完美防错(PEP)体系在汽车零部件制造业的应用

在高标准的汽车零部件制造业,防错的应用能防止或大大降低不良产品的产生和流出,有助于建立零缺陷的生产过程。介绍一套汽车部件制造业的系统的完美防错体系,说明如何构建完美防错体系,并如何通过计量化等手段进行全方位的维护管理,最终杜绝质量风险,持续减少质量成本,确保客户满意。     

Design and implementation of Web-based diagnosis and management system for an FMS

Given the rise in competition within the global marketplace, the paradigm for manufacturing has changed dramatically. While downstream activities have become the focal point for global competitors, manufacturing remains at the root of a firm’s competitive edge. To remain competitive, firms are progressively shifting their manufacturing operations to overseas markets. Foreign markets offer a host of advantages to manufacturers but one of the obvious key advantages is cheaper labor. Even in industries where the required labor-to-capital input ratio is relatively low within the production process, lower labor costs allow the production of more competitively priced products. The emergence of this paradigm, however, has led to a number of managerial problems. Operating a manufacturing facility overseas creates difficulties for management both in the area of personnel and resource allocation. In this project we developed a Web-based remote control platform using digital cameras, a PLC controller and a PC-based Visual Basic human-machine interface (HMI) to create a flexible manufacturing system (FMS). An FMS can be easily controlled and monitored through an Internet-based PLC-control system using a PC-based HMI platform. From remote locations, this platform enables management to effectively monitor, control and diagnose a manufacturing process via the Internet.     

An Information Modelling Framework to Support Intelligent Concurrent Design and Manufacturing of Sheet Metal Parts

Sharing of information is an important issue in supporting integrated and rapid product development. The use of information modelling technology is a promising approach for solving the problems of the intensive sharing of information in a concurrent and rapid product development cycle. This paper explores the definition and the structure of a framework of information modelling for the concurrent design and manufacturing of sheet metal parts. This framework aims to build an information bridge to fill the gap between the sheet metal part design and manufacturing systems. It is based on abstract handling principles of entities called zero thickness and zero bend radius principles. Based on this framework, information models can be built for information sharing by different systems. Knowledge bases that support intelligent concurrent design and manufacturing can also be created. In this paper, a two-branch tree based stepping-structure information modelling methodology for sheet metal parts is described, and a case study is given.     

虚拟制造环境下模特法的应用

在虚拟制造环境下，应用模特法对制造系统进行作业测定，制定标准时间，突破了模特法一般应用在现实制造系统进行作业测定的传统应用范围，进而为虚拟制造系统优化设施布局、编制生产计划、确定劳动力需求计划提供了方法和依据，避免了生产系统投产后调整布局及人员配置等所花费的人力和物力。最后，给出了一个实例验证。     

Java-based computer-aided process planning

This investigation addresses distributed environments for computer-aided process planning (CAPP) over a network. The Java 2 Enterprise Edition (J2EE) standard using Java is applied to implement cross-platform and distributed computing architecture, thus reducing the system loading during manufacturing process planning. The product-oriented standard, standard exchange of product (STEP), model data is applied to define a robust data model that associates product, shape, and feature definitions and provides the mechanisms for data exchange, sharing, and integration with other engineering systems, such as computer-aided design (CAD) and computer-aided manufacturing (CAM). STEP AP224 is engaged to define the machining features of machined products in the proposed CAPP system. The life cycle of a product from design to sale, and especially the period of manufacturing, can be greatly shortened; the cost of manufacturing can be reduced and the quality of the product can be improved using the proposed CAPP system.     

Concurrent process/inspection planning for a customized manufacturing system based on genetic algorithm

