GB2060821A

GB2060821A - Roller for a rotary printing machine

Info

Publication number: GB2060821A
Application number: GB8031975A
Authority: GB
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1979-10-09
Filing date: 1980-10-03
Publication date: 1981-05-07
Also published as: DE2940879A1; DD153345A1; JPS5682253A; IT1128580B; IT8049825A0

Abstract

To transfer a moment for bending the casing (2) of a bending impression cylinder, there is provided at each end of the shaft (3) an adjustable lever (18, 19), by which the shaft (3) can be rotated. As a result, a bending-force is transferred on to the casing (2) via bearings (6, 7) mounted eccentrically on the shaft (3). Next to the adjustable levers (18, 19) are provided eccentric cases (14, 15) connected with adjustable levers (16, 17). The eccentric cases (14, 15) rest on bearings (12, 13) mounted on the shaft (3). The ends of the casing (2) are supported via bearings (10, 11) on the eccentric cases (14, 15). By rotating the adjustable levers (16, 18) or, respectively, (17, 19) in opposite directions by means of pneumatic cylinders (25, 26), or respectively, (27, 28), the bending can be influenced according to size and direction. In an alternative embodiment (Fig. 5), end bearings are displaceable by a pneumatic or hydraulic ram. <IMAGE>

Description

SPECIFICATION Device for use in bending a roller of a rotary printing machine This invention is concerned with a device for use in bending a roller of a rotary printing machine, the device consisting of a shaft and a tubular casing rotatably supported on the shaft by bearings.

In printing machines, for example gravure machines, two cylinders are pressed against each other in the printing process. It is known that the cylinders are bent by the pressing of one cylinder supported on both sides or of a roller against a second cylinder or of a roller arranged parallel to the former. This bending is greater in the middle than at the ends.

Consequently the surface pressure between the cylinders is smaller in the middle than at the ends. It is a basic requirement for achieving a good printing result that the surface pressure between the cylinders should be constant over the whole nip.

An impression cylinder for gravure machines is already known from Swiss patent specification 456 649 in which the cylinder consists of two parts, i.e. of a casing and a shaft set within this. To avoid the aforementioned problem of bending, the casing and shaft in the case of the impression cylinder known from this patent specification come into contact only over a predetermined length in the middle of the roller. Further, in the case of this known impression cylinder the casing ends of the centre part present irregular profiles. A cylinder constructed in such a way is expensive and in spite of these measures the danger of bending cannot be completely ruled out.Another device is known from German Auslegeschrift 2033515. In this case a counter moment is produced on the gravure cylinder of a printing machine which bends it, whereby the position, length and size of the bend is matched to the particular image requirements. The bending moment is produced by the effect of a load directed on the two pivot pins projecting out over the bearings. To produce this power there is in each case a piston acted upon by a fluid medium arranged over a pivot pin. Since during the printing process the bending of the cylinder must be kept upright, it is essential that the fluid medium should act permanently on both pistons over the pivot pins. Such an arrangement to effect a bending moment is expensive, space-consuming and naturally exacts high running costs.

It is already known from German Offenlegungsschrift 24 22 696, how to effect the necessary moment for the bending of cylinders by means of mechanical tensioning devices e.g. tensioning screws. Such draw-devices, however, lend themselves only to 4cylinder arrangements, since the tensioning elements used are supported on the four shafts of the cylinders.

One aim of the invention is to provide, in preferred embodiments, a device for effecting a moment to bend a printing roller, for example, the casing of an impression cylinder, which device is simple in comparison to known, in parts very complicated, devices, requires no appreciable additional space, offers the possibility of simple exchange of the most heavily gummed casing and, if necessary, offers the possibility of control of the sheet to be printed by changing the bending direction out of the vertical contact level, in order to achieve an effect of tightening in width.

More generally, according to the present invention, there is provided a device for use in bending a roller of a rotary printing machine, the device comprising a shaft, bearings mounted on the shaft, and a tubular casing mounted on the bearings for rotation relative to the shaft, at least one of the bearings being adjustable in position transversely of the shaft to transmit a bending force to the casing.

Although the use of two eccentrics on the shaft of a printing-machine cylinder is already known from German Offenlegungsschrift 27 25 030, there the arrangement of two concentrics on top of each other only permits the position of the cylinder against another cylinder positioned parallel to the former. The production of a bending moment, or, as the case may be, a correction in the bending of the cylinder is in any event not possible in the case of this known device.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made by way of example to the accompanying diagrammatic drawings, in which: Figure 1 is a sectional elevation of a printing roller provided with a bending device; Figure 2 is a schematic side view of the bending device, used on the left side of the roller (as seen in Fig. 1); Figure 3 is a modified view of a somewhat modified bending device used on the right side of the roller; Figure 4 is a further variation of a bending device usable on the roller shown in Fig. 1, Figure 5 is a sectional elevation of another example of a printing roller; and Figure 6 is a side view of the roller of Fig.

