1986 年 52 巻 7 号 p. 1218-1223
Aiming at trimming and boring of steel material under water pressure, the effect of water pressure affecting the discharge phenomena was investigated by testing underwater single discharge under the hydrostatic pressure of 7.95 MPa. The result indicates that the effect mentioned below is appeared when capacitor charging voltage of 250 V DC is given to between a brass electrode in vibration of 32 Hz and a sample piece of S 45 C by increasing water pressure gradually. (1) Crater diameter of the sample piece becomes somewhat smaller while crater depth becomes deeper than the water level by about 25% at 7.95 MPa. (2) Both crater and upheaval sectional area are increased. Net displacement of the sectional area is slightly increased. On the other hand, no change due to water pressure is found on the wave forms and magnitudes of the discharge gap voltage and discharge current.