EP1274589B1 - Jacket assembly for an impression cylinder - Google Patents

Abstract

The invention relates to a jacket assembly for an impression cylinder, comprising a rigid inner jacket (20, 22) that can be fixated on the impression cylinder, and a thin-walled printing form jacket (10) that can be axially slipped onto the inner jacket and that is provided with the printing surface (16). The inner jacket (22) is provided with a compressible layer (24) on its outer periphery and the printing form jacket (10) is designed as a flexible film jacket (12) with a wall thickness of less than 0.5 mm on which the printing surface (16) is fastened. The inventive design allows for lower production, storage and replacement costs in the production of printing forms as compared to conventional jacket assemblies.

Description

The invention relates to a sleeve arrangement for a printing cylinder, consisting of a fixable on a printing cylinder, rigid inner sleeve and one axially on the inner sleeve slide-on thin-walled printing form sleeve with the printing Surface.

In the printing industry, printing forms or printing plates are used mounted on the steel printing cylinders of printing machines. The printing surfaces of the printing blocks are special with so-called flexographic printing, they are generally frustoconical Printing dots are present, which are characterized by the process during printing widening the occurring forces elastically (so-called "dot gain"). To avoid this undesirable effect, the Printing clichés not directly attached to the printing cylinders, it becomes an elastic or compressible intermediate layer provided that become elastic during the printing process deformed and thus the dot gain, which leads to loss of quality of pressure would decrease.

Conventionally, the manufacture or assembly of a Printing form, which is produced by means of a printing plate, follows. On a rigid plastic support sleeve or metal becomes a double-sided, compressible Foam tape applied, on which the pressure plate is fixed. The assembly of the printing form thus produced on the printing cylinder takes place either directly or via an intermediary Adapter sleeve using a compressed air from the Air cushion built up inside the pressure cylinder.

When using a photopolymer plate, it is placed on a stiff one Support sleeve applied a layer of glue on which a compressible Foam tape is wound spirally. Subsequently the foam tape is sanded to the correct external dimension and provided with an adhesive layer. The photo polymer layer is then applied and by the action of heat both at the joint and on the surface fused, creating a seamless printing form becomes. The printing form thus formed is in the same way as described above, fixed on the printing cylinder.

The known methods have the following disadvantages.

The conventional manufacture of printing forms using thick-walled sleeves requires a lot of material as well a considerable amount of work in production. This in turn leads to a large logistical effort during transport and the storage of the printing forms. In the event of damage or errors, the high production costs lead to considerable Replenishment lead times and thus an increased risk for frequently occurring print jobs with a tight schedule Frame.

Conventional printing forms have a lot of weight finally a considerable sensitivity to the effects of shock.

DE 695 08 184 describes a sleeve arrangement for one Printing cylinder disclosed, which consists of a rigid inner sleeve (Intermediate sleeve 12) and one axially slidable onto the inner sleeve thin-walled printing form sleeve (thin jacket 14) with the printing surface (18). This arrangement, so in particular the arrangement of the intermediate sleeves should Serve purpose, a reduced supply of metallic Keep support cylinders in stock. This prior arrangement consists of two matching rigid sleeves, the outer jacket forming a unit with the printing block.

The use of thin support sleeves can solve the problems above do not eliminate, as to ensure good print quality a compressible liner below the printing cliché is necessary and therefore between the support sleeve and printing block a foam layer can be assembled with great effort got to.

EP-A-0 313 511 discloses a sleeve assembly which does the same The preamble of claim 1 corresponds to a rigid Inner sleeve with a four-layer structure is disclosed on the a thin-walled printing form sleeve (printing plate) is pushed on is. Furthermore, EP-A-0 727 326 and EP-A-0 452 disclose 184 one-piece printing sleeves, which on a printing cylinder be put on the outside Printing block is attached. The cliché is firmer Part of the sleeve. Especially in EP-A-0 727 326 the printing sleeve is fixed with a cliché with the one underneath provided layer connected. According to EP-A-0 452 184 the cliché also firmly with the one below Layer connected.

The object of the invention is based on the prior art based on the production, storage and replacement costs to reduce in printing form production.

According to the invention, this object is achieved in the claims listed features solved.

The main advantages of the invention can be seen in that the printing form produced according to the invention due to the very small wall thickness requires less material, which reduces the manufacturing costs. Because of the flexibility the film-like support sleeve, it is possible to conventionally provided between the support sleeve and printing plate to dispense with compressible foam layer, which makes the with the production of this foam layer very considerable work can be omitted. The compressibility of the overall system is inventively effected in that on the below the adapter sleeve provided the compressible Layer is firmly in place and due to the flexibility the film sleeve acts through it.

