GB2275019A

GB2275019A - A printing unit

Info

Publication number: GB2275019A
Application number: GB9402396A
Authority: GB
Inventors: Rainer Burger; Georg Riescher
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1993-02-10
Filing date: 1994-02-08
Publication date: 1994-08-17
Anticipated expiration: 2014-02-08
Also published as: GB9402396D0; GB2275019B; CH687916A5; JPH06255077A; DE4303904A1; DE4303904C2

Description

2275019 A Printing Unit The invention relates to a printing unit

comprising two printing mechanisms comprising in each case blanket cylinder and plate cylinder pairs. 5 One form of printing unit of this type is generally known and is referred to as "eight-tower". Fig. 1 shows a known eight- tower unit of this type, which comprises an upper eight-cylinder printing mechanism 1 and a lower eight-cylinder printing mechanism 2. Each of these eight-cylinder printing mechanisms 1, 2 comprises four plate cylinders 6, 7, 8, 9 and four rubber blanket cylinders 10, 11, 12, 13. Since the same basic structure is used for each of the cylinder arrangements described below, these references likewise apply for the cylinders which are not provided with reference numerals.

Using an eight-tower as illustrated in Fig. 1, a printing material web 3, abbreviated to "web" in the following, can be printed on both sides using vertical guidance in an upward direction with for example four inks, as is indicated in known manner by the triangles. As shown in Fig. lb, it is also possible to apply two dyes to both sides of two webs when the web 4 is guided through the lower, and the web 5 through the upper, eight-cylinder printing mechanism 2, 1 respectively.

An eight-cylinder printing mechanism of this type may have a simple structure and may be operable in one direction of rotation only. In addition, only the blanket cylinders lying in the same horizontal plane can be set against one another in each case. This may only allow for limited web paths, but the structure is simple and cost-effective. A serious disadvantage however is the poor register in the case of 4/4 printing (Fig. la), since the inks in the respective separated eight cylinder printing mechanisms 2 and 1 are applied in succession to the same side of the web.

The printing towers illustrated in Fig. 2 have the same advantages and disadvantages. These printing towers are also referred to as bridge printing mechanisms and in each case comprise, for example, four 5 superimposed "bridges", indicated by the numerals 14, 15, 16, 17. Also in this case, each of the "bridges" is formed by two blanket cylinders 18, 19, which can be set against one another, and two plate cylinders 20, 21. According to Fig. 2a, a web 22 can be provided with 4/4 printing - as in Fig. la; two webs 23, 24 can be provided with 2/2 printing on each side, as shown in Fig. 2b; one web 25 can be provided with 3/3 printing and a second web 26 with 1/1 printing, as shown in Fig. 2c; or one web 27 can be provided with 1/1 and a second web 28 with 3/3 printing, as shown in Fig. 2d; when the respective webs are guided in the illustrated manners through the printing unit.

As already mentioned, generally known printing units of this type have the same disadvantages as the printing unit according to Fig. 1.

Printing units comprising two superimposed socalled nine-cylinder satellites according to Fig. 3 are also known, in which the register stability is ensured, since all inks are applied in the lower or upper printing mechanism. However, it is not possible - at least not without taking further measures - to print two webs simultaneously on both sides using this type of printing unit comprising two superimposed ninecylinder satellites, e.g. as shown in Fig. 3, as is possible in the case of the printing units according to Figs. 1 and 2. Fig. 3 shows an upper 29 and a lower 30 nine-cylinder satellite printing mechanism with blanket/plate and impression cylinders, 31, 32 and 33 for providing a web with 4/4 printing.

Proceeding from known eight-cylinder towers (according to Fig. 1), it is the object of the invention to improve register stability whilst retaining the possibility of printing either one or two webs on both sides in each case.

According to the present invention there is provided a printing unit formed by two printing mechanisms each comprising a maximum of four blanket cylinder and plate cylinder pairs; wherein at least one of the printing mechanisms is constructed as a tencylinder satellite printing mechanism and the two printing mechanisms are arranged with each cylinder being exclusively drivable in a single predetermined direction of rotation and with each blanket cylinder being exclusively settable against an associated impression cylinder, the printing mechanisms being arranged to transfer print to one or two webs.

A washing, cleaning or rinsing device may be arranged beneath the impression cylinders of one of the two printing mechanisms.

