Research On Pulse Detection And Control For Micro-hole Electrical Discharge Machining Of SiCp/Al

Because of its excellent properties, Si Cp/Al composite now is widely used in defense and aerospace fields, and in order to reduce mass, dissipate heat, keep air flowing and machine micro-jet, many micro-holes need be processed in Si Cp/Al composite productions. As a kind of efficient methods to machine the micro-holes of Si Cp/Al, Electrical Discharge Machining(EDM) requires the detection and control system of the EDM power possessing higher properties, which not only demands the power could detect the discharge state on time during discharge machining, but also can control the servo parameters, adjust the pulse off and improve the influencing factors automatically online. So, it is significant to improve the machining result by researching on pulse detection and control for micro-hole EDM of Si Cp/Al.Firstly, in the way of introducing principle of EDM and conducting compared experiment, the influence of Si C particles on material removal rate(MRR) and tool wear rate(TWR) of EDM Si Cp/Al composite was analyzed. The experiment result showed that Si C particles play an important role in the MRR and TWR of EDM Si Cp/Al composite, and for conquering the difficulty of Si C particles evacuation, the composite detection and control strategy of pulse expanding and applying sweep pulse was raised.Based on the raised detection and control strategy, the hybrid technology including the average voltage detection and flowing threshold detection was utilized to detect and recognize the discharge state of EDM micro-holes of Si Cp/Al in real time. Then the fuzzy controller, consist with the ARM microcontroller and CPLD, was designed to decide when to expand pulse and apply the high power sweep pulse after receiving the detection message. While in designing the software of ARM microcontroller, the MATLAB was used to model and simulate the fuzzy controller, and then export the fuzzy documents, which were called in IAR System as the fuzzy function. At the same time, a bottom-up style of programming was taken to design the software of CPLD in Quartus II, determining the timing relationship of different control signal.Finally, the result showed that the MRR was improved by 25.52%, the TWR was decreased by 18.24% and the limit depth was increased by 76.69% after using the new kind pulse power.