Analytical Prediction Of Tool Point Frequency Response Function Of Spindle-holder-tool Assembly And Verification

In recent years,high speed cutting technique has been used more and more widely with the development of machine-tools.However,in the process of high speed cutting,chatter results in poor surface quality,and damage on the tool itself,which seriously restricts the applications of high speed cutting technique.Stability lobe diagrams can be used to avoid chatter,the main requirement for generating the stability lobe diagrams is the tool point frequency response function of the spindle-holder-tool assembly.Experimental modal analysis can be performed to obtain the tool point FRF.However,since the frequent changes of the tool and holder,a large number of tests are needed.Repeated hammer tests are not only time-consuming but also will bring errors,which seriously reduce the efficiency of manufacturing.The tool point FRF can also be obtained accurately by using analytical methods,and the number of hammer tests can be reduced considerably.Therefore,it is necessary to use the analytical methods to predict the tool point FRF of the spindle-holder-tool assembly.The main research contents are given as followings:Firstly,hammer tests were performed for studying the effects of the tool clamping length between the tool and spindle-holder assembly on the tool point FRF,in order to provide an experimental basis for modeling the FRF of the system accurately;Secondly,RCSA is a simple method which can predict the FRF of systems effectively.In the thesis,the FRF of the spindle-holder-tool assembly was modeled analytically by using RCSA method.First,the spindle-holder-tool assembly was divided into 3 substructures: spindle-holder-base,extended holder and tool;Then,Timoshenko beam theory,finite element method,hammer tests,finite difference method and reverse RCSA method were used to determine the FRF of each substructure;The spring-damping model was employed to simulate the flexible coupling between the spindle-holder assembly and tool,and the least squares fitting was used to determine the parameters of the spring-damping model;Finally,considering the influence of the tool clamping length,the FRF of the each substructure was coupled rigidly or flexibly to obtain the tool point FRF of the whole spindle-holder-tool assembly;Finally,hammer tests were performed again to verify the proposed analytical models of the FRF of the spindle-holder-tool assembly.HSK spindle-shrink fit holder-tool assembly was used to verify the validity of the analytical models of each substructure and the whole spindle-holder-tool assembly.