GB2067468A

GB2067468A - Register system for the in-register aligning of a flexible printing plate

Info

Publication number: GB2067468A
Application number: GB8001724A
Authority: GB
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1980-01-18
Filing date: 1980-01-18
Publication date: 1981-07-30

Abstract

Register system for the in-register alignment of a flexible printing plate 9 on the plate cylinder 2 of a rotary printing press wherein at least two register punch holes 14 are provided in the plate 9 and corresponding marks 12 are provided on the plate cylinder 2, the register marks 12 being in the form of areas similar to but smaller than the punch holes 14, and lying substantially level with the surface of the printing plate, but being of a contrasting nature. Contrasting blackened shadow joints 16 may be provided between the holes 14 and areas 12, which may be highly polished. The holes 14 and areas 12 may be circular or polygonal. Register bolts 8 may provide the similar areas, and these may have studs which are smaller than the holes 14. Alternatively, annular grooves may be provided in the face of the bolts 8, or directly in the face of the plate cylinder 2. <IMAGE>

Description

SPECIFICATION Register system for the in-register aligning of a flexible printing plate The invention concerns a register system forthe in-register aligning of a flexible printing plate on the plate cylinder of a rotary printing press with at least two register punch holes provided in the printing plate and corresponding register marks in the plate cylinder.

In principle, there are two essential groups of register systems: With the first group, the plate is indirectly aligned on the cylinder, i.e. primary elements are provided for aligning the plate in the clamping rails and secondary elements are additionally provided for aligning the clamping rails on the cylinder.

The second group dispenses with this roundabout approach. The plate is directly aligned with respect to the cylinder body. The invention in question is to be assigned to the latter group.

The DE-PS 830 343 describes a method for the in-register clamping in position of printing plates in which, after-the copying of the printing plate, it is provided with coarse punch holes in the region of register crosses which have been copied onto the printing plate, so that the register crosses can be brought into line with register markings, likewise cruciform, provided on the plate cylinder. In the course of recent years this method has proven quite successful since it provides a direct and relatively fast way of aligning a printing plate whereby deformations in the plate due to the printing plate clamping rails do not have any negative effect on the adjusting system.However, this method has the disadvantage that the two coarse punch holes are not constituent parts of a register system and that the printing plate is aligned exclusively by the register crosses copied onto the plate. DE-PS 20 10 899 describes a device of the type initially mentioned which obviates the disadvantages of the aforementioned method. Rigid register pins are provided on a common base strip mounted on the front wall of the cylinder gap. These register pins are rectangular in cross-section and projectthrough register slots provided at the leading edge of the printing plate. The front edges of the register pins serve as a stop for the edges of the register slots. There is, however, the disadvantage that the edges of the register slots are deformed by the register pins when the printing plate is adjusted or clamped circumferentially.Any damage to a register slot incurred during clamping is sufficient to make it no longer possible to pre-align the plate in register during the initial or any subsequent mounting operation. Furthermore, one of the disadvantages of this device in practice is that if a plate has been copied askew, there is no possibility of correction. If, for example, one side of the plate has to be corrected with respect to the other side, the plate already being in contact with the stops, then all that can be done first of all is to reduce the plate tension on the side in question in order, for example, to obtain a parallel line for the leading edge. Subsequentto this operation it is necessary to make an additional circumferential register adjustment of the entire plate cylinder A corresponding device is, therefore, indispensable.

Proceeding from this state of the art, the object of the invention in question is to create an easy-tooperate register system which compulsorily guarantees that the accuracy obtained when making the printing plate is retained when it is used on the press and which permits the precise alignment of a printing plate within a very short space of time without damaging or deforming the register punch holes.

The invention achieves this aim using a register system of the type initially mentioned in which the register marks have the form of areas similar to and smaller than the register punch holes lying at most on a level with the surface of the printing plate and contrasting with their surroundings.

With such an arrangement the fixing, clamping and adjustment of the printing plates does not have any negative influence on the punch holes of the register system and the printing plates can, even with repeated use, be quickly brought into correct register irrespective of deformations and damage in the front edge clamping area, with the result that, in order to obtain a multi-colour print in correct register, it is virtually always unnecessary to re-adjust the printing plates, although the system allowsforthis.

So that any deviations of the printing plate from its in-register position can be noticed particularly easily, a further elaboration of the invention provides for contrasting shadow joints between the register punch holes and the similar areas.

In order to increase the accuracy of adjustment of the register system a further development of the invention provides for the shadow joints to have a uniform width of a few tenths of a millimetre.

In order to keep production costs as low as possible, an advantageous embodiment of the invention employs register punch holes and areas similar to the latter which are circular in shape. Furthermore, as a completely symmetrical figure, the circle offers the ideal method of alignment.

