Method for operating a printing press for flexographic printing

Abstract

An inventive method for operating a flexographic printing press, wherein a web (2) of substrate is unwound, transported, and guided through at least two double printing units (10) of the printing press (1), and wherein the double printing units (10) each comprise at least one impression cylinder (20) and two printing cylinders (30) for flexographic printing, is characterized in that the impression cylinders (20) and the printing cylinders (30) are each driven rotaryally by a separate motor (50), and that a computer (60) of the printing press (1) calculates at least two virtual drive axes (61) and that the computer controls the motors (50) using one of the virtual drive axes (61). The invention advantageously enables the highly productive and flexible operation of a flexographic printing press. The invention is used, for example, in the following applications:used in industrially operated, web-processing flexographic printing machines for packaging printing.

Description

invention

[0001] The invention relates to a method for operating a printing press for flexographic printing with the features of the preamble of claim 1. Such a printing press may include, in addition to flexographic printing units, also additional gravure printing units. field of technology

[0002] The invention lies in the technical field of the graphic arts industry, and therein particularly in the area of ​​operating a flexographic printing press, i.e., a rotary printing press for printing with flexographic printing plates on web-like substrates. Specifically, the invention relates to the subfield of controlling or regulating the machine or its drives and / or actuators. State of the art

[0003] Modern web-processing flexographic printing presses no longer use a so-called main shaft, as revealed, for example, in EP0464309B1, which connects the printing units. Instead, they employ highly dynamic and precise servo motors to drive the printing units. A virtual drive axis, implemented purely computationally and / or electronically, is used instead of a mechanical shaft or axis connecting the printing units.

[0004] There are already web-processing printing presses for flexographic printing that allow for a seamless changeover between two print jobs.

[0005] There are also web-processing flexographic printing presses with a central impression cylinder and two or more impression cylinders arranged around it. Such machines are often very large and difficult to operate. Furthermore, the number of printable colors may be limited, and varnish application may not be possible.

[0006] DE102017222700A1 already discloses a printing machine for printing a substrate web with a plurality of flexographic printing units arranged in series, wherein the flexographic printing units are arranged in a plane accessible to the machine operator, wherein two flexographic printing units of the plurality of flexographic printing units always form a double printing station together, and wherein the two flexographic printing units of a respective double printing station have a common impression cylinder.

[0007] Manufacturers of graphic products—for example, industrial printing companies with prepress, printing, and finishing departments—constantly desire to reduce or even eliminate downtime on their web-processing printing presses. They also demand affordable and compact printing presses. These presses should have short web paths to minimize start-up waste. Finally, they should be flexible enough to handle a wide variety of print jobs. Generally, there is also a desire to improve product quality while maintaining or even increasing production speed. Technical task

[0008] It is therefore an object of the present invention to provide an improvement over the prior art which in particular makes it possible to operate a flexographic printing machine in a highly productive and flexible manner. Inventive solution to the problem

[0009] This problem is solved according to the invention by a method according to claim 1.

[0010] Advantageous and therefore preferred embodiments of the invention are evident from the dependent claims as well as from the description and the drawings.

[0011] A method according to the invention for operating a printing press for flexographic printing, wherein a web of substrate is unwound, transported and guided through at least two double printing units of the printing press, and wherein the double printing units each comprise at least one impression cylinder and each comprise two printing cylinders for flexographic printing, is characterized in that the impression cylinders are each driven rotaryally by a separate motor and that the printing cylinders are each driven rotaryally by a separate motor, and that a computer of the printing press calculates at least two virtual drive axes and that the computer controls the motors each using one of the virtual drive axes. Advantageous forms and effects of the invention

[0012] The invention advantageously enables a flexographic printing press to be operated in a highly productive and flexible manner. The invention is used, for example, in industrially operated, web-processing flexographic printing presses for packaging printing.

[0013] One advantage of the invention is that printing (in one printing unit) and setup (in the other) can occur simultaneously in a double printing unit, or printing can be performed with both units simultaneously, making the printing press highly flexible. A significant advantage of the invention is that the printing ink can also be set up using the double printing unit. This saves considerable downtime and thus increases productivity. Depending on how the printer intends to use the double printing units, they can choose between short web paths, made possible by intermediate drying within the double printing unit, or rapid job changes. Furthermore, a simple changeover from front- to back-side printing is enabled by selecting a different web path and simply reversing the direction of rotation of the rotary axes, i.e., from clockwise to counterclockwise or vice versa.Furthermore, it is advantageous that different formats can be printed simultaneously. Formats differ, for example, when the prints have different lengths in the web direction or when different printing cylinder circumferences are present. Finally, it is advantageous that partial printing units can be operated in the opposite direction of rotation (compared to other partial printing units of the printing press), i.e., "backwards" instead of "forwards" or counterclockwise instead of clockwise. This makes it possible, for example, to print the front and back of a web in a single pass.

[0014] According to the invention, virtual drive axes are used. The virtual drive axes are generated by computer, e.g., based on the principle of a very precisely rotating (mathematical) vector, and are provided for controlling the corresponding rotary drives for cylinders or rollers of the printing press, preferably electric servomotors. Between a virtual axis and the associated real axis of a servomotor, an electronic gearbox and / or a real gearbox can be provided, which effects a transmission from the virtual to the real axis.