Producing products with multiple quality characteristics is always one of the concerns for an advanced manufacturing system. To assure product quality, finite manufacturing resources (i.e., process workstations and inspection stations) could be available and employed. The manufacturing resource allocation problem then occurs, therefore, process planning and inspection planning should be performed. Both of these are traditionally regarded as individual tasks and conducted separately. Actually, these two tasks are related. Greater performance of an advanced manufacturing system can be achieved if process planning and inspection planning can be performed concurrently to manage the limited manufacturing resources. Since the product variety in batch production or job-shop production will be increased for satisfying the changing requirements of various customers, the specified tolerance of each quality characteristic will vary from time to time. Except for finite manufacturing resource constraints, the manufacturing capability, inspection capability, and tolerance specified by customer requirement are also considered for a customized manufacturing system in this research. Then, the unit cost model is constructed to represent the overall performance of an advanced manufacturing system by considering both internal and external costs. Process planning and inspection planning can then be concurrently solved by practically reflecting the customer requirements. Since determining the optimal manufacturing resource allocation plan seems to be impractical as the problem size becomes quite large, in this research, genetic algorithm is successfully applied with the realistic unit cost embedded. The performance of genetic algorithm is measured in comparison with the enumeration method that generates the optimal solution. The result shows that a near-optimal manufacturing resource allocation plan can be determined efficiently for meeting the changing requirement of customers as the problem size becomes quite large.     

Implementing lean manufacturing with cellular layout: a case study

Lean manufacturing is an applied methodology of scientific, objective techniques that cause work tasks in a process to be performed with a minimum of non-value adding activities resulting in greatly reduced wait time, queue time, move time, administrative time, and other delays. In a cellular manufacturing system (CMS), machines are grouped into several cells, where each cell is dedicated to a particular part family and the objective is to maximize cell independence. CMS helps in reducing the material handling, work-in-process, setup time, and manufacturing lead time and improve productivity, operation control, etc. The facility layout used during lean implementation can be either be a line layout or in the form of cells. After grouping parts in to various part families, machine cells can be formed to produce those parts well inside the cells. As some of the lean manufacturing concepts are different from that of cellular manufacturing, e.g., establishment of Takt time, Takt-based resource balancing, etc., some new cell design methodology is required to be explored that is compatible with lean manufacturing. The rate at which work progresses through the factory is called flow rate or Takt. In the present work, a design methodology for cellular layout is proposed for implementing lean concepts and is exemplified in a manufacturing industry dealing with ammunition components for defense applications. Based on Takt time for various parts, the production flow among cells was optimized thus minimizing several non-value added activities/times such as bottlenecking time, waiting time, material handling time, etc. This case study can be useful in developing a more generic approach to design cellular layouts in lean environment.     

Reconfigurability consideration design of components and manufacturing systems

A manufacturing system should be able to produce a variety of components at a low cost and in a short period of time. In this paper, manufacturing system reconfigurability in agile manufacturing is discussed. The reconfiguration of a manufacturing system is analysed based on the relationship of component routes, material handling costs, reconfiguration cost, and so on. Components with similar routes are selected in an early design stage in order to minimise the number of machines to be relocated. The variety of resources required is reduced by a proper selection of components and manufacturing processes for system reconfiguration. An algorithm for selection of components and manufacturing resources is developed.     

Complexity of cellular manufacturing systems based on entropy models

Even structurally simple manufacturing systems can be operationally complex. This operational complexity can be colloquially defined as the uncertainty associated with managing the dynamic variations, in time or quantity, across information and material flows at the manufacturing systems interface. This paper proposes a means of measuring the information demands placed on cellular manufacturing systems, as a result of this uncertainty. A utility function for complexity is proposed according to the relationships between the complexity and utility in a manufacturing system and the underlying trend that the system becomes more and more complex in an everchanging environment is analyzed. This paper mathematically models the static entropy and the dynamic entropy of cellular manufacturing systems from an information-theoretic perspective. A unique feature of this measure is that it captures, in relative terms, the expected amount of information required to describe the state of the system. The measure provides flexibility in the scope and detail of analysis. Finally, an example is used to demonstrate the validity of the proposed methodology.     

Application of ORFPM system for lean implementation: an industrial case study

This paper presents an on-line radio frequency identification (RFID)-based facility performance monitoring (ORFPM) system. This system supports the implementation of Lean production in a small manufacturing facility. This system uses wireless monitoring via RFID to automatically generate a real-time value stream map (VSM) using computer-aided programming. Creating the VSM automatically saves time, reduces errors, and makes the VSM more visible to supervisors at any time. This up-to-date information allows supervisors to make more accurate, real-time shop floor decisions. The results of this study indicate that the ORFPM system can successfully track performance variations when production has low time consumption requirements and is labor intensive. Several Lean improvement suggestions are also proposed based on the collected data from the ORFPM system.     

