Anti-bouncing printing roller/sleeve

Abstract

A printing roller for a printing machine, e.g., for a flexographic printing machine, wherein the printing roller includes a rotary and longitudinal axis and an external surface, the external surface being substantially cylindrical and adapted for mounting a plate. The new feature of a printing roller according to the invention is that the external cylindrical surface includes at least one longitudinal groove, where the at least one longitudinal groove includes a geometry with one or more surfaces, the surface or surfaces lying within a circumscribed cylindrical surface for the external surface of the printing roller. In other words, this means that the longitudinal groove or grooves are cutouts in the form of milled or ground grooves in the external cylindrical surface itself on a printing roller.

Claims

1. A printing roller with a sleeve for a flexographic printing machine, including an axis of rotation and a longitudinal axis, where the printing roller is adapted for concentric mounting of the sleeve, and where the sleeve has a substantially internal circular cylindrical surface for unbroken circumferential contact with the entire periphery of the printing roller, and wherein the sleeve has a continuous unbroken external surface, the external surface being substantially cylindrical and adapted for mounting a plate, where the external and substantially cylindrical surface includes at least one longitudinal groove, where the at least one longitudinal groove includes a geometry with one or more surfaces and in which a leading edge of the plate can be fixed, said surfaces lying within a circumscribed cylindrical area of the external surface of the sleeve, wherein the at least one longitudinal groove has a surface geometry of reduced diameter relative to and extending circumferentially continuously between the external surface of circular circumferential curvature, wherein the at least one longitudinal groove has a depth between 0 and 3 mm, wherein the depth is a distance between the circumscribed cylindrical surface of the sleeve and a bottom surface of the longitudinal groove as measured on a cross-section at right angles to the rotary axis of the printing roller/sleeve, the longitudinal groove being of a depth in a radial direction that is less than the thickness of the plate but sufficient to minimize jolting or bouncing of a leading edge upon contact with a counterpressure roller.

2. A printing roller with sleeve for a printing machine according to claim 1, wherein the at least one longitudinal groove includes a planar surface.

3. A printing roller with sleeve for a printing machine according to claim 1, wherein the at least one longitudinal groove includes a convex surface.

4. A printing roller with sleeve for a printing machine according to claim 1, wherein the at least one longitudinal groove includes a concave surface.

5. A printing roller with sleeve for a printing machine according to claim 1, wherein the at least one longitudinal groove is linear and parallel with an axis of rotation of the printing roller.

6. A printing roller with sleeve for a printing machine according to claim 1, wherein the at least one longitudinal groove has a width in one of the following intervals: between 1 and 30 mm, between 2 and 20 mm, between 3 and 10 mm, where the width of the at least one groove is measured on a cross-section of the sleeve which is at right angles to the axis of rotation of the printing roller/sleeve.

7. A printing roller with sleeve for a printing machine according to claim 1, wherein the at least one longitudinal groove has a depth between 0.1 and 2 mm.

8. A sleeve for a printing roller for a flexographic printing machine, including an axis of rotation and a longitudinal axis, wherein the sleeve is adapted for concentric mounting on the printing roller, and wherein the sleeve has a substantially internal cylindrical surface for unbroken circumferential contact with the entire periphery of the printing roller, and wherein the sleeve has an external surface, wherein the external surface is substantially cylindrical and adapted for mounting a plate and includes at least one longitudinal groove, wherein the at least one longitudinal groove includes a geometry with one or more surfaces, wherein said surfaces lie within a circumscribed cylindrical area for the external surface of the sleeve, wherein the longitudinal groove is provided is adapted to fix a leading edge of the plate, wherein the longitudinal groove or grooves of different surface geometry being of reduced diameter relative to and extending circumferentially continuously between the external surface of circular circumferential curvature, where the longitudinal groove or grooves have a depth in one of the following intervals: between 0 and 3 mm, between 0.1 and 2 mm and between 0.2 and 1.5 mm, where the depth is a distance between the circumscribed cylindrical surface of the sleeve and the bottom of the longitudinal groove as measured on a cross-section at right angles to the rotary axis of the printing roller/sleeve, the groove being of a depth in a radial direction that is less than a thickness of the plate, but sufficient to minimize jolting or bouncing of a leading edge upon contact with a counter-pressure roller.

9. A printing machine including at least one doctor blade, screen roller, a printing roller with a sleeve and a counter-pressure roller, wherein the printing roller comprises a sleeve for a flexographic printing machine, including an axis of rotation and a longitudinal axis, where the printing roller is adapted for concentric mounting of the sleeve, and where the sleeve has a substantially cylindrical internal cylindrical surface for unbroken circumferential contact with the entire periphery of the printing roller, and wherein the sleeve has a continuous external surface, the external surface being substantially cylindrical and adapted for mounting a plate, where the substantially cylindrical external surface includes at least one longitudinal groove, where the at least one longitudinal groove includes a geometry with at least one surface, said at least one surface lying within a circumscribed cylindrical area of the external surface of the sleeve, wherein the longitudinal groove is adapted to fix a leading edge of the plate, wherein the geometry of the at least one longitudinal groove being of reduced diameter relative to and extending circumferentially continuously between the external surface of circular circumferential curvature, wherein the longitudinal groove or grooves have a depth between 0 and 3 mm, wherein the depth is the distance between the cylindrical surface of the sleeve and a bottom of the groove as measured on a cross-section at right angles to the rotary axis of the printing roller/sleeve, the longitudinal groove being of a depth in a radial direction that is less than a thickness of the plate, but sufficient to minimize jolting or bouncing of a leading edge upon contact with said counter-pressure roller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a printing machine in a first situation according to prior art.

