APPARATUS FOR MILLING SCREW HAVING CIRCULAR HELICAL SURFACE WITH LARGE PITCH AND SMALL DISTANCE BETWEEN APEX AND RECESS Russian patent published in 2007 - IPC B23C3/00 B23G1/32 

FIELD: machine engineering, working screws of screw pumps made of hard-to-form materials.

SUBSTANCE: apparatus includes tool in the form of three disc shaped milling cutters uniformly arranged one relative to other in cross plane and spaced one from other in axial direction by distance consisting of 1/3 of pitch. Rotation axes of said milling cutters are inclined relative to axis of worked screw by angle equal to that lead angle of helical surface turns. Height of said milling cutters is no less than pitch value of worked screw and they are provided with individual drives for radial feed and individual drives for rotation motion.

EFFECT: enlarged manufacturing possibilities, improved efficiency of working.

2 dwg, 1 ex