虚拟产品制造规划中仿真优化技术的研究与应用

论述了制造系统的仿真与优化技术在规划中所起的巨大作用,提出了将工艺计划和生产计划的集成规划置于制造系统仿真的多级优化环境框架,并对仿真优化的目标进行层次分类,最后通过生产线系统设计实例,验证了本文的部分核心思想,为工程师进行产品制造规划提供了有力的前瞻性预测工具。     

Virtual plastic injection molding based on virtual reality technique

Virtual reality (VR), as a new technology, is integrated with software systems for engineering, design, and manufacturing. The integration has given a new impetus to the field of computer-aided engineering. This paper presents a research effort aimed at creating a virtual plastic injection molding (VPIM) environment, which is designed and implemented based on techniques such as VR, multidiscipline simulation, and scientific visualization. The VPIM system includes two parts: designing in VPIM and evaluation in VPIM. It is the first system to scrutinize virtual prototype mock-ups of new products, machines and production processes in interactive graphic simulation. During the evaluating phase, coupled to appropriate computer-based reasoning and decision-support tools and driven by data from the real manufacturing environment, a realistic impression of the process of plastic injection molding and manufacture can be achieved and can be changed interactively, and it is possible to thoroughly examine the planned system and eventually detect and remove any defects and inadequacies. The construction approach and key techniques (FEA, virtual assembly, stereoscopic display, a triangulated boundary-representation of an approximating polyhedron, collision detection, etc.) of the system are described in detail. The overall system is a powerful new approach for highly relevant industrial application of VPIM which focuses on the construction and assessment of alternate manufacturing sequences and mold design in an early design stage. Improvement of the design and manufacturing process will lead to better design and reduced development time and cost.     

Study of laminated object manufacturing with separately applied heating and pressing

To improve the hot-pressing process currently employed in laminated object manufacturing (LOM), an innovative heating-and-pressing separation system is proposed, and heat transfer problems of this system are investigated. A thermal model is first established. It is solved numerically by the finite element method (FEM) software ANSYS, and verified by experiments. Based on the numerical solution under various operating conditions, it is found that the operating temperature of an adhesive can be reached quickly when the heater is maintained at a higher temperature, corresponding to a deeper heat-affected zone. This shortcoming can be effectively reduced if the speed of the heater is increased. Hence, a higher heater temperature together with a higher moving speed is suggested to shorten processing time and promote manufacturing efficiency. Through analysis, the appropriate distance between the roller and the heater, so as to obtain finished parts of high quality, is determined.     

高职院校教育成本结构的回归分析及启示

通过院校类型、富裕程度和规模等因素对高职院校人力成本结构、业务成本结构、设备成本结构、修缮成本结构影响的回归分析发现,院校类型与人力成本结构和设备成本结构正相关,与修缮成本零相关;院校富裕程度与人力成本负相关,与业务成本和修缮成本正相关;院校规模与所有成本结构零相关。国家需根据院校类型加大经费投入,才能有效提升高职院校的人才培养质量,实现高职院校良性发展。     

A web-based advisory system for process and material selection in concurrent product design for a manufacturing environment

This paper reports the work of selecting suitable manufacturing processes and materials in concurrent design for manufacturing environment. In the paper, a fuzzy knowledge-based decision support method is proposed for multi-criteria decision-making in evaluating and selecting possible manufacturing process/material combinations in terms of the total production cost. Based on the proposed method, a prototype Web-based knowledge-intensive manufacturing consulting service system (WebMCSS) with the client-knowledge server architecture is developed to help designers/users find good processes and materials while still at the conceptual level of design. The system, as one of the important parts of an advanced design for manufacturing tool, is a concept level process and material selection tool that can be used as both a standalone application and a Java applet freely available via the Web. Interlinked with Web pages of tutorials, and reference pages explaining the facets, fabrication processes and material choices, the system performs reasoning and calculations using the process capability and material property data from the remote Web-based database and knowledge base that can be maintained and updated via the Internet. The use of the system is illustrated with an example.     

