基于CAD／CAPP并行设计的特征描述与操作

本文介绍了在作者开发的基于特征的ＣＡＤ／ＣＡＰＰ并行系统ＦＯＰＳ中,针对ＣＡＤ／ＣＡＰＰ并行设计的要求,对形状特征的表示处理策略。提出了基于加工的形状特征分类及体描述思想,并从一个新的角度认识处理形状特征,建立了基于特征描述的实体几何模型,提出了广义“凹孔”的特征认识概念及相应的“内环”处理技术,为有效地在设计过程中同时为ＣＡＰＰ系统提供必要的信息,便于进行零件设计的结构工艺性分析、评价及工艺规程     

An integration of feature recognition and process planning functions for turning operation

This paper deals with the development of a Computer Aided Process Planning(CAPP) system interfaced with CAD for turning operation. The developed system performs CAD interfaced feature recognition from part geometry database, and the decision procedures for process planning functions such as process and operation selection, machine tool selection, setup planning and operation planning.

The system runs under personal computer environments and AutoCAD is employed as CAD system and Turbo-C is used for the decision procedures. A case study is performed to evaluate the performance of the system.     

通用型CAPP专家系统中知识表示和推理机制的研究

ＣＡＰＰ作为ＣＡＤ与ＣＡＭ的中间桥梁，是ＣＩＭＳ必不可少的重要环节．本文针对开发通用性ＣＡＰＰ专家系统过程中，产品零件表示和工艺规程设计这两个关键问题，根据事物之间的相似性原理，提出了面向对象的产品零件和工艺规程的知识表示方法，以满足ＣＡＰＰ系统对产品零件信息表示的完整性、通用性、逻辑可分解性、动态性和相容性等要求，并在此基础上提出了ＣＡＰＰ专家系统的混合推理机制，包括单继承、多继承、非单调继承、类比推理等．     

提高蒸气流量计量精度的算法及实现

为了充分利用气体流量测控网络资源，分析了一般带温度压力补偿的节流式流量计量算法在ｔ，ｐ波动较大时，不能很好地补偿气体密度的问题。提出了利用网络上层监测站进行数据查询和复杂计算，向下传输最新补偿参数的方法，去提高算法精度，给出了算法流程图，对算法进行了仿真，其效果令人满意。     

An automated interface between CAD and CAM

The interface between CAD and CAM is an important phase in CAE (Computer Aided Engineering). There are many systems such as CAPP (Computer Aided Process Planning) that can solve this problem. But CAPP needs recognition of the features of a solid model that result from a complex procedure. This paper describes a new highly efficient method to link CAD and CAM from solid models to machinable models.     

BOM在ERP升蓝软件系统中的作用

本文在分析ERP系统升蓝软件和“（CAD／CAPP）”技术特点的基础上,认为生产制造型企业在信息化建设过程中应以BOM为信息纽带,以PDM为核心,再结合CAD／CAPP和ERP升蓝软件系统,并辅以Internet和EDI系统,这将有利于实现企业信息化建设的目标。     

An algorithm for CAD tolerancing integration: Generation of assembly configurations according to dimensional and geometrical tolerances

For several years, Digital Mock-Up (DMU) has been improved by the integration of many tools as Finite Element (FE) Analysis, Computer Aided Manufacturing (CAM), and Computer Aided Tolerancing (CAT) in the Computer Aided Design (CAD) model. In the geometrical model, the tolerances, which specify the requirements for the proper functioning of mechanical systems, are formally represented. The nominal modeling of the parts and assemblies does not allow the prediction of the tolerance impacts on the simulation results as the optimization of mechanical system assemblability. So, improving the CAD model to be closer to the realistic model is a necessity to verify and validate the mechanical system assemblability. This paper proposes a new approach to integrate the tolerances in CAD model by the determination of the configurations with defects of a CAD part, used in a mechanical system. The realistic parts are computed according to the dimensional and geometrical tolerances. This approach provides an assembly result closer to the real assembly of the mechanical system. The Replacement of the nominal parts by the realistic ones requires the redefinition of the initially defined assembly mating constraints. The update of the mating constraints is performed by respecting an Objective Function of the Assembly (OFA). Integrating tolerances in CAD allows the visualization and simulation of the mechanical assemblies’ behavior in their real configuration and the detection of possible interference and collision effects between parts which are undetectable in the nominal state.     

面向弯曲件工艺交互设计的几何模型

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     

Development of a multi-resolution framework for NUBS

The piecewise polynomial B-spline representation is a flexible tool in Computer Aided Geometric Design (CAGD) for representing and designing the geometric objects. In the field of Computer Graphics (CG), Computer Aided Design (CAD), or Computer Aided Engineering (CAE), a very useful property for a given spline model is to have locally supported basis functions. This allows localized modification of the shape. Unfortunately this property can also become a serious disadvantage when the user wishes to edit the global shape of a complex object. A multi-resolution representation is proposed as a solution to alleviate this problem.In this work, we propose a multi-resolution representation for Non-uniform B-splines (NUBS). The proposed multi-resolution model has three features that it uses control point decimation strategy for decomposing NUBS curves and it is efficient in both time and space utilization. A comparative study of the proposed work is also made with an alternate approach in the literature, which is based upon knot decimation.     

基于实体的特征反求技术研究

反求工程是当今CAD建模技术的一种重要途径,它极大地提高了设计人员的设计效率.然而仅包含曲面信息的三维重构限制了反求工程与CAD/CAPP/CAM系统的集成.针对这一问题,本文提出了基于多色图表示子特征之间空间约束关系的集合运算思路,可以较好地得到反求实体的特征信息以及特征树的结构利于其后的CAD模型的再设计、设计分析和加工.     

