ROTARY DIE CUTTER FOR CUTTING OUT A PIECE OF MATERIAL FROM A PRINTING MATERIAL

Description

invention

[0001] The present invention relates to a rotary punch having the features of the preamble of claim 1. Technical field of the invention

[0002] The invention lies in the technical field of the graphic arts industry, and in particular in the area of ​​die-cutting. In print finishing, die-cutting is the division of materials, e.g., printing substrates such as paper, cardboard, or plastic film, along a non-straight line. The material can be conveyed as a sheet or web. Die-cutting is preferably performed using the knife-cutting principle and often involves the use of closed-shaped dies, such as circular or polygonal dies.

[0003] Rotary die-cutting uses a rotating die-cutting cylinder and an associated impression cylinder. Together, these form a die-cutting unit. The die-cutting cylinder carries the die-cutting die with the die-cutting knives, which interact with the outer surface or a winding device of the impression cylinder. The die-cutting waste (also referred to as "snippets" in this application) can be vacuumed away in the die-cutting unit. The blanks can be transported and further processed, e.g., stripped, separated, and stored. State of the art

[0004] DE 10 2004 058 599 B4 discloses a device for the finishing processing of sheet-shaped substrates. The device comprises two rotating, interacting processing tools, in particular rollers, for punching the substrate. At least one of the rollers has openings that can be connected to a suction air source and / or blown air source. An extraction hood can also be provided.

[0005] DE 101 47 486 A1 also discloses a punching device with a magnetic cylinder, counter-pressure cylinder and suction device.

[0006] With the current technology, the problem can arise that the (larger) chips completely cover the (smaller) suction air opening of the processing tool. The suction air then only acts on a small portion of the chip's surface, which can result in a holding force that is lower than necessary for secure retention. Chips cannot then be safely transported and removed. Task

[0007] Against this background, it is an object of the present invention to provide a rotary die cutter which is improved compared to the prior art and which in particular makes it possible to remove snippets without problems both from the printing material, to convey them with the die cutting cylinder and to remove them from the die cutting die or the die cutting knife.

[0008] This object is achieved according to the invention by a rotary punch according to claim 1.

[0009] Advantageous and therefore preferred developments of the invention emerge from the subclaims as well as from the description and the drawings. invention

[0010] A rotary die cutter according to the invention for punching a piece of material from a printing substrate comprises: a punching cylinder and an associated impression cylinder guiding the printing substrate, wherein the punching cylinder is connected to a suction air source and preferably alternately to a blowing air source; a punching die arranged on the punching cylinder with at least one punching blade, which has a closed die and a suction opening within the closed die; a cylinder winding device arranged on the impression cylinder;at least one raised or recessed first guide element for guiding suction air and preferably alternately blown air, which is arranged within the closed mold and / or at least one recessed or raised second guide element for guiding air, preferably suction air and preferably alternately blown air, which is arranged in the cylinder lift, and is characterized in that the raised first and / or second guide element is designed as a web and / or that the recessed first and / or second guide element is designed as a groove.;

[0011] The invention advantageously enables problem-free rotary punching, i.e., the problem-free removal of scraps from the printing material, their conveyance with the punching cylinder or its punching die, and their removal from the punching die or its punching blade. For this purpose, according to the invention, a first guide element is provided within the closed die and / or a second guide element is provided in the cylinder lift. Preferably, both guide elements are provided. Likewise, both guide elements preferably work together.

[0012] The first guide element can direct the suction air from the suction opening to the piece of material or snippet, i.e., to its surface facing the cutting cylinder, particularly to its entire surface (obviously reduced by the portion covered by the guide element or its support surface). This can increase the suction force, as well as the holding force. This can also improve the separation of the snippet from the printing material if blast air is used alternately instead of suction air.

[0013] The second guide element can direct air between the cylinder cover and the shred during the detachment of the cutting blade from the impression cylinder or its surface. This improves the detachment of the shred from the cylinder cover, especially if the shred is stuck to the cylinder cover. Further developments of the invention

[0014] A preferred development of the invention can be characterized in that the first guide element is raised or recessed relative to the outer surface of the cutting die and / or that the second guide element is recessed or raised relative to the outer surface of the cylinder guard. The cutting die preferably has a thickness of 0.1 to 0.2 millimeters (measured without the height of the cutting blades). Metal, e.g., steel, is preferably chosen as its material. The cylinder guard preferably has a thickness of 0.05 to 0.2 millimeters. Plastic is preferably chosen as its material. The cylinder guard is preferably glued on, in particular detachably.