[0015] The virtual drive axes can be web transport axes or format axes. A web transport axis controls separate drives for the impression cylinders and / or the web-feeding, driven cylinders or rollers, e.g., cooling rollers or guide rollers. A format axis controls separate drives for the impression cylinders and / or anilox rollers. Since the impression cylinders (or their cores and / or printing plates) can have different formats depending on the print job, a format axis is preferably adapted to the cylinder's current printing format, i.e., the respective angular velocity is adjusted. A web transport axis can be calculated and provided as a master axis, and a format axis as a slave axis related to it. An advantage of coupling via virtual axes is that any real axes (e.g.,Servomotor axes) can also be connected during the operation of the printing press, for example the axes of the anilox rollers can be coupled to the axis of the web transport, especially via electronic gearboxes. Further developments of the invention

[0016] Preferred embodiments of the invention (hereinafter referred to as embodiments) are described below. These can also be combined with one another, unless technically precluded. Virtual drive axles

[0017] Each continuing education program is characterized by the following: that the motors of the impression cylinders are controlled using a common virtual web transport axis. Preferably, a single web transport axis is calculated and provided, e.g., as a rotating vector. that the motors of the impression cylinders are each controlled using separate virtual format axes. Preferably, several format axes are calculated and provided, e.g., as rotating vectors, especially when different formats are printed simultaneously, e.g., on different sides or longitudinal strips of the web. Imprint cylinders, or their rotary drives, of different double printing units can be controlled via different virtual format axes. A printing press can be controlled via several virtual drive axes for a given print job, e.g., via one virtual web transport axis and via one, two, three, or more virtual format axes.that the motors of the printing cylinders of the respective partial printing units of the double printing units are controlled using two virtual format axes. It can be provided that in each double printing unit, one partial printing unit is assigned to a first virtual drive axis, and that the other partial printing units of the double printing units are assigned to a second virtual drive axis. This solution is particularly advantageous for seamless switching between two consecutive print jobs. that the motors of the printing cylinders are controlled using a common virtual format axis. that at least one web tension roller is used in the printing press, wherein the web tension roller is driven rotaryally by a separate motor. that the motor of the web tension roller is controlled using the common virtual web transport axis.that the motor of at least one web tension roller is positively or negatively superimposed in rotational speed with the position or deflection of a dancer roller or a web measuring roller (or a value derived therefrom) using the virtual web transport axis, so that a desired, e.g., predetermined, web tension results. that the control is carried out using the common virtual web transport axis with a web angular velocity. that the respective control is carried out using the respective virtual format axis with a respective format angular velocity. that when printing a print job, the web angular velocity and at least one of the format angular velocities coincide. It can also happen that the two angular velocities differ from each other, e.g., only temporarily and e.g., if a web length change (shrinkage or expansion) needs to be compensated.that when printing a different print job, the web angular velocity and at least one of the format angular velocities differ by a factor other than 1. This allows for a preferably slight compression or stretching of the printed image. that when printing a different print job, the web angular velocity and at least one of the format angular velocities differ by a factor of -1. In this way, at least one partial printing unit of a double printing unit can be operated with a reversed direction of rotation, and the partial printing unit can print on the reverse side of the web; preferably both partial printing units. Switching between front and back printing

[0018] Each continuing education program is characterized by the following: that, during the first print job, the first impression cylinder of a first double printing unit and the second impression cylinder of a second double printing unit rotate in the same direction. that the first impression cylinder is controlled using the common virtual web transport axis, and that the second impression cylinder is controlled using the common virtual web transport axis. that at least two or all double printing units print on the same side of the web during the first print job. that, during a second print job, the first impression cylinder of the first double printing unit and the second impression cylinder of the second double printing unit rotate in opposite directions. In this way, a partial printing unit of a double printing unit can be operated with the direction of rotation reversed, and the partial printing unit can print on the reverse side of the web.that the first impression cylinder is controlled using the common virtual web transport axis and that the second impression cylinder is controlled using the reversed common virtual web transport axis, e.g., using an electronic gearbox. that at least two or all double printing units print on opposite sides of the web during the second print job. that when switching from the first to the second print job, the web path changes from a first double printing unit to a second double printing unit. that the web path during the first print job lies substantially above a horizontal area in which the rotation axes of the impression cylinders are located. that the web path during the second print job lies partially below a horizontal area in which the rotation axes of the impression cylinders are located.that inactive virtual axes are modified during the ongoing production of the printing press, e.g., accelerated or decelerated to a desired or predetermined angular velocity. Changing formats

