| As one of the most widely used metal materials,nickel-based superalloy is often used in the manufacture and production of high-end parts.As the most typical two brands,Inconel 718 and GH4169 play an important role in the high temperature alloy materials.The excellent comprehensive mechanical properties of these two materials make them widely used in various fields of industry.However,the excellent material properties of nickel-base superalloys make it one of the most difficult metal materials to process.In the process of cutting nickel-base superalloy,the main problems restricting the machining quality are large cutting force,high cutting temperature,severe tool wear,poor surface quality and large residual stress.Based on the above reasons,an elliptical ultrasonic vibration machining(UEVC)system,which is conveniently installed on a common horizontal machine tool,is designed to carry out an experimental study on the nickel-base superalloys Inconel 718 and GH4169.The cutting performance of circular ultrasonic vibration turning is studied deeply,which provides sufficient data support and theoretical basis for the further development and manufacture of elliptical ultrasonic vibration turning of nickel-base superalloy materials.The main contents of this paper include:(1)The UEVC working head designed is easy for installation and disassembly.The finite element analysis of each part of the working head is carried out and the structure is optimized.Finally,the reliability of the system is verified by ultrasonic atomization and cutting tests of different materials.(2)Study on the machined surface formation mechanism of elliptical ultrasonic vibration turning.The design of elliptical ultrasonic vibration turning system was used to test the nickel base superalloy Inconel 718,and the experimental data were optimized by Taguchi method.The optimal cutting parameters were obtained by using the regression method.The roughness prediction model was established by the method of analysis.The surface micro-morphology and surface damage of workpiece in UEVC and CC were compared by cutting experiments.The influence of cutting speed,ultrasonic amplitude ratio,feed rate and cutting depth on Sa,Ra and surface damage were also analyzed.(3)The wear mechanism of coated cemented carbide tool in elliptical ultrasonic vibration turning nickel base superalloy was studied.The design of elliptical ultrasonic vibration turning system was used to test the tool wear of Inconel 718,and the test data were carried out by Taguchi method.Parameter optimization,the best cutting parameters can be obtained to obtain the minimum flank wear,and the prediction model of tool flank wear is established by regression analysis method.The wear status of the coated cemented carbide tool in the elliptical ultrasonic vibration turning nickel base superalloy was studied.Finally,the economic cost of carbide cutting in general turning and elliptical ultrasonic vibration is analyzed.(4)The design of the Ni-based superalloy Inconel 718 was carried out by using the designed elliptical ultrasonic vibration turning system.The residual stress of the workpiece during processing and unprocessing was studied.The influence of the processing parameters and their interaction on the residual stress of the workpiece was analyzed.The prediction model of the residual stress of the workpiece after the elliptical ultrasonic vibration is established by the influence surface method.Finally,the linear minimized confidence domain method is used to find the best combination of parameters to obtain the residual stress on the surface of the workpiece.(5)The surface roughness,cutting force,chip shape and tool wear of the workpiece surface were studied by tu rning test of GH4169 nickel base superalloy with domestic grade on the elliptical ultrasonic vibration turning system designed by using diamond coating tool.The cutting performance and overall advantages of the ultrasonic vibration turning GH4169 are analyzed by comparison between ordinary turning and ultrasonic vibration turning. |
