Patent Application
20140124490
This application claims the priority, under 35 U.S.C. ยง119, of German Patent Application DE 10 2012 021 723.4, filed Nov. 5, 2012; the prior application is herewith incorporated by reference in its entirety.
The invention relates to an apparatus for cutting, cutting-out and perforating web-shaped or sheet-shaped substrates, in particular for producing folding boxes or labels, including a transport device for transporting the substrate in a transport plane in a transport direction, a laser cutting device disposed above or below the transport plane for processing the substrate and a machine control system for driving at least the transport device and the laser cutting device. The invention also relates to a method for cutting, cutting-out and perforating web-shaped or sheet-shaped substrates, in particular for producing folding boxes or labels, using the apparatus.
It is known, during the production of folding boxes or labels, to punch out the individual folding boxes or labels from web or sheet substrates. Mechanical punching devices, such as rotary punches and flat-bed punches, for example, are used for that purpose. Alternatively, it is also known to make the cut with a laser. Thus, International Application No. WO 02/14069 A1, corresponding to U.S. Pat. No. 6,592,693, discloses a device and a method for punching out self-adhesive labels by using a laser. In that case, many holes produced in the substrate by the laser are aligned in a row to form a cutting line.
International Application No. WO 99/29496 A1 discloses an apparatus and a method for processing folding boxes, in which creasing lines are introduced into a respective folding box by using a laser and subsequently represent folded edges of the folding box. Likewise, it is known to punch out folding boxes by using a laser apparatus. In that case, the laser beams are aimed at the web or sheet substrates by motorized tilting mirror deflection systems and there travel over the cutting lines or creasing lines to be produced.
The disadvantage of such methods and apparatuses is the large amount of mechanical and control expenditure. That is associated with high costs, high integration effort and a large amount of required space. Furthermore, it is not possible to achieve high production speeds in such systems. The processing speeds of known individual-beam laser systems lie considerably below processing speeds of known narrow-web rotary presses. If the cutting processing is to be carried out in-line in order to print the web or sheet substrates, then as a rule the printing speed has to be reduced. It is further disadvantageous that motor-driven mirror-deflected individual beam laser systems have a limited working area due to a limited projection area, and adaptation to different web widths or sheet formats of the substrate can only be implemented with difficulty.
It is accordingly an object of the invention to provide an apparatus and a method for cutting, cutting-out, creasing and perforating web or sheet substrates with a laser array, which overcome or at least reduce the hereinafore-mentioned disadvantages of the heretofore-known apparatuses and methods of this general type, in which the apparatus can be produced economically and in which the method permits a high processing speed.
With the foregoing and other objects in view there is provided, in accordance with the invention, an apparatus for cutting, cutting-out, creasing and/or perforating web or sheet substrates, in particular for producing folding boxes or labels. The apparatus comprises a transport device for transporting the substrate in a transport plane, a laser cutting device disposed above or below the transport plane for processing the substrate, and a machine control system for driving at least the transport device and the laser cutting device. The laser cutting device has at least one laser array extending over the width of the substrate, i.e. transversely with respect to the transport direction, with individually drivable lasers. It is particularly advantageous if the lasers are constructed as vertical-cavity surface-emitting lasers (VCSEL). Advantages result from the simple construction of the laser array, which permits integration in limited spaces and sharply reduces the mechanical and control effort. The advantage with using VCSEL is the high reliability and longevity thereof.
The laser array can preferably be formed from a plurality of individual arrays. It is advantageous in this case that the VCSEL arrays are very accurate in their geometric form and can be produced economically, which makes it possible to position individual arrays accurately in relation to one another. Thus, a plurality of the VCSEL individual arrays can be combined to form a modular larger array. It is advantageous that a laser array can be built up over the entire substrate width. It is thus possible to process substrates for the production of folding boxes or labels over the entire substrate width at high production speeds.
