EP1104347A1

EP1104347A1 - Holding device for flexographic printing sleeves

Info

Publication number: EP1104347A1
Application number: EP99953547A
Authority: EP
Inventors: Helmut Busshoff
Original assignee: Rotec Hulsensysteme GmbH and Co KG
Current assignee: Rotec Hulsensysteme GmbH and Co KG
Priority date: 1998-08-21
Filing date: 1999-08-17
Publication date: 2001-06-06
Anticipated expiration: 2019-08-17
Also published as: US6796234B1; EP1104347B1; WO2000010809A1

Abstract

The invention relates to a holding device (1) for a flexographic printing sleeve (2), which comprises at least one receiving member (3) exhibiting a cylindrical side surface over which a printing sleeve can slide, said receiving member being able to rotate around its longitudinal axis and around the sleeve longitudinal axis. According to the invention, the receiving member comprises two or more shoulders (4) with differing diameters and the holding device comprises a second identical receiving member (3). Both receiving members are placed in such a way that they can rotate around the same longitudinal axis and are oriented toward each other with their small shoulders. At least one of the receiving members can be moved along said longitudinal axis in such a way that the distance between said two receiving members can be adjusted.

Description

"Holding device for flexographic printing - printing sleeves"

The invention relates to a holding device according to the preamble of claim 1.

A non-generic holding device for a printing cylinder is known from FR 1, 275.904. It has two conical mounts for the printing cylinder with the printing motif.

For the exclusively non-positive power transmission from the rotary driven conical receptacles to the pressure cylinder to be rotated, the is basically narrow

The contact surface between the cone and the cylinder is disadvantageous, so that comparatively heavy, thick-walled pressure cylinders have to be used, which allow a sufficiently large contact surface as a force transmission surface due to bevels on the two ends of the cylinder. In addition, this represents great

Wall thickness sure that the compression forces required to fix the printing cylinder between the two receptacles do not cause any deformation of the printing cylinder.

From CH 377 854 is also a non-generic tensioning device for storing rolls with paper, foils and the like. Known, in which each end of the role of a conical receptacle in the form of a clamping cone. A form fit between the sleeve-shaped roller core and the clamping cone is provided to prevent rotation.

For this purpose, either ribs and corresponding grooves have to be created on these two parts, or the tensioning cone is pressed into the material of the roll core, this roll core being permanently deformed.

The device of CH 377 854 is intended for holding rolls that can only be used once.

When transferring the construction known from CH 377 854 to the field of printing technology, the application of would be

Grooves or ribs are not possible with sleeves with thin walls. A permanent deformation of the printing sleeves by the receptacles would hinder or rule out the multiple use of the printing sleeves and would also run the risk that the surface with the printing motif would have undesired roundness.

Contrary to the teaching of FR 1, 275.904, in a special area of printing technology known as "flexographic printing", not complete, one-piece printing cylinders, each with its own printing motif, are used, but interchangeable sleeves that can be pushed onto a cylindrical receptacle made of metal .

Generic holding devices are known from DE 27 00 118 C2 or from DE 36 33 155 A1, the cylindrical receptacle made of metal extending through the sleeve over the entire length of the sleeve. The cylindrical receptacle thus represents a “permanent printing cylinder”, since it can be used with several sleeves and thus for several printing motifs. Each sleeve can have the printing motif directly, for example etched or lasered, or it can have a separate outer plate layer with the print motif.

To mount the sleeves, compressed air emerges from the inner cylindrical receptacle during flexographic printing and expands the partially pushed-on sleeve so that it can be pushed completely onto the receptacle. When the compressed air is switched off, the sleeve contracts and lies firmly against the cylindrical receptacle, so that it can be rotated together with it. The cylindrical holder consists of

Metal, which are disadvantageous in their high manufacturing costs and heavy weight which makes them difficult to handle.

In addition to the applications in the printing plants themselves, that is to say in the printing presses, many devices are provided in the processing stations which are required for the production of a printing sleeve and which also have a rotatable holder for the printing sleeve or for its pre-production stages, e.g. B. coating machines, which coat the surface of the raw casing with light- or acid-sensitive materials, so that the print motifs can later be applied to the sleeve surface by laser or etching processes. The etching or laser machines must also have such a rotatable holder for the pressure sleeve.

