Process Basis And Experimental Research Of Fused Silica In Ductile Regime Micromilling

With the energy crisis being spotlighted, the importance of the nuclear fusio n energy has been noticed, and the research of inertial confinement fusion(ICF) has become more and more popular worldwide. Optical material fused silica has been largely used in the finial optical assembly(FOA) of ICF for its excellent optical performance and stable chemical property. However, damage caused by laser beam with high energy may happen on the surface and subsurface of fused silica, where mit igation measure usually been taken on fused silica in a certain range of damage scale. High flexibilit y and controllable profile are demanded for the mit igat ion method because o f the complexit y of damage profile and the role of damage in modulat ing the following light field. Thus, micromilling method with ball end mill is suitable in mit igat ion of damage caused by laser on fused silica.It is shown that the study of the mechanical properties of fused silica is of great importance in achieving the ductile regime micromilling by init ial research of the project, because of it is hard and britt le feature. According to the indentation experiment, key parameters of mechanical properties, the Vickers hardness and the fracture toughness, are measured and calculated, and the britt le-duct ile transit ion crit ical load of fused silica is predicted based on the indentation experiment. Based on the ruling experiment, the britt le-duct ile transit ion crit ical width, crit ical depth and crit ical ruling force are measured and calculated, and the influence on the crit ical values by variation of feed rate is analyzed, which provides a reference for the setting o f process parameters.The difference between the establishing condit ion of the classical calculation model of the brittle-duct ile transit ion crit ical thickness and the minimum chip thickness theory and the experimental condit ion in micro milling of fused silica wit h micro ball end mill is analyzed, and limitations of the former two theory applying in this pro ject is proved. The influence on the maximum undeformed chip thickness by variation of process parameters is researched, and the change rule of the milling forces in processing over variation of process parameters is analyzed. By single factor experiments, the influence on the qualit y of machined surface by variation ofprocess parameters is summarized, and the range of process parameters in which ductile regime micromilling of fused silica can be achieved is predicted.Confirmatory exper iment is implemented, from which high qualit y machined surface wit hout brittle crack is obtained. Other factors which may influence the processing qualit y in experiment are explored.The standard of choosing cutters for the ductile regime micromilling of fused silica is clarified. The stages and corresponding phenomena of cutter wear is observed and analyzed, from which the main form, the mechanism and the causes o f cutter wear is summarized. The influence on cutter wear by the variation of process parameters is analyzed, and feasible proposals and measurements reducing cutter wear are put forward.