数控车床丝杠进给系统刚度对系统的失动量和定位精度影响较大。基于进给系统质量和弹簧力学模型，给出了进给系统轴向刚度和扭转刚度对失动量的影响与定位误差的解析表达式，为进给系统结构设计、降低系统的失动量和提高系统的定位精度提供了理论依据；结合实例进行了应用分析计算，取得了明显效果。

Rigidity of feed system with ball screw in NC lathe has a major influence on loss of momentum and positioning precision. Based on the spring mechanics model and the quality of the feed system, the analytic formulation for the effect of the transition and torsion rigidity of the feed system on the loss of momentum have been given. The analytic formulation for position error have been given, too. Theoretic basis for designing the structure, reducing loss of momentum and increasing positioning precision of feed system has been provided. Moreover, analysis and calculation have been made in combination with an actual example, and significant effect has been obtained.