Roller with coating

Abstract

A heatable roller suitable for a machine for producing and/or upgrading a web of material, in particular a fibrous material web such as a paper, paperboard or tissue web. The roller has a main element with a metallic and cylindrical roller wall which is heatable by suitable means and on the radially outer side of which there is, at least in sections, a coating. When the roller is used as intended, the coating provides a web contact side which can be brought into contact with the web of material. The coating includes, or is formed by, at least one metallic or metal-carbidic layer with a first layer component providing a matrix and a second layer component distributed in the matrix. The first layer component has a higher abrasion resistance than the second layer component and the second layer component has a greater thermal conductivity than the first layer component.

Claims

1. A heatable roller for a machine for processing a web of material, the roller comprising: a main element having a heatable, metallic, cylindrical roller wall; a coating formed on a radially outer side of said roller wall, at least in sections thereof, for providing a web contact surface to be brought into contact with the web of material; said coating including at least one metallic or metal-carbidic layer, said at least one metallic or metal-carbidic layer including a first layer component providing a matrix and a second layer component distributed in said matrix; said at least one layer being formed with 60% by weight or more of said first layer component and with not more than 40% by weight of said second layer component; and said first layer component having a higher abrasion resistance than said second layer component and said second layer component having a greater thermal conductivity than said first layer component.

2. The heatable roller according to claim 1, wherein said second layer component is formed, in essence, of a plurality of discrete regions.

3. The heatable roller according to claim 2, wherein discrete regions of said second layer component have a size in a range from 5 to 50 m.

4. The heatable roller according to claim 1, wherein said first layer component comprises, of consists of, an iron-based alloy and/or a cermet.

5. The heatable roller according to claim 4, wherein said iron-based alloy comprises iron and at least one further constituent selected from the group consisting of chromium, niobium, tantalum, molybdenum, silicon, boron and tungsten.

6. The heatable roller according to claim 1, wherein said second layer component comprises, or consists of, copper or a copper-based alloy.

7. The heatable roller according to claim 1, wherein said second layer component is configured to at least partly form a 3-dimensional network.

8. The heatable roller according to claim 7, wherein a plurality of discrete regions of the second layer component are in contact with one another to form the 3-dimensional network.

9. The heatable roller according to claim 1, wherein said coating is formed by a single one of said at least one metallic or metal-carbidic layer.

10. The heatable roller according to claim 1, wherein said at least one layer has a specific thermal conductivity in a range from 15 W/mK to 250 W/mK.

11. The heatable roller according to claim 1, wherein said at least one layer has an abrasion resistance of less than 0.6 g measured in accordance with ASTM G65-04.

12. The heatable roller according to claim 1, wherein said coating has a thickness in a range from 50 m to 1500 m.

13. The heatable roller according to claim 1, wherein said coating consists of said at least one metallic or metal-carbidic layer.

14. The heatable roller according to claim 1, wherein said second layer component consists of copper or a copper-based alloy.

15. A heatable roller for a machine for processing a web of material, the roller comprising: a main element having a heatable, metallic, cylindrical roller wall; a coating formed on a radially outer side of said roller wall, at least in sections thereof, for providing a web contact surface to be brought into contact with the web of material; said coating including at least one metallic or metal-carbidic layer, said at least one metallic or metal-carbidic layer including a first layer component providing a matrix and a second layer component distributed in said matrix; said second layer component comprising copper or a copper-based alloy; and said first layer component having a higher abrasion resistance than said second layer component and said second layer component having a greater thermal conductivity than said first layer component.

16. A process for coating a heatable roller of a machine for processing a web of material, the process comprising: providing a roller body with a heatable, metallic and cylindrical roller wall; and applying a coating to a radially outer side of the roller wall, the coating including at least one metallic or metal-carbidic layer, thereby applying the at least one metallic or metal-carbidic layer with a first layer component providing a matrix and a second layer component distributed in the matrix, the first layer component having a higher abrasion resistance than the second layer component and the second layer component having a greater thermal conductivity than the first layer component; forming the coating with 60% by weight or more of the first layer component and with not more than 40% by weight of the second layer component.

17. The process for coating a heatable roller according to claim 16, which comprises surface-treating the radially outer side of the roller wall prior to applying the coating.

18. The process for coating a heatable roller according to claim 17, wherein the surface-treating step comprises grinding a radially outer surface of the roller wall.

19. The process for coating a heatable roller according to claim 16, which comprises producing the at least one layer by thermal spraying and grinding the metallic or metal-carbidic layer providing the web contact side after the thermal spraying.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention is illustrated below with the aid of a working example, see table 1 and FIG. 1 and also FIGS. 2 and 3.

DESCRIPTION OF THE INVENTION

(2) The present working example is a coating which is formed by only one metallic layer and has been applied to the radially outer side of the cylindrical surface of a Yankee drying cylinder and has the following properties and the following composition:

(3) TABLE-US-00001 TABLE 1 Competition sample 1 Competition (competition sample 2 Invention HVOF) (competition arc) Com- Iron-based alloy: Fe balance, Fe balance, position: Fe > 70% by weight, Mn 2% by weight, Mn 1.65% by Cr 20.6% by weight, Cr 14% by weight, weight, Nb 4.5% by weight, Mo 24% by weight, Cr 29% by Ta 3.5% by weight W 10% by weight, weight, Pure copper (99.9% C 5% by weight B 3.75% by by weight of Cu) weight, Ratio of iron-based Si 1.6% by alloy to copper in weight, the layer: 85% by weight to 15% by weight Thermal 32 W/mK 9 W/mK 11 W/mK conductivity Abrasion 0.17 g 0.2 0.2 resistance ASTM G65-04

(4) It can be seen that the solution according to the invention provides a significantly higher thermal conductivity than is known from the prior art, at a comparable abrasion resistance.

(5) FIG. 1 shows a section, which is not to scale, of a roller wall 1 of a Yankee drying cylinder having the coating 2 according to the invention as per table 1. The coating 2 is formed by a metallic layer which in turn is formed by a first layer component 3 providing a matrix and a second layer component 4 (shown hatched) distributed in the matrix 3.

(6) In the present case, the second layer component 4 is pure copper (99.9% by weight) and in its entirety formed by a plurality of discrete regions which at least partly adjoin one another. The discrete regions of the second layer component 4 have a size in the range from 5 to 50 m. Furthermore, the second layer component 4 at least partly forms a 3-dimensional network, with a majority of the discrete regions of the second layer component 4 being in contact at the boundaries to form the 3-dimensional network.

(7) The layer 2 and thus the coating has a specific thermal conductivity in the region of 32 W/mK and an abrasion resistance in the region of 0.2 g measured in accordance with ASTM G65-04. The thickness of the coating 2 is 500 m.