GB2206534A

GB2206534A - Plate cylinder for a rotary printing machine

Info

Publication number: GB2206534A
Application number: GB08811838A
Authority: GB
Inventors: Friedrich Gottwald; Gunter Koppelkamm; Hans-Joachim Kreisig; Ernst Freitag; Siegfried Barthel; Erwin Dimmel
Original assignee: Kombinat Polygraph Werner Lamberz VEB; Polygraph Leipzig Kombinat Veb
Current assignee: Kombinat Polygraph Werner Lamberz VEB; Polygraph Leipzig Kombinat Veb
Priority date: 1987-07-02
Filing date: 1988-05-19
Publication date: 1989-01-11
Anticipated expiration: 2008-05-19
Also published as: DE3812137A1; GB8811838D0; FR2617431B3; DD266233A3; GB2206534B; FR2617431A1; RU1827360C

Description

2 0 6 5 k31 1 + - 1 PLATE CYLINDER FOR A ROTARY PRINTING MACHINE The

present invention relates to a plate cylinder for a rotary printing machine and has particular reference to fastening of a print ing plate on the cylinder.

In DE-PS 1 945 535 there is disclosed a cylinder in which a hollow shaft, equipped with a recess for the introduction of the edges of a printing plate, and a solid shaft are rotatably arranged co-axially in a channel extending axially in the cylinder and receiving the bent edges of both ends of the printing plate. The shaft has a longitudinal groove into which the edge of the plate trailing in rotational direction of the cylinder is inserted by a rolled reinforcement, whilst the leading edge of the plate is inserted adjacent to the trailing edge of the plate, into a recess, open towards the solid shaft, of the hollow shaft. Whilst the printing plate is tightened by rotation of the inwardly disposed shaft, the rotatable hollow shaft with the printing plate untensioned serves for adjustment of the circumferential register.

It is disadvantageous in this cylinder that both the edges of the printing plate cannot be clamped separately. Thus, in case of the arrangement of several devices for mounting on the cylinder of a plate consisting of a plurality of discrete portions in circumferential direction, during the mounting or removal of such a plate portion the edge of the plate portion adjoining in circumferential direction is also loosened and partially displaced.

A further disadvantage is that that edge, which is trailing in rotational direction of the cylinder, must be rolled in additionally and therefore must be constructed to be relatively long.

4 Finally, the rotation of the hollow shaft is not effective for the actual clamping or tightening of the edges of the plate and the special arrangement of the hollow shaft in the plate cylinder and its utilisation as adjustable lay edge for the leading edge of the plate gives rise to doubts with respect to exact bearing of this edge in view of the hollow space present at the circumference of the cylinder Although the trailing edge of the plate is drawn into the channel on rotation of the shaft, an effective tightening force acting tangentially of the cylinder cannot be exerted on this edge due to the con- struction. This effect is, however, particularly desirable for a secure seating of t he plate on the cylinder in the case of high speed printing machines, so that rolling-out of the plate towards its trailing edge during running of the machine with an alternating bending stress endangering the strength of this edge is avoided.

It would thus be desirable to provide a plate cylinder which is relatively simple to manufacture and to operate and to which printing plates, which are equipped with simple bent end portions, including plates consisting of discrete portions in circumferential direction of the cylinder, can be fastened securely independently of the cylinder speed.

According to the present invention there is provided a plate cylinder for a rotary printing machine, the cylinder being provided at its circumference with a channel extending in the axial direction of the cylinder for reception of leading and trailing angled end portions of a flexible printing plate when mounted to extend around the cylinder and being further provided with plate fastening means comprising a shaft which is arranged in the cylinder to extend parallel to the axis thereof and which is provided with a first clamping strip extending into the channel, an inner hollow cylindrical member coaxially arranged on the shaft and provided with a slot through which the first clamping strip passes with rotational play and with a second clamping strip extending into the channel, and an outer hollow cylindrical member coaxially arranged on the inner member and provided with a slot through which the first and second clamping strips pass with rotational play and with a third clamping strip extending into the channel, the strips being so arranged in succession in the channel that the leading one thereof is engageable with the leading end portion of such plate and the intermediate and trailing ones thereof are respectively engageable with leading and trailing faces of the trailing end portion of such plate, and the shaft and the inner and outer members being relatively rotatable to effect clamping of said leading end portion against a leading wall of the channel by the leading strip as well as clamping of said trailing end portion between the intermediate and trailing strips and tensioning of the plate around the cylinder.

