Method of operating a flat-bed die cutter

Abstract

In a method of operating a flat-bed die-cutter a printing substrate in the form of a web is fed to a die-cutting module of the flat-bed die-cutter, a web section is severed from the web and removed as waste. The web is guided through the die-cutting module and the web section is severed from the web in or downstream of the die-cutting module and removed as waste. Products are thus formed by die-cutting a web while reducing waste and periods of standstill.

Claims

1. A method of operating a flat-bed die-cutter, the method comprising: feeding a printing substrate in the form of a web to a die-cutting module of the flat-bed die-cutter and guiding the web through the die-cutting module; severing a web section from the web downstream of the die-cutting module by either, cutting the web section off by a cross-cutter that rotates or moves up and down and is different from a die-cutting knife of the die-cutting module; or only partly cutting the web section off by a cross-cutter that rotates or moves up and down and is different from the die-cutting knife of the die-cutting module and then tearing off the web section; and removing the web section as waste by at least one of winding the waste onto a winding roller, depositing web sections into a waste delivery or shredding the web sections; operating the die-cutting module, during or after removing the web section, in-register at a matching speed relative to the speed of a printed image of a print on the web; and starting the feeding of the web to the flat-bed die-cutter and guiding of the web through the die-cutting module at a beginning of a production run, continuing the feeding and guiding without interruption during the removal of the web section and the in-register die-cutting of the web at the matching speed, and not stopping the feeding and guiding until production ends.

2. The method according to claim 1, which comprises moving the severed web section out of the die-cutting module by way of a pair of rollers.

3. The method according to claim 2, wherein the cross-cutter is disposed upstream or downstream of the pair of rollers.

4. The method according to claim 1, wherein a cross-cutter is disposed upstream or downstream of the pair of rollers.

5. The method according to claim 1, which comprises removing the web sections out of a transport path by way of a deflector.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 illustrates the implementation of a first preferred embodiment.

(2) FIG. 2 illustrates the implementation of a second preferred embodiment.

(3) FIG. 3 illustrates the implementation of a third preferred embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(4) Referring now to the figures of the drawing in detail, each of the figures illustrates a machine 1 implementing different preferred embodiments of the method of the invention. Among other aspects, the following paragraphs describe a die-cutting process; alternatively, it may be an embossing process or a simultaneous die-cutting and embossing process.

(5) Each one of the figures illustrates a machine 1, in particular a flat-bed die-cutter 1 or in particular a machine comprising a flat-bed die-cutter 1. A printing substrate 2 in the form of a web 2, in particular made of paper, cardboard, paperboard, or foil, preferably a web of cardboard, is fed to the die-cutter. The web may be unwound from a (non-illustrated) supply reel. The supply reel may be received on a (non-illustrated) unwinding device.

(6) Preferably the web has a print on at least one side or at least carries a print register mark. The printing operation may be carried out on the same machine, i.e. the machine may comprise at least one printing unit disposed upstream of the die-cutter. The machine may be a printing press with an integrated flat-bed die-cutter or with a flat-bed die-cutter connected in line. The printing unit may be a lithographic offset printing unit, a gravure unit, a relief printing unit or flexographic printing unit or a digital printing unit, in particular an ink printing unit. There may likewise be a number of identical or different upstream printing units. The printing operation may alternatively be carried out by a different machine such as a separate printing machine.

(7) The web is fed in via rollers 3, preferably multiple rollers 3, along a transport path 4, preferably a winding transport path. At least roller 3a and/or roller 20 may be (a) pull roller(s), i.e. driven by a motor. At least one roller 3b may interact with a counterpart roller or engagement roller. The counterpart roller/engagement roller may have segments. At least a roller 3c may be a storage roller, i.e. it may be disposed for movement and driven by a motor. At least roller 3a and/or 20 may be a steel roller.

(8) The transport path may comprise a so-called curling sensor 5 and/or a register sensor 6. The curling sensor is used to detect so-called curling, i.e. the formation of undesired waves or other deformation of or damage to the web such as wavy web edges. Curling may be caused by changes in humidity and/or ambient temperature, for example. Curling may cause problems when the printing substrate is processed. The register sensor is used to detect the print register of a print located on the web. The register sensor may be used to detect a bar code or two-dimensional code. The transport path may comprise a decurler 21.

(9) Each one of the figures illustrates a die-cutting module 7 of the flat-bed die-cutter 1. The module may comprise an upper die-cutter platen 8, for instance with a cutting tool or cutting die or cutting plate, and a lower die-cutter platen 9, for instance with a counter-pressure tool/creasing plate. At least one of the two die-cutter platens may be disposed to be movable for die-cutting purposes; the lower die-cutter platen may, for instance, move up and down. At least one of the two platens may comprise die-cutting knives 22, preferably multiple die-cutting knives 22. At least one of the two platens may preferably include a severing knife 10. The severing knife is preferably used to sever the die-cut sheet 2a from the web 2. The severing knife may sever the web 2 across its entire width. Alternatively, the severing knife may only partly sever the web, for instance only in the edge region thereof.

