Method of producing an element for contacting printing material, element for contacting printing material and machine for processing printing material

Abstract

A method of producing an element for contacting printing material, such as an impression cylinder jacket, includes generating a micro-structured surface on a carrier, preferably on an aluminum plate, by electrolytic oxidizing, i.e. anodizing aluminum, and coating the micro-structured surface by a sol-gel process. An element for contacting printing material includes an anodization layer and a sol-gel layer. A machine for processing printing material, in particular a printing press or a sheet-processing rotary printing press for lithographic offset printing, includes an element for contacting the printing material.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a fragmentary, diagrammatic, sectional view of an element contacting printing material in accordance with a preferred exemplary embodiment of the invention;

FIG. 2 is a flow chart of a preferred exemplary embodiment of the method of the invention; and

FIG. 3 is a sectional view of a sheet-fed rotary printing press.

DETAILED DESCRIPTION OF THE INVENTION

Referring now in detail to the figures of the drawings, in which corresponding elements are identified by identical reference numerals, and first, particularly, to FIG. 1 thereof, there is seen a diagrammatic, sectional view of an element 1 contacting printing material, in accordance with the invention, that is to say of a surface 1 contacting printing material in accordance with a preferred exemplary embodiment. The left side of FIG. 1 shows a carrier 2 with a thickness 2′, preferably an aluminum surface or an aluminum plate, before a method step of structuring 13 shown in FIG. 2 has been carried out. The right side of FIG. 1 shows the carrier 2 after the method step of structuring 13 has been carried out.

As a result of the method step of structuring 13 and a corresponding application of material, a thickness 1′ of the element 1 contacting the printing material is greater than the thickness 2′ of the carrier 2 before the method step of structuring 13 has been carried out. A particular proportion of an anodization layer 3, preferably about one third of its thickness 3′, penetrates into the carrier 2. The anodization layer 3, in other words an anodized layer or eloxation layer, has been produced on the carrier 2 according to the invention and is a structured, in particular micro-structured, anodization layer 3, i.e. an anodization layer that has structural protrusions in the micrometer range. Another particular proportion of the anodization layer 3, preferably about two thirds of its thickness 3′, protrudes from the carrier 2. Due to the penetration, the micro-structured layer 3 advantageously adheres to the carrier 2 in a particularly reliable way so that additional time-consuming and costly steps of improving adhesion can be dispensed with.

The thickness 3′ of the anodization layer 3 is preferably between approximately 10 and approximately 50 micrometers. The hardness of the anodization layer 3 preferably ranges up to approximately 500 HV 0.025 (Vickers hardness test).

An ink-repellent layer or coating 4 is applied to or disposed on the anodization layer 3. The ink-repellent coating 4 is generated in a method step 15 shown in FIG. 2 of sol-gel coating and is referred to herein as a sol-gel layer 4. The effect of the sol-gel layer 4 on the structuring of the surface of the element 1 contacting printing material is insignificant and, if necessary, the structuring can be slightly smoothened.

FIG. 2 shows a flow chart of an exemplary embodiment of the method of the invention. The broken lines in FIG. 2 indicate optional steps, i.e. steps that may or may not be carried out.

In a step 10, the carrier 2 is provided for subsequent processing. In a step 11, the carrier 2, in particular its outer surface, which is to be structured, is cleaned to remove any adhering dust and the natural oxidic layer. The cleaning operation 11 may be abrasive blasting, in particular shot peening, bead blasting, or sandblasting.

In the step 13, the carrier 2 is structured or roughened by anodizing the surface of the carrier 2 in a step 14 so that a preferably micro-structured or micro-rough anodization layer, i.e. an electrolytically oxidized aluminum layer (A₁₂O₃) is provided. For this purpose, the carrier 2, which in a preferred embodiment mainly is formed of aluminum, is treated in an electrolytic bath. In order to anodize the carrier 2, the carrier 2 may be dipped into a sulfuric acid or oxalic acid bath and connected as an anode. The anodization layer 3 additionally protects the outer surface of the carrier 2 against corrosion.