The invention makes it possible for a Number of foam adapter sleeves with different parameters (Diameter, elasticity and thickness of the compressible Layer) are kept in stock and only those without compressible Layer-made printing form must be mounted.

In addition, the lower weight of the invention Printing forms that the transport and storage of the Printing forms is less expensive.

The combination of features according to the invention advantageously achieves a material saving in that the avoidance the compressible layer required for the dot gain Part of the molded part is (such as in of DE 695 08 184 cited above is the case) and therefore the elastic covering is part of the reusable inner sleeve. Due to the extreme flexibility of the film sleeve, the Compressibility of the intermediate layer on the printing surface transfer. The actual printing form is at Invention only from the flexible film sleeve with the attached printing surface (cliché), whereby due to the high flexibility (the extremely thin walls) the printing form sleeve is very strongly deformable and thereby for Storage can be compressed like an elypse. hereby do not arise in this compared to the conventional Scope deformable sleeve assemblies significant storage advantages (less space, less weight). The high flexibility also enables a simplified Transport of the printing form sleeves according to the invention, since smaller Packaging can be chosen.

Fig. 1:

eine erfindungsgemäße Hülsenanordnung bestehend aus einer Folienhülse nebst aufgebrachtem Druckklischee in Seitenansicht;

Fig. 2:

eine Seitenansicht einer Hülsenanordnung mit Schaumbeschichtung.

The invention is explained in more detail below with reference to the accompanying drawings. It shows:

Fig. 1:

a sleeve assembly according to the invention consisting of a film sleeve and applied printing block in side view;

Fig. 2:

a side view of a sleeve assembly with foam coating.

1 shows a printing form sleeve according to the invention, which consists of a film sleeve 12 , an adhesive layer 14 applied thereon and a printing block 16 . For bes seren recognizability, the axial extent of the adhesive layer 14 and the printing plate 16 is shown shorter, while it is generally as long as the film sleeve 12th The film sleeve 12 has a wall thickness of at most 0.5 mm, preferably between 0.15 mm and 0.35 mm and particularly preferably between 0.25 mm and 0.30 mm. It is preferably made of a plastic, but could also be made of metal or other materials, provided that it is only sufficiently flexible, ie has a sufficiently low rigidity. Polyesters are particularly suitable as the sleeve material. The film sleeve 12 can be provided on the outside with axial micro-grooves 18 for the removal of air between the film sleeve and the printing plate in the production of the printing form using photopolymer films. These micro grooves 18 are only indicated in a small area in FIG. 1, they are actually provided on the entire outside of the film sleeve 12 .

mindestens eine Vliesmatte, vorzugsweise aus Polyestervlies, wird um einen Formgebungszylinder und mittels eines Harzes, vorzugsweise Vinylesterharz, getränkt;

je nach Art des verwendeten Harzes wird mittels Wärme oder UV-Licht das Harz ausgehärtet;

eine das Druckklischee 16 bildende Fotopolymerfolie wird um die Folienhülse 12 gelegt und das System Folienhülse 12 und Druckklischee 16 unter Unterdruck oder Vakuum gesetzt, um die Luft zwischen der Folienhülse 12 und dem Druckklischee 16 über die gebildeten Mikrorillen 18 abzuleiten;

das Druckklischee 16 und die Folienhülse 12 werden unter Einwirkung erhöhter Temperatur miteinander verbacken, wobei die Stoßstelle der Fotopolymerfolie zur Bildung eines nahtlosen Fotopolymersleeves verschmolzen wird.

A method according to the invention for producing a printing form sleeve using the film sleeve described above comprises the following steps:

at least one fleece mat, preferably made of polyester fleece, is impregnated around a shaping cylinder and by means of a resin, preferably vinyl ester resin;

depending on the type of resin used, the resin is cured by means of heat or UV light;

a photopolymer film forming the printing plate 16 is placed around the film sleeve 12 and the system of film sleeve 12 and printing plate 16 is placed under reduced pressure or vacuum in order to discharge the air between the film sleeve 12 and the printing plate 16 via the micro grooves 18 formed;

the printing block 16 and the film sleeve 12 are baked together under the action of elevated temperature, the joint of the photopolymer film being fused to form a seamless photopolymer sleeve.

Then there is a printing form sleeve with very little Wall thickness, low rigidity and light weight Available, which are mounted on a foam adapter sleeve can.

