The Research Of Composite Processing Technology Of The Oil Casting Using Micro-edm And ECM

The problem of how to prevent sand from developing the oil and gas fields has plagued us for a long time. Now the rectangular slit sand screens are widely used in the fields. The main processing screen are mechanical cutting and laser processing. The former has relatively low surface quality and precision; the latter easily leads to sticky residue, poor "match head", bad surface quality and high cost of production. Meanwhile there is a serious problem of sand blocking in rectangular screen. In order to solve this technical problem, the composite processing of EDM and ECM is used in the trapezoidal slotted screen processing. Compared with the original rectangular screen, the trapezoidal slotted screen has low flow resistance for the crude and terrific “self-cleaning” influence, getting rid of the the easily clogged problem of rectangular screen.In order to meet the trapezoidal slotted processing, the subject design the special machine for slotted screen, using the composite of EDM and ECM. For the purpose of complex power requirements, this paper proposes the combination of tip high-voltage pulse and direct-current low voltage. By applying an alternating magnetic field, controlling the movement of electronics, the slots with “narrow top and wide bottom” is successfully processed. The working fluid circulation system using strong magnets like star, solves the cooling problem of the electrode disk during processing, and improves the utilization efficiency of it. Stepper motor’s automatic regulating system can dynamically maintain a stable discharge gap, ensuring a stable discharge machining process.This paper also optimizes the composite processing technology, the qualities of the slots evaluated through three indicators-slots width, processing efficiency and surface roughness. The influences of electrical parameters(pulse width, pulse interval, duty cycle and processing polar) and non-electrical parameters(electrode disk rotational speed, rotational direction and oil speed) on slots width were studied respectively and the optimal process parameters were obtained. The best processing parameter of this machine is: positive polarity processing, duty cycle 0.6(pulse width 45μs, pulse interval 30μs), the electrode plate forward 400r/min, washed oil rate 100L/min. The paper proposes failures of circular electrodes and mainly explores the influence of pulse width, it is concluded that big pulse processing can prolong the life of the electrode plate. The microstructure of screen from inner to outer is melting layer, heat effect and parent metal in turn. The paper mainly studys the effect of pulse width, concluding that the melting layer thickness increases with the pulse width.