A major problem both for printing and in the preparatory manufacturing processes for the printing sleeves is that printing sleeves with very different outside diameters are required. In a comparatively old state of the art, very thin-walled metallic pressure sleeves were pushed onto cylindrical receptacles. The wall thickness of these sleeves had to be small to ensure the flexibility required so that the sleeves could be expanded by compressed air. The cylindrical receptacles therefore have almost the same diameter as the pressure sleeves. With different outside diameters Correspondingly, sleeves for printing motifs of different sizes had to have a large number of exposures with different diameters available.

A simplification for the user is that when using receptacles with the same diameter, sleeves with different wall thicknesses can be used, so that when using a reduced number of different receptacles, a larger number of sleeves with different outer diameters can be used. These sleeves have the necessary flexibility to be able to be expanded by compressed air despite these wall thicknesses due to the at least partial use of plastics.

However, a gradation of the outer diameter of the cylindrical receptacles in 10 mm steps is common. In view of a bandwidth of approx. 250 mm to approx. 2,000 mm for the circumferences of the sleeves, depending on the size of the print motifs, a comparatively large number of exposures must therefore also be kept with flexographic printing. This requires a very large amount of investment in the printing houses and especially in the above-mentioned companies of the preparatory manufacturing processes: while a printing house may be specialized in the processing of print motifs in a limited size range, the laser engravers and similar companies are usually in the processing of Sleeves aligned for the entire range of the sleeve circumferences mentioned.

In practice, therefore, the number of stocks to be stocked

To keep receptacles with different outside diameters small, sleeves with sometimes very large wall thicknesses are used, so that a sleeve with a large outside diameter and a correspondingly large print motif can be used on a “small” receptacle. Particularly in the case of sleeves with such a large wall thickness or with a large diameter, the considerable weight of such sleeves and, in particular, the associated cylindrical receptacles results in a considerable amount of handling. Not all companies have their own handling devices for this purpose, such as crane systems, elevators or the like, which mean a very high investment outlay. Therefore, if necessary, only sleeves with a comparatively small diameter can be processed. In addition, the set-up times when changing the receptacles are considerably shorter and therefore cheaper if this change can be made by hand, that is to say without such handling devices.

The invention has for its object to improve a generic holding device in such a way that an inexpensive holding device simplifies the handling of the receptacle when changing the receptacle, simplifies the change of sleeves and simplifies the change of sleeves with different diameters.

This object on which the invention is based is achieved by a device having the features of claim 1.

In other words, the invention proposes to use two receptacles, which hold the sleeve between them, instead of one, the receptacles each having two or more steps with different diameters.

Compared to a single, cylindrical receptacle, which extends over the entire length of the printing sleeve and as is known from flexographic printing, considerable weight savings are achieved, so that handling when changing the receptacle or the holder is simplified. In particular, such changes are required less frequently, since the receptacles allow the handling of different sleeves with different inner diameters. Compared to the use of two conical receptacles, as are known from other technical fields, axial compression forces are avoided, so that even very thin-walled sleeves can be held safely and without deformation. In addition, especially for very thin-walled sleeves, there is reliable support through the cylindrical outer surfaces: thin-walled sleeves, which may be slightly out of round at first, are securely centered after mounting on the mount by the circular, constant-diameter circumference of the step and receive one perfectly round outer contour, in the case of a raw sleeve in favor of precise machinability or, in the case of a finished printing sleeve, in favor of a precise and uniform print image.

In this way, sleeves with very different

Outside diameters are held on the same receptacle, the wall thickness of the sleeves being comparatively small since the sleeve can be pushed onto the section of the receptacle that comes as close as possible to the desired sleeve outer diameter. This has three advantages:

1. The handling of the receptacle when changing the receptacle is simplified because two receptacles are provided instead of one, so that each individual receptacle is lighter anyway, and because both receptacles together do not extend over the entire sleeve length, but each receptacle is provided only in the area of one end of the sleeve. 2. The exchange of the sleeves is simplified since the steps in the receptacles make it possible to optimally adapt the wall thickness of the sleeve to the desired outside diameter, so that thin-walled and accordingly lightweight sleeves can be provided, which accordingly are easy to close are handling. 3. The change of sleeves with different diameters is simplified in many cases, because often the receptacles do not have to be changed at all. Rather, in many cases, a different stage of the receptacle for the new sleeve, which has a different inner diameter than the sleeve previously used, can simply be used

