GB2089473A

GB2089473A - Ink Ductor Roller

Info

Publication number: GB2089473A
Application number: GB8137211A
Authority: GB
Original assignee: Polygraph Leipzig Kombinat Veb
Current assignee: Polygraph Leipzig Kombinat Veb
Priority date: 1980-12-12
Filing date: 1981-12-10
Publication date: 1982-06-23
Also published as: DD154087A1; FR2498523A1; DE3136351A1; SE8107410L; JPS57110448A

Abstract

An ink ductor roller, for cooperation with a zonally actuable doctor blade of steel or brass in a rotary printing machine, is designed with a view to suppressing the metering irregularities which are caused through the co-operation of the ink ductor roller with the doctor blade and which are visible as ink deviations in the printed image. To accordingly provide the ductor roller with good bending stiffness and a high wear resistance paired with good sliding properties, an outside layer (3), applied by metal spraying, of the roller comprises an extremely wear- resistant supporting layer (4) into which material (5) capable of sliding is embedded in islands, the material (5) capable of sliding being provided in parts with openings (5') towards the surface of the supporting layer (4). <IMAGE>

Description

SPECIFICATION Ink Duct or Roller The present invention relates to an ink ductor roller, and has particular reference to a ductor roller for co-operation with a zonally actuable doctor knife of steel of brass in a rotary printing machine.

In printing machine construction, use is predominantly made of ink ductor rollers of cast iron. This material possesses a relatively small modulus of elasticity. An ink ductor roller of cast iron is accordingly prone to distortion, which has a negative effect on the reproduction of settings, particularly in modern ink metering equipment with ink zone remote setting.

If ink ductor rollers of steel are employed, these are not functionally reliable due to the pairing of the steel roller with doctor blades of steel or brass, since on the blank-setting of the ink ductor roller (thus ink gap equal to 0) and even with small gaps between the blade and roller, erosion points arise through body contact and the resulting grooves in the ductor roller can lead to metering irreguiarities.

There is accordingly a need for an ink ductor roller, which can co-operate with a doctor blade of steel or brass and which has a great bending stiffness and a high wear resistance paired with good sliding properties, such a roller being able to suppress metering irregularities which result from co-operation with the doctor blade and which are visible as ink deviations in a printed image.

According to the present invention there is provided an ink ductor roller comprising a base body of steel provided with a circumferential covering comprising a sprayed outer layer of wear-resistant material in which a low friction material is embedded in islands, the low friction material being provided with openings facing towards the surface of the outer layer.

In a preferred embodiment, the outer layer is applied through metal spraying and comprises an extremely wear-resistant supporting layer, into which material capable of sliding is embedded in islands, the material capable of sliding in parts having openings towards the surface of the supporting layer.

Such a ductor roller is stiff in bending, so that accurate reproduction of settings is ensured. Due to the high wear resistance, the operating life of the roller is appreciably increased. Virtually no reduction in the quality of the surface occurs, as due to the abrasion, which in consequence of the wear-resistant supporting layer is in any case small, openings of the material capable of sliding arise again towards the surface and the features favouring quality are thus maintained. The ink ductor roller is very easily restored by grinding the surface.

Co-operation of the ink ductor roller with a doctor blade is improved through the increase in the capability of sliding of the roller surface. In the case, of, in particular, ink gaps tending towards zero or a blank setting of ink ductor roller (gap 0), satisfactory operation of the roller is ensured.

The pairing of roller and blade can be optimized through the composition of the outside layer, with the desired effect on the slidability of the surface of the ink ductor roller.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawing, the single figure of which is a schematic section of part of a multi-layer shell of an ink ductor roller.

Referring now to the drawing, there is shown an ink ductor roller comprising a steel base body 1 to which is applied, by coating process, a welladhering intermediate layer 2 of nickel and aluminium. Sprayed over the intermediate layer 2 is an outside layer 3, which consists of an extremely wear-resistant supporting layer 4 and a material 5 capable of sliding embedded therein in islands. This is achieved through the choice of a metal powder which is applied to metal spraying and which, through its composition, brings about the above-mentioned technical effect.

The components of the wear-resistant supporting layer 4 are tungstem W, aluminium Al, titanium Ti and cobalt Co and/or their oxides, carbides and nitrides. The material capable of sliding consists of molybdenum, copper Cu, chromium Cr and nickel Ni and/or their oxides and/or sulfides. The islands of material capable of sliding in parts have openings 5' towards the surface 4' of the supporting layer 4. The openings 5' are distributed relatively uniformly on the ink ductor roller surface and determine the capability of sliding of the outside layer 3. In order to increase the metering accuracy through the operational pairing of doctor blade and ink ductor roller, a mechanical finishing treatment of the surface 4' is preferably, as the metal spraying process may result in excessive surface roughness. The depth of roughness is less than 5 microns.

