Development Of A New Type Capacitor Energy Storage Stud Welding Machine

With the rapid development of industrial technology,new requirements have been put forward for the processing technology of connecting metal studs or similar fasteners to plates or pipes.A new welding method,stud arc welding,has been developed.Among them,arc stud welding is mainly used for stud welding of medium and thick plates,while capacitor energy storage stud welding has more advantages for thin plates.Capacitor energy storage stud welding completes the stud welding process by releasing the energy stored in the capacitor bank.It has the characteristics of short welding time(0.8-3ms),small heat-affected zone and high production efficiency.It is suitable for welding stud or columnar metal with diameter of 2-10 mm to thin plates with diameter of 0.6-3mm.The traditional capacitor energy storage stud welding machine has large volume,heavy weight and low control precision.To solve the above problems,a new type of capacitor energy storage stud welding machine is designed.Firstly,the capacitor energy storage stud welding machine is designed from two aspects of mechanical structure and circuit structure.The mechanical structure mainly includes the structure design of the welding machine and the gun.The circuit structure includes power conversion circuit,control circuit and driving circuit.In the design of power conversion circuit,the single-ended forward circuit with RCD clamp is chosen as the power conversion circuit topology,and the shape and size of the main transformer and the number of turns and diameter of the primary and secondary side windings are designed and selected.According to the functional requirements of the power conversion circuit,IGBT is chosen as the power switch,the input and output rectifier filter modules are designed,and the large capacity capacitor bank is selected according to the energy storage requirement.The control circuit is mainly used to control the capacitance charge and discharge and to ensure the normal operation of the welding machine.In order to ensure the accuracy of control circuit,the real-time and reliable,choose PIC16F1782 microcontroller as the master control chip to control and monitor the working state of the welding machine in real time.Based on the microcontroller,the circuit of voltage detection circuit,contact detection circuit,welding torch control circuit,capacitance discharge circuit and parameter display circuit are designed.In order to achieve constant current capacitor charging,SG3525 is selected as the pulse width modulation chip to adjust the output pulse width,and TLP250 was selected as the IGBT driver chip.In order to improve the control function of MCU,the software program structure of the control system is designed,which mainly includes the main program and the subroutines to realize each control function.The interference in the software and the commonly used anti-interference measures are analyzed.The waveforms of discharge current and arc voltage during the welding process are tested,which conform to the ideal waveform when the welding quality is optimum.In order to verify the rationality of preset voltage,welding tests under different voltages were carried out,and the rationality of parameters was verified by a series of process tests.