Frictional Effect on Ultrasonic-vibration Forming of Aluminum Alloy

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題名:	Frictional Effect on Ultrasonic-vibration Forming of Aluminum Alloy
作者:	洪榮崇
貢獻者:	機械工程(學)系
日期:	2012-09
上傳時間:	2017-12-19 09:23:23 (UTC+8)
摘要:	The frictional effect of ultrasonic vibration was investigated during the forming of aluminium alloy. This study analyzed the procedures of ultrasonic-vibration drawing and ultrasonic-vibration upsetting, which are two extreme cases at relative speed of die and workpiece. The effect of relative speed was explored based on the finite element analysis of the convention drawing (CD), axial ultrasonicvibration drawing (AUD) and radial ultrasonic-vibration drawing (RUD). For both AUD and RUD, the drawing force fluctuated with die vibration when the drawing speed was below its critical value, and the amplitude of fluctuation increased when the drawing speed decreased. The frictional effect of ultrasonic vibration disappeared when the drawing speed reached its critical value. Therefore, the frictional effect of ultrasonic vibration was considered insignificant when the drawing speed approached its critical value. In general, the critical drawing speed of RUD was higher than AUD. In addition, this study superimposed an ultrasonic vibration parallel to the direction of forming to explore the frictional effect on ultrasonic-vibration upsetting. Two tests in differing compressed methods were performed, as follows: the extrapolated compression test (EC) and the hot ring compression test (HRC). The results from EC revealed that ultrasonic vibration can reduce the compressive force without frictional force. Conversely, the results from HRC indicated that the temperature increase by ultrasonic vibration may reduce the flow stress and enlarge the interfacial friction. Therefore, in ultrasonic-vibration forming processes, the frictional effect is highly related to the variation of interfacial gap and the temperature. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. (9 refs)
關聯:	Steel Research International
顯示於類別:	[機械工程系(所)] 【機械工程系】期刊論文

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