Method for generating a proof print in a web-fed printing press

Abstract

The invention relates to a method for producing a proof print in a web-fed processing printing press, wherein the printing press (1) prints one print job (50) and then a subsequent print job (51), and for this subsequent print job (51) a proof print (52) is carried out, characterized in that a preferably fly change from a first web (3a) to a second web (3b) is carried out, and the proof print (52) is carried out on an end section (54) of the first web (3a) and preferably before a bonding point (4) between the two webs (3a, 3b) or on an edge section (62) of the first web (3a) or the second web (3b). The invention can produce a proof print in an advantageous manner, here saving waste paper and providing a proof print for checking in a simple manner. The invention is applied, for example, in a rotary printing press for industrial packaging printing.

Description

Technical Field

[0001] This invention relates to a method for generating proof prints in a web processing printing press.

[0002] This invention pertains to the technical field of the graphics industry, and particularly to the field of operating printing presses, preferably rotary printing presses for printing on substrates in the form of webs. Specifically, this invention relates to the subfield of generating and inspecting so-called proof prints to improve print quality. Background Technology

[0003] A printing press is known for its rapid job changes. Proofing is generated for this purpose. Finally, it is known that waste paper is used during proofing.

[0004] DE102017222700A1 discloses a web-based printing press, for example for flexographic printing, which has a switchable double-ink-decks (so-called "Double Ink Decks" or DID). This press allows for rapid job changes, wherein multiple ink-decks of the double-ink-decks can be activated alternatively.

[0005] DE102014220361A1 discloses a method for color control, wherein a proof print (inspection print or test print used to check for errors before the actual printing process) is performed and detected by means of a color measuring instrument.

[0006] When generating a proof print, the printing press is stopped to make the proof print accessible for inspection. This results in production losses and higher production costs.

[0007] EP3921164B1 discloses a method for setting color characteristics (Farbprofil) in a sheet offset printing press, in which pre-printed waste sheets and unprinted good sheets are used during readjustment after job change or during proofing.

[0008] DE102010003385B4 discloses a method for performing job changes on a sheet printing press, in which pre-printed waste sheets and unprinted good sheets are used alternately during readjustment after a job change or during proofing, wherein a certain number of clean printing waste sheets (Sauberdruck-Makulaturbogen) are generated after the last good sheet is printed, and wherein at least a portion of these clean printing waste sheets are used as starter waste sheets (Anlauf-Makulaturbogen). Summary of the Invention

[0009] In view of this background, the objective of the present invention is to propose a technical solution that is an improvement over the prior art, which in particular is capable of generating proof prints, thereby saving waste paper and providing proof prints for inspection in a simple manner.

[0010] This task is solved according to the solution of the present invention:

[0011] This task is solved according to the present invention by a method based on a technical solution.

[0012] Advantageous and further preferred improvements of the present invention can be derived from other technical solutions, as well as the description and drawings.

[0013] According to the present invention, a method for generating proof prints in a web processing printing press, wherein the printing press prints a print job and then prints a subsequent print job, and performs proof prints for the subsequent print job, characterized in that a web change from a first web to a second web is performed, and the proof prints are performed on the end section of the first web or on the edge section of the first or second web.

[0014] The end section of the first web strip is the last segment of the web strip before the end of the first web strip, such as the last 10 meters, 5 meters, or 2 meters, or the last segment of length that is roughly equivalent to the length of the proof print. The edge section of the first or second web strip is the section at the side (Seite) of the web strip, that is, the section located on the left or right side when viewed from the direction of web strip movement, such as a section whose width is less than 33%, 25%, or 10% of the web strip width.

[0015] The term "proof printing" in this application should be understood as follows: Proof printing is a type of inspection printing (Prüfdruck) performed on the substrate with the applied printing method prior to the actual printing job, and this inspection printing is used for checking (particularly by means of an inspection device), wherein, (if necessary) settings changes for improving the printing results for the printing job can be derived and subsequently made. Proof printing in this application is not so-called soft proofing (not a pure screen display without actual printing). Proof printing is preferably performed using a printed image of the actual printing job; alternatively, it is performed using a proof printing image or a proof control bar. During the so-called proofing process, for example, ink density measurements and / or determination of color consistency for spot colors compared to a given sample can be performed.

[0016] Advantageous configurations and effects of the present invention:

[0017] This invention advantageously enables the generation of proof prints, thereby saving paper waste and providing proof prints for inspection in a simple manner. This invention is applied, for example, to rotary printing presses used for industrial packaging printing.

[0018] By means of the method according to the invention, proofing of the next print job can be performed during a continuing printing run. This is particularly advantageous when using (variable) spot colors, as it advantageously prevents production interruptions and saves waste paper. The proof print is advantageously accessible for inspection during a continuing printing run, for example, located outside the finished web roll, where it can be inspected directly or removed for inspection, or, for example, located on the ejected sheets or on the edge section separated from the web roll.

