GB2322332A

GB2322332A - Process and apparatus for carrying out lateral register corrections

Info

Publication number: GB2322332A
Application number: GB9803748A
Authority: GB
Inventors: Heiner Sirowitzki; Gernot Moser; Rainer Schneider
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1997-02-22
Filing date: 1998-02-23
Publication date: 1998-08-26
Anticipated expiration: 2018-02-23
Also published as: FR2759940A1; GB9803748D0; DE19707063C1; GB2322332B; FR2759940B1

Abstract

A process and apparatus for carrying out side register corrections of printing plates adjustably on a plate cylinder of a printing press particularly an offset sheet printing press are described. In accordance with the invention, this is prior to the axial shifting of a tensioning rail (2) together with a printing plate (1) held by this (Fig. 1), the tensioning rail (2) and the printing plate (1) are moved peripherally on one side (Fig. 2) and thereafter the preset side register correction is carried out by axially moving the tensioning rail together with the printing plate, and simultaneously or thereafter swivelling the rail back (Fig. 3) to position the tensioning rail and the printing plate parallel to their original position but axially shifted (Fig. 4).

Description

2322332 - 1 PROCESS AND APPARATUS FOR CARRYING OUT LATERAL REGISTER

CORRECTIONS This invention relates to a process for carrying out lateral register corrections in particular in offset sheet printing presses, as well as to an apparatus for carrying out this process.

In multi-colour offset sheet printing presses the printing plates mounted on the individual plate cylinders must be aligned in correct register, in order that in the overall printing, a register correct print result appears. In order to be able to correct the positions of the individual printing plates in the printing units relatively to one another, it is known either to mount the plate cylinder movably in the peripheral, lateral and/or oblique register direction or to apply the individual printing plates on the plate cylinders movably relative to the cylinders in the directions noted. On carrying out register corrections and in particular lateral register connections as a rule in this connection the position of one printing plate is left unchanged and the positions of the remaining printing plates (colours) corrected relative to this standard colour. From the register differences emerging in the print, the corresponding adjustment quantities can be determined.

From DE 4 205 276 Al, a device for tensioning a printing plate on a plate cylinder is known in which a tensioning rail arranged relative to the print start is mounted movably on the plate cylinder both in the peripheral and also in the lateral register direction. The print end of the printing plate which is wound around the plate cylinder is in this connection held by several pins spaced from one another cooperating with corresponding perforations at the print end of the printing plate and sprung in the peripheral and also in the axial direction of the plate cylinder. If remote controlled drives for the peripheral and also for the lateral register direction are additionally fitted to the print start tensioning rail of the plate cylinder then it is possible, by means of this apparatus, to move the printing plate on the plate cylinder during press running, thus making it possible to carry out the corresponding register corrections with the press running.

From DE 4 210 897 C1 a plate cylinder with an adjustable tensioning rail is known in which the tensioning rail arranged relative to the print start has both on the A and also on the B side in each case an adjusting drive making possible a peripheral register correction and furthermore in the middle of the tensioning rail a further adjusting drive for generating lateral register corrections is provided. The individual adjustment mechanisms are connected via eccentrics with the tensioning rail, this being effected in such a fashion that adjustments can be undertaken in each case 3 independently of the remaining adjustment drives. Thus, it is in particular possible to control the adjustment drive on the A side of the tensioning rail to generate an oblique adjustment of the printing plate on the plate cylinder. Simultaneous control of the adjustment drive on the A and B side of the plate cylinder through the same/different movement paths furthermore effects a movement of the printing plate in the peripheral direction/in peripheral direction and oblique register direction. By controlling the adjustment drive fitted i the centre of the tensioning rail, furthermore the tensioning rail together with the printing plate can also be moved in the lateral register direction of the plate cylinder.

If in particular lateral register corrections are carried out during press running by means of a device known from DE 4 205 276 Al, then it is found that the print end held by the spring loaded pins does not immediately follow, or not completely follow the movements generated by corresponding movement of the print start tensioning rail. In particular, it is found in this connection if the tensioning rail for example is moved in the direction to the B side of the press that the parts present on the A side of the printing plate print shift in the peripheral direction towards the print start. This obviously has its origin in that if the print start tensioning rail is shifted for generating a lateral register correction exclusively in the lateral register direction, then because of the cooperation with the blanket cylinder and its pull exerted on the printing plate in combination with the friction between printing plate and plate cylinder surface, the result is that forces arise which cause the side away from the direction on movement of the side register correction to arch up slightly, and to compression of the printing plate between print start and the print start tensioning rail. This displacement of the printing plate occasioned by a lateral register correction must then compensated by further register corrections, which is correspondingly time-consuming and means further waste sheets arise.

We have now found that if, before the introduction of the corresponding lateral register correction by moving the print start tensioning rail is first twisted, the end of the rail which will lead the axial movement being moved back towards the print start, and then that end moved forwards again as the rail is shifted axially, rapid lateral register adjustment can be achieved while the press is running over the course of a few revolutions.

