本文選題：凸輪輪廓 + NURBS重構�。� 參考：《山東農業(yè)大學》2014年博士論文

【摘要】：在自動機械中，凸輪機構主要用作傳動、導向和控制元件，其運動、動力等工作特性對自動機械的精度、效率和速度有決定性影響。本文在全面分析國內外凸輪機構運動和動力特性研究的基礎上，提出了一種新的凸輪機構設計和優(yōu)化方法，該方法以非均勻有理B樣條(non-uniform rational B-splines, NURBS)為工具，通過凸輪廓線、廓面NURBS重構，進一步改善和提高凸輪機構的運動和動力等工作特性，從而滿足各類自動機械對高速、高精度工作的日益追求。 NURBS曲線曲面因其優(yōu)良的全局表達性和強大的局部調控性，正逐漸引起工程界重視并在各領域得到應用。本文首先分析了NURBS曲線曲面的數學模型及其模型特性，設計了曲線曲面NURBS重構流程，，重點研究了NURBS曲線曲面控制參量節(jié)點矢量、權因子及控制頂點等各項參數的幾何意義、對曲線曲面形狀的影響及計算方法。 其次，在研究NURBS曲線曲面重構方法的基礎上，提出了凸輪廓面NURBS重構的設計方法。為提高空間凸輪廓面的建模和創(chuàng)成精度，利用直紋面和等距曲面理論分析了空間凸輪廓面的幾何特性，基于單參數曲面包絡理論，建立了空間凸輪廓面方程。利用空間分度凸輪廓面方程獲取離散點云數據，實現了空間凸輪廓面NURBS重構，建立了空間凸輪參數化特征模型。基于該模型，進行空間凸輪分度機構運動特性優(yōu)化與仿真，進而生成加工制造模型，實現空間凸輪NURBS廓面的仿真加工和四軸銑削NURBS高品質創(chuàng)成。 再次，針對高速工況下凸輪機構動態(tài)特性變差的問題，利用NURBS曲線設計和優(yōu)化凸輪機構從動件運動規(guī)律，進行高速凸輪廓線NURBS重構。采用動態(tài)分析方法，建立高速凸輪機構單自由度動態(tài)特性模型，推導了高速凸輪機構輸入和動態(tài)輸出之間的關系，獲得了系統(tǒng)殘余振動評價指標，由此建立了高速凸輪機構多目標動態(tài)特性優(yōu)化模型。設計了集成禁忌搜索策略和變參數二次尋優(yōu)思想的改進人工魚群多目標優(yōu)化算法。通過該算法對高速凸輪機構多目標動態(tài)特性優(yōu)化模型尋優(yōu)，以獲取優(yōu)化模型的Pareto最優(yōu)解，藉此重構高速凸輪NURBS廓線，研究NURBS廓線高速凸輪機構的主振和余振響應，以降低系統(tǒng)的振動和沖擊。 最后，采用運動和動力性能集成優(yōu)化方法，基于NURBS曲線進一步研究凸輪機構的動力接觸特性。以擺動從動件固定凸輪機構為研究對象，分析了槽道凸輪殘膜撿拾機構的工作特性，設計了適合機構的單停留修正正弦（Modifed Sine，MS）運動規(guī)律曲線，考慮運動副摩擦，建立槽道凸輪殘膜撿拾機構的動力模型，根據赫茲接觸理論得到槽道凸輪殘膜撿拾機構的接觸應力計算方程。采用NURBS曲線進行槽道凸輪殘膜撿拾機構的運動特性設計，以接觸應力和加速度為優(yōu)化目標，利用改進人工魚群算法進行多目標優(yōu)化，優(yōu)化結果和運動仿真表明：與單停留MS廓線相比，優(yōu)化后NURBS廓線槽道凸輪殘膜撿拾機構的加速度和接觸應力較小，沖擊和磨損較輕，提高了機構工作的可靠性和使用壽命。 本文的研究結果為凸輪機構的設計與制造提供了一個新的方法和思路，對于提升我國中高端凸輪機構的研發(fā)水平，實現高端產品的國產化具有一定的理論研究價值和工程應用前景。
[Abstract]:In automatic machinery, the cam mechanism is mainly used as transmission, guidance and control elements, and its motion and dynamic characteristics have a decisive influence on the accuracy, efficiency and speed of automatic machinery. On the basis of a comprehensive analysis of the motion and dynamic characteristics of the cam mechanism at home and abroad, a new design and optimization method of the cam mechanism is proposed in this paper. The method uses the non-uniform rational B spline (non-uniform rational B-splines, NURBS) as a tool, through the cam profile and the reconstruction of the profile surface NURBS, to further improve and improve the working characteristics of the cam mechanism, such as motion and power, so as to meet the increasing pursuit of high speed and high precision work of various automatic machines.