To change the sleeves, the two receptacles can be “opened” in a manner known per se, that is to say they can be moved apart, the two receptacles subsequently being moved toward one another again to hold the sleeves. Both receptacles can be provided on a common, physically realized axis Alternatively, it can be provided that both receptacles are arranged on an ideal common rotational or longitudinal axis, for example in that both receptacles are freely rotatably supported on a base, at least one the recordings are driven by rotation.

The division of the previously one-piece, cylindrical, metallic receptacle, as well as the gradation to smaller diameters, as well as an overall length, which may be shorter than half of a previously usual receptacle, result in a considerable overall

Weight reduction of the individual parts to be handled, so that usually a crane is not required.

The mounting of the receptacle in the holding device can be made smaller and cheaper due to the lower weight of the receptacle. Fewer receptacles need to be kept in stock, since sleeves with different inner diameters can be used on the same receptacle. In addition, there is the possible omission of handling devices such as a crane or the like. The fourth advantage is therefore that the manufacturing costs for the holding device are lower and in particular the investment costs for the user as a whole are considerably lower than when using conventional holding devices.

Set-up times are reduced considerably, since sleeves with different inner diameters can be used on the same holder and the holder has to be changed less frequently. Not only the assembly time has to be considered, but also the subsequent check for concentricity and cylindricity of the mount. The operating costs are therefore also lower than when using conventional recordings

Since the receptacles do not support the sleeve over their entire length, the risk that the sleeve slips on the receptacle when the receptacle is driven can be countered by a toothing between receptacle and sleeve, such a toothing in the axial and / or radial direction - can be provided. For thin-walled sleeves

To rule out the risk of deformation, or if a toothing cannot be formed due to the wall thickness of the sleeve, it can alternatively be provided to roughen or coat the lateral surfaces of the steps in order to improve the frictional connection with the sleeves.

According to the invention, the receptacles will have a maximum of half the length of the pipe to be accommodated if both receptacles are inexpensively designed to be the same. In order to ensure that the sleeve is held securely, the section of the receptacle that extends into the sleeve must not be less than a certain minimum length, which depends, for example, on the materials used and any toothing used or the ability to rub the surface. Accordingly, the number of stages of each recording is limited. In order to be able to use the entire range from 250 mm to 2,000 mm sleeve circumference, several types of receptacles can be provided, the step diameter of which varies from type to type.

In order to make changing the receptacles even less frequently and to keep the same receptacles as often as possible, an additional component can be provided in the holding device in order to make the sleeve quasi two-layered: namely an inner “support sleeve” on which the actual sleeve is to be processed or which has the printing surface in the manner known per se, which is typical for flexographic printing. The support sleeve thus represents the intermediate stages which the receptacle does not have due to the above-mentioned restrictions.

The support sleeve can advantageously be stiff, lightweight and hardly stretchable, e.g. B. from a material such as foamed aluminum or the like. Made of fiber composite materials or from a sandwich construction, while the actual sleeve can consist of a more flexible (and possibly heavier) material, which enables the typical flexographic printing assembly. This assembly can either be on the support sleeve, e.g. initially be provided for processing the raw sleeve or else on printing presses, which contain the stepped receptacles and one

Have support sleeve. The assembly can also be provided on printing presses which have the conventional, one-piece receptacles.

For mounting the sleeve, the support sleeve has air guide channels, so that the compressed air can be conveyed through the support sleeve by a compressed air generator and enables the outer sleeve to be pushed on, as is typical for flexographic printing. The "overall sleeve" thus created, consisting of the actual sleeve and the support sleeve, can now be handled together in a simple manner and held between the receptacles. The support sleeve therefore replaces the comparatively heavier and more expensive flexographic printing cylinder. Even if the sleeves are not drawn directly onto the receptacles, but even if additional support sleeves are always used, there are considerable handling advantages.

