Worm polishing method and device thereof

A worm polishing method for polishing tooth faces of a gear tooth of the worm with a polishing tape, comprising the steps of:

• rotatably retaining a worm and rotating the worm about a rotational axis of the worm;
• continuously or intermittently transferring the polishing tape from a source to pass proximate to the worm;
• inserting and retracting the polishing tape into and from a tooth space between opposing tooth faces of the worm by a pressure contact roll, wherein a rotational axis of the pressure contact roll is tilted corresponding to a tooth lead angle of the tooth space of the worm, and the polishing tape is transferred and guided along a perimeter of the pressure contact roll, wherein the pressure contact roll has a tapered peripheral edge defined by a top edge and a pair of slant edge faces on a periphery of the pressure contact roll, and the polishing tape is bent into a substantially V-shape in cross section by the tapered peripheral edge of the pressure contact roll forming a bent portion of the polishing tape along each of the slant edges;
• swinging the pressure contact roll transversely across the tooth space of the worm;
• alternately advancing and retreating the pressure contact roll along the rotational axis direction, and alternately pressure contacting each of the bent portions of the polishing tape against the tooth faces on opposing sides of the tooth space of the worm;
• moving the polishing tape along an axial direction of the worm;
• synchronizing a rotating speed of the worm with a moving speed of the polishing tape such that the polishing tape tracks a lead of the tooth space of the worm;
• whereby the tooth faces of the worm are polished by a combined operation of the rotation of the worm, the transfer of the polishing tape, the swing motion of the pressure contact roll and the movement of the polishing tape synchronized with the rotating speed of the worm.