DE2508397A1 - METHOD OF MANUFACTURING A GRAVURE PRESSURE CYLINDER - Google Patents

Description

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Crosfield Electronics Limited

766 Holloway Road

London N 19 3 JG / England

Process for the production of a gravure cylinder

The invention relates to a method of manufacture a gravure cylinder or a gravure plate.

British Patent 1,229,243 proposes a method of making a gravure cylinder, which consists of a first material, and in the surface of which a grid of cells is worked out, the has the greatest depth of pressure required and which are filled with a second material that is slightly from

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a laser beam guided over it can be decomposed or vaporized. To engrave the cylinder, his Surface scanned line by line by a laser beam whose energy corresponds to that to be engraved Image is modulated, the intensity and the scanning speed of the beam is chosen so that the first Material remains unaffected, but the second material, which fills the cells mentioned, decomposes or vaporizes to a depth that depends on the energy of the laser beam on the elementary area concerned depends.

The advantage of such a method is that the laser beam is not dependent on the grid must be modulated, but only in accordance with the image to be recorded. The scanning process of the The gravure surface therefore does not need to be synchronized with the grid.

The preparatory steps for shaping the cells in the cylinder surface can be carried out beforehand, so that several such cylinders can be processed at the same time and then kept in stock.

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The present invention aims at a further improvement in the production of a gravure surface. A method according to the invention is characterized in that holes or recesses in a flexible Layer of a first material of the same size and regular arrangement according to a grid arrangement for gravure printing systems that the flexible material layer around the surface as a cylindrical Body is placed that said holes or recesses before, during or after the application of the Material layer on the cylindrical body are filled with a second material, which is from the energy radiation is more easily decomposed than the material of the first-mentioned material layer.

In a further embodiment of the invention it is provided that the prepared material layer is filled with the Recesses is exposed to an energy beam scanning the surface line by line, which in accordance with the density of successive elementary surface areas of the to be produced Image is modulated, and that the energy beam has sufficient power to said second

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To decompose or evaporate material.

Depending on the application, the energy beam can be a laser beam or an electron beam or another suitable one Be radiation.

The said flexible material layer can be glued or mechanical or magnetic forces on the cylindrical body are held. This first material layer can for example be copper, with holes or recesses can be made mechanically, e.g. by punching. Depending on the choice of this material, if necessary an etching process can also be used.

This first-mentioned flexible material layer can also be formed from another material, e.g. stainless Steel, mild steel, etc., while the thickness of this first layer of material is kept extremely small can be. This offers the advantage, for example, that the amount required in a method according to the invention on copper is much smaller than is the case with gravure cylinders made of copper.

In addition, the walls of the molded cells

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i.e. the material remaining between the cells from the surface to the base of this material layer have the same thickness. This has the advantage that in the aftertreatment of this material layer after Applying the filling compound, i.e. the second material, stripping off excess filling compound and that associated abrasion of said first layer of material not to change the size of the cells or to change the ratio of the diameter of the cells leads to the wall thickness.

It is also possible to use simple and clean methods for applying the second material to the first Material layer to be used. For example, after the first-mentioned perforated material layer has been applied A liquid plastic is poured over the surface of the printing cylinder at the required cell angle which is cleaned and smoothed after the plastic has hardened. After another process In the context of the invention it is provided that the cylindrical body is coated with a plastic, that then the said first material layer is placed over the thus coated cylindrical body and through

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Heat and / or pressure applied to the plastic through the holes or recesses of the first material layer is pushed through on the outside. This plastic can be used at the same time to form the first layer of material to stick on the surface of the gravure cylinder.

An epoxy resin, for example, is suitable for carrying out a method according to the invention. A hardener is preferably added to the plastic in the form of particles which are smaller than one jx . Suitable hardeners are, for example, aluminum oxide (corundum) in a weight ratio of 40-60%, titanium dioxide in a weight ratio of 10-40% or carbon black in a weight ratio of 2% to 25%.

In another embodiment of a method according to the invention it is provided that the first material layer is filled with the plastic before it is applied to the printing cylinder. Said first material layer may be provided with a tacky base layer, so that it can be applied directly to the impression cylinder, the surface can then be post-processed _o An inventively prepared impression cylinder is in the

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The following is explained in more detail with reference to the drawings and shows:

Fig.1: a printing cylinder with a mechanical Devices held on its surface layer of material j

Fig.2: a process of applying an inventive Gravure foil on a printing cylinder in side view and

3: a side view of a manufactured in this way Printing cylinder.

