GB2286365A

GB2286365A - Changing the covering of a printing machine cylinder

Info

Publication number: GB2286365A
Application number: GB9502897A
Authority: GB
Inventors: Peter Knauer; Klaus Reichel
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1994-02-15
Filing date: 1995-02-15
Publication date: 1995-08-16
Also published as: FR2716140B1; GB9502897D0; JPH07256864A; DE4404758C2; DE4404758A1; FR2716140A1

Description

Changing the covering of-a cylinder in a web-fed rotary printing machine

2286365 The invention relates to a web-fed rotary printing machine including a cylinder which carries a covering, in particular a printing forme or a printing blanket, in which at least one side wall has an aperture through which the covering can be guided into or out of the printing machine; the invention also concerns a process for changing the covering of a cylinder.

One type of printing forme used in web-fed rotary printing machines is the finite type, in the form of a plate clamped with its ends in the clamping channel of the forme cylinder (e.g. DE-AS 27 59 434). For clamping purposes the printing plate is inserted with one end into the clamping channel. In tip or step operation the forme cylinder is then set into rotation and the printing plate is wound onto it. The second end of the printing plate is then inserted into the clamping channel and then, if necessary, clamping elements are actuated and the plate ends are drawn into the clamping channel. This procedure is timeconsuming. In addition the web has to be cut off; the subsequent drawing-in of the web involves a further loss of time, in addition to the resulting waste. Finite (i.e. sheet-like) printing blankets of transfer cylinders are changed in a similar way (e.g. DD 248 695 A3) and also give rise to the described losses.

There is an alternative type of printing formes and printing blankets, which is endless in construction in the form of a sleeve (DE 35 43 704 A1). For assembly or dismantling purposes these sleeves are pushed through apertures in the side wall of the printing machine up on to or down from the appropriate cylinder. This is possible quickly without tip operation and with the web drawn in to the machine, though lifted from the cylinder in question. Laser welding apparatus, for instance, is required for the production of the sleeves, or seamless or galvanically produced sleeves are used.

An aim of the invention is to produce a web-fed rotary printing machine in which as an alternative economically producible coatings of cylinders can be used and in addition the advantages of this machine concept remain usable but without the sleeves being welded, galvanically produced or drawn. In addition a process for changing the coatings has to be devised.

According to one aspect of the invention there is provided a cylinder for a web-fed rotary printing machine in which one side wall has an aperture through which a covering can be guided into or out of the printing machine and on to or off the cylinder, in which the casing of the cylinder is provided with an axial slot open at its end towards the side wall having the aperture, which slot is adapted to receive the ends of the covering when applied to the cylinder, so that the covering can be applied to the cylinder in the axial direction.

In an alternative aspect the invention is directed to a process for applying a covering to a cylinder of a web-fed rotary printing machine, in particular a printing forme or a printing blanket, wherein a plateshaped flexible covering is bent by hand into a circle corresponding to the shape when laid on the cylinder, the covering is inserted into the printing machine through an aperture in a side wall and pushed onto the cylinder, the ends of the covering being pushed into a longitudinal slot of the cylinder open at the insertion end of the cylinder.

The invention means that the plate or blanket is flat but can be applied to the cylinder in a similar way to a sleeve; this makes possible the rapid exchange of finite coverings of cylinders, for instance rubber blankets or printing plates, since tip operation and cutting-off of the web are not necessary. On the other hand the advantages of these flat coatings are offered. Laser technology is dispensed with. The only thing necessary is the bending machine for bending over the plate ends or, as appropriate, the ends of the carrier for the printing blanket. Advantageously a printing plate can be imaged, transported and mounted in a space-saving manner, all in the flat state in the traditional way. The printing plate and the rubber blanket can be reliably secured with conventional clamping elements, thus ensuring in-register fixing. The use of compensation or make-ready sheets under the printing plate, allowed by the traditional clamping of finite offset printing plates, can also be retained in order to compensate for thickness variations. Thanks to the axial insertion of the plate ends into the longitudinal slot of the cylinder a very narrow clamping channel can be produced which in practice only needs to be dimensioned slightly wider than twice the thickness of the plate. With an offset plate 0.3 mm thick the width of the clamping channel can be, for instance, in the region of 0.8 mm. With such a clamping channel a larger type area can be produced, or if the type area is maintained a saving in paper can be achieved with a smaller cylinder. A saving in cost is also produced by dispensing with an air supply to the cylinders. Furthermore the vibration behaviour of the printing machine is improved.

