Cut-to-length squeegee tape for printing technology

Description

Technical field

[0001] The invention relates to a doctor blade for cutting individual doctor blades to length for printing technology, in particular doctor blades for gravure printing, flexographic printing and / or screen printing. The invention further relates to methods for manufacturing such a doctor blade. State of the art

[0002] In printing technology, squeegees are used to remove excess printing ink from the surfaces of printing cylinders and rollers. Such squeegees are usually based on a steel body with a specially shaped working edge.

[0003] Especially in gravure and flexographic printing, the quality of the doctor blade has a decisive influence on the printing result. Unevenness or irregularities on the working edges of the doctor blade, which are in direct contact with the printing cylinder, can lead, for example, to incomplete ink removal from the cylinder's ribs. This can result in uncontrolled ink transfer onto the substrate. Doctor blades for printing must therefore be manufactured with high precision and adapted to the specific requirements of the printing process.

[0004] For example, CH 699 806 A2 (Daetwyler SwissTec AG) describes a manufacturing process for a doctor blade in which a metal base body is subjected to a planing process. This process allows for the production of mirror-symmetrical doctor blades, which are then separated along their longitudinal axis, e.g., by laser cutting.

[0005] Since doctor blades are subject to constant wear and tear during operation, they must be replaced after a certain period of use. Doctor blades are therefore often offered as semi-finished products in the form of rolled-up doctor blade strips or so-called continuous strips. When a new doctor blade is needed, it can be cut from the strip to the required length and installed in the printing press.

[0006] To facilitate cutting to length and simplify the process for end users when replacing squeegees, it is known to pre-cut the individual squeegees to the desired length, then join them together at their ends with strips of adhesive tape and roll them up into a squeegee strip. Individual squeegees can then be easily detached from the squeegee strip as needed by simply peeling back the adhesive tape to the next squeegee. This eliminates the need for the end user to cut or trim the squeegee strip to the correct length.

[0007] However, due to the additional process steps, this is a relatively complex solution in the manufacturing process.

[0008] DE 699 14 492 T2 (Metso Paper AG) also describes a special system for replacing a scraper blade, in which the scraper blade is guided from a roller as a scraper blade strip past a roller and a blade holder and received into a blade pulling device at the opposite end of the roller. The scraper blade strip has edge notches along one longitudinal edge of the strip, so that during operation the notches are present at both ends of the working area or on the sides of the roller. The notches enable uniform bending of the scraper blade during operation, which is intended to lead to more uniform wear. When the working edge area is worn, the scraper blade strip is shifted longitudinally by the distance between two notches, so that a new section of the strip is in contact with the roller. This solution requires a special system.

[0009] Therefore, there is still a need for improved solutions that do not have the aforementioned disadvantages. Description of the invention

[0010] The object of the invention is therefore to provide improved solutions for replacing worn doctor blades in printing technology. In particular, doctor blade strips for cutting individual doctor blades to length for printing technology are to be provided, which can be manufactured as efficiently as possible and allow for easy cutting to length or...

[0011] Allow for the separation of individual squeegees. This must be done in such a way that the quality of the squeegees is not impaired during separation and the safety of the end user is guaranteed.

[0012] This problem is solved by a squeegee strip according to claim 1 and a method for manufacturing a squeegee strip according to claim 13.

[0013] According to a first aspect, the invention therefore relates to a doctor blade for cutting individual doctor blades for printing technology, in particular doctor blades for gravure printing, flexographic printing and / or screen printing, wherein the doctor blade comprises a flat and elongated base body with a working edge area formed in a longitudinal direction, characterized in that the doctor blade has continuous predetermined breaking points extending across the entire width of the doctor blade at defined intervals along the longitudinal direction transverse to the longitudinal direction, wherein the predetermined breaking points are areas of the doctor blade which break predictably under load due to the structure, shape and / or the material properties.

[0014] The squeegee strip or the individual squeegees available from it are designed for removing printing ink from a printing cylinder, an anilox roller and / or an ink roller.

