GB2366242A

GB2366242A - Lithographic printing machine with interchangeable cartridge

Info

Publication number: GB2366242A
Application number: GB0021557A
Authority: GB
Inventors: Andrew Steven; Andrew Hamer
Original assignee: CRABTREE GATESHEAD Ltd; Crabtree of Gateshead Ltd
Current assignee: CRABTREE GATESHEAD Ltd; Crabtree of Gateshead Ltd
Priority date: 2000-09-02
Filing date: 2000-09-02
Publication date: 2002-03-06
Also published as: GB0021557D0

Abstract

A lithographic printing machine which is arranged to accommodate any one of a series of interchangeable cartridges 16 each containing a plate cylinder 18 and a blanket cylinder 20 of the same effective diameter as one another with the cylinders disposed in peripheral contact with one another, the effective diameter being different in each cartridge 16 in the series. Each plate cylinder 18 is adapted to make peripheral contact with a common tangential point 22 on a forme cylinder 12. Preferably each blanket cylinder 20 may make peripheral contact with an impression cylinder 26 mounted in an associated cartridge so as to be capable of printing on a substrate fed between the cylinders.

Description

<Desc/Clms Page number 1> "A Lithographic Printing Machine." This invention relates to an improvement in lithographic printing machines.

Printing machines of lithographic type are well known, and basically comprise an integral inking mechanism including at least one forme roller for transferring ink to a lithographic or other rigid printing plate fixed on the periphery of a plate cylinder which transfers a pattern of ink to a plain sheet of resilient material fixed on the periphery of a blanket cylinder, said cylinder having the same effective diameter as one another.- The blanket cylinder in turn transfers the pattern to a substrate fed between the blanket cylinder and an impression cylinder, all three cylinders being driven in timed relationship with one another and with the rate of fed of the substrate.

Printing machines of flexographic type are also well known. In order to facilitate changes in ink colour, instead of having an integral inking mechanism, machines of this type are provided with an interchangeable cartridge containing an ink reservoir, an inking or so-called aniiox cylinder which picks up ink from the reservoir, and a printing cylinder to which ink is transferred by the inking cylinder. The printing cylinder has fixed on its periphery a bas-relief printing plate formed of resilient material which transfers a pattern of ink to a substrate fed between the printing cylinder and an impression cylinder, the anilox, printing and impression cylinders being driven in

timed relationship with one another and with the rate of feed of the substrate.

The object of the present invention is to combine features of both of the aforesaid types of machines in order to facilitate changes in plate sizes.

According to the invention, a lithographic printing machine is arranged to accommodate any one of a series of interchangeable cartridges each containing a plate cylinder and a blanket cylinder of the same effective diameter as one another with said cylinders disposed in peripheral contact with one another, said effective diameter being different in each cartridge of the series and each plat cylinder being adapted to make peripheral contact with a common tangential point on a forme roller.

Preferably, the forme roller has a fixed axis when in operative position.

Preferably, also, each blanket cylinder can make peripheral contact with an impression cylinder mounted on the machine so as to be capable of printing on a substrate fed between said cylinders.

Alternatively, each blanket cylinder can make peripheral contact with an impression cylinder mounted in the associated cartridge so as to be capable of printing on a substrate fed between said cylinders.

Preferably, each plate cylinder is also adapted to make peripheral contact with at least one additional forme roller.

Preferably, also, the or each additional forme roller is arranged to be moved into operative position defined by a stop.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawing, which is a side elevation of part of a print tower for an improved lithographic printing machine.

Referring now to the drawing, a lithographic printing machine comprises an elongated base frame or bed (not shown) with a plurality of print towers such as 10 spaced along it. Each print tower 10 is provided integrally in its upper part with an inking mechanism comprising a train of rollers which receive ink from a reservoir and transfer it as a thin even coating onto a large diameter forme roller 12 which is a feature of this invention and also onto two additional small diameter forme rollers 14 which are conventional. Contrary to the usual practice in lithographic printing, each print tower 10 is arranged ro accommodate any of one of a series of interchangeable cartridges such as 16. Each cartridge 16 contains a plate cylinder 28 and a blanket cylinder 20 of the same effective diameter as one another with such pair of cylinders disposed in peripheral contact with one another. Said effective diameter is different in each cartridge 16 of the series, different sizes of said cylinders being shown diagrammatically in broken lines as pair 18A and 20A, pair

