高速微小孔钻头动态应力特性

针对微小钻头工作时容易折断的问题,依据转子动力学理论,利用Timoshenko梁-轴单元,建立了微孔钻床主轴系统的动力学模型。该模型考虑了钻头在切削时主轴-钻夹头-微钻头系统的偏心、钻削轴向力、系统转动惯性力、陀螺力矩和轴承等因素对微弯曲变形的影响。利用该模型确定了钻头的危险截面,分析了钻头夹持长度、轴承刚度、轴承阻尼、主轴转速、系统偏心、钻削轴向力以及钻削扭矩等因素对危险截面应力的影响。最后提出了避免微小钻头折断的措施,可用于指导微小孔钻床的设计和生产实践。

Dynamic Stress Characteristic of High-speed Micro-hole Drill

Facing the problem of micro-drill snapping easily during drilling, a dynamic model of micro-drilling spindle system was built by using Timoshenko beam element according to rotor dynamics. The model included the effect of the eccentricity of spindle-clamp-drill system, the drilling thrust, the system rotating inertia, the gyroscopic moments, and the bearings on the bending deformation. The minimum life section was figured out by the model, and the influence of the fixed length of the drill, the stiffness and damping of bearings, the speeds of spindle, the system eccentricity, the drilling thrust, the drilling torque on the stress of minimum life section were performed. Several measure to avoid micro-drill snapping were proposed in micro-drill design and practice.