Papers by Keyword: Alternating Magnetic Field

Abstract: In previous studies, it has been verified that the magnetic abrasive finishing process using alternating magnetic field can achieve higher finishing efficiency and surface quality, and nanolevel finishing of 5052 aluminum alloy material and SUS304 stainless steel material has been realized. In this study, the feasibility for ultra-precision finishing of polychlorotrifluoroethylene resin by this process was investigated, and the cutting mechanism of particles was discussed. As a result, the cutting depth of the particles is mainly affected by the size of the magnetic particles and abrasive particles. According to the experimental results, under optimized experimental conditions, the surface roughness of the workpiece can be improved from 112.83 nm Ra to 5 nm Ra within 15 minutes.

Abstract: To further improve the finishing efficiency, it has been proposed to apply full-wave rectified current to the coil. In this paper, the effect of full-wave rectified current on the magnetic field and finishing force is studied. The effects of full-wave rectified current and alternating current on finishing characteristics were compared through experiments. The experimental results show that, with different magnetic particle sizes, the finishing efficiency shows different results. In the case of full-wave rectified current, when the average diameter of the magnetic particles is 30 μm, 75 μm and 149 μm, the finishing efficiency is higher than the alternating current, and when the average diameter of the magnetic particles is 330 μm, the finishing efficiency is lower than the alternating current.

Abstract: Composites and dynamic materials that include conductive components are becoming a suitable choice in different applications. The eddy currents are generated when the conductive components are placed in alternating magnetic field. The eddy currents decrease the primary field and this effect has been well studied and it is used for electromagnetic shielding. Besides, the magnetic field increases in small space near edges of the conductive components. While this effect of magnetic field strengthening is known, it is rarely examined. We will introduce a simple model that can be appropriate for the conductive components in form of long thin sheets. We analytically analyze the model and obtain expressions that give upper bounds for increasing of the net magnetic field. The electromagnetic effect of strengthening should be taken into account when considering an application of the composites. The results are useful for electromagnetic compatibility analysis, non-destructive testing and monitoring of composite and dynamic materials with conductive components.

Abstract: In this paper, we present results of theoretical modeling of the rise of temperature for the unit of time in a dilute suspension of the fiber ferromagnetic particles under the action of the linearly polarized oscillating magnetic field. Two mechanisms of the heat production, namely the particle rotation in the liquid and its internal remagnetization are considered. We study effect of the particle shape, its magnetic properties and rheological properties of the carrier liquid on the rise of temperature for the unit of time by the particles.

Abstract: It is a fact that at present the focus in the area of new energy-saving electrotechnologies for heating of non-ferrous metal products is on induction heating in transverse magnetic field, but a large range of products with rectangular cross-section made of non-ferrous metals is not treated by heating method in a transverse magnetic field. Currently such products are heated in the induction heating installations in alternating longitudinal magnetic field though their electrical efficiency is not greater than 0.5. Attractiveness of heating of such products in the transverse rotating magnetic field of permanent magnets is in ist potential to achieve electrical efficiency equal to 0.75-0.85. The study of heating aluminum products with rectangular and cylindrical cross-sections to a temperature of 550 ° C is done and described.

Abstract: The austenite steel after rolling was radiated by the alternating magnetism, and the effects that alternating magnetic on the austenite transition was studied. The result shows that the alternating magnetism promotes the austenitic grain growth of low carbon steel. If the magnetic field intensity is increased, it could provide better performance of raw materials to cold rolling processing.

Abstract: Alternating current field Measurement is one of the important progresses about electromagnetic nondestructive testing in recent years. Alternating magnetic fields excitation testing model is established by using electromagnetic simulation software ANSOFT, a flat plate crack defects are simulated. By analyzing its principle, crack depth and the width change influence on test results, finally the simulation results are verified by the method of experiment. The experimental results are consistent with the simulation results. The results show that this differential probe has good effect on crack defects test.

Abstract: By analyzing the pattern and law which alternating magnetic field signals affect, the relations of alternating magnetic field signals and flaws were obtained. These relations illustrated alternating magnetic field technology s method and way. Some analysis was done after making contrast test samples. These analysis confirm that alternating magnetic field method can quickly find locations of defects during detection of blade part. It may raise efficiency and ensure equipments safely run.

Abstract: In this paper, a new plane magnetic abrasive finishing process by using alternating magnetic field is proposed to improve the efficiency and surface precision. In alternating magnetic field, the forced direction of magnetic particles is changing. Therefore, magnetic particles could produce the up and down movement, which promote the scatter of magnetic particles , improve the roll of abrasive particles and enhance the utilization of abrasive. In order to know well the magnetic intensity distribution in processing area, measured the magnetic flux density. Finishing force is important to understand the mechanism of material removal, investigated to the finishing force and contrasted to the movement changes of magnetic particles in water-soluble finishing fluid and oily finishing fluid. A set of experimental devices have been designed to realize surface polishing on C2801 brass plate, the results proved the feasibility of this method, which can improve the workpiece surface quality.

Abstract: The dynamic behavior of a magnetic fluid droplet adsorbed to magnetized needlepoint in alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field were parallel and opposite to static magnetic field of magnetized needlepoint. It was found that the surface of magnetic fluid droplet responds to the external magnetic field in elongation and contraction. The frequency of magnetic fluid droplet oscillation was exactly same of the external magnetic field. The shape and instability oscillations of the magnetic fluid droplet were revealed experimentally.