| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball end mill capable of improving strength of a nose part of the ball end mill, preventing chipping by improving a chip discharging property, lengthening tool longevity, improving finished surface roughness and providing a lustrous and beautiful metal surface especially on a cutting surface. SOLUTION: The ball end mill furnished with two pieces of ball blades continued through a chisel edge constituted with flanks of the two pieces of the ball blades on a nose head end part is constituted by making passing difference quantity of the ball blades more than zero and less than 0.2 mm and a chisel angle 165 deg.-185 deg. seen from the front of the ball end mill and by making length of the chisel edge three to sevent times larger a value than that of chisel width seen from the front of the ball end mill.
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