Abstract:

In response to the problems of deformation and rupture of the main structure caused by excessive impact force and the unstable vibration of equipment in the process of rock breaking by impact force during the operation of the downhole drilling rig, the downhole drilling rig for open-pit mines was taken as the research object to analyze the rock breaking characteristics under drilling conditions. Firstly, the rock breaking mechanism of the downhole drilling rig by impact force was analyzed to obtain the main modes of rock breaking under impact load. Secondly, by comparing the yield and breaking criteria of the model, the Drucker-Prager model was used to analyze the rock fragmentation effect under the impact of the drill bit. Finally, ABAQUS software was used to analyze the rock breaking characteristics by impact force under different drilling parameters. The results show that when the impact force is too small, and the rotation speed is too high, the force of the drill bit on the rock is not enough, leading to low drilling efficiency. When the rotation speed is too small, and the impact force is too large, the rock is not completely destroyed, and it is difficult to discharge debris, resulting in a poor crushing effect. As the rotation speed increases, the drilling speed first increases and then decreases. As the impact force increases, the energy of the drill bit invading the rock increases, resulting in an increase in drilling speed. However, excessive pushing force can cause unstable drilling of the drill rod, leading to an unsatisfactory rock breaking effect and affecting the drilling efficiency.

Key words: downhole drilling rig, rock breaking, drilling speed, ABAQUS software