数控机床主轴轴承动态精度研究

发布时间：2018-04-12 11:11

本文选题：角接触球轴承 + 动态精度　；参考：《河南科技大学》2015年硕士论文

【摘要】：数控机床是高端装备制造业的工作母机,随着科学技术的发展,机床正向着高精度化、高速化的方向发展。机床主轴系统作为整个机床的核心部分,其动态性能的好坏直接影响着机床的加工精度,轴承作为电主轴系统的重要支承部件,轴承的动态精度及其性能直接影响着主轴系统的稳定性和可靠性。为了提高高档数控机床的加工精度,需要对数控机床主轴轴承的动态精度进行分析研究。本文主要围绕机床主轴常用的角接触球轴承进行了动态精度研究,运用赫兹理论、套圈控制理论等滚动轴承的基本理论知识,以及滚动轴承动力学分析方法,对轴承的运动状态进行了分析,建立滚动轴承的力学模型,对轴承的载荷分布与变形之间的关系进行了研究,主要研究了预紧力和初始接触角对轴承变形的影响,分析了摩擦力矩产生的机理,推导了摩擦力矩和旋滚比的计算公式,研究了轴承的联合载荷、转速对轴承旋滚比的影响,探讨了这些参数对轴承磨损及动态精度的影响。通过分析计算得出轴承的原始接触角、曲率之间的关系;推导了滚动轴承轴向、径向位移变形公式,随着转速的升高,轴承的径向变形逐渐增大,轴承的轴向变形则减小,在同一转速时滚动轴承的径向变形量随着预紧力的变大而逐渐减小,轴向变形量随着预紧力的变大而变大;当滚动轴承的初始接触角较大时,轴承的径向变形量较大,径向刚度较小,轴承轴向变形量较小,其刚度较大。通过比较发现,轴承的旋滚比会随着转速的升高而逐渐增大;在载荷作用下,增加轴向力可以降低轴承的旋滚比。大的旋滚比将会加剧轴承磨损生热,不利于轴承精度的保持。在Hertz接触理论和轴承运动学的基础上,推导了滚动轴承非线性轴承力,建立了滚动轴承非线性振动的分析模型,分析了轴承的振动特性,研究了转速、阻尼、径向力及滚动体数目对轴承系统振动特性的影响,结果显示轴承系统的响应具有周期和非周期形式,增加滚动体个数和减小径向载荷,有利于提高轴承系统的动态精度。通过设计合理的结构参数和工况参数,保证系统的稳定性,提高轴承系统的动态精度。最后对某型数控机床主轴系统进行了试验研究。
[Abstract]:With the development of science and technology, CNC machine tool is developing towards high precision and high speed.The spindle system of the machine tool is the core part of the whole machine tool, and its dynamic performance directly affects the machining accuracy of the machine tool. Bearing is an important supporting part of the motorized spindle system.Bearing dynamic accuracy and performance directly affect the stability and reliability of spindle system.In order to improve the machining accuracy of high-grade NC machine tools, it is necessary to analyze and study the dynamic accuracy of spindle bearings of NC machine tools.In this paper, the dynamic precision of the angular contact ball bearings commonly used in machine tool spindle is studied, and the basic theoretical knowledge of rolling bearings, such as Hertz theory and ring control theory, as well as the dynamic analysis method of rolling bearings are used.The motion state of the bearing is analyzed, the mechanical model of the rolling bearing is established, the relationship between the load distribution and the deformation of the bearing is studied, and the influence of the preloading force and the initial contact angle on the deformation of the bearing is mainly studied.The mechanism of friction torque is analyzed, the formula of friction moment and rotation ratio is deduced, the influence of bearing joint load and rotational speed on bearing rotation ratio is studied, and the influence of these parameters on bearing wear and dynamic precision is discussed.The relations between the original contact angle and curvature of the bearing are obtained by analyzing and calculating. The axial and radial displacement deformation formulas of the rolling bearing are derived. With the increase of the rotational speed, the radial deformation of the bearing increases gradually, and the axial deformation of the bearing decreases.At the same speed, the radial deformation of the rolling bearing decreases with the increase of the pretightening force, and the axial deformation increases with the increase of the preloading force, and when the initial contact angle of the rolling bearing is large, the radial deformation of the bearing is larger.The radial stiffness is smaller, the axial deformation is smaller, and the stiffness is larger.By comparison, it is found that the rolling ratio of bearings increases with the increase of rotational speed, and the axial force can decrease the ratio of rotation to roll under load.Large roll ratio will increase the bearing wear heat, which is not conducive to the bearing accuracy.On the basis of Hertz contact theory and bearing kinematics, the nonlinear bearing force of rolling bearing is deduced, the analysis model of nonlinear vibration of rolling bearing is established, the vibration characteristic of bearing is analyzed, and the speed and damping are studied.The effects of radial force and the number of rolling bodies on the vibration characteristics of bearing system are discussed. The results show that the response of bearing system has periodic and aperiodic forms. Increasing the number of rolling bodies and reducing radial load can improve the dynamic accuracy of bearing system.The stability of the system is ensured and the dynamic precision of the bearing system is improved by designing reasonable structure parameters and working conditions parameters.Finally, the spindle system of a numerical control machine tool is tested and studied.
【学位授予单位】：河南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG659

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