In a further embodiment of the invention the register punch holes and the areas similar to the latter are polygonal in shape. A straight shadow joint or its extension can likewise provide advantages as regards optical alignment.

A practical embodiment of the invention features as similar areas the faces of register bolts mounted in the plate cylinder with the faces pointing towards the printing plate. Such a simple structural arrangement makes for low-cost production and also makes it possible to equip existing plate cylinders with the register system. Furthermore, the similar areas used for the alignment of the printing plate can easily be replaced if they become dirty or worn.

Further advantageous embodiments of the invention are contained in the following description and in Sub-Claims 3 and 9 to 14.

The drawings originally filed were informal and the print here reproduced is taken from a later filed formal copy.

The invention is described below in greater detail on the basis of the drawing in the form of a basic design and five specimen embodiments.

Fig. 1 shows a partial side view of a basic design of a register system according to the invention in the form of a cut-out section from a plate cylinder Fig. 2 shows a top view of Fig. 1 Fig. 3 shows a cut-out section from a cylinder gap with a top view of a non-aligned printing plate with the register system atthe leading edge Fig. 4 shows the same view as in Fig. 3 with a top view of an aligned printing plate Fig. 5 shows a top view of a plate cylinder with an additional third register bolt positioned at the leave Fig. 6 shows a partial diagramatic side view of a first specimen embodiment of the register system Fig. 7 shows the same view as in Fig. 6 of a second specimen embodiment of the register system Fig. 8 shows the same view as in Fig. 6 of a third specimen embodiment of the register system Fig. 9 shows the same view as in Fig. 6 of a fourth specimen embodiment of the register system Fig. 10 shows the same view as in Fig. 6 of a fifth specimen embodiment of the register system and Fig. 11 shows a top view of Fig. 10.

As shown in Figs. 1 to 5, in a basic design of the invention retaining pieces 4 are mounted at an exact distance from one another and with their axes parallel in respect of one another on both sides of the cylinder gap 1 of a plate cylinder 2 on the side facing the leading edge and are adjustable in the axial direction of the cylinder gap 1 by means of bolts 3.

Screwed onto each retaining piece 4 is an intermediate member 6 which is vertically adjustable by means of adjusting screws 5. The intermediate member 6 is provided with a through hole 7 which accommodates a register bolt 8.

At its end facing a printing plate 9 projecting into the cylinder gap 1, the register bolt 8 is provided with a tight-fitting plug-in sleeve 10, the face side of which is equipped with a circular recess 11 and finishes flush with the face 12 of the register bolt 8.

The face 12 of the register bolt 8 as well as the plugin sleeve 10 mounted on the latter are both surfaceground and brightly polished similarly to the surface of the printing plate. The base of the circular recess 11 surrounding the register bolt 8 contrasts with the face 12 of the register bolt 8 contrasts with the face 12 of the register bolt 8 enclosed by it, with the annularsurface of the plug-in sleeve 10 surrounding it and with the surface of the printing plate 9. This may be achieved, for example, by deadening or dulling.

Black is the preferred colour for the circular recess 11 which thus forms a clear visual contrast with the aforementioned surfaces.

When the printing plate 9 is mounted, i.e. when it is lying flat, there is a gap 13 of a few hundredths of a millimetre between the bottom edge of the printing plate and top edge of the register bolt. However, this gap is not absolutely necessary and can also be dis pensed with.

The printing plate 9 projecting into the cylinder gap 1 is clamped in its clamping range 19 by means of clamping screws 15 represented in diagrammatic form in Fig. 5 in the clamping rails 18 of a printing plate clamping device, as the one known, for e::am ple, from the DE-PS 23 10228, which is not rep resented or described in any greater detail. During or before the copying of the plate, the printing plate 9 has, by means of a register hole punch, been provided in the region of the register bolts 8 at the lead ing edge with two circular register punch holes 14, precisely spaced as are the register bolts 8, the diameter of the register punch holes 14 being a few tenths of a millimetre larger than that of the faces 12 or the register bolts 8.The circular recesses 11 have a darker colouring than their surroundings and those regions of them lying between the register punch holes 14 and the register bolts 8 which can be viewed from above the printing plate 9 form easily perceptible, contrasting shadow joints 16.

The system used for applying the films to the printing plates 9 in correct register in relation to the register punch holes 14 is not discussed in any greater detail since it does not fall within the scope of the invention. It is, of course, self-evident that the register punch holes 14 are punched eithertogetherwith the punch holes for aligning the film or that the register punch holes 14 are used directly to align the film.

The operation of the basic design of the register system forthe in-register aligning of the printing plate 9 on the plate cylinder 2 is as follows.

The printing plate is clamped in the normal manner in the clamping rails 18 using the clamping screws 15. In order now to align the printing plate in exact register, the printer sights the faces 12 on the register bolts 8 through the two circular register punch holes 14 of the printing plate 9 whose axes are parallel to one another and brings these into line with one another.

