基于维修的DFA/D系统设计

 DFX 是实现产品并行设计的重要工具，考虑到产品维修活动中的拆卸与装配问题，指出研究面向维修的DFA／D)的必要性．在借鉴传统DFA，DFD研究的基础上，阐明面向维修的DFA／D的结构设计及其关键技术，初步证明了面向维修的DFA／D作为设计工具实现维修性并行设计具有现实可行性．     

Functional characterisation of mechanical joints to facilitate its selection during the design of open architecture products

New trends in product design require the use of modularity as key feature aimed to improve functional performance and the generation of open architecture products. For mechanical systems, one of the challenges during early design stages of these products involves the proper selection of joining methods among their constructive components. A robust joint selection process must consider product requirements, life cycle analysis and eventual procedures for assembly and disassembly. However, the general approach towards a Design-for-Assembly (DFA)/Design-for-Disassembly (DFD) only considers design, manufacturing and in some cases final disposal stage. Additionally, most of the works found in the literature are merely focused on assembly operations, disregarding economic and environmental benefits from optimising disassembly complexity. Herein, a functional characterisation of mechanical joint methods for the assembly and disassembly activities that take place throughout the product life cycle is proposed, focusing on open architecture products. Additionally, a classification of joining methods, a joint complexity metric valuation and a selection process are proposed for the conceptual design stage. The approach integrates both DFA and DFD principles in a formal methodology. The proposed selection roadmap can be implemented to increase product sustainability positively regarding resources optimisation, operational time and costs in reuse, remanufacturing and recycling tasks.     

Identified research directions for using manufacturing knowledge earlier in the product life cycle

Design for manufacturing (DFM), especially the use of manufacturing knowledge to support design decisions, has received attention in the academic domain. However, industry practice has not been studied enough to provide solutions that are mature for industry. The current state of the art for DFM is often rule-based functionality within computer-aided design (CAD) systems that enforce specific design requirements. That rule-based functionality may or may not dynamically affect geometry definition. And, if rule-based functionality exists in the CAD system, it is typically a customisation on a case-by-case basis. Manufacturing knowledge is a phrase with vast meanings, which may include knowledge on the effects of material properties decisions, machine and process capabilities or understanding the unintended consequences of design decisions on manufacturing. One of the DFM questions to answer is: How can manufacturing knowledge, depending on its definition, be used earlier in the product life cycle to enable a more collaborative development environment? This paper will discuss the results of a workshop on manufacturing knowledge that highlights several research questions needing more study. This paper proposes recommendations for investigating the relationship of manufacturing knowledge with shape, behaviour and context characteristics of a product to produce a better understanding of what knowledge is most important. In addition, the proposal includes recommendations for investigating the system-level barriers to reusing manufacturing knowledge and how model-based manufacturing may ease the burden of knowledge sharing. Lastly, the proposal addresses the direction of future research for holistic solutions of using manufacturing knowledge earlier in the product life cycle.     

A topological model of limitations in design for manufacturing

Design for manufacturing (DFM) is a methodology that requires the use of specific manufacturing information at all stages of design. The method relies on a collection of informal and often controversial principles that seem to have eluded the benefits of formal analysis. The transition from design to manufacturing can be modeled as a mathematical mapping, and it has been previously shown how the discontinuity of this mapping formally captures the folklore that small design changes can lead to significantly increased manufacturing cost. We study the properties of the transition map in the presence of design and manufacturing variations, and show that its continuity is closely related to the structure of design and manufacturing topological spaces. The main result of this paper establishes conditions on these spaces under which design for manufacturing cannot be described by any continuous transition map. In practical terms, our study reveals the limitations of many DFM systems and approaches in their ability to relate design and manufacturing knowledge, and explains these limitations in terms of a basic incompatibility between the underlying design and manufacturing representations. We discuss how our model applies to DFM relative to traditional manufacturing methods (such as casting and stamping) and we speculate what changes might occur for alternative manufacturing technologies (such as electrical discharge machining (EDM), stereolithography, laser machining, and particle deposition).     

