Method for operating a web-fed printing press

Abstract

A method according to the invention for operating a web-fed printing press comprising a roll changer (10) and a plurality of printing units (20), wherein a flying web change from a first web (13) to a second web (15) takes place with the creation of a splice (17), and wherein settings are made on the printing units (20) in accordance with the passage of the splice (17) through the web-fed printing press (1), is characterized in that at least two printing units (20) are designed as double-sided printing units (20) for flexographic printing, and in that switching is carried out from a first partial printing unit (21) to a second partial printing unit (22) of the respective double-sided printing unit (20) in accordance with the passage of the splice (17) through the web-fed printing press (1). The invention advantageously makes it possible to operate a flexographic printing press non-stop and in an automated manner during a web change.The invention is advantageously used in the operation of a web-processing rotary printing press for flexographic printing; it increases its degree of automation, productivity, and print quality.

Description

Invention: InventionThe invention relates to a method for operating a web-fed printing press having the features of the preamble of claim 1.Field of TechnologyThe invention is in the technical field of the graphic industry and there in particular in the field of the operation of a flexographic printing machine, i.e. a rotary printing press for printing with flexographic printing plates on web-shaped printing material. In particular, the invention is in the sub-field of controlling or regulating the machine or its drives and / or actuating drives for increasing the print quality and productivity and / or avoiding or reducing faultsJP2006321213A discloses an offset web printing machine having a web changer and a plurality of printing units. If a web roll is almost used up, a change is made over to a new web roll with essentially the same web material, i.e. with a material still matching the existing print job, or both webs are connected to one another at an adhesive location ("splice"). During such a change of web, register changes can occur as a result of the production and the machine pass of the adhesive bonding location and therefore a necessary adaptation of the register settings of the printing units takes place. This adaptation appears to be made in a manner coordinated with the passage of the adhesive location through the web-fed printing press. It is not disclosed here that simultaneously with the web change, a print image change also takes place, that the two webs differ substantially (i.e. for example in web thickness, web width or web material) or that printing cylinders or offset cylinders are shut down when performing the register adjustments. It seems that only the longitudinal register but not the transverse register is addressed. Register sensors are mentioned, but not their measurement positions. When performing the register adjustments, a database can be accessed.A web-processing flexographic printing press with dual printing units is known, for example, from DE102017222700A1 or DE102021126115A1.During the permanent operation of a flexographic printing press (high-product non-stop operation), a web change can occur, the two webs differing substantially in at least one web parameter, in particular in the web thickness. This can be effected, for example, during a change of order. Printing operators require that such a change should not disrupt production, reduce print quality, and produce little or no waste. Printing operators also require further automation of the printing machines in order to save personnel costs or to be able to replace missing persons.Technical TaskIt is therefore an object of the present invention to provide an improvement over the prior art which makes it possible in particular to operate a flexographic printing machine non-stop and in an automated manner during web change.Solution of the Invention to the ProblemThis object is achieved according to the invention by a method according to claim 1.Advantageous and therefore preferred developments of the invention are evident from the dependent claims and from the description and the drawings.A method according to the invention for operating a web-fed printing press, which comprises a web changer and a plurality of printing units, wherein a flying web change from a first web to a second web takes place while producing an adhesive location, and wherein settings are carried out at the printing units in a manner matched to the passage of the adhesive location through the web-fed printing press, is distinguished in that at least two printing units are designed as double printing units for flexographic printing and in that, in a manner matched to the passage of the adhesive location through the web-fed printing press, a switch is made from a first partial printing unit to a second partial printing unit of the respective double printing unit.Advantageous Embodiments and Effects of the InventionThe invention advantageously makes it possible to operate a flexographic printing machine non-stop and automatically during web change.The invention is advantageously used for operating