Causes and Solutions for the Skid of Drill Bits

When drill bits are drilling into extra-hard formation, it always causes the phenomenon: the skid of drill bits. Many people think the cause of this phenomenon is that it can not make the ket exposed from diamond and its drill bit matrix is too hard. Therefore, they are trying their best to reduce the hardness and abrasion resistance of drill bits matrix, which causes to the other extreme that the drill bit while drilling into extra-hard strata can avoid the skid, but its life is extremely short.

In fact, when drilling into extra-hard strata, the wear is too fast for the diamond but the wear is relatively slow for drill bits, which leads to a small plane on the surface of diamond within a very short time. The small plane greatly increases the contact area of the rock and diamond, which reduces the contact pressure per unit area between the rock and diamond. When the pressure from diamond acting on the surface of the rock is less than the compressive strength of extra-hard stratum, diamond cannot effectively break the rock, and then when drilling into rock, drill bits appear the skid phenomenon.

When the slippage phenomenon appears in drilling into extra-hard formation, blunt diamond on the drill bits matrix surface not only can not break the rock effectively, but also cannot fall off from the surface of the drill bits matrix. This is because the top body of blunt diamond is wrapped by matrix, and the bottom surface forms the contact formation with rock; Diamond has actually been closer in the state of great stress from two directions, so it has strong compression ability, and is not easy to let it fall off more. Because when the slippage phenomenon appears, the contact surface of the rock and drill bit does not produce rock powder, which will lead to no wear and tear of drill bits matrix , and diamond wrapped in drill bits cannot be exposed or fallen off.

After the slippage phenomenon appears, blunt diamond has become obstacles in the drill bits matrix. In order not to make blunt diamond useless in the drill bits matrix, the most important thing is trying to make it off as soon as possible, which can make a new intact diamond can be taken out as soon as possible to break rock.

Based on this point, the weak-bonded means is used to design the extra-hard formation drill bit that can solve the problem of drill bit slippage. The design method of weak-bonded and anti-slip drill bit is: Firstly, a layer of tungsten carbide powder should be put on the surface of diamond by mechanical method; Secondly, to mix the processed diamond and the matrix powder uniformly; Finally, to load mode and sintering. The drill bit after such processing will not have a layer of tungsten carbide powder between matrix and diamond, which weakens the body's ability to pack with diamond. In the condition of no less wear, diamond will fall off from the matrix by itself so as to achieve the change of the diamond layer.