【摘要】：增材制造技術是一種通過逐層累加來實現(xiàn)成形的制造技術。由于每次堆敷都存在很多不可控的變量,如散熱條件、熱積累等因素,導致堆敷尺寸容易出現(xiàn)偏差。所以,如何提高增材制造產(chǎn)品精度是當前增材制造面臨的主要研究問題之一。本文開發(fā)了一套具有手持式、自定位特點的三維形貌掃描系統(tǒng),并建立了閉環(huán)的增材制造系統(tǒng),提高了增材制造產(chǎn)品的成形精度。首先,本文建立了手持式自定位的三維掃描實驗系統(tǒng),使用張正友標定法標定了相機的內(nèi)外參數(shù),并提出了一種自動高效標定結構光平面方程的方法。利用雙目視覺原理計算標定點的三維坐標,精度達到了0.2mm,根據(jù)結構光三角法恢復了單幀掃描圖像,得到了單幀圖像被掃描物體結構光上點的三維信息,精度達到了0.1mm。優(yōu)化了圓形標定點中心坐標提取的算法,實現(xiàn)了相同幀左右目相機圖像坐標系下標定點的匹配,及相鄰幀圖像相機坐標系下標定點的立體匹配,使用標定點信息將不同幀圖像的數(shù)據(jù)拼接起來,完成數(shù)據(jù)拼接,獲取整體點云。根據(jù)上述原理,使用C++語言實現(xiàn)了具有在線采集處理圖像,顯示獲取三維點云功能的軟件。掃描精度在0.5mm以下,在保證點云之間最大間距為0.5mm的情況下,掃描速度可以達到15cm/min。針對電弧增材制造一般都是在平板上進行的現(xiàn)象,提出了一種投影到平板上均勻化點云的算法,有效的剔除了重復信息,在保證有效信息不丟失的情況下,大幅度減少了點云的數(shù)量,提高了點云處理的效率。結合點云統(tǒng)計濾波,高斯濾波和基于Delaunay三角形的貪婪投影三角化算法,對點云進行后處理并利用點云重建成曲面。使用C++語言實現(xiàn)了上述功能,利用OpenGL三維顯示技術,在MFC環(huán)境下實現(xiàn)了模型的動態(tài)三維顯示。將三維模型保存成STL格式,為其他三維模型處理軟件如CAD、SolidWorks等留出了接口。最后,分別對電弧增材制造過程中單層多道及多層多道堆敷情況,提出了堆敷道特征信息提取算法。對每層堆敷形貌都進行了三維形貌恢復,特征信息提取并根據(jù)檢測到的尺寸信息,改進了下一層堆敷參數(shù)和路徑,建立了閉環(huán)增材制造系統(tǒng),提高了增材制造產(chǎn)品的成形質(zhì)量。
[Abstract]:Adding material manufacturing technology is a kind of manufacturing technology which can realize forming by layer-by-layer accumulation. Because there are a lot of uncontrollable variables such as heat dissipation condition and heat accumulation, it is easy to deviate from the size of stack coating. Therefore, how to improve the precision of material-increasing manufacturing is one of the main research problems. In this paper, a three-dimensional scanning system with the characteristics of hand-held and self-positioning has been developed, and a closed-loop material increasing manufacturing system has been established to improve the forming accuracy of the products. Firstly, a three dimensional scanning experiment system of hand-held self-positioning is established. The internal and external parameters of the camera are calibrated by Zhang Zhengyou calibration method, and a method of automatically and efficiently calibrating the structural light plane equation is proposed. Using the binocular vision principle to calculate the 3D coordinates of the scalar points, the accuracy reaches 0.2mm. according to the structure-light triangulation method, the single-frame scanning image is restored, and the three-dimensional information of the points on the structural light of the scanned object is obtained. The precision is 0.1 mm. This paper optimizes the algorithm of extracting the center coordinate of circular frame, realizes the matching of the subscript point of the same frame left and right camera image coordinate system, and the stereo matching of the next frame image camera coordinate system. The data of different frame images are stitched up with the information of mark and fixed point to complete the data mosaic and obtain the whole point cloud. According to the above principle, the software with the function of on-line collecting and processing images and displaying and acquiring 3D point cloud is realized by using C language. The scanning accuracy is below 0.5mm and the scanning speed can reach 15 cm / min when the maximum distance between point clouds is 0.5mm. In view of the phenomenon that arc augmentation manufacturing is generally carried out on a flat plate, an algorithm for projecting the point cloud homogeneously on the plate is proposed, which effectively removes the repeated information and ensures that the effective information is not lost. It greatly reduces the number of point clouds and improves the efficiency of point cloud processing. Combining statistical filtering with point cloud, Gao Si filter and greedy projection triangulation algorithm based on Delaunay triangle, point cloud is processed and reconstructed into curved surface. C language is used to realize the above functions and OpenGL 3D display technology is used to realize the dynamic 3D display of the model in the MFC environment. The 3D model is saved into STL format, and the interface is provided for other 3D model processing software such as CAD,SolidWorks. Finally, an algorithm for extracting characteristic information of single layer multi-channel and multi-layer multi-channel stack is proposed. The 3D morphology of each layer was restored, and the feature information was extracted. According to the detected size information, the parameters and path of the next layer were improved, the closed-loop material increasing manufacturing system was established, and the forming quality of the product was improved.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG806

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