Patent Application
20080041206
In the following, the invention will be described in more detail with reference to the accompanying drawings, in which
The main edge portion 20 is relatively linear, as seen in the lateral cross-section according to
The lateral extension of the intermediate portions 28, 30 is denoted I1 and I2, respectively. The intermediate portions 28, 30 also have a curved surface of a desired radius r1 and r2, respectively.
The angle of the side surfaces 16, 18 with respect to a radial plane of the cutter drum 2 is denoted γ1 and γ2, respectively.
The shape of this cutting member is symmetrical, for which reason I1=I2; r1=r2 and γ1=γ2.
Accordingly, the angle γ2 is larger than γ1, causing the first side portion 16 to have a steeper slope than the second side portion 18. Furthermore, the second radius r1 of the second intermediate portion is smaller than the radius r2 of the first intermediate portion, and the lateral extension I1 of the second intermediate portion 30 is larger than the lateral extension I2 of the first intermediate portion 28.
It should however be noted that it would be possible that I1=I2 and that r1=r2.
As in the previous embodiments, the angle of the side surfaces 16, 18 with respect to a radial plane of the cutter drum 2 is denoted γ1 and γ2, respectively.
Furthermore, the angle of the first and second side edge portions 22, 24 with respect to a radial plane of the cutter drum 2 is denoted α1 and α2, respectively.
The shape of this cutting member is symmetrical, for which reason I1=I2; r1=r2; γ1=γ2 and α1=α2.
Accordingly, the main cutting edge 20 is not arranged centrally, but the lateral extension L thereof is pushed to the right. Furthermore, angle γ2 is larger than γ1, causing the first side portion 16 to have a steeper slope than the second side portion 18. Furthermore, the second radius r1 of the second intermediate portion is smaller than the radius r2 of the first intermediate portion, and the lateral extension I1 of the second intermediate portion 30 is larger than the lateral extension I2 of the first intermediate portion 28.
The angle of the first and second side edge portions 22, 24 with respect to a radial plane of the cutter drum 2 is denoted α1 and α2, respectively, and α2>α1.
For the corresponding reasons as those relating to the embodiment of
In all the above embodiments the following ranges are suitable:
r1=5-50 μm
r2=5-50 μm
It has surprisingly been proven that the cutting effort was reduced in the range of 20-40% by means of the cutter drum according to the invention.
Furthermore, a more robust edge than according to the prior art was achieved.
Yet furthermore a better surface roughness was achieved, which in turn increases the lifetime of the cutter drum.
The cutting member 10 according to any one of the above embodiments can be manufactured by grinding a non-shaped member protruding substantially radially from the cutter drum by means of e.g. a diamond wheel shaped to a rounded form, for creating the rounded shape according to the invention. Alternatively, the cutting member is first provided with e.g. sharp edges. The edges are then treated by brushing or by sputtering of abrasive particles for achieving the desired widths and radii of the edges.
Prior art cutting members having sharp edges on either sides of a flat surface, causes the fibre material of the web to be pressed against the anvil. The flat surface and sharp edges prevent the fibre material from escaping laterally away from the edges. This requires a high applied pressure and two cuts on each side of the flat surface, i.e. the compressed portion will be cut along the two sharp edges.
The cutting member according to the invention will instead allow the compressed material to move side-wards, depending on the fact that the rounded edges will create a progressive pressure on the web, and will surprisingly cause the web to tear somewhere between the rounded edges 28, 30 at less pressure than what is the case regarding the prior art cutting members having sharp edges.
This progressive pressure is enhanced by the first and second side edge portion 22, 24.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0601526-7 | Jul 2006 | SE | national |
