GB2490029A

GB2490029A - Flexographic plate mounting apparatus

Info

Publication number: GB2490029A
Application number: GB201206313A
Authority: GB
Inventors: Graham Littler
Original assignee: J M HEAFORD Ltd
Current assignee: J M HEAFORD Ltd
Priority date: 2011-04-14
Filing date: 2012-04-10
Publication date: 2012-10-17
Anticipated expiration: 2032-04-10
Also published as: GB201206313D0; GB2490029B; GB201106348D0

Abstract

Apparatus for mounting flexible printing plate 40 to a cylinder 20 comprises a table 12 mounted below a support frame 16 onto which a cylinder 20 is rotationally mounted; the support frame 16 and cylinder 20 can be raised and lowered relative the table 12; the table 12 has a compressible upper surface and a portion 26 which is transparent or includes an aperture to enable viewing of the cylinder 20 and the printing plate 40 by cameras 30, 31 mounted below the table 12; the table 12 is movable below the cylinder 20 in a direction perpendicular to the cylinder axis.

Description

I

FLEXOGRAPHIC PLATE MOUNTING APPARATUS

TECHNiCAL FIELD

The present invention relates to apparatus particularly but not exclusively for mounting a flexible printing plate, commonly termed a flexographic plate, onto a cylinder. The terms "flexible printing plate" and "flexographic plate" will be used interchangeably herein.

BACKGROUND

In the printing industry, flexographic plates formed on one surface with raised print areas, namely required text and images for printing, and lowered non-print areas, called floor or relief areas, have to be mounted with accuracy either directly onto press cylinders, or onto cylindrical sleeves mounted on mandrels, which are subsequently transferred onto press cylinders. For simplicity, both such press cylinders and sleeves will hereinafter be referred to as "cylinders". The machines to effect such mounting vary in size and complexity to suit different print widths and types of press cylinder and sleeve mandrels.

The accuracy of mounting is particularly important in the case of photopolymer printing plates where the individual colours of an image, yellow, red, blue (cyan), black etc. are overlaid to produce a finished image. To ensure accuracy of alignment on the cylinder, each printing plate has two or more registration marks, usually crosses or dots, which are precisely positioned in the same place on each plate of the image set. Thus, on the mounting machine, the mounting operation has to be repeated with precision for each of the plates carrying the image portions for each colour, four or more colours being typical.

Typically, the cylinder is rotatably mounted in a support frame, and the flexographic plate, with print surface uppermost is either applied from above, by being draped over the top of the cylinder manually, as is common in the case of shorter width cylinders/printing plates or is offered up tangentially to the top of the cylinder from a support table, particularly in the case of wider cylinders. Adhesion of the plate to the cylinder is typically by double sided adhesive tape, which is applied to the cylinder before mounting of the plate and will have release paper at least partially removed just prior to application of the plate to the cylinder. Typically, also, accurate registration of the marks on the plate with locations on the cylinder is achieved by the mounting machine including cameras and a display screen to which the cameras are operatively linked. Usually, video cameras and a video monitor are employed. The cameras, of which there are at least two, are mounted above the cylinder, usually directed vertically downwards towards the top surface of the cylinder.

These provide, on the monitor, a magnified image of the registration marks so the alignment of these marks with required locations on the cylinder can be achieved, if necessary by manipulation of the plate by the operator before the plate is finally positioned and adhered.

A flexible printing plate mounting machine of the type just described is disclosed in US 5,488,781. It shows a machine with a printing plate support table which is movable horizontally in a direction perpendicular to the shaft of the printing cylinder in order that the printing plate can be supported thereby and fed onto the top of the cylinder.

Once the flexographic plate is initially applied to the cylinder in correct alignment its mounting is completed by rotating the cylinder, along with removal of remaining release paper from the adhesive tape. During this process and/or afterwards the flexible plate has to be smoothed down onto the cylinder, by hand or using a roller, to remove air bubbles to ensure that the surface for printing is as even as possible around the cylindrical exterior.

The aforesaid type of apparatus and method of mounting is widely used throughout the print industry. Sometimes there are minor differences such as offset cameras or differing designs of plate support tables, which may be displaceable horizontally and/or capable of being raised and lowered while supporting the flexographic plate.

