Pulp feed for a papermaking machine

Claim 2

A pulp feed for feeding pulp from a headbox into a forming screen of a papermaking machine containing a guide device for a stock suspension, said guide device comprising: an elongate, substantially slot-shaped guide channel means having a predetermined lengthwise direction of extent; said guide channel means being bounded by side surfaces; one of said side surfaces having two substantially step-shaped widened portions; the other of said side surfaces being essentially flat at the region of the widened portions and between said widened portions; the other of said side surfaces defining a substantially flat counter surface; the one of said side surfaces having, before and after each widened portion, a respective surface section merging therewith; each said surface section being essentially flat and extending essentially parallel to said flat counter surface; said step-shaped widened portions defining a first widened portion and a second widened portion spaced from one another in the direction of flow of the stock suspension; a tapered channel section merging with the flat surface section following the first step-shaped widened portion in the direction of flow of the stock suspension; said tapered channel section having a boundary surface enclosing an angle which does not exceed 45° with respect to the flat counter surface; a perforated plate, having substantially cylindrical bores, being connected forwardly of said slot-shaped guide channel means; a mixing chamber being connected after said perforated plate and having an enlarged cross-sectional area in relation to a starting region of said guide channel means; and the length of the flat section following the first step-shaped widened portion amounts to at least six times the height of said first step-shaped widened portion.

Claim 3

A pulp feed for feeding pulp from a headbox onto a forming screen of a papermaking machine containing a guide device for a stock suspension, said guide device comprising: an elongate, substantially slot-shaped guide channel means having a lengthwise direction of extent; said guide channel means being bounded by side surfaces; one of said side surfaces having two substantially step-shaped widened portions; the other of said side surfaces being essentially flat at the region of the widened portions and between said widened portions; the other of said side surfaces defining a substantially flat counter surface; the one of said side surfaces having, before and after each widened portion, a respective surface section merging therewith; each said surface section being essentially flat and extending essentially parrallel to said flat counter surface; said step-shaped widened portions defining a first widened portion and a second widened portion spaced from one another in the direction of flow of the stock suspension; a tapered channel section merging with the flat surface section following the first step-shaped widened portion in the direction of flow of the stock suspension; said tapered channel section having a boundary surface enclosing an angle which does not exceed 45° with respect to the flat counter surface; a perforated plate, having substantially cylindrical bores, being connected forwardly of said slot-shaped guide channel means; a mixing chamber being connected after said perforated plate and having an enlarged cross-sectional area in relation to a starting region of said guide channel means; and the flat surface section directly forwardly of the second step-shaped widened portion having a length amounting to at least twice the gap width of the guide channel means at such location.

Claim 4

A pulp feed for feeding pulp from a headbox onto a forming screen of a papermaking machine containing a guide device for a stock suspension, said guide device comprising: an elongate, substantially slot-shaped guide channel means having a lengthwise direction of extent; said guide channel means being bounded by side surfaces; one of said side surfaces having two substantially step-shaped widened portions; the other of said side surfaces being essentially flat at the region of the widened portions and between said widened portions; the other of said side surfaces defining a substantially flat counter surface; the one of said side surfaces having, before and after each widened portion, a respective surface section merging therewith; each said surface section being essentially flat and extending essentially parrallel to said flat counter surface; said step-shaped widened portions defining a first widened portion and a second widened portion spaced from one another in the direction of flow of the stock suspension; a tapered channel section merging with the flat surface section following the first step-shaped widened portion in the direction of flow of the stock suspension; said tapered channel section having a boundary surface enclosing an angle which does not exceed 45° with respect to the flat counter surface; a perforated plate, having substantially cylindrical bores, being connected forwardly of said slot-shaped guide channel means; a mixing chamber being connected after said perforated plate and having an enlarged cross-sectional area in relation to a starting region of said guide channel means; and the flat surface section directly forwardly of the second step-shaped widened portion having a length amounting to at least twice the gap width of the guide channel means at such location.

Claim 5

The pulp feed as defined in claim 1 or 2 wherein: the flat surface sections located in front of both step-shaped widened portions are located essentially in the same plane in a manner such that they form essentially the same gap widths with the counter surface.

Claim 6

The pulp feed as defined in claim 1 or 2, further including: means for translatorily displacing one of the side surfaces of the guide channel means in relation to the other side surface and essentially perpendicular to the flat counter surface.

Claim 7

The pulp feed as defined in claim 1 or 2, wherein: said bores of said perforated plate are arranged in spaced relationship from one another at a spacing amounting to at least 50 mm between each two adjacent bores.

Claim 8

The pulp feed as defined in claim 5, wherein: said spacing amounts to more than 80 mm.

Claim 9

The pulp feed as defined in claim 1 or 2, further including: pulp feed channel means connected with said guide channel means; sieve means with which cooperate said pulp feed channel means; said pulp feed channel means being provided with at least one adjustable lip for adjusting the cross-sectional area of said pulp feed channel means.

Claim 10

The pulp feed as defined in claim 7, wherein: said pulp feed channel means is structured to provide at least one step-shaped widened portion.

Claim 11

The pulp feed as defined in claim 1, wherein: the flat surface section directly forwardly of the second step-shaped widened portion having a length amounting to at least twice the gap width of the guide channel means at such location.