Investigation On Mechanism Of Precision Micro-cutting And Its Application Technology

Since miniaturization and high-precision have become a trend for global manufacturing technology, micro-machining methods with high-efficiency and high-precision become more and more important. As a kind of new micro-machining method, precision micro-cutting is based on conventional metal cutting theory and technology, and oriented to micro-structure with various materials in micro-systems.In this thesis, a series of micro-turning, micro-milling and micro turn-milling combined machining experiments have been carried out to aluminum alloy and brass respectively in the miniature turn-milling machining center. Micro cutting principle and mechanism, including size effect, non-free cutting theory, dislocation theory, cutting force characteristic and its influence factors, characteristic of vibration signal in micro end-milling process, characteristic of machining surface roughness and profile, micro-cutting processing were investigated. The main results were as follows:(1) Non-free cutting theory, size effect, dislocation theory are proposed to explain those complex micro phenomenon in precision micro-cutting. The rounded edge effect of cutting tool, and relevant negative rake angle and critical cutting thickness in precision micro-cutting was analyzed.(2) The principle of minimum cutting thickness was explained, and the analytical expression of minimum cutting thickness was derived by analyzing the force condition in cutting area.(3) An analytical cutting force model in micro end-milling considered the tool edge radius was predicted, and its cutting force characteristics were analyzed.(4) The characteristic of vibration signal in micro end-milling process were analyzed, which indicated that vibration in micro end-milling were related to feed rate, axial depth of cut and work-piece material which were originated from critical cutting thickness effect.(5) According to the machining ability of the miniature turn-milling machining center and the characteristics of micro-structure parts, the micro processing technological requirements and criterions in micro cutting was proposed, based on which some typical parts were produced.