GB2147852A

GB2147852A - Printing press dampening system

Info

Publication number: GB2147852A
Application number: GB08325712A
Authority: GB
Inventors: Louis Surbrook; Stuart John Pellatt Turner
Original assignee: VILLAGER PRESS MANUFACTURING C
Current assignee: VILLAGER PRESS MANUFACTURING C
Priority date: 1983-09-26
Filing date: 1983-09-26
Publication date: 1985-05-22
Also published as: GB2147852B; GB8325712D0

Abstract

A printing press dampening system comprising a pan roller (14) partially immersed in a water tray (12). A brush roller (52) is arranged with its bristles in contact with the wetted surface of the pan roller (14). The brush roller (52) is arranged to be driven at a greater speed than the pan roller (14) to create a mist spray. A chrome oscillator roller (16) lies spaced from the brush roller (52) and pan roller (14) so that during press operation the mist spray is directed into the space between the brush and oscillator rollers (14 and 16) thereby to dampen the outer peripheral surface of the oscillator roller (16). A conventional roller damping system may be converted to one according to the invention by replacing a roller by brush 52 and applying semi-cylindrical shells 50 to original fountain roller 14. <IMAGE>

Description

SPECIFICATION Printing press dampening system The present invention relates to a printing press dampening system and in particular to a dampening system which can be readily fitted to an existing printing press of the offset lithographic type.

According to one aspect of the present invention, there is provided a printing press dampening system comprising a pan roller which in use has a peripheral surface wetted by water in a water tray, a brush roller arranged with its bristles in contact with the wetted surface of the pan roller, and transmission means operable when driven to rotate the brush roller at a greater speed than the pan roller to create a mist spray, the system being such that when assembled into a printing press the outer peripheral surface of the brush roller is spaced from an outer peripheral surface of a chrome oscillator roller of the printing press, and such that during press operation the mist spray is directed into the space between the bush and oscillator roller thereby to dampen the outer peripheral surface of the oscillator roller.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side view of a typical offset lighographic press, and Figure 2 is an enlarged diagrammatic side view of a retrofit dampening system according to the present invention.

Referring to the drawings, a typical offset lighographic printing press 10 includes a water dampening system comprising a water tray 12, a pan roller 14 wetted by water in the tray, a sock roller 15 in surface contact with the pan roller, a chrome oscillator roller 16 in surface contact with the sock roller, a transfer roller 18 in surface contact with the roller 16, a plate cylinder 20 in surface contact with the roller 18 and a blanket cylinder 22 in surface contact with the plate cylinder 20. For printing on both sides of a paper web W, a second dampening system is provided in mirror image" relationship with the first, the paper web passing between and contacted by the two blanket cylinders 22. The printing press also includes two inking systems (not shown) which by means of a series of rollers transfer a layer of ink to each of the plate cylinders 20.

Disadvantages of the above type of printing press are: 1) Improper sock roller adjustments cause waste and poor print quality.

2) Worn sock roller covers cause waste and poor print quality until cover can be changed.

3) Clogged drains and tray overspills are caused by ink and lint feedback into the dampener system causing poor print quality and requiring manpower for cleaning.

4) After half width webs, the sock roller delivers solution unevenly across the plate cylinder causing waste and/or poor print quality. The same is true with web width changes.

The now to-be described retrofit dampening system aims to substantially reduce the above mentioned disadvantages.

Referring to Figure 2, the existing pan roller of the printing press is modified by two half cylindrical metal shells 50 which are clamped to the pan roller to enlarge its diameter. The existing sock roller is replaced by a brush roller 52 with bristles in contact with an outer peripheral surface of the enlarged pan roller. Transmission means including spur gear wheels (not shown) located at the shaft end of the brush and pan rollers are driven in use to rotate the brush roller at a much greater speed (say 600 rpm) than that of the pan roller (say 50 rpm). The brush roller would be driven at constant speed by a take-off from the press drive, and the pan roller would be driven by a variable speed electric motor which may form part of the press or provided in addition thereto.

