초록 ▼

A drill head assembly for drilling holes in bony structure is disclosed. The assembly has an inner drill and an outer drill which rotate together as a unit. The leading portions of the outer drill are contiguous with the peripheral portions of the inner drill, and the inner and outer drills are adap

A drill head assembly for drilling holes in bony structure is disclosed. The assembly has an inner drill and an outer drill which rotate together as a unit. The leading portions of the outer drill are contiguous with the peripheral portions of the inner drill, and the inner and outer drills are adapted to form a bore-countersink opening in the bone, whereby the drill head assembly may be used to safely drill through relatively thin bone.

대표청구항 ▼

A perforator comprising: (1) a drill head assembly comprising (a) an inner drill having a plurality of inner cutting flutes, each terminating in a front cutting edge, and (b) an outer drill comprising a plurality of outer cutting flutes, each terminating in a front cutting edge, said drill head asse

A perforator comprising: (1) a drill head assembly comprising (a) an inner drill having a plurality of inner cutting flutes, each terminating in a front cutting edge, and (b) an outer drill comprising a plurality of outer cutting flutes, each terminating in a front cutting edge, said drill head assembly being constructed so that the leading portions of said front cutting edges of said outer cutting flutes are contiguous with the peripheral portions of said front cutting edges of said inner cutting flutes so long as said drill assembly is enabled and said inner drill encounters a resistive surface; and (2) drive means for enabling said drill head assembly when said inner drill is encountering a resistive surface, and disabling said drill head assembly when said inner drill is no longer encountering said resistive surface while said outer drill is still encountering said resistive surface.