Sieve for paper pulp strainer and classifier

Claim 2

A sieve for a paper pulp strainer and classifier comprising: at least one elongated element having a U-shaped cross section, said at least one U-shaped element having a bottom including openings therein and two side walls, said at least one element being formed into a least one continuous loop joined together at said sidwalls to form a cylinder, said cylinder having a cylindrical wall substantially comprising said at least one bottom and including and openings, said side walls of said at least one loop extending continuously for 360 degrees, said U-shape being unobstructed for 360 degrees of said at least one loop.

Claim 3

A sieve according to claim 1, wherein the cross section of the at least one element is symmetrical having two parallel flanges of equal length and a bottom perpendicular to said flanges in which the openings are formed.

Claim 4

A sieve for a paper pulp strainer and classifier according to claim 1, wherein said at least one element is disposed with the length thereof being at an angle in a range of 0 to 90° with the direction of the generatrices of the cylinder.

Claim 5

A sieve according to claim 3, wherein the cylinder is fastened at its lower and upper ends by a respective rim, fastened to one of the edges of a side wall.

Claim 6

A sieve according to claim 1, wherein said at least one element is juxtaposed and joined together as a cylinder by a weld which extends along the entire juxtaposition.

Claim 7

A sieve according to claim 1, wherein said at least one element is held together as a cylinder by a U-shaped section which squeezes the adjacent walls of the elements by extending over the entire juxtaposition.

Claim 8

A sieve according to claim 1, wherein said at least one element is in transverse section of the order of 10 millimeters and of a thickness of the order of one millimeter, said openings being slots of a width between about 10 microns and 1 millimeter.

Claim 9

A sieve according to claim 1, wherein between two adjacent joined side walls, a flat element , with an arcuate edge is positioned to ensure the rigidity of the cylindrical wall of said sieve.

Claim 10

S sieve according to claim 8 wherein the thickness of the flat element is close to the thickness of the U-shaped element and its width is at least equal to the height of the side walls.

Claim 11

A sieve according to claim 1, wherein said at least one element is spirally wound.

Claim 12

A sieve according to claim 10, wherein the number of spirally wound elements of U-shaped cross section is one, and further comprising means for joining and tightly clasping together the spirals of said element.

Claim 13

A sieve according to claim 1, wherein said openings include grooves and slots formed perpendicularly to the side walls in the bottom of the at least one U-shaped element, the grooves having a smaller depth than the thicknes of the bottom, the slots having a greater depth.

Claim 14

A sieve for a paper pulp strainer and classifier comprising juxtaposed elements of U-shaped cross section each having a flat bottom with openings therein and two sidewalls, and wherein the cross-section of the elements is asymmetrical, comprising two flanges of unequal length, the bottom in which the openings are formed being disposed obliquely to the flanges so that the ends of the flanges are in the same plane perpendicular to said flanges and said bottom is inclined relative to said plane, the elements of the U-shaped cross section being arranged to form a cylindrical wall provided with openings.

Claim 15

A sieve for a paper pulp strainer and classifier comprising juxtaposed elements of U-shaped cross section each having a flat bottom with openings therein and two sidewalls, and wherein the cross-section of the elements is asymmetrical, comprising two flanges of unequal length, the bottom in which the openings are formed being disposed obliquely to the flanges so that the ends of the flanges are in the same plane perpendicular to said flanges and said bottom is inclined relative to said plane, the elements of the U-shaped cross section being arranged to form a cylindrical wall provided with openings.

Claim 16

Sieve according to claim 13 characterized in that the elements comprise openings in the form of slots made in the bottom of the U, the axis of the slots forming with the plane transverse to the element an angle alpha of a value substantially equal to the angle of inclination of the spirals relative to the plane perpendicular to the longitudinal axis of the sieve.

Claim 17

A sieve for a paper pulp strainer and classifier comprising juxtaposed elements of U-shaped cross section having a flat bottom including openings therein and two sidewalls, wherein the elements of the U-shaped cross section form a cylindrical wall provided with openings, at least one said element being arched and spirally wound.

