Doctor Blade Strip For Cutting To Length For Use In Printing

Abstract

A doctor blade band is disclosed. The doctor blade may be used for cutting individual doctor blades for printing technology, in particular for gravure printing, flexographic printing and/or screen printing. The doctor blade band includes a flat and elongate base body with a working edge region formed in a longitudinal direction. The doctor blade band has continuous predetermined breaking points running at defined intervals along the longitudinal direction transversely to the longitudinal direction.

Claims

1. A doctor blade band configured to be cut into individual doctor blades for at least one of printing technology, for gravure printing, flexographic printing and screen printing, the doctor blade band comprising: a flat and elongate base body comprising a working edge region formed in a longitudinal direction, and continuous predetermined breaking points arranged at defined intervals along the longitudinal direction transversely to the longitudinal direction.

2. The doctor blade band according to claim 1, wherein the predetermined breaking points are arranged over a width of the doctor blade band, such that the doctor blade band is substantially uniformly weakened with respect to breaking behavior over the width.

3. The doctor blade band according claim 1, wherein the doctor blade band comprises no perforations in a region of the continuos predetermined breaking points.

4. The doctor blade band according to claim 1, wherein material of the doctor blade band at the predetermined breaking points at least partially comprises at lease one of a different grain structure, microstructure, hardness and brittleness as compared with regions of the doctor blade band which adjoin the predetermined breaking points in the longitudinal direction.

5. The doctor blade band according to claim 1, wherein the predetermined breaking points comprise continuous grooves extending transversely to the longitudinal direction.

6. The doctor blade band of claim 5, wherein the grooves comprise decreasing width with increasing depth.

7. The doctor blade band according to claim 5, wherein the grooves comprise a depth of at least one of 20 - 80 of the thickness of the doctor blade band.

8. The doctor blade band according to claim 5, wherein the doctor blade band comprises in edge regions adjacent to the groove surfaces at least one of a different grain structure, microstructure, hardness and brittleness than an inner region of the doctor blade band lying further inside the base body.

9. The doctor blade band according to claim 8, wherein the edge regions comprise a thickness of 1 - 50 .Math.m.

10. The doctor blade band according to claim 1, wherein the continuous predetermined breaking points are produced by laser processing.

11. The doctor blade band according to claim 1, wherein the doctor blade band a steel base body.

12. The doctor blade band according to claim 1, wherein the doctor blade band comprises a thickness of 0.05 - 0.35 mm.

13. The doctor blade band according to claim 1, wherein the doctor blade band is arrarged in a roll in a container comprising an opening configured for removing the doctor blade band.

14. A method for producing a doctor blade band, comprising the steps of: forming a flat and elongate base body comprising a working edge region formed in a longitudinal direction; and forming at least one of continuous predetermined breaking points and continuous grooves running transversely to a longitudinal direction into the doctor blade band at defined intervals along the longitudinal direction (L).

15. The method according to claim 14, further comprising the steps of continuously moving the doctor blade band in the longitudinal direction during the insertion of the predetermined breaking points.

16. The method according to claim 14, further comprising the steps of introducing the predetermined breaking points with a laser light beam.

17. The method according to claim 16, further comprising the steps of moving a focus of the laser light beam on the doctor blade band both in a longitudinal direction and a perpendicular direction with respect to the doctor blade band.

18. The method according to claim 16, further comprising the steps of controlling power of the laser light beam such that grain structure of the doctor blade band and microstructure of the doctor blade band is at least one of changed at the predetermined breaking points, increases at least one of hardness and brittleness in regions of the predetermined breaking points, and produces continuous grooves running transversely to the longitudinal direction by material removal.

19. The doctor blade band according to claim 5, wherein the grooves have a depth of 35 - 65% of the thickness of the doctor blade band.

20. The doctor blade band according to claim 12, wherein at least a region of the working edge comprises one or more coatings.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0088] Further advantages, features, and details of the various embodiments of this disclosure will become apparent from the ensuring description of a preferred exemplary embodiment and with the aid of the drawings. The features and combinations of features recited below in the description, as well as the features and feature combination shown after that in the drawing description or in the drawings alone, may be used not only in the particular combination received, but also in other combinations on their own, without departing from the scope of the disclosure.