[0019] Each continuing education program is characterized by the following: that a first double printing unit comprises a first printing cylinder and a second printing cylinder, and that a second double printing unit comprises a third printing cylinder and a fourth printing cylinder. that the first printing cylinder and the third printing cylinder have a first circumferential format. that the second printing cylinder and the fourth printing cylinder have a second circumferential format that differs from the first circumferential format. that the circumferential formats are defined by the outer circumference of the printing cylinders or by the outer circumference of sleeves on the printing cylinders that carry the printed image(s). that at least one flexographic printing plate is arranged circumferentially on each printing cylinder or sleeve. that at least one flexographic printing plate is arranged transversely on each printing cylinder or sleeve. that, during a first printing job, the first printing cylinder and the third printing cylinder rotate at a first angular velocity.that the first angular velocity is given by the first circumferential format. that during the first print job, the second and fourth print cylinders are disengaged from their respective impression cylinders. that during a second print job, the second and fourth print cylinders rotate at a second angular velocity that differs from the first. that the second angular velocity is given by the second circumferential format. that during the second print job, the first and third print cylinders are disengaged from their respective impression cylinders. that during the first print job, the first and third print cylinders are controlled using the same virtual format axes, or that during the first print job, the first and fourth print cylinders are controlled using the same virtual format axes.that in the first print job, the first print cylinder and the third print cylinder are controlled using the same virtual format axis, or that in the first print job, the first print cylinder and the fourth print cylinder are controlled using the same virtual format axis. that in the second print job, the second print cylinder and the fourth print cylinder are controlled using the same virtual format axes, or that in the second print job, the second print cylinder and the third print cylinder are controlled using the same virtual format axes. that in the second print job, the second print cylinder and the fourth print cylinder are controlled using the same virtual format axis, or that in the second print job, the second print cylinder and the third print cylinder are controlled using the same virtual format axis.that for the first and second print jobs, the printing cylinders are controlled using different virtual format axes. that a first print job is produced with rotating first printing cylinders, and meanwhile, a second print job is prepared with stationary second printing cylinders; that the counter-pressure cylinders associated with the first and second printing cylinders rotate coupled to the virtual web transport axis; and that at a given time, e.g., at the end of the first print job, the process switches from the first to the second print job. Railway strip

[0020] Each continuing education program is characterized by the following: that the web is printed on at least one side in at least two parallel longitudinal strips. One longitudinal strip can, for example, be on the drive side (AS) and a second on the operator side (BS). that print jobs with different formats are printed in the longitudinal strips. that print jobs with different longitudinal formats are printed in the longitudinal strips. that print jobs with different transverse formats are printed in the longitudinal strips. Number of counter-pressure cylinders

[0021] Each continuing education program is characterized by the following: that at least one double printing unit with only one impression cylinder is provided and operated. that at least one double printing unit with two impression cylinders is provided and operated. that at least one dryer is provided and operated in the double printing unit. Single print

[0022] Each continuing education program is characterized by the following: that at least one individual printing unit is provided and operated. Drying

[0023] Each continuing education program is characterized by the following: that the web is dried. that at least one dryer is arranged and operated along the web path after each double printing unit, and that the web is dried after each double printing unit. that at least one dryer is arranged and operated along the web path in each double printing unit, e.g., on the impression cylinder or between two impression cylinders, and that the web is dried in each double printing unit. that at least one dryer is arranged and operated along the web path in each double printing unit between two impression cylinders, and that the web is dried in each double printing unit. that the dryer is a hot air dryer. that the dryer is a UV dryer. that the dryer is an IR dryer. Row construction

[0024] Each continuing education program is characterized by the following: that the double printing units are arranged in a horizontal row. that the double printing units are arranged such that the axes of rotation of the impression cylinders lie in a horizontal area. that the double printing units are arranged such that the axes of rotation of the impression cylinders lie in a horizontal plane. that the horizontal plane is at operating height above the floor of a production facility. that four or more colors are printed and that a corresponding number of double printing units are operated. that varnish is applied and that a varnishing unit is operated downstream of the double printing units for this purpose. The varnishing unit can be designed as an intaglio printing unit. that one or more barrier layers are applied in a so-called barrier unit, e.g., as varnish layers, whereby the barrier unit is designed as a single or double printing unit. Rapid changeover and refitting

[0025] Each continuing education program is characterized by the following: that a seamless switch occurs between a first print job and a directly following second print job. This enables uninterrupted production. that, with at least two double printing units, switching occurs from one partial printing unit to the other, or vice versa. that the switching is register-accurate. This prevents waste. that the switching is precise along the path. Waste is avoided by switching in such a way that the two print jobs or the corresponding print images lie on the web with virtually no longitudinal distance to each other. that the switching is performed in such a way that essentially no waste is produced. that one partial printing unit is set up while the other partial printing unit is printing. that at least one printing plate is changed during setup. that at least one core with at least one printing plate is changed during setup.that the print image is changed during setup. that the format is changed during setup. that the format length is changed during setup. that the format width is changed during setup. that at least one printing color is changed during setup. that the computer calculates a first virtual drive axis for the motors of the impression cylinders of double printing units, that the computer calculates a second virtual drive axis for the motors of the format cylinders of the first partial printing units of the double printing units for a first print job and a third virtual drive axis for the motors of the format cylinders of the second partial printing units of the double printing units for a directly following second print job, and that the switch from the first print job to the second print job is seamless, whereby the switch is made from the second virtual drive axis to the third virtual drive axis.This solution is particularly advantageous for seamless, register-compliant, and precise switching between the respective partial printing units of the double printing units, as production continues uninterrupted and waste is reduced or avoided, especially when the format changes between the two print jobs. The system calculates a first virtual drive axis for the motors of the impression cylinders of the double printing units, a second virtual drive axis for the motors of the format cylinders of both partial printing units of the double printing units for a first and a directly following second print job, and the switch from the first to the second print job is seamless, while maintaining the second virtual drive axis.This solution is particularly advantageous for seamless, register-compliant, and precise switching between the respective partial printing units of the dual printing units, as production continues uninterrupted and waste is reduced or avoided, especially if the format does not change between the two print jobs and a die-cutting tool, e.g., a rotary die-cutter or a flatbed die-cutter, is planned for use after printing. Further processing

