Key Engineering Materials Vol. 572

Abstract: In order to study the effect of oil-air lubrication on traditional sliding bearing, the experiments oil-air lubrication and oil lubrication have been done by using friction-abrasion testing machine. By means of measuring friction moment, the temperature rise of two different lubrication systems in the same conditions and studying the friction moment and the temperature rise of oil-air lubrication and oil lubrication with different load at the same rotating speed level, the results obtained show that when rotating speed and oil supply is at 210rpm and 1.4L/h level, the friction moment of traditional sliding bearing with oil lubrication increases significantly after the load 900N, and when rotating speed, oil supply and air pressure is at 210rpm , 30ml/h and 0.25MPa level, the friction moment of traditional sliding bearing with oil-air lubrication increases significantly after the load 1500N. The friction moment of oil-air lubrication and oil lubrication is almost the same before the load 900N, and after the load 900N, the friction moment of oil-air lubrication is much lower than the oil lubrication. The oil-air lubrication temperature rise is much lower than the oil lubrication in traditional sliding bearing with the same experimental conditions.

Abstract: The influence of the oil supply, nozzle type, air supply, the performance of sliding friction element under the lubrication preloads were investigated by measuring the element’s temperature and friction coefficient based on the M2000-A friction wear testing machine. When the load, rotating speed and air supply is at 1500N, 210rpm and 2.25 m3/h level respectively, as the oil supply is increased, the temperature rises and friction coefficient decreases. The temperature rise decreases monotonically. The friction coefficient rises monotonically with the air supply increases when the air supply is less than 2.4m³/h, but when the air supply is more than 2.4m³/h, the friction coefficient decreases monotonically. Furthermore, when the oil supply is reached 15ml/h, they remain almost unchanged regardless of direct nozzle and conical nozzle. Nevertheless, the direct nozzle is more suitable than the conical nozzle in oil-air lubrication of the sliding friction pairs .

Abstract: The characteristic of cyclical impact is reflected on the signal of rolling bearing in fault condition. The carrier frequency is modulated by times of the failure frequencies. When the traditional cyclical spectrum density (CSD) method is used to analyze the signal, all the modulation frequencies will be demodulated in the cyclic frequency spectrum. In this case, it is difficult to recognize the fault type of the bearing. Therefore, a new cyclical spectrum density method based on the kurtosis energy (CSDK) is proposed. The kurtosis of every cyclic frequency’s slice is used as the weight coefficient of the cyclic frequency’s energy accumulation to extract fault feature effectively. The proposed method has greatly reduced times of the harmonic frequencies’ effect in traditional CSD method. The analysis of the signal gathered from the outer rolling bearing of blast furnace belt cylinder shows that the fault feature extracted by the new method is more clear and accurate than CSD method.

Abstract: Adaptive-mechanical CVT differs from existing CVT by absence of the hydraulic converter. The transfer mechanism contains the toothed wheels closed contour which provides definability of motion at presence only one entry. Such transfer possesses effect of power adaptation. Change of a moment of resistance leads to change of target angular speed. Dynamics problem consists in definition of parameters of transition from one power regime to another. The work purpose consists in definition of dynamic parameters adaptive-mechanical CVT and in definition of parameters of transition from start power regime to operation regime.

Abstract: This paper examines wide V-belt operational behaviour operated continuously variable transmission (CVT). Important for the prediction of an optimum driving performance it is necessary to understand the motion principle of the belt in the pulley during operation. First, the design of a test rig is described, where both the driving and driven pulleys are programmable controlled, giving details of the capabilities. Second, to describe the efficiency of the drive, losses due to slip and the mechanical properties of belt material are determined. To conduct the mechanical properties of the steel-reinforced belt an experimental method is introduced. Finally, emphasis is placed on determination of circumferential motion of the belt due to various drive operating parameters. Through the study, it is found that mechanical wear at both sides of the V-belt caused by the belt’s motion is the most serious problem that affects the CVT performance.

Abstract: This article presents the main aspects of modeling, design and development of a manipulator type parallelogram 3-DOF for the control of path tracking with open architecture, this model allow easy maintenance and program modification. The design and manufacturing tasks was aided by CAD/CAE/CAM technology. The assembly and commissioning was carried out by the integration of the mechanical and electronic components. The integration and evaluation of the control algorithms during the prototype manipulation was obtained by the kinematic and dynamics models and Lagrange equations of motion. Finally, results of monitoring control paths are present through testing in the joint and cartesian spaces, the results showed the optimum performance of the manipulator under different parameters of control.

Abstract: In this paper, the vibration modeling and analysis of Stewart platform-based machine tool is presented. The vibration modeling includes the derivation of the vibration equation and the detailed processes to deal with that. Each of the kinematic chains is considered as a flexible chain and simplified into a spring-damper submodel. Vibration modeling of the machine tool is established by Newton-Euler approach. Then, the natural frequencies of the moving platform are obtained based on the vibration equation by the aid of MATLAB. The vibration characteristics of the machine tool are analyzed and discussed by means of the numerical examples considering the different poses of the moving platform. The conclusion can be drawn that the natural frequencies of the platform are influenced by the poses of the platform.

Abstract: A novel 5-DOF parallel mechanism applied to active vibration isolation is proposed in this paper. And by using Newton-Euler approach we set up models of the kinematics and dynamics of the isolator. Besides, a wide-range giant magnetostrictive actuator (GMA) composed of a GMA and a micro-displacement amplification mechanism is designed for the actuation of the isolator. Finally modal analysis of this isolator is carried out in ANSYS software to testify that the parallel mechanism is suitable for active vibration isolation.

Abstract: This paper presents a deployable modularized truss mechanism which can have different number of module units. Some necessary analysis for mechanism design will be done such as mechanism analysis, kinematic, dynamic and thermodynamic analysis. For the purpose of gaining the fundamental frequency maximum and the minimum of structural weight, some optimizations are carried out. In order to simplify the design process of the mechanisms, a simulation-design platform is developed, which has the function of analysis, simulation and optimization about mechanisms.

Abstract: A vertical-axis tidal turbine was designed in the paper. Modal analysis of the vertical-axis tidal turbine was investigated based finite element software analysis method. Finite element simulation model for modal analysis of the accelerator and the whole tidal turbine were built by appropriate structure simplification. And, the anterior 10 ranks of natural frequencies and corresponding mode shapes were calculated. Modal analysis results show that the natural frequency of the turbine away from the frequencies of tidal current incentive, impeller incentive and generator rotor incentive, so the resonance phenomenon does not exist in the turbine of the paper. Also, the modal analysis results show that the input of the accelerator and leaves of impeller have a large deformation, and the stiffness of the input shaft and spokes and leaves of impeller should be increased.