Assessment of Manufacturing Operational Complexity

The manufacturing system must balance human characteristics, needs, skills and capabilities within the technical and business environment, in order to be effective and successful. A Systems Analysis and Design approach was utilized to integrate manufacturing technologies with the capabilities of human workers, in order to augment the performance of both. A framework was created on which to build systems analysis tools that focus on realistic factors within the manufacturing environment, such as information quantity, diversity and content; complexity (product, process and operational); task effort, and so forth. A matrix methodology and an objective measure of complexity have been developed that assess the three levels of manufacturing complexity: product complexity, process complexity and operational complexity. The focus of this paper is the ‘operational complexity’ and it provides insight into the system performance and sensitivities when considering human characteristics.     

基于知识工程的工艺决策方法研究

为了解决集成环境下的复杂零件的工艺决策问题,从问题描述、规则定义和过程控制三个方面出发,提出了以"对象-规则-过程"为核心的知识工程应用方法.分析了包括产品特征信息、工艺过程信息、资源能力信息和加工方法知识信息在内的工艺决策对象信息,提出基于本体和元模型的建模框架.研究了基于规则引擎的工艺决策规则的表达和应用的方法.在分析工艺决策的过程化特点的基础上,结合工作流思想,提出工艺决策的过程化组织模式.开发了工艺设计原型系统,支持工艺决策方法的实施及应用.     

A process sequence design on the forming process of disk-brake piston

A design methodology is applied to manufacturing a disk-brake piston component. A rigid plastic finite element method is applied to simulate the conventional four-stage manufacturing process and the one-step process from a selected stock to the final product shape for information on metal flows. Two-stage forming operations with different punch corner and nose radii are also simulated to identify the best possible solutions. The best manufacturing process is selected, which uses a hemispherical punch in the drawing process. Experiments are conducted for comparison with the numerical results. The good agreement between the experimental and numerical results validates the design methodology using the finite element method.     

基于分布式结构的制造系统信息集成技术研究

在制造系统运行过程中,底层模块会产生大量的现场信息。随着对网络化制造技术的深入研究和实施,有必要对现场信息加以管理和利用,所以需要开放的分布式软件平台将这些信息进行集成。为此,利用DNC、局域网及互联网的成熟技术,提出了一种基于分布式结构的制造系统信息集成框架,并根据该框架设计了对应的分布式信息处理平台。最后,根据上述研究方法在.NET环境下建立的一种B/S模式的制造系统信息集成模型。     

现代制造企业对制造信息系统的需求与发展问题研究

分析了在市场环境发生变化的情况下，现代制造企业对信息技术的实际需求及其制造信息系统存在的主要问题，探讨和研究了现代制造业对信息技术的实际需求及其发展趋势与特征，旨在为企业适应新的生产管理和组织模式，构建新一代制造信息系统的软件开发集成平台，进一步促进制造企业实现网络化集成产品的开发与制造奠定基础。     

Methodological Approach and Reconfiguration Tool for Assembly Systems

Assembly lines design is intended to solve many problems related to assembly operations. The introduction of a new product should often entail the salvage of existing assembly lines. This work proposes a methodology for assembly line reconfiguration, to rationalize and support the redesign process of assembly systems. This research formalizes a representation model and a method for assembly line reconfiguration. The model describes the main characteristics and significant features of the assembly process. The study is concerned with three fundamental models, the first describes assembly line structures. The second illustrates component assembly features and the third produces all the assembly sequences. The assembly line reconfiguration method provides an analysis and estimation tool on the reconfiguration process complexity. The method proposed is also meant to be a tool to identify the operational flexibility limit. The method results point out the way to implement assembly system reconfiguration and gives detailed information about the assembly line. Each assembly line, facing a new product to be assembled, is processed with the reconfiguration method and receives operative results for reconfiguration process and quality indicators.     

基于变速箱装配线的虚拟规划建模与仿真

数字化制造可充分利用产品生产制造过程中的各类信息,为产品生产系统的设计提供有效依据.本文结合变速箱的生产特点,提出了变速箱装配线的模型构建方法,使用Quest数字化仿真软件完成了变速箱装配线的虚拟规划仿真,并根据仿真结果实现了部分制造参数的优化.     

Evaluating the substitution risk of production systems in volatile environments

Today’s manufacturing companies are confronted with key challenges such as an increasing individualization and shorter product life cycles. Production systems are to be made resistant to substitutions in order to secure sustainable competitive advantages in such a volatile market environment. A production system runs at risk of being substituted if an alternative production system exists, which is at least equivalent in terms of economic, ecologic, social, and technological criteria with respect to current as well as possible future product programs. The research presented in this paper provides a systematic approach to assess the substitution risk of production systems regarding a current as well as possible future product programs. It comprises a methodology, which allows for a static and dynamic evaluation of production systems based on analytical cost models, scenario creation and real options analysis. By implementing a Monte Carlo simulation, various probability distributions of system parameters can be taken into account. The presented methodology focusses on economic and ecologic aspects. Finally, the methodology is applied to a case study.     

