WO2006048377A2

WO2006048377A2 - Rotary printing press

Info

Publication number: WO2006048377A2
Application number: PCT/EP2005/055391
Authority: WO
Inventors: John Mccrone
Original assignee: Goss Graphic Systems Ltd
Current assignee: Goss Graphic Systems Ltd
Priority date: 2004-11-08
Filing date: 2005-10-19
Publication date: 2006-05-11
Anticipated expiration: 2007-05-08
Also published as: GB2419876A; GB0424632D0; WO2006048377A3

Abstract

A rotary printing press is disclosed. It comprises a print unit for applying ink to a web of print medium (7) passing through the unit, a folder located adjacent to the print unit to receive the printed web from the print unit and, a slitting mechanism (2) located between the print unit and the folder to longitudinally slit the web into a plurality of ribbons (8a, 8b) each travelling side-by-side across the width of the press for entry into the folder. The press includes means (9,10) for changing the position of at least one ribbon (8a) relative to the or each adjacent ribbon (8b) so that the edges of adjacent ribbons are spaced apart from each other in a direction across the width of the press before entering the folder.

Description

Rotary Printing Press

Description

The present invention relates to a rotary printing press comprising at least one print unit and a folder. More specifically, the invention relates to a rotary press having a modified configuration between the or each print unit and the folder to adjust the path of the ribbons before they enter the folder. The invention also relates to a method of controlling the path of a web of print medium through a printing press according to the invention.

Each printing unit comprises a frame to which each print couple and its respective inking system are mounted. The printing unit may also comprise a dampening system associated with each inking unit also mounted to the frame. The printing units are spaced from each other and are aligned with a folder unit so that the paper web is fed through each print unit from a separate reelstand mounted below or to one side of each printing unit at floor level in a vertical direction through the print unit from its associated reelstand and then travels in a lateral direction away from the unit and down into the folder.

The folder has several functions; it must collect the webs, fold them at least once and cut them into longitudinal sections. The folder may be split into two functional groups. The upper folder collects the webs, folds or slits them longitudinally and delivers them to the lower folder. The lower folder — positioned vertically below the upper folder — cuts the webs into longitudinal sections, imparts a cross-fold to the sections and delivers them for transportation out of the folder.

Print units are expensive and consume a lot of space, so a modification of the print unit is common whereby the length of the plate and blanket cylinders, and the width of the paper web, is doubled or even tripled. So-called double-width or triple-width print units contribute 8 or 12 broadsheet pages to the newspaper being produced and their use is widespread. The use of double- or triple-width print units requires a corresponding modification to other parts of the printing press. The webs are too wide to pass over a single former within the upper folder and must be slit longitudinally into a number of what are commonly known as ribbons. The ribbons may be the width of a single-width web. The upper folder is normally provided with a plurality of formers (for instance two for double- width or three for triple-width) mounted side by side, with the ribbons passing over them to form the longitudinal fold along the centreline of each ribbon. The folded ribbons are then brought together for entry into the lower folder.

A slitting mechanism is provided for cutting the web into two or three ribbons before it enters the folder, depending on whether the press is a double or triple width press. It can be seen that this modification to the press is inflexible, because each printing unit contributes the same number of ribbons to each former and the ribbons from each former, held together by their longitudinal folds, form discrete sections of the newspaper. A triple-width press — without further modification — would produce a newspaper divided into three equal sections. In practice newspaper publishers require flexibility in the number of sections into which a newspaper is divided as well as in the number of pages within each section. Improved flexibility is achieved by the use of a turner bar arrangement after the web has been slit into ribbons to laterally shift one or more ribbons so that multiple ribbons can pass through the same former. A simplified representation of a conventional turner bar arrangement showing a single web which is slit into two ribbons initially travelling side-by-side and in which one ribbon is shifted by passing it through a turner bar assembly so that the two ribbons are positioned one above the other, is illustrated in Figure 1. This will now be described in more detail.

The web 1 is slit by a slitting mechanism 2 into two ribbons 3a,3b travelling side- by-side in the direction of arrow "A". The arrangement includes two turner bars 4,5 circular in cross section and arranged at 45 degrees to the direction of ribbon travel. One of the ribbons 3a is wrapped around the first turner bar 4 so that its direction of travel is altered and it leaves the bar at 90 degrees to its original direction. The second turner bar 5 is positioned parallel to the first and the ribbon 3a passes over this turner bar 5 to reverse the change of direction imparted by the first turner bar 4. As can be seen from the drawing, the two turner bars 4,5 used together have the effect of shifting ribbon 3a sideways in a direction across the width of the press but they also shift the plane occupied by ribbon 3a so that the ribbons 3a, 3b are no longer co-planar but occupy different parallel planes, while leaving the final direction of travel of ribbon 3a unaltered, so that the ribbons 3a, 3b are now in an overlapping relationship. The spacing between turner bars 4,5 is chosen so that the centreline 6a of ribbon 3a is positioned directly beneath centreline 6b of the neighbouring ribbon 3b. Both ribbons 3a,3b can then pass into the upper folder and onto the same former (not shown). It will be appreciated that a sufficient quantity of turner bars would allow all the ribbons in a double- or triple-width printing press to be directed to a single former to improve the flexibility of the press and allow sections of differing page sizes to be produced. The use of turner bars thus gives flexibility in the format of the finished newspaper, in terms of the number of sections and the number of pages in each section.

