激光诱导空泡微孔抛光机理及实验研究

摘要

A novel micro-hole polishing method was introduced,this method applied the laser plasma shock waves,cavitation bubble shock waves of bubble collaps and jet to push the abrasive particles to polish the micro-holes.A high-speed camera and a silicon piezoresistive high-frequency dynamic pressure sensor were utilized to research the mechanism of the micro-hole polishing.Then the experiments of 304 stainless steel pipe polishing were carried out based on different laser energy,different laser pulse number and different laser pulse frequencies,which were found that the surface roughnesses were improved with the increasing of laser energy(from 7 mJ to 21.6 mJ) and laser pulses number (from 0 to 7 000),but the different laser pulse frequencies(from 1 Hz to 10 Hz) might not improve the surfaces roughnesses of the micro-holes.Finally,the polishing effectivenesses of different positions along the stainless steel pipes were studied,it is found that the polishing effectivenesses at the entrance of the pipes about 1～1.5 mm are better than the middles and ends of the pipes.Through the experiments of micro-hole polishing mechanism and experiments based on laser-induced cavitation bubbles,it is pointed out that the plasma shock wave,the cavitation collapse shock wave and jet work together during the micro-hole polishing,and the general rules of micro-hole polish are obtained based on laser-induced cavitation bubbles.%针对微孔抛光的问题,提出了一种新的抛光方法,该方法利用激光聚焦水中产生空泡,并利用激光等离子体冲击波、空泡溃灭冲击波和射流推送磨粒进行微孔抛光.通过高速摄影仪和高频动态压力传感器对激光诱导空泡机理进行了研究.利用不同激光脉冲能量、脉冲次数和脉冲频率对304不锈钢管进行抛光实验,发现随着激光脉冲能量(7～21.6 mJ)和脉冲次数(0～7000)的增加,微孔表面粗糙度也随之改善;同时激光在低脉冲频率(1～10 Hz)情况下,改变脉冲频率的大小对微孔的抛光效果影响不大.对微孔在不同位置的抛光效果进行了对比分析,发现孔入口1～1.5 mm处的抛光效果较好,孔中和孔尾的抛光效果不佳.通过激光诱导空泡微孔抛光机理和实验研究,表明微孔抛光过程是激光等离子体冲击波、空泡溃灭冲击波和射流共同作用的过程,并得到了激光微孔抛光的一般规律.