EP1068076A1

EP1068076A1 - Method for positioning engraving members

Info

Publication number: EP1068076A1
Application number: EP99924764A
Authority: EP
Inventors: Bernd LÜBCKE
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1998-04-03
Filing date: 1999-04-03
Publication date: 2001-01-17
Also published as: DE19814939A1; US6540453B1; WO1999051436A1; JP2002510570A

Abstract

The invention relates to a method and device for positioning engraving members in an electronic engraving machine in order to engrave printing cylinders for rotogravure. At least two engraving billets (A,B,C) of the printing cylinder (1) are arranged next to each other in the direction of the printing cylinder (1) axis, each having a given width (SB), and are engraved as cup-shapes by an associated engraving member (3). Before engraving, the axial distances separating the engraving members (3) have to be adjusted according to the required width of the billets (SB). In order to save time, the axial distances between the engraving members (3) are initially adjusted in an approximate manner by hand. Axial reference position marks whose axial distances correspond to the width of the billets (SB) are produced in a device (20). The engraving members (3) also have axial position marks (19). When approximate positioning occurs, the engraving members (3) are displaced manually until their position marks (19) coincide with the assigned reference position marks. The engraving members (3) are finely positioned once approximate manual positioning has occurred.

Description

Method of positioning engraving elements

The invention relates to the field of electronic reproduction technology and relates to a method for positioning engraving elements in an electronic engraving machine for engraving printing cylinders for gravure printing, in which at least two engraving strands of predetermined strand widths lying next to one another in the axial direction of the printing cylinder, each with an associated engraving element be engraved, as well as a device for generating reference position marks for the positioning of the engraving members and an engraving machine for performing the method.

When engraving printing cylinders in an electronic engraving machine, an engraving element moves in the axial direction along a rotating printing cylinder. The engraving element is designed, for example, as an electromagnetic engraving element with an engraving stylus as a cutting tool. The engraving stylus, which is controlled by an engraving control signal, cuts a sequence of cups of different depths arranged in an engraving grid into the lateral surface of the printing cylinder. The engraving control signal is formed by superimposing an image signal which represents the tonal values to be engraved between "light" (white) and "depth" (black) with a periodic raster signal. While the periodic raster signal causes the engraving stylus to vibrate to generate the engraving raster, the image signal values determine the depths of the cells engraved in the outer surface of the printing cylinder and thus the engraved tonal values.

For magazine printing, a large number of strip-shaped cylinder areas, called engraving strands, lying axially next to one another must often be engraved with one engraving element, for example the different printed pages of a print job. The engraving elements assigned to the individual engraving strands are mounted on a common engraving carriage, which moves along the printing cylinder in the axial direction during the engraving. In order to achieve good reproduction quality, the axial spacing of the engraving stylus tips of the engraving elements must be adjusted to the required widths of the individual engraving strands by axially shifting the engraving elements on the engraving carriage. The engraving carriage with the precisely spaced engraving elements is then positioned relative to the printing cylinder in such a way that the engraving stylus tips lie in the axial starting positions for the engraving of the engraving strands.

In order to save time when registering the individual engraving elements with precise registration, an operator roughly sets the required axial distances by manually moving the engraving elements, for example using position marks or using a measuring tape. The manual rough positioning of the engraving elements saves time in particular when a large number of engraving strands are to be engraved and thus a large number of engraving elements have to be positioned. After the rough positioning, the precise positioning of the engraving elements is then carried out using various methods.

The object of the present invention is to provide a method for positioning engraving elements in an electronic engraving machine, a device for generating and displaying reference position marks for positioning the engraving elements, and an engraving machine for carrying out the method, with which the positioning of engraving elements is facilitated and in short - zester time is carried out.

This object is achieved with respect to the method by the features of claim 1, with respect to the device by the features of claim 9 and with respect to the engraving machine by the features of claim 14.

Advantageous further developments and refinements are specified in the subclaims. The invention is explained in more detail below with reference to FIGS. 1 and 2.

Show it:

Fig. 1 is a basic block diagram of an engraving machine for printing cylinders and

Fig. 2 shows an embodiment of a device for generating reference position marks.

1 shows a basic block diagram of an engraving machine for engraving printing cylinders for gravure printing. The engraving machine is, for example, a HelioKlischograph "from Hell Gravure Systems GmbH,

Kiel, DE.

