GB2329153A

GB2329153A - Printing cylinders in a web printing machine

Info

Publication number: GB2329153A
Application number: GB9820020A
Authority: GB
Inventors: Peter Knauer; Josef Singler
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1997-09-15
Filing date: 1998-09-14
Publication date: 1999-03-17
Anticipated expiration: 2018-09-14
Also published as: DE19740475A1; FR2768364B1; FR2768364A1; GB2329153B; GB9820020D0

Abstract

In printing cylinders in a web printing machine arrangements of cylinder gaps (11 to 15) are created in different printing cylinders (3 to 6), with the cylinder gaps (11 to 15) of adjacent cooperating cylinders (3 to 6) being offset with respect to each other, preferably by 90‹ if there are two printing plates, rubber blankets or coatings in at least one of the adjacent cylinders, or by 180‹ if there is only one single coating or one single printing plate arranged on each of the two adjacent cylinders.

Description

2329153 Printing Cylinders in a Web Printing Machine The invention relates

to printing cylinders in a web printing machine.

It is already known from DE 34 41 175 C2 to provide a transfer cylinder, i.e. a rubber blanket cylinder, with a plurality of cylinder gaps on the circumference and to cover it with a plurality of rubber blankets, each surrounding a circumferential section allocated to one turn of a plate cylinder. In this connection, the cylinder gaps of the rubber blanket cylinder each lie opposite the single cylinder gap of the plate cylinder. A sheet-fed printing machine for indirect printing is known from DE 256 705, in which printing machine a forme cylinder is covered with two plates, and a transfer cylinder allocated thereto is likewise covered with two rubber blankets. Also in the case of this printing machine, the cylinder gaps of the forme cylinder roll on the cylinder gaps of the transfer cylinder.

As a result of the rolling of the cylinder gaps, vibrations occur in the printing cylinders, i.e. the forme cylinder and the transfer cylinder.

It is the object of the invention to reduce the vibrations of printing cylinders having gaps on the circumferences thereof.

According to the present invention there is provided a printing unit or printing couple in a web printing machine for offset printing, having at least three printing cylinders, with the printing cylinders comprising at least one forme cylinder and at least one transfer cylinder and with at least two printing cylinders which cooperate with each other being covered on their lateral surfaces by coatings or blankets which each form at least one cylinder gap, the cylinder gaps of the coatings or blankets of adjacent cooperating -1) 2- cylinders being arranged so as to be offset with respect to each other.

Advantageous developments are set out in the attached subsidiary claims.

The cylinder gaps of two printing cylinders which cooperate with each other in each case, i.e. roll on each other, for example a forme cylinder and a transfer cylinder, are offset with respect to each other in accordance with the invention. An offset of a rubber blanket of 900 or 1800 with respect to the printing plate of the forme cylinder is particularly suitable, in which case care is to be taken that the cylinder gap of the rubber blanket on the transfer cylinder lies opposite a non-printing area of the printing plate of the forme cylinder.

Transfer cylinders which cooperate with each other and between which a web of printing material runs, as is the case in a blanket-to-blanket printing unit, can also have cylinder gaps which are offset by 900 or 1800 or by another angle.

If a transfer cylinder cooperates with an impression cylinder in such a way that a web of printing material passes between the transfer cylinder and the impression cylinder, the impression cylinder, provided that it is covered with an ultimate layer and has a cylinder gap, can also have an offset angle of a cylinder gap with respect to the cylinder gap of the transfer cylinder.

An offset of the cylinder gaps of a forme cylinder and of a transfer cylinder can be realised both in the case of a single-sized forme cylinder and in the case of a double-sized forme cylinder, with respect to the size of the transfer cylinder. A single-sized forme cylinder can cooperate with a single-sized transfer cylinder or with a doublesized transfer cylinder. Likewise, a double-sized forme cylinder can roll on a double-sized transfer cylinder.

The measures described above can also be realised in conjunction with each other.

In the following, the invention is described in greater detail in exemplary embodiments with the aid of the drawings, in which:

Figures 1 to 3 show printing units for blanket-toblanket printing; and Figure 4 shows a printing couple having an impression cylinder.