Apparatus for mounting a flexographic printing plate onto a cylinder by placing the printing plate with raised print areas facing downwards onto a support table and lowering the cylinder into contact with the back of the plate is proposed in the US 5,676,058. The support table is fixed in position. A transparent portion extends across the table to enable alignment of registration marks on the plate with a centreline marked across the transparent area. Cameras are mounted below the table and directed upwards at the transparent portion to enable the alignment to be achieved by viewing the camera image on a display monitor and manual adjustment of the plate before the cylinder is lowered.

After the cylinder has been lowered into contact with the plate and is adhered to the plate, the cylinder is raised from the support table sufficient to be rotated so that the plate can be roIled onto the surface of the cylinder. A pressure roller is brought into a position adjacent to the cylinder to provide, with the cylinder, a pressure nip through which the fiexographic plate passes as it is wound onto the cylinder.

OBJECT OF INVENT1ON An object of the invention is to provide an improved flexible plate mounting machine and methodology whereby the mounting of the flexible printing plate onto the cylinder can be achieved with greater ease, with less skill and manual intervention, hence less time, and with greater reliability than hitherto.

BRIEF SUMMARY OF THE DISCLOSURE

The present invention provides apparatus for mounting a flexible printing plate (or other flexible sheet material) onto a cylinder, said apparatus comprising a support frame for rotatably mounting the cylinder to which the flexible printing plate or similar is to be applied, a substantially horizontally arranged support table mounted below the support frame and providing a surface for supporting the flexible printing plate prior to and during its application to the cylinder, the support frame being mounted to a support structure to allow the cylinder to be lowered onto the support table or raised and supported above the support table, as required, and the support table being movable below the cylinder in a direction perpendicular to the cylinder axis and having a compressible upper surface as well as a portion which is transparent or apertured or recessed, and at least one camera mounted below the support table and directed upwards to view the transparent or apertured or recessed portion of the support table, the camera being operatively connected to a display screen to enable alignment of registration marks on the flexible printing plate with respective predetermined locations on the cylinder.

Therefore, in accordance with the invention the support table is mounted at a level below the cylinder and in such a manner that it is displaceable beneath the cylinder and the support table also has a compressible surface. This arrangement enables the flexographic plate to be supported on the table throughout the mounting procedure. Previously, to press the back of the flexographic printing plate firmly to the double sided adhesive tape on the cylinder required an additional operation with a rubber roller, either manually or by means of an additional pressure roll. Now, in accordance with the present invention, when the cylinder is lowered it forces the plate into the compressible surface of the support table ensuring adequate and even pressure and reliable adhesion across the surface of the cylinder and the plate. Displacement of the table perpendicular to the cylinder axis after initial contact of the cylinder with the plate serves to rotate the cylinder and attach the plate around the cylinder with continued even pressure throughout. Accordingly, requirement for any further manual intervention, such as for smoothing down the printing plate to remove air pockets, or requirement for an additional pressure roller is eliminated.

Mounting the cameras below the support table viewing the plate upwards from below enables registration marks on the flexographic plate to be aligned with locationslregistration markings on the table or on the cylinder or both. It also provides clear access around the cylinder itself for mounting and demounting same and for applying the customary double sided adhesive tape to its surface.

Oplionally the same apparatus could be employed, in a preliminary operation, to apply the adhesive tape to the cylinder surface. The tape would be placed on the table, and when appropriately positioned and its upper release paper removed, it would be contacted with the cylinder surface, by lowering the cylinder, and then the table moved tangentially below the cylinder to rotate the cylinder and wind the tape around. Another option in use of this apparatus would be to apply adhesive tape to the upper, substantially flat back surface of the flexographic plate, when it is supported upon the table surface, raised print surface facing downwards, instead of to the cylinder surface.

In practical embodiments of the apparatus of the invention, the support table may be made of a transparent material, such as glass or polycarbonate, having two or more sections of a compressible material, such as closed cell polyurethane foam, applied thereto as an upper surface layer, with narrow gaps between these sections defining transparent windows through which the camera view path is directed. Alternatively, the support table itself, having an upper surface layer of compressible material, may be provided as two or more separate sections with narrow open gaps (apertures) there between as camera view slots.

It would also be possible for just certain parts, transversely part way across the upper layer of compressible material, when mounted on a transparent lower layer, or transversely part way across the entire support table to be cut away as partial windows, slots or recesses for this purpose.

