An algorithm for compensating the varying section contour within the extent of each layer thickness is proposed to improve the rapid prototyping part’s shape and size precision.
Abstract： Hand drawings and two dimensional （2D） CAD drawings have been replaced by three dimensional （3D） CAD models in mechanical design, but some 2D drawings produced before are needed in the new design. Howev...Abstract： Hand drawings and two dimensional （2D） CAD drawings have been replaced by three dimensional （3D） CAD models in mechanical design, but some 2D drawings produced before are needed in the new design. However, the techniques and software packages for automatically converting 2D drawings into 3D-CAD models with high precision have not yet been developed due to the difficulties to verify the validity of the drawings, to decide the hidden lines and eoncavo-convex faces, and to represent free-form surfaces. In addition, it is very time consuming to manually convert a large number of 2D drawings into 3D CAD models. To address these problems, we propose an approach for converting 2D drawings into 3D-CAD models automatically.展开更多
3D CAD模型长期保存困难重重。为此,国际航空工业界推出LOTAR(LOng Term Archiving and Retrieval)项目,旨在建立、测试、颁布并维护3D CAD模型长期保存和获取所需要的标准,目前其主要成果是NAS/EN 9300系列标准。而汽车工业产品数据标...3D CAD模型长期保存困难重重。为此,国际航空工业界推出LOTAR(LOng Term Archiving and Retrieval)项目,旨在建立、测试、颁布并维护3D CAD模型长期保存和获取所需要的标准,目前其主要成果是NAS/EN 9300系列标准。而汽车工业产品数据标准战略联盟通过LTAR(Long Term Archiving&Retrieval of Digital Product Definition Data,LTAR)项目已经形成了一套完整的建议体系,包括四个部分:文件格式、存取流程、保存时间、质量保证。目前,国内还未有国家或行业层面的3D CAD模型长期保存策略。借鉴电子文件前端控制和全程管理的思想,通过3D CAD模型生成时的模型质量控制措施、流转过程中的更改和版本控制以及归档后的物理与逻辑实体控制措施,确保3D CAD模型长期可读、可理解。展开更多
提出了一种基于CAD零件离散体素模型的异质材料建模方法,重点对多材料模型和功能梯度材料模型建模进行阐述,提出固定参考特征活动梯度源(Fixed reference features ＆ active gradient sources,FRF＆AGs)的概念,引入复合AGS和不同方向FR...提出了一种基于CAD零件离散体素模型的异质材料建模方法,重点对多材料模型和功能梯度材料模型建模进行阐述,提出固定参考特征活动梯度源(Fixed reference features ＆ active gradient sources,FRF＆AGs)的概念,引入复合AGS和不同方向FRF的建模算子,提高异质材料/零件建模的效率和灵活性。并将传统CAD实体建模的交、并、差等布尔算子扩展到异质材料零件的建模中。最后给出了设计实例。展开更多
基金Supported by College Science Foundation of Jiangsu(07KJB460113)
文摘An algorithm for compensating the varying section contour within the extent of each layer thickness is proposed to improve the rapid prototyping part’s shape and size precision.
文摘Abstract： Hand drawings and two dimensional （2D） CAD drawings have been replaced by three dimensional （3D） CAD models in mechanical design, but some 2D drawings produced before are needed in the new design. However, the techniques and software packages for automatically converting 2D drawings into 3D-CAD models with high precision have not yet been developed due to the difficulties to verify the validity of the drawings, to decide the hidden lines and eoncavo-convex faces, and to represent free-form surfaces. In addition, it is very time consuming to manually convert a large number of 2D drawings into 3D CAD models. To address these problems, we propose an approach for converting 2D drawings into 3D-CAD models automatically.
文摘3D CAD模型长期保存困难重重。为此,国际航空工业界推出LOTAR(LOng Term Archiving and Retrieval)项目,旨在建立、测试、颁布并维护3D CAD模型长期保存和获取所需要的标准,目前其主要成果是NAS/EN 9300系列标准。而汽车工业产品数据标准战略联盟通过LTAR(Long Term Archiving&Retrieval of Digital Product Definition Data,LTAR)项目已经形成了一套完整的建议体系,包括四个部分:文件格式、存取流程、保存时间、质量保证。目前,国内还未有国家或行业层面的3D CAD模型长期保存策略。借鉴电子文件前端控制和全程管理的思想,通过3D CAD模型生成时的模型质量控制措施、流转过程中的更改和版本控制以及归档后的物理与逻辑实体控制措施,确保3D CAD模型长期可读、可理解。
文摘提出了一种基于CAD零件离散体素模型的异质材料建模方法,重点对多材料模型和功能梯度材料模型建模进行阐述,提出固定参考特征活动梯度源(Fixed reference features ＆ active gradient sources,FRF＆AGs)的概念,引入复合AGS和不同方向FRF的建模算子,提高异质材料/零件建模的效率和灵活性。并将传统CAD实体建模的交、并、差等布尔算子扩展到异质材料零件的建模中。最后给出了设计实例。
