整体构件数控电解加工CAD/CAM平台关键技术

针对整体构件数控电解加工中存在的问题,利用数据库、有限元、数控等技术建立了以工程数据库为集成方式的整体构件数控电解加工CAD/CAM平台;解决了该平台中建模、加工过程数值模拟、数控运动仿真、数控加工编程、参数优化等关键技术;并将该平台用于整体叶轮、压气机静子等复杂零件的电解加工中.应用结果表明,采用文中的平台缩短了整体构件的试制周期,提高了电解加工试验的成功率.     

Five-axis pencil-cut planning and virtual prototyping with 5-DOF haptic interface

In this paper, techniques of 5-axis pencil-cut machining planning with a 5-DOF (degree of freedom) output haptic interface are presented. Detailed techniques of haptic rendering and tool interference avoidance are discussed for haptic-aided 5-axis pencil-cut tool path generation. Five-axis tool path planning has attracted great attention in CAD/CAM and NC machining. For efficient machining of complex surfaces, pencil-cut uses relatively smaller tools to remove the remaining material at corners or highly curved regions that are inaccessible with larger tools. As a critical problem for 5-axis pencil-cut tool path planning, the tasks of tool orientation determination and tool collision avoidance are achieved with a developed 5-DOF haptic interface. A Two-phase rendering approach is proposed for haptic rendering and force-torque feedback calculation with haptic interface. A Dexel-based volume modeling method is developed for global tool interference avoidance with surrounding components in a 5-axis machining environment. Hardware and software implementation of the haptic pencil-cut system with practical examples are also presented in this paper. The presented technique can be used for CAD/CAM, 5-axis machining planning and virtual prototyping.     

数控玻璃雕刻CAD/CAM系统

本文在分析数控玻璃雕刻的特点及对CAD／CAM系统的要求的基础上，详细介绍了数控玻璃雕刻CAD／CAM系统构成、功能及关键技术。     

An integrated manufacturing planning assistant — IMPA

In this paper, we describe our development of a fully integrated manufacturing planning assistant (IMPA) system, which is able to: (1) interpret the finished part requirements directly from the designer's CAD systems or solid modelers without user intervention or special feature coding; (2) check the machinability of a designed part; (3) automatically generate a process plan, a tool path and an NC (numerically controlled) code, and (4) support interactive user modification of the resulting plans, tool paths and NC code. A demonstration version of the system was designed to provide automated assistance for the planning of machining processes on three-axes NC machine tools. The underlying architectural concepts and reasoning algorithms can be extended to more complex machines such as four-or-more-axes NC machines. CAD, CAE, and CAM including robotic, FMS (flexible manufacturing system) and NC machines are widely used in industry today. There is increasing interest in automation of factory control software Merchant, (1988); this includes automating the generation of the control programs — that is, in developing systems which will automatically produce the NC code for machining the part, given a model of the part, the shape of the raw material, and the machine specifications. With such systems, there are several difficulties in the manual preparation of an NC program code such as, long and tedious calculations, high risk of error in data preparation, etc., which need to be eliminated. This is a critical step toward the integration of CAD and CAM into a truly concurrent engineering and manufacturing environment.     

CAD/CAM integrated system in collaborative development environment

For virtual enterprises to realize efficient operation in the 21st century, it is necessary to develop an environment that can support collaborative work of multi-disciplinary groups distributed in different places. CAD/CAM integrated system is an important subsystem in this environment. In this paper, the structure of CAD/CAM integrated system is presented, then, key technologies related to realize CAD/CAM integration are discussed in detail and finally main functions and an application case of CAD/CAM integrated system is introduced.     

