GB2139956A

GB2139956A - Printing plate carrier for a rotary printing machine

Info

Publication number: GB2139956A
Application number: GB08402798A
Authority: GB
Inventors: Hotst Eichhorn; Erwin Dimmel; Harald Feustel; Ernst Freitag
Original assignee: Kombinat Polygraph Werner Lamberz VEB; Polygraph Leipzig Kombinat Veb
Current assignee: Kombinat Polygraph Werner Lamberz VEB; Polygraph Leipzig Kombinat Veb
Priority date: 1983-02-09
Filing date: 1984-02-02
Publication date: 1984-11-21
Also published as: SU1486360A1; IN161636B; DD228963A3; GB8402798D0; DE3401336C2; DE3401336A1; FR2540433B1; FR2540433A1; GB2139956B

Abstract

A printing plate carrier comprises a plate cylinder (1) provided with a recess (2) which extends axially in the cylinder and is inclined by its opening in the rotational direction of the cylinder. Passing through the recess (2) are pins (6) for a printing plate (3), which has bent front and rear end portions (14, 15) that are slotted to fit the pins. A strip (8) is arranged in the recess (2) and is narrower compared therewith by at least twice the thickness of the plate (3), the strip having bores (9) with a play fit for the pins (6). <IMAGE>

Description

SPECIFICATION Printing plate carrier for a rotary printing machine The present invention relates to a printing plate carrier for a rotary printing machine.

A known arrangement for the fastening of flexible printing plates (DE-PS 1 960 635) comprises a plate cylinder having at least one recess which in width is about equal to the thickness of two printing plates and extends axially in the cylinder. The recess is inclined by its opening in the rotational direction of the cylinder and positioning pins, which are fastened in the cylinder, pass through the recess. The two end portions, which are bent in dependence on the inclination of the recess and have slots for the pins, of the printing plate resting on the cylinder circumference are held without additional means.

It is disadvantageous in this arrangement that, to prevent the two end portions of the printing plate from slipping out of the recess during the printing operation, this recess must be made very narrow.

This has the consequence of time and cost in its production. Moreover, foreign matter in the printing process can be removed therefrom only with relative difficulty. In addition, the end portions of the printing plate, which are relatively freely movable in the recess, impose certain limits in printing speed.

It would thus be desirable to simplify the production of the plate carrier, to reduce the effort involved in its maintenance and to increase its functional reliability.

According to the present invention there is provided a printing plate carrier for a rotary printing machine, the carrier comprising a cylinder provided with an axially extending recess which opens at the cylinder circumference to permit reception of bent front and rear end portions of at least one flexible printing plate of a given thickness and which is so inclined that the opening of the recess leads the base thereof in an intended direction of rotation of the cylinder, a plurality of positioning pins mounted in the cylinder to extend through the recess and through slots in the plate end portions when received in the recess, and a locating strip arranged in the recess and provided with bores receiving the pins with play, the width of the strip being less than that of the recess by an amount equal to at least twice said plate thickness.

In a preferred embodiment of the invention, a carrier for a flexible printing plate comprises a plate cylinder with at least one recess which extends axially in the cylinder and is inclined by its opening in the rotational direction of the cylinder. Passing through the recess are positioning pins, fastened in the cylinder, for the printing plate, which is provided at its front and rear ends with bent end portions slotted to fit the pins.In order that the recess can be mechanically produced in rotational manner and later to be cleaned free of problems, and particularly so that the leading end portion of the plate is held to the extent required for the printing operation and that additional location of the trailing end portion of the plate is possible for a rapidly running rotary printing machine, there is arranged in the recess a strip which is narrower than the recess by at least twice the thickness of the plate and which has bores with a play fit for the pins.

Through the arrangement of a simply producible strip in the recess, the recess can be made so wide in dependence on the thickness of the strip so that it can be manufactured through a simple milling operation in the cylinder. Since particularly the location of the plate leading end portion in the cylinder is endangered with rising rotational speed of the cylinder, the force component, directed towards it by reason of the special inclination of the recess and resulting fron the centrifugal force of the strip, acts positively in this respect.

The insertion of the bent end portions of the plate into the recess is facilitated if the strip has a bevel or rounding on one or both longitudinal sides at the circumference of the cylinder.

For the avoidance of excessive loading of the pins during a printing process, it is advantageous if the strip is set back relative to the circumference of the cylinder.

