Method for producing proofs in a web-processing printing press - Patent Application 20070122997

Abstract

To create a proof print in a web-processing printing press.SOLUTION: A method for printing a print job (50) and a subsequent print job (51) and for producing a proof print (52) for the subsequent print job (51) by means of a printing press is characterized in that a preferably flying web change from a first web (3a) to a second web (3b) is carried out, and the proof print (52) is produced on an end section (54) of the first web (3a), preferably in front of a joint (4) between the two webs (3a, 3b), or on an edge section (62) of the first web (3a) or of the second web (3b). The invention advantageously makes it possible to produce a proof, thereby making it possible to reduce spoilage, and to provide the proof print for inspection in a simple manner. The invention is used, for example, in rotary printing presses for industrial packaging printing.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for producing proofs in a web-processing printing press having the features of the preamble of claim 1 .

[0002] The invention is located in the technical field of the graphics industry, in particular in the field of operation of printing machines, preferably rotary printing machines for printing on web-like substrates, in particular in the area of ​​producing and checking so-called proofs in order to improve print quality.

[0003] Background technology It is already known to have printing presses for changing jobs on the fly, it is further known to produce proofs, and finally it is known to use misprints during on-press proofing.

[0004] DE 10 2017 222 700 A1 discloses a printing machine for web processing, for example used in flexographic printing, with a switchable twin printing unit (so-called "Double Ink Decks" or DID), which allows job changes on the fly, in which case the printing units of the twin printing unit are operated alternately.

[0005] DE 10 2014 220 361 A1 discloses a method for color control in which a proof print (a trial print before the actual printing process or a print to be checked for defects) is made and detected by a color measuring device.

[0006] When a proof is produced, the printing press is stopped to allow access to the proof for inspection, which results in lost production and higher production costs.

[0007] EP 3921164 discloses a method for adjusting color profiles in a sheet offset printing press, which uses pre-printed waste sheets and unprinted OK sheets during changeover after a job change or on-press proofing.

[0008] German Patent No. 102010003385 discloses a method for implementing a job change in a sheet printing press, in which, during changeover after a job change or on-press proofing, previously printed waste sheets and unprinted OK sheets are alternately used, and after the last OK sheet has been printed, several clean print-time waste sheets are created, and at least some of these clean print-time waste sheets are used as start-up waste sheets.

[0009] Technical challenges Against this background, the object of the present invention is to provide an improvement over the prior art, in particular to produce proofs, reduce print waste and make it possible to easily provide proofs for inspection.

[0010] Solution to the problem by the invention This problem is solved according to the invention by the method according to claim 1.

[0011] Advantageous and therefore preferred refinements of the invention are evident from the dependent claims and from the description and drawings.

[0012] A method according to the present invention for producing a proof in a web-processing printing machine, in which a print job and then a subsequent print job are printed by the printing machine and a proof for the subsequent print job is produced, the method being characterized by carrying out a web change from a first web to a second web and producing the proof on an end section of the first web or on a selvage section of the first web or the second web.

[0013] The end section of the first web refers to the last portion of the web at the end of the web, for example, the last 10 m, 5 m, or 2 m, or a last length substantially corresponding to the length of a proof. The selvage section of the first or second web refers to a section on the side of the web, i.e., a section on the left or right side as viewed in the web running direction, for example, a section with a width of less than 33%, 25%, or 10% of the web width.

[0014] The term "proof" is to be understood in the present application as follows: A proof is a test print that is made using a printing method in time before the actual print job on a substrate and is used in particular for inspection by an inspection device, in which case, if necessary, adjustment changes to the print job can be derived and then made to improve the print result. A proof in this application is not a so-called soft proof (a mere monitor display without actual printing). A proof is preferably made using a printed image of the actual print job, or alternatively using a proof image or a calibration control strip. So-called proofing allows, for example, color density measurements in specific colors and / or checking color consistency by comparison with a given sample.

[0015] Advantageous Configurations and Effects of the Invention The present invention advantageously allows for the creation of proofs, reduces print waste, and makes it easy to provide proofs for inspection. The present invention is used, for example, in rotary printing machines for industrial packaging printing.

[0016] The method according to the invention allows proofing (checking) of the next print job in an ongoing printing run. This is particularly advantageous when using (replaced) spot colors, since this advantageously prevents production interruptions and reduces print waste. The proof advantageously allows for external access to the finished web roll, which can be inspected directly or removed for inspection during the ongoing printing run, or allows for access to, for example, an ejected sheet or a selvedge section separated from the web.