First the end of the tensioning rail together with the printing plate held by this is pulled so that the corner of the plate moves in the direction towards the print start. After this one side peripheral register shift has been carried out, in a second process step the corresponding movement of the tensioning rail as well as the printing plate held by this takes place in the lateral register direction by the desired amount as well as the peripheral repositioning of the leading end of the tensioning rail, i.e. during the axial movement of the rail, the peripheral register adjustment imparted to one side is, by the provision of corresponding control commands, undone again, so the tensioning rail accordingly brought into a position parallel with its starting position, as though it had been shifted purely axially.

- 5 With the process in accordance with the invention both before the adjustment of the oblique register correction by corresponding adjustment of the print start tensioning rail parallel to itself first a certain twisting of the printing plate is generated, which then on carrying out the oblique register correction (moving the print start tensioning rail in the axial direction of the plate cylinder while moving its leading end peripherally) is undone again.

In accordance with a preferred further development of the invention, it is provided in this connection that before carrying out a preset lateral register correction by shifting the tensioning rail arranged relative to the print start through an amount s, an oblique adjustment of the printing plate together with the printing rail arranged relative to the print start takes place by corresponding control of the adjusting devices set on the A or B side respectively via the amount n, s, wherein the factor n is preferably chosen of an order of magnitude of 2. This mode of operation has emerged as particularly preferred since by the approximately double size oblique adjustment (one side peripheral adjustment) of the tensioning rail together with the printing plate before the introduction of the lateral register correction any remaining positional differences can be prevented wholly or substantially wholly. In accordance with the invention, it is in this connection seen as a further development that since the side and also peripheral register adjusting devices always have maximum adjustment paths (e.g. 1.5 mm), the single side peripheral register adjustment for oblique adjustment of the printing plate is exactly undertaken then through the maximum possible amount, when the product of the preset lateral register correction s with the preset factor n is greater than the maximum movement path which can be carried out by the peripheral register adjustment device.

The invention is further explained by way of example with reference to the accompanying drawings in which:

Figures 1 - 4 show the principle of register adjustment in accordance with the invention, and Figure 5 shows a block circuit diagram of an apparatus in accordance with the invention.

Referring to Figures 1 to 4, Figure 1 shows a tensioning rail 2 arranged relative to the print start of a not illustrated plate cylinder, together with a printing plate 1 held in rail 2. The end of printing plate 1 remote from the tensioning rail 2 is in this connection preferably held by not illustrated spring elements both in the peripheral and also in the axial direction of the not illustrated plate cylinder.

Arranged relative to the print start tensioning rail 2 are three independent adjusting drives 3.1, 3.2 and 3.3 by means of which the tensioning rail 2 can be moved on its A and B sides independently from one another in the peripheral direction and also in the lateral register direction with respect to the plate cylinder. Shifting the printing plate 1 together with the tensioning rail 2 in the lateral register direction is promoted in this connection by the adjusting drive 3.2, which is illustrated in Figures 1 to 4 acting substantially on the centre of the tensioning rail 2. The movements which can be imparted to tensioning rail 2 by the adjusting drives 3.1, 3.2 and 3.3 are indicated by the double arrows.

Figure 1 shows the starting adjustment of the printing plate 1 together with the tensioning rail 2 before a lateral register correction, wherein the desired position to be achieved by the lateral register correction of the printing plate 1 together with the tensioning rail 2 is illustrated dashed. In this example, the printing plate 1 together with the tensioning rail 2 is to be shifted away from the A side in the direction towards the B side.

In accordance with the invention, it is provided that prior to the shifting of the tensioning rail 2 in the lateral register direction by corresponding control of the adjusting drive 3.2, the tensioning rail 2 together with the printing plate 1 fixed thereon is twisted by corresponding control of the adjusting drive 3.3, so that the printing plate on the B side is pulled nearer towards the print start of the plate cylinder. The tensioning rail 2 together with the printing plate 1 is accordingly tipped at its end in the direction in which the correction of the lateral register has to occur towards the print (Figure 2).

After the tensioning rail 2 as well as the printing plate 1 fixed thereon has taken up the tipped position illustrated in Figure 2 by corresponding control of the adjustment drive 3.3, the adjusting drive 3.2 is then actuated in order to move the tensioning rail 2 together with the printing plate 1 fixed thereon in the preset side register direction, and the adjustment drive 3.3 is actuated to return the tensioning rail 2 into its starting position. In Figure 2 in this connection the pulling back of the printing plate 1 together with the tensioning rail 2 is illustrated by the arrow indicated on the B side in the direction towards the print start. In Figure 3 the return of the tensioning rail 2 with the printing plate 1 fixed thereon into the parallel starting direction again characterised by an arrow running vertically as the drawing is viewed. The moving of the tensioning rail 2 in the lateral register direction is in this case indicated by the arrow running parallel to tensioning rail 2, i.e. longitudinally in the drawing as viewed. The tensioning rail 2 and the printing plate 1 fixed thereon carry out a combined movement as shown by the curved arrow in Figure 3.