[0015] As has been demonstrated, the predetermined breaking points incorporated according to the invention make it possible to detach or cut to length individual squeegees by simply bending them, forming a well-defined break line. The properties and quality of the individual squeegees are not affected when cut to length. In particular, the squeegees are neither deformed nor is there any damage to the particularly important working edge areas. Furthermore, the break lines are such that there is no significant risk of injury to the end user.

[0016] This contrasts with experimentally produced squeegee strips, which, instead of continuous break points, only featured several spaced perforations. In this case, less clearly defined break edges were created when cutting by folding, and these edges also had sharp and pointed sections. Consequently, there is a significant risk of injury with such squeegees, and the quality of individual squeegees can be compromised during cutting.

[0017] Squeegees for printing are relatively thin compared to other blades. Typically, they have a thickness of less than 0.4 mm. Furthermore, squeegees for printing must be manufactured with exceptional precision, as they are in direct contact with the printing cylinders or rollers.

[0018] The doctor blade has a thickness of 0.05–0.35 mm, particularly 0.15–0.3 mm. This makes the doctor blade suitable for typical printing applications. At the same time, these thicknesses allow for the reliable and efficient incorporation of well-defined break points in doctor blades made from materials typically used in printing applications. These points can then be folded by hand to cut the blade to length.

[0019] The distances between the predetermined breaking points are, in particular, 10 cm - 5 m, and in particular 20 cm - 2 m. However, other distances are also possible.

[0020] The cross-sectional area of ​​the doctor blade can be rectangular, or it can have a shape other than a rectangle. The latter is the case, for example, when the doctor blade has been sanded for texturing purposes.

[0021] In particular, the working edge of the squeegee blade has a grinding finish. Preferably, the working edge is tapered towards the free end in one or more stages, beveled in a wedge shape, chamfered, and / or rounded. Different grinding finishes can also be combined. For example, the working edge can be tapered towards the free end in one or more stages and simultaneously beveled at the free end.

[0022] Accordingly, the squeegee tape is, for example, a lamellar squeegee tape, an I <eilschliffrakelband ein gefastes Rakelband und / oder ein arrondiertes Rakelband.

[0023] According to the invention, a "predetermined breaking point" refers to an area of ​​the squeegee belt which, due to its structure, shape and / or material properties, predictably breaks under load.

[0024] The expression "perpendicular to the longitudinal direction" means in this case that the predetermined breaking points run in a direction approximately perpendicular, in particular at an angle of 80 - 90°, preferably 90°, to the longitudinal direction of the squeegee strip.

[0025] According to the invention, the predetermined breaking points are continuous, meaning that they extend across the entire width of the squeegee belt, in particular without interruption. Preferably, the predetermined breaking points run in a straight line.

[0026] The length of the doctor blade, as is customary, refers in particular to the dimension of the doctor blade measured along its longest extent. The width of the doctor blade, as is customary, refers in particular to the dimension of the doctor blade running perpendicular to its length, extending from the trailing edge of the doctor blade opposite the working edge to the working edge. The thickness of the doctor blade, as is customary, refers in particular to the dimension of the doctor blade running perpendicular to its length and width, extending from the top surface of the doctor blade to its underside. The top and undersides are, in particular, the two largest surfaces of the doctor blade.

[0027] Typically, the length of the squeegee blade is greater than its width. Likewise, the width of the squeegee blade is typically greater than its thickness.

[0028] For example, the thickness of the doctor blade is 0.03–1 mm, preferably 0.1–0.6 mm. The width of the doctor blade is particularly 5–100 mm, preferably 8–80 mm. The length of the doctor blade is, for example, 1–150 m, preferably 25–100 m.

[0029] Preferably, the squeegee strip has no perforations in the area of ​​the predetermined breaking points. This prevents the formation of rough or undefined break edges. However, for special applications, it is also possible to provide one or more perforations in the area of ​​the predetermined breaking points.

[0030] Preferably, the predetermined breaking points extend over the entire width of the squeegee strip, such that the squeegee strip is weakened essentially uniformly with regard to its breaking behavior over the entire width of the squeegee strip.

