Patent Grant
8164800
This present preferred embodiment concerns a method and a device for engraving printing cylinders for packaging printing and similar printing applications in an electronic engraving machine in which an engraving member engraves elements to be printed (in particular made up of cups) into the printing cylinders, and the engraving member for areal engraving executes a feed movement parallel to the longitudinal axis of a printing cylinder. To shorten the engraving time, an engraving member can be associated with a respective circumferential engraving strip when a print image or layout for a respective printing cylinder is sub-divided into at least two of such circumferential engraving strips parallel to one another and next to each other in the axial direction.
An electronic engraving machine for engraving printing cylinders is known from DE-C-25 087 34. An engraving member with an engraving tool controlled by an engraving control signal as a cutting tool moves along a rotating printing cylinder in the axial direction. The engraving element cuts cups into the generated surface of the printing cylinder, which cups are arranged in an engraving grid in the manner of engraving lines. The engraving control signal is obtained by superimposing a periodic raster signal with image signal values which represent the tone values to be engraved. While the raster signal produces an oscillating lifting motion of the engraving tool to engrave the cups arranged in the engraving grid, the image signal values determine the geometric dimensions of the cups corresponding to the tone values to be engraved. According to the preferred embodiment, laser engraving tools could also be considered as engraving members. Instead of rotogravure cylinders with cups, cylindrical flexoprinting forms could also be engraved according to the preferred embodiment.
For magazine printing, for the most part the various print sides of a print job are simultaneously engraved with a respective engraving member on a printing cylinder on axially parallel, band-shaped cylinder regions called engraving lines.
However, for packaging printing and for similar printing applications (for example pattern or wallpaper printing) it is common practice (as is known from DE 199 47 397 A1) to engrave a printing cylinder in an engraving strip with only one engraving member. However, this procedure has the disadvantage that, in the engraving of large (in particular long) printing cylinders, long engraving times result that can amount to multiple hours. In contrast to this, the advantage is that no visible junctions (to which the human eye is very sensitive) arise in the engraved image.
It is an object to improve a method and a device for engraving printing cylinders for packing printing and similar printing applications such that the times required for engraving the printing cylinders are shortened without visible junctions arising in the engraved image.
In a method or machine for engraving printing cylinders for packaging, pattern, or wallpaper printing and equipped with at least two engraving members, each engraving member engraving elements to be printed into the printing cylinder and, for an areal engraving, executes a feed movement parallel to a longitudinal axis of the printing cylinder. To shorten engraving time, a print image or layout for the printing cylinder is subdivided into at least two circumferential engraving strips, one engraving member being associated with each engraving strip. At least one strip boundary is automatically placed between said engraving strips in at least one white space remaining unengraved between at least some of the elements to be printed.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the preferred embodiment/best mode illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and such alterations and further modifications in the illustrated device and such further applications of the principles of the invention as illustrated as would normally occur to one skilled in the art to which the invention related are included.
The object is achieved according to the preferred embodiment in that at least one strip boundary between is automatically placed between engraving strips in at least one white space that remains unengraved between at least some of the elements to be printed, which strip boundary is placed by the engraving machine provided to engrave the respective printing cylinder or an electronic data processing device that is associated or can be associated with the engraving machine.
In DE 100 10 904 A1 it has basically already been proposed to also use white spaces presented for the packaging printing for a strip between the engraving regions of two engraving members, which there should occur manually in a complicated manner, however. Economically, this basic idea should primarily be implemented automatically via the present preferred embodiment in which the engraving machine or its workstation automatically positions not only the engraving members but also the establishment of the path of a strip boundary according to an automatic interrogation of the existing white spaces, and advantageously after an automatic check of the time savings that is thereby provided. The respective white space that is thereby to be considered should advantageously extend in a width of one engraving strip around the circumference of the printing cylinder; however, it is advantageously also possible to economically use white spaces distributed over the circumference and/or the length extent of the printing cylinder (possibly also of different width and/or length) according to the preferred embodiment for a more economic, time-saving engraving with optionally multiple engraving members. The engraving members can be of the same or different types, in particular can operate mechanically and/or with electromagnetic radiation.
