一、麻花钻头的钻芯增量与扇形板的半径由于麻花钻头的钻芯必须沿轴向逐渐增厚,故扇形轧辊的半径也必须是变量,即扇形板的外圆应是一条阿基米德螺线(见图1)。这条螺线可以用铲齿车床加工,因此磨截形又被称为“铲磨”。按国家标准GB1436——78,钻芯增量应为:K_(?)=△k/△l=0.014～0.02式中:△l为沿轴线方向的一段长度: First, the twist drill twist drill core and the radius of the sector As twist drill bit core must be gradually increased along the axial thickness, the radius of the fan-shaped roll must also be a variable, that is, the outer sector of the sector should be an Archimedean German spiral (see Figure 1). This helix can be machined with a shovel, so the truncation is also called shoveling. According to the national standard GB1436--78, the increment of drilling core should be: K _ (?) = △ k / △ l = 0.014 ~ 0.02 Where: △ l is a length along the axial direction: