【作者】 靳岚；

【导师】 芮执元；

【作者基本信息】 兰州理工大学 ， 机械设计及理论， 2021， 博士

【摘要】 大功率高速主轴系统具有功率大、速度高、轴颈尺寸大等特点。在高速运转时,离心力、轴承的摩擦生热更强。为获得良好的主轴系统动态特性,大功率高速主轴连接结构的装配参数设计与主轴系统动态特性的协同统一是需要解决的关键技术之一。本论文针对工作状态下的大功率高速主轴转子与轴承过盈连接界面的接触状态,从宏观尺度上,分析了集过盈量、离心力、热载荷、切削力等共同作用下的主轴转子与轴承过盈连接界面的接触机制,得到了转速、过盈量等因素对过盈连接界面接触特性,及其对主轴系统动态特性的影响规律;为进一步探究过盈连接界面的接触状态,从微观尺度上,分析了微凸体在接触变形三阶段的接触刚度和接触载荷分别与接触变形量的关系,探究了接触全域上的微凸体接触刚度和宏观过盈量的关联性。论文主要研究内容与结果为:(1)依据大功率高速主轴结构组成特点,运用厚壁圆筒理论和轴对称平面应力理论,分析了理想状态下的主轴转子与轴承过盈连接界面的接触状态。发现在相同过盈量的条件下,随转速的增大,主轴转子外径的径向变形、轴承内圈内径的径向变形、过盈连接界面的过盈减小量都在增大,而接触应力逐渐下降;在相同转速的条件下,轴承内圈内径的径向变形量、过盈连接界面的过盈减小量则都随着过盈量的增加呈线性递增,主轴转子外径的径向变形量递减。以上研究结果为分析工作状态下的主轴转子与轴承过盈连接界面接触特性奠定了理论基础。(2)针对由高速轴承摩擦生热产生的热效应影响接触界面问题,运用三维热弹性理论,构建了大功率高速主轴转子与轴承连接部件的热力耦合有限元模型,分析了在离心力、热载荷、拉刀力、切削力共同作用下陶瓷球角接触球轴承滚动体与滚道的接触特性、以及主轴转子与轴承过盈连接界面的接触特性及其影响。发现随着转速的升高,轴承滚动体与轴承滚道接触界面和主轴转子与轴承内圈连接界面的温度、接触应力、接触刚度随着转速升高而降低,且相互影响,同时,不同过盈连接部位,其界面接触特性也明显不同。上述研究结果为建立轴承刚度模型和大功率高速主轴动力学模型提供了相关数据。(3)基于主轴转子与轴承过盈连接界面接触特性与轴承滚动体和滚道接触特性的相互影响,而导致的轴承内圈滚道的径向耦合位移,建立了串联轴承的刚度模型,计算了组配形式为DTDB四列陶瓷球角接触球轴承刚度。同时,结合主轴转子与轴承过盈连接界面弹性刚度,构建了基于Timoshenko梁理论的大功率高速主轴动力学有限元模型;计算结果表明,主轴转子与轴承过盈连接界面的接触状态对主轴系统各阶固有频率、临界转速,以及回转精度等动态特性有一定的影响。这些结果为装配设计参数合理匹配大功率高速主轴的动态特性提供了理论依据。(4)针对过盈连接界面的微观接触状态与宏观过盈量的关联问题,构建了主轴转子粗糙表面与轴承光滑刚性表面的接触模型;运用统计理论解析了过盈接触界面上的单个微凸体以及接触全域上微凸体的弹性、弹塑性、全塑性变形,获得了接触全域上的微凸体接触刚度和宏观过盈量关系模型,发现在接触过程中,不同过盈量的取值范围可引起微观接触界面上不同的变形形式,且接触刚度随过盈量的变化符合微凸体受压变形的接触机理;通过建立的有限元微观接触模型,间接证明了,在接触全域上,微凸体的接触刚度和宏观过盈量之间的关系模型是正确的;过盈连接界面接触特性的微观研究为合理选择装配设计参数提供了理论支撑。论文研究结果为从过盈装配设计参数与动力学特性匹配的角度设计大功率高速主轴系统提供了基本思路,同时也为形成大功率高速主轴系统的精确设计技术提供了一定的理论支撑。更多还原

【Abstract】 High-power & high-speed spindles is famous for its remarkable features suchas large power,high speed and large journal size.The centrifugal force of spindles and thermal effect of the bearing is stronger in high-speed operation,so the coordination and unification between the assembly parameters and dynamic characteristics of spindle system is one of the key technologies in the process of structure design to be overcome.The problem about contact state of the interference contact surface between the rotor of the high-power & high-spindle and the bearing is discussed and studied under the working state in this thesis.From the macroscopic scale,the contact mechanism of contact surface between spindle rotor and bearing under the combined action of interference,centrifugal force,thermal load and cutting force was analyzed.The influence of rotational speed and interference on the contact characteristics of interference connection interface and the dynamic characteristics of spindle system was obtained.In order to further explore the contact state of interference contact surface,the relationship between contact stiffness and contact load of micro-convex body and contact deformation in three stages of contact deformation was analyzed from the microscopic scale,and the relationship between contact stiffness of micro-convex body in whole contact area and macroscopic interference was explored.The main research contents and results of this thesis are as following:(1)According to the structural characteristics of high-power high-speed spindle,the contact state of interference contact surface between spindle rotor and bearing inner ring under ideal condition is analyzed by using thick-walled cylinder theory and axisymmetrical plane stress theory.It is found that under the condition of the same amount of interference,the radial deformation of the outer diameter of the spindle rotor,the radial deformation of the inner diameter of the bearing inner ring,and the interference reduction of the contact surface of the interference increase with increasing speed,while the contact stress decreases gradually.At the same speed,the radial deformation of inner diameter of bearing inner ring and the reduction of interference contact surface increase linearly with the increase of interference,while the radial deformation of outer diameter of spindle rotor decreases.These results lay a theoretical foundation for analyzing the contact characteristics of interference contact surface between spindle rotor and bearing under working conditions.(2)Aiming at the problem that the thermal effect caused by the friction heating of high-speed bearings affects the contact interface,a thermal-mechanical coupling finite element model of the connecting parts of high-power high-speed spindle rotor and bearing was established by using the three-dimensional thermoelastic theory.The contact characteristics between the roller and raceway of ceramic ball bearing and the interference interface between spindle rotor and bearing under the combined action of centrifugal force,thermal load,broach force and cutting force are analyzed.It is found that the temperature,contact stress and contact stiffness of the contact interface between the rolling body and the raceway of the bearing and the interface between the spindle rotor and the inner ring of the bearing decrease with the increase of the rotational speed,and they affect each other.At the same time,the interface contact characteristics of different interference connection parts are obviously different.The above research results provide relevant data for the establishment of bearing stiffness model and high power high-speed spindle dynamic model.(3)The radial coupling displacement of raceway of bearing inner ring was caused,because of the interaction between the contact characteristics of interference contact surface between spindle rotor and bearing and the contact characteristics of rolling body and raceway of bearing.Based on this displacement,the stiffness model of series bearing was established,and the stiffness of four-row ceramic angular contact ball bearing was calculated.At the same time,the dynamic finite element model of high-power high-speed spindle based on Timoshenko beam theory was constructed by combining the elastic stiffness of interference contact surface between spindle rotor and bearing.The calculation results show that the contact state of interference contact surface between spindle rotor and bearing has certain influence on the dynamic characteristics of spindle system,such as natural frequency,critical speed and rotary accuracy.These results provide a theoretical support for reasonably matching the dynamic characteristics of high-power high-speed spindle with assembly design parameters.(4)Aiming at the relation between the micro contact state and the macro interference,a contact model of the rough surface of the spindle rotor and the smooth rigid surface of the bearing was established.By using the theory of statistical parsing the interference connection interface on a single micro convex body and contact on the whole domain of micro convex body elastic,elasticplastic and plastic deformation,the whole domain slightly convex body contact stiffness and the macroscopic interference quantity relation model,found in the process of contact,the different values range can cause of the over surplus quantity of the micro deformation of different form on the contact interface,The variation of contact stiffness with interference is consistent with the contact mechanism of microconvex deformation under compression.Through the finite element microscopic contact model established,it is proved indirectly that the relationship model between the contact stiffness of micro-convex body and the macroscopic interference is correct in the whole contact domain.The microscopic study of interface contact characteristics of interference connection provides theoretical support for reasonable selection of assembly design parameters.The results of dissertation would provide a basic idea for designing highpower& high-speed spindle system from the view of matching design parameters of interference assembly and dynamic characteristics,and also provide a certain theoretical support for forming accurate design technology of high-power& highspeed spindle system.更多还原