An Intelligent Knowledge-Based System for Product Cost Modelling

An intelligent knowledge-based system for product cost modellingis presented in this paper. The developed system has the capability of selecting a material, as well as machining processes and parameters based on a set of design and production parameters; and of estimating the product cost throughout the entire product development cycle including assembly cost. The proposed system is applied without the need for detailed design information, so that it can be used at an early design stage, and, consequently, redesign cost and longer lead time can be avoided. Hybrid knowledge representation techniques, such as production rules, frame and object oriented are employed to represent manufacturing knowledge. Fuzzy logic-based knowledge representation is applied to deal with uncertainty in the knowledge of cost model to generate reliable cost estimation. This paper deals with cost modelling of both a machining component and an injection moulding component, which is a process that gives high production rates, excellent quality and accuracy of products, and low manufacturing cost. Based on the analysis of the moulded product life cycle, a computer-based cost model was developed which integrated the relationship between cost factors, product development activities, and product geometry. The estimated cost included the costs of material, mould and processing. The system has been validated through a case study.     

基于KBE的大型复杂冲压件工艺信息模型

运用KBE和特征技术 ,采用多种知识表达方法实现了对大型复杂冲压件工艺信息知识的描述 ,并建立了完整工艺信息知识模型 ,实现了高层次全局信息的表达。     

汽车覆盖件工艺规划的发展及基于知识的智能CAPP系统研究

通过综述典型的汽车覆盖件CAPP系统，指出了目前覆盖件CAPP系统存在的问题和主要原因，提出了利用智能化、系统化和集成化技术开发汽车覆盖件CAPP系统的发展趋势，建立了基于知识的覆盖件智能CAPP系统和覆盖件产品设计管理一体化系统工程的框架，结合实例阐述了采用智能化技术和CAD工具开发覆盖件CAPP系统的方法。     

多目标质量的覆盖件成形工艺参数优化

覆盖件冲压是复杂的塑性变形过程,成形工艺参数较多,难以精确地建立工艺参数与成形质量之间的关系。选取优化合理的工艺参数匹配是保证无破裂、无起皱和板料厚度均匀分布等成形质量的关键。通过将压边力、拉深筋高度、凸筋圆角半径、凹筋圆角半径、摩擦因数作为自变量的条件下,以正交试验为设计方案,模拟轮包覆盖件成形,获得成形质量目标破裂、起皱、厚度最大变薄率的数据。通过层次分析法计算多质量目标的权重,利用灰色系统理论,分别计算成形质量对理想单目标值的关联系数和多目标函数的关联度,进一步计算获得各成形工艺参数的平均关联度,用优化的工艺参数进行有限元模拟验证,最终指导设计、试模,板料冲压结果表明成形的质量明显提高。     

基于知识工程的大型复杂冲压件工艺方案设计

运用知识工程和特征技术实现了大型复杂冲压件工艺知识的完整表述及其知识模型的建立,并通过冲压工艺知识驱动对应的智能决策机制完成了工艺特征的映射及工艺方案的智能设计,有效地解决了基于图形、规则及经验知识的决策判断,以及计算、分析与推理判断的融合问题.基于知识工程的工艺设计提升了大型复杂冲压件工艺方案设计的智能化程度,提高了设计的质量和效率,减少了工艺设计对设计人员经验的依赖.     

A Prototype Knowledge-Based System for Conceptual Synthesis of the Design Process

This paper presents a knowledge-based system "KBCS", the "Knowledge-based conceptual synthesiser" that supports the synthetic phase of conceptual design. It was developed using an expert system shell called CLIPS. By using this knowledge, physical behaviour can be derived from a desired function or desired behaviour, and a functional model which represents causal relationships among the functions and behaviours can be created. In addition, complicated desired functions which cannot be matched with the functional output of any behaviour after searching the object-oriented behaviour base, will be automatically decomposed into subfunctions by means of relevant function decomposition rules. A case study for the conceptual synthesis of an automatic assembly system provides an application of this intelligent design environment, and a demonstration of its methodology. In this paper we also describe how two popular AI representation techniques, object-oriented representation and production rule representation, can be usefully integrated to solve the problem.     

