EP2305464A1 - Method for engraving a surface, a surface of a printing plate for gravure printing and a surface produced according to the method - Google Patents

Abstract

The method involves forming points in the form of cups in a predetermined arrangement in the form of a raster (12) form by engraving a surface (11) of a printing plate (10), where the points are formed on the surface. The engraving of the surface is performed by a graver that is electromagnetically operated. A part of the raster is inclined at a pointed angle relative to a rotary and/or linear motion device (15) of the printing plate while generating raster points. A bar separating the raster points is defined by formation of raster partial points.

Description

The invention relates to a method for engraving a surface of a printing form for gravure printing, wherein points to be formed on the surface are formed in predeterminable arrangement in raster form by the engraving in the form of wells, and wherein the engraving is carried out by means of an electromagnetically operable engraving stylus,

a method for engraving the surface of a solid medium, wherein for forming on the surface of the medium to be formed points in a predetermined arrangement in raster form by the engraving in the form of wells, and wherein the engraving is carried out by means of an electromechanically operable engraving stylus, and

a product produced by one or the other pre-listed process.

The imaging of printing forms, i. the engraving of color picker and color blanker screen dots on the surface of printing forms used for gravure printing has long been recognized and is a standard technique used for decades to produce high quality printing results. Thus, for example, the gravure printing technology for the production of high-quality magazines, magazines, high-quality brochures but also used for printing on packaging or for printing catalogs. Rather, this illustrative enumeration is not exhaustive, but merely representative of the broad field of gravure application. Basically, the imaging engraving as used for printing forms may be used for other purposes, e.g. the printing form need not be a printing cylinder and it is also possible to use the engraving by means of the known engraving process for gravure printing for flat media, for example. Metal, plastic or planar, solid materials based on minerals and the like. In this respect, everything that is explained below, in principle, also be applicable for the engraving of flat, solid media. Otherwise, the application of the generic method for the imaging of printing forms for gravure printing is described in the main focus.

There are in the prior art several fundamentally different methods for imaging of printing forms, ie the formation of the Farbaufnahme- and Farbabgabasterasterpunkte on the printing form. The oldest method for forming the halftone dots, or so-called "wells", which pick up the ink and release it again during printing, is the so-called etching process, in which the cells are etched on the basis of an imaging scheme. Although this imaging technique is very accurate in the imaging result and allows the training The smallest details on the printing form, but this Bebilderungstechnik has the disadvantage that it is very expensive and requires a lot of time and thus is very expensive, so that it is used only for very specific applications. It should be noted, however, that due to the very high level of detail this imaging technique is not generally no longer used, but rather, as I said, but only for special cases special application.

The broadened and still used today imaging technique of printing forms is based on the so-called. Engraver engraving, in which provided with a cutter or a cutting tool, electromechanically actuated stylus the wells on the surface or in the surface area of the printing plate in the course of the execution of the illustration using a Executes imaging schemes. As a rule, the actual cutting tool or the cutting surface of the stylus is formed by a correspondingly ground diamond. According to the controllable movement of the stylus, the diamond, i. the actual cutting tool in contact with the printing form to be imaged and, as it moves, produces relative to the surface of the printing form, i. both vertically and horizontally, a cup. This method is a so-called. Spanabhebendes method.

Since the diamond, the actual cutting tool, the engraving stylus during the imaging of the printing form no change in its geometric dimensions (cutting angle, maximum depth penetration possible), a variation of the imaging on the surface of a printing form ultimately can only be done over the surface width, which the art as a disadvantage is known and one has developed procedures in which a different Training the depth of the wells would be trying to achieve the same opening of the cup in the surface of the printing plate.

That is, for example, succeeded with the formation of the wells by means of an electron beam. However, this technique has not been successful to date, since in fact the entire imaging of a printing form, which can be several meters long, can only be carried out in a high vacuum, i. the entire imaging apparatus must be kept in a high vacuum during the execution of the imaging process. Although this imaging technique provides very precise results, i. Ultimately, arbitrarily suitable wells with respect. The opening of the wells in the surface plane of the printing plate and in the depth of wells allows form, this imaging has not enforced to this day, since it is also very costly.

