EP2200824A1

EP2200824A1 - Engraving head for engraving printing formes

Info

Publication number: EP2200824A1
Application number: EP08802227A
Authority: EP
Inventors: Dieter Fangmeyer; Jörg WOLTER
Original assignee: Hell Gravure Systems GmbH and Co KG
Current assignee: Hell Gravure Systems GmbH and Co KG
Priority date: 2007-09-20
Filing date: 2008-09-16
Publication date: 2010-06-30
Anticipated expiration: 2028-09-16
Also published as: DE102007048668A1; DE102007048668B4; EP2200824B1; JP2010538874A; WO2009040013A1

Abstract

The invention relates to an engraving head for engraving printing formes, comprising an engraving tool holder which is arranged on a shaft of a vibrating drive unit and is used for an engraving tool. The aim of the invention is to reduce the risk of the engraving tool breaking and/or the shape of the cup being distorted while preferably increasing the productivity of an engraving tool, especially allowing the engraving tool to be operated at a higher operating frequency. According to the invention, said aim is achieved in a first embodiment in which the engraving tool holder is moved closer to the printing forme in relation to a radial orientation relative to the shaft, along the major part of the length of the holder, from the attachment point on the shaft to the free end of the holder.

Description

Engraving head for engraving printing forms

The invention relates to an engraving head for engraving printing forms, comprising a stylus holder for an engraving stylus arranged on a shaft of a vibration drive.

From DE-C-2508734 an electronic engraving machine for engraving printing cylinders by means of an engraving element is already known. The engraving element with an engraving stylus controlled by an engraving control signal as a cutting tool moves along a rotating impression cylinder in the axial direction. The engraving stylus cuts a sequence of cells arranged in a printing grid in the lateral surface of the printing cylinder. The engraving control signal is formed by superposition of a periodic screen signal for generating the print screen with image signal values which define the tonal values to be reproduced between "black" and "white". While the raster signal causes an oscillating stroke movement of the engraving stylus to engrave the wells arranged in the printing raster, the image signal values determine the cutting depths of the engraved cells in accordance with the tone values to be reproduced.

In DE-A-23 36 089 an engraving member is specified, which essentially comprises a rotary system and an electromagnetic drive for the rotary system. The turning system consists of a shaft, an armature, a bearing for the shaft, a return element and a damping device. On the shaft, a hebeförmörmige stylus holder is attached, which carries the engraving stylus. The electromagnetic drive for the rotary system has an exciting coil applied to the engraving control signal and a stationary permanent magnet in whose air gap the armature of the rotary system moves. The drive causes a small angle oscillating rotational movement of the shaft, and the stylus holder with the engraving stylus performs the engraving of the wells a corresponding oscillating stroke movement in the direction of the lateral surface of the printing cylinder. In a conventional engraving machine, the components of the engraving element are arranged with respect to the printing cylinder to be engraved such that the oscillating shaft of the rotating system is aligned approximately tangential to the printing cylinder and the lifting movement of Engierstichels takes place on a circular arc around this shaft. Such a circular arc movement of

Engraving stylus in its stroke is in principle also given when the shaft of the rotary system, as disclosed in DE 199 52 996 A1, is stored substantially parallel to the longitudinal axis of the printing cylinder.

The pronounced curving stroke movement of the engraving stylus in the known systems causes the engraving stylus not only immersed substantially perpendicularly in the printing plate surface to excavate a well or engraving a stroke, but also always this lifting movement, depending on the orientation of the shaft Sideways component or a pitch component. As a result, the engraving stylus penetrates obliquely into the printing plate surface, which falsifies the desired cup shape. In addition, this additional movement component increases the risk of grave scuttles. In addition, with the known engraving heads, which are operated in the region of a self-resonance of the engraving head, only maximum operating frequencies of about 4000 to 5000 Hz can be achieved. However, this limits the productivity of such an engraving system.

