Solid Edge工程图设计中的两个问题

一、隐藏视图 在Ｓｏｌｉｄ Ｅｄｇｅ的工程图环境设计三维模型（＊·ｐａｒ,＊·psm,＊．ａｓｍ）的工程图时,有时需要隐藏整个或部分视图。如要生成剖视图,必须先生成一个投影视图,在上面添加剖面分割线,然后再生成剖视图。有时我们只需要剖视图,而不需要与之关联的投影视图。但如果直接删除该投影视图,与之关联的剖视图也就会消失。又如要在一个投影视图上作一个局部剖,则必须隐藏部分线条,这时就必须要用到隐藏视图的技术。归纳起来,隐藏视图的方法主要有以下几种。 第一种方法是通过右键快捷菜单先把要保留的剖视图转换为工…     

基于Inventor软件的肋板剖视图制作方法

基于Inventor讨论了三维CAD软件生成的剖视图存在与GB国标不一致的问题。本文充分挖掘了Inventor三维实体转换平面工程图的功能,以肋板结构为例,提出了处理图形的方法与技巧,解决了与GB国标不一致的问题。并指出三维软件在创建平面工程图时存在不少缺陷,用户不仅要深入了解软件本身的功能,还须具备扎实的工程制图知识。     

三维零件模型的工程图输出系统

本文在通用绘图软件AutoCADR12平台上研讨了三维零件模型的工程图表达形式，着重分析了三维零件模型的三视图、剖视图的工程表达方式以及零件尺寸的自动化标注，提出了在AutoCADR12上实现它们的原理和途径。同时，系统补充了图幅及格式的确定、局部放大、形位公差及表面粗糙度的标注等工程图表达的辅助形式，以符合实际工程的要求。     

三维零件模型的工程图输出系统

本文在通用绘图软件ＡｕｔｏＣＡＤＲ１２平台上研讨了三维零件模型的工程图表达形式，着重分析了三维零件模型的三视图、剖视图在工程表达方式以及零件尺寸的自动化标注，提出了在ＡｕｔｏＣＡＤＲＥ１２上实现了它们的原理和途径。同时，系统补充了图幅及格式的确定，局部放大、形位公差及表面粗糙度的标注等工程图表达的辅助形式，以符合实际工程的要求。     

三维造型设计与工程图学的有效融合

随着计算机软硬件技术的普及和飞速发展以及制造业对二维计算机绘图以及三维设计造型技术日益增长的需求,在工程图学教学中有效地融入二维计算机绘图以及三维设计造型技术已显得尤为重要。论文介绍了北京理工大学在工程图学和三维造型创新设计方面“外挂式、分段式和融合式”三种模式的教学改革实践,并着重对如何将三维造型设计与工程图学有效地融合进行了论述。     

定制符合国家标准的Pro/ENGINEER工程图模板

各企业在Pro/ENGINEER工程图的绘制上都有不同的要求,现代企业都在提倡团队协作设计,因而为保证整个设计团队设计的一致性,预先设置好工程图模板就十分重要了.     

大规模整机装配三维设计方法探讨

一、引言 当前,三维设计在机械零部件方面得到全面的应用,开始向机、电、液一体的整机设计方向迈进,5000个零件左右规模的部件以起重机桥架、锻压机本体为代表达到成熟应用的阶段.但其工程图生成时系统的速度滞后现象也开始出现,打开文件、剖视图生成等个别命令响应速度达到4、5分钟.在整机装配时,零件个数达到万件以上,死机、常用命令滞后一分钟和打开文件半小时以上的现象十分普遍,使得绝大部分产品总装无法执行,只能分部件显示或开始探索部件的简化方法.显然,有必要对软件功能做全面的研究,探索一种新的整机装配模式.     

三维重建中的剖视图处理

剖视图处理能够有助于更好地理解视图,提高三维重建的效率。基于对剖视图自身特点的分析,提出了三维重建中对剖视图的处理算法,即通过剖视图信息的智能提取生成基元体,将基元体同由视图轮廓生成的参照体进行布尔运算,从而得到最终的目标体。算法能够处理包括全剖视图、半剖视图以及平行剖视图在内的剖视图,最后给出了应用算例以验证算法的可行性。     

