## 2 Structure and Working Principle of New Torsional Impactor
### Working Principle  
The working principle of the new torsional impactor is as follows: the ground drilling rig drives the drill pipe to rotate, and the drill pipe transmits torque to the drill bit through the drill pipe joint, the upper joint, the torque transmission joint, and the lower joint, thus realizing the rotation of the drill bit and crushing rocks. The ground drilling fluid driving the device transports the drilling fluid while carrying energy to the hollow channel of the drill pipe joint through the hollow drill pipe channel, and the drilling fluid flows to the turbine and makes contact with the turbine blades through the waist hole on the bearing seat. The turbine converts the fluid energy of the drilling fluid into mechanical energy for the rotation of the turbine rotor, and the transmission shaft rotates synchronously with the turbine rotor driven by the turbine rotor. The torque generating device is installed on the transmission shaft through a square hole and square shaft, and the rotating transmission shaft drives the connecting shaft in the torque generating device so that they can together with the punching hammer through the square hole and square shaft. Because of the special structure of the impact anvil (wall thickness is inconsistent and impact surface is designed), the rotating impact hammer can impact the impact anvil and can produce an impact force and impact vibration. When the torque-generating devices are arranged in pairs that are adjacent to each other, then they can generate pairs of impact force and impact vibrations that are basically equal in size, different in action points, and opposite in direction. This pair of impact forces constitutes torsion, while the impact vibration that is generated by cooperation constitutes torsion impact. Torsional impact is finally transmitted to the drill bit through the impact anvil, the torque transmission joint, and the lower joint in order to realize torsional impact drilling. The torsion generator is a key component in the impactor, the structure of which is shown in Figure 2 and is mainly composed of an impact anvil, impact hammer, and connecting shaft. The working principle is as follows: a single torque generator is composed of four parts, including one 1 connecting shaft, two impact hammers, and one impact anvil. The impact anvil is ring-shaped with protruding keys on the outer part and has a different inner radius, so the thickness of the impact anvil ring wall is different. The part where the impact anvil has protruding keys is the thickest, and the impact surface is designed here, and the thinnest part is designed on the opposite side. The purpose is that when the impact surface of the impact hammer comes into contact and impacts the impact surface of the impact anvil, according to the principle of acting force and reaction force, the impact surface of the impact hammer is subjected to an acting force that is perpendicular to the inclined plane, which can be decomposed into a tangential acting component of the impact hammer and axial-acting component of the connecting shaft. The axial-acting component drives the connecting shaft and the impact hammer to move along the axial direction of the connecting shaft to the thinnest part of the impact anvil wall, thus enabling the impact hammer to bypass the impact surface at the thickest part of the impact anvil and allowing it to continue to rotate after completing the impact task. After the impact hammer rotates 180\({}^{\circ}\), the other impact hammer rotates to the impact surface of the impact anvil, and the other impact hammer also impacts the impact surface of the impact anvil, which also produces tangential and axial force components. Due to the axial force components, the connecting shaft and two impact hammers are driven to move axially and to continue to rotate together under the drive of the transmission shaft, bypass the impact surface of the impact anvil, and then enter the next cycle. A single torsion generator can only generate impact force and impact vibration.