Research On The Technology And Mechanism Of Green,Efficient And High-Quality EDM Of CFRP In Aerosol Medium

Carbon fiber reinforced composites(CFRP)are widely used as an advanced composite material.Traditional machining methods like drilling and milling can already process CFRP,but they suffer from certain processing defects such as delamination,burrs,and cracks,and they also cause significant tool wear.Recently,special processing methods such as laser machining,waterjet machining,and ultrasonic-assisted machining have also been applied to CFRP machining,improving processing conditions and enhancing both efficiency and quality.Nevertheless,due to technological limitations,issues like thermal damage zones and delamination can still occur.In order to further improve CFRP processing efficiency and surface quality,electric discharge machining(EDM)of CFRP in aerosol medium is proposed to explore its processing characteristics and provide theoretical reference for subsequent CFRP processing.Based on the EDM theory,a high-low voltage composite pulse power supply,current detection circuit,and PLC upper computer control system are designed to build a gas EDM experimental platform for CFRP.The material removal mechanism and surface damage mechanism of CFRP in high-pressure gas media EDM are analyzed and experimentally verified.Based on this,a single-factor experiment on hole machining is carried out to study the effects of main electrical parameters such as polarity,breakdown voltage,air pressure,pulse frequency,duty cycle,and machining current on machining speed and surface quality.The study finds that discharge machining of CFRP can be achieved in gas media,where the material is mainly removed through melting and high-temperature oxidation.The addition of high-pressure gas can facilitate discharge machining,whose efficiency is low,and there is a large heat-affected zone on the surface.Based on the gas EDM experimental platform built in this work,a mist system is constructed to achieve EDM of CFRP in aerosol medium.The mechanism of aerosol in EDM is analyzed,including guiding discharge channel formation,compressing discharge channels,cooling,and improving chip removal conditions.A single-factor experiment on hole machining in aerosol medium is conducted to study the machining rules of the main electrical parameters and compared with those in gas media.The experimental results suggest that the addition of aerosol medium increases the machining speed by several times and significantly reduces the width of the heat-affected zone at the edge of the hole.Furthermore,the main electrical parameters are optimized,and experiments on variable parameters and deep-hole machining are conducted,which achieves better surface quality with a heat-affected zone width of 75 μm and efficient deep-hole machining with a depth of 18 mm.This validates the feasibility of achieving high-efficiency and high-quality EDM of CFRP in aerosol medium.CFRP space milling is studied based on a series robot with six-degrees-of-freedom.Trajectory design is carried out using CATIA software to export waypoint coordinate information.A posture function for cylindrical surfaces is developed to plan the robot milling process and achieve variable posture machining.A flat-line milling experiment is conducted to study the effects of electrode movement speed,machining current,and pulse frequency on milling speed and surface quality.Hole milling experiments are conducted to compare the results of fixed posture and variable posture machining and confirm the necessity of variable posture machining.Based on this,experiments on flat curve milling,spatial line milling,and spatial curve milling are conducted to verify the feasibility of CFRP mist spatial milling.