[0031] According to a particular embodiment, the material of the doctor blade at the predetermined breaking points has at least partially a different structural structure and / or microstructure than the areas of the doctor blade that border the predetermined breaking points longitudinally. This is particularly true over the entire length of the predetermined breaking point. The length of the predetermined breaking point is measured in the direction of the width of the doctor blade. In particular, the predetermined breaking points consist of the same material as the areas of the doctor blade that border the predetermined breaking points longitudinally and / or as the other areas of the doctor blade.

[0032] In particular, the material of the doctor blade at the predetermined breaking points exhibits, at least partially, a higher hardness and / or brittleness than the areas of the doctor blade that border the predetermined breaking points longitudinally. This is especially true across the entire length of the predetermined breaking point. Specifically, the predetermined breaking points consist of the same material as the areas of the doctor blade bordering them longitudinally and / or as the other areas of the doctor blade.

[0033] In this context, "hardness" refers to the Vickers hardness determined according to standard DIN EN ISO 6507-1:2018 to -4:2018.

[0034] In particular, an area of ​​the predetermined breaking points with a different structural structure and / or microstructure and / or an area of ​​the predetermined breaking points with higher hardness and / or brittleness extends in the direction of the thickness of the doctor blade across the entire thickness of the predetermined breaking point. However, it is also possible that these areas extend only across a portion of the thickness.

[0035] In particular, the width of the predetermined breaking points, measured in the longitudinal direction of the squeegee strip, is 25 - 800 µm, especially 100 - 500 µm.

[0036] In particular, the predetermined breaking points each have or consist of a heat-affected zone. Heat-affected zones can be formed by appropriate conditions during the introduction of the predetermined breaking points into the doctor blade body, e.g., by a suitable selection of process parameters during laser processing.

[0037] In a preferred embodiment, the doctor blade has a substantially constant material thickness in the areas of the predetermined breaking points along its entire width. In other words, the material thickness at the predetermined breaking points is essentially constant or uniform. This allows for particularly clean break edges when cutting to length.

[0038] In principle, it is also possible to provide a material thickness that varies along the width of the squeegee belt in the areas of the predetermined breaking points, if this is expedient.

[0039] The thickness or material thickness of the predetermined breaking points can be essentially the same as the thickness or material thickness of the doctor blade in the areas bordering the predetermined breaking points longitudinally. In this case, the fracture behavior at the predetermined breaking points can be controlled, for example, by the material properties at the predetermined breaking points.

[0040] The predetermined breaking points preferably feature continuous grooves running transversely to the longitudinal direction. In the area of ​​the grooves, the doctor blade is thus tapered and therefore weakened.

[0041] The grooves are continuous, meaning they extend across the entire width of the squeegee belt and are open at both ends. Preferably, the grooves run in a straight line.

[0042] The grooves can have a constant cross-sectional area, particularly in the direction of the squeegee blade's width. However, varying cross-sectional areas are also possible in principle. The latter can be advantageous, for example, with specially shaped squeegee blades, such as lamellar squeegees, as it allows the material thickness to be kept constant in the area of ​​the predetermined breaking point.

[0043] Preferably, the squeegee blade has no perforations in the groove area. This reduces or prevents the formation of rough or undefined fracture edges.

[0044] For special applications, it is also possible to provide one or more perforations in the area of ​​the grooves.

[0045] According to a preferred embodiment, the grooves have a decreasing width with increasing depth. The width of the grooves is measured in the longitudinal direction of the doctor blade. This results in clearly defined break edges when the material is cut to length by folding.

[0046] In particular, the grooves have a U- or V-shaped cross-sectional area. This has proven to be the optimal shape.

[0047] However, grooves with other cross-sectional areas, e.g. rectangular cross-sectional areas, are also possible.

[0048] The grooves preferably have a depth of 20–80%, and especially 35–65%, of the squeegee blade thickness. With most materials used in squeegees for printing, this results in good bendability and a clean break.

[0049] In particular, the grooves have a depth of 20–150 µm, especially 25–90 µm. This applies specifically when the doctor blade has a steel body.

[0050] Preferably, the grooves in their widest area have a width in the longitudinal direction of the doctor blade of 20–500 µm, particularly 50–200 µm. This is especially true when the doctor blade has a steel body.