a web-processing rotary printing press for flexographic printing; it increases its degree of automation, productivity and print quality.The invention advantageously avoids production interruptions and thus reduces production costs. The invention advantageously reduces or avoids maculatur and thus also reduces production costs. The invention advantageously improves the print quality, for example by rapidly and optimally adjusting the pressing (printing cylinder to impression cylinder), whereby particularly squeezing edges can be avoided during flexographic printing. The invention allows fewer personnel or less trained personnel to be used and thereby further reduces production costs.The invention can be used in particular in the case of the so-called flying job change, for example from a first print job for a first product (first print image, first web material, first web thickness) to a second print job for a second product different therefrom (second print image, second web material, second web thickness). The products can preferably be packages.According to the invention, "switched over from a first partial printing unit to a second partial printing unit of the respective dual printing unit" is made "in a manner coordinated with the passage of the adhesive location through the web-fed printing press. Since the adhesive station passes through the double-printing units of the printing press successively in time, the changeover is effected successively for the double-printing unit, i.e. not simultaneously at all printing units, but with a time offset corresponding to the respective web running time from the double-printing unit to the double-printing unit. In this case, all double-printing units are preferably ultimately switched over.The changeover in the double printing unit is preferably effected temporally close to the point in time at which the adhesive point passes the printing nip between the printing cylinder and the impression cylinder. In this way, maculatur can be saved in an optimum manner. In the best case, the changeover takes place as soon as the adhesive bonding point passes the printing nip. The switching over accordingly takes place in synchronization with the movement of the adhesive location through the web-fed printing press. It would be desirable to have a changeover which takes place very close in time to the passage of the adhesive bonding point through the double printing unit and in particular through the printing nip formed there. However, the location of the adhesive location that varies over time must be known for this purpose, for which purpose a corresponding sensor and a computer are preferably used. Since the speed of the web transport in industrial web-fed printing presses is extremely high, it is therefore advantageous to arrange the sensor at a corresponding spatial distance in front of the printing unit / in front of the printing nip, in order to be able to trigger a corresponding reaction in good time for the changeover process.The invention can be extended to machines or aggregates of the further processing, for example for punching, folding, gluing or also for palletizing. Such machines or units can be automatically switched over when the printing material is changed: settings for punching and / or folding can be adapted depending on the printing material, for example.Instead of flexographic printing, the invention can also be used accordingly, for example, in gravure printing.Developments of the InventionPreferred refinements of the invention (briefly: refinements) are described below. Where they are not technically ruled out, they can also be combined with one another.A further development can be characterized in that the second partial printing units or their respective flexographic printing cylinders are set on the second web at a speed matched to the speed of the second web during the changeover. A further development can be distinguished in that the second partial printing units or their respective flexographic printing cylinders are set on the second web during the changeover with a press which is matched to the second web or its web parameters. A further development can be characterized in that the pressing on both lateral sides of the second partial pressing mechanism is set separately. For this purpose, the thickness of the web can be measured at a plurality of locations (in a direction lateral to the transport direction of the web). A further development can be distinguished in that, during the changeover, screen cylinders of the second partial printing units are set to the flexographic printing cylinders with a press which is matched to the second web or to its web parameters. A further development can be distinguished in that the second partial printing units or their respective flexographic printing cylinders are set on the second web during the changeover with a preregister adapted to the second web or its web parameters. A development can be characterized in that the preregister comprises the longitudinal register and the transverse register. The positioning-as well as the opposite positioning-can preferably be effected with servomotors.A further development can be characterized in that the output of dryers is adapted to the second web or its web parameters during the changeover. The dryers