Claims

1. An ink ductor roller comprising a base body of steel provided with a circumferential covering comprising a sprayed outer layer of wear-resistant material in which a low friction material is embedded in islands, the low friction material being provided with openings facing towards the surface of the outer layer.

2. A roller as claimed in claim 1, wherein the wear-resistant material comprises tungsten, aluminium, titanium and cobalt, each present in the form of any one of pure metal, an oxide, a carbide and a nitride.

3. A roller as claimed in either claim 1 or claim 2, wherein the low-friction material comprises molybdenum, copper, chromium, and nickel each present in the form of any one of pure metal, an oxide and a sulphide.

4. A roller as claimed in any one of the preceding claims, wherein the outer layer has a

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Ink Duct or Roller The present invention relates to an ink ductor roller, and has particular reference to a ductor roller for co-operation with a zonally actuable doctor knife of steel of brass in a rotary printing machine. In printing machine construction, use is predominantly made of ink ductor rollers of cast iron. This material possesses a relatively small modulus of elasticity. An ink ductor roller of cast iron is accordingly prone to distortion, which has a negative effect on the reproduction of settings, particularly in modern ink metering equipment with ink zone remote setting. If ink ductor rollers of steel are employed, these are not functionally reliable due to the pairing of the steel roller with doctor blades of steel or brass, since on the blank-setting of the ink ductor roller (thus ink gap equal to 0) and even with small gaps between the blade and roller, erosion points arise through body contact and the resulting grooves in the ductor roller can lead to metering irreguiarities. There is accordingly a need for an ink ductor roller, which can co-operate with a doctor blade of steel or brass and which has a great bending stiffness and a high wear resistance paired with good sliding properties, such a roller being able to suppress metering irregularities which result from co-operation with the doctor blade and which are visible as ink deviations in a printed image. According to the present invention there is provided an ink ductor roller comprising a base body of steel provided with a circumferential covering comprising a sprayed outer layer of wear-resistant material in which a low friction material is embedded in islands, the low friction material being provided with openings facing towards the surface of the outer layer. In a preferred embodiment, the outer layer is applied through metal spraying and comprises an extremely wear-resistant supporting layer, into which material capable of sliding is embedded in islands, the material capable of sliding in parts having openings towards the surface of the supporting layer. Such a ductor roller is stiff in bending, so that accurate reproduction of settings is ensured. Due to the high wear resistance, the operating life of the roller is appreciably increased. Virtually no reduction in the quality of the surface occurs, as due to the abrasion, which in consequence of the wear-resistant supporting layer is in any case small, openings of the material capable of sliding arise again towards the surface and the features favouring quality are thus maintained. The ink ductor roller is very easily restored by grinding the surface. Co-operation of the ink ductor roller with a doctor blade is improved through the increase in the capability of sliding of the roller surface. In the case, of, in particular, ink gaps tending towards zero or a blank setting of ink ductor roller (gap 0), satisfactory operation of the roller is ensured. The pairing of roller and blade can be optimized through the composition of the outside layer, with the desired effect on the slidability of the surface of the ink ductor roller. An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawing, the single figure of which is a schematic section of part of a multi-layer shell of an ink ductor roller. Referring now to the drawing, there is shown an ink ductor roller comprising a steel base body 1 to which is applied, by coating process, a welladhering intermediate layer 2 of nickel and aluminium. Sprayed over the intermediate layer 2 is an outside layer 3, which consists of an extremely wear-resistant supporting layer 4 and a material 5 capable of sliding embedded therein in islands. This is achieved through the choice of a metal powder which is applied to metal spraying and which, through its composition, brings about the above-mentioned technical effect. The components of the wear-resistant supporting layer 4 are tungstem W, aluminium Al, titanium Ti and cobalt Co and/or their oxides, carbides and nitrides. The material capable of sliding consists of molybdenum, copper Cu, chromium Cr and nickel Ni and/or their oxides and/or sulfides. The islands of material capable of sliding in parts have openings 5' towards the surface 4' of the supporting layer 4. The openings 5' are distributed relatively uniformly on the ink ductor roller surface and determine the capability of sliding of the outside layer 3. In order to increase the metering accuracy through the operational pairing of doctor blade and ink ductor roller, a mechanical finishing treatment of the surface 4' is preferably, as the metal spraying process may result in excessive surface roughness. The depth of roughness is less than 5 microns. Claims

4. A roller as claimed in any one of the preceding claims, wherein the outer layer has a mechanically smoothed outer surface with a roughness depth not greater than substantially 5 microns.

5. An ink roller substantially as hereinbefore described with reference to the accompanying drawing.