5.

In Fig. 1 a roller 1 is shown which can be used as a bending impression cylinder in a gravure machine and which consists of a casing 2 set on a shaft 3. On the shaft 3 eccentric cross-sectional strengtheners can be seen in the central zones, chiefly in the form of eccentric discs 4 and 5 by which the casing 2 is supported over bearings 6 and 7, and rings or discs 8 and 9 having corresponding eccentric bores. The mean axis of the shaft 3 can thus be displaced with respect to the bores of discs 4 and 5 and of bearings 6 and 7.

At both ends the casing 2 rests on bearings 10 and 11. Underneath the roller ends, bearings 1 2 and 1 3 are fitted onto the shaft and respective eccentric cases 1 4 and 1 5 are set on to the bearings. The aforementioned endbearings 10, 11 of the casing thus rest on the eccentric cases 14 and 1 5. The eccentric cases 1 4 and 1 5 are each fitted with a lever 1 6 and 1 7 respectively, with the help of which a pivoting round the shaft 3 is possible.

At each shaft end, connected firmly to the shaft 3, levers 1 8 and 1 9 are provided, having tubular components which, each surrounding a shaft end, support the shaft 3. The shaft bearings 20 and 21, resting on the aforementioned components, are fixed to side walls 22 and 23 in a conventional manner.

The levers 1 6 and 1 8 used on the left side of the roller 1 can be pivoted countercurrently to the shaft 3 by pneumatic cylinders (rams) 25 and 26, as shown in Fig. 2. On the right side of the roller 1, levers 1 7 and 1 9 can be swivelled in an opposite direction round the shaft by pneumatic cylinders 27 and 28, shown in Fig. 3. Both the arrangement of the pneumatic cylinders according to Fig. 2 and that according to Fig. 3 can of course be used on both sides of the roller 1.

The arrangement shown in Fig. 3 of the pneumatic cylinders 27 and 28 on a bracket 24 permit, by loosening the fastening lever 31, an arcuate displacement of the pneumatic cylinders 27, 28 in the slot 30 in the same direction around the casing 2 or respectively the shaft 3.

A further possibility of adjustment of levers 1 7 and 1 9 by means of a single pneumatic cylinder is shown in Fig. 4. Here it is possible to swivel in opposite direction levers 1 7 and 1 9 over a scissor-like member, consisting of levers 32 and 33, by a pneumatic cylinder 29. In comparison to the arrangement of the pneumatic cylinders 27 and 28 according to Figs. 2 and 3, a reduction in cost is effected with the use of the pneumatic cylinder 29 with the arrangement according to Fig. 4, since only one pneumatic cylinder is necessary on both sides of the roller 1. A further alteration in the arrangement according to Fig.

4 could be for the pneumatic cylinder 29 to be secured, similarly to the style in Fig. 3, also in an arcuate mounting, whereby it would be possible to pivot the adjustable levers 1 7 and 1 9 around the shaft 3 in the same direction and by the same amount.

According to the principle of operation under lying the illustrated embodiment, a bending moment can be transferred on to the casing 2 of the roller 1 by the adjustment in opposite directions of the levers 1 6 and 1 8 or respectively, levers 1 7 and 19, by the pneumatic cylinders 25, 26, 27 and 28 connected with them. By pivoting the levers 1 6 and 1 7 around the shaft 3, a force which bends the casing is exerted on the end zones of the casing 2 through the eccentric cases 1 4 and 15.By swivelling the adjustable levers 18 and 1 9 in opposite directions the shaft 3 can be twisted, whereby a force in opposition is set up on the inner areas of the casing over the middle, eccentric bearings 6 and 7 connected to the shaft 3. Thus, with the illustrated embodiment, an individual bending of the roller can easily be brought about independently of the control of the pneumatic cylinder, whereby both the degree of bending and the course of the bending line can be controlled. With the device according to Fig. 3, the direction, i.e. the plane of the resulting bending moment can be advantageously adjusted in addition.

By adjusting the arrangement in the slot 30 a bending component for the slight tightening in width of a sheet can be put to use in order to counteract the shrinkage action of the sheet. The same thing can be achieved according to Fig. 2 with assymetrical piston positioning. This arrangement for tightening in width is, if necessary, controllable with a measuring and regulating member.