A pressure cylinder (1) is driven in rotation by a cylinder drive (2). A plurality of engraving strands lying next to one another in the axial direction of the printing cylinder (1), in the exemplary embodiment three engraving strands (A, B, C), which have corresponding axial strand widths (SB), are to be engraved on the printing cylinder (1), each with an associated engraving member (3) .

The engraving elements (3), which are designed, for example, as electromagnetic engraving elements with engraving styluses (4) as cutting tools, are located on an engraving carriage (5) on which they can be manually shifted and locked in the axial direction of the printing cylinder (1). For the axial positioning of the engraving carriage (5) relative to the printing cylinder (1) and for advancing the engraving carriage (5) in the axial direction during engraving, the engraving carriage (7) moves it via a spindle (6) in the axial direction of the printing cylinder (1). The engraving elements (3) can also be individually coupled to the spindle (6) by means of spindle nuts. In this case, the common engraving carriage (5) is omitted. - 4 -

The engraving stylus (4) of the engraving elements (3) cut engraving line by engraving line a series of cells arranged in a printing grid into the outer surface of the rotating printing cylinder (1), while the engraving carriage (5) with the engraving elements (3) move in the feed direction on the printing cylinder (1) moved along.

In the exemplary embodiment shown, the cups are engraved on individual engraving lines which run in a circular manner in the circumferential direction around the printing cylinder (1), the engraving carriage (5) carrying out an axial feed step to the next engraving line on each engraving line after the engraving of the cups.

Such an engraving method is described, for example, in US Pat. No. 4,013,829. Alternatively, the engraving of the engraving strands (A, B, C) can also take place in an engraving line running helically around the printing cylinder (1), the engraving carriage (5) then executing a continuous feed movement during the engraving.

The engraving stylus (4) of the engraving elements (3) are controlled by engraving control signals (GS). The engraving control signals (GS) are formed in engraving amplifiers (8) from the superimposition of a periodic raster signal (R) on a line (9) with image signal values (B) which define the tonal values of the cells to be engraved between "light" (white) and "depth""(Black) represents. While the periodic raster signal (R) causes the engraving stylus (4) to vibrate to generate the engraving raster, the image signal values (B) determine the respective geometric dimensions, such as depth of penetration, transverse diagonal and longitudinal diagonal, into the outer surface of the printing cylinder (1 ) engraved cells. The analog image signal values (B) are obtained in D / A converters (10) from engraving data (GD) which are stored in engraving data memories (11) and are read from these engraving lines for engraving lines and fed to the D / A converters (10)

become. Each engraving location for a well on the printing cylinder (1) is assigned an engraving date of at least one byte, which, among other things, contains the tonal value to be engraved between "light" and "depth" as engraving information.

The engraving locations for the cells specified by the engraving grid are defined by location coordinates (x, y) of an XY coordinate system assigned to the printing cylinder (1), its Y axis in the circumferential direction (engraving direction) of the printing cylinder (1) and its X axis are oriented in the axial direction of the printing cylinder (1) (feed direction).

The engraving carriage drive (7) generates the x-location coordinates in the feed direction, which define the axial positions of the engraving carriage (5) in relation to the printing cylinder (1). A position transmitter (12) mechanically coupled to the printing cylinder (1) generates the corresponding y-location coordinates in the engraving direction. The location coordinates (x, y) are fed via lines (13, 14) to a control unit (15) which controls the engraving process.

The control unit (15) generates three reading cycle sequences (T) on a multiple line (16) for reading out the engraving data (GD) from the engraving data memories (11), a feed command (S ^ on a line (17) to the engraving carriage drive (7) for control the gradual feed of the Gravierwageπs (5) and the raster signal (R) on the line (9).

The frequency of the raster signal (R) together with the peripheral speed of the printing cylinder (1) and the axial feed increment of the engraving carriage - 6 -

(5) determine the geometry of the engraving grid with respect to the screen angle and screen width.

In order to achieve a precise registration of the engraving strands (A, B, C) on the impression cylinder (1), the axial distances between the engraving styluses (4)

the engraving elements (3) are set so that they correspond to the specified strand widths (SB).

For this purpose, in practice, the operator initially roughly positions the engraving elements (3) on the approximate strand widths (SB) by manually axially moving the engraving elements (3) on the engraving carriage (5). A fine positioning of the engraving stylus (4) of the engraving elements (3) is then carried out under visual observation by the operator. The fine positioning takes place, for example, with the aid of a special microscope device (stylus assignment gauge) and manually operable spindle drives on the engraving carriage (5).

