GB2233281A

GB2233281A - Inking mechanism for a rotary printing machine

Info

Publication number: GB2233281A
Application number: GB9012972A
Authority: GB
Inventors: Harald Rudolph
Original assignee: Kombinat Polygraph Werner Lamberz VEB; Polygraph Leipzig Kombinat Veb
Current assignee: Kombinat Polygraph Werner Lamberz VEB; Polygraph Leipzig Kombinat Veb
Priority date: 1989-06-22
Filing date: 1990-06-11
Publication date: 1991-01-09
Anticipated expiration: 2010-06-11
Also published as: FR2648750A1; DE4017307A1; FR2648750B1; GB2233281B; DE4017307C2; DD285051A5; GB9012972D0

Abstract

An inking mechanism for a rotary printing machine comprises an ink duct roller (6) which is arranged at an ink duct (5) and drivable continuously at relatively low peripheral speed, and a pivotable vibrator roller (7) with a resilient coating and arranged between the ink duct roller (6) and an ink transfer roller (8) driven at the relatively high peripheral speed of a printing plate cylinder (2) of the machine and conducting ink to the downstream inking mechanism rollers. A frictionally drivable ink takeover roller (9) with resilient coating (10) is arranged between the vibrator roller (7) and the ink transfer roller (8) so that the vibrator roller (7) is movable alternately against the ink duct roller (6) and the takeover roller (9). The vibrator, takeover and transfer rollers (7, 8, 9) are so arranged relative to each other that when the vibrator roller (7) is lying against the takeover roller (9) the straight line connecting the axes of the takeover and vibrator rollers (9, 7) and the straight line connecting the axes of the takeover and transfer rollers (9, 8) include an angle much greater than 0 DEG and much smaller than 180 DEG . <IMAGE>

Description

G Inking mechanism for a rotary printing machine The present invention

relates to an inking mechanism for a rotary printing machine.

Ink fees systems in printing machines have the task of withdrawing the printing ink from a supply container, the ink duct, and to feed it in appropriately metered quantity to the printing plate.

The principle of the discontinuous ink transfer by means of a vibrator rolleris used in modern printing machines, in particular in offset printing machines, because of the high accuracy of the ink transfer. The vibrator roller executes an oscillating movement and contacts an ink duct rol]er and i nk transfer rol]er in alternation, wherein a narrow ink stripe of certain thickness and width and a length corresponding to the machine-printing width is transferred over the entire width of the vibrator roller. The quantity of ink fed in one vibrator roller oscillation to the downstream inking mechanism roller corresponds to the volume of the ink stripe transferred by the vibrator roller.

The rotationally movable vibrator roller experiences alternately a retardation shock on contact with the ink duct roller and an acceleration shock on contact with the ink transfer roller. In the case of, in particular, a high speed printing machine and because the number of the vibrator roller oscillations per unit of time increases in the same ratio as the printing cylinder rotational speed per unit of time, a reaction of the acceleration shock occurs in the inking and printing mechanisms. This reaction may have the form of excitation of oscillations, which lead to a reduction i'n quality of the printed product.

C.11 Known solutions of the problem include provision, in the drive transmission between the printing cylinders and the inking mechanism rollers, of resilient members, for example as described in US-PS 3 002 451. The damping of the acceleration shock thereby achieved is not satisfactory. Alternatively, the peripheral speed of the vibrator roller may be matched by special drive means, before contact with the ink transfer roller, to the peripheral speed of the transfer roller (cf for example, DE-OS 2 031 504 and US-PS 3 688 696). Considerable complications and a certain susceptibility to faults are disadvantage- ous.

Also known is a vibratory inking mechanism (DD-PS 132 253) in which a driving gear wheel of the ink transfer roller is directly connected by a special gear wheel sprocket chain with the main drive shaft and the driving wheels of the remaining inking mechanism rollers as well as of the rubber blanket and printing plate cylinders belong to the gear wheel sprocket chain. In addition, a roller with resilient coating and driven only by friction is arranged between the ink transfer roller and the downstream inking mechanism rollers. Although a considerable degree of decoupling is achieved by this solution, the complication is substantial.

It would thus be desirable to avoid the mentioned disadvantages while keeping undesired oscillations away from the printing cylinders and thus contributing to fulfilment of the requirements for print quality. Such an objective should preferably be achieved by an inking mechanism in which ink transfer roller and driven inking mechanism rollers downstream thereof are driven by a single wheel train without branches and in which a reaction of the retardation and acceleration of the vibrator roller occurring alternately within each oscillation cl - 3 cycle on the inking and printing mechanisms is eliminated by simple means.

