GEAR SHAPER

PURPOSE:To improve machining accuracy and also to make the synchronous adjustment work of a helical guide simply and accurately by connecting a first and a second driving motors to a first and, a second crankshaft for reciprocating a male mold and a first female mold and connecting a synchronizer to the motors. CONSTITUTION:A first crankshaft 25 is rotated by a first driving motor 103 to reciprocate a main shaft 11 in an axial direction, whereby, the male mold 15 of the main shaft 11 is rotationally reciprocated along the lead of a first helical convex portion, meantime, a second crankshaft 43 is rotated by a second driving motor 107 to reciprocate a first female mold 16 in the axial direction, whereby, a reciprocating rotational movement along the lead of a second helical protrusion is synthesized to the reciprocating rotation along the lead of the first helical protrusion to be rotated. In this case, the first and the second driving motors 103, 107 are rotated accurately and synchronously by a synchronizer to rotate the first and the second crankshafts 25, 43 also synchronously and the relative movements of the male mold 15 and the first female mold 16 following a main shaft moving speed is obtained, and the rotation of the main shaft 11 corresponding to the moving speed can be obtained.