To ensure contact between the flexographic plate and the support table, eliminating natural curling of the plate, some embodiment of the apparatus of the invention may be provided with mechanical clamp means to hold the plate to the support table. Other embodiments of the apparatus in accordance with the invention may, more preferably, have vacuum suction devices mounted into the support table for the same purpose.

A further aspect of the invention is a method of mounting a flexible printing plate onto a cylinder comprising the steps of: mounting the cylinder above a substantially horizontal support table which has a compressible upper surface as well as a portion which is transparent or apertured or recessed; placing the printing plate onto the upper surface of the table with raised print areas of the printing plate facing downwards onto the upper surface of the table and with registration marks of the plate overlying the transparent or apertured or recessed portion of the table; aligning the registration marks on the printing plate with required locations on the cylinder; lowering the cylinder into contact with the back of the printing plate on the table so that the upper surface of the table is compressed; and moving the table beneath the cylinder in a substantially horizontal direction perpendicular to the axis of the cylinder whereby, due to adhesion between the printing plate and the cylinder surface, the cylinder is rotated and the plate is wound onto its surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described further, by way of example, by reference to the accompanying drawings in which: Figure 1 is a perspective view of a practical embodiment of the flexible printing plate mounting apparatus of the invention shown with printing cylinder mounted thereto and printing plate positioned, ready for mounting to the cylinder; Figure 2 is a larger scale partial perspective view from the other side to figure 1; Figure 3 is a further slightly larger perspective view from a similar viewpoint to the apparatus shown in figure 1, illustrating only the main parts of the apparatus, again with the printing cylinder mounted thereto and the printing plate positioned ready for mounting to the cylinder; Figure 4 is a view comparable to figure 3 of the same parts of the apparatus in a further stage of use where the cylinder has been lowered into contact with the printing plate on the

support table;

Figure 5 is a plan view of the apparatus shown in figure 1 after the printing plate has been mounted onto the cylinder; and Figure 6 is an enlarged partial perspective view also showing pads of the apparatus after a printing plate has been mounted onto the cylinder.

DETAILED DESCRIPTION

As shown, this embodiment of the apparatus of the invention comprises a support structure, designated generally by reference number 10, to which a support table 12 is mounted in a hodzontal disposition. The support structure includes legs 11, side panels 13, top surface panels 15, a pair of upright support posts 14 extending from the top surface and a support frame 16 which is mounted upon the support posts 14, extending there between. The frame 16 and posts 14 are capable of being lowered and raised by means of pneumatic rams 18. The rams 18 are pistons which are extensible from cylinders 28, shown in figures 3 and 4, to raise the support frame 16. The support frame 16 is designed for mounting a printing cylinder 20 and has respective arms 19 for connecting to the ends of the cylinder 20. One of the arms 19a is mounted to a carriage 29 which is slidably adjustable along a pair of transverse members 17 of the frame 16 to enable mounting of cylinders of different axial length. The cylinder 20 is mounted rotatably but it can be selectively free to rotate or Cocked to prevent rotation. The support structure also includes a linear bearing arrangement whereby opposing, substantially parallel side edge rails 22 of the table 12 engage respective side bearings 24 enabling the table 12 to slide forwards and backwards at a location between the support posts 14, in a horizontal plane and in a direction perpendicular to the axis of mounting of the cylinder 20, as indicated by the arrows in figures 1 to 5.

The support table 12 is made of transparent material, for example glass or polycarbonate, to which an upper surface layer of compressible material, for example closed cell polyurethane foam, is applied. This compressible material layer may be between 1 and 5 mm thick, most preferably about 3 mm thick. The foam layer is in two sections applied at the front and rear of the table in the direction of sliding with a narrow gap 26 remaining there between. This gap 26 defines a transverse window across the centre of the table.

The gap may suitably be between 5 and 10 mm wide. Edge frame members of any suitable material are provided at front and rear of the table 12, with the front edge frame member incorporating a hand hold 27 to facilitate manual sliding of the table 12. The table 12 extends, on its linear bearing mounting arrangement, below the support frame 16, and, as previously mentioned, it can be traversed forwards and backwards beneath the support arms 19 and the cylinder 20 which, in use, will be mounted there between. As an alternative to manual operation of the table, a motor driven mechanism may be provided.

Fine adjustment of the position of the support table 12 in a direction perpendicular to the axis of the cylinder 20 and perpendicular to the line of the gap 26 is possible, for example by means of a rack and pinion arrangement at one side edge of the table. In the illustrated embodiment a toothed rack 28 extends along one side rail 22 of the table 12 and a pinion which engages the rack can be manually adjusted. In a modified version such adjustment could be automated by having the pinion rotatable under motor control.