According to the preferred embodiment, an automatic determination of the strip boundary is advantageously possible in that fast feed information is used that is stored for a faster crossing of a white space by an engraving member. Fast feed information is stored for wider white spaces in which the number of engraving tracks of the white space exceeds a predetermined number. This number is appropriately selected so that the time savings achieved by the fast feed justifies the necessary effort to establish a white space as a fast feed region and for the generation and storage of the fast feed information.
Nowadays, information about white spaces of a form to be engraved is normally already available to an engraving machine before the engraving. It has previously served on the one hand to control the automatic crossing of a white space with a speed higher than the engraving speed for the purpose of saving engraving time, and on the other hand to determine the engraving time to be expected.
Information about white spaces can be determined in different ways: in a pre-stage system during the generation of the engraving data, in a separate calculation run on a corresponding workstation or at the engraving machine itself. The engraving format is thereby explicitly communicated to the engraving machine via a manual input or via a digital job packet in what is known as a “job ticket”. According to the preferred embodiment, the engraving machine then independently determines the ideal strip boundary between two engraving strips as well as the shape or the curve of these engraving strips from this aforementioned information.
Given an engraving machine that can be equipped with two engraving members, the strip boundary is advantageously placed in a white space located in the center of the engraving cylinder, for example when the number of engraving elements arranged in parallel on the printing cylinder and separated by white spaces or fast feed spaces is even and one of the white spaces is thereby located approximately in the axial center of the printing cylinder. Otherwise, the strip boundary is appropriately arranged as close as possible to the axial center of the printing cylinder so that approximately the same time is respectively required for the engraving of the engraving strips to be engraved by both engraving members.
Insofar as no suitable line boundary can be established or the engraving time savings to be expected would run below the preset value of a minimum engraving time savings, according to the preferred embodiment the printing cylinder is also advantageously engraved with only one engraving member. According to the preferred embodiment, the decision as to whether and, if necessary, where a strip boundary is established is thus advantageously made depending on the condition of what time savings actually results from the division into engraving lines and the use of multiple engraving members. This time savings is appropriately calculated by the engraving machine or the electronic data processing on the basis of the engraving data, the information about the white spaces or the fast feed information.
A strip boundary is advantageously ideal when the following three conditions are satisfied:
In the method according to the preferred embodiment, a cylinder layout can be designed by positioning the elements to be engraved on a monitor in a workstation with visual inspection, and the strip boundaries can appear in the design of the cylinder layout.
The engraving members are preferably positioned at axial engraving start points (predetermined by the line boundaries) before the engraving.
Protection is also independently claimed for a device for engraving of printing cylinders for packaging printing and similar printing applications in which an engraving member engraves elements to be printed into the printing cylinder in the form of cups and, for areal engraving, executes a feed movement parallel to the longitudinal axis of a printing cylinder (wherein, to shorten the engraving time when a print image or layout for a respective printing cylinder can be subdivided into at least two engraving strips situated parallel to one another in the axial direction, one engraving member can be associated with each engraving strip), which device is characterized in an independent solution of the posed object according to the preferred embodiment in that at least one strip boundary between engraving strips can be automatically established—by the engraving device provided to engrave the respective printing cylinder or an electronic data processing device associated with or that can be associated with the engraving device—in at least one white space remaining unengraved between elements to be printed.
The device according to the preferred embodiment is preferably characterized in that at least two engraving members are arranged on supports or carriages that can be moved independent from one another in the axial direction of a printing cylinder.
The engraving members or their supports or their carriages can thereby advantageously be moved with at least one linear actuator.
As already mentioned in the preceding, the engraving members can in particular possess engraving tools and/or laser engraving tools.
The preferred embodiment is subsequently explained in detail using
A printing form 3 for packaging printing or similar printing applications should be engraved on the printing cylinder 1. The printing form is comprised of a plurality of elements 4 (subsequently called engraving elements) to be engraved, the composition and position of which within the printing form are defined by a cylinder layout generated before the engraving.