In practice, most double- or triple-width printing presses are supplied with sufficient turner bars to shift the ribbons as described above from some, not all, of the printing units. Normally the majority of the webs are not slit and turned on turner bars before the upper folder, but arrive at the first roller in the upper folder intact. These webs are then slit immediately prior to the formers, the ribbons thus produced passing through separate formers. The remaining webs pass through turner bar arrangements to shift ribbons from one former to another and therefore to change the number of broadsheet pages formed over each former.

The fold imparted to the ribbons as they pass through a former is sometimes known as the broadsheet fold as it forms the spine of a broadsheet newspaper. It will be appreciated that one ribbon, once folded longitudinally, contributes four broadsheet pages to the newspaper being produced. Therefore, one print unit is - A -

required for every four pages which are to be included in the newspaper being produced.

It will be appreciated that ribbons travel toward and into their respective formers without any lateral spacing between the edges of adjacent ribbons in a direction across the width of the press. The conveyance of ribbons having no lateral spacing between them can cause problems because there is a tendency for ribbons to move slightly off their original centreline as they progress through the press. This "ribbon wander", although only small, means that it is not good practice to convey adjacent ribbons on the same rollers because their edges may overlap. This overlap can initiate ribbon breakage when the ribbons have to separate in the upper folder leading to expensive machine downtime. To alleviate this problem, each ribbon follows a separate path, using separate path rollers, to the folder. However, this is not only expensive but also increases the height of the press and makes webbing up more difficult and time-consuming.

It is also common for the width of the ribbons in the press to be as great as 850 mm. This means that the path rollers in a triple-width press must be at least three times as long as the width of one ribbon. Path rollers of this length may deflect out of their axis of rotation due to a lack of sufficient support for the roller. Although using larger diameter path rollers can solve this problem, roller inertia then also becomes a significant factor affecting overall control of the press and the tension in the webs.

It is also common practice in large-scale high volume presses to automate the feeding of paper webs through the printing units and to the folder. A typical method is the use of tracks, which follow each web path through which a length of chain may be propelled, the chain being temporarily attached to the paper web and the propulsion being achieved by the use of drive motors located at regular intervals along the length of the track. Web feeding is considerably more difficult to achieve when the webs have been slit into ribbons because the one mechanism required to feed a web is not sufficient to feed the multiple ribbons produced from that web. Web feeding is particularly difficult in a triple-width press where the central ribbon is entrained by the outer ribbons.

The present invention seeks to overcome or substantially alleviate the problems described in more detail above. In particular, the present invention concerns a modified configuration of the upper area of the printing press between the printing units and the folder.

According to the invention, there is provided a rotary printing press comprising a print unit for applying ink to a web of print medium passing through the unit, a folder located adjacent to the print unit to receive the printed web from the print unit and, a slitting mechanism located between the print unit and the folder to longitudinally slit the web into a plurality of ribbons for entry into the folder, wherein the press includes means for changing the position of at least one ribbon relative to the or each adjacent ribbon so that the edges of adjacent ribbons formed by slitting the web are spaced apart from each other in a lateral direction across the width of the press before entering the folder.

The lateral spacing introduced between the ribbons provides the advantage that a support structure can be introduced into the space between them. Therefore, long path rollers can be replaced with short ribbon path rollers mounted to the support structure between ribbons. In the case of a triple-width press three coaxial short rollers could be used mounted either between supports or in a cantilever fashion. This substantially overcomes the problems of roller deflection when long rollers are used and large roller inertia caused by the use of oversize rollers. It will also be appreciated that, in addition to or in place of a support structure, automatic ribbon feeding equipment can be installed in the spacing between ribbons so that the feeding of each ribbon is automated and the difficulty of propelling, for example, a central ribbon entrained by an outer ribbon on each side is largely overcome. In a preferred embodiment, the means for changing the position of at least one ribbon is configured so that the ribbons all remain side-by-side extending across the width of the press and do not overlap after the position of at least one ribbon has been changed, i.e. the edges of adjacent ribbons formed when the web is slit remain facing each other but are spaced apart in a direction across the width of the press. Most preferably, all the ribbons lie in the same plane side-by- side spread across the width of the press before and after the position of at least one ribbon has been changed.