With the technology in the meantime successful provision of suitable semiconductor lasers (laser diodes) which are suitable for the removal of material of the printing for forming the wells, have already established in the art imaging techniques of printing forms that work by means of lasers, but the Edge zones of the cells formed by laser light cups in the surfaces of the printing plates still pose problems, so that is still turned off for a high-quality imaging of printing plates on the conventional engraving by means of electromechanically operable engraving stylus.

Another problem with intaglio printing is, for example, the avoidable formation of a moiré when printing with ready-imaged printing forms. Normally, when printing gravure, four impression cylinders are used imaged and then the color cyan, magnet, yellow and black is applied to the respective printing cylinder. When overprinting the individual color separations (also called separations) to produce the finished Druckendprodukts, it often comes to the moire phenomena, ie optical interference that interfere with the image impression of the finished printing result sensitive. This is a significant disadvantage of the illustrations of the printing forms produced by the conventional engraving technique when the printed product is being executed.

Another significant drawback of the conventional imaging processes by means of an electromechanically operable engraving stylus is that there is a continuous fixed relationship between the depth of a well formed and the opening of the well in the surface, such that the depth of a well also determines the size of the surface opening and vice versa. This will ultimately require the use of a great deal of printing ink which would not be necessary per se, e.g. it is important to leave only color in the surface for printing again, but to the entire depth of the cup must be filled with color.

It is therefore an object of the present invention to provide a method for engraving a surface of the aforementioned types, in which on the one hand by means of a conventional, electromechanically operated Engraving engraving an imaging can be performed, but this illustration should be designed so that a moire-free Print result can be generated and a significant saving of ink compared to previously known, generic method is achieved.

This task is gem. a first invention achieved in that at least a portion of the grid is executed inclined at an acute angle α relative to the rotational and / or linear movement direction of the printing plate in the generation of the screen dots and

gem. a second solution according to the invention that at least a portion of the grid is performed inclined at an acute angle α relative to a linear direction of movement and / or a rotational axis of movement of the medium in the generation of the screen dots.

The very great advantage of the solutions according to the invention consists essentially in that by means of the solution according to the invention, the technique of engraving by means of electromagnetically operable engraving stylus, which is extremely common and also due to their relatively simple process management and a relatively simple apparatus design of a device with which According to the invention, a moiré-free printing result can be achieved by means of the imaged printing forms or a correspondingly precise engraving result of the engraved medium, which has hitherto not been considered possible by means of engraving engraving. A moiré effect does not occur, being parametrically rigid in its process control, i. not influenceable vibration engraving is left according to the invention, since this does not allow an angulation of the cell grid.

According to the invention, it is possible with the process control to carry out a partial raster of the imaging of a printing forme or a medium at an acute angle α ₁ and to form a different part of the raster at a different angle α ₂ on the same printing form, ie in fact the angulation of each raster individually according to the type of template that effects the control of the illustration. This measure also contributes to the moiré-free representation of the finished printed image.

According to an advantageous embodiment of the method, the engraving stylus is actuated in the manner of a high-resolution engraving technique, i. the engraving stylus can thus much more easily controlled so form the cup, the cup is broken down into a predetermined amount of individual Teilnäpfchen and engraved, which is in fact repealed the hitherto indissoluble relationship between cup opening and cup depth in conventional process management by means of a engraving stylus.

Also, the hitherto strict, unchangeable arrangement of the grid, as far as the size of the grid and the direction of the grid relative to the adjacent grid, can be advantageously varied by the engraving stylus is performed to perform the engraving process such that the grid point from a Is formed plurality of grid subdivisions. And similar, as it is possible with the laser engraving, which was not yet possible with the conventional electromechanically operated engraving by means of a engraving stylus.

Gem. A further advantageous embodiment of the method, each sub-grid for forming the printing form and / or at least one separation of a printing form is separately addressed and controlled. In other words, that a complete procedural decoupling for the production of the individual printing forms (separations) is possible according to the invention, which finds its expression in a virtually moiré-free printing result.

