Drilling apparatus

摘要

A drill steel and a drill bit having a tip with a cutting element and a hollow open ended shank forming a polygonal socket which is fitted onto a complementary engagement portion at one end of the drill steel so that rotation of the drill steel rotates the bit. The engagement portion of the drill steel has an axial slot to hold a spring retainer clip with a protrusion. A slot is formed in the shank of the drill bit to receive the protrusion on the spring retainer clip to hold the bit in the axial position on the drill steel. An opening in the shank of the drill bit and a pin extending through the opening and through the axial slot in the engagement portion of the drill steel when a spring retainer clip is not located in the slot. Axial openings in the tip of the drill bit communicate with the socket for the passage of either liquid or compressed air to the cutting element of the drill bit or for creating a vacuum at the cutting element, and an axial passage extends through the drill steel for supplying liquid or compressed air to the socket in the drill bit or for creating a vacuum in the socket of the drill bit.