GB2215272A

GB2215272A - Offset printing machine

Info

Publication number: GB2215272A
Application number: GB8902250A
Authority: GB
Inventors: Arndt Jentzsch
Original assignee: Kombinat Polygraph Werner Lamberz VEB; Polygraph Leipzig Kombinat Veb
Current assignee: Kombinat Polygraph Werner Lamberz VEB; Polygraph Leipzig Kombinat Veb
Priority date: 1988-02-04
Filing date: 1989-02-02
Publication date: 1989-09-20
Anticipated expiration: 2009-02-02
Also published as: GB2215272B; FR2626814B1; IT8967066A0; JP2832244B2; DE3901176A1; DE3901176C2; DD285877A7; IT1232567B; GB8902250D0; JPH01288444A; FR2626814A1

Description

h tlv r).;- j L- PRINTING MACHINE The present invention relates to a

printing machine, especially for multi- colour printing.

A sheet printing machine is known (DE 3203948) in which rubbe- cylinders of indfvidual printing units are arranged in series one::ontacting the other for ink transmission. A cylinder, which at the same time represents a feeder drum and a deflecting system of a deposit chain circle, is arranged to be pressable against a rubber cylinder.

It is disadvantageous in this machine that, for orint,ng ma2 transfer, numerous ink gaps are necessary, which cause point enlargement, image doubling and thereby a loss in quality. Moreover, regulation of ink layer thickness according to the different lengths of path of the ink to the sheets or web material to be printed is difficult in these machines in view of the more than average number of gaps. This design is not usable for modern machines with a larger number of printing units, for example a ten-colour machine, due to the mentioned disadvantages.

There is therefore a need for a printing machine which may provide an increase in printing quality, simplification of the sheet or web guidance and an increase in printing performance, especially a machine which may have a small number of ink gaps and may be able to be equipped with a larger number of printing units.

According to the present invention there is provided a printing machine comprising sheet or web material feed means, sheet or web material discharge means, a central printing cylinder to transfer sheet or web material from the feed means to the discharge means, an endless, printing image collecting element contacting the central printing cylinder, and at least one printing unit co-operable with the 2 endless element and comprising a printing cylinder, a counterpressure cylinder and inking and moistening means, the endless element extend ing through a pressure zone between the printing and counterpressure cylinders of said at least one unit.

The central printing cylinder may be provided with gripper means for gripping sheets or arranged to guide a web from the feed means to the discharge means. The printing cylinder of the at least one printing unit can be arranged above an upper run of the endless element or below a lower run of the element. The printing machine may comprise a further printing unit co-operable with the endless unit, the printing cylinder of the further unit being arranged below a lower run of the element. The machine may also comprise a further such endless printing image collect ing element and a further such printing unit co-operable with the further element, the further element being arranged in contact with the central printing cylinder.

The printing image collecting element can be constructed as an offset blanket, or at least one offset blanket portion is connected with the element, or the element is provided with at least one gripper for an offset blanket portion.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic elevation of a first printing machine embodying the invention; is a schematic elevation of a second printing machine embodying the invention; Fig. 3 is a schematic elevation of a third printing machine embodying the invention; Fi 9. 2 t 1 Fig. 4 is a schematic elevation of a fourth printing machine embodying the invention; and Fig. 5 is a schematic elevation of a fifth printing machine embodying the invention.

Referring now to the drawings, there is shown a printing machine which comprises a sheet or web conducting system and a printing-imageconducting system. The sheet or web conducting system consists (Figs. 1 to 4) of a blank material feed with a feeder 1, a feed table 2 and a sheet transfer device 3, for example a preliminary gripper, a sheet transport system constructed as a sheet-guiding central printing cylinder 4.1 arranged behind the sheet transfer device and a sheet discharge device constructed as a sheet deposit 5. The cylinder 4.1 is provided with two gripper systems 6, wherein the number of the gripper systems can be greater or smaller. In a construction as a roller printing machine (Fig. 5), the machine consists of a web-guiding system and a printing- image-guiding system. The web-guiding system consists of a web feed with an unreeling device 22, a web feed roller 23, a web-guiding central printing cylinder 4.2 and a web discharge device constructed as a reel ing device 24 with web discharge rollers 25.