Adjustment of the position of the support table in a side to side direction parallel to the axis of the cylinder 20 and parallel to the line of the gap 26 is also possible, for example by mounting the table 12 so as to be movable along a track which extends parallel to the cylinder axis and providing a mechanism to move the table along said track. Again, this can be automated by having the adjustment mechanism under motor control. Fine adjustment in this direction may be provided for, for example by a threaded adjustment screw mechanism (not shown), which may be manual or under motor control.

As best shown in figures 3 and 4, two cameras 30, 31 are mounted below the table 12 and are directed vertically upwards through the transparent gap 26 between the front and rear sections of the compressible surface layer. These cameras are mounted onto a track 34 which extends below the table 12 parallel to the cylinder axis and generally in a location directly below the in use position of the cylinder 20. The cameras are mounted on respective carriages 35 which are adjustable in position, across the width of the machine, i.e. parallel to the cylinder axis. During use these cameras 30, 31 can be moved and then accurately fixed in position to match the size of the cylinder and/or the printing plate 40 which is to be mounted onto the cylinder 20. These cameras 30, 31 are operatively linked to a video monitor 32, shown only in figures 1 and 2, which is mounted for viewing by an operator during the alignment and plate mounting process. The cameras and the video registration system generally provide target markings and enable viewing of registration marks on the printing plate 40 and on the cylinder 20 through the transparent gap 26.

In a typical operation sequence, the pistons 18 are actively extended from the pneumatic cylinders 28 to put the support frame 16 into the raised position, as shown in figures 1 to 3, and maintain it in that position. The printing cylinder 20 is then mounted between the arms 19 of the support frame 16. Double sided adhesive tape, with release paper still covering the exterior surface, may already be applied to the cylinder, or it may be applied using this apparatus, as will be explained later. The flexographic printing plate 40 which is to be mounted to the cylinder 20 is then placed onto the compressible upper surface of the support table 12, as shown in figures 1 to 4, with its raised/relief printing surface facing downwards.

Typically, registration marks are provided at a central location between the ends of the printing plate and adjacent to each side edge of the plate, and further registration marks are provided adjacent each end of the plate, again adjacent to each side edge of the plate.

In the illustrated example the printing plate 40 is shown placed onto the table so that its mid-position registration marks overlie the transparent gap 26. The plate 40 may be illuminated by means of a light being shone through the transparent gap from below.

The printing plate 40 is centred relative to the cylinder 20, if necessary by moving the support table 12 in a direction parallel to the cylinder axis by the applicable adjustment mechanism. Also, if necessary, the cameras are moved into position across the width of the table and the plate to align the target marks of the video registration system with the registration marks of the plate 40 in a direction parallel to the cylinder axis. When the apparatus is used for mounting a set of photopolymer plates for printing different colours in a given image the position of the cameras is fixed when the first plate of the set is mounted and the subsequent plates are then aligned to the same positioning.

Registration marks on the cylinder 20 are aligned with targets (typically crosses or circles) generated by the cameras and the video registration system and the cylinder is clamped to prevent its rotation. The position of the printing plate 40 is then further adjusted, if required, preferably using the fine adjustment of the table in the lengthwise and transverse direction of its horizontal plane, as previously mentioned, to be accurately aligned with the aforesaid targets generated by the video registration system.

Once the printing plate 40 is accurately aligned below the cylinder 20, the release paper is removed from the adhesive tape and the support frame 16 is lowered until the cylinder 20 contacts the plate 40, as shown in figure 4. The support frame 16 is lowered by release of the air pressure in the cylinders 28, allowing the pistons 18 to retract. Under gravity alone, without further force being necessary, the weight of the cylinder 20 presses the print surface of the printing plate 40 into the resilient surface layer of the table 12 and adheres the cylinder to the reverse, upward facing surface of the printing plate. The cylinder lock is released so that it is again rotatable in its mounting. The support table 12 is then traversed tangential to the cylinder, namely perpendicular to the cylinder axis, which causes rotation of the cylinder 20 and wrapping of the printing plate 40 around the cylindrical surface. In the illustrated example where initial alignment is with mid-line registration marks of the printing plate, the table 12 is moved first in one direction to wrap one end region of the plate around the cylinder and then in the other direction back to the middle and beyond to wrap the other end region of the plate around the cylinder. The cylinder 20 is shown with the printing plate 40 applied thereto in figures 5 and 6. By depressing the surface layer of the table 12 the cylinder 20 maintains a constant and even pressure between itself and the back surface of the plate with the result that the tendency for air pockets to be formed between the plate and cylinder is virtually eliminated. Nor is there any risk of plate distortion due to forces appiled by an operator as operator manipulation to press and smooth the plate against the cylinder is no longer required.

