In a typical printing press a web of substrate, such as newsprint, will pass through one or more printing units where printing takes place and will subsequently be passed together with a number of other printed webs to a folder where the webs are cut arrange and folded to produce, for example, a newspaper.

For printing in full colour on each side of the substrate the web generally passes through four printing units, each printing unit printing one of four colour images, generally yellow, cyan, magenta and black.

Typically these four printing units are arrange one on top of the other in a tower or four high. The web runs up through the tower, from a roll below the tower. The printed web is directe from the top of the tower to a folder.

For any particular print run a press operator may wish, for example, to select which tower or units within the tower to use and which of a number of folders to use.

The operator may also wish to select the number of colours that are printed for a particular web, for example, for a

newspaper the operator may wish to select only black, single colour printing for some pages, or perhaps two colour printing.

To enable the press operator to have flexibility, the operator must be able to select how the various individual webs are threaded through the press rollers to ensure that the webs are correctly printed and correctly passed to the selected folder.

Printing units may also be arrange in other configurations such as eight or ten cylinder satellite arrangements. These may also be variously threaded depending upon requirements.

One known web lead system comprises a plurality of endless tapes arrange on one side of the press. An end of a web to be threaded can be attache to the tape and the tape driven to draw the web through the press. To select the direction of threading of the web, the web must be periodically removed from the tape to which it is attache at that. time and reattached to another of the continuous tapes. This is labour intensive and relies upon the press operators attaching the web to the correct tape at any point in the threading procedure.

In an alternative automate web lead system a plurality of chain tracks are arrange along one side of the press. A length of chain may be driven through the chain tracks by drive means arrange at intervals along the tracks. The chain is connecte by, for example, a hook or

other suitable connection to the web. Passage of the chain along the chain tracks draws the web through the press. To allow the direction of passage along the tracks to be selected a points system is provided, each point allowing branching from one incoming track to a choice of two outgoing tracks. The choice of outgoing track is selected by operation of a solenoid moving a finger within the points to one of two positions.

This known system allows automation of the web lead system. However, a large number of points are required to provide any significant level of track selection to accommodate possible variations in web threading requirements. The points are directional. That is to say the points enable a selection of one of two tracks when the chain is passing in a particular direction. In some cases however it might be desired to thread a web in the opposite direction, and to allow for this additional sets of points and tracks to allow operation in the reverse direction are required.

According to the invention there is provided a web lead system for a printing press comprising a plurality of lengths of web lead track and a plurality of direction selection means for selectively connecting said lengths of web lead track to each other wherein said direction selection means comprises a rotatable member having a plurality of differently orientated web lead passages selectably connectable between a plurality of lengths of

web lead track by rotation of said rotatable member.

The preferred direction selection means is a turntable comprising: a rotatable member rotatable around a rotary axis and comprising a plurality of web lead passages; at least one locating member; said rotatable member further comprising a plurality of locating member receiving means; said at least one locating member being movable into and out of said locating member receiving means; said at least one locating member and said locating member receiving means being arrange to provide a plurality of positions of said rotatable member at which at least one said locating member is locatable in a said locating member receiving means so as to prevent rotation of said rotatable member and further being arrange such that withdrawal of one or more of said locating members from said locating member receiving means enables said rotatable member to be rotated to a next indexed position; means for rotating said rotatable member; means for moving said locating member into and out of said locating member receiving means.

Preferably the rotatable member rotates to a next indexed position under the control of one or more of the said locating members.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying

drawings in which:- Figure 1 shows a plan view of a section of a part of a press with a web lead system of the present invention in operation; Figure 2 is a cross-section through a chain track and chain.

Figure 3 is a perspective view of a turntable in accordance with the present invention; Figures 4 and 5 are reverse views of the rotatable member of the turntable of Figure 3 in a first and a second rotational position; Figures 6 and 7 are reverse views of an alternative turntable embodiment; Figure 8 is a front view of a turntable of the present invention with an outer annular rotating member; Figure 9 is a schematic view of the operation of a prior art system of chain and web control using points; Figure 10 is a schematic view of the operation of a web lead system of the present invention equivalent to the system of Figure 9; Figure 11 is a further enlarged view of a part of the system of Figure 10; Figure 12 is a cross-sectional view of an alternative embodiment of a turntable of the present invention; Figure 13 is a view of the cross-section of the locating member receiving means of the turntable of Figure 12;

Figures 14 and 15 are cross-sectional views of two further embodiments of the turntable of the present invention; Figure 16 is a cross-sectional view of a further embodiment of the turntable of the present invention.

