Ultrasonic Vibration Assisted Variable Parameter Pecking Drilling Technology For Ti-CFRP-Ti Laminated Materials

In recent years,laminated materials composed of titanium alloy and carbon fiber reinforced plastic(CFRP)have been widely used in manufacturing industry,especially in aerospace field.However,the cutting performance of the two materials is quite different.In the drilling process of Ti/CFRP laminated materials,the tool wear is serious and the quality of the hole is difficult to guarantee.It is a difficult problem for aerospace industry to realize high quality and high efficiency hole making method of Ti/CFRP laminated materials.In this paper,the composite drilling method of variable parameter pecking drill assisted by ultrasonic vibration is used to study the drilling process of Ti-CFRP-Ti laminate,and the relevant process parameters are optimized.The main contents of this paper are as follows:(1)The research on axial force and drilling temperature in ultrasonic vibration drilling of Ti-CFRP-Ti laminated materials was carried out.A drilling experimental platform for Ti-CFRP-Ti laminated material was built and the experimental research was carried out.The influence laws of spindle speed,feed rate and ultrasonic amplitude on drilling axial force were obtained and the regression model of drilling axial force was established.A numerical simulation model of tool temperature was established based on heat transfer theory and the prediction of tool temperature during drilling was realized.(2)The research on ultrasonic vibration drilling quality of Ti-CFRP-Ti laminated materials was carried out.The influence laws of spindle speed,feed rate and ultrasonic amplitude on surface roughness of hole wall were obtained based on the experiment,and roughness regression model was established.The kinematics analysis of tool for ultrasonic vibration drilling was carried out and the influence laws of process parameters on tool path were obtained.The conditions that the parameters should meet when chip breaking is formed were obtained.(3)The Optimization Research on ultrasonic vibration assisted pecking drilling technology with variable parameters was carried out.An optimization model of drilling consumption for each layer of material was established,and the spindle speed and feed rate suitable for drilling each layer of material were obtained.A discrete model of the axial force on the main cutting edge and the chisel edge was established,and the drilling axial force in the interface region of Ti-CFRP-Ti laminated material was analyzed.The optimal variable parameter strategy for drilling Ti-CFRP-Ti laminated material were obtained by comparison.A peck drilling method with unsteady time parameters limited by temperature threshold was proposed.The drilling experiments and tool temperature simulation with different single cooling time parameters was carried out,and the more efficient peck drilling parameters were obtained.