[0051] In particular, the squeegee blade has a different structural structure and / or microstructure in an edge region adjacent to the groove surface than in an inner region of the squeegee blade located further within the base body. Specifically, both the edge region and the inner region consist of the same material.

[0052] In particular, the edge area constitutes a heat-affected zone. This heat-affected zone can be created by appropriate conditions during the machining of the grooves into the doctor blade body, for example, by selecting suitable process parameters during laser processing.

[0053] According to a further advantageous embodiment, the doctor blade has a higher hardness and / or brittleness in an edge region adjacent to the groove surface than in an inner region of the doctor blade located further inside the base body. In particular, both the edge region and the inner region consist of the same material.

[0054] The edge areas preferably have a thickness of 5-60%, in particular 20-50%, of the depth of the respective groove.

[0055] In particular, the edge areas have a thickness of 1–50 µm, especially 5–30 µm. This is especially true when the doctor blade has a steel base.

[0056] The special edge areas allow the fracture behavior at the predetermined breaking point to be specifically improved, so that the fracture edge is even better defined or cleaner.

[0057] The marginal areas can be characterized, for example, by preparing a polished section, polishing it to a high gloss, and examining it under a reflected light microscope. Such methods are known to those skilled in the art.

[0058] In another embodiment, the predetermined breaking points, in particular the grooves, have a projection extending beyond the surface of the doctor blade, especially a rib-shaped projection. This allows the predetermined breaking point to be located by touch, which simplifies cutting to length.

[0059] In particular, the projection is located at the transition between predetermined breaking points, especially the grooves, and the adjacent areas of the squeegee strip.

[0060] In particular, in the longitudinal direction, on both sides of the predetermined breaking points, especially the grooves, there is a rib-like projection running along the entire width of the squeegee body.

[0061] According to another advantageous embodiment, there is a projection on both the underside and the top side of the squeegee strip, in particular a rib-like projection.

[0062] The main body of the squeegee blade is made primarily of metal, plastic, and / or a composite material. Specifically, this includes steel, thermoplastic, thermosetting plastic, and / or fiber-reinforced plastic.

[0063] Preferably, the base body contains or consists of metal, especially steel. For example, carbon steel or stainless steel can be used.

[0064] According to a further advantageous embodiment, the doctor blade has one or more coatings at least in one area of ​​the working edge. The one or more coatings consist, in particular, of a different material than the base material. Specifically, the material of the coating(s) differs from the material of the base material with respect to its chemical composition. For example, the one or more coatings are wear-reducing and / or friction-reducing coatings. The coating can be, for example, a metal coating, a hard coating, a ceramic coating, or a polymer coating. With such coatings, the doctor blade can be further adapted for specific applications.

[0065] Preferably, the predetermined breaking points, especially the grooves, are those created by laser processing. In laser processing, a laser beam is directed at the areas to be processed on the doctor blade, where the interaction of the laser light with the material of the doctor blade causes a localized material modification and / or material removal or ablation.

[0066] Laser processing has proven to be a particularly advantageous method. On the one hand, predetermined breaking points, especially grooves, can be created very efficiently using laser processing, with varying dimensions, shapes, and / or cross-sectional profiles. On the other hand, laser processing has the advantage that, with appropriate selection of process parameters, grooves with the specific edge areas described above can be directly produced.

[0067] Since the processing of the doctor blade during laser processing is carried out purely by laser light and thus without interaction with a physical tool (as in milling) or substances (e.g., in etching), the risk of contamination of the doctor blade with wear material from the tool or substances can be prevented. This is important for doctor blades used in printing technology, as even small amounts of contamination in the working edge area can lead to significant losses in quality.

[0068] Further details on how to carry out the laser processing can be found later in connection with the inventive method.

[0069] The squeegee tape is preferably supplied as a roll, particularly in a container with an opening for dispensing the tape. This allows for space-saving transport and storage of the squeegee tape. Furthermore, using a container protects the squeegee tape from damage and contamination, and the opening makes it easy to remove and cut to length.

