Development of Expert System for Concurrent Product Design and Planning for Assembly

This paper addresses the development of an expert system for concurrent product design and assembly planning (CDAPFAES) including conceptual design, detailed design, assemblability analysis and design for assembly, assembly system design, assembly process planning and stimulation, and technical–economics justification. This approach is implemented through an agent-based framework with concurrent integration of multiple cooperative knowledge sources and software. This intelligent system can offer systematic assistance for assembly design and planning in the early stage of product development and facilitate, as far as possible, the use of flexible assembly equipment, including robots. Finally, this new design methodology is illustrated with a successful implementation of a switch product design.     

Managing modularity in product family design with functional modeling

Recent market transition from mass production to mass customization forces manufacturers to develop product families with a common platform to increase design variety, shorten time-to-market, and reduce production costs. This paper presents a new functional modeling approach to support identification of both shared and individual behavioral modules across a family of products for module-based product family design. After separate functional modeling of each product variant, the individual functional models are merged into a single, coherent, and unified family functional model to determine all the shared and individual behavioral modules. The modularity in the family functional model is further explicitly identified using a behavioral modularity matrix of product variants versus behavior. The proposed approach provides a fast method for generating new concept variants during the conceptual design of a family of products. The rationale of managing modularity in product family design with functional modeling is manifested using a modular design example of a family of automatic assembly devices.     

Dimensional and geometrical tolerance balancing in concurrent design

In conventional design, tolerancing is divided into two separated sequential stages, i.e., product tolerancing and process tolerancing. In product tolerancing stage, the assembly functional tolerances are allocated to BP component tolerances. In the process tolerancing stage, the obtained BP tolerances are further allocated to the process tolerances in terms of the given process planning. As a result, tolerance design often results in conflict and redesign. An optimal design methodology for both dimensional and geometrical tolerances (DGTs) is presented and validated in a concurrent design environment. We directly allocate the required functional assembly DGTs to the pertinent process DGTs by using the given process planning of the related components. Geometrical tolerances are treated as the equivalent bilateral dimensional tolerances or the additional tolerance constraints according to their functional roles and engineering semantics in manufacturing. When the process sequences of the related components have been determined in the assembly structure design stage, we formulate the concurrent tolerance chains to express the relations between the assembly DGTs and the related component process DGTs by using the integrated tolerance charts. Concurrent tolerancing which simultaneously optimizes the process tolerance based on the constraints of concurrent DGTs and the process accuracy is implemented by a linear programming approach. In the optimization model the objective is to maximize the total weight process DGTs while weight factor is used to evaluate the different manufacturing costs between different means of manufacturing operations corresponding to the same tolerance value. Economical tolerance bounds of related operations are given as constraints. Finally, an example is included to demonstrate the proposed methodology.     

现代产品设计方法及其演进

为了更好地体会现代产品设计的本质，有必要对产品设计的特点和方法学的演进进行分析。传统串行产品设计与开发的各领域间缺乏信息的交流，产品设计不具备全局的考虑，造成因返工带来的时间与资源浪费。针对该弊端，并行工程提出集成／并行的产品与过程设计，通过团队协作与过程重组，使产品设计得到优化。虚拟制造则强调在产品加工之前，通过拟实模型提高产品设计的可靠性。基于上述要求，提出了３种可行的产品设计方法，其中产品综合平衡设计方法兼顾了面向型产品设计方法和拟实型产品设计方法的特点，从内在结构和外部机制上以更大的柔性使设计能够保证产品最终的ＴＱＣＳ指标。同时该方法为实现支持现代产品设计的软件环境打下理论基础。     

Assembly Process Design for Managing Manufacturing Complexities Because of Product Varieties

This paper comprehensively studies assembly process design (APD) to handle variety and presents a new approach to strategically manage manufacturing complexities because of product varieties. It links the chronological steps of APD to a general approach with a view to reduce both short and long term wastes. It synthesizes two strategic approaches, product and process-based, while exploiting the APD of an entire product family. A new evaluation method for measuring the complexities of an assembly system at different stages of design has been introduced by applying information entropy. The developed evaluation methodology explains the available techniques related to design, interprets them from a design for variety point of view, and leads to techniques to manage complexities in manufacturing. The suggested methodology has been applied to examples from automobile part manufacturers and has been found to be effective in understanding the complexities in manufacturing and leading to some strategies to manage variety.     