For this purpose, the foam adapter sleeve 20 shown in FIG. 2 is axially pushed onto a pressure cylinder, not shown, with air outlet holes on the outer surface, forming an air cushion between the pressure cylinder and foam adapter sleeve 20 . The foam adapter sleeve 20 comprises a supporting layer 22 , on the outside of which a compressible layer 24 is applied. The supporting layer 22 is usually made of plastic and has a thickness of 3 to 70 mm. The elastic layer 24 firmly attached to the supporting layer 22 is preferably a foam layer, especially consisting of PU foam, and has a thickness of 0.5 mm to 3 mm.

The foam adapter sleeve 20 has through bores 26 which lead from the inside of the load-bearing layer 22 through the elastic layer 24 and ensure that compressed air from the inside of the pressure cylinder can get to the outside of the foam adapter sleeve 20 when pushed onto the (not shown) pressure cylinder ,

The printing form sleeve 10 is then axially slid on using an air cushion that forms between the elastic layer 24 of the intermediate sleeve 20 and the film sleeve 12 .

The printing form sleeve is then aligned and the air supply is shut off, which completes the assembly of the printing form sleeve 10 .

In the flexographic printing process, the printing cliché can change over the thin and flexible film sleeve elastic on the compressible Support layer of the foam adapter sleeve, creating a high print quality is ensured. After finishing the Printing process can remove the printing form sleeve and can be stored temporarily without great effort.

Claims (11)

1. A printing cylinder sleeve assembly comprising a rigid inner sleeve (20, 22) affixable to a printing cylinder and a thin-walled plate sleeve (10) including the image surface (16) for axial mounting on said inner sleeve (20), characterized in that said inner sleeve (22) is provided on the outside with a compressible layer (24) and said plate sleeve (10) is configured as a flexible film sleeve (12) with a wall thickness less than 0.5 mm to which said image surface (16) is secured.
2. The sleeve assembly as set forth in claim 1, characterized in that said inner sleeve (20) comprises radial air passages (26) circumferentially distributed for the passage of compressed air from an inside printing cylinder to the outside of said inner sleeve (20).
3. The sleeve assembly as set forth in claim 1, characterized in that the wall thickness of said film sleeve (12) is in the range 0.15 mm to 0.35 mm.
4. The sleeve assembly as set forth in claim 1, characterized in that said film sleeve (12) is made of natural fiber or plastics, more particularly of polyester.
5. The sleeve assembly as set forth in claim 1, characterized in that said film sleeve (12) is provided on the outside with microgrooves (18) oriented axially.
6. The sleeve assembly as set forth in claim 1, characterized in that said compressible layer (24) of said foamed adapter sleeve (20) is a foamed layer, preferably of foamed PU.
7. The sleeve assembly as set forth in claim 6, characterized in that said compressible layer (24) is 0.5 mm to 3 mm thick.
8. A method for producing a plate sleeve in making use of said film sleeve (12) as set forth in any of the claims 1 to 7 as well as a plate comprising the steps:

   (a) wrapping a molding cylinder with at least one non-woven mat, preferably of polyester non-woven and saturating said mat with a resin;

   (b) curing said resin;

   (c) wrapping said thus formed film sleeve (12) with stickyback tape;

   (d) securing said image surface to said stickyback tape.
9. A method for producing a plate sleeve in making use of said film sleeve (12) as set forth in any of the claims 1 to 7 as well as a photopolymer plate comprising the steps:

   (a) wrapping a molding cylinder with a non-woven mat and saturating said mat with a resin:

   (b) curing said resin;

   (c) grinding said molded film sleeve (12) on the outside axially to form microgrooves (18);

   (d) wrapping said film sleeve (12) with the photopolymer plate and evacuating the system to remove any air inclusions;

   (e) fusing both ends of said photopolymer plate at a high temperature to form a seamless plate.
10. The method as set forth in claim 8 or 9, characterized in that said film sleeve (12) is formed alternatively by said injection molding by injecting said fiber/resin blend on a molding cylinder and subsequently curing said blend.
11. A method for affixing a plate sleeve on a printing cylinder in making use of said sleeve assembly as set forth in claim 1 comprising the steps:

    (a) Providing a printing cylinder circumferentially with air outlet holes and ejecting compressed air through said air outlet holes;

    (b) axially mounting said inner sleeve (20) in making use of said air cushion forming between printing cylinder and inner sleeve (20);

    (c) axially mounting a plate sleeve (10) in making use of said air cushion forming between inner sleeve (20) and plate sleeve 10;

    (d) terminating compressed air ejection following registration of said plate sleeve (10).

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