基于“积木式”电极单元的强可控极间流场高速电弧放电加工方法研究

Limited by the design and manufacturing technology of electrode, the electrode geometry of blasting erosion arc machining and the internal flow paths are difficult to be both taken into account, resulting in a poor controllability of the gap flow field , and its performance advantages and application fields are limited. To address this problem, a new method on the blasting erosion arc machining of strong controllable gap flow field is proposed, of which the core can be described as: 1) Brazing welding the "building block" graphite electrode units, and create a complex shape of the electrodes and the internal flow paths; 2) Control the flow field precisely to enhance the arc machining performance by using sophisticated flow paths; 3) Use the inclined liquid outlet to suppress remaining material to avoid electrode shaking. The research studies and solves key scientific and technical issues of the self-sustaining discharge conditions of the steady-state plasma arc column, the basic characteristics of the goal flow field in gap, the construction design of the porous electrodes, the brazing welding of many complex arrangement of joints of graphite electrodes, and to achieving blasting erosion arc machining of strongly controllable flow field between electrodes, further enhancing the processing performance and expanding the range of its applications. The features of this project are: improving the plasticity of electrode shape and the flow path greatly by the innovative method of electrode manufacturing, the characteristics of the cavity and the internal flow paths are both taken into account, so that the research of blasting erosion arc machining can be studied more thoroughly and a new solution to the many processing problems of manufacturing aerospace is provided.

受电极设计制造技术的限制，高速电弧放电加工电极的几何外形与内部流道难以兼顾，导致极间流场的可控性差，效能优势发挥与应用范围受限。针对该问题，提出了一种实现极间流场强控制的高速电弧放电加工新方法，其核心为：1）钎焊连接“积木式”石墨电极单元，塑造电极的复杂外形与内流道；2）利用复杂内流道精确控制极间流场，提高大电流电弧放电加工的效率；3）采用冲液出口倾斜的料芯抑制策略实现不平动加工。主要研究并解决等离子体弧柱脱离稳态自持放电的条件、极间目标流场的形态特征、多孔电极的设计构建、空间多焊点复杂排布的石墨钎焊等关键科学问题和技术问题，实现强可控的高速电弧放电极间流场，进一步提升加工性能，拓展其应用范围。本项目的特点是：通过电极制备方法的创新，大大提高了电极外形与内流道的可塑性，完美兼顾了型腔特征与流场控制，从而可将高速电弧放电加工研究推向新高度，并为航空航天制造领域的诸多加工难题提供新的解决方案。

高速电弧放电加工电极的几何外形与内部流道难以兼顾，导致极间流场的可控性差，效能优势发挥与应用范围受限。针对该问题，提出了一种实现极间流场强控制的高速电弧放电加工新方法。通过钎焊连接“积木式”石墨电极单元，塑造电极的复杂外形与内流道，并利用复杂内流道精确控制极间流场，提高大电流电弧放电加工的效率。.项目在以下方面取得了进展：.（1）获得了内冲液条件下等离子体弧柱的运动行为特征.揭示了峰值电流对电蚀坑的宽度与电弧柱移动距离以及脉冲宽度对电弧柱移动距离影响；通过高速摄像机观测得到电弧柱移动规律；进行弧柱、气泡、工作液三者结合的仿真研究，验证了气泡的产生运动规律和弧柱移动规律。.（2）实现了空间多焊点复杂排布下的高强石墨钎焊成型.通过调节焊接温度、保温时间、焊接压力参数，获得拉伸力和三点弯曲力矩下的最佳参数数据，使用XRD分析了焊点各层次成分，并确定了多焊点复杂排布下的最佳焊料组分。.（3）揭示了极间流场和电极内部加工液流动特征.建立极间固液两相流模型和电极内部流场模型并进行了数值模拟，揭示了电极内部流道不同状态下造成的冲液差异，证明了极间蚀除产物能够快速地排除出极间加工区域，降低极间蚀除产物浓度。.（4）提出了电极模块设计与电极构建方法.提出了多通道冲液、可关停冲液、三维冲液、斜向冲液等电极设计思路，以及通过设计单元模块电极，按照需要刻画流道与焊料，通过钎焊制备整体电极的方法。.（5）开发了大功率脉冲电源和控制系统.采用IGBT软开关技术的ZVZCS全桥变换器获得大功率大电流输出；并以现有电火花加工机床的本体为基础，设计并制作了一套用于探索高速电弧放电加工工艺的脉冲电源及机床的数控系统。.（6）验证了整体技术方案并开展了加工工艺特性研究.对圆形电极进行整体钎焊得到整体电极，并进行了工艺特性研究，研究冲液入口流量，放电峰值电流，放电脉冲宽度对材料去除率的影响，并研究不同的放电峰值电流与冲液入口流量对材料去除率的影响趋势。