| In high voltage electromagnetic riveting process, high discharge frequency leads to short time of rivet deformation and high strain rate of material, so rivet head prones to emerge micro-crack. In order to solve the problems existed in high voltage equipment, a low voltage electromagntic riveting apparatus was designed based on the general scheme. And the research on process property was performed.The charging circuit and the discharge circuit of the low voltage electromagnetic riveting were analyzed and designed. The influence of various parameters on the discharge current was investigated. According to the analysis of discharge circuit, the parameters of the capacitor bank and the charging voltage were determined.According to the fuctions of the low-voltage electromagnetic riveting equipment, design principles of control system was proposed, and control scheme was determined. The control system was designed in the view of PLC as the control core. The control system includes the design of hardware and software. The hardware design includes allocating the I/O port, external circuit wiring diagram, A/D module and the sensor module connected to the circuit. The structural design methods were applied in software design part. Software design was based on the preparation of the program to meet the control requirements to achieve a set of preset voltage, the charging voltage control and the discharge circuit trigger function. Overvoltage, overcurrent and overcharge automatic protection function of the device performance has been further improved in control system design.The experiment of process property was conducted based on the low voltage electromagnetic riveting equipment successfully developed. The effect of electrical parameters and process parameters on the rivet deformation was explored. The experimental results showed that 6 mm rivet in diameter of common materials (luminum, copper,2A16 aluminum alloy and iron) can be deformed by the low voltage electromagnetic riveting equipment. And 8 mm copper rivet in diameter need to rivet twice to meet the requirements of riveting process. The effect of discharge voltage, the system resistance, inductance and riveting times on rivet deformation was obtained. The microstructures of deformtion copper rivets were analyzed. It showed that the deformation of copper rivet do not generate adiabatic shearing in electromagnetic riveting process, but mainly deformed by elongated and broken of grains. |
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