Before aligning the printing plate, the printer is presented with a picture like that shown in Fig. 3. The two register punch holes 14 of the printing plate 9 are eccentricallyoffsetwith respectto the faces 12 of the register bolts 8 similar to the latter This can be seen particularly clearly due to the eccentric offset of the shadow joints 16 surrounding the faces 12 with respect to the corresponding register punch holes 14.

Using adjusting screws of the printing plate clamping device which is not represented or described in any greater detail, the front edge of the printing plate held by the printing plate clamping rails is now adjusted and aligned until there is concentric agreement between the two register punch holes 14 of the printing plate 9 and the two faces 12 of the register bolts 8.

The warping or compressing of the front edge of the printing plate as a result of its being clamped in no way affects the register punch holes 14 of the register system used, with the result that the printing plates 9 equipped with this register system which have already been aligned once can readily be re used, i.e. they can be clamped and newly aligned repeatedly without the accu racy of the register system obtained during production being lost thereby.

The contrasting colouring of the recesses 11 which serve as shadow joints 16 in the basic design of the register system and the small width of the shadow joints 16 of only a few tenths tenths of a millimetre make the register system highly accurate, as a result of which the printer is very easily able to perceive even the slightest eccentric offset of the faces 12 with respect to the register punch holes 14 and thus to eliminate minimal deviations of the printing plate 9 from its in-register position. Practice has proved that, owing to the high accuracy of the register system, one alignment of the printing plates 9 is completely sufficient in order to obtain an in-reguiator multi-colour print.

Also of particular advantage is the fact that precisely because of its above-mentioned accuracy this register system can be used alone or also as an addition to existing, less accurate systems.

In order to provide additional assistance with the lateral aligning of the printing plate 9 at the leave, it is possible, as shown in Fig. 5, to position an additional, third register bolt 8 of the same structural arrangement in the centre on the side of the cylinder gap 1 facing the leave. Since different interlay thicknesses may result in different printing lengths in the circumferential direction too, it is, for this reason, not possible to use any individual circular register punch holes 14 at the leave like those at the leading edge.

Instead, the back region of the printing plate must be provided with an oblong hole 20, the side edges of which must, when the printing plate 9 is aligned, be at the same distance from the face 12 of the back register bolt 8 (Fig. 5). However, an additional register bolt 8 at the leave is not essential to the invention.

In a first specimen embodiment of the register system as shown in Fig. 6, the register bolts 8 are provided, on their end facing the printing plate 9, with a circular stud 21, the diameter of which is slightly smaller than the corresponding circular register punch hole 14 of the printing plate 9. In this embod imentthe shadow joints 16 are formed by that part of the annular surfaces of the register bolts 8 surrounding the circular studs 21 which can be viewed through the circular register punch holes 14 of the printing plate.

A second specimen embodiment of the register system shown in Fig. 7 has, as shadow joints, ring grooves 22 sunk into the faces of the register bolts 8, the inside diameter of which is slightly, preferably a few tenths of a millimetre, smaller than that of the corresponding register punch holes 14 in the printing plate 9. The preferred colourforthe ring grooves 22 is black. in this embodiment the shadow joints 16 are formed by the ring groove regions lying between the register punch holes and the inside diameter of the ring grooves 22, these regions being visible from above the printing plate 9.

The register bolts 8 of a third specimen embodiment of the register system are provided on their face side with blind holes 23 slightly smaller in diameter than the register punch holes 14 of the printing plate 9. In this specimen embodiment the separate contrasting of individual surfaces is not absolutely necessary, yet promotes the contrasting effect since the contrast of the area decisive as regards the alignment of the printing plate 9 resuits from the base of the blind hole 24 which is darker than its surroundings. Depending on the depth of the blind holes 23, the base 24 may be lighter or darker (Fig. 8).

In a fourth specimen embodiment of the register system shown in Fig. 9 the ring grooves 22 are sunk directly into the surface of the plate cylinder 2 without the interposition of register bolts 8. In this case, the similar areas used for aligning the printing plate 9 are circular areas 17 of the plate cylinder 2 enclosed by the ring grooves 22. The shadow joints 16 are formed by the regions of the contrasting ring grooves 22 which can be viewed from above the printing plate 9. These regions lie between the circular register punch holes 14 and the inside diameter of the ring grooves 22.

Of course, instead of being circular, the similar surfaces used for aligning the plate may also be polygonal. This is the case in a fifth specimen embodiment of the register system shown in Figs. 10 and 11 in which the register punch holes 14 of the printing plate 9 and the faces 12 of the register bolts 8 similar to and smaller than the latter are triangular in shape, preferably in the form of equilateral triangles. The faces 12 are located on triangular studs 25 at the ends of the register bolts 8. The regions of the stepped register bolts 8 lying between the register punch holes 14 and the studs 25 form the shadow joints 16 when viewed from above the printing plate 9.

