BORE EXPANDABLE TAPPING BAR

摘要

PURPOSE: A bore expandable tapping bar is provided to restrain output of dust and flying substances and to make the structure effectively discharge molten substance without extra-positioning a tapping bar in punching a wire output hole. CONSTITUTION: A stay area of a wire output hole is formed in a cupola level in a furnace at an early stage of wire output. A cupola area is formed in a drill bit part inserted deeply in the furnace. An inside diameter expanding piece(4) combined to the front end of the drill bit by screw is molten. After stoppage time, a punching machine body is separated from a tapping bar(7a). After completing separation, nitrogen gas is blocked up. Herein, the output of cupola is restrained by the nitrogen gas supplied via a cooling fluid passage(6a) of the tapping bar. After completing separation, cupola is discharged by the pressure in the furnace.