Heidelberger Druckmaschinen Ag

Hell Gravure Systems Gmbh

Hall Gravure Systems Gmbh

Bernd L&uuml;bcke

Christian Wiechering

Dieter Fangmeyer

Reinhold Bruno Bleih&ouml;fer-Sterzinger

Karsten Becker

Armin Jacht

In a method for processing signals in an electronic engraving machine for engraving printing forms, in particular printing cylinders used for rotogravure, an engraving control signal is obtained by superimposing engraving data, representing tone values between &ldquo;white&rdquo; and &ldquo;black&rdquo; which are to be engraved, with a periodic screen signal for generating a gravure screen. The engraving control signal guides the lifting movement of the stylus of an engraving element. As a result of the lifting movement of the stylus, a series of cups arranged in the gravure screen is engraved on the printing form. To compensate an incorrect lifting movement of the stylus (rebound effect, lag effect), the engraving data undergo digital filtering before superposition of the gravure screen.

Method for signal processing

In to a method and apparatus for positioning engraving elements in an electronic engraving machine for engraving printing cylinders for rotogravure, at least two engraving lanes of predetermined lane widths lying side-by-side in the axial direction of the printing cylinder are engraved in the form of cups with a respectively allocated engraving element. Before engraving, the axial spacings of the engraving elements from one another must be set to the required lane widths. In order to save time, a manual rough adjustment of the axial spacings of the engraving elements is implemented first. Axial reference position marks whose axial spacings from one another correspond to the lane widths are generated in an apparatus. The engraving elements comprise axial position marks. In the rough positioning, the engraving elements are manually displaced until the position marks are in coincidence with the respectively allocated reference position marks. A fine positioning of the engraving elements occurs after the manual rough positioning.

Method for positioning engraving members

The invention relates to a method and a circuit for processing signals in an electronic graving machine, in which a series of cups arranged in a gravure screen is engraved in a printing cylinder by a burin of a graving element guided by an engraving control signal (G). In a digital signal processor ( ), a transfer function is determined from function value data used to calculate a periodic screen signal for producing the gravure screen; from adjustment data for adjusting the depth of cut; from digital adjustment parameters for calibrating &ldquo;light&rdquo; (white) and &ldquo;dark&rdquo; (black); and from control data (SD). The transmission coefficients of the transmission function and/or the transmission function can be modified by the control data (SD). The engraving data (GD), which represent the different tone values between &ldquo;black&rdquo; and &ldquo;white&rdquo; which are to be engraved, are then converted into engraving control data (GSD) in the digital signal processor ( ) after the transmission function. The engraving control data (GSD) undergo digital-analog conversion and the analog engraving control signal (G) is amplified in a current amplifier ( ) and fed to the graving element.

Signal processing method

In a method for determining the axial position of an engraving element in an engraving machine used for engraving impression cylinders, the engraving machine has a fixed toothed comb in which a significant tooth flank of each tooth presents an axial distance which is a multiple of the tooth spacing of the toothed comb to a reference point. A photoelectric barrier which serves as axial reference mark is positioned on the engraving element and the toothed comb serves as black-out element for said photo-electric barrier. The engraving element is displaced by means of the photoelectric barrier from a momentary position to the nearest relevant tooth flank of the toothed comb. The approximate distance between the reference mark and the reference point is measured by means of a distance meter. Next, the approximate distance is compared with the multiple of the tooth spacing of the toothed comb and the exact distance between the reference mark of the engraving element and the reference point is determined from this comparison.

Method for determining the position of an engraving element

In a device for engraving screen-based impression cylinders, particularly for intaglio printing, by means of an engraving element in an electronic engraving machine, an engraving element is controlled by an engraving signal which engraves a series of wells into the rotating impression cylinder line by line. The wells are arranged according to a screen defined by presettable engraving parameters, and their engraving depths represent the engraved tone values. To engrave the entire surface area of the wells, the engraving element moves in a feed motion along the impression cylinder in the direction of the axis of the impression cylinder. The screen geometry is determined by the peripheral speed of the rotating impression cylinder and the feed motion of the engraving element. By controlling the engraving machine using automatic process control, several sequential engravings with different engraving parameters, such as screen parameters, are carried out in one step on at least one impression cylinder with at least one engraving element. The sequential engravings are multiple engravings or re-engravings from first engravings.

Growing community of inventors

Molfsee, Germany

Bernd Lübcke

Growing community of inventors

Molfsee, Germany

Bernd L&uuml;bcke

Bernd Lübcke