Figure 17 is a cross-sectional view of a further embodiment of the turntable of the present invention.

Figure 18 is a plan view of a track pattern arrangement of a turntable of the present invention.

Figure 1 shows in plan view the threading of a web 4 through a section of a press. The section of press comprises a plurality of roller 6 arrange between parallel vertical frame 16. During the printing operation the passage of the web 4 through the section of the press is governed by the way that the web 4 is threaded between the rollers 6. To thread the web 4 through the press a kite 12, a plastic triangular member, is attache to the leading edge of a roll of the sheet material forming the web 4. A chain 10 is carried in a system of chain tracks 8. The chain 10 carries a kite hook 14 as shown in cross-section in Figure 2.

The chain 10 is similar to the arrangement of a bicycle chain with a plurality of links and has a predetermined length. The chain 10 may be driven along the system of chain tracks 8 by means of a plurality of chain drive units which are spaced such that the chain 10 is always under drive by at least one chain drive unit.

To determine the way the web 4 is threaded through the press, means is provided to selectively connect lengths of the chain tracks 8. In the present invention selective connection is provided by turntables 2. As shown in Figure 1 the turntables 2 and the chain track 8 may be mounted to the vertical frames 16 by way of support plates 18.

Figure 3 is a perspective view of a turntable 2 according to the present invention. A rotatable member 20 comprises a plurality of chain passages. As shown in Figure 3 there is one diametral chain passage 22. On either side of the diametral chain passage 22 are chain passages 24 having respective entrances and exits at 45° from the diametral chain passage 22. Eight lengths of chain track 8 are arrange rotationally extending from the rotatable member 20 at 45° intervals. Rotation of the rotatable member 20 through steps of 45° allows any length of inlet track 8 to be selectively connecte to any one of three outlet tracks 8 in the diametral direction, or exiting. to the left or right. The tracks do not intersect and turntable 2 therefore allows three chains 10 to pass through the turntable simultaneously. Other patterns, including intersecting tracks, are possible and these may also allow more than one chain to pass at a time.

Moreover, the turntable, unlike the prior art points, is non-directional and operates equally effectively from any inlet direction.

In the preferred embodiment shown in Figure 3 and

further described by reference to Figures 3,4 and 5 means are provided to ensure that the rotatable member 20 is accurately located with respect to the radiating track sections 8 in any operating position. Moreover the rotation of the rotatable member 20 is accurately controlled and indexed to allow stepwise rotation through rotational steps of 45°.

The turntable 2 of Figure 3 is fitted with two linear solenoids 28 and 30 and a rotary solenoid 32. The rotary solenoid 32 is connecte to the rotational member 20 via a sprag clutch. When power is applied to the rotary solenoid 32 the sprag clutch supplies drive to the rotational member 20. The sprag clutch slips in the opposite direction to allow the solenoid shaft of the rotary solenoid to return under spring action to the starting position when power is removed. The turntable is preferably fitted with a proximity sensor and a pair of sensor targets are provided on the rotational member 20 at 180° from each other. As the rotational member is symmetrical this provides for two zero datum positions. Starting from a zero datum position the rotational member can be indexed to align the chain passages 22,24 with the selected inlet and outlet tracks 8.

The first linear solenoid 28 is associated with a first locating pin 29 and the second linear solenoid 30 is associated with a second locating pin 31. Figure 4 is a view from the reverse side of the rotational member 20 and

shows the pins 29 and 31 each located in one of a plurality of arcuate slots 36. With both pins 29 and 31 located in the slots 36a and 36b as shown in Figure 4 the rotational member 20 is retained against movement in both the clockwise and anticlockwise direction.

