探索准时制生产的成功之路

即便完全采用面向订单生产（ＭＴＯ）策略的企业也能从其资源的周密计划中获益。我们在此勾勒的是追寻有效的准时制生产目标的企业如何拾级而上。 有一部分经理的观念中存在这样的错误想法：如果一个公司实行准时制生产或看板实施系统,那么它就不再需要企业资源计划或物料需求计划（ＥＲＰ／ＭＲＰ）。事实正相反,正如一位供应管理专家所观察到的那样：“看板制在工厂中失败的主要原因是没有对需求变动作出相应的计划,这样看板的大小经常是错误的。” 为了直观地描述计划较差的准时制过程,我们来考虑杂货铺的面包架。只有面包供应商有效…     

Pro/Engineer中装配仿真的实现方法

装配仿真能实时检测和改进产品的可装配性.提出一种可以实现零件在装配路径上进行连续运动的装配仿真方法.在装配体的基准零件中利用草绘工具规划出装配路径,在将要装配到基准零件上的零件中定义装配基准点.利用Mechanism模块的槽从动机构将装配路径定义为槽曲线,将装配基准点定义为从动机构点.根据槽曲线的空间形态定义伺服电动机即可驱动零件实现装配过程仿真.利用"回放"命令还可以重新演示装配过程以及进行实时干涉检测.     

Solid Works2001plus在工程图制作中的使用

一、 零件、装配件及工程图模板的定制在企业中成功使用SolidWorks制作工程图的关键工作之一是如何准确地定制符合本企业的设计工作模板,并将设计模板存放在SolidWorks 2001 plus→data→Templates目录中,将明细表模板(Excel)存放在SolidWorks 2001 plus→lang→Chinese-simplified目录中。在定制零件和装配件模板时需注意企业在设计生产过程中所需的信息必须定制在“属性”的“指定配置”中,这样才能使零件、装配件以及多配置文件的属性信息统一;如果定义制在“自定义”中,将不能与多配置文件进行统一,否则可能造成在工程图中因零件信…     

VDVAS：一个集成的虚拟设计与虚拟装配系统

随着虚拟现实技术的逐渐成熟，研究者们已将其引入到工程领域，为实现虚拟设计与虚拟装配过程的集成，避免现有的虚拟装配系统中，虚拟环境与CAD系统间所必需进行的复杂的、无谓的数据传输，描述了一个基于多通道的、集成的虚拟设计与虚拟装配系统VDVAS。在该系统中，设计得可以通过直接三维操作和语音命令直观方便地建立机械零件及其装配模型，并通过交互拆装来得到零件的装配顺序和装配路径等信息，VDVAS的一个重要特征在于，可通过集成虚拟设计与虚拟装配过程，使设计者能在一个集成的虚拟环境中修改零件几何（假如在装配过程中发现零件存在设计缺陷的话）。     

SolidWorks 2001 plus在工程图制作中的使用技巧

一、零件、装配件及工程图模板的定制 在企业中成功使用SolidWorks制作工程图的关键工作之一是如何准确地定制符合本企业的设计工作模板,并将设计模板存放在SolidWorks 2001 plus→data→Templates目录中,将明细表模板(Excel)存放在SolidWorks 2001 plus→lang→Chinese-simplified目录中.在定制零件和装配件模板时需注意企业在设计生产过程中所需的信息必须定制在"属性"的"指定配置"中,这样才能使零件、装配件以及多配置文件的属性信息统一;如果定义制在"自定义"中,将不能与多配置文件进行统一,否则可能造成在工程图中因零件信息的不统一(可能发生冲突)而无法取到信息.     

基于Java 3D的交互式三维动画的研究

为了建立基于工程图学的虚拟实验室,在计算机的屏幕上虚拟现实中零件的装配,笔者通过对两种虚拟语言VRML与Java 3D的分析比较,选定以Java 3D为虚拟平台,在引入.obj文件的基础上,按照现实中零件的安装和工作过程,通过设定相应的程序来实现零件的交互和装配过程,并完成了对零件交互式三维装配动画以及工作原理的论述。以压板为例,给出了一个基于Java 3D的交互式三维装配动画的例子,实现了该装配体在虚拟现实中的要求,达到了虚拟装配的目的。从而验证了该方法在现实零件装配中的预见性和优越性。     

虚拟环境中产品装配过程回溯方法研究

在记录虚拟装配过程的基础上，提出基于任务时间的虚拟装配过程整体回溯与基于任务对象的虚拟装配过程局部回溯方法．虚拟装配过程整体回溯以装配任务时间为回溯准则，允许将装配场景中零部件的方位与装配关系回溯到曾经存在的装配历史状态，而虚拟装配过程局部回溯，是根据装配序列中零件间装配约束与几何干涉方面存在的相关性进行装配过程的选择性回溯．文中方法在虚拟设计与装配原型系统开发中得到实现．实践表明，装配过程回溯方法有效地提高了虚拟环境中产品装配设计的效率。     

