Abstract: 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.

Abstract: Electrochemical machining is used to generate the helical lobe profiles of the stator of a progressive cavity pump or motor. A thin, elastomeric liner, of uniform thickness is bonded either to the interior of the stator, or to the exterior of the rotor. Where the elastomeric liner is to be bonded to the interior of the stator, bonding is improved by electrically etching the interior of the stator during the electrochemical machining process to produce a roughened surface.

Abstract: An ECM apparatus includes a fluted cathode tool for being driven through a tubular workpiece for electrochemically forming internal flutes therein. The cathode tool is sealed at one end for isolating electrolyte over the flutes thereof to seal against flow of the electrolyte past the tool and into the finished fluted bore.

Abstract: A slave assembly is provided to protect an anodic workpiece joined to a shuttle from stray electrochemical machining. The assembly includes a slave having a support flange joined integrally with a sacrificial flange positionable adjacent to the workpiece for being electrochemically machined along with the workpiece to prevent stray electrochemical machining between the sacrificial flange and the workpiece. A retainer is positionable on the slave support flange to clamp the slave to the shuttle.

Abstract: An apparatus for electrochemically machining a workpiece having first and second platforms and an airfoil extending transversely therebetween includes a first cathode trio having a center cathode disposed between first and second cathodes. The center cathode is configured for electrochemically machining a first side of the airfoil, and the first and second cathodes are configured for electrochemically machining at least the first and second platforms adjacent to the airfoil first side. The first and second cathodes are movable relative to the center cathode so that they move away from each other and toward the opposing platforms during machining. A second cathode trio is provided for electrochemically machining the airfoil second side.

Abstract: A machine for electrochemically machining (ECM) a workpiece having a stacking axis and first and second opposite sides includes a pair of cathode tools. The first and second tools have first and second longitudinal axes, respectively, disposed substantially perpendicularly to the workpiece stacking axis. The first and second tools also include the first and second transverse axes, respectively, disposed perpendicularly to the first and second longitudinal axes, respectively, and substantially parallel to the workpiece stacking axis. The machine is effective for practicing an improved method of moving the first and second tools along the first and second longitudinal axes and along the first and second transverse axes, respectively, toward the workpiece for the electrochemical machining thereof. By moving the respective cathode tools along both longitudinal and transverse axes, a selectively variable resultant feedrate direction is obtained which is inclined relative to the workpiece stacking axis.