| Abstract:Ultrasound effect caused by power ultrasonic has special acoustic characteristics which can change the properties of physics^chemistry、biology of substances. Treating aluminum melt with power ultrasonic can improve physical and chemical properties of metals obviously. It is the international research hotspot nowadays and a new developing direction of technology of aluminum alloy casting. Taking the7XXX aluminum alloy ultrasonic casting as research object, the main study of the paper was done as follows:1. Combined with the characteristic of the casting, the longitudinal oscillation equation of ultrasonic horn with random variable cross-section was discussed. The physical and mathematical models were established. Based on the design theory, by choosing appropriate material, the main structure sizes of ultrasonic vibration system of25kHz, which including transducer, front and back cover, horn and tool rod were designed.2. The finite element model of new ultrasonic vibration system was performed by using finite element analysis software ANSYS. The main performance parameters of the system, which including the longitudinal resonant frequency and the amplitude of the displacement of the ultrasonic vibration system, was calculated by modal analysis, which proves the resemblance with the experimental results and simulation results.3.7xxx aluminum was treated with ultrasonic vibrations of25kHz and20kHz respectively by dipping the acoustic radiator into melt Experimental results show that the microstructure with fine uniform non-dendrite grain was achieved with ultrasonic vibration of both systems. By compared with the experiment result, the effect of20KHz is better than that of25KHz under the same condition. |
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