According to the invention, there is also provided a method of controlling the path of a print medium through a rotary printing press comprising a print unit for applying ink to a web of print medium passing through the unit, a folder located adjacent to the print unit to receive the printed web from the print unit and, a slitting mechanism located between the print unit and the folder, the method including the step of longitudinally slitting the web into a plurality of ribbons for entry into the folder and, changing the position of at least one ribbon relative to the or each adjacent ribbon so that the edges of adjacent ribbons are spaced apart from each other in a lateral direction across the width of the press before entering the folder.

In one embodiment, the step of slitting the web includes the step of slitting it into two ribbons and the step of changing the position of at least one ribbon includes the step of passing one ribbon over first and second turner bars, having their axes parallel to each other and 45 degrees to the direction of travel of the ribbons, so that the original direction of travel of said ribbon is maintained but it is spaced from the unturned ribbon in a direction across the width of the press.

In another embodiment, the step of slitting the web includes the step of slitting it into three ribbons to form a central ribbon and an outermost ribbon on either side of the central ribbon, the method further including the step of feeding each of the outermost ribbons through their respective turner bar arrangements to space each of the outermost ribbons from the central ribbon in a lateral direction across the width of the press.

It will be appreciated that many printing presses are used to produce a range of newspapers for different publishers where each publisher requires their newspaper to be a different size. The size of a newspaper is determined by the circumference of the printing cylinders and by the width of the paper web. In traditional printing presses the printing cylinder circumference is not changeable. However it is straightforward to change the web width, and printing presses are designed to allow a range of webs of different widths to be used.

It will be clear that when a web is slit into two or more ribbons and the ribbons have no lateral gap between them then the distance between one ribbon centreline and the next is a function of the width of the web. If two webs of different widths are compared, it follows that the pitch between ribbon centrelines is different for each web. This is significant because the formers in an upper folder must be positioned on the ribbon centrelines. It therefore follows that in a printing press, which operates with a range of webs of different widths, the formers must be adjustable in position so that their position can be changed in dependence on the web width being used.

Adjustable formers have several disadvantages. Firstly, they must be narrow enough to fit side-by-side when the narrowest web width is in use. This means that when they are moved further apart to cater for a wider web, there are gaps between formers. As already described there are no gaps between ribbons, so the formers cannot fully support the ribbons which pass over them. This situation can lead to poor ribbon flow and accelerated wear to the former. With the aim of avoiding or alleviating this problem, the formers are sometimes equipped with extension pieces which are added to the inside edge when the former spacing is increased to accommodate a wide web and removed before the former spacing is reduced for a narrow web. However former extension pieces do not easily lend themselves to automation of former position — time-consuming manual intervention is required. Secondly, all the ribbons finish in the same place - the lower folder — and moving formers together and apart changes the length of the paths taken by the ribbons. This change must be corrected before the ribbons enter the lower folder by the addition of section registers to the upper folder, adding cost and making the ribbon paths more tortuous. Thirdly, adjustable former mounting arrangements themselves add expense and reduce rigidity.

A typical former arrangement for a double-width press is illustrated in Figure 2 in which two ribbons 30 cut from a web having width slightly greater than the minimum web width are fed over a path roller 35 into separate side-by-side formers 31, 32 to fold them along their respective longitudinal centrelines 30a,30b. As the formers 31,32 must be able to accommodate other web widths, there is a space "Y" between the formers 31,32 to allow it to be changed. For example, the formers 31,32 would be pushed together to close the space "Y" if the web was of the minimum web width. In all configurations other than with the minimum web width, the formers 31,32 must be spaced from each other and so provide poor support to the ribbons 30 in the region of the spacing between the formers 31,32.

In view of the foregoing, the folder preferably includes a fixed datum for each ribbon spaced from each other across the width of the press and the slitting mechanism is operable to slit the web into two ribbons, wherein the means for changing the position of at least one ribbon changes the position of both ribbons in a lateral direction across the width of the press and is operable to change their position so that each ribbon is aligned with its corresponding fixed datum in the folder.

In a preferred embodiment, the distance through which the ribbons move to align them with their corresponding fixed datums in the folder depends on the width of the web. Advantageously, said means comprises a turner bar arrangement associated with each ribbon whose position is to be changed, the arrangement being such that when each ribbon is fed through its respective turner bar arrangement, the original direction of travel of said ribbons is maintained but they are spaced from each other in a lateral direction across the width of the press.

The turner bar arrangement may comprise first and second turner bars having their axes parallel to each other and 45 degrees to the direction of travel of the ribbons so that each ribbon whose direction is to be changed is turned twice by passing it over the first and second turner bars.