Conveniently the brush is of spiral form and is located in shallow spirals cut in the outer peripheral surface of the brush roller; securing screws (not shown) would secure the brush to the brush roller.

When assembled in the printing press, the outer periphery of the brush roller is spaced by a gap 'G' from the outer periphery of the chrome oscillator roller. In use, the water from the wetted peripheral surface of the pan roller is directed by the brush bristles into the gap G thereby to dampen the oscillator roller, the "flicking" action of the bristles causing the water to break down into minute water droplets or mist which is propelled across gap G to effectively and evenly dampen the entire peripheral surface of the oscillator roller. The brush roller is mounted on eccentric bearings (not shown) which enable the distance between the brush and pan rollers to be varied and hence the "flick" action of the bristles to be adjusted.

Advantages of the above described retrofit system are: 1) It reduces paper waste, press down time and other unwanted wasteful by-products associated with sock rollers.

2) It cuts down on dampener system maintenance by as much as 90% and therefore frees the press and crew for production.

3) It improves print quality usually compromised by sock roller problems.

4) It requires no predampening before printing.

5) The dampener action is stopped automatically as soon as the press is stopped, and is commenced as soon as the press is started.

1. A liquid transfer system comprising a first roller, means for supplying the outer surface of said first roller with a liquid, a second roller having a rotary axis extending parallel to that of the first roller, the outer surface of the second roller being spaced from the outer surface of the first roller, and a brush roller provided with radially extending flexible bristles, the brush roller being so positioned relative to said first and second rollers that

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Printing press dampening system The present invention relates to a printing press dampening system and in particular to a dampening system which can be readily fitted to an existing printing press of the offset lithographic type. According to one aspect of the present invention, there is provided a printing press dampening system comprising a pan roller which in use has a peripheral surface wetted by water in a water tray, a brush roller arranged with its bristles in contact with the wetted surface of the pan roller, and transmission means operable when driven to rotate the brush roller at a greater speed than the pan roller to create a mist spray, the system being such that when assembled into a printing press the outer peripheral surface of the brush roller is spaced from an outer peripheral surface of a chrome oscillator roller of the printing press, and such that during press operation the mist spray is directed into the space between the bush and oscillator roller thereby to dampen the outer peripheral surface of the oscillator roller. An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side view of a typical offset lighographic press, and Figure 2 is an enlarged diagrammatic side view of a retrofit dampening system according to the present invention. Referring to the drawings, a typical offset lighographic printing press 10 includes a water dampening system comprising a water tray 12, a pan roller 14 wetted by water in the tray, a sock roller 15 in surface contact with the pan roller, a chrome oscillator roller 16 in surface contact with the sock roller, a transfer roller 18 in surface contact with the roller 16, a plate cylinder 20 in surface contact with the roller 18 and a blanket cylinder 22 in surface contact with the plate cylinder 20. For printing on both sides of a paper web W, a second dampening system is provided in mirror image" relationship with the first, the paper web passing between and contacted by the two blanket cylinders 22. The printing press also includes two inking systems (not shown) which by means of a series of rollers transfer a layer of ink to each of the plate cylinders 20. Disadvantages of the above type of printing press are: 1) Improper sock roller adjustments cause waste and poor print quality. 2) Worn sock roller covers cause waste and poor print quality until cover can be changed. 3) Clogged drains and tray overspills are caused by ink and lint feedback into the dampener system causing poor print quality and requiring manpower for cleaning. 4) After half width webs, the sock roller delivers solution unevenly across the plate cylinder causing waste and/or poor print quality. The same is true with web width changes. The now to-be described retrofit dampening system aims to substantially reduce the above mentioned disadvantages. Referring to Figure 2, the existing pan roller of the printing press is modified by two half cylindrical metal shells 50 which are clamped to the pan roller to enlarge its diameter. The existing sock roller is replaced by a brush roller 52 with bristles in contact with an outer peripheral surface of the enlarged pan roller. Transmission means including spur gear wheels (not shown) located at the shaft end of the brush and pan rollers are driven in use to rotate the brush roller at a much greater speed (say 600 rpm) than that of the pan roller (say 50 rpm). The brush roller would be driven at constant speed by a take-off from the press drive, and the pan roller would be driven by a variable speed electric motor which may form part of the press or provided in addition thereto. Conveniently the brush is of spiral form and is located in shallow spirals cut in the outer peripheral surface of the brush roller; securing screws (not shown) would secure the brush to the brush roller. When assembled in the printing press, the outer periphery of the brush roller is spaced by a gap 'G' from the outer periphery of the chrome oscillator roller. In use, the water from the wetted peripheral surface of the pan roller is directed by the brush bristles into the gap G thereby to dampen the oscillator roller, the "flicking" action of the bristles causing the water to break down into minute water droplets or mist which is propelled across gap G to effectively and evenly dampen the entire peripheral surface of the oscillator roller. The brush roller is mounted on eccentric bearings (not shown) which enable the distance between the brush and pan rollers to be varied and hence the "flick" action of the bristles to be adjusted. Advantages of the above described retrofit system are: 1) It reduces paper waste, press down time and other unwanted wasteful by-products associated with sock rollers. 2) It cuts down on dampener system maintenance by as much as 90% and therefore frees the press and crew for production. 3) It improves print quality usually compromised by sock roller problems. 4) It requires no predampening before printing. 5) The dampener action is stopped automatically as soon as the press is stopped, and is commenced as soon as the press is started. CLAIMS

1. A liquid transfer system comprising a first roller, means for supplying the outer surface of said first roller with a liquid, a second roller having a rotary axis extending parallel to that of the first roller, the outer surface of the second roller being spaced from the outer surface of the first roller, and a brush roller provided with radially extending flexible bristles, the brush roller being so positioned relative to said first and second rollers that the bristles of the brush roller are urged against the first roller and when the brush roller is rotated the bristles transform the liquid on the outer surface of the first roller into a mist which is directed by the bristles towards the outer surface of the second roller.

2. A system according to Claim 1 including drive means for driving the brush roller at a higher speed than that of the first roller.

3. A system according to Claim 1 or to Claim 2 including a liquid container for containing said liquid and arranged so that the first roller is partially immersed in the liquid therein.

4. A system according to any one of Claims 1 to 3, wherein the first roller comprises a central core supporting two outer part-circular shells.

5. A printing press dampening system comprising a pan roller which in use has a peripheral surface wetted by water in a water tray, a brush roller arranged with its bristles in contact with the wetted surface of the pan roller, and transmission means operable when driven to rotate the brush roller at a greater speed than the pan roller to create a mist spray, the system being such that when assembled into a printing press the outer peripheral surface of the brush roller is spaced from an outer peripheral surface of a chrome oscillator roller of the printing press, and such that during press operation the mist spray is directed into the space between the brush and oscillator roller thereby to dampen the outer peripheral surface of the oscillator roller.

6. A printing press dampening system conversion kit for converting a dampening system which comprises a first roller arranged for partial immersion in a tray of liquid, a second roller in contact with the first roller, a third roller in contact with the second roller, and a drive system for driving the rollers to effect the transfer of liquid from the tray to the third roller through the first and second rollers, the kit comprising a cylindrical shell for clamping to the first roller to increase the diameter of the first roller, a brush roller having a plurality of radially extending bristles for replacing said second roller such that the bristles thereof engage the first roller and lie spaced from the third roller and a drive assembly for modifying the drive means to ensure that the brush roller is driven at a higher speed than the first roller whereby when the drive means is actuated the brush roller converts the liquid on the outer surface of the first roller into a mist and directs it at the third roller.

7. A system according to any preceding claim, wherein the bristles on the brush roller are spirally arranged about the outer surface of the brush roller.

8. A printing press dampening system substantially as hereinbefore described, with reference to the accompanying drawings.

9. A printing press including a dampening system, according to any preceding claim.