[0070] A second aspect of the present invention relates to a method for producing the aforementioned squeegee strip, wherein a squeegee strip to be processed is provided, characterized in that continuous predetermined breaking points, in particular in the form of continuous grooves extending transversely to the longitudinal direction and extending over the entire width of the squeegee strip, are introduced into it at defined intervals along a longitudinal direction, wherein the predetermined breaking points are areas of the squeegee strip which break predictably under load due to their structure, shape and / or material properties.

[0071] The doctor blade to be processed preferably has a base made of metal, plastic, and / or a composite material. In particular, it is made of steel, thermoplastic, thermosetting plastic, and / or fiber-reinforced plastic. Steel, e.g., carbon steel or stainless steel, is especially preferred.

[0072] The process is carried out in such a way that a squeegee strip results as described above, preferably with one or more of the features described above as optional.

[0073] According to a particularly preferred embodiment, the doctor blade is moved continuously, preferably at a constant speed, in the longitudinal direction during the creation of the predetermined breaking points, especially the grooves. The speed is particularly 1–100 m / min, preferably 10–50 m / min. This enables extremely efficient processing of the doctor blade.

[0074] In this case, the tool used to introduce the predetermined breaking points can be moved section by section in the longitudinal direction during processing, so that it is possible to introduce transverse predetermined breaking points, in particular grooves, into the squeegee strip despite the movement of the squeegee strip.

[0075] According to a particularly preferred embodiment, the predetermined breaking points, especially the grooves, are created by laser processing with a laser light beam. The advantages in this regard have already been described above in connection with the squeegee strip according to the invention.

[0076] In particular, the laser light beam is either a continuous-wave laser beam or a pulsed laser beam. A continuous-wave laser beam consists of light waves with a constant intensity over time. A pulsed laser beam has a pulsating intensity of light waves. Such laser processing systems are generally known to those skilled in the art.

[0077] In laser processing, the movement of the laser beam can be achieved using X-deflection units to deflect and focus laser beams in one dimension, or XY-deflection units to deflect and focus laser beams in two dimensions. Galvanometer scanners with mirrors are one example of a suitable device.

[0078] The laser beam power during laser processing is preferably between 5 and 100 W, particularly between 30 and 70 W. This allows for the efficient processing of materials typically used for doctor blades, such as steel. However, lower or higher power levels may be suitable for other materials or special doctor blades.

[0079] Preferably, the light of the laser beam is UV light, visible light, or infrared radiation. The wavelength of the light is, for example, in the range of 150 nm to 3 µm, preferably 400 nm to 2.5 µm, and in particular 500 nm to 1.5 µm.

[0080] A focus diameter of the laser beam at the point of impact on the doctor blade is advantageously 1–100 µm, particularly 30–70 µm. This allows for the creation of relatively fine predetermined breaking points, especially grooves.

[0081] Preferably, the doctor blade is moved continuously, particularly at a constant speed, in a longitudinal direction during the creation of the predetermined breaking points, and simultaneously, a focus of the laser light beam on the doctor blade is moved both longitudinally and perpendicularly to it during processing. This allows for a very high throughput, as laser light beams can be moved extremely quickly and precisely by means of appropriate deflection units.

[0082] The process parameters during laser processing, in particular the power and movement of the laser light beam, are controlled in such a way as to change the material properties and / or result in material removal.

[0083] Changing the material properties particularly affects the structure, microstructure, hardness and / or brittleness.

[0084] The removal of material creates grooves in particular.

[0085] According to a particularly advantageous embodiment, the process parameters during laser processing, in particular the power and movement of the laser light beam, are controlled in such a way that grooves are formed and at the same time the structural structure, microstructure, hardness and / or brittleness of the doctor blade is changed in the edge areas of the grooves.

[0086] According to an advantageous embodiment, the process parameters are controlled during laser processing in such a way that deformation of the squeegee is reduced or prevented.

[0087] Preferably, the process is controlled by a control unit. In particular, the control unit controls the movement of the laser light beam, the movement of the doctor blade, and / or the power of the laser light beam.

[0088] In particular, the squeegee strip is rolled up after the grooves have been cut and preferably packed in a container.

