GB1590025A - Web guide for intaglio printing mechanisms - Google Patents

Abstract

A web (21) to be printed is conveyed over guide rollers (23, 24) of a web conveying system and over an impression cylinder (26). One (24) of the guide rollers is mounted so as to be freely rotatable on the support of the impression cylinder (26) and of a back pressure roller (27). The other guide roller (23) is firmly connected to slides (23.1). The slides (23.1) are connected in an articulated manner to the bearing shells of the one guide roller (24) by means of a coupler (29). The position of the guide rollers (23, 24) relative to one another is coordinated such that, when the impression cylinder (26) is raised from the forme cylinder (28), the shortening of the web (21) thus caused is compensated by displacing the other guide cylinder (23). After renewed engagement of the impression cylinder (26) on the forme cylinder (28), printing can be continued in register with the colours printed prior to the raising of the impression cylinder (26). <IMAGE>

Description

(54) WEB GUIDE FOR INTAGLIO PRINTING MECHANISMS (71) We, WINDMÓLLER & HOLSCHER, a Kommanditgesellschaft organised and existing under the laws of the Federal Republic of Germany, of 48-52 Miinsterstrasse, 454 Lengerich, Westphalia, the Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to an intaglio printing machine having a plate cylinder fixed with respect to the machine frame, and a web guide comprising an impression cylinder which can be applied thereto and lifted therefrom.

In multi-colour printing presses having a plurality of intaglio printing mechanisms which are stopped and withdrawn from time to time and wherein the web disposed in the printing mechanisms is to be printed with the missing colours in proper registration after the impression cylinder has again been applied to the plate cylinder, the problem arises of aligning the web to be printed in registry with the plate cylinder after the impression cylinder has been withdrawn and re-applied, so that printing errors are avoided after the impression cylinder has been re-applied and the press started. When lifting the impression cylinder off the plate cylinders, the web to be printed becomes loose so that it is displaced by the jockey rollers of the printing press out of the position it assumed before the impression cylinder was lifted off. Upon reapplication of the impression cylinder, the initial position of the web cannot again be accurately found, so that printing in proper registration is impossible and waste occurs.

According to the invention, there is provided in an intaglio printing machine having a plate cylinder fixed with respect to a frame of the machine, a web guide comprising an impression cylinder movable between one position in which it is applied to the plate cylinder and another position in which it is lifted therefrom, a freely rotatable guide roller in bearings which are fixed relative to the impression cylinder axis, and a coupling freely pivotable about the axis of the guide roller and guiding a further freely rotatable guide roller for movement relative to the frame whereby changes in the length of web entrained around the impression cylinder and the first said guide roller during movement of the impression cylinder between its two positions are compensated by movement of the further guide roller.

Deflecting rollers having axes fixed with respect to the frame can be provided to divert the web into supply and withdrawal directions.

According to one embodiment of the invention, provision is made for a guide roller displaceable parallel to itself in slides extending transverse to the direction of travel of the impression cylinder and its bearings are displaceable by the coupling which is hinged to the support of the impression cylinder so that the guide roller deflects the web to the same extent as length differences arise through raisin and lowering the impression cylinder.

According to another embodiment, the web is supplied and withdrawn over a respective deflecting roller fixed with respect to the frame and passes over a guide roller carried by pivotally mounted steering members one of which forms rq r .1 .

the coupling. The lengths of the steering members are selected so that they deflect the guide roller to such an extent that it compensates the length differences resulting from lifting and lowering of the impression cylinder.

The invention will now be described in more detail with reference to the accompanying drawings, wherein: Figure 1 is a diagrammatic representation of a web guide with two guide rollers of which one is mounted in a supporting arm rigidly connected to the support of the impression cylinder and the other is mounted in a supporting arm hinged to the other supporting arm, and Figure 2 shows a web guide in which the guide roller that is movable relatively to the impression cylinder is carried by two steering members and is deflected corresponding to the motion of the impression cylinder.

Figure 1 illustrates a web guide with a web 21 fed over loosely rotatably mounted deflecting rollers 22, 25 and guide rollers 23, 24 and an impression cylinder 26. The rollers 22 and 25 are fixed with respect to the frame but loosely rotatable. The guide roller 24 is mounted to be lifted from and re-applied to the plate cylinder 28 together with the impression cylinder 26 and a backing roller 27. The bushings of the guide roller 23 are fixed to slides 23.1 which are easily displaceable in guides 23.2 in the horizontal direction. The slides 23.1 are hinged to the bushings of the guide roller 24 by a coupling 29. The mutual position of the rollers is such that on lifting the impression cylinder 26 off the plate cylinder 28 into the chain-dotted position, the resultant shortening of the web is compensated by displacement of the guide roller 23 in its guide 23.2. The same applies to re-application, whereby printing in accurate registry is ensured.