[0089] The drawings used to explain embodiments of the presently disclosed invention depict the following:

[0090] FIG. 1 depicts a device for continuous laser processing of a doctor blade band from the side;

[0091] FIG. 2 depicts a schematic representation of a band section with V-shaped, continuous grooves processed with the device from FIG. 1 in a top view;

[0092] FIG. 3 depicts a schematic view of the machined band section from FIG. 2 from the side;

[0093] FIG. 4 depicts the guidance of the laser light beam during the insertion of the grooves into the moving doctor blade band from FIGS. 2 and 3;

[0094] FIG. 5 depicts on the left side, the finished doctor blade band in wound form in a doctor blade box with a slit-shaped removal opening. The right side schematically depicts the cutting of individual doctor blades from the doctor blade band;

[0095] FIG. 6 depicts a micrograph of a steel doctor blade band in the area of a U-shaped groove made by laser machining; and

[0096] FIG. 7A depicts a micrograph of a steel doctor blade band in the area of a predetermined breaking point introduced by laser processing in the form of a continuous heat-affected zone with altered grain structure and microstructure.

DETAILED DESCRIPTON OF THE INVENTION

[0097] As used throughout the present disclosure, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, the expression “A or B” shall mean A alone, B alone, or A and B together. If it is stated that a component includes “A, B or C”, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. Expressions such as “at least one of” do not necessarily modify an entirety of the following list and do not necessarily modify each member of the list, such that at least one of “A, B, and C” should not be understood as including only one of A, only one of B, only one of C, or any combination of A, B, and C.

[0098] In principle, the same parts are given the same reference signs in the figures.

[0099] FIG. 1 depicts a device 10 for laser processing of a doctor blade band 100 from the side. FIGS. 2 and 3 depict the processed band sections 100c in a top view as well as from the side.

[0100] In FIG. 1, on the left-hand side, a wound-up band section 100a of the doctor blade band is present on a first spool 11a. The doctor blade band 100 is unwound continuously from the spool 11a and guided via a band centering device 12 past a laser processing station 14 through a band feed device 13 to a second spool 11b. The doctor blade band 100 has a base body 101 and a working edge 102 extending in the longitudinal direction L and tapered in a step-like manner (see FIG. 2). For example, it is a lamellar doctor blade band with a length of 50 m and a width of 50 mm, which is made, for example, of steel with a thickness of 0.15 mm.

[0101] In the area between coil 11a and laser processing station 14, there is an unwound and unprocessed band section 100b which enters the laser processing station 14 and is there provided with a laser light beam 15 at regular intervals with predetermined breaking points running transversely to the longitudinal direction of the doctor blade band 100 in the form of continuous grooves 110.1, 110.2, 110.3 (see FIGS. 2 and 3). The laser processing system 14 includes a laser light source 14.1, for example a fiber laser, with a downstream galvanometer scanner 14.2, with which the laser beam can be moved spatially. During processing, the doctor blade band is continuously moved 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 over the doctor blade band 100 by the galvanometer scanner 14.2 in such a way that the transverse grooves are formed. The light of the laser light beam 15 has, for example, a wavelength of 1064 nm.

[0102] After the doctor blade band 100 has passed the laser processing station 14, the processed band section 100c passes to the second reel 11b, where the previously processed and wound band sections 100d are present.

[0103] FIG. 2 depicts the processed band section 100c of the doctor blade band 100 in a top view. Perpendicular to the longitudinal direction L of the doctor blade band 100c, three continuous V-shaped grooves 110.1, 110.2, 110.3 with a constant groove cross-section run parallel to the transverse direction B (= direction of the width). The grooves extend in a straight line over the entire width of the doctor blade band 100 and have a distance A between them of, for example, 50 cm. The V-shaped grooves 110.1, 110.2, 110.3 form predetermined breaking points at which the doctor blade band can be cut to length.

[0104] FIG. 3 depicts the machined band section 100c of the doctor blade band 100 in a top view from the side. Here, the V-shaped grooves have a width NB (measured along the longitudinal direction L) of, for example, 250 .Math.m and a depth NT (measured along the direction of thickness D) of, for example, 50 .Math.m.

