An ECM method involves the use of a thin hollow electrode assembly that carries the electrolyte within and that is advanced relatively to the workpiece. The small profile of the electrode results in a minimal removal of metal in forming the desired rotor or stator shape. The electrode profile allows significant power consumption reduction or increased machining speed for a given rate of power input. The electrode can be a unitary ring shape or can be made of segments that are placed adjacent each other so that a continuous shape is cut. Not all the lobes of the stator or rotor have to be cut in the same pass. Electrode segments can be used to sequentially provide the desired lobe count in separate passes. The lobe shapes in the electrode can be slanted to get the desired rotor or stator pitch or they can be aligned with the workpiece axis.

A machine for machining a workpiece having a first central longitudinal axis passing through a workpiece plane that is disposed orthogonally relative to the first central longitudinal axis is provided. The machine includes a chuck or fixture on which the workpiece is disposable, a grinding spindle having a body, a wheel supporting an abrasive and an insulator electrically isolating the wheel from the body, the wheel being operable to remove material from the workpiece, the grinding spindle having a second central longitudinal axis about which the grinding spindle rotates, the second central longitudinal axis of the grinding spindle passing through the workpiece in the workpiece plane so as to create a continuous gear tooth on the workpiece and an electrochemical grinding (ECG) element configured to execute ECG processing on the grinding spindle and the workpiece to soften the workpiece as the gear tooth is being created by the grinding spindle.

An electric discharge machining electrode is shaped to form a die for roll forming a dual threaded screw. The electrode is oriented with a face thereof adjacent to a forming surface of the die and placed within an electric discharge machine to cause electric discharge via the electrode to the forming surface of the die, to shape the die to have the geometry required for roll forming of the dual threaded screw. The EDM electrode face has a plurality of troughs and tips substantially matching coarse threads of the screw. Grooves are formed in the tips. The grooves are angled relative the tips and have a geometry substantially matching the fine threads of the screw. The face of the electrode has a form which shapes the forming surface of the die so that the die can roll form the dual threaded screw.

A machine for machining a workpiece having a first central longitudinal axis passing through a workpiece plane that is disposed orthogonally relative to the first central longitudinal axis is provided. The machine includes a chuck or fixture on which the workpiece is disposable, a grinding spindle having a body, a wheel supporting an abrasive and an insulator electrically isolating the wheel from the body, the wheel being operable to remove material from the workpiece, the grinding spindle having a second central longitudinal axis about which the grinding spindle rotates, the second central longitudinal axis of the grinding spindle passing through the workpiece in the workpiece plane so as to create a continuous gear tooth on the workpiece and an electrochemical grinding (ECG) element configured to execute ECG processing on the grinding spindle and the workpiece to soften the workpiece as the gear tooth is being created by the grinding spindle.

A worm wheel is provided in which a step is not formed near a tooth face meshing with a worm, and noise does not easily occur during power transmission. A worm wheel 1 includes a circular arc-shaped tooth section 5 that is a portion meshing with a worm 101 and configuring a circular tube worm gear, and a helical tooth section 4 that is connected to one end side of the circular arc-shaped tooth section 5. An angle of torsion at an arbitrary reference point 14 in a tooth depth direction of a tooth 3 on a boundary 7 between the circular arc-shaped tooth section 5 and the helical tooth section 4 is equal to an angle of torsion at a second reference point 15 corresponding to the first reference point 14 in the tooth depth direction of the tooth 3 in a diameter portion P0 of a throat of the circular arc-shaped section 5. As a result, a step is not formed on a tooth face on the boundary 7 between the circular arc-shaped tooth section 5 and the helical tooth section 4. A tooth face of the circular arc-shaped tooth section 5 and a tooth face of the helical tooth section 4 are smoothly connected.

A machine for machining a workpiece having a central longitudinal axis is provided. The machine includes a chuck or fixture on which the workpiece is disposable, a grinding spindle to remove material from the workpiece, the grinding spindle having a central longitudinal axis about which the grinding spindle rotates and being disposed with the central longitudinal axes intersecting one another so as to create a continuous gear tooth on the workpiece and an electrochemical grinding (ECG) element configured to execute ECG processing on the grinding spindle and the workpiece to soften the workpiece as the gear tooth is being created by the grinding spindle.