| 摘要 |
A diamond drill coring bit has an annular crown 6 formed from radially extending composite segments 18 spaced apart circumferentially by a circumferential spacer material 24, all integrally bonded together. Each composite segment consists of diamond impregnated segments 20 spaced radially from each other by a radial spacer material 22. The diamond impregnated segments 20 have greater abrasion resistance than the radial spacer material 22 such that the latter will wear faster than the former. The radial spacer material 22 likewise has greater abrasion resistance than that of the circumferential spacer material 24 such that the latter will wear faster but not so fast as prematurely to expose the composite segments 18. The circumferential spacer material 24 has good thermal conductivity to conduct heat from the composite segments 18, and substantial ductility to absorb drilling shocks. <IMAGE> |