According to the present invention-there is provided an inking mechanism for a rotary printing machine, the mechanism comprising a plurality of inking rollers for feeding ink to a printing plate cylinder, an ink transfer roller arranged to transfer ink to the inking rollers and drivable at substantially the same peripheral speed as such printing plate cylinder, a frictionally driven ink takeover roller having a resilient circumferential surface and arranged to co-operate with the transfer roller, an ink duct roller arranged at an ink duct and continuously drivable at a peripheral speed lower than that of the transfer roller, and a vibrator roller having a resilient circumferential surface and pivotable into contact with the ink duct roller and the takeover roller in alternation, the vibrator roller, takeover roller and transfer roller being so arranged relative to each other that when the vibrator roller isin contact with the takeover roller the straight line connecting the axes of thetakeover and vibrator rollers and the straight line connecting the axes of the takeover and transfer rollers include an angle substantially greater than 00 and substantially smaller than 1800.

In a preferred embodiment theink takeover roller, which is drivable only by friction by the ink transfer roller, has a"resilient coating and is arranged between the vibrator roller and the transfer roller so that the vibrator roller is layable in alternation against the ink duct rol]er and against the takeover rol 1 er. The vibrator roller, the takeover roller and the transfer roller are so arranged relative to each other in respect of their geometric position that cl - 4 the straight line connecting the central axis of the takeover roller and the central axis of the vibrator roller and the straight line connecting the central axis of the takeover roller and the central axis of the transfer roller include an angle which is very much greater than 0' and very much smaller than 180'. For preference, the hardness of the material for the resilient coating of the takeover roller is equal to or smaller than the hardness of a resilient coating of the vibrator roller.

Preferably, means are provided for separate and mutually independent adjustment and re-adjustment of the force of application of the takeover roller against the vibrator roller and against the transfer roller. In one form of such means for adjustment and readjustment of the force of application of the takeover roller, axle means of the takeover roller are mounted in eccentric bushes arranged to be rotatable in lever means, the inclination of the lever means relative to the vibrator roller being adjustable by threaded adjusting means.

The vibrator roller can thus contact duct roller and takeover roller in alternation during each vibrator roller cycle period, while a narrow ink stripe of defined thickness, length and width is initially transferred from the ink duct roller to the vibrator roller and subsequently to the takeover roller. The takeover roller is driven through friction from the transfer roller rotating at the relatively high peripheral speed of the printing plate cylinder.

When the vibrator roller, which rotates at the relatively low peripheral speed of the ink duct roller, moved against the takeover roller, the vibrator roller experiences an acceleration shock. The resilience of theforce-coupled friction bodies of vibrator roller, r_."

- 5 takeover roller and transfer roller ensures that the transmission factor for the transmission of shock is small in direction towards a gear wheel sprocket chain, by means of which the printing plate and rubber blanket cylinders, the inking mechanism rollers as well as the ink transfer roller may be driven via respective driving gear wheels.

Due to the specified arrangement of the vibrator roller, the takeover roller and the transfer roller when the vibrator roller is lying against the takeover roller, the line of action of the force transmission from the vibrator roller to the takeover roller and the line of action of the force transmission from the takeover roller to the transfer roller preferably include nearly a right angle. The transmission factor for shocks in direction of the driving wheel chain is thus additionally reduced and a disturbing reaction to the acceleration shock of the vibrator roller, in particular a reaction in the inking and printing mechanisms, may be able to be eleiminated.

An adjustability o f the force of application of the takeover roller to the transfer roller may be achieved by the rotatability of the eccentric bushes in which axle spigots of the takeover roller are mounted. The adjustability of the force of application of the takeover roller to the vibrator roller results from the adjustability of the inclination of the levers, in which the eccentric bushes are arranged. These means offer the particular advantage of the simple compensation for influences due to wear.

An embodiment of the present invention will now be more part- icularly described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic elevation of an inking mechanism embodying the invention, in particular for. a first and perfecting C form printing mechanism of a rotary roller printing machine for offset printing; and Fig. 2 is a detail view, to an enlarged scale, of a vibrator roller, ink takeover roller and ink transfer roller in the mechanism of Fig. 1.

Referring now to the drawings, there is shown an inking mechanism in a printing machine comprising a printing plate cylinder 2 and rubber blanket cylinder 3 which are arranged above and below a web of material 4, which is to be printed on, and between side walls 1 of the printing mechanism of the machine. An inking mechanism is associated with each of the printing plate cylinders 2. The inking mechanism comprises an ink duct roller 6, which is arranged at an ink duct 5 and continuously drivable to rotate at relatively low peripheral speed, a pivotable vibrator roller 7 which has a resilient coating, an ink transfer roller 8, which is driven at the relatively high peripheral speed of the printing plate cylinder 2 and feeds ink to the downstream inking mechanism rollers, and a further ink takeover roller 9 which is drivable only through friction by the transfer roller 8 and which has a resilient coating 10. The takeover roller 9 is so arranged that the vibrator roller 7 can be laid against the ink duct roller 6 and the ink takeover roller 8 in alternation.

