Method for operating printing machine for flexographic printing

Abstract

SOLUTION: There is provided a method for operating a printing machine for flexographic printing, wherein a web 2 of a printed material is unwound, transported and thereby guided through at least two double printing units 10 of the printing machine 1. Each of the double printing units 10 has at least one impression cylinder 20 and in each case two printing cylinders 30 for flexographic printing. The impression cylinders 20 are each driven in rotation by a separate motor 50 and the printing cylinders 30 are each driven in rotation by a separate motor 50. A computer 60 of the printing machine 1 calculates at least two virtual drive axes 61 and the computer controls the motors in each case using one of the virtual drive axes 61.EFFECT: The invention makes it possible to operate a flexographic printing machine in a highly productive and flexible manner. The invention is particularly suitable, for example, in industrially operated, web-processing flexographic printing machines for packaging printing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for operating a printing press for flexographic printing having the features of the preamble of claim 1. Such a printing press may comprise, besides a flexographic printing unit, an additional intaglio printing unit.

[0002] Technical Field The invention is located in the technical field of the graphics industry, in particular in the field of operation of flexographic printing machines, i.e. rotary printing machines for printing a web-like substrate with flexographic printing plates, in which the invention is particularly located in the subfield of open-loop or closed-loop control of the machines or their drives and / or actuation drives.

[0003] Background technology Modern web-handling printing presses for flexographic printing do not operate via so-called king shafts that drive the printing units, as disclosed, for example, in EP 0 464 309 B1, but instead have highly dynamic and precise servo motors for driving the printing units, in which case, instead of mechanical shafts or axes connecting the printing units, virtual drive axes are used that are realized purely computationally and / or electronically.

[0004] There are already web-handling presses for flexographic printing that allow on-the-fly changeover of two print jobs.

[0005] There are also web-handling presses for flexographic printing that have one central impression cylinder and two or more printing cylinders arranged around it. These presses are often quite large and difficult to operate. Furthermore, they may have a limited maximum number of inks that can be printed, making varnishing impossible.

[0006] DE 10 2017 222 700 A1 already discloses a printing machine for printing on a substrate web, which comprises a plurality of flexographic printing units arranged in series, which flexographic printing units are arranged in a plane accessible to the machine operator, and in which always two of the flexographic printing units together form a double printing station, and in which the two flexographic printing units of each double printing station have a common impression cylinder.

[0007] There is a continuous demand on the part of manufacturers of graphic products, i.e., industrially operating printing companies that perform, for example, prepress, actual printing, and post-printing, to reduce or even prevent downtime of their web-processing printing presses. There is also a demand for convenient and compact printing presses. There is also a demand for printing presses that have short web paths and thus generate little so-called start-up waste. Finally, there is a demand for printing presses that can be used flexibly for different printing jobs. In general, there is also a demand for improving product quality while maintaining or even increasing production speed.

[0008] Technical challenges The object of the present invention is therefore to provide an improvement over the prior art, which in particular makes it possible to operate flexographic printing machines productively and flexibly.

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

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

[0011] A method according to the present invention for operating a printing press for flexographic printing, comprising unwinding, transporting and, during transport, guiding a web of printing substrate through at least two double printing units of the printing press, the double printing units each comprising at least one impression cylinder and two printing cylinders for flexographic printing, the method being characterized in that the impression cylinders are each driven to rotate by a separate motor and the printing cylinders are each driven to rotate by a separate motor, a computer of the printing press calculates at least two virtual drive axes and the computer controls the motors using one of the virtual drive axes, respectively.

[0012] Advantageous Configurations and Effects of the Invention The invention advantageously allows for a highly productive and flexible operation of flexographic printing machines, for example in industrially operated web-handling flexographic printing machines for packaging printing.

[0013] The advantage of the present invention is that simultaneous printing (in one partial printing unit) and preparation (in the other partial printing unit) can be performed in one double printing unit, or printing can be performed by both partial printing units, making the printing press extremely flexible. In this case, an important advantage of the present invention is that printing ink can also be prepared in the double printing unit. This reduces lengthy downtimes and therefore increases productivity. Depending on how the printer wishes to use the double printing unit, he can decide between short web paths made possible by intermediate drying in the double printing unit or quick job changes. Furthermore, a simple change from front to back printing is possible by selecting a different web path and simply reversing the rotation direction of the rotating shaft, i.e., from clockwise to counterclockwise or vice versa. It is also advantageous to be able to simultaneously print different sizes. The sizes differ, for example, when the printed products have different lengths in the web running direction or when the printing cylinder circumferences are different. Finally, it is advantageous if the partial printing device can be operated in a counter-rotational direction (compared to other partial printing devices of the printing press), i.e., for example, "backward" instead of "forward" or counterclockwise instead of clockwise, thereby making it possible, for example, to print on the front and back of the web in one pass.

