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: 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: A drive head for a bolt, fastener, coupling, nut or other driveable head made from a less malleable metal such as a powder metal nickel alloy. The drive head has an upper drive portion having at least six convex corners spaced around the outer periphery thereof, each corner terminating in an edge. The drive head also has a lower flange portion adjacent to the drive portion and having an edge extending radially outwardly to at least the edge of each corner. The drive portion and the flange portion of the drive head is formed by subjecting a blank having a generally circular head to electrochemical machining (ECM). A tool is also provided for the ECM method to form the drive portion and flange portion of the drive head.

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 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.