METHOD FOR ELECTROEROSION-CHEMICAL PIERCING OF HOLES OF SMALL DIAMETER AND DEVICE FOR ITS IMPLEMENTATION

摘要

FIELD: technological processes.;SUBSTANCE: invention relates to the field of electrophysical and electrochemical machining methods, mainly to piercing holes of small diameter in parts from high-strength and hard steels and alloys. Proposed method comprises billet processing in flow electrolyte at electrode-tool movement in billet direction and performing electroerosion and electrochemical removal of billet material by means of periodic feed of initiating pulses and the following power pulses to inter-electrode gap. At the electroerosion removal of the material, the erosion hole is produced in the workpiece, the diameter of which exceeds the diameter of the working end of the tool electrode by selecting values of the amplitude and duration of the discharge current in the initiating pulse, determined from the conditions: 0.8K_md_e²/(K_fI_a√t_i)K_m, where d_e is diameter of working end of electrode-tool; K_f is current pulse form coefficient; I_a is a discharge current pulse amplitude; t_i is duration of discharge current in initiating pulse; K_m is empirical coefficient, and for electrode-tool from tungsten and workpiece from chrome-nickel steel K_m=0.21⋅10^-6 m²/As^0.5, and electrochemical removal is carried out using power pulses of bipolar current, and before each power pulse of direct current of high density is fed pulse low-density reverse current.;EFFECT: providing, when piercing holes of small diameter, high quality of the surface of holes at high rate of piercing of 100 mm/min and more, by ensuring absence of a layer with a modified structure, burrs and sharp edges at R_a 0,2–0,8 mcm.;10 cl, 11 dwg