Drill head shape
The shape of the drill bit directly affects the cross-section of the borehole. Most drill hole sections for rock drilling are polygonal rather than circular. So the formation of a polygonal cross-section is due to the deviation of the drill head towards the side of the gun limit when it rotates along its own axis. During rock drilling, the drill rod does not rotate on a fixed axis, but freely swings in the hole of the gun. This situation can be seen through careful observation in actual supply. The shape of the drill bit varies, and the cross-section of the borehole obtained during rock drilling also varies.
Rock properties
The rock properties that affect the drilling speed are mainly viscosity, hardness, and elasticity. The stickiness of rocks is their ability to resist breaking into small pieces. The viscosity of rocks and their composition and composition; Particle size and shape; The quantity, composition, and moisture content of the cement are related. Dense and homogeneous rocks have the same viscosity in all directions, while heterogeneous or layered rocks have different viscosity in all directions. The hardness of rocks, like their viscosity, is determined by the connecting force between rock particles. However, the hardness of rocks is their ability to resist sharp tools penetrating them. The elasticity of a rock refers to its ability to restore its original shape and volume after the external force acting on it disappears. All rocks have elasticity. The elasticity of rocks has a significant impact on impact drilling.
