Papers by Author: Ming Sheng Jin

Abstract: Damping in built-up structures is often caused by energy dissipation or energy loss due to micro-slip along frictional interfaces interaction, which provides a beneficial damping mechanism and plays an important role in the dynamics vibration behavior of such structures, especially the contact stiffness and damping coefficient accounting for the kinematics joint. A detailed study the mechanics derived from the interaction interface between the different components has some embarrassment. And a careful study on the micro-slip phenomenon has been carried out using the finite element method. A classical joint configuration, the plane translation joint, has been used as the model problems. The focus of this paper is to evaluate the effect of dry friction coefficient, the external mechanics on the damping response of frictional joint interfaces interaction, to understand the evolution of the slip-stick regions along a joint interface during loading, and to quantify the amount of energy dissipation/loss during cyclic loading and its dependence on structural and loading parameters.

Abstract: This paper focuses on the dynamics characteristic difference on the two kinds of broading machine, the workpiece moving and the cutting-tool moving. There is 0.002mm thickness of oil-film clearance between the mobile and immobile components of the broading machine. Hydraulic pressure derived from the driving oil cylinder drives the workpiece or cutting-tool moving, while the material on the workpiece is cutting. Cutting-tool of the machine is an external expand cutter with the groove for breaking the cutting waste, the manufacturing phase is a pulse impact cutting exciting applying on the broading machine correspondingly. On manufacturing, natural characteristic of the broading machine is approximately the pulse impulsion frequency of the machine;response amplitude of the lather is increasing manifesting. The study is focused on the dynamics characteristic of two kinds of broading machine, the difference is workpiece or cutter moving, to predict the manufacturing performance.

Abstract: Nowadays, researches concerned magnetic abrasive finishing (MAF) are becoming increasingly popular. Polishing head is one of the most important factors in the whole polishing system in which magnetic abrasive act directly on the workpiece. In this paper, two kinds of polishing heads applied in the polishing of free form surface are proposed. They are hard polishing head and soft polishing head, respectively. And some important factors are contrasted such as selfsharpening capacity, morphology distribution, and removal uniformity. Moreover, the finishing force is the key factor which is different between the two polishing heads having a great influence on polishing effect. Through comparison and analysis, the soft polishing head is better to finish free form surface. And the experimental results reflect its superiority in polishing free form surface.

Abstract: Application of magnetic abrasive to the field of finishing processes is increasingly popular and important. Magnetic abrasive finishing (MAF) is effective in precision machining of non-planar workpieces. To study the control of working abrasive morphology and the valid way to solve “incline effect” which is common in some industrial field, application of magnetic abrasive in gasbag polishing is presented. Besides, the polishing system is introduced, and the important factors which influence the magnetic abrasive polishing are studied. Then some tentative experiments are carried out to study its polishing effect. It is found that the difference of surface roughness value and material removal rate under different bevel angle is in small range, which indicates this approach is useful in solving “incline effect”. The work in this paper is also a good attempt for further study that polish precipitous surface of mould or other products.

Abstract: Magnetorheological flexible gasbag polishing based on the special application of magnetorheological fluid (MRF) in robotic gasbag polishing technique is a novel efficient approach in the field of mould finishing. It can control the polishing pressure by changing the magnetic force generated by MRF inside of the gasbag with the effect of variable magnetic field of electromagnetic coil. Its mathematical model is established to study the main factors influencing the material removal. The orthogonal tests are applied to analyze these important parameters. From the experimental results, it can be seen that this new approach is desirable in realizing the control of surface figure accuracy and improvement of surface quality under certain condition.

Abstract: To improve the quality and efficiency of the finish, industrial robots are used to polish the workpiece cavities with complex shapes. This paper presents key technologies of robotic polishing system including path generation, tool orientation control and G-code converting. Robot path data is generated automatically from the NC data, and tool posture angle is superadded to the robotic polishing path according to the requirement of the robotic polishing technology. Specialized software is developed to automatically generate a program, which includes the path data and tool posture angle, and this program is uploaded to the robot controller for the die polishing process.

Abstract: Gasbag polishing is an automatic, flexible, controllable and practical technique, which has wide application prospect. A pulse technique based on robotic gasbag polishing system is proposed. Its main principle is to use the Pulse Width Modulation (PWM) technique to control the switching time of High-speed Solenoid Valve (HSV). It can not only control the internal pressure of gasbag, but also make the rubber gasbag present pulsation with PWM technique. Moreover, the performance of pulse technique is presented and the effects of different frequency pulse pressure on the polished surface roughness are analyzed through a series of experiments. At last, experimental results show that the pulse technique can improve the polished surface roughness more rapidly in certain extent with appropriate pulse frequency and process parameters comparing with conventional gasbag polishing way.

Abstract: Combining the advantages of rheological behavior of magnetorheological fluid (MRF) and flexibility adjustability of rubber gasbag, a magnetorheological flexible gasbag polishing technique applied to free-form mould is proposed. With the development of robotic gasbag polishing technique, the flexibility of rubber gasbag can be adjusted by three methods of changing its internal pressure controlled through a pressure control unit, its own material property and structural parameter, and the rheological behavior of MRF inside of it in response to the application of an alterable magnetic field. Effect of rheological behavior to the flexibility of rubber gasbag and surface quality of mould is the single most important focus in this paper. The magnetorheological flexible gasbag polishing system is established and rheological behavior of MRF with magnetic field is described. Through polishing experiment focusing on the relationship between the surface roughness and current around electromagnetic coil, it can be obtained that magnetorheological flexible gasbag polishing technique is effective to improve surface quality when increasing current around coil in certain extent.

Abstract: The paper discusses the near wall region of soft abrasive particle flow in weak force finish machining method. Turbulent flow morphology in near wall region of rectangular channel with different viscosity is numerically simulated and compared. Through the analysis of kinetic equation of abrasive particle, the abrasive particle motion trace of different diameter in turbulent flow with different viscosity is simulated and compared. The result reveals the condition under which the fluids with different viscosity can form Turbulent flow is different. The greater the viscosity is, the greater the velocity needed is. Also the quantitative relation of velocity and flow volume is available to determine the pump parameter in abrasive particle flow machining. Fluid at wall has pressure and shear stress on work piece. The greater the viscosity and velocity is, the greater the wall pressure and shear stress is. So it is helpful to make material removal on work piece surface. But the greater the viscosity is, the greater the velocity attenuation of abrasive particle is. Abrasive particle mainly move along the flow direction with the movement of fluid. The velocity attenuation of larger diameter abrasive particle is much than the smaller particle but the latter can maintain greater velocity in a longer distance favorable for collision with the work piece surface salient.

Abstract: Static analysis plays an important role on the design and applications of manipulator. In this paper, The torque balance equations of the spherical 3-DOF manipulator was derived in closed forms by analyzing the relationship of its input and output torques, then the torque transmission evaluation index and the global torque transmission evaluation index were defined based on the torque balance equation and discussed in detail, at last, by using the physical model technique, the parameters of the spherical 3-DOF manipulator were optimized based upon the global torque transmission evaluation index. Moreover, an integrated design scheme of the spherical 3-DOF manipulator was confirmed when satisfied the assembly conditions, which can provide theoretical base for the applications of the spherical 3-DOF manipulator. The spherical 3-DOF manipulator can be used as the waist, wrist and the ultra-precision machine in which the requirements for high stiffness, high accuracy and good technological efficiency.