[0014] According to the invention, a virtual drive axis is used, which is generated, for example, with the aid of a computer based on the principle of highly accurate rotational (mathematical) vectors and is used to control the corresponding rotary drives, preferably electric servomotors, for the cylinders or rollers of a printing press. Between the virtual axis of the servomotor and the corresponding real axis, there may be a so-called electronic and / or real transmission that produces a speed change from the virtual axis to the real axis.

[0015] The virtual drive axis may be a web-transport axis or a size axis. The web-transport axis is used to control separate drives for the impression cylinder and / or the driven cylinders or rollers transporting the web, such as cooling rollers or, if appropriate, guide rollers. The size axis is used to control separate drives for the printing cylinder and / or the anilox roller. Since the printing cylinders (or their sleeves and / or printing plates) may have different sizes depending on the print job, the size axis is preferably adapted to the size of the cylinder currently to be printed, i.e., the respective angular velocities are adapted. The web-transport axis may be calculated and provided as a master axis, and the size axis may be provided as a slave axis associated with it. The advantage of virtual axis coupling is that any real axes (e.g., servo motor axes) can be connected even during operation of the printing press; for example, the axis of the anilox roller can be coupled to the axis of the web transport, especially via an electronic transmission.

[0016] Improvements of the invention In the following, preferred refinements (abbreviated as refinements) of the invention will be described, which refinements may be combined with one another if this is not technically excluded.

[0017] Virtual Drive Axis Each improved form is: The impression cylinder motors are controlled using a common virtual web transport axis. Preferably, only one web transport axis is calculated and provided, for example, as a rotational vector. The motors of the printing cylinders are controlled using separate virtual size axes. Preferably, several size axes are calculated, e.g., provided as rotational vectors, especially if different sizes are simultaneously printed, e.g., on different sides or longitudinal stripes of the web. The printing cylinders or their rotary drives of different double printing units may be controlled via different virtual size axes. A printing press may be controlled for a given print job via several virtual drive axes, e.g., a virtual web-transport axis and one, two, three or more virtual size axes. The motors of the printing cylinders of each of the partial printing units of a double printing system are controlled using two virtual size axes. It can be specified that in each double printing system, one partial printing unit is assigned to a first virtual drive axis, and the other partial printing unit of the double printing system is assigned to a second virtual drive axis. This solution is particularly advantageous when changing over between two immediately successive print jobs. The print cylinder motors are controlled using one common virtual size axis. At least one web tension roller is used in the printing machine, which is driven in rotation by a separate motor. The motors of the web tension rollers are controlled using a common virtual web transport axis. The motor of at least one web tension roller is superimposed on the position or displacement of the dancer roller or web measuring roller (or a value derived therefrom) using a virtual web transport axis, positively or negatively in terms of the number of rotations, thereby resulting in a desired, e.g., preset, web tension. Control is performed at a given web angular velocity using a common virtual web transport axis. Each control is performed at each predetermined size angular velocity using each virtual size axis. When printing a print job, the web angular velocity and at least one of the size angular velocities match. It may also occur that both angular velocities differ from each other, for example only temporarily and for example to compensate for web length changes (shrinkage or expansion). When printing another print job, the web angular velocity and at least one of the size angular velocities differ by a factor not equal to 1. This allows for preferably only slight compression or expansion of the printed image. When printing another print job, the web angular velocity and at least one of the size angular velocities differ by a factor of −1. In this way, at least one partial printing device of a double printing device can be operated in the opposite rotation direction, in which case this partial printing device, preferably both partial printing devices, can print on the reverse side of the web. It is characterized by the following.

[0018] Change between front and back printing Each improved form is: During the first print job, the first impression cylinder of the first double printing device and the second impression cylinder of the second double printing device rotate in the same direction of rotation. The first impression cylinder is controlled using a common imaginary web transport axis and the second impression cylinder is controlled using a common imaginary web transport axis. During the first print job, at least two or all of the double printing devices print on the same side of the web. During the second print job, the first impression cylinder of the first double printing device and the second impression cylinder of the second double printing device rotate in opposite directions, so that one partial printing device of one double printing device can operate in the opposite direction, and in this case, the partial printing device can print on the back side of the web. The first impression cylinder is controlled using a common virtual web-transport axis and the second impression cylinder is controlled using a reversed common virtual web-transport axis, for example using a so-called electronic transmission. During the second print job, at least two or all of the double printing devices print on opposite sides of the web. When changing a first print job to a second print job, the web path is changed from the first double printing device to the second double printing device. During the first print job, the web path is located substantially above the horizontal area in which the rotation axis of the impression cylinder is located. During the second print job, the web path is partially located below the horizontal area in which the rotation axis of the impression cylinder is located. During continuous production of the printing press, the invalid virtual axis is changed, for example accelerated or decelerated to a desired or preset angular velocity. It is characterized by the following.

