GB2278574A

GB2278574A - Ink transfer means for printing machine

Info

Publication number: GB2278574A
Application number: GB9311230A
Authority: GB
Inventors: David Edward Mcmanamon
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-06-01
Filing date: 1993-06-01
Publication date: 1994-12-07
Also published as: GB9311230D0

Abstract

Ink transfer means for a printing machine includes an application roller (12) to receive ink from an ink rail (11) and transfer the same to print rollers for printing. A pair of wiper rollers (13) are provided above and below the centre of the application roller (12) and in close proximity to the surface thereof. The wiper rollers (13) are driven in opposite directions such that they effectively wipe the surface of the application roller (12) to prevent build up of ink and the associated ink misting, irrespective of the direction of rotation of the application roller. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO INR TRANSFER MEANS FOR A PRINTING MACHINE This invention relates to ink transfer means for a printing machine and more particularly to such means for transferring ink from an ink source onto an application roller and subsequently onto one or more print rollers.

A common problem with printing machines is that the application of ink from an ink rail to an application roller, for subsequent transfer to the print rollers of the machine, is such that an uneven layer of ink is applied to the application roller and in areas where there are thick layers of ink there is a tendency for globules or droplets of ink to form on the surface of the roller and ink rail. As the roller rotates these are released from the surface of the roller or rail as droplets and even mists of fine droplets of ink which results in undesirable ink wastage. Furthermore, since the ink layer is uneven, this results in non-uniform application of ink to the print rollers which gives rise to uneven and less than satisfactory printing results.

It is an object of the present invention to provide an ink transfer means which overcomes or at least minimises the abovementioned problems.

According to the present invention therefore there is provided ink transfer means for a printing machine comprising application roller means to receive ink from an ink source onto an outer peripheral surface thereof and to transfer the ink from said surface to print rollers for printing wherein at least one wiper roller means is provided in close proximity to said surface of said application roller means, said wiper roller being rotated at reduced speed relative to said application roller means thereby to wipe the surface to cause a uniform layer of ink to be formed thereon.

With this arrangement it is possible to apply ink uniformly to the surface of the application rollers and minimise the development of droplets which can be released from the roller on rotation thereby suppressing ink dripping and misting.

Preferably a pair of wiper roller means are provided, an upper wiper roller above the centre of the application roller and a lower wiper roller below the centre. The wiper roller means are rotated in opposite directions such that the surface of the application roller can be wiped regardless of the direction of rotation of the roller.

Preferably each wiper roller means is located in close proximity to both said ink source and said surface of said application roller means.

Preferably an outer periphery surface of said wiper rollers are spaced from the outer peripheral surface of said application roller by a distance in the range of O.003"-O.008" (O.076mm-0.203mm). Most preferably the spacing is 0.005" (0.127mm).

Preferably the outer peripheral surface of the wiper rollers are spaced from the ink source by a distance in the region of 1-5mm and most preferably 2mm.

Preferably the relative speed of rotation of the application and wiper rollers is such that the speed of the wiper rollers is in the range 5-30% of the application roller speed.

Most preferably the wiper roller speed is 12% of the application roller speed.

Preferably the ink source is an ink rail of the kind described in my co-pending Application No. 9215076.2.

However, the ink source can take any form as desired or as appropriate.

The invention will now be described further by way of example only and with reference to the accompanying drawing, the single figure of which shows a diagrammatic side view of the form of ink transfer means according to the present invention.

Referring now to the drawing, there is shown an ink transfer means which comprises an ink rail 11 for supplying ink to an application roller 12 and a pair of wiper rollers 13 mounted in close proximity to the ink rail 11 and application roller 12 to wipe the outer peripheral surface 14 thereof.

The application roller 12 is a smooth surfaced ground metallic roller which is driven by any suitable drive means (not shown) at the print speed, i.e. the speed of rotation of the print rollers of the printing machine.

The wiper rollers 13 are smooth surfaced steel rollers which are also driven by any suitable drive means (not shown). The drive means for the application and wiper rollers 12 and 13 can be independent of each other or combined in a single drive means.

The ink rail 11 comprises an elongate member which has multiple ink outlet ports (not shown) through which ink is fed under pressure from a source thereof to the surface 14 of the application roller 12.

The wiper rollers 13 are mounted one above and one below a centre 16 of the application roller 14 and are mounted such that the outer peripheral surfaces 17, 18 of the wiper rollers 13 are disposed in close proximity to the outer peripheral surface 14 of the application roller 12. Preferably the respective outer peripheral surfaces of the application and wiper rollers are separated by a distance of 0.005" (0.127mm) although it is thought that larger and and smaller distances than this could be used and the same results achieved.

In use, ink is supplied to the outer surface 14 of an application roller 12 via ink outlets (not shown) in the ink rail 11. With the application roller 14 being driven at print speed (up to 1000 rpm), for example in the direction of arrow A, the ink received on the surface 14 of the roller 12 has a tendency to form globules or droplets of ink if a large accumulation of ink develops due to non-uniform application. Of course it will be apparent that, in these circumstances, if the globules or droplets drop from the roller wastage of ink occurs and if, furthermore, the non-uniformly distributed ink is allowed to remain in that state on the roller, the results of the eventual printing will be deteriorated perhaps to an unacceptable level.