(2) FIG. 2 shows a printing machine in a second situation according to prior art.

(3) FIG. 3 shows a detail of a sleeve with a first example of a longitudinal groove.

(4) FIG. 4 shows a detail of a sleeve with a second example of a longitudinal groove.

(5) FIG. 5 shows a printing machine in a first situation.

(6) FIG. 6 shows a printing machine in a second situation.

(7) FIG. 7 shows a printing machine in a third situation.

(8) FIG. 8 shows a printing machine in a fourth situation.

(9) FIG. 9 shows a printing machine in a fifth situation.

DETAILED DESCRIPTION OF THE INVENTION

(10) In the explanation of the figures, identical or corresponding elements will be provided with the same designations in different figures. Therefore, an explanation of all details will not necessarily be given in connection with each single figure/embodiment as well as all elements are not necessarily provided with designations in all figures.

(11) In FIG. 1 appears a printing machine 1 according to the prior art, represented here in simple form, and wherein a doctor blade 2 appears in contact with a screen roller/anilox roller 3, to which ink, glue or varnish is transferred from the doctor blade 2. At the center appears a printing roller 4 which in the shown variant is surrounded by a sleeve 5 on which is mounted a plate 6. By rotation of the screen roller 3 and the plate roller 4 with sleeve 5 and plate 6 there is transferred ink, glue or varnish, at first from the screen roller 3 to the plate 6, and then to a medium 8 (shown only in FIG. 9). A counterpressure roller 7 appears at a position under the printing roller 4. The medium 8 is moved between this counterpressure roller 7 and the plate 6 whereby ink, glue or varnish is applied from the plate 6. The rollers 3, 4, 7, doctor blade 2, sleeve 5 and plate 6 all extend in the same direction, and FIG. 1 only shows a cross-sectional view of these units. The direction of rotation of the printing roller is shown by arrow 9 encircling the axis of rotation which is extending into the drawing and in the longitudinal direction at the radial center of the printing roller. The sleeve 5 has an internal cylindrical surface 10 and an external cylindrical surface 11. The plate 6 has a plate leading edge 12 and a plate trailing edge 13 that delimit the plate in its extension on the periphery of the sleeve 5.

(12) In the shown situation, the plate leading edge 12 is in contact with the screen roller 3, which is exaggerated here in order to clarify the problem. Since the distance between the screen roller 3 and the external surface 11 of the sleeve 5 is less than the thickness of the plate 6, this will cause a jolting, called bouncing, for each rotation performed by the printing roller 4. Actually, bouncing will also occur when the plate trailing edge 13 passes the screen roller 3. Furthermore, bouncing will also occur when the plate leading edge 12 and the plate trailing edge 13 encounter and leave, respectively, the counterpressure roller. This bouncing causes an unwanted physical load on the printing machine 1 itself, but also some noise and thereby a challenge to the work environment.

(13) In FIG. 2, appears the same printing machine as in FIG. 1, but here with the screen roller 3 in full contact against the plate 6 on the sleeve 5 on the printing roller 4. Here again, the drawing is exaggerated in order to illustrate that the screen roller 3 and the printing roller 4 are arranged such that a certain contact pressure is built up between these parts.

(14) FIG. 3 shows a detail of a sleeve 5 where, in this external cylindrical surface 11, there is provided a longitudinal groove 14 which, in this variation, includes two convex areas 15 and one concave area 16. These areas 15, 16 together form a longitudinal groove 14 in which the leading edge of a plate 6 can be fixed. In this regard, while in the conventional sense only the concave area 16 can be considered a groove, from the standpoint of this disclosure, the term longitudinal groove is intended to cover any shaped surface that departs from the cylindrical contour of the outer surface of the sleeve 5, whether it be planar, convex or concave.

(15) FIG. 4 also shows a detail of a sleeve 5 where in the external cylindrical surface 11 there is provided a longitudinal groove 14 as well, which in this variation includes three planar areas 17. These planar areas 17 together form a longitudinal groove 14 in which the leading edge of a plate 6 can be fixed.

(16) In FIG. 5, appears a printing machine 1 according to the invention in a first position where the plate leading edge 12 is arranged on a planar area 17, extending across the other two planar areas 17 and 17. The shown situation is immediately before the plate leading edge 12 will encounter the screen roller 3.

(17) FIG. 6 shows a situation which is immediately after the situation in FIG. 5 as the printing roller 4 has now rotated so much that the plate leading edge 12 is only barely in contact with the screen roller 3. Here, it is mentioned that, due to the longitudinal groove 14, the plate 6 is guided in under the screen roller 3 without striking the plate front edge 12 and inducing bouncing.

(18) FIG. 7 shows yet a situation where the plate 6 and the screen roller 3 are on their way to full contact pressure. In this Figure, the screen roller 3 is, however, only on its way up along the second planar area 17, and only after passing the third planar area 17 is there full contact pressure between the screen roller 3 and the plate 6.

(19) In FIG. 8, the screen roller 3 is shown in full contact pressure against the plate 6 as the printing roller 4 is now rotated so much that the longitudinal groove 14 has passed the line of contact between screen roller 3 and plate 6. In FIG. 8, furthermore, it can be seen that the plate leading edge 12 approaches the counterpressure roller 7 where the same advantage as by the longitudinal groove 14 is achieved.

(20) Finally, it is seen in FIG. 9 that the plate 6 is in contact with the screen roller 3 and the medium 8 which is transported between the counterpressure roller 7 and the plate 6. Also between the counterpressure roller 7 and the plate 6 there is a given contact pressure which is also illustrated here by an exaggerated deformation of the plate 6.