[0017] 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.

[0018] A refinement may be characterized by the change from one print job to the subsequent print job being carried out in flight, i.e. without stopping the machine and preferably without slowing down the production speed. A refinement may be characterized by carrying out a web change in flight, gluing the second web to the first web at the gluing point. Instead of gluing, other fixations are also possible, which are conceptually encompassed. A refinement may be characterized by the end section of the first web being located in front of the gluing point, preferably just before the gluing point, i.e. without another section with a different printing being located between them.

[0019] A refinement may be characterized by separating the first web from the second web, preferably by punching and / or cutting and possibly additionally tearing if the web is not completely separated initially. A refinement may be characterized by winding the first web onto a web roll. A refinement may be characterized by ending the web roll with a proof, i.e., forming in particular the last or outer layer of the roll. A refinement may be characterized by the proof provided on the web roll being ready for inspection or being accessible for inspection, in particular from the outside, in particular without being obstructed by further web layers. The proof can therefore preferably be viewed from the outside in the wound roll.

[0020] A refinement may be characterized by separating the first web into sheets, preferably by punching and / or cutting, and possibly additionally tearing if they are not completely separated at first. A refinement may be characterized by removing at least one sheet with the proof. Removal may preferably be performed by automatic removal. A refinement may be characterized by removing the sheet in the die-cutting machine or behind the die-cutting machine. A refinement may be characterized by removing the sheet in the sheet cutter or behind the sheet cutter. The removed sheet is ready for inspection. For removing the proof in the die-cutting machine, the following process is advantageous: the printing press prints in the same phase position and thus in the same register position as the change from the print job to the proof, so that after changing back from the proof to the print job, the print job is again punched in register. This is particularly important if the proof differs from the print job in terms of format. Proof removal at the sheet cutter allows adjustment of the length of the proof cut from the web.

[0021] A refinement may be characterized by separating the proof from the first web. A refinement may be characterized by cutting with a knife or a laser. A refinement may be characterized by separating a selvage section of the first web. In this case, the selvage section is preferably located on a longitudinal side of the web. A refinement may be characterized by separating the selvage section in an arc. Preferably, a cut is made into the web from one longitudinal side, followed by a subsequent cut in an arc (alternatively parallel to the longitudinal side), and finally, a cut is made again in the same longitudinal side. The arc may have the shape of a flat parabola. The selvage section may be separated from the web and led out, for example, by suction. The selvage section may preferably have a marking printed on the web, in particular on the selvage of the web, ahead of the selvage section, which marking may be detectable in order to recognize the position of the selvage section and to activate the cutting tool at the right moment. The creation of the selvage sections may in principle take place anywhere on the web, ie even outside the end sections.

[0022] A refinement can be characterized in that the print job and the subsequent print job are different from one another, in particular have different print images, for example different print images for packaging. A refinement can be characterized in that at least one printing ink is exchanged. A refinement can be characterized in that a spot color is exchanged.

[0023] A refinement may be characterized in that the proof is produced by at least one printing device. A refinement may be characterized in that the proof is produced by at least four printing devices for CMYK printing. A refinement may be characterized in that the proof is produced by at least five printing devices for CMYK printing and including spot colors.

[0024] One improved form may be characterized in that a value for the length L of the end section of the first web is preset and calibration printing is performed in the end section. The setting is preferably carried out computationally, that is, by a digital computer, preferably taking into account relevant parameters such as the length of the calibration printing image and / or the production speed (web speed) and / or the switching speed of the printing device and / or the period for coloring the involved printing device / printing plate. One improved form may be characterized in that 5m < L < 20m, 5m < L < 15m or 8m < L < 12m or L = 10m is appropriate.

[0025] One improved form may be characterized in that the printing device required for calibration printing of a subsequent printing job is actuated when passing through the end section. One improved form may be characterized in that the corresponding printing device for the printing job is stopped when passing through the end section. One improved form may be characterized in that the printing device required for calibration printing of a subsequent printing job is stopped after passing through the end section. One improved form may be characterized in that the corresponding printing device for the printing job is actuated again after passing through the end section. In this case, actuation and stopping particularly mean the insertion or removal of the printing cylinder and the impression cylinder (or transfer cylinder) involved. Actuation and stopping may be performed immediately before or after the start or end of the end section, respectively.