From the position shown in Figure 4 the rotational member 20 can be caused to rotate through 45° to the position shown in Figure 5 by the following sequence of operations. Firstly power is applied to the first linear solenoid 28. The first pin 29 is thereby retracted, withdrawing from the slot 36b. Secondly, power is applied to the rotary solenoid 32. This causes the rotational member 20 to rotate in an anticlockwise direction as seen from the rear view of Figures 4 and 5. The rotatable member 20 remains under the control of the second pin 31 and thus rotation of rotatable member 20 stops when the pin 31 abuts the end of the arcuate slot 36a in which it is engage. At that time power is removed from the first linear solenoid 28 and the first pin 29 is inserted into the arcuate slot 36a as shown in Figure 5 under spring action. Power is then removed from the rotary solenoid 32 and the solenoid shaft rotates back to its initial start position under spring action. The turntable 2 is now in the position shown in Figure 5.

The mechanism is now ready to index round to the next position if required. To do this the second solenoid 30 is energised and the second pin 31 thereby retracted while the

first pin 29 remains in the slot 36a during the cycle. The pins 29 and 31 can be further retracted alternately until the desired position is reached. The pins 29 and 31 are arrange and operated such that one pin is always fully engaged in an arcuate slot 36. This ensures positional accuracy and thus track alignment. It maintins positive turntable control at all times, both under power and when inactive.

Other suitable linear drive means may be used for the pins 29,31 and other suitable rotary drive means for the rotational member 20. The drive means may be hydraulic, pneumatic, electronic, or electromagnetic.

Figures 6 and 7 show an alternative embodiment of the turntable 2 which allows indexing by steps of 22M° by the provision of eight slots.

Whilst the pins 29 and 31 in Figures 4 and 5 are set 45° apart so that both pins may be in one single slot 36 or may be located at the opposite ends of adjacent slots, it is possible for pins 29 and 31 to be spaced further apart as shown in Figures 6 and 7. In this case pin 29 in slot 36e controls the motion of the rotational member 20 between the positions shown in Figures 6 and 7 as pin 31 engages with slot 36f after disengaging from the preceding slot.

For 2n indexed positions in one rotation n slots may be provided, the slots having a length equivalent to an arc of eo plus a pin diameter, where 6 = 360/2n. The slots are spaced apart by a length equivalent to arc length eo less a

pin diameter. The retaining pins 29 and 31 may be spaced apart having centres at each end of an arc of (2m-1) @° where m is a whole number from 1 to n.

Alternatively, but less preferably, it would be possible to arrange two sets of slots lying on concentric circles centred on the axis of rotation of the rotational member 20, the first pin 29 being arrange to locate in one set of slots and the second pin 31 being arrange to locate in the second set of slots.

In another alternative embodiment (not shown) the pins may be arrange for insertion in a radial direction into slots formed in a cylindrical wall of the rotatable member 20.

In each case the pin and slot location may be selected to provide that rotation from a first to a second indexed position can take place under control of one pin and preferably at each indexed point of rotation both pins may be inserted into respective slots to prevent rotation of the rotatable member 20 in either direction.

More than two pins may be provided, for example two sets of pins set 180° apart, if this is considered desirable.

Any shape of pin or locating member may be used provided that these can be withdrawn and inserted in such a manner as to allow the rotatable member 20 to be indexed around always under the control of at least one locating member.

The front face of the turntable may have any pattern of track passages and track connections. A symmetrical arrangement of non-intersecting tracks such as that shown in Figure 3 is preferred.

Increasing the number of chain passages enables an increased number of chains to be carried and an increased number of combinations to be achieved. However, this may also require an increase in the size of the rotatable member 20. For a typical application with a three passage rotatable member 20 as shown in Figure 3 the rotatable member may have a diameter of about 10cm. To carry more non-intersecting passages, it would be necessary to increase the diameter. An alternative approach is to provide a further outer rotatable member 40 incorporating a number of chain passages such as that shown in Figure 8.

With both the rotatable member 20 being able to be indexed around to different positions and the outer rotatable member 40 being able to be indexed independently of the inner turntable, a plurality of different arrangements of chain passages can be provided for up to six chains simultaneously.