Because several support sleeves can be designed with different outside diameters, the entire device can be finely graded, in which the receptacles are designed with a few steps and a fine adjustment to almost any outside diameter of the pressure sleeves is possible by using corresponding support sleeves. In addition, the support sleeve reinforces sleeves with a small wall thickness, so that a more stable overall sleeve is created and the damage-free handling of the sleeve is facilitated. In particular, this enables attachment to the receptacles, in which non-reinforced sleeves could be damaged: e.g. B. if a toothing is provided and a very thin-walled sleeve is to be used, or if the sleeve is not stretched as is typical for flexographic printing and is relaxed on the receptacle, but if it is to be mechanically firmly clamped on the receptacle.

The use of the support sleeves considerably simplifies and shortens the handling of the sleeves: Instead of lifting the conventional pressure cylinder with a crane into a special assembly device and opening the sleeve there, the support sleeve can be placed vertically on the floor and connected to a compressed air supply using a quick-release fastener. so that the sleeve can then be “put over.” And instead of inserting the conventional printing cylinder provided with the sleeve into the processing or printing machine and adjusting concentricity and cylindricity, the “total sleeves” created from the sleeve and support sleeve can be mechanically inserted between the receptacles tight without additional alignments. Overall, as the time for a tube change to ^_1/5 or ¹ / _10th of the conventional time required can be reduced.

To make handling easier and as small as possible

To enable weights of the sleeves and support sleeves, these can have the smallest possible wall thicknesses. In order to exclude deformations and damage both during processing and later in printing, the sleeves or support sleeves can have stiffening elements in their inner cavity: z. B. a core of fiber composites or lightweight material such as foamed aluminum, or extruded profiles such. B. made of aluminum with, for example, star-shaped, cruciform or similar, or z. B. cross-section formed as a polygonal tube.

An embodiment of the invention is explained in more detail below with reference to the purely schematic drawing.

A cross section through a holding device 1, which serves to hold sleeves 2, is shown purely schematically, the sleeves 2 serving as “pressure sleeves” and this designation relating to the use of the sleeves 2 in the printing industry. The sleeve 2 can be ready for use However, it can also be a “raw sleeve” which is subjected to production steps in order to create a ready-to-use pressure sleeve.

The sleeve 2 is pushed at its two front ends onto a receptacle 3, each of which has several stages

4 with different diameters and with cylindrical outer surfaces. Purely by way of example, 4 chamfers are provided on some stages, which make it easier to push the sleeves onto the receptacles 3, but the receptacles 3 can also be designed without such chamfers or with chamfers on all stages 4. Both recordings 3 are rotatably mounted. The receptacle 3 shown on the left is held in a indicated base, which represents a non-driven abutment. On the receptacle 3 shown on the right, a stub shaft is indicated, which leads to a machine base, not shown, which contains a drive unit for this right receptacle 3, so that the sleeve 2 can be set in rotation. In a departure from this embodiment, both receptacles 3 can also be driven in rotation synchronously. The right-hand receptacle 3 can be axially displaced with the shaft, the stub shaft of which is indicated, within a slide bearing of the machine base, not shown, or, if necessary, displaced together with the machine base, so as to insert the sleeves 2 between the receptacles 3 or out of the receptacle - Men 3 to remove, as well as to adjust the distance between the receptacles 3 to different lengths of sleeves 2. The axial displacement of the receptacle 3 can be done pneumatically, for example, since the sleeves are anyway installed using compressed air, as is typical for flexographic printing.

A rotationally secure mounting of the sleeve 2 on the receptacle 3 is ensured by toothing elements 5 which extend into a support sleeve 6 carrying the sleeve 2. In the exemplary embodiment shown, the toothing elements 5 are shown purely schematically and purely by way of example as pins which run parallel to the axis and are provided on the receptacles 3. The overall sleeve formed from the actual sleeve 2 and from the support sleeve 6 has corresponding bores in the support sleeve 6 as corresponding toothing elements in order to receive the pins. Deviating from the purely schematic representation, the wall thicknesses of the sleeve and support sleeve can be very different. For example, a thin-walled sleeve can be fitted onto a thick-walled support sleeve, the larger wall thickness of the support sleeve possibly making it possible to design toothing elements, which may not be possible in the sleeve due to their small wall thickness.