In Figs. 5 and 6 a second embodiment of the invention is shown. A roller 35, consisting of a casing 36 and a fixed shaft 37, is positioned over sliding carriers 42 and 43 between side-walls 44 and 45. The casing 36 rests over inner bearings 38 and 39 and over outer bearings 40 and 41 on the shaft 37. In the example of operation described here the outer bearings 40 and 41 are acted upon by pneumatically or hydraulically controllable pistons touching their inner rings with a force which produces a bending of the roller casing.

In order to be able to adjust the centre of the outer bearings 40 and 41, in relation to the mean axis of the shaft 37, an equivalent clearance, shown in Fig. 6 at 34, is provided between shaft 37 and the inner rings of the outer bearings 40 and 41.

By an equivalent control of pistons 46 and 47 the course of the bending line for the casing 36 can easily be controlled.

Claims

1. A device for use in bending a roller of a rotary printing machine, the device comprising a shaft, bearings mounted on the shaft, and a tubular casing mounted on the bearings for rotation relative to the shaft, at least one of the bearings being adjustable in position transversely of the shaft to transmit a bending force to the casing.

2. A device according to claim 1, wherein at least one axial end of the casing is mounted on a respective bearing which in turn is mounted on an eccentric casing which is eccentrically pivotable with respect to the shaft, and which is in turn mounted on another bearing which is in turn mounted on the shaft.

3. A device according to claim 1 or 2, wherein at least one eccentric is provided on a central portion of the shaft, a corresponding concentric annulus is provided on the inner surface of the casing, and said annulus is mounted on a respective bearing which in turn is mounted on said eccentric.

4. A device according to claim 3, wherein means is provided for rotating at least one axial end of the shaft.

5. A device according to claim 4, wherein said means comprises a lever having a hollow portion mounted on the shaft, and journalled in a bearing provided in a frame of the device or of an associated printing machine.

6. A device according to claim 2 or to any one of claims 3 to 5 as appendant thereto, wherein the or each eccentric case is provided with a lever for pivoting the case about the shaft.

7. A device according to claim 2 or to any one of claims 3 to 6 as appendant thereto, wherein a respective eccentric case is provided at each axial end of the casing, and means is provided for pivoting the eccentric cases about the shaft in opposite directions.

8. A device according to claim 2 or to any one of claims 3 to 7 as appendant thereto, comprising at least one pneumatic or hydraulic ram for pivoting the eccentric case(s) about the shaft.

9. A device according to claim 4 or to any one of claims 5 to 8 as appendant thereto, including means for rotating both axial ends of the shaft in opposite directions.

10. A device according to claim 4 or to any one of claims 5 to 9 as appendant thereto, including at least one pneumatic or hydraulic ram for rotating the axial end(s) of the shaft.

11. A device according to claims 2 and 4 or to any one of claims 5 to 10 as appendant thereto, wherein means is provided for rotating the or at least one of the eccentric case(s) together with the respective axial end of the shaft together in the same direction.

1 2. A device according to claim 11 as appendant to claims 8 and 10, wherein one end of the or each pneumatic or hydraulic ram for rotating an axial end of the shaft and a respective said eccentric case is or are mounted at a point which is displaceable along an arcuate path, for rotating the eccentric case with the respective axial end of the shaft together in the same direction.

1 3. A device according to claim 11 or 12, including means for measuring tightening in width of a sheet when fed through an associated printing machine in use, and for controlling such tightening by rotating the or at least one of the eccentric case(s) with the respective axial end of the shaft together in the same direction.

14. A device according to claims 8 and 10, or to claim 11, 1 2 or 1 3 as appendant thereto, wherein a single pneumatic or hydraulic ram and scissors-like linkage is provided for rotating the or one of the eccentric case(s) together with the respective end of the shaft in opposite directions.

1 5. A device according to claim 1, wherein each axial end of the casing is mounted on a respective bearing which is in turn mounted on the shaft, and means is provided for displacing said bearing relative to the shaft.

1 6. A device according to claim 15, wherein said means comprises a respective pneumatic or hydraulic ram arranged to operate on an inner race of the said bearing at each axial end of the casing, which bearing is mounted with play on the shaft.

1 7. A device for use in bending a roller of a rotary printing machine, the device being substantially as hereinbefore described with reference to Figs. 1 and 2, and/or Figs. 1 and 3, and/or Figs. 1 and 4, of the accompanying drawings.

1 8. A device for use in bending a roller of a rotary printing machine, the device being substantially as hereinbefore described with reference to Figs. 5 and 6 of the accompanying drawings.

1 9. A printing machine provided with a device according to any preceding claim.