润滑导轨结合面的刚度建模与等效间隙模型研究

发布时间：2018-11-03 14:14

【摘要】：机械零件表面并非绝对光滑面是具有一定形式的粗糙度,当两个表面接触时是表面间的较高微凸体发生接触。润滑导轨结合面在细、微观尺度上是流体润滑与微凸体接触共存的状态。目前关于结合面微凸体的研究大多建立在球形或者椭球形假设上,而且取得了相关的研究成果。但是对于磨削、刨削等加工产生的圆柱形微凸体的研究相对较少,大多停留在单个微凸体的弹性接触阶段。结合面间润滑油的存在可以有效地改善其稳定性,在接触分析时不应该忽略润滑接触过程中油膜的影响。因此,基于圆柱微凸体模型综合考虑弹塑性接触变形和润滑因素,建立更加完善的动力学接触模型,研究结合面的接触及油膜刚度特性,对机床动、静态特性的分析与结构优化设计都具有重要的理论意义与工程价值。以机床润滑导轨结合面为研究对象,通过理论模型推导、数值分析、有限元分析与实验分析相结合的方式对结合面接触特性进行对比和研究,主要工作内容如下:(1)基于圆柱微凸体在弹性、弹塑性和塑性变形阶段的接触特性和Tresca屈服条件,推导了适用范围更广的综合考虑三个阶段接触变形影响的法向和切向接触刚度模型。并使用MATLAB软件对模型进行数值仿真分析,研究了微观条件下结合面分形维数、分形幅度系数和法向载荷对接触刚度的影响。(2)综合考虑润滑因素的影响,运用弹流润滑理论、平均流动的广义Reynolds方程与部分膜润滑方程,建立了基于串并联结构的考虑入口油膜刚度、接触区油膜刚度和接触区法向刚度的综合刚度模型。(3)基于表面微观形貌具有自相似特征,利用TR200型手持式粗糙度仪测定了滑块-导轨结合面的分形维数、分形幅度参数,为研究表面微观形貌对构件固有频率的影响提供真实数据,并得出所推导综合刚度模型的理论计算值。(4)通过滑块-导轨实验平台模态实验对结合面的刚度模型进行验证。基于单自由度系统结合面的单位面积等效刚度识别方法,获取单位面积的等效刚度,验证导轨结合面的数学模型。动态刚度试验采用单因素法,分析滑动速度、面压、有无润滑油等各因素对滑动结合面动刚度的影响规律;对比干摩擦和润滑状态,分析润滑油膜在结合面刚度中的贡献。(5)从宏微观相结合的角度出发,重构结合面为“固-等效间隙层-固”模型,将结合面等效为一种虚拟材料。基于本文前期推导的刚度公式,由外力所做的功和模态应变能等效的方法,得出等效间隙层材料参数,并进行有限元预应力模态分析。最后结合实验完成了对导轨结合面等效间隙模型的验证。
[Abstract]:The surface of mechanical parts is not absolutely smooth and has a certain form of roughness. When two surfaces are in contact with each other, the higher convex surfaces are in contact with each other. The interface of lubricating guideway is the coexistence of fluid lubrication and microconvex contact on fine and micro scale. At present, most of the researches on the microconvex body of bonding surface are based on the spherical or ellipsoid hypothesis, and some related research results have been obtained. However, the research on cylindrical microconvex produced by grinding, planing and other machining is relatively few, and most of them stay in the elastic contact stage of single microconvex. The stability of interfacial lubricating oil can be improved effectively, and the influence of oil film in lubrication contact process should not be ignored in contact analysis. Therefore, based on the consideration of elastoplastic contact deformation and lubrication factors, a more perfect dynamic contact model is established, and the contact and oil film stiffness characteristics of the interface are studied. The analysis of static characteristics and structural optimization design have important theoretical significance and engineering value. In this paper, the contact characteristics of the lubrication guideway of machine tool are compared and studied by theoretical model derivation, numerical analysis, finite element analysis and experimental analysis. The main work is as follows: (1) based on the contact characteristics and Tresca yield conditions of cylindrical microconvex in elastic, elastoplastic and plastic deformation stages, The normal and tangential contact stiffness models with a wider range of applications considering the effects of contact deformation at three stages are derived. The influence of fractal dimension, fractal amplitude coefficient and normal load on contact stiffness is studied by using MATLAB software. (2) the influence of lubrication factors is considered synthetically. Based on the elastohydrodynamic lubrication theory, the generalized Reynolds equation of average flow and the partial film lubrication equation, the stiffness of the inlet oil film is established based on the series-parallel structure. The integrated stiffness model of oil film stiffness and normal stiffness of contact zone. (3) based on the self-similarity of the surface morphology, the fractal dimension and fractal amplitude parameters of the slider-guideway joint surface were measured by TR200 hand-held roughness instrument. In order to study the influence of the surface microtopography on the natural frequency of the component, the theoretical calculation value of the derived comprehensive stiffness model is obtained. (4) the stiffness model of the combined surface is verified by the mode experiment of the slider-guide-rail experimental platform. Based on the method of identifying the equivalent stiffness per unit area of the single degree of freedom system, the equivalent stiffness of the unit area is obtained, and the mathematical model of the guide rail joint surface is verified. The single factor method is used to analyze the influence of sliding speed, surface pressure and lubricating oil on the dynamic stiffness of sliding joint. Compared with dry friction and lubrication, the contribution of lubricating oil film to the stiffness of bonding surface is analyzed. (5) from the point of view of macro and micro combination, the model of "solid-equivalent clearance lamella-solid" is reconstructed. The bonding surface is equivalent to a virtual material. Based on the stiffness formula derived earlier in this paper, the equivalent gap layer material parameters are obtained by the method of equivalent work and modal strain energy done by external force, and the finite element prestressing modal analysis is carried out. Finally, the equivalent clearance model of the guide rail joint surface is verified by experiments.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG502

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