Technological Realization From Physical Manufacture Basis To 3D Digital Model

With the development of aviation design and manufacturing technology,the traditional aircraft physical manufacturing is reconstructed based on 3D digitalization,which is conducive to increasing the cooperative production capacity of the aviation manufacturing industry,improving the efficiency of aircraft modification and reducing the cost of production suspension.However,it is difficult to convert the aircraft physical manufacturing reference into a digital model not only due to its diversity in categories,structural forms,size differences and surface information but also its complexity in contour and scribing information.In order to realize 3D digital modeling of aircraft physical manufacturing,this thesis focuses on three steps of reverse modeling,namely,on-site measurement,data processing,and digital modeling to explore a 3D digital modeling process scheme suitable for aircraft physical manufacturing.This thesis sorts out the various physical manufacturing reference required for aircraft manufacturing,and extracts its design elements and the factors that influence measurement and digital modeling.Based on the rapid development of photoelectric measurement technology in recent years,the three methods of contact measurement,i.e.photogrammetry,structured light scanning measurement and optical tracking,are used to realize the high-precision acquisition to the geometric shape,surface scribing and other design elements,as well as the unification of the coordinate system in the subsequent modeling of the acquired data.Meanwhile,in order to achieve the rapid measurement,corresponding measurement strategies are formulated according to the size,form and complexity of physical manufacturing reference.The data obtained by the measuring device has many redundant points and is usually in disorder.In order to meet the subsequent modeling requirements,improve the measurement data quality and the calculation efficiency for modeling,the measured point cloud data is triangulated and the data fusion,data simplification and noise deletion are performed at the stage of data preprocessing.And the noise deletion,data grouping and sorting preprocessing are carried out on scribing data.At the stage of digital modeling,the process and implementation scheme for 3D digital modeling is established,which contains coordinate system establishment,point cloud data fitting,scribing data fitting and curved line and surface fusion.In the specific implementation process,based on the curved surface contour,the benchmark scribing and other key measurement data,the digital modeling method combined with the theoretical two-dimensional drawing is used to greatly improve the overall efficiency in measurement and modeling.The 3D digital modeling scheme against physical aircraft manufacture reference has been proved feasible by the completion of on-site measurement,data processing and digital modeling of the typical test part.And by checking difference of digitized model from measured point cloud,and that from the current 3-coordinate measurement points,the reliability of 3D digital modeling scheme is verified and the digital modeling accuracy meets the engineering application requirements.