[0019] Changed size Each improved form is: The first double printing device includes a first printing cylinder and a second printing cylinder, and the second double printing device includes a third printing cylinder and a fourth printing cylinder. The first printing cylinder and the third printing cylinder have a first circumferential size. The second printing cylinder and the fourth printing cylinder have a second circumferential size that is different from the first circumferential size. The circumference is determined by the circumference of the printing cylinder or by the circumference of a sleeve on the printing cylinder that carries one or more printed images. At least one flexographic printing plate is arranged around the circumference of each printing cylinder or sleeve. At least one flexographic printing plate is arranged transversely on each printing cylinder or sleeve. During a first print job, the first print cylinder and the third print cylinder rotate at a first angular velocity. The first angular velocity is given by the first perimeter size. During the first print job, the second and fourth printing cylinders are off-loaded from their respective impression cylinders. During a second print job, the second printing cylinder and the fourth printing cylinder rotate at a second angular velocity different from the first angular velocity. The second angular velocity is given by the second perimeter size. During the second print job, the first and third printing cylinders are relieved from their respective impression cylinders. During the first print job, the first and third print cylinders are each controlled using the same virtual size axis, or during the first print job, the first and fourth print cylinders are each controlled using the same virtual size axis. During the first print job, the first and third print cylinders are controlled relative to each other using one virtual size axis, or during the first print job, the first and fourth print cylinders are controlled relative to each other using one virtual size axis. During the second print job, the second print cylinder and the fourth print cylinder are each controlled using the same virtual size axis, or during the second print job, the second print cylinder and the third print cylinder are each controlled using the same virtual size axis. During the second print job, the second and fourth print cylinders are controlled relative to one another using one virtual size axis, or during the second print job, the second and third print cylinders are controlled relative to one another using one virtual size axis. During the first and second print jobs, the print cylinder is controlled using different virtual size axes. A first print job is performed by rotating a first printing cylinder, while a second print job is prepared by stopping the second printing cylinder, and at this time, impression cylinders corresponding to the first and second printing cylinders are coupled to a virtual web transport axis and rotate, and at a given time, for example at the end of the first print job, a change from the first print job to the second print job is made. It is characterized by the following.

[0020] Web Stripe Each improved form is: Printing is carried out in at least two parallel longitudinal stripes on at least one side of the web, where one longitudinal stripe may be located at AS and a second longitudinal stripe may be located at BS (AS: drive side; BS: operating side). Print jobs are printed in longitudinal stripes with different sizes. Print jobs are printed in longitudinal stripes with different longitudinal sizes. Print jobs are printed in longitudinal stripes with different horizontal sizes. It is characterized by the following.

[0021] Number of impression cylinders Each improved form is: At least one double printing unit with only one impression cylinder is provided and put into operation. At least one double printing unit with two impression cylinders is provided and put into operation. At least one dryer is provided and activated in the double printing device. It is characterized by the following.

[0022] Single Printing Device Each improved form is: At least one single printing device is prepared and activated. It is characterized by the following.

[0023] Drying Each improved form is: The web is dried. At least one dryer is disposed downstream of each double printing device in the web path and is activated to dry the web downstream of each double printing device. At least one dryer is arranged in the web path in each double printing unit, for example on the impression cylinder or between the two impression cylinders, and is activated so that the web is dried in each double printing unit. At least one dryer is arranged between the two impression cylinders in each double printing device in the web path and is activated to dry the web in each double printing device. The dryer is a hot air dryer. The dryer is a UV dryer. The dryer is an IR dryer. It is characterized by the following.

[0024] Tandem Structure Each improved form is: · Double printing devices are arranged in a horizontal row. The double printing unit is arranged so that the rotation axis of the impression cylinder is located in a horizontal area. The double printing unit is arranged so that the rotation axis of the impression cylinder is located in a horizontal plane. A horizontal plane is located at operating height above the production floor. Four or more inks are printed, and a correspondingly large number of double printing devices are operated. Varnishing is applied, for which purpose a varnishing unit is operated downstream of the double printing unit, which varnishing unit may be configured as an intaglio printing unit. In one so-called barrier device, one or more barrier layers are applied, for example as varnish layers, the barrier device being configured as a single-printing device or a double-printing device. It is characterized by the following.