The cleaning of the recess is considerably facilitated if the strip can be previously removed from the recess. The same manner of procedure is possible during exchange of the printing plates, in that the strip previoulsytaken out of the recess is pressed back into the recess after hooking-in of the two end portions of the plate or plates. For this purpose the bores for the pins are each enlarged in the longitudinal direction of the strip to form a respective elongate hole which, outside the setting of the pins with the strip mounted, passes over into a slot directed into the interior of the recess, wherein the elongate hole and the slot possess at least the width of the diameter of the bore.

In this case, for the purpose of preventing the strip from dropping out of the recess, an abutment means, which is detachably fastened laterally at the cylinder, is arranged at the end face of the strip.

For the relief of the pins and additional securing of the strip, a holding device, which engages over a step of the strip or into a bore or end face of the strip, can be detachably fastened laterally at the cylinder.

If the strip is to be frequently removed from the recess, for example for each changing of the printing plate, then it is advantageous if the bores for the pins are each enlarged in the strip to form a respective slot directed into the interior of the recess end of at least equal width, so that the strip can be introduced into and removed from the recess directly perpendicularly. In that case, the strip must be secured in the recess with the aid of a holding device, in a manner as already described, at both end faces. This arrangement is particularly suitable for a largely play-free insertion of the strip into the recess already receiving the two end portions of the plate, which acts positively towards secure seating of the plate on the cylinder at high printing speed.

Pressing of the strip into the recess after insertion of the end portions of the plate is facilitated, and the clamping effect exerted on the end portions is enhanced, if the cross-section of the strip narrows in wedge shape in direction of its side facing the base of the recess. At very high printing speed, the increasing centrifugal force of the plate causes the plate trailing end portion to also be disposed free of play in the recess, which is of advantage for the printing process. The wedge-shaped strip is thus particularly suitable in this case.

The insertion of a strip of preferably rectangular cross-section into the recess can be facilitated if the strip has a bevel or rounding on one or both longitudinal sides at the base of the recess. In this case, bevels or roundings are not required for the strip at the circumference of the cylinder For high printing speeds it is favourable if the strip pressurably bears against that end portion of the printing plate which is leading in the rotational direction of the cylinder. It is of further advantage that, after the introduction of that plate end portion into the recess, the strip, pressed against this portion, on its other side offers good conditions for the insertion of the trailing end portion of the plate.

This can be realised in an advantageous manner if the strip projects laterally of the cylinder and, at its side leading in the rotational direction ofthe cylinder, bears against a screw guided in a holder fastened at the end face of the cylinder.

In connection with exchange of the strip, the latter lets itself be secured simply in this case of the screw has a step which is of smaller diameter compared with the screw diameter externally of the strip and which engages with play in a bore in the strip.

Embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Figure 1 is a cross-section of part of a first plate carrier embodying the invention; Figure 2 is a sectional view of part of a second plate carrier embodying the invention; Figure 3 is an end view of part of the plate carrier of Figure 2; Figure 4 is an end view of part of a third plate carrier embodying the invention; Figure 5 is a sectional view on line A-A of Figure 4, showing a modification in chain-dotted lines; Figure 6 is a partly sectional end view of part of a fourth plate carrier embodying the invention; Figure 7 is a cross-section of part of a fifth plate carrier embodying the invention; and Figure 8 is a partly sectional end view of a sixth plate carrier embodying the invention.

Referring to the drawings, there is shown in Figure 1 part of a plate carrier comprising a plate cylinder 1 having an axially extending recess 2 which is inclined by its opening in the rotational direction, marked by an arrow, ofthe cylinder. This recess can, in dependence on the number of printing plates 3 over the width of the cylinder 1 extend over the entire width or only part of the width of the cylinder.

Passing through the recess 2, perpendicularly to side surfaces 4 and 5 thereof, are postioning pins 6, which are pressed into corresponding bores 7 in the cylinder 1 and end flush with the cylinder circumference.

Arranged in the recess 2 is a strip 8, which is narrower by at least twice the thickness of the plate 3 and has a respective bore 9 to receive with play each of the pins 6, so that the strip 8, which does not rest on the base of the recess 2, can be displaced in the recess in axial direction of the pins 6 in dependence on spatial conditions.

The front and rear end portions 14 and 15 of the printing plate 3, which were previously bent in a special device, are pushed into gaps 10 and 11 between the strip 8 and the side surfaces 4 and 5, respectively, of the recess, for which purpose the end portions 14 and 15 have perpendicular slots 12 and 13 in the region of the pins 6 adjusting the plate 3 on the cylinder 1. In that case, the end portion 14, which is leading in rotational direction of the cylinder 1 and particlarly stressed during the printing operation, is held at an acute angle by reason of the inclination of the recess 2 and the less stressed trailing end portion 15 is held at an obtuse angle to the cylinder circumference.

