Study On Single Point Diamond Turning Technology Of ZnSe Crystal

Infrared technology is not only widely used in space field,but also has a very important position in national defense security and civil field.With the rapid development of modern military equipment,the researches on the characteristics of infrared optical materials and the corresponding processing problems of the optical components have attracted worldwide attention.At present,many kinds of infrared optical materials,such as Zinc selenide(ZnSe),have been able to conduct a more sophisticated manufacture by single point diamond turning in other countries.However,due to their important military scientific value,the process has highly security features.Although there are many units in our country engaged in the research on ultra-precision turning technology of ZnSe crystal materials,but in view of the lack of processing technology and processing experience,we have not yet obtained the ideal mirror processing effect.Therefore,we have to independently solve the key technical problems in ultra-precision machining about these materials,to explore novel diamond turning approaches which adapt to cutting process of the soft brittle polycrystalline materials like ZnSe crystals.The single point diamond turning process of ZnSe crystal material is researched in this paper.The major achievement is as following:Firstly,according to the material characteristic parameters of ZnSe crystal and the characteristics of single point diamond turning of brittle materials,the theoretical cutting model which reflects the actual three-dimensional processing characteristics is established.Based on the theory of "brittle-plastic coupling" and the simulation results of the model,the critical processing conditions of the mirror cutting about ZnSe crystal are explored,and the key problems such as minimum cutting thickness,"brittle-plastic transition" depth and critical undeformed chip thickness are explored.The critical parameter range about tool feed,cutting depth,tool front angle and tool nose radius is forecasted or optimized,which provides theoretical guidance for the following study.Secondly,the cutting simulation model which reflects the actual processing characteristics is established.The finite element simulation analysis of the turning process about ZnSe crystal is carried out.The influence of tool geometry parameters and process parameters on the cutting process and the surface quality is studied,and the brittle removal phenomenon of the workpiece is given a reasonable explanation.Finally,based on the priority of the process parameters obtained by the simulation analysis,the experimental scheme is designed to realize the further verification and analysis of the brittle material cutting model and the simulation results.And the effects of process parameters on the surface quality of ZnSe crystal were studied systematically.The relevant theory,simulation and experimental results are integrated to optimize the processing parameters to obtain the ideal ultra-smooth ZnSe crystal mirror.