本文選題：顫振 + 加工穩(wěn)定性　； 參考：《山東大學》2017年碩士論文

【摘要】：振動是切削加工中普遍存在的現象,尤其是在航空航天、汽車等領域的車削和銑削加工中,刀桿懸伸長、剛性差的問題極易導致切削加工過程產生顫振,降低切削加工穩(wěn)定性,嚴重影響加工質量和加工精度。為抑制長懸伸刀桿切削加工中的顫振,提出一種結構簡單、性能優(yōu)良和適應性強的被動減振解決方案,研制約束阻尼結構減振刀桿,以此實現抑制顫振,提高切削加工穩(wěn)定性的目的。約束阻尼結構刀桿能夠吸收切削加工過程產生的振動能量,并通過粘彈性阻尼材料的剪切變形轉化為熱能耗散,其阻尼減振性能在高頻時更強,可在一定程度上適應復雜多變的切削加工條件。首先,分析約束阻尼結構的耗能機理并結合刀桿的具體結構,初步設計約束阻尼結構車刀桿和約束阻尼結構銑刀桿,并根據粘彈性阻尼材料的動態(tài)力學性能分析減振刀桿的頻變阻尼特性;研究車削顫振和銑削顫振的產生機理,建立車削頻變阻尼單自由度振動模型和銑削頻變阻尼二自由度振動模型,推導車削極限徑向切削深度、銑削極限軸向切削深度和穩(wěn)定主軸轉速的計算公式;分析刀桿的模態(tài)參數與切削加工穩(wěn)定性的關系,確定減振刀桿的設計優(yōu)化目標為增大一階動剛度,同時保證較高的一階固有頻率。其次,通過實驗和回歸擬合確定三種粘彈性阻尼材料的動態(tài)剪切損耗因子和動態(tài)剪切模量與頻率的關系;對板類約束阻尼結構和軸類約束阻尼結構進行模態(tài)分析,建立懸臂梁模型和微元剪切耗能模型,推導模態(tài)參數的理論計算公式;通過有限元仿真和模態(tài)實驗驗證理論建模和計算的準確性。然后,對設計的約束阻尼結構車刀桿和約束阻尼結構銑刀桿進行減振性能優(yōu)化,優(yōu)化阻尼層結構尺寸以及優(yōu)選粘彈性阻尼材料;制造最優(yōu)約束阻尼結構車刀桿和最優(yōu)約束阻尼結構銑刀桿,并通過模態(tài)實驗對比約束阻尼結構刀桿和普通刀桿的阻尼減振性能,最優(yōu)約束阻尼結構車刀桿的一階動剛度同比增大82%,最優(yōu)約束阻尼結構銑刀桿的一階動剛度同比增大23.5%。最后,繪制車削加工和銑削加工穩(wěn)定性葉瓣圖,最優(yōu)約束阻尼結構車刀桿的極限徑向切削深度同比增大86.7%,最優(yōu)約束阻尼結構銑刀桿的極限軸向切削深度同比增大22%,加工穩(wěn)定區(qū)域均增大,加工穩(wěn)定性改善;根據穩(wěn)定性葉瓣圖選擇切削加工參數進行車削實驗和銑削實驗,在高主軸轉速和大切削深度下,約束阻尼結構刀桿的減振效果更好,加工穩(wěn)定性更強,與普通刀桿相比其工件表面質量明顯改善。
[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.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG502.3

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