[0089] Further advantageous embodiments and combinations of features of the invention can be derived from the following detailed description and the entirety of the patent claims. Brief description of the drawings

[0090] The drawings used to illustrate the exemplary embodiment show: Fig. 1 a device for continuously laser processing a doctor blade from the side; Fig. 2 a schematic representation of a device made with the device. Fig. 1 machined strip section with V-shaped, continuous grooves in a top view; Fig. 3 a schematic representation of the machined strip section made of Fig. 2 from the side; Fig. 4 the guidance of the laser light beam when introducing the grooves into the moving doctor blade from the Figs. 2 and 3Fig. 5 on the left shows the finished doctor blade in coiled form in a doctor blade box with a slotted dispensing opening. On the right, the cutting of individual doctor blades from the doctor blade is shown schematically; Fig. 6 is a micrograph of a steel doctor blade in the area of ​​a U-shaped groove created by laser processing; Fig. 7 is a micrograph of a steel doctor blade in the area of ​​a predetermined breaking point created by laser processing in the form of a continuous heat-affected zone with altered structure and microstructure.

[0091] Basically, identical parts in the figures are marked with the same reference symbols. Ways to implement the invention

[0092] Fig. 1 Figure 10 shows a device 10 for laser processing a doctor blade 100 from the side. Figures 2 and 3 Figure 100c shows the processed tape sections in a top view and from the side.

[0093] In Fig. 1On the left side, a wound section 100a of the doctor blade strip lies on a first spool 11a. The doctor blade strip 100 is continuously unwound from the spool 11a and guided via a strip centering device 12 past a laser processing station 14 and through a strip feed device 13 to a second spool 11b. The doctor blade strip 100 has a base body 101 and a longitudinally extending and step-tapered working edge 102 (see Fig. 2 For example, it is a lamellar squeegee strip with a length of 50 m and a width of 50 mm, which is made of steel with a thickness of 0.15 mm.

[0094] In the area between spool 11a and laser processing station 14, there is an unwound and unprocessed strip section 100b, which enters the laser processing station 14 and is provided there with a laser light beam 15 at regular intervals with predetermined breaking points in the form of continuous grooves 110.1, 110.2, 110.3 running transversely to the longitudinal direction of the doctor blade 100 (see Figs. 2 and 3The laser processing system 14 includes a laser light source 14.1, e.g., a fiber laser, with a downstream galvanometer scanner 14.2, which allows the laser beam to be moved spatially. During processing, the doctor blade is continuously guided past the laser processing station 14 at a constant speed of, for example, 30 m / min. A control unit ensures that the laser light beam 15 is moved across the doctor blade 100 by the galvanometer scanner 14.2 in such a way as to form the transverse grooves. The light of the laser light beam 15 has, for example, a wavelength of 1064 nm.

[0095] After the squeegee strip 100 has passed the laser processing station 14, the processed strip section 100c reaches the second spool 11b, where the previously processed and wound strip sections 100d are already present.

[0096] Fig. 2Figure 1 shows the processed section 100c of the doctor blade 100 in a top view. Perpendicular to the longitudinal direction L of the doctor blade 100c, and parallel to the transverse direction B (direction of width), are three continuous V-shaped grooves 110.1, 110.2, 110.3 with a constant groove cross-section. The grooves extend straight across the entire width of the doctor blade 100 and are spaced apart from each other at a distance A of, for example, 50 cm. The V-shaped grooves 110.1, 110.2, 110.3 form predetermined breaking points at which the doctor blade can be cut to length.

[0097] Fig. 3 Figure 1 shows the processed section 100c of the doctor blade 100 in a side view. The V-shaped grooves have a width NB (measured along the longitudinal direction L) of, for example, 250 µm and a depth NT (measured along the direction of the thickness D) of, for example, 50 µm.

[0098] In Fig. 4The situation is shown after the two grooves 110.1, 110.2 have been cut and shortly before the third V-shaped groove 110.3 is cut. Since the doctor blade is moved at a constant speed (in Fig. 4 (to the right), while the laser processing device 14 remains in place, the focus of the laser light beam is guided over the doctor blade in an oblique direction 15.1. This makes it possible to create a groove perpendicular to the longitudinal direction despite the doctor blade running continuously. The laser light beam 15 is thus moved during the processing process simultaneously in a direction parallel to the longitudinal direction and perpendicular to it.