In a preferred embodiment the cylinder has at least one channel, which extends axially in the cylinder, receives the bent end portions of the plate and in which a hollow member, which has a slot parallel to the axis and of the width of the plate, and a shaft are rotatably arranged coaxially, so that both end portions of the plate can be clamped separately from each other and the trailing end portion of the plate can be tightened in tangential direction. To achieve this, a second, outer hollow member, which is parallel to the axis and of the width of the printing plate and equipped with a strip, is rotatably - 4 arranged co-axially on the inner member. A strip, which is parallel to the axis and passes with rotary play through the slots of both members, is connected with the shaft, and a strip, which is parallel to the axis and passes with rotary play through the slot of the outer member, is connected with the inner member, wherein the strip leading in rotational direction of the cylinder is pivotable as clamping strip against the leading end portion, lying against the adjacent side wall of the channel, of the plate, the trailing strip is pivotable as tightening strip against the inward side of the trailing end portion of the plate, and the intermediate strip is pivotable as clamping strip against the outward side of the trailing end portion. The plate fastening means permits a mutually independent clamping of both end portions and additionally a tightening of the trailing end portion. Thereby, a secure seating of the printing plate on the cylinder is ensured even in the case of a high-speed printing machine. In the case of division of plate into individual portions in circumferential direction of the cylinder, the end portions of any plate portion can be clamped and tightened as well as loosened without influencing the fastening of the succeeding plate portion. During removal of a plate, the trailing end portion clamped between the intermediate and trailing strips can be loosened through pivotation of these strips together in direction of the trailing side wall of the channel and, resulting therefrom, the leading end portion of the plate can be lifted out after release of its clamping from the leading side wall of the channel.

Thereupon, the printing plate can be taken off from the cylinder through appropriate rotation of the cylinder without a damage of the trailing end portion of the plate, whereafter the clamping of the trailing end portion of the plate is released.

Such fastening means has a small space requirement, low effort in production and assembly of the individual parts, high functional reliability and resistance to wear, and low maintenance needs. Moreover, the fastening means permits use of simple operating. elements.

In one embodiment, the leading strip is connected with the shaft, the intermediate strip with the inner member, and the trailing strip is connected with the outer member. In another embodiment, the leading strip is connected with the inner member, the intermediate strip with the shaft and the trailing strip with the outer member. In yet another embodiment, the leading strip is connected with the outer member, the intermediate strip with the shaft and the. trailing strip with the inner member. In a further embodiment, the leading strip is connected with the outer member, the intermediate strip with the inner member and the trailing strip with the shaft. In that case, the individual arrangements are to be regarded as functionally equivalent.

Whilst both leading and trailing strips can be associated with the shaft as well as with both hollow members, the intermediate strip can be connected only with the shaft or the inner member.

Expediently, the intermediate strip bears at the one side by way of resilient means, such as compression springs, against the leading strip and by its other side, in the untensioned and unclamped setting of the trailing end portion of the plate, against an abutment fixing its spacing from the trailing wall of the channel and passing through a bore in the trailing strip. Thereby, no separate operating elements are required for the actuation of the intermediate strip. Moreover, a uniform clamping force on the trailing end portion of - 6 the plate is exerted in axial direction by the resilient means.

The afore-mentioned effect is present, with further reduced space requirement, if the intermediate strip is constructed as a leaf spring which, in the untightened and unclamped setting of the trailing end portion, bears unpivotably under bias against an abutment- fixing its spacing from the trailing wall of the channel and passing through a bore in the trailing strip.

Alternatively, the intermediate strip, if not equipped with separate operating elements, can bear on one side by way of resilient means, such as compression springs, against the leading strip and on the other side, in the untightened and unclamped setting of the trailing end portion, by way of a pin, which is firmly connected with the inner member and passes pivotably through an opening in the outer member or is firmly connected with the shaft and passes through openings in the inner and the outer members, on an abutment fixing its spacing from the trailing wall of the channel, the abutment being arranged in a hollow space of a bridge of the cylinder.

It is possible to construct any of the strips selectably as leaf springs. Apart from the small space requirement for leaf springs, their elasticity can in addition be used functionally, for example for resilient retensioning of the trailing end portion of the printing plate.

