Research On The Slicing Technology In Rapid Prototyping And Manufacturing

Rapid prototyping and manufacturing(RP&M) plays an important role in reducing the time required for new product development and lowering development costs. The emergence of RP&M is vitally an important technical innovation in manufacturing. Although building physical parts with different techniques has become popular, intersecting a CAD model with a plane in order to determine two dimensional contours on which material is to be deposited is the foundation for the various RP&M processes. Therefore, the study of slicing methods has become an important subject of RP&M techniques.To fulfil the requirements of morden integrated manufacturing system, a new method, which takes the STEP-NC as the uniform data exchange formats, is put forward. It has been pointed out that the key problem to construct integrated system of RP&M is to realize the slicing technology based on STEP-NC.A method of generating realistic image view for STL model has been proposed. By setting a critical angle to select appropriate common point and recalculate the vector, the redundancy problem of vertex coordinate in STL model is solved and the model looks smoother. A stereo display system is developed by calling functions from OpenGL graphic library through VC++. The developed system is conducive to slicing process of STL model.On the basis of analyzing the slicing technology and absorbing the merit of current algorithms for slicing STL model, a new algorithm has been put forward. In the strategy, the grouping matrix was established by sorting for the triangular facets according to the minimum and maximum z-axis value of the triangular facets. Then the contour segments were generated by marching from edge to edge. Applications are made to show that the approach is efficient, stable and reliable.Based on a systematic analysis and comprehension on the expression of STEP-NC geometry model, the map between EXPRESS and C++ was studied. The module of map has been developed as a dynamic link library, which facilitated the expansion of system. In order to ensure the coherence and availability of collected data, a module to obtain feature data has also been designed. The reading and analysis for AP203 neutral file has been realized so that the feature information in the geometry model could be extracted.The key problem of the slicing for STEP-NC geometry model is realizing the algorithm of intersection between the slicing plane and the geometry element. Different algorithms have been designed aim at various geometries so that the special property can be utilized sufficiently. Hence this algorithm is more efficient and reliable.Through in-depth research and analysis for the existing technique of seanning and hatching, a new composite filling method, which combined profile offset and region hatching by grouping the point of intersection, has been put forward. The presented way can make use of the property of high quality and efficiency separately in profile offset and region hatching. And it adapts to various technics in RP&M. In order to implement the proposed method, a vector excursion is utilized to compute the profile offset. The group algorithm of intersections, which reduced the process of partiton and anvanced the efficiency, is also used to relize the region hatching.