(10) Each one of the figures illustrates what is known as an upper kicking roller 11 and a lower kicking roller 12. The kicking rollers are preferably used to grip a severed sheet 2a, preferably in the downstream third thereof, and convey it out of the die-cutting module 7. At least one of the kicking rollers preferably comprises a lip, for instance a rubber lip. The said lip may grip a sheet that has been severed from the web.

(11) FIG. 1 illustrates exemplary embodiments preferably including one or more deflection rollers 3d and a winding roller 13, preferably driven by a motor. Deflection rollers guide the web 2 to the winding roller along a transport path 4b. The winding roller is used to wind up an undesired section 2b of the web 2.

(12) Section 2b shown in FIG. 1 (and in FIGS. 2 and 3) may exhibit what is known as curling, for instance, or may have become unusable due to another form of deformation, damage, and/or prints. The section is preferably severed from the web by cross-cutting or partial cross-cutting and tearing. The severed section is waste.

(13) FIG. 1 illustrates a first embodiment in which the machine 1 comprises a winding roller 13 disposed upstream of the die-cutting module 7. The web 2 is preferably guided to the winding roller by multiple deflection rollers 3d. FIG. 1 illustrates second and third embodiments (in dashed and dash-dotted lines, respectively), in which the respective winding roller is disposed downstream of the die-cutting module 7. The web 2 is preferably guided to the winding roller by a deflection roller 3d. The rollers 3d are preferably movable. “Upstream” and “downstream” are understood as spatial terms: in the first embodiment 1, the winding roller is disposed on the inlet-side region relative to the module 7; in the second and third embodiments, it is disposed in the outlet-side region thereof. In the first and second embodiments, the respective winding roller is disposed “at the top”; in the third embodiment it is “at the bottom”. “At the top” and “at the bottom” are likewise understood as spatial terms: in the first and second embodiments, the respective winding roller is disposed above the plane 14 of the transport path of the printing substrate 2 through the module 7; in the third embodiment, it is disposed below the plane of this path. The preferred embodiment has a short transport path 4b corresponding to the second or third embodiment, for instance. If a prior art machine is retrofit, the first embodiment may be preferred if the winding roller has already been provided in a position “upstream of the die-cutting module and below the plane”. In all three embodiments, the web 2 is advantageously guided through the die-cutting module 7 before being guided to the winding roller. This provides an advantageous severing of the web in the die-cutting module, preferably using severing elements of the die-cutting module such as one or more die-cutting knives or at least one severing knife.

(14) In addition to the three embodiments, FIG. 1 illustrates how the web is guided to the winding roller 13 in accordance with the prior art: A disadvantage is that the web 2 is guided from the storage roller 3c to the winding roller along the transport path 4a indicated by dashed lines, i.e. upstream of the die-cutting module 7 and not through the latter.

(15) FIG. 2 illustrates two further embodiments (four and five) that preferably include a waste deflector 15, preferably a guide plate 15a, and preferably include a waste delivery 16. The deflector guides a severed web section/sheet 2 to the delivery—a process that the guide plate may assist in. In addition or as an alternative to the delivery, a shredder 16b for waste may be provided. The web section/sheet 2a may likewise be severed from the web 2 by a cutting device 17 such as a rotating cross-cutter 17 or cross-cutter that moves up and down 17, which may be disposed between the die-cutting module 7 and the kicking rollers 11 and 12 or, alternatively (as indicated by the dashed lines), between the kicking rollers and the delivery. This embodiment does without the winding roller 13; however, it may still be present for a different purpose.

(16) FIG. 3 illustrates two further embodiments (six and seven) that preferably likewise include a waste deflector 15, preferably a guide plate 15a, and preferably include a waste delivery 16. The deflector guides a severed web section/sheet 2a to the delivery—a process that the guide plate may assist in. In addition or as an alternative to the delivery, a shredder 16b for the waste may be provided. The web section/sheet 2a may likewise be severed from the web 2 by a cutting device 17 such as a rotating cross-cutter 17, which may be disposed between the die-cutting module 7 and the kicking rollers 11 and 12 or, alternatively (as indicated by the dashed lines), between the kicking rollers and the delivery. This embodiment does without the winding roller 13; however, it may still be present for a different purpose.

(17) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: 1 machine or flat-bed die-cutter 2 printing substrate or web 2a sheet 2b web section 2c waste 3 rollers 3a pull-in roller 3b roller and counterpart roller 3c storage roller 3d deflection rollers 4 transport path (web infeed) 4a transport path 4b transport path 4c transport path (die-cut product) 5 curling sensor 6 register sensor 7 die-cutting module 8 upper die-cutter platen 9 lower die-cutter platen 10 severing knife 11 upper kicking roller 12 lower kicking roller 13 winding roller 14 plane 15 waste deflector 15a guide plate 16 waste delivery 17 cutting device or cross-cutter 18 printed image 19 control unit 20 advancement roller 21 decurler