[0026] One improved form may be characterized in that the printing machine is a flexographic printing machine or a gravure printing machine. One improved form may be characterized in that the printing machine comprises a roll changer for flying roll change. One improved form may be characterized in that the printing machine preferably comprises at least one switchable double printing device with a central impression cylinder. One improved form may be characterized in that the printing machine comprises an in-line platen punching machine. One improved form may be characterized in that the printing machine comprises an in-line sheet cutter.

[0027] A refinement may be characterized in that the proof is produced during production operation of the printing press.A refinement may be characterized in that the proof is inspected using an inspection device, preferably an optical device.A refinement may be characterized in that the inspection is produced during production operation of the printing press.

[0028] The features and combinations of features disclosed in the above Technical Field, Invention and Improvements sections and in the Examples section below may be combined with one another in any way to form further advantageous improvements of the present invention.

[0029] Examples and drawings for the invention 1 to 7 show preferred embodiments of the present invention and improvements, in which corresponding features are numbered the same. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a schematic diagram of a production facility for carrying out a preferred embodiment of the method according to the invention; [Figure 2] FIG. 1 is a schematic cross-sectional view of a payout or roll changer of a production facility. [Figure 3] 1 is a schematic cross-sectional view of a double printing device of a production facility. [Figure 4] 1 is a schematic cross-sectional view of a double printing device of a production facility. [Figure 5] FIG. 2 is a schematic cross-sectional view of a winder of a production facility. [Figure 6] FIG. 2 is a schematic cross-sectional view of a winder of a production facility. [Figure 7] FIG. 2 is a schematic plan view of the first and second webs.

[0031] The production installation shown in Figure 1 comprises a printing press 1, for example a flexographic printing press for packaging printing, for processing a first web 3a and / or a subsequent second web 3b (and possibly further subsequent webs) and optionally a substrate 2 in the form of a sheet 5 traversed from each web. Both webs 3a, 3b fed to the printing press 1 are joined or "spliced" at a gluing point 4 (see Figure 2). The printing press 1 processes the webs substantially in a production direction 6. The production installation further comprises a control computer 7 for controlling the web feed, the printing process and possible further processing steps. The printing press 1 also comprises a sensor 8 for detecting the gluing point 4 or its presence during transport alongside it (see Figure 3).

[0032] The production installation further comprises an unwinder 10, i.e. a roll changer ("splice") for flying roll changes, a retraction device 20, in particular for controlling the web tension, and at least one, preferably several, printing units 21, in particular configured as double printing units 21a and optionally single printing units 21b, which are for example flexographic printing units.

[0033] Furthermore, the production installation comprises a web winder 30 and / or a platen die-cutter 40 and / or a rotary die-cutter 41 and / or a sheet cutter 42. Preferably, only one of the units described is provided, or several units are provided, in which case only one of the several units is active.

[0034] 2, the unwinder for two webs 3a, 3b or with a first web winding 14 and a second web winding 15, has a splicing device 11 which joins the two webs at the gluing point 4, for example with a double-sided adhesive tape, and cuts off the remaining web behind the gluing point 4 with a separating knife 12. In this way, a flying web exchange is possible.

[0035] 3 and 4 show how the two partial printing units 22, 23 of the double printing unit 21a are switched over. The first partial printing unit 22 prints a print job, while the second partial printing unit 23 (temporarily) prints a proof 52 and then prints the subsequent print job 51. A sensor 8 arranged upstream of the double printing unit 21a in the area of ​​the web path detects the passing glue point 4. A control computer 7 connected to the sensor 8 can subsequently calculate the time when the glue point 4 or the end section 54 (see FIG. 7) of the first web 3a will reach the double printing unit 21a. In this case, the distance between the sensor 8 and the double printing unit 21a can be greater than shown. As soon as or just before the end section 54 reaches the printing nip of the double printing unit 21a, one cylinder 25, in particular the flexographic printing cylinder, is released from the central impression cylinder 24, and the other cylinder 25 is simultaneously engaged. A flying change therefore takes place at the beginning of the end section 54, as well as at the end of the end section or behind the gluing point 4. In the region of the end section 54, the second partial printing device 23 is therefore activated, and the first partial printing device 22 is deactivated.