Because of its excellent global expressiveness and strong local regulation, NURBS curve and surface are gradually attracting the attention of the engineering community and being applied in various fields. Firstly, the mathematical model and its model characteristics of NURBS curve and surface are analyzed. The NURBS reconstruction process of curve and surface is designed, and the control parameter node vector of NURBS curve and surface is studied. The geometric meaning of parameters such as quantity, weight factor and control point, and its influence on the shape of curve and surface and its calculation method are discussed.
Secondly, on the basis of studying the method of NURBS curve and surface reconstruction, the design method of NURBS reconstruction of cam profile is put forward. In order to improve the modeling and creating precision of the spatial cam profile, the geometric characteristics of the spatial cam profile are analyzed by the theory of the straight surface and the isometric surface. Based on the single parameter curved loaf theory, the spatial cam profile is established. Using the spatial indexing cam profile equation to obtain the discrete point cloud data, the spatial cam profile NURBS reconstruction is realized, and the spatial cam parameterized characteristic model is established. Based on this model, the motion characteristics of the spatial cam indexing mechanism are optimized and simulated, and then the processing model is generated to realize the simulation processing of the spatial cam NURBS profile surface. And four axis milling of NURBS high quality creation.
Thirdly, in view of the problem of the dynamic characteristics of cam mechanism in high-speed working condition, the NURBS curve is used to design and optimize the motion law of the cam mechanism, and the NURBS reconstruction of the high-speed cam profile is carried out. The dynamic analysis method is used to establish the dynamic characteristic model of the single degree of freedom of the high-speed cam mechanism, and the input and dynamic output of the high-speed cam mechanism are derived. The evaluation index of the residual vibration of the system is obtained, and the multi-objective dynamic characteristic optimization model of the high-speed cam mechanism is established. The integrated tabu search strategy and the variable parameter two optimization thought are designed to improve the multi target optimization algorithm of the artificial fish group. The algorithm is used to optimize the dynamic characteristics of the multi target dynamic characteristics of the high-speed cam mechanism. In order to obtain the optimal Pareto solution of the optimized model, the NURBS profile of the high-speed cam is reconstructed, and the main vibration and the residual vibration response of the high-speed cam mechanism of the NURBS profile are studied in order to reduce the vibration and impact of the system.
Finally, based on the integrated optimization method of motion and dynamic performance, the dynamic contact characteristics of the cam mechanism are further studied based on the NURBS curve. The working characteristics of the cam mechanism with swinging follower are taken as the research object. The working characteristics of the grooved cam residual membrane pickup mechanism are analyzed, and the Modifed Sine, MS motion gauge suitable for the mechanism is designed. According to the Hertz contact theory, the contact stress calculation equation of the grooved cam residual film pickup mechanism is obtained according to the Hertz contact theory. The motion characteristics of the grooved cam residual film pickup mechanism are designed by using the NURBS curve, and the contact stress and acceleration are used as the optimization target and the modification is used. The artificial fish swarm algorithm is used for multi-objective optimization. The optimization results and motion simulation show that the acceleration and contact stress of the cam residual membrane pickup mechanism of the optimized NURBS profile slot channel are smaller than the single MS profile, and the impact and wear are lighter, and the reliability and service life of the mechanism work are improved.
The results of this paper provide a new method and idea for the design and manufacture of the cam mechanism. It has a certain theoretical research value and engineering application prospect for improving the R & D level of the middle and high end cam mechanisms in China and realizing the localization of the high-end products.
【學位授予單位】：山東農業(yè)大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TH112.2

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