CAD／CAM中曲面光滑拼接的研究

本文讨论了CAD／CAM软件系统中复杂曲面的光滑拼接问题。提出了对曲面光滑接接的磨光法和覆合法。利用这些方法对一些机械零件进行了行造型和控具加工，取得了令人满意的效果。     

基于Internet的计算机辅助设计与制造技术

本文阐述了基于Ｉｎｔｅｒｎｅｔ 的计算机辅助设计与制造（ＣＡＤ／ＣＡＭ） 技术的国内外动态。提出了一种基于Ｉｎｔｅｒｎｅｔ的ＣＡＤ／ＣＡＭ 系统模型和实现方法。介绍了一个基于Ｉｎｔｅｒｎｅｔ的机床数控系统。     

Standard process monitoring and traceability programming in collaborative CAD/CAM/CNC manufacturing scenarios

The paper focuses on collaborative STEP-based CAD/CAM/CNC supply chains to program and automate machining process data monitoring and traceability activities. A traceability interface (traceability nc_functions) is defined for the new CNC programming standard ISO STEP-NC. CAM systems will be able to program monitoring and data access activities by inserting traceability nc_function calls in CNC programs. On the shop floor, controllers will automatically interpret these nc_functions to access process data while machining and will relate data records with the corresponding machining operations in a STEP-NC part program. With both types of information—process data and standard machining program (STEP-NC part program)—spread and technologically heterogeneous engineering systems will have full knowledge about what has happened in production. Traceability data access automation will assure data reliability. The paper describes a traceability scenario where standards such as MTConnect and ISA-95 support, rather than interfere with, the STEP-NC traceability proposal.     

A Visibility Sphere Marching algorithm of constructing polyhedral models for haptic sculpting and product prototyping

This paper presents a Visibility Sphere Marching algorithm of constructing polyhedral models from Dexel volume models for haptic virtual sculpting. Dexel volume models are used as the in-process models representation during interactive modification in a haptic virtual sculpting system. The stock material represented in a Dexel volume model is sculpted into a designed model using a developed haptic sculpting system. The sculpted Dexel volume models are converted to polyhedral surface models in STL format by the proposed visibility sphere marching algorithm. The conversion turns out to be an interesting and challenging problem. The proposed visibility sphere marching algorithm consists of three sub-algorithms: (i) roof and floor covering, (ii) wall-building, and (iii) hole-filling algorithms. The polyhedral surface models converted from the Dexel volume models can then be input to and processed by available computer-aided manufacturing (CAM) or rapid prototyping systems. The presented technique can be used in virtual sculpting, CAD/CAM, numerically controlled machining verification and rapid prototyping.     

An integrated intelligent machining system for axisymmetric parts using PC-based CAD and CAM software packages

Machining process planning involves the formation of a set of directions describing the machining operations required to transform raw stock into a finished part. Conventional process planning, performed manually, relies on the knowledge and competence of an experienced process planner and tends to be time consuming and error prone. In the past two decades, much effort has been spent on improving process planning by utilizing the power of a computer to emulate the capabilities of an experienced planner. During the same period, computer-aided design (CAD) and computer-aided manufacturing (CAM) software has been developed to enhance design productivity and to assist the NC code generation facets of the machining process. The entire planning process may be automated be integrating CAD and CAM using computer-aided process planing (CAPP). The research described in this paper outlines the design and development of an intelligent CAPP system integrating two commercial CAD and CAM software packages, Autocad and Mastercam.     

协同开发环境中的CAD/CAM集成数据管理的实现

协同开发环境是虚拟企业高效运作的支撑平台,CAD/CAM集成系统是该环境中的重要子系统,迫切需要对CAD/CAM集成数据进行有效的管理和操作。文章讨论了协同开发环境中CAD/CAM集成数据的管理技术,并详细分析了CAD/CAM集成数据库的数据结构和数据集成。     

基于激光快速原型的CAD网络浏览器的研制

把CAD/CAM中快速成形建模技术与TCP/IP网络套接字技术相结合 ,并以脚医学中的脚支撑模型为应用领域 ,研究开发CAD网络浏览器 ,该浏览器能在Internet网络上提供CAD模型浏览和脚支撑铣削加工刀具轨迹及其数控G码的生成。     

Nonsymmetric streamlined extrusion dies through computer aided engineering

CAD/CAM procedure on the development of nonsymmetric streamlined die for hot extrusion has been detailed in this paper. The modelling for the selection of the processing variables and the design of die geometry were achieved through the use of an Advanced Die Design System (ADDS^™)¹ by taking into account the material's dynamic behaviour. Complicated sculptured surfaces of the die were constructed using Drafting/Design module of Unigraphics II (UGII)². Cutting simulations and NC coding for the machining of die electrodes were conducted by UGII Manufacturing Operation module. Electrodes for EDM die sinking were machined on a 4-axis CNC milling machine and the die cavity was finally eroded.     