can be dryers on the web path between the dual printing units and / or between the partial printing units.A development can be distinguished in that a print job change takes place during the changeover. A development can be distinguished in that a print image change is carried out during the print job change.A further development can be characterized in that the flexographic printing cylinders of the first partial printing units are set down in a manner matched to the passage of the adhesive location through the web-fed printing press. A further development can be distinguished in that the flexographic printing cylinders of the first partial printing units are set down directly upstream of the adhesive location. A further development can be characterized in that the flexographic printing cylinders of the second partial printing units are adjusted in a manner coordinated with the passage of the adhesive location through the web-fed printing press. A further development can be distinguished in that the flexographic printing cylinders of the second partial printing units are set directly after the adhesive location.A further development can be characterized in that the dual-printing units each comprise a register sensor and that the register sensors are changed in their respective measurement position in a manner coordinated with the passage of the adhesive location through the web-fed printing press. A further development can be characterized in that the register sensors are moved transversely to the transport direction of the webs. A further development can be characterized in that the dual-print engines are each operated with a register algorithm and at least one register parameter, and in that the register algorithm and / or the register parameters are changed in a manner matched to the passage of the adhesive bonding point through the web-fed printing press.A further development can be characterized in that the first path and the second path differ substantially in at least one path parameter. A further development can be characterized in that the web parameter is one of the following parameters: web thickness, web width, web material, web surface. The web surface differs substantially, for example, if the material is recycled and / or coated on one / two sides and / or calendered and / or drawn and / or extruded. The roughness of the web surfaces of two webs can also vary. The material / surface parameters present for a material to be processed can be measured: by reflection or IR spectroscopy or using ultrasound or laser light. The measurement / measurements take place / take place preferably before the printing couple, particularly preferably shortly before the printing couple (few maculatur!). The measurement, in particular of the web thickness, is preferably carried out continuously. The web thickness can preferably be measured using an optical measurement system. Alternatively, the required parameters may be loaded from a database. Further alternatively, the required parameters can be stored on the web (e.g. QR code) or on the web roll (e.g. QR code or NFC chip) and can be read out, preferably in the roll changer. A further development can be characterized in that the web thickness is determined by sensor. A development can be characterized in that the path parameters are stored and provided in a digital database.A further development can be characterized in that the second web is connected to the first web at the adhesive location.A further development can be characterized in that during the passage of the adhesive bonding point through the web-fed printing press, at least one first partial printing unit is set for a first print job and contributes to the first print job on the first web, and in that at least one second partial printing unit is set for a second print job and contributes to the second print job on the second web.A further development can be characterized in that the web tension is adjusted upstream of the double printing units and / or downstream of the double printing units, in particular in that the feed web tension is adjusted.A further development can be characterized in that at least one individual printing unit is provided in addition to the double printing units.A further development can be distinguished in that instead of the dual printing units for flexography, dual printing units for gravure printing with gravure cylinders are used.The features and combinations of features disclosed in the above sections, technical field, invention and developments and in the following section, exemplary embodiments, represent further advantageous developments of the invention-in any combination with one another.Example 1: Specific ApplicationA package A with a circumference 567 mm ("six-pack") is printed in the printing machine. The corresponding web W A has a thickness / thickness of 300 μm and is located as a roll R A on a winding spindle W A. A roll R B is placed in the free part of the nonstop winder, this roll having, for example, a thickness / thickness of 250 μm. Print job package B with circumference 678 mm ("mint tea") is prepared in the machine as it continues to produce package A. The job A is finished when the roll R A is wound on the winding spindle W A. The winding spindle W B is in each case brought to