DE102004022953A1 - Papermaking wet web de-watering drum has water extraction channels distributed evenly on outer face and irregularly on inner face - Google Patents

Abstract

A paper manufacture de-watering assembly has a rotating drum with a perforated mantle (3) that encloses a suction zone (4) coupled to a suction pump via a suction chamber (5). The drum perforations consist of channels that are equally distributed over the drum inner face but irregularly arranged around the outer face. The channels are inclined to the drum radial axis. The channel inlet to the suction chamber is a countersunk drill hole.

Description

The The invention relates to a rotatable suction roll with a perforated Roll shell and at least one suction zone, the one, with a Vacuum source connected, position-stable suction chamber within the roll shell is formed, wherein the perforation through the roll shell extending channels and the channel mouths the inner lateral surface at least predominantly evenly distributed are.

such Suction rollers have been around for a long time known and become u.a. in machines for manufacturing and / or finishing of fibrous webs, in particular paper, board or tissue webs used.

Around while the effect of the suction zone on the wrapping fibrous web evenly will one possible uniform arrangement of preferably many outer canal mouths sought. This is generally done via a variety of holes of the roll shell, which is seconded in circumferential rows and axial rows are and run into the interior of the suction roll.

at the ventilation of the channels after leaving the suction zone, there is a sound emission according to the principle of the hole siren. The fundamental frequency of this is Sound waves from the distance of the channel mouths in the circumferential direction and the rotational speed of the suction roll is determined.

The The object of the invention is the noise in such Suction rollers as effectively as possible to diminish.

According to the invention was solved the task by that the canal mouths at least predominantly on the outer lateral surface distributed unevenly are. By the unevenness the outer channel mouths the frequency spectrum of the resulting sound is widened, what the perceptible noise decreases.

there should at least at a predominant Part of the channels at least one ending on the outer lateral surface Channel section inclined to the radial direction.

The Radial direction also corresponds to the vertical on the cylindrical roll shell.

The The result is perfected if at least one of the ends of all the channels ends in the outer surface Channel section extends inclined to the radial direction.

there is it advantageous with regard to the production of the roll mantle, if at least some, preferably all channels inclined entirely to the radial direction run and / or the channels executed as holes are.

Also about that Can sink at least a portion of the holes on the inner circumferential surface, especially if the type and depth of the countersink varies be changed, the frequency distribution of the sound emission and so the noise level be reduced.

A greater frequency diversity and therefore less noise let yourself also achieve that the holes have different diameters and / or the radial inclination to the radial direction in the channels is different in size.

to But it may also be advantageous to simplify production if the inclination to the radial direction is the same for the channels, but varies in the direction of inclination.

in the With regard to retrofitting already radially drilled roll shells if it has a reference advantageous if only the each extending in relation to the channel section inclined to the radial direction runs. Thus, when changing the cover, the desired inclination of the channel sections easily will be realized.

following the invention will be explained in more detail in several embodiments. In the accompanying Drawing shows:

1 a schematic cross section through a suction roll;

2 : a partial cross section through a roll shell 3 with reference 6 and

3 : a partial cross-section through another roll shell 3 ,

According to 1 The suction roll is made of an air-permeable belt 2 and the outer fibrous web 1 entwined. To the fibrous web 1 in the wrap around the tape 2 to suck and so improve the web guide, the suction roll has a suction zone 4 ,

This suction zone 4 is inside the roll mantle 3 from a position-stable suction chamber 5 formed opposite to the rotating roll shell 3 sealed and with an external sub pressure source is connected.

The roll jacket 3 has a perforation in the form of a plurality of continuous channels 7 , so that the negative pressure of the suction chamber 5 through the perforation and the air-permeable band 2 on the fibrous web 1 can work.

If the channels 7 during rotation the area of the suction chamber 5 leave, it comes to pressure equalization and thus the inflow of air into the channels 7 , In order to increase the frequency spectrum of the sound emission and thus reduce the noise, are the channels 7 or their outer channel sections 8th to the radial direction 11 of the roll mantle 3 differently inclined.

To simplify the production, the channels 7 designed as holes with the same diameter.

In 2 owns the roll shell 3 an outer cover 6 made of plastic. While the hole outside the cover 6 in the radial direction 11 runs, is the reference 6 extending channel section 8th to the radial direction 11 inclined. This allows a retrofit in Walzenmänteln 3 whose relation 6 is changed.

there are the canal mouths on the inner lateral surface evenly and unevenly distributed on the outer lateral surface.

At the in 3 shown embodiment, the entire bore to the radial direction 11 inclined, which simplifies the production.

To influence the frequency of the sound emission, the holes also have different depths 9 on.

Claims (11)

Rotatable suction roll with a perforated roll shell ( 3 ) and at least one suction zone ( 4 ) connected by a, with a vacuum source, position-stable suction chamber ( 5 ) within the roll shell ( 3 ) is formed, wherein the perforation through the roll shell ( 3 ) running channels ( 7 ) and the channel openings are at least predominantly uniformly distributed on the inner circumferential surface, characterized in that the channel mouths are at least predominantly unevenly distributed on the outer lateral surface. Rotatable suction roll according to claim 1, characterized that the canal mouths Equidistant on the inner surface are arranged. Rotatable suction roll according to claim 1 or 2, characterized in that at least a majority of the channels ( 7 ) at least one end of the outer circumferential surface channel section ( 8th ) to the radial direction ( 11 ) inclined. Rotatable suction roll according to claim 3, characterized in that in all channels ( 7 ) at least one end of the outer circumferential surface channel section ( 8th ) to the radial direction ( 11 ) inclined. Rotatable suction roll according to claim 3 or 4, characterized in that at least some, preferably all channels ( 7 ) entirely to the radial direction ( 11 ) inclined. Rotatable suction roll according to one of the preceding claims, characterized in that the channels ( 7 ) are designed as holes. Rotatable suction roll according to claim 6, characterized that at least part of the bores is countersunk on the inner circumferential surface. Rotatable suction roll according to claim 6 or 7, characterized characterized in that the holes have different diameters exhibit. Rotatable suction roll according to one of the preceding claims, characterized in that the inclination to the radial direction ( 11 ) at the channels ( 7 ) is different in size. Rotatable suction roll according to one of claims 1 to 8, characterized in that the inclination to the radial direction ( 11 ) at the channels ( 7 ) is the same size. Rotatable suction roll according to one of the preceding claims, characterized in that the roll shell ( 3 ) a reference ( 6 ) and preferably only in each case in relation ( 6 ) extending channel section ( 8th ) to the radial direction ( 11 ) inclined.