Influence Mechanism Of Ultrasonic Vibration On Machining Quality Of Titanium Alloy Drilling Based On Power Flow Theory

Titanium alloy has the characteristics of high stiffness,low thermal conductivity,small elastic modulus and so on.It is widely used in aircraft engines,medical instruments and other fields.As titanium alloy is a difficult material to machining,especially in the semi-closed processing such as drilling,it will produce heat dissipation difficulties,not easy chip removal,easy to scratch the hole surface,low machining accuracy,serious bit wear and other problems.Ultrasonic vibration drilling was introduced to solve the problems in drilling difficult materials.Because it changes the motion characteristics of traditional drilling,the drilling force and torque can be reduced and the machining quality can be improved.Drilling force is a key parameter in drilling process.Drilling force is related to tool wear,tool life and machining surface quality.In order to reasonable choice of drilling amount,optimize the parameters,monitor the drilling process to effectively reduce the machining defects,improve the surface quality and production efficiency,a prediction model of ultrasonic vibration drilling force was established to control the size of drilling force.Based on the cutting power flow theory,attempts to establish the drilling force model in the process of drilling.The drilling force is mainly generated by the main cutting edge and the chisel edge,so it is divided into two parts to solve the problem.Then,the mathematical formula between drilling force and feed rate of drilling force coefficient is established,and then the micro element drilling energy consumption model is established.Finally,based on the law of energy conservation,a three-way power model of ultrasonic drilling is established.Verify the ultrasonic vibration drilling force-work model to formulate the ultrasonic vibration drilling experiment program,select parameters and required equipment,set up the ultrasonic vibration drilling experiment platform for different tool diameter,spindle speed and feed single factor experiment,analysis of the three on the drilling force torque unit energy and power.The drilling force,torque and power collected by the experiment are compared with the predicted value of the model to verify the correctness of the model.The chip generation and machined surface during ultrasonic vibration drilling are studied.The titanium alloy was machined in ultrasonic vibration drilling and non-ultrasonic state,and the single factor experiment of tool diameter,spindle speed and feed rate was carried out.The chip morphology under different parameters was compared and analyzed by super depth of field microscope,and the actual chip parameters were measured.According to the experimental results,ultrasonic vibration drilling is beneficial to chip breaking,reducing the friction between cutter and chip,and more conducive to chip discharge.The surface quality of ultrasonic and non-ultrasonic drilling was observed with the help of ultra depth of field microscope and white light interferometer.The single-factor experiment was set to analyze the roughness of the hole,the burr height and the variation of the surface hardness after drilling.At the same time,the stress generated by drilling was studied with the help of simulation software.The experimental results show that the surface quality of ultrasonic machining is better than that of conventional drilling.