超声振动对板材固体颗粒介质成形的影响

Effect of ultrasonic vibration on solid granules medium forming of sheet metals

针对常规变形方法难以实现的轻合金板成形问题,综合固体颗粒介质成形和超声振动塑性成形技术,提出超声激励颗粒介质成形工艺。采用ABAQUS对变幅杆及凹模按照20 k Hz工作频率进行设计并展开模态及谐响应分析,并以此为基础,设计并制造了最大输出功率1.5 k W的板材超声激励颗粒介质成形模具,进行AZ31B筒形件热态拉深试验,研究超声振动对板材颗粒介质拉深成形的影响。结果表明：超声激励促进颗粒介质的流动性及其传压性能;超声激励影响镁合金板材的极限拉深比,在振幅为6.7～11.6μm范围内,该极限拉深比呈现先增加后降低的规律。超声振动可以降低最佳压边力及成形载荷并抑制法兰区起皱,并且成形载荷随着超声振幅的增加,载荷降低比例越高。

For the lightweight alloy sheet which is hard to deform with conventional techniques, ultrasonic-vibration granules medium forming （UGMF） technology was put forward in this work, combining solid granules medium forming with ultrasonic vibration plastic forming technology. Modal analysis and harmonic response analysis of the horn and the concave die were carried out by ABAQUS with the working frequency of 20 kHz. Based on the above research, the UGMF tools of sheet metals with a maximum output of 1.5 kW were designed and manufactured. In order to reveal the effect of ultrasonic vibration on sheet granules medium forming, cylindrical parts thermal drawing test of AZ31B magnesium alloy was performed. The results show that ultrasonic vibration promotes the liquidity and internal pressure transmission performance of granules medium. Meanwhile, the ultrasonic vibration not only reduces the optimal blank holder force and the forming load, but also suppresses wrinkle on the flange. The limit drawing ratio of magnesium alloy sheet first rises then falls with the ultrasonic amplitudes ranging from 6.7 to 11.6 μm. In addition, the reduction percent of forming load increases with the increase of ultrasonic amplitudes.