Refiner and method for refining fibrous material

A method for refining fibrous material comprising the steps of:

• refining fibrous material by passing said fibrous material into a refiner chamber formed between a first refining element and a second refining element, the at least one refining element forming a shell having a back side, a shell body and a front side, the front side defining a first refining surface comprising portions of the shell body which extend away from the shell body forming outwardly extending blade bars which terminate at the first refining surface, the blade bars defining blade grooves therebetween, and wherein the refining element has portions forming a regular geometrically distributed pattern of a multiplicity of first openings passing though the shell body from the back side to the first refiner surface so that at least most of the first openings cut through at least one blade bar, and substantially every blade bar is cut by said openings a plurality of times, the second refining element having a second refining surface which is arranged at least partly substantially opposite to the first refining surface;
• defibrating the fibrous material in the refiner chamber with the blade bars with the blade grooves therebetween, which blade bars and grooves being formed on at least the first refining surface, the defibrating of the fibrous material in the refiner chamber taking place by moving at least a selected one of the first refining surface and the second refining surface with respect to the other refining surface;
• wherein the step of defibrating the fibrous material in the chamber formed between the first refining surface and the second refining surface further comprises passing the fibrous material either in through the first openings or out through the first openings in at least the first refining surface, which first openings extend through the first refining surface into the refiner chamber;
• wherein the first refining surface defines a total refining area of the refining surface, and the first openings define a surface area of said first openings;
• and
• wherein a ratio is formed between the surface area of said first openings and the total refining area of the first refining surface which is from 10% to 40%.

A refiner for refining fibrous material comprising:

• at least one refining element forming a shell having a back side, a shell body, and a front side, the front side defining a first refining surface comprising portions of the shell body which extend away from the shell body forming outwardly extending blade bars which terminate at the first refining surface, the blade bars defining blade grooves therebetween;
• wherein the at least one refining element has portions forming a regular geometrically distributed pattern of a multiplicity of first openings passing though the shell body from the back side to the first refining surface so that at least most of the first openings cut through at least one bar, and substantially every bar is cut by said openings a plurality of times;
• at least one second refining surface which is arranged at least partly substantially opposite to the first refining surface to form a refiner chamber therebetween, to which material to be defibrated is arranged to be fed;
• at least a selected one of the first refining surface and the second refining surface in the refiner being arranged to move with respect to the other refining surface;
• wherein the first refining surface has a total refining area, and the first refining surface portions forming the first openings are ones through which fibrous material to be refined may be arranged to be fed into the refiner chamber of the refiner or removed from the refiner chamber of the refiner, the first openings defining a surface area;
• and
• wherein a ratio is defined of the surface area of said first openings to the total refining area which is from 10% to 40%.

A blade segment for a refiner intended for refining fibrous material, the blade segment comprising

• a shell having a back side, a shell body, and a front side, the front side defining a first refining surface comprising portions of the shell body which extend away from the shell body forming outwardly extending blade bars which terminate at the first refining surface, the blade bars defining blade grooves therebetween;
• wherein the refining surface has portions forming a regular geometrically distributed pattern of a multiplicity of openings passing though the shell body from the back side to the refining surface so that at least most of the openings cut through at least one blade bar, and substantially every blade bar is cut by said openings a plurality of times;
• wherein the openings define a surface area of said openings and the refining surface defines a total refining area;
• and
• wherein a ratio defined between the surface area of said openings and the total refining area is from 10% to 40%.