Experimental Study On ELID Grinding Of The Si₃N₄Ceramics Spherical Parts

ELID grinding technology is widely performed in the manufacturing of hardbrittle material at the regions of aerospace, IT electronics, machinery, optical,automobile, instruments and so on because of its characteristics of high processingefficiency, high quality precision, easy design of the device and wide adaptability etc.In this paper, a typical heat resisting Si₃N₄ceramics spherical parts which used inaerospace defense weapons was studied. According to the high efficiency, high quality,less/none damage processing requirements, the Si₃N₄ceramics spherical parts of theELID grinding experiment and theoretical has been researched.An electrolysis electrode device accommodating to CNC jig grinding machinewas designed, an ELID experimental platform based on precision CNC jig grinders ofspherical surface grinding MK2945C was built, a method to realize the grinding wheeltracking method of Si₃N₄ceramics spherical shape ELID grinding process as well asthe writing and checking of spherical forming CNC program code was studied.The small diameter iron-based diamond fine grinding wheel was shaped by theelectrolysis-mechanical compounding method which effectively eliminated thegrinding wheel eccentric error and roundness error; The taguchi experimental designmethod was used to analyze the influence of ELID grinding wheel pre-dressing in thethickness of the oxide film and pre-dressing time. The study demonstrated thatthe higher quality of the oxide film can be obtained in minimum amount of time asthe grinding wheel speed was6000r/min, the Pulse frequency is200kHz, the DutyRatio is0.7and the voltage was90V, It was beneficial to the parameter selection andtheoretical guidance of ELID grinding process.Through ELID grinding process experiments with the following five process ofcontrol strategies including electrolysis grinding dynamic balance, electrolysis activecontrol, electrolysis grinding cross, grinding active control and radial feed activecontrol. It was concluded the optimal combination strategy of ELID grinding process,which was using electrolysis active control strategy in the rough grinding phase of theELID grinding mainly to remove processing materials, the fine grinding phaseapplying active control strategy was to remove scratches and reduce surface andsurface damage for the priority, the buffing phase with radial feed active controlstrategies was mainly for polishing.The electrolytic parameters and technological parameters on the surface roughness of the influence law has been studied, the surface roughness of workpieceincreased with the increasing of voltage and the grinding depth, but opposite to thepulse frequency, with the occupies empties increased, the surface roughness ofworkpiece decreased, when occupies empties beyond0.7, the surface roughnessincreased, with the increasing of speed, the surface roughness of workpiece increased,when speed more than12000r/min, the surface became more rough.The comparison and analysis between the ordinary precision grinding and ELIDgrinding in surface roughness of workpiece and surface morphology demonstrated thatthe ELID grinding was not only improve the processing efficiency, but also greatlyreduced the surface of workpiece and surface damage and got a higher processingsurface quality as well.