Research On The Free-form Surface Feature Extraction Method Of Complex Ring Forging Based On Topological Homogeneous Transform

Complex ring forgings,such as aeroengine turbine casing,nuclear power barrel cone,pressure vessel flange rings,are important connecting and bearing components of heavy equipment.They are widely used in mechanical manufacturing fields such as wind power,nuclear power,aerospace,petroleum and petrochemical equipment.In the rolling process,the shape and geometric dimension of the key parts of the ring forging are determined by the free-form surface characteristics of the complex ring forging outline.It is an important basis for judging whether the ring forging product meets the deformation quantity and quality required by the rolling process,and for accurately identifying the shape outline of the ring forging in the rolling process of the complex ring forging.Characteristic information is of great significance to improve the internal forming quality of complex ring forgings and the technology level and efficiency of ring rolling.In this paper,the problems of insufficient utilization of point cloud data in feature extraction of free-form surface,drift and crowding of point cloud coordinates of free-form surface under geometric transformation,unilateralization and discretization of free-form surface model are studied,aiming at exploring accurate and efficient rolling process of complex ring forgings.The feature extraction method of free-form surface of shape contour can guarantee the forming quality of ring forging,improve its production efficiency and market competitiveness.Specific research work is as follows:Firstly,based on the actual production conditions of complex ring forgings and the characteristics of point cloud data structure,the noise elimination and dynamic deviation tracking compensation methods of original sampling point cloud information are studied,and the point cloud data of complex ring forgings contour are constructed.Based on the geometric feature structure of data,the data analysis method considering the local neighborhood structure and global internal correlation between scattered point cloud sets is studied,and the topological space of point cloud information of complex ring forging contour is constructed,which lays a theoretical foundation for the extraction of complex ring forging contour features.Then,based on the constructed point cloud topological space of complex ring forging contour,the influence of point cloud data on the overall and detailed characteristics of point cloud model is studied.A rigid spherical meshed free-form surface model is constructed.Based on the theory of topological transformation,the topological homeomorphic transformation mapping of free-form surface model is constructed.The method of homeomorphic transformation of free-form surface model of complex ring forgings is studied to realize the topological homeomorphism of free-form surface model before and after geometric transformation,which lays the foundation of model analysis for feature recognition of free-form surface.Secondly,aiming at the problems of curvature,normal direction inconsistency and discontinuity in the free-form surface model of complex ring forging topological transformation,the smoothness and orientation of the free-form surface model of complex ring forging topological transformation are studied based on the theory of topological differentiation,and the tangent cluster analysis model of the free-form surface of topological transformation is constructed to solve the complex ring forging.The tangent vector matrix of any point on the free-form surface of the forging contour is used to realize the continuity analysis of the change trend of any point on the free-form surface of the complex ring forging and its adjacent area.Based on curvature and extremum continuity analysis,the solution method of relative position information between feature points is studied,which lays a foundation for feature points extraction of free-form surface of complex ring forgings.Finally,the feature extraction method of the complex ring forging profile free-form surface proposed in this paper is applied to verify the feature extraction effect of the complex ring forging profile free-form surface by laboratory test and field measurement contrast test.Firstly,the complex ring forging test workpiece is heated,and the hot ring forging under high-speed rotation and high vibration is scanned by laser to obtain its contour scanning point cloud.Then,the point cloud information is successively de-noising,dynamic error tracking compensation and feature extraction experiments.Then,based on the actual production site of ring forging,two different feature extraction algorithms are proposed Experiment comparison.The research shows that the feature extraction offree-form surface of complex ring forging based on topological homeomorphism transformation proposed in this paper has achieved the expected effect and the method is accurate and feasible.