To reduce the engraving time, it is proposed to subdivide the printing form 3 into multiple engraving strips (advantageously engraving strips running essentially in the circumferential direction)—in the exemplary embodiment into two circumferential engraving strips A, B—and to engrave each engraving strip A, B with a separate engraving member 5A, 5B. The subdivision of the printing form 3 into the circumferential engraving strips A,B thereby preferably occurs automatically or independently via the engraving machine itself, using the cylinder layout, such that the strip boundaries run between the engraving elements 4, and an (advantageously each) engraving element 4 of an engraving strip A, B is completely engraved by the engraving member 5A, 5B of the corresponding engraving strip A, B in order to save engraving time on the one hand and, on the other hand, to avoid visible junctions in an engraving element 4 that are due to mechanical tolerances of the engraving members 5.
In the shown exemplary embodiment, the engraving members 5A, 5B are mounted on individual engraving supports 6A, 6B that can be shifted on an engraving carriage 7 in the axial direction of the printing cylinder 1 to axial engraving start points SPA and SPB and can be arrested there. The engraving carriage 7 can be moved axially along the printing cylinder 1 by means of a spindle 8 and an engraving carriage actuator 9; at least one linear actuator could advantageously be used instead of these. The engraving supports 6A, 6B can be axially positioned on the engraving carriage 7 by means of manually operable fine actuators or by means of motorized actuators, which can likewise also occur more elegantly via a linear actuator or via the linear actuator according to the preferred embodiment.
Each engraving member 5A, 5B cuts (with its engraving tool or laser tool 10A, 10B) cups or other printing elements arranged in an engraving grid in the manner of engraving strips into the generated surface of the rotating printing cylinder 1 while the respective engraving carriage 7 engraving members 5A, 5B moves axially along the printing cylinder 1.
For example, the engraving occurs in each strip on individual engraving lines running circularly in the circumferential direction around the printing cylinder 1, wherein after engraving one engraving line the engraving carriage 7 respectively executes an axial feed step to the next engraving line. For example, such an engraving method is described in U.S. Pat. No. 4,013,829. Alternatively, the engraving can also occur in a helical engraving line running around the printing cylinder 1. In this case, the engraving carriage moves continuously along the printing cylinder during the engraving.
The engraving tools 10A, 10B of the engraving members 5A, 5B are controlled by engraving control signals GSA and GSB. The engraving control signals GSA and GSB are formed in engraving amplifiers 11A, 11B from the superimposition of a periodic raster signal R on a conductor line 12 with image signal values BA and BB on lines 13A, 13B, which represents the tone values of the cups to be engraved between “light” (white) and “deep” (black). During the periodic raster signal R, a vibrating lifting motion of the engraving tool 10A, 10B for engraving produces the cups arranged in the engraving grid; the image signal values BA and BB corresponding to the tone values to be engraved determine the geometric dimensions of the cups to be engraved.
The analog image signals BA and BB are acquired in D/A converters 14A, 14B from engraving data GDA and GDB of the printing form 3 to be engraved, which data are stored in engraving data memories 15A, 15B and are read out from these engraving lines by engraving conductor line and are supplied to the D/A converters 14A, 14B via data lines 16A, 16B. An engraving datum of at least one byte—which, among other things, contains the tone value (between “light” (GD=161) and “deep” (GD=1)) to be engraved—is thereby associated with each engraving location for a cup in the engraving grid.
The engraving locations in the engraving grid are defined by spatial coordinates (x, y) of an XY coordinate system associated with the printing cylinder 1, the Y-axis of which is oriented in the circumferential direction of the printing cylinder 1 (engraving direction) and the X-axis of which is oriented in the axial direction of the printing cylinder 1 (feed direction). A position transmitter 17 mechanically coupled with the printing cylinder 1 generates the y spatial coordinates and the engraving carriage actuator 9 generates the corresponding x spatial coordinates of the engraving locations on the printing cylinder 1. The spatial coordinates (x, y) are supplied via conductors 18, 19 to an engraving control group 20 that controls the engraving workflows.
From the spatial coordinates (x, y), the engraving control group 20 generates read addresses and corresponding read clock sequences that are supplied via data lines 21A, 21B to the engraving data memories 15A, 15B. Moreover, in the engraving control group 20 the raster signal R is acquired on line 12 and diverse control signals are acquired to control the cylinder actuator 2 and the engraving carriage actuator 9.
