A geometrical approach to computer-aided process planning for computer-controlled machine tools

This paper documents part of a research program which has been under way at the CIM Centre at Swinburne University of Technology since 1989. The purpose of the research program was to develop an open-architecture machine tool control system and then to see how that system could be used to change the distribution of traditional manufacturing design, planning and control functions. This paper examines one part of that research program and focuses on a methodology which could prove to be useful in the machine tool selection, cutter selection and cutter path generation phases of process planning for cutting operations on workpieces in computer-controlled machine tools.It is suggested that a configuration space transform be used for each cutter/machine tool combination to find the volume that the combination could remove from the uncut workpiece without removing any of the material that will form the final workpiece. A method of comparing these volumes from different combinations is then outlined. The output of this method is a reasonable sequence of machine tools and cutters. Path planning can then be carried out for each of the chosen combinations using a method similar to the one used to find the possible volume to be removed.Possible implementation techniques, and their limitations on existing computer hardware, are discussed and the most promising of these are identified, based upon some properties of configuration space transforms.     

基于TRBAC的协同设计动态访问控制

针对协同设计过程中由于任务执行的动态性承担任务的角色与权限之间的动态分配问题,在协同设计访问控制中引入任务关联,提出一种基于任务/角色的动态访问控制模型TRBAC,给出TRBAC的形式化描述。论述基于TRBAC的协同设计动态访问过程,设计其访问授权及控制算法。以凸轮组协同设计为例,通过引入TRBAC模型,实现其动态访问控制。     

A knowledge base model for complex forging die machining

Recent evolutions on forging process induce more complex shape on forging die. These evolutions, combined with High Speed Machining (HSM) process of forging die lead to important increase in time for machining preparation. In this context, an original approach for generating machining process based on machining knowledge is proposed in this paper. The core of this approach is to decompose a CAD model of complex forging die in geometrical features. Technological data and topological relations are aggregated to a geometrical feature in order to create machining features. Technological data, such as material, surface roughness and form tolerance are defined during forging process and dies design. These data are used to choose cutting tools and machining strategies. Topological relations define relative positions between the surfaces of the die CAD model. After machining features identification cutting tools and machining strategies currently used in HSM of forging die, are associated to them in order to generate machining sequences. A machining process model is proposed to formalize the links between information imbedded in the machining features and the parameters of cutting tools and machining strategies. At last machining sequences are grouped and ordered to generate the complete die machining process. In this paper the identification of geometrical features is detailed. Geometrical features identification is based on machining knowledge formalization which is translated in the generation of maps from STL models. A map based on the contact area between cutting tools and die shape gives basic geometrical features which are connected or not according to the continuity maps. The proposed approach is illustrated by an application on an industrial study case which was accomplished as part of collaboration.     

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.     

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。     

用二次插值实现近似弧长参数化

分段二次Ｈｅｒｍｉｔｅ插值用来保单调地反插值参数曲线的弧长函数．所作近似弧长参数化曲线在插值节点处,近似弧长是精确的,并且具有与精确弧长参数曲线同方向的单位切矢．在整个近似弧长参数区间,近似弧长的误差可达到０（△ｔ）＾２（△ｔ为节点步长）．数值实例得到了很好的结果．     

并行工程在汽车车身开发与制造上的应用

本文分析了常规车身ＣＡＤ／ＣＡＭ技术所存在的弊病,提出了采用并行工程的原理进行车身开发及车身工装设计与制造的方法。重点介绍了实施车身并行工程要解决的关键性技术,诸如建立集成化的产品数据模型、ＣＡＤ／ＣＡＰＰ／ＣＡＭ集成技术、建立多功能小组、计算机技术支持等。     

基于OpenGL的快速原形制造系统仿真

随着计算机技术的发展,可视化仿真和快速原形制造RPM已经成为CAD/CAM仿真领域的热点.文中介绍了RPM可视化仿真系统的总体结构和软件设计思想,为了实现数控机床加工零件产品的快速原形制造系统,提出了一种基于AutoCADRl4、VisualC 6.0和OpenGL语言的RPM技术实现方案.该方案利用VisualC 6.0作为系统开发平台,使用目前通用的3D图形API标准,可以方便地将AutoCADRl4输出的STL文件利用OpenGL进行三维真实感显示,并可以根据需要实现各种视图变换操作.最后给出了一个仿真结果,验证了该系统的性能.     

某研究所CIMS实现浅见

首先对CIMS进行了简述,然后介绍了某研究所科研生产的现状,最后提出某研究所实现CIMS的可能途径。