In one embodiment, only one ribbon is turned and the turner bars are located such that a path followed by the turned ribbon extends across the unturned ribbon as the turned ribbon travels between the first and second turner bars.

The first and second turner bars are preferably spaced from each other by a distance greater than two-thirds of the width of the web but less than the full web width.

According to a preferable embodiment of the invention, the slitting mechanism is operable to slit the web into three ribbons to form a central ribbon and an outermost ribbon on either side of the central ribbon and said means comprises a turner bar arrangement associated with each outermost ribbon configured so that, when each of the outermost ribbons is fed through its respective turner bar arrangement, they are spaced from the central ribbon in a lateral direction across the width of the press.

Advantageously, the folder includes a fixed datum for each ribbon spaced from each other across the width of the press, the web being pre-aligned with the folder so that the central ribbon is aligned with its fixed datum in the folder without having to move the central ribbon in a lateral direction across the width of the press after the web has been slit into ribbons. Preferably, the means for changing the position of the two outermost ribbons in a lateral direction across the width of the press is operable to change their position so that each of the outermost ribbons are aligned with their corresponding fixed datums in the folder, respectively.

In one embodiment, the folder includes two formers spaced from each other across the width of the press to receive respective ribbons spaced from each other across the width of the press, wherein the fixed datums in the folder are defined by the positions of each former.

In an alternative embodiment, the folder includes three formers spaced from each other across the width of the press to receive respective ribbons spaced from each other across the width of the press, wherein the fixed datums in the folder are defined by the positions of each former.

Advantageously, the means is operable to change the position of ribbons in a lateral direction across the width of the press so that a longitudinal centreline of each ribbon is aligned with its corresponding datum in each former through which said ribbon is to pass.

Preferably, the formers are immovably located in fixed relative positions in the folder.

In another embodiment, the print unit and the folder are configured so that the plane of the ribbons as they pass into the folder is substantially at right angles to the plane of the web as it passed through the print unit.

Conveniently, the fixed distance between the datum centreline of each former is equal to the distance between the datum centrelines of adjacent ribbons when the position of the ribbons has been changed in a direction across the width of the press. As the formers are fixed laterally — the distance between former centrelines being equal to the distance between ribbon centrelines — the problems associated with adjustable formers discussed earlier are avoided. Section register devices are no longer needed in the upper folder because path length correction is applied to every ribbon within the turner bar arrangement.

It will be appreciated from the foregoing that each turner bar arrangement slits the paper web into a number of ribbons, adjusts the path length of each ribbon so that the printed matter on it is aligned with the printed matter on the other ribbons and directs the ribbons to the upper folder in such a way that there is a lateral spacing between adjacent ribbon paths. The distance between adjacent ribbon centrelines is fixed, regardless of web width. This has a number of advantages. Path rollers used to convey ribbons between the turner bar arrangement and the upper folder can transport adjacent ribbons without any risk of overlap. The number of path rollers, and the overall size and cost of the upper press can therefore be reduced.

In one embodiment of the invention, the print unit and the folder are configured so that the plane of the ribbons as they pass into the folder is substantially at right angles to the plane of the web as it passed through the print unit, the slitting mechanism being operable to slit the web into three ribbons to form a central ribbon and an outermost ribbon on either side of the central ribbon and said means comprises a turner bar arrangement associated with each ribbon configured so that, when each ribbon is fed through its respective turner bar arrangement to turn each ribbon through 90 degrees to align it with the folder, each of the outer most ribbons are spaced from the central ribbon in a lateral direction across the width of the press.

The folder preferably includes a fixed datum for each ribbon which are spaced from each other across the width of the press by a distance which is greater than the width of a single ribbon, the turner bar arrangement for the central ribbon being located so that the central ribbon is aligned with its datum in the folder when the central ribbon has passed over its turner bar arrangement, the turner bar arrangement for each outer ribbon being spaced from the turner bar arrangement for the central ribbon so that each of the outermost ribbons are aligned with their datum in the folder once they have passed over their respective turner bar arrangements, thereby spacing the ribbons in a lateral direction across the width of the press.

According to the method of the invention, when the print unit and the folder are configured so that the plane of the ribbons as they pass into the folder is substantially at right angles to the plane of the web as it passed through the print unit, the method includes the step of feeding each of said ribbons through a respective turner bar arrangement to turn each ribbon through 90 degrees to align each ribbon with the folder, each turner bar arrangement being separated from each other by a predetermined distance so that the ribbons are spaced from each other in a lateral direction across the width of the press once the ribbons have been fed through their respective turner bar arrangement.