By the fact that the engraving stylus can be addressed at any point to which the engraving stylus passes, at which the engraving stylus performs the engraving process by means of the movement of the engraving stylus, and the impulse controllable for each location of the engraving stylus, which determines the depth of the cup at the predetermined engraving location. can be carried out by means of the method according to the invention, the formation of the wells in the manner of a conventional reproduction mode, similar to the conventional Engraving etch, so, but it can also be advantageously carried out the formation of the wells in the manner of a autotypical reproduction mode, but it can also advantageously the training of the wells after Type of semi-autotypic playback mode done. Due to the decoupling of the movement of the engraving stylus of a rigid engraving scheme, as was previously not possible in the conventional vibration engraving, according to the invention per well or per grid, as you want, the appropriate engraving technique can be used, just for the formation of the wells in a certain grid or partial grid appears the most suitable.

If in the following the formation of the halftone dots e.g. in a raster cell, the cells which form the raster points are always meant. The same applies when partial grid points, partial grid cells and partial cells are mentioned.

Thus, a grid point can be formed by means of the diamond stylus from a plurality of individual partial cells or individual partial grid points. A halftone dot can - as usual - but also be generated by a single act on the stylus with a suitably large signal.

There are gem. the inventive method any combination of engraving techniques according to the invention due to the decoupling of the rigid engraving by means of vibration engraving possible.

Not only the wells or the sub-wells are in the engraving technique in the manner of gravure special areas in terms of the final print result, but also the raster points separating ridges that limit or define the color ranges. By means of the method according to the invention, it is now likewise advantageously possible for a web separating at least two grid points to be defined by the design of the grid subdivisions or, if one so wishes, of the grid subjets, i. Overall, the imaging resolution can be significantly improved compared to a Bebilderungsergebnis due to a rigid vibration engraving imaging.

According to yet another embodiment of the method, the angles α are the different separations required for total color printing, i. the screen angles to i.d.R. 30 ° formed differently from each other, but, as already explained above, on a printing plate or a separation even the angle can be designed differently regardless of the advantageous relation described here.

Advantageously, the cutting angles β of a cutting tool in the form of a diamond engraving stylus in the range of 150 ° to 80 ° are formed large, these different training can also be selected depending on the material of the printing plate or the medium to be engraved.

According to another advantageous development of the method, the longitudinal axis of the wells or the wells formed of a plurality of Teilnäpfchen traverses the grid points, this embodiment in a simple way always the inclination angle α to Drehund / or linear motion of the printing plate or relative to a linear Movement direction and / or a rotational axis of the medium can be defined, ie this scheme can basically be chosen at all possible different angles α.

Finally, the method can be advantageously carried out such that for the engraving of a printing plate or a medium a plurality of diametrically different in their cutting angle β angle diamonds substantially simultaneously perform the engraving.

Naturally, the engraving styluses, since they have a concrete, three-dimensional shape, extend essentially in the transverse direction, in the longitudinal direction and in the height depending on the respective design. Thus, it is absolutely impossible that, for example, the engraving stylus or the diamonds of the engraving stylus, which are used for the formation of the side walls of the wells during engraving, simultaneously positioned with the engraving styli to form the same cup and can be controlled to perform the engraving , At the same time in the above sense should only mean that several styluses can be used simultaneously to form the Teilnäpfchen in a portion of the printing form application, as far as allow the geometric dimensions of the stylus. Thus, with a stylus example. The entire edge regions of the wells or Teilnäpfchen be formed at a certain angle β ₁ , wherein adjacent thereto, as far as possible, but at the same time the central Teilnäpfen of the Trainees cup can be made with the other stylus with different cutting angle β ₂ .

Thus, with the method according to the invention, imaging of a printing form is also possible much more precisely than with the classic engraving tools for classical vibration engraving.

