Development Of Closed-loop Feedback Controlling Micro Friction Stir Welding Machine

Due to the rapid development of electronic technology,components and parts can be made in the miniature original size,and the demand for micro-connection technology is also growing in the industrial system.Except the welding of conventional thickness plates,research work on micro friction stir welding(?FSW)for thin plates and ultra-thin plates(t < 1 mm)is currently very limited,in which there is still much room for exploration.Due to the thin thickness of weldments,the weld forming and joint quality are extremely sensitive to the change of the process parameters.As a result,the friction stir welding equipment must have extremely high positioning accuracy,processing accuracy,machine stability and response speed of the numerical control system.In this paper,a micro friction stir welding machine was designed,including the overall design of mechanical structure,motion system and the control strategy with hardware circuit of the numerical control system.And a real-time monitoring equipment was developed to measure the various physical signals affecting weld formation and joint quality,and to realize the real-time monitoring and closed-loop feedback control of the welding process.Based on the general requirements,a typical micro friction stir welding machine was developed through the selection,installation and debugging of the planned friction stir welding equipment,including the rotating spindle,X,Y,Z feed shaft,drive control circuit of each axis and numerical control system.The machine has small deformation,good dynamic and static stiffness of the mechanical structure.Every feed unit of the machine can maintain a stable state in low speed.The welding machine structure has a high stability overall.A set of functional control strategy and numerical control system scheme were equipped for the micro friction stir welding machine.The welding process was standardized through traceable numerical control programming.The parameters of numerical control software and every driver of axes of motion were set and debugged.The machine can correctly weld the workpiece with accurate positioning because of the respond of any preset parameters,and has a good overall stability during the welding process.By developing the LabVIEW function module,the accurate real-time measuring of the various physical signals and closed-loop feedback control on the welding parameters affecting weld formation and joint quality during the welding process are provided,which helps the micro friction stir welding test proceed with the preset parameters by using of the welding machine.Finally,the closed-loop feedback controlling micro friction stir welding machine is used to carry out the welding test under different process parameters.The welding machine has a good running stability,which can ensure the repeatability and stability of the welding process.And the closed-loop feedback control of the welding process improves the quality of the weld,so the manufactured welding machine can be used in practical industrial production and manufacture.