In one embodiment, the print unit and the folder are configured so that the plane of the ribbons as they pass into the folder is substantially at right angles to the plane of the web as it passed through the print unit and the method includes the step of slitting the web into three ribbons to form a central ribbon and an outermost ribbon on either side of the central ribbon and feeding each of said ribbons through a respective turner bar arrangement to turn each ribbon through 90 degrees to align each ribbon with the folder, each turner bar arrangement being separated from each other by a predetermined distance so that each of the outermost ribbons are spaced from the central ribbon in a lateral direction across the width of the press once the ribbons have been fed through their respective turner bar arrangement.

Preferably, the folder includes a fixed datum for each ribbon which are spaced from each other across the width of the press by a distance which is greater than the width of a single ribbon, the turner bar arrangement for the central ribbon being located so that the central ribbon is aligned with its datum in the folder when the central ribbon has passed over its turner bar arrangement, and the turner bar arrangement for each outer ribbon being spaced from the turner bar arrangement for the central ribbon so that each of the outermost ribbons are aligned with their datum in the folder once they have passed over their respective turner bar arrangements, thereby spacing the ribbons in a lateral direction across the width of the press.

Embodiments of the invention will now be described, by way of example only, with reference to Figures 3 to 7 of the accompanying drawings in which:- FIGURE 1 is a simplified perspective view of a conventional arrangement for moving one ribbon from a first position in which it is travelling side-by-side with an adjacent ribbon to a position in which the two ribbons are travelling back-to- back one above the other for entry of both ribbons into the same former in the folder; FIGURE 2 illustrates a perspective view of a conventional double width former arrangement;

FIGURE 3 is a simplified perspective view of a modified arrangement of turner bars according to an embodiment of the present invention; FIGURE 4 is a perspective view of a possible arrangement of separate path rollers for conveying individual ribbons with central support structures situated in the spacing between the ribbons;

FIGURE 5 illustrates a perspective view of a four-turner bar arrangement for a double width press in which both ribbons are moved laterally in a direction across the width of the press to maintain a constant ribbon centreline position; FIGURE 6 illustrates a perspective view of a double width former arrangement according to the invention; and

FIGURE 7 illustrates a simplified perspective view of another modified arrangement of turner bars for use in a press in which the folder is orientated at right angles to the printing units and each ribbon is turned over a single turner bar.

Referring now to the drawings, a first embodiment of the invention will now be described with reference to Figure 3 which shows a portion of the path of a web of print medium 7 between a print unit (not shown) and a folder (not shown). It illustrates how a turner bar assembly, comprising turner bars 9,10, may be configured to introduce lateral spacing in a direction across the width of the press between a pair of ribbons 8a,8b slit from a single web 7 and in which the ribbons 8a,8b remain side-by-side once the lateral spacing has been introduced, i.e. the ribbons 8a,8b, are either coplanar or they each lie in separate spaced parallel planes in which the ribbons do not overlap each other.

Ribbon 8a travels over the first and second turner bars 9,10, which are positioned with their axes parallel to each other but at 45 degrees to the direction of travel of the ribbons, in a direction indicated by arrow "B". When ribbon 8a has passed over the first turner bar 9, it is travelling at right angles to the direction of travel of the unturned ribbon and passes beneath, or across, the unturned ribbon 8b, in the direction of arrow "C". When ribbon 8a has passed over the second turner bar 10, it is travelling in its original direction adjacent to, but on the opposite side of, the unturned ribbon 8b, in the direction of arrow "D". By spacing each of the turner bars 9,10 by a distance which is greater than the width of the web 7, it will be appreciated that the edge 11 of the turned ribbon 8a is spaced from the edge 12 of the unturned ribbon 8b by a distance indicated by "X", in Figure 3.

When the turned ribbon 8a has passed over the second turner bar 10, the ribbons 8a,8b each lie in a different plane. However, this is easily adjusted by passing the turned ribbon 8a beneath at least one path roller 13 before bringing both ribbons 8a, 8b over the same path roller 14 so that they are now both travelling side-by-side with a space "X" between them in a direction across the width of the press.

Figure 3 represents the arrangement in a double width press in which the web 7 is slit into two ribbons. However, it will be appreciated that the arrangement may be modified for a triple width press in which the web 7 is slit into three ribbons. Spacing may be introduced between the central and each of the outer ribbons by passing each of the outer ribbons over a pair of first and second turner bars respectively, as has been described with reference to a single ribbon in Figure 3. It will be appreciated that each of the outer ribbons will cross or pass beneath the unturned ribbon in opposite directions and, once turned, will be on opposite sides of the unturned ribbon.

