Research On Key Technology Of High Efficiency Profile Grinding Of Nickel- Based Superalloy

Due to their high resistance to corrosion, mechanical and thermal fatigue, mechanical and thermal shock, creep and erosion at elevated temperature, superalloys are widely used in aerospace, shipbuilding and chemical insustry and serve in severe operating environments(high temperatute and complex stress). In aeroengine, nickel- based superalloys are most widely used and regard as the ‘heart’ of the engine. The improved material performance leads to their poorer machinability. In order to meet the higher requirement of machining efficiency, it is necessary to develop high efficiency grinding process. High Efficiency Deep Grinding represent the most advanced grinding process in the machining of nickel- based superalloy. And how to take advantage of the superiority is urgent problems need to be solved. Therefore, with the target of successful application in solidified directional nickel- based superalloy DZ125, the key technology of high efficiency profile grinding process has been studied. The major research works are included as follows:1. Study on the performance of CBN grinding wheel used in the grinding of nickel- based superalloy. The grinding force, specific grinding energy and grinding temperature were analysised to evaluated the performance of different kind of CBN grinding wheel. With the utiliziton of replication process, 3D microscope and SEM, the wear characteristic of electroplated CBN grinding wheel was investigated. And the wear mechanism was discussed combining with the change of grinding force. Sinle grit test was used to analysis the grinding ratio of CBN grain.2. Study on the fluid pressure in grinding zone. Based on the analysis of the relationship between fluid pressure in grinding zone and grinding burn, it was figured out that the pressure was an important character affecting the cooling condition. With the target of improving the pressure, the effect of process parameter, air acrape, coolant supply condition were analysised. And the shape of nozzle was also optimized based on the distribution of pressure. Finally, the effect of coolant supply contition on the available spindle power was studied.3. The grinding process of HEDG was investigated. The critical grinding speed was determined based on the analysis of specific grinding energy, and the relationship between undeformed chip thickness and specific grinding energy has been found out. And the effect of undeformed chip thickness on distribution character of grinding temperature was also studied. The observation of chip microtopography was conducted to reveal the chip formation mechanism.4. The application of HEDG in turbine blade tenon made of solidified directional nickel- based superalloy DZ125. The CBN grinding wheel was designed and manufacetred according to the requirement. The process parameter was optimized based on the machining allowance. The profile accuracy and surface integrity were analysised to verify that the application of HEDG could improve both of machining efficiency and quality.