Selection and use of diamond drill bits
The principle of choosing a diamond drill
1. Soft to medium hard (referring to the drillability classification table 1-6 for diamond core drilling) and complete homogeneous rock formations. Generally, natural surface-set drill bits, composite drill bits, polycrystalline drill bits are suitable, and some sintered body drill bits can be used. .
2. For hard to hard and dense rock formations (levels 7-12 in the grading table), impregnated drill bits, concentric or staggered pointed ring groove drill bits, or fine-grained surface-inlaid diamond drill bits are generally suitable.
3. In broken, hard and soft interlayers, developed fissures or strong abrasive rock formations, such as coal-measure formations, it is advisable to use sharp-tooth type broad-spectrum drill bits or electroplated impregnated drill bits with good wear resistance and reinforcement.
4. According to the abrasiveness, weathering degree and crushing degree of the rock, the principle of choosing the wear resistance of the matrix is: (1) Strong abrasive rock layer, select the matrix with high wear resistance. (2) For medium abrasive rock formations, use a matrix with medium abrasion resistance. For weak abrasive rock formations, use low-wear-resistant carcasses. (3) For complex rock formations, the stronger the abrasiveness, the harder the diamond drill bits with better grades and relatively finer grain size should be used. (4) For highly abrasive and relatively broken rock formations, under the condition of ensuring good diamond enclosing, choose a diamond bit with a higher diamond concentration. On the contrary, for homogeneous, dense, and weakly abrasive rock formations, diamond drill bits with lower diamond concentration should be used. (5) The rock formation is soft (grade 1-4), with a lot of powder discharge, choose composite drill bit or polycrystalline drill bit. For coring of easy-erosion rock and mineral layers, bottom jet drill bits should be used.