Refiner with easily attachable discs

A refiner comprising,

• a circular plate-shape runner having an outer periphery and two side faces;
• a rotating shaft fixed to a center of the runner to extend perpendicularly thereto;
• at least one annular rib projecting from said outer periphery of the runner in an axial direction of said rotating shaft to form a disc receiving dent portion at one of the side faces of the runner, said annular rib having a side surface, and inner and outer circumferential surfaces;
• a plurality of discs having blades on side faces and outer peripheries, said discs being disposed in the disc receiving dent portion in the runner;
• a plurality of engaging members provided on said outer peripheries of said discs to extend outwardly therefrom;
• and
• a plurality of dent portions for receiving and engaging said engaging members provided in said at least one annular rib, each dent portion extending from the side surface along the axial direction of said rotating shaft and having a bottom surface extending along the side surface of the rib, a first surface and a second surface, said first and second surfaces facing each other and extending from said bottom surface to cross said inner and outer circumferential surfaces of the rib, said first surface facing a rotating direction of said circular plate-shape runner, said second surface facing a direction opposite to said rotating direction of said runner, said discs being fixed and supported onto said runner such that said engaging members contact said first surfaces of the dent portions.