【作者】 孙青；

【导师】 卢泽生；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2010， 硕士

【摘要】 随着科学技术的发展,功能、结构复杂,可靠性高的微小型产品需求不断增加,微细铣削技术作为实现产品微型化的主要技术而被广泛关注。但是,传统的微细铣削技术在加工硬脆材料等难加工材料时刀具磨损很快,加工表面质量不高,最终导致零件的使用性能达不到要求。超声振动微细铣削和传统微细铣削相比,具有能显著降低切削力、提高加工表面质量并延长刀具使用寿命的优点。其中残余应力作为表面质量的重要指标,是影响零件使用性能的主要因素,因此对超声振动微细铣削的残余应力进行研究具有重要的意义。本文针对这个问题,以降低残余应力为目标,利用有限元法对超声振动微细铣削残余应力随各影响因素的变化规律进行了系统的分析研究。本文分析了国内外超声振动切削技术和切削加工残余应力的研究现状,并总体阐述了残余应力的产生机理、影响因素及其对零件性能的影响。在分析前人所建立模型不足之处的基础上,使用有限元软件ABAQUS,建立了适用于超声振动微细铣削的二维有限元模型,并通过切削实验验证了模型的正确性,结合该模型对超声振动微细铣削的断屑功能和断续切削机理进行了分析。采用所建立的二维有限元模型,对超声振动微细铣削表面残余应力进行了仿真研究,分析了工件材料、刀具几何参数、振动参数和切削用量对已加工表面残余应力的影响规律,并结合残余应力的产生机理和超声振动微细铣削的特点探讨了产生这些规律的原因。建立并验证了超声振动微细铣削的三维有限元模型,采用该模型进行了表面残余应力的正交仿真研究,给出了各个工艺参数对残余应力影响的主次顺序,得到了残余应力的回归方程。通过三维仿真研究了超声振动微细铣削和传统微细铣削的残余应力沿已加工表面深度方向上变化规律的不同,并采用和仿真相同的工艺参数进行了槽铣实验,用X射线衍射法测定了残余应力,实验结果和仿真结果一致。更多还原

【Abstract】 With the development of science and technology,the demand for micro products with high reliability and complicated functions and structures are continuously increas-ing, and micro-milling is extensively concerned as a main way of achieving miniaturi-zation. However, owing to the fast tool wear and low surface integrity, the parts proc-essed by conventional micro-milling (CMM) especially out of hard and brittle materi-als often cannot achieve the performance requirements. Compared to conventional mi-cro-milling, ultrasonic vibration assisted micro-milling (UVAMM) can significantly reduce the cutting force, enhance the surface integrity and extend the tool life. While as an important indicator of surface integrity, residual stress (RS) is the main factor which influences the performance of parts. Thus, it is very necessary to study the RS in UVAMM. The object of the thesis is performing a research on the influences of vari-ous factors on the RS in UVAMM in detail, and finally finds a way to reduce RS.A summary is made to the mechanism of RS, the factors that influence RS, and the influences of RS on the performance of parts.A 2D finite element model is especially established for UVAMM using ABAQUS. The model is verified via milling experiment. With the help of the estab-lished model, the chip-breaking function and interrupted cutting mechanism of UVAMM are analyzed.Simulation of the surface RS in UVAMM is carried out with the previously estab-lished 2D model. The influence rules of workpiece material, tool geometric parameters, ultrasonic vibration parameters and cutting parameters on surface RS are analyzed. In-terpretations are made with the mechanism of RS and the features of UVAMM.A 3D finite element model of UVAMM is established and verified, with which orthogonal simulation is carried out. The importance order of process parameters is obtained, and the regression equation of RS is gained. A research on the difference of RS variation with the depth from the machined surface between UVAMM and CMM is putted into practice with the established 3D model. Slot-milling experiments are im-plemented using the same process parameters as simulation, and the RS is measured with the method of X-ray diffraction. The results of simulation and experiment are in good agreement.更多还原