In the variants without a separately actuable intermediate strip, the inner member or the shaft can be axially divided into several portions each separate from the other in dependence on the connection of this strip with the inner member or the shaft. The intermediate spaces obtained by the division can be utilised for the mounting of k 1 7 - the hollow members or shaft standing in connection with operating elements. This may simplify production of the plate fastening means.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, 5 in which:

Fig. 1 is a crosssection of a first plate cylinder embodying the Fig. 2 is a the is the Fig. 4 is Fig. 3 Fi 9. 5 Fi 9. 6 Fi g. 7 Fi g. 8 Fi 9. 9 Fig. 10 Fig. 11 invention; cross-section of a second plate cylinder embodying invention; a cross-section of a third plate cylinder embodying invention; a cross- section of a fourth plate cylinder embodying the invention; is a cross- section of a fifth plate cylinder embodying the invention; is a crosssection of a sixth plate cylinder embodying the invention; is a cross-section of a seventh plate cylinder embodying the invention; is a cross-section of an eighth plate cylinder embodying the invention; is a cross-section of a ninth plate cylinder embodying the invention; is a longitudinal sectional view on the line A-A of Fig. 5, showing a segmented inner hollow member of the cylinder; and is a view similar to Fig. 10, but showing a segmented - 8 shaft of the cylinder.

Referring now to the drawings, there is shown in Fig. 1 a plate cylinder 1 which has an axially extending channel 5 for receiving the bent end portions 2 and 3 of a printing plate 4. Arranged in a space communicating with the channel is a shaft 6, an inner hollow cylindrical member 9 arranged on the shaft, and an outer hollow cylindrical member 10 arranged on the member 9. The members 9 and 10 are provided with, respectively, slots 7 and 8, each of which is parallel to the cylinder axis and at least of the width of theprinting plate. Fastened in an axially parallel recess in the shaft 6 is a clamping strip 11, secured by screws to the shaft, for the end portion 2 of the plate 4 which leads in rotational direction of the cylinder 1. A clamping strip 12 welded to a longitudinal side of a recess 7 in the inner member 9, and a clamping strip 13 is secured by screws to the longitudinal side of a recess 8 in the outer member 10, the strips 12 and 13 serving to clamp the trailing end portion 3 of the plate 4.

The recesses 7 and 8 of the inner and outer members 9 and 10 are at least of such radial width that the strips 11 and 12 passing through them possess the rotary play required for the clamping operation for the leading end portion 2 and the clamping and tensioning operation for the trailing end portion 3.

For the separate actuation of the strips 11, 12 and 13, the shaft 6 and the inner and outer members 9 and 10 are connected at an end face of the cylinder with operating elements (not shown), for example setting levers limited in their movement by adjustable abutments and equipped with setting screws in combination with spring elements.

The leading end portion 2 of the printing plate 4 to be fastened on the cylinder 1 is introduced into the channel 5 and then brought into contact with and clamped to the leading wall of the channel by 7 - 9 the strip 11 through rotation of the shaft 6 to the left. Thereafter, the plate 4 is placed around the circumference of the cylinder 1 through appropriate rotation thereof and its trailing end portion 3 is then introduced radially into the gap between the strip 13 lying against the trailing wall 15 of the channel 5 and the strip 12 piyoted away to the left. The end portion 3 is then clamped through pivotation of the inner member 9 so that the strip 12 engages its outward side 16, while the inward side 17 lies against the strip 13. Finally, the thus clamped trailing end portion 3 is tensioned through a common pivotation of the strips 12 and 13 under rotation of the outer and inner members 10 and 9.

On removal of the printing plate 4, with reversal of the operations described so far, first the trailing end portion 3 is loosened so that, after unclamping of the leading end portion 2, the latter can be drawn off the circumference of the cylinder 1 during rotation thereof Finally, the end portion 3 can, after unclamping, be removed from the channel 5. This procedure ensures damage-free removal of the plate 4, since rolling-out or damaging of the trailing end portion 3, initially still secured in the channel 5, is prevented during rotat- ion of the cylinder 1.

In the case of a printing plate 4 consisting of a plurality of discrete portions in circumferential direction, several plate fastening devices, i. e. channels with shafts and inner and outer members, are provided for fastening of the plate portions. In that case, in Fig. 1, the leading end portion 2 belongs to the first portion of the plate and the trailing end portion 3 belongs to the last portion of the plate in circumferential direction of the cylinder 1. The separately - 10 actuable strips 11, 12 and 13 ensure mutually independent fastening of all the plate portions in circumferential direction of the cylinder.

