The Unit Bolted Joints Static Feature Modeling And Research

The bolted joints are widespread in machine tool,and have a great effect on the performance fomachine tool.Therefor,studying on the characteristics of bolted joints has significance for the design of NC machine tool.In this paper,static characteristic model of the unit bolted joints is established which is based on the basic characteristic parameters of joints,and bearing rules ofthe bolted joints can be obtained.Through the static characteristic analysis model of unit bolted joints and the stiffness equivalent principle,provide a method for processing unit bolted joints in the machine tool static FEM.First of all.based on ABAQUS,the 3D model of the bolted joints is established.The basic characteristic parameters of joints are given to contact properties by subprogram.The deformation and pressure distribution of joints can he obtained by accurate analysis of joints.Secondly,regarding the unit bolted joints as the study aims,based on basic charactcristic parameters of joints,establish contact deformation equation of any point on joints and ensure constraint conditio ns of the joints displacement.The total reaction force and torque on the joints can be obtained due to the pre-loaiding and the static equilibrium equation of the bolted joints.And then,contact stiffness matrix of the bolted joints can be obtained.According to the thought of equivalent with four points,based on the symmetry ofstructure and bearing,stiffness equivalent model of the bolted joints is established by the force balance equation.The equivalent method significantly reduces the calculation of finite element software,and provides the method and datum in analyzing the bolted joints of machine tool.Finally,taking a NC machine tool for example,experiment with stiffness of the machine tool.And compared with the finite element analysis results,verify the feasibilky of bolted joints stiffness analysis and its equivalent method.