rollers could be. On the part of the carrier element 100, which also carries the unit 23, is the Abtragelement 20th articulated about a head 200, the head 200 about a joint 105, which is a substantially axial Direction 17 has parallel axis of rotation, rotatable is. By means of a spring element 103, the head 200 and thus the removal element 20 with suitably adjusted Pressure to the printing cylinder 12 are pressed. by virtue of the displaceability of the support element also in radial direction 170, the Abtragelement 20 also on different diameter of the printing cylinder 12th be easily adapted. At the beginning of the removal process, what will be discussed further below, the Abtragelement 20 with suitable adjustable pressure in one Target position shifted relative to the printing cylinder 12, so that when this is achieved and a suitable one Pressure of the Abtragelementes 20 is set, the removal process can start.

Fig. 5 shows only a partial enlarged Representation of FIG. 4 is.

The removal element 20, cf. Figures 1, 4 and 5, is For example, in the form of a scraper, wherein the Abtragelement 20 controlled to rest on the impression cylinder 12 and can be moved away from it (not shown). Also, the Abtragelement 20 and possibly his holding and Control mechanism are either together with the Unit 23 and the output 15 of the laser light 14 along the printing cylinder 12 moves in the axial direction 17, but it is also possible for the Abtragelement 20th including his investment and swivel mechanism a separate Leadership or for a separate drive provide, by means of which the Abtragelement 20 along the Pressure cylinder 12 moves in the axial direction 17 can be. The removal element 20 may be provided with a support element Be provided 25, with which it is on the surface 24 of the printing cylinder 12 can be supported. The Support surface 26 of the support member may be made of a suitable abrasion resistant, having good sliding properties Material consist, for example. Carbide or diamond. The Abtragelement 20 may in the form of a scraper, but also in the form of an abrasive element with diamond as Abrasives can be stocked, or even in the form of a Polierelementes be formed.

Figures 6 and 7 show in plan view in one Part of the interaction of the Abtragelementes 20 with the printing cylinder 12. The function of the Abtragelementes 20 in cooperation with the engraving itself will be described in detail below.

The unit 23, from which either the output only 15 along the axial direction 17 of the printing cylinder the said support can be moved or the entire Unit 23 itself, includes the actual laser light source 13, for example, from at least one laser diode, but also from any other suitable laser source can exist. To operate the laser light source 13 is from a power supply 30 supply voltage supplied by the laser light source 13 generated laser light, as above indicated, is given to the output 15, the optical Means such as lenses and possibly covers to one suitably focused and possibly collimated beam of Laser light 14 to produce, wherein the laser light 14 on the surface 24 of the printing cylinder 12 is given. This is done by means of a control and regulating device 31, which into the overall control and regulation function the device 10 is embedded. This one Control of the device 10 and the control and regulation the unit 23 for the previously listed Components are known per se in the art, will not be discussed further here.

Reference will now be made to the illustrations of Fig. 8 and 9, wherein Fig. 8 a for the formation of wells 11 in the surface 24 of the printing cylinder 12 for the gravure typical engraving grid in context with a high-resolution, direct laser engraving shows.

As already indicated above, it rotates during execution the engraving of the printing cylinder 12 in the direction of the arrow 22. This will be the execution of the engraving individual Well 11, lane 27, for lane 27, in the direction of rotation 22 Engraved one after the other.

