大面积钛合金电火花加工放电产物运动规律研究

发布时间：2018-03-24 12:29

  本文选题：钛合金　切入点：电火花加工　出处：《机械工程学报》2017年21期

【摘要】：在大面积钛合金电火花加工过程中,容易造成电蚀产物聚集且不易冷却从而产生集中放电、拉弧及短路现象,严重的甚至会烧伤工件的表面。因此,为了实现持续稳定的正常火花放电,在放电过程中放电点的位置分布必须均匀。电火花放电产生的气泡及加工屑是影响放电点分布均匀性的关键因素。为此,首先通过计算流体动力学软件Fluent对气泡的运动规律进行了仿真分析,然后通过高速摄像机拍摄透明电极下气泡的运动规律验证仿真的可靠性。结果表明气泡在间隙内的运动经过了膨胀、收缩及破裂的过程。通过试验对脉冲放电产生的加工屑颗粒的直径分布及数量进行了研究,并对加工屑在放电瞬间的抛撒机理做出了合理的假设,建立了电火花加工过程中放电间隙流场的气液固混合相三维模型,仿真分析了气泡运动对加工屑运动的影响规律。研究发现加工屑在气泡内部时,由于空气对加工屑的阻力小于工作液对气泡膨胀的阻力,加工屑快速向气泡的边界靠近。而当加工屑穿透气泡的边界进入工作液中后其速度迅速降低,且随着气泡的收缩逐渐靠近放电发生的位置。因此可以通过改变脉冲间隔实现控制气泡的大小及加工屑的分布,从而可以有效避免集中放电提高放电点分布的均匀性。
[Abstract]:In the process of large area titanium alloy EDM, it is easy to cause electrical corrosion products to gather and not to be cooled, resulting in concentrated discharge, arc pulling and short circuit phenomena, which may even burn the surface of the workpiece seriously. In order to realize the continuous and stable normal spark discharge, the location distribution of the discharge point must be uniform during the discharge process. The bubble produced by the electric spark discharge and the processing chip are the key factors affecting the uniformity of the discharge point distribution. Firstly, the motion law of the bubble is simulated and analyzed by the computational fluid dynamics software Fluent. The simulation results show that the bubble motion in the gap has expanded. The process of shrinkage and rupture. The diameter distribution and quantity of machining chip particles produced by pulse discharge are studied through experiments, and reasonable assumptions are made on the throwing mechanism of machining chips at the moment of discharge. A three-dimensional model of gas-liquid-solid mixed phase in discharge gap flow field during EDM is established, and the effect of bubble motion on chip motion is simulated and analyzed. Because the air resistance to the processing debris is smaller than that of the working fluid to the bubble expansion, the processing debris is rapidly approaching the bubble boundary, and the velocity decreases rapidly when the cutting debris penetrates the boundary of the bubble into the working fluid. As the bubble shrinks closer to the position where the discharge occurs, the size of the bubble and the distribution of the chip can be controlled by changing the pulse interval, which can effectively avoid the concentrated discharge to improve the uniformity of the discharge point distribution.
【作者单位】： 西安交通大学机械制造系统工程国家重点实验室;
【基金】：陕西省工业攻关资助项目(2014K06-03)
【分类号】：TG661
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本文编号：1658293