Cell formation with reduction in setup times

Cell manufacturing (CM) is a well-known strategy for reducing lead times in batch production systems. In essence, the basic information required to solve a CM problem is the machine-part incidence matrix. Most of the methods of cell formation are based on machine-part incidence matrix alone. However, other factors such as production sequence and production volumes, if incorporated, can enhance the quality of the solutions. Recently, Nair and Narendran (1998) [Int. J. Prod. Res. 36 (1) (1998) 157] presented the algorithm which clusters machines and parts on the basis of sequence data. It is, however, required to consider the setup in the case of cell formation with sequence data. This paper proposes a new cell formation with reduction in setup times between machines in the same cell. Through the computational experiment, performance of the proposed method is also investigated.     

Applications of group technology in distributed manufacturing

This paper discusses the systematic use of group technology (GT) to support important activities of distributed manufacturing including design indexing and retrieval, variant design, variant process planning, and design critiquing. We introduce an Object-Oriented Group Technology (OOGT) scheme, which captures design data critical to the product's manufacture. Our approach uses a STEP-based product information model to generate the OOGT data automatically. The latter are then used to conduct an efficient search for similar products manufactured by selected companies and to retrieve and use information about the manufacturing processes and performance of these similar products.     

虚拟制造技术在VE型分配泵研发中的实现

该文基于虚拟制造技术,从面向产品伞生命周期的角度,以汽车发动机VE型分配泵为研究对象,研究了以设计为中心的虚拟制造技术在汽车零部件设计中的实现。研究内容主要包括虚拟设计、虚拟样机、虚拟装配、有限无分析、虚拟加工仿真等,并对研究结果进行了实验验证。该文利用该研究力’法重点分析了VE型分配泵传动部件易断裂问题,并结合企业实际给出了解决方案。企业的成功实践表明．将虚拟制造技术应用于产品的开发与改进,是一种切实可行的设计理念和方法。     

A self-organizing neural network approach for the design of cellular manufacturing systems

The crux problem of group technology (GT) is the identification of part families requiring similar manufacturing processes and the rearrangement of machines to minimize the number of parts that visit more than one machine cell. This paper presents an improved method for part family formation, machine cell identification, bottleneck machine detection and the natural cluster generation using a self-organizing neural network. In addition, the generalization ability of the neural network makes it possible to assign the new parts to the existing machine cells without repeating the entire computational process. A computer program is developed to illustrate the effectiveness of this heuristic method by comparing it with the optimal technique for large-scale problems.     

A clustering approach for minimizing intercell trips in cell formation

Excessive intercell trips in a cellular manufacturing system may minimize the benefits that the system can provide. Hence, this research develops a non-linear integer formula to reduce intercell trips in a cell type system design. A clustering algorithm is then developed to obtain a satisfactory solution to the proposed cell formulation problem. To determine the performance of the proposed clustering algorithm, comparisons are made with an Exhaustive Search (ES) algorithm to show the relative optimality.     

虚拟现实与卫星仿真技术

该文通过对虚拟现实技术理论和应用状况的分析,结合卫星技术的特殊性,提出如何将虚拟现实技术与卫星仿真技术相结合,在虚拟环境下对卫星的设计、制造、发射,直至在预定轨道上的运行等全过程进行可视化仿真的方法。     

虚拟样机技术在家电产品开发中的应用

该文简要介绍了虚拟样机技术的概念以及目前的发展应用状况。指出虚拟样机技术在家电产品开发过程中应用的可行性。对虚拟样机技术在家电产品开发中的应用思路进行了分析,说明其应用主要是指综合利用三维造型设计(CAD)技术、加工仿真(CAM)技术、虚拟装配技术、机构运动学动力学仿真技术、虚拟试验研究、试验设计(DOE)及参数优化技术来加快设计和投产的速度,保证产品质量。并举例应用Pro/E、ADAMS软件对某家用吸尘器进行虚拟样机建模,对其过滤网的受力进行仿真分析找出失效原因,进而完成过滤器结构的优化设计。     

