1. Drilling Rig Torque#screw pile drilling machine#
Select the drilling rig torque according to the project requirements to ensure the rig can reliably operate in its high-efficiency zone. The high-efficiency zone of a drilling rig generally refers to an average drilling speed of 5m/h or higher during normal drilling. For example, using short auger bits and cylindrical drill bits, for a hole diameter of 800mm in soil, the drilling rig should have a torque of 80kNm. For every 100mm increase in hole diameter, the drilling rig torque should increase by 10kNm. In dense sand or gravel layers, for every 100mm increase in hole diameter, the drilling rig torque should increase by 15-20kNm. It must be pointed out that the drilling speed is closely related to the structure and parameters of the drill bit.
2. Drill Rods
Drill rods must transmit the full torque of the power head to the drill bit at the bottom of the hole, and also stably transmit the pressure of the hydraulic cylinder, the weight of the power head, and the weight of the drill rod itself to the drill bit tens of meters below. Therefore, when drilling into harder formations, the drill rod must simultaneously withstand high torque and high drilling pressure, and overcome significant bending moments. If the drill rod does not meet these requirements, it is easily damaged.#screw pile drilling machine#
The pressurization methods used by different manufacturers are mainly reflected in the type of drill rod. Friction-type telescopic drill rods have high drilling efficiency in soft soil layers; mechanically locked drill rods are suitable for drilling hard rock layers, but require more precise operation, necessitating the location of the pressurization point; self-locking armored drill rods can be pressurized at any