Experimental And Simulation Research On Ultra-High Speed Grinding Of Nickel-Based Superalloys Based On Single Abrasive Grain

Due to its excellent mechanical properties at high temperature,nickel-based superalloy has been widely used in the aerospace and aviation industry.However,at the same time,nickel-based superalloy has high-temperature strength,low thermal conductivity,and many strengthening phases,resulting in low grinding processing efficiency and processing quality.Ultra-high-speed grinding technology has the advantages of high machining efficiency,small grinding force,less grinding wheel wear,and good workpiece surface quality,etc.,and provides a new way for the efficient processing of nickel-based superalloy.There are few studies on ultra-high-speed grinding of nickel-based superalloy,and there is still no corresponding analysis and discussion on the mechanism of ultra-high-speed grinding of nickelbased superalloy.In view of the above problems,this paper adopts the grinding technique with single abrasive grain,through the research method of combining experiment and simulation,the influence rule of the underformed chip thickness and grinding speed on the material chip formation removal process under the condition of ultra-high speed grinding was analyzed,and the material removal mechanism of ultrahigh speed grinding was revealed.The main research work and achievements are as follows:(1)A single grain brazed grinding wheel for ultra-high speed grinding is developed.The dynamic and static properties of steel,aluminum alloy,titanium alloy and CFRP were compared by the way of finite element modeling.And CFRP was selected as the grinding wheel matrix.According to the material characteristics of CFRP,the structure of the grinding wheel was designed and its strength was checked.The diamond grains and metal segments were welded together by high-frequency induction brazing,and the grinding wheel was prepared and tested for safe rotation.The results show that the single grain brazed grinding wheel can be used in the ultra-high speed grinding test with a maximum grinding speed of 200m/s.(2)Based on the single grain brazed grinding wheel,the experiment of ultra-high speed grinding GH4169 nickel base superalloy with grinding speed of 80-200m/s was carried out.The groove morphology of the workpiece and chip morphology were observed and analyzed,the pile-up ratio and concentrated shear frequency were obtained,and the influence of the underformed chip thickness and grinding speed on material removal behavior was analyzed.(3)The simulation of single abrasive grain grinding was carried out by using the finite element method.A three-dimensional model of single-grain grinding of GH4169 nickel-based superalloy was established.Both the chip morphology evolution and the variation of the grinding force were explored in the simulation of grinding process.In addition,the distribution and changes of physical parameters such as stress,strain and temperature in the grinding area were characterized.And the influence of the underformed chip thickness and the grinding speed on the chip morphology,chip formation frequency and the pile-up ratio were revealed.The research results of this paper deepen the understanding of ultra-high speed grinding mechanism and provide theoretical and technical support for the realization of high quality and high efficiency machining of nickel base superalloy.