Torque-adaptive impact tool suitable for PDC bit

A torque-adaptive impact system, comprising a Polycrystalline Diamond Compact (PDC) bit, a rotary-driving power device, and a torque-adaptive impact tool above the PDC bit, wherein the torque-adaptive impact tool is located between the PDC bit and the rotary-driving power device, and the torque-adaptive impact tool comprises an outer housing, an upper end cover, a main shaft, an elastic element, an upper impact body, and a lower impact body;

• the main shaft is provided with spiral grooves, and an upper end of the main shaft is connected to a torque output end of the rotary-driving power device;
• an upper jaw is arranged on a lower end surface of the upper impact body, and protrusions, in fit with the spiral grooves, are arranged on an inner wall of the upper impact body, and the upper impact body is rotatable along with the main shaft and movable in an axial direction of the main shaft under a combined action of the main shaft, the spiral grooves and the protrusions;
• the elastic element is arranged between the upper impact body and the upper end cover;
• the upper end cover does not move along an axis of the main shaft, and is configured to support the elastic element;
• a lower jaw is arranged on an upper end surface of the lower impact body, and the lower impact body rotates under a driving action of the upper jaw to the lower jaw;
• an anti-falling device is arranged between the lower impact body and the outer housing;
• in a case of a normal operation, the main shaft rotates under an action of the rotary-driving power device, the upper impact body rotates along with the main shaft due to a pushing action of the spiral grooves to the protrusions, and the lower impact body rotates under the driving action of the upper jaw to the lower jaw so as to drive the PDC bit to rotate, wherein a rotational speed of the PDC bit is same as that of the rotary-driving power device;
• and
• in a case that the PDC bit is in a sticking state due to a fact that a rock-breaking torque required by the PDC bit exceeds a torque provided by the upper impact body to the lower impact body, the main shaft remains rotating under the action of the rotary-driving power device, the upper impact body moves upward under the pushing action of the spiral grooves to the protrusions to compress the elastic element;
• when the upper jaw passes over the lower jaw;
• the upper impact body moves downwards under an action of the elastic element and is accelerated to rotate under the pushing action of the spiral grooves so as to enable the upper jaw to generate rotary impact on the lower jaw.