ZH110型微型汽车上的转向节是转向系统上的关键零件。零件形状复杂（见图1），三个悬臂上的三个锥孔对于轮轴轴线位置度要求较高，给加工带来很大困难。钻轮轴两端中心孔是第一道工序，中心孔的质量好坏直接影响三个锥孔对于轮轴的位置度。如何保证两中心孔的精度，是达到此零? Steering knuckles on the ZH110 miniature car are key components of the steering system. The complex shape of the parts (see Figure 1), the three conical holes on the three cantilevers require a high degree of axial position of the axle, which brings great difficulties to the processing. Drill shaft center hole at both ends is the first procedure, the quality of the center hole directly affects the position of the three cone for the wheel shaft. How to ensure the accuracy of the two center holes, is to achieve this zero?