金属熔滴气动按需喷射特性试验研究

摘要

To generate single molten droplet by one gas pulse is essential for molten metal pneumatic drop-on-demand (DOD) ejection. This experimental study was carried out to investigate the characteristics of single molten droplet DOD ejection with a proprietary molten metal pneumatic DOD ejection system. The ejection process was examined by dynamic pressure acquisition system and strobe photography system. Based on the molten droplet forming process recorded,the influence of pressure on generating molten droplet was revealed. For each single pulse, the number of generated molten droplets increased with the pulse width. The pinch-off time was affected by the peak pressure in the chamber. The variation of the range of the pulse width for generating single molten droplet with gas pulse pressure was determined, and the range became wider in the case of relatively low supply pressure. The results show that, within the single molten droplet generation window, the size of the molten droplets is not influenced significantly by changing the pulse width but the peak pressure in the chamber decreases with the pulse width; the velocity of the molten droplet decreases proportionally with the decreasing peak pressure.%利用自行研制的气动式金属熔滴按需喷射系统进行了单颗熔滴的喷射特性试验研究,并采用动态压力采集系统和频闪拍摄系统测量了产生单颗熔滴时的坩埚腔内气压变化,记录了熔滴成形时刻和成形过程,揭示了气压对熔滴产生的影响规律:在每一次喷射中,产生熔滴的数目随着脉冲宽度的增加而增加;单颗熔滴的断裂时间受气压的影响;脉冲宽度在一定范围内改变可以使液体断裂形成单颗熔滴,当供给气压相对较低时,此脉冲宽度的取值范围较广;在喷射产生单颗熔滴的前提下,改变脉冲宽度将使腔内气压的峰值发生变化,但不能显著改变熔滴尺寸;熔滴飞行速度与腔内气压峰值成正比关系.