Stability Evaluation For Carbon-dioxide Arc Welding Based On The Input Electrical Signal

Carbon-dioxide arc welding been wildly employed in automobile manufacture,ship construction,and petrochemical industry,owing to its high efficiency,energy saving,low hydrogen,low cost,and easy to realize automation.1 However,in actual welding process,the mismatched welding parameters often lead to instability of the welding process,which seriously deteriorate the mechanical property of welding joint.Therefore,it is of critical importance to investigate the stability of short circuiting transfer process,thus to discern the property of welding joint and avoid the application of bad welding joint in actual manufacture.Lately,many methods have been presented to evaluate the stability of short circuiting transfer process based on the welding electrical signals(voltage and current)and these works have shown some promising results.However,almost of methods were monitored the output terminal electrical signals of arc welding machine,but the input terminal is lack of focus.The electrical properties affect a lot by the input terminal which supplies energy to the welding machine.As a result,there is an obvious mutual relationship between the input terminal and the output terminal.Besides that,judging the stability of a welding process by its input terminal could not only broaden the means of welding procedure qualification,but also beneficial to the integration and modularization of the related stability evaluation system.Therefore,this evaluation method has great theoretical significance and application value.An experimental platform of carbon-dioxide arc welding is established,which is used to measure input power.An algorithm for instantaneous input power is introduced.Output current and input pulsatile energy is determined as study project for output and input terminal respectively.By comparing waves of output current and input pulsatile energy,it is found that the variation trend of them is basically the same.An algorithm of short circuiting transfer frequency is introduced based on output current and input pulsatile energy.With different wire feeding speed,welding voltage and wire extension,by comparing short circuiting transfer frequencies calculated by input and output terminal,it can be concluded that the variation trend of them is basically the same.Besides,correction coefficient between them is calculated,which indicates that there is a very strong linear correlation between them.For different transfer modes,variation coefficients of the output current and the input pulsatile energy are calculated.The results show that they not only share the same variation trend but also have very strong linear correlation,which demonstrates that the stability of carbon-dioxide arc welding can be evaluated by the variation coefficient of input pulsatile energy.