Multi Physical Information Coupling Of Micro Plasma Arc Welding

The arc of micro plasma arc welding is compressed by small aperture compression nozzle,so the high stability,stiffness,density arc can be used for welding of ultra-thin ultra-fine structures.When ultra-thin plate(thickness less than 0.2mm)is welded by pulse micro plasma arc welding,the weld surface is smooth and uniform,the average grain size is small,and the forming quality is good.However,the pulse micro plasma arc welding of thin plate is prone to deformation,burn and other defects,so the analysis of factors affecting deformation and burning through in micro plasma arc welding of thin plate is very important to the quality control of welding process.In order to solve the problems of deformation and burning through in the process of pulsed micro plasma arc welding,a real-time synchronous acquisition method is adopted to synchronously trigger various detection devices through an external synchronous trigger circuit,the welding current,welding voltage,arc,weld pool,deformation,welding seam of the ultra-thin plate welding process of pulse micro plasma arc welding were collected by the real time synchronous acquisition system.And the diameter of the arc at the bottom,the intensity of the arc light radiation,the characteristic parameters of the weld pool profile,the rotational deformation of the joint,and the deviation of the weld seam were extracted by the method of image processing.Firstly,the non-synchronization of multi-phase physical information of pulsed micro plasma arc welding was studied.The reasons for the non-synchronization were as follows.Due to the limitation of the circuit components,there was a delay between triggering the synchronous signals of the various detecting devices,and therefore the synchronization signals received by various detecting devices were asynchronous.The detection position of the deformation of the welding position at a certain time is ahead of the position of the welding point at this time.Secondly,the non-synchronization of multiphase physical information in pulse micro plasma arc welding was studied.And the studies show that,the heat input power of peak current decreases with increasing base frequency,duty ratio and frequency,and the input power of base current increases with the increase of base frequency,duty ratio and frequency.The range of heat input of peak current decreases with the increase of the duty cycle and increases with the base current,while the heat input range increases with the duty cycle at the peak current.The change of base current is very small,and the change rule of large base pulse is opposite to that of base pulse.With the increase of frequency,the range of heat input decreases and the value of base current increases.The characteristic parameter of the molten pool is larger when the duty ratio is small,and the characteristic parameter of the molten pool is big and similar when the duty ratio is large and medium,and the characteristic parameter of the bath decreases with the increase of the frequency and the ratio of the base veins.The multiple regression analysis was used to calculate welding heat input power,welding heat input range and the coupling relationship of weld pool characteristic quantity and welding P-MPAW welding current.The regression equation was tested for significance and residual and correlation coefficient were anayzed,and the results show that the regression equation of the correlation is more significant,high reliability.Finally,In order to solve the problems of easy burnout,welding bias,welding impermeability and deformation in the welding process,the quality inspection of welding center and the deviation of welding center alignment were calculated.Then,the quality control of P-MPAW based on weld torch offset adjustment was achieved,the result shows that according to the relationship of multi physical information coupling,coordinated control of welding quality which ensure the same width based on multi information coupling was realized.