Advanced Materials Research Vols. 299-300

Abstract: Binding additives used in selective laser sintering (SLS) of metal powders determine the vital performance of untreated metal prototypes. The types of polymer binding materials were presented in this work. The binding conditions and processes were represented. The thermal variations of binding additives and interfaces actions between polymer and metal were discussed. This work provides a reference for the selection of polymer binding additives in SLS.

Abstract: Mill-grinding experiments were carried out on SiCp/Al to investigate effects of mill-grinding parameters and grinding wheel parameters on machined surface roughness in this paper. The machined surface topography was also analyzed. Experimental results show that surface roughness increases with increasing feed rate and the depth of the mill-grinding. The effect of mill-grinding speed on surface roughness is low. The machined surface reveals many defects. The fine grit diamond grinding wheel can reduce the surface roughness and decrease the machined surface defect. Compared to the vitrified bonded diamond and electroplated diamond grinding wheels used in the experiment, the resin-based diamond grinding wheel produces a better surface.

Abstract: Self-reconfigurable modular robots consist of many identical modules. By changing the connections among modules, the whole configuration of the robot can transform into arbitrary other configurations. In this paper, a hybrid self-reconfigurable modular robot is designed, which is composed of a master module and a slave module. Then, the docking process is analyzed with the geometric method. The docking states between two modules are presented. It is a complicated multi-peg-in-hole process.

Abstract: By applying the direct calculation of Maxwell stress tensor using three-dimensional finite difference time domain method, the feasibility of using a metal-coated fiber probe to create near-field optical tweezers is investigated. Numerical results indicate that these schemes are able to trap nano-particles with lower laser intensity than that required by conventional optical tweezers. The near-field optical trapping systems that are more flexible than conventional optical tweezers are built. In experiments, 120-nm polystyrene particles are trapped in a multi-circular shape with a minimum size of 400 nm. The realization of trapping particles in the range of tens of nanometers largely promotes the role of near-field optical manipulation at the nanometer scale.

Abstract: A finite element model of an eddy current sensor array is built up by electromagnetic-circuit couple method, and the influences of crack length and frequency on sensor’s output characteristics are analyzed by this model. It is shown that the model established in this paper is reasonable. There would be a change on amplitude and phase when a crack appears below the footprint of sensing coil in metal plane, and the amplitude and phase of sensor coil are increasing gradually as crack propagation. As frequency increased, the differences between the sensing coils’ output become obvious. However, the differences begin decreasing while the frequency above 3MHz approximately. These results will provide a reference for further research and application of the sensor.

Abstract: The finite element method is adopted to analyze the pre-loaded cylindrical roller bearings according to the theory of contact mechanics. The effects of hollow ratio on the radial stiffness of bearings, the maximum contact stress of rollers, and the maximum radial load of bearing are analyzed. The analysis results show that the smaller the hollowness is, the larger the radial stiffness of pre-loaded cylindrical roller bearings, the maximum contact stress of the rollers, and the maximum radial load of the bearing would be. Under different magnitude loads, the reasonable combination of interference magnitude with the hollowness can not only increase the stiffness of roller bearings, but also decrease the maximum stress of rollers, which provides a reference for the design and manufacture of pre-loaded cylindrical roller bearings.

Abstract: The three-dimensional parametric model of spiral bevel gear was built based on Pro/E, The parametric model was converted to Patran, and the modal analysis, 10 order natural frequency and 10 order correspondence with the frequency were obtained with the Nastran. It can avoid the resonance in the design of spiral bevel gear.

Abstract: The application of Yolico YD5000 series YD5200 frequency converter in mine hoist is presented. The parallel Yolico YD5200 energy feedback unit is adopted to overcome the traditional hoist disadvantages, such as discontinuity of running speed and being unsatisfied with speed adjustment. From the local records of debugging, hoist system running steady, the design requirements are satisfied.

Abstract: Currently, design and processing of complicated model are enabled by the progress of the CAD/CAM system. In shape measurement, high precision measurement is performed using CMM. In order to evaluate the machined part, the designed model made by CAD system the point cloud data provided by the measurement system are analyzed and compared. Usually, the designed CAD model and measured point cloud data are made in the different coordinate systems, it is necessary to register those models in the same coordinate system for evaluation. In this research, a 3D model registration method based on feature extraction and iterative closest point (ICP) algorithm is proposed. It could efficiently and accurately register two models in different coordinate systems, and effectively avoid the problem of localized solution.

Abstract: Several rotating rates and welding speeds were chosen to joint 6063/3A21 dissimilar aluminum alloys, tensile strength of the welds were measured to analyze effect of welding parameters on weld performance. Results show that tensile strength of the weld is better than the base material. Weld tensile strength will decrease under a too high or too low welding speed while effect of rotating rate on weld strength is relatively small. The weakest position is at heat affected zone at 3A21 side after T6 post weld heat treatment.