Research On Forming Mechanism Of Friction Stir Welding Based On Mechanical Signal

During the friction stir welding,one of the main factors impact on the quality of welding is the force from the tools.At present,the domestic has not responded about the force testing and research.In this study,according to the experimental needs Self-designed experiment measuring table for detect mechanical signals.In order to ensure accuracy and reliability of the measured data.First,design of the mechanical signal detection table in accordance with the pressure sensor size.Pressure sensors will be installed in its respective position on the selected.Installed for two pressure sensors on the axial direction place,one pressure sensor before and after the Vertical direction place,two pressure sensors on the left and right lateral direction place.So that in the before and after,left and right of the table,as well as the bottom part have a very good point contact with pressure sensors.Using of data acquisition system,Real-time detection the longitudinal force and the forward force of the pin role in the Welded panels.For friction stir welding process of different materials,such as 2A12,3A21,5A02 aluminum alloy,and H62 copper alloy with different thickness,has studied an impact of welding parameters over the longitudinal force and the forward force of welding. Have got the change in law of the longitudinal force and the forward force. Experimental results show that while welding different materials under the same welding parameter,the longitudinal force and the forward force are different. Meanwhile,when welding the same species material Under the different welding parameters,the longitudinal force and the forward force are also different.The experiments proved that the longitudinal force increase with press speed and press in amounts increases,and decrease with the rotate speed adds.The main factor that influence the longitudinal force is rotate speed,press in amounts and press speed.At the same rotational speed conditions,the forward force increases with the welding speed increase.At the other parameters are unchanged,the forward force increases with the press in amounts increase;With the rotation speed increases,the forward force first increases and then decreases.With the pin length and the diameter increases,the forward force increases.In addition,studied the longitudinal force impact on the weld surface forming.Experimental results show that while the longitudinal force at a certain range(from 4000N to 8500N),the weld surface forming more and more good witht the longitudinal force increase. With the finite element analysis software Deform-3D.For the longitudinal force changes,by 3-D numerical stimulation and finite element analysis has studied an impact on temperature distribution and stress-strain field.The results show that, Start-up phase in the weld,the longitudinal force no impact on the changes in equivalent stress.At Welding start-up stage,the maximum equivalent stress appear in the materials around the pins.the equivalent stress of the materials below Shoulder followed,On the edge of the Weld materials effect to be relatively small.As for welding,the highest temperature appear in the materials around the pins,and the equivalent stress is also the smallest.And welding in a stable stage,the longitudinal force has little effect on the distribution of equivalent stress,However,the size of equivalent stress changes greatly affected.The simulation results show that the longitudinal force directly affects the quality of the weld shape.Under low pressure can not be forming a good weld.The simulation results and actual results are basically the same as welding.This study further analysis of the factors influence the formation of the weld.It had practical value to ascertain welding parameter,optimize processing technology, control the microstructure and quality of the joint.