As an alternative to the fine positioning of the engraving elements (3), an electronic compensation of the distance errors made during the rough positioning according to the German patent application P 197 23 007.5 can take place during the engraving.

The engraving carriage (5) is then axially displaced such that the engraving stylus tips of the engraving elements (3) are positioned on the start engraving lines of the individual engraving strands (A, B, C) on the printing cylinder (1), and the engraving can begin .

To facilitate the manual coarse axial positioning of the engraving elements (3) by the operator before engraving, axial reference position marks (18) are generated depending on the engraving parameters "number of engraving strands" and "strand width", the number of which is to be engraved - 7 -

Engraving strands (A, B, C) corresponds and their axial distances from each other match the desired strand widths (SB). Corresponding position marks (19) are attached to the engraving elements (3). In the case of rough positioning, the operator advantageously only has to align the position marks (19) of the engraving elements (3) with the associated reference position marks (18) by axially displacing the individual engraving elements (3).

For this purpose, the engraving machine has a device (20) for generating and displaying the reference position marks (18). In the exemplary embodiment shown in FIG. 1, the device (20) is aligned with its longitudinal extent in the axial direction or feed direction and is attached to the axially displaceable engraving carriage (5). The device (20) is actuated as a function of the specified engraving parameters by corresponding control commands (S ₂ ) on a line (21) from the control unit (15).

2 shows an embodiment of the device (20) for generating and displaying the reference position marks (18), which consists of a transparent tube (22), for example an acrylic glass tube, in which optically refractive particles, for example not rounded glass powder particles. A frequency transmitter (23) which can be controlled in frequency is attached to one end of the tube (22), and a light source (24) for generating visible light is attached to the other end. The sound propagating in the glass of the tube (22) and / or in the air space of the tube (22) generates a standing sound wave (25) with wave nodes (26) in the tube (22), the first wave node (26) in the Area of the sound generator (23) and the last wave node are in the area of the light source (24). Particle deposits form at the shaft nodes (26), which are made visible to the outside as reference position marks (18) with the aid of the light source (24). Alternatively, the glass powder can also be mixed with a fluorescent substance, the light source (24) being designed as a UV light source. - 8th -

The distance between two wave nodes (26) corresponds to half the wavelength (λ 2) of the standing wave (25). The wavelength (λ) can be changed via the frequency (f) of the standing wave (25). The distance (L) between the end faces of the sound generator (23) and the light source (24), which is a multiple of half the wavelength (λ / 2), can be adjusted by axially shifting the sound generator (23) and / or the light source ( 24) adapt to the requirements.

The number of reference position marks (18) to be generated or the number of shaft nodes (26) to be generated is equal to the number n of engraving strands (A, B, C) to be engraved on the printing cylinder (1). The distance between the reference position marks (18), which corresponds to half the wavelength (λ / 2), is equal to the predetermined strand width (SB) of the engraved strands (A, B, C) to be engraved.

Provided that the first and last wave nodes (26) on the mutually facing end faces of sound generator (23) and light source (24) are used to generate the reference position marks, the distance (L) to be set between sound generator (23) and light source results (24) and the frequency (f) to be set on the sounder (23) at a speed of sound (c) to:

L = n x λ / 2 = n x SB and

f = c / λ = c / 2 SB

Provided that only the "free" wave nodes of the standing wave are used to generate the reference position marks, the distance (L) to be set between sound generator (23) and light source (24) and the frequency to be set on sound generator (23) (f ) at a speed of sound (c) to: - 9 -

L = (n + 1) x λ / 2 = (n + 1) x SB and

f = c / λ = c / 2 SB

With normal line widths of SB = 0.15 to 0.6 m, sound frequencies of f = 1103 to 275 Hz then result.

