Research On The Prediction Method Of Preload Degradation Of Rolling Linear Guide Pai

In order to improve the bearing capacity,dynamic characteristics and reliability of the machine tool feed system,different degrees of preload should be applied to the linear rolling guide in most applications.However,due to the lack of a clear definition,calculation and prediction method of preload,the existing research only divides the rolling linear guide pair into three grades:light preload,medium preload and heavy preload.With the rapid development of CNC machine tools,this rough classification method is increasingly unable to meet people’s demand for high precision,high reliability and intelligence of linear rolling guide.Therefore,this article is supported by the National Natural Science Foundation of China（51905274）.Firstly,the preload of the linear rolling guide is clearly defined.Then,the accurate calculation method of the preload of the linear rolling guide,the calculation method of the wear area and other parameters related to wear are studied theoretically and experimentally.Finally,the preload degradation prediction model of the linear rolling guide is established,and the preload degradation prediction software is developed.The specific research contents are as follows:（1）According to the characteristics of the preload of the ball screw,this paper first defines the resultant force of the normal force of the upper（or lower）roller in the vertical direction as the preload in the linear rolling guide,and then constructs the synchronous online measurement system of the preload and the external load of the linear rolling guide,and measures the friction coefficient under different preload and rotational speeds.On this basis,the accurate calculation method of preload in the wear degradation process of linear rolling guide is proposed,which establishes the foundation for the verification of the prediction model of preload degradation.（2）Different from the traditional Hertz contact theory,the contact shape between the roller and the raceway is regarded as a complete contact ellipse.In this paper,the traditional MB fractal contact theory is improved by considering the surface contact form and density distribution function of the linear rolling guide from the microscopic point of view,and the microscopic contact mechanics model of the linear rolling guide is further established.The improved calculation method of the wear area of the linear rolling guide is proposed.（3）The five-dimensional load on the linear rolling guide,the deformation and displacement of the sliding block under the load,the change of the indirect contact angle between the rolling element and the raceway,and the sliding motion of the rolling element during the movement are comprehensively analyzed.The geometric correction coefficient′₉′4))is introduced to consider the intermittent reciprocating contact between the rolling element and the raceway during the movement.Combined with the micro contact mechanics model,the multi-scale prediction model of the preload degradation of the linear rolling guide is established.A series of tests were designed to verify the model,and the effects of vertical external load₍（1）,operating speed(1,fractal dimension D and characteristic scale parameter G on the preload degradation rate were analyzed.（4）Based on the Matlab GUI development tool,a convenient and easy-to-use human-computer interaction interface is designed,and the information database of the main components of the linear rolling guide is constructed.The model is algorithmized,and the prediction software of the preload degradation of the linear rolling guide is developed.The rapid calculation of the wear depth of each row of the linear rolling guide and the rapid prediction of the preload degradation are realized.