[0025] Flying Modifications and Preparation Each improved form is: The first print job and the immediately following second print job are changed on the fly, allowing for uninterrupted production. In at least two double printing devices, one partial printing device is switched over to the other partial printing device, or vice versa. Switching is done according to the register, which prevents printing mistakes. The changeover is performed precisely in sections, so that the two print jobs or the corresponding print images are positioned on the web without significant gaps from each other in the longitudinal direction, thereby preventing print errors. The changeover is carried out in a manner that virtually eliminates waste. One partial printing device is prepared while the other partial printing device prints. At least one printing plate is changed during preparation. At least one sleeve is replaced with at least one printing plate during preparation. -The print image can be changed during preparation. - Size can be changed during preparation. - The size and length can be changed during preparation. - The size width can be changed during preparation. At least one printing ink is changed during preparation. The computer calculates a first virtual drive axis for the motor of the impression cylinder of the double printing unit, calculates a second virtual drive axis for the motor of the size cylinder of the first partial printing unit of the double printing unit for the first print job, and calculates a third virtual drive axis for the motor of the size cylinder of the second partial printing unit of the double printing unit for the immediately following second print job, and changes from the first print job to the second print job are made in a flying manner, changing from the second virtual drive axis to the third virtual drive axis. This solution is particularly advantageous for uninterrupted and precisely section-accurate switching between the partial printing units of the double printing unit, since production continues uninterrupted and printing errors are reduced or avoided, especially when the size is changed between both print jobs. The computer calculates a first virtual drive axis for the motor of the impression cylinder of the double printing unit, and the computer calculates a second virtual drive axis for the motor of the size cylinder of both partial printing units of the double printing unit for the first print job and the immediately following second print job, and the change from the first print job to the second print job is made in a flying manner, while the second virtual drive axis is maintained. This solution is particularly advantageous for uninterrupted and register-based section-accurate changeover between the partial printing units of the double printing unit, since production continues uninterrupted and printing waste is reduced or avoided, especially when the size is not changed between the two print jobs and cutting dies, such as rotary cutting machines or platen cutting machines, are provided downstream in the printing process in the subsequent processing. It is characterized by the following.

[0026] Subsequent Processing Each improved form is: A double printing unit is followed in the production direction by a subsequent processing station. The subsequent processing station comprises one sheet punching machine with one punching device or several sheet punching machines with one punching device each or at least one double sheet punching machine with two punching devices. When changing the print size, the die-cut size is adapted. The punching size can be adapted by changing the punching device. The die size can be adapted by changing the die on the fly. The subsequent processing station comprises at least one semi-rotary die-cutting machine. A punching cylinder having a circumferential length of L1 and a punching die having a length of L2 disposed on the punching cylinder, <L1である。 The punching cylinder of a semi-rotary punching machine is driven at an angular velocity that alternates between a relatively high speed and a relatively low speed, with the lower angular velocity being used during punching. The semi-rotary die-cutting machine is equipped with a web reservoir. The subsequent processing station includes at least one sheet cutter for cutting across the web to form a sheet. It is characterized by the following.

[0027] The present invention also makes it possible to change the mode of a double printing device, in this case changing from front printing to back printing (or vice versa) and / or changing the print size and / or changing the print size in the longitudinal stripes.

[0028] The technical features and feature combinations disclosed in the above technical fields, invention and improvement sections and the following example section may be combined with each other in any way to form further advantageous improvements of the present invention.

[0029] Alternative Solutions Alternatively to the present invention, a technical solution may be found in which instead of multiple virtual drive axes, only one virtual drive axis is used, which preferably controls the rotary drive / motor of the impression cylinder, from which the size cylinder is controlled via a so-called electronic transmission, i.e., using the respective high-precision conversion factors. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a diagram showing the configuration of two double printing devices. [Figure 2] FIG. 2 shows a configuration similar to that of FIG. 1. [Figure 3] FIG. 2 shows a configuration similar to that of FIG. 1. [Figure 4] FIG. 1 shows a flexographic printing press, a computer and a printing cylinder. [Figure 5] FIG. 1 shows a flexographic printing press. [Figure 6] FIG. 1 shows a flexographic printing press. [Figure 7] FIG. 1 shows a double printing device, a horizontal plane and a rotary drive. [Figure 8] FIG. 2 shows a double printing device and a rotary drive device. [Figure 9] FIG. 7 shows a printing machine similar to that of FIG. 6.

[0031] Examples and drawings for the invention The drawings illustrate preferred embodiments of the present invention and improvements, in which corresponding features are designated by the same reference numerals and some repetition of reference numerals has been omitted for clarity.

[0032] In the figure, NoD stands for a so-called "non-stop deck", i.e., a double printing apparatus without intermediate drying, in which one or the other partial printing apparatus prints. In addition, DoD stands for a so-called "double deck", i.e., a double printing apparatus with (optional) intermediate drying, in which one or the other partial printing apparatus prints (without intermediate drying) or both partial printing apparatuses print with intermediate drying.

[0033] FIG. 1 shows an arrangement of at least two double printing units 10; 11, 12 in a flexographic printing machine 1, which allows printing on one side 2a ("front") of a web 2 and the other side 2b ("back") of the web 2. To this end, the web path 4 first passes horizontally below the second double printing unit 12 (shown on the left in the figure) and then is guided upward and finally introduced into the double printing unit 12 from above. It can be seen that the two impression cylinders 20; 21, 22 of the illustrated double printing unit 10 rotate in opposite directions (as do the other cylinders of the partial printing units 13, 14 of the double printing unit 10). This arrangement advantageously eliminates the need for a reversing rod assembly with reversing rods arranged diagonally opposite each other. 1 also shows a computer 60, preferably a digital computer, such as an existing press computer or a separate control computer, that calculates and provides a virtual drive axis 61 to the printing press 1 or rotary drive 50. FIG. 1 also shows a portion of a web 2 having, in plan view, two longitudinal stripes 3 and a web movement direction 70.

