Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C1/00—Forme preparation
  • B41C1/02—Engraving; Heads therefor
  • B41C1/04—Engraving; Heads therefor using heads controlled by an electric information signal
  • B41C1/045—Mechanical engraving heads

Definitions

• the invention relates to the field of electronic reproduction technology and relates to an engraving element for an electronic engraving machine for engraving printing cylinders and an electronic engraving machine with such an engraving element.
• an electronic engraving machine for engraving printing cylinders by means of an engraving member is already known.
• the engraving member with an engraving stylus controlled by an engraving control signal as the cutting tool moves in the axial direction along a rotating printing cylinder.
• the engraving stylus cuts a series of cups arranged in a printing grid into the outer surface of the printing cylinder.
• the engraving control signal is formed by superimposing a periodic raster signal to generate the print raster 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 cells arranged in the printing raster, the image signal values determine the depths of cut of the engraved cells in accordance with the tonal values to be reproduced.
• DE-A-23 36 089 specifies an engraving device which essentially has a rotating system and an electromagnetic drive for the rotating system.
• the rotating system consists of a shaft, an armature, a bearing for the shaft, a return element and a damping device.
• a lever-shaped stylus holder is attached to the shaft and carries the engraving stylus.
• the electromagnetic drive for the rotary system has a stationary electromagnet to which the engraving control signal is applied, in the air gap of which the armature of the rotary system moves. The drive causes the shaft to rotate at a small angle, and the stylus holder with the engraving stylus carries out a corresponding oscillating stroke movement in the direction of the outer surface of the printing cylinder for the engraving of the cups.
• the components of the engraving member are arranged with respect to the impression cylinder to be engraved in such a way that the oscillating shaft of the rotary system is aligned approximately tangentially to the impression cylinder and the stroke movement of the engraving stylus takes place in a plane running diametrically through the impression cylinder.
• the position of the shaft of a conventional engraving element with respect to the impression cylinder has the disadvantage that the forces which arise when the engraving stylus penetrates into the impression cylinder act asymmetrically on the stylus holder and the engraving stylus, which is due to an insufficient mechanical rigidity in an asymmetrical geometry of the engraved cups can impact.
• Another disadvantage is that due to the position of the shaft, heating of the engraving member can lead to incorrect depths of cut of the cells and thus to undesired changes in the tonal value.
• the invention is therefore based on the object of designing an engraving element for an electronic engraving machine for engraving printing cylinders and an electronic engraving machine with such an engraving element in such a way that, in particular, an improved geometry of the engraved cells and thus an improved engraving quality is achieved.
• 1 is a block diagram of an electronic engraving machine with an engraving member (prior art)
• 2 shows a first basic embodiment for the engraving element
• Fig. 4 shows a second basic embodiment for the engraving element
• Fig. 1 shows a block diagram of an electronic engraving machine according to the prior art.
• the engraving machine is for example a graph HelioKlischo- ® from Hell Gravure Systems GmbH, Kiel, DE.
• a printing cylinder (1) is driven by a rotary drive (2).
• An engraving element (3) with an engraving stylus (4) as a cutting tool is mounted on an engraving carriage (5) which can be moved in the axial direction of the printing cylinder (1) with the aid of a spindle (7) driven by a feed drive (6).
• the engraving element (3) is equipped, for example, with an electromagnetic drive for the engraving stylus (4).
• the engraving stylus (4) which is controlled by an analog engraving control signal GS on a line (8), cuts a series of engraving lines in the printing surface (s) into the outer surface of the rotating printing cylinder (1), while the engraving carriage (5) engages with the engraving element (3) For extensive engraving, move it step by step or continuously in the axial direction along the printing cylinder (1).
• the engraving control signal GS is generated in an engraving amplifier (9) by superimposing a periodic raster signal R to generate the print raster on a line (10) with image signal values B on a line (11), which the tone values of the cells to be engraved between "light” and depth "while the raster signal R causes an oscillating stroke movement of the engraving stylus (4) to engrave the cups arranged in the printing raster, 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 obtained 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 out in engraving lines and fed to the D / A converter (12) via a data bus (14).
• the engraving locations of the cells on the printing cylinder (1) specified by the printing grid are defined by the location coordinates (x, y) of a coordinate system assigned to the lateral surface of the printing cylinder (1), the X-axis in the axial direction and the Y-axis in the circumferential direction of the printing cylinder (1) are aligned.
• the feed drive (6) generates the x location coordinates and a pulse generator (15) mechanically coupled to the pressure cylinder (1) generates the y location coordinates.
• the xy location coordinates are fed 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 member (3) for engraving the printing cylinder (1).
• the engraving element (3) essentially consists of an oscillating rotating system and a drive for the rotating system, which in the exemplary embodiment is designed as an electromagnetic drive.
• the rotating system consists of a shaft (20), a torsion bar (21), a shaft bearing (22), a damping device (23), a stylus holder (24) and an armature (25).
