Method of mirror-finishing a cylindrical workpiece

摘要

In a method of mirror-finishing a cylindrical workpiece, according to which, with an abrasive matter and an electrolyte disposed at and supplied to each of the gaps between a cylindrical workpiece connected to the anode of a power supply and working electrodes connected to the cathode of the power supply and disposed oppositely to the outer surface or the inner surface of said cylindrical workpiece, an anodic liquation operation by electrolysis performed onto metal in the surface to be treated of the cylindrical workpiece is assisted with an abrasive operation by which anodic passive films generated on the surface to be treated are mechanically abrased by the abrasive matters, whereby the projected portions of the surface to be treated are electrolytically liquated and abrased preferentially, said method is characterized in that an electrolyte in a passive state is used, an electrolytic voltage to be used is in the range from a few volts to about 15 V, the density of an electrolytic current to be used is about 10 A/cm2 or less, the abrasive matter has a water-permeable property, the pressing force of the abrasive matters to the surface to be treated is 0.5 kgf/cm2 or more, the abrasive speed of the abrasive matters is 2 m/s or more, and the cycle which a portion of the surface to be treated is faced to the working electrodes is in the range from 20 to 200 ms. According to the method of the present invention, the outer surface or the inner surface of a cylindrical workpiece may readily, easily and efficiently be mirror-finished so as to have surface roughness of about 0.1 mu mRmax or less with the roundness of a cylindrical workpiece being a few mu m. There is also provided a mirror-finishing apparatus capable of performing a continuous long-term mirror-finishing with improved working efficiency, by abrasive matter feed mechanisms, a swivelling mechanism, a moving mechanism or the like.