车削氟金云母陶瓷脆性破碎机理及表面粗糙度模型

基于脆性断裂力学和刀具-工件干涉原理，研究氟金云母陶瓷脆性破碎机理及表面成形机制，预测了脆性材料车削中的裂纹扩展角度与深度;建立氟金云母陶瓷车削表面粗糙度理论模型，用以评价精密车削陶瓷表面质量并提高加工效率.脆性材料车削表面粗糙度由几何干涉粗糙度和脆性崩碎粗糙度构成.刀具几何形状和进给量主要影响几何干涉粗糙度，工件力学性能、切削速度、切削深度和切削力主要影响脆性崩碎粗糙度.验证实验结果表明，氟金云母陶瓷车削表面粗糙度随切削速度的增大而减小，随进给量或切削深度的增大而增大.本模型的理论预测值与实验结果趋势一致，与传统的几何模型相比更接近实验值.

Brittle Fracture Mechanism and Surface Roughness Model in Turning Fluorophlogopite Ceramics

The brittle fracture mechanism and surface formation mechanism are studied based on brittle fracture mechanics and tool-work piece interference principle in turning fluorophlogopite ceramics. The crack propagation angle and depth are predicted. The theoretical model of turning surface roughness is established to evaluate the surface quality of precision turning fluorophlogopite ceramics and improve the machining efficiency. The surface roughness in turning brittle materials consists of kinematical-geometrical roughness and brittle fracture roughness. Kinematical-geometrical roughness is mainly affected by tool geometry and feed rate， while brittle fracture roughness is mainly affected by cutting speed， cutting depth， cutting force and mechanical properties of ceramics. Experiment results show that surface roughness increases with the increase of feed rate and cutting depth， while decreases with the increase of cutting speed. Compared with the traditional geometric roughness model， the theoretical values of brittle model are closer to the experimental results， and theoretical values and experimental trends are identical.