Preferred embodiments of the apparatus in accordance with the invention include means which enable correct mounting of the plate onto the cylinder to be checked before its removal from the machine. Thus, means are provided to lift the cylinder, with plate mounted thereon, out of contact with the support table 12 but still within the focal distance of the cameras 30, 31. For example, a secondary piston and cylinder arrangement (not shown) also powered by compressed air may be provided to jog the support frame 16 upwards just sufficiently to lift the cylinder 20 in this way, not raising it the full distance achieved using the main cylinders 18. Once lifted in this way, the cylinder 20 can be freely rotated on its axis to view the registration marks at the midline, and adjacent leading and trailing edges of the plate 40 relative to the video registration system to check for parallelism and position. Once these are verified the cylinder can be lifted fully clear of the table 12 using the main pneumatic lifting arrangement and removed. If any inaccuracy is detected it may be possible to remedy this before the cylinder is removed. Figures 5 and 6 show the apparatus at a stage of operation where the printing plate 40 has been mounted onto the cylinder 20 and is being checked in a manner just described. The front and trailing edge registration marks of the printing plate 40 are visible in these drawings.

In modified embodiments of apparatus in accordance with the invention the table 12 may be provided with two or more transparent gaps or gaps in the surface at different locations to cater for printing plates which have registration markings only at the leading and trailing ends. For mounting such plates, the table 12 would typically be displaced at the beginning to its extreme forward or rearward position so that the relevant gap or window with which cameras need to be aligned is still positioned beneath the mounting location of the cylinder. After the printing plate is appropriately aligned with the video registration targets and the cylinder is lowered, the table 12 is then displaced fully in the relevant other direction to wrap the plate onto the cylinder.

In other embodiments of apparatus in accordance with the invention which are not illustrated, vacuum suction devices may be mounted in the support table 12, at spaced intervals across its width or in any other suitable arrangement, to further promote constant, even contact between the flexible plate 40 and the table 12, which in turn will optimise the accuracy of application of the plate 40 to the cylinder 20, as just mentioned.

As mentioned in the introduction hereto, instead of a printing cylinder, a print sleeve mounted on a mandrel may alternatively be used for application of a flexographic printing plate, the sleeve subsequently being transferred from the mandrel for use in a later print operation. The present apparatus can be employed in exactly the same manner with such a sleeve mounted on a mandrel in place of the printing cylinder 16.

It is also possible to use the apparatus just described, or other comparable apparatus within the scope of this invention, for applying adhesive tape to the surface of the cylinder.

This is achieved in the same general manner, the tape being placed, release liner downwards, onto the support table 12. The tape would be appropriately positioned, using comparable camera registration and/or using other measurement or stop means which may be provided, particularly along certain sides/edges of the support table 12, and could be cut to size at this point. Then after removal of release liner from the top surface of the tape, the cylinder would be lowered onto the upwardly facing adhesive surface of the tape, in the same manner previously described in respect of the printing plate, with the support table 12 being moved transversely beneath the cylinder to automatically wind the tape around the contacted surface of the cylinder. This additional possibility of use is likely to have considerable benefit to users of the apparatus, enabling a much easier manner of tape application than previously, with less risk of air bubble formation. lt should be particularly useful for wide cylinders where the adhesive tape typically has to be laid lengthwise to the cylinder axis.

The apparatus of the invention, with its support table which is movable below the cylinder, has another advantageous use in verification of the printing plate content. In this respect, a printing plate mounted onto a cylinder and mounted into the apparatus can be inked up.

Then, with a paper substrate positioned on the support table below, the cylinder can be lowered and rotated together with the tangential movement of the table there below so as to apply an impression of the print image to the paper. This image can then be quickly checked for any inaccuracies to the text or image or for any less distinct areas, indicative of low spots in the mounted printing plate. When using photopolymer plates this could be repeated for each colour of the relevant print job, if required.

