Study On The Surface Registration Technology Of 3D Ship Hull Plate Bending Machine

With the technology of adjustable mold and no-pair square press head,the 3D Ship Hull Plate Bending Machine can solve the defects of formed plates,process the fair and almost none creasing three-dimensional curved surface plate with high quality and high efficiency.After several "lower die adjustment-upper die punch-surface measurement",the plate's springback can be controlled and precision can be guaranteed.While being adjusted firstly,the lower die is adjusted to the theoretical surface,and springback value is considered during the latter adjustment.During the process of unloading the upper die,the plate's shape changes firstly because of springback,then position changes because of constraint losing,which leads to space position deviation between theoretical surface and formed surface,affecting the accuracy of the extracted springback value and next adjustment of lower die.It is Surface Registration technology that relates to reducing the position deviation between 2 surfaces to get more accurate springback value.This paper studies on the Surface Registration of 3D Ship Hull Plate Bending Machine,the main contents are as follows:1.Considering the actual production situation of machine,the bad edge point is corrected.Based on the "point-triangle" approach,the theoretical surface is divided into a high-density triangle mesh to approximate characterize the theoretical surface;2.The KD-Tree structure of grid points of triangle mesh is established to find the closest grid points of every measured point in the triangle mesh,which lays the foundation of Surface Registration;3.The measured surface is positioned initially to reduce the relative positional deviation between the theoretical surface and measured surface firstly,which provides a better initial condition for the ICP(Iterative Closest Point)algorithm.Then,based on KD-Tree(K Dimension Tree),using SVD(Singular Value Decomposition)to get transfer matrix,the optimal fit is made with ICP;4.After implementing the above 1?2?3 by means of using MATLAB / C mixedprogramming manner,next job is to identify a springback calculation method and use cloud image to display distribution of sprinbgback.After applying surface registration to different types of plates,the result shows: the springback changes very little with different density of triangulation of theoretical surface,and compared with unusing surface registration,surfaces registration in this paper can improve the springback distribution and reduce the mean springback value.