TAP HOLE DRILLING MACHINE

In a tap hole drilling machine which comprises a tap hole drilling machine body for drilling a tap hole (5) at a blast furnace wall by giving impacts and revolutions to a drill rod (1) supported by a drifter (2) while advancing the drifter (2) along a guide channel (6) through a chain (8) linked to a feed motor (7) provided at the rear end of the guide channel (6), and a unit for retreating the tap hole drilling machine, which supports the tap hole drilling machine body and moves the body between a drilling position and a retreat position, the drifter is an oil hydraulic drifter that produces at least any of the impacts, revolutions and reversed impacts by oil hydraulic driving. Preferably a unit (50) for restricting and supporting the drill rod in a freely restriction-releasable state is provided at the tip end of the guide channel (6) besides a drill rod support (3). Power and the restriction force on the drill rod can be increased, thermal deformation of guide channel (6) can be prevented and the tap hole centering can be ensured.