Although this type of production restriction of a gravitational stylus vibrating in the region of natural resonance has already been recognized in JP 9-24598, this document merely discloses the proposal to decouple the stylus holder mechanically from the shaft with respect to a vibration transmission in order to reduce the area of the shaft Stichelhalters of the engraving head and its self-resonance independent to be able to operate at a higher natural resonance of the Stichelhalters. The engraving system disclosed therein, however, is very unstable and of little reproductive design and neglects the above-described problems of cup shape adulteration and the risk of stylus breakage and even increases these problems. US 1 785 883 A discloses a stylus holder in the form of an angled two-armed lever, wherein the stylus is arranged at the free end of a lever arm, while the end of the other lever arm is attached to the armature of a magnetic coil. The magnetic coil pivots the stylus holder about an arranged between the lever arms pivot axis whose orientation is not specified in relation to the printing plate. The stylus holder extends along its entire length between the pivot axis and its free end carrying the stylus along a pivot axis radius extending from the pivot axis approximately through the center of the lever arm to the free end. Similar to the stylus holder from DE 199 52 996 A1, the stylet performs a circular arc movement, so that its stroke movement depending on the orientation of the pivot axis has a sideways or pitch component, which leads to an oblique penetration of the stylus in the printing form surface.

The invention is therefore based on the object to reduce the Stichelbruchgefahr and / or the Näpfchenformverfälschung and preferably also to increase the productivity of Engierstichels, in particular to operate the engraving stylus at a higher operating frequency.

This object is achieved in that the Stichelhalter over the greater part of its extension between the shaft and its free end on the side adjacent to the printing forme arranged by its free end shaft radius and thereby moved closer to the printing forme zoom.

According to the invention, therefore, in the stylus holder the portion of a region preceding its free end carrying the engraving stylus is moved closer to the printing plate surface so that this region of the stylus holder, which is important for the stroke movement of the engraving stylus, has a more tangential orientation to a cylindrical or a parallel orientation to obtain a flat printing surface. This inventive design allows the stylus holder, a vibration axis or a vibration Form the area that is shifted closer to the total pressure plate surface as the shaft, which thereby loses importance as a vibration center, in such a way that just the more important area of the Stichelhalters with the tangential or parallel orientation to the printing plate surface more essential for the engraving Part of the vibration in itself performs. As a result, in the case of the stroke movement newly produced according to the invention as a result, a curvilinear course largely disappears, and the engraving stylus penetrates straight perpendicularly, orthogonally to the tangential surface of the cylindrical printing form surface or to the parallel surface of a flat printing surface in this printing surface. In addition, it is also possible by the inventive design of the Stichelhalters to operate the Stichelhalter wholly or in sections in the range of a higher natural frequency, for example above 8000 Hz, preferably at an operating frequency of about 11000 to 12000 Hz. Thus, it is inventively preferably by a new found resonance a new oscillation approach.

A next development of the engraving head according to the invention, which favors the above-described effect according to the invention, is characterized in that a root region of the needle holder attached to the shaft is designed as a cantilever projecting in the direction of the printing forme, between the root region and the engraving stylus arranged portion of the Stichelhalters with respect to the shaft radius by the free end of the Stichelhalters closer to the printing form zoom to move.

Thus, this embodiment of the invention provides by a shaping or arrangement of the Stichelhalters invention a division of the Stichelhalters into sections of which at least one important for the Hubbewegungsverlauf the engraving stylus area of the Stichelhalters is moved closer and with a more favorable orientation to the printing plate surface or the Stichelhalter total or a section thereof is brought closer by an inventive arrangement closer and with a more favorable orientation to the printing plate surface and also a new oscillation approach of described type allows.

A further preferred embodiment of the engraving system according to the invention provides that the stylus holder has a curved or bent course when viewed in an axial direction of the shaft.

It is preferably provided that the course of the Stichelhalters has substantially an L- or J-shape, wherein preferably the shorter lower portion of this form forms the attached to the shaft root area.

Another possible embodiment according to the invention of the engraving system according to the invention provides that an intermediate piece is provided for the same purpose. The Stichelhalter must then not necessarily have a special shape itself, but is oriented by its inventive arrangement wholly or partially cheaper.

In particular, it can be provided that the stylus holder is attached via a lever linkage to the shaft.