A printing unit 1 (Figure 1) for printing according to the blanket-toblanket principle for printing a web of printing material 2 has two forme cylinders 3 and 4 and also double-sized transfer cylinders 5 and 6 respectively allocated thereto. The transfer cylinders 5 and 6 are in each case covered with two rubber blankets 7 and 8, and 9 and 10 respectively. As a result of this, the transfer cylinders 5 and 6 each have two cylinder gaps 11 and 12, and 13 and 14 respectively- In order to reduce the vibrations between the forme cylinders 3, 4 and the associated transfer cylinders 5 and 6 respectively, cylinder gaps 15 and 16 for gripping printing plates 17 and 18 respectively on the forme cylinders 3 and 4 are arranged so as to be offset with respect to the cylinder gaps 11 and 12, and 13 and 14 respectively on the transfer cylinders 5 and 6. The offset preferably amounts to 900 with respect to the rotation of the transfer cylinders 5, 6. With respect to the rotation of the forme cylinders 3 and 4, this means that the offset of the cylinder gaps 15, 16 with respect to the cylinder gaps 11 to 14 on the transfer cylinders 5 and 6 amounts to 1800. As a result of this measure, an effective reduction in the vibrations of the forme cylinders 3, 4 and of the transfer cylinders 5, 6 is achieved.

1 In a printing unit 19 (Figure 2), instead of the forme cylinder 3 and the transfer cylinder 5, there are a forme cylinder 3' and a transfer cylinder 51, which are jointly rotated with respect to the transfer cylinder 6 and the forme cylinder 4. The transfer cylinder 51 is rotated by 900 with respect to the transfer cylinder 6, so that its cylinder gaps 11 and 12 are offset with respect to the cylinder gaps 13 and 14 of the transfer cylinder 6. The 900 rotation of the double-sized transfer cylinder 51 corresponds to a 1800 rotation of the forme cylinder 31.

An additional reduction in cylinder vibrations is achieved as a result of the fact that in addition to the offset of the cylinder gaps 15 and 16 of the forme cylinders 31 and 4 with respect to the transfer cylinders 51 and 6, the transfer cylinders 51 and 6 are also rotated by 900 with respect to each other.

In a printing unit 20 (Figure 3), double-sized forme cylinders 21, 22 each cooperate with double-sized transfer cylinders 23, 24 in order to print the web of printing material 2. Such double-sized forme cylinders 21, 22 are used, for example, in illustration printing, in which case, for example, each of the forme cylinders 21, 22 is covered with a printing plate 25 and 26 respectively, which is used to print, for example, in each case four pages arranged so as to be lying or standing on each other. The pages have, for example, a DIN A4 format, with there remaining between the first two and the following two sides on the respective printing plate 25, 26 a sufficiently wide print-free gap on which the respective cylinder gap 27 and 28 respectively of the associated transfer cylinder 23 and 24 respectively can roll. This additional print-free region necessarily results because of the folding process for the "collect-run production". The cylinder gaps 27, 29 are thus offset by 1800 with respect to the cylinder gaps 29, 30 on the forme cylinders 21 and 22. As an additional measure, analogous to the representation in Figure 2, the cylinder gaps 27 and 28 of the transfer cylinders 23 and 24 can be offset with respect to each other. Preferably, an offset of 1800 is suitable if in each case there is only one cylinder gap on each of the transfer cylinders 23 and 24. For the case that there are two cylinder gaps on each of the transfer cylinders 23, 24, the cylinder gaps of the transfer cylinders 23 and 24 can each be offset by 900 with respect to each other in order to reduce vibrations.

A printing couple 31 (Figure 4) has a forme cylinder 32, a transfer cylinder 33 and an impression cylinder 34 for printing a web of printing material 2. The forme cylinder 32 and the transfer cylinder 33 are constructed as shown in Figure 3, the impression cylinder 34 is coated with a preferably hard coating 35 which is held in a cylinder gap 36 by means of gripping means.