A product prepared by the two methods described herein in the form of an imaged printing plate or engraved medium is characterized in that at least part of the screen is inclined at an angle α to an imaginary major axis of the printing plate or solid medium.

Fig. 1

eine beispielhafte Darstellung des erfindungs- gemäß ausbildbaren Rasters auf einer Druckform mit einem Neigungswinkel von 30°,

Fig. 2

eine Darstellung eines Rasters auf einer Druckform, die gegenüber dem Raster von Fig. 1 feiner gewählt ist, geneigt unter einem Winkel von 15°,

Fig. 3

einen schematischen Schnitt durch mehrere ne- beneinanderliegende Rasterpunkte, wobei hier dreieinhalb Näpfchen dargestellt sind,

Fig. 4

die Draufsicht auf einen Teilausschnitt einer fertig gravierten Oberfläche einer Druckform, den Rasteraufbau schematisch zeigend,

Fig. 5

eine Draufsicht auf einen Teilausschnitt einer Druckform, wobei die dort ausgebildeten Näpf- chen mittels dem erfindungsgemäßen Verfahren hergestellt worden sind und einen Vollton zei- gen,

Fig. 6

eine Darstellung wie gem. Fig. 5, jedoch einen Mittelton zeigend,

Fig. 7

eine Darstellung wie die Fig. 5 und 6, jedoch einen lichten Ton zeigend,

Fig. 8

in vergrößerter Darstellung einen Teil einer einzelnen Gravurlinie gem. der Erfindung für die Darstellung des Grenzbereiches zwischen zwei Rasterpunkten im Hinblick auf einen Da- tenbestand zur Steuerung eines Gravierstichels, vier unterschiedliche Fälle (Fall a, Fall b, Fall c, Fall d) zeigend,

Fig. 9

einen Diamanten mit einem Schneidwinkel β₁ von 80°, mit dem ein Stichel bestückt wird, wie er erfindungsgemäß verwendet wird, und

Fig. 10

eine Darstellung wie Fig. 9, jedoch einen Dia- manten darstellend, der einen Schneidwinkel β₂ von 50° aufweist.

The invention will now be described in detail with reference to the following schematic drawings using an exemplary embodiment. Show:

Fig. 1

an exemplary representation of the grid according to the invention can be formed on a printing plate with an angle of inclination of 30 °,

Fig. 2

a representation of a grid on a printing form, compared to the grid of Fig. 1 fine, tilted at an angle of 15 °,

Fig. 3

a schematic section through a plurality of adjacent grid points, wherein three and a half wells are shown here,

Fig. 4

the top view of a partial section of a finished engraved surface of a printing form, showing the grid structure schematically,

Fig. 5

2 a top view of a partial section of a printing form, wherein the wells formed there have been produced by means of the method according to the invention and show a full tone,

Fig. 6

a representation like gem. Fig. 5 but showing a midtone,

Fig. 7

a representation like that Fig. 5 and 6 but showing a light tone,

Fig. 8

in an enlarged view a part of a single engraving line acc. of the invention for the representation of the border area between two screen dots with respect to a data stock for controlling an engraving stylus, showing four different cases (case a, case b, case c, case d),

Fig. 9

a diamond with a cutting angle β ₁ of 80 °, which is equipped with a stylus, as used in the invention, and

Fig. 10

a representation like Fig. 9 but showing a diamond having a cutting angle β ₂ of 50 °.

First, reference will be made to the illustration of Fig. 1 and 2 , which shows a section of an imprinting printing forme 10 for gravure printing or a solid medium for forming an engraving according to the invention. A printing form 10 for gravure printing is generally circular cross-section in cross section, that is formed overall in the form of a cylinder which rotates about a rotation or rotational axis 17, in the embodiment According to the invention at least a portion of the grid 12, which is formed here in the illustrated examples substantially in the form of a square grid 12, inclined at an acute angle α relative to the rotational and linear movement of the printing plate 10, wherein the Longitudinal axis 20 of the grid through the diagonally opposite points of the grid 12 and the wells, if they are then passes through.

