Research On Quality Optimization Of Hybrid Robot Based Helical Milling For Titanium Alloy/CFRP Stacks Structure

Titanium alloy and carbon fiber reinforced polymers(CFRP)are widely used in aerospace because of their excellent material properties.However,due to the low thermal conductivity,low modulus of elasticity of titanium alloys and anisotropy of CFRP.It is difficult to guarantee the quality of their holes,which has become a major difficulty in the field of aviation manufacturing.Helical milling technology based on hybrid robot is becoming an ideal hole-making technology for difficult-to-machine materials such as titanium alloy and CFRP.At present,the research on helical milling quality of titanium alloy/CFRP laminated components of hybrid robots is still in the exploratory stage.Based on TriMule hybrid robot,the quality of helical milling holes for titanium alloy/CFRP laminated components is studied in this paper.The main research contents include the following aspects:The theoretical model of cutting force for helical milling holes is established based on the analysis of motion and instantaneous chip thickness in the process of helical milling,and the identification method of cutting force coefficients for side and bottom edges is proposed.The cutting force coefficient for side edge is identified by groove milling experiment and linear regression method,and the bottom edge coefficient is identified by helical milling hole experiment.Finally,the correctness of the cutting force coefficient was verified.The stiffness distribution of TriMule hybrid robot in the workspace is calculated by SAMCEF simulation software,and the higher stiffness workspace is selected to improve the machined hole accuracy.The helical milling process of the hybrid robot is simulated,and the deformation of the robot structure in the process of milling holes is analyzed.The orthogonal experiment method is used to optimize the processing parameters for stack of helical milling based on hybrid robot.The helical milling experiments of stack of the robot are carried out with the optimized parameters to verify the simulation results of hybrid based helical milling hole-making process.The optimization strategy of helical milling hole quality of hybrid robot is established by changing the geometrical structure of helical milling tool.The first edge diameter of the tool is optimized through two process experiments.The helical milling hole experiments are carried out by using the improved tool.From the experimental data,it can be concluded that the geometric accuracy and surface quality of the hole can be optimized.This paper are mainly focused on hole-making quality improvement for hybrid robot based helical milling.The research results can provide theoretical basis for the application of hybrid robot in aviation manufacturing industry.