EP0812686A2 - Method and device for mounting a flat printing plate to a cantilevered plate cylinder of a printing press - Google Patents

Abstract

The method involves bending the printing plate (2) in a cylindrical shape. The hollow pipe (12) in which the bent plate (6) is inserted, has an internal diameter greater than the external diameter of the printing plate. The pipe and plate are slid onto the cylinder over an arbour (16) which is concentric to the press cylinder. The arbour has an outer diameter which is smaller than the inner diameter of the pipe and is larger than the press cylinder outer diameter. A clamping mechanism is then actuated to fix the plate on the press cylinder, after which the pipe is removed. The ends of the plate can be bent over, and there can be a recess (20) in the arbour corresponding with the gap in the plate, whose ends slide through the recess. A datum mark can be provided on the pipe, so as to align the gap in the plate with one (3) in the press cylinder.

Description

The present invention relates to a method and a device for applying a flat printing plate to a cantilevered plate cylinder of a printing press, in particular an offset web-fed printing press.

In order to apply a conventional flat printing plate to the plate cylinder body of a rotary printing press, the plate must be wound around the plate cylinder body and fastened at its ends by a tensioning device. In the printing machines of the prior art with a plate cylinder which is rotatably mounted in two bearings arranged in the left and the right machine side wall, the application of a flat printing plate is usually carried out by inserting a first bent end of the printing plate into a first groove of the clamping device Rotating the plate cylinder until the second end of the pressure plate can be inserted into a second groove of the tensioner, and then by actuating the tensioner, the pressure plate being tensioned and securely attached to the peripheral surface of the plate cylinder body.

In printing presses with a cantilevered plate cylinder - a plate cylinder which is rotatably supported at only one end in only one side wall of the printing machine when changing plates - it is also possible to apply a conventional flat printing plate to the plate cylinder by pressing it from the side onto the Platter cylinder body is pushed on, in such a way that the bent ends of the pressure plate are received and guided in an axially extending groove or recess formed in the plate cylinder body.

A method for sliding a conventional printing plate onto a flying plate cylinder body laterally is e.g. B. is described in GB 2 286 365. When applying a flat pressure plate according to that described in GB 2 286 365 However, the process shows the problem that it is difficult to keep the flat printing plate in a cylindrical shape while maintaining the concentricity with the plate cylinder. In addition, the inherent forces inherent in the resilient plate material (usually aluminum), which cause the pressure plate to tend to remain in its original flat condition, cause friction between the plate material and the plate cylinder body, which increases the forces that must be applied to the plate to be pushed onto the plate cylinder body, thus increasing the risk of damage to the plate. Such damage can e.g. B. result in changes in the length of the flat plate or the geometry of the curved plate, which significantly affects the quality of the printed product.

It is an object of the present invention to provide a method and an apparatus for applying a flat printing plate to a cantilevered plate cylinder body of a rotary printing press, in particular an offset web-fed rotary printing press, which enable the plate to be applied precisely and easily and which furthermore reduce the risk of Prevent damage to the plate by changing the geometry in the curved state and the length in the flat state, etc. during application.

According to the present invention, a method of applying a planar printing plate to a flying plate cylinder of a printing machine comprises the following steps: the printing plate is first brought into a substantially cylindrical shape, preferably by hand, and then into a hollow tube with an inside diameter that is somewhat larger larger than the outer diameter of the plate cylinder body is inserted. The tube with the pressure plate is then pushed onto the plate cylinder body via a mandrel, the mandrel being arranged concentrically with the plate cylinder core and having an outside diameter which is smaller than the inside diameter of the tube and larger than the outside diameter of the plate cylinder body. The pressure plate is then clamped onto the cylinder by actuating a plate clamping device and the tube is pulled down from the plate cylinder.

According to a further embodiment of the present invention, the ends of the pressure plate are bent before the pressure plate is inserted into the tube, the mandrel having a recess in which the plate ends can move freely when the tube with the pressure plate is pushed onto the plate cylinder body.

According to a further exemplary embodiment of the invention, the gap in the printing plate is aligned with the gap of the plate cylinder body by means of an identifier or mark on the tube.

According to a further embodiment of the invention, the mandrel has a conical, tapering part in order to facilitate the insertion and guiding of the tube containing the pressure plate when it is moved onto the plate cylinder body.

According to a further exemplary embodiment of the invention, air passage openings are provided in the circumferential surface of the mandrel in order to create an air bed which additionally facilitates the application of the tube and the pressure plate to the plate cylinder body.

