Working principle of rotary drilling rig
The rotary drilling machine adopts the rotary excavation process to form holes. First, the drilling tool can be correctly positioned to the pile position through the self-propelled walking function and the mast luffing mechanism of the drilling machine. The bucket drill bit with a trapdoor at the bottom is placed at the hole position by lowering the drill pipe guided by the mast. The rotary head device of the drilling machine provides torque for the drill pipe, and the pressurization device transmits the pressing force to the drill pipe and bit through the pressurized rotary head. The drill bit rotates to crush the rock and soil and loads it directly into the drill bit. Then, the drill bit is lifted out of the hole by the lifting device and the telescopic drill pipe of the drilling machine for soil unloading. This process is repeated in a cycle to continuously remove and unload soil until the design depth is reached. Currently, the working principle of rotary drilling machines mostly adopts the form of connecting drill pipes and soil bucket for soil excavation. In the drilling process, mud circulation is often used, and mud plays a role in lubrication, supporting, displacement, and carrying drill cuttings for this type of drilling machine.
As environmental protection requirements for urban construction become stricter, traditional drilling machines face greater challenges. The rotary drilling machine, on the other hand, employs a rotary head design. Its working principle involves using a short auger bit or rotary bucket to directly rotate and excavate soil, sand, gravel, and other drill cuttings with strong torque, and then quickly lifting them out of the hole. It enables dry construction without the need for mud support. Even in special strata where mud retaining walls are required, the mud content during drilling is quite low, significantly reducing pollution sources, lowering construction costs, improving the construction environment, and enhancing hole-forming efficiency. This demonstrates the excellent environmental friendliness of rotary drilling machines.
Rotary drilling machines are suitable construction machinery for hole-forming operations in building foundation engineering. They are primarily used in soil layers such as sandy soil, cohesive soil, and silty soil, and are widely applied in various foundation constructions, including cast-in-place piles, continuous walls, and foundation reinforcement. With rated powers generally ranging from 125 to 450 kW and power output torques from 120 to 400 kN·m, rotary drilling machines can achieve maximum hole diameters of 1.5 to 4 meters and maximum hole depths of 60 to 90 meters, meeting the requirements of various large-scale foundation construction projects.
These drilling machines typically feature hydraulic crawler-type telescopic chassis, self-lifting and foldable masts, telescopic drill pipes, automatic verticality detection and adjustment, digital hole depth display, etc. The entire machine is generally operated using hydraulic pilot control and load sensing, providing easy and comfortable operation. The primary and secondary winches are suitable for various situations on the construction site. By pairing with different drilling tools, the drilling machine can be used for both dry (short auger) and wet (rotary bucket) hole-forming operations, as well as for rock formations (core drilling), and can also be equipped with long auger drills, grab buckets for underground continuous walls, and vibrating pile hammers to achieve multiple functions. It is mainly used in municipal construction, highway bridges, industrial and civil buildings, underground continuous walls, water conservancy, anti-seepage and slope protection, and other foundation construction projects. Domestic experts believe that rotary drilling machines will still have a significant market in China in the coming years.
The mechanical devices of rotary drilling machines primarily include luffing mechanisms, masts, primary and auxiliary winches, rotary heads, follow-up frames, pressurization devices, drill pipes, and drilling tools. They adopt parallelogram luffing mechanisms, self-lifting and folding masts, automatic control and detection of host power, rotary positioning, and safety protection; automatic detection and adjustment of drill pipe verticality; preset and monitoring of drilling depth, and other new technologies. The color display screen visually displays operating status parameters, and the entire machine is operated using pilot control and load sensing, maximizing the convenience, sensitivity, and safety comfort of operation, fully realizing the integration of human, machine, hydraulics, and electricity.
The rotary drilling machine is equipped with a range of drilling tools, including short auger bits, ordinary bits, sand dredging bits, and core bits, which can drill through different geological formations such as clay layers, gravel layers, pebble layers, and moderately weathered mudstone.
