大型丝杠硬态旋铣加工特性及丝杠副综合性能评估研究

发布时间：2018-05-19 13:16

本文选题：螺纹硬旋铣 + 多点动态约束　；参考：《南京理工大学》2016年硕士论文

【摘要】：大型丝杠硬旋铣具有时变断续冲击、多点变约束、抱紧装置动态夹持等特点,使得丝杠加工过程中“机床-刀具-工件”系统产生复杂的动态响应,从而影响丝杠工件表面完整性、寿命、可靠性等综合性能。为实现对丝杠铣过程中的优化控制,提高螺纹工件加工质量及综合性能,本课题以八米丝杠旋风铣床及加工后丝杠副为研究对象,分别从螺纹硬旋铣圆弧型切削及二次切削仿真、丝杠加工全长系统动态特性,以及加工后丝杠副工件综合性能的评估与优化等方面进行了研究。针对螺纹硬旋铣几何成型机理,基于ABAQUS软件建立圆弧型切削模型,仿真了切削过程中的切削力,并通过硬旋铣试验进行了验证；基于最大瞬时厚度建立了二维正交切削模型,研究了切削速度、切削厚度、刀具前角等切削工艺参数下切削力、温度场及残余应力的变化规律；建立了二次切削有限元模型,分析了二次切削对切削力、温度场及残余应力的影响。针对时变断续冲击和多点动态约束等特性,建立了基于瑞利梁理论的三向移动力作用下的动力学模型,分析了丝杠加工全长的振动响应情况,并通过硬旋铣试验进行了验证；研究了均匀布局条件下浮动支撑及抱紧装置刚度、浮动支撑个数及间距对全长动态响应的影响；以最小的系统振动响应为目标,基于遗传算法研究了非均匀布局条件下浮动支撑最优布局位置。针对丝杠副高可靠性长寿命及试验台数量有限等局限性,提出了基于全周期分段步加策略的小子样加速寿命试验方法,开展了丝杠副小子样加速寿命试验；为更加全面地评估及提高丝杠副综合性能,构建了基于熵权和专家知识综合权重的丝杠副综合性能多目标评估及优化模型。本文在物理行为仿真、系统动力学及丝杠副综合性能方面的研究成果将进一步完善金属高速硬旋铣加工的基础理论,为高品质大型丝杠高效旋铣加工提供理论指导,小子样加速寿命试验的研究可用于同类型的细长轴类零件的可靠性评估及寿命预测,在丝杠副综合性能评估及优化方面的研究将为丝杠副性能的提升提供理论支撑,具有显著的社会经济效益。
[Abstract]:Large screw hard rotary milling has the characteristics of time-varying intermittent impact, multi-point variable constraint, and dynamic clamping of clamping device, which makes the "machine-cutter-workpiece" system produce complex dynamic response in the machining process of the lead screw. Thus affecting the surface integrity, life, reliability and other comprehensive performance of the lead screw workpiece. In order to realize the optimal control of the milling process of the screw and improve the machining quality and comprehensive performance of the thread workpiece, this paper takes the whirlwind milling machine of the 8-meter screw and the pair of the leadscrew after machining as the research object. In this paper, the simulation of spiral cutting and secondary cutting, the dynamic characteristics of full-length lead screw machining system, and the evaluation and optimization of the comprehensive performance of the screw pair after machining are studied respectively. Aiming at the geometric forming mechanism of hard rotary milling of thread, the arc cutting model is established based on ABAQUS software, and the cutting force in the cutting process is simulated and verified by hard rotary milling test, and the two-dimensional orthogonal cutting model is established based on the maximum instantaneous thickness. The variation of cutting force, temperature field and residual stress under cutting parameters such as cutting speed, cutting thickness and cutting tool front angle are studied, the finite element model of secondary cutting is established, and the cutting force of secondary cutting is analyzed. The effect of temperature field and residual stress. In view of the characteristics of time-varying intermittent impact and multi-point dynamic constraint, a dynamic model based on Rayleigh beam theory is established, and the vibration response of the full length of the lead screw machining is analyzed and verified by hard rotating milling test. The effects of stiffness, number and spacing of floating braces on full-length dynamic response under uniform layout are studied, and the minimum vibration response of the system is taken as the target. Based on genetic algorithm, the optimal position of floating support is studied under the condition of non-uniform layout. In view of the limitation of high reliability and limited number of test stands, a method of small sample accelerated life test based on full period piecewise stepping strategy is put forward, and the small sample accelerated life test of lead screw pair is carried out. In order to evaluate and improve the comprehensive performance of the screw pair more comprehensively, a multi-objective evaluation and optimization model of the comprehensive performance of the screw pair based on entropy weight and expert knowledge comprehensive weight was constructed. In this paper, the physical behavior simulation, system dynamics and the comprehensive performance of the screw pair will further improve the basic theory of metal high speed hard rotary milling, and provide theoretical guidance for the high quality and high efficiency rotary milling of large screw. The research of small sample accelerated life test can be used to evaluate the reliability and predict the life of the slender shaft parts of the same type. The research on the comprehensive performance evaluation and optimization of the lead screw pair will provide theoretical support for the improvement of the performance of the lead screw pair. It has remarkable social and economic benefits.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG54

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