According to a further embodiment of the invention, the circumferential surface of the mandrel has a low coefficient of friction with respect to the material of the pressure plate.

In a further embodiment of the invention, the outer diameter of the mandrel and the inner diameter of the tube are selected so that when the tube with the pressure plate is pushed over the mandrel, the pressure plate is pressed into a circular cross section, the inner diameter of which is somewhat larger than the outer diameter of the plate cylinder body.

According to a further embodiment of the invention, air passage openings are provided in the plate cylinder body, through which an air bed is created, on which the tube with the pressure plate is moved over the plate cylinder body.

According to a further embodiment of the invention, the mandrel is permanently attached to the plate cylinder body. According to another embodiment of the invention, the mandrel is removed from the plate cylinder body during operation of the printing press.

In a further embodiment according to the invention, the mandrel is mechanically or pneumatically expandable and is stretched in order to press the pressure plate against the inner surface of the tube after the front end of the tube with the plate has been moved over the mandrel.

According to a further embodiment of the invention, when the pressure plate is removed from the plate cylinder body, the tube is pushed over the plate cylinder body, the tensioning mechanism is actuated to release the ends of the pressure plate, and the tube with the pressure plate located therein is moved down from the plate cylinder body.

According to a further exemplary embodiment of the invention, the compressed air is switched on when the tube with the pressure plate is removed from the plate cylinder body.

According to a last embodiment of the invention, the mandrel has an arrangement of radially extending nozzles, through which an air cushion is formed, which forces the pressure plate against the inner surface of the tube when the tube with the pressure plate is pushed over the plate cylinder body.

Further advantages and features of the present invention are explained in more detail in the following description of preferred exemplary embodiments in conjunction with the accompanying drawings explained below:

Fig. 1

eine schematische Ansicht eines hohlen Rohres mit einer herkömmlichen Druckplatte, die aufgebracht wird, indem das Rohr zusammen mit der Druckplatte gemäß vorliegender Erfindung seitlich über einen Spanndorn auf den Plattenzylinderkörper geschoben wird;

Fig. 2

ein schematischer Querschnitt eines hohlen Rohres mit einer Druckplatte, während beide über den Spanndorn auf den Körper eines in einer Seitenwand der Druckmaschine fliegend gelagerten Plattenzylinders bewegt werden;

Fig. 3

ein Querschnitt eines dehnbaren Spanndorns innerhalb eines hohlen Rohres mit der Druckplatte; und

Fig. 4

ein weiteres Ausführungsbeispiel eines Spanndorns, der mit einer Anzahl Düsen versehen ist.

Show it

Fig. 1

is a schematic view of a hollow tube with a conventional pressure plate, which is applied by pushing the tube together with the pressure plate according to the present invention laterally over a mandrel on the plate cylinder body;

Fig. 2

a schematic cross section of a hollow tube with a pressure plate, while both are moved over the mandrel on the body of a plate cylinder mounted in a side wall of the printing machine;

Fig. 3

a cross section of an expandable mandrel within a hollow tube with the pressure plate; and

Fig. 4

a further embodiment of a mandrel, which is provided with a number of nozzles.

As shown in FIGS. 1 and 2, a plate cylinder body 2 of a rotary printing press, in particular an offset web-fed rotary printing press, is overhung in a side wall 4a of the printing press in order to enable the printing plate 6 to be replaced while the printing press is at a standstill. The printing plate 6 is a generally available flat offset printing plate which has first and second ends 8a, 8b which are usually bent in a known plate bending device before the plate is applied to the plate cylinder body 2. As is known from the prior art, the ends 8a and 8b are each received in grooves of a known tensioning device 10, which is arranged in the plate cylinder body 2, as is shown schematically in FIG. 3. Such a facility is e.g. B. from US 5,284,093.

Teflon", das einen niedrigen Reibungskoeffizienten, im besonderen bezüglich des Materials der Druckplatte 6 aufweist. Folglich kann die Druckplatte 6 in dem Rohr 12 mit Leichtigkeit bewegt werden, so daß die Gefahr einer Beschädigung der bebilderten Oberfläche der Druckplatte 6 verringert ist.In order to apply the pressure plate 6 to the plate cylinder body 2, the pressure plate 6 is preferably rolled up loosely by hand so that it assumes an essentially cylindrical shape, as shown in FIG. 1. The pressure plate 6 is then inserted into a hollow tube 12 having an inner diameter d that is slightly larger than the outer diameter of the plate cylinder body 2. The tube 12 is preferably made of a rigid material, e.g. B. plastic or metal, but it can also be formed from an elastic or partially elastic material. In the preferred embodiment of the invention, the inner surface of the tube 12 consists, for example, of

Teflon ", which has a low coefficient of friction, particularly with regard to the material of the pressure plate 6. As a result, the pressure plate 6 can be moved in the tube 12 with ease, so that the risk of damage to the imaged surface of the pressure plate 6 is reduced.