[0015] The web can be straight or curved. The web can run radially or parallel to the axis of the impression cylinder. A single web or multiple webs can be provided. Multiple webs are preferably similar or identical in design. The web height (measured relative to the outer surface of the cutting die or cylinder cover) is preferably 0.05 to 0.2 millimeters.

[0016] A preferred development of the invention can be characterized in that the first guide element, designed as a web, is spaced from the punching blade by a distance of 0.2 to 1.0 millimeters.

[0017] A preferred development of the invention can be characterized in that a support surface of the first guide element, designed as a web, is located lower than the punching blade or its cutting edge. The height difference is preferably 0.1 to 0.5 millimeters.

[0018] The groove can be straight or curved. The groove can run radially or parallel to the axis of the impression cylinder. A single groove or multiple grooves can be provided. Multiple grooves are preferably similar or identical in design. The groove depth (measured relative to the outer surface of the cutting die or cylinder cover) is preferably 0.01 to 0.2 millimeters.

[0019] A preferred development of the invention can be characterized in that the second guide element designed as a groove is arranged in the circumferential direction of the impression cylinder.

[0020] A preferred development of the invention can be characterized in that the second guide element designed as a groove is arranged transversely to the circumferential direction of the impression cylinder.

[0021] A preferred development of the invention can be characterized in that the cylinder cover is designed as a film or a film strip and is glued to the surface of the impression cylinder. A film strip is preferably used. The area of ​​the film preferably corresponds to the area of ​​the printing material, particularly if this is in sheet form, or is larger than this area. The film strip is preferably arranged with its longitudinal direction parallel to the axis of the impression cylinder, and its width in the transverse direction preferably corresponds at least to the extent of the punching blades and is, for example, 10 to 50 millimeters.

[0022] A preferred development of the invention can be characterized in that the punching knife penetrates the cylinder sleeve during punching, in particular, penetrates the cylinder sleeve. As a result, the piece of printing material lies deeper in the punching knife or its closed form and can be separated from the printing material more easily.

[0023] The features of the invention, the further developments of the invention, and the exemplary embodiments of the invention, even in any combination with one another, represent advantageous further developments of the invention. Further developments of the invention may also have the individual features or combinations of features disclosed in the above section "Technical Field of the Invention." Embodiments of the invention

[0024] The invention and its preferred developments are described in more detail below with reference to the drawings using a preferred embodiment.

[0025] The drawings show: Figure 1 shows a preferred embodiment of a rotary punch according to the invention; Figure 2 shows a detail of this embodiment; Figure 3 shows a further detail of this embodiment; and Figures 4a-c show embodiments of the first guide element;

[0026] Figure 1 shows a side view of a machine, in particular a printing press 1, or a rotary die cutter 2 of such a machine. The rotary die cutter can also form a die-cutting unit of the machine. The machine can be, for example, a Speedmaster 52 from Heidelberger Druckmaschinen AG.

[0027] The rotary die cutter comprises a cutting cylinder 3 and an impression cylinder 4 associated with the cutting cylinder, i.e., interacting with it. The impression cylinder serves to transport a printing substrate 5, in particular a sheet of paper, cardboard, carton, or film (plastic or metal / metallized). The rotary die cutter is intended or designed to cut a piece of material (or a so-called snippet) 6 from the printing substrate.

[0028] The punching cylinder 3 is connected to a suction air source 7 and a blowing air source 8. The suction air provided thereby serves to suck in the material piece 6 during the punching process (at a first angular position), and the blowing air provided serves to remove the material piece / chip after the punching process (at a second angular position).

[0029] A cutting die 3 is mounted on the surface 3a of the cutting cylinder 3, for example, held magnetically. The cutting die has at least one cutting blade 10, preferably a plurality of cutting blades. The cutting blade has a closed shape 11 or a so-called ring shape. The ring shape can be, for example, a circle, oval, square, or rectangle. Other, arbitrarily shaped, closed shapes or rings are also possible.

