Manufacturing signature and operating conditions in a variational model for tolerance analysis of rigid assemblies

The need of a univocal language for geometrical product specification considering all steps of the product life cycle such as design, manufacturing, and inspection is inevitable. Most models for Computer-Aided Tolerancing proposed by researchers and used in industry do not fully conform with standards. Moreover, most of them make severe assumptions on observable geometric deviations and can therefore hardly handle all kinds of 3D tolerances. These lacks inspired the idea and the development of a discrete geometry framework that is capable of considering geometric deviations of different stages of the product life cycle and is versatile regarding current and future tolerancing standards. This work uses a point cloud-based geometry representation scheme to implement the pattern left on the surfaces by a manufacturing process; then, this scheme has been inserted in a variational approach for tolerance analysis. Moreover, gravity and friction among the parts to assemble have been simulated too. In this way, a new Computer Aided Tolerancing (CAT) simulation tool has been developed; it approaches reality more than existing software packages do. To verify the effectiveness of the new CAT simulation tool, it has been applied to two case studies. The obtained results have been compared with those due to a geometrical model that has been developed by simulating what happens among the parts in the actual assembly. The obtained results show how the new CAT simulation tool gives results nearer to reality than literature models do.     

amePLM: a platform providing information provision in engineering

The procedure for the engineering of products and production systems in manufacturing companies is often distributed over several organisational units. The different units involved in these procedures use their respective methods and tools, resulting in silo-like and distributed information and data sources for engineering. In this paper, the open platform amePLM is introduced. This platform is based on a semantic data model. The ontology as explicitly formulated data model allows an integrated view on data and information available in the systems used along the product lifecycle, and the automatic provision of suitable information to the user. Furthermore, this open approach allows the linking of the solution to existing engineering software systems in the sense of a continuous flow of information.     

基于三维轻模型的装配MES系统关键技术

针对现阶段产品设计已经实现三维数字化,但在航空等典型离散行业的制造现场仍以二维工程图为产品制造依据的现实,提出了基于三维轻模型的装配MES系统,将产品设计数据向制造过程延伸,并结合MBD( ModelBased Definition,基于模型的定义)技术实现基于三维轻模型的装配工艺定义,以三维轻模型为车间现场装配生产的...     

Assembly sequence influence on geometric deviations propagation of compliant parts

This paper presents a non-rigid part variation simulation method for fulfilling functionnal requirements on compliant assemblies. This method is based on the propagation of different geometrical deviations (manufacturing and assembly process defects) using the method of influence coefficient. Tolerance analysis of compliant assemblies is also achieved very early in the design stage. As a consequence, designers and manufacturing engineers can efficiently analyse the assembly design principles both in terms of installed stresses and geometric variation clearance. They can also set optimised sequences that enable ridding of geometric variations.     

A systematic literature review to explore traceability and lifecycle relationship

Traceability is the ability to follow a product along its lifecycle. It ensures product safety and quality along the supply chain, managing information generated by several players. Even though regulations establish the information that has to be traced, each player generates much more product (and process) information, which could be used to add value to products, with respect to, not only traceability, but also the lifecycle approach. However, the concepts do not appear to be immediately related in scientific panorama. This paper aims to explore the relationship between traceability and lifecycle through a systematic literature review. Six industries (Software, Manufacturing, Automotive, Automation, Aircraft, and Aerospace) and seven subject areas (Software engineering; System engineering; Industry 4.0; New product development; Process management; Data Management; and Environmental sustainability) were identified through bibliometric analysis. To better explore this relationship in the context of the food industry, a content analysis on lead papers’ sample was performed to identify traceability and lifecycle definitions, methodologies and technologies and their relation. The results of the work, synthetised in a proposed research map, will be of interest to those who are approaching the subject for the first time, and for companies involved in product lifecycle management and food traceability.     

数字化检测在MES中的应用研究

讨论了机械制造企业中三维数字化检测的相关技术,进行了基于DMIS标准的数字化测量研究.通过三维检测技术与生产车间制造执行系统(MES)的结合,完成了基于三维轻量化模型的检验工艺管理、检验任务的执行与管理、产品质量数据和状态的可视化管理,以及产品的质量审理和追溯.这些研究实现了机械制造企业检验的自动化和无纸化,达到了对检...     