If two printing plates 3 are to be fastened on the plate cylinder 1 around its circumference, then two recesses 2 with associated pins 6 must be arranged at a 180 spacing at the circumference. In this case, the trailing end portion 15 would belong to the second printing plate.

To facilitate insertion of the end portions 14 and 15 of the plate 3, the strip 8 is provided at both sides with a respective bevel 16 and 17 at the circumference of the cylinder 1.

During laying of the plate 3 onto the cylinder 1, the leading end portion 14 of the plate is first introduced into the gap 10. In that case the strip lies against the oppositely disposed side surface 5 of the recess 2.

The location of the plate 3 in axial direction of the cylinder 1 takes place through the pins 6 in the slots 12 of the plate 3.

While the cylinder 1 is rolled along, the flexible printing plate 3 is guided around the circumference of the cylinder and its trailing end portion 15 is pushed into the gap 11 after displacing of the strip 8 on the positioning pins 6 against the end portion 14.

In order to avoid too high a loading of the pins 6, the strip 8 is set back somewhat relative to the circumference of the cylinder 1.

The force component of the centrifugal force of the strip 8 directed towards the leading end portion 14 increases with increasing rotational speed of the cylinder 1, whereby the location of the plate 3 on the cylinder is enhanced.

Figure 2 shows an embodiment with an exchangeable strip 8 in mounted setting. In this case, the bores 9 forthe pins 6 are each enlarged in the strip 8 in the longitudinal direction thereof to form an elongate hole 18, which outside the setting of the pins 6 with the strip mounted passes over into a slot 19 directed into the interior of the recess 2.

With this arrangement, the strip 8 can be readily removed from the recess 2 for the purpose of cleaning the latter. In addition, it is possible during exchange of the plate 3 to firstly hook the two end portions 14 and 15 into the recess 2 and only subsequently to press the strip 8 into the recess 2 and to locate it by a corresponding longitudinal displacement on the pins 6.

In order to prevent the strip 8 from falling out during the printing operation, this strip is to be secured by suitable technical means against longitu dinal displacement.

Figure 3 shows an abutment 24 for this purpose, which abutment lies against the end face of the strip 8 and is fastened laterally at the cylinder 1 by means of two screws 20 and 21 through elongate holes 22 and 23. This abutment can also be constructed to be pivotably or tiltably fastened to the cylinder 1 while observing the possibility of a location in a setting securing the strip 8.

Figure 4 shows a holding device 29, which is fastended laterally at the cylinder 1 by means of screws 25 and 26 through elongate holes 27 and 28 for the additional securing of the strip 8 and possesses a recess 30, into which a step 31, arranged at the end face, of the strip 8 so engages that the latter is movable only in the axial direction of the pins 6. As is evident from Figure 5, the sectional illustration relating to Figure 4, the holding device 29 also fufuls the task of the abutment 24 shown in Figure 3 in the sense of the securing of ths strip 8 against a longitudinal displacement.

The holding device 29, too, can be constructed to be pivotable ortiltable in order to facilitate exchange of the strip 8.

In Figure 6, a holding device 34, which is similarly fastened by two screws 32 and 33 to the cylinder 1, engages by a pin 35 analagouslyto the pins 6 into a bore 36 of the dtrip 8 laterally projecting beyond the cylinder 1. In the case of frequent exchanging of the strip 8, the strip 36 could be formed with a recess open at the end side or the holding device 34 could be constructed to be displaceable in axial direction of the bore 36 with a pin 35 mounted only at one end or, in imitation of Figure 4, could be provided with a step.

In Figure 5, chain-dotted lines show that each bore hole 9 can be enlarged into an at least equally wide slot 37 directed into the interior of the recess 2. In this case the strip 8 must be secured at both ends by respective holding devices 29 to prevent the strip from dropping out of the recess 2. This arrangement offers the advantage that, for example, the strip 8 can be removed from the recess relatively simply on each change of the plate 3 and also can be pressed to the largest extent free of play into the recess 2 already receving the end portions 14 and 15 of the plate 3. For this purpose, the strip 8 is with advantage provided with bevels 38 and 39 at both adges of the side facing the base of the recess 2 (Figure 4).

The last-mentioned embodiment offers advantages for secure seating of the printing plate at high printing speed.

Figure 7 shows an embodiment in which the strip 8 has a cross-section which narrows in wedge shape in direction of its side facing the base of the recess 2.