[0019] Improvements to the present invention:

[0020] The preferred improvements of the present invention (hereinafter referred to as "improvements") will now be described. These improvements can also be combined with each other as long as there is no technical incompatibility.

[0021] One improvement may be characterized by a rapid changeover from one printing job to a subsequent printing job, i.e., without stopping the machine, and preferably without reducing production speed. Another improvement may be characterized by a rapid tape changeover, wherein the second tape is bonded to the first tape at the bonding point. Other fixing methods besides bonding may also be used; these should be conceptually included. A further improvement may be characterized by the end section of the first tape being located before the bonding point; preferably directly in front of it, i.e., without any other printed sections in between.

[0022] An improved embodiment may feature the separation of the first and second web strips, preferably by stamping and / or cutting, and if necessary by additionally breaking them apart even with an initial incomplete separation. An improved embodiment may feature the first web strip wound on a web strip roll. An improved embodiment may feature the proofing printing finishing the web strip roll, i.e., particularly forming the last (or outer) layer of the roll. An improved embodiment may feature the proofing printing on the web strip roll being ready or accessible for inspection; particularly from the outside and particularly unobstructed by other web strip layers. The proofing printing is therefore preferably visible from the outside on the wound roll.

[0023] An improvement may be characterized in that the first tape is separated into sheets, preferably by stamping and / or cutting, and if necessary by additional disconnection if the initial separation is incomplete. An improvement may be characterized in that at least one sheet with proof printing is removed. This removal may preferably be achieved by automatic ejection. An improvement may be characterized in that this removal is performed in or after the stamping press. An improvement may be characterized in that this removal is performed in or after the sheet cutter. The removed sheets can be used for inspection. When proof printing is removed at the stamping press, the following process is advantageous: after the printing press switches back from proof printing to the print job, it prints with the same phase and registration position as before the switch from the print job to proof printing, thereby stamping the print job again in a registered manner. This is especially important when the proof printing differs from the print job in format. When proof printing is removed at the sheet cutter, the length of the proof print cut from the tape can be set.

[0024] One improvement may involve cutting the proof print from the first strip. Another improvement may involve cutting using a tool or laser. A further improvement may involve cutting off an edge segment of the first strip. Here, the edge segment is preferably located on a longitudinal side of the strip. An improvement may involve cutting the edge segment in an arc: preferably cutting into the strip from one longitudinal side, then continuing the cut in an arc (alternatively, parallel to the longitudinal side), and finally cutting back to the same longitudinal side. This arc can have a flat parabolic shape. The edge segment can be separated from and extracted from the strip, for example, by suction. The edge segment may have a mark (particularly a mark at the edge of the strip) preferably printed on the strip before the edge segment, which can be detected to identify the position of the edge segment and activate the cutting tool at the correct time. The generation of the edge segment can, in principle, be performed at any point on the strip, i.e., outside the end segments.

[0025] An improvement may be characterized in that the printing job and subsequent printing jobs are different from each other, particularly having different printed images, for example, for different packaging. An improvement may be characterized in that at least one printing ink is changed. An improvement may be characterized in that spot colors are changed.

[0026] A feature of an improved solution may be that the proof printing is carried out by means of at least one printing mechanism. A feature of an improved solution may be that the proof printing is carried out by means of at least four printing mechanisms for CMYK printing. A feature of an improved solution may be that the proof printing is carried out by means of at least five printing mechanisms for CMYK printing and having a spot color.

[0027] A feature of an improved solution may be that a value of the length L for the end section of the first web is pre-given, where the proof printing is carried out in the end section. This pre-giving is preferably carried out in a computational-technical manner, i.e., by means of a digital computer, and preferably takes into account relevant parameters, such as the length of the proof printing image and / or the production speed (web speed) and / or the switching speed of the printing mechanism and / or the time required for inking the relevant printing mechanism / plate. A feature of an improved solution may be that: 5 m < L < 20 m, 5 m < L < 15 m or 8 m < L < 12 m or L = 10 m applies.

[0028] A feature of an improved solution may be that the printing mechanisms required for the proof printing of subsequent printing jobs are activated when the end section passes by. A feature of an improved solution may be that the corresponding printing mechanisms for the printing job are deactivated when the end section passes by. A feature of an improved solution may be that the printing mechanisms required for the proof printing of subsequent printing jobs are deactivated after the end section has passed by. A feature of an improved solution may be that the corresponding printing mechanisms for the printing job are activated again after the end section has passed by. Here, activation and deactivation particularly refer to bringing the relevant printing cylinder into contact (Anstellen) or out of contact (Abstellen) with the impression cylinder (or transfer cylinder). Activation and deactivation can be carried out directly before or after the start or end of the end section, respectively.