Advantageous developments can be seen in the subclaims in conjunction with the description.

Some exemplary embodiments of the invention will now be described in detail, referring to the accompanying drawings, in which:

Fig. 1 shows a printing unit in a web-fed Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 rotary printing machine in a partial sectional view; shows the view Z according to Fig. 1; shows the view Y according to Fig. 1; shows a printing plate to be clamped; shows the printing plate of Fig. 4 bent into the shape of a circle; shows a partial view of the printing plate inserted into the longitudinal slot of the cylinder; and shows a further variant embodiment of the invention.

Fig. 1 shows two cylinders 1, 2 of a printing unit. On the drive side they are mounted in the side wall 5 on journals 3, 4. The operating-side journals 6, 7 of the cylinders 1, 2 are mounted in two carrier walls 8 which are placed onto the side wall 9. The carrier walls 8 cover an aperture 10 in the side wall 9. The carrier walls 8 are divided along a vertical line and the two halves can be moved horizontally away from the journals 6, 7, exposing the aperture 10.

Each cylinder 1, 2 has in its casing a slot 11, 12 parallel to the axis of the cylinder and preferably open towards both ends of the cylinder body, though it is sufficient if it is merely open towards the side wall 9 having the aperture 10. The longitudinal slots 11, 12 have insertion gradients or bevels 13 (Figs. 2, 3) at the end facing the side wall 9. These bevels extend radially, being inclined with respect to the axial direction so as to assist in inserting the ends of a plate, as described below. At the same end the cylinder casings are also provided with circumferential sliding gradients 14, 15.

In the embodiment shown the cylinder 2 is constructed as a forme cylinder. Its covering is a printing plate 16, shown in Fig. 4. Its longitudinal slot 13 thus leads, in the radially inward direction, to a channel 17 which is to contain a clamping device for the printing plate 16. The longitudinal slot 12 and such a clamping device 18 are shown in Fig. 6 in an embodiment modified with respect to Fig. 2.

A plate 16 suitable for use with the invention is shown in Figs. 4 and 5. It consists of a flat area which is the plate proper, and two end portions 21 and 22 bent over in the same direction out of the plane of the plate. These ends are adapted to overlap each other when the plate is curved to the diameter of the cylinder, as shown in Fig. 5. Moreover the ends preferably interengage, as exemplified by the rounded end edge of the left-hand end 22 and the corresponding hook 23 of the other end 21. Finally at least one of the ends has a thickened part, here a wire or rod 24, to enable clamping to take place.

To mount the printing plate 16 on the cylinder 2 first of all the aperture 10 in the side wall 9 is exposed. For this purpose the carrier walls 8 are moved apart. No precise description of this procedure is given since this is not the object of the patent. One possibility of bringing this into effect is described, for instance, in EP 0 352 599 B1, but other solutions are also known for producing an aperture 10 in the side wall 9 which has to be larger than the diameter of the cylinder 2 when it is covered. The cylinders 1, 2 are now no longer mounted on the operating side, so they are kept in the horizontal position by support devices 19, 20 engaging on their drive-side journals 3, 4. Solutions for this also are known to the expert from the prior art, e.g. according to EP 0 279 349 A2.

Now the printing plate 16 to be clamped is bent into a circle to form a sleeve, its bent-over ends 21, 22 coming into abutment. Thus shaped the printing plate is pushed through the aperture 10 in the side wall 9 onto the cylinder 2, the sliding gradients 15 facilitating the sliding onto the cylinder body, and the insertion gradients 13 facilitating insertion of the ends 21, 22 into the longitudinal slot 12. Whilst being pushed on the ends 21, 22 of the printing plate 16 extend into the region of the clamping elements of the clamping device. In the embodiment shown the ends 21, 22 close with a loop or hook 23 and a wound-in wire 24 respectively, as mentioned above, which come to lie in the longitudinal groove 25 of a clamping spindle 26 (see Fig. 6). When the clamping spindle 26 is rotated clockwise the ends 21, 22 are drawn deeper into the longitudinal slot 12, and the printing plate 16 is clamped.

Other clamping systems can also be used when applying the invention. Thus, the clamping slot does not need to lead to a clamping channel but the clamped- in ends of the printing forme can be clamped in the slot itself. These ends are then advantageously held together by adhesive to facilitate the bending of the circular shape of the printing plate. Other cylinder coverings can also be clamped with the invention, for instance printing blankets of transfer cylinders or impression coatings of impression cylinders.