Teflon" bestehen, das einen niedrigen Reibungskoeffizienten im besonderen bezüglich des Materials der Druckplatte 6 aufweist. Außerdem kann das vordere Ende des Rohres 12, welches zuerst auf den Plattenzylinderkörper 2 bewegt wird, einen konischen, sich verjüngenden Abschnitt mit einem größeren Durchmesser als dem Durchmesser d des hinteren Endes des Rohres 12 aufweisen. Wie in den Figuren 1 und 3 ersichtlich ist, weist der Spanndorn 16 vorzugsweise eine Aussparung 20 aus, die eine freie Bewegung der abgekanteten Enden 8a, 8b der Druckplatte 6 erlaubt, wenn diese seitlich auf den Plattenzylinderkörper 2 aufgebracht wird.At the free end 14 of the plate cylinder body 2, a mandrel 16 is mounted coaxially with the plate cylinder body 2, as shown in Figures 1 and 2. The mandrel 16 can be attached to the plate cylinder body 2 either permanently or in an easily removable manner at the free end 14 of the plate cylinder body 2. As shown in FIG. 2, the mandrel 16 has a peripheral surface 18 which is somewhat larger than the outer diameter of the plate cylinder body 2, but somewhat smaller than the inner diameter d of the tube 12. The peripheral surface 18 of the mandrel 16 can be somewhat conical and preferably also made of a material such. B.

Teflon ", which has a low coefficient of friction, particularly with regard to the material of the pressure plate 6. In addition, the front end of the tube 12, which is first moved onto the plate cylinder body 2, can have a conical, tapered section with a larger diameter than the diameter d of the rear end of the tube 12. As can be seen in Figures 1 and 3, the mandrel 16 preferably has a recess 20 which allows free movement of the bent ends 8a, 8b of the pressure plate 6 when it is laterally on the plate cylinder body 2 is applied.

To apply the tube 12 with the pressure plate 6 to the plate cylinder body 2, the tube 2 is arranged concentrically with respect to the mandrel 16 and then the tube 12 containing the pressure plate 6 is moved from the side over the mandrel 16 and onto the plate cylinder body 2, the mandrel 16 the pressure plate 6 against the Presses the inner surface of the tube 12 so that the pressure plate 6 assumes a circular shape which essentially corresponds to the round shape of the plate cylinder body 2. Since the pressure plate 6 fitted into the space formed between the inner surface of the tube 12 and the outer circumferential surface of the mandrel 16 is preferably in a tensioned state, this undergoes permanent, uniform deformation, so that the pressure plate 6 also passes after passing through the mandrel 16 keeps circular shape.

After the tube 12 with the pressure plate 6 has been moved completely over the mandrel 16 and the pressure plate is on the plate cylinder body 2 in its desired position, the clamping device 10 is actuated and the pressure plate is fastened so that it sits securely on the plate cylinder body 2. The tube 12 is then removed laterally from the plate cylinder and the printing press can work.

When the pressure plate 6 is to be removed from the plate cylinder body 2, the tube 12 is moved from the side over the plate cylinder body 2, the tensioning device 10 is actuated to release the ends 8a, 8b of the pressure plate 6, and then the tube 12 together with the pressure plate 6 laterally moved down from the plate cylinder body 2. Because of the elastic forces remaining in the pressure plate 6, its outer surface contacts the inner surface of the tube 12 while it is being moved down by the plate cylinder body 2. In order to further reduce the risk of damage to the imaged surface of the printing plate, the tube 12 for removing the printing plate 6 can have a larger inner diameter d than the tube 12 which is used for the application of the printing plate 6.

In a further exemplary embodiment of the invention shown in FIG. 2, the mandrel 16 can have a tapering part 22, which facilitates the application of the tube 12 with the loosely rolled-up pressure plate 6 to the mandrel 16. The tapered part 22 has a diameter that increases in the direction of the plate cylinder body 2. To reduce the friction between the pressure plate 6 and the peripheral surface 18 of the mandrel 16 can in the Circumferential surface 18 of the mandrel 16 can also be provided with air nozzles or air passage openings 24, to which compressed air is supplied from a compressed air source 26, an air bed being created for the purpose of attaching the tube 12 with the pressure plate 6 to the plate cylinder body 2.