Utilising robotic process automation technologies for streamlining the additive manufacturing design workflow

This paper proposes a framework that utilises robotic process automation (RPA) technologies within the additive manufacturing (AM) design workflow to make the product development process more efficient. A commercial RPA platform is employed to create an automated workflow, which is capable of considering multiple AM process configurations. The main objective is to ensure that AM process cost and time requirements may be reliably calculated for any Computer-Aided Design (CAD) part model and multiple process configurations via simulation, with minimal human interaction. The proposed automated workflow was tested on a realistic case scenario and was compared against a standard conventional AM workflow.     

Functional model for the development of an inspection integration framework

Product dimensional inspection is set as one of the essential parts of the production process, where not only product quality test is checked but also its interaction with other development stages in a minimal time. This enables a feedback to make quicker production and design decisions, provides updated information about the inspection processes to be shared and used in the new development processes, and permits the simultaneous work in the preparation of the inspection processes themselves. For this aim, it is necessary, as it occurs in the STEP framework, to develop an application context that includes all dimensional inspection aspects, from the geometrical and measurement aspects to those related to administration and configuration product data. This paper proposes a solution to integrate the dimensional inspection process with coordinate measuring machines with the design and manufacturing processes. Integration is achieved through a common product information model. A functional information model, a reference information model and an interpreted information model have been defined. The interaction with other information models associated to other activities of the production cycle is possible. Tests have been made of the possibility of making the inspection information interchange at the operation level instead of making it at the CMM trajectory level, as it is the case of the current DMIS format. This level of information definition is easier to put into effect, easier to interpret, and it is more productive.

In order to test the validity of the information model, a real work environment which has been called IFCIA (Inspection Framework for Concurrent Information Access) has been developed. The IFCIA architecture is composed of a product modelling system, an object-oriented central database and a tri-dimensional coordinate measuring machine. The model has been implemented on an object-oriented product central database which is accessible by all the applications, so that the access to data is achieved in a concurrent way and in real time for the different agents involved in the development cycle, in a heterogeneous framework of platforms and applications. The generation and transference of the information among these systems are carried out exclusively according to data structures defined in the information model.     

A multi-agent architecture for plug and produce on an industrial assembly platform

Modern manufacturing companies face increased pressures to adapt to shorter product life cycles and the need to reconfigure more frequently their production systems to offer new product variants. This paper proposes a new multi-agent architecture utilising “plug and produce” principles for configuration and reconfiguration of production systems with minimum human intervention. A new decision-making approach for system reconfiguration based on tasks re-allocation is presented using goal driven methods. The application of the proposed architecture is described with a number of architectural views and its deployment is illustrated using a validation scenario implemented on an industrial assembly platform. The proposed methodology provides an innovative application of a multi-agent control environment and architecture with the objective of significantly reducing the time for deployment and ramp-up of small footprint assembly systems.     

A systematic approach to enhance machine tool accuracy for precision manufacturing

As competitive pressures demand higher levels of productivity and automation, accuracy and reliability of products become increasingly important. Innovations in manufacturing technology also are driven by demands to shorten production cycle time and to maintain a consistently high level of product quality in an advanced manufacturing environment. Innovative and cost-effective methods must be developed to advance precision manufacturing technologies to compete in the global economy. In this paper, a systematic approach is presented to advance the accuracy and functionality of multi-axis machines for precision manufacturing. Four major steps are introduced. First, a method is presented for rapid characterizing of the accuracy of multi-axis machines. Detailed derivation of a generalized error model is given. Second, a method is discussed on the feasible applications of on-machine sensing and analysis. The information obtained from on-machine sensing process is used with the information collected from post-process inspection to improve the machine performance. Third, a method is presented for utilizing post-process inspection and innovative data analysis techniques to decouple the effects of process- and machine-related errors. Finally, an adaptive error correction system is outlined for iterative identification of the residual error and the fine-tuning of the error model for more accurate error modeling and compensation.     

Process sequence design in cold forging to form a constant velocity joint housing

A systematic approach to process sequence design is established by the finite element method for multi-operational cold forging to form a constant velocity joint housing. Both the loading simulation and the backward tracing by the rigid plastic finite element method provide useful information for designing new process sequences. The newly designed sequence has four forming operations and one annealing treatment, and can achieve net-shape manufacturing, while the conventional process sequence has five forming operations and two annealing treatments, and requires machining after forming. The refinement at the top surface of the product is made by applying the backward tracing scheme for the purpose of net-shape manufacturing. This specific case can be considered for application of the method and for development of the sequence design methodology in general.     