基于装配自由度分析解决欠约束问题

装配是机械制造过程中的一个重要环节,在装配过程中,经常会遇到欠 约束问题。在复杂装配环境下,某个装配零件的欠约束会对其他零件的装配产生意想不到的 结果。装配时,约束条件和零件自由度之间存在一种内在联系,通过建立基体和目标零件的 自由度空间坐标系,对约束条件和自由度关系分析,得到约束条件和自由度关系的逻辑值, 通过逻辑值判断剩余自由度的个数和类型,从而为快速解决欠约束问题提供了一种途径。     

汽配企业先上ERP还是先上PDM

顺腾（企业化名）是一家高速发展中的民营汽车零部件企业，生产汽车底盘、车身类零部件，主要为上海大众、一汽大众、上海通用、北美通用等国内外知名汽车主机厂做配套。主机厂在汽车产业链上非常强势，对上游供应商的产品质量、价格、服务、交货能力，交货准时性等方面都有严格要求。近年来，顺腾业务突飞猛进，管理却基本停留在手工操作阶段，信息化程度较低，     

基于装配约束动态管理的虚拟拆卸

装配约束是虚拟拆卸环境下必须考虑的装配体的重要信息，提出虚拟拆卸过程中装配约束的动态管理机制，并实现了基于装配约束导航的虚拟拆卸。装配约束的动态管理包括虚拟环境下装配约束的获取、表达以及拆卸过程中装配约束的动态维护，即装配约束的动态解除和产生，文中用装配约束图表达零件间的装配约束，提出装配约束的间接解除方法，并实现了基于装配约束推理的零件可拆卸方向的推导。最后，通过一个简单装配体的拆卸实例，对文中方法进行了验证。     

CIMS企业中应用Push/Pull生产方式的研究

文章首先对MRP＿II和JIT生产方式进行了对比,分析各自的优缺点,并针对性地提出一种适合于CIMS类企业Push／Pull生产方式.然后,作者详细研究了Push／Pull生产方式下原材料投入的Push控制方法和后续加工的Pull控制方法.最后,作者研究了Push／Pull生产方式下生产计划和调度策略的基本框架、系统的总体结构和JIT的主生产计划方法等.     

A systematic modelling and simulation approach for JIT performance optimisation

Robust computer aided simulation and modelling tools help to visualise, analyse and optimise complex production processes with a reasonable amount of time and investment. A review of the literature shows that simulation and modelling have not been extensively applied in just-in-time (JIT) manufacturing environments. Also there remains a lack of a comprehensive mechanism to identify the most significant JIT drivers for the purpose of system process optimisation. The prime objective of this study is to close this gap by applying computer based simulation tools and linear mathematical modelling to identify the impact of selected key JIT parameters on performance in an automotive component-manufacturing environment. Research shows that variables such as inconsistent task distribution, variation on operator performance, misconception of total quality management philosophy and lack of set-up time elimination plans disrupt ideal JIT production. In this study, ProModel simulation and modelling software is used to model and simulate different experimental scenarios in order to understand and quantify the impact of selected input key JIT variables on objective functions (i.e. process time and takt time). The outcome is a robust mathematical model that highlights the significance of JIT drivers in the manually operated mixed-model assembly lines.     

A study on sequencing method for the mixed-model assembly line in just-in-time production systems

This paper deals with the problem of sequencing products on the mixed-model assembly line in a multi-level JIT production system. We consider both Goal(1) which levels the load at each station on the mixed-model assembly line, and Goal(2) which keeps a constant rate of production of every part in the preceding processes which are used on the mixed-model assembly line, together. We propose a mathematical model which determines the number of every product to be scheduled in each withdrawal position to realize making each withdrawal quantity of all the parts, with a fixed interval, as constant as possible. A sequencing method based on the solution stated above is given. Finally, an example is shown.     

