Theoretical Research On The Interference Error And Cutting Force During The Whole Process Of Thread Milling

As a common mechanical connection,the thread has a simple structure,reliable performance,and easy disassembly.It is one of the indispensable structural elements in today’s mechanical equipment.With the popularization of multi axis NC machining technology in China,thread milling technology has been used more and more because of its own advantages in industrial manufacturing.However,due to interference errors and unstable cutting forces in the process of thread milling,the quality of threaded parts processing and the service life of thread milling cutters are affected.Therefore,how to establish an accurate and complete thread milling interference error model and a cutting force prediction model has become a key problem to be solved urgently in thread precision milling.In this process,feature point description method,envelope surface theory,space curve parameterization theory,metal cutting theory,UG NX11.0 software,DMU50 five-axis CNC machining center,JOHNFORD-VMC850 Vertical machining center,automatic image measurement platform,cutting force measurement and other methods are used.The specific research work is as follows:1)Definition of the profile parameters of the standard internal thread tooth.The processing principle and basic processing steps of thread milling are elaborated in detail;and the trajectory of thread milling cutter under different conditions is analyzed.These works provide theoretical foundation for the research of thread helical modeling.2)Establishment of interference error model for helical milling of threaded holes and cutting experiment verification.The two-dimensional plane feature point method is used to define the standard thread profile and thread milling cutter profile,respectively,to generate standard thread profile and thread milling cutter profile.Parametric equation of integrated tool path for helical milling is defined by using the parameterization theory of space curve.On this basis,according to the movement characteristics of thread milling cutters in the process of helical milling cut-in and cut-out process and machining process,the corresponding interference error calculation model is established.The correctness and effectiveness of the interference error model for threaded hole of helical milling are verified by experiments.3)Establishment of cutting force prediction model for helical milling of threaded hole and cutting experiment verification.This paper parametrically defines the geometry of the thread milling cutter.Aiming at the different machining stages of helical milling,a calculation method for the radial cutting depth of the thread milling cutter is proposed.The instantaneous cut-in angle and cut-out angle of each micro-element of the thread milling cutter are calculated to establish the instantaneous cutting thickness calculation model of the thread milling cutter.On this basis,the cutting force prediction model for threaded hole of helical milling cut-in process and machining process is established.The correctness and effectiveness of the cutting force prediction model for threaded hole of helical milling are verified by experiments.