Investigation On The Dry Gas Seal Theory And Rotational Error Detection Of The Spindle For CNC Machine Tools

With the implementation of the 2025 major strategies in China,the machinery manufacturing industry will usher in a more rapid development opportunity,which puts forward higher requirements for the intelligence and machining accuracy of CNC machine tools.The spindle system is one of the key functional components of CNC machine tool,and its rotary precision is the key to ensure the precision of machine tool manufacturing.As a non-contact mechanical seal,dry gas seal has the advantages of low wear,low heating and high reliability compared with the common contact seal in CNC machine tools.Therefore,the theoretical research on dry gas seal of NC machine tool spindle is of great significance.In this paper,based on the fluid dynamics theory,the numerical simulation for gas film face seal spiral groove dry gas,analyzes the influence of structure parameters on sealing performance;a spindle error mathematical model based on the nonlinear least squares method,at the same time using the laser displacement sensor to test and analysis the cause of the error.The specific research contents are as follows:(1)Analysis of the working principle of spiral groove dry gas seal,compares several typical structural characteristics of spiral groove dry gas seal,completed a spiral groove dry gas seal structure design;based on the fluid dynamics theory,on the basis of the sealing cavity lubrication film flow characteristics put forward reasonable assumptions of dry gas flow,a fluid dynamic model of dry gas lubricating film.(2)To set the boundary condition and mesh using Gambit function,establish 3-D finite element model of spiral groove movable ring and the static ring lubrication film;numerical calculation of flow field between the end with Fluent,obtained the contours of pressure lubricating film,analysis of typical characteristics of dry gas lubrication;the dry gas sealing performance evaluation index structure,Matlab calculation program,the finite element calculation results were processed by the seal opening force,structure of the gas film stiffness and leakage rate and other performance parameters,analyzed the influence of helix angle,spiral groove,groove width,groove ratio,dam the groove depth film thickness ratio and other structural parameters on opening force,gas film stiffness and leakage rate,determine the range of sealing structure parameters.(3)Based on HTC2050 CNC machine as the research object,by using the non-contact laser displacement sensor to the spindle jump experiments were carried out;based on the nonlinear least squares method,the Matlab program for the preparation of test data processing,separation of turning period jump and residual;The L-M method is used to fit the data,and the spectrum of the fitting data is obtained by FFT algorithm.The residual spectrum is mainly the 1/2,2,and 3 frequency doubling rate of the spindle rotation frequency.The causes of the errors in different positions and different rotational speeds are analyzed.