面向并行设计的模具装配模型描述

通过对传统模具ＣＡＤ系统的分析及目前并行工程等先进制造理论对新型模具ＣＡＤ系统的要求,基于一般模具设计过程及ＥＸＰＲＥＳＳ－Ｇ的研究,提出了面向并行设计的模具装配描述模型,同时讨论了已有装配模型的不足。基于此模具装配模型,解释了实现并行设计的方法与过程     

产品并行设计技术研究

本文提出了基于集成产品信息模型，实现产品并行设计的体系结构。在产品设计过程中采用分阶段策略，基于知识对产品设计进行评价，及时指导产品设计，从而优化产品及其设计过程。     

面向ASP与DFA集成系统的装配模型技术

针对并行工程中的产品装配设计与优化分析 ,提出了一种装配顺序规划与为装配而设计相集成的产品装配分析系统。重点分析研究了集成系统中的产品装配建模方法。首先对现有的各种典型的装配模型技术进行分析比较 ;其次 ,根据 ASP与DFA集成系统的需求 ,设计出了一种包含装配草图、装配关联图信息、装配结构树图、零件设计参数和连接参数等信息的装配模型结构。并结合实例分析了该装配模型的计算机实现方法     

工艺规划为核心的产品协同研发生产平台

为实现具有市场竞争力产品的高端研发,并具备较高的质量及成本控制能力,文中提出构建以工艺规划为核心的产品数字化研发生产平台的解决思路.平台框架包含计算机辅助设计、产品数据管理、计算机辅助工艺规划和协同制造模块;通过工艺与设计、生产两端的数据共享,实现设计、工艺数据和生产的高效协同;通过工艺规划方案的功能描述,展现了一个为...     

基于DFA和DFC的综合公差优化

公差是机械设计和制造过程中最重要的参数之一,其对加工成本和产品质量有很大的影响。本文采用 DFA和DFC的综合方法对制造过程中的装配精度进行分析和综合,建立了以公差为主的成本信息模型,对设计公 差和加工公差进行了系统分析,以最低制造成本为目标,根据成本 公差间的函数关系,建立了非线性的公差优化模 型,并采用遗传算法使这一问题得到了很好的解决。实例证明该方法是可行的。并为并行工程实施中其他的DFX 与DFC结合实现制造成本最低提供了良好的解决方案。     

RESEARCH ON PRODUCT INNOVATION DESIGN IN VIRTUAL PRODUCT DEVELOPMENT

An integrated template of virtual product development alters primarily sequential tradition mode of product lifecycle. The template integrates all processes of product development using digital modern. An environment of virtual product development provides product development environment of integration, communion, network, concurrent and collaboration. Combining development of new rapier loom, an innovated design process is researched in virtual product development, which consists three portions: constructing an integration development environment, innovation design andmanufacturing simulation. The innovated design process realizes reverse design, mechanism concept design, structuraldesign and analysis, performance analysis and manufacturing process simulation of virtual product, which can enhancegreatly product performance and reduce cost and development cycle of new product.     

A connector-based approach to the modular formulation problem for a mechanical product

To respond to marketing competition, companies strive to provide a large variety of products to meet consumers requirements. With more choices in products, such variety brings the company closer to the consumers. However, manufacturers are facing a new challenge. The assembly and partitioning of components and subassembly are becoming increasingly more complicated, which cause not only a proliferation of subassemblies but also increases the difficulty in manufacturing. To solve this problem, modular design is a key issue.This study presents a methodology for the formulation of modules on the basis of the connector concept. Based on the information entry in the assembly network sequence proposed by Tseng and Li [12], a modular partition based on the connector concept is explored. Moreover, the problem of assigning components after partitioning and the evaluation of the partitioning results are discussed.In this study, the definition and representation of connectors are described first. Then, the algorithm for the formulation of modules is discussed. Finally, a case study with a detailed analysis is provided to illustrate the application of the proposed methodology.     

Production engineering-oriented virtual factory: a planning cell-based approach to manufacturing systems design

In the traditional process of designing a manufacturing system, a sequential approach treats each of the design steps individually, without considering the requirements of concurrent design activities. The lack of systematic and concurrent consideration of the interactive impact of design decisions leads to repeated and excessive changes in the design and process. To resolve this problem, this research develops a production engineering-oriented virtual factory – a planning cell-based manufacturing systems design approach. The manufacturing systems design process based on a planning cell is reengineered according to the concept of concurrent engineering. The process modeling of a production engineering-oriented virtual factory is proposed at generic and particular levels. An illustrative example of an engine assembly plant demonstrates the effectiveness of the new approach.     

支持变型设计的装配模型建模方法研究

指出产品结构变型的两种基本形式:纵向布局结构变化和横向布局结构变化。提出了支持变型设计的装配模型——“顶层基本骨架”的建模理论和方法。在装配模型层次化的基础上,将“项层基本骨架”作为自顶向下设计过程中信息传递的纽带,并以Pro/E为技术平台,通过具体设计实例,展示了产品变型设计的过程。     

面向协同装配规划的装配单元规划方法

作为复杂产品装配规划的有效求解策略,协同装配规划将复杂产品的装配规划结构按照装配要求分解为简单的子装配规划结构,子装配规划结构的最优或次优装配序列采用成熟的装配规划方法求解,通过装配序列合并得到产品的整体装配序列。协同装配规划所要解决的首要问题是装配规划结构分解,针对这个问题,提出装配单元规划方法。首先从产品可装配性的角度分析了影响装配单元规划的装配设计和装配工艺约束,并对归类的部分装配约束进行量化;进而基于模糊层次分析法生成装配单元决策图,采用最小生成树算法生成候选装配单元。同时,建立装配关系干涉矩阵对候选装配单元进一步验证,生成装配过程中互不干涉的装配单元。以一款电动机装配体为例验证提出的方法,结果表明该方法是一种求解装配规划结构分解问题的有效方法。     

基于WAVE和克隆装配的车身变形设计

以UG软件为设计研究平台,利用WAVE技术建立车身产品的控制结构和控制参数编辑器,采用WAVE和克隆装配技术完成车身的变形设计。满足不同消费者的要求,缩短产品开发周期,降低产品开发成本和制造成本,适应瞬息万变的市场需求。     

面向自顶向下设计的装配模型研究

装配模型是支持数字化产品设计和制造的重要基础。设计人员通过装配建模表达产品的功能形状和设计师的设计意图。本文针对自顶向下设计模式对装配模型的特殊要求 ,提出一种面向自顶向下设计的装配模型 ,支持产品设计过程中的多种设计活动。给出了模型的维护方法 ,为自顶向下的装配设计提供了安全的数据支持。该模型为产品装配的自顶向下设计提供了良好的模型基础。     

支持并行产品开发的数据集成方法研究

并行产品开发的基本支持条件之一是计算机辅助工具之间必须实现信息集成，目前，大多数ＣＡｘ系统仍缺乏支持产品生命周期信息集成的手段，特别是ＣＡＤ与ＣＡＰＰ之间的特征集成，至今仍是一个未解决的难题。ＳＴＥＰ方法的提出为ＣＡｘ／ＤＦｘ集成确定了总体方向。本文根据８６３／ＣＩＭＳ关键技术攻关项目“并行工程”的需求，利用ＳＴＥＰ开发工具，通过对ＣＡＤ特征再建模的方法支持ＣＡＤ与ＤＦＭ／ＣＡＰＰ／ＣＡＭ／ＣＡＦ     

Resource Portfolio Planning Methodology for Semiconductor Wafer Manufacturing

Resource portfolio planning is a frequent task in semiconductor wafer fabrication plants, as process, machine and product technologies evolve rapidly and the plants go through capacity expansion. As wafer fabrication plants are complex integrated factories with conspicuous queuing effects, portfolio planning must take into consideration machine use, factory throughput, and total flow-time simultaneously. This paper describes a resource portfolio planning methodology for wafer fabrication foundry plants. An improved static capacity model is first presented. A portfolio planning procedure based on static capacity estimation and queuing analysis is next described. This procedure enables the solution space of resource portfolios to be explored effectively and has demonstrated a capability superior to the current planning method in an industry case study. A software implementation of the procedure is also used to clarify planning dilemmas. It is shown that empirical formulae can be used to estimate the efficiency of batch machines. It is also used to show three types of portfolio adjustment action: flow-time reduction, cost reduction and effectiveness improvement.     

An automated assembly environment in feature-based design

In the integration of design and manufacturing, one of the primary techniques is to evaluate the parts in the assembly so that the labour cost can be reduced. In this paper, the mechanical parts within the design and assembly are examined, and an integrated architecture of an assembly model is proposed which includes a proper assembly environment, the interface between the assembly model and feature-based design, and a knowledge-based expert system for assembly analysis. In order to determine satisfactory plans for assembly and to achieve the required functions in the product model, explicit relational information between the major components is implemented. The evaluation of interference checking of the parts and the geometric tolerances (such as perpendicularity, parallelism, and angularity) of the parts in the assembly model are also studied.