Simulation of Hammer Bit Drilling Based on Rock Properties Experiment

To investigate frequent failures of drill bit teeth in air hammer drilling like teeth falling,breaking and severe wear,laboratory experiments of dynamic splitting tensile,uniaxial and triaxial compression and compression with granite samples were conducted with the SHPB and material test system to obtain mechanical properties of the rock for numerical simulation.H-J-C dynamic constitutive model was adopted for in numerical simulation,the material model parameters were determined from experiment,and tensile strength of granite was selected as failure criterion.Drill bit tooth parameters,the bit teeth sinking depth,crushing volume were simulated numerically,which showed that the cone tooth has the highest efficiency in rock breaking under the same conditions and heel tooth in 30° can increase the rock crushing volume significantly.In addition,the configuration of tooth surface was examined,which showed that the pattern of "ball teeth in the middle and cone teeth in the peripheral" has highest rock breaking efficiency,but the pattern of "ball teeth in the middle and peripheral" has lowest in rock breaking efficiency.