[0026] Each continuing education program is characterized by the following: that a finishing station is located downstream of the double printing units in the production direction. that the finishing station comprises a sheet-fed die-cutter with one die-cutting unit, or several sheet-fed die-cutters, each with one die-cutting unit, or at least one double-sheet-fed die-cutter with two die-cutting units. that the die-cutting format is adjusted when the printing format is changed. that the die-cutting format is adjusted by switching between die-cutting units. that the die-cutting format is adjusted by a flying change of die-cutting tools. that the finishing station comprises at least one semi-rotary die-cutter. that the semi-rotary die-cutter comprises a die-cutting cylinder with a circumference of length L1 and a die-cutting tool of length L2 arranged on the die-cutting cylinder, where L2 <L1.that a die-cutting cylinder of the semi-rotary die-cutting machine is driven with an alternating angular velocity – between a higher and a lower angular velocity – with the lower angular velocity being used during die-cutting. that the semi-rotary die-cutting machine includes a web storage unit. that the downstream processing station includes at least one sheet cutter for cross-cutting the web into sheets.

[0027] The invention also makes it possible to retrofit a double printing unit and thereby switch from front-side printing to back-side printing (or vice versa) and / or to change the printing format and / or to change the printing format in a longitudinal strip.

[0028] The technical features and combinations of features disclosed in the above sections Technical Field, Invention and Further Developments, as well as in the following section Exemplary Embodiments, represent – ​​in any combination with one another – further advantageous developments of the invention. Alternative solution

[0029] As an alternative to the invention, a technical solution could be considered that uses only one virtual drive axis instead of several. This virtual drive axis preferably controls the rotary drives / motors of the counter-pressure cylinders. From this virtual drive axis, the format cylinders are controlled via so-called electronic gearboxes, i.e., using a highly accurate conversion factor. Exemplary embodiments of the invention and figures

[0030] The figures show preferred embodiments of the invention and its further developments. Corresponding features are identified in the figures by the same reference numerals. For clarity, some reference numerals that are repeated in the figures have been omitted.

[0031] In the figures, NoD denotes a so-called "non-stop deck," i.e., a double printing unit without intermediate drying, in which either one or the other printing unit prints. Furthermore, in the figures, DoD denotes a so-called "double deck," i.e., a double printing unit with (optional) intermediate drying, in which either one or the other printing unit prints (without intermediate drying), or in which both printing units print and are dried in between.

[0032] Figure 1Figure 1 shows a configuration of at least two double printing units 10 and 11 and 12 in a flexographic printing press 1, which allows both one side 2a ("front") and the other side 2b ("back") of the web 2 to be printed. For this purpose, the web path 4 is first guided horizontally under the second double printing unit 12 (shown on the left in the figure) and its cylinders, then guided upwards, and finally fed into the double printing unit 12 from above. It can be seen that the two impression cylinders 20 and 21 and 22 of the double printing units 10 shown rotate in opposite directions (as do the other cylinders of the partial printing units 13 and 14 of the double printing units 10). Reversing rod arrangements with diagonally arranged reversing rods are advantageously not required in this configuration. Figure 1also shows a computer 60, preferably a digital computer, e.g. an existing printing press computer or a separate control computer, which calculates the virtual drive axes 61 and provides them to the printing press 1 or the rotary drives 50. Figure 1 It also shows a section of track 2 in top view with two longitudinal stripes 3 and track direction 70.

[0033] Figure 2 shows a similar configuration to Figure 1 , where first the reverse side 2b and then the front side 2a are printed. The two configurations shown can also be combined (in one order or the other).

[0034] Also Figure 3 shows a similar configuration, where one of the two double printing units 10 comprises two counter-pressure cylinders 20 or 21 and 22.

[0035] Figure 4The following is shown: A web-processing flexographic printing press 1 (also called printing plant, system or machine) comprises at least one illustrated double printing unit 10 with side walls 53, a partial printing unit A or 13, a partial printing unit B or 14 and a common impression cylinder GDZ or 20; in addition, two printing cylinders DZ or 30 and two anilox cylinders RZ or 40. Figure 4 also shows a computer 60, preferably a digital computer, e.g. an existing printing press computer or a separate control computer, which calculates the virtual drive axes 61 and provides them to the double printing unit 10 or the rotary drives 50. Figure 4Figure 30 also shows a sectional view through an exemplary pressure cylinder DZ or 30 with an (axially slidable) sleeve 35 and at least one (mounted on the sleeve) pressure form 36. The GDZ cylinder 20 is mounted in bearing blocks 55, the DZ cylinders 30 are mounted in adjustable bearing blocks 54, and the cylinders 40 are mounted in further adjustable bearing blocks 54. The adjustable bearing blocks 54 are adjustable in direction 71 by means of positioning drives 52. The DZ cylinders 30 are also adjustable in axial direction 72 by means of positioning drives 51.