A printing plate 37 is held firmly in a cylinder gap 38 on the forme cylinder 32, while a rubber blanket 39 is held firmly in a cylinder gap 40 on the transfer cylinder 33.

The cylinder gaps 36, 38, 40 are offset at an angle with respect to each other in the printing couple 31 as well. The cylinder gap 40 is preferably offset by 1800 with respect to the cylinder gap 38, the cylinder gap 36 is likewise offset by 1800 with respect to the cylinder gap 40. If the transfer cylinder 33 and the impression cylinder 34 are each provided with, for example, two coverings on their lateral surface, which coverings are held in two cylinder gaps, the cylinder gaps of the impression cylinder 34 are preferably offset by 900 with respect to the cylinder gaps of the transfer cylinder 33. The same applies if the forme cylinder 32 also has two printing formes, which are held in two cylinder gaps. These cylinder gaps are then also preferably offset by 901 with respect to the single cylinder gap or the two cylinder gaps of the transfer cylinder.

In accordance with the invention, arrangements of cylinder gaps 11 to 15, 27 to 30, 36, 38, 40 are created, which cylinder gaps are arranged in different printing cylinders 3 to 6, 31, 51, 21 to 24, 32 to 34, with the cylinder gaps 11 to 15, 27 to 30, 36, 38, 40 of adjacent cooperating cylinders 3 to 6, 3', 51, 21 to 24, 32 to 34 being offset with respect to each other, preferably by 901, if there are two printing plates, rubber blankets or coatings in at least one of the adjacent cylinders, or by 1800 if there is single coating or one single printing plate each of the two adjacent cylinders.

only one arranged on -7 r_

Claims

1 A printing unit (1, 19, 20) or printing couple (31) in a web printing machine for offset printing, having at least three printing cylinders (3 to 6, 31, 51, 21 to 24, 32 to 34), with the printing cylinders comprising at least one forme cylinder (3, 31, 4, 21, 22, 32) and at least one transfer cylinder (5, 5', 6, 23, 24, 33) and with at least two printing cylinders which cooperate with each other being covered on their lateral surfaces by coatings or blankets (7 to 10, 17, 18, 25, 26, 35, 37, 39, 41, 42) which each form at least one cylinder gap (11 to 15, 27 to 30, 36, 38, 40), the cylinder gaps of the coatings or blankets of adjacent cooperating cylinders being arranged so as to be offset with respect to each other.

2. A printing unit (1, 19, 20) or printing couple (31) according to claim 1, wherein a cylinder gap on a forme cylinder is offset by 900 with respect to the rotation of a cylinder gap on the associated adjacent transfer cylinderwhen the transfer cylinder is twice the size of the forme cylinder.

3. A printing unit (1, 19, 20) or printing couple (31) according to claim 1, wherein a single cylinder gap in a forme cylinder is offset by 1800 with respect to a single cylinder gap of the associated adjacent transfer cylinder (23, 24).

4. A printing unit (1, 19) or printing couple according to any one of the preceding claims, wherein a transfer cylinder (5, 51, 6) has a circumference which amounts to an integral multiple of the circumference of the associated adjacent forme cylinder (3, 3', 4), and the transfer cylinder (5, 51, 6) is covered with a number of rubber blankets (7, 9) that corresponds to the respective integral multiple and has a number of cylinder gaps (11, 14) that corresponds thereto.

5. A printing unit (20) or printing couple (31) is -8 according to any one of claims 1 to 3, wherein the forme cylinder (21, 22, 32) and the transfer cylinder (23, 24, 33) are in each case double-sized cylinders.

6. A printing unit (20) or printing couple (31 according to any one of claims 1 to 5, wherein one of the printing cylinders is an impression cylinder (34) which has a coating (35) held in a cylinder gap (36) which is offset with respect to the cylinder gap (40) of the transfer cylinder (33) which presses against said impression cylinder (34).

7. A printing unit (20) or printing couple (31) according to claim 6, wherein said offset of the impression cylinder gap (36) is 1800.

8. A printing unit substantially as hereinbefore described with reference to Figure 1, 2 or 3 of the accompanying drawings.

9. A printing couple substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.