[0034] Figure 2 shows a similar configuration to Figure 1, in which printing is first performed on the back surface 2b and then on the front surface 2a. Both configurations shown may be combined with each other (in one or another order).

[0035] A similar arrangement is shown in FIG. 3, in which one of the two double printing units 10 comprises two impression cylinders 20; 21, 22.

[0036] Figure 4 shows a web-handling flexographic printing press 1 (also called a printing plant, plant, or machine) with a side wall 53, a section printing unit A 13, a section printing unit B 14, a common impression cylinder GDZ 20, and at least one double printing unit 10 shown with two printing cylinders DZ 30 and two anilox cylinders RZ 40. Figure 4 also shows a computer 60, preferably a digital computer such as an existing printing press computer or a separate control computer, that calculates and provides a virtual drive axis 61 to the double printing unit 10 or the rotary drive 50. Figure 4 also shows a cross-section of an exemplary printing cylinder DZ 30 with an (axially slidable) sleeve 35 and at least one printing plate 36 (mounted on the sleeve). The GDZ cylinder 20 is supported on a bearing bed 55, the DZ cylinder 30 is supported on an adjustable bearing bed 54, and the cylinder 40 is supported on a further adjustable bearing bed 54. The adjustable bearing bed 54 is adjustable in direction 71 by means of a positioning drive 52. The DZ cylinder 30 is further adjustable in axial direction 72 by means of a positioning drive 51.

[0037] The drive units provided in the double printing unit 10, which includes both partial printing units A and B, are designated by the following nomenclature: (A) Rot_DZ: Rotation drive device 50 for the printing cylinder provided in the partial printing device A (A) Rot_RZ: Rotation drive device 50 for the anilox cylinder provided in the partial printing device A Rot_GDZ: Rotary drive for common impression cylinder 50 (A) Posi_Axial: Positioning drive device 51 for lateral register provided in partial printing device A (A) Posi_DZAS: Positioning drive device 52 on the drive side for the printing cylinder provided in the partial printing device A (A) Posi_DZBS: Positioning drive device 52 on the operating side for the printing cylinder provided in the partial printing device A (A) Posi_RZAS: Positioning drive device 52 on the drive side for the anilox cylinder provided in the partial printing device A (A) Posi_RZBS: Positioning drive device 52 on the operation side for the anilox cylinder provided in the partial printing device A The partial printing units B are provided with corresponding drives (B).

[0038] A first print job is executed in the section printing device A. At the same time, a second print job can be prepared in the section printing device B or section printing device B can be serviced, for example, a blade change can be performed on the doctor blade of the anilox roller 40. For production on the section printing device A, the drives Rot_GDZ, (A)Rot_DZ, and (A)Rot_RZ are activated. The drive (A)Posi_Axial compensates for lateral register variations, and the drive (A)Rot_DZ compensates for longitudinal register variations. During production, when speed changes occur, the positioning pairs (A)Posi_DZAS / (A)Posi_DZBS as well as (A)Posi_RZAS and (A)Posi_RZBS are moved, where the positioning pairs do not necessarily have to be operated in parallel.

[0039] At a defined time, the first job is finished. Then, to perform the second print job, the partial printing unit B is automatically brought into the printing position, whereby the second job is printed with the ink for the first print job of the entire printing installation. For this purpose, the drives (preferably servo drives) (B)Rot_DZ and (B)Rot_RZ are brought to a speed that matches the circumference of the flexographic print motif and is registered (as far as possible based on the identical circumference size of both print jobs) to match the first job or the die-cutter 44 (or sheet cutter). Once this speed is reached, the positioning motors (B)Posi_DZAS and (B)Posi_DSBS, as well as (B)Posi_RZAS and (B)Posi_RZBS, are brought to the optimal flexographic print position, thereby producing a high-quality flexographic print motif. In this case, the data for the pressure or print advance may come from an internal or external data carrier, i.e., a database, for example. Also, pressure or print feed data from an external scanner that determines the topography of the flexographic printing plate used may be used.

[0040] If necessary, the register sensor system is optionally moved axially by a motor, so that it directly enters the location of the printing marks, which may differ between the two jobs, detects the register marks, and adjusts them longitudinally and laterally (longitudinal and lateral register adjustment). This is time-clocked to minimize waste. In this case, data for the position of the register marks may come from an internal or external data carrier, i.e., a database, for example. However, data for the printing mark position from a scanner that recognizes the printing marks and provides their location axially and / or laterally, for example as XY coordinates, to the double printing device may also be used. These data may preferably be present in a cloud or a database. As soon as one or more register marks are recognized by the sensor, the longitudinal register is adjusted via the servo drive (B)Rot_DZ, and the lateral register is adjusted via the servo drive (B)Posi_Axial.

