| 摘要 |
PURPOSE:To relax concentrated stress at a corner of an end mill tool, and as well to reduce defects and abrasions in the tool, by forming the outer peripheral corner part of the shear point of the end mill tool in such a shape that the corner of the corner part takes the form of a circular arc having a radius of larger than 1/40 but less than 1/3 of the diameter of the rotary tool or a similar curve. CONSTITUTION:The diameter of a drill is 10mm. dia. and the corner part thereof is in a shape of a circular arc having a radius of curvature of 1/20 of the drill diamter or 0.5mm. radius. Twisted grooves for discharging chips are extended from the tip of the drill in a distant of 4 times longer than the drill diameter or 40mm. and the overall length of the drill is 100mm.. The high hardness sintered material 1 of the shear point of the drill is the one including high pressure phase boron nitride, is covered at both surfaces with super-alloy 3, and is brazed to a shank 4 with the use of silver solder 2. |
