Research On Curve Reconstruction And Corner Feature Extraction Of Cross-section Line Point Cloud Data

Ring forging is a kind of heavy industrial parts with many materials and large quantities.Because ring forgings are often in the harsh environment of long working hours,high temperature,high pressure,high speed,high and low frequency vibration,the quality and accuracy of forgings are very strict.In the forging process,not only the excellent forging process of ring forgings should be carried out,but also the higher requirement for on-line measurement of ring forgings should be put forward.The accuracy of measurement indirectly determines the quality of ring forging products.As one of the classifications of ring forgings,ring forgings with special cross-section have complex rolling deformation.To produce ring forgings by ring rolling process,various problems in rolling process must be studied and solved thoroughly from the aspects of blank,pass and rolling process parameters.Because of the complex environment of forging site and the influence of forging process,there are a lot of complex noises in the measurement data.It is difficult to measure the cross-section line of ring forgings with special cross-section from the point cloud with noise.Therefore,it is necessary to reconstruct the curve of the cross-section point cloud and extract the characteristic corner points.These work can help to improve the rolling quality and performance of ring forgings with special cross-section,avoid redundant subsequent processing operations,improve production efficiency and save production costs.In this paper,the algorithm of reconstructing section line and extracting characteristic corner of ring forgings with special section is studied.The specific contents are as follows:Firstly,based on the theory of reconstructing curve by field function,the potential value of scanning point cloud of cross-section line is given and connected graph is constructed.Then,the initial curve reflecting the change of cross-section shape is extracted by the shortest path algorithm.Finally,the Lagrange-Projection method is proposed to adjust the initial curve locally to obtain a smooth projection curve.Secondly,the theory of curvature scale space is optimized by the adaptive calculation method of design scale,and then the sparse parts are filled with the distance weighted inverse ratio interpolation method.The filling points of each scan period and the reconstructed curve points are measured for similarity,and the neighborhood curve sets are constructed.Neighborhood curve is smoothed by self-adaptive scale to perform feature enhancement operation,which can effectively extract feature corners.Finally,based on the experimental system of on-line detection of cross-sectional line of ring forgings,experiments are carried out on second-order and third-order special-section ring forgings respectively.According to the algorithm designed in this paper,cross-sectional data are processed and error analysis is carried out to verify the effectiveness of the proposed algorithm for reconstruction of cross-sectional line and feature corner extraction.