machine speed and "spliced in", that is to say the web of material B B is adhesively bonded to the running web B A. The two material webs thus have a different thickness and optionally also a different modulus of elasticity. As soon as the new web B B enters the machine, certain machine parameters are adapted, namely in such a way that as little waste as possible is produced. Next, the print job B, i.e., the respective print cylinders, are brought into register with each other at speed in the machine. The print adjustment of the print job B then takes place exactly suitably at the location where the new web of material B passes B with the respective printing unit. The print setting, i.e., e.g., the pressing, is set such that it matches the new print substrate with a changed thickness. This is effected first in the front part of the printing press, where the material is just moving in and print job B is being printed. In the rear part of the printing press, where print job A is still running, the value 300 μm is used further for the print settings in order not to produce any waste there. The changeover takes place while the printing press continues to produce. Accordingly, there are simultaneously two different material webs B A and B B with different properties in the machine and the printing machine "manages" the two material webs and the two associated print jobs A and B with different package sizes / package designs. With a continuous time, the material change (adhesive location) moves towards the end of the printing press. At a certain point in time, the changeover operation is complete and only print job B is produced and only web B B is still present in the machine.Example 2: Concrete Setting ChangesThe following specifications and adaptations can be changed individually or in groups or all together during the passage of the adhesive bonding point:The method according to the invention is based on the following features: web thickness, web width, web material, web modulus, web tension, pressing between printing and counter-cylinders and / or between raster and printing cylinders, printed image, printing format, preregister (register presetting), locations of the register marks on the web (axial and in the circumferential direction), measurement locations of the register regulator sensors (axial and in the circumferential direction).Embodiments of the Invention and FiguresThe figures show preferred exemplary embodiments of the invention and of the developments. Features corresponding to one another are provided with the same reference numerals in the figures. Repeating reference numerals in the figures have been partially omitted for clarity. FIG. 1 shows a schematic illustration of a sectional view of a web-fed printing press when carrying out a preferred exemplary embodiment of the method according to the invention. FIG. 2 is a schematic illustration of a sectional view of a roll changer involved in carrying out a preferred embodiment of the method according to the invention. FIGS. 3, 4 and 5 each show a schematic representation of a sectional view of a double printing unit, involved in carrying out a preferred exemplary embodiment of the method according to the invention.FIG. 1 shows a web-fed printing press 1, in particular for flexographic or intaglio printing, for printing a web 2 of printing material, in particular a web of paper or board, which is conveyed through the machine 1 in a transport direction 4 via a number of guide rollers 3. The control of the web-fed printing press 1 is preferably effected via a computer 55.The web-fed printing press 1 comprises a reel changer 10 (cf. FIG. 2 ) for the flying reel change with two unwinders 11 for unwinding a first reel 12 or a first web 13 and for unwinding a second reel 14 or a different, second web 15. The reel changer 10 furthermore comprises a so-called spider device 16 for connecting the first web 13 to the second web 15 via a common adhesive point 17 between the two webs 13 and 15. Alternatively, it can be provided that the web 13 or 15 wound on a reel 12 or 13 and stored already has one or more adhesive points 17, i.e. that at least two different webs are wound on the reel and can be unwound. The reel changer 10 also comprises a number of guide rollers 3 which define the path of the web 2 or its transport direction 4. Arranged downstream of the reel changer 10 is an infeed unit 18, which serves, for example, to control the web tension.The web-fed printing press 1 comprises at least one printing unit 20 (cf. FIGS. 3, 4 and 5 ), but preferably a plurality of printing units 20 for the production of multi-color printing. The printing unit 20 is designed as a dual printing unit 20, i.e. it comprises a first partial printing unit 21 and a second partial printing unit 22. The first partial printing unit 21 comprises a first printing cylinder 30, in particular a flexographic or gravure cylinder, and preferably a first screen cylinder 34 for printing a first printed image 31 on the web 2; the second partial printing unit 22 comprises a second printing cylinder 32, in particular a flexographic or gravure cylinder, and preferably a second screen cylinder 35 for printing a second printed image 33 on the web 2. the double printing unit 20 is designed for the flying job change, i.e. preferably