| Nickel-based superalloys are one of the ideal candidates for critical components in aerospace and gas turbine applications due to its excellent physical and chemical properties.However,the better the performance of engineering materials,the worse its cutting performance.Nickel-based superalloy due to its high temperature strength,poor thermal conductivity,high toughness and other reasons,resulting in large cutting force and high cutting temperature during the cutting process,tool serious wear and chipping of the tool,so the processing quality and efficiency of nickel-based superalloy workpieces are difficult to guarantee,is recognized as one of the difficult to process materials,which seriously restricts the efficient production of hightemperature alloy parts.Sialon ceramic tool material has excellent heat resistance,wear resistance and high temperature strength,and has good thermal stability and thermal shock resistance,which has excellent performance in processing some difficult-to-machine materials such as heat-resistant alloys.At present,the research on ceramic integral end mill high-speed cutting superalloy mainly focuses on cutting performance,tool wear and failure mechanism,etc.,while the geometry of the tool is relatively little.Therefore,for the high-speed machining of nickel-based superalloy GH4099,this paper studies the influence of the geometric parameters of Sialon ceramic integral end mill on milling stability and cutting performance from the geometric optimization of Sialon integral end mill,and optimizes the geometric structure of Sialon ceramic integral end mill.At the same time,aiming at the problem of high cutting temperature during high-speed cutting of superalloys,the MQL method is introduced to study the cutting performance of Sialon ceramic integral end mills under different MQL conditions,and the optimal process for efficient cutting of nickel-based superalloys is optimized.The specific research work is as follows:Conducted research on the milling stability of Sialon ceramic integral end mills.The influence of ceramic milling cutter geometric parameters on the modal characteristics of Sialon ceramic integral end mill was analyzed through modal experiments,and the modal parameters of ceramic milling cutters with different structures were solved.The average milling force was obtained by high-speed cutting experiment,the average milling force coefficient was calculated by linear regression analysis,the flutter stability lobe diagram was drawn by using the solved modal parameters and the average milling force coefficient,and the milling stability of Sialon ceramic integral end mills with different structures was predicted.The vibration acceleration experiment was carried out to analyze the cutting vibration generated by the ceramic milling cutter in the actual machining process.The results show that:When the helix angle is 35°,the rake angle is-12° and the relief angle is 9°,the stable area of Sialon ceramic integral end mill milling is the largest,and the cutting process can be carried out under a wider range of machining parameters without chatter.According to the vibration acceleration experiment,the vibration amplitude frequency of the seven structures of Sialon ceramic integral end mills for structural optimization all occurred at the fundamental frequency or frequency doubling of the tooth passing frequency,which proved that the optimized ceramic milling cutter mainly generated forced vibration rather than flutter during the cutting process,which verified the rationality of the selected machining parameters.By comparing the vibration acceleration values of ceramic milling cutters of different structures,it can be seen that when the helix angle is 35°,the front angle is-18° and the relief angle is 9°,the cutting vibration is minimal.Carry out the research on the cutting performance of Sialon ceramic integral end mill highspeed milling nickel-based superalloy GH4099.High-speed milling experiments were carried out to analyze and evaluate the cutting force,cutting temperature,tool flank wear and processed surface roughness,and the influence of ceramic milling cutter geometric parameters on cutting performance was studied.The results show that the milling cutter has serious flank wear during high-speed milling,and chipping is the main cause of its failure.With the increase of helix angle,the cutting force and cutting temperature gradually decrease,but when the helix angle is 35° and 40°,the cutting force and cutting temperature are not significantly reduced,and when the helix angle is 35°,the ceramic milling tool has lower tool wear and surface roughness,so the cutting performance is better.The influence of rake angle and relief angle is mainly reflected in the strength of the cutting edge of the tool.With the increase of the front angle and the back angle,the cutting edge strength of the ceramic milling cutter becomes low,and it is easy to chip phenomenon,so that the cutting force and cutting temperature in the cutting process surge,which has an adverse effect on the cutting process.When the rake angle is-15° and the relief angle is 12°,the cutting edge of the tool has higher strength,is not easy to chipping,which has lower cutting force and cutting temperature and better cutting performance.Therefore,when the helix angle is 35°,the front rake is-15° and the relief angle is 12°,the cutting temperature and tool wear of the ceramic milling cutter are small,the tool life is the longest,and the surface processing quality of the workpiece is obtained,which has the best cutting performance.Carry out research on the cutting performance of Sialon ceramic integral end mills under different cutting conditions.By changing the oil-water ratio under the condition of MQL,the cutting force,cutting temperature,tool flank wear and machining roughness were taken as the evaluation index,and the influence of different MQL conditions on the cutting performance was studied,and compared with the dry cutting condition,the wear form and mechanism of ceramic milling cutters under different cutting conditions were revealed.The results show that the MQL method can effectively reduce the cutting force and cutting temperature in the cutting process,reduce the tool wear,reduce the roughness of the machined surface,and improve the processing quality.Under different MQL conditions,with the increase of the proportion of water,the overall cutting performance of ceramic milling cutter first improves and then decreases,when the oil-water ratio is 1:5.Because the cutting fluid has sufficient lubricating oil,and the viscosity is small,so that the formed lubricating oil film is easier to diffuse to the entire cutting area,playing a better cooling and lubrication effect,so it has the best cutting performance.By analyzing the tool wear surface under different cutting conditions,it is found that the failure forms of ceramic milling cutters under both dry cutting and micro-lubrication conditions are pit wear,chipping,spalling and sticky chips,and the failure mechanism is diffusion wear and bonding wear,but the tool wear and sticky chips are more serious in the dry cutting environment. |
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