低温磨料气射流加工PDMS实验研究

通过自研的低温磨料气射流加工装置进行低温磨料气射流加工聚二甲基硅氧烷(polydimethylsiloxane,PDMS)实验研究,分析了加工时间、加工距离、冲蚀角度和磨料粒径对冲蚀率、孔深和孔横截面形貌的影响。结果表明:随着加工时间的增加,冲蚀率先增大后减小,在第1阶段加工过程中,孔深与加工时间大致呈线性关系,增加加工时间还可使孔底部变平整;存在一个最佳加工距离使孔深最大,当加工距离大于最大加工距离时,孔深将随着加工距离的增加而急剧下降,孔的锥度随着加工距离的增大而增大;当冲蚀角度处于30°～60°之间时,冲蚀率最大,随着冲蚀角度的增加,孔的形状逐步由椭圆形变成圆形;存在一个最佳磨料粒径,使冲蚀率和孔深达到最大;当冲蚀角度小于90°时,低温磨料气射流加工PDMS材料去除机理为塑性去除和脆性去除的结合。

Experimental Study on Cryogenic Abrasive Air Jet Machining of PDMS

Experiment on cryogenic abrasive air jet machining (CAAJM) of PDMS has been achieved using self-developed CAAJM device. Based on the experimental study of CAAJM of PDMS, the influences of machining time, the centerline distances from the nozzle to the target, attack angle and the diameter of abrasive on erosion rate, the depth of holes and cross-sectional morphologies are investigated. Results indicate that with the increase of time, erosion rate firstly increases and then decreases. In the first stage of processing, the depth of the hole has linear relation to the the machining time. Increasing machining time can make the bottom of the hole smooth. There is an optimum distance to get the maximum machining depth. When the machining distance is greater than the optimum distance, the depth of the hole drops off sharply with machining distance. The taper of the hole grows with machining distance. The maximum erosion rate can be obtained when attack angle is between 30°and 60°. With the increase of attack angle, the shape of the hole gradually changes from elliptical to circular. There is an optimum diameter of abrasive to get the maximum erosion rate and machining depth. When the attack angle is less than 90°, the material removal mechanism of CAAJM of PDMS is a mix of ductile erosive system and brittle erosive system.