大直径长轴打中心孔是件麻烦的事。因为坯料一般为热轧件、锻压件或铸钢件,外径往往不圆、不规则、不光滑,因而不能直接放在车床中心架上,由车床卡盘夹住工件作旋转运动。如由钳工划线用手电钻打中心孔,却存在着质量差、效率低、劳动强度高的问题,也不是好办法。我厂万能试验机上长3m、重300多kg的大轴,φ130mm外径表面粗糙、锈斑麻点严重,我们在C630接长车床上,将原有车床尾架座的活顶尖改装成中心孔钻具, Big diameter long axis hit the center hole is a troublesome thing. Because the blank is usually hot rolled, forged or cast steel, the outer diameter is often not round, irregular, not smooth, and therefore can not be directly on the lathe center frame, the lathe chuck clamping workpiece for rotational movement. If the fitter crossed with a flashlight to drill the center hole, but there are poor quality, low efficiency, high labor intensity, is not a good idea. I plant universal testing machine length 3m, weighing more than 300 kg of large shaft, φ130mm outer diameter rough surface, serious rust pits, we long in the C630 lathe, the original lathe tailstock seat into the center of the current drilling center drill With,