Rotary digging into the rock is achieved by impact

From the way of rock force in the rock drilling, all kinds of drilling rigs strive to achieve the impact on the rock, because the impact of the device makes the output force far exceed the static output. For example, the down-the-hole hammer directly impacts the rock through the impactor; the reverse-circulating drilling of the intermediate roller hob, the wedge-shaped hob, etc. is achieved by the different rotation radius of each point on the hob to realize the impact on the rock during the rotation process.

Rotary drilling rigs enter the rock by controlling the weight of the drill to achieve rock impact. The drilling pressure is continuously cycled, supercharged, and decompressed in three modes in the mode shown in Figure 2. When the pressure is increased, the rotational resistance of the drill bit increases and decelerates. When the pressure is reduced, the resistance of the drill bit decreases and accelerates. From the equation of momentum and impulse conversion, the change of velocity is greater, and the shorter the change time is, the greater the impact force on the rock. Through the impact, the rig's insufficient force on the rock is effectively solved, and it is difficult to exceed the minimum load value of the broken rock. The impact on the rock also facilitates the formation of free faces. During the continuous rotation of the drill bit, the cutter head intermittently impacts the rock, and as a result, irregularities are continuously formed in the running direction of the cutter, and the old projection is broken to form a new projection. These rugged surfaces are the free faces of the drill. Whether the large free surface or the small free surface is beneficial to the rock under load (especially the impact load), the deformation is peeled off from the whole rock mass to form cuttings, thus increasing the drilling. effectiveness. The large pressurization capacity of the rig and the large power head power are the equipment conditions for realizing the rock into the rock. The ability to convert the equipment capacity into an effective rock breaking capacity must be properly coordinated by the pulse pressurization operation mode. From Figure 2, the reasonable pressure mode of rock drilling, the rock-injection mode of the rotary drilling rig is combined with dynamic and static loads, and the static load can increase the peak force of the impact dynamic load. The static load can also press the drill teeth on the rock at the bottom of the hole, so that the dynamic load is directly transmitted to the rock, reducing the power transmission loss and the power loss of the elastic collision. Dynamic loading is beneficial to make the applied load on the rock exceed a threshold.