| Ultra-precision machining technology,a high precision machining technology,can obtain sub-micron level of shape precision and nano level of surface precision products.It mainly applied in nuclear energy,integrated circuits and aerospace and other high-end science and technology fields.Ultra-precision milling is a kind of ultra-precision machining technology.It is the most widely used machining technology in ultra-precision machining such as turning,grinding and flying cutting.It has excellent three-dimensional machining ability and is often used in the machining of small parts and complex structures.Research on cutting mechanism of ultra-precision milling is an important process to improve machining stability,and it can improve machining quality,reduce machining cost,prolong tool life and optimize milling parameters.In this paper,theoretical modeling and experimental research are carried out for ultra-precision milling force of single point diamond ball milling cutter.The main content is summarized as follows:(1)Modeling of milling force.The geometric shape and motion of milling cutter are described mathematically,and the transformation equation of dynamometer signal to milling edge coordinate system is derived,and the contact area between cutter and workpiece is modeled by solid model method and Z-map method respectively.Based on the research and analysis of tool contact model,the ultra-precision milling force model based on high speed milling force model and considering the force of milling cutter sphere was established.(2)Solution of milling force model.Firstly,ABAQUS finite element simulation software was used to determine the relationship between the minimum milling thickness of brass and the cutting edge radius.Then,MATLAB programming was used to simulate the pose changes of the cutter and workpiece in the milling process,and the instantaneous milling thickness of the milling edge and the sphere was obtained.Finally,the force of cutter in milling process is studied,and the finite simulation method and average milling force method are used to solve the milling force coefficient.(3)Experimental study on milling.The results of the spherical milling force coefficient and the milling force coefficient in the plastic zone of the milling edge were obtained through several groups of milling force measurement tests.The milling force prediction model is compared with the milling force measured by experiments and there is good consistency between the two.To sum up,the ultra-precision milling force model established in this paper,combined with the cutter contact model and high-speed milling force model,and realized the accurate prediction of the force variation trend of the single penalty cutter in the ultra-precision milling process.It has certain reference value for researchers to model milling force in the future and is beneficial to further study of ultra-precision cutting mechanism. |