Claims

-10 claims

1. Method for positioning engraving elements in an electronic engraving machine for engraving printing cylinders for gravure printing, in which

at least two engraving strands (A, B, C) of a predetermined strand width (SB) lying next to one another in the axial direction of the printing cylinder (1) are engraved in the form of cups, each with an associated engraving member (3),

- Before the engraving, the axial distances of the engraving elements (3) from one another are set and

- The engraving members (3) perform an axial feed movement along the printing cylinder (1) during engraving, characterized in that for the approximate adjustment of the axial distances between the engraving members (3) on the strand widths (SB) - for the engraving members (3) axial reference position marks (18) are generated and displayed, whose axial distances from one another correspond to the predetermined strand widths (SB) of the engraving strands (A, B, C) to be engraved on the printing cylinder (1),

- The engraving elements (3) have axial position marks (19) and - The engraving elements (3) are axially displaced such that the position marks (19) are in register with the respectively assigned reference position marks (18).

2. The method according to claim 1, characterized in that - the engraving members (3) on a engraving carriage (5) are arranged displaceably and lockable,

- The engraving elements (3) for adjusting the distance on the engraving carriage (5) are moved and locked and

- The engraving carriage (5) with the locked engraving members (3) carries out the feed movement along the printing cylinder (1) when engraving the engraving strands (A, B, C). ^■ 1 1 -

3. The method according to claim 1 or 2, characterized in that the position marks (19) of the Gravierorgaπe (3) each lie in a plane perpendicular to the axis of the printing cylinder (1) and through the element producing the cup of the engraving member (3).

4. The method according to claim 3, characterized in that the element producing the cells is an engraving stylus (4).

5. The method according to any one of claims 1 to 4, characterized in that the reference position marks (18) with the axial engraving start positions in the engraving strands (A, B, C) on the printing cylinder (1) match.

6. The method according to any one of claims 1 to 4, characterized in that the engraving carriage (5) after adjustment of the distances between the engraving members (3) is moved such that the reference position marks (18) with the axial engraving start positions in the engraving strands (A , B, C) on the printing cylinder (1) match.

7. The method according to any one of claims 1 to 6, characterized in that after the approximate adjustment of the axial distances between the engraving members (3), an exact adjustment of the distance is carried out.

8. The method according to any one of claims 1 to 7, characterized in that the reference position marks (18) are generated automatically depending on the number of engraving strands to be engraved (A, B, C) and the predetermined strand widths (SB).

9. Device for generating and displaying reference position marks, characterized by -12-

- a transparent tube (22) in which there are optically refractive particles,

- One on one end of the tube (22) arranged sound generator (23) for generating a standing sound wave (25), at the wave node (26), the particles are deposited and

- A light source (24) arranged on the other end of the tube (22) for generating light which makes the deposited particles visible as reference position marks (18).

10. The device according to claim 9, characterized in that the sound generator (23) and / or light source (24) in the tube (22) are arranged axially displaceable.

11. The device according to claim 9 or 10, characterized in that the particles are glass powder particles.

12. Device according to one of claims 9 to 11, characterized in that the particles are mixed with a fluorescent substance and the light source (24) generates UV light.

13. Device according to one of claims 9 to 13, characterized in that the frequency of the sound generator (23) is adjustable.

14. Engraving machine for the engraving of at least two engraving strands (A, B, C) lying next to one another in the axial direction of a printing cylinder

String widths (SB) each with an associated engraving element (3), consisting of:

- A rotatably mounted printing cylinder (1) which is rotated by a first drive (2), - an engraving carriage (5) which can be moved along the printing cylinder (1) in the axial direction by means of a second drive (7) and -13-

- Engraving elements (3) for engraving the engraving strands (A, B, C), which are arranged on the engraving carriage (5) so as to be displaceable and lockable, characterized by

- A device (20) for the automatic generation and display of reference position marks (18) for the approximate setting of the axial distances of the engraving elements (3) to the required strand widths (SB).

15. Engraving machine according to claim 14, characterized in that the device (20) is located on the engraving carriage (5) and extends at least over the displacement area of the engraving members (3).

16. Engraving machine according to claim 14 or 15, characterized in that the device (20) for generating and displaying reference position marks

(18) consists of the following components:

- a transparent tube (22) in which there are optically refractive particles,

- One on one end of the tube (22) arranged sound generator (23) for generating a standing sound wave (25), at the wave node

(26) the particles deposit and

17. Engraving machine according to one of claims 14 to 16, characterized in that the frequency of the sound generator (23) and the distance between the sound generator (23) and light source (24) are adjustable such that the number of wave nodes (26) of the standing sound wave (25) corresponds to the number of engraving strands (A, B, C) to be engraved and the spacing of the shaft nodes (26) is equal to the specified strand widths (SB).