Clustering algorithm for solving group technology problem with multiple process routings

Cell formation is an important problem in the design of a cellular manufacturing system. Most of the cell formation methods in the literature assume that each part has a single process plan. However, there may be many alternative process plans for making a specific part, specially when the part is complex. Considering part multiple process routings in the formation of machine-part families in addition to other production data is more realistic and can produce more independent manufacturing cells with less intercellular moves between them. A new comprehensive similarity coefficient that incorporates multiple process routings in addition to operations sequence, production volumes, duplicate machines, and machines capacity is developed. Also, a clustering algorithm for machine cell formation is proposed. The algorithm uses the developed similarity coefficient to calculate the similarity between machine groups. The developed similarity coefficient showed more sensitivity to the intercellular moves and produced better machine grouping.     

Concurrent engineering utilities for controlling interactions in process planning

This paper presents two concurrent engineering tools for serving in process planning. The first one, as design for manufacturing utility, evaluates critical interactions between several types of machining features (i.e., holes, pockets, etc.) on prismatic parts, and modifies original design (if possible) and reflects the modifications to all down- and up-stream stations in CAD/CAM integration. The second one is for group technology and flexibility, by which products are designed according to the existing manufacturing system. Methodologies of the developed systems are illustrated with several examples throughout the paper.     

A -based layout design for gratings allocation

In the design process of gratings, the grating layout design is the most important activity influencing manufacturing cost. In the grating layout design, the key to saving manufacturing cost is to find a design with a minimal number of cutting operations. This paper presents an application of the A^* algorithm in grating layout design. The design problem is represented as the space search problem of design alternatives. A^* explores the feasible alternatives within the space, until an optimal solution is obtained.     

A methodology to incorporate product mix variations in cellular manufacturing

The identification of part families and machine groups that form the cells is a major step in the development of a cellular manufacturing system and, consequently, a large number of concepts, theories and algorithms have been proposed. One common assumption for most of these cell formation algorithms is that the product mix remains stable over a period of time. In today’s world, the market demand is being shaped by consumers resulting in a highly volatile market. This has given rise to a new class of products characterized by low volume and high variety. To incorporate product mix changes into an existing cellular manufacturing system many important issues have to be tackled. In this paper, a methodology to incorporate new parts and machines into an existing cellular manufacturing system has been presented. The objective is to fit the new parts and machines into an existing cellular manufacturing system thereby increasing machine utilization and reducing investment in new equipment.     

Capability-based virtual cellular manufacturing systems formation in dual-resource constrained settings using Tabu Search

Formation of Virtual Cellular Manufacturing Systems (VCMSs), as one of the main applications of Group Technology (GT), by presentation of unique and shared capability boundaries of machine tools through defining Resource Elements (REs) creates a good solution for Capability-Based VCMSs (CBVCMSs), which increases opportunities to create systems with more efficient utilizations. Considering workers as the second important resources in Dual-Resource Constraint (DRC) settings makes this problem more serious and critical to research because, in reality, jobs cannot be processed if workers, machines, or both are not available. This paper attempts to form CBVCMSs with DRC settings using a multi-objective mathematical model with a Goal Programming (GP) approach. Using the developed model, parts, machines, and workers are grouped and assigned to the generated virtual cells at the same time. The proposed model is solved through a multi-objective Tabu Search (TS) algorithm to find optimum or near-to-optimum solutions. The validity of the developed model is illustrated by two numerical examples taken from the literature and evaluated through comparing the performance of the CBVCMSs and the original classical CMSs in the System Capacity Utilization (SCU) point of view.     