As mentioned above, the introduction of a lateral spacing between ribbons 8a,8b positioned side-by-side across the width of the press enables support frames 15 to be introduced between ribbons 8a,8b which, in turn, allows short, low inertia path rollers 16 to be employed, as illustrated in Figure 4. It also enables additional equipment, such as ribbon feeding equipment (not shown), to be mounted on the central support frames 15 between ribbons 8a,8b. In a further modification, strengthened central support frames 15 located in the space between ribbons 8a,8b could eliminate the requirement for outer support frames 17 altogether. Cantilevered path rollers 16 would then afford excellent access to the ribbons 8a,8b.

As has been previously explained, in addition to providing spacing between ribbons it is desirable to maintain a constant distance or pitch between ribbon centrelines irrespective of the web width and position the ribbons so that the centrelines of each ribbon line up with the centreline of each former through which they are to pass, without having to re-position the formers each time the web width is changed. This can be achieved if, in the case of two ribbons, the position of both rather than just one of them is changed in a lateral direction across the width of the press so that the centreline of each ribbon corresponds to the centreline of the former through which it is to pass irrespective of web width.

Referring to Figure 5, there is shown a double width press arrangement in which each ribbon is passed over a pair of turner bars 18,19. Each pair of turner bars 18,19 are positioned in a similar way to that described with reference to the turner bars described with reference to Figure 3, the turner bars 18,19 of each pair being spaced from each other so that, when the ribbons 20,21 have passed over their respective second turner bars 18b, 19b, they are travelling in their original direction but are spaced from each other in a lateral direction across the width of the press by distance "X". It will be appreciated that each ribbon 20,21 is travelling in opposite directions one above the other as they pass between their respective first and second turner bars 18,19 and that the positions of the ribbons is reversed when they have each passed over their second turner bars 18b,19b.

In the case of a triple width press in which there are three ribbons, the web is pre-aligned so that its longitudinal centreline, which corresponds to the longitudinal centreline of the central ribbon when it has been slit, is in alignment with its corresponding datum in the central former through which it is to pass. Therefore, it is only necessary to change the positioning of each of the outermost ribbons so that their ribbon centrelines are in alignment with their corresponding datums in their respective formers through which they are to pass. The lateral distance through which the ribbons move changes in dependence on the web width so that the ribbon centrelines will always be aligned with their respective datum in the folder.

By moving both ribbons laterally in this way, the ribbons are all positioned so that their centrelines are fixed with respect to the formers which receive them irrespective of the web width, and there is no need to re-position the formers each time a different web width is used. The formers 24,25 may therefore be immovably located in fixed lateral positions spaced from each other across the width of the press, such as is illustrated in Figure 6. As can be seen from Figure 6, each ribbon 20 ,21 is supported across its entire width.

In a conventional press, the plane of the web as it passes upwardly through the print unit is parallel to the plane of the ribbons as they pass downwardly through the folder. However, a modified configuration of press has the folder oriented at right angles to each of the print units so that the ribbons must be turned through 90 degrees to orientate them before they enter the folder. Such a configuration is described in the Applicant's own co-pending UK patent application No. 0408085.9. In this configuration, it will be appreciated that all the ribbons must be turned but that it is only necessary to turn them once, through 90 degrees, by passing each ribbon over a single turner bar. By altering the spacing between adjacent turner bars 28,29, the resulting spacing between adjacent turned ribbons 26,27 may be adjusted so that the distance "S" between ribbon centrelines 26a,27a is kept constant irrespective of the width of the web. A double width press arrangement configured in this way and in which two ribbons 26,27 are each turned through 90 degrees is shown in Figure 7. To maintain register between ribbons 26,27, one of them is passed over a path roller 29a, whose position is adjustable in the direction of arrow "Z" after it has been passed over its turner bar 29.

Many modifications and variations of the invention falling within the terms of the following claims will be apparent to those skilled in the art and the foregoing description should be regarded as a description of the preferred embodiments only.

Claims

1. A rotary printing press comprising a print unit for applying ink to a web of print medium passing through the unit, a folder located adjacent to the print unit to receive the printed web from the print unit and, a slitting mechanism located between the print unit and the folder to longitudinally slit the web into a plurality of ribbons for entry into the folder, wherein the press includes means for changing the position of at least one ribbon relative to the or each adjacent ribbon so that the edges of adjacent ribbons formed by slitting the web are spaced apart from each other in a lateral direction across the width of the press before entering the folder.

2. A rotary printing press according to claim 1, wherein said means is configured so that the ribbons all lie in the same plane before and after the position of at least one ribbon has been changed.

3. A printing press according to claim 1 or 2, wherein the folder includes a fixed datum for each ribbon spaced from each other across the width of the press and the slitting mechanism is operable to slit the web into two ribbons, wherein said means for changing the position of at least one ribbon changes the position of both ribbons in a lateral direction across the width of the press and is operable to change their position so that each ribbon is aligned with its corresponding fixed datum in the folder.

