| 摘要 |
PURPOSE:To form the leading side of a cutting blade into a circular arc of high accuracy by fixing a secondary tip machined into a prescribed diameter on a holder, and relieving the outer circumferential face, in a ball end mill forming a recessed face by cutting work. CONSTITUTION:A secondary tip 10b is formed by finish machining the outer circumferential face 12 of a primary tip into a prescribed diameter with an external cylindrical grinding machine. Meanwhile, by recessedly forming the left end part of a bar-like holder 17, a fitting surface 18 having a flat part 18a extended in the lengthwise direction of the holder 17 and a circular arc step part 18b with nearly same radius as that of the secondary tip 10b on the holder base part side of the flat part 18a is formed. The secondary tip 10b is fixed on the holder 17, by contacting one face and the outer circumferential face 12 respectively with the flat part 18a and the circular arc step part 18b of this fitting surface 18. Further, the leading side 12b of the secondary tip 10b on the outer circumferential face of the outer end part of the holder is relieved, and the relief side is formed into a small diameter. |