面向产品全生命周期的标准件库研究与实现

设计数据是制造企业产品生命周期管理中的源头数据,设计数据的标准化、规范化很大程度决定了整个PLM系统的应用效果。据此,研究了在设计过程中物料信息的产生及在PLM系统中的传递过程以及设计工具软件与PLM系统的单一数据源理论,提出了面向产品全生命周期管理的标准件库系统的构建与实现方法;以及实现设计工具软件与PLM系统协同应用的方法。基于该理论及方法在SOLIDWORKS的软件平台上开发实现了面向产品全生命周期的标准件库系统,所开发系统已在某制造企业的设计部门得到应用,效果明显。     

A STEP-compliant product data model for injection moulding products

In the current rapidly changing manufacturing environment, most manufacturing companies have realised that the ability to quickly develop a customised product at competitive prices is very crucial for them to survive in the keen competitive global market. Product modelling has been recognised as one of the key factors in determining the success of various product development strategies and for industrial competitiveness now and in the future. Standard for Exchange of Product model data (STEP) is an international standard designed to provide a complete, unambiguous, computer-readable definition of the physical and functional characteristic of a product through its lifecycle. This paper proposes a STEP-compliant product data model to fully support the complete product information representation and management for injection moulding product development. The data model is developed based on the structure of an injection moulding company. The entire data model consists of six data models which are defined to express information from various departments of the company. The data model is described in EXPRESS language, which can be integrated with other STEP-based product data models and databases. Consequently, the proposed system can be further extended for helping other injection moulding manufacturers to improve their product development process. An information sharing prototype system is implemented based on the proposed product data model to demonstrate the feasibility of the approach.     

基于数字化设计制造协同的飞机计量保障体系架构探讨

在国家科技创新,数字化设计制造高速发展的背景下,先进的数字化制造与传统的"先制造后检测再校准"的计量保障模式的矛盾愈发突出。以几何参数的数字化计量保障能力为例,通过分析对比国内外航空数字化设计制造工程中的几何参数计量保障工作现状,提出在飞机全生命周期内要保证产品数字化制造的几何尺寸精度,应依据新的产品几何规范,从产品的数字模型定义出发,面向数字化设计制造协同的关键过程和关键参数的测量溯源性要求,研究架构新的数字化计量保障技术体系,并就体系架构展开探讨。     

Smart,connected open architecture product: an IT-driven co-creation paradigm with lifecycle personalization concerns

Nowadays, the emphasis on manufacturing has shifted from a manufacturer-dominating to a customer-centric manner by actively involving users into the co-creation process to realise individual satisfaction. In such era, the rapid development of information and communication technology (e.g. wireless sensor network, and cyber-physical systems) enables a promising market of IT-driven product, i.e. smart, connected product, and also changes the way of user–manufacturer interaction in the product development process. However, to the best of authors’ knowledge, co-creation manner in such context is scarcely reported. Meanwhile, there is a lack of any paradigms given to enable such product open innovation along the lifecycle for personalisation concerns. Aiming to fill this gap, this paper, as an explorative research, proposes a new product development paradigm, i.e. smart, connected open architecture product (SCOAP). It follows the adaptable design principles for product extendibility and lifecycle consideration. Moreover, it enlarges the scope of existing open architecture product by involving IT-driven innovation consideration as well. Hence, the definitions, characteristics, evaluation criteria, development method, and lifecycle co-creation context of SCOAP are presented in details. To make it more concrete, a demo project of a smart, connected open architecture bicycle is given at last.     

基于五轴加工中心智能生产线的数字孪生应用研究

智能制造是我国近年来大力倡导的重点发展方向之一。随着智能制造试点的不断建立、发展和完善,数字孪生技术逐步得到应用。基于此,以五轴加工中心智能生产线为例,对数字孪生技术的应用情况进行总结。基于数字孪生技术,按1∶1的比例构建五轴加工中心智能生产线上实体设备的数字模型并配置对应的物理属性,使得数字模型具有与实体设备相同的动作状态。然后,对数字模型进行信号点设置并与外部控制信号进行映射与连接,实现对建成前五轴加工中心智能生产线的虚拟调试,并通过不断迭代获得最优的建设方案。实践结果表明,利用数字孪生可实现智能生产线组合、调试和生产的虚拟仿真;基于数字孪生的虚拟仿真功能,可实现产品物理属性参数和设计精准度的可视化展示,使得产品在设计阶段就能通过适应性验证,实现快速更新;在智能生产线建成后,利用数字孪生可实现对生产线上实体设备的管理及其工作状态的实时监控,以更好地了解各设备的运行状态。综上,数字孪生技术贯穿了智能生产线的全生命周期,可在智能制造领域推广应用。     

