Investigation On Ultrasonic Vibration-assisted Plastic Deformation Behaviors And Micro-blanking Mechanism Using TA2 Pure Titanium Foil

With the rapid development of the micro electro mechanical systems(MEMS) and the micro system technology(MST), the demands for high-accuracy micro-parts of the foil with high quality and dimensional precision are more and more urgent. In this paper, a new technology of forming foil micro-parts is presented in which ultrasonic vibration is superimposed to the metal foil micro-blanking process. The superposition of ultrasonic vibration could make metal foil exhibit the deformation behavior different from conventional deformation and previous research has shown that ultrasonic vibration can improve the final quality of the micro-parts. In this paper, the experiments of micro-forming with ultrasonic vibration-assisted using TA2 pure titanium foil are carried and the research for the influence on the deformation behavior of ultrasonic vibration is developed.To study the effect of ultrasonic vibration on micro-tensile deformation behavior of TA2 pure titanium foil, the experiments of ultrasonic vibration-assisted micro-tensile using TA2 pure titanium foil with a range of grain sizes are conducted. The law of softening effect is revealed. That’s to say the superposition of ultrasonic vibration could reduce the flow stress of TA2 titanium foil in the experiment, showing a softening effect on metallic materials. In addition, this effect on TA2 pure titanium foil with smaller grain size is more obvious. The experiments of ultrasonic vibration-assisted micro-tensile with a range of amplitudes using TA2 pure titanium foil are conducted. It’s found that with the increase of amplitude, the flow stress decreases and the brittle fracture occurs gradually. Under different strain rate conditions, the influence of ultrasonic vibration on the deformation of TA2 pure titanium foil is different.In order to predict the influence of ultrasonic vibration on micro-blanking, the finite element simulation analysis is conducted. ABAQUS is used to simulate the blanking process-assisted by ultrasonic vibration. It’s found that The combination of appropriate frequency and amplitude can reduce the height of the burr and increase the proportion of the bright band, improving the quality of the cross section. The superposition of ultrasonic vibration in the blanking process could make effects on the distribution of stress. The superposition of ultrasonic vibration could make the larger tensile stress existing in deformation regions transfer to the intermediate zone of the deformed material in vertical direction and delay the initiation of the crack. However, the ultrasonic vibration makes the crack propagation accelerates.The integrated ultrasonic vibration-assisted blanking punch in which the blanking punch is connected with the ultrasonic transducer rigidly is designed and the mould device used for ultrasonic vibration-assisted TA2 pure titanium foil blanking experiments is developed. A series of experiments are carried with the developed device. It’s found that the superposition of ultrasonic vibration could increase the proportion of the bright band which is coincided with the finite element simulation results. And this effect on the foil with smaller grain size is more obvious. But the roughness of the bright band presents an increasing tendency when the ultrasonic vibration is superposed to the blanking process. In addition, the superposition of the ultrasonic vibration increases the tear toughening nests and decreases shear toughening nests on the fracture surface. The experiments of ultrasonic vibration-assisted micro-blanking using TA2 pure titanium foil with a series of blanking speeds are carried. The results show that with the increase of blanking speed, the proportion of the bright band increases firstly and then presents a decreasing tendency. When the ultrasonic vibration is superposed, the proportion of the bright band increases and the effect is more obvious when the blanking speed is smaller. The research for the crack spreading angle is conducted and it’s found that the superposition of ultrasonic vibration could increase the crack angel with the vertical direction which leads to greater tearing deformation in the fracture stage.