[0105] FIG. 4 depicts a situation after which the two grooves 110.1, 110.2 have been inserted and shortly before the third V-shaped groove 110.3 is inserted. Since the doctor blade band is moved at a constant speed (to the right in FIG. 4) while the laser processing device 14 remains in place, the focus of the laser light beam is guided over the doctor blade band in an oblique direction 15.1. This makes it possible to introduce a groove running perpendicular to the longitudinal direction despite the doctor blade band passing through. During the processing operation, the laser light beam 15 is thus moved both in a direction parallel to the longitudinal direction and perpendicular to it.

[0106] FIG. 5 depicts on the left the completely finished doctor blade band 100′, which has grooves running at regular intervals along its entire length at right angles to the longitudinal direction, in wound-up form in a doctor blade box 20 or container, respectively.

[0107] The doctor blade band 100′ can be removed from the doctor blade box 21 through a slit-shaped opening 21.

[0108] FIG. 5 on the right illustrates the situation in which two individual doctor blades 200.1, 200.2 have already been cut to length or separated from the doctor blade band 100′ and a third individual doctor blade 200.3 has just been separated by buckling the groove 110.3.

[0109] The individual doctor blades thus obtained can then be used in a printing machine, e.g., to strip off printing ink in gravure or flexographic printing.

[0110] FIG. 6 depicts a micrograph of a steel doctor blade band in the area of a U-shaped groove 310 made by laser machining. The steel doctor blade band has a base body 301 made of steel with a thickness 303 of 0.15 mm. The longitudinal direction L runs in the horizontal direction in FIG. 6.

[0111] The groove 310 has a depth of about 52 .Math.m and a width at the upper end (measured in the longitudinal direction) of about 100 .Math.m. An edge region 312 adjacent to the groove surface 311 (appearing light in FIG. 6) is a heat-affected zone generated by the laser processing with a different grain structure and microstructure compared to the more interior region of the base body 301. The edge region 312 has a thickness of approx. 15 - 30 .Math.m .

[0112] On both sides of the groove 310, there is also a rib-like projection 313a, 313b running along the entire width of the doctor body (the direction of the width runs in the direction of the image plane in FIG. 6). The protrusions 313a, 313b were directly generated during laser processing.

[0113] FIG. 7 depicts a micrograph of a steel doctor blade band in the area of a predetermined breaking point 410 introduced by laser processing. The steel doctor blade band has a base body 401 made of steel with a thickness of approx. 0.20 mm. The longitudinal direction is also horizontal in FIG. 7. The predetermined breaking point 410 is designed as a heat-affected zone which has a modified microstructure compared with the areas adjacent in the longitudinal direction (light areas). A rib-like projection 413a, 413b is formed in the area of the predetermined breaking point on the upper side and on the lower side and extends over the entire width of the doctor blade band.

[0114] The methods and doctor blades described above are to be understood as illustrative examples only, which may be modified within the scope of the invention.

[0115] For example, it is possible to use differently shaped doctor blade bands, e.g., with rounded or chamfered working edges, and/or to provide a doctor blade band made of a different material, e.g., a plastic.

[0116] In principle, it is also possible during the processing of the doctor blade band 100 to stop the band each time it reaches the point to be processed, to insert the respective groove and then to move the doctor blade band further. 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 insert the grooves.

[0117] Furthermore, several doctor blade bands can be run in parallel next to each other and processed with the same laser processing system. This allows the throughput to be increased.

[0118] The cross-sectional shapes of the grooves 110.1, 110.2, 110.3 can in principle also be selected differently, e.g., rectangular or asymmetrical. Likewise, the dimensions of the grooves can be adapted to special materials if required.

[0119] The predetermined breaking point 410 in the doctor blade of FIG. 7 can be produced without rib-like protrusions 413a, 413b if the process parameters are selected accordingly. The same applies to the doctor blade shown in FIG. 6.

[0120] In summary, it can be stated that a novel and highly efficient solution has been found for the supply of cut-to-length doctor blade bands. Doctor blade bands produced in this way and individual doctor blades that can be cut to length from them are of high quality and, in particular, fully suitable for doctoring printing ink in printing technology.

[0121] Since the devices and methods described in detail above are examples of embodiments, they can be modified to a wide extent by the skilled person in the usual manner without departing from the scope of the invention. In particular, the mechanical arrangements and the proportions of the individual elements with respect to each other are merely exemplary. Some preferred embodiments of the apparatus according to the invention have been disclosed above. The invention is not limited to the solutions explained above, but the innovative solutions can be applied in different ways within the limits set out by the claims.