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针对精密仪器轴系的研制和精度分析,研究了立式三油楔动压轴系的结构、轴承轮廓结构,建立数学模型、分析模型,对轴系动压油膜的动力特性做了分析。对于主轴在动压油膜反力与外载荷作用下处于某一平衡位置(e,bθ)运转时,能否经得起任意微扰动的干扰而失稳,建立了油膜运动稳定性的判据。应用数值模拟和计算机编程,深入研究了关键设计参数楔形间隙bmc、m相应的油膜运动稳定特性,揭示了楔形间隙值与轴系失稳的对应关系,给出了油膜稳定性因数Log(Sp)与偏心率ε(ε=e/c)之间的变化曲线图,并指出了楔形间隙参数最佳的取值范围。研究结果指出:楔形间隙是轴系设计和制造的重要敏感参数;最大楔形间隙bm和最小间隙cm值之间应保持一定的比例,否则油膜运动发散,轴系平衡失稳,导致主轴转动中产生较大的晃动。对于低速立式三油楔动压轴系,则bm-cm≥0.8μm。比较研究结果与成功轴系实例,表明实例中bm、cm取得符合轴系的油膜稳定条件。证明研究结果对该类轴系的设计具有实用性。
Aiming at the development and precision analysis of precision instrument shaft system, the structure and bearing contour structure of vertical three oil wedge hydrofracture system are studied. The mathematical model and analysis model are established, and the dynamic characteristics of dynamic pressure oil film with shaft system are analyzed. When the spindle is in some equilibrium position (e, bθ) under the action of the reaction force and the external load of the dynamic pressure oil film, the stability criterion of the oil film can be established whether it can withstand the instability caused by any perturbation disturbance. The relationship between the wedging clearance and the instability of the shafting was revealed by numerical simulation and computer programming. The stability of the oil film, Log (Sp) And the eccentricity ε (ε = e / c), and pointed out that the optimum range of wedge gap parameters is obtained. The results show that the wedge gap is an important sensitive parameter in the design and manufacture of the shaft system. The maximum wedge gap bm and the minimum gap cm should maintain a certain ratio, otherwise the oil film movement will diverge and the shaft balance will be unbalanced, resulting in the rotation of the spindle Larger shaking. For low-speed vertical three wedge hydrofoil system, then bm-cm ≥ 0.8μm. The comparison between the results of the study and the successful shaft example shows that the bm and cm obtained in the example are consistent with the oil film stability conditions of the shaft system. It is proved that the research results are practical for the design of such shaft system.