| 摘要 |
<p>Strategically placed hardfacing material (61, 71, 81, 91, 101, 111, 121) near the shank end (37) of a drill bit (31) above the transition edges (53) provides additional protection for compensator areas and the upper leg surfaces of drill bits during updrilling and/or backreaming operations. The strategically located hardfacing is typically passive in the normal drill mode, but active in the updrill drilling mode and/or backreaming. Alternative designs including other strategic material placement, the formation of hardfacing materials in tooth/wear design shapes, bi-metallic gage, graded composite hardfacing materials, recesses or cavities at edges of the outer diameter, and various methods of applying the material also may be employed.</p> |
