Advanced Materials Research Vols. 139-141

Abstract: 6σ has proved numerous times that it can help any business to deliver products to meet or even exceed customer expectations. DMAIC (Define – Measure – Analyze – Improve - Control) is one of the Six Sigma methodologies used for a 6σ project that aims to improve and control quality of exiting products. Aiming at the drawbacks existed in the problem selection in definition stage, considering the fuzziness and uncertainty of problem analyzing, a method integrating fuzzy QFD (Quality Function Deployment), frequency-cost FMEA (Failure Mode Effect Analysis) and gray relation analysis is presented, in which the customer requirements, occurring frequencies and the relative costs of the problems are taken into account comprehensively. Thus the key quality characteristics or process features to be improved are determined, which can provide decision support for key problem selection. An example is given to illustrate the effectiveness of the proposed method.

Abstract: Product configuration design is a knowledge intensive process during product development. It is a critical step as the cost and quality of a product is based on decisions made at this stage. In the iterative process of product configuration design, customers and design engineers use different terms describing products which often results in misunderstanding. Based on the historical transaction records of customer requirements and design parameters, this paper proposes an Apriori-based data mining method to transform the implicit knowledge into explicit association rules. Three criterions, support, confidence and interestingness, are applied for the evaluation of the extracted rules. The effectiveness of the proposed method is illustrated with a case study of electrical bicycles. The results show that that the proposed method can be a promising tool for product configuration design.

Abstract: Dimensional tolerance is an important factor for the geometry quality of products. The stiffness matrices of sheet metal components are usually not variational during the process of tolerance analysis; however, material properties of the compliant parts may change in volume production. The variation of the part thickness changes the part stiffness matrix so that the sensitivity matrix is different from that of the assembly with nominal thickness. The paper proposes an improved sensitivity matrix between the incoming part variation and the assembly variation for the assembly with thickness variation. Moreover, the orthogonal design is used to judge the importance of part and thickness variation for the assembly deviation. The proposed method is illustrated through a case study and the results show that the thickness variation influences the relationship between the part variation and the assembly variation. In addition, part variation plays a more important role to assembly variation than the thickness deviation does according to the orthogonal design.

Abstract: Based on virtual prototyping technology (VPT) and software engineering principles, and combining with the characteristics of steam jet pump, a virtual prototyping development platform of steam jet pump, consisting of five functional models, including general scheme design, virtual physical prototype design, virtual performance prototype design, assemble process analysis and VR model design and evaluation, was present in this paper. The architecture and functional model of the virtual steam jet pump prototyping development platform (VSJPDP) were proposed in the article. The ideas corresponding to several key technological problems for implementing the VSJPDP were also described. At last, the platform’s feasibility, effectiveness and advancement were verified by the development process of the virtual single-stage steam jet pump.

Abstract: With the production system of modern manufactures complexity increasing, it is very difficult to establish a practical model to satisfy the current trend by means of traditional methods and theories of modeling. According to IDEF0 modeling method, this paper presents a functional model of the production line object model framework. Based on this, an object-oriented abstraction mechanism is considered to solve the camshaft production line complexity practical situation and an object-oriented Petri nets (OPNs) modeling is proposed. Simulation models are established by using Witness 2008 simulation software based on camshaft production line to analyze the layout and bottleneck of production line, to check the design programs, and to optimize configuration and layout of the production line furthermore. The manufacturing capacity of the line is also discussed in this paper. Finally the corresponding solutions to avoid the existing bottleneck of the line are also discussed in detail.

Abstract: With the development of scientific and technology, the automotive industries competition is becoming more and tougher. The camshaft production system is an important part of the engine manufacturing. The production line productivity and characteristic are affected by many practical factors of the workshop. It’s a complex discrete manufacturing system somehow. In this paper, the production line model is presented based on Petri net. Then the mapping relationship is established between the Petri net model and the eM-Plant discrete system model. The discrete simulation model of production line is constructed by using eM-plant software. Based on the simulation, the reasonable simulation experimental are carried out with the determined simulation boundary and objectives under the different input conditions such as orders, the working stations' processing time, the working stations’ fault distribution, and the production line layout. The simulation experimental results are discussed on condition that the shifts, equipment operation condition, production line capacity and WIP in detail. These results could provide the theory basis for decision-making of the production plan of the automotive industries.

Abstract: According to sine law, a vertical wall square box can’t be formed by NC incremental sheet metal forming process in a single process, rather, it must be formed in multi processes. A vertical wall square box can be considered to consist of corners and straight sides. Straight sides and corners affect each other and the effect is different in various square boxes. The effect depends on the ratio r/B of the corner radius r and straight side width B. The smaller r/B, the larger the effect of straight side on corner is. In this case, the deformation in the straight sides isn’t even, and the metal of the corner is compressed and gradually piled up. With the increase of r/B, the deformation becomes more uniform. The tool path with gradually reduced corner radius is adopted to overcome this question. A vertical wall square box with small corner radius is successfully formed.

Abstract: The incremental sheet metal forming technology is a flexible forming technology without dedicated forming dies. The locus of the forming tool can be adjusted by correcting the numerical model of the product. The effect of forming half-apex angle on forming process with all kind of sheet material, sheet thickness and ironing ratio is researched. The limit half-apex angle is different for all kind of sheet material and thickness. The limit half-apex angle is smaller for the larger thickness of sheet metal. It will succeed in square conical box incremental forming in a single tool-path if the forming is carried out with an angle which is larger than the forming limit half-apex angle θ. The ironing ratio ψt is decided by the forming half-apex angle θ. The ironing ratio ψt varies with θ. The ironing ratio ψt is smaller when is larger.

Abstract: The security of BPEL (Business Process Execution Language) based manufacturing service workflow management system is researched in this paper, in order to achieve the efficient and secure integration and sharing of dispersed and heterogeneous design/manufacturing resources, and to realize the reuse of the complex distributed Design/Manufacturing process models. By integrating the secure BPEL engine, proxy credential server and authentication trust level, the security framework of the BPEL based manufacturing service workflow management system is built up, and the security mechanism of integrating BPEL and WSRF (Web Service Resource Framework) is analyzed. In addition, the system implementation technologies are analyzed and a distributed injection mould Design/Manufacturing application scenario is described. The research results provide the basis for developing a secure BPEL based distributed Design/Manufacturing prototype system.

Abstract: The accuracy and efficiency of case retrieval decline with individuality and diversity of customer needs in current product configuration design. To cope with this problem, this paper proposes the method of case retrieval based on NRS and KNN. Firstly, setting neighbor value can effectively avoid errors generated by discretization of continuous attributes in classical RS. Secondly, NRS is used for redundant reduction and weight allocation of attributes, and to calculate distance of each sample points by weighted distance. Thirdly, K similar cases are selected according to Euclidean distance with weight, then the case that meet customer needs best is acquired. Lastly, product configuration of coal mining machine is used to illustrate that accuracy and efficiency of the method are superior to the existing methods of case retrieval.