Also possible is the separate fastening of several printing plate portions, making up the width of a single page, along the cylinder 1, in which case the operating elements for the single-page printing plate, respectively arranged inwardly and outwardly on the circumference of the cylinder, can be arranged alternately at both ends of the cylinder.

A bridge 18 can be detachably mounted by means of screws in the cylinder 1 and facilitates assembly as well as disassembly in the case of repair.

Figs. 2 to 4 show variants of construction of Fig. 1, which do not differ in respect of their basic_.function. In that case, in Fig. 2 in departure from Fig. 1, the strip 11 for the leading end portion 3 of the plate 4 is connected with the inner member 9 and the strip 12 for the trailing end portion 3 of the plate is connected with the shaft 6. In Fig. 3, the strip 11 for the leading end portion 2 is connected with the outer member 10 and the strip 13 for the trailing end portion 3 with the inner member 9. In Fig. 4 the strips 12 and 13 are connected with the inner member 9 and the shaft 6, respectively.

In Fig. 5, th.p strip 12 bears by way of several compression springs 19 along the cylinder 1 against the strip 11. On the other side, the pivotal movement of the strip 12 is limited by an abutment 21, which passes through a bore 20 in the strip 13 and is fastened in the cylinder at the wall 15 of the channel 5 so that on pivoting-back of the strip 13 with the abutment 21 at the same time coming out of the bore 20, an introductory gap arises for the trailing end portion R 3 (Fig. 6).

The particular advantage of the variants of construction shown in Figs. 5, 7 and 8 is that no operating elements are required for the strip 12 and this strip exerts a uniform clamping force on the end portion 3 along the cylinder 1.

As a consequence, the member 9 (Fig. 10 according to section A-A in Fig. 5), which carries the strip 12, or in modification the shaft 6 (Fig. 11), can be divided along the cylinder 1 into individual segments 22 and 23.

The fastening devices of Figs. 2 to 4 can be varied analogously to Fig. 5 with the manner of function remaining the same.

Fig. 7 shows a variant of Fig. 1 in which the inner member 9 carrying the intermediate strip, constructed as a leaf spring 24, is adjustably fixed, wherein the leaf spring 24, when the strip 13 is pivoted back, lies. under bias against the abutment 21 in accordance with the clamping force to be exerted. The function of the fastening device shown in Fig. 7 in that case corresponds to that of Fig. 5.

The fastening devices shown in Figs. 2, 3 and 4 can be varied analogously to Fig. 7 with the manner of function remaining the same, wherein the shaft 6 carrying the leaf spring 24 is adjustably fixed relative to the cylinder 1 in Fig. 7 in departure from the variants according to Figs. 2 and 3.

Fig. 8 shows a variant of Fig. 5, in which a pin 26 is connected with the inner member 9, Divotably passes through a cut-out 25 in the outer member 10, and in the unclamped and untensioned state of the trailing end portion 3 of the plate 4 bears against an abutment 28. The abutment is arranged in a hollow space 27 of the bridge 18 - 12 of the cylinder and fixes the spacing of the strip 12 from the wall 15 of the channel 5.

The fastening devices shown in Figs. 2, 3 and 4 can be varied analogously to Fig. 8 with the manner of function remaining the same, wherein in the variants according to Figs. 2 and 3 and in.departure from Fig. 8, the pin 26 is connected with the shaft 6 and passes through respective cut-outs in the inner and -also the outer member.

Fig. 9 shows a variant of Fig. 1, in which the strips 11, 12 and 13 are each replaced by a respective leaf spring 24, 29 and 30.

Apart from the relatively small space requirement for the leaf springs, their resilience can be used for the clamping of both end portions 2 and 3 of the plate 4 and in particular for a retensioning effect for the trailing end portion 3.

The device shown in Fig. 9 can be varied according to Figs. 2 to 4 as well, in the sense of selectable replacement of one or more of the strips 11, 12 and 13 by a respective leaf spring 24, 29 and 30.

