GB2398038A

GB2398038A - Apparatus for mounting a printing plate to a printing cylinder

Info

Publication number: GB2398038A
Application number: GB0302939A
Authority: GB
Inventors: Gavin Ross Jones
Original assignee: FLEXICO Ltd
Current assignee: FLEXICO Ltd
Priority date: 2003-02-08
Filing date: 2003-02-08
Publication date: 2004-08-11
Anticipated expiration: 2023-02-08
Also published as: GB0302939D0; GB2398038B

Abstract

An apparatus for mounting a printing plate to a printing cylinder (2) comprising: means (4,6) for supporting a printing cylinder (2), such that the rotational axis of the cylinder extends horizontally across the front of the apparatus; a table (8) positioned behind the cylinder supporting means (4,6), for supporting a plate in a horizontal plane against the upper surface of a supported cylinder (2); means (28) for releasably clamping a plate in position upon the surface of the table (8); a pair of cameras (10,12) for obtaining respective magnified images, at spaced apart points, of the upper surface of a plate supported on the table (8); and means (14,16) for displaying the images obtained from each camera (10,12), over which respective reference lines, e.g. cross-hairs (18,20), are superimposed for aligning the plate with the upper surface of the cylinder (2).

Description

PLATE MOUNTING APPLE ___

The present invention relates to an apparatus for mounting a plate to a printing cylinder and, more particularly, to an apparatus wherein relative alignment between the plate and the cylinder may be readily achieved.

It is widely known within the printing industry to apply inks to a substrate from a moulded or pressed, flexible plate, secured, by an adhesive, to the surface of a cylindrical roller.

However, hitherto, the operation of aligning a plate with the surface of a cylinder to which the plate is to be secured, has been carried out entirely manually, requiring a considerable amount of skill and dexterity on the part of the person carrying out the alignment.

We have now devised an arrangement which overcomes the problems associated with existing plate-alignment methods.

In accordance with the present invention, there is provided an apparatus for mounting a plate to a printing cylinder, the apparatus comprising: means for supporting a printing cylinder, such that the rotational axis of the cylinder extends horizontally across the front of the apparatus; a table positioned behind the cylinder supporting means, for supporting a plate in a horizontal plane against the upper surface of a supported cylinder; means for releasably clamping a plate in position upon the surface of the table; a pair of cameras for obtaining respective magnified images, at spaced apart points, of the upper surface of a plate supported on the table; and means for displaying the images obtained from each camera, over which respective reference lines, e.g. cross hairs, are superimposed for aligning the plate with the upper surface of the cylinder.

Thus, accurate alignment of a plate upon a cylinder may be achieved by registering respective alignment markings formed on the plate with the reference lines superimposed over the displayed images and clamping the plate in position, prior to securing the plate to the cylinder.

Preferably, the apparatus is arranged such that the position of the table is adjustable in a horizontal plane, preferably such that the table is at least rotatable with respect to a supported cylinder, to allow minor adjustments to be made to the alignment of plate clamped thereon.

Preferably the apparatus is arranged such that the vertical position of the table is adjustable, preferably such that the relative vertical positions of the table and cameras remain fixed, to accommodate cylinders of differing radii.

Preferably the cameras are arranged to obtain respective images at spaced apart points along a line extending parallel to the axis of rotation of a supported cylinder, with the apparatus preferably being arranged such that the horizontal position of each camera is adjustable parallel to the axis of rotation of the supported cylinder. Preferably said horizontal line is vertically aligned with the axis of rotation of a supported cylinder.

The apparatus is preferably arranged such that the reference line(s) superimposed over the displayed images obtained from at least one of the two cameras is/are adjustable in position, at least perpendicularly of the axis of rotation of a displayed cylinder.

The reference lines may, for example be provided by reticules fitted to each camera or to said display means, or may be electronically superimposed over the displayed images.

The display means may comprise a single display screen but preferably comprise a respective display screen for each camera.

Preferably the apparatus is arranged such that the operation of the releasable clamping means is controlled via a foot-switch, thereby allowing a plate supported on the table to be secured held by both hands of an operator as the plate is clamped in position.

An embodiment of the present invention will now be described by way of an example only and with reference to the accompanying drawings, in which: Figures 1 and 2 are respectively a front elevation and a side elevation of a plate mounting apparatus in accordance with the present invention) Figures 3 and 4 are respective isometric views of the plate clamping mechanism of the apparatus in unclamped and clamped states; Figures 5 and 6 are respective plan views of the plate clamping mechanism in first and second states; and Figures 7 and 8 are respective side elevations of an upper portion of the apparatus in first and second states.

Referring to Figures 1 and 2 of the drawings, a plate mounting apparatus in accordance with the present invention is shown, to which a printing cylinder 2 is fitted, by pneumatically clamping the cylinder between a pair of tapered centres 4,6, such that the rotational axis of the cylinder extends horizontally across the front of the apparatus.

The apparatus further comprises a table 8, positioned behind the supported cylinder 2, for supporting a flexible plate in a horizontal plane, and a pair of cameras 10,12, mounted above the cylinder 2 to provide, via respective display screens 14,16, magnified images, at spaced apart points, of the upper surface of a plate supported on the table.

