CEMENTED CARBIDE SQUARE END MILL HAVING OUTER PERIPHERAL EDGE EXCELLENT IN CHIPPING RESISTANCE IN HIGH SPEED CUTTING

摘要

PROBLEM TO BE SOLVED: To provide a cemented carbide square end mill having an outer peripheral edge excellent in chipping resistance in high speed cutting. SOLUTION: This cemented carbide square end mill is constituted of a cutting edge part and a shank part, and at least the cutting edge part is made of a tungsten carbide group cemented carbide. The end mill has a structure in which a cylindrical cut-out bottomed hole concentrically exists along the longitudinal direction of the cutting edge part on a bottom edge surface of the cutting edge part and a cylindrical tip made of the relatively heavy tungsten carbide group cemented carbide is fitted into the cylindrical cut-out bottomed hole. The cutting edge part made of a sintered compact of powder green compact having a composition made of Co: 8 to 10 mass%, chrome carbide and/or vanadium carbide: 0.1 to 1.5 mass%, a composite carbide of Ta and Nb: 0.1 to 1.5 mass% as necessary and tungsten carbide: remainder. The cylindrical tip is made of a sintered compact of powder green compact having a composition made of Co: 0.5 to 2 mass% and tungsten carbide: remainder. The diameter of the cylindrical tip is made a dimension corresponding to 25 to 45% of an outer diameter of the outer peripheral edge of the cutting edge part, and the length is made a dimension corresponding to 20 to 40% of the length of the cutting edge part.