Gl&v Sweden Ab

Roine Andersson

Lars-G&ouml;ran Rundqvist

A method for manufacturing a screen plate with screen slots from a thin plate ( ), which screen slots ( ) are achieved by cutting. The plate is formed by bending to a screen plate of a desired shape. The screen slots ( ) are produced by a laser beam for cutting, which hits the plate from one of its sides, the inlet side. Focus for the beam is situated on a predetermined depth between both sides of the plate. The slot is obtained by at least two cutting operations following each other, in which the direction ( ) of the laser beam forms two different angles with the main plane of the plate. There is obtained a screen slot ( ), the cross section of which increases against the other side of the plate, the outlet side.

Manufacture of screen plate with screen slots obtained by laser beam cutting

In a pressure screening device for separating undesired particles from a fibre suspension a cylindrical screen ( ) is provided. The screen has an outer side and an inner side and is provided with a plurality of projections ( ) on the outer side of the screen ( ) which extend in the circumferential direction of the screen ( ), grooves ( ) formed on the inner side of the screen ( ) and extending in a direction having an axial component, and screening passages in the form of slots ( ) disposed in the area of each groove ( ) and diverging from the inner side of the screen ( ) towards its outer side. According to the invention, the projections ( ), grooves ( ) and slots ( ) of the screen ( ) are produced by working of a substantially planar screen plate bent into cylindrical shape subsequent to the working. Thereby it is possible to form a screen ( ) having uniform slots ( ), the width of which at the inner side of the screen ( ) is only about 0.1 mm. The invention also relates to a method of manufacturing such a screen ( ).

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Furusund, Sweden

Roine Andersson