The invention also allows printing machines to be fitted as required with cylinders for finite or endless coverings, i.e. for channel technology or sleeve technology. Both technologies can also be represented at the same time in one printing unit, i.e. one cylinder can be made in channel technology and another cylinder in channel-less technology.

The invention also allows not only the covering but also the body of the cylinder to be guided through the aperture of the side wall respectively out of or into the printing unit. When the cylinder is constructed as a printing forme cylinder it is also possible, for instance, to change its body for a body of another type of printing forme. It is also possible to change the body for a body for another printing process, e.g. a body with a channel for a finite offset printing plate for a body on whose casing a gravure printing forme is engraved. Hybrid printing machines can therefore be made.

This type of interchangeability is shown in Fig.

7. The cylinder 27 is mounted with its journals 28, 29 in the side wall 30 and the carrier walls 31. The body 32 of the cylinder 27 is releasably connected by means of a cone 33 to the drive-side journal 28. In order to be able to remove the cylinder body 32 from the printing unit first of all the aperture 34 in the side wall 35 is exposed, the carrier walls 31 being moved apart. The cylinder 27 is held in the horizontal position by means of the support device 36 engaging on the journal 28. Using a handling device (not shown), for instance a robot, the body 32 is then withdrawn together with the journal 29 from the cone 33 and removed from the printing unit through the aperture 34 which is larger than the diameter of the body 32. In reverse sequence another body, or the body 32 provided with another coat, is then inserted. The separation of the body from the drive-side journal can also be effected in a different way. For instance the dividing point may be in the region of the drive-side journal, or only the body of the cylinder is removed from the cylinder axis.

Claims

1. A cylinder for a web-fed rotary printing machine in which one side wall has an aperture through which a covering can be guided into or out of the printing machine and on to or off the cylinder, in which the cajing of the cylinder (1, 2) is provided with an axial slot (11, 12) open at its end towards the side wall (9) having the aperture (10), which slot is adapted to receive the ends of the covering when applied to the cylinder, so that the covering can be applied to the cylinder in the axial direction.

2. A cylinder according to claim 1, in which the longitudinal slot (11, 12) has insertion gradients (13) at the entry end of the body of the cylinder (1, 2).

3. A cylinder according to claim 1 or 2 and carrying a covering, in particular a printing forme or a printing blanket.

4. A web-fed rotary printing machine including at least one cylinder according to any preceding claim.

5. A web-fed rotary printing machine according to claim 4, in which the body (32) of the cylinder (27) can be guided through the aperture (34) of the side wall (35) into or out of the printing machine.

6. A web-fed rotary printing machine in which one side wall (35) has an aperture (34) through which a covering can be guided into or out of the printing machine and on to or off a cylinder (27), characterised in that the body (32) of the cylinder (27) can be guided through the aperture (34) of the side wall (35) into or out of the printing machine.

7. A web-fed rotary printing machine according to claim 5 or 6, in which the cylinder (27) is a printing forme cylinder and its body (32) can be changed for a body of another type of printing forme.

8. A web-fed rotary printing machine according to any of claims 5 to 7, in which the body (32) of the R cylinder (27) can be changed together with its journal (29) facing towards the aperture of the side wall (35).

9. A web-fed rotary printing machine according to any of claims 5 to 7, in which the body of the cylinder 5 can be withdrawn from the shaft of the cylinder.

10. A web-fed rotary printing machine in which one side wall, at least in the case of a cylinder which carries a covering, in particular a printing forme or a printing blanket, has an aperture through which the covering can be guided into or out of the printing machine, characterised in that the casing of the cylinder (1, 2) is provided with an axis- parallel longitudinal slot (11, 12) open towards the side wall (9) having the aperture (10), which slot, for the purposes of clamping, receives the bent-over ends of the covering or leads to the channel (17) with the clamping device (18) for the covering.

11. A process for applying a covering to a cylinder of a web-fed rotary printing machine, in particular a printing forme or a printing blanket, wherein a plateshaped flexible covering is bent into a circle corresponding to the shape when laid on the cylinder, the covering is inserted into the printing machine through an aperture in a side wall and pushed onto the cylinder, the ends of the covering being pushed into a longitudinal slot of the cylinder open at the insertion end of the cylinder.

12. A process according to claim 11, in which the ends (21, 22) of the covering are provided with an adhesive and stuck together, aiding the formation and preservation of the circular shape.

13. A process according to claims 11 or 12 and including the further, preliminary, step of the removal of the previous covering in reverse sequence.

14. A cylinder substantially as described herein with reference to any of the embodiments shown in the accompanying drawings.