[0030] Within the closed die 11 of the punching blade 10, the punching die 9 has at least one suction opening 12, e.g., a central and / or circular suction opening. The suction opening 12 is connected to the suction air source 7, for example, via a radial and / or axial bore of the punching cylinder 3 and a rotary feedthrough of the punching cylinder. The suction opening is small compared to the area bounded by the closed die (blade contour), preferably less than 50%, less than 25%, or less than 10%.

[0031] A sheet metal part 4b is mounted on the surface 4a of the impression cylinder 4, and a cylinder cover 13 is mounted on this sheet metal part. The cylinder cover is preferably formed as a foil or a preferably narrow foil strip (parallel to the axial direction of the impression cylinder 4). The cylinder cover is preferably glued to the surface of the impression cylinder.

[0032] When punching the printing substrate 5, the punching knife 10 or its cutting edge 10a penetrates and passes through the printing substrate. The punching knife or its cutting edge also penetrates and passes through the cylinder cover 13, so that the cutting edge touches the surface 4a of the impression cylinder 4. Since the cylinder cover 13 is glued to the surface of the impression cylinder, the piece of the cylinder cover located within the closed mold 11 cannot be removed from the impression cylinder by the suction air. Furthermore, the piece of material 6 lies above it.

[0033] The piece of material 6 of the printing substrate 5, which is also punched out by the punching knife 10 or its cutting edge 10a, is removed from the cylinder intake 13 by the suction air from the suction opening 12 or the suction air source 7 and moved towards the cutting die 9 or its outer surface 9a. The detachment of the piece of material 6 is improved by at least one second guide element 15, in particular a groove, in the cylinder 13. Due to the rotary movements of the two cylinders 3 and 4, the punching knife 10 or its cutting edge 10a moves away from the surface 4a of the impression cylinder 4, and air can thereby pass through the second guide element into the space between the cylinder intake 13 and the piece of material 6.

[0034] The piece of material 6 comes to rest on at least one first guide element 14, preferably a web, of the punching die 9. According to the invention, the first guide element advantageously prevents the piece of material 6 from completely closing the suction opening 12, thereby reducing the suction force and holding force. For the piece of material 6 to rest on, the first guide element or the web preferably has at least one support surface 16. The effective diameter of the suction opening is advantageously increased by the first guide element. Furthermore, the first guide element can advantageously reduce the amount of sucked-in unwanted air.

[0035] The material piece 6 is moved out of the gap between the two cylinders 3 and 4 by the rotational movement of the punching cylinder 3 and into the effective area of ​​a suction hood 17. There, the suction opening 12 is separated from the suction air source 7 and connected to a blowing air source 8, so that the suction opening becomes a blowing opening and the material piece 6 is blown out of the closed mold and removed by means of the suction hood 17.

[0036] Figure 2 shows a detail of a top view of the impression cylinder 4 with the cylinder cover 13 arranged on its surface 4a. The cylinder cover has at least one second guide element 15, which in the example shown is designed as a groove. The groove or the plurality of grooves can be aligned, as shown, substantially parallel to a circumferential direction 19 of the impression cylinder 4. A comparison of the Figures 1 and 2 shows that in Figure 1the orientation of the second guide element is not parallel to the circumferential direction 19, but essentially transverse to the circumferential direction 19. Both are therefore possible.

[0037] In Figure 2 The punching knife 10 and its closed mold 11 are also shown schematically. It can be seen that the space defined by the closed mold is connected to the outside by means of at least one second guide element 15, so that air can penetrate into the interior of the closed mold 11 during the lifting of the punching knife from the impression cylinder 4.

[0038] In Figure 3The penetration of air is shown schematically as a detail. The cylinder cover 13 is mounted with its outer surface 13a on the impression cylinder 4 or its surface 4a. A groove 15 is formed in the cylinder cover 13. The printing substrate 5 lies on the cylinder cover. The punching knife 10 or its cutting edge 10a penetrates through the printing substrate 5 and the cylinder cover 13 to the surface 4a.

