In a conventional electrolytic machine, liquid electrolyte such as sodium nitrate solution or sodium chloride solution is continuously passed between an electrode and a work at a high speed during machining, so that residual products such as particles of eroded metal from the work, hydrogen gas, and others are discharged from the gap between the electrode and the workpiece and a direct current voltage in the form of pulses is applied between the workpiece and the electrode for finishing the surface of the workpiece.
The applicant of the present invention have proposed electrolytic finishing systems in which a workpiece having a complicated three-dimensional shaped recess is finished by electrolytic machining (see Japanese Patent Application Laid-Open 63-283818 and U.S. Pat. No. 4,800,006). In the system, since an electrode has a surface corresponding to the recessed surface of the workpiece, it is very difficult to center the workpiece with the electrode and a long time is consumed for the centering operation. Japanese Patent Application Publication 62-58850 discloses a centering method in which deflection of an electrode is automatically corrected. However, such a method can not be applied to the system employed with a pair of electrodes consisting of the workpiece having three-dimensional shaped recess and the electrode.
The object of the present invention is to provide a centering method in which the workpiece is a automatically centered with the electrode, thereby reducing operation time for centering.