[0041] At the same time, the first job with the appropriate ink is ended in the partial printing unit A, and the positioning drives (A)Posi_RZAS / BS and (A)Posi_DZAS / BS move the printing cylinder away from the substrate and the anilox cylinder away from the printing cylinder. The printing cylinder (A)Rot_DZ is stopped, so that the printing sleeve can be safely replaced in the partial printing unit A, and the subsequent job (third job) can be prepared again. If necessary, it may be necessary to change the pattern on the anilox roller, and for this, the drive (A)Rot_RZ is reliably stopped. This all takes place while production in the partial printing unit B continues. If it is not necessary to change the pattern, for example by replacing the anilox roller or anilox sleeve, the drive (A)Rot_RZ continues to operate at a preset speed, thereby preventing the ink from drying out.

[0042] The second printing device (of the subsequent double printing device) then performs the same process exactly. That is, the second printing device performs the same steps, but at the exact location on the substrate web where the first printing device (of the first double printing device) performed them, thus reducing waste. In this case, the printing devices are synchronized as precisely as possible from the first job to the second job, so that no waste is generated in the optional downstream die-cutter (or sheet cutter). However, it is also possible to change to another printing plate, for example, from a 680 mm circumference to a 642 mm circumference, in a flying manner. For this purpose, at least two virtual drive axes are used in the printing press to handle two different printing sizes. This makes it possible to print two different printing sizes side by side in the machine at the same time.

[0043] Furthermore, during exchange via a motorized register sensor crossbeam, the register sensor can be moved axially, thereby differentiating the register marks between the first and second jobs, both in the direction of movement and perpendicular to the direction of movement. Information about where the register marks are located can come from a scanner that scans the location of the register marks (and preferably an identifying feature therein, such as a QR code or RFID chip) on the print sleeve. The information can be provided to a database or, for example, the cloud. Alternatively, the information can come from a pre-information database (e.g., cloud-based) or as a PDF. A QR code or another 2D code or RFID chip can be scanned or queried as an identifying feature, and the resulting ID can be used to retrieve corresponding data, for example, from a local or cloud-based database, and transmit it to the printing device for adjustment.

[0044] Each motorized register sensor crossbeam can be configured with a corresponding sensor system or camera for front and back printing within the printing device, generating information on where the register marks are located, as described in the previous paragraph.

[0045] In Figure 5 it is shown that a web-handling flexographic printing machine 1 (also called printing plant, plant or machine) comprises at least one double printing unit 10 shown with a section printing unit A; 13, a section printing unit B; 14 and two impression cylinders GDZ; 20, 21, 22.

[0046] In the partial printing device A, a first job is executed. At the same time, a second job can be prepared in the partial printing device B or maintenance can be performed on this printing device in the partial printing device B (for example, a blade change in the doctor blade). At a defined time, the first job is finished. The partial printing device B is then automatically brought into the printing position, whereby the second job is printed with the ink for the first printing. In practice, at the same time, the first job with the corresponding ink is finished in the partial printing device A.

[0047] The second printing device (of the subsequent double printing device) then performs the same step exactly. That is, the second printing device performs the same step, but at the exact location on the substrate web where the first printing device (of the first double printing device) performed it, thus reducing waste. In this case, the printing devices are synchronized as precisely as possible from the first job to the second job so that no waste is generated in the optional downstream die-cutter (or sheet cutter). However, it is also possible to change to a different printing plate, in which case the first printing device is preferably synchronized precisely with the second printing device.

[0048] The exchange is event-driven in terms of time, section, number, splicing, material exchange or button push, where the system can process jobs simultaneously and execute them sequentially.

[0049] If at least one intermediate dryer is used in a 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 zone (between the impression cylinders). Furthermore, as already explained with reference to FIG. 4, it is possible to print two different circumferences in a single double printing unit, preferably side-by-side. For example, partial printing unit A can print a 480 mm circumference on the web on the AS side (drive side of the machine), while partial printing unit B can print a 960 mm circumference on the BS side (work side of the machine) or prepare a 960 mm circumference. The impression cylinders of partial printing units A and / or B can be temperature-controlled, in particular cooled, so that each impression cylinder does not expand when heated.

[0050] 6 shows an industrial, web-handling flexographic printing machine 1 with a roll changer 45 for the web to be printed (from right to left, or in the production direction 70 shown by the arrow), a web inlet 46, six double printing units 10, each with a dryer 43 arranged above it, and a winder 47 for the printed and dried web 2. The machine 1 also includes a computer 60, e.g., a control computer. As an alternative to the illustrated configuration, the production direction 70 can run in the opposite direction (i.e., from left to right as viewed in the drawing), in which case the winding units 45, 47 are swapped with respect to their functions (unwinding and winding).

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

[0052] FIG. 8 shows a double printing apparatus 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 dumped separately from each impression cylinder 20, and the anilox rollers 40 can also be dumped from the printing cylinders 30. At least one (hot air) dryer 43 is located in the superstructure of the double printing apparatus 10. Such double printing apparatuses 10 can be arranged in a horizontal row 84. FIG. 8 also shows six rotational drives 50 (electric motors) for the separately driven cylinders / rollers 20, 30, 40, controlled by a computer 60 using virtual drive axes 61. It is also possible to drive both impression cylinders 20 of the double printing apparatus 10 using a common drive 50, preferably an electric motor, for example via a transmission and / or belt.

