Applied Mechanics and Materials Vols. 446-447

Abstract: This paper introduces a stamping die design of a kind of textile machine needle. According to the size,material and mass production requirements of needle, the blanking technological property of parts are analyzed, and its general principles, methods and steps of die design are introduced. The structure of stamping die is gap-frame press, and JB23-25 is selected to do the work. The dimensions of cutting edge and dimensional tolerance are calculated. Finally designing components, checking stamping equipment and drawing assembly diagram are finished. This stamping die is mainly composed by punch die and concave die, positioning parts, discharge unit, die set, stamping machine and fasteners.

Abstract: Box-Wrench is a tool widely used in industry and especially suitable for screwing the bolt and the nut in the place where the space is very narrow and dent. In this paper, a process of hot extrusion box-wrench was presented. The structure of hot extrusion die and its working process were discussed. The feasibility of the process and the workability of the die were analyzed with Finite Element Analysis. The external diameter and the length of the box-wrench are designed according to the equipment's shape and size, the box-wrench's structure should be relatively flexible. How to manufacture the box-wrench in high efficiency and with high quality is the most important question of the box-wrench producing.

Abstract: Homemade Friction Stir Welding (FSW) Tool utilizing conventional milling machine has been developed. The FSW tool made from mild steel was designed and fabricated. Experimental investigation of FSW process of the Aluminum alloy specimens to observe its mechanical performances was performed. To evaluate its performance, hardness test, tensile test as well as visual inspections of the welding result were performed. Hardness number in the welding region was measured about 40-60% lower than the base metal, and heat affected zone region. The tensile test result varies with maximum 100 MPa. The imperfection of final form of metal due to the stirring mechanism was inspected. The presence of void/crack at cross-section of the welded specimen was observed. It was found that by applying suitable configuration, the use of mild steel as the FSW tool was reasonable for performing FSW process. It was concluded that, using a relatively low cost FSW tool, a quite satisfactory result of welding performance was achieved.

Abstract: Oil-immersed transformer is the use of transformer oil as an insulating and cooling medium. The gas relay protects the transformer by detecting the methane,and plays a crucial role in the safe operation of the power system. Verify gas relay system has these advantages: automatic test, easily operation, and the calibration precision is high. This paper introduces the design of the gas relay verificaton system based on STM32F107 chip. The mechanical principle, the hardware and software flow chart are described also.As a demonstration, we show the test results using this system.

Abstract: The traction motor installed on the high-speed train is powered by inverter. A large number of harmonics may appear when motor is operating. Then the motor speed generate oscillation and finally the dynamic characteristic is affected in vehicle system. In this paper, relied on the electromagnetism of traction motor, the mechanism about emerging harmonic torque is analyzed. In addition, based on the equivalent circuit, the method of calculating the parameters in harmonic circuit is proposed. Two mathematical formulas are also proposed to obtain the fundamental electromagnetic torque and the harmonic electromagnetic torque on traction motor. The time domain and frequency domain distributions of the torques are gained and analyzed. Finally a calculation example of traction motor harmonic torque was analyzed and calculated, and prepared for further study of harmonic torque impacting on vehicle system dynamic performance.

Abstract: With main transmission system structural form of main servo motor-worm and worm gear commutation reducer-transmission screw-linkage force increasing mechanism, mathematical model of linkage force increasing mechanism is established to obtain the relationships of the velocity and displacement between nut and slide. Velocity and displacement of feature points of slide on the velocity-displacement curve inputted by user transform into which of nut by binary search algorithm and linear interpolation calculation. The feature points of nut transform into the velocity and displacement arrays of points based on S-curve, and then the arrays of points transfer through UDP protocol to lower computer. After the linear fine interpolation by Siemens Simotion D425 motion controller, slide moves according to the setting velocity-displacement curve. The experimental results show that slide moves smoothly, which meets specific technology requirements. The achievements have been successfully applied to a self-developed 2000KN mechanical linkage servo press in a production line of hot forming technology for more than one year, which extends the technology application scope of traditional mechanical press, and improves product quality.

Abstract: This paper investigates the performance enhancement of a newly designed stack ultrasonic motor by using PZNPT material. Based on the numerical simulations, it is concluded that PZNPT can greatly improve the mechanical performance of the motor.

Abstract: This paper is concerned with the decentralized sliding window Kalman filter for multisensor discrete-time dynamic linear systems having different sensor memories. The proposed filtering is presented that combines the Kalman filter and sliding window strategy. A decentralized fusion with the weighted sum structure is applied to the local sliding window Kalman filters (LSWKFs) having different sensor memory size. The proposed decentralized algorithm has a parallel structure and allows parallel processing of observations, thereby it more reliable than the centralized version if some sensors become faulty. Moreover, the choice of sliding window strategy makes the proposed algorithm robust against dynamic model uncertainties. The derivation of the error cross-covariances between the LSWKFs is the key idea of this paper. The application of the proposed decentralized filer to linear discrete-time dynamic systems within a multisensor environment demonstrates its high accuracy and computational efficiency.

Abstract: In this paper, a new nonintrusive efficiency estimation method without using stray loss approximation value was presented, the efficiency of induction motor was computed using estimated value of speed and load torque by AEKF. In AEKF, the speed and load torque as the state of system are estimated, the noise covariance matrices are estimated adaptively while the state of induction motor system are estimated to overcome the defect that estimation results are affected by the selected noise covariance matrices in EKF, then the estimated speed and the load torque are used to achieve noninvasive efficiency estimation. Experimental results demonstrate that the efficiency estimation results of this method has higher accuracy and are not affected by initial value of noises covariance matrices.

Abstract: This paper focuses on developing an optimal system of Vertical Axis Wind Turbine (VAWT) for low wind speed. After studying the performance analysis of the turbine parameters for speeds less than 5 m/s, a realistic model was designed in Matlab/ Simulink that could produce suitable torque for low wind condition. The Multi-pole Axial Flux Permanent Magnet Synchronous Generator (PMSG) had been proven to be a good choice for this optimal design as it performed well enough to generate sufficient amount of voltage and power. The turbine design parameters such as the radius, height and wind speed were varied to observe the change in generator output voltage and power and based on that an optimal design for Permanent Magnet Synchronous Generator was proposed in this paper. The simulation results were tested with an actual Permanent Magnet Synchronous Generator in laboratory applying the optimized turbine parameters and were compared accordingly for error calculation. Lastly, future possibility of improvement and the limitations had been proposed to develop the system further.