Patent attributes
An ECM apparatus includes a stationary cathode tool having a passage, and a drive mechanism for moving a bar-shaped workpiece through the passage of the cathode tool while simultaneously rotating the workpiece. Electrolyte flows, from a manifold on one end of the cathodic tool to a manifold at the other end, through the passage, between the wall of the passage and the workpiece. An electric current is simultaneously established in the electrolyte, between the wall of the passage and the workpiece. The internal shape of the cathodic tool wall has a gradual transition from a circular entry opening to a lobed exit opening, and lobes formed in the wall of the tool are shaped so that they twist in the direction of workpiece rotation, in order to form helical lobes in the workpiece.
