Predictive Methods Of Surface Roughness In Micro-Milling Nickel-base Superalloy

The micro parts which can be used in the field of aerospace and energy and power often need to meet the requirement that the parts can have high strength in high temperature.The micro parts manufactured by nickel-base superalloy can meet this requirement and is suitable to the above fields.Micro-milling technology is a kind of machining method,it can fabricate micro parts with millimeter or less dimensions which have precise three-dimensional complex structures,so it can meet the requirements of manufacturing micro parts by nickel-base superalloy.However,there are many hard spots in the nickel-base superalloy and chip is easy to adhere on the cutter,that cause the cutting force is large,cutting heat is high and the wear of micro milling cutter is serious in the micro-milling.Nickel-base superalloy is a typical difficult-to-machine material,it is hard to guarantee the surface quality when micro milling this material.The surface quality is an important content in micro-milling research,it has important influence on wear resistance,corrosion resistance and heat transfer performance.Surface roughness research occupies an important position when studying and analyzing micro-milling surface quality,it can reflect the machining process and the surface quality of micro parts,and it can estimate comprehensive functions of process parameters and system variables to the machining process.Compared with the conventional milling,scale effect,multiple regenerative effect and dynamic response have a great influence on surface roughness,so micro-milling surface roughness is hard to control and predict.Thus this paper takes nickel-base superalloy(brand: Inconel718)as the research object,and researches the surface roughness of micro-milling.The main research contents are as follows:Firstly,based on the machine characteristic of micro-milling analysis by our research group,including the instantaneous cutting thickness,cutting force and dynamic characteristic of micro milling,this paper establishes intergrating model of micro milling,and the actual cutting trajectory is obtained.Then,this paper establishes flexible deformation model of micro milling cutter in order to solve the flexible deformation generated by cutting force.Based on the truth that machined surface is generated by duplicating the tool profile on the workpiece surface,according to the actual cutting trajectory and flexible deformation of micro milling cutter,the simulation model of micro milling surface topography of side wall of nickel-base superalloy Inconel718 is established,and the surface topography of micro milling is obtained.Ra is taken as the evaluation index of surface roughness and this paper calculates the value of Ra from the simulated micro-milling surface topography of side wall.The accuracy of simulation model is verified by micro milling experiments.Finally,based on the data acquired by micro-milling experiments,this paper presents a kind of prediction method to predict micro-milling surface roughness of bottom of slot.The relationship between cutting parameters and micro-milling surface roughness is built,that can realize prediction before machining.Some experiments are conducted to verify the accuracy of this method.