Respective pairs of cross-hairs 18,20 are electronically superimposed over the displayed image from each camera 10,12, for registering with corresponding markings formed on the surface of an underlying plate. The two cameras 10,12 are displaceable mounted to a track 22, such that their relative positions, axially of a supported cylinder 2, are independently adjustable, by rotating respective control handles 24,26. Further controls (not shown) allow the vertical positions of the horizontal cross- hairs displayed on each of the two screens 14,16 to be varied.

A pneumatically driven clamping plate 28, positioned above the table 8, is operable, via a foot-switch 30, to releasably clamp a plate in position on the surface of the table, as shown in Figures 3 and 4, a second foot-switch 32 being provided for controlling the operation of the cylinder mounting centres 4,6.

Rotatable control handles 34,36 on either side of the table 8 are provided for adjusting the horizontal position of the table, for example as shown in Figures 5 and 6, the variation in the degree of yaw of the table between the two figures resulting from a forwards displacement of the left-hand side of the table and a rearwards displacement of the right hand side of the table.

It will be appreciated that both sides of the table 8 may, if required, be adjusted in the same forwards or backwards direction, to accurately position the leading edge of a plate supported thereon over the surface of an underlying cylinder 2.

So that the apparatus may accommodate cylinders of differing radii, the table 8 and the cameras 10,12 are each mounted to a vertically displaceable armature 38, which may be raised or lowered- with respect to the cylinder mountings 4,6, for example -as shown in Figures 7 and 8, by rotating a control handle 40.

In use of the apparatus, the two camera displays are first calibrated by setting the position of one of the cameras e.g. 10 along the track such that the cross-hairs 18 of its associated display are centred on a fixed point, and then setting the second camera 12 in the same position and adjusting the vertical position of its horizontal cross-hair to intersect the same fixed point.

A cylinder 2, having a covered, adhesive coating, is then fitted to the apparatus by operating the foot-switch 32 to clamp the cylinder in place between the centres 4,6, with the vertical position of the armature 38 adjusted such the plane of the surface of the table 8 lies above the cylinder.

A plate is then positioned on the table 8, with the forwards edge of the plate in approximate parallel alignment with the axis of rotation of the cylinder 2, and the transverse positions of the two cameras 10,12 adjusted to achieve approximate registration of the cross-hairs 18,20 of their associated displays with respective alignment markings formed on the plate.

The foot-switch 30 is then operated to clamp the plate in position and the horizontal orientation of the table 8 and transverse positions of the two cameras 10,12 finely adjusted to achieve an exact alignment of the plate.

With the plate thus aligned, the adhesive coating of the cylinder 2 is then exposed and the armature 38 lowered to bring the leading edge of the plate into contact with the upper surface of the cylinder, to which it becomes adhered.

The foot-switch 30 is then once again operated to unclamp the plate, allowing the remainder of the plate to be fastened to the cylinder 2 by rotating the cylinder about its axis.

The apparatus thus described provides a convenient and time-efficient means for mounting a plate to a printing cylinder. -

Claims

Claims 1) An apparatus for mounting a plate to a printing cylinder, the

apparatus comprising: means for supporting a printing cylinder, such that the rotational axis of the cylinder extends horizontally across the front of the apparatus; a table positioned behind the cylinder supporting means, for supporting a plate in a horizontal plane against the upper surface of a supported cylinder) means for releasably clamping a plate in position upon the surface of the tables a pair of cameras for obtaining respective magnified images, at spaced apart points, of the upper surface of a plate supported on the tables and means for displaying the images obtained from each camera, over which respective reference lines, e.g. cross hairs, are superimposed for aligning the plate with the upper surface of the cylinder.

2) An apparatus as claimed in Claim 1, arranged such that the position of the table is adjustable in a horizontal plane.

3) An apparatus as claimed in Claim 2, arranged such that the table is at least rotatable with respect to a supported cylinder.

4) An apparatus as claimed in any preceding claim, arranged such that the vertical position of the table is

adjustable.

5) An apparatus as claimed in Claim 4, arranged such that the relative vertical positions of the table and cameras remain fixed.

6) An apparatus as claimed in any preceding claim, wherein the cameras are arranged to obtain respective images at spaced apart points along a line extending parallel to the axis of rotation of a supported cylinder.

7) An apparatus as claimed in Claim 6, arranged such that the horizontal position of each camera is adjustable parallel to the axis of rotation of the supported cylinder.

8) An apparatus as claimed in Claim 6 or Claim 7, wherein said horizontal line is vertically aligned with the axis of rotation of a supported cylinder.

9) An apparatus as claimed in any preceding claims, arranged such that the reference line(s) superimposed over the displayed images obtained from at least one of the two cameras is/are adjustable in position, at least perpendicularly of the axis of rotation of a displayed cylinder.

10) An apparatus as claimed in any preceding claim, wherein the reference lines are provided by reticules fitted to each camera or to said display means.

11) An apparatus-- as claimed in any of Claims 1 to 9, wherein the reference lines are electronically superimposed over the displayed images.

12) An apparatus as claimed in any preceding claim, wherein the display means comprise a single display screen 13) An apparatus as claimed in any of Claims 1 to 11, wherein the display means comprise a respective display screen for each camera.

14) An apparatus as claimed in any preceding claim, arranged such that the operation of the releasable clamping means is controlled via a footswitch.

15) An apparatus substantially as herein described with reference to the accompanying drawings.