• the shaft (20) lies parallel to the axis of rotation (27) of the printing cylinder (1).
• One end of the shaft (20) is designed as a resilient torsion bar (21) which is fastened in a fixed clamping (28) and forms the restoring element of the rotating system.
• the shaft bearing (22) is, for example, a spoke bearing according to the German utility model application G 298 12 163.8.
• the damping device (23) exists, for example, according to the - 5 - patent application P 198 30 471.4 from a stationary damping chamber filled with a damping medium, in which a damping disc connected to the shaft (20) moves.
• the lever-shaped stylus holder (24) in the exemplary embodiment described is attached with a radial orientation to the end of the shaft (20) opposite the torsion bar (21) and carries the engraving stylus (4).
• the damping device (23) and the shaft bearing (22) are arranged between the armature (25) and the stylus holder (24). Damping device (23) and shaft bearing (22) can also be designed as a structural unit.
• the end of the shaft (20) to which the stylus holder (24) is attached can also be supported by a further shaft bearing (29).
• the electromagnetic drive for the rotary system consists of a stationary electromagnet (26), which is shown in Fig. 3, and the armature (25) sitting on the shaft (20).
• the electromagnet (26) is acted upon by the engraving control signal GS, which is composed of the periodic raster signal R and the image signal values B.
• the drive for the rotary system can also be designed as a solid-state actuator, which consists for example of a piezoelectric or a magnetostrictive material.
• the oscillating rotary movement of the shaft (20) is converted by the stylus holder (24) into a corresponding stroke movement of the engraving stylus (4) in the direction of the outer surface of the printing cylinder (1), the stroke movement depending on the respective image signal values B the respective penetration depth of the Engraving stylus (4) in the impression cylinder (1) determined.
• the shaft (20) By arranging the shaft (20) parallel to the axis of rotation (27) of the printing cylinder (1), the rotary movement of the stylus holder (24) and the lifting movement of the engraving stylus (4) take place according to the invention in a plane perpendicular to the axis of rotation (27) of the printing cylinder (1) (30), which advantageously results in a symmetrical loading of the stylus holder (24) and engraving stylus (4) and thus an improved geometry of the engraved cup when engraving the cups.
• a change in the length of the shaft (20) due to heating does not have a disruptive effect on the cup geometry, but rather in a negligible change in the web width between the cups.
• Fig. 3 shows a sectional view A-B through the engraving member (3) and impression cylinder (1).
• the stationary electromagnet (26) of the drive for the shaft (20) has two opposing, U-shaped laminated cores (31) which are arranged in relation to each other in such a way that air gaps (32) are created between the legs forming the poles.
• the armature (25) of the rotating system moves in the air gaps (32).
• An excitation winding (34) is attached in longitudinal parts (33) of the laminated cores (31), of which only one coil side is shown.
• the field winding (34) is traversed by the engraving control signal GS.
• Fig. 4 shows a second basic embodiment of the engraving member (3) with a mirror-symmetrical structure with respect to the center of the longitudinal axis of the shaft (20).
• both ends of the shaft (20) are designed as torsion bars (21a, 21b) which are fastened in the fixed clamps (28a, 28b).
• the stylus holder (24) with the engraving stylus (4) is fork-shaped and is attached to the shaft (20) in the center of the longitudinal axis.
• Two anchors (26a, 26b) and two damping devices (23a, 23b) are present in mirror symmetry with the stylus holder (24).
• the shaft (20) is advantageously mounted in the center of its longitudinal axis in a shaft bearing (22), the shaft bearing (22) being arranged, for example, in the region of the fork-shaped stylus holder (24). It is within the scope of the invention to have a damping device act not directly on the shaft (20) but on the stylus holder (24). Furthermore, the torsion bars (21a, 21b) acting as restoring elements can also be replaced by spoke bearings, for example according to German utility model application G 298 12 163.8.
• Fig. 5 shows a third basic embodiment of the engraving member (3) with an electrically controlled adjusting device (35) for axially displacing the rotating system.
• the inherently stationary components such as shaft bearings (22), damping device (23) and clamping (28) are mounted in such a way that they cannot rotate by suitable resilient elements such as diaphragms and leaf spring crosses, that a small axial displacement of the rotating system and thus of the engraving stylus (4th ) is made possible by the adjusting device (35) and a return to a rest position.
• the axial displaceability of the clamping (28) for the torsion bar (21) is indicated, for example, by a membrane (36).
• the adjusting device (35) which is mechanically coupled to the end face of the shaft (20), for example, can be equipped with a piezoelectric drive.
• the cups on the printing cylinder (1) can be engraved axially displaced from their desired positions specified by the printing grid and shifted into a contour line to be reproduced, which advantageously smoothes the contour line during engraving becomes.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=7927841

Family Applications (1)

Country Status (5)

Families Citing this family (7)

Family Cites Families (12)

• 1999
  • 1999-11-04 DE DE19952996A patent/DE19952996A1/de not_active Withdrawn
• 2000
  • 2000-10-27 WO PCT/DE2000/003790 patent/WO2001032419A1/de not_active Application Discontinuation
  • 2000-10-27 EP EP00983065A patent/EP1230085A1/de not_active Withdrawn
  • 2000-10-27 JP JP2001534601A patent/JP2003512953A/ja active Pending
  • 2000-10-27 US US10/110,760 patent/US6634286B1/en not_active Expired - Lifetime

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