大型长轴的两端面中心孔,是工件车削的定位基准,有十分严格的加工要求。因为大型长轴的坯料一般为型钢件、锻压件和铸钢件,外径往往不圆正、不规则、不光滑,因而不能直接放在车床中心架上,出车床卡盘夹住工件作旋转运动。如由钳工用手电钻加工长轴中心孔,则质量差、效率低,劳动强度大。 Large long axis of both ends of the center hole is the positioning of the workpiece turning standards, there are very strict processing requirements. Because the large long axis of the billet is generally steel, forging and cast steel, the outer diameter is often not round positive, irregular, not smooth, and therefore can not be directly on the lathe center frame, the lathe chuck clamping work piece for rotation movement. If the fitter hand drill long axis of the center hole, the poor quality, low efficiency, labor-intensive.