Experimental Investigation On Grinding Process Performance Of Aeroengine Single Crystal Parts

Single crystal superalloy has excellent high temperature performance and maintains high stability and reliability for a long time under high temperature and complex stress conditions.It is the preferred material for advanced aeroengine hot end parts.As a means of precision machining,grinding is usually used in the last process of parts machining,and the machining accuracy of micron and submicron can be obtained.Grinding is applied to the machining of aeroengine single crystal parts,which can improve the current situation of difficult machining of single crystal parts.At present,there are few reports about the grinding of aeroengine single crystal parts.Many basic theoretical problems and key technologies need to be solved and studied.In this paper,a series of experimental investigations on the grinding process performance of aeroengine single crystal parts are carried out,which has certain practical necessity and engineering significance.In the paper,based on the grinding experiment,combined with the finite element simulation and theoretical analysis,the material removal mechanism,processing technology and surface integrity of aeroengine single crystal parts grinding were investigated.In addition,the influence of Re content and abrasive type on the grinding surface quality of single crystal parts has also been investigated.The main research contents of the paper include:(1)Investigation on material removal mechanism of aeroengine single crystal parts grinding.Based on the finite element simulation of single grain grinding and plane grinding experiment,the morphology characteristics of the chip,grinding surface and subsurface were studied respectively.After comparing with the material removal mechanism of polycrystal superalloy grinding,the material removal mechanism of single crystal superalloy parts was obtained.In addition,within the range of experimental parameters,the effect of the grinding wheel linear speed on the material removal process of single crystal parts grinding has been studied.A larger grinding wheel linear speed is beneficial to improve chip formation frequency and surface quality.(2)Experimental investigation on grinding process of aeroengine single crystal parts.Based on the anisotropy theory and grinding experiment,the effect of different crystal orientations of the(001)crystal plane on the grinding force and the surface quality were investigated.The results show that the grinding force and surface quality along different crystal directions on(001)crystal surface show a certain change trend.Through the orthogonal experiment,it is concluded that the grinding wheel linear speed has the most significant effect on the grinding surface quality of single crystal parts.In addition,the optimized combination of process parameters(i.e.vs=30m·s-1,ap=20?m,vw=0.4m·min-1)is proposed to effectively control the grinding surface quality of single crystal parts within the range of experimental parameters(MQL).(3)Investigation on grinding surface integrity of aeroengine single crystal parts.The grinding surface integrity of aeroengine single crystal parts was studied by single factor plane grinding experiment.The results show that the grinding surface quality of single crystal parts changes with grinding parameters,and MQL as the cooling condition can improve the grinding surface quality more effectively.The y phase and y' phase of grinding subsurface distort along the grinding direction,and the hardness of grinding subsurface is enhanced.The thickness of grinding metamorphic layer varies with grinding parameters,and MQL can obtain relatively small thickness of grinding metamorphic layer.(4)Investigation on the influence of Re content and abrasive type on grinding surface quality of aeroengine single crystal parts.The influence of Re content and abrasive type on the surface quality of aeroengine single crystal parts was studied respectively by exploring experiment.The mechanical properties of the Re free DD98 single crystal part are similar to those of the Re containing DD5 single crystal part,so the two kinds of single crystal parts have similar grinding surface quality under most machining conditions.Due to the influence of Re,DD5 single crystal part is more difficult to be machined under the condition of larger grinding wheel linear speed and larger grinding depth,and the surface quality is relatively poor.Carbon reacts with single crystal parts under processing conditions,resulting in the surface quality of single crystal parts processed by the diamond wheel is inferior to that of the CBN grinding wheel.