[0039] Figure 3shows the punching knife 10' (horizontally offset for clarity) in a further vertical position, in which the punching knife has again moved away from the surface 4a. As soon as the cutting edge 10a at least partially clears the groove 15, air can pass under the cutting edge into the interior of the closed mold 11. This assists in the detachment of the piece of material 6 from the cylinder sleeve 13. Particularly when punching plastic films, e.g., so-called in-mold films, guiding air between the cylinder sleeve 13 and the snippet 6 is advantageous, since such snippets often adhere firmly to the cylinder sleeve.

[0040] In the Figures 4a to 4c various embodiments a to c of the first guide element 14 or preferred webs 14 are shown.

[0041] In Figure 4aThe punching blade 10 is essentially circular, and the suction opening 12 is located centrally to the center of the circular blade. The webs 14 extend from the suction opening 12, but not purely radially, but rather in a curved manner. The ends of the webs 14 do not touch the punching blade 10, but are spaced 18 from the punching blade. Providing such a distance facilitates the manufacture of the punching blade by etching and subsequent machining with a milling head. Due to the distance 18, the milling head can be guided precisely along the contour of the punching blade 10 and the contour of the web 14.

[0042] In the Figures 4b and 4c Alternative embodiments are shown. According to embodiment b, the suction opening 12 is located centrally and the webs 14 extend exactly radially, whereby a distance 18 is also maintained.

[0043] According to embodiment c, the suction opening 12 is not located centrally, but closer to the punching blade 10 in the substrate conveying direction, and the webs 14 extend essentially parallel to each other and transversely to the conveying direction, maintaining a distance from the punching blade. This selection of the position of the suction opening can advantageously improve the removal of the shredded material.

[0044] The suction opening 12 can also be designed as an elongated hole or a hole with any contour, in particular in embodiment c. List of reference symbols

[0045] 1Machine / Printing machine 2Rotary die cutter / Die cutter 3Die cylinder 3bSheet metal 4Impression cylinder 4aSurface 4bSheet metal 5Printing material 6Piece of material / snippet 7Suction air source 8Blowing air source 9Die cutter 9aOuter surface 10Die cutter 10aCutting edge 10'Die cutter 11Closed die 12Suction opening / Blowing opening 13Cylinder winding / Foil / Foil strip 13aOuter surface 14First guide element / web 15Second guide element / groove 16Support surface 17Extraction hood 18Distance 19Circumferential direction

Claims

1. Rotary die cutter for punching out a piece of material from a printing substrate, comprising: - a die-cutting cylinder (3) and an associated impression cylinder (4), the die-cutting cylinder being connected to a suction air source (7); - a cutting die (9) arranged on the die-cutting cylinder with at least one punching knife (10), which has a closed form (11) and a suction opening (12) within the closed form; - a cylinder packing (13) arranged on the impression cylinder; - at least one raised or recessed first guide element (14) for guiding suction air, which is arranged inside the closed form and / or at least one recessed or raised second guide element (15) for guiding air, which is arranged in the cylinder packing characterized in that the raised first and / or second guide element (14, 15) is constructed as a web (14, 15) and / or that the recessed first and / or second guide element (14, 15) is designed as a groove (14, 15).

2. Rotary die cutter according to claim 1, characterized in that the first guide element (14) is raised or recessed towards the outer surface (9a) of the cutting die (9) and / or that the second guide element (15) is recessed or raised towards the outer surface (13a) of the cylinder packing (13).

3. Rotary die cutter according to claim 2, characterized in that the first guide element (14), constructed as a web (14), is at a distance (18) from the punching knife (10).

4. Rotary die cutter according to claim 2 or 3, characterized in that a supporting surface (16) of the first guide element (14), which is constructed as a web (14), is located radially lower than the punching knife (10), i.e. its cutting edge (10a).

5. Rotary die cutter according to claim 4, characterized in that the second guide element (15), which is constructed as a groove (15), is arranged in the circumferential direction (19) of the impression cylinder (4).

6. Rotary die cutter according to claim 4, characterized in that the second guide element (15), which is constructed as a groove (15), is arranged transversely to the circumferential direction (19) of the impression cylinder (4).

7. Rotary die cutter according to one of the preceding claims, characterized in that the cylinder packing (13) is constructed as a foil (13) or a foil strip (13) and is bonded to the surface (4a) of the impression cylinder (4).

8. Rotary die cutter according to one of the preceding claims, characterized in that the punching knife (10) pierces, and in particular penetrates, the cylinder packing (13) during die-cutting.