高性能表面层制造:基于可控表面完整性的精密制造

高性能表面层制造是具有特殊功能性表面层结构零件的精密制造,体现了高性能零件性能与几何参数一体化制造的特点。依据功能性表面层结构零件的性能要求所设计的几何参数和材料特性,选择表面层加工制造方法,确定加工工艺载荷的物质与能量输入条件,通过减控加工工艺的几何、结构、物理、化学等多源耦合约束,构建主动协调的材料加工载荷的应力场、温度场和化学位场等(多)场环境,相应地揭示零件表面完整性变化关系内禀的加工过程印记,利用可控的表面完整性与高性能零件性能的关联模型,实现具有特殊功能性表面层的精密制造。高性能表面层加工制造原理的核心是表面完整性的形成机制、评价方法和调控作用,所提出的高性能表面层精密制造的体系框架,以基于知识方法取代实验迭代的试错法,可解决高性能制造的加工制造反问题。     

应用STEP-NC实现产品设计制造信息的共享

开放式数控系统是为适应现代制造业发展的潮流而提出的,但是对传统的数控代码所代表的数控系统的改造,并不能适应网络化制造和数字化制造的需要,也不利于系统的开发。STEP-NC标准作为新一代数控标准,继承了STEP标准中的产品信息,同时具有开放性,可以作为CAD/CAM/CNC集成的桥梁。利用STEP-NC面向特征和面向对象的特点,建立各制造特征的加工工步,就可以开发相应的数控系统,实现面向制造特征的数控加工,从而达到CAD/CAM/CNC信息集成的目的。     

A web-enabled open database system for design and manufacturing of micro-electro-mechanical systems (MEMS)

This paper presents the development of a web-enabled database system for MEMS design and manufacturing which can provide the networked design and manufacturing services over the Internet. Specifically, the data obtained from various sources for MEMS manufacturing processes/materials are organised as databases by using the relational database management systems (RDBMS), Microsoft Access and MySQL. The database system can be accessed from a Java application as well as an applet. The stand-alone Java application is created using JFC Swing, JDBC and SQL, and the Java applet is subsequently created to enable web functionality. The underlying database is open, extensible through a set of administrator tools or via the web, which gives commercial design and manufacturing facilities the ability to update their own materials, processes and rules. This plays a crucial role in the system for advisory MEMS manufacturing service and concurrent collaborative MEMS design and simulation. The developed database system, e-MEMS Designer @Database, which contains extensive manufacturing or fabrication processes and materials databases for MEMS and microelectronics, is easily incorporated as a sub-system into both the standalone system and the web-enabled MEMS design system, MEMS Designer, which is being developed. The database system can also be updated to create a comprehensive data warehouse and an advisory system for MEMS manufacturing processes/materials selection.     

Development of a new concrete pipe molding machine using topology optimization

Sulfur polymer concrete (SPC) is a relatively new material used to replace Portland cement for manufacturing sewer pipes. The objective of this work is to develop an efficient molding machine with an inner rotating die to mix, compress and shape the SPC pipe. First, the alternative concepts were generated based on the TRIZ principles to overcome the drawbacks of existing machines. Then, the concept scoring technique was used to identify the best design in terms of machine structure and product quality. Finally, topology optimization was applied with the support of the density method to reduce mass and to displace the inner die. Results showed that the die volume can be reduced by approximately 9% and the displacement can be decreased by approximately 3% when compared with the initial design. This work is expected to improve the manufacturing efficiency of the concrete pipe molding machine.

     

Development of a new lapping method for high precision ball screw (1 report)-feasibility study of a prototyped lapping tool for automatic lapping process

Ball screws are being lapped as a finishing process to improve the travel variation, drunkenness and surface finish in order to provide high precision requirements in various mechanical applications. However, the existing manufacturing method is very labor intensive that needs a highly skilled machinist to perform the hand lapping operations using the conventional laps which have two or three slits. These types of lap cannot eliminate and improve the special components of drunkenness such as ellipsoidal, triangular and other polygonal cross sections. This paper presents a new lapping method to determine the technical and operational feasibility of a prototyped lapping tool with the combination of a flexible lap and polyurethane elastomer which can be mounted in the vertical-type automatic lapping machine. This new type lapping tool with six slits, is especially designed which each section can move in radial direction wherein the uniform lapping pressure is applied on the test piece from six directions. Based on experimental results, it showed that the travel variation was greatly reduced along with drunkenness and lapping time.