铣削过程力学建模与刀具结构优化技术方法研究

发布时间：2018-06-11 11:46

本文选题：薄壁件 + 铣削力　；参考：《天津大学》2016年硕士论文

【摘要】：薄壁筋板是保证火箭燃料贮箱强度的重要组成部分,因其薄壁特性,加工时易产生振动。薄壁件加工已成为机械制造加工领域研究的一大难点。本论文以铣削大型薄壁件为研究对象,以能够有效减振的刀具为研究目标。一方面,研究建立能够用于预测变螺旋角立铣刀铣削力大小的解析模型。另一方面,研究立铣刀的结构参数的优化和设计。论文的工作开展如下:(1)建立了基于切削机理的铣削力解析模型,将切削参数、刀具几何结构与切削力联系起来,模型中考虑了齿间角和螺旋角的影响。离散各刀齿切削刃为许多微元切削刃,建立了基于能量法的三维微元斜角切削模型,模型清晰表达了微元切削的几何角度、切削速度和微元切削力的关系。对各切削刃上的微元切削力沿铣刀轴向进行积分,考虑进给速度对铣削速度的影响,建立了静态铣削力模型。考虑再生效应的影响,建立了动态铣削力模型。(2)应用已经建立的铣削力模型相关理论,对变螺旋角立铣刀的齿距和切削厚度进行了分析,并得到变螺旋角立铣刀铣削力变化趋势。对铣削力进行傅立叶变换,从频域的角度对变螺旋角立铣刀的减振机理进行了分析。基于铣削力频域能均布,对变螺旋角立铣刀结构进行优化。建立以铣削力频谱标准偏差最小为目标,以铣削过程中的切削力大小、切削热大小和铣刀动平衡为约束条件的数学模型,应用遗传算法对齿间角、螺旋角进行了全域优化。对变螺旋角立铣刀进行了具体的结构设计,并应用有限元软件对优化设计的立铣刀进行了校核。(3)设计了铣削力实验方案,并分别应用等齿距立铣刀和变螺旋角立铣刀进行了铣削力实验,实验结果与仿真结果匹配良好,验证了本论文建立的铣削力模型的准确性。进行了优化设计的变螺旋角立铣刀的制备,并对其进行了薄壁件铣削振动实验,并与等齿距立铣刀进行了实验对比。分别从铣削振动位移和铣削力频域的角度证明了优化设计的立铣刀的减振有效性。
[Abstract]:Thin-walled stiffened plate is an important part to ensure the strength of rocket fuel tank. Because of its thin-wall characteristics, vibration is easy to occur in machining. Thin-walled parts processing has become a major difficulty in the field of mechanical manufacturing. In this paper, milling of large thin-walled parts is studied, and the research target is the tool which can effectively reduce vibration. On the one hand, an analytical model which can be used to predict the milling force of variable helical angle end milling cutter is established. On the other hand, the optimization and design of the structural parameters of the end milling cutter are studied. The main work of this paper is as follows: (1) an analytical model of milling force based on cutting mechanism is established. The cutting parameters, tool geometry and cutting force are related. The influence of the angle between teeth and helical angle is considered in the model. The cutting edge of discrete teeth is many micro-element cutting edges. A three-dimensional angular cutting model of micro-element based on energy method is established. The relationship among geometric angle, cutting speed and cutting force of micro-element cutting is clearly expressed by the model. The static milling force model is established by integrating the micro-element cutting force along the axis of the milling cutter and considering the influence of the feed speed on the milling speed. Considering the influence of regeneration effect, the dynamic milling force model is established. (2) based on the theory of milling force model, the tooth pitch and cutting thickness of variable helical angle end milling cutter are analyzed. The changing trend of milling force of variable helical angle end milling cutter is obtained. In this paper, the Fourier transform of milling force is carried out, and the damping mechanism of variable helical angle end milling cutter is analyzed from the angle of frequency domain. Based on the energy distribution of milling force in frequency domain, the structure of variable helical angle end milling cutter is optimized. A mathematical model with the minimum standard deviation of milling force spectrum as the objective, the cutting force, the cutting heat and the dynamic balance of milling cutter as the constraint condition is established. The global optimization of the angle between teeth and helical angle is carried out by using genetic algorithm. The structural design of the end milling cutter with variable helical angle is carried out, and the experimental scheme of milling force is designed by using finite element software to check the optimized end milling cutter. The experiments of milling force with equal pitch end milling cutter and variable helical angle end milling cutter are carried out respectively. The experimental results match well with the simulation results, which verify the accuracy of the milling force model established in this paper. In this paper, the optimized design of variable helical angle end milling cutter is made, and the vibration experiment of thin-wall milling cutter is carried out, and the experiment is compared with that of equal tooth spacing end milling cutter. The vibration reduction effectiveness of the optimized end milling cutter is proved from the milling vibration displacement and milling force frequency domain respectively.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V460

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