平板圆形爆破片预制缺陷的精密放电加工研究

Study on Precision EDM of Prefabricated Defects on Flat Circular Bursting Sheet

爆破片是安全阀内部气压控制的关键零部件,其爆破压力由表面预制的缺陷特征控制,影响因素多、加工精度要求高。根据环形沟槽截面轮廓的周向一致性和旋转对称性,提出采用薄壁圆筒电极旋转放电加工预制缺陷特征,解决了几何特征可控性问题;在此基础上,进一步提取沟槽截面轮廓特征,通过模型仿真和实验测试确定了决定零件爆破压力的最主要几何特征,并进一步确定了满足目标爆破压力的加工流程。基于以上工作,定量给出了满足目标爆破压力范围的关键几何特征容许区间,并在后续验证实验中取得了良好的加工效果,实现了特定爆破压力的平板圆形爆破片零件的高效高质量加工。

Bursting sheet is the key component to control working pressure of safety valve,of which the geometry is composed of a circular metal sheet and a coaxial ring trench.As the pre-fabricated defect,the coaxial ring trench is of significance in bursting pressure control,which also put forward higher requirements in machining precision.In present investigation,the ring trench feature is fabricated in a more controlled way by rotary EDM with a thin wall cylinder electrode.By extracting the sectional profile of ring trench,the FEM model of flat circular bursting sheet is established as well as the bursting pressure is predicted.With all above,the applicable scope of geometric features corresponding to desired bursting pressure is determined,which is experimentally verified subsequently.Finally,a procedure to pre-fabricate coaxial defects on flat circular bursting sheets with desired bursting pressure is carried out.