Drill bits having tips of varying shapes and serving different purposes are well known in the art. In most instances, the drill bit tips form a chisel structure that effectively pushes the drilled material to the side while the drill is rotating. Unfortunately, however, these drill bit tips create friction and produce undesired heat. FIG. 1 is illustrative of this type of conventional solid type drill bit. The prior art drill bit 10 comprises a shank 12 with cutting edges 14 and 16. Each cutting edge 14 and 16 is defined by the intersection of one of the relief surfaces 18 and 20 and its respective rake surface 22 and 24. Further, the two relief surfaces 18 and 20 form a cusp or chisel edge 26 at the tip of the drill bit 10.
The prior art does disclose various different drill bit tips, but each fails to suggest a structure which would provide a relief angle. Specifically, U.S. Pat. No. 4,671,710 eliminates the chisel by forming recessed surfaces in the neighborhood of the axis of rotation of the drill. However, due to the inner cone of the "v" shape and the width of cone ".delta.", this structure makes the non-cutting zone smaller and provides no relief angle to the inner cutting edges.
FIGS. 2A and 2B are also illustrative of standard carbide drill tips having the cutting edges 38, 40 connected via a chisel 42. The cutting edges 38, 40 are parallel to each other, and to the diameter line of the drill bit. However, the cutting edges 38, 40 fail to pass through the center 44 of the drill bit tip.
Drill bit tips addressing the issue of heat generated by the friction of the rotating drill bit are disclosed in the prior art. This combination of friction and heat distort the shape of the drill by distorting the chisel, detracting from the efficiency of the drill to create more heat. The prior art devices inadequately solve the heat problem. As a result, a need exists for a drill bit with a tip structure that efficiently and effectively eliminates heat caused by friction while drilling a bore in an object. The present invention provides such a drill bit tip structure.