轴承过盈配合量对主轴动力学特性的影响

摘要

为探索轴承配合过盈量在转速和温升等因素影响下的变化规律及对主轴系统动力学特性的影响规律,首先建立了考虑转速引起的内圈离心膨胀和温升引起的热位移轴承过盈配合模型,然后将过盈配合模型耦合进Harries轴承动力学模型,建立了考虑轴承配合的轴承动力学模型,并基于Timoshenko理论建立机床主轴系统有限元模型. 针对实验室自建主轴系统,进行了轴承配合过盈量对主轴动力学特性影响分析. 结果表明:轴承内、外圈初始过盈量增加,原始接触角线性减小;初始过盈量在温升及离心力的双重影响因素下会增大;初始过盈量、内圈离心膨胀及内外圈热膨胀会导致轴承刚度增大,轴承刚度增大导致主轴系统固有频率增加,相比较一、二阶固有频率,三、四阶固有频率受过盈量及其影响因素的影响较大.%It is necessary to explore the interference fit amount under the influence of rotational speed and the temperature rise and the rules of change of dynamic characteristics of spindle system. Considering the inner ring centrifugal expansion aroused by the speed and the thermal displacement caused by temperature rise, an interference fit model of bearing was established in this paper. Then the interference fit model was coupled into Harries bearing dynamic model, the bearing dynamic model was established with consideration of the interference fit, and based on the Timoshenko theory, a finite element model of machine tool spindle system was established. Conferred on the self-built spindle system in laboratory, the effect of interference fit impact on the dynamic characteristics of spindle was analyzed. The results show that the bearing inner and outer ring initial interference amount increases, and the original contact angle linear decreases; the initial interference fit amount under the influence factors of temperature and centrifugal force increases; the initial interference quantity and inner ring centrifugal expansion and thermal expansion leads to the bearing stiffness increase, and the increase of bearing stiffness leads to the increase of natural frequency of spindle system, and compared with the first and second order natural frequency, the degree of three and four order natural frequency affected by the factors is larger.