Both printing mechanisms may be constructed as ten-cylinder satellite printing mechanisms or, alternatively, at least one of the printing mechanisms may be a merely partially assembled ten-cylinder satellite printing mechanism possibly having no upper blanket cylinder and plate cylinder pair. 25 The two printing mechanisms are preferably arranged one above the other, although it is possible for them to be arranged side by side. When the two printing mechanisms are arranged one above the other, an aforementioned washing, cleaning or rinsing device is preferably arranged beneath the impression cylinders of the upper printing mechanism.

It may be advantageous for the printing unit to be arranged such that when it is use, webs to be printed are guided in an upward direction through the printing mechanisms in each case.

For a better understanding of the invention and -4 its developments, and to show how it may be put into effect, reference will now be made by way of example to Figs. 4 to 7 of the accompanying drawings, which illustrate printing units in accordance with the invention and different web guidance possibilities and assembly stag es.

As a result of a new use of two superimposed tencylinder satellite printing mechanisms 35 and 36 as shown in each of Figs. 4a and 4b, it is possible to provide a single web 37 with a maximum 4/4 (Fig. 4a) printing and to print both sides of two webs 41, 42 simultaneously, in each case with a maximum 2/2 (Fig. 4b) printing, in each case the printing mechanism being in the fully assembled stage. Register stability is substantially improved as compared with the state of the art from which the invention proceeds. Also, the outlay required to this end consists solely in that two impression cylinders 40 are additionally required in each ten-cylinder satellite 35, 36.

It is significant to note that previously proposed ten-cylinder satellites, which offer a high degree of flexibility including the most web guidance possibilities, were provided with a reversible drive, i.e. the direction of rotation of the cylinders involved in the printing could be varied. In addition, it was a prerequisite for two blanket cylinders to be set against the associated impression cylinders and also against one another (blanket-blanket pressure). Otherwise the use of a ten-cylinder satellite would be meaningless before the present invention was devised.

The present invention departs from this formerly strictly observed principle. In accordance with the present invention, only a single direction of rotation of the cylinders involved in the printing is possible, and moreover the blanket cylinders are only settable against the associated impression cylinders - i.e. no longer against one another. This results in the significant advantage that a printing unit in accordance with the present invention and as shown in Figs. 4 to 6 can be manufactured more economically, since the use of two additional impression cylinders in the upper and lower printing mechanisms results in relatively low costs when compared with the reversible (reversal of direction of rotation) and convertible (from blanket-impression to blanket-blanket) printing mechanism of the previously proposed ten-cylinder satellites.

Furthermore, it was formerly unknown and not regarded as practical to arrange two ten-cylinder satellites above one another as shown in Figs. 4, 5 and 6. In this respect, the illustrated embodiments of the invention depart from the conventional way of thinking and propose the use of two superimposed printing mechanisms 35, 36 in a novel ten-cylinder satellite arrangement.

According to Fig. 4, the printing unit thereof comprises an upper printing mechanism 35 and a similarly constructed lower printing mechanism 36.

Each of these printing mechanisms comprises, as shown in the case of 35, four blanket cylinder/plate cylinder pairs 39, 38, two superimposed blanket cylinders (e.g. 39) being settable in each case against the same associated impression cylinder 40. A cleaning, washing or rinsing device 34 is preferably arranged beneath each of the upper impression cylinders 40 in order to remove the ink supplied by the lower printing mechanism 36 which has deposited on these cylinders 40.

As shown, it is possible using the printing unit in accordance with Fig. 4a to provide a web 37 with 4/4 printing with good register stability. In accordance with Fig. 4b two webs 41 and 42 can be simultaneously provided with 2/2 printing in each case, very good register stability again being obtained. Each side of the web is printed with the inks in succession in the same printing mechanism, so that no significant register errors can occur.

Figs. 5 and 6 illustrate different web guidance possibilities for the printing material webs 43, 44, 45, 46, 47, 48, the web guidance being effected in an upward direction in each case, but running in different ways through the printing unit. When compared with the web guidance according to Figs. 5a and 5b, which is a mirror image of the web guidance according to Figs. 4a and 4b, Figs. 6a and 6b show further variations of the web guidance for the webs 46, 47 and 48, which, whilst also providing good register stability, do somewhat impair accessibility of the individual printing mechanism parts as compared with the web guidance paths according to Figs. 4 and 5.

Fig. 5 shows different web guidance possibilities for the printing material webs 43, 44, 45, the web guidance being effected in an upward direction in each case, but running in different ways through the printing unit. The web guidance paths according to Figs. 5a and 5b are a mirror image of those shown in Figs. 4a and 4b.