Just‐in‐time parts feeding policies for paced assembly lines: possible solutions for highly constrained layouts

This paper deals with the dimensioning of a just‐in‐time (JIT) parts feeding system, for a paced assembly line. Specifically, we consider the quite frequent case of an old‐fashioned, push‐oriented warehouse arrangement, characterized by materials and subassemblies that are stocked in different and peripheral areas of the manufacturing plant. In these circumstance, layout changes are almost impossible and warehouses cannot be substituted by supermarkets. Nevertheless, this does not preclude the possibility to rationalize material flow and to reduce work in process (WIP) using a JIT parts feeding system. To this aim, we propose two alternative approaches, differentiating in terms of the order with which warehouses and workstations are visited. In order to dimension both systems and to estimate their expected performances, a mathematical model is also presented. At first, the model is presented in a basic formulation, which is very effective and easy to use. A more sophisticated formulation, based on Bayesian probability, is introduced next; this is not so much for practical purposes, but rather to demonstrate the potential of the proposed JIT system in very constrained operating settings.     

基于设计环境的图纸BOM 管理系统

随着无纸化生产模式的普及,大量工程图和BOM 数据的管理成了一个重 要的研究领域。论文介绍一种基于设计环境的图纸BOM 管理系统,该系统以整个产品或者 是整个部件的图纸为划分,基于数据库技术,直接集成于CAD 环境中,免去了PDM、PLM 等管理软件繁琐的流程管理,更接近设计人员的使用习惯,系统以工程图纸为数据基础,可 以生成多种格式的BOM 报表,通过在企业的实际应用中证明了该系统的可靠和高效。     

A sequencing problem for a mixed-model assembly line in a JIT production system

In an assembly line of a just-in-time (JIT) production system, workers have the power and the responsibility to stop the line when they fail to complete their operations within their work zones. This paper deals with a sequencing problem for the mixed-model assembly conveyor line in the JIT production system. In some environment, the most important criterion is the line stoppage rather than the variation of production rates. The problem is to find an optimal sequence of units that minimizes the total line stoppage time. Lower and upper bounds of the total line stoppage time are derived and the branch-and-bound method is applied to the problem. A numerical example is given.     

基于地铁车辆新造过程的工时管理系统 实施与应用

工时管理是生产管理的基础性工作,对企业生产任务的编排与调整影响重大。地铁车辆是典型的离散定制产 品,且零部件众多,结构复杂,组装工序繁琐,对其生产过程实施工时管理有利于确保企业按期交货,提升产品质量。本文以杭 州中车车辆有限公司工时管理系统的实施与应用为切入点,并结合工位制节拍生产方式来研究工时管理在地铁车辆新造过程 中的改善效果。通过数据监测发现,工时管理系统实施上线后,单辆地铁车辆的生产工位工时减少了1958.5 小时,生产效率提 高了20.70%,每年可给企业带来500 余万元的直接经济效益。     

Development of an agent-based system for manufacturing control and coordination with ontology and RFID technology

Integrating physical objects with the corresponding enterprise applications any time any where is the essential issue for a real-time enterprise. This study proposes a multi-agent system framework called agent-based manufacturing control and coordination (AMCC) system, a agent-based framework using ontology and RFID technology to monitor and control dynamic production flows and also to improve the traceability and visibility of mass customization manufacturing processes. The capabilities offered by multi-agent systems to respond to RFID events in real-time and a broad class of agent design and coordination issue regarding just in time (JIT) and just in sequence (JIS) manufacturing processes are also exploited in this study. To validate the proposed framework, case study of a bicycle manufacturing company is used to demonstrate how the proposed framework can benefit its JIT production. Finally, an example prototype system is implemented to demonstrate the concept of the proposed framework.     

装备制造企业生产物流仿真系统

分析了装备制造企业生产物流的特点,属于典型的离散型复杂装备制造企业,生产过程复杂、物流供应链复杂,产品批量小,以定制生产为主。提出了基于离散事件建模的生产物流过程模型,研究了影响企业生产物流的约束条件及其相互关系;设计了装备制造企业生产物流仿真系统,实现了生产全过程的物流仿真。基于生产物流仿真系统,以某大型企业为研究应用背景,量化分析了生产过程物流的关键因素,并给出了相应建议。     

An algorithm for the automatic generation of an assembly process for modular fixture parts

In metal mold production systems, rapid, high-quality, and low-cost production technologies are needed. In these systems, assembly tasks to make fixtures to immobilize the mold are required. The mold must be firmly fixed in order to resist the force generated by NC machine tools. In this article, we discuss the automatic generation of an assembly process for modular fixture parts in the systems. The assembly drawing of the parts can be obtained from STEP/AP203, which is a text file of CAD/CAF data. In these data, the shape and configuration of all assembled fixtures are included. The shape of each fixture is constructed with planar, cylindrical, and conical surfaces. From the data, the number of surfaces in contact with other surfaces is derived for each part, and valid contacts are judged for their degree of importance. A tree of contacts among all fixtures is derived. In the numerical examples, the assembly process is automatically generated by our proposed method. It is shown that a suitable assembly process is obtained.