Claim 18

A sieve for a paper pulp strainer and classifier comprising juxtaposed elements of U-shaped cross section having a flat bottom including openings therein and two sidewalls, wherein the elements of the U-shaped cross section form a cylindrical wall provided with openings, at least one said element being arched and spirally wound.

Claim 19

Sieve according to claim 15, characterized in that it is made up of a single spirally wound element of U-shaped cross section, the spirals being joined and held tightly clasped together by any means.

Claim 20

A sieve for a paper pulp strainer and classifier comprising juxtaposed elements of U-shaped cross section having a flat bottom and two sidewalls, wherein the elements of the U-shaped cross section form a cylindrical wall provided with openings, wherein said openings include grooves and slots formed in the bottoms of the U-shaped elements, perpendicularly to the side walls; the grooves having a smaller depth than the thickness of the bottom, the slots having a greater depth.

Claim 21

A sieve for a paper pulp strainer and classifier comprising juxtaposed elements of U-shaped cross section having a flat bottom and two sidewalls, wherein the elements of the U-shaped cross section form a cylindrical wall provided with openings, wherein said openings include grooves and slots formed in the bottoms of the U-shaped elements, perpendicularly to the side walls; the grooves having a smaller depth than the thickness of the bottom, the slots having a greater depth.

Claim 22

A sieve for a paper pulp strainer and classifier comprising: at least one elongated element having a U-shaped cross section, said at least one U-shaped element having a bottom and two side walls, said bottom including openings, said at least one element being joined together at said side walls to form a cylinder of said at least one element, said cylinder having a cylindrical wall substantially comprising said at least one bottom including said openings, the cross section of said at least one element being asymmetrical comprising two flanges of unequal length, the bottom in which the openings are formed being disposed obliquely to the flanges so that the ends of the flanges are in the same plane perpendicular to said flanges, and said bottom is inclined relative to the cylindrical surface of the sieve.

Claim 23

A sieve for a paper pulp strainer and classifier comprising: at least one elongated element having a U-shaped cross section, said at least one U-shaped element having a bottom and two side walls, said bottom including openings, said at least one element being joined together at said side walls to form a cylinder of said at least one element, said cylinder having a cylindrical wall substantially comprising said at least one bottom including said openings, the cross section of said at least one element being asymmetrical comprising two flanges of unequal length, the bottom in which the openings are formed being disposed obliquely to the flanges so that the ends of the flanges are in the same plane perpendicular to said flanges, and said bottom is inclined relative to the cylindrical surface of the sieve.

Claim 24

A sieve according to claim 18, wherein said at least one element includes said openings in the form of slots in the bottom of the U-shaped, the axis of the slots forming with a plane transverse to the element an angle of a value substantially equal to the angle of inclination of the spirals relative to a plane perpendicular to the longitudinal axis of the sieve.

Claim 25

A sieve for a paper pulp strainer and classifier comprising: at least one elongated element having a U-shaped cross section, said at least one U-shaped element having a bottom and two side walls, said bottom including openings, said at least one element being wound into at least one continuous loop joining together at said side walls to form a cylinder of said at least one element, said cylinder having a cylindrical wall substantially comprising said at least one bottom and including said openings, said side walls of said at least one loop extending continuously for 360 degrees, said U-shaped being unobstructed for 360 degrees of said at least one loop.

Claim 26

A sieve for a paper pulp strainer and classifier comprising: at least one elongated element having a U-shaped cross section, said at least one U-shaped element having a bottom and two side walls, said bottom including openings, said at least one element being wound into at least one continuous loop joining together at said side walls to form a cylinder of said at least one element, said cylinder having a cylindrical wall substantially comprising said at least one bottom and including said openings, said side walls of said at least one loop extending continuously for 360 degrees, said U-shaped being unobstructed for 360 degrees of said at least one loop.