[0036] The following nomenclature is used for the drives in the double printing unit 10 with the two partial printing units A and B: (A)Rot_DZ: Rotary drive 50 for the impression cylinder in sub-unit A; (A)Rot_RZ: Rotary drive 50 for the anilox cylinder in sub-unit A; Rot_GDZ: Rotary drive 50 for the common impression cylinder; (A)Posi_Axial: Positioning drive 51 for the page register in sub-unit A; (A)Posi_DZAS: Positioning drive 52 for the impression cylinder in sub-unit A on the drive side; (A)Posi_DZBS: Positioning drive 52 for the impression cylinder in sub-unit A on the operator side; (A)Posi_RZAS: Positioning drive 52 for the anilox cylinder in sub-unit A on the drive side; (A)Posi_RZBS: Positioning drive 52 for the anilox cylinder in sub-unit A on the operator side; Corresponding drives (B)... are provided for sub-unit B.

[0037] In sub-unit A, the first print job is running. Simultaneously, a second print job can be prepared in sub-unit B, or sub-unit B can be serviced, for example, a blade change can be performed on the doctor blade of anilox roller 40. The drives Rot_GDZ, (A)Rot_DZ, and (A)Rot_RZ are running for production in sub-unit A. The (A)Posi_Axial drive compensates for side register fluctuations, and the (A)Rot_DZ drive compensates for longitudinal register fluctuations. During speed changes, the positioning pairs (A)Posi_DZAS / (A)Posi_DZBS, as well as (A)Posi_RZAS and (A)Posi_RZBS, move within the production process, although these positioning pairs do not necessarily have to move in parallel.

[0038] At a certain point, the first job is complete. To produce the second print job, the partial printing unit B automatically moves into the printing position to print the second job – using the first printing color of the entire printing system. For this, the drives (preferably servo drives) (B)Rot_DZ and (B)Rot_RZ are brought up to speed, such that this speed matches the dimensions of the flexographic print design and that it is aligned with the first job (if possible due to identical page sizes of the two print jobs) or with a die-cutter 44 (or a sheet cutter). Once the speed is reached, the positioning motors (B)Posi_DZAS and (B)Posi_DZBS as well as (B)Posi_RZAS and (B)Posi_RZBS move into the optimal flexographic printing position to produce a high-quality flexographic print design. The data for the pressing or print delivery can come from an internal or external data carrier, such as a database.Data for pressing or printing delivery can also be used from an external scanner that has determined the topography of the flexographic printing form(s) used.

[0039] If necessary, the register sensor can be optionally moved axially by a motor, so that it moves directly to the location of the print marks, which may differ between two jobs, detects the register marks, and adjusts them longitudinally and laterally (longitudinal and lateral register control). This is timed to minimize waste. The data for the register mark position can come from an internal or external data carrier, such as a database. Alternatively, data for the print mark position can be used from a scanner that detects the print marks and provides their axial and / or lateral location, e.g., as an XY coordinate, to the dual printing unit. This data can preferably be stored in a cloud or database. As soon as the register mark(s) are detected by the sensor, the longitudinal register is controlled via the servo drive (B)Rot_DZ and the lateral register via (B)Posi_Axial.

[0040] Virtually simultaneously, the first job with the corresponding color is completed in sub-unit A, and the printing and anilox cylinder, along with the positioning drives (A)Posi_RZAS / BS and (A)Posi_DZASBS, is removed from the substrate and printing cylinder, respectively. The printing cylinder (A)Rot_DZ is brought to a standstill so that the ink sleeve can be safely changed in sub-unit A, allowing for immediate preparation of the next job (third job). If necessary, the anilox roller's screen ruling must be changed; for this, (A)Rot_RZ is brought to a safe stop. All of this occurs while production continues in sub-unit B. If it is not necessary to change the screen ruling, for example, by changing the anilox roller or anilox sleeve, the drive (A)Rot_RZ continues to run at a predetermined speed to prevent ink drying.

[0041] Now, the same process is performed with the second printing unit (of another double printing unit) – precisely along the same path. This means the second printing unit performs these steps exactly as before, but at the exact point on the web where the first printing unit (of the first double printing unit) completed them, thus minimizing waste. The printing units synchronize – where possible – with register-accurate precision from the first job to the second, ensuring no waste is generated in an optional downstream die-cutter (or sheet cutter). Furthermore, it is also possible to switch to a different print format, for example, changing from a 680 mm to a 642 mm perimeter on the fly. This requires at least two virtual drive axes, which process two different print formats within the printing press. This allows two different print formats to be printed simultaneously side-by-side in the machine.