The engraving head according to the invention is preferably characterized in that a vibration axis arranged closer to the shaft than the shaft is formed substantially parallel to the shaft, which is achieved in particular by a shaping according to the invention and / or by a real additional axis, for example as part of a lever linkage can.

A further development of the engraving system according to the invention is characterized in that the stylus holder at least partially forms a resonance system following a natural resonance of the engraving head or at least a part of a resonance system following a natural resonance of the engraving head. In this development, preferably in consideration of the aforementioned aspects, achieved by a shaping and / or arrangement of the Stichelhalters that improved vibration excitation of the Stichelhalters, in particular his engraving stylus bearing free end, is achieved. Thus, it is possible by the inventive design and / or arrangement of the Stichelhalters to operate the Stichelhalter wholly or in sections in the region of a higher natural frequency, for example, preferably at an operating frequency of about 11000 to 12000 Hz, by a displacement of the Stichelhalters or at least a section away from the shaft towards the printing form. In addition, a portion of the stitch holder and / or an element of its arrangement could be weakened.

A further development of the invention is characterized in that, when viewed in a radial direction of the shaft, the stylus holder tapers towards its free end at least in a region between its root region attached to the shaft and its free end, wherein it is preferably whip-like , This also promotes a vibration behavior with a higher operating frequency, possibly also by a mass reduction. The stylus holder could also or alternatively be made of aluminum, titanium, metal matrix composite, carbon fiber plastic, ceramic or the like, for example. The axis or shaft could be made of hard metal.

Another development of the invention is characterized in that at least one area of the Stichelhalters and / or at least a portion of an intermediate piece has a material weakening, which could in particular decouple the engraving stylus carrying section of the Stichelhalters more vibration from the shaft and a vibration behavior with a higher operating frequency and in particular could also favor a novel vibration approach according to the invention. It can also be provided for this purpose leaf spring-like areas and / or storage elements or be designed as weakened areas.

In particular, for mass reduction, but at the same time also for stabilization, it could be preferably provided that at least one region of the stitch holder has a material cavity.

Another embodiment of the invention provides that the extension of the shaft and the extension of the Stichelhalters are oriented transversely to each other.

A preferred embodiment of the invention is characterized in that the extension of the shaft is aligned substantially parallel to the longitudinal axis of a cylindrical printing form, which could be achieved, for example, similar to the cited DE 199 52 996 A1, but taking into account the inventive design and / or arrangement of the Stichelhalters. Embodiments from which further inventive features may result, to which the invention is not limited in scope, are shown in the drawing.

Show it:

Fig. 1 is a block diagram of an electronic engraving machine with a

Engraving organ and with a printing forme cylinder (according to the state of

Technology),

2 shows a first basic embodiment of the engraving element according to the invention,

3 is a cross-sectional view of a second embodiment of an engraving element according to the invention with a printing form cylinder,

Fig. 4 is a perspective view of a third embodiment of an engraving according to the invention and Fig. 5 is a perspective view of a fourth embodiment of an engraving according to the invention.

Fig. 1 shows a block diagram of an electronic engraving machine according to the prior art.

A printing form cylinder 1 is driven in rotation by a rotary drive 2. An engraving element 3 with a engraving stylus 4 as a cutting tool is mounted on an engraving carriage 5, which is movable by means of a driven by a feed drive 6 spindle 7 in the axial direction of the plate cylinder 1. The engraving element 3 is equipped, for example, with an electromagnetic drive for the engraving stylus 4.

Engraving stylus 4, controlled by an analog engraving control signal GS on a line 8, engravably cuts a sequence of cups and / or lines (intaglio) arranged in a printing grid in the lateral surface of the rotating printing plate cylinder 1, while the engraving carriage 5 engages with the engraving element 3 for planar engraving moved stepwise or continuously in the axial direction of the printing form cylinder 1 along.