The strip 8 fully pressed into the recess 2 effects a play-free pressing of both end portions 14 and 15 against the respective side surfaces 4 and 5 of the recess 2 so that the end portions do not detach from the recess 2 even at high printing speed.

Figure 8 shows an embodiment woth an additional securing of the leading end portion 14, particularly loaded at high printing speeds, of the plate 3. A holder 42, which is fasteneay two screws 40 and 41 to the end face of the cylinder 1, has a threaded bore in which a screw 43 is guided. The screw 43 bears against the side, leading in rotational direction of the cylinder 1, of the strip 8 at a portion thereof projecting laterally of the cylinder. For the introduction of the end portion 14, the screw 43, guaranteeing the unhindered movability of the strip 8 in the recess 2, is screwed back in the holder 42. After completion of this operation, the strip 8 is pressed, through actuation of the screw 43, against the end portion 14, whereby the gap 11 for the insertion of the end portion 15 is enlarged at the same time.

In the case of an exchangeable strip 8, the screw 43 additionally takes over a retaining function for the strip 8 in that a step 44 of the screw engages with play into a bore 45 in the strip. The step 44 is of smaller diameter compared with the screw diameter externally of the strip 8 and thereby inhibits all possibilities of movement of the strip 8 except in the longitudinal direction of the pins 6.

Claims

1. A printing plate carrier for a rotary printing machine, the carrier comprising a cylinder provided for with an axially extending recess which opens at the cylinder circumference to permit reception of bent front and rear end portions of at least one flexible printing plate of a given thickness and which is so inclined that the opening of the recess leads the base thereof in an intended direction of rotation of the cylinder, a plurality of positioning pins mounted in the cylinder to extend through the recess and through slots in the plate end portions when received in the recess, and a locating strip arranged in the recess and provided with bores receiving the pins with play, the width of the strip being less than that of the recess by an amount equal to at least twice said plate thickness.

2. A carrier as claimed in claim 1, wherein the strip is provided with bevelled or rounded longitudinal edge portions in the region of the cylinder circumference.

3. A carrier as claimed in claim 1, wherein the strip is wholly disposed in the recess at a spacing from the cylinder circumference.

4. A carrier as claimed in any one of the preceding claims, wherein each of the bores in the strip communicates with a respective first slot portion which extends in the strip longitudinally thereof and which communicates with a respective second slot portion extending in the strip to open at a side facing the base of the recess, the width of the first and second slot portions being at least substantially equal to the diameter of the bore.

5. A carrier as claimed in claim 4, comprising abutment means detachably mounted at one end of the cylinder in abutment with one of the ends of the strip.

6. A carrier as claimed in any one of claims 1 to 3, comprising a holding member detachably mounted at one end of the cylinder in engagement with a step in the strip.

7. A carrier as claimed in any one of claims 1 to 3, comprising a holding member detachably mounted at one end of the cylinder and engaged in a bore or recess in an end portion of the strip.

8. A carrier as claimed in either claim 6 or claim 7, wherein each of the bores in the strip communicates with a respective slot which extends in the strip to open at a side of the strip facing the base of the recess and the width of which is substantially equal to the diameter of the bore.

9. A carrier as claimed in either claim 4 or claim 8, wherein the width of the strip continuously reduces in direction towards the base of the recess.

10. A carrier as claimed in either claim 4 or claim 8, wherein the strip is provided with at least one bevelled or rounded longitudinal edge portion at a side thereof facing the base of the recess.

11. A carrier as claimed in any one of the preceding claims, wherein the strip is so arranged as to in use pressurably bear, at the side thereof trailing in said direction of rotation, against an adjacent one of such plate end portions.

12. A carrier as claimed in claim 11, wherein a portion of the strip protrudes from the cylinder at one end of the cylinder and an adjustable screw is mounted at said one end of the cylinder and arranged to bear on the protruding portion of the strip at the side thereof leading in said direction of rotation.

13. A carrier as claimed in claim 12, wherein the screw is provided at its free end with a reduced diameter portion engaged with play in a bore in the strip.

14. A printing plate carrier substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

15. A printing plate carrier substantially as hereinbefore described with reference to Figures 2 and 3 of the accompanying drawings.

16. A printing plate carrier substantially as herein before described with reference to Figures 4 and 5 of the accompanying drawings.

17. A carrier as claimed in claim 16 and modified substantially as herein before described with reference to Figure 5 of the accompanying drawings.

18. A printing plate carrier substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.

19. A printing plate carrier substantially as herein before described with reference to Figure 7 of the accompanying drawings.

20. A printing plate carrier substantially as hereinbefore described with reference to Figure 8 of the accompanying drawings.