[0053] Figure 9 shows a printing press 1 similar to Figure 6, but in this case, in the configuration shown, the printing press 1 preferably has an additional single printing unit 15 downstream of the existing double printing unit 10 in the production direction 70. This single printing unit 15 may be used for varnishing, for example as a flexographic or intaglio printing unit. Additionally or alternatively, a double intaglio printing unit may also be present.

[0054] The illustrated double printing apparatus allows for six exemplary modes of operation:

[0055] 1) Flexographic printing machines for front / reverse printing with selectable web path and reversible rotation of the rotating cylinder. In this case, the front and back can be printed in exact register with each other, but it is also possible to print on the front and back with different print sizes. For example, if the front is 490 mm and the back is 980 mm, the inks can be printed and adjusted in register with each other on the front and back, or printed in register with each other at 490 mm and 680 mm.

[0056] When going from front to back printing, the following axes change rotation direction: (A)Rot_RZ, (B)Rot_RZ, (A)Rot_DZ, (B)Rot_DZ, (A)Rot_GDZ in DoD devices, (B)Rot_GDZ in DoD devices, Rot_GDZ in NoD devices, Rot_KUW (if present, requires rotational drive of driven cooling roller and change of rotation direction) and Rot_LW (if present, requires rotational drive of driven guide roller and change of rotation direction).

[0057] 2) Register-accurate job change between two jobs, where the change is made register-accurately on a die-cutting machine (rotary die-cutting machine, platen die-cutting machine, semi-rotary die-cutting machine, or sheet cutter) while the package size remains unchanged, for example, a 1-liter orange juice package is changed in a flying manner to a 1-liter grape juice package, which is then registered register-accurately on the die-cutting machine or sheet cutter. In this case, the die-cutting machine or sheet cutter is preferably located at the end of the printing installation. During a job change, the web traversal by the sheet cutter can advantageously be changed register-accurately to suit the new job.

[0058] 3) Register-accurate job change between two jobs, where the change is made by changing the package size in a register-accurate die-cutter (rotary die-cutter, platen die-cutter, semi-rotary die-cutter or sheet cutter), for example, changing a 1 liter orange juice package to a 0.75 liter grape juice package in a flying manner, and the die-cutter brings the cutting dies into the process register-accurately and section-accurately at the time of the change, or the sheet cutter adapts its cutting length register-accurately and section-accurately, with only little waste and the production speed, for example 400 m / min, remaining unchanged before, during and after the change. In this case, the die-cutter or sheet cutter is preferably located at the end of the printing installation.

[0059] 4) A register sensor adjusts at least one or both inks of the double printing device when printing on the front side. A register sensor adjusts at least one or both inks of the double printing device when printing on the back side.

[0060] 5) The double printing device acquires printing adjustment data from an external scanner for flexographic printing plates and adjusts pressure or printing feed using the drive devices (A) Posi_DZAS, (B) Posi_DZAS, (A) Posi_RZAS, (B) Posi_RZBS, (A) Posi_Axial, (B) Posi_Axial.

[0061] 6) Two sizes can be printed in register. At least two virtual size axes allow at least two print sizes, i.e., cylinder circumferences, to be printed and prepared in the machine in register, or at least two print circumferences to be printed simultaneously and in register, side by side. For example, circumferences of 680 mm and 480 mm, or integer multiples thereof. Also, multiple print jobs, e.g., three or four, with different circumferences can be printed, i.e., four packaging sizes can be printed side by side. [Explanation of symbols]

[0062] 1. Printing machines 2. Web 2a One side of the web 2b The other side of the web 3 Longitudinal stripes on the web 4 Web Paths 4a Web path segment (in a double printing unit between two impression cylinders) 10 Double printing device 11 First double printing device 12 Second double printing device 13 First partial printing device 14 Second partial printing device 15 Single Printing Device 20 impression cylinder 21 First impression cylinder 22 Second impression cylinder 23 Rotation axis of impression cylinder 30 Printing cylinder 31 First printing cylinder 32 Second printing cylinder 33 Third printing cylinder 34 Fourth printing cylinder 35 sleeve 36 Print Edition 37 First circumference size 38 Second Circumference Size 40 Anilox Roller 41 Web tension roller 42 Cooling roller 43 Dryer 44 Die-cutting machine or sheet cutter 45 Roll Changer 46 Web retraction device 47 Winder 50 Drives, especially rotary drives 51 Drives, especially positioning drives 52 Drives, especially positioning drives 53 Side wall 54 Adjustable bearing bed 55 bearing bed 60 Computer 61 Virtual Drive Axis 62 Virtual web transport axis 63 Virtual Size Axis 70 Production Direction 71 Circumferential / Longitudinal 72 Horizontal 73 First rotation direction 74 Second Rotation Direction 80 Production Floor 81 Operating height 82 horizontal area 83 horizontal plane 84 A horizontal row of printing devices, especially double printing devices

Claims

1. A method for operating a printing press for flexographic printing, comprising unwinding, transporting and, during transport, guiding a web (2) of substrate through at least two double printing units (10) of said printing press (1), said double printing units (10) each comprising at least one impression cylinder (20) and two printing cylinders (30) for said flexographic printing, a computer (60) of the printing press (1) calculating at least two virtual drive axes (61), and controlling each of the motors (50) by using one of the virtual drive axes (61).