Fig. 6 shows a variant of the printing unit according to Figs. 4 and 5 with a geometrically modified arrangement of the individual cylinders, which in a previously proposed embodiment observed the formerly strictly observed principle of reversible drive and blanket cylinders being settable both relative to one another and to the associated impression cylinders. A printing unit in accordance with the invention can also be constructed using the above variant and all other conceivable geometrical cylinder arrangements.

Fig. 6 also shows different web guidance possibilities of the printing material webs 46, 47, 48, the web guidance running in an upward direction in each case. Whereas good register stability is obtained in this case, the accessibility of the individual printing mechanism parts is somewhat impaired as compared with the web guidance paths according to Figs. 4 and 5.

A special further advantage of an embodiment of the invention lies in good part replaceability, it being possible, for example, to omit the upper blanket/plate cylinder pairs 39, 38 in the upper printing mechanism according to Fig. 7, g, i, or to easily fit these pairs at a later stage.

Figs. 7a, b, d, e show partially assembled versions of the prior printing units of Figs. 1 and 2.

In these partially assembled printing units a and b according to Fig. 7, it is necessary to omit the plate cylinders 9 (or 7) in the eightcylinder printing mechanisms 1 and 2 of Fig. 1 in order to provide either a single web with 4/2 printing or two webs with 2/1 printing. Similar considerations apply to the partially assembled printing units according to Figs. 7d and e in comparison with Fig. 2. According to the embodiments of the invention shown in Figs. 7g and i on the other hand, the impression cylinder 40 is required for the associated blanket cylinder 39.

In a partially assembled printing mechanism 35 according to Fig. 7, g, i, each upper blanket/plate cylinder pair 39, 38 is omitted in each case. In the case of a printing unit according to Figs. 7, a, b, d, e, the omitted plate cylinders 38 with the associated inking mechanisms need to be fitted at a later point in time by way of individual parts, which involves a correspondingly long standstill time. On the other hand, a subsequent fitting of the omitted blanket/plate cylinder parts 39, 38 with the associated inking mechanisms in a printing unit of the invention according to Figs. 7, g, i, can be effected by the attachment of a complete supplementary unit and is possible with a shorter standstill time.

The description and drawings focus on the arrangement of the two printing mechanisms 35, 36 one above the other as illustrated, which is extremely advantageous. However, it also falls within the framework of the invention and therefore within the protective scope of claim 1, to arrange the two printing mechanisms 35, 36 alongside one another in an equivalent manner, although this arrangement is less preferred.

Claims

Claims:

1. A printing unit formed by two printing mechanisms (35, 36) each comprising a maximum of four blanket cylinder and plate cylinder pairs (39, 38); wherein at least one of the printing mechanisms (35, 36) is constructed as a ten-cylinder satellite printing mechanism and the two printing mechanisms are arranged with each cylinder (38, 39, 40) being exclusively drivable in a single predetermined direction of rotation and with each blanket cylinder (39) being exclusively settable against an associated impression cylinder (40), the printing mechanisms (35, 36) being arranged to transfer print to one or two webs.

2. A printing unit according to claim 1, wherein a washing, cleaning or rinsing device (34) is arranged beneath the impression cylinders (40) of one (35) of said two printing mechanisms.

3. A printing unit according to claim 1 or 2, wherein both printing mechanisms (35, 36) are constructed as ten-cylinder satellite printing mechanisms.

4. A printing unit according to claim 1 or 2, wherein at least one (35) of the printing mechanisms is a partially assembled ten-cylinder satellite printing mechanism.

5. A printing unit according to claim 4, wherein said partially assembled ten-cylinder satellite printing mechanism (35) has no upper blanket cylinder and plate cylinder pair (39, 38).

6. A printing unit according to any preceding claim, wherein the two printing mechanisms (35, 36) are arranged one above the other.

7. A printing unit according to claim 6 when appended either directly or indirectly to claim 2, wherein said washing, cleaning or rinsing device (34) is arranged beneath the impression cylinder (40) of the upper printing mechanism (35).

8. A printing unit according to any one of the preceding claims which is arranged such that when it is in use, webs to be printed are guided in an upward direction through the printing mechanisms (35, 36) in each case.

9. A printing unit according to any one of the preceding claims, and having a web guidance path according to any one of those shown in Figures 4 to 7.

10. A printing unit substantially as hereinbefore described with reference to Figures 4 and 5, or Figure 6, or Figure 7i, g of the accompanying drawings.