Preliminary Study on Quantitative Research Methods of Discussion-based Teaching: CAD/CAM Course

Computer-aided design and manufacturing,or CAD/CAM,in a narrow sense,is the use of a computer for component design and machining. As a specialized course for students,CAD/CAM course is a required course for undergraduates majoring in mechanical engineering and related engineering majors and also the core technical skills to be mastered during the undergraduate study. Based on the teaching practices of CAD/CAM course,this paper tries to introduce the discussion-based method in curriculum design and the implementation of the course,and enhance the interaction between teachers and students through using new information interaction tools such as We Chat group and course homepage to stimulate students' interest,and also expand the learning space and time. Thus,the problems students have will be solved in real time. In this study,for the first time,the statistical methods are used to record detailed the speaking time,keywords and the frequency of teachers and students' interaction,and also carries out quantitative analysis in order to explore the interactive patterns between teacher and students in discussion-based teaching,so as to improve communication and learning efficiency between teacher and students. Meanwhile,this paper also discussed the advantages and the disadvantages of using discussion-based teaching in the hope that it can provide reference for the following discussion-based teaching of CAD/CAM course in mechanical or related engineering majors.     

“材料成型”专业CAX课程体系探索与实践

文章介绍了CAD／CAE／CAM课程体系教改实施意义、实施过程与实践效果，阐述了CAD／CAE／CAM课程体系强调理论与实操并重的教学目标，让学生掌握信息集成的制造思想的教育模式。并对CAD／CAE／CAM课程体系教改后进一步完善提出了建议。     

Integrated and concurrent approach for compound sheet metal cutting and punching

In sheet metal processing and manufacturing, there are a lot of small- and medium-sized job shops. These small- and medium-sized manufacturing companies have been facing keen competitive pressure in the market. This pressure has forced these companies to make every effort to shorten product development lead-time, improve production efficiency, approach high-quality standards, but at the same time cut down the costs. To meet the needs of these companies, this paper presents a compound cutting and punching production method supported by an integrated CAD/CAPP/CAM system in sheet metal manufacturing. Many existing commercial CAD/CAM systems are not suitable for this manufacturing method, especially under concurrent and global design and manufacturing environments. Some problems have to be solved before these CAD/CAM systems can be employed and integrated for this compound manufacturing method. This paper deals mainly with the solutions to solve some of these problems. The solutions include an integrated data integration platform based on Pro/INTRALINK and STEP, and a knowledge-based real time CAPP (RTCAPP) system for compound sheet metal cutting and punching. Within the presented CAD/CAPP/CAM system, some key modules have been developed. They are the automatic tool selection and manufacturing sequencing module, a shortest tool path optimization module, a cost estimation module and an automatic insertion of auxiliary path module based on knowledge bases. These modules will be addressed here.     

复杂零件数控编程KBE系统广义知识库应用研究

在分析数控编程KBE系统各模块相互联系的基础上,构建了基于KBE的复杂零件数控编程系统功能架构和广义知识库结构模型．综合数据库技术和知识库理论,建立了数控编程广义知识库系统．阐述了广义知识库的设计思想,给出了数控编程广义知识库与UG CAD／CAM应用接口实现的技术路线．并以企业需求为背景,在知识驱动型制造平台（UG CAD／CAM）上,利用VC＋＋6．0和UG／Open,将广义知识库系统和UGCAD／CAM无缝集成,实现了KBE和UG CAD／CAM系统的融合,开发了复杂零件数控编程KBE系统,验证了课题研究的可行性和实用性．     

基于ObjectARX实现特征建模的方法

为了满足中小企业实施CAD/CAM集成过程中对产品特征模型的需要,基于特征设计的建模理论,建立了特征的信息模型。研究了在AutoCAD系统上实现特征建模的方法,阐述了特征的参数输入、定位、生成及存储等特征建模的主要步骤。以齿轮泵泵体特征建模为例,证明了基于ObjectARX实现特征建模的可行性,为中小企业实施CAD/CAM集成提供了一种简单而有效的方法。     

基于设计流程的产品数字化设计研究

结合产品数字化设计的现状及趋势,分析了现代产品设计的主要思路及流程,详细论述了CAD/CAM技术在现代产品设计各环节中的辅助作用。详细论证了通过有机整合现有CAD/CAM软件,实现合理、高效地产品设计流程的可行性。在此基础上,提出基于设计流程的产品数字化设计方案。该方案在产品设计中的实施,大大提高了设计效率,缩短了产品设计周期。     

面向三维CAD/CAM技术的机械制图教学研究

分析了三维CAD／CAM技术的发展引起的设计和制造领域的变革及其对机械制图课程的影响，介绍了面向三维CAD／CAM技术的机制图教室研究及实践，根据高素质人才培养的需要，强调优化课程体系，教学内容、教学方法，加强空间思维能力，形体构形能力，创新能力，工程意识的培养。     

Computer integrated materials processing (CIMP) — A generic application of CAD/CAM technology

The paper features the development and application of CAD/CAM technology to materials forming processes. A research programme focusing on materials behaviour during the design, tooling and production phases is examined. Discussion of the generic concept for establishing a fully integrated system shows how technology crosslinking can be achieved. The benefits of a combined analytical-experimental research are emphasised. Typical applications to injection moulding, die casting and other forming processes are presented.     

