【摘要】：隨著生活水平的不斷提高,僅僅重視功能要求的產(chǎn)品已經(jīng)無法滿足消費者了。市場需要產(chǎn)品不僅要有優(yōu)良的性能還要有美觀的外形。美觀且豐富多樣的產(chǎn)品造型必然會增加產(chǎn)品外形的復(fù)雜程度和加工難度,越復(fù)雜的外形越需要由多個自由曲面縫合而成,但是傳統(tǒng)的加工方法受到了局限。為了順應(yīng)時代的變化,產(chǎn)品的創(chuàng)造性和經(jīng)濟性,利用逆向工程技術(shù)手段成了必然趨勢。 在許多工業(yè)領(lǐng)域中,逆向工程技術(shù)采用3D掃描和3D打印技術(shù)相結(jié)合的方式來實現(xiàn)產(chǎn)品的快速制造。對已有的實物或油泥模型進行處理并用三維掃描設(shè)備完成測量,將模型表面測得的數(shù)據(jù)通過相應(yīng)的逆向軟件實現(xiàn)曲面重構(gòu),獲得實物模型的3D數(shù)字模型,不斷循環(huán),直到符合標準的產(chǎn)品模型用于后續(xù)的計算機輔助分析和制造。 在掃描測量方面,本文介紹了掃描儀的類型和測量原理,著重分析了實驗所用的手持式三維激光掃描儀設(shè)備。通過使用手持式掃描儀對實物模型的實際操作,本文探索出一種最優(yōu)的掃描順序,可以使系統(tǒng)在表面最優(yōu)運算法方面發(fā)揮最好的效果,以便更好的獲得準確的數(shù)據(jù)。 在運用逆向工程技術(shù)的過程中,會遇到因為點云數(shù)據(jù)量大而影響到曲面擬合的質(zhì)量或者是和廣泛運用的CAD軟件兼容性的問題,所以本文深入研究了曲線、曲面基礎(chǔ)理論和特性,總結(jié)了在不同情況下三角Bezier曲面擬合NURBS曲面擬合的區(qū)別以及NURBS方法的優(yōu)點。利用專業(yè)的逆向軟件來進行點云處理,以實例為代表,突出了專業(yè)逆向軟件的優(yōu)勢,同時更好的應(yīng)用了NURBS方法。本文總結(jié)出了最優(yōu)的擬合方法,能夠擬合出高質(zhì)量的曲面,與下游CAD軟件的工程應(yīng)用實現(xiàn)了良好的兼容性。 逆向工程技術(shù)也在曲面重建中起著重要作用,它明顯地降低了曲面重建的時間和模型相同部分的成本。在數(shù)據(jù)拼合、數(shù)據(jù)劃分和模型重構(gòu)中,為了要獲得精確的實體數(shù)字模型,必須保證數(shù)據(jù)的精簡和準確。在數(shù)據(jù)每一步操作過程中,數(shù)據(jù)的特征識別和提取,特別是輪廓線的提取,在曲面重建中起著十分關(guān)鍵的作用。本課題通過實例研究,得出結(jié)果：對特征和輪廓線實現(xiàn)精確的識別和提取,可以提高曲面重建后的精度,快速實現(xiàn)產(chǎn)品的創(chuàng)新設(shè)計。
[Abstract]:With the continuous improvement of living standards, only pay attention to functional requirements of the product has been unable to meet consumers. The market needs products not only to have excellent performance but also to have a beautiful appearance. Beautiful and rich and diverse product modeling will inevitably increase the complexity and processing difficulty of the product shape. The more complex the shape is, the more necessary it is to be stitched up by multiple free-form surfaces, but the traditional machining methods are limited. In order to adapt to the changes of the times and the creativity and economy of products, the use of reverse engineering technology has become an inevitable trend. In many industrial fields, reverse engineering technology uses 3D scanning and 3D printing technology to realize the rapid manufacturing of products. The existing physical or sludge models are processed and measured by three-dimensional scanning equipment. The data measured on the surface of the model are reconstructed by the corresponding reverse software, and the 3D digital model of the physical model is obtained, which is constantly circulating. Until the standard product model is used for subsequent computer-aided analysis and manufacturing. In the aspect of scanning and measuring, this paper introduces the type and measuring principle of scanner, and analyzes the handheld 3D laser scanner equipment used in the experiment. Through the practical operation of the physical model by using the handheld scanner, this paper explores an optimal scanning sequence, which can make the system play the best role in the surface optimal operation algorithm, so as to obtain the accurate data better. In the process of using reverse engineering technology, we will encounter the problem of affecting the quality of surface fitting or compatibility with widely used CAD software because of the large amount of point cloud data, so this paper deeply studies the basic theory and characteristics of curve and surface. The difference of fitting NURBS surface fitting with triangular Bezier surface under different conditions and the advantages of NURBS method are summarized. The point cloud processing is carried out by using the professional reverse software, represented by an example, which highlights the advantages of the professional reverse software and better applies the NURBS method. In this paper, the optimal fitting method is summarized, which can fit the high quality surface and achieve good compatibility with the engineering application of downstream CAD software. Reverse engineering also plays an important role in surface reconstruction, which obviously reduces the time of surface reconstruction and the cost of the same part of the model. In order to obtain accurate entity digital model, it is necessary to ensure the simplification and accuracy of data in data combination, data partition and model reconstruction. In each step of data operation, the feature recognition and extraction of data, especially the extraction of contours, play a very key role in surface reconstruction. Through the case study, the results show that the accurate recognition and extraction of features and contours can improve the accuracy of surface reconstruction and quickly realize the innovative design of products.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TB472

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