[0029] A feature of an improved solution may be that the printing press is a flexographic printing press or a gravure printing press. A feature of an improved solution may be that the printing press includes a reel changer for rapid reel change. A feature of an improved solution may be that the printing press includes at least one switchable double printing mechanism, preferably having a central impression cylinder. A feature of an improved solution may be that the printing press includes an in-line flat-bed punching machine. A feature of an improved solution may be that the printing press includes an in-line sheet cutter.

[0030] A feature of an improved solution may be that the proof printing is carried out during the production run of the printing press. A feature of an improved solution may be that a checking device (preferably an optical device) is used to check the proof printing. A feature of an improved solution may be that the checking is carried out during the production run of the printing press.

[0031] The features and combinations thereof disclosed in the above-described technical field, inventive summary and improvement schemes, and in the following embodiment section—in any combination—represent further advantageous improvements to the present invention. Attached Figure Description

[0032] Figures 1 to 7 Preferred embodiments of the present invention and its improvements are shown. In the drawings, corresponding features are indicated by the same reference numerals.

[0033] Figure 1 A schematic diagram of a production apparatus is shown when performing a preferred embodiment of the method according to the invention.

[0034] Figure 2 A cross-sectional schematic diagram of the unwinder (Abwickler) or roll changer of the production equipment is shown.

[0035] Figure 3 and Figure 4 Cross-sectional schematic diagrams of the dual printing mechanisms of the production equipment are shown.

[0036] Figure 5 and Figure 6 Cross-sectional schematic diagrams of the winding machine (Aufwickler) of the production equipment are shown.

[0037] Figure 7 A top view of the first and second strips is shown. Detailed Implementation

[0038] Figure 1 The production equipment shown includes a printing press 1 (e.g., a flexographic printing press for packaging printing) for processing substrate material 2 in the form of a first web 3a and / or a subsequent second web 3b (and possibly further subsequent webs) and sheets 5 that can be cut laterally from the respective webs if necessary. The two webs 3a and 3b supplied to the printing press 1 are joined together or “stitched” at a bonding point 4 (see [link to printing press]). Figure 2 The printing press 1 handles the web strip essentially along the production direction 6. The production equipment also includes a control computer 7 for controlling the web strip feed and printing process, as well as any possible further processing. The printing press 1 also includes a sensor 8 for detecting the bonding area 4 or its presence during transport past the sensor (see [link to sensor]). Figure 3 ).

[0039] The production equipment also includes: an unwinder 10, i.e., a roll changer (“jointer”) for rapid roll changes; a feeding mechanism 20, particularly for controlling the tension of the web; at least one (and preferably multiple) printing mechanism 21, particularly configured as a dual printing mechanism 21a; and an optional single printing mechanism 21b. These printing mechanisms are, for example, flexographic printing mechanisms.

[0040] In addition, the production equipment includes a winder 30 for the web strip and / or a flatbed press 40 and / or a rotary press 41 and / or a sheet cutter 42. Preferably, only one of the above-described units is present, or multiple units are present, but only one of the multiple units is active.

[0041] Figure 2 The unwinder 10 shown for two webs 3a and 3b (or having a first web roll 14 and a second web roll 15) has a splicing device 11 that joins the two webs together at an adhesive portion 4 (e.g., using double-sided tape) and cuts off the remaining webs after the adhesive portion 4 using a separating cutter 12. In this way, rapid web changeovers can be achieved.

[0042] By comparison Figure 3 and Figure 4 It can be seen how the two sub-printing units 22 and 23 of the dual printing unit 21a switch between each other. The first sub-printing unit 22 prints the final print job, and the second sub-printing unit 23 (temporarily) prints the proof print job 52 and then prints the subsequent print job 51. A sensor 8, arranged in the area of ​​the web path before the dual printing unit 21a, detects the passing bonding area 4. The control computer 7, connected to the sensor 8, can calculate the bonding area 4 or the end section 54 of the first web 3a (see...). Figure 7 When will the dual printing mechanism 21a be reached? Here, the distance from sensor 8 to the dual printing mechanism 21a can be greater than shown in the figure. Once the end section 54 reaches the printing gap of the dual printing mechanism 21a, or shortly before the end section 54 reaches the printing gap of the dual printing mechanism 21a, one roller 25 (especially the flexographic printing roller) depresses from the central impression roller 24, while the other roller 25 closes. Thus, a rapid switch is achieved at the beginning of the end section 54 or at its starting point; similarly, a rapid switch is achieved at the end of the end section or at its ending point, or after the bonding portion 4. Therefore, within the area of ​​the end section 54, the second sub-printing mechanism 23 is active, and the first sub-printing mechanism 22 is deactivated.

