大型螺纹旋风铣床主传动系统轴向刚度的分析与研究

文章以大型螺纹旋风铣床的主传动系统为对象,并运用赫兹接触模型及相关理论,研究了主传动系统中丝杠螺母轴向接触刚度和支承轴承的轴向刚度与轴向负载的关系、丝杠轴及丝杠的扭转等效轴向刚度与负载作用位置的关系,并使用贡献比来评价主传动系统各组成部分对系统整体刚度的影响。计算结果表明:主传动系统整体刚度随轴向负载增加呈非线性增加,在丝杠中间处时系统整体轴向刚度值最小,且整体轴向刚度主要取决于轴承轴向刚度和丝杠轴的轴向刚度。其中,轴承刚度贡献比最大,为65%以上,丝杠轴的轴向刚度贡献比小于31%,而丝杠螺母接触和丝杠扭转引起的轴向刚度的贡献比非常小。因此提高轴承轴向刚度是提高大型螺纹旋风铣床主传动系统刚度的关键。

Analysis and Study on the Axial Stiffness of Main Transmission System for the Large-Scaled Screw Thread Whirlwind Milling Machine

In this paper,Taking the main transmission system of the large-scaled screw thread whirlwind milling machine as the research object,and using Hertz contact model and related theory,we study the relationship between the axial load and the axial contact stiffness of the ball screw assembly and supporting bearing axial stiffness,relationship between the axial load location and the screw shaft axial stiffness and screw’s torsion equivalent axial stiffness,that composing the main transmission system.In order to evaluate the effect of each component to whole axial stiffness of the main transmission system,the contribution ratio concept was used.The calculation results show that: Main transmission system whole axial stiffness was nonlinearly increased with load increasing,to be minimum at the middle position of the screw,and that largely depend on the axial stiffness of the supporting bearing and the screw shaft.The contribution ratio to the whole axial stiffness of the bearing is above 65%,and the screw shaft is about 31%.Obviously,the contribution ratio caused by ball screw assembly contact deformation and screw shaft torsion is extremely small.Therefore increasing bearing axial stiffness is the key point to improving the stiffness of main transmission system of the large-scaled screw thread whirlwind milling machine.