The engraving control signal GS is generated in an engraving amplifier 9 by superposition of a periodic screen signal R for generating the printing screen on a line 10 with image signal values B on a line 11, which define the tonal values of the cells to be engraved between "light" and depth " R causes an oscillating lifting movement of the engraving stylus 4 to engrave the cups arranged in the printing grid, the image signal values B determine the depths of cut of the cells in accordance with the tonal values to be reproduced The image signal values B are in a D / A converter 12 from engraving data GD of the printing form to be engraved The engraving data GD are stored in an engraving data memory 13, from which they are read by the engraving line and supplied to the D / A converter 12 via a data bus 14.

The predetermined by the print grid engraving of the wells on the plate cylinder 1 are defined by the location coordinates x and y of the lateral surface of the plate cylinder 1 associated coordinate system whose X-axis in the axial direction and its Y-axis in the circumferential direction of the plate cylinder 1 are aligned. The feed drive 6 generates the x-location coordinates and a mechanically coupled to the printing form cylinder 1 pulse generator 15, the y-location coordinates. The x-y location coordinates are supplied via lines 16 to an engraving control unit 17. The engraving control unit 17 generates the raster signal R on the line 10, read addresses for the engraving data memory 13 on an address bus 18 and signals for controlling and synchronizing the engraving process.

FIG. 2 shows a first basic embodiment of the engraving element 3 according to the invention with a mirror-symmetrical structure with respect to the center of the longitudinal axis of the shaft 20. In this embodiment, both ends of the shaft 20 are formed as torsion bars 21a, 21b which are fixed in stationary clamps 28a, 28b. An engraving holder 24 according to the invention with the engraving stylus 4 is attached to the shaft 20 at the center of the longitudinal axis. Mirror symmetrical to the stylus holder 24, two anchors 26a, 26b and two damping devices 23a, 23b are present. Advantageously, the shaft 20 is still mounted in the center of its longitudinal axis in a shaft bearing 22, wherein the shaft bearing 22 is arranged for example in the region of the Stichelhalters 24. Preferably, the anchors 26a, 26b are located no further than about 25 mm from the engraving stylus holder 24 and define and thus define a unique resonant region of the stylus holder 24 with a new vibration lug. It is within the scope of the invention, for example, to replace the torsion bars 21a, 21b acting as restoring elements by spoke bearings, for example according to German Utility Model Application G 298 12 163.8.

The stylus holder 24 can be seen in Fig. 2 only in plan view, but has a bent shape in principle, such as the stylus holder in Fig. 3. It has a material cavity 19 for reducing material, which can also serve to receive the shaft bearing 22.

3 shows a sectional view through a second embodiment of an engraving element 3 according to the invention and the printing form cylinder 1.

In the area of a non-illustrated stationary permanent magnet of the drive for the shaft 20, two opposing, U-shaped sheet metal packages 31 are arranged, which are arranged to each other, that between the poles forming air gaps 32 arise. In the air gaps 32 shown, the armature 26b moves in front of a damping device 23b of the rotary system. At base portions 33 of the laminated cores 31 excitation windings 34 are mounted, of which only one coil side is shown. The excitation windings 34 are traversed by the engraving control signal GS.

The stitch holder 24 according to the invention shown in Fig. 3 is bent to an L-shape having leg portions 24b and 24c, wherein the leg portion 24b is disposed with its root portion 24a on the shaft 20. By the leg portion 24 b, which projects from the shaft 20, the viewing kelabschnitt 24 c is moved away from the shaft 20 and is flatter or tangential and also oriented closer to the printing plate 1. In particular, a large part of the stylus holder 24 is pulled out of the radial direction 29 relative to the shaft 20, corresponding approximately to the connecting line between engraving stylus 4 and shaft 20. Fig. 4 shows a perspective view of a third embodiment of a Stichelhalters 24. The Stichelhalter has substantially an L or J-shape, which appears rounded rounded, while the L-shape of the Stichelhalters 24 appears folded in Fig. 3. An X in FIG. 4 indicates where approximately the engraving stylus 4 is placed, but on the side of the stylus holder 24 facing away from the observer of FIG. 4. The stylus holder 24 has a non-rotatable, rotationally secure bore 30 for correspondingly positive passage of a section a shaft 20 on.