[0043] Figure 5 and Figure 6 The winding device 30 shown for webs 3a and 3b includes a first web roll 33, a second web roll 34, and a separating device 31 with a separating cutter 32 for separating the two webs joined together at the bonding portion 4. The first web 3a, together with its end section 54 and the bonding portion 4, is wound onto the first web roll 33, wherein the end section 54 is external and therefore accessible for direct inspection or to an operator. The second web 3b is then wound onto the second web roll 34.

[0044] exist Figure 7 The upper region shows a first strip 3a and a second strip 3b. These two strips were joined together at the bonding point 4 and separated from each other by the separating device 31. Printing jobs 50 are printed on the first strip 3a and the second strip 3b respectively; additionally, proofing prints 52 are printed on the end section 54 of the first strip 3a. Subsequent printing jobs 51 are printed on the second strip 3b or only on the other strip. The end section can be completely separated from the first strip, for example by means of a cutting device 61, or in stamping devices 40, 41, or in a sheet cutter 42.

[0045] exist Figure 7 The lower region shows an alternative solution, namely a proofing control strip 53, which is printed only in the edge section 62 of the first strip 3a, and the proofing control strip 53 is cut out of the strip in an arc shape by means of a cutting device 61, for example by means of a laser.

[0046] Proof printing 52 and proof control bar 53 can be inspected by inspection device 60 (e.g., camera); this can be done inline, i.e., within the machine, or offline after the corresponding printing section 52 or 53 is removed.

[0047] List of reference numerals

[0048] 1. Printing press

[0049] 2. Printing substrate

[0050] 3 strips

[0051] 3a First picture

[0052] 3b Second tape

[0053] 4. Adhesive parts

[0054] 5 pages

[0055] 6. Production Direction

[0056] 7. Control the computer

[0057] 8 Sensors for adhesive bonding areas

[0058] 10. Unwinder, Drum Converter

[0059] 11. Assembly device

[0060] 12 Separation tools

[0061] 14 First image with roll (unwinder)

[0062] 15 Second roll (unwinder)

[0063] 20 Feeding mechanism (Einzugswerk)

[0064] 21 One or more printing presses

[0065] 21a One or more dual printing units

[0066] 21b One or more single printing units

[0067] 22 First Printing House

[0068] 23 Second Printing House

[0069] 24 Impression Rollers

[0070] 25. Printing cylinders, especially flexographic printing cylinders.

[0071] 26 Anilox Roller

[0072] 27. Dryer

[0073] 30 Rewinder

[0074] 31 Separation device

[0075] 32 Separation Tool

[0076] 33 First image with a roll (rewinder)

[0077] 34 Second roll (rewinder)

[0078] 40 Flatbed Stamping Machine

[0079] 41 Rotary stamping machine

[0080] 42-page cutter

[0081] 50 Print jobs

[0082] 51 Subsequent Printing Jobs

[0083] 52 Proofing and Printing

[0084] 53 Proofing Control Bar

[0085] 54 End Section

[0086] 60. Inspection device, inspection

[0087] 61 Cutting devices, especially blades or lasers

[0088] 62. Edge section.

Claims

1. A method for generating proof prints in a web processing printing press, wherein, The printing press (1) prints a print job (50) and then prints a follow-up print job (51), and performs a proof print (52) for the follow-up print job (51). Its features are, Perform a bandgap transformation from the first band (3a) to the second band (3b), and The proofing printing (52) is performed on the end section (54) of the first strip (3a) or on the edge section (62) of the first strip (3a) or the second strip (3b).

2. The method according to claim 1, Its features are, A rapid band change is performed, wherein the second band (3b) is bonded to the first band (3a) at the bonding portion (4).

3. The method according to claim 2, Its features are, The end section (54) of the first strip (3a) is located before the adhesive portion (4).

4. The method according to any one of claims 1 to 3, Its features are, The first strip (3a) is wound on the strip roll (33).

5. The method according to claim 4, Its features are, The proofing printing (52) terminates the web roll (33).

6. The method according to claim 5, Its features are, The proofing print (52) is accessible for inspection (60) on the web roll (33).

7. The method according to any one of claims 1 to 3, Its features are, The first strip (3a) is separated into sheets (5).

8. The method according to claim 7, Its features are, Take out at least one page (5) with the proof print (52).

9. The method according to any one of claims 1 to 3, Its features are, The proof print (52) is cut from the first strip (3a).

10. The method according to claim 9, Its features are, Cut off the edge segment (62) of the first strip (3a).

11. The method according to any one of claims 1 to 3, Its features are, The printing mechanism (22) required for the proof printing (52) of the subsequent printing job (51) is activated as the end section (54) passes.

12. The method according to claim 11, Its features are, The corresponding printing mechanism for the printing job is deactivated when the end section (54) passes through.

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