either the first partial printing unit 21 prints the first printed image 31 or the second partial printing unit 22 prints the second printed image 33, wherein (cf. FIGS. 3 and 4 ) one of the two printing cylinders 30 or 32 is placed against a central impression cylinder 36 and the other printing cylinder is placed off the latter. Alternatively, (see FIG. 5 ) two impression cylinders 36 and 37 can be provided. During the flying job change, a changeover is made between the two partial printing units 21 and 22, for which purpose each partial printing unit 21 and 22 is equipped with a stopping device 38. The non-printing partial printing unit 21 or 22 can be set up for a new print job during production, i.e. can be provided with at least one new printing form.FIGS. 3, 4 and 5 each show a dual printing unit 20 to which a web 2 is fed in a transport direction 4 and from which the web 2 is fed in a transport direction 4 to a further unit. Above the double printing unit 20, a superstructure is provided with a number of guide rollers 3 for the web 2 and a dryer 53 for the printed web 2. The double printing units 20 shown each comprise a first partial printing unit 21 and a second partial printing unit 22, as already described above.At least upstream of a first dual printing unit 20 of the web-fed printing press 1 (optionally upstream of each dual printing unit 20, cf. FIG. 1 ), a sensor 40 is arranged. The sensor 40 can be, for example, a web thickness sensor 40 for determining the thickness of the incoming web 2 and / or for detecting a glue joint 17. The web-fed printing press 1 and / or the dual-printing press 20 comprises / comprise the computer 55, which is connected-preferably via a connection 56-to the sensor 40. The sensor 40 transmits its measured values preferably continuously to the computer 55, and the computer 55 thereupon sends-after appropriate calculations-control signals 57 (cf. FIG. 1 ) to the dual printing unit 20 or to the plurality of dual printing units 20. In this way, it can be ensured that the changeover takes place in a manner coordinated with the passage of the adhesive location 17 through the web-fed printing press 1 or its double-fed printing units 20. When switching between the two partial printing units 21 and 22, the pressing of the printing cylinder 32 on its impression cylinder 36 or 37 can preferably be preset. This preadjustment can be selected depending on the web thickness of the web 15 following the adhesive location 17. Likewise, the pressing of the grid cylinder 34 on the printing cylinder 30 during the web change can be preset as a function of the passage of the adhesive location 17.The double printing units 20 further preferably each comprise a register sensor 41 which is arranged in a variable manner in its measuring position 42; preferably, the register sensor 41 can be displaced transversely to the transport direction of the web 2. During a change of web, the register sensor 41 can therefore be changed in its measuring position 42 as soon as the glue spot has passed the register sensor. The control signals 57 or corresponding control signals can also be used for this switching process. During the passage of the glue spot 17 and during the switching over synchronized therewith, register presetting can also take place.FIG. 5 also shows that intermediate dryers 54 can be arranged on the web course of the web 2 between the two impression cylinders 36 and 37. These intermediate dryers 54 and / or the dryers 53 of the web-fed printing press 1 can likewise be controlled by the computer 55 during a web change and the drying parameters can be changed from the first web 13 to the second web 15. This change also takes place in an advantageous manner at the time at which the adhesive point 17 passes the respective dryer.In addition to the dual-printing unit 20, the web-fed printing press 1 shown in FIG. 1 optionally also comprises at least one individual printing unit 50, in particular for flexographic printing or gravure printing. This individual printing unit 50 can also be set on and off and can be controlled in this respect by the computer 55.Furthermore, the web-fed printing press 1 comprises a further unit 51, which can preferably be designed as a winder 51 for the printed web 2. The web-fed printing press 1 can comprise, in addition to the work 51 or alternatively, a further work 52, which can preferably be designed as a further processing work 52, for example a punching work 52. The further processing unit 52 can also be controlled by the computer 55 with regard to a changeover process in the event of a change of web.The figures show, by way of example, the switching from a first path 13 to a second path 15. It is clear that a switching from the second belt 15 to the first path 13 can also take place and that a multiple switching to paths 13, 15 to be processed one after the other can take place.List of reference characters1 Web printing press 2 Web 3 Guide rollers 4 Transport direction 10 Web changer 11 Winder 12 First roller 13 First web 14 Second roller 15 Second web 16 Splicing device 17 Adhesion point 18 Draw-in unit 20 Printing couple / e, in particular dual printing couple / e for flexographic printing 21 First partial printing couple, in particular flexographic printing couple 22 Second partial printing couple, in particular flexographic printing couple 30 First printing cylinder, in particular flexographic printing cylinder 31 First printed image 32 Second printing cylinder, in particular flexographic printing cylinder 33 Second printed image 34 First engraved cylinder 35 Second engraved cylinder 36 (central) impression cylinder 37 Further impression cylinder 38 Take-off device 40 Sensor, in particular web thickness sensor 41 Register sensor 42 Measurement position 50 Single printing couple for flexographic printing 51 Further work, In particular, winders 52 optional further processing units 53 dryers 54 intermediate dryers 55 computers 56 connections / connections 57 control signalsReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2006321213A