11

Claims

1 A plate cylinder for a rotary printing machine, the cylinder being provided at its circumference with a channel extending in the axial direction of the cylinder for reception of leading and trailing angled end portions of a flexible printing plate when mounted to extend around the cylinder and being further provided with plate fastening means comprising a shaft which is arranged in the cylinder to extend parallel to the axis thereof and which is 'provided with a first clamping strip extending into the channel, an inner hollow cylindrical member coaxially arranged on the shaft and Drovided with a slot through which the first clamping strip passes with rotational play and with a second clamping strip extending into the channel. and an outer hollow cylindrical member coaxially arranged on the inner member and provided with a slot through which the first and second clamping strips pass with rotational play and with a third clamping strip extending into the channel, the strips being so arranged in succession in the channel that the leading one thereof is engageable with the leading end portion of such plate and the intermediate and trailing ones thereof are respectively engageable with leading and trailing faces of the trailing end portion of such plate, and the shaft and the inner and outer members being relatively rotatable to effect clamping of said leading end portion against a leading wa 11 of the channel by the leading strip as well as clamping of said trailing end portion between the intermediate and trailing strips and tensioning of the plate around the cylinder.

2. A plate cylinder as claimed in claim 1, wherein the leading strip is the first strip, the intermediate strip is the second strip and the trailing strip is the third strip.

3. A plate cylinder as claimed in claim 1, wherein the leading strip i s the second strip, the intermediate strip is the first strip and the trailing strip is the third strip.

4. A plate cylinder as claimed in claim 1, wherein the.leading strip is the third strip, the intermediate strip is the first strip and the trailing strip is the second strip.

5. A plate cylinder as claimed in claim 1, wherein the leading strip is the third strip, the intermediate strip is the second strip and the trailing strip is the first strip.

6. A plate cylinder as claimed in any one of the preceding claims, comprising resilient means arranged to urge the leading and intermediate strips apart and an abutment extending through a bore in the trailing strip and engageable with the intermediate strip to limit movement thereof towards a trailing wall of the channel.

7. A plate cylinder as claimed in any one of claims 1 to 5, wherein the intermediate strip is constructed as a leaf spring and the cylinder comprises an abutment extending through a bore in the trailing strip and engageable with the intermediate strip to limit movement thereof towards a trailing wall of the channel.

8. A plate cylinder as claimed in either claim 2 or claim 5, comprising resilient means arranged to urge the leading and intermediate strips apart, a pin connected to the inner member and extending with rotational play through an opening in the outer member, and an abutment arranged in a hollow space in the cylinder and engageable with the pin to limit movement of the intermediate strip towards a trailing wall of the channel.

9. A plate cylinder as claimed in either claim 3 or claim. 4, comprising resilient means arranged to urge the leading and intermediate strips apart, a pin connected to the shaft and extending with rotational play through openings in the inner and outer members, and an abutment arranged in a hollow space in the cylinder and engageable with the pin to limit movement of the intermediate strip towards a trailing wall of the channel.

10. A plate cylinder as claimed in any one of claims 1 to 5, wherein at least one of the strips is constructed as a leaf spring.

11. A plate cylinder as claimed in either claim 3 or claim 4, wherein the inner member is divided into a plurality of separate length portions.

12. A plate cylinder as claimed in either claim 2 or claim 5, wherein the shaft is divided into a plurality of separate length portions.

13. A plate cylinder substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

14. A plate cylinder substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

- 16

15. A plate cylinder substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.

16. A plate cylinder substantially as hereinbefore described with reference to Fig. 4 of the accompanying drawings.

17. A plate cylinder substantially as hereinbefore described with reference to Figs. 5 and 10 of the accompanying drawings.

18. A plate cylinder substantially as hereinbefore described with reference to Fig. 6 of the accompanying drawings.

19. A plate cylinder substantially as hereinbefore described with 10 reference to Fig. 7 of the accompanying drawings.

20. A plate cylinder substantially as hereinbefore described with reference to Fig. 8 of the accompanying drawings.

21. A plate cylinder substantially as hereinbefore described with reference to Fig. 9 of the accompanying drawings.

22. A plate cylinder substantially as hereinbefore described with reference to Fig. 11 of the accompanying drawings.

Published 19893 at The Patent Office. State House. 66.71 High Holborn, London Y7C1R 4TP. Further copies may be obtained from The Patent ofnce, Sales Branch, St Mary Cray. Orpington, Kent. BW 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con. 1187.