[0099] Fig. 5 The image on the left shows the fully finished squeegee strip 100', which has grooves running transversely to the longitudinal direction at regular intervals along its entire length, wound up in a squeegee box 20 or a container.

[0100] The squeegee tape 100' can be removed from the squeegee box 21 through a slot-shaped opening 21.

[0101] In Fig. 5 On the right side, the situation is illustrated in which two individual squeegees 200.1, 200.2 have already been cut or separated from the squeegee strip 100' and a third individual squeegee 200.3 is now being separated by folding the groove 110.3.

[0102] The individual squeegees obtained in this way can then be used in a printing machine, e.g. for removing printing ink in gravure or flexographic printing.

[0103] In Fig. 6 A micrograph of a steel doctor blade in the area of ​​a U-shaped groove 310 produced by laser processing is shown. The steel doctor blade has a base body 301 made of steel with a thickness 303 of 0.15 mm. The longitudinal direction L runs in Fig. 6 in a horizontal direction.

[0104] The groove 310 has a depth of approximately 52 µm and a width at the upper end (measured in the longitudinal direction) of approximately 100 µm. An edge region 312 adjacent to the groove surface 311 (in Fig. 6 The light-colored area is a heat-affected zone created by laser processing, with a different structure and microstructure compared to the inner region of the base body 301. The edge region 312 has a thickness of approximately 15–30 µm.

[0105] Furthermore, on both sides of the groove 310 there is a groove running along the entire width of the doctor blade body (the direction of the width runs in the direction of the groove). Fig. 6 A rib-like projection 313a, 313b extending towards the image plane. The projections 313a, 313b were created directly during laser processing.

[0106] In Fig. 7A micrograph of a steel doctor blade is shown in the area of ​​a predetermined breaking point 410 created by laser processing. The steel doctor blade has a steel body 401 with a thickness of approximately 0.20 mm. The longitudinal direction runs in Fig. 7 also in a horizontal direction. The predetermined breaking point 410 is designed as a heat-affected zone, which has a different structure and microstructure compared to the adjacent areas in the longitudinal direction (light areas). On both the upper and lower sides, a rib-like projection 413a, 413b is formed in the area of ​​the predetermined breaking point, extending over the entire width of the doctor blade.

[0107] The methods and squeegees described above are to be understood merely as illustrative examples, which may be modified within the scope of the invention.

[0108] For example, it is possible to use differently shaped squeegee blades, e.g. with rounded or chamfered working edges, and / or to provide a squeegee blade made of a different material, e.g. a plastic.

[0109] In principle, it is also possible during processing of the doctor blade 100 to stop the blade as soon as it reaches the area to be processed, to create the respective groove, and then to continue moving the doctor blade. In this case, the laser processing system can be simplified, since only a deflection of the laser light beam 15 in one spatial direction is required to create the grooves.

[0110] Furthermore, multiple squeegee belts can be guided parallel to each other and processed with the same laser processing system. This increases throughput.

[0111] The cross-sectional shapes of the grooves 110.1, 110.2, 110.3 can also be chosen differently, e.g. rectangular or asymmetrical. Likewise, the dimensions of the grooves can be adapted for specific materials if required.

[0112] The predetermined breaking point 410 in the squeegee made of Fig. 7 With appropriate selection of process parameters, it is possible to produce without rib-like boards 413a, 413b. The same applies to the doctor blade. Fig. 6 .

[0113] In summary, a novel and highly efficient solution for the production of cut-to-length doctor blades has been found. Doctor blades produced in this way, and the individual doctor blades cut from them, are of high quality and particularly well-suited for removing printing ink in printing technology.

Claims

1. Doctor blade band (100, 100') for cutting individual doctor blades (200.1, 200.2, 200.3) for printing technology, in particular doctor blades for gravure printing, flexographic printing and / or screen printing, the doctor blade band comprising a flat and elongate base body (101; 301; 401) with a working edge region (102) formed in a longitudinal direction, characterized in that the doctor blade band (100) has continuous predetermined breaking points (110.1, 110.2, 110.3; 310; 410) running at defined intervals (A) along the longitudinal direction (L) transversely to the longitudinal direction (L) and extending over the entire width of the doctor blade band, wherein the predetermined breaking points are regions of the doctor blade band which are predictably breakable under load due to the structure, shape and / or material properties.