5 shows a perspective view of a fourth exemplary embodiment of a stylus holder 24 according to the invention. The stylus holder has a cantilever arm or an intermediate piece 24d, which radially protrudes from the shaft 20, for which a leadthrough 30 is provided, the further region 34 of the stylus holder 24 and brings in a flatter orientation to a printing plate, so that the engraving stylus 4 can penetrate more vertically into the printing plate. In addition, the intermediate piece 24d has a material-weakened region 35, which is formed like a leaf spring, in order to decouple the region 34 of the Stichelhalters 24 from the region of the shaft 20 vibration technology. In addition, laterally at the region 34, further leaf spring elements 37 for an additional vibration bearing with wave function for the vibration of

Range 34 may be provided. This also achieves a further decoupling of the shaft 20 and at the same time enables a high natural vibration frequency of the region 34 through a new oscillation approach.

It could also be the area 34 alone in the embodiment of FIG. 5 as

Stichelhalter be addressed which is arranged at a total of an intermediate piece 24d, for example, is screwed and then itself has no L-shape or J-shape.

The stylus holder 24 or 34 could also be arranged by means of a complicated lever linkage on the shaft 20 and be moved away from it and decoupled, in particular by lever joints. Both embodiments of the Stichelhalters in Figs. 4 and 5 have a shape which tapers in its front view towards its free end, substantially approximately triangular. A rejuvenation could also be done in cross section. The shape may be tongue or whip-like rejuvenate.

Claims

claims

An engraving head for engraving printing forms, comprising a stylus holder attached to a shaft of a vibratory drive for an engraving stylus, characterized in that. in that the stylus holder (24) is arranged over the greater part of its extent between the shaft (20) and its free end on the side adjacent to the printing forme (1) of a shaft radius (29) running through the free end and thereby closer to the printing form (1 ) is shifted closer.

2. engraving head according to claim 1, characterized in that on the shaft (20) fixed root portion (24 a) of the Stichelhalters (24) is formed as a in the direction of printing plate (1) projecting cantilever to one between the root area (24 a) and the engraving stylus (4) arranged region (24c) of the Stichelhalters (24) with respect to the shaft radius (29) closer to the printing plate (1) to move zoom.

3. engraving head according to one or more of the preceding claims, characterized in that the stylus holder (24) when viewed in an axial direction of the shaft (20) has a bent or kinked

History has.

4. Engraving head according to claim 3, characterized in that the course of the Stichelhalters (24) has a substantially L- or J-shape.

5. Engraving head according to one or more of the preceding claims 1 to 3, characterized by a Heranverlagerung of the sickle holder (24) to the printing plate (1) between the shaft (20) and the stylus holder (24) provided intermediate piece (24d).

6. Engraving head according to claim 5, characterized in that the stylus holder is attached via a lever linkage to the shaft.

7. Engraving head according to one of the preceding claims, characterized in that substantially parallel to the shaft (20) one of

Printing form (1) closer than the shaft (20) arranged vibration axis is formed.

8. Engraving head according to one of the preceding claims, characterized in that the stylus holder (24) at least partially forms a resonant system with respect to a base resonance of the engraving increased self resonance following resonance system or at least part of a comparison with a fundamental resonance of the engraving increased self-resonance system following.

9. Engraving head according to one of the preceding claims, characterized in that the stylus holder (24) when viewed in a radial direction of the shaft (20) at least in a region (24c) between a at the shaft (20) fixed root portion (24a) and its free end rejuvenated to its free end.

10. engraving head according to claim 9, characterized in that the stylus holder is formed like a whip.

11. engraving head according to any one of the preceding claims, characterized in that at least a portion of the Stichelhalters (24) and / or at least a portion of between the shaft (20) and the Stichelhalter (24) provided intermediate piece (24d) a material weakening (35) having.

12. Engraving head according to one of the preceding claims, characterized in that at least a portion of the Stichelhalters (24) a Material excavation (19).

13. Engraving head according to one of the preceding claims, characterized in that the stylus holder (24) extends transversely to the shaft (20).

14. Engraving head according to one of the preceding claims, characterized in that the shaft (20) is arranged parallel to the longitudinal axis (27) of a cylindrical printing form (1).