In the picture acc. Fig. 9 below is schematically the beam profile 28 of the laser beam 14 at the impact 19 on the Pressure cylinder 12 shown. As can be seen, overlap the beam profiles 28 from track 27 to track 27th Due to physical laws it is not possible, the beam profile 28 to the edges of the wells 11 abruptly restrict, as it is, for example, in a cross section desirable with respect to the width of the beam would be, i. to aim for a rectangular course. Since this is not possible, the beam affects the laser light 14 of a track 27, the adjacent Lane 27, as this also schematically in Fig. 9 below is indicated. Thus, normally arise in the respective edge regions of the wells 12 and thus In the course of engraving in each track 27 smelting drops 21 from the molten metal of the printing cylinder 12, Lane 27 for track 27, so that by the formation of each adjacent wells 11 each adjacent tracks 27, the wells 11 in the previous track partially again filled with solidified printing cylinder material become. To prevent this melt throw 21, is in the region 18 of the impingement 19 of the laser light 14 on the printing cylinder 12, the said Abtragelement 20th arranged. The arrangement of the Abtragelementes 20 is chosen such that the material of the printing cylinder 12, i.e. the enema 21, immediately after its formation Will get removed. The removal element 21 is direct in the region of the impact location 19 of the laser light 14 on the printing cylinder 12 in the direction of rotation 22 of the Pressure cylinder 12 is arranged below, as is made Fig. 1 and illustrated in FIG. 9 can be seen.

Regardless of whether the metallic material of the Printing cylinder 12, in which the wells 11 are engraved, Copper, chrome or even zinc, the melt can be 21 are completely removed according to the invention.

LIST OF REFERENCE NUMBERS

10

contraption

100

support element

101

bearing block

102

guide

103

spring element

105

joint

106

bed

11

wells

12

pressure cylinder

13

Laser light source

14

laser light

15

output

16

Axle - pressure cylinder

17

axial direction

170

radial direction

18

Area

19

impingement

20

excavating

200

head

201

feed motion

21

Schmelzaufwurf

22

direction of rotation

23

unit

24

Surface - impression cylinder

25

support element

26

support surface

27

track

28

beam profile

29

optical fiber

30

Power supply means

31

Control and regulation device

Claims (14)

Device (10) for engraving cups (11) in printing cylinders (12) for gravure printing, comprising at least one laser light source (13), by means of the laser light (14) for forming the cups (11) on the printing cylinder (12) driven thereby in rotation. is directed, wherein an output (15) of the laser light source (13) in response to the rotation of the printing cylinder (12) along the printing cylinder (12) in the axial direction is constantly moved or after completion of a complete rotation of the printing cylinder (12) by each a predetermined amount in the axial direction (17) is moved, characterized in that in the region (18) of the impact location (19) of the laser light (14) on the printing cylinder (12) an ablation element (20) is arranged such that with this the forming of the pressure cylinder (12) with laser light (14) to form the cup (11), a burr-forming enamel topping (21) of the material of the printing cylinder (12) for is removed immediately after its formation. Apparatus according to claim 1, characterized in that the Abtragelement (21) immediately in the region of the impact location (19) of the laser light (14) on the printing cylinder (12) this in the direction of rotation (22) of the printing cylinder (12) is arranged below. Device according to one or more of claims 1 or 2, characterized in that at least the laser light source (13) and the output (15) of the laser light (14) are moved together along the printing cylinder (12) in its axial direction. Apparatus according to claim 3, characterized in that at least the output (15) of the laser light (14) and the laser light source (13) in a unit (23) are combined. Device according to one or more of claims 1 to 4, characterized in that the removal element (20) is drive-coupled together with at least the output (15) of the laser light (14) along the printing cylinder (12) is movable. Device according to one or more of claims 1 to 5, characterized in that the ablation element (20) is designed in the form of a scraper at its end facing the pressure cylinder (12). Device according to one or more of Claims 1 to 6, characterized in that the removal element (20) can be moved in a controlled manner for bearing against and away from the impression cylinder (12). Device according to one or more of claims 1 to 7, characterized in that the ablation element (20) on the surface (24) of the printing cylinder (12) slidably supported by a support member (25). Apparatus according to claim 8, characterized in that the support element (25) has a support surface (26) made of diamond. Device according to one or more of claims 1 to 9, characterized in that the removal element (20) is designed in the form of a grinding element. Device according to one or more of claims 1 to 10, characterized in that at least the region of the surface (24) of the printing cylinder (12), in which the wells (11) are formed, consists of metallic material. Apparatus according to claim 11, characterized in that the metallic material is copper. Apparatus according to claim 11, characterized in that the metallic material is chromium. Apparatus according to claim 11, characterized in that the metallic material is zinc.

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