关键词: 机械设计, 钻头, 钻床, 应力分析, 微小钻头, 动态应力, 转子动力学, 微小孔钻床

Abstract: 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.

Key words: mechanical design, drills, drilling machines, stress analysis, microdrills, dynamic stress, rotor dynamics, microhole drilling machines