MBD Model Construction Methodology For Manufacturing Feature Of Large Thin-wall Part Of Spacecraft

The large thin-wall part of spacecraft is the main bearing part on launch vehicle.With large numbers of complicated features with curved surfaces,it leads to a great tough preparatory technical work like the process planning and CNC programming in parts' machining.Feature based CNC programming technology is a solution based on the information of machining feature,also it can integrate processing knowledge and experience effectively.Therefore,it's the key link to realize the automation and intelligence of CNC programming.So it's with great theoretical significance and application value to do research on the MBD model of manufacturing feature construction methodology.A methodology is presented in this thesis studies around manufacturing feature construction with the information from a part's MBD model.The specific contents include:On the manufacturing feature recognition issue,with consideration of characteristics of large thin-wall part,a methodology is presented to solve the problem of recognizing both isolated and composite features.Firstly,a hierarchical attributed adjacency matrix(HAAM)model is put forward to represent the CAD model of both part and feature,describing models' topological geometrical and special relationship information.Owning to the topological layer of HAAM,the adjacency and concavity and convexity between geometrical elements is described very well.Then,an algorithm based on edge's convexity is designed for feature searching.By the information from the special relationship layer of HAAM expressing the complex structural correlation among features,the features belong to the same convex-connected feature are revised and merged.With the help of geometrical layer of HAAM,the concave-connected features division problem is solved.A combination use of topological and geometrical layer of feature's HAAM makes the isolated feature recognition work accurately and efficiently.On the basis of automatic manufacturing feature recognition,a MBD model of manufacturing feature construction methodology based on MBD model is proposed.First,a MBD model of manufacturing feature aiming to describe the feature's form and the technical requirements information is designed.The information of the model is organized in three level: the tier of feature form information,the tier of geometric elements information in the feature and the tier of technical requirements information related to geometric elements.The model is established by extracting the geometric information and non-geometric information from the MBD model and making them organically integrating into together.Taking advantage of the clearly impressed feature information of manufacturing feature's MBD model,the process panning and NC programming of a feature will be easier.Based on the research above,a system of the model construction methodology is realized on the Pro/E platform.The research achievement of this thesis provides some new methods for the realization of automatic and intelligent CNC programming work in large thin-wall spacecraft part manufacturing.The enterprise application shows that the recognition method improves production efficiency and reduce production cost,which tests and verifies the effectiveness of the methods.