WO2006134208A1

WO2006134208A1 - Creping blade

Info

Publication number: WO2006134208A1
Application number: PCT/FI2006/000196
Authority: WO
Inventors: Ingmar Vesterlund
Original assignee: Ingmar Westerlund Consulting Oy
Priority date: 2005-06-14
Filing date: 2006-06-14
Publication date: 2006-12-21
Also published as: FI20050629A; FI20050629A0

Abstract

A creping blade (2), which is used to detach a paper web (3) moving along a drying cylinder (1) from the drying cylinder to form soft crepe paper, in which blade the upper surface (21) to be arranged against the paper is coated with a coating (22) to reduce wear, said coating (22) being a diamond-like coating.

Description

CREPING BLADE

The present invention relates to a creping blade for a soft crepe paper machine, said blade being used to detach a paper web moving along a drying cylinder from the drying cylinder to form soft crepe paper.

A creping blade is used in paper manufacture to detach the paper web from the surface of the drying cylinder. Traditionally, drying cylinders are cast from cast iron, and the creping blade detaches the paper web by "scratching" the cylinder surface. At the same time, the upper surface or upper edge of the blade produces a compressive force on the paper, thus producing a crepe structure typical of soft crepe paper as needed in the manufacture of soft crepe paper.

The creping blade is subjected to sustained wear. For this reason, creping blades are typically coated with a wear-resistant material. Such a coating may be e.g. ceramic, forming a hard surface and thus reducing wear of the blade.

Specification SE 506 563 describes a blade structure in which the blade thickness is at least 0.5 mm but not over 2 - 3 mm, and in which the edge resting against the cylinder is uncoated, being therefore subjected to wear due to the sliding contact, but in which the upper surface coming into contact with the paper web is coated with a ceramic, metallic or composite coating to reduce wear.

A drawback with the solution disclosed in the SE specification in question is that the blade is subject to wear and reduction of thickness expressly in the portion against the cylinder, and that the surface facing against the paper also undergoes relative wear.

The object of the present invention is to overcome the drawbacks of prior-art technology and to provide a new type of creping blade. The creping blade of the invention makes use of the very advantageous structure of diamond-like coatings (DLC) in particular in the area of the blade surface (upper surface, front surface) facing against the paper web. The edge facing against the cylinder, especially to reduce wear of the cylinder, can then be coated with a different coating, which can be produced via thermal spraying, e.g. plasma spraying (APS, Atmospheric Pressure Spraying, flame or HVOF (High Velocity OxyFuel) spraying. With diamond-like blade coatings, which can be advantageously formed on the blade surface by the so-called PVD (Physical Vapour Deposition) coating method in a PVD reactor. Blades used at present are hardened and coated with ceramics or hard metal to increase the service life (e.g. WC-CoCr or TiO2). The reduction of wear of the blade is based on the hardness of the coating. The hardness of the coatings and hardening varies in the range of HV 700-1500. By increasing the hardness of the coating, it is possible to extend the service life of the blade. Harder than the above-mentioned coatings are diamond or diamond- like carbon coatings (DLC). Diamond-like coatings are used because diamond is the hardest material known, HV 10000 on Vickers scale. By using a diamond coating, the durability of the blade can be significantly improved. By increasing the durability of the blade, the interval between blade changes in the paper machine can be considerably increased. The coating is formed as a film of a thickness of 1-20 μm on the edge of a pre-ground blade.

The features characteristic of the creping blade of the invention and the method for its manufacture are set forth in detail in the claims below.

The creping blade of the invention has a better resistance especially to long- term wear caused by the paper web than prior-art blades.

In the following, the invention will be described in detail by referring to an example and the attached drawing, wherein Fig. 1 illustrates the solution of the invention.

It represents the drying cylinder 1 of a soft crepe paper machine and a creping blade 2 fitted in conjunction with the cylinder. The creping blade is fixed to a blade holder, and it serves to detach the paper web 3 moving along the drying cylinder from the drying cylinder to form soft crepe paper.

In the blade, the upper surface 21 coming into contact with the paper web 3 is coated with a diamond-like DLC blade coating 22, which can be advantageously formed on the surface of the blade by the so-called PVD coating method in a PVD reactor. The edge or part 23 of the edge facing against the cylinder 1 is coated with a ceramic or equivalent wear-resistant coating 24, such as a wear-resistant material, such as a ceramic or hard-metal material (e.g. TiO2 or WC-Co).

The DLC coating 22 may also extend partly over the ceramic coating 24, as indicated in Fig. 1.

It is obvious to a person skilled in the art that different embodiments of the invention are not exclusively limited to the embodiment example described above, but that they may be varied within the scope of the claims presented below.

Claims

1. Creping blade (2), which is used to detach a paper web (3) moving along a drying cylinder (1) from the drying cylinder to form soft crepe paper, in which blade the upper surface (21 ) to be arranged against the paper is coated with a coating (22) to reduce wear, characterized in that the coating (22) is a diamond-like coating.

2. Creping blade according to claim 1 , characterized in that the blade side (23) facing against the drying cylinder or a part of said blade side is coated with a second wear-resistant coating, such as a ceramic or hard-metal coating.

3. Creping blade according to claim 1 or 2, characterized in that the diamond- like coating (22) extends on the blade side facing against the drying cylinder at least partly over the second wear-resistant coating.

4. Method for manufacturing a creping blade (2), which is used to detach a paper web (3) moving along a drying cylinder (1) from the drying cylinder to form soft crepe paper, in which blade the upper surface (21) to be arranged against the paper is coated with a coating (22) to reduce wear, characterized in that the coating of the upper surface to be arranged against the paper is implemented by the PVD (Physical Vapour Deposition) coating method in a PVD reactor, and that the coating (22) is a diamond-like coating.

5. Method according to claim 4, characterized in that the blade side (23) facing against the drying cylinder or a part of said blade side is coated with a second wear-resistant coating, such as a ceramic coating.

6. Method according to claim 4 or 5, characterized in that the diamond-like coating (22) extends on the blade side facing against the drying cylinder at least partly over the second wear-resistant coating.