[0036] 5 and 6, the winder for webs 3a, 3b comprises a first web winding 33, a second web winding 34, and a separating device 31 with a separating knife 32 for separating both webs joined at the bonding point 4. The first web 3a, with its end section 54 and bonding point 4, is wound onto the first web winding 33, with the end section 54 located on the outside and therefore accessible for direct inspection or to the operator. The second web 3b is then wound onto the second web winding 34.

[0037] 7 shows a first web 3a and a second web 3b in the upper region. Both webs are joined to one another at the glue point 4 and separated from one another by a separating device 31. A print job 50 is printed on each of the first web 3a and the second web 3b, and additionally, a proof 52 is printed on an end section 54 of the first web 3a. Only on the second web 3b or on a further web is a subsequent print job 51 printed. The end section can be completely separated from the first web, for example, by a cutting device 61 or in the die-cutting devices 40, 41 or in the sheet cutter 42.

[0038] In Figure 7, the lower area shows another solution, namely a calibration control strip 53, which is printed only on the selvage section 62 of the first web 3a and is cut out in an arc from the web by a cutting device 61, for example a laser.

[0039] The proof print 52 and the proof control strip 53 may each be inspected by an inspection device 60, e.g., a camera, which may be done in-line, i.e., within the machine, or offline after removal of each print 52; 53. [Explanation of symbols]

[0040] 1. Printing machines 2 Printing material 3. Web 3a First Web 3b The Second Web 4 Adhesion points 5 seats 6 Production Direction 7 Control Computer 8 Sensors for adhesive points 10 Payout device, roll exchanger 11 Splicing device 12 Separation Knife 14 First web winding body (unwinder) 15 Second web winding body (unwinder) 20 Retraction device 21 Printing device 21a Double Printing Device 21b Single Printing Device 22 First partial printing device 23 Second partial printing device 24 impression cylinder 25 Printing cylinders, especially flexographic printing cylinders 26 Anilox roller 27 Dryer 30 Winder 31 Cutting device 32 Separation Knife 33 First web winding unit (winder) 34 Second web winding device (winder) 40 Platen type punching machine 41 Rotary punching machine 42 Sheet cutter 50 print jobs 51 Subsequent print jobs 52 Proof Print 53 Calibration Control Strips 54 End division 60 Inspection equipment, inspection 61 Cutting devices, especially knives or lasers 62 ear classification

Claims

1. 1. A method for producing proofs in a web-processing printing press, the method comprising printing a print job (50) and then a subsequent print job (51) by said printing press (1), and producing said proof (52) for said subsequent print job (51), A web change is performed from the first web (3a) to the second web (3b), and the proof printing (52) is performed on an end section (54) of the first web (3a), which is the last partial web at the end of the web, or on an edge section (62) of the first web (3a) or the second web (3b), which is a section at a side of the web; If the proof (52) is made on an end section (54) of the first web (3a), winding the first web (3a) onto a web roll (33), finishing the web roll (33) with the proof (52), and externally accessing the completed web roll (33) and proofing the proof (52) against a given sample, or detaching the proof (52) from the first web (3a) by detaching the end section (54) of the first web (3a), and proofing the proof (52) against a given sample, When the proof (52) is made on an edge section (62) which is a section at the side of the first web (3a) or the second web (3b), the proof (52) is separated from the first web (3a) or the second web (3b) by cutting off the edge section (62) of the first web (3a) or the second web (3b), and the proof (52) is proofed by comparing it with a given sample.

2. 2. The method according to claim 1, characterized in that a flying web exchange is carried out and the second web (3b) is glued to the first web (3a) at the glueing points (4).

3. 3. A method according to claim 2, characterized in that the end section (54) of the first web (3a) is located in front of the bonding point (4).

4. 4. The method according to claim 1, wherein the proof (52) provided on the web roll (33) is accessible for inspection (60).

5. 4. A method according to any one of claims 1 to 3, characterized in that the first web (3a) is separated into sheets (5).

6. 6. A method according to claim 5, characterized in that at least one sheet (5) carrying said proof (52) is removed.

7. 4. The method according to claim 1, wherein a printing device (22) required for the proof (52) of the subsequent print job (51) is activated when the end section (54) passes.

8. 8. The method according to claim 7, wherein the corresponding printing device (21) for the print job (23) is stopped when the end section (54) passes.

Images