CYLINDRICAL MEMBER FOR ELECTROPHOTOGRAPHY, MAGNET ROLLER, DEVELOPING ROLLER, DEVELOPING DEVICE AND IMAGE FORMING DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent trouble in terms of an image caused by the deterioration of sleeve deflection by eliminating the warpage of an extrusion-molding article caused by a groove or a flat part provided on the extrusion-molding article in order to fix an angle formed by a reference surface provided on a core bar and respective magnetic poles or in order to attain magnetic characteristic distribution. SOLUTION: This magnet roller 11 is provided with a cylindrical magnet M formed by welding magnetic material and performing extrusion molding while magnetic field is applied and having plural fixed magnetic poles and a core bar 12 arranged in the center of rotation of the magnet M. The roller 11 is provided with a reference groove 11a and a dummy groove 11b in an axial direction on the outer periphery of the magnet M, and the respective centers of the grooves 11a and 11b are arranged at equal intervals in a peripheral direction, and also the grooves 11a and 11b have the equal area (s) within a cross section orthogonal to the axial direction.