Papers by Keyword: Mechanical Vibration

Abstract: The preparation of a semi-solid slurry with fine and spherical solid particles dispersed in the liquid phase is a key technology for the semi-solid process. In this study, we have developed the slurry preparation method by applying mechanical vibration for JIS AC4CH (equivalent to A356 in the ASTM standard) and ADC12 (equivalent to A383 in the ASTM standard) aluminum alloys. In this method, the mechanical vibration was applied to the aluminum alloys during cooling from a liquid state to semi-solid state. The shape of the particle was varied by controlling vibration conditions. Therefore, we investigated the effect of conditions on mechanical vibrations. There are four parameters which are frequency, acceleration amplitude, velocity amplitude and displacement amplitude in the mechanical vibration. Among these parameters, the velocity amplitude had highest effects on the shape of solid particles. By properly controlling of the frequency and the velocity amplitude, the slurry with fine and spherical solid particles could be obtained. Moreover, the fraction solid of slurry could be controlled by varied initial liquid temperature. Especially, ADC12 aluminum alloy has low liquid-solid coexistence temperature range, so it is not considered to be suited for the semi-solid process. However, by using this mechanical vibration method, the semi-solid slurry could be obtained stably. This method is expected to be effective for the semi-solid high-pressure die-casting process.

Abstract: This Paper studied the precipitation behaviour and creep deformation of 2124 aluminum alloy based on the concept of complex field. A mechanical vibration field was introduced into the creep aging forming process of 2124 aluminum alloy, and its effects on creep deformation, precipitations behaviour and mechanical properties under the condition of double curvature loading and aging temperature were investigated by three-dimensional scanning technique, TEM and tensile test, respectively. The results showed that the spring back value along the rolling and transverse direction presented after creep aging forming were reduced by 25% and 15% respectively. The volume fraction of precipitates increased and distributed more densely and uniformly. Meanwhile, the yield stress improved by 15MPa and the degree of anisotropy decreased by 17% with mechanical vibration field applied to the manufacturing process.

Abstract: In order to solve the spindle vibration problem which is mainly caused by the mass unbalance, the single-plane influence coefficient balancing technique was applied into the experimental study. The unbalance elimination could be done through correction weight through before adding trial weight. The coefficient magnitude, the balance weight magnitude and other parameters could be available by extracting vibration signals and measuring vibration phases. The dynamic balance effect comparison has been done under different working rotations. Results indicate that the spindle mechanical vibration decreased by 87.04%, the balancing precision also improved a lot. Such achievements would surly hold an important meaning in reducing noise, improving the equipment service life and ensuring the safely working machine.The method provides regulation strategies for the online dynamic balancing control technique. Key words:single-plane influence coefficient balancing technique; regulation strategy; mechanical vibration

Abstract: This paper presents the results of experimental research of the authors in terms of overall vibration behavior MUSD (machine tool, tool-device) during processing by removing metal on a pump body on a CNC milling and boring machine. At the research conducted in this direction were considered mechanical vibration measurements occurred during the processing of various operations of the technological process in parallel with noise measurements. These experimental research in determining the direction of vibration occurring in machining process led to some conclusions about the interdependence between the intensity and quality cutting data processing carried out and the influence of noise pollution produced.

Abstract: In industries that work with particulate material is observed from among other concerns, not to discard solid material in the air. Aiming to develop gas-solid filtration equipment more efficient, the study of a self-cleaning system utilizing filter fabric made ​​from synthetic material, was conducted using the phosphate rock as particulate material. The objective of this study is to evaluate the performance of a vibratory system filtration of gases. The system is made up a box filter coupled to an eccentric motor which causes a continuous vibration during the filtration cycle, not being necessary to interrupt the process to the procedure of fabric filter cleaning. We used polyester synthetic filter for the tests. With known relative humidity and temperature at which the tests were performed, it was possible to estimate the performance of the equipment in continuous vibration filtration of pulverulent material dispersed in gas currents, under the influence of different vibration frequencies.

Abstract: The influences of different pulse voltage, pulse frequency, pouring temperature and mold temperature on solidified structure of Mg₉₇Y₂Cu₁ alloy reinforced by long-period ordered structure with compound treatment of pulsed magnetic field and mechanical vibration were studied. The results show that grains of the alloy can be refined greatly with compound treatment. Primary phase degrades from developed dendrites into rosette-shaped crystal. Distribution of second phase is more uniform and continuous, and its volume fraction increases. When the pulse voltage is at 0-280V or the pulse frequency is at 1-10Hz, grain size of the alloy decreases dramatically as pulse voltage or pulse frequency increases. When the pouring temperature is at 660-750°C or the mold temperature is at 20-600 ^oC, grain size of the alloy with compound treatment decreases grossly with the increase of the pouring temperature or the mold temperature.

Abstract: The treatment with mechanical vibrations during the solidification process promote microstructural changes in metallic alloys, in order to have a better understanding on this matter mechanical vibration were applied to an aluminum alloy A356, while teeming in order to evaluate the morphological changes on αAl primary phase in the solidification process. Two routes were analyzed, a cooling slope and a rotational mold. This paper shows the results of quantify the effect of mechanical vibration and the specific characteristic of casting to obtain a spherical morphology on the αAl primary, that allow to obtain thixoformable raw material.

Abstract: Vibration monitoring of machinery and equipment plays a very important role in judging the equipment maintenance and operational status. This paper discussed the mechanical vibration amplitude measurement system scheme based on PVDF piezoelectric sensors. The entire test system is mainly composed of PVDF piezoelectric film sensors, charge amplifiers, data acquisition and processing and display of valid values. It can display the amplitude of vibration signals in real time and alarm. The measurement system has the advantages of a simple structure and convenient operation.

Abstract: This paper introduces the empirical mode decomposition (EMD) method of the basic theory, problems and means to solve. Apply the approach to mechanical vibration signal containing a transient pulse processing and analysis carried out, and the wavelet time-frequency analysis methods are compared, the results show that it can effectively decompose nonlinear and non-stationary vibration signals, and has a self-adaptive, and in the time domain and frequency domain have better resolution capabilities, and the component with a more clear physical meaning. Due to its diversity of showing the results, you can make further precise analysis of a single component, and the transient signals can be effectively recognized, and can locate mutation point in time, describing the time-frequency localization properties. EMD, transient signals, mechanical vibration

Abstract: In recent years, the high speed railway vehicle dynamics performances have been studied and investigated in order to determine the ride comfort of the passengers. Most of the time, these researches were involving expensive and high end technology of data logging system to record and analyze the data. In this research, a low cost data logging system (Lego Mindstorms) is used to gather the data from accelerometer and gyro during experimentation. The study about the behaviour of railway vehicle in term of roll and vibrations at three perpendicular axes during running at the curve track is performed. Actual field run of railway vehicle data collection is performed on the available high speed railway vehicle operating from Kuala Lumpur International Airport (KLIA) to the Kuala Lumpur (KL) Sentral. The route selected consists of several curves which are important to study the dynamics performance of the vehicle. The results from experiment establishes the dynamics performances of the railway vehicle in term of passengers ride comfort. With the availability of the data logging system and sensors, the railway vehicle dynamics performance can be analyzed and monitored for future improvement of railway vehicle service and operation.