The printing-image-conducting system comprises a printing image collecting element 7, which is constructed as an endless belt guided over two deflecting rollers 8 and is disposed in contact with the central printing cylinder 4.1 or 4.2, and at least one printing unit. The print ing unit consists of a printing plate cylinder 9 with an inking mechanism 10, a moistening mechanism 11 and a counterpressure cylinder 12. The upper run 13 of the element 7 passes through the contact zone between the printing cylinder 9 and counterpressure cylinder 12 (Fig. 1). At - 4 least one drying device 15 acts on the central printing cylinder and at least one washing device 16 and a patch collector 17 act on the element 7. The element 7 is constructed as an endless offset blanket 18 (Fig. 3), or at least one offset blanket piece 19 is connected with the element 7. In the case of several offset blanket pieces connected with the element 7, a gap for the gripper system 6 is provided. The element 7 can also consist of at least one offset blanket portion 21 held by a front edge or a front edge and rear edge and/or side edge gripper system 20 (Fig. 2). Fig. 2 shows an embodiment where the print- ing units, each consisting of a printing cylinder 9 with inking and moistening mechanisms 10 and 11 and a counterpressure cylinder 12, are disposed in contact with the lower run 14 of the element 7. Fig. 3 shows an embodiment where a number of printing units are disoosed in touching contact with the upper run of the element 7 and a number of further printing units are disposed in contact with the lower run of the element 7. Fig. 4 shows an embodiment where a further printing image collecting element 71 with appropriate printing units is associated with the central printing cylinder 4.1. Finally, Fig. 5 shows an embodiment where a printing image collecting element 7 is associated with the central printing cylinder 4.2.

In use of the machine, for example that of Fig. 1, a sheet taken from the feeder 1 is conducted by way of the feed table 2 and the sheet transfer device 3 to the central printing cylinder 4.1. Af ter printing, the ink applied to the sheet is dried by means of the dry- ing device 15 and conducted by means of the sheet discharge device 5 to the deposit stack. The printing image collecting element 7 runs through the pressure zone between printing cylinder 9 and counterpressure i j Z.! ^f - 5 cylinder 12 of the first printing unit and takes over the printing image with the first colour. In accordance with the number of the printing units, the further colours are applied in the same mode and manner. The collected colour image is transferred to the sheet on its passage through the printing zone between the central printing cylinder 4. 1 and printing image collecting element 7. The advantages of this system lie in the simple sheet guidance and printing with least doubling problems for a small number of ink gaps.

1

Claims

- 6 CLAIMS 1. A printing machine comprising sheet or web material feed

means, sheet or web material discharge means, a central printing cylinder to transfer sheet or web material from the feed means to the discharge means, an endless, printing image collecting element contacting the central printing cylinder, and at least one printing unit co-operable with the endless element and comprising a printing cylinder, a counterpressure cylinder and inking and moistening means, the endless element extending through a pressure zone between the printing and counter- pressure cylinders of said at least one unit.
2. A printing machine as claimed in claim 1, wherein the central printing cylinder is provided with gripper means for gripping sheets.
3. A printing machine as claimed in claim 1, wherein the central printing cylinder is arranged to guide a web from the feed means to the discharge means.
4. A printing machine as claimed in any one of the preceding claims, wherein the printing cylinder of said at least one printing unit is arranged above an upper run of the endless element.
5. A printing machine as claimed in any one of claims 1 to 3, wherein the printing cylinder of said at least one printing unit is arranged below a lower run of the endless element.
6. A printing machine as claimed in claim 4, comprising a further such printing unit co-operable with the endless element, the printing z;l cylinder of the further unit being arranged below a lower run of the endless element.
7. A printing machine as claimed in any one of claims 1 to 4, comprising a further such endless, printing image collecting element contacting the central printing cylinder and at least one further such printing unit cooperable with the further endless element.
8. A printing machine as claimed in any one of the preceding claims, wherein the endless element has the form of an offset blanket.
9. A printing machine as claimed in any one of claims 1 to 7, wherein the endless element is provided with at least one offset blanket portion.
10. A printing machine as claimed in any one of claims 1 to 7, wherein the endless element is provided with at least one gripper for an offset blanket portion.
11. A printing machine substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.
12. A printing machine substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.
13. A printing machine substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.
14. A printing machine substantially as hereinbefore described with reference to Fig. 4 of the accompanying drawings.
15. A printing machine substantially as hereinbefore described with reference to Fig. 5 of the accompanying drawings.

Published 1989 at The Patent Office, State House, 65-7 1 High Holborn, London WClR 4TP. Further copies maybe obtalned from The Patent Onice. Sales Branch, St Mary Cray, Orpington. Kent BRS 3RD. Printed by MWtaplex teebniques RAI, St Mary Cray, Kent, Con. 1187 I i j 1 i