Figure 4 shows the tensioning rail 2 together with the printing plate 1 fixed thereon after these two steps, i.e. now in the desired position, as was illustrated dashed in Figure 1. Now further lateral and/or peripheral and/or oblique register corrections can be undertaken.

In the previously explained exemplary embodiment of the invention, a tensioning rail 2 together with the printing plate 1 fixed thereon is shifted in a lateral register direction from the A towards the B side and correspondingly the end of the tensioning rail 2 on the B side together with the printing plate 1 is first shifted via a preset amount in the direction towards the print start and following thereon again set back by the same amount. Correspondingly in this connection a lateral register correction of the tensioning rail 2 together with printing plate 1 installed thereon may be undertaken in the direction from the B side towards the A side. In that case, prior to carrying out the lateral register shifting by controlling the adjustment drive 3.2 first - 9 the end of the tensioning rail 2 towards the A side is pulled forward by control of the adjusting drive 3.1 in the direction towards the print start in order thereafter by controlling the adjustment drive 3.2 to move the tensioning rail 2 through the preset register path and thereby simultaneously the adjustment path effected by the adjustment drive 3.1 is compensated again.

Figure 5 shows a block circuit diagram of apparatus in accordance with the invention for carrying out the process described above. The adjusting drives 3.1, 3.2, 3.3 fitted to a not illustrated tensioning rail are in this connection operatively connected with a control device 4 and can be controlled by this both individually and also together in groups. The control device 4 in this connection is connected with the adjusting drives 3.1, 3.2, 3.3 of all of the tensioning rails of a printing press.

The control apparatus furthermore is operatively connected with a servicing unit 5, in particular the control desk of the printing press, by means of which, for example, after measuring test sheets, register corrections which have been determined can be input and can be brought to execution. By means of the control device 4, the control explained previously with reference to Figures 1 to 4, both of the adjustment drives provided for lateral register correction 3.2 and also the adjustment drives 3.1 and 3.3 effecting the circumferential register correction, takes place.

Claims

1. A process for carrying out lateral register corrections in printing presses, particularly offset sheet printing presses, in which a printing plate located on a plate cylinder is adjusted with the press running by moving a tensioning rail holding one end of the plate and arranged relative to the print start, in the direction of the axis of the plate cylinder, wherein before moving the tensioning rail in the lateral register direction, first the end of the tensioning rail which will lead when the rail is moved in the lateral register direction is moved peripherally towards the print start and thereafter the tensioning rail is moved axially by a preset amount in the lateral register direction and the leading end of the tensioning rail is moved back peripherally into its starting position.

2. A process according to Claim I wherein the moving back of one end of the tensioning rail into its peripheral starting position and the shifting of the tensioning rail in the lateral register direction take place simultaneously.

3. A process according to Claim 1 or 2 wherein the movement of the end of the tensioning rail directed in the direction of the lateral register adjustment towards the print start, and the corresponding return movement take place exclusively under the control of an adjustment drive located at one end of the tensioning rail and arranged to move the tensioning rail in the peripheral direction.

4. A process according to any one of the preceding 11 Claims wherein the movement in the peripheral direction of the end of the tensioning rail is by an amount which is the product of the distance the rail is to move axially for the correction of the lateral register and a preset factor.

5. A process according to Claim 4 wherein the amount of movement in the peripheral direction, if the product is greater than the maximum movement path for the peripheral register, is that maximum movement path.

6. A process according to Claim 4 or 5 wherein the peripheral movement of the end of the tensioning rail substantially double the axial adjustment path to be traversed by the tensioning rail to correct the lateral register.

7. A process for carrying out lateral register correction substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.

8. Apparatus for shifting a printing plate tensioned on a plate cylinder with a tensioning rail holding the printing plate at its print start, the apparatus including adjustment drives fitted thereon to the tensioning rail, and a control apparatus connected thereto, the adjustment drives including drives at each end of the rail for moving the rail in the peripheral direction and a drive intermediate the ends for moving the rail in the lateral register direction, and wherein the control apparatus is adapted, following the input of a command to effecting a lateral register correction, to control of at least one of the adjustment drives effecting the peripheral register adjustment to generate - 12 a peripheral movement of one end of the tensioning rail and thereafter to control the adjustment drive effecting the lateral register adjustment of the tensioning rail, and to the adjustment drive effecting the peripheral movement of the end of the tensioning rail.

9. Apparatus according to Claim 8 wherein the control device is adapted to effect the second peripheral movement and the lateral register correction movement of the tensioning rail simultaneously.

10. Apparatus according to Claim 8 and substantially as hereinbefore described with reference to Figure 5 of the accompanying drawings.