In FIG. 1, a copper mesh 10 is held on the surface of a cylindrical body 12 by mechanical means. The copper network 10 consists of a material layer or Foil made of copper, in which holes have been punched in a regular grid. To hold this copper layer a terminal block 14 is provided which engages in a keyway 16 in the surface of the cylinder 12.

The second material, i.e. the soft filler filling the holes in the copper mesh, is preferably used after the Applying the copper mesh to the cylinder.

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A perforated material layer 10 is shown in FIG. wherein the holes or cells are already filled with a filling compound before being applied to the printing cylinder 12 became. The material layer 10 is provided with an adhesive coating 18 on its rear side In the illustration of FIG. 3, the material layer 10 is already glued onto the cylinder 12, with the Joint 20 a subsequent pouring is required.

Within the scope of the inventive concept, other methods of fastening the first material _{layer on the printing cylinder can also be used o} For example, "the material layer can be placed over a removable curved surface area of the cylinder, which is then clamped onto the printing cylinder",

In all of the aforementioned exemplary embodiments of the invention, a laser beam can be used to scan the printing surface which caused a displacement or evaporation of the plastic used as a filler suitable device for scanning the cylinder surface

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land to produce the engraving with the help of a laser beam is in the aforementioned British patent; writing 1,229,243 of the applicant described and illustrated ji

Instead of using a plastic as a filler in the first layer of material it is possible to have a perforated or to use metal foil provided with recesses, the cells of which are filled with a second metal, which is more easily attacked by an energy beam than the first metal. In such a use case an electron beam from an electron beam generator can expediently be used as the energy radiation is produced.

The invention is not limited to the illustrated and described exemplary embodiments, but can Different combinations of the features of the invention are used within the scope of the concept of the invention. j

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Claims (14)

Expectations: 1 · Method of machining a cylinder from which a gravure cylinder is made by scanning the Cylindrical surface is produced with an energy radiation, characterized in that holes or Recesses in a single layer of a first Material in the same size and regular arrangement according to a grid arrangement for Gravure printing systems are attached that the flexible Layer of material is placed around the surface as a cylindrical body that said holes or Recesses before, during or after the application of the material layer to the cylindrical body be filled with a second material that is more easily decomposed by the energy radiation than that Material of the first-mentioned material layer. 2. The method according to claim 1, characterized in that that the prepared layer of material with the filled recesses is the surface line for Line is exposed to a scanning energy beam, 509 8 36/0739 which corresponds to the density of successive elemental surface areas of the to be generated image is modulated, and that the energy beam, has sufficient power to the to decompose or vaporize said second material. 3 · The method according to claim 1 or 2, characterized in that the holes or recesses in the said first layer of material are produced mechanically. 4. The method according to any one of the preceding claims, characterized in that said first layer of material mechanically held in a fixed position on the cylindrical body. 5. The method according to any one of the preceding claims, characterized in that said first layer of material is held by gluing on the cylindrical body. 36/0739 6. The method according to claim 5, characterized in that the back of the first material layer is a Has adhesive coating. 7. The method according to any one of the preceding claims, characterized in that the holes or recesses filled in the first material layer after application to the cylindrical body in which a second material forming this filling is poured onto the first material layer and excess material is stripped from the surface. 8. The method according to any one of claims 1 to 4, characterized in that the cylindrical body with a Plastic is coated, that then said first layer of material over the so coated cylindrical body and placed by heat and / or pressure of the plastic through the holes or Recesses of the first material layer is pressed outwards. 9 · Method according to one of the preceding claims, 509836 / ü 73 9 characterized in that said second material forming the filler material is a Epoxy resin is " 10. The method according to any one of the preceding claims, characterized in that the first layer of material consists of copper. 11. The method according to any one of the preceding claims, characterized in that the energy beam is formed by a laser beam. 12. The method according to any one of claims 1 to 8, characterized characterized in that the first material layer is a metal and that the second material, the is used as a filler for the holes or recesses in this first layer of material, is formed by a second metal, which is more easily affected by the energy beam than that former metal. 13. The method according to claim 12, characterized in that that the energy beam is formed by an electron beam. 509836 / G739 14. Gravure cylinder, characterized in that it carries a flexible layer of a first material, in which holes or recesses are formed in a constant size and regular arrangement, that these holes or recesses with a material are filled in by means of a laser or electron beam guided over the cylinder surface is more easily displaced or evaporated than the material of the first-mentioned flexible material layer. 50 98 38/073