SCREW TAP FOR CUTTING THREAD IN DEAD OPENINGS Russian patent published in 2003 - IPC

FIELD: machine engineering, fitting and tools for working in condition of automatic production of large-size body parts of viscous constructional materials. SUBSTANCE: screw tap includes stem, sizing and starting portions and it has two slit like cutouts arranged in zone of transition of starting portion to sizing one. Slit-like cutouts have length equal to that of starting portion or less than it. Their width and spacing from end until leading end is selected depending upon thickness of cuttings according to formulae given in description of invention. EFFECT: elimination of screw tap breakage, enhanced operational reliability of automatic lines. 3 dwg