Motion generation and virtual simulation in a digital environment

The growing complexity in product design and manufacturing processes has made virtual prototyping an important new approach that enhances products and process development. Considering the ergonomic issues evident in product lifecycles, digital human modelling (DHM) is adopted for virtual simulation and proactive evaluation. A motion generation from semantics (MGS) system is proposed in this research. The MGS system features include virtual prototyping, natural language instruction, a method time measurement (MTM) translator and motion generator. The system was implemented using product lifecycle management (PLM) software and validated in an automotive manufacturing company. The practice of intuitively generating manual operations and conducting virtual simulations enables the system planners to quickly respond to manufacturing process changes and recursively improve the tooling and process design flexibility and efficiency.     

Incorporating production concerns in conceptual product design

This paper presents a set of analytical tools that can be used to alter a product's design, manufacturing processes and assembly techniques to increase production rate. The analytical tools obtain these improvements by simultaneously considering each part's geometric attributes and complexity, vendor selection, material and process selection, and capacity planning at the conceptual stage of the product realization process. The method detects and then avoids heavily used resources by indicating which combination of one or more of its components' geometric attributes, manufacturing processes, material and assembly methods should be altered. The method is illustrated with the analysis of an overhead projector. It is shown that production rate can be doubled by either making small changes to a component's geometric attributes or by selecting different manufacturing processes. Neither of these changes affects the functionality of the product.     

Automatic feature selection for unsupervised clustering of cycle-based signals in manufacturing processes

Recent developments in sensing and computer technology have resulted in most manufacturing processes becoming a data-rich environment. A cycle-based signal refers to an analog or digital signal that is obtained during each repetition of an operation cycle in a manufacturing process. It is a very important class of in-process sensing signals for manufacturing processes because it contains extensive information on the process condition and product quality (e.g., the forming force signal in forging processes). In contrast with currently available supervised classification approaches that heavily depend on the training dataset or engineering field knowledge, this paper aims to develop an automatic feature selection method for the unsupervised clustering of cycle-base signals. First, principal component analysis is applied to the raw signals. Then a new method is proposed to select information containing principal components to allow clustering to be performed. The dimension of the problem can be significantly reduced through the use of these two steps. Finally, a model-based clustering method is applied to the selected principal components to find the clusters in the cycle-based signals. A numerical example and a real-world example of a forging process are used to illustrate the effectiveness of the proposed method. The proposed technique is an important data pre-processing technique for the monitoring and diagnostic system development using cycle-based signals for manufacturing processes.     

先进设计技术平台与包装机械虚拟样机

目的研究先进设计技术平台的构成、包装机械虚拟样机的开发过程。方法采用先进设计技术与工具,规划平台建设方案,建设数字设计、数字仿真、数字测量、数字制造等4个模块构成的先进设计技术平台,制定设计型教学实践项目7个、综合型教学实践项目4个、自主型教学实践项目3个。结合实际研究课题,以打包机上砖装置为例,通过方案设计与3D建模,虚拟样机机构与运动建模,虚拟样机仿真求解,虚拟样机仿真优化等4个步骤,完成虚拟样机开发,并投入实际生产。结果先进设计技术平台在数字设计与仿真、数字测量与制造等2个方面能有效地支持教学和科研。结论平台能够训练研究生掌握先进设计技术与工具,培养其产品创新思维和创新能力。虚拟样机是促进产品创新的有效技术与方法,能提高产品开发质量、缩短产品开发周期。     

Sculptured surface tolerance verification with design datums

Sculptured or free-form surfaces are widely used in many fields with extensive applications. Once such surfaces are manufactured, surface inspection compares the manufactured surfaces with the surface design specifications to verify conformance. Although significant research and development efforts have been devoted to the design and manufacturing of products consisting of partial or sole free-form surfaces, the inspection of these surfaces is still a difficult task. For many engineering applications, a free-form surface is assigned a profile tolerance with reference to design datums for assembly, functionality and other manufacturing requirements. The paper discusses developments of surface inspection techniques for profile tolerance of free-form surfaces. The concept of datum direction frame is proposed to find the transformation information that localizes measurement data to design model. The technique consists of two major steps: localization of measurement data to the design system, based on the datum reference information; and further localization based on the information from free-form surfaces. Testing examples were carried out to validate the developed techniques. The new method does not need corresponding points from the datums of the design model and measured surfaces. Therefore, it is simpler, yet more robust. It can also be used conveniently in manufacturing processes.     

