| Nickel-based superalloy has many excellent properties such as high temperature resistance,good corrosion resistance and significant fatigue resistance,and is widely used in aviation,aerospace,nuclear power and petroleum and other fields,but it is a difficult material to process,and it is mainly manifested in the cutting process as large cutting force and serious fluctuations,high processing temperature,tool wear and work hardening phenomenon.Due to the difficulty of machining nickel-based superalloys,and the easy presence of chips winding tools or workpieces in turning processing,resulting in tool chipping or rough machining surface or even product scrapping,it is difficult for ordinary cutting technology in the traditional sense to achieve high-quality and high-efficiency processing.Due to the characteristics of periodic contact and separation of tools and workpieces,low-frequency vibration cutting technology has excellent performance such as reducing cutting force and cutting temperature,improving workpiece surface quality,enhancing tool durability and easy chip breakage.In this paper,the influence of cutting speed,feed,back-eating amount and amplitude on chip morphology,cutting force and cutting temperature during the cutting process of nickel-based alloy is discussed through finite element simulation modeling and experimental research of ordinary turning and vibration turning.It provides a strong theoretical support and test basis for improving the machinability of nickelbased superalloys and other difficult-to-machine materials and the practical promotion of lowfrequency vibration cutting technology.The kinematic mechanism of axial vibration turning was analyzed,and the mathematical model of the motion space trajectory of the tool tip relative to the workpiece was established.The chip breaking characteristics of axial vibration turning were studied,the chip breaking critical formula was derived,and the relationship between process parameters and chip morphology was analyzed.The influence of process parameters on the working angle of the tool in the process of vibration turning is studied,and the turning force model of vibration cutting is established,which provides a design basis for the subsequent development of vibration turning tool holders.Based on the Deform software,the finite element model in the turning process is established,and the chip morphology,forming process,stress field,main cutting force and temperature field under the two machining conditions of ordinary turning and vibration turning are studied.The results show that the chips of vibration turning are more prone to fracture and their stress field distribution is more concentrated.The peak peak cutting force of vibration cutting is higher than that of ordinary turning,but the average main cutting force is small,and the average main cutting force is reduced by 27.8%compared with that of ordinary turning.The average cutting temperature of vibrating cutting is 291℃,which is lower than the average cutting temperature of ordinary turning,and the highest point of the rake face temperature before vibrating turning is farther away from the tip than that of ordinary turning.Using the principle of eccentric vibration,a low-frequency axial vibration turning tool holder that can be directly mounted on the tool holder,with adjustable amplitude and powered by the motor was developed,and the static simulation analysis of the vibration turning tool holder was carried out.By building a tool holder test platform to test its performance,the results show that the actual output curve of the tool holder is sinusoidal and the maximum error between the actual amplitude and the theoretical amplitude is 11.5%.By building the Vibratory Cutting Test Platform of InConel718,the influence of process parameters on chip morphology,turning force and cutting temperature of ordinary turning and vibration turning was studied.The test results show that the chip breaking effect of vibration turning is better,when the ratio of amplitude to feed is less than 0.5,no chip breaking occurs;the main cutting force of vibration turning with the increase of cutting speed shows a trend of first decreasing and then increasing and then decreasing,and the separation characteristics are weakened when the cutting speed increases to a certain situation,and the amount of back eating has the greatest influence on the three forces of vibration turning,and the increase of amplitude reduces the cutting force and cutting temperature of vibration turning. |
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