By means of a with a diamond 19 as an actual cutting tool equipped engraving stylus 14, s. Fig. 8 , which is described in the manner of a high-resolution engraving technique, be in space between the four grid points bounding the space, cf. especially Fig. 3 , the cups 13 formed here in the illustration of Fig. 3 each consist of five Teilnäpfchen 130, viewed along a cross-sectional line through the longitudinal axis 20 of the wells 13, consist. In the formation of the wells 13 and the Teilnäpfchen the printing plate 10 is rotated about the rotation axis 17, wherein the wells 13 and the Teilnäpfchen 130 are formed on respective tracks with respect to the printing plate 10.

As can be seen, the sub-wells 130, which are formed in the edge region of a cup 13, have a smaller depth than the sub-wells 130, which are formed in the intermediate region. However, as an alternative possibility, for example, as in a conventional imaging mode, the density, ie the removal of the material, in the core region of the wells 13 can first be reduced until they have the same density as in the edge region of the wells 13. Then, for example, the removal of the remaining Teilnäpfchen 130 corresponding to the individual predetermined density information.

In the circumferential direction of the printing plate 10, the tracks shown have a finite extent. The edges of the wells 13 are in the circumferential direction as shown by Fig. 1 reduced according to the given edge information. However, the density value of the different edge information may differ from information to information. The envelope of the tracks represents the well 13.

The formation of the wells 13 can be carried out in the manner of a conventional reproduction mode, which was previously reserved only for the above-described or above-described design of the wells by the known etching technique. In addition, the formation of the wells 13 gem. However, it is also possible to make the formation of the wells in the manner of a semi-automatic reproduction mode, wherein also for the most diverse predetermined areas of the printing form to be imaged any suitable mixed forms of these 3 basic imaging techniques can apply. This applies not only to the training of figurative representations, but also to the training of numbers, where one simply speaks of stroke representations or simply stroke.

In the FIGS. 9 and 10 is a typical electromechanically actuated engraving tool in the form of a diamond shown as an actual tool for a stylus, with a stylus can be equipped. Fig. 9 shows a diamond with a cutting angle β ₁ of 80 °, Fig. 10 shows a diamond with a cutting angle β ₂ of 50 °.

Fall a.

ein Durchlauf mit einem Diamanten mit einem Schneidwinkel β₁,

Fall b.

eine Teilgravur für den Kernbereich eines Ra- sterpunktes mit einem Diamantschneidwinkel β₁,

Fall c.

eine Teilgravur für den Randbereich eines Ra- sterpunktes mit einem Schneidwinkel von β₂ und

Fall d.

eine eine Überlagerung der Gravurteilraster darstellend, und zwar zur Darstellung des End- ergebnisses einer fertigen Gravurlinie.

With regard to the representations in the Fig. 8 Showing cases a, b, c and d becomes a part of a single Engraving line shown. For the understanding of the invention, in particular the representation of the border region between two halftone dots is important. The structure of a database with which a diamond equipped with a stylus (not shown here) is controlled, is as follows:

Case a.

a pass with a diamond with a cutting angle β ₁ ,

Case b.

a partial engraving for the core area of a raster point with a diamond cutting angle β ₁ ,

Case c.

a partial engraving for the edge area of a raster point with a cutting angle of β ₂ and

Case d.

one representing a superimposition of the gravure grid, to represent the final result of a finished engraving line.

The Fig. 8 a, 8 b . 8c and 8d correlate with the schemes listed below with respect to the control data for the equipped with a diamond or the like stylus for performing the grid points or sub-grid points (wells, Teilnäpfchen).

The data for controlling the stylus that does not trigger a pricking action are shown above the horizontal bar, in case a. symbolized by the data command A5, in case b. symbolized by the data commands A4, A5 and A6, in case c. by the data commands A1, A2, A3, A5, A7 and A8.

Beschreibung der Kerninformationen eines Rasterpunktes. Entsprechende Trennung in zwei Datenbestände für die Gravuren mit zwei Diamanten mit Schneidwinkeln β₁, β₂.

