本文選題：蜂窩芯測(cè)量 + 外形輪廓測(cè)量　； 參考：《西南交通大學(xué)》2017年碩士論文

【摘要】：隨著航空制造技術(shù)的日益發(fā)展,現(xiàn)代飛機(jī)正朝著高性能、高減重、以及低成本的方向發(fā)展。蜂窩芯結(jié)構(gòu)是現(xiàn)代飛機(jī)上采用的一種新型填充復(fù)合材料,具有重量輕、穩(wěn)定性好、強(qiáng)度高特點(diǎn)。但蜂窩芯結(jié)構(gòu)較為復(fù)雜,類似蜜蜂巢穴呈空心六方晶格,有規(guī)則的排列。蜂窩芯類零件上下表面是密集排列的孔,側(cè)面為切割后不完整的蜂窩孔壁。壁厚占蜂窩芯外形輪廓的總表面積比例較小,且壁厚較薄。結(jié)構(gòu)特殊性給該類零件加工質(zhì)量測(cè)量帶了來(lái)較大困難。針對(duì)這情況,分析了現(xiàn)階段較為典型的數(shù)字化測(cè)量技術(shù),針對(duì)蜂窩芯結(jié)構(gòu)的外形輪廓和孔特征分別提出較優(yōu)的測(cè)量方案,并將兩種不同的測(cè)量數(shù)據(jù)進(jìn)行了融合研究,主要工作內(nèi)容如下:1.針對(duì)蜂窩芯外形輪廓測(cè)量,提出了一種基于三維光學(xué)掃描的測(cè)量方案。首先在蜂窩芯表面緊密貼合一覆蓋層,以覆蓋層的外形輪廓間接反映蜂窩芯的外形輪廓。采用三維光學(xué)掃描采集覆蓋層外形點(diǎn)云數(shù)據(jù),通過(guò)計(jì)算點(diǎn)云的法矢,然后在法矢方向偏置覆蓋層厚度,從而獲得蜂窩芯的外形輪廓數(shù)據(jù)。最后通過(guò)實(shí)例驗(yàn)證了測(cè)量方法的可行性。在計(jì)算點(diǎn)云數(shù)據(jù)法矢的過(guò)程中,采用計(jì)算點(diǎn)云k鄰域,以k鄰域建立微切平面得到法矢的方法,文中改進(jìn)了點(diǎn)云k鄰域的搜索算法,提高了點(diǎn)云數(shù)據(jù)法矢的計(jì)算速度。2.提出了一種基于三坐標(biāo)測(cè)量機(jī)的蜂窩芯孔特征測(cè)量方法。首先計(jì)算孔截面內(nèi)包含孔壁最小測(cè)量范圍,然后利用測(cè)針在此范圍內(nèi)采樣測(cè)量,不斷逼近零件孔壁獲得近似孔壁點(diǎn),通過(guò)近似孔壁點(diǎn)擬合獲得精確的孔心坐標(biāo)。根據(jù)三坐標(biāo)測(cè)量機(jī)測(cè)針參數(shù)、蜂窩芯參數(shù)以及孔特征理論數(shù)據(jù)對(duì)測(cè)量過(guò)程的極限誤差進(jìn)行了分析。3.三維光學(xué)掃描數(shù)據(jù)與三坐標(biāo)測(cè)量數(shù)據(jù)的精確融合。在測(cè)量過(guò)程中引入靶標(biāo)球,用三坐標(biāo)測(cè)量機(jī)和光學(xué)掃描儀分別對(duì)靶標(biāo)球進(jìn)行測(cè)量,根據(jù)不同測(cè)量數(shù)據(jù)中的球心位置計(jì)算得到數(shù)據(jù)的變換矩陣,實(shí)現(xiàn)數(shù)據(jù)的融合。在計(jì)算三維光學(xué)測(cè)量數(shù)據(jù)的靶標(biāo)球心過(guò)程中,按照球體特性先對(duì)球體數(shù)據(jù)進(jìn)行初步提取,然后引入了 RANSAC算法,精確提取球體數(shù)據(jù),提高了球心的計(jì)算精度。研究成果表明:有效的解決了蜂窩芯外形輪廓及孔特征的測(cè)量難題,提高了測(cè)量效率和測(cè)量精度,并實(shí)現(xiàn)了不同測(cè)量數(shù)據(jù)的精確融合。
[Abstract]:With the development of aeronautical manufacturing technology, modern aircraft are developing towards high performance, high weight loss and low cost.Honeycomb core structure is a new type of filled composite material used in modern aircraft, which has the characteristics of light weight, good stability and high strength.But honeycomb core structure is more complex, similar to honeybee nest with hollow hexagonal lattice, regular arrangement.The upper and lower surface of honeycomb core parts are densely arranged holes, and the side is incomplete honeycomb hole wall after cutting.The ratio of wall thickness to the total surface area of honeycomb core profile is small, and the wall thickness is thin.The structural particularity makes it difficult to measure the machining quality of this kind of parts.In view of this situation, this paper analyzes the typical digital measurement technology at the present stage, puts forward better measuring schemes for the outline and hole characteristics of honeycomb core structure, and studies the fusion of two kinds of measurement data.The main work is as follows: 1.A measurement scheme based on three-dimensional optical scanning is proposed for the profile measurement of honeycomb core.Firstly, a covering layer is tightly attached to the honeycomb core surface, and the contour of the honeycomb core is indirectly reflected by the outline of the cover layer.The contour data of honeycomb core are obtained by calculating the normal vector of the point cloud and biasing the thickness of the cover layer in the normal vector direction.Finally, the feasibility of the measurement method is verified by an example.In the process of calculating the normal vector of point cloud data, the method of computing point cloud k neighborhood and establishing a micro-tangent plane by k neighborhood is used to obtain the normal vector. In this paper, the search algorithm of point cloud k neighborhood is improved, and the computing speed of normal vector of point cloud data is improved.In this paper, a method for measuring the characteristics of honeycomb core holes based on CMM is proposed.First, the minimum measurement range of the hole wall is calculated in the section of the hole, and then the sample measurement is made by using the needle in this range, and the approximate hole wall point is obtained by continuously approaching the hole wall of the part, and the exact coordinates of the hole center are obtained by fitting the approximate hole wall point.The limit error of the measuring process is analyzed according to the needle parameters, honeycomb core parameters and the theoretical data of hole characteristics of CMM.Accurate fusion of 3D optical scanning data and 3D measurement data.The target ball is introduced into the measurement process, and the target sphere is measured by CMM and optical scanner respectively. The transformation matrix of the data is calculated according to the position of the ball center in different measurement data, and the data fusion is realized.In the process of calculating the spherical center of 3D optical measurement data, the spherical data is extracted preliminarily according to the characteristics of the sphere, and then the RANSAC algorithm is introduced to accurately extract the spherical data, which improves the accuracy of the calculation of the spherical center.The research results show that: the problem of measuring the contour and hole characteristics of honeycomb core is solved effectively, the measuring efficiency and precision are improved, and the accurate fusion of different measurement data is realized.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB33

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