基于动态联盟和分布式虚拟制造的产品设计方法

本文在分析动态联盟和分布式虚拟制造的基础上,进行产品设计方法的研究与实现。用HTMLVRMLJAVA技术实现产品设计过程,重点介绍了产品设计的主要功能模块。详细介绍了产品设计中的建模和并行设计两项关键技术。     

A versatile virtual prototyping system for rapid product development

This paper presents a versatile virtual prototyping (VP) system for digital fabrication of multi-material prototypes to facilitate rapid product development. The VP system comprises a suite of software packages for multi-material layered manufacturing (MMLM) processes, including multi-toolpath planning, build-time estimation and accuracy analysis, integrated with semi-immersive desktop-based and full-immersive CAVE-based virtual reality (VR) technology. Such versatility makes the VP system adaptable to suit specific cost and functionality requirements of various applications.

The desktop-based VR system creates a semi-immersive environment for stereoscopic visualisation and quality analysis of a product design. It is relatively cost-effective and easy to operate, but its users may be distracted by environmental disturbances that could possibly diminish their efficiency of product design evaluation and improvement. To alleviate disturbance problems, the CAVE-based VR system provides an enclosed room-like environment that blocks out most disturbances, making it possible for a design team to fully concentrate and collaborate on their product design work.

The VP system enhances collaboration and communication of a design team working on product development. It provides simulation techniques to analyse and improve the design of a product and its fabrication processes. Through simulations, assessment and modification of a product design can be iterated without much worry about the manufacturing and material costs of prototypes. Hence, key factors such as product shape, manufacturability, and durability that affect the profitability of manufactured products are optimised quickly. Moreover, the resulting product design can be sent via the Internet to customers for comments or marketing purposes. The VP system therefore facilitates advanced product design and helps reduce development time and cost considerably.     

虚拟家居漫游系统的设计与实现

虚拟现实技术的沉浸感交互性和构想性决定了其在家居设计领域的应用前景广阔。本文提出了一个基于3dmax和虚拟现实建模语言（VKML）的虚拟家居漫游系统。对于系统的整体架构及实现方法进行了阐述。     

Virtual factory approach for implementation of holonic control in industrial applications: A case study in die-casting industry

Design and implementation of holonic manufacturing control systems for the real industrial applications require risky, careful decisions to ensure that the manufacturing system will successfully satisfy the demands of an ever-changing market. This paper suggests a virtual reality (VR)-based methodology for enhancing the design and implementation process of holonic control systems in manufacturing practice. The major focus has been given to the implementation of holonic control into the small to medium size manufacturing enterprises (SMEs).     

虚拟制造技术在吸尘器制造中的应用

该文简要介绍了面向机械设计制造过程的虚拟制造技术的特点和应用方法,分析了应用中的主要技术环节和技术方法,并阐述了如何应用虚拟制造技术提高生产企、世的经济效益。如何在虚拟原型产品的设计中,应用三维设计造型工具进行产品的外形和结构的布局设计。应用ADAMS系统的动力学仿真结果对产品结构进行了改进设计,解决了尾杆滚轮的运动不平衡问题。应用HSCAE Smart5．O系统对塑料外壳进行了注塑成形过程模拟分析,优化了注射成形工艺,避免了成形缺陷,提高了产品的性能,缩短了设计制造周期。     

Threshold value for the number of cells in group technology

The similarity coefficient methods are more flexible in incorporating manufacturing data into the machine cells formation process in group technology. When threshold value is applied it is impossible to consider the restriction of number of cells or pact family. This paper discusses how a function is defined on Similarity coefficients and generates a threshold value which specifies an upper band on number of cells.     

A simulation model for the fabrication of components made from multiphase perfect materials

A component, which has an optimized combination of different materials (including homogeneous materials and different types of heterogeneous materials) in its different portions for a specific application, is considered as the component made of a multiphase perfect material. To manufacture such components, a hybrid layered manufacturing technology was proposed. Since it would be risky and very expensive to make such a physical machine without further study and optimization, manufacturing simulation is adopted to do further research so as to provide the reliable foundation for future practical manufacturing. This paper describes its virtual manufacturing technologies and modeling of the component virtually manufactured. Such a model can be used to evaluate the errors of the virtual manufacturing. Finally, an example of simulating manufacturing process and generating the model of the component virtually manufactured is introduced in more detail.