In the case of d. Showing the engraving commands for overlaying the engraving of the halftone dots and the sub-grid dots, respectively, the command data for the engraving stylus are different Engraving depths A1, A2, A3 for engraving depth T ₁ , A4 and A6 for the engraving depth T ₂ and finally A7 and A8 Engraving instructions for the engraving depth T ₁ .

Description of the core information of a grid point. Corresponding separation into two databases for the engraving with two diamonds with cutting angles β ₁ , β ₂ .

Description of the border areas of the grid point

Overlay schematically for possible overall picture

LIST OF REFERENCE NUMBERS

10

Printing form / solid medium

11

surface

12

Raster form / grid

13

wells

130

Rasterteilnäpfchen

14

engraving tool

15

Rotary and / or linear movement direction

16

dot

116

Grid sub point

17

Rotational movement axis

18

web

19

diamond

20

Longitudinal axis / well

21

main axis

Claims (15)

Method for engraving a surface (11) of a printing form (10) for gravure printing, wherein dots to be formed on the surface (11) are formed in predeterminable arrangement in raster form (12) by the engraving in the form of cells (13), and wherein the engraving is performed by means of an electromagnetically operable engraving stylus (14), characterized in that at least a part of the grid (12) at an acute angle α relative to the rotational and / or linear movement direction (15) of the printing plate (10) in the generation of the Grid points (16) is performed inclined. Method according to Claim 1, characterized in that the engraving stylus (14) is operated in the manner of a high-resolution engraving technique. Method according to Claim 1 or 2, characterized in that the engraving stylus (14) for carrying out the engraving process is formed per grid point (16) from a plurality of grid dividing points (160). Method according to one or more of claims 1 to 4, characterized in that each sub-grid point (160) for forming the printing form (10) and / or at least one separation of a printing form (10) is separately addressable and controllable. Method according to one or more of claims 1 to 3, characterized in that the formation of the wells (13) takes place in the manner of a conventional reproduction mode. Method according to one or more of claims 1 to 3, characterized in that the formation of the wells (13) takes place in the manner of an autotypical reproduction mode. Method according to one or more of claims 1 to 3, characterized in that the formation of the wells (13) takes place in the manner of a semi-automatic reproduction mode. Method according to one or more of claims 2 to 7, characterized in that a web (18) separating at least two grid points (16) is defined by the formation of the raster subdivisions (160) or raster subnodes (130). Method according to one or more of claims 1 to 8, characterized in that the angles α of different separations differ from one another in the region of 30 °. Method according to one or more of claims 1 to 9, characterized in that the cutting angle β of a cutting tool in the form of a diamond (19) having engraving stylus (14) in the range of 120 ° to 90 ° is large. Method according to one or more of Claims 1 to 10, characterized in that the longitudinal axis (20) of the cup formed from a plurality of partial cups (130) traverses the diagonally adjacent grid points (16), wherein between the longitudinal axis (20) and the direction of rotation (15 ) the angle α is clamped. Method according to one or more of Claims 1 to 11, characterized in that each raster point (16) can be formed by respectively a plurality of different raster subdivisions (160) or raster subdubules (130). Method according to one or more of Claims 1 to 12, characterized in that, for the engraving of a printing form (10), a plurality of diamonds (19) of engraving styluses (14) having different angles at their cutting angle β execute the engraving process substantially simultaneously. Method for engraving the surface (11) of a solid medium (10), wherein the points to be formed on the surface (11) of the medium (10) are formed in predeterminable arrangement in raster form (12) by the engraving in the form of wells (13) , and wherein the engraving is carried out by means of an electromechanically operable engraving stylus (14), characterized in that at least a part of the grid (12) at an acute angle α relative to a linear direction of movement (15) of the medium (10) is inclined at the generation of the screen dots (16). Product produced by the process according to one or more of claims 1 to 14, or produced by the process according to claim 15, characterized in that at least a part of the grid (12) is at an angle α to an imaginary main axis (21) of the printing plate (10) or the solid medium (10) is inclined.

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