钻齿齿形对潜孔钻头冲击凿岩效能的影响

为优选钻齿齿形，提高潜孔钻头的凿岩效能，通过分离式霍普金森压杆（SHPB）试验研究灰砂岩、红砂岩和大理岩条件下，球形钻齿、锥形钻齿和镐形钻齿在不同加载率下的峰值应力、耗散能以及不同入射能下的能量耗散率。分析发现： 1）B-SHPB试验的峰值应力、耗散能和能量耗散率参数，可以用来评估钻齿的凿岩性能； 2）对于灰砂岩和节理较为发育的大理岩等软岩，建议尽量提高输入钻齿的能量，以提高能量耗散率，但是对于红砂岩类硬岩，提高耗散能对提高能量耗散率作用不显著，因此可以根据钻进速度需求设置耗散能； 3）在钻机功率受限工况下，建议采用镐形钻齿，以降低破碎岩石所需的冲击力和冲击功率； 4）在需要快速钻进和需要考虑成本效益时，建议首先尝试使用锥形钻齿，以提高耗散能和能量耗散率。

Influence of Bit Profile on Drilling Efficiency of Down the Hole Drill Bit

The bit profile of a down the hole drill bit is optimized to improve rock drilling efficiency. Through a split Hopkinson pressure bar(SHPB) test, spherical, tapered, and pick shape drill bits are employed to drill gray sandstone, red sandstone, and marble with different loads, respectively, and peak stress, input energy, and energy dissipation rate variation trends under different incident energies are compared and analyzed. The findings are summarized as follows: (1) The peak stress, dissipated energy, and energy dissipation rate in SHPB test can be used as indexes to estimate the drilling performance of a drill bit. (2) For soft rocks, e.g., gray sandstone and marble with well developed joints, it is suggested to increase the input energy of the bit to improve the energy dissipation rate. For hard rocks, e.g., red sandstone, the input energy must be set according to the drilling speed because increased input energy has negligible effect on improving energy dissipation rate. (3) Under limited drilling power conditions, the pick shape drill bit is recommended to reduce the impact force and impact power required by rock crushing. (4) Relative to drilling speed and cost, a tapered drill bit is preferred to improve dissipation energy and energy dissipation rate.