【作者】 贾莹；

【导师】 龚俊；

【作者基本信息】 兰州理工大学 ， 机械制造及其自动化， 2010， 硕士

【摘要】 拉镗机床是加工深孔零件的重要设备之一。在深孔镗削过程中,被加工工件的质量取决于机床的加工精度,然而由于深孔加工特殊的加工环境,镗杆尺寸和形状都要受到一定的限制,造成刀具直径小、悬伸长、刚性差,易产生振动,这将严重影响加工质量。所以如何减小镗削过程中的振动已成为迫待解决的问题。本文研究镗杆的切削过程,所选用镗杆的长径比为50(L/D=4000/80)。建立镗杆系统动力学方程,在此基础上利用软件ANSYS对方程进行精确求解,分析镗杆的静、动态力学性能,并对镗杆结构进行优化,具体包括：首先对镗杆振动系统做了理论计算分析,建立拉镗镗杆在镗削时的简化受力模型,并在此基础上对镗杆在镗削过程中可能产生的各种振动形式的运动方程进行简化推导。其次分析切削角度,切削力以及镗杆弹性支撑的弹性系数对镗杆振动系统的影响。分别建立镗刀切削角度的数学模型；对镗头做静力分析；推导系统的耦合微分方程,求出引起该系统产生自激振动的条件,以及它与弹性支撑刚度的函数关系。再次利用有限元分析软件ANSYS对整个镗杆系统做静力分析,确定镗杆出现应力集中的位置,并对镗杆的强度和刚度进行校核；对镗杆结构的动态特性进行研究,通过模态分析得到前10阶固有频率及振型图,并对结果进行分析,在此基础上做谐响应分析,得出镗杆在受到外界激励的作用下,产生共振的频率,再通过瞬态分析,得到镗杆在开始和结束镗削时的瞬态动力响应。最后利用ANSYS参数设计语言对镗杆进行参数化建模,以空心镗杆截面内径为设计变量进行优化,得出最优解。更多还原

【Abstract】 Pulling boring machine is one of the most important equipment to manufacture deep hole parts. The quality of work piece is depended on machining accuracy of tool, but the special machining environment restrains boring bar’s size and shape which needs small diameter and long extended length, that makes boring bar’s rigidity weak, then it is easy to vibration in the processing, and affect machining quality seriously, so how to reduce the vibration becomes a critical issue needed to resolve.The object of study in this paper is the boring bar whose draw ratio is 50. In order to study on the cutting process of boring bar, it is need to create a dynamic equation for boring bar system. On the basis of it, the dynamic equation of boring bar system is solved accurately; its dynamics performance is analyzed and its structure optimized by use of the finite element analysis software ANSYS. Including:Firstly, presents theoretical analysis of boring bar vibrating system, creates the simplified model for pulling boring bar and on the light of these, the equations of motion for various vibration presenting in the boring process are created.Secondly, some factors are researched such as cutting angles and forces as well as elasticity coefficients of elastic supports, all of these affect the boring bar vibration system. This paper builds the mathematical model for the cutting angles, makes static analysis for boring head and presents the coupled equations of motion for system to determine the conditions which cause self-excited vibration and to define the functional relation between conditions and elasticity coefficients of elastic supports.Thirdly, static analysis is made to determine places where stress concentrations appeared in boring bar whose intensity and stiffness are checked. By dynamic characteristics, the first ten step natural frequencies and model patterns are obtained by modal analysis. Boring bar’s resonant frequencies presented under the action of a external excitation are gotten by harmonic response analysis, and transient dynamic responses are obtained for boring bar’s starting and ending cutting.Finally, the boring bar’s parameterization model is build by the ANSYS parametric design language, and the section diameter of hollow boring bar is regarded as design variable to optimize for getting the optimal solution.更多还原