| 摘要 |
A diamond drill bit for drilling bore holes in earth formations having a body connectible to a drilling string, and provided with a matrix portion of hard metals in which diamonds are surface set at the outer gage portion and adjacent to the bit axis, the hard metal matrix having preformed grooves in which preformed diamond impregnated segments are inserted, which are a mixture of diamonds and hard metals, and secured to the matrix portion by brazing material. During bit rotation in the bore hole, the segments cut the major portion of the hole, the diamonds being dispersed throughout the mass of each segment for selective release from the segment as the diamonds become damaged and lost, thereby exposing new diamonds in the segment at a controlled rate, and thereby producing continual resharpening of the segments. As a result, the drilling rate of the bit is increased, as well as the length of hole drilled.
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