涡轮盘榫槽加工工艺及变形控制方法研究

Research on deformation control method during the machining of turbine disk fir-tree slot

涡轮盘毛坯粉末冶金制备工艺过程中形成的内部残余应力是影响榫槽尺寸精度和使用稳定性的重要因素。分析了加工过程中材料残余应力导致变形的机理,提出了“线切割+磨削”的变形控制组合加工工艺。针对涡轮盘榫槽的加工变形特点,设计V形槽实验测量出了涡轮盘残余应力变形规律,进而提出采用大余量粗切释放应力、小余量精切修复变形的加工工艺,此方法可有效控制榫槽加工中的残余应力变形,保证了磨削工序的余量均匀。通过磨削去除重融层并保证精度的使涡轮盘榫槽精加工余量获得较好的一致性。最终,磨削后的精度比设计要求提高了50%以上。

Internal residual stress formed during powder metallurgy preparation of turbine disk blank.It was an important factor affecting the dimensional accuracy and service stability of fir-tree slot.After analyzing the mechanism of deformation caused by material residual stress in machining process,this paper puts forward the combined machining technology of deformation control of"WEDM+Grinding".According to the machining deformation characteristics of fir-tree slot,V-groove experiment was designed to measure the residual stress deformation law of turbine disk.Furthermore,the machining technology of using large margin coarse cutting to release stress and then using small margin precision cutting to repair deformation was put forward.This method can effectively control the residual stress and deformation in tenon groove machining and ensure the uniform margin in grinding process.The remelting layer was removed by grinding and the precision was ensured so that the fine machining allowance of turbine disk mortise and groove can be well consistent.Finally,the grinding accuracy was improved by more than 50%compared with the design requirements.