A comprehensive review of tolerancing research

Ever since the plus/minus limits on dimensions first started to appear on engineering drawings in the early 1900s, tolerances have been one of the most important issues for every engineer involved in the product realization processes. In particular, with the advancement of computers and CAD/CAM techniques in the 1970s, the tolerance-related issues have continuously drawn the attention of many researchers since then. As a result, a tremendous number of research articles have been published over the last 30 years. This paper aims at a comprehensive state-of-the-art review on various tolerancing issues in design and manufacturing. However, due to the overwhelming number of existing research publications, any reviews on tolerancing issues could by no means be exhaustive. Rather, this review attempts to provide the reader with a view toward a balanced understanding of the various problems in tolerancing by presenting some typical research work for each of the classified fields, and tries to draw the potential research directions in the future.     

CAD/CAM 系统中曲面模型真实感显示方法的研究与实现

本文介绍了由南京航空航天大学ＣＡＤ／ＣＡＭ工程研究中心开发的集成化超人ＣＡＤ／ＣＡＭ／ＣＮＣ系统中对产品模型进行着色的方法，同时介绍了该系统所运用的防变形的新方法。运用这种方法实现产品模型的真实感显示，速度已达到实用的要求。效果良好。     

Optimal cutter size determination for 2½-axis finish machining of NURBS profile parts

A curve model of non-uniform rational B-spline (NURBS) has been widely adopted in mainstream CAD/CAM software systems to design complicated geometries of mechanical parts, for example, the curved profiles of pockets, sides, and islands. NURBS profile parts (the profiles include NURBS curves for pockets and islands) are produced in 2½-axis rough and finish machining. In rough machining of the parts, several end-mills with different sizes are employed for high cutting efficiency, and in finish machining, a single end-mill is usually used to cut along the profiles for high surface quality. To accurately produce the geometries with NURBS curves in finish machining, the cutter size should be optimised in order to eliminate gouging and save machining time. Although this topic has been a research focus for a decade, optimal cutter size determination still remains as a technical challenge. To rise to this challenge, our work proposes a new approach to determining the largest allowable size for the cutter to move along all the profiles (including NURBS curves) in 2½-axis finish machining without global and local gouging. The salient feature of this approach is that an original model of the cutter size is formulated and an effective solver–the particle swarm optimisation method–is employed to compute the largest allowable cutter size. This intelligent approach is more efficient and accurate than the conventional computational method based on the test examples in this work. It can also be applied to global and local gouging detection for NURBS profile machining. Our research work has great potential to advance CNC machining techniques.     

基于CAD／CAM的复杂曲面产品设计

以现代产品设计发展现状和趋势为依据,深入探讨了不同造型类别产品的设计方式与制造过程。在此基础上,提出了如何整合设计方法,合理利用现代先进的CAD/CAM技术,实现复杂曲面产品在造型和结构上的设计,以适应现代社会发展的需求。     

基于Multi-Agent的协同设计中虚拟环境感知研究

在现代机电产品设计过程中,要求采取快捷灵活的行动方式。随着虚拟现实技术的发展, 研究协同虚拟产品设计成为CAD/CAM的重要课题之一。结合协同虚拟设计原型系统(cooperative virtual production design, CVPD),提出了一种新的基于Multi-Agent的虚拟环境感知体系结构,给出离散系统神经网络的算法,并以动态多光标为例,解决用户自定义虚拟感知结构的实现方式。该结构提高了协同虚拟设计感知能力和工作效率。     

ISO10303-compliant computer-aided wheel-rim design system - the framework and data model

This paper focuses on developing a framework for a computer-aided part design system that considers design efficiency and facilitates product information sharing across the automotive supply chain. The system applies the concept of feature-based design to enhance the efficiency and effectiveness of auto-part design and implements the standard exchange of product (ISO10303/STEP) data model to enable the data sharing between original equipment manufacturers (OEMs), suppliers and customers. This research demonstrates the technology of standard data modelling for a feature-based CAD system to achieve cross-platform CAD/CAM integration. The framework supports technical data interchange (TDI) using international data standard to enable the concept of virtual engineering community and collaboration.     

