Research On The Friction Stir Welding With Axial Vibration

Ultrasonic friction stir welding is based on friction stir welding, and at the same time, an additional ultrasonic longitudinal vibration is added to the stirring head. It is designed to use the small axial displacement with high frequency to upsetting the extrusion effect of friction stir weld and use the impulsive force with high frequency to improving the upsetting force of stir head. Previous research show that the ultrasonic vibration-fsw can effectively improve welding processing efficiency owing to the impact of high frequency pulsing force. In this paper, by comparing the ultrasonic vibration friction stir welding and traditional friction stir welding, combining the effect of ultrasonic vibration, analyze the influence of ultrasonic vibration in improving the upsetting force of stirring head and its positive effects.In order to further study the application of ultrasonic vibration in friction stir welding, in this paper, the design model of ultrasonic system is established based on the theory of one-dimensional vibration of variable cross-section rod theory and design theory of ultrasonic system. Then, the theoretical analysis and deduction are carried on. In order to study the dynamic characteristic of ultrasonic vibration system, the finite element model is established and ANSYS is used to make a dynamic analysis of ultrasonic vibration system, including the modal analysis to ensure the design and harmonic responding analysis ensure the output amplitude and the amplification characteristics of ultrasonic transformer.In the last part, the movement characteristics and mechanical properties of stir head in the process of welding are analyzed, and the influence of ultrasonic vibration on friction are deduced. In order to analyze the upsetting force in the welding process, the finite element software Deform is adopted. Through the comparison of the results, the impulsive force resulting from ultrasonic vibration achieve the positive effects on improving upsetting force. At the same time, the impulsive force can immediately function on weld seam to ensure the mechanical its properties when the axial ultrasonic is added, and the other stirring is also added-the axial small displacement stirring with high frequency.