Laser ultrasonic testing for near-surface defects inspection of 316L stainless steel fabricated by laser powder bed fusion

The laser powder bed fusion (L-PBF) method of additive manufacturing (AM) is increasingly used in various industrial manufacturing fields due to its high material utilization and design freedom of parts. However, the parts produced by L-PBF usually contain such defects as crack and porosity because of the technological characteristics of L-PBF, which affect the quality of the product. Laser ultrasonic testing (LUT) is a potential technology for on-line testing of the L-PBF process. It is a non-contact and non-destructive approach based on signals from abundant waveforms with a wide frequency-band. In this study, a method of LUT for on-line inspection of L-PBF process was proposed, and a system of LUT was established approaching the actual environment of on-line detection to evaluate the method applicability for defects detection of L-PBF parts. The detection results of near-surface defects in L-PBF 316L stainless steel parts show that the crack-type defects with a sub-millimeter level within 0.5 mm depth can be identified, and accordingly, the positions and dimensions information can be acquired. The results were verified by X-ray computed tomography, which indicates that the present method exhibits great potential for on-line inspection of AM processes.     

Analysis–synthesis of dimensional deviation of the machining feature for discrete-part manufacturing processes

Dimensional deviation analysis has been an active and important research topic in mechanical design, manufacturing processes, and manufacturing systems. This paper proposes a comprehensive dimensional deviation evaluation framework for discrete-part manufacturing processes (DMP). A generic, explicit, and transmission model is developed to describe the dimensional deviation accumulation of machining processes by means of kinematic analysis of relationships between fixture error, datum error, machine tool geometric error, fixturing force inducing error and the dimensional quality of the product. The developed modeling technology can deal with general fixture configurations. In addition, the local contact deformations of the workpiece–fixture system are determined by solving a nonlinear programming problem of minimizing the total complementary energy of the frictional workpiece–fixture subsystem in machining system. Moreover, the deviation of an arbitrary point on machining feature can be also evaluated based on a point deviation model with prediction dimension deviation from the transmission model. The dimensional error transmission within the machining process is quantitatively described in this model. A systematic procedure to construct the model is presented and validated. This model can be also applied to process design evaluation for complicated machining processes.     

Integrated Virtual Manufacturing Systems for Process Optimisation and Monitoring

The implementation of an Internet-based Virtual Manufacturing facility for the development and optimisation of new manufacturing processes is presented. The facility integrates advanced process simulation software, a remote machine monitoring system and multimedia technologies to realise a virtual environment for manufacturing process optimisation. Utilising physics-based process simulations, process parameters and operational sequences are evaluated and optimised with respect to desired product features. Having optimised the operation, a prototype of the part can be created at the facility. During prototyping, process parameters are monitored in real-time. A Case Study is presented, where a 3-axis milling operation is defined, optimised and executed using the facility.     

Adaptive model estimation of machine-tool thermal errors based on recursive dynamic modeling strategy

A systematic model adaptation methodology is developed in order to continuously update the thermal-error model under varying manufacturing conditions. Process-intermittent probing and adaptive system identification techniques are integrated to monitor and estimate machine-tool thermal errors and recursively modify model coefficients as manufacturing process proceeds. The recursive model adaptation, which is based on the Kalman filter parameter estimation technique and multiple-sampling horizons, minimizes intrusion to production while maintaining good model adaptation capability. The experimental results proved that the proposed methodology has good model accuracy and robustness to frequently changing working conditions.     

Optimization of Steel Production to Improve Lifecycle Environmental Performance

To reduce lifecycle impacts, manufacturers require an understanding of how design, manufacturing, and other decisions influence their eco-footprint across all product lifecycle stages, e.g., manufacturing, use, and end-of-life. However, few tools exist to address manufacturing impacts on the environment. For many products, steelmaking accounts for the majority of manufacturing energy use, with process wastes also representing significant concerns. A predictive model for a steelmaking electric arc furnace (EAF) is briefly described and is then used to illustrate how environmental performance can be optimized for a given steel alloy. Process inputs are identified that minimize a variety of environmental measures.     

数字化制造工程系统在工艺评审中的应用

数字化制造工程系统(DMES)是基于研发PDM系统建立的设计、制造一体化开发和管理的系统平台,以产品数据、工艺数据、工厂数据和资源数据为基础,在数字化环境内,进行产品制造工艺规划、工艺仿真和工艺可行性评审。主要针对SE工艺评审业务活动,提出了工艺虚拟评审在DMES中的应用方案,以实现系统对业务过程的有效支持。