协同CAD/CAM系统中数据的高效传输

在协同CAD/CAM系统中,存在着大量的数据传输和交换。如何使数据在目前网络低传输率的情况下及时、有效和可靠地传输,成为了提高协同CAD/CAM系统性能及实现同步协同的关键所在。结合南航CAD/CAM工程研究中心开发的WebSuperman系统,该文研究了数据的高效传输策略并进行了实现。     

数控加工远程通信系统

介绍了集CAD／CAM、远程通信于一体的数控加工系统的功能和实现技术,同时对CAD／CAM、远程通信系统的开发等关键技术作了详细介绍。     

Building MRSEV models for CAM applications

In integrating CAD and CAM applications, one major problem is how to interpret CAD information in a manner that makes sense for CAM. The goal is to develop a general approach that can be used with a variety of CAD and CAM applications for the manufacture of machined parts.

In particular, a methodology is presented for taking a CAD model, extracting alternative interpretations of the model as collections of MRSEVs (material removal shape element volumes, a STEP-based library of machining features), and evaluating these interpretations to determine which one is optimal. The evaluation criteria may be defined by the user, in order to select the best interpretation for the particular application at hand.     

Computer aided design of form rolls for NC manufacture

Computer aided design (CAD) and computer aided manufacture (CAM) are two modern areas of computer application which have decisive influence in the manufacturing industries. The recognition of the potential of CAD/CAM is worldwide and many have taken advantage of the new technology. The design and manufacture of form rolls and the special tooling used in cold roll forming of thin walled metal sections are areas where the CAD/CAM approach can make a positive computer aided tool for creating form roll designs suitable for NC (numerical control) manufacturing. This work was undertaken by the Department of Production Technology and Production Management at the University of Aston in Birmingham in collaboration with a leading manufacturer of thin walled sections. Significant improvement of lead time and productivity in both design and manufacturing of form rolls have been accompanied.     

基于微机平台的注塑模型腔CAD/CAM一体化的实现

本文分析了注塑模型腔CAD／CAM实践中具体的曲线曲面造型处理方法，讨论了CAD／CAM实现中的各项关键技术，并成功地在微机系统上实现了注塑模型腔CAD／CAM的一体化。     

Robust uniform triangulation algorithm for computer aided design

This paper presents a new robust uniform triangulation algorithm that can be used in CAD/CAM systems to generate and visualize geometry of 3D models. Typically, in CAD/CAM systems 3D geometry consists of 3D surfaces presented by the parametric equations (e.g. surface of revolution, NURBS surfaces) which are defined on a two dimensional domain. Conventional triangulation algorithms (e.g. ear clipping, Voronoi-Delaunay triangulation) do not provide desired quality and high level of accuracy (challenging tasks) for 3D geometry. The approach developed in this paper combines lattice tessellation and conventional triangulation techniques and allows CAD/CAM systems to obtain the required surface quality and accuracy. The algorithm uses a Cartesian lattice to divide the parametric domain into adjacent rectangular cells. These cells are used to generate polygons that are further triangulated to obtain accurate surface representation. The algorithm allows users to control the triangle distribution intensity by adjusting the lattice density. Once triangulated, the 3D model can be used not only for rendering but also in various manufacturing and design applications. The approach presented in this paper can be used to triangulate any parametric surface given in S(u,v) form, e.g. NURBS surfaces, surfaces of revolution, and produces good quality triangulation which can be used in CAD/CAM and computer graphics applications.