4. A printing press according to claim 3, wherein the distance through which the ribbons move to align them with their corresponding fixed datums in the folder depends on the width of the web.

5. A printing press according to any of claims 1 to 4, wherein said means comprises a turner bar arrangement associated with each ribbon whose position is to be changed, the arrangement being such that when each ribbon is fed through its respective turner bar arrangement, the original direction of travel of said ribbons is maintained but they are spaced from each other in a lateral direction across the width of the press.

6. A printing press according to claim 5, wherein the turner bar arrangement comprises first and second turner bars having their axes parallel to each other and 45 degrees to the direction of travel of the ribbons so that each ribbon whose direction is to be changed is turned twice by passing it over the first and second turner bars.

7. A printing press according to claim 6, wherein only one ribbon is turned and the turner bars are located such that a path followed by the turned ribbon extends across the unturned ribbon as the turned ribbon travels between the first and second turner bars.

8. A printing press according to claim 7, wherein the first and second turner bars are spaced from each other by a distance greater than the width of the web.

9. A printing press according to claim 1 or claim 2, wherein the slitting mechanism is operable to slit the web into three ribbons to form a central ribbon and an outermost ribbon on either side of the central ribbon and said means comprises a turner bar arrangement associated with each outermost ribbon configured so that, when each of the outermost ribbons is fed through its respective turner bar arrangement, they are spaced from the central ribbon in a lateral direction across the width of the press.

10. A printing press according to claim 9, wherein the folder includes a fixed datum for each ribbon spaced from each other across the width of the press, the web being pre-aligned with the folder so that the central ribbon is aligned with its fixed datum in the folder without having to move the central ribbon in a lateral direction across the width of the press after the web has been slit into ribbons, wherein said means for changing the position of the two outermost ribbons in a lateral direction across the width of the press is operable to change their position so that each of the outermost ribbons are aligned with their corresponding fixed datums in the folder, respectively.

11. A printing press according to claim 10, wherein the distance through which the ribbons move to align them with their corresponding fixed datums in the folder depends on the width of the web.

12. A printing press according to any of claims 9 to 11, wherein the turner bar arrangement comprises a pair of first and second turner bars, each pair being associated with an outermost ribbon respectively, the first and second turner bars of each pair having their axes parallel to each other and 45 degrees to the direction of travel of the ribbons.

13. A printing press according to claim 12, wherein the turner bars of each pair are located such that a path followed by each of the outermost turned ribbons extends across the unturned central ribbon as each of the outermost ribbons travel between their first and second turner bars.

14. A printing press according to claim 13, wherein the turner bars of each pair are configured so that each of the outermost ribbons moves to opposite sides of the unturned central ribbon when the outermost ribbons have been turned by their first and second turner bars.

15. A printing press according to claim 13, wherein each ribbon travels across the unturned ribbon in opposite directions as they travel between their associated first and second turner bars.

16. A printing press according to claim 15, wherein the first and second turner bars of each pair are spaced from each other by a distance which is greater than two-thirds of the width of the web but less than the full web width.

17. A printing press according to any of claims 3 to 8, wherein the folder includes two formers spaced from each other across the width of the press to receive respective ribbons spaced from each other across the width of the press, wherein the fixed datums in the folder are defined by the positions of each former.

18. A printing press according to any of claims 9 to 16, wherein the folder includes three formers spaced from each other across the width of the press to receive respective ribbons spaced from each other across the width of the press, wherein the fixed datums in the folder are defined by the positions of each former.

19. A printing press according to claim 17 or claim 18, wherein the means is operable to change the position of ribbons in a lateral direction across the width of the press so that a longitudinal centreline of each ribbon is aligned with its corresponding datum in each former through which said ribbon is to pass.

20. A printing press according to any of claims 17 to 19, wherein the formers are immovably located in fixed relative positions in the folder.

21. A printing press according to any of claims 1 to 4, wherein the print unit and the folder are configured so that the plane of the ribbons as they pass into the folder is substantially at right angles to the plane of the web as it passed through the print unit.

22. A printing press according to claim 1 or claim 2, wherein the print unit and the folder are configured so that the plane of the ribbons as they pass into the folder is substantially at right angles to the plane of the web as it passed through the print unit, the slitting mechanism being operable to slit the web into three ribbons to form a central ribbon and an outermost ribbon on either side of the central ribbon and said means comprises a turner bar arrangement associated with each ribbon configured so that, when each ribbon is fed through its respective turner bar arrangement to turn each ribbon through 90 degrees to align it with the folder, each of the outer most ribbons are spaced from the central ribbon in a lateral direction across the width of the press.