2. 2. The method of claim 1, wherein the motors (50) of the impression cylinders (20) are controlled using a common imaginary web transport axis (62).

3. 3. The method according to claim 2, characterized in that the motors (50) of the printing cylinders (30) are controlled using separate virtual size axes (63), or the motors (50) of the printing cylinders (30) of each partial printing device (13, 14) of the double printing device (10) are controlled using two virtual size axes (63), or the motors (50) of the printing cylinders (30) are controlled using one common virtual size axis (63).

4. 4. The method of claim 3, wherein the control is performed at a predetermined web angular velocity using said common virtual web transport axis (62).

5. 5. The method of claim 4, wherein each control is performed at a respective predetermined size angular velocity using a respective one of said virtual size axes (63).

6. 6. The method of claim 5, wherein the web angular velocity and at least one of the size angular velocities are matched when printing a print job.

7. 6. The method of claim 5, wherein when printing another print job, the web angular velocity and at least one of the size angular velocities differ by a factor not equal to one.

8. 6. The method of claim 5, wherein when printing another print job, the web angular velocity and at least one of the size angular velocities differ by a factor of -1.

9. 9. The method according to claim 1, wherein during the first and second printing jobs, printing is performed on opposite sides (2a, 2b) of the web (2) by at least two or all of the double printing devices (10).

10. 10. The method according to claim 9, characterized in that when changing the first print job to the second print job, the web path (4) is changed from the first double printing device (11) to the second double printing device (12).

11. 11. The method according to claim 10, characterized in that during the first printing job, the web path (4) is located substantially above a horizontal area (82) in which the rotation axis (23) of the impression cylinder (20) is located.

12. 12. The method according to claim 11, characterized in that during the second printing job, the web path (4) is partially located below a horizontal area (82) in which the rotation axis (23) of the impression cylinder (20) is located.

13. 13. The method according to claim 1, wherein during the first printing job, the first printing cylinder (31) of the first double printing unit (11) and the third printing cylinder (33) of the second double printing unit (12) are each controlled using the same imaginary size axis (63), or during the first printing job, the first printing cylinder (31) of the first double printing unit (11) and the fourth printing cylinder (34) of the second double printing unit (12) are each controlled using the same imaginary size axis (63).

14. 14. The method according to claim 13, wherein during the second printing job, the second printing cylinder (32) of the first double printing unit (11) and the fourth printing cylinder (34) of the second double printing unit (12) are each controlled using the same imaginary size axis (63), or during the second printing job, the second printing cylinder (32) of the first double printing unit (11) and the third printing cylinder (33) of the second double printing unit (12) are each controlled using the same imaginary size axis (63).

15. 15. The method of claim 14, wherein the printing cylinder (30) is controlled using different virtual size axes (63) during the first and second print jobs.

16. 16. A method according to any one of claims 1 to 15, characterized in that the printing is carried out in at least two parallel longitudinal stripes (3) on at least one face (2a, 2b) of the web (2).

17. 17. Method according to claim 16, characterized in that the print jobs are printed in the longitudinal stripes (3) with different sizes.

18. 18. The method according to claim 1, wherein at least one dryer (43) is arranged in the web path (4) between the two impression cylinders (20) in each double printing device (10) and is activated to dry the web (2) in each double printing device (10).

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

20. 20. The method according to claim 19, characterized in that the double printing device (10) is arranged so that the rotation axis (23) of the impression cylinder (20) is located in a horizontal area (82).

21. 21. The method according to claim 1, wherein a first print job and a second print job that immediately follows are changed on the fly.

22. 22. The method according to claim 21, characterized in that in at least two double printing devices (10), one partial printing device (13) is switched to the other partial printing device (14) or, conversely, the other partial printing device (14) is switched to one partial printing device (13).

23. 23. The method of claim 22, wherein the switching is performed in accordance with a register.

24. 24. The method according to claim 22 or 23, characterized in that the switching is performed section-accurately.

25. 25. Method according to any one of claims 22 to 24, characterized in that the size is changed.

26. 26. The method according to claim 22, further comprising changing at least one printing ink.

27. 27. The method according to claim 1, further comprising calculating, by the computer, a first virtual drive axis for the motor of the impression cylinder of the double printing apparatus, a second virtual drive axis for the motor of the size cylinder of the first partial printing apparatus of the double printing apparatus for a first print job, and a third virtual drive axis for the motor of the size cylinder of the second partial printing apparatus of the double printing apparatus for a second print job that immediately follows, and changing from the first print job to the second print job in a flying manner, and changing from the second virtual drive axis to the third virtual drive axis.

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