Refiner disc

Abstract

A refiner disc of a refiner for refining of lignocellulosic material has an active surface configured to face another refiner disc when used in the refiner. active surface comprises a pattern of bars and grooves disposed in a plurality of pattern areas. The pattern areas are positioned side by side with each other to cover at least a part of the active surface.

1 - 14 . (canceled) 
     
     
         15 . A refiner disc of a refiner for refining of lignocellulosic material, the refiner disc having an active surface configured to face another refiner disc when used in the refiner, wherein the active surface comprises a pattern of bars and grooves disposed in a plurality of pattern areas, wherein the pattern areas are positioned side by side with each other to cover at least a part of the active surface,
 wherein each of the pattern areas has a length extending between a first end and a second end of the pattern area and a width extending between two side edges, which two side edges both extend between the first and second ends of the pattern area, wherein the second end is provided at an outer circumference of the active surface and the first end is provided closer to a centre of the refiner disc than the second end is and wherein a distance between the two side edges is smallest in the first end of the pattern area and increases towards the second end of the pattern area, and   wherein each of the pattern areas is positioned on the active surface such that a centre line of the pattern area, which is positioned in a centre of the pattern area and extends from the first end to the second end of the pattern area, is provided at an angle to a radius of the refiner disc passing through a centre position of the pattern area, the angle being between 10°-60°,   wherein at least some of the bars are extending along a direction between the two side edges of the pattern area in which the bars are provided,   wherein at least 80% of a total number of bars which are provided within one pattern area extend only within the pattern area.   
     
     
         16 . The refiner disc according to  claim 15 , wherein the sizes and extension directions of the bars within each pattern area can be freely varied within each pattern area. 
     
     
         17 . The refiner disc according to  claim 15 , wherein at least 90% of the bars which are extending along a direction between the two side edges of the pattern area have a length which is at least 75% of the width of the pattern area where each respective bar is positioned. 
     
     
         18 . The refiner disc according to  claim 15 , wherein the pattern area is delimited in its second end by a part of the outer circumference of the active surface, which part extends between the two side edges of the pattern area, the part having a length corresponding to an arc length of a circular sector having a central angle being between 1°−15° in a circle with the outer circumference of the active surface. 
     
     
         19 . The refiner disc according to  claim 15 , wherein the pattern area is delimited in its second end by a part of the outer circumference of the active surface, which part extends between the two side edges of the pattern area, the part having a length corresponding to an arc length of a circular sector having a central angle being between 4°-12° in a circle with the outer circumference of the active surface. 
     
     
         20 . The refiner disc according to  claim 15 , wherein the centre line, c, of the pattern area is provided at an angle, p, to a radius, R, of the refiner disc, the angle, p, being between 20°-40°. 
     
     
         21 . The refiner disc according to  claim 15 , wherein the bars each has a length, a thickness and a height, wherein the height extends in a perpendicular direction from the active surface, whereby a thickness of the bars within each pattern area decreases towards the outer circumference of the active surface. 
     
     
         22 . The refiner disc according to  claim 15 , wherein a distance between adjacent bars in the same pattern area decreases towards the outer circumference of the active surface. 
     
     
         23 . The refiner disc according to  claim 15 , wherein an average angle between a direction of length extension of each bar in a pattern area and a radius of the refiner disc passing through a middle point of this bar decreases towards the outer circumference of the active surface. 
     
     
         24 . The refiner disc according to  claim 15 , whereby in a first part of the pattern area starting from the first end and extending towards the second end of the pattern area the bars are not extending all the way between the first and second side edges but are leaving an open wedge-shaped area without bars between adjacent pattern areas. 
     
     
         25 . The refiner disc according to  claim 15 , whereby there are at least three end bars in each pattern area which are shorter than an adjacent bar in a direction towards the first end of the pattern area, which end bars are the bars positioned closest to the second end of the pattern area, whereby these end bars each extends towards the outer circumference of the active surface. 
     
     
         26 . The refiner disc according to  claim 15 , wherein dams are provided to the active surface, whereby each dam extends between two adjacent bars, wherein at least four dams are positioned such that they together form a continuous dam provided along a smooth curve. 
     
     
         27 . The refiner disc according to  claim 24 , wherein each pattern area comprises a continuous last dam comprising at least four dams which are connecting at least five end bars of this pattern area, which end bars are the bars positioned closest to the second end of the pattern area, whereby the continuous last dam of a plurality of pattern areas are connected, whereby a combined continuous last dam is provided substantially along the outer circumference of the active surface. 
     
     
         28 . A refiner segment for use in a refiner disc according to  claim 15 , wherein the refiner segment comprises a part of the active surface of the refiner disc, wherein the refiner segment comprises a number of complete pattern areas and/or a number of parts of pattern areas.