According to a further exemplary embodiment of the invention, air passage openings or air nozzles 28 can also be provided in the peripheral surface of the plate cylinder body 2, which are connected to the same compressed air source 26. The blown air or compressed air supplied to the air passage openings 24 and / or the air passage openings 28 is preferably controlled by a valve 30 which, for. B. can in turn be controlled by the central control unit 32 of the printing press or manually. The compressed air supplied to the air passage openings 24, 28 is preferably switched on during the application and / or removal of the pressure plate 6 to and from the plate cylinder body 2, as already described above, an air bed being formed for this purpose.

As shown in Fig. 1, an identifier or indexing device 34, preferably a mark, can also be provided on the outer surface of the tube 12 in order to better fit the gap in the plate cylinder body 2 to that formed in the pressure plate 6 between the two ends 8a, 8b Align gap or hem.

In a further embodiment of the invention shown in Fig. 3, the mandrel 16 is stretchable, so that its diameter either mechanically or by compressed air, the z. B. is supplied by the compressed air source 26 and the valve 30, can be enlarged or reduced. In this exemplary embodiment, the mandrel 16 has segments 150 which are supported on radially extending support elements 152. The support elements 152 are arranged on the plate cylinder body 2 and allow the segments 150 to move radially with respect to the center of the plate cylinder body 2, as indicated by the broken lines in FIG. 3. In the preferred embodiment of the invention, the segments 150 of the expandable mandrel 16 have a circumferential curvature 154 that corresponds to the curvature of the inner surface corresponds to the tube 12. As shown in FIG. 3, the support members 152 can be received in respective holes 153 formed in the segments 150, and the compressed air is supplied through air passage openings 155 located in the members 152, which act on the members 150 in such a way that that the elements 150 are forcibly moved away from the center of the mandrel 16.

In this embodiment of the invention, the segments 150 are first in their inner position (see the solid lines in Fig. 3), and after the end of the tube 12 with the pressure plate 6 has been moved over the mandrel 16, the compressed air is switched on and the segments 150 are pressed by the compressed air against the inner surface of the tube 12, the pressure plate 6 being pressed against the inner surface of the tube 12 until the corresponding part of the pressure plate 6 assumes a circular shape. The tube 12 is then pushed laterally onto the plate cylinder body 2, as already described above. To remove the pressure plate 6, or the tube 12, the compressed air for expanding the mandrel 16 is switched off and the mandrel 16 by elastic means, for. B. contracted by retaining springs (not shown) or supplying suction air instead of compressed air.

In a further exemplary embodiment of the invention shown in FIG. 4, the mandrel 16 can have a series of radially extending nozzles 156 which are connected via a valve 30 to a compressed air source, e.g. B. the compressed air source 26 are connected. After the end of the tube 12 with the pressure plate 6 has been moved over the nozzles 156, the compressed air is switched on, the pressure plate 6 is pressed against the inner surface of the tube 12 and then the tube 12 with the pressure plate 6, as described above, over the plate cylinder body 2 emotional. In the embodiment shown in FIG. 4, it is not necessary that the mandrel 16 have a diameter that is larger than the diameter of the plate cylinder body 2.

LIST OF REFERENCES

2nd

Plate cylinder body

4a

Side wall of the printing press

6

printing plate

8a

first pressure plate end

8b

second pressure plate end

10th

Plate clamping device

12th

pipe

14

free end of the plate cylinder body 2

16

Mandrel

18th

Circumferential surface of the mandrel 16

20th

Cut-out of mandrel 16

22

tapered part of mandrel 16

24th

Air nozzles or air passage openings of the mandrel 16

26

Compressed air source

28

Air nozzles or air passage openings of the plate cylinder body 2

30th

Valve

32

central control unit

34

Indexing device / brand of pipe 12

150

Segments (Fig. 3)

152

Support elements (Fig. 3)

153

Segment 150 holes

154

Curvature of the segments 150

155

Air passage openings of the support elements 152

156

Mandrel 16 nozzles

Claims (20)

