DRILL FOR COMPOSITE SECTION STEEL

摘要

PROBLEM TO BE SOLVED: To provide a drill for a composite section steel for preventing the fracture of a holder by protecting the holder even when a carbide chip is broken. SOLUTION: A holder 3 rotatable around an axial line is installed, and a base metal 11 jointed to a carbide chip 7 by a jointing means 9 is detachably installed at the tip of the holder 3 by a detachment means 19. The jointing means is brazing 9, and the center of the tip of the holder 3 is coupled with the center of the rear end of the base metal 11 by coupling means 23 and 25 for securing concentricity. COPYRIGHT: (C)2004,JPO