An Automated Process Planning and Die Design System for Quasi-Axisymmetric Cold Forging Products

This paper deals with an automated computer-aided process planning and die design system with which a designer can determine operation sequences even after only a little experience in process planning and die design of quasi-axisymmetric cold forging products by multistage former working. The approach is based on knowledge-based rules, and a process knowledge base consisting of design rules is built. Knowledge for the system is formulated from plasticity theories, empirical results and empirical knowledge of field experts. Programs for the system have been written in AutoLISP for AutoCAD with a personal computer. An attempt is made to link programs incorporating a number of expert design rules with the process variables obtained by commercial FEM software, DEFORM and ANSYS, to form a useful package. The system is composed of three main modules and five submodules. The process planning and die design module considers several factors, such as the complexities of preform geometry, punch and die profiles, specifications of available multiformers, and the availability of standard parts. The system uses 2D geometry recognition and is integrated with the technology of process planning, die design, and CAE analysis. The standardisation of die parts for wheel bolts requiring a cold forging process is described. The system developed makes it possible to design and manufacture quasi-axisymmetric cold forging products more efficiently.     

A Graph Representation Scheme for Process Planning of Machined Parts

A new generic graph representation scheme for process planning is presented. It has been specifically developed to facilitate the planning and control of geometric dimensions and tolerances. Relationships between cut, location, and datum surfaces and machining operations are represented by a graph consisting of connected boxes. A box is a multi-terminal node that corresponds to a machine set-up. Machining operations are depicted as arrows inside the box. These connect input nodes, representing datum and location surfaces, to output nodes, representing machined surfaces. External connectors join boxes together to form a directed graph. The main purpose of these connectors is to indicate the surfaces (from prior set-ups) that are used as location and datum surfaces for later set-ups. The representation covers cutting operations and non-cutting operations, such as surface finishes and coatings. The paper concludes with an example that illustrates the application and power of the scheme.     

基于油液分析的汽车发动机摩擦系统故障诊断专家系统知识库的建立

采集汽车发动机润滑系统中摩擦副经历磨擦学行为的信息是诊断发动机摩擦系统故障的有效手段。油液分析从摩擦学系统的润滑剂和磨损物两方面获得磨擦副的润滑和磨损状态的信息。但常规的油液分析信息处理方法上的不足影响了油液分析技术在汽车行业的实际应用,开发基于油液分析的故障诊断系统,无疑会改善油液分析的诊断准确性和诊断成本。本文着重针对该诊断专家系统知识库的建立,     

H机械公司某新产品发动机推杆的工艺规程设计

在某校“校企联合”人才培养模式的背景下,结合企业实际典型产品,对某H机械公司的某发动机推杆零件生产的工艺规程进行了设计。     

基于UG的汽车车门外板曲面重构

在Imageware中完成了点云的三角化处理后,导入UG软件中进行曲面重构,最终建立车门外板三维模型并进行了必要的曲面质量分析。通过UG对车门外板的反求,为逆向工程的实现提供了有价值的参考。     

基于Dynaform的汽车覆盖件拉延成形有限元模拟分析

基于Dynaform软件的基础,探讨了汽车覆盖件拉延成形过程有限元分析的关键步骤,重点研究了零件网格划分、工艺补充面建立、毛坯形状尺寸估算、拉延筋设置等关键内容以及模拟过程中应注意的问题。并利用Dynaform软件对该零件进行了拉延过程的有限元分析,根据模拟分析的结果,对拉延筋尺寸和分布方式以及工艺补充面的主截面线参数等工艺参数进行了优化调整,消除了拉裂及起皱现象,给出了相应的拉深工艺优化方案。     

Research of knowledge-based hammer forging design support system

Die design is experience-extensive in the field of plasticity engineering, in which knowledge and experience play a very important role in supporting the design process. In order to make good use of the accumulated engineering knowledge, the methodology of knowledge-based hammer forging design support is elaborated in detail, including: engineering knowledge representation, knowledge acquisition and knowledge-based design support techniques. Based on these, a knowledge-based hammer forging design support system is developed using the API of SolidWorks. This prototype system is a design guide system, which provides the right knowledge to support the designer, make decision/selection and design the die step by step. This way, the computerized public and private knowledge can be greatly shared and reused, which improves the design efficiency, and avoids previous mistakes effectively. Finally, a case study is shown to elaborate how the system is operated.     

