频变约束阻尼结构减振刀杆的设计与研究

发布时间：2018-04-21 14:23

本文选题：颤振 + 加工稳定性　；参考：《山东大学》2017年硕士论文

【摘要】：振动是切削加工中普遍存在的现象,尤其是在航空航天、汽车等领域的车削和铣削加工中,刀杆悬伸长、刚性差的问题极易导致切削加工过程产生颤振,降低切削加工稳定性,严重影响加工质量和加工精度。为抑制长悬伸刀杆切削加工中的颤振,提出一种结构简单、性能优良和适应性强的被动减振解决方案,研制约束阻尼结构减振刀杆,以此实现抑制颤振,提高切削加工稳定性的目的。约束阻尼结构刀杆能够吸收切削加工过程产生的振动能量,并通过粘弹性阻尼材料的剪切变形转化为热能耗散,其阻尼减振性能在高频时更强,可在一定程度上适应复杂多变的切削加工条件。首先,分析约束阻尼结构的耗能机理并结合刀杆的具体结构,初步设计约束阻尼结构车刀杆和约束阻尼结构铣刀杆,并根据粘弹性阻尼材料的动态力学性能分析减振刀杆的频变阻尼特性;研究车削颤振和铣削颤振的产生机理,建立车削频变阻尼单自由度振动模型和铣削频变阻尼二自由度振动模型,推导车削极限径向切削深度、铣削极限轴向切削深度和稳定主轴转速的计算公式;分析刀杆的模态参数与切削加工稳定性的关系,确定减振刀杆的设计优化目标为增大一阶动刚度,同时保证较高的一阶固有频率。其次,通过实验和回归拟合确定三种粘弹性阻尼材料的动态剪切损耗因子和动态剪切模量与频率的关系;对板类约束阻尼结构和轴类约束阻尼结构进行模态分析,建立悬臂梁模型和微元剪切耗能模型,推导模态参数的理论计算公式;通过有限元仿真和模态实验验证理论建模和计算的准确性。然后,对设计的约束阻尼结构车刀杆和约束阻尼结构铣刀杆进行减振性能优化,优化阻尼层结构尺寸以及优选粘弹性阻尼材料;制造最优约束阻尼结构车刀杆和最优约束阻尼结构铣刀杆,并通过模态实验对比约束阻尼结构刀杆和普通刀杆的阻尼减振性能,最优约束阻尼结构车刀杆的一阶动刚度同比增大82%,最优约束阻尼结构铣刀杆的一阶动刚度同比增大23.5%。最后,绘制车削加工和铣削加工稳定性叶瓣图,最优约束阻尼结构车刀杆的极限径向切削深度同比增大86.7%,最优约束阻尼结构铣刀杆的极限轴向切削深度同比增大22%,加工稳定区域均增大,加工稳定性改善;根据稳定性叶瓣图选择切削加工参数进行车削实验和铣削实验,在高主轴转速和大切削深度下,约束阻尼结构刀杆的减振效果更好,加工稳定性更强,与普通刀杆相比其工件表面质量明显改善。
[Abstract]:Vibration is a common phenomenon in cutting, especially in turning and milling in aerospace, automobile and other fields. The machining quality and precision are seriously affected. In order to suppress the chatter in the cutting process of the long overhanging cutter rod, a simple structure, excellent performance and strong adaptability solution for passive vibration reduction is put forward, and the damper rod of constrained damping structure is developed so as to suppress the chatter. The purpose of improving the stability of cutting. The constrained damping structure tool rod can absorb the vibration energy produced in the cutting process, and the shear deformation of the viscoelastic damping material is converted into heat energy dissipation, and its damping and damping performance is stronger at high frequency. It can adapt to the complicated and changeable cutting conditions to some extent. First of all, the energy dissipation mechanism of constrained damping structure is analyzed and combined with the specific structure of cutter rod, the tool rod of constrained damping structure and the constrained damping structure milling cutter rod are preliminarily designed. According to the dynamic mechanical properties of viscoelastic damping materials, the frequency varying damping characteristics of vibration absorber are analyzed, and the mechanism of turning chatter and milling flutter is studied. The vibration model of single degree of freedom with variable damping for turning frequency and the vibration model of two degrees of freedom with variable damping for milling frequency are established, and the formulas for calculating the limit radial cutting depth, the limit axial cutting depth of milling and the stable spindle speed are derived. Based on the analysis of the relationship between the modal parameters of the tool rod and the stability of the cutting process, it is determined that the optimum design objective of the vibration absorber is to increase the first-order dynamic stiffness and ensure the higher natural frequency of the first order. Secondly, the dynamic shear loss factor and the relationship between dynamic shear modulus and frequency of three kinds of viscoelastic damping materials are determined by experiments and regression fitting, and the modal analysis of plate constrained damping structure and axial constrained damping structure is carried out. The cantilever beam model and micro-element shear energy dissipation model are established, and the theoretical formulas for modal parameters are derived, and the accuracy of theoretical modeling and calculation is verified by finite element simulation and modal experiment. Then, the vibration absorption performance of the constrained damping structure tool rod and the constrained damping structure milling stem are optimized, the structure size of the damping layer and the viscoelastic damping material are optimized. The optimal constrained damping structure cutter rod and the optimal constrained damping structure milling cutter rod are manufactured. The damping and vibration absorption performance of the constrained damping structure tool rod and the common tool rod are compared by modal experiments. The first order dynamic stiffness of the optimal constrained damping structure turning tool rod is increased by 82%, and the first order dynamic stiffness of the optimal constrained damping structure milling cutter rod increases by 23. 5% year on year. Finally, the stable leaf flap diagram of turning and milling is drawn. The limit radial cutting depth of the optimal constrained damping structure turning rod is increased by 86.7 compared with the same period of last year, and the limit axial cutting depth of the optimal constrained damping structure milling rod is increased by 22% compared with the same period of last year, the machining stability region is increased and the machining stability is improved. The turning experiment and milling experiment are carried out by selecting cutting parameters according to the stable leaflet diagram. Under the condition of high spindle speed and large cutting depth, the vibration reduction effect of constrained damping structure cutter rod is better and the machining stability is stronger. Compared with the common tool rod, the surface quality of the workpiece is obviously improved.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG502.3

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