空间凸轮刀位补偿加工方式中理论加工误差的研究

开展空间凸轮廓面的非等价加工研究是实际生产的需要，刀位补偿加工方式因其加工效率高，成本低而受到研究者的重视。运用等距曲面理论对“刀位补偿加工必然存在理论徊工误差”的命题进行了理论证明，探讨了刀位补偿加工的基本思想，推导出了刀位补偿加工中的凸轮廓面综合的数学模型，给出了相应的计算机实现算法。     

3D Metal printed heat sinks with longitudinally varying lattice structure sizes using direct metal laser sintering

This research relates to the design, modelling and fabrication of 3D metal printed heat sinks. The heat sinks presented in the research are the commonly used longitudinal fin solid heat sink (LFSHS) and three LFSHS lattice structure designs, differing only in their lattice sizes, fabricated using the Direct Metal Laser Sintering (DMLS) technique in Maraging Steel (MS1), on an EOSINT M280 system. In order to increase the heat sink surface area, the heat sinks are manufactured with mesh lattices along the length of the fins, while keeping the overall heat sink volume constant. The research is focused on pushing the limitations of the DMLS technique for the development of repeating unit, lattice structures heat sinks, and to examine the effect of incrementally varying the lattice sizes with regards to the resultant surface area of the heat sink and the thermal performance of the system. The results obtained under natural convection show that the thermal performance of the LFSHS outperformed all lattice structure heat sinks. This is due to the fact that, the pressure drop across the lattice heat sinks were so high, due to lattice meshes that it negated the positive effect of the greater surface area.     

Near optimal process plan selection for multiple jobs in networked based manufacturing using multi-objective evolutionary algorithms

The networked manufacturing offers several advantages in current competitive atmosphere by way of reducing the manufacturing cycle time and maintenance of the production flexibility, thereby achieving several feasible process plans. In this paper, we have addressed a Multi Objective Problem (MOP) which covers-minimize the makespan and to maximize the machine utilization while generating the feasible process plans for multiple jobs in the context of network based manufacturing system. A new multi-objective based Territory Defining Evolutionary Algorithm (TDEA) to resolve the above computationally challenge problem have been developed. In particular, with two powerful Multi-Objective Evolutionary Algorithms (MOEAs), viz. Non-dominated Sorting Genetic Algorithm (NSGA-II) and Controlled Elitist-NSGA-II (CE-NSGA-II) the performance of the proposed TDEA has been compared. An illustrative example along with three complex scenarios is presented to demonstrate the feasibility of the approach. The proposed algorithm is validated and the results are analyzed and compared.     

Model for flexibility evaluation in manufacturing network strategic planning

In response to market pressures, manufacturers have adopted different approaches to provide flexibility regarding several aspects. In this paper, we suggest a model for the evaluation of the flexibility of the manufacturing supply chain, based on graph theory techniques. This model defines maximum excess demand that may be met using flexibility. Recourse to flexibility enablers is determined based on cost minimisation. Such enablers are volume flexibility, mix flexibility and safety stocks. The proposed model is solved using a two-step Mix Integer Linear Programme; the first step consists in defining maximum demand that may be met while the second step concerns minimising cost. The main benefit of our model is to deal with realistic problems in a rather short time. Therefore, it can be used in a wide ‘what-if’ design process. It means evaluating various contemplated flexibility configurations in multiple demand scenarios in order to choose the best option. It can be also used during operational supply chain planning in order to face to an unbalanced situation. This paper ends with a numerical example illustrating our model’s efficiency.     

Developing manufacturing ontologies for knowledge reuse in distributed manufacturing environment

The use of ontologies for knowledge sharing and distributed collaboration has been widely recognised in the knowledge modelling community, but the lack of a systematic and constructive methodology for developing manufacturing ontologies has impeded their wide usage for knowledge reuse in distributed manufacturing environments. This paper presents a constructive, two-level knowledge modelling approach to systematically develop manufacturing ontologies using both software engineering and Semantic Web paradigms. The UML/OCL (Unified Modeling Language/Object Constraint Language)-based object modelling is used first to serve as a graphical and structured basis for conceptual communication between domain experts and knowledge engineers. The OWL/SWRL (Web Ontology Language/Semantic Web Rule Language)-based ontology modelling then extends the UML/OCL-based object models with added semantics using a progressive, semantics-oriented knowledge acquisition method. An illustrative example for manufacturing ontology development in the manufacturing industry for producing electronic connectors is used to demonstrate the practicality of the proposed approach.     

Evaluating the performance of a discrete manufacturing process using RFID: A case study

The material flow is a major focus point in improving productivity in today’s product diversified manufacturing organizations. Nevertheless, there is still a lack of efficient methods to control material flow through manufacturing processes in cases where multi-item tracking is difficult to achieve. This paper presents an RFID-based RTLS (Real-Time Location System) solution for obtaining multi-item work-in-process visibility within a manufacturer. It delivers detailed performance metrics through RTLS data analysis in order to evaluate workflow performance and to obtain a lean process. We pre-filter the RTLS data through the development of a middleware data collection method to acquire near real-time performance evaluation. A case study illustrates the complete process including measurements before and after a workflow redesign. The increased level of detail from RFID measurements yields new insights into shop floor actions and the real effects of redesign efforts.     

Practice world

Civil Engineer Sigurd Hveem at the Norwegian Building Research Institute, BI, describes the laboratory and field tests carried out on the dynamic response of different lightweight timber floors to establish new design guidelines. NBI are also looking at theoretical calculation methods in order to predict the results obtained by measuring dynamic properties.     

Characterisation of 4043 aluminium alloy deposits obtained by wire and arc additive manufacturing using a Cold Metal Transfer process

ABSTRACT

4043 aluminium deposits were elaborated using a 3D print device equipped with a Cold Metal Transfer welding source. Two sets of process parameters leading to different average powers were compared in order to establish the relations between the powers and energies produced and the geometrical characteristics of the deposits. The effects of the travel speed and layer superposition on the transfer mechanisms as well as on the geometrical characteristics of the deposits were discussed for both sets of parameters. Finally, the formed microstructures were analysed and the porosity defects were quantified and discussed with regard to the heat input characteristics and the solidification conditions.     

注射模的绿色设计与制造初探

将绿色制造的理念运用于注射模的设计与制造中，在介绍绿色制造的概念、内涵的基础上，介绍了注射模绿色制造的整个生命周期，包括绿色设计、绿色制造、绿色回收、再处理等，并结合注射模自身的特点，具体阐述了基于绿色制造的注射模设计与制造方法。     

New Young Writers on Wool

Abstract

I am fascinated by performance architecture. My particular interest is in theatrical qualities of spaces and the beauty of the processes happening within the space. I felt that the wool manufacturing process is a spectacular performance of sound, texture, and density of light—hence it could be reinterpreted through architecture. The essay was written to celebrate the theatricality of the wool manufacturing process.