Of course, the invention is in no way restricted to the embodiments described above and represented in Figs. 1 to 11.These embodiments should merely be viewed as examples which do not restrict the scope of the invention. It goes without saying that other embodiments are also conceivable with numerous modifiations to structural details still lying within the scope of the invention.

Thus, for example, other curved shapes or other polygonal shapes may be used for the register punch holes 14 of the printing plate 9 and for the areas 12 similar to the latter. It is irrelevant in this connection whetherthe similar areas 12 are sunk directly into the plate cylinder or into register bolts or whether, instead, they are located on studs at the ends of the register bolts. It is also within the scope of the invention, instead of having two register bolts 8 at the leading edge and one at the leave, to have only one single register bolt 8 at both the leading edge and at the leave or to reverse the contrasting, i.e. to make the similar areas 12 dark and the areas surrounding them light or brightly polished.

Claims

1. Register system for the in-register aligning of a flexible printing plate (9) on the plate cylinder (2) of a rotary printing press with at least two register punch holes (14) provided in the printing plate (9) and corresponding register marks (12, 17, 23) in the plate cylinder (2), wherein the register marks have the form of areas (12, 17, 23) similar to and smaller than the register punch holes (14), lying at most on a level with the surface of the printing plate and contrasting with their surroundings.

2. Register system according to Claim 1, wherein contrasting shadow joints (16) are provided between the register punch holes (14) and the similar areas (12,17,23).

3. Register system according to Claim 2, wherein the shadow joints (16) are blackened and the areas (12, 17,23) similar to the register punch holes (14) are brightly polished similarly to the printing plate (9).

4. Register system according to Claim 2 and 3, wherein the shadow joints (16) have a uniform width of a few tenths of a millimetre.

5. Register system according to Claims 1 to 4, wherein the register punch holes (14) and the areas (12, 17, 23) similar to the latter are circular in shape.

6. Register system accordingtoClaims 1 to4, wherein the register punch holes (14) and the areas (12) similar to the latter are polygonal in shape.

7. Register system according to Claims 1 to 6, wherein the faces (12) of register bolts (8) mounted in the plate cylinder (2) with the faces (12) pointing towards the printing plate (9) are provided as the similar areas.

8. Register system according to Claim 7, wherein the register bolts (8) are mounted on adjustable intermediate members (6).

9. Register system according to Claims 1 to 5,7 and 8, wherein mounted on the register bolts (8) flush with the faces (12) of the latter are plug-in sleeves (10), the ends of which are provided with circular recesses (11) enclosing the register bolts (8), whereby the regions between the register punch holes (14) and the register bolts (8) which can be viewed from above the printing plate (9) are provided as shadow joints (16).

10. Register system according to Claims 1 to 5,7 and 8, wherein the ends of the register bolts (8) are equipped with studs (21) of slightly smaller diameter than the circular register punch holes (14), whereby the regions of the stepped annular surfaces of the register bolts (8) lying between the register punch holes (14) and the studs (21) when seen from above the printing plate (9) are provided as shadow joints (16).

11. Register system according to Claims 1 to 5,7 and 8, wherein the faces of the register bolts (8) are provided with ring grooves (22) enclosing the similar face areas (12), the inside diameter of the ring grooves (22) being slightly smaller than that of the circular register punch holes (14), whereby shadow joints (16) are provided between the register punch holes (14) and the inside diameter of the ring grooves (22).

12. Register system according to Claims 1 to 5,7 and 8, wherein the faces of the register bolts (8) are provided with blind holes (23) forming the similar areas, the diameter of the blind holes being slightly smaller than that of the circular register punch holes (14), the blind holes (23) being dark in colour as compared with their surroundings.

13. Register system according to Claims 1 to 5, wherein the ring grooves (22) are directly sunk into the plate cylinder (2) without the interposition of register bolts (8), whereby the regions lying between the register punch holes (14) and the inside diameter of the ring grooves (22) which can be viewed from above the printing plate (9) are provided as shadow joints (16), the circular areas (17) ofthe plate cylinder (2) enclosed by the ring grooves (22) being provided as similar areas.

14. Register system according to Claims 1 to 5 and 6 to 8, wherein the ends of the register bolts (8) are equipped with triangular studs (25) whose faces (12) have the form of areas similar to and slightly smaller than triangular register punch holes (14), whereby the regions lying between the register punch holes (14) and thetriangularstuds (25) which can be viewed from above the printing plate (9) are provided as shadow joints (16).

15. A registersystem for in-register alignment of a flexible printing plate, substantially as hereinbefore described with reference to the accompanying drawings.

16. Rotary printing press having a register system for aligning a flexible printing plate on the plate cylinder of the press, substantially as hereinbefore described with reference to the accompanying drawings.