The support sleeve 6 has air guide channels, not shown, via which compressed air can be passed to the outer surface of the support sleeve 6, so that the sleeve 2 can be fastened to the support sleeve 6 in a manner known per se to form the overall sleeve. It can be provided regardless of the material of the support sleeve 6, the air ducts through pressure-resistant hoses or tubes, e.g. of metal or plastic to form, which can be arranged in the wall with thick-walled support sleeves 6, e.g. overmoulded, foamed or laminated, and fixed in the case of thin-walled support sleeves 6 on the inside of the wall, e.g. can be screwed and / or glued. Through holes can each lead the air from the air duct to the outer surface of the support sleeve 6.

The sleeve 2 is mounted on the support sleeve 6 in a preparation station before the entire sleeve formed from the sleeve 2 and the support sleeve 6 is then held in the device 1. Since the support sleeve 6 can consist of a lightweight fiber composite material, a foamed metal material or the like, the lightweight configuration and thus the simple, crane-free handling of the overall sleeve mentioned is made possible.

The device 1 shown can be provided in the area of a processing station for producing a pressure sleeve from the sleeve 2, the sleeve 2 in this case representing a raw sleeve. Possibly. However, the printing unit itself can also be equipped with such a device 1 instead of the conventional printing cylinder for receiving the sleeve 2, in which case the sleeve 2 would represent a printing sleeve. The support sleeve 6 shown serves as a type of adapter for receiving the actual sleeve 2, which has the printed motif. Adapters of this type can be dispensed with if the receptacles have 3 stages 4 with the diameters suitable for the desired sleeves 2 and if the sleeve is secure

Stops on the recording 3, e.g. by a suitable toothing (form fit) or by a stability that allows a firm, non-rotatable clamping (frictional connection) of the sleeve 2 between the receptacles 3. This stability can with plastic sleeves z. B. can be achieved by fiber reinforcements. The

Non-positive connection can also be improved by the friction-friendly design of the interacting surfaces on the sleeve and receptacle.

Depending on the usual requirement profile, different receptacles with different step diameters can therefore be provided for the individual users. Furthermore, as an alternative to the use of the support sleeve 6 shown, it can be provided that the user may replace the comparatively small and light, easy-to-handle receptacles 3 of the device 1 to use sleeves 2 with different inner diameters, so that the receptacles 3 can be used in each case , which have a step 4 with the outer diameter which is suitable for the inner diameter of the sleeve 2 or support sleeve 6 to be used.

If no support sleeves are to be used, air channels can be provided in the receptacles 3 in a similar manner to that of the known, comparatively large ones

Cylinders in the field of flexographic printing are known: outlet openings for the air are provided on the lateral surfaces of the steps in order to widen the sleeves 2 and enable them to be pushed directly onto the receptacles 3. Outlet openings on unused steps can be blocked or closed using appropriate valves or plugs

Claims

Claims:

1. Holding device for a flexographic printing sleeve, wherein the holding device has at least one receptacle with a cylindrical outer surface onto which a

Pressure sleeve can be pushed on, the receptacle being rotatable about its and the longitudinal axis of the sleeve, characterized in that the receptacle (3) has two or more steps (4) with different diameters and that a second, similar receptacle (3) is provided, wherein both receptacles (3) are arranged and rotatable on the same longitudinal axis, and wherein the receptacles (3) with their smallest steps (4) are directed towards one another, and at least one receptacle (3) is adjustable along the longitudinal axis, that a different distance between the two receptacles (3) can be set from one another.

2. Device according to claim 1, characterized in that the receptacle (3) has toothing elements (5) in the radial and / or axial direction which cooperate with corresponding toothing elements associated with the sleeves (2).

3. Device according to claim 1 or 2, characterized in that for receiving the sleeve (2) an inner

Support sleeve (6) is provided, the support sleeve (6) having air guide channels which lead from the end face or from the inner surface of the support sleeve (6) to its outer surface. Device according to one of the preceding claims, characterized in that the sleeve (2) or the support sleeve (6) has stiffening elements in its inner cavity.