Research On Power Supply And Adaptive Control For Enameled Wire Resistance Spot Welding

With the development of welding automation and intelligence,more and more high requirements are put forward for inverter resistance spot welding power supply.High performance power supply needs to have rich welding process monitoring function and welding state adaptive ability.Multi information monitoring can identify welding problems,automatically screen unqualified welds,and it is also the premise of parameter adaptive adjustment.Adaptive adjustment can improve power stability,output consistency and welding quality,both of which are conducive to reducing manual participation,reducing the operator's experience and technical requirements,and improving welding efficiency.In this paper,an inverter resistance spot welding power supply with multi information sensor monitoring is designed,including the real-time acquisition of welding current,electrode voltage,electrode pressure and displacement information,the calculation of welding power and dynamic resistance.The synchronous sampling,storage and display of six important process information in the welding process,and the dynamic or static envelope monitoring of each information are realized.The power supply has four basic control modes:constant pulse width,constant current,constant voltage and constant power mode,it also has two kinds of external communication functions,RS485 and Wi Fi,and the communication service program of upper computer is designed,which can realize the simultaneous acquisition of multi welding process data by one upper computer.In practical application,the electrode of enameled wire spot welding has the problems of constant wear and frequent replacement during its service life,which affects the output response of power supply and welding quality,so it is necessary to adjust the control parameters manually.In order to solve this problem,this paper carried out the electrode wear welding test,analyzed the corresponding relationship between the electrode wear state and the parameters of enameled wire spot welding,and initially put forward the self-adjusting method of welding parameters based on the identification of electrode end wear,which can reduce the dependence on manual adjustment and the product quality problems caused by untimely adjustment to a certain extent.The dynamic resistance information of electrode wear process and its influence on constant voltage control were obtained.At the same time,an expert intelligent PI self-tuning method based on pattern recognition is proposed and integrated in the power supply.Combined with the envelope monitoring strategy,the problems of inconsistent control response and even output waveform oscillation caused by electrode change are effectively solved,the stability and consistency of power output are improved,and the rise time is shortened,which can better meet the requirements of some short-time rapid spot welding process requirements.