Operation method of down-the-hole hammer rotary drilling
The operation method of hammer rotary drilling is to install a down-the-hole hammer between the lower end of the rotating drill pipe column and the coring drill, so that the hammer pulse, axial drill bit pressure and drill pipe rotation torque act on the drill bit at the same time to achieve drilling and core collection. This drilling method originated in Europe in the early 19th century. The Chinese Ministry of Geology began to study it in 1958 and developed rapidly in the 1970s. Its main advantages are that it can greatly increase the drilling speed and the length of each round of footage in hard rock formations, reduce the degree of borehole bending, and significantly reduce drilling costs. hammer rotary drilling is usually achieved by two types of hammers. One is to use the hammer driven by the energy of the drilling fluid, which is called hydraulic hammer rotary drilling, and the other is to use a pneumatic hammer driven by compressed air, which is called pneumatic hammer rotary drilling. The following mainly introduces hydraulic hammer rotary drilling.
The hydraulic hammer rotary drilling system uses a mud pump to pump drilling flushing fluid through the drill pipe into the hammer to drive the hydraulic hammer to hammer the core tube and drill bit. The drill pipe is driven by the drilling rig to rotate and pressurize the drill bit. This drilling method can also be combined with rope coring drill tools, called rope coring hydraulic hammer rotary drilling. Before drilling begins, the hydraulic hammer and the inner core tube suspended by the spearhead are put into the rope coring drill pipe from the ground, and then the drilling flushing fluid is pumped into the drill pipe to drive the hammer for drilling and coring. At the end of the return, a thin steel wire rope is used to put the salvage device and the hammer and the inner core tube are lifted out of the ground by a special winch.
The hydraulic hammer is the main tool for hammer rotary drilling. According to its working principle, it can be divided into three types: positive action, double action and reaction action. Depending on the hammer frequency, those with a frequency higher than 40 Hz are high-frequency hammers, which can be equipped with diamond drill bits. Rock crushing is mainly done by rotation and supplemented by hammer, which is called hydraulic rotary hammer drilling. Those with a frequency less than 40 Hz are low-frequency hammers, which are often equipped with carbide drill bits. Rock crushing is mainly done by hammer and supplemented by rotation, which is called hydraulic rotary hammer drilling.