The vibrator roller 7, the takeover roller 9 and the transfer roller 8 are so arranged relative to each other with respect to their geometric position that the straight line G1 connecting the central axis of the takeover roller 9 and the central axis of the vibrator roller 7 and the straight line G2 connecting the central axis of the takeover roller 9 and the central axis of the transfer roller 8 include almost a right angle.

G_ - The resilient coating 10 6f the takeover roller 9 and the resilient coating of the vibrator roller 7 have the same hardness, for example a hardness of 30 Shore A. ' The roller 9 has axle spigots 11 disposed one at each end thereof and mounted in respective eccentric bushes 13 which are rotatably arranged in levers 12. The inclination of the levers 12 relative to the vibrator roller 7 is adjustable by adjusting screws 14.

A cam gear 15 serves for conversion of continuous driving movement into oscillating movement of the vibrator roller 7.

On contact of the vibrator roller 7, which is rotating at the relatively low peripheral speed of the ink duct roller 6, with the ink takeover roller 9, which is rotating at the relatively high peripheral speed of the printing plate cylinder 2, the vibrator roller 7 experiences an acceleration shock. The resilience of the force- coupled friction bodies of vibrator roller 7, takeover roller 9 and transfer roller 8 ensures that the transmission factor for the transmission of force shocks is small in direction towards a spur wheel sprocket chain, by means of which the printing plate cylinder 2, the rubber blanket cylinder 3, the inking mechanism rollers and the transfer roller 8 are driven via respective driving spur wheels.

Due to the fact that the vibrator roller 7, the takeover roller 9 and the transfer roller 8 are so arranged relative to each other in respect of their geometric position, When the vibrator roller 7 is in contact with the ink takeover roller 9, that the line of action of the force transmission from the vibrator roller 7 to the takeover roller 9 and the line of action of the force transmission from the takeover roller 9 to the transfer roller 8 include almost a right angle, the transmission factor is additionally reduced for force c1 shocks in direction of the driving wheen chain. A disturbing reaction of the acceleration shock of the vibrator roller 7 on the inking and printing mechanisms may thus be eliminated.

C

Claims

- 9 CLAIMS

1. An inking mechanism for a rotary printing machine, the mechanism comprising a plurality of inking rollers for feeding ink to a printing plate cylinder, an ink transfer roller arranged to transfer ink to the inking rollers and drivable at substantially the same peripheral speed as such printing plate cylinder, a frictionally driven ink takeover roller having a resilient circumferential surface and arranged to cooperatewiththe transfer roller, an ink duct roller arranged at an ink duct and continuously drivable at a peripheral speed lower than that of the transfer roller, and- a vibrator roller having a resilient circumferential surface and pivotable into contact with the ink duct roller and the takeover roller in alternation, the vibrator roller, takeover roller and transfer roller being so arranged relative to each other that when the vibrator roller is in contact with the takeover roller the straight line connecting the axes of the takeover and vibrator rollers and the straight line connecting the axes of the takeover and transfer rollers include an angle substantially greater than 00 and substantially smaller than 1800.

2. An inking mechanism as claimed in claim 1, wherein the resilient circumferential surfaces of the vibrator and takeover rollers are provided by resilient coatings.

3. An inking mechanism as claimedfffeither claim 1 or claim 2, wherein the hardness of the material of the resilient circumferential surface of the takeover roller is at most equal to that of the resil- ient circumferential surface of the vibrator roller.

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4. An inking mechanism as claimed in any one of the preceding claim, comprising means for setting and adjusting the force of application of the takeover roller against the vibrator roller and against the transfer roller.

5. An inking mechanism as claimed in claim 4, said means for setting and adjusting comprising eccentric bushes journalling axle means of the takeover roller, lever means journalling the bushes, and threaded adjusting means for adjusting the inclination of the lever means relative to the vibrator roller.

6. An inking mechanism substantially as hereinbefore described with reference to the accompanying drawings.

7. A rotary printing machine comprising an inking mechanism as claimed in any one of the preceding claims.

Published 1991 at The Patent Office. State House. 66171 High Holborn. LondonWC I R 4TP. Further copies mav be obtained from The Patent Office. Sales Branch. St Cray. Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd. St Miry Cray. Kent. Con. 1187