2. The doctor blade band according to claim 1, wherein the doctor blade band (100) is substantially uniformly weakened with respect to breaking behavior over the entire width (B) of the doctor blade band.

3. The doctor blade band according to at least one of claims 1 - 2, wherein the doctor blade band (100) has no perforations in the region of the predetermined breaking points (110.1, 110.2, 110.3; 310; 410).

4. A doctor blade band according to at least one of claims 1 - 3, wherein the material of the doctor blade band at the predetermined breaking points (310; 410) has in each case at least partially a different grain structure, microstructure, hardness and / or brittleness than the regions of the doctor blade band which adjoin the predetermined breaking points in the longitudinal direction.

5. A doctor blade band according to at least one of claims 1 - 4, wherein the predetermined breaking points comprise continuous grooves (110.1, 110.2, 110.3; 310) extending transversely to the longitudinal direction (L).

6. The doctor blade band of claim 5, wherein the grooves (110.1, 110.2, 110.3; 310) have decreasing width with increasing depth.

7. Doctor blade band according to at least one of claims 5 - 6, wherein the grooves (110.1, 110.2, 110.3; 310) have a depth of 20 - 80%, in particular 35 - 65%, of the thickness (D) of the doctor blade band.

8. Doctor blade band according to at least one of claims 5 - 7, wherein the doctor blade band in edge regions (312) adjacent to the groove surfaces (311) has in each case a different grain structure, microstructure, hardness and / or brittleness than an inner region of the doctor blade band lying further inside the base body (301), wherein in particular the edge region (312) and also the inner region consist of the same material.

9. Doctor blade band according to claim 8, wherein the edge regions (312) have a thickness of 1- 50 µm, in particular 5 - 25 µm.

10. The doctor blade band according to at least one of claims 1 - 9, wherein the base body (101; 301; 401) is made of steel, wherein optionally at least in a region of the working edge (102) one or more coatings are present.

11. The doctor blade band according to at least one of claims 1 - 10, wherein the doctor blade band (100) has a thickness (D) of 0.05 - 0.35 mm, in particular 0.15 to 0.3 mm.

12. The doctor blade band according to at least one of claims 1 - 11, wherein the doctor blade band is present as a roll, preferably in a container (20) with an opening (21) for removing the doctor blade band (100').

13. Method for producing a doctor blade band (100, 100') according to at least one of claims 1- 12, wherein a doctor blade band to be processed is provided, characterized in that continuous predetermined breaking points (110.1, 110.2, 110.3; 310; 410), which extend over the entire width of the doctor blade band and run transversely to a longitudinal direction (L), in particular in the form of continuous grooves running transversely to the longitudinal direction, are introduced into said doctor blade band at defined intervals (A) along the longitudinal direction (L), wherein the predetermined breaking points are regions of the doctor blade band which are predictably breakable under load due to the structure, shape and / or material properties.

14. The method according to claim 13, characterized in that the doctor blade band (100) is moved continuously, in particular at constant speed, in the longitudinal direction (L) during the insertion of the predetermined breaking points (110.1, 110.2, 110.3; 310; 410).

15. The method according to at least one of claims 13 - 14, characterized in that the predetermined breaking points (110.1, 110.2, 110.3; 310; 410) are introduced by laser processing with a laser light beam (15).

16. The method according to claim 15, characterized in that a focus of the laser light beam (15) on the doctor blade band is moved both in longitudinal direction and perpendicular thereto during processing.

17. The method according to at least one of claims 15 - 16, characterized in that the power of the laser light beam (15) is controlled in such a way that (i) the grain structure and / or microstructure of the doctor blade band is changed at the predetermined breaking points, (ii) an increase in hardness and / or brittleness occurs in the regions of the predetermined breaking points, and / or (iii) continuous grooves (110.1, 110.2, 110.3; 310) running transversely to the longitudinal direction (L) are produced by material removal.