Patent ID: 7479214

Claim:
An apparatus for electrochemical trepan machining of a workpiece having a large length-to-diameter ratio, to a desired product, the apparatus comprising: a cathodic tool having a through passage for receiving a workpiece, the passage having an entry opening and an exit opening, the entry opening corresponding in shape to, and being slightly larger than, the cross-section of the workpiece, and the exit opening corresponding in shape to, and being slightly larger than, the cross-section of the desired finished product, the cross-sectional shape of the through passage having a gradual transition from the shape of the entry opening to the shape of the exit opening, along the length of the through passage; a manifold connected to the cathodic tool adjacent one of said entry and exit openings for directing electrolyte through said through passage of the cathodic tool, about a workpiece moving through said through passage; a drive mechanism that moves the workpiece through said passage of the cathodic tool and said manifold, such that a first amount of material may be removed from a first predetermined portion of the workpiece at a first rate of removal and a second amount of material may be removed from a second predetermined portion of the workpiece at a second rate of removal; supports for holding the workpiece as it moves through the cathodic tool; and an electric power supply connected to the cathodic tool and connectible to the workpiece, wherein the drive mechanism stops the movement of the workpiece through the cathodic tool at a predetermined position along the workpiece, wherein the stop of the movement of the workpiece provides a bearing journal.