An Operation Planning System for Multi-Axis Milling of Sculptured Surfaces

Multi-axis milling of sculptured surfaces with cylindrical or toroidal cutters has many advantages compared to the use of three-axis milling with ball nose cutters. Surfaces to be machined are often of complex shape and characterised by convex, concave and saddle areas. Today, CAM-systems do not support the user in the selection of the different operations in order to finish the workpiece. This paper describes an operation planning system, which facilitates process planning for the multi-axis machining of sculptured surfaces. The core of the system is surface analysis, which divides the surfaces into regions, each characterised by a preferred milling direction and tool diameter. Further, for each region or set of regions, a drive surface is constructed that is used as the basis for the tool-path calculation. The drive surface approximates to the original workpiece as closely as possible, and the isoparametric lines which will be the tool-path feed direction lie in the preferred milling direction.     

专用机床夹具设计及其知识库系统的研究与应用

通过对专用机床夹具设计方法的分析 ,建立了基于知识的 CF- CAFix设计系统。对其中的知识库系统 ,采用框架 /规则相结合的知识表示方法和参数化图形处理技术 ,创建底层的种子件 ,形成种子组合和种子结构。以动态建模的方法 ,生成具有属性和尺寸数据参数化的常用件库、常用组合库以及典型结构库 ,结合实例库 ,大大地提高了夹具设计的自动化程度     

Process Planning Using Adjacency-Based Feature Extraction

The use of attributed adjacency (AA) feature recognition can encapsulate the engineering significance of a part and represent it as a matrix or an arc-node graph. This creates a feature recognition technique that involves scanning a matrix or graph for a combination of zeros (concave relationships/edges) and ones (convex), or smaller arc-node graphs that are predetermined to be features. AA techniques have often suffered problems when dealing with feature interactions, as a feature found must be exactly matched with those stored. This paper presents a modification of the AA matrix and employs a new concept for identifying features and the application in developing software for process planning. A unique feature taxonomy is described, which when combined with the new feature identification system creates a feature recognition and extraction system that includes curved surfaces and eliminates the need for separating interacting primitive features. The new system takes its input from neutral STEP files and produces a list of features with complete information for process planning. cycle, and so automatic feature recognition has its place in manufacturing. ID="A1"Correspondance and offprint requests to: R. Ibrahim, Faculty of Engineering, Monash University, Caulfield Campus, 900 Dandenong Road, Caulfield East, 3145 Victoria, Australia. E-mail: raafat. ibrahim@eng.monash.edu.au     

工业色谱仪谱峰识别参数的自整定

针对智能工业色谱仪的谱峰数据处理问题，提出谱峰识别参数类型的确定方案，介绍了在嵌入式系统中实现识别参数自整定的方法。该研究已用于国产工业色谱仪，提高仪器的智能化功能，方便仪器的现场应用，并在工业流程的使用中取得较好效果。     

并行产品开发过程分析与重组方法研究与实现

产品开发过程分析与重组是企业实施并行工程的前提和基础。分析并行产品开发过程的特点 ,提出面向并行工程的产品开发过程分析、改进与重组的基本方法与步骤 ,建立产品开发过程分析与重组的过程模型 ,并针对齐车公司产品开发过程的实际情况 ,对现有的粮车产品开发过程进行分析、改进与重组 ,建立集成产品开发团队 ,并取得令人满意的效果     

基于服务的工艺设计方法

为实现工艺过程的快速设计以满足企业对工艺设计应用系统实用化、集成化、柔性化和网络化的需求,提出了基于服务的工艺设计方法,包括工艺设计领域建模、工艺设计服务的规划以及服务化工艺设计平台搭建3个方面。结合领域分析方法,建立了工艺设计领域模型,对工艺设计领域进行分析与界定,分别以粗、细2种粒度划分工艺设计服务,提供面向服务的数据访问服务和工艺业务服务调用。给出了服务化工艺设计平台体系,采用开源的面向服务架构技术进行了系统实现。以齿轮轴工艺设计为例,说明了工艺设计服务划分和工艺设计服务调用在该平台上的应用。     

后轮罩封板翻边工艺优化研究

以汽车后轮罩封板为研究对象,对其翻边成形工艺进行分析,指出翻边缺陷产生的实质是翻边边缘切向应变的绝对值超过成形极限;以减小翻边边缘处切向应变绝对值为优化指标,对影响翻边成形性能的三个工艺参数:压边力、摩擦润滑条件、模具间隙进行正交设计,运用有限元模拟软件Dynaform进行模拟试验得到优化工艺方案;最后对优化方案进行实验验证,结果表明,数值模拟试验是可靠的,得到的优化方案可以避免翻边成形中的缺陷。