Training programme on engineering applications at the CityPolytechnic of Hong Kong

An integrated training programme on engineering applications has been devised to meet the unique socio-economic needs of Hong Kong. The programme is directed at the design of a product which is competitive in the world market because product design is of paramount importance to the local export-oriented electronics industry. It comprises modules taught during the regular academic year and practical sessions held in a simulated industrial environment in the summer. Students are involved in nearly all aspects of the production process. It is an integrated programme because material covered in taught modules and the practical training are blended together to form a consolidated programme with a common theme. The programme has been operational for six years; feedback from former students their employers, industrialists, and members of accreditation teams is, in general, favourable     

HPRODIE: Using feature modelling and feature mapping to speed up progressive die design

For various reasons, the advances in progressive die design remain too slow compared with the increasing importance of progressive dies in modern industry. Aimed at speeding up the design process, HPRODIE, an integrated CAD/CAM system for progressive dies, was developed. In HPRODIE, three featuresthe product feature for the representation of sheet metal parts, the stamping process feature for the strip layout, and the die design feature for building the die assembly modelare introduced respectively to represent three life-cycle aspects of sheet metal parts. Feature mapping methods are employed to transfer the design information between different design stages at high-level semantics. With feature modelling and feature mapping, most of design processes can be carried out automatically. The testing results have shown that the design cycle has been cut down significantly by using this system.     

基于环球网的CAD/CAM技术

提出了开发基于Ｉｎｔｅｒｎｅｔ（中文意为环球网）的ＣＡＤ／ＣＡＭ系统的思想，并利用Ｉｎｅｔｅｒｎｅｔ中应用最普遍的ＷＷＷ服务中的上应网关接口成功地开发了基于Ｉｎｔｅｒｎｅｔ的ＣＡＤ／ＣＡＭ系统。     

NURBS machining and feed rate adjustment for high-speed cutting of complex sculptured surfaces

Owing to the enormous engineering advancement in modern industry, the competition in the development of advanced manufacturing technologies has been increasingly intense as can be seen in automobile, aerospace and various industries. Not only has product quality improved tremendously, but also the demand over production speed has become higher. Therefore, high-speed and high-accuracy production has become a very important goal of modern manufacturing companies. Thanks to ever increasing computer speed and the open architecture of new controllers in computer-controlled machines, the capability and flexibility of today's CNC machines allow us to machine contoured geometry using non-uniform rational B-spline (NURBS) curves directly from the free-form surfaces of a complex CAD/CAM model. As a result, machining accuracy and product quality can be greatly improved while machining time is also significantly reduced. This paper proposes a post-processing approach to convert G1 NC codes from most CAD/CAM systems to NURBS NC paths for highspeed contour machining. The NURBS interpolation strategy that takes into account the optimized cutting feed rate based on machine dynamic response and curvature of the NURBS curve is also developed. Experiments show that the implemented NURBS cutting can significantly improve machining accuracy and reduce cutting time and therefore satisfies the requirements of today's highspeed and-accuracy machining needs.     

产品研发标准评估方法

针对多年从事产品研发工作中标准化方面的问题,阐述了研发标准规范性、适宜性、标准间协调性的评估方法,也提出了企业研发标准应用的审核要求和方法;对完善和有效实施研发标准体系具有实际指导意义.     

STEP-compliant NC research: the search for intelligent CAD/CAPP/CAM/CNC integration

Since the first generation of Numerically Controlled (NC) machine tools was developed in the 1950s, there have been many developments which make today's NC machines completely unrecognizable from their early ancestors. Further developments, however, are now being significantly limited by the current programming language (ISO6983 or RS274D) that has been supporting NC manufacture since day one. Today a new standard, informally known as STEP-NC, is being used as the basis for development of the next generation of Computer Numerically Controlled (CNC) controller. This new standard is ISO 14649 and ISO 10303 AP 238. This standard gives CAM and CNC vendors the opportunity to integrate the capabilities of CAD/CAM systems with a new breed of intelligent CNC controllers, which have bi-directional communication of information representing standardized geometric and manufacturing data. This paper presents a comprehensive review of STEP-NC developments for a range of CNC processes. These developments include some major projects collaborated at the international level as well as those carried out by different groups of researchers in countries such as Germany, Switzerland, UK, Korea, USA and New Zealand. This paper also tries to portray a futuristic view of STEP-NC applications for CAD, CAPP, CAM and CNC integration, identifies the issues and challenges for STEP-NC, and provides a vision of a STEP-NC-compliant process chain supported by a product and manufacturing model.