[0042] Furthermore, when changing between print jobs, the register sensor can be moved axially via a motorized register sensor traverse, so that the register marks differ between the first and second applications both in the direction of travel and perpendicular to the direction of travel. Information on the location of the register marks can be obtained from a scanner that has scanned the position of the register marks on a printing sleeve (and preferably from an identification feature, e.g., a QR code or RFID chip). This information can be stored in a database or, for example, in the cloud. Alternatively, it can also come from a prepress information database (e.g., cloud-based) or as a PDF. The QR code, or another 2D code, or the RFID chip can be scanned or queried as an identification feature, and the resulting ID can be used to retrieve associated data, e.g.,from a local or cloud-based database, to be retrieved and transferred to the printing unit for setting.

[0043] It is possible that a motorized register sensor traverse with corresponding sensors or cameras for front and back printing is installed in the printing unit, which generates the respective information on where the register marks are located, as described in the previous paragraph.

[0044] Figure 5 The following is shown: A web-processing flexographic printing press 1 (also called printing plant, system or machine) comprises at least one illustrated double printing unit 10 with a partial printing unit A or 13, a partial printing unit B or 14 and two impression cylinders GDZ or 20, 21, 22.

[0045] In printing unit A, the first job is running. Simultaneously, a second job can be prepared in printing unit B, or maintenance can be performed in printing unit B, for example, a blade change on the doctor blade. At a certain point, the first job is finished. Printing unit B then automatically moves to the printing position to print the second job – using the first printing color. Virtually simultaneously, the first job is completed in printing unit A using the corresponding color.

[0046] Now the same thing is done with the second printing unit (of another double printing unit) - and precisely along the same path, i.e. the second printing unit performs these steps in the same way, but exactly at the point on the material web where the first printing unit (of a first double printing unit) has done so, in order to save waste in this way.

[0047] The printing units synchronize – where possible – with register-accurate precision from the first job to the second, so that no waste is generated in an optional downstream die-cutter (or sheet cutter). Furthermore, it is also possible to switch to a different print format, in which case the first printing unit is preferably synchronized with the second printing unit with register-accurate precision.

[0048] The changeover is event-driven – based on time, distance, quantity, splice, material change, or button press. The system is capable of processing multiple orders simultaneously and sequentially.

[0049] If at least one intermediate dryer is used in the double printing unit, both partial printing units A and B of a double printing unit can print simultaneously. If a double printing unit with two impression cylinders is used, the printing speed can potentially be increased due to the longer drying distance (between the two impression cylinders). Furthermore, it is possible, as described in relation to Figure 4 As previously described, a double printing unit can preferably print two different circumferences side by side. For example, printing unit A on the AS side (drive side of the machine) can print a circumference of 480 mm onto the web, and printing unit B on the BS side (operator side of the machine) can print or prepare a circumference of 960 mm onto the web. The impression cylinders of printing units A and / or B can be temperature-controlled, particularly cooled, so that the respective impression cylinder does not expand when heated.

[0050] Figure 6Figure 1 shows a web-processing, industrial flexographic printing press 1 with (from right to left, or in the production direction 70 shown as an arrow) a roll changer 45 for the web to be printed, a web feeder 46, six double printing units 10, each with dryers 43 arranged above them, and a rewinder 47 for the printed and dried web 2. The machine 1 also includes a computer 60, e.g., a control computer. Alternatively, the production direction 70 can also be reversed (i.e., from left to right in the diagram), in which case the functions of the rewinding units 45 and 47 (unwinding and rewinding) are reversed.

[0051] Figure 7Figure 1 shows a double printing unit 10 with a single impression cylinder 20 and two partial printing units 13, 14, each with a (flexographic) printing cylinder 30 and an anilox roller 40. The printing cylinders 30 can be switched off separately from the impression cylinder 20, as can the anilox rollers 40 from the printing cylinders 30. At least one (hot air) dryer 43 is arranged in the superstructure of the double printing unit 10. Such double printing units 10 can be arranged in a horizontal row 84. Figure 7 also shows a horizontal area 82 (in which the rotation axes 23 of the counter-pressure cylinders 20 are located) and - more precisely - a horizontal plane 83 (in which the rotation axes 23 of the counter-pressure cylinders 20 are located) at an operating height 81 above the floor 80. Figure 7 also shows five rotary drives 50 (electric motors) for the separately driven cylinders / rollers 20, 30 and 40, which are controlled by the computer 60 using the virtual drive axes 61.

[0052] Figure 8 Figure 1 shows a double printing unit 10 with two impression cylinders 20 and two partial printing units 13, 14, each with one (flexographic) printing cylinder 30 and one anilox roller 40. The printing cylinders 30 can be switched off separately from their respective impression cylinders 20, as can the anilox rollers 40 from the printing cylinders 30. At least one (hot air) dryer 43 is arranged in the superstructure of the double printing unit 10. Such double printing units 10 can be arranged in a horizontal row 84. Figure 8 Figure 60 also shows six rotary drives 50 (electric motors) for the separately driven cylinders / rollers 20, 30 and 40, which are controlled by the computer 60 using the virtual drive axes 61. It is also possible to drive the two counter-pressure cylinders 20 of the double printing unit 10 using a common drive 50, preferably an electric motor, e.g. by means of a gearbox and / or belt.

