Key Engineering Materials Vol. 584

Abstract: Pneumatic splice makes use of high-speed compressed air as the driving force to complete the yarn splicing, noticing that the change of the vent pressure has a significant effect on yarn splicing. This paper studies the impact of vent pressure on the quality of yarn splicing when twisting and untwisting. Modeling, analysis and simulation of the air splice is done with the integration of Pro/E and ANSYS software, to study the flow filed and obtain the influence on the speed and pressure of the inside the splicing chamber when changing the speed and pressure while keeping the diameter of splicing chamber diameter, the vent hole diameter and the relative angle are unchanged. The results of the analysis of the air splice will lay a solid foundation for the further optimized structure design.

Abstract: Discussing the technology of small holes processing and the development of the combined ultrasonic and electrochemical machining, the technology of combined ultrasonic and electrochemical Machining was studied and its device was designed. By the preliminary tests, the impacts of various factors on the processing of small holes by combined ultrasonic and electrochemical machining were analyzed and some problems were found, which provided a basis for the future research.

Abstract: A device was designed to study the small holes by the rotary combined ultrasonic and electrochemical machining, and the gap between cathode and anode in the processing was also analyzed. A three-dimensional model of flow field was developed in ANSYS CFX software based on FEM by the gas-liquid two-phase fluid cavitations model as well as the effect of rotary cathode and the vibrated cathode to the flow field was analyzed. The simulation showed that the pressure and the velocity of the electrolyte in the gap were oscillated by additional motion of cathode, which is helpful to the electrochemical machining. The comparison of rotary electrochemical machining and the rotary combined ultrasonic and electrochemical machining showed that the rotary combined ultrasonic and electrochemical machining has better ability of making small holes than that of rotary electrochemical machining

Abstract: The content of magnesium in various parts of a nodular iron casting is measured by using spectrum analyzer. The results show that the skin of castings has an enrichment of magnesium, and the inner has a gradient distribution of magnesium, not an average distribution. Discussions on the results indicate that bubbles in the liquid metal would not move upward under the action of buoyancy, but migrate toward all directions and the bubble stranded below the surface of the liquid metal form blowholes, because these bubbles can not migrate with the obstruction of oxide films and dendrites. The results of production practices show that increasing carbon equivalent in the liquid metal is helpful to avoid blowhole defects.

Abstract: To improve the mechanical properties of the EDM electrode material, the electroforming process for fabricating copper-nanozirconia (ZrO₂) particles composite aided by ultrasonic has been presented. In this research, some vital process parameters such as concentration of ZrO₂, rotational speed and ultrasonic frequency have been evaluated. Two inspection criteria, content of ZrO₂ and micro hardness of deposited layer were employed to evaluate the fabrication quality of copper-nanozirconia (ZrO₂) composite material. The experimental results indicate that nanocomposites grains electroformed aided by ultrasonic are refined. Their organizations are more uniform and dense, the surface is flatter and the microhardness of nanocomposites is significantly improved.

Abstract: Heat treatment equipment are usually harmful to people, they need to be monitored remotely. As the fact that different types of equipment are used in factories, which leads to the problem that monitoring equipment is difficult. Therefore, research on remote centralized temperature monitoring system is necessary. The concept of isomeric equipment is proposed. The framework of monitoring system is established, which is constituted of temperature control instruments, monitoring server and clients. The functions of monitoring system are described, such as setting temperature, receiving temperature, showing the chart of temperature, accumulating and reusing heat treatment experience etc. The key technologies of monitoring system including dynamic protocol adapter and knowledge accumulation and reuse are also explained. Finally, the system is applied in a factory. The engineer can monitor almost all of the heat treatment equipment only by use the system in the office.

Abstract: This paper advances a new method, double phase differences correction method, which aims at correcting the errors of frequency, phase and amplitude of the harmonic signal. The employment of this method involves that two phase differences of two highest spectral lines in the main lob are used to get the correcting value of frequency and then phase and amplitude can be rectified by corresponding formula. It solves the problem that the traditional formula of translation of window center is only for rectangle window. This new formula can correct for the different window by the principle of translation of window center. Simulation shows that the maximum error of frequency of the signal with white noise is less than 1% of frequency resolution. The maximum error of phase is around 1.5º, and the maximum error of amplitude is within 0.01. The average errors in frequency, phase and amplitude are approximately 0.002Hz, 1º and 0.005, respectively.

Abstract: In 2007, a new hybrid electric vehicle was released by General Motor, which is called as Two-mode hybrid electric vehicle. The two-mode hybrid car is famous for its hybrid transmission, which contains two electric motors/generators, three planetary gear sets and four controlled clutches, and allows six different operation modes: two electrically variable transmission modes and four fixed-gear modes [. This paper analyzes the operating condition of the electric machines (Motors/generators) in each mode. And then, it presents three mode selection strategies in order to make a comparison of them.

Abstract: ntermittent fault under extreme vibration environment is an important cause to affect the function of mechatronics system. A new intermittent fault diagnostic technique based on EMD and neural network methods is proposed in this paper. Firstly, the essential characteristics of intermittent fault under extreme vibration environment are summarized. Then in view of the extreme vibration analysis of electromechanical systems, a new intermittent fault diagnostic technique is put forward by combining EMD and neural network approach. Lastly, the technique is verified by conducting in the heading attitude system of helicopter.

Abstract: Large systems have complex structures and functions, which makes it more difficult in fault isolation. Given the design features of BITs (built-in test) of large complex systems, a method, based on the diagnostic tree and Bayesian network, has been proposed for fault diagnosis and isolation of System-level BITs. First, faults are rapidly isolated in accordance with the diagnostic tree as well as the information of periodic BITs and maintenance BITs. Then, a diagnostic method based on the Bayesian network has been put forward to solve the problems of ambiguity groups of three LRUs or more and to accomplish further diagnosis and isolation. Finally, a certain subsystem of radar has been exemplified to verify the effectiveness of the method proposed by this study.