In the present arrangement, one of the wiper rollers 13 (when the application roller 14 is rotating in the direction of arrow A, the upper wiper roller) is driven such that it rotates in the same sense as the application roller 12. Due to the close proximity of the outer surfaces 17 and 14 of the wiper roller 13 to that of the application roller 12 and the positioning thereof relative to the roller, it is clear that the tangential direction of movement of the wiper and application rollers 13 and 12 are in opposite senses. Thus it is clear that the wiper roller 13 will effectively wipe the surface 14 of the application roller 12 in the region of proximity and will allow only a build-up of a layer of ink on the surface of the roller up to a maximum of the distance between the outer surfaces 17 and 14 respectively of the wiper and application roller 13 and 12, for example, 0.0047" (0.12mum). Thus it is clear that since the wiper roller 13 wipes the surface 14 of the application roller 12, a uniform layer of ink of predetermined thickness (determined by the distance between the wiper roller and application roller surfaces 17 or 18, 14) can be applied to the application roller 12. This uniform layer can then be transferred to the print rollers (not shown) for much improved printing results. Furthermore, in practice, the wiper rollers 13 will be mounted in close proximity to the ink outlets of the ink rail 11 and therefore the formation of droplets or globules of ink which can be released from the surface of the roller 12 are removed before there is an opportunity for them to be released from the roller surface 14.

It will be appreciated that when the application roller 12 is driven in direction A, the lower wiper roller 13 is driven to wipe the surface 14 and when the roller 12 is driven in direction B, the upper wiper roller 13 is driven to wipe the surface 14.

In order to increase the wiping action, the wiper rollers 14 are driven at a reduced speed to the application roller and the speeds of rotation thereof is usually in the range 5-10% of application roller speed.

It can be seen that with this arrangement it is not necessary to reduce the speed of the application roller 12 to achieve uniform printing results and accordingly the application roller can operate at print speed and therefore no delay or timing problems are introduced into the machine. Alternatively the wiper rollers 14 can be driven at a predetermined speed which is less than the speed of the application roller, e.g. 25-500 rpm.

With this arrangement it is possible to provide a means for transferring ink onto an application roller of a printing machine which reduces or eradicates the problems associated with non-uniform ink application and dripping or misting leading to ink wastage and unsatisfactory printing results.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only.

Claims

1. Ink transfer means for a printing machine comprising application roller means to receive ink from an ink source onto an outer peripheral surface thereof and to transfer the ink from said surface to print rollers for printing wherein at least one wiper roller means is provided in close proximity to said surface of said application roller means, said wiper roller being rotated at reduced speed relative to said application roller means thereby to wipe the surface to cause a uniform layer of ink to be formed thereon.

2. Ink transfer means for a printing machine according to claim 1 comprising a pair of wiper roller means are provided, an upper wiper roller above the centre of the application roller and a lower wiper roller below the centre.

3. Ink transfer means for a printing machine according to claim 1 or claim 2 wherein the wiper roller means are rotated in opposite directions such that the surface of the application roller can be wiped regardless of the direction of rotation of the roller.

4. Ink transfer means for a printing machine according to any one of claims 1 to 3 wherein each wiper roller means is located in close proximity to both said ink source and said surface of said application roller means.

5. Ink transfer means for a printing machine according to any one of claims 2 to 4 wherein an outer peripheral surface of each said wiper rollers is spaced from the outer peripheral surface of said application roller by a distance in the range of 0.003"-0.008" (0.076mm-0.203mm).

6. Ink transfer means for a printing machine according to claim 5 wherein the spacing is 0.005" (0.127mm).

7. Ink transfer means for a printing machine according to any one of claims 2 to 6 wherein the outer peripheral surface of the wiper rollers are spaced from the ink source by a distance in the region of 1-5mm.

8. Ink transfer means for a printing machine according to claim 7 wherein said spacing is 2mm.

9. Ink transfer means for a printing machine according to any one of claims 1 to 8 wherein the relative speed of rotation of the application and wiper rollers is such that the speed of the wiper rollers is in the range 5-30% of the application roller speed.

10. Ink transfer means for a printing machine according to claim 9 wherein the wiper roller speed is 12% of the application roller speed.

11. Ink transfer means for a printing machine according to any preceding claim further including an elongate ink rail, an ink or fluid chamber in said rail and extending in the longitudinal direction thereof, a multiplicity of spaced parallel feed passages in said rail having respective outlet orifices at a common surface of said rail, a corresponding multiplicity of adjustable keys, one for each feed passage, operable to control flow of ink or fluid to and through the respective feed passages, and control means operable on said keys to effect controlled adjustment thereof, the said common surface being cylindrically concave at least in that region thereof whereat said feed passages exit the rail.

12. Ink transfer means substantially as hereinbefore described with reference to the accompanying drawing.

13. A printing machine including ink transfer means according to any preceding claim.