[0053] Figure 9 shows a similar printing press 1 as Figure 6 , wherein the printing press 1 has an additional single printing unit 15, preferably in the production direction 70 after the existing double printing units 10. This single printing unit 15 can be used for applying varnish, e.g. as a flexographic printing unit or as a gravure printing unit. Additionally or alternatively, a double gravure printing unit could also be present.

[0054] The following six exemplary operating modes are possible with the double printing units shown: 1) Flexographic printing press for front / back printing via selectable web threading path and reversible rotation of the rotary cylinder axes. The front and back can be printed with perfect registration, but different print formats are also possible. Examples: front 490 mm and back 980 mm, where the colors are printed and controlled in register on both sides, or 490 mm and 680 mm printed one below the other with perfect registration. The following axes are reversed in the direction of rotation during front-to-back printing: (A)Rot_RZ, (B)Rot_RZ, (A)Rot_DZ, (B)Rot_DZ, (A)Rot_GDZ at the DoD unit, (B)Rot_GDZ at the DoD unit, Rot_GDZ at the NoD unit, Rot_KUW (rotational drive of the driven cooling roller, if present and change of direction of rotation necessary) and Rot_LW (rotational drive of the driven guide roller(s), if present and change of direction of rotation necessary).2) Register-accurate job change between two jobs, wherein the changeover is made register-accurately to a die-cutting machine (rotary die-cutting machine, flatbed die-cutting machine, semi-rotary die-cutting machine, or sheet cutter) with the same package size, e.g., a 1-liter orange juice carton is changed on the fly to a 1-liter grape juice carton, such that this fits the die-cutting machine or sheet cutter with register accuracy. The die-cutting machine or sheet cutter is preferably located at the end of the printing press. The cross-cutting of the web by the sheet cutter can advantageously be changed register-accurately during the job changeover and adapted to the new job. 3) Register-accurate job change between two jobs, wherein the changeover is made register-accurately to a die-cutting machine (rotary die-cutting machine, flatbed die-cutting machine, semi-rotary die-cutting machine, or sheet cutter) with a different package size, e.g.,A 1-liter orange juice carton is changed to a 0.75-liter grape juice carton on the fly, such that the die-cutter inserts the die-cutting tool into the process with precise registration and distance at the moment of the changeover, or the sheet cutter adjusts its cutting length with precise registration and distance – in such a way that minimal waste is generated and the production speed, e.g., 400 m / min, remains constant before, during, and after the changeover. The die-cutter or sheet cutter is preferably located at the end of the printing press. 4) A register sensor controls at least one or both colors of the double printing unit for front-side printing; a register sensor controls at least one or both colors of the double printing unit for back-side printing. 5) The double printing unit receives printing setting data from an external scanner for flexographic printing plates and uses the drives (A)Posi_DZAS, (B)Posi_DZAS, (A)Posi_RZAS, (B)_Posi_RZBS, (A)Posi_Axial, (B)Posi_Axial to adjust the pressure or pressure.The print delivery. 6) Two different formats can be printed in register. At least two virtual format axes enable at least two different print formats, i.e., cylinder circumferences, to be printed and prepared in the machine with register accuracy, or at least two print circumferences to be printed simultaneously and with register accuracy side by side. Example: 680 mm and 480 mm circumference, or an integer multiple thereof. Multiple print jobs with different circumferences can also be printed simultaneously, e.g., three or four, i.e., four different package sizes side by side. Reference symbol list

[0055] 1 Printing press 2 Web 2a One side of the web 2 Other side of the web 3 Longitudinal strip of the web 4 Web path 4a Web path section (in the double printing unit between two impression cylinders) 10 Double printing unit(s) 11 First double printing unit 12 Second double printing unit 13 First partial printing unit 14 Second partial printing unit 15 Single printing unit 20 Impression cylinder 21 First impression cylinder 22 Second impression cylinder 23 Pivot points of the impression cylinders 30 Printing cylinder 31 First printing cylinder 32 Second printing cylinder 33 Third printing cylinder 34 Fourth printing cylinder 35 Sleeve(s) 36 Printing form(s) 37 First perimeter format 38 Second perimeter format 40 Anilox rollers 41 Web tension roller(s) 42 Cooling roller(s) 43 Dryer 44 Die cutter or cutter 45 Roll changer 46 Web feeder 47 Rewinder 50 Drive(s), in particular rotary drive(s) 51 Drive(s), in particular positioning drive(s) 52 Drive(s),in particular positioning drive(s) 53 side wall 54 adjustable bearing blocks 55 bearing blocks 60 computer 61 virtual drive axis 62 virtual web transport axis 63 virtual format axis 70 production direction 71 circumferential / longitudinal direction 72 transverse direction 73 first direction of rotation 74 second direction of rotation 80 floor of a production facility 81 operating height 82 horizontal area 83 horizontal plane 84 horizontal row of printing units, in particular double printing units,

Claims

1. Method for operating a printing press for flexographic printing, wherein a web (2) of substrate is unwound, transported and guided through at least two double printing units (10) of the printing press (1) and wherein the double printing units (10) each comprise at least one impression cylinder (20) and each comprise two printing cylinders (30) for flexographic printing, characterized by that the counter-pressure cylinders (20) are each driven rotaryally by a separate motor (50) and the printing cylinders (30) are each driven rotaryally by a separate motor (50), and a computer (60) of the printing machine (1) calculates at least two virtual drive axes (61) and the computer controls the motors (50) each using one of the virtual drive axes (61).