23. A printing press according to claim 22, wherein the folder includes a fixed datum for each ribbon which are spaced from each other across the width of the press by a distance which is greater than the width of a single ribbon, the turner bar arrangement for the central ribbon being located so that the central ribbon is aligned with its datum in the folder when the central ribbon has passed over its turner bar arrangement, the turner bar arrangement for each outer ribbon being spaced from the turner bar arrangement for the central ribbon so that each of the outermost ribbons are aligned with their datum in the folder once they have passed over their respective turner bar arrangements, thereby spacing the ribbons in a lateral direction across the width of the press.

24. A method of controlling a rotary printing press comprising a print unit for applying ink to a web of print medium passing through the unit, a folder located adjacent to the print unit to receive the printed web from the print unit and, a slitting mechanism located between the print unit and the folder, the method including the step of longitudinally slitting the web into a plurality of ribbons for entry into the folder and, changing the position of at least one ribbon relative to the or each adjacent ribbon so that the edges of adjacent ribbons are spaced apart from each other in a lateral direction across the width of the press before entering the folder.

25. A method according to claim 24, wherein the folder includes a fixed datum for each ribbon spaced from each other across the width of the press, the method including the step of slitting the web into two ribbons and changing the position of both ribbons in a lateral direction across the width of the press so that each ribbon is aligned with its corresponding fixed datum in the folder.

26. A method according to claim 24, wherein the step of slitting the web includes the step of slitting it into two ribbons and the step of changing the position of at least one ribbon includes the step of passing one ribbon over first and second turner bars, having their axes parallel to each other and 45 degrees to the direction of travel of the ribbons, so that the original direction of travel of said ribbon is maintained but it is spaced from the unturned ribbon in a direction across the width of the press.

27. A method according to claim 24, wherein the step of slitting the web includes the step of slitting it into three ribbons to form central ribbon and an outermost ribbon on either side of the central ribbon, the method including the step of feeding each of the outermost ribbons through their respective turner bar arrangements to space each of the outermost ribbons from the central ribbon in a lateral direction across the width of the press.

28. A method according to claim 27, wherein the folder includes a fixed datum for each ribbon spaced from each other across the width of the press, the web being pre-aligned with the folder so that the central ribbon is aligned with its fixed datum in the folder without having to move the central ribbon in a lateral direction across the width of the press after the web has been slit into ribbons, the method including the step of changing the position of each of the outermost ribbons in a direction across the width of the press so that they are aligned with their corresponding fixed datums in the folder, respectively.

29. A method according to claim 28, wherein the step of changing the position of at least one ribbon includes the step of passing one outermost ribbon over a first pair of turner bars having their axes parallel to each other and 45 degrees to the direction of travel of the ribbons and, passing the other outermost ribbon over a second pair of turner bars having their axes parallel to each other and 45 degrees to the direction of travel of the ribbons, so that the original direction of travel of the outermost ribbons is maintained but they are spaced from the unturned ribbon in a direction across the width of the press.

30. A method according to claim 24 or claim 25, wherein the print unit and the folder are configured so that the plane of the ribbons as they pass into the folder is substantially at right angles to the plane of the web as it passed through the print unit and the method includes the step of feeding each of said ribbons through a respective turner bar arrangement to turn each ribbon through 90 degrees to align each ribbon with the folder, each turner bar arrangement being separated from each other by a predetermined distance so that the ribbons are spaced from each other in a lateral direction across the width of the press once the ribbons have been fed through their respective turner bar arrangement.

31. A method according to claim 24, wherein the print unit and the folder are configured so that the plane of the ribbons as they pass into the folder is substantially at right angles to the plane of the web as it passed through the print unit, the method including the step of slitting the web into three ribbons to form a central ribbon and an outermost ribbon on either side of the central ribbon and feeding each of said ribbons through a respective turner bar arrangement to turn each ribbon through 90 degrees to align each ribbon with the folder, each turner bar arrangement being separated from each other by a predetermined distance so that each of the outermost ribbons are spaced from the central ribbon in a lateral direction across the width of the press once the ribbons have been fed through their respective turner bar arrangement.

32. A method according to claim 31, wherein the folder includes a fixed datum for each ribbon which are spaced from each other across the width of the press by a distance which is greater than the width of a single ribbon, the turner bar arrangement for the central ribbon being located so that the central ribbon is aligned with its datum in the folder when the central ribbon has passed over its turner bar arrangement, and the turner bar arrangement for each outer ribbon being spaced from the turner bar arrangement for the central ribbon so that each of the outermost ribbons are aligned with their datum in the folder once they have passed over their respective turner bar arrangements, thereby spacing the ribbons in a lateral direction across the width of the press.

33. A press substantially as hereinbefore described with reference to the accompanying drawings.

34. A method of controlling a printing press substantially as hereinbefore described.