Method for applying a flat printing plate to a cantilevered plate cylinder of a printing press, which comprises the following steps: Curving the pressure plate into a substantially cylindrical shape; Inserting the pressure plate into a hollow tube having an inner diameter slightly larger than the outer diameter of the plate cylinder; Pushing the tube and the pressure plate laterally onto the plate cylinder via a mandrel, the mandrel being arranged concentrically to the plate cylinder and having an outer diameter which is smaller than the inner diameter of the tube and larger than the outer diameter of the plate cylinder; Securing the printing plate to the plate cylinder by actuating a plate clamping device; and Remove the tube from the plate cylinder. Method according to claim 1,
characterized by that the ends of the pressure plate are bent before the pressure plate is inserted into the tube, that the mandrel has a recess which corresponds to a gap in the pressure plate, and that the tube and the pressure plate are moved over the mandrel and the ends of the pressure plate are pushed through the recess. The method of claim 1 or 2,
characterized by that with the help of a label on the tube, a gap in the pressure plate is matched to a gap in the plate cylinder. Method according to one of the preceding claims,
characterized by that an air bed for the tube and the pressure plate is generated during the movement of the tube and the pressure plate over the mandrel. Method according to one of the preceding claims,
characterized by that when the tube and the pressure plate move over the mandrel, the pressure plate is given a circular cross-section, the inside diameter of which is somewhat larger than the outside diameter of the plate cylinder. Method according to one of the preceding claims,
characterized by that an air bed for the tube and the pressure plate is generated during the application of the tube and the pressure plate on the plate cylinder. Method according to one of the preceding claims,
characterized by that the mandrel is removed from the plate cylinder during operation of the printing press. Method according to one of the preceding claims,
characterized by that the mandrel is stretched to press the pressure plate against the inner surface of the tube after the front end of the tube has been moved over the mandrel. Method according to one of the preceding claims,
characterized by that removing the printing plate from the plate cylinder comprises the steps of: moving a tube over the plate cylinder; Release the ends of the pressure plate by actuating the plate tensioning device and Pull off the tube together with the pressure plate from the plate cylinder. Method according to claim 9,
characterized by that when removing the tube with the pressure plate from the plate cylinder blown air is directed to the inside of the pressure plate. Apparatus for applying a flat printing plate to a cantilevered plate cylinder of a printing press, which comprises the following features: a hollow tube (12) with an inner diameter slightly larger than the outer diameter of the plate cylinder (2); such as a mandrel (16) attached to the plate cylinder (2), which is arranged concentrically to the plate cylinder (2) and has an outer diameter that is smaller than the inner diameter of the tube (12) and larger than the outer diameter of the plate cylinder (2). Device according to claim 11,
characterized by that the mandrel (16) has a conical part (22) with a diameter that widens in the direction of the plate cylinder (2). Device according to claim 11 or 12,
characterized by that on the peripheral surface (18) of the mandrel (16) air passage openings (24) are provided in order to produce an air bed when the tube (12) and the pressure plate (6) move on the plate cylinder (2). Device according to one of claims 11 to 13,
characterized by that the peripheral surface (18) of the mandrel (16) is a material with a low Contains friction coefficient with respect to the material of the pressure plate (6). Device according to one of claims 11 to 14,
characterized by that the mandrel (16) is permanently attached to the plate cylinder (2). Device according to one of claims 11 to 15,
characterized by that the mandrel (16) has a recess (20) which corresponds to a gap in the pressure plate. Device according to one of claims 11 to 16,
characterized by that the tube (12) has a mark. Device according to one of claims 11 to 17,
characterized by that the mandrel (16) can be expanded to such an extent that the mandrel (16) has an outer diameter which is smaller than the inner diameter of the tube (12) and larger than the outer diameter of the plate cylinder (2). Device for applying a flat printing plate to a cantilevered plate cylinder of a printing press, which has the following features: a hollow tube (12) with an inner diameter slightly larger than the outer diameter of the plate cylinder (2); a mandrel (16) concentric with the plate cylinder (2) which is mounted on the plate cylinder (2) and has a radially extending row of nozzles (156) through which an air bed is created, such that the pressure plate (6) is pressed against the inner surface of the tube (12) if that Pipe (12) and the pressure plate (6) are moved over the plate cylinder (2). Method for applying a flat printing plate to a cantilevered plate cylinder of a printing press, which comprises the following steps: Curving the pressure plate into a substantially cylindrical shape; Inserting the pressure plate into a hollow tube with an inner diameter slightly larger than the outer diameter of the plate cylinder; Pushing the tube with the pressure plate laterally onto the plate cylinder via a mandrel, an air bed being generated by air passage openings in the mandrel which presses the pressure plate against the inner surface of the tube when the tube and the pressure plate are moved over the mandrel; Securing the printing plate to the plate cylinder by actuating a plate clamping device; and Remove the tube from the plate cylinder.

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