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1.
计算机辅助工艺设计的主要任务是对被加工零件选择合理的加工方法和加工顺序。本文提出一种个用于变曲工步设计的几何模型,此模型已成功地用于汽车冲压件工艺卡创成系统中,解决了弯曲展开、弯曲工序设计,产品几何建模等关键技术。  相似文献   

2.
正论述了应用Pro/ENGINEER软件在Intralink环境下完成柴油机数字化设计的自顶向下建模准则和方法,以曲轴几何建模实例介绍了柴油机通用零部件几何模型的细化过程,体验了"顶层总体控制、逐级细化完善、并行协同设计"数字化建模方法的高效实施。  相似文献   

3.
自顶向下的设计模式符合一般的设计规律,而以几何建模技术为主的各种CAD系统难以真正地对这一过程提供支持。本文介绍了一种基于功能单元和功能特征的产品功能模型,它能够表达产品的功能结构和功能关系,并建立对零件形状特征的功能约束。功能建模系统同基于特征的产品建模系统相连接,能够实现自顶向下的产品设计。  相似文献   

4.
计算机辅助工艺设计的主要任务是对被加工零件选择合理的加工方法和加工顺序。针对冲压弯曲件工艺设计包括的弯曲工步设计和弯曲件平面几何展开等主要内容,本文提出一个用于弯曲工步设计的几何模型,此模型已成功地用于汽车冲压件工艺卡创成系统中,解决了弯曲件展开、弯曲工序设计、产品几何建模等关键技术  相似文献   

5.
Computer Aided Drafting,Design and Manufacturing(计算机辅助绘图设计与制造(英文版))创刊于 1991 年 12 月。《CADDM》是中国工程图学学会主办的全国一级英文学术刊物。《CADDM》在国内外公开发行。该学报面向制造业和工程建设业中有关产品几何形状的数字化建模技术,及时反映其研究、开发和应用的最新有关成果。内容涉及计算机图形学、计算机辅助几何设计、设计几何、CAD/CAM 技术、CAE分析用产品数据的前置处理、计算机辅助工艺过程设计、产品装配规划、产品数  相似文献   

6.
本文以某柴油机高压油管设计为例,基于Pro/ENGINEER平台提出利用骨架模型实现高压油管自顶向下的三维布置设计方法和步骤。通过建立关联几何对象的骨架模型,并以骨架模型为桥梁进行自顶向下的设计信息传递,从而实现高压油管设计过程的参数化驱动。  相似文献   

7.
从过程系统的角度说明了面向对象概念,完成了对化工过程的多层次抽象,建立了近20个化工类,并提出了用面向对象方法建立化工单元和过程系统面向方程模型的思想。文中介绍了化工类库的分类方法,类库定义、类库组织形式和面向对象建模机制等,可以看出,面向对象方法能快速、方便地建立新的化工单元和系统的面向方程模型,克服了传统设计方法中面向方程法模拟流程难以建模和利用已有模型产生新单元模型的缺点,为迅速、有效地建立化工模型探索了一条新途径。这也是作者提出的基于Windows的面向对象化工过程计算机辅助开发环境─OOCP的核心内容。  相似文献   

8.
变动几何约束网络的运动学模型及其应用研究   总被引:6,自引:1,他引:6  
引入机器人学中的运动学分析方法研究了变动几何约束网络的运动学模型。基于ISO/TC213的特征分类,定义了三类变动几何约束(VGCs)给出变动几何约束网络(VGCN)的概念;基于旋量参数研究变动几何约束网络的运动学模型,给出此模型的一般表示式;并研究了此模型在计算机辅助公差设计中的应用。实例分析验证了该方法的有效性。  相似文献   

9.
产品的快速设计是产品赢得上市时间的关键,而模型的建立是其进行快速设计的前提.在研究了齿轮泵产品快速设计的基础上提出了一种齿轮泵模型的建模方法,重点介绍了基于尺寸驱动原理的几何建模方法以及基于编码技术的信息建模方法.  相似文献   

10.
支持自顶向下设计的产品功能建模技术   总被引:1,自引:0,他引:1  
自顶向上的设计模式符合一般的设计规律,面对几何建模技术为主的各种CAD系统难以真正地对这一过程提供支持本文介绍了一种基于功能单元和功能特征的产品功能模型。它能够表达产品的功能结构和功能关系,并建立了对零件形状特征的功能约束。功能建模系统 基于特征的产品建模系统相连接,能够实现自顶向下的产品设计 。  相似文献   

11.
Container spaces and functional features for top-down 3D layout design   总被引:1,自引:0,他引:1  
Although there have been many advances in computer-aided modelling techniques and representations of mechanical parts, there are areas where exact modelling is a handicap. One of these is 3D layout design. Here, simpler models are useful for initial design sketches to verify kinematic behaviour and organise product structure before the detailed component design phase begins. A commitment to exact, or close approximational geometry too early can imply a commitment to form before functionality has been finalised. This paper describes a system for top-down 3D layout design based on simple conceptual elements which can be used as a basis for visualisation, discussion, definition of product structure and kinematic functionality in the conceptual design phase before the embodiment or detailing begins. This tool forms a bridge between the abstract nature of the conceptual design phase and the geometric nature of the embodiment phase. The 3D layout module uses design spaces with simple geometry and kinematic connections to represent a product. The design spaces act as containers or envelopes within which the final component design is to be realised. The kinematic connections allow the behaviour of the product to be simulated to gain more information (such as overall component dimensions and areas of potential collisions) for the detailed design phase. In addition the paper describes the design process based on the proposed 3D layout design system and contrasts this with the traditional design process. An industrial case study is presented to illustrate the following advantages of the proposed approach: (i) the design process proceeds faster because unnecessary layout parameter and constraint modifications are avoided since kinematic functionality verification precedes the detail design, (ii) the design process can produce better designs since alternative solution principles can be explored early in the design process. Theoretical issues are discussed concerning kinematic constraint inheritance during design space decomposition and concerning computer support for non-rigid design spaces.  相似文献   