使用Solid2000在工程图中标注工程信息

工程图样是现代工业生产的重要技术文件,是设计师表达设计思想,进行技术交流,组织生产和加工的重要文件。国家标准对工程图中工程信息的标注有详细规定,设计人员在绘图时必须严格遵守,以便生产部门科学、精确地进行生产与管理。在工程设计过程中,工程图中工程信息标注的工作量占设计工作的一半以上,因此,操作简便、完全符合国标的标注方式可以大大提高设计效率。国产的三维CAD软件Solid2000比较适应国标化的应用需求,其所采用的单一数据库技术提供了三维模型与二维工程图双向关联的功能,可以随时由3D实体模型自动产生符合国标的2D工程视…     

基于增强现实的地下管线真实感可视化方法

为便于城市地下管线的铺设与维护,提出一种基于增强现实的地下管线真实感可视化方法,将原本不可见的虚拟地下管线真实地呈现在视频画面中.首先将屏幕空间分割为对地下管线具有不同遮挡语义的4个区域;然后借鉴工程图学中的剖视图方法,采用沿地下管线走向的坑道式剖切和地表面的竖直剖切方法来展示被遮挡的地下管线;进而根据画面的遮挡语义,运用视频中地表遮挡物和地下管线的重要视觉特征,揭示地下管线与地表物体之间的正确遮挡关系;最后利用渐变融合对地下隐藏信息与真实场景视频进行合成.实验结果表明,该方法不依赖于三维场景的精确几何重建,可在GPU上实时实现.     

Geometric model simplification for distributed CAD

Visualization of CAD models in distributed design environment is an essential feature to support collaborative design. To efficiently transmit and render CAD models geometric simplification can be applied to CAD models. However, it is difficult to use available general geometric simplification algorithms because these algorithms are not designed to handle mechanical CAD parts. Applying general simplification on a CAD model would result in distortion of design features and make them unrecognizable to viewers. In this paper, a novel approach is proposed to exploit trimming information in CAD models to simplify their geometry. Visibility culling is integrated into this approach to facilitate selective refinements. The work introduced here aims to support visualization of multiple CAD models in a distributed CAD environment. Implementation details are included and case studies are demonstrated.     

Computer assistance in design engineering

The design engineering process is analysed from a cognitive ergonomics point of view, relating it to models of problem-solving and cognitive skills. Observations from several Swedish studies are discussed in this framework. Results indicate that CAD systems require some re-thinking; in particular concepts related to the computer storage have to be incorporated in the problem space of design. As to heuristics, CAD systems seem to offer a wide variety of working. Cognitive skills related to CAD seem to be easily acquired, although the transition between different CAD systems will cause some initial problems. In general it is found that current CAD systems mainly support the detail design phase. Some ideas for future systems which would support the conceptual design phase in addition are discussed.     

Design reuse oriented partial retrieval of CAD models

As a huge number of 3D CAD models is generated each year, retrieval of 3D CAD models is becoming more and more important for achieving design reuse. However, the existing methods for partial retrieval of 3D CAD models are very few and far from the requirements of design reuse. In this paper, we present an approach to partial retrieval of 3D CAD models for design reuse. The criteria for determining whether a subpart of 3D CAD models is reusable for design is defined first. Based on the criteria defined, all the design reusable subparts involved in the 3D CAD models in the library are automatically extracted and stored in the library as reference models. Moreover, each design reusable subpart in the library is represented by all its local matching regions in a hierarchical way so as to support multi-mode partial retrieval. In our approach, three partial retrieval modes including normal retrieval, exact retrieval and relaxed retrieval are defined to meet various partial retrieval requirements of design reuse such as the incomplete and vague queries during the early design stage. And the multi-mode partial retrieval is achieved by performing multi-mode matching and similarity assessment between the query and the design reusable subparts in the library indexed by bitmap. Experimental results are presented to demonstrate the effectiveness of the approach.     

Knowledge engineering and CAD

The technology of Computer Aided Design (CAD) has rapidly been changing the processes of machine design, especially in detail and production design. Conventional CAD systems are necessary in production design where precise geometrical data are indispensable, but we can point out some problems of those systems from a point of view of the total machine design process. Though the main aim of introducing CAD systems is to increase designers' creativities, it is doubtful whether designers are really supported by such CAD systems. We think that knowledge engineering is useful to improve such situations. In this paper, we discuss these problems and we study the feasibilities of future CAD systems that can really help designers very intelligently and efficiently. We also show some results of our experimental systems applying knowledge engineering.     

