Determination And Quick Selection Of Milling Parameters Of The Gantry Machine Tools Based On Analysis Of Static And Dynamic Characteristics Of Milling Head

As the main processing equipment,CNC machine tools are widely used in modern manufacturing industry.And the milling head that can expand the scope of the applications of machine tools is the most commonly used functional component of gantry machine tools.It is of great significance to select suitable cutting parameters of gantry machine tools after that have been equipped with milling heads in improving the processing accuracy,reducing tool wear and ensuring the machine tools' overall rigidity.But current study on cutting parameters of machine tools with milling head is shortage.Based on the current cutting parameters of the gantry machine tools,the relationship between the milling head's static and dynamic characteristics and the cutting parameters is studied through the combination of theory,simulation and experiment.The rapid selection of cutting parameters of gantry machine tools after using milling heads is realized by human-computer interface.(1)The empirical model of milling forces is established using orthogonal test method.It analyzes the basic principles,the purposes and the conditions of the milling orthogonal test.Using dynamometer to collect milling forces corresponding to different cutting parameters under four conditions: indexable end mills milling of HT300 grey cast iron,face mills milling of HT300 grey cast iron,indexable end mills milling of hardened cast iron and face mills milling of hardened cast iron.The empirical formulas of cutting parameters and milling forces in different directions are established by using the multiple linear regression technique.The accuracy of milling force models is demonstrated by methods of variance analysis and numerical comparison.(2)The relationship between the static characteristics of the milling head and the cutting parameters is studied by combining finite element simulation and experiments.The mechanical structure of the long milling head and the right-angled milling head is analyzed.According to the force distribution during the operation of milling head,it infers that components of milling force which have the greatest impact on the accuracy of the long milling head and the right-angled milling head are Fx and Fz,respectively.The finite element software is used to solve the static deformation of the milling head under different milling forces.The relationship between the maximum static deformation of the milling head and the cutting parameters is obtained by numerical simulation.A static test program for milling heads is designed to measure the deformation of the milling heads under the corresponding static loads.And the relationship between static deformation and cutting parameters is furtherly modified by comparing test results with simulation results.(3)The relationship between the dynamic characteristics of the milling head and the cutting parameters is studied by combining theoretical calculation and finite element simulation.According to the principle of energy conservation,the expression formula of the natural frequency of the structure is deduced.It uses the finite element software to solve the first six natural frequencies and modes of long milling head and right-angled milling head,which ensure that the milling head will not resonate within the rated rotation speed.According to the steady-state forced vibration theory,amplitude expression of the structure is deduced,and the harmonic response analysis of the milling head is taken to obtain its amplitude under certain processing conditions.Then,compare the simulation results with deduced results.Taking the milling force as the exciting force as well as combining the mass and the rigidity of milling head,the relationship between the amplitude of milling head and the cutting parameters is obtained.(4)Rapid selection of cutting parameters of a gantry machine after using milling heads is achieved through a computer program.Using C# program,the relationship between cutting parameters and milling force,static deformation of milling head,dynamic characteristics of milling head are converted into computer language,which ensure that human-computer interface that can select cutting parameters is made successfully.The machining test proves that the method described in this paper has great advantages in improving the machining quality of the gantry machine with accessory milling head.When the cutting parameters of gantry machine tools is selected,taking the static and dynamic characteristics of milling heads into account is beneficial for ensuring the overall performance and improving the machining accuracy of machine tools.The method described in this paper will be to fill the gap in an area of cutting parameters selection after using the milling head.Also,it is of great practical significance for guiding the actual production.