Research On Key Technologies Of The Data Pretreatment In Decomposed Injection Sculpturing

The precision, strength, and efficiency of the prototype manufactured by the Rapid Prototyping processes based on the layered manufacturing are not fully up to expectations because of the limitation of their prototyping theory. Decomposed Injection Sculpturing (DIS) is a novel RP process, which combines the discrete/additive process and Numerical Control (NC) machining. DIS possesses the characteristics of both the flexibility of RP and the high precision of NC machining. In order to promote the further study of DIS and to accelerate the process of putting DIS into practice, several key problems are studied, which are mainly relevant to the development of software for the pretreatment of the STL model used in DIS and for the distributed collaboration in distributed RP manufacturing. The finished work is as follows:(1) General analysis and design for DIS system software: On the base of analysis of the process and equipment of DIS, the functional analysis and general design for DIS system software are accomplished, which include the modularized architecture and efficient Data Structures. Two new algorithms are presented respectively for rebuilding the topological information of STL and searching the adjacent facets under the given conditions.(2) Research on the three-dimensional decomposition of the triangular mesh: The basic theory of the 3-dimensional decomposition of CAD model for 3-axis NC machining and the basic principle of 3D decomposition for DIS are presented. Several algorithms are put forward for the 3D decomposition of STL, which include the 3D decomposition algorithm based on Extended Z-Buffer model, the algorithm based on the silhouettes with direction, the algorithm for the model which can be decomposed into two sub-parts, and the decomposition algorithm using plane. The details about the implements of these algorithms are keenly studied.(3) Research on processing local features in the triangular mesh: The analysis, definition and classification for the feature of STL used in DIS are given, and the presentation and recognition method for the local feature is presented. The machining feasibility of the local feature is discussed, and the verifying algorithm based on the offset of contour line is presented. And some special process plannings are demonstrated for some typical local features which can't be manufactured directly.(4) Research on the generation of Contour Tool Path from the triangular mesh: The research on generation of the tool path from STL is insufficient at present, and the existing research is mainly about the parallel tool path. The algorithm for the generation of contour tool path from STL is presented, which consists of twice offsets. The algorithm comprises the offset of STL, the generation of the transition line, the slicing of the offset STL model, the second offset of the temporary path, and the elimination of the interference in the tool path.(5) Research on the realization of the distributed collaboration in the RP software: A hybrid architecture for the distributed collaboration in RP is put forward based on the analysis of the entire procedure of the RP collaboration and the information transportation. The asynchronous information of collaboration is transported by B/S. And synchronous information is transported between the IE control embedded in the web page and the special collaborative server, just like C/S. Some work are accomplished such as the development of the ActiveX control with Document/View frame, menu, tool bar and status bar, the realization of the synchronous information transportation, the replay of the synchronous collaboration.The innovations in this paper mainly include such as follows: 1. The decomposition of CAD model is truly 3-dimension according to the geometrical characteristics of part models; 2. Based on the classification, recognition and machining feasibility verification of local features on the CAD model, the special process plannings are presented for enhancing the prototyping capability of DIS; 3. An algorithm including twice offsets is presented for the generation of contour tool path from STL for bull mill, which can simplify the computational complexity and improve computational efficiency.