低温微磨料气射流加工PDMS传热仿真及实验研究

Heat Transfer Simulation and Experimental Research of Cryogenic Micro‑abrasive Air Jet Machining PDMS

由于在常温下聚二甲基硅氧烷(Polydimethylsiloxane,PDMS)是一种高弹性材料而非硬脆材料,此时利用微磨料气射流对其进行加工,加工效率很低,甚至为零,而且还会有大量的磨料颗粒嵌入PDMS表面中。当PDMS冷却不完全,即处于高弹态和玻璃态之间的过渡状态时,利用低温微磨料气射流加工PDMS仍然会发生很严重的磨料嵌入现象,致使加工效果较差。针对这一问题,本文利用ANSYSFluent软件对PDMS进行传热仿真分析来获得PDMS内部温度的变化情况,从而能够计算得到在PDMS深度方向上的冷却速率,同时利用与传热仿真分析过程中完全相同的工艺参数在PDMS表面上加工微孔,计算出在PDMS深度方向上的最大平均冲蚀加工速率,最终发现冷却速率远大于冲蚀加工速率。根据传热仿真的分析结果,通过开展单因素实验探究进给速度v、加工距离D、冲蚀角度α以及加工压强p对PDMS加工性能的影响规律,为后续进行更深入的研究提供重要参考依据。

As polydimethylsiloxane(PDMS)is a high elastic material rather than a hard and brittle material at room temperature,the processing efficiency is very low or even zero by using micro-abrasive air jet to process it,and a large number of abrasive particles will be embedded into the surface of PDMS.When the cooling of PDMS is incomplete,that is,in the transition state between the high elastic state and the glass state,the machining of PDMS using cryogenic micro-abrasive air jet will still have a very serious abrasive embedding phenomenon,resulting in poor processing effect.To solve this problem,this paper uses ANSYS Fluent software to conduct heat transfer simulation analysis on PDMS to obtain the internal temperature change of PDMS,so as to calculate the cooling rate in the depth direction of PDMS.At the same time,the same process parameters are used to process micro holes on the surface of PDMS,and the maximum average erosion processing rate in the depth direction of PDMS can be calculated.Finally,it is found that the cooling rate is much faster than the erosion processing rate.According to the analysis results of heat transfer simulation,single-factor experiments are carried out to explore the effect of feed speed v,processing distance D,erosion angleα,and processing pressure p on the processing performance of PDMS,which provides an important reference for further research.