Working principle of four-corner drill

According to the types, it can be divided into drag bit, roller bit, diamond bit and PDC bit.

According to their functions, they can be divided into all-round bits, coring bits and bits for special processes (such as reaming bits and directional deflecting bits).

Four-corner drill, also known as PDC drill, works by cutting to break rocks. Self-sharpening cutting teeth can easily cut into strata under the action of WOB, and move forward to shear rocks under the action of torque. Many PDC cutting teeth work at the same time, and there are many free surfaces of rock at the bottom of the well, so the rock is easy to be broken under shear, so the rock breaking efficiency is high and the drilling speed is fast.

As long as the two points are symmetrical, the final result must be circular drilling, but circular drilling has a lot of inconvenience for carpenters, because in the process of construction, it is inevitable to need square wood blocks to cooperate. After the cooperation is stable, a tight wooden structure can be obtained without a nail and hammer, which is also the tenon-mortise structure proposed by carpenters in modern China.