The cylinder layout of the printing form 3 to be engraved is designed, for example by an operator offline in workstation 22 via manual positioning of the engraving elements 4 by means of a cursor or via input of position coordinates under visual inspection on an observation monitor 23, and is stored per pixel in the form of layout data in the workstation 22.
During or after the design of the cylinder layout, according to the preferred embodiment strip boundaries (in the exemplary embodiment one line boundary) in the cylinder layout running between at least some of the engraving elements 4 are also automatically established by the workstation 22 (see also
The dimensions of the printing cylinder 1, the possible axial feed paths of the engraving members 5A, 5B or the possible axial feed path of the engraving carriage 7, and possibly also the separation of the engraving members 5A, 5B or engraving carriage 7 from one another are taken into account in the establishment of the strip boundaries. The established strip boundaries are correspondingly marked in the layout data.
Before or after determining the strip boundaries, the engraving data GDA and GDB required for engraving of the individual engraving strips (A, B) are assembled in the workstation 22 engraving line by engraving line from the engraving data (GD*) of the individual engraving elements 4 using the layout regions defined in the cylinder layout. For example, the engraving data (GD*) of the engraving elements 4 are acquired by scanning models or patterns with a scanner and/or by mounting the individual models in an image processing system.
In the generation of the engraving data GD of an engraving line, the engraving data GD of engraving elements 4 are associated with those engraving line segments that belong to the engraving elements 4 while the tone value “super white” representing engraving data (GD>161) is associated with “blank” engraving line segments W (
The engraving data GDA and GDB generated by in the workstation 22 are transferred via data lines 24A, 24B into the corresponding engraving data memories 15A, 15B. Upon transfer of the engraving data GDA and GDB, position data PD (for example the x location coordinates of the engraving start points SPA and SPB in the engraving strips A, B) are simultaneously transmitted via a data line 25 to the control group 20 and are stored there.
For clarification,
An example of an engraving workflow is subsequently explained in detail using
First, the engraving members 5A, 5B are positioned at the engraving start points SPA and SPB of the engraving strips A, B. In the shown exemplary embodiment, the positioning occurs via axial displacement of the engraving supports 6A, 6B on the or with the engraving carriages 7. The positioning of the engraving members 5A, 5B at the engraving start points SP can occur automatically using the position data PD expressed in the workstation 22, controlled by the engraving control group 20.
After the positioning of the engraving members 5A, 5B, the engraving of the engraving strips A, B is implemented. The engraving members 5A, 5B with the fixed separation d from one another are moved along the printing cylinder 1 in the X direction, from the start position. The first engraving member 5A engraves the first engraving strip A from the engraving start point SPA up to the point PA1. The second engraving member 5B engraves the second engraving strip B from the engraving start point SPB up to the point PB and thereby moves from the engraving start point SPB to the point PB while the first engraving member 5A moves at a fixed distance d of the engraving members 5A, 5B from one another from the engraving start point SPA up to the point PA2. Via (preferably separate) feed actuators and/or controllers for the engraving members 5A, 5B, it can be ensured in a simple manner that the engraving members economically move independent of one another; if necessary, they (perhaps intermittently) also take up a park position, and the feed movements of the engraving members 5A, 5B end with the engraving.
In the described exemplary embodiments, the printing form was engraved directly onto the printing cylinder. It also lies within the scope of the preferred embodiment to engrave the printing form on printing plates that are clamped to a printing cylinder.
While preferred embodiments have been illustrated and described in detail in the drawings and foregoing description, the same are to be considered as illustrative and not restrictive in character, it being understood that only two preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention both now or in the future are desired to be protected.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 053 909 | Nov 2007 | DE | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3351009 | Plank | Nov 1967 | A |
| 4013829 | Baar et al. | Mar 1977 | A |
| 4665824 | Greiner et al. | May 1987 | A |
| 6502510 | Breiholdt | Jan 2003 | B1 |
| Number | Date | Country |
|---|---|---|
| 25 08 734 | Aug 1976 | DE |
| 199 47 397 | May 2001 | DE |
| 100 10 904 | Sep 2001 | DE |
| 101 16 672 | Oct 2001 | DE |
| 2001071449 | Mar 2001 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20090122353 A1 | May 2009 | US |