The foregoing is illustrative and not limitative of the scope of the invention and many variations, refinements and modifications to the detail of the apparatus and its operation are possible, as will be readily apparent to a person skilled in the art. In particular, as already mentioned, it would be possible within the scope of the present invention, to provide apparatus with servo drives for positional control of the support table 12 and of the support frame 16 in order to achieve fully automated mounting of the flexible plate 40 or other flexible material, such as adhesive tape, to the cylinder 20. The raising and lowering of the cylinder 20 may, of course, be achieved by hydraulic instead of pneumatic piston and cylinder arrangements or indeed by any other suitable mechanism which is different from that described an respect of the illustrated embodiment.

Claims

CLAIMS1. Apparatus for mounting a flexible printing plate onto a cylinder comprising a support frame for rotatably mounting the cylinder to which the flexible printing plate is to be applied, a substantially horizontally arranged support table mounted below the support frame and providing a surface for supporting the flexible printing plate prior to and during its application to the cylinder, the support frame being mounted to a support structure to allow the cylinder to be lowered onto the support table or raised and supported above the support table, as required, and the support table being movable below the cylinder in a direction perpendicular to the cylinder axis and having a compressible upper surface as well as a portion which is transparent or apertured or recessed, and at least one camera mounted below the support table and directed upwards to view the transparent or apertured or recessed portion of the support table, the camera being operatively connected to a display screen to enable alignment of registration marks on the flexible printing plate with predetermined locations on the cylinder.
2. Apparatus as claimed in claim I wherein the compressible upper surface of the support table is provided by a layer of resilient material.
3. Apparatus as claimed in claim 2 wherein the compressible upper surface of the support table is provided as a layer of closed cell foam material.
4. Apparatus as claimed in any preceding claim including a hydraulic or pneumatic piston and cylinder arrangement for raising and lowering the support frame relative to the support structure.
5. Apparatus as claimed in claim 4 wherein the piston and cylinder arrangement is actuable to raise the support frame and releasable to lower the support frame so that the cylinder rests upon the support frame under gravity.
6. Apparatus as claimed in any preceding claim including rack and pinion means at one side edge of the support table to enable adjustment of the position of the table in a direction perpendicular to the cylinder axis.
7. Apparatus as claim in any preceding claim including means for adjustment of the position of the support table in a direction parallel to the cylinder axis.
8. Apparatus as claimed in claim 7 wherein the means for adjustment of the position of the support table in a direction parallel to the cylinder axis is a threadedly adjustable actuator at one side edge of the support table.
9. Apparatus as claimed in claim 5 including secondary means to lift the support frame thereby to hold the cylinder, after the printing plate has been applied thereto, at a predetermined limited distance above the support table, less than the distance through which the cylinder is raised by actuation of said hydraulic or pneumatic piston and cylinder arrangement.
10. Apparatus as claimed in claim 5 wherein the piston and cylinder arrangement is actuable to raise the support frame by first and second distances relative to the support structure, the first distance being greater than the second distance, and the second distance being sufficient to hold the cylinder just clear of the upper surface ofthe support table.
11. Apparatus as claimed in any preceding claim further including vacuum means associated with the support table to enable the flexible printing plate to be held in close contact with the support table once positioned thereon.
12. A method of mounting a flexible printing plate onto a cylinder comprising the steps of: mounting the cylinder above a substantially horizontal support table which has a compressible upper surface as well as a portion which is transparent or apertured or recessed; placing the printing plate onto the upper surface of the table with raised print areas of the printing plate facing downwards onto the upper surface of the table and with registration marks of the plate overlying the transparent or apertured or recessed portion of the table; aligning the registration marks on the printing plate with locations on the cylinder using an optical registration system including at least one camera mounted below the support table and directed upwards to view the transparent or apertured or recessed portion of the support table; lowering the cylinder into contact with the back of the printing plate on the table so that the upper surface of the table is compressed; and moving the table beneath the cylinder in a substantially horizontal direction perpendicular to the axis of the cylinder whereby, due to adhesion between the printing plate and the cylinder surface, the cylinder is rotated and the plate is wound onto its surface.
13. A method as claimed in claim 12 wherein the step of aligning the registration marks on the printing plate with required locations on the cylinder is by adjusting the position of the support table in directions parallel and perpendicular to the cylinder axis, as required.
14. Apparatus for mounting a flexible printing plate onto a cylinder substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.