The web guide shown in Figure 2 differs from the web guide of Figure 1 in that the guide roller 33 movable relatively to the impression cylinder is not displaceably mounted in a guide fixed with respect to the frame but is carried by steering members 39.1 and 39.2, of which one is mounted at the axis of the deflecting roller 32 fixed with respect to the frame. On lifting the impression cylinder 36, loosening of the web 31 is compensated by appropriate swinging motion of the roller 33.

WHAT WE CLAIM IS: 1. An intaglio printing machine having a plate cylinder fixed with respect to a frame of the machine, a web guide comprising an impression cylinder movable between one position in which it is applied to the plate cylinder and another position in which it is lifted therefrom, a freely rotatable guide roller in bearings which are fixed relative to the impression cylinder axis, and a coupling freely pivotable about the axis of the guide roller and guiding a further freely rotatable guide roller for movement relative to the frame, whereby changes in the length of web entrained around the impression cylinder and the first said guide roller during movement of the impression cylinder between its two positions are compensated by movement of the further guide roller.

2. An intaglio pirnting machine according to Claim 1, wherein the further guide roller is mounted in slides extending at right angles to the direction of movement of the impression cylinder.

3. An intaglio printing machine according to Claim 1, wherein the further guide roller is mounted on two steering members one of which forms the coupling and the other of which is pivotally mounted with respect to the frame.

4. An intaglio printing machine according to Claim 3, wherein the said other steering member is pivotally mounted in coincidence with a freely rotatable deflecting roller entraining the web.

5. An intaglio printing machine constructed and arranged substantially as hereinbefore described and shown in Figure 1 or 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. rollers 22, 25 and guide rollers 23, 24 and an impression cylinder 26. The rollers 22 and 25 are fixed with respect to the frame but loosely rotatable. The guide roller 24 is mounted to be lifted from and re-applied to the plate cylinder 28 together with the impression cylinder 26 and a backing roller 27. The bushings of the guide roller 23 are fixed to slides 23.1 which are easily displaceable in guides 23.2 in the horizontal direction. The slides 23.1 are hinged to the bushings of the guide roller 24 by a coupling 29. The mutual position of the rollers is such that on lifting the impression cylinder 26 off the plate cylinder 28 into the chain-dotted position, the resultant shortening of the web is compensated by displacement of the guide roller 23 in its guide 23.2. The same applies to re-application, whereby printing in accurate registry is ensured. The web guide shown in Figure 2 differs from the web guide of Figure 1 in that the guide roller 33 movable relatively to the impression cylinder is not displaceably mounted in a guide fixed with respect to the frame but is carried by steering members 39.1 and 39.2, of which one is mounted at the axis of the deflecting roller 32 fixed with respect to the frame. On lifting the impression cylinder 36, loosening of the web 31 is compensated by appropriate swinging motion of the roller 33. WHAT WE CLAIM IS:

1. An intaglio printing machine having a plate cylinder fixed with respect to a frame of the machine, a web guide comprising an impression cylinder movable between one position in which it is applied to the plate cylinder and another position in which it is lifted therefrom, a freely rotatable guide roller in bearings which are fixed relative to the impression cylinder axis, and a coupling freely pivotable about the axis of the guide roller and guiding a further freely rotatable guide roller for movement relative to the frame, whereby changes in the length of web entrained around the impression cylinder and the first said guide roller during movement of the impression cylinder between its two positions are compensated by movement of the further guide roller.

2. An intaglio pirnting machine according to Claim 1, wherein the further guide roller is mounted in slides extending at right angles to the direction of movement of the impression cylinder.

3. An intaglio printing machine according to Claim 1, wherein the further guide roller is mounted on two steering members one of which forms the coupling and the other of which is pivotally mounted with respect to the frame.

4. An intaglio printing machine according to Claim 3, wherein the said other steering member is pivotally mounted in coincidence with a freely rotatable deflecting roller entraining the web.

5. An intaglio printing machine constructed and arranged substantially as hereinbefore described and shown in Figure 1 or 2 of the accompanying drawings.