Some of the avantages of the present invention are shown by comparison of a prior art web lead system shown in Figure 9 and a web lead system of the present invention shown in Figures 10 and 11. Figure 9 shows a prior art method of chain and web control in which four webs 4 run from the right hand side of the figure as shown by the

arrows running towards a folder (not shown). A fifth web 4a is shown entering from the left hand side of the figure (from a printing unit there) and joining in the run to the folder. A plurality of sets of points 50 are used to direct the passage of the chain 10 for each web lead.

The same arrangement of webs as in Figure 9 is shown in Figure 10. In place of the plurality of points 50 of Figure 9 seven turntables 2 are arrange in two vertical stacks, one stack of four and one stack of three. Each turntable 2 is provided with four connections set at 90°.

The turntable 2 is of the type described above with reference to Figures 3,4 and 5 providing indexed positions at 45° spacings and having the web lead passage pattern of Figure 3. Alternative web lead passage patterns are possible. For example a second diametral passage 22 could be provided at right angles to the first diametral passage allowing two chains to pass at any of the turntable settings as shown in Figure 18.

The turntables 2 provide a number of avantages over points. Fewer turntables are required to perform the same function. They can be readily mounted on cheaper mounts than the plurality of points of Figure 9. By grouping the turntables together as shown in Figure 10 an incoming chain can be caused to jump through more than one level. So the web 4a entering from the left hand printing stack may be caused to follow one of the paths shown as a broken line in Figure 10. This is not possible with the prior art system

shown in Figure 9. Providing turntables in groups or stacks thus provides particular advantages.

Further details of the arrangement of Figure 10 can be seen by reference to Figure 11 which shows part of the left hand portion of the system of Figure 10 with the web lead chains passing through the turntables being driven by chain drive units 60.

An alternative turntable arrangement is shown in Figure 12. A single lug 70 is movable in an axial direction into and away from an annular ring 72 which has a tooth profile shown in Figure 13 with a series of raised portions 74 and a series of gaps 75. The lug 70 may be withdrawn from the ring 72 and allowed to return under spring action into the next adjacent gap 75 as rotatable member 20 is caused to rotate. The next indexed position will be reached when the lug 70 locates in the next gap 75.

Further alternative embodiments are shown in Figures 14 and 15. The rotatable member 20 is provided with a plurality of detents 80 formed in either an outer or an inner cylindrical wall of the rotatable member 20. Pin 81 may be caused to be withdrawn and advanced by a suitable linear drive means 82, for example withdrawn by activation of a solenoid and advanced by spring action on deactivation of the solenoid. Withdrawal of the pin 81 allows rotation of the rotatable member 20 under action of a rotational driver until the next indexed position is reached where the retaining pin 81 under spring action locates in the next

detent 80.

A further embodiment is shown in Figure 16. The rotatable member 20 is arrange with a saw tooth profile on its outer circumference. A spring loaded pawl 83 may be moved away from the outer circumference of the saw toothed profile and returned under spring action to allow rotation of the turntable in an anticlockwise direction as viewed in Figure 16.

Figure 17 shows a further embodiment of the turntable in which a spring loaded plunger 84 co-operates with a fan shaped arrangement on a circular face of the rotatable member 20. The spring loaded plunger 84 may be driven by suitable drive means away from contact with the fan shaped face of the rotatable member 20 and returned under spring action to allow the rotatable member 20 to be stepwise rotated in an anticlockwise direction as viewed in Figure 17.

The above embodiments of figures 12 to 17 enable control. of the rotatable member 20 via operation of a single drive means acting upon a single locating member with spring return of the locating member, thus reducing the number of components of the turntable.

A web lead system incorporating the turntables 2 above described allows remote operation. The operator may determine, for example, by means of a suitable computer program, the settings for the various turntables and the turntables may be indexed to the required positions under

remote control. Preferably the turntables incorporate a location detection means which operates at at least one of the stepwise locations of the turntable to provide a zero datum reference. The turntables 2 may be rotated stepwise to the zero datum reference location and thence stepwise to the required position, as described by way of example with reference to the embodiment of Figure 3.

While the embodiments have been described with reference to a length of chain as the web lead which may be driven along the web lead tracks, lengths of other flexible material may be used and may be driven along a track by suitable means.