Finite Element Analysis On Drilling Process For Nickel-based Superalloy And Main Cutting Edge Structure Evaluation

As a type of hard-to-cut material and an important part of aerospace materials,nickel-based superalloy has many problems in its cutting process,such as large cutting force,high cutting temperature,and serious tool wear.These problems are more prominent in the drilling scene due to the semi-closed space.Many scholars have been committed to the research of tool structure improvement to optimize the drilling process.However,the change of tool structure will lead to the change of tool load.The in-depth analysis of drilling process for nickel-based superalloy is conducive to the optimization of drilling nickel-based superalloy,which is of great strategic significance for promoting the development of aerospace industry.This paper takes the drilling process of Inconel 718 nickel-based superalloy as research object,and the specific research contents are as follows(1)The structure of drilling tools is analyzed and divided into different sections.The global and local coordinates are established respectively,and the corresponding force component analysis for each section of tool unit is carried out.The forces under global coordinate system can be obtained by coordinate conversion of forces in the local coordinate system,and the overall main cutting force and axial force can be calculated by the sum of forces for each tool unit.The geometrical analysis is conducted to acquire the basic parameters of each tool unit.The simplified three-dimensional simulation model is established to conduct the finite element analysis.(2)The finite element analysis is set according to the obtained parameters.The double and single drill tests are used in measurement of axial force and main cutting force.The experimental and simulated results are compared to verify the effectiveness of the simulation model.The errors for axial force and main cutting force between simulation and experiments are acceptable.The simplified three-dimensional simulation model has certain reliability for predicting the drilling load for Inconel 718 under small feed(3)The drilling load,equivalent stress,highest cutting temperature and tool wear under different drilling parameters are discussed based on the analysis of control variables(the cutting speed and the feed rate per tooth).The influences of different drilling parameters on drilling process for nickel-based alloy are explored.With the increase of feed rate per tooth and cutting speed,the high equivalent stress distribution area of workpiece expands.The drilling temperature is positively related to feed rate per tooth and cutting speed.The largest wear depth and the highest interface temperature are positive with the increasing feeds per tooth and cutting speeds.In the range of medium/low cutting speed,the main cutting force and axial force varies little with cutting speed,because the heat softening effect is too weak to reduce the deformation resistance of workpiece material.Compared with the cutting speed,the Inconel 718 drilling seems more sensitive with the varying feeds.The main cutting force and axial force increase with the increasing feed rate per tooth(4)The distribution of Fxy load along the edge is extracted and analyzed.The Fxy load tends to push tool material obliquely outwards.The finite element analysis is carried for different main cutting edge structures to assess the possibility of different main cutting edge structures to improve drilling process for Inconel 718.The convex-edged tool leads to the lowest cutting temperature,slightest tool wear and smallest drilling load,as the bigger inclination angle helps buffer the shock of workpiece on tool and reduce the plastic deformation work of workpiece material.The pushing effect of the load vector towards the tool material seems the mildest,so the convex main cutting edge structure can protect the tool body to some extent.