18B and 20B, and pair 18C and 20C. In well known manner, each plate cylinder has a lithographic or other rigid printing plate (not shown) fixed on its periphery and each blanket cylinder has a plain sheet of resilient material (not shown) fixed on its periphery. The purpose of providing cartridges 16 containing pairs of cylinders of different sizes is to facilitate changes in the size of printing plates utilised. It follows that on the same machine at any one time, all the print towers 10 must accommodate identical cartridges 16 containing pairs of cylinders of a uniform diameter. Each plate cylinder, whatever its diameter, is adapted to make peripheral contact with a common tangential point 22 on the large diameter forme roller 12. Said roller has an axis 24 which is fixed when the roller is in operative position in contact with a plate cylinder, whereas each of the two small diameter forme rollers 14 is arranged to be moved relative to the inking mechanism into operative position defined by a stop (not shown) so as to make contact with a plate cylinder. The whole inking mechanism including the rollers 12 and 14 is adapted to be moved relative to the plate cylinder from its operative position to facilitate inking of the plate and changing of the cartridge 16. Each blanket cylinder, whatever its diameter, can make peripheral contact with an impression cylinder 26 mounted on the bed of the machine in association with each of the print towers 10.

In operation, all of the plate cylinders, the blanket cylinders and the impression cylinders 26 of a machine are positively driven in timed relationship with one another and with the rate of feed of a substrate (not shown) fed between the blanket cylinders and the impression cylinders. The substrate can be a continuous web or a succession of individual sheets accurately registered in well known manner, and can consist of paper, metal or other suitable material. Ink is transferred from the forme rollers 12, 14, which may be frictionally driven, to the printing plate. The printing plate transfers a pattern of ink to the sheet of resilient material fixed on the periphery of the blanket cylinder, and said sheet in its turn transfers the pattern to the substrate to print an image thereon.

In a modification, one of the small diameter forme rollers 14 is supplied with water for damping purposes instead of, or in addition to, ink. In another modification, each cartridge 16 also contains the associated impression cylinder.

Claims

Claims:- 1. A lithographic printing machine arranged to accommodate any one of a series of interchangeable cartridges each containing a plate cylinder and a blanket cylinder of the same effective diameter as one another with said cylinders disposed in peripheral contact with one another, said effective diameter being different in each cartridge of the series, and each plate cylinder being adapted to make peripheral contact with a common tangential point on a forme cylinder. 2. A lithographic printing machine according to claim 1, wherein the forme roller has a fixed axis when in operative position. 3. A lithographic printing machine according to either of the preceding claims, wherein each blanket cylinder can make peripheral contact with an impression cylinder mounted on the machine so as to be capable of printing on a substrate fed between said cylinders. 4. A lithographic printing machine according to claim 1 or claim 2, wherein each blanket cylinder can make peripheral contact with an impression cylinder mounted in the associated cartridge so as to be capable of printing on a substrate fed between said cylinders. S. A lithographic printing machine according to any one of the preceding claims, wherein each plate cylinder i6 also adapted to make peripheral contact with at least one additional forme cylinder.

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6. A lithographic printing machine according to claim 5, wherein the or each additional forme roller is arranged to be moved into operative position defined by a stop.

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Amendments to the claims have been filed as follows Claims:- 1. A lithographic printing machine arranged to accommodate any one of a series of interchangeable cartridges each containing a plate cylinder and a blanket cylinder of the same effective diameter as one another with said cylinders disposed in peripheral contact with one another, said effective diameter being different in each cartridge of the series, and each plate cylinder being adapted to make peripheral contact with a common tangential point on a forme roller. 2. A lithographic printing machine according to claim 1, wherein the forme roller has a fixed axis when in operative position. 3. A lithographic printing machine according to either of the preceding claims, wherein the forme roller is of substantially larger diameter than conventional forme rollers. 4. A lithographic printing machine according to any one of the preceding claims, wherein each blanket cylinder can make peripheral contact with an impression cylinder mounted on the machine so as to be capable of printing on a substrate fed between said cylinders. 5. A lithographic printing machine according to any one of claims 1 to 3, wherein each blanket cylinder can make peripheral contact with an impression cylinder mounted in the associated cartridge so as to be capable of printing on a substrate fed between said cylinders.

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6. A lithographic printing machine according to any one of the preceding claims, wherein each plate cylinder is also adapted to make peripheral contact with at least one additional forme roller. 7. A lithographic printing machine according to claim 6, wherein the or each additional forme roller is arranged to be moved into operative position defined by a stop. 8. A lithographic printing machine according to claim 6 or claim 7, wherein the additional forme rollers are of conventional small diameter compared with the plate and blanket cylinders. 9. A lithographic printing machine according to any one of the preceding claims, wherein its whole inking mechanism including the forme roller or rollers is adapted to be moved relative to the plate cylinder away from the operative position of said mechanism. 10. A lithographic printing machine constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawing.