AU633452B2

AU633452B2 - Ink roller for rotary press

Info

Publication number: AU633452B2
Application number: AU85555/91A
Authority: AU
Inventors: Yuji Ijichi
Original assignee: Rockwell International Corp
Current assignee: Goss International Asia Pacific Inc
Priority date: 1987-08-18
Filing date: 1991-10-03
Publication date: 1993-01-28
Anticipated expiration: 2008-07-28
Also published as: AU8555591A; JPS6430272U

Description

m '=S 633452

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT NAME OF APPLICANT: ROCKWELL INTERNATIONAL CORPORATION ACTUAL INVENTOR: YUJI IJICHI ADDRESS FOR SERVICE: GRIFFITH HACK CO., 601 ST. KILDA ROAD, MELBOURNE, VIC. 3004.

INVENTION TITLE: INK ROLLER FOR ROTARY PRESS The following statement is a full description of this invention, including the best method of performing it known to me:

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2 INK ROLLER FOR ROTARY PRESS This invention relates to ink rollers having doctor blades.

Conventionally, ink rollers used in presses have steel roller cores which have surfaces which are covered with a hard coating of, for example, copper and ceramic having an engraved surface with irregular topography. The edge of a doctor blade is brought into contact with the outer surface of the coating to adjust the amount of ink held in recesses of the engraved surface.

During use of such an ink roller, raised portions on the surface of the in]r roller are worn by the doctor blade. The result is that the volume of ink that may be held in the recesses in the surface is decreased.

Oleophilic and hydrophobic properties are also degraded, and print quality decreases. The damaged ink roller must be replaced totally. Ink rollers of this kind are very expensive to replace. The replacement of worn doctor blades further adds to the cost of maintaining the ink rollers.

The edge of the doctor blade can be polished through use so as not to degrade excessive ink wipe-away action.

According to the present invention there is provided an ink metering roller with a cylindrical core for a printing press having a wear adjusting, ink metering outer layer of selected depth for provision around said core, comprising: means providing a dispersion of potential ink cell locations throughout a substantial portion of the depth of the outer layer beneath an ink metering surface thereof; and means for successively enabling a plurality of said potential ink cell locations as they successively appear at the surface of the outer layer to become actual ink cells each capable of holding a small quantity of ink as the surface of the outer layer is worn.

2 vi Said potential ink cell dispersion may provide means including a dispersion of element defining walls between potential cells.

The cell enabling means may include means for wearing away material between the dispersion of wall defining elements at the surface of the outer layer to form the actual cells from the potential cells.

The material that is worn away may substantially fill the space between said wall defining elements prior to being worn away.

The material worn away to form the actual cells may be a different material than that of the wall defining elements.

The material of the wall defining elements may be relatively harder than the material worn away to form the cells.

The dispersion may be substantially uniform throughout the depth of the outer layer to maintain a uniform ink holding capacity as the surface of the outer layer is worn away.

The material worn away to form the cells may be material which fills the cells before the cells are formed.

According to the present invention there is provided a method of maintaining a substantial uniform ink metering capacity of an ink metering roller, comprising the steps of: providing an outer coat for said roller with a substantially uniform dispersion of potential ink carrying cells throughout a significant thickness thereof; causing potential cells beneath the surface to become new actual cells as actual cells at the surface are worn away, said new actual cells being created at substantially the same rate at which said actual cells at the surface are worn away to maintain a uniform actual cell capacity at different thicknesses of the outer coat.

The potential cells may be filled with material which is worn away when they reach the surface to form the actual cells.

The method may include the step of wearing away material at the surface of the outer coat with a doctor blade.

According to the present invention there is still further provided a device for supplying ink for a printing press comprising a roll, and a doctor associated with the roll, said roll having an outer layer defining a plurality of recesses exposed in an outer surface of the layer, and a plurality of additional recesses being exposed on the surface as the layer of the roll is worn.

The roll may comprise an inner roller, and a binder material forming the layer on an outer surface of the rollr.

In order that the invention might be more fully understood, embodiments of the invention will be described by way of example only with reference to the accompanying drawings in which: Fig. 1 is a front view illustrating a rotary press having an ink roller with doctor; Fig. 2 is an enlarged sectional view of a portion of Fig. 1 enclosed by lines II, illustrating a fragment of the embodiment of Fig. 1; and Fig. 3 is an enlarged sectional view of a portion of an ink roll illustrating a fragment of the roll.

Referring to the drawings, Fig. 1 illustrates a rotary press in which an ink roller 5 is provided. To describe this illustration, 1 designates a cylinder having its outer circumferential surface mounted with a lithographic plate 2. Ink 13 in an ink basin 3 is supplied to the lithographic plate 2. Ink 13 in an ink basin 3 is 4supplied to the lithographic plate 2 through a fountain rubber roller 4, the ink roller 5 and set of rollers 6, 7 and 8. At the same time water is supplied by a water supply means 11 to the roller 7 through water receiving roller 10, so that the ink which is being supplied to the lithographic plate is mixed with water.

The surface of the ink roller, as shown in Fig. 2, is made up of a composite material 18 which comprises a large number of highly wear-resistant hard particles 17 and a binding material 20. The binding material may be a hard polymer, The hard particles are bound together such that minute gaps 19, 19' are formed between the hard particles into which ink can penetrate. The particles are coated onto the outer circumferential surface of a roller core The binding material is preferably highly oleophilic and hyrdophobic.

In the ink roller 5, the surface of the roller into which ink penetrates exhibits oleophilic and hydrophobic properties. During operation, the hard particles 17 and the binding material 20, in the surface of the roller 5, are abraded by the action of a doctor blade 9, the fountain rubber roller 4, roller 6 and by carbon particles in the ink so that part of the hard particles 17 always protrudes from the surface of the roller. The doctor blade 9 comes in contact with crests of the protruding particles to squeeze ink, whereby ink penetrating into the minute gaps 19, 19' formed between the hard particles 17 can be transferred sequentially to the rollers. The edge of the doctor blade 9 can be ground by the hard particles 17.

Referring to Fig. 2, the core 15 is made of steel and has a surface of length of 1710mm and a diameter of 160mm. The hard particles 17 may comprise aluminum oxide, other oxide or carbide preferably having a average grain size. (The average grain size need not always be 20 microns. Larger grain size and smaller grain size may be mixed together). The hard particles 17 are bound together by the binding material 20 to form the composite material 18. The composite material is coated and set on the core 15. Phenol resin is used as the binder but vitrified oxychloride rubber, ceramic or other resin may also be used. Binding which is achieved through the use of the binding material 20 produces the minute gaps 19, 19' which are formed between the hard particles 17. The ink penetrates through the minute gaps 1~1__ 7into the surface of the composite material 18 as well as the interior thereof.

In a further embodiment of a roll in Fig. 3, the core 15 is made of steel. The core has a surface length of 1710mm and a diameter of 160mm. The composite material 18 is prepared using a plastic as the hard material 16 and aluminum oxide of 20-micron average grain size as the hard particles 17. These were coated and set on the core The hard material 16 was mixed with the hard particles 17 by 25 percent in volume.

After the coating has set, the roller 5 is ground to a diameter of 163.5mm. Finally its outer circumferential surface is polished with emery paper of about #i000, thus forming recesses having a depth of 5 to 10 microns in the surface. These recesses are used to hold ink.

The roller 5 is then set in the press, as shown in Fig. 1. The doctor blade 9, having a thickness of 0.2mm is set to contact the roller 5 at an angle of 0 to Printing was carried out and excellent printing characteristics where obtained. The impression was effected about a thousand times. Print quality was not degraded during the impression by ink exfoliation due to interference by water required for printing. Optical density was sufficiently high.

As described above, the composite material comprises a large number of highly wear resistant hard particles. The hard particles are bound by a binding material such that minute gaps are formed between hard particles into which ink penetrates. The particles are coated onto the outer circumferential surface of the roller core. Progressive wear of the hard particles by the doctor blade results in the sequential protrusion to the surface of hard particles which lie initially within the coating.

Minute gaps are formed into which ink penetrates so that the ink can make the surface highly oleophilic and

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VI,

hydrophobic. The minute gaps into which ink penetrates can be protruded and exposed to the surface. The coating on the core is formed of the composite material which comprises the hard material that is highly oleophilic and hydrophobic. A number of wear-resistant hard particles and minute recesses for ink retention are formed in the surface of the composite material. Wear of hard particles by the doctor blade results in sequential protrusion of the remaining hard particles and minute ink retaining recesses are formed automatically and sequentially. Consequently, the ink roller can be used for longer periods of time which is highly economical. The cutting edge of the doctor blade may be ground during use so that it can withstand longer periods of use. Print quality is improved. The cost of printing can be reduced as a whole.

The embodiments have been advanced by way of example only and modifications are possible within the spirit and scope of the invention as defined in the claims.

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Claims

2. The ink metering roller of claim 1 in which said potential ink cell dispersion providing means includes a dispersion of element defining walls between potential cells.
3. The ink metering roller of claim 2 in which the cell enabling means includes means for wearing away material between the dispersion of wall defining elements at the surface of the outer layer to form the actual cells from the potential cells.
4. The ink metering roller of claim 3 in which said material that is worn away substantially fills the space between said wall defining elements prior to being worn away. The ink metering roller of claim 3 in which the material worn away to form the actual cells is a different material than that of the wall defining elements.
6. The ink metering roller of claim 5 in which the material of the wall defining elements is relatively harder than the material worn away to form the cells.
7. The ink metering roller of claim 1 in which the dispersion is substantially uniform throughout the depth of the outer layer to maintain a uniform ink holding capacity as the surface of the outer layer is worn away.
8. The ink metering roller of claim 5 in which the material worn away to form the cells is material which fills the cells before the cells are formed.
9. A method of maintaining a substantial uniform ink metering capacity of an ink metering roller, comprising the steps of: providing an outer coat for said roller with a substantially uniform dispersion of potential ink carrying cells throughout a significant thickness thereof; causing potential cells beneath the surface to become new actual cells as actual cells at the surface are worn away, said new actual cells being created at substantially the same rate at which said actual cells at the surface are worn away to maintain a uniform actual cell capacity at different thicknesses of the outer coat. The method of claim 9 in which said potential cells are filled with material which is worn away when they reach the surface to form the actual cells.
11. The method of claim 10 in which said step of causing includes the step of waring away material at the surface of the outer coat with a doctor blade.
12. A device for supplying ink for a printing press comprising a roll, and a doctor blade associated with the roll, said roll having an outer layer defining a plurality of recesses exposed in an outer surface of the layer, and a plurality of additional recesses being exposed on the surface as the layer of the roll is worn.
13. The device claim 12 wherein the roll comprises an inner roller, and a binder material forming the layer on an outer surface of the roller. -i.9
14. The device of claim 12 wherein the recesses in the outer surface of the layer are formed by a plurality of particles retained on the outer surface of the layer. The device of claim 12 wherein the additional recesses are formed by a plurality of particles embedded in said layer.
16. An ink metering roller substantially as hereinbefore described and illustrated with reference to the accompanying drawings.
17. A process for producing an ink metering roller substantially as hereinbefore described and illustrated with reference to the accompanying drawings.
18. A method for maintaining a substantial uniform ink metering capacity of an ink metering roller substantially as hereinbefore described and illustrated with reference to the accompanying drawings. DATED this 13th day of November, 1992. ROCKWELL INTERNATIONAL CORPORATION By Its Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia I i ABSTRACT An ink metering roller for use in a printing press in conjunction with a doctor blade that contacts the surface of the roller to remove excess ink therefrom, comprising: a core of preselected strength and dimensions; and means providing a surface on said core having recesses to hold ink, said means including an outer ink metering layer covering said core, said outer layer including an outer layer of matrix material having oleophilic and hydrophobic properties, which material is worn away during contact with the doctor blade, and (ii) a quantity of relatively wear resistant elements dispersed throughout said outer layer of matrix material, the relatively greater wear of said matrix material caused by the doctor blade leaving some of said elements protruding outwardly beyond the outer surface of said matrix material to define recesses holding quantities of ink and supporting the doctor blade at different depths of said outer layer as it is worn. /2