Research On Key Technology Of Low Stress Assembly Of Linear Rolling Guide

Accuracy retention is an important performance index of CNC machine tools,and assembly stress is one of the key factors that affect the accuracy of retention.Based on the related engineering requirements of low stress assembly technology,this paper studies the stress generated during assembly process and the restraint method of system internal stress.The method is applied to the low stress assembly process of the linear rolling guide.The main work is as follows:Based on the Hertz contact theory,the contact state and the force of the roller in the slide block is analyzed.The relationship between the geometric error of the guide rail and the load of the roller is established.According to the structural features of the slide block,it is equivalent to the cantilever beam model and then the stress analysis model is established.The main stress measurement and calculation methods under the condition of linear stress and plane stress are expounded respectively.The finite element model of single bolt connection is established by using ABAQUS,and the stress distribution state of bolt connection is analyzed.The same method is used to establish the finite element model of the bolt connection between the bed and the guide rail,the slide block and the test plate.The stress distribution is analyzed when multiple bolts are tightened.The roller in the slide block is equivalent to a nonlinear spring and the integral finite element model is established.16 positions are selected as the key measurement points on the test plate and the slide block.The stress changes at key measurement points under different geometric errors of the guide rail are analyzed.The relationship between the geometric error and the stress is established by using BP neural network.The training samples of BP neural network are collected through orthogonal experiments,and then BP neural network is trained.In this paper,a method of establishing the mapping relationship between stress and geometric error by BP neural network is proposed to reduce the internal assembly stress in the system.Firstly,the stress measurement system is set up to measure the stress values at key measurement points.Then the measured stress is input into the BP neural network.According to the geometric error,the corresponding process method is adopted to reduce the internal stress of the system.The proposed method is verified by using the low stress assembly experiment table.The results show that this method can effectively reduce the internal stress of the linear rolling guide system.