产品可装配性设计方法和使能技术研究

产品可装配性设计（ＤＦＡ）理论研究,对实施并行工程具有重要的意义,上前得到广泛的重视。本文从实现ＤＦＡ目标出发,提出了ＤＦＡ的设计系统模型,论述了ＤＦＡ设计方法的相关使能技术,如并行装配设计、装配结构和装配性能分析、装配约束分析、装配序列规划、装配公差分析等。     

Application of Axiomatic Design principles to control complexity dynamics in a mixed-model assembly system: a case analysis

The purpose of this paper is to test the validity of Axiomatic Design (AD)-based complexity theory as an explanatory construct and as a methodological guidance for the early detection of need for change in flexible manufacturing systems in order to maintain competitiveness even in turbulent environmental conditions. The AD approach postulates that there are general design principles that govern the behaviour of a system. This proposition is empirically investigated for a flexible mixed-model assembly system by the examination of a long-term study conducted in a medium-sized industrial company. The findings of the long-term study suggest the introduction of a company specific cycle of functional periodicity in combination with a set of functional requirements working together as a regular trigger to detect whether the system range is moving away from the once defined manufacturing system's design range. The paper extends the research work made in the field of AD by focusing on mechanisms that help to control the effects of time-dependent complexity in manufacturing (re)design. Examples of methods and lead measures are given that can be used by organisations in early detecting and controlling complexity driven efficiency losses in manufacturing systems.     

Object-oriented modelling of manufacturing information system for collaborative design

Object-oriented technology has been widely acclaimed as offering a revolution in computing that is resolving a myriad of problems inherent in developing and managing organisational information processing capabilities. Although its foundations arose in computer programming languages, object-oriented technology has implications for a wide range of business computing activities including: programming, analysis and design, information management, and information sharing. The problematic issues in the development of manufacturing software systems are related to the various characteristics of manufacturing systems, which are wide, dynamic and complex. Design for manufacturing (DFM) is the integrated practice of designing components while considering their manufacturability, and its benefits are widely acknowledged in the industry. A model has been developed using object oriented technology, after analysing the fundamental elements necessary for modelling manufacturing and process planning framework used in collaborative design and manufacturing in machine tool manufacturing. The main components of this model are: process planning model (PPM), manufacturing activity model (MAM), manufacturing resource model (MRM) and manufacturing cost and time model. We are using ontologies in conjunction with specific conceptual models, which can contribute to improve the interoperability between these models. The performance of this model is shown by means of one real world case. The developed manufacturing information based design tool integrated with an intelligence design system can be used for collaborative design and manufacturing, which will support machine tool designers’ to achieve cost effective and timely design.     

A multi-criteria model for evaluating design for manufacturability

The design for manufacturability (DFM) method is most effective when integrated with the new product development (NPD) process. Due to the focused nature of the associated product and process knowledge and the extensive effort required, there are many NPD situations where classical DFM techniques cannot be readily applied. In this paper, Pro-DFM a multi-criteria model for manufacturability analysis that identifies product realisation opportunities (PRO) for cost reduction is presented. The key assumption in Pro-DFM is that the NPD team has a baseline estimate of production costs, and the evaluation question is how DFM issues will affect the expected unit production cost. The Pro-DFM model analyses a new design in three different factors: part procurement and handling, product assembly fabrication processes, and inventory costs. Each of these is independently analysed using a hierarchy of multiple criteria and sub-criteria. This approach is found to be amenable to most NPD processes, and conducive to easy integration. Each evaluation sub-criterion is presented in the form of a simple query, which is associated with a set of responses that is flexibly anchored to a uni-dimensional scale. A case study example is used to demonstrate the DFM evaluation process and the derivation of the cost penalties.     

