Advances in Materials Manufacturing Science and Technology II

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Authors: Lei Zhang, Bo Zhang, Lin Ba, Hang Gao
Abstract: The precision machining of the rail base for high-speed Magnetically Levitated Trains (MAGLEV) is the precondition for laying the high-quality whole rail and accomplishing the integrative performance test of the train. A new method is advanced to improving the machining precision in this paper. The X and Y coordinates of the cross centers on the rail base for MAGLEV will be obtained through two raster displacement sensors which are perpendicular to each other. So the machining datum position of the rail will be determined. According to the spatial position relationship between the straight movement error of the guideway on the numerical control machine tools and the central line of the rail base for MAGLEV, error compensation will be made to improve the machining precision in the process of the numerical control machining. The mechanism design theory of the measuring system is presented in this paper. On basis of both the design theory and the software platform of LabWindows/CVI, the virtual measurement system for measuring straight movement error of the rail on the numerical control machine tool, which is used to machining the rail base for MAGLEV will be established.
592
Authors: Tungwai Leo Ngai, Yuan Yuan Li, Zhao Yao Zhou
Abstract: Increasing density is the best way to increase the performance of powder metallurgy materials. Conventional powder metallurgy processing can produce copper green compacts with density less than 8.3g/cm3 (a relative density of 93%). Performances of these conventionally compacted materials are substantially lower than their full density counterparts. Warm compaction, which is a simple and economical forming process to prepare high density powder metallurgy parts or materials, was employed to develop a Ti3SiC2 particulate reinforced copper matrix composite with high strength, high electrical conductivity and good tribological behaviors. Ti3SiC2 particulate reinforced copper matrix composites, with 1.25, 2.5 and 5 mass% Ti3SiC2 were prepared by compacting powder with a pressure of 700 MPa at 145°C, then sintered at 1000°C under cracked ammonia atmosphere for 60 minutes. Their density, electrical conductivity and ultimate tensile strength decrease with the increase in particulate concentration, while hardness increases with the increase in particulate concentration. A small addition of Ti3SiC2 particulate can increase the hardness of the composite without losing much of electrical conductivity. The composite containing 1.25 mass% Ti3SiC2 has an ultimate tensile strength of 158 MPa, a hardness of HB 58, and an electrical resistivity of 3.91 x 10-8 Ω.m.
596
Authors: Jin Zhon Lu, Yong Kang Zhang, De Jun Kong, Su Min Yin, Jian Zhong Zhou, Ai Xin Feng
Abstract: The theoretical researches on fabrication, measurement and identification of laser marking system of 3D(three-dimension) anti-counterfeiting identifiers have been done in this paper. 3D identifiers were fabricated and 3D identifiers’ modelings were reconstructed, and binary coding of gray images were encoded by programmable control of liquid crystal mask, spatial modulating of laser beam and photolithography fabrication technics. We regarded the depth of 3D identifiers as anti-counterfeiting information, and the original marking data and anti-counterfeiting information are saved in remote database server by database technology and computer network technology,so true produces can be distinguished from fake through network. The basic theory of 3D nondestructive anti-counterfeiting identifiers based on liquid crystal mask was built, and a new technology of creating 3D anti-counterfeiting identifiers by laser shock wave was set up, which differs entirely from marking by laser ablation (or laser thermal effect). A new high-efficiency theory of detecting and identifying on 3D anti-counterfeiting identifiers by 3D identifiers’ reconstruction and binary coding was set up. The study enriches dynamic plastic deformation theory of partial high-strain-rate and anti-counterfeiting design & manufacturing theory which is also a highlight based on advanced manufacturing theory of mechanical effect on laser shock wave.
600
Authors: Yong Jun Wang, Jun Biao Wang, Sheng Min Wei, Jiang Jun Jiang
Abstract: In extrusion stretch bending process, there are many factors which affect springback of the workpiece such as mechanical properties of the material, friction condition and process parameters. The springback of same batch of extrusion is different at same forming parameters because of the variation of the mechanical properties of the material and the friction condition. A method of intelligent control of springback in stretch bending process is proposed by using ANN(artificial neural networks). The online identification model of the mechanical properties of the material and friction coefficient and the online prediction control model of springback of workpiece in stretch bending process are established by using ANN ,which are trained by the data of analysis calculation. It realizes the intelligent control on springback of stretch bending to online identify the material properties and friction coefficient and predict springback and adjust process parameters dynamically through the whole process of stretch bending. The results from the experiment state that the intelligent control method can suit the variation of mechanical properties of material and friction condition and improve the geometry precision.
604
Authors: Lin Teng, Qing Hong Le
Abstract: A Computer Aided Innovation (CAI) system was constructed for the New Product Development (NPD) engineers of Guidance, Navigation and Control (GNC) precision complex product, which consists of two modules, namely, Knowledge Management (KM) module and innovation process module. KM module was used to manage internal knowledge of enterprise, and innovation process module provides innovation principles and methods for R&D engineer. The whole CAI system was constructed to utilize the internal and external knowledge effectively, also to bring a structured process for problem-identification, problem-solving and solution-generating during NPD process. At last, an engineering application example demonstrates this system can provide innovation support for GNC product.
608
Authors: Chuang Guo Hu, Ding Hua Zhang, Jun Xue Ren, Lei Yang
Abstract: The study presents a new method for 5-axis machining of blisk, which consists of both roughing tunnels and finishing blades. The ruled surface is used to approximate the freeform surface of blade, and the boundary contour of the tunnel is then determined. Based on the double point offset method, the 5-axis tool paths for roughing blisk tunnel region are generated. Similarly, by linking the corresponding points on the tool center curves and the tool axis drive curves, the spiral tool paths are developed to finish milling thin-walled blades taking into account the residual stresses induced part distortion during machining. This strategy is experimentally verified.
612
Authors: Jun Xue Ren, Ding Hua Zhang, Yao Yao Shi, Zeng Qiang Wang
Abstract: This paper presents a new method for chatter suppression during finishing thin-walled blades. Traditionally auxiliary support is used to increase the stiffness of the structure, however, the shrink or dilate effect of the packing material, such as wax and rosin, is difficult to control, so the machining precision could not be assured. Based on the principle of stiffness optimization principle, the rigidity of the cantilever blade tip and leading/trailing edge region are improved with the non-uniform allowances distribution. The milling experiments have showed that the proposed strategy could be successfully used to realize the suppression of chatter vibration during flexible parts machining.
616
Authors: Yan Xu, Kai Leung Yung, Hai Pang Ng
Abstract: Understanding the solid conveying process is important for the optimal design of micro injection molding machines. To solve problems such as starve feeding and process instability during plastication of polymers, which deteriorate product qualities, studies have been carried out on the conveying process of discrete polymer pellets. The effect of screw axis inclination on the speed of solid conveying is investigated with both simulation and experimental approaches. A discrete element modeling method (DEM) specially designed for simulating polymer particle movements in screw channels, which takes into account the effect of gravity while maintaining the simplicity of calculations, has been developed. The agreements between results of simulations and experiments verify the integrity of the models developed herein. The proposed modeling method is capable of optimizing the design of plasticizers of micro injection molding machines.
620
Authors: Lan He, Kai Leung Yung, Yun Wen Shen, Yan Xu
Abstract: The rheological properties and phase orientation of liquid crystalline polymer (LCP) melts flowing in a nanochannel with different surface roughness are investigated by molecular dynamics (MD) simulations. Simulation results show the surface roughness has great impact on the rheological properties and phase orientation of LCP melts in the nanochannel (cross section is 12nm). As the amplitude of serrations increases, the shear viscosity increases nonlinearly and the value of orientational order parameter decreases. When the serration amplitude is larger than 1.1nm, a phase transition (from nematic to isotropic phase) of LCP melt happens, which makes flowing in nanochannels more difficult. On the other hand, the influence of serration period on the shear viscosity and orientational order parameter are found not so obvious. Findings in this study will be helpful for injection molding plastic products with nanofeatures.
624
Authors: Xiao Peng Jiang, Run Xiao Wang, Tao Li, Zhi Qing Luo, Dong Bo Wang
Abstract: Reconfigurable manufacturing systems (RMS) offer capabilities for quick adjustment of production capacity and functionality in response to sudden changes in market conditions. Both at the system and at the cell level exception events occur dynamically and unpredictably during the production process. These exceptions interrupt the production process by causing errors in the schedule plan. Error/ exception handling is the policy how to deal with errors caused by the occurrence of out-of-ordinary events. Author explores the new strategies to handling error events and proposes an intelligent control structure for real-time error handling, and illustrates the reconfiguration ability is the new crucial technological factor enabling new strategies to handle out-of-ordinary events of the production process.
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