A review of designing machine tool for leanness

As an ideology, Leanness is not a new concept but still researchers strive for developing new methods to reduce almost all kinds of identified wastages at almost every stage and in every activity ?? right from design till delivery of final product to the end-customer. Newly developed manufacturing ideologies, paradigms and systems are always critically examined from the point of view of leanness. In other words, leanness is becoming an important evaluation tool to compare the recently developed/pioneered approaches. There has been a gradual evolution of the leanness over the years from the shop floor level of a manufacturing (automobile) organization to almost every operational and management aspect now. The Leanness has undergone and still is undergoing a process of continuous and never-ending evolution due to its inherently built dynamic concept of continuous improvement. Although in the literature a lot of work has been reported to the application of lean tools, principles, theories and methodologies to production systems, but a very few is evident in the area of Lean design process of a product and machine tool. For this reason an attempt is being made here to focus a significant proportion of this paper on evolutionary aspect of leanness from manufacturing to design stage. Also, this paper reviews the concepts and practices being followed till date by the industrialists, researchers and academicians in applying lean tools and techniques in the design of product and machine tools along with the methods to measure the lean improvements in the systems.     

基于数字孪生与深度学习技术的制造加工设备智能化方法研究

针对传统制造加工设备在生产加工过程中存在设备与数据信息联系不紧密,设备使用维护多依赖于人工经验等问题,提出了一种新的设备智能化方法。首先,在信息层建立能反映制造加工设备真实状态的数字孪生体;其次,基于历史加工大数据,通过数字孪生体对加工过程的行为进行建模及深度学习和训练,并利用训练好的人工神经网络根据采集到的实时数据来预测制造加工设备下一时刻的状态,使制造加工设备实现物理层与信息层数据的深度融合,拥有自我感知、自我预测的能力,最终实现智能化;最后,以浆料微流挤出成型设备挤出结构系统的智能化实施过程为例,验证了所提出方法的可行性。实例结果表明该设备智能化方法可有效地对挤出结构系统的运行状态进行监测及预测,为后续提高挤出成型精度提供了有效的数据信息。研究表明数字孪生和深度学习技术能够提升制造加工设备的智能化程度,可为未来智能制造的发展提供理论支撑。     

Product complexity and design of inspection strategies for assembly manufacturing processes

In the manufacturing field, the assembly process heavily affects product final quality and cost. Specific studies, concerning the causes of the assembly defects, showed that operator errors account for high percentage of the total defects. Also, models linking the assembly complexity with the operator-induced defect rate were developed. Basing on these models, the present paper proposes a new paradigm for designing inspection strategies in case of short-run productions, for which traditional approaches may not be carried out. Specifically, defect generation models are developed to get a priori predictions of the probability of occurrence of defects, which are useful for designing effective inspection procedures. The proposed methodology is applied to a case study concerning the assembly of mechanical components in the manufacturing of hardness testing machines.     

Fuzzy-based analysis of process capability for assembly quality assessment in mechanical assemblies

Process capability indices are useful tools for evaluating the ability of a process to produce products that meet certain specifications. The assembly quality is dependent on the distribution of variations of assembly dimensions, which is in turn dependent on mating conditions in the mechanical assembly. Since it is often difficult to measure the assembly dimensions in the production stages, they are not considered as a direct inspection objective. Rather, the inspection and evaluation of quality is carried out by specifying whether the assembly requirements satisfy the specified limits. Therefore, we can basethe process capability indices on the assembly dimensions. In most real life cases, the observations are fuzzy. In this paper, a novel method based on fuzzy concepts for process capability analysis of assembly dimensions in mechanical assemblies is presented. According to this scheme, sample observations of manufactured variables are described as fuzzy numbers. The proposed method is able to estimate the ability of the manufacturing process in satisfying the assembly quality in the mechanical assemblies with asymmetric tolerances which have non-normal distributions. In this paper, a proper criterion based on the probability of fuzzy set to interpret the computed fuzzy results is proposed, so these results are converted to the interpretable results for making a decision to evaluate the assembly quality. Furthermore, a new fuzzy-based quantity factor for expressing the percent contributions of effective manufacturing variables on the assembly quality is presented. The application of the presented method is demonstrated through an example and its results are discussed.