侧铣式高速电弧放电加工的极间流场仿真及加工试验

Flow Field Simulation and Machining Experiment of Flank Milling Blasting Erosion Arc Machining

在高速电弧放电加工方法的基础上提出一种用于加工连续曲面、直纹面等的新型加工工艺——侧铣式高速电弧放电加工方法。与其他利用电弧进行加工的工艺方法相比,侧铣式高速电弧放电加工主要利用电极的侧面进行电弧蚀除加工,可用于加工各种复杂曲面和曲率半径较大的型腔及沟槽、流道等。侧铣电极采用侧面周边及底面多孔结构,能够实现极间的强化内冲液,在电极旋转运动的配合下,可有效控制电弧进而达到高效去除材料的目的。为了深入研究流场对侧铣式高速电弧放电加工效果的影响,建立了加工过程的极间流场模型,仿真并分析了侧铣电极在不同冲液孔分布及冲液入口压力下的极间流场。分析及进一步的工艺试验结果皆表明,在冲液入口压力为1.6 MPa时,在保证电极结构强度的条件下,增加电极的周向孔数,可以实现极间工作液的充分流动,使流场分布更均匀,从而改善电弧放电状态,可以获得较好加工效果。试验表明,在峰值电流400 A时,侧铣式高速电弧放电加工Cr12模具钢的材料去除率可以达到4 095 mm^3/min,相对电极损耗率为2.5%。最后,采用侧铣式高速电弧放电加工方法进行了连续曲面及涡轮叶片特征流道加工的可行性验证。

To extend the application of blasting erosion arc machining, a new arc machining process-flank milling blasting erosion arc machining is proposed, which can process continuous curved surfaces and ruled surfaces. Compared to other processes which utilize arc to machine, flank milling blasting erosion arc machining malnly uses the flank of its electrode to remove workpiece material. It can implement machining of complex surfaces, cavities with large radius of curvature, slots and passages as well. The hole array distributed on the side wall and the rotary motion of the electrode enhance the flushing in the inter electrode gap, combining both mechanisms of hydrodynamic arc breaking mechanism and mechanical moving arc breaking mechanism, thereby obtalning high material removal rate. In order to explore the influence of flushing on machining performance of flank milling blasting erosion arc machining, the inter electrode gap flow models of different electrodes and different inlet pressure are built for simulations. Meanwhile, the machining experiments are conducted. Both simulation and experiments indicate that the increase of number of flushing holes lead to a better machining performance while the inlet pressure kept at 1.6 MPa. It attributes to the improvement of the inter electrode gap flow field, thus malntalning better arcing state. Experiments demonstrate that the material removal rate can reach 4 095 mm3/min and the relative tool wear ratio malntalned below 2.5%while the peak current is 400 A. The passage of turbine is machined to demonstrate the feasibility of flank milling blasting erosion arc machining.