A parallel simulated annealing algorithm based on functional feature tree modeling for 3D engineering layout design

Computation complexity and modeling complexity are primary clog in 3D engineering layout design. In this paper, a parallel simulated annealing based on multiple Markov chains is employed to deal with the computation complexity. The algorithm increases computing efficiency by allocating computation burden to networked computers. To cope with the modeling complexity, machine components and space limitation are modeled by a hierarchical, feature-based modeling method—the functional feature tree modeling method. And multiple complex design constraints can be described by the representation. In order to support whole layout design solving process, a Computer Aided Layout Design System is introduced briefly. This system not only implements the algorithm and the components representation, but also integrates some other subsystems as evaluation system, constrains editor etc. The methods are demonstrated through a real engineering application, a vehicle engine compartment layout design.     

A framework for extending computer aided process planning to include business activities and computer aided design and manufacturing (CAD/CAM) data retrieval

Computer aided process planning (CAPP) systems have had limited success in integrating business functions and product manufacturing due to the inaccessibility and incompatibility of information residing in proprietary software. While large companies have developed or purchased complex order management and engineering applications, smaller manufacturers continue to use semi-automated and manual methods for managing information throughout the lifecycle of each new product and component. There is a need for reconfigurable and reprogrammable systems that combine advances in computer aided design (CAD/Computer Aided Manufacturing (CAM) technology and intelligent machining with product data management for documentation and cost control. The goal of this research is to demonstrate an architecture in which customer service, CAPP and a costing methodology known as activity based costing (ABC) are incorporated into a single system, thereby allowing companies to monitor and study how expenditures are incurred and which resources are being used by each job. The material presented in this paper is the result of a two year university and industry sponsored research project in which professors and students at the Costa Rica Institute of Technology developed a software application for FEMA Industrial S.A., a local machining and fabrication shop with sixty five employees and both conventional and CNC capabilities. The final results represent not only a significant contribution to local industry and to the students’ education but, also to the continuing growth of CAPP. Implementing better decision making tools and standardizing transactions in digital format would reduce the workload on critical personnel and archive valuable knowledge for analyzing company methods and expertise.     

FPGA-based hardware CNC interpolator of Bezier,splines, B-splines and NURBS curves for industrial applications

Tool path interpolation is an important part of Computerized Numerical Control (CNC) systems because it is related to the machining accuracy, tool-motion smoothness and overall efficiency. The use of parametric curves to generate tool-motion trajectories on a workpiece for high accuracy machining has become a standard data format that is used for CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) and CNC systems. Splines, Bezier, B-splines, and NURBS (Non-Uniform Rational B-splines) curves are the common parametric technique used for tool path design. However, the reported works bring out the high computational load required for this type of interpolation, and then at best only one interpolation algorithm is implemented. The contribution of this paper is the development of a hardware processing unit based on Field Programmable Gate Arrays (FPGA) for industrial CNC machines, which is capable of implementing the four main interpolation techniques. It allows the selection of the required interpolation technique according the application. Two CAD models are designed for test the CNC interpolations; experimental results show the efficiency of the proposed methodology.     

基于STEP和约束机制的CAD/CAP集成技术的研究

提出一种支持用户自定义ＣＡＰＰ数据结构,及与多种ＣＡＰＰ系统集成的方法,通过对ＣＡＰＰ系统的数据模型（用Ｃ／Ｃ＋＋描述）进行分析,获取其词法与语义信息,按照ＣＡＰＰ系统数据模型的数据要求,在集成系统的末端给出工艺数据,以工艺特征树为操作核心,实现了ＣＡＤ系统与多种ＣＡＰＰ系统之间的数据交换。同时,该技术在产品数据的交换中支持ＳＴＥＰ标准,实现了基于ＳＴＥＰ的信息集成。     

基于UML的管理信息系统开发

以一个管理信息系统为背景,探讨了利用统一建模语言对系统进行面向对象分析、设计以及实现问题,顺利实现了对象模型向关系数据库模型的转换。     

Multiuser collaborative work in virtual environment based CASE tool

VRCASE is a virtual environment based Computer Aided Software Engineering (CASE) tool. It provides a 3D multiuser collaborative software modeling environment with automatic object-class abstraction, class diagram generation, and C++ skeleton generation facilities for assisting Object-Oriented software development. It allows multiple concurrent users to model software system collaboratively. To achieve efficient collaborative software development in VRCASE, we have proposed and implemented a Fine-grained locking and notification mechanism together with visual indicators to maintain system consistency among multiple concurrent users. The system evaluation shows that our approach can effectively support multiuser collaborative software design in VRCASE.     

质量约束的三维模型建模方法

在当今的智能制造和工业软件设计领域,CAD和CAE是极为重要的技术.但现有的CAD和CAE模型表示方法不统一,在数据交换上需要耗费大量时间,造成了计算资源极大的浪费.非均匀有理B样条(NURBS)模型作为一种兼容CAD和CAE的模型表达方式,以样条曲线为基函数,无须进行交换即可进行等几何分析.本文提出了一种基于质量约束...     

STEP信息集成软件工具的设计和实现

ＳＴＥＰ是国际标准化组织ＩＳＯ正在组织开发的应用于计算机集成制造系统（ＣＩＭＳ）信息集成的产品数据表达与交换标准，ＳＴＥＰ不仅是一种规范，更是一种信息集成技术，本文以ＣＡＤ／ＣＡＰＰ／ＣＡＭ系统集成为背景，提出了ＳＴＥＰ信息集成支持工具ＥｘＴｒａ的设计和实现技术，该软件工具已成功且有效地应用于ＣＡＤ／ＣＡＰＰ／ＣＡＭ系统集成中。