2. Method according to claim 1, characterized by thatthe motors (50) of the counter-pressure cylinders (20) are controlled using a common virtual rail transport axis (62).

3. Method according to claim 2, characterized by that the motors (50) of the printing cylinders (30) are each controlled using separate virtual format axes (63), or that the motors (50) of the printing cylinders (30) are controlled by respective partial printing units (13, 14) of the double printing units (10) using two virtual format axes (63), or that the motors (50) of the printing cylinders (30) are controlled using a common virtual format axis (63).

4. Method according to claim 3, characterized by that The control is carried out using the common virtual rail transport axis (62) with a rail angular velocity.

5. Method according to claim 4, characterized by thatThe respective control is carried out using the respective virtual format axis (63) with a respective format angular velocity.

6. Method according to claim 5, characterized by that When printing a print job, the web angular velocity and at least one of the format angular velocities must match.

7. Method according to claim 5, characterized by that When printing a different print job, the web angular velocity and at least one of the format angular velocities differ by a factor other than 1.

8. Method according to claim 5, characterized by that When printing a different print job, the web angular velocity and at least one of the format angular velocities differ by a factor of -1.

9. Method according to any one of the preceding claims, characterized by thatat least two or all double printing units (10) print on opposite sides (2a, 2b) of the web (2) in a first print job and a second print job.

10. Method according to claim 9, characterized by that When switching from the first print job to the second print job, the web path (4) is changed from a first double printing unit (11) to a second double printing unit (12).

11. Method according to claim 10, characterized by that The path (4) during the first print job lies essentially over a horizontal area (82) in which the axes of rotation (23) of the counter-pressure cylinders (20) are located.

12. Method according to claim 11, characterized by that The path (4) during the second print job lies partially under a horizontal area (82) in which the axes of rotation (23) of the counter-pressure cylinders (20) are located.

13. Method according to any one of the preceding claims, characterized by thatin a first print job a first printing cylinder (31) of a first double printing unit (11) and a third printing cylinder (33) of a second double printing unit (12) are controlled using the same virtual format axes (63) or that in a first print job a first printing cylinder (31) of a first double printing unit (11) and a fourth printing cylinder (34) of a second double printing unit (12) are controlled using the same virtual format axes (63).

14. Method according to claim 13, characterized by thatin a second print job a second printing cylinder (32) of a first double printing unit (11) and a fourth printing cylinder (34) of a second double printing unit (12) are controlled using the same virtual format axes (63) or that in a second print job a second printing cylinder (32) of a first double printing unit (11) and a third printing cylinder (33) of a second double printing unit (12) are controlled using the same virtual format axes (63).

15. Method according to claim 14, characterized by that During the first print job and the second print job, the print cylinders (30) are controlled using different virtual format axes (63).

16. Method according to any one of the preceding claims, characterized by that the web (2) is printed on at least one side (2a, 2b) in at least two longitudinal strips (3) parallel to each other.

17. Method according to claim 16, characterized by that Print jobs with different formats can be printed in the longitudinal strips (3).

18. Method according to any one of the preceding claims, characterized by that at least one dryer (43) is arranged and operated on the web path (4) in each double printing unit (10) between two counter-pressure cylinders (20) and that the web (2) is dried in each double printing unit (10).

19. Method according to any one of the preceding claims, characterized by that the double printing units (10) are arranged in a horizontal row (83) and are operated.

20. Method according to claim 19, characterized by that the double printing units (10) are arranged such that the axes of rotation (23) of the counter-pressure cylinders (20) lie in a horizontal area (82).

21. Method according to any one of the preceding claims, characterized by thatThe system switches seamlessly between a first print job and a directly following second print job.

22. Method according to claim 21, characterized by that with at least two double printing units (10) switching from one partial printing unit (13) to the other partial printing unit (14) or vice versa.

23. Method according to claim 22, characterized by that The switching is carried out in accordance with the register.

24. Method according to claim 22 or 23, characterized by that The switching is performed with precise route accuracy.

25. Method according to any one of the preceding claims 22 to 24, characterized by that the format is changed.

26. Method according to any one of the preceding claims 22 to 25, characterized by that at least one printing color is changed.

27. Method according to any one of the preceding claims, characterized by thatThe computer (60) calculates a first virtual drive axis (62) for the motors (50) of the impression cylinders (20) of double printing units (10), calculates a second virtual drive axis (63) for the motors (50) of the format cylinders (20) of first partial printing units (13) of the double printing units (10) for a first print job, and a third virtual drive axis (63) for the motors (50) of the format cylinders (20) of second partial printing units (14) of the double printing units (10) for a directly following second print job, and calculates that the switch from the first print job to the second print job is seamless, with a switch from the second virtual drive axis (63) to the third virtual drive axis (63).

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