12.
《数字信号处理》是信息与计算科学专业的核心课程,涉及内容多、概念抽象、设计复杂等特点,而工程学类课程比较匮乏,为了使得学生更好地学好该课程,分析教学过程中存在的主要问题,给出产生问题的主要原因,从把握教学重点难点,注重实验课程教学和探索,通过方法论把握整体教学,结合学校学科特点进行专题拓展等几方面进行教学思考和探索。  相似文献   

13.
A new geometric constraint model is described,which is hierarchical and suitable for parametric feature based modeling.In this model,different levels of geometric information are repesented to support various stages of a design process.An efficient approach to parametric feature based modeling is also presented,adopting the high level geometric constraint model.The low level geometric model such as B-reps can be derived automatically from the hig level geometric constraint model,enabling designers to perform their task of detailed design.  相似文献   

14.
面向集成变量化设计的三维几何约束求解方法   总被引:3,自引:2,他引:1  
针对集成变量化设计中三维几何约束和装配几何约束的混合建模与求解问题,提出改进的有向图方法.该方法采用几何约束的基本约束表达和几何实体的抽象对偶实体表达,引入定向弧表达实体之间的内在依赖关系建立混合几何约束有向图模型;结合约束有向图的优化处理,实现了几何约束系统的细粒度分解和高效并行求解.最后用实例验证了文中方法的正确性和有效性.  相似文献   

15.
A large number of design decisions are made during the conceptual design of a part. However, there are few representation and reasoning tools for decision support during conceptual design. The conceptual design stage is characterized by a lack of complete geometric information. Existing geometric modelers require complete geometric information, while a functional reasoning methodology using a <verb, noun > representation is typically too terse. In this paper, we present a new representation called sketching abstraction for conceptual design, using the function-form relations in a design. The functionally critical part of the geometry is presented using a set of functional features, while the rest of the geometry is abstracted as a set of linkages. Part functionality is correlated with the sketching abstraction using data structures called function-form matrices. The sketching abstraction is annotated using a set of primitives, and a set of grammar rules are used to extract canonical relationships between the functional features. The sketching abstraction can be used for extracting designs that are geometrically dissimilar but functionally similar, thus providing the designer with ideas for design alternatives. The sketching abstraction can also be used to carry out domain-dependent manufacturability evaluation checks. A further use of sketching abstractions is to initiate the development of a process plan for manufacturing. Sketching abstractions are related to the solid model of a part. Thus, this representation provides a link between pure functional and pure geometric representations. The domain of application is stamped metal parts. We present the part functionality and the features used in this domain. We also illustrate the use of sketching abstractions for conceptual design, manufacturability evaluation and preliminary process planning.  相似文献   

16.
VRML环境下基于语义的产品装配设计技术研究   总被引:11,自引:4,他引:11  
装配语义是零件间装配约束的抽象与概括,研究基于语义的产品装配设计可有效地提高装配设计的直观性与装配效率。文中给出了基于语义的产品装配设计系统的总体框架结构,将装配语义分为常用语义与特殊语义,并建立了装配语义的层次表达;通过装配语义与几何约束的映射,形成几何约束的代数表达;借助零部件间的运动自由度的求解,实现了装配语义的驱动,有助于将装配设计从几何层发展到语义层进行操作。  相似文献   

17.
This paper describes the use of liaison to better integrate product model and assembly process model so as to enable sharing of design and assembly process information in a common integrated form and reason about them. Liaison can be viewed as a set, usually a pair, of features in proximity with which process information can be associated. A liaison is defined as a set of geometric entities on the parts being assembled and relations between these geometric entities. Liaisons have been defined for riveting, welding, bolt fastening, screw fastening, adhesive bonding (gluing) and blind fastening processes. The liaison captures process specific information through attributes associated with it. The attributes are associated with process details at varying levels of abstraction. A data structure for liaison has been developed to cluster the attributes of the liaison based on the level of abstraction. As information about the liaisons is not explicitly available in either the part model or the assembly model, algorithms have been developed for extracting liaisons from the assembly model. The use of liaison is proposed to enable both the construction of process model as the product model is fleshed out, as well as maintaining integrity of both product and process models as the inevitable changes happen to both design and the manufacturing environment during the product lifecycle. Results from aerospace and automotive domains have been provided to illustrate and validate the use of liaisons.  相似文献   

18.
近来用SystemC进行嵌入式软件建模研究非常活跃,目前尚不能用SystemC直接模拟嵌入式软件中常见的抢占式进程调度的行为。本文在详细的分析了SystemC模拟内核的基础上,提出将进程划分为一个一个不可分割的原子进程单元(APUs),作为进程调度的最小单位,并构造出一个RTOS抽象层实现任务抢占、实时调度、中断处理等功能,用以实现抢占式进程调度行为的建模和验证。实例表明,采用文中提出的方法,设计者在系统抽象层就可以进行多任务系统的动态调度如中断、抢占的模拟和验证,有效地提高了设计能力。  相似文献   

19.
20.
THEOBJECT-ORIENTEDINTELLIGENTPROGRAMMINGINCAD/CAM¥WangSu;ZhuXinxiong(DepartmentofManufacturingEngineeringBeijingUniversityofA...  相似文献   

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