In addition to a pre-structuring step 12, the carrier 2 may be selectively roughened mechanically and thus pre-structured before it is anodized in step 14. This may preferably be done by abrasive blasting, in particular shot peening, bead blasting, or sandblasting. The method steps 11 and 12 can thus be expediently combined to form a cleaning and pre-structuring step. Alternatively, the pre-structuring can be achieved by laser treatment, which can be used to produce a specific desired (pre-) structure or (pre-)profile.

Once the surface of the carrier 2 has been provided with the anodization layer 3, the sol-gel layer 4 is applied in a step 15, preferably by spraying and subsequent drying, to improve the ink-repellent surface property and to seal pores in the surface. The sol-gel layer 4 may also be a double layer obtained in two sol-gel coating operations. Preferably, a nano-sol is used, such as polysiloxane, polysilane, or polysilazane.

The back of the carrier 2 may be selectively ground in a step 16 to set the thickness of the element 1 contacting the printing material to a certain value.

Elements 1 according to the invention for contacting printing material may be applied in the shape of plates to impression cylinders, guide cylinders, transfer cylinders, or reversing cylinders. Alternatively, the surfaces of aluminum cylinders may be structured in accordance with the method described above. It is also possible to use the method described herein to structure the operating surfaces of printing material grippers.

FIG. 3 shows a sheet-fed rotary printing press 100 according to the invention, for lithographic offset printing. As viewed in a direction of sheet-transport, the printing press 100 has a sheet feeder 110, a feed table 120, several printing units 130a and 130b (two in the given example, but possibly four, six, or eight), a varnishing unit 140, and a sheet delivery 150. In the feeder 110, printing material sheets 111 are taken from a feed pile 112, guided over the feed table 120 as a shingled stream, and individually fed to the first printing unit 130a. Each of the printing units 130a and 130b has a printing form cylinder 131, a guide cylinder 132, and an impression cylinder 133, as well as an inking unit 135 and a dampening unit 136. A transfer cylinder 134, which may also be a reversing cylinder, is disposed between the printing units 130a and 130b. The sheets pass from the last printing unit 130b to a conveyor 151 of the delivery 150. The sheets to be dried are guided past a drier 152, and the sheets to be powdered are guided past a powdering device 153. Finally, the sheets are deposited on a delivery pile 154 of the delivery 150. The printing press 100 is controlled by a control unit 160. The transfer cylinders 134 or further sheet-guiding cylinders may be equipped with elements 1 contacting printing material, in particular cylinder jackets.

Claims

1. A method of producing an element for contacting printing material, the method comprising the following steps: producing a micro-structured surface on a carrier by electrolytic oxidizing of aluminum; andcoating the micro-structured surface in a sol-gel process.

2. The method according to claim 1, which further comprises carrying out a pre-structuring step prior to the electrolytic oxidizing step.

3. The method according to claim 2, which further comprises performing the pre-structuring step by abrasive blasting.

4. The method according to claim 3, which further comprises selecting the abrasive blasting from the group consisting of shot peening, bead blasting and sandblasting.

5. The method according to claim 2, which further comprises performing the pre-structuring step by laser treatment.

6. The method according to claim 1, which further comprises initially cleaning the carrier.

7. The method according to claim 6, which further comprises performing the cleaning by abrasive blasting.

8. The method according to claim 7, which further comprises selecting the abrasive blasting from the group consisting of shot peening, bead blasting and sandblasting.

9. An element for contacting printing material, the element comprising: a carrier; anda surface having a structured anodization layer and an ink-repellent sol-gel layer.

10. The element for contacting printing material according to claim 9, wherein said carrier is substantially formed of aluminum.

11. The element for contacting printing material according to claim 9, wherein said carrier has a pre-structured surface.

12. A machine for processing printing material, the machine comprising an element for contacting printing material according to claim 1.

13. A printing press, comprising an element for contacting printing material according to claim 1.

14. A sheet-processing rotary printing press for lithographic offset printing, the rotary printing press comprising an element for contacting printing material according to claim 1.