In a particularly advantageous and therefore preferred development of the apparatus according to the invention, the laser array has a plurality of individual arrays disposed beside one another transversely with respect to the transport direction. The laser array can also have a plurality of individual arrays disposed after one another in the transport direction. In an advantageous development, the individual arrays are disposed offset in relation to one another. It is particularly advantageous if the laser array includes a plurality of individual arrays disposed beside one another and offset after one another. As a result of this offset configuration and the large number of individual laser light sources, overlapping of the laser light sources is produced within the laser array. Until a defective individual array is replaced, the adjacent laser light sources can thus perform the task of the defective individual array during the processing of the substrate. Even with a non-offset configuration of the individual arrays, the advantage is that the arrays can be replaced simply and economically in the event of a defect.
In an advantageous development of the apparatus according to the invention, the laser cutting device has optics disposed between the laser array and the transport plane. This can be implemented, for example, in such a way that individual laser beams are focused, in order to achieve a partial increase in power. Thus, a respective individual array can be constructed, in particular, as a coherently coupled diode-laser emitter array, which provides high power and a high power density.
In an advantageous embodiment of the apparatus according to invention, the machine control system thereof has a workflow link, a standard interface and/or an interface for the entry of cutting data. In this case, cutting data means the specification of the geometry and position on the substrate of the cuts, cut-outs, creasing lines or perforations to be made. The cutting data can, for example, already be present from the pre-press stage.
In an advantageous embodiment of the apparatus according to the invention, the machine control system thereof is connected to a camera aimed at the substrate, in particular a CNN camera. The camera is disposed upstream of the laser cutting device and is used to detect elements, i.e. individual printed images, blanks or labels, on the substrate. In this case, detection of the edges is carried out, so that, by using the laser cutting device, processing of the substrate can automatically be carried out in the correct positions.
Edges can be extracted from gray value images by using gradient filters (e.g. Sobel filters) and stored in gradient images. For each image point, the gradient images contain information about the thickness (magnitude) and the direction of an edge at the position of the image point. This information can be used to follow edges along the direction thereof (tracking). Therefore, the pixel-based edge information is transformed into list representations. In a subsequent evaluation, the contour lists can then be processed further as objects.
During the tracking of edges, secondary conditions relating to the geometric shape of the edge to be extracted can be imposed, e.g. that the edge points tracked are to form a straight line. Then, only points which satisfy this condition are taken into account during the tracking. The tracking then no longer transforms edge regions into list representations but into geometric shapes, for example straight-line segments. Further examples of geometric shapes are circles and ellipses.
With the objects of the invention in view, there is concomitantly provided a method for cutting, cutting-out, creasing and/or perforating web or sheet substrates, in particular for producing folding boxes or labels, in particular by using an apparatus as described above, which comprises moving the substrate past a laser array having individually drivable vertical-cavity surface-emitting lasers (VCSEL) and processing the substrate, i.e. providing it with cuts, trims, cut-outs, creasing lines and/or perforations. In this way, processing at high transport speeds of the substrate is made possible.
The above-described invention and the above-described advantageous developments of the invention also represent advantageous developments of the invention in any desired combination with one another.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an apparatus and a method for cutting with a laser array, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now in detail to the figures of the drawings, in which mutually corresponding elements and components are provided with the same designations,
and first, particularly, to
The structure of the laser cutting device 1 is illustrated in more detail in
The machine control system 6 can, moreover, be connected to a camera 11 aimed at the substrate 100, in particular a CNN camera. The camera 11 is disposed upstream, as seen in the transport direction T, of the laser cutting device 1 and is used to detect printed elements, i.e. individual printed images, blanks or labels, on the substrate 100. The required computing operations are carried out in the machine control system 6. In this case, detection of edges is carried out, so that, by using the laser cutting device 1, processing of the substrate 100 can automatically be carried out at the correct positions, so that, for example, labels can be cut out.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102012021723.4 | Nov 2012 | DE | national |