[0003] DE 10201722700A1

[0004] DE 102021126115A1

[0004]

Claims

Method for operating a web-fed printing press, which comprises a web changer (10) and a plurality of printing units (20), wherein a flying web change from a first web (13) to a second web (15) takes place with the production of an adhesive location (17), and wherein settings are carried out at the printing units (20) in a manner matched to the passage of the adhesive location (17) through the web-fed printing press (1), characterized in that at least two printing units (20) are designed as double printing units (20) for flexographic printing, and in that a switch is made from a first partial printing unit (21) to a second partial printing unit (22) of the respective double printing unit (20) in a manner matched to the passage of the adhesive location (17) through the web-fed printing press (1).Method according to Claim 1, characterized in that the second partial printing units (22) or their respective flexographic printing cylinders (32) are set on the second web (15) during the changeover at a speed matched to the speed of the second web (15).Method according to one of the preceding claims, characterized in that the second partial printing units (22) or their respective flexographic printing cylinders (32) are set on switching over to the second web (15) with a press adapted to the second web (15) or its web parameters.Method according to one of the preceding claims, characterized in that, during the changeover, screen cylinders (35) of the second partial printing units (22) are set on the flexographic printing cylinders (32) with a press which is matched to the second web (15) or its web parameters.Method according to one of the preceding claims, characterized in that the second partial printing units (22) or their respective flexographic printing cylinders (32) are set on the second web (15) during the changeover with a preregister adapted to the second web (15) or its web parameters.Method according to one of the preceding claims, characterized in that the power of dryers (53) is adapted to the second web (15) or its web parameters during the changeover.Method according to one of the preceding claims, characterized in that a print job change takes place during the changeover.Method according to one of the preceding claims, characterized in that the flexographic printing cylinders (30) of the first partial printing units (21) are set down in a manner matched to the passage of the adhesive point (17) through the web-fed printing press (1).Method according to Claim 8, characterized in that the flexographic printing cylinders (30) of the first partial printing units (21) are set down directly upstream of the adhesive location (17).Method according to one of the preceding claims, characterized in that the flexographic printing cylinders (30) of the second partial printing units (21) are set at a position matched to the passage of the adhesive point (17) through the web-fed printing press (1).Method according to Claim 10, characterized in that the flexographic printing cylinders (30) of the second partial printing units (21) are set directly after the adhesive point (17).Method according to one of the preceding claims, characterized in that the dual-printing units (20) each comprise a register sensor (41), and in that the register sensors (41) are changed in their respective measurement position (42) in a manner matched to the passage of the adhesive location (17) through the web-fed printing press (1).Method according to one of the preceding claims, characterized in that the first path (13) and the second path (15) differ substantially in at least one path parameter.Method according to claim 13, characterised in that the web parameter is one of the following parameters: web thickness, web width, web material, web surface.Method according to one of the preceding claims, characterized in that during the passage of the adhesive bonding point (17) through the web-fed printing press (1), at least one first partial printing unit (21) is set for a first print job and contributes to the first print job on the first web (13), and in that at least one second partial printing unit (22) is set for a second print job and contributes to the second print job on the second web (15).Method according to one of the preceding claims, characterized in that instead of the dual printing units (20) for flexography, dual printing units (20) for gravure printing with gravure cylinders (30, 32) are used.

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