Automation in the design of EDM electrodes

Plastic parts, especially those designed for consumer electronics products, are becoming more compact and freeform in shape. This requires the construction of compact and delicate geometric features in the injection moulds that produce these parts. It is now common practice to employ electric discharge machining (EDM) whenever the conventional machining process fails to machine such delicate features. Although CAD/CAM systems are widely used in mould design and manufacturing, and specific commercial CAD/CAM systems that are customized for injection mould applications are also available, there are still no intelligent CAD tools that address the specific requirements of EDM electrode design. The aim of this research is to develop an intelligent CAD tool that supports EDM electrode design. This CAD tool uses a new technique that recursively splits the EDM region into sub-regions until machinable electrodes can be constructed. The CAD tool has been implemented and integrated into a commercial CAD/CAM system, and 40 different real designs has been used to test its capability in handling a wide variety of geometric shapes. Performance data show that the efficiency of the design process can be improved by at least 50%, with a potential to achieve 85% through improved implementation and further research.     

Integrated CAD development for building services engineering

The potential benefits of CAD in building design are well established. In reality most production CAD systems are developed in response to the particular requirements of users who are architects or building engineers. These requirements are often fragmented. They relate to different aspects of the complete building engineering design cycle and are often specified by different users at different moments in time. The role of the CAD systems developer is to design a coherent software system and to establish a consistent set of user interface conventions with which an integrated solution of these different requirements can be provided. This paper describes how this methodology has been successfully applied to an important aspect of CAD relating to building services engineering.     

Design gene based secure mechanism for collaborative product development

In collaborative product development, a CAD model needs to be effectively shared among partners to facilitate co-design. In the meantime, it is essential to preserve the intellectual property information (design knowledge) of the shared CAD. To resolve the above dilemma, this paper presents a novel approach to share CAD models to support collaboration, as well as conserving confidential design knowledge in the models. The motivation of the approach is to develop collaborative mechanisms pertaining to an innovative concept of design genes, which imitate biological genes that are responsible for the heritable characteristics of an organism during evolving. The approach consists of the following steps. Firstly, design genes are defined to represent the design knowledge in CAD models. Secondly, a filter is introduced to retrieve design genes from the CAD model flexibly. An encryption algorithm is then designed to encrypt the design genes, and ensure the geometrical validity of the model to support effective collaboration. Finally, case studies are used to validate the developed approach. The complexity of the case studies can demonstrate that the approach is applicable to real-world application scenarios.     

Selecting and evaluating CAD systems

This article discusses some of the factors to be considered when selecting and evaluating systems for CAD (computer-aided design). An operative CAD system is one which performs a particular design function (application) by employing software running on suitable hardware.

Although the selection of an application of software and of hardware, are usually interdependant, they are treated separately within the article. The first two sections are concerned with identifying design problems which are suitable for the application of CAD. These sections are followed by a summary of the factors to be considered in choosing software and hardware. The final sections discuss the costing and economics of CAD systems.     

Cad-induced changes in design work

CAD systems are a new aid for design processes that can be used to solve both simple and complex tasks. Sometimes, it is possible to perform tasks, such as the dynamic simulation of movement and finite element analysis, which could not have been done without the aid of computers. But, even the ability of the computer to perform less time-consuming tasks leads to changes in design activities. Advances in design methodologies and organization have been made, leading to better fulfillment of functions, better manufacturing-oriented design, and better scheduling of design and manufacture. Using computers for design, new design processes have become possible due to the computational speed and large storage capacity of modern computers, and to advances in software. The process of merging conventional and computer-aided design processes for a new computer-aided design technology is not finished: a methodology based on CAD still has to be developed. This paper will explain some developments in CAD systems that are changing the design activities. The aim of CAD systems development is to change the need for the designer to work within the limited possibilities of today's CAD systems. In the new systems, support will be easier and the information will be better integrated so that they can better serve the design demands.     

Virtual DesignWorks—designing 3D CAD models via haptic interaction

Haptic devices (force feedback interfaces) show great promise for use in the design of CAD models. However, current haptic systems are used primarily to verify rather than to interact with CAD systems to design a model.The paper discusses a haptic-based CAD system—Virtual DesignWorks. It is the world's first haptic application for the design of CAD models based on component technology (COM+). With haptic devices, the system allows engineers, in virtual space, to directly touch a native B-Rep CAD model, and deform it by pushing, pulling and dragging its surfaces in a natural three-dimensional environment. Virtual DesignWorks adopts the novel COM-based haptic model, which demonstrates significant advantages compared to the traditional haptic models. Force feedback gives designers the greatest flexibility for the design of complex surfaces, and haptics has the potential to become a critical interface for design applications.