The Dynamic Characteristics Of Typical Mechanical Joint Surface And Its Application

Mechanical Joints are natural structure of all Mechanical System.When be loaded with force,it behave complex dynamical characteristic with damping and elasticity and affect so much dynamical characteristic of Mechanical System.Take the Machine Tools as an example,It is proved that damping and elasticity of machine tool's Joints is greater than Mechanical structure themselves',so Joints affect dynamical characteristic of Machine tools very much.The facts show that in dynamic mechanical design,the availability of reasonable combination of kinetic parameters, as well as its own mechanism and the role of reasonable characterization of the dynamic characteristics is the key to establish accurate dynamic model of the mechanical structure.Therefore,the study of the dynamic characteristics of the mechanical Joints is of great significance.The research of Joint can be divided into macro research and micro research.Macro research generally use springs and dampers model to simulate Joint and establish the vibration system model.Micro research generally gets the characteristics of the Joint through the testing and analysis of the deformation of physical mechanism and damping characteristics of the Joint.This thesis is a part of the application of Yunnan Province basic research projects "Theory and applied research of dynamic characteristics of the mechanical Joints". Based on the studies at home and abroad,in view of the mechanical Joints characteristics in the mechanical Structure,the dynamic characteristics of typical mechanical Joints of the bolts were studied.The 12 fixed spring-damping model were applied to build the Joints model,finite element analysis and experimental modal were used to identify equivalent parameters of the mechanical Joints.Analyze the effects of different surface roughness and different pressure and different size to the Joints' characteristics,by studying the mechanical Joints' dynamic characteristics of different surface roughness and different pressure and different size.Through the data,we know that stiffness and damping of the Joints decreases with the surface roughness increases and increases with pressure increases and increases with increases,but not strictly proportional to the size increase.Classical theory is used to derivate the formula of the normal direction stiffness and tangent direction stiffness when the single Micro-convex contact with each other in this paper.Analyze and explain the impact of external conditions to the stiffness through the rough surface's Micro-convex contacts.Then a detailed introduction and summary of the mechanical Joints damping mechanism was given.And the impact of external conditions to the damping is analyzed and explained.The fundamental purpose of studying the Joint's characteristics is engineering applications.In this paper three-dimensional modeling software SolidWorks and finite element analysis software ANSYS are used to study the reality Joints in the XK8150 CNC milling machine based on ji-cun-yun-xiao method.Compared with the different modal shape of XK8150 when considering the Joints and not considering them.It provides the reference for us to further enhance the accuracy of the computer simulation of the mechanical structure.