Proactive assessment of basic complexity in manual assembly: development of a tool to predict and control operator-induced quality errors

A major challenge for manufacturing companies today is to manage a huge amount of product variants and build options at the same time in manufacturing engineering and in production. The overall complexity and risk of quality errors in manual assembly will increase placing high demands on the operators who must manage many different tasks in current production. Therefore, methods for decreasing and controlling assembly complexity are urgent because managing complex product and installation conditions will result in distinct competitive advantages. The objective of this paper is to present a method for predictive assessment of basic manual assembly complexity and explain how included complexity criteria were arrived at. The verified method includes 16 high complexity and 16 low complexity criteria to aid designers in preventing costly errors during assembly and create good basic assembly conditions in early design phases of new manufacturing concepts.     

A roadmap for Assembly 4.0: self-configuration of fixed-position assembly islands under Graduation Intelligent Manufacturing System

The layout of fixed-position assembly islands (FPAI) is widely used for producing fragile or bulky products. With the increasing customised demand and unique operation patterns, manufacturing practitioners are facing challenges on flexible and efficient production arrangement to meet customer demand, which lead to inappropriate assembly islands configuration, frequent setups and long waiting times in FPAI. Industry 4.0 comes with the promise of improved flexibility and efficiency in manufacturing. In the context of Industry 4.0, this paper proposes a 5-layer APICS (assembly layer, perception layer, interaction layer, cognition layer, and service layer) roadmap for transformation and implementation of Assembly 4.0. Following the 5-layer APICS roadmap, a Graduation Intelligent Manufacturing System (GiMS) is presented as the pioneering implementation in FPAI. A graduation-inspired assembly system is designed for FPAI at assembly layer. Internet of Things (IoT) and industrial wearable technologies are deployed for perception, connection, and collaboration among various manufacturing resources at perception and interaction layer. A self-configuration model is proposed at cognition layer for autonomously configuring optimal assembly islands and corresponding production activities to meet customer demand. Cloud-based services are developed for managers and onsite operators to facilitate their decision-making and daily operations at service layer. Finally, a demonstrative case is conducted to verify the feasibility of the proposed methods.     

Integrated scheduling and self-reconfiguration for assembly job shop in knowledgeable manufacturing

The problems of integrated assembly job shop (AJS) scheduling and self-reconfiguration in knowledgeable manufacturing are studied with the objective of minimising the weighted sum of completion cost of products, the earliness penalty of operations and the training cost of workers. In AJS, each workstation consists of a certain number of teams of workers. A product is assumed to have a tree structure consisting of components and subassemblies. The assembly of components, subassemblies and final products are optimised with the capacity of workstations simultaneously. A heuristic algorithm is developed to solve the problem. Dominance relations of operations are derived and applied in the development of the heuristic. A backward insertion search strategy is designed to locally optimise the operation sequence. Once the optimal schedule is acquired, the teams are reconfigured by transferring them from workstations of lower utilisation to those of higher utilisation. Effectiveness of the proposed algorithm is tested by a number of numerical experiments. The results show that the proposed algorithm promises lower total cost and desirable simultaneous self-reconfiguration in accordance with scheduling.     

Design for manufacturing: application of collaborative multidisciplinary decision-making methodology

Design for manufacturing is often difficult for mechanical parts, since significant manufacturing knowledge is required to adjust part designs for manufacturability. The traditional trial-and-error approach usually leads to expensive iterations and compromises the quality of the final design. The authors believe the appropriate way to handle product design for manufacturing problems is not to formulate a large design problem that exhaustively incorporates design and manufacturing issues, but to separate the design and manufacturing activities and provide support for collaboration between engineering teams. In this article, the Collaborative Multidisciplinary Decision-making Methodology is used to solve a product design and manufacturing problem. First, the compromise Decision Support Problem is used as a mathematical model of each engineering teams’ design decisions and as a medium for information exchange. Second, game-theoretic principles are employed to resolve couplings or interactions between the teams’ decisions. Third, design-capability indices are used to maintain design freedom at the early stages of product realization in order to accommodate unexpected downstream design changes. A plastic robot-arm design and manufacturing scenario is presented to demonstrate the application of this methodology and its effectiveness for solving a complex design for manufacturing problem in a streamlined manner, with minimal expensive iterations.     

并行环境下面向装配设计的集成化建模技术

在分析了DFA的主要内容的基础上 ,为了对设计者提供一个友善的集成化DFA分析环境和工具 ,提出了一种适合于对产品可装配性进行分析和评价的集成化的产品信息模型 .该模型能完整地储存产品的装配信息 ,有效地为面向装配设计的各个活动提供集成化的信息支持     

制造及其系统的创新与管理的发展

从制造业面临的形势分析出发,介绍了先进制造战略、技术、制造系统与系统管理的最新研究成果。并指出在建立现代企业制度中,制造战略、产品开发、质量保证和优化动作是３个增强竞争力的基本技术。     

Balancing of mixed-model parallel U-shaped assembly lines considering model sequences

As a consequence of increasing interests in customised products, mixed-model lines have become the most significant components of today’s manufacturing systems to meet surging consumer demand. Also, U-shaped assembly lines have been shown as the intelligent way of producing homogeneous products in large quantities by reducing the workforce need thanks to the crossover workstations. As an innovative idea, we address the mixed-model parallel U-shaped assembly line design which combines the flexibility of mixed-model lines with the efficiency of U-shaped lines and parallel lines. The multi-line stations utilised in between two adjacent lines provide extra efficiency with the opportunity of assigning tasks into workstations in different combinations. The new line configuration is defined and characterised in details and its advantages are explained. A heuristic solution approach is proposed for solving the problem. The proposed approach considers the model sequences on the lines and seeks efficient balancing solutions for their different combinations. An explanatory example is also provided to show the sophisticated structure of the studied problem and explain the running mechanism of the proposed approach. The results of the experimental tests and their statistical analysis indicated that the proposed line design requires fewer number of workstations in comparison with independently balanced mixed-model U-lines.     

一种基于约束的并行设计方法研究

在简化QFD分析过程和矩阵框架的基础上，提出了一种支持并行工程的设计约束展开（DCD）方法。该方法将适用对象由QFD方法中单纯的顾客需求扩展到并行工程整个产品生命周期中的所有约束，使得分析过程更具灵活性，并为并行设计过程提供了一个一致的环境。讨论了DCD方法中约束的确定和矩阵的结构与算法两个问题，并以DFA为例给出了一个DCD方法的应用实例。     

高校飞行器制造工程专业的综合实验课程教学研究

针对高校飞行器制造工程专业的综合实验课程教学,论文提出了设置飞机数字化设计制造一体化技术实验、飞机钣金精密塑性热成形工艺教学实验、飞机数字化柔性装配教学实验及飞机复合材料构件设计制造一体化技术等四大实验系列共14个实验的教学设想。这些实验既涉及传统的飞机制造工艺,也包括最新的飞机研制信息化手段。完成上述实验可提高本专业学生的动手能力,加深对飞行器产品制造过程各项知识点的理解。     

Simulation modelling and analysis of scheduling in robotic flexible assembly cells using Taguchi method

Due to increasing competition in the developing global economy, today’s companies are facing greater challenges than ever to employ flexible manufacturing systems (FMS) capable of dealing with unexpected events and meeting customers’ requirements. One such system is robotic flexible assembly cells (RFACs). There has been relatively little work on the scheduling of RFACs, even though overall scheduling problems of FMS have attracted significant attention. This paper presents Taguchi optimisation method in conjunction with simulation modelling in a new application for dynamic scheduling problems in RFACs, in order to minimise total tardiness and number of tardy jobs (N_T). This is the first study to address these particular problems. In this study, Taguchi method has been used to reduce the minimum number of experiments required for scheduling RFACs. These experiments are based on an L9 orthogonal array with each trial implemented under different levels of scheduling factors. Four factors are considered simultaneously: sequencing rule, dispatching rule, cell utilisation and due date tightness. The experimental results are analysed using an analysis of mean to find the best combination of scheduling factors and an analysis of variance to determine the most significant factors that influence the system’s performance. The resulting analysis shows that this proposed methodology enhances the system’s scheduling policy.