Key Engineering Materials Vol. 499

Abstract: Using the designed multi-tooth tool, a novel porous metal fiber sintered felt (PMFSF) with three-dimensional reticulated structure has been produced by solid-state sintering of copper fibers. The copper fibers were fabricated using the cutting method. According to the SEM results, it was found that there were two kinds of sintering joints of surface contact and crossing fiber meshing among the fibers in the PMFSF. The coarser sintering joints will help to enhance the mechanical strength of PMFSF. Based on the structure characteristic, a three-dimensional model with the cubic pore cell structure was established to describe the structure of PMFSF. In addition, the effectiveness of geometric model was verified by the test results of specific surface area of PMFSF.

Abstract: In this study, mechanical model of plowing process considering material flow process was built. Dynamic material model of workpiece (AISI D2) was included in this plowing model. The friction between diamond indenter against AISI D2 steel was obtained by the ball-on-plate test. The scratch tests with diamond indenter against AISI D2 steel were performed. The scratch morphology was investigated by white light interferometer. The scratch forces in the different loads were calculated by the mechanical model of plowing process. The calculated scratch forces showed good agreement with experimental results.

Abstract: Light-weight structures operating at high speeds may suffer from significant vibration problems, thus degrading positioning accuracy and exhibiting large settling time. High-performance vibration and motion controllers are usually designed based on precise dynamic model. This paper addresses the problem of modeling and identification of a high speed high accuracy lightweight positioning stage with flexible arm. A simplified state space model for vibration motion control purpose is given. A separated identification method is proposed. The parameters related to rigid body part and flexible body part are identified, separately. Rigid body dynamics is firstly identified by employing unbiased Least Squares technique. Subsequently, flexible body dynamics is identified by impact test and nonlinear LS technique. The experiment results show that applying proposed identification strategy can get more precise low frequency rigid body dynamic parameters without loss the identification precision of high frequency parameters.

Abstract: The grain growth in the sintering process of ceramic materials has an important impact on the ceramic materials performance. In this paper, a grain growth simulation model considering the requirement of heat and space is established. The Al2O3-based ceramic materials are preparation, and the model is verified by the Al2O3-based ceramic materials. The simulated results of the grain growth by the model are very close to the grain growth of Al2O3-based ceramic materials. The model can be used in the study of grain growth in ceramic materials sintering process.

Abstract: This paper presents a simulation study of an H-type vertical axis wind turbine. Two dimensional CFD model using sliding mesh technique was generated to help understand aerodynamics performance of this wind turbine. The effect of the pith angle on H-type vertical axis wind turbine was studied based on the computational model. As a result, this wind turbine could get the maximum power coefficient when pitch angle adjusted to a suited angle, furthermore, the effects of pitch angle and azimuth angle on single blade were investigated. The results will provide theoretical supports on study of variable pitch of wind turbine.

Abstract: The 5-aix machining postprocessor of non-orthogonal machine tool is difficult to develop. On the analysis of characteristics of non-orthogonal machining center with dual worktables and 5-axis milling programming, a postprocessing algorithm of 5-axis milling is presented. Based on the algorithm, a postprocessor is developed by Visual C++ to convert tool path file to G-code file. For tentative validation of the postprocessor, a simulation model of the machine is established by Ver-icut to simulate G-code files created by the program. Finally a test workpiece is machined, which confirms the validity of the postprocessor.

Abstract: Because of the liquid phase’s driving action, particles would be collided the surface and impacted with each other in the flow passage, the surface will be machined though the continuous action of impact force and friction force. The finishing results of structural surface is related to the collision frequency and the pressure, abrasion situation in different area of the structural surface can be analyzed obviously by investigating dynamic characteristic and distribution of particle group. Based on coupled wave theory of liquid-solid two phases flow, using mixture model which belongs to Euler-Euler multiphase flow model and realizable turbulence model, turbulence effects of liquid-solid two-phase flow in the wall is numerical simulated and some parameters such as turbulent velocity and turbulent energy are calculated with different particles concentration in the flow passage which has V-shaped texture and semicircular cross-section. The simulation results show that the disorder degree of turbulence can be improved by assembling V-shaped constrained component, because V-shaped passage is benefit of eddy current’s generation. As the concentration of particles being enhanced, the velocity of particle would be increased in a certain range, turbulence energy reduces gradually, fluctuation margin of particle volume fraction is smaller and smaller, and curves of every kind of parameters change as continuous oscillation, area of surface corresponded with crest of the curve. The concentration of particles should be selected properly and different particles distribution and finishing performance would be obtained with different particles concentration.

Abstract: Dynamic modelling method for disc indexing cam mechanism was presented based on virtual prototype technology according to the analysis of mechanism feature. Rigid-flexible coupled dynamic model was established by means of Adams, Pro/E and Ansys softwares. Dynamic simulation has been done. It follows the analysis of simulation that effects of input speed, and stroke angle to torsional vibration were illustrated corresponding to dynamics simulation. Dynamic characteristics of different transmission functions commonly used in practical engineering were analyzed in detail. The application principle of transmission functions was presented based on dynamic simulation and analysis results. Construction method of transmission function was presented finally.

Abstract: Coordinate polishing technology with abrasive tap is targeted for crankshaft, camshaft, eccentric shaft and other complex surface polishing. In the process of coordinate polishing crankshaft crankpin with abrasive tap, the constant removal rate is to ensure accuracy rate of removal, which is very important factor. This article is to mainly analyze constant rate of removal. First, analyzing the movement model of a single abrasive and on the exact model and the constant speed along under the conditions of uniform rotation of the crankshaft still grinding the neck of a diagram analysis, we found that controlling the abrasive in constant linear speed and constant pressure under the crankpin can achieve constant rate of removal. Then, when the abrasive is moving with constant speed under the crankpin, we analyses on the laws of crankshaft rotation and institutions movement, and simulates the equation of motion, Those curves are no mutations and to meet the engineering requirements. Finally, in order to ensure coordinate polishing crankshaft crankpin with abrasive tap with the polishing block clamping force, that is constant pressure grounding, so coordinate institutions must be analyzed counter weight. Those curves are no mutations and to meet the engineering requirements.

Abstract: This paper summarizes the research progress of integral end milling cutter and series of common theories and methods: the construction in the reasoning machine of end milling cutter structure parameters, obtained structure parameter according to the type and the main design parameters of end milling cutter; General the mathematical model and the geometric modeling method of end milling cutter ,based on structure parameters that get from reasoning machine, get 3D parametric model which include all structure information and manufacturing characteristic of end milling cutter; the design technology of end milling cutter Based on manufacturing simulation, check the tool-position trajectory quickly by 2D curved shapes from 2D section Boolean operation, then validate the process rationality and manufacturability of end milling cutter via combine the 2D section simulation technology and the 3D manufacturing simulation. Present some research results finally, the detailed studies details will report in the subsequent articles.