Development Of High-frequency Microsecond Electroche- Mical Micromachining Pulse Power

ECM (Electrochemical Machining) is a non-contact special processing method useingfor a metal workpiece electrochemical dissolution in the electrolyte to achieve material removal, it has an outstanding advantage in comparison with conventional machining, such as tool electrode without loss, not conductive material properties (hardness, strength, toughness, etc.), limited by the surface to be machined and stress-free heat-affected layer and the like. Studies have shown that HSPECM can greatly improve the molding accuracy and surface quality. And the pulse frequency is higher, the pulse width is narrower, the processing effect is more obvious.The paper developed a microsecond pulse power prototype for studying electrochemical machining process used in a new medical needle hole process.The power supply adopts the DC chopper output form, and set up a quick short-circuit protection system.DC power module is composed of the frequency transformer, the balance reactor with double inverse star rectifying circuit and voltage regulator circuit and other components, enabling the AC to DC conversion.This circuit structure is simple, fast dynamic response, good reliability, and the high voltage regulator accuracy.The chopper in power supply has IGBT module in GB-type as a power switching device, which is driven by single-chip microcontrollers UPD79F9211CPU in the form of trigger pulse to achieve. And the frequency and duty cycle of the power supply’s output waveformcan be adjusted by pulse width modulation. Meanwhile, we make the analysis of failure modes for IGBT module, which is provided with overvoltage protection, overcurrent protection and thermal protection to ensure the power supply which can work stablely, safely and reliably.The power supply prototype is used to explorepreliminarily in the needle hole electrochemical processing test, and orthogonal method is used to optimize the electrical parameters which influences the effect of hole machining. Regardingprocessing time as evaluations, the best parameter combinations aremachining voltage 14V, pulse frequency 40kHz, duty cycle 0.5. Regarding hole length diameter ratio as evaluations, the best parameter combinations aremachining voltage 12V, pulse frequency 30kHz, duty cycle 0.3. The test results not only show that microsecond pulse power supply can meet the processing requirements of the needle hole, but also provethe feasibility of power supply’s design scheme.