Design And Process Research Of Ultrasonic Additive System For Aluminum Parts

In recent years,Ultrasonic Metal Additive Manufacturing(UAM)technology has become a popular research topic due to its many advantages.UAM boasts a wide range of raw material options,low processing temperatures,and minimal residual stress in parts,making it a promising technology for aerospace and other industries.The solidification mechanism of ultrasonic metal additive manufacturing is not uniform,and there are varying opinions.Additionally,the impact of different process parameters on the performance of additive specimens has been explored during the process.To address these issues,a push-pull type ultrasonic metal additive device with dual transducers was designed specifically for aluminum foil material.This thesis presents the details of this self-designed device.This subject thesis delves into the low-temperature solidification mechanism of ultrasonic metal additive manufacturing.The study utilized finite element analysis software to examine the effects of different process parameters on the material surface’s instantaneous temperature during the additive process.The findings were experimentally validated.The effect of additive process parameters on the performance of specimens was investigated by conducting additive experiments on the commonly used material 8011 aluminum for lithium-ion batteries.The main research contents are as follows:(1)Based on the theory of ultrasonic propagation and relevant mechanical design theory,material selection and structural design were carried out for the transducer,the horn,and tool head of a 20 k Hz,4k W single-ended ultrasonic metal additive manufacturing device.Modal analysis was performed using ABAQUS finite element analysis software to verify its resonant frequency,and ultimately,the ultrasonic metal additive manufacturing device was developed.(2)A coupled thermal-mechanical model was established using ABAQUS finite element analysis software to simulate the temperature field generated during the additive process,and the effects of the three main additive factors,namely,additive pressure,additive amplitude,and additive speed,on the surface temperature of the aluminum foil during the additive process were analyzed.The surface temperature of the aluminum foil increased with the increase in additive pressure and additive amplitude,but decreased with the increase in additive speed.Within the selected range of process parameters,additive amplitude had a greater effect on the surface temperature of the aluminum foil during the additive process compared to the other two factors.The surface temperature measurement experiment during the ultrasonic additive process shows that the minimum instantaneous temperature of the specimen surface during the additive process is 53.7℃,and the maximum value is 133.3℃,both of which do not exceed 1/2 of the material melting point.The trend of temperature changes with various process parameters is consistent with the simulation results,verifying the low-temperature solidification mechanism of ultrasonic metal additives.(3)In order to ensure the optimal output amplitude of the ultrasonic tool head,the effect of the phase difference between the inputs at both ends of the horn on the vibration displacement output of the tool head was investigated using the ABAQUS finite element analysis software.The results showed that the tool head output vibration displacement was best when the phase difference was 0.(4)Microscopic morphology observation of the bonding interface and mechanical performance testing of additive manufactured specimens were carried out.The reasons for the formation of point,pit,line and vortex defects were summarized.The effects of three factors,namely additive pressure,amplitude and velocity,on the mechanical properties of the specimens and the instantaneous temperature of the aluminum foil surface during the additive process were analyzed.Within a certain range of parameters,both additive pressure and amplitude were linearly positively correlated with the mechanical properties of the specimens and the instantaneous temperature of the aluminum foil surface,while additive velocity was linearly negatively correlated with them.Among them,the impact of additive amplitude on the solidification quality of the specimens was significant.The minimum surface roughness value was 2.415μm;the maximum microhardness value of the bonding interface was 33.5HV,which was 67.5% higher than the original hardness of the material;the maximum tensile strength was 43.38MPa;the maximum bending strength was262.2MPa.