Abstract
A screen-printing cylinder includes a cylinder shell and one or more flexible surface elements on the cylinder shell. The one or more flexible surface elements are at least one of resilient or springy, and the one or more flexible surface elements are elliptical patches or circular patches. The flexible surface elements give way upon contact with sheet grippers projecting from an impression cylinder, so that it is not necessary to move the screen-printing cylinder out to avoid contact with the sheet grippers.
Claims
1. A screen-printing cylinder for rotary screen printing, the screen-printing cylinder comprising: a cylinder shell and one or more flexible surface elements on said cylinder shell; said one or more flexible surface elements being at least one of resilient or springy and being able to be curved inward of the screen-printing cylinder; and said one or more flexible surface elements being elliptical patches or circular patches.
2. The screen-printing cylinder according to claim 1, which further comprises a cylinder axis, said one or more flexible surface elements including a plurality of flexible surface elements disposed in a row parallel to said cylinder axis.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
(1) FIGS. 1 and 2 are diagrammatic, cross-sectional views of a screen-printing cylinder and an impression cylinder of a printing system according to the invention;
(2) FIGS. 3 and 4 are perspective views of a screen-printing cylinder; and
(3) FIGS. 5A, 5B and 5C are enlarged, fragmentary, cross-sectional views of flexible surface elements on a cylinder shell.
DETAILED DESCRIPTION OF THE INVENTION
(4) Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is seen a printing system according to the invention. A screen-printing cylinder 1 of the printing system has four flexible surface elements 6, which are disposed in a row parallel to the cylinder axis of the screen-printing cylinder 1 (as seen from the side). An impression cylinder 2 of the printing system transports a sheet 10 of printing material, for example paper, which is held firmly by a pair of sheet grippers 4 projecting out of its cylinder shell 3. A doctor blade 9 has not yet been moved out. The screen-printing cylinder 1 and the impression cylinder 2 are coordinated with each other in such a way that during the continuous rotation of the two cylinders 1, 2 the flexible surface elements 6 of the screen-printing cylinder 1 come to lie exactly over the two pairs of the sheet grippers 4 of the impression cylinder 2.
(5) FIG. 2 shows the same printing system as in FIG. 1, in which the sheet-guiding pair of sheet grippers 4 and the flexible surface elements 6 come into contact with one another. The doctor blade 9 has been moved out. Due to the flexible property of the surface elements 6, the surface elements 6 are curved inward upon contact with the pair of sheet grippers 4. After the end of the contact, the surface elements 6 curve back into their starting position again (not illustrated in FIG. 2).
(6) FIG. 3 shows a screen-printing cylinder 1 according to the invention. The screen-printing cylinder 1 has three flexible surface elements 6 on its cylinder shell 5. The surface elements 6 are disposed in a row parallel to a cylinder axis 7 of the screen-printing cylinder 1.
(7) FIG. 4 shows a screen-printing cylinder 1 according to the invention which has only one flexible surface element 6, which extends over the entire cylinder length.
(8) FIG. 5 shows various possible ways of fixing a flexible material on the sheet-shaped screen-printing cylinder material or in the openings of the sheet-shaped screen-printing cylinder material in step c) of the method according to the invention. In a variant shown in FIG. 5A, the flexible material of the surface elements 6 is fixed, for example by adhesive bonding, to the edges of the openings of the sheet-shaped screen-printing cylinder material, which later forms the cylinder shell 5.
(9) In a variant shown in FIG. 5B, a flexible material of the surface element 6 is additionally fixed to the sheet-shaped screen-printing cylinder material from the other side.
(10) In a variant shown in FIG. 5C, no opening is produced in the sheet-shaped screen-printing cylinder material. In this embodiment, the flexible material of the surface element 6 is fixed directly to the sheet-shaped screen-printing cylinder material, for example by adhesive bonding.
LIST OF DESIGNATIONS
(11) 1 Screen-printing cylinder 2 Impression cylinder 3 Cylinder shell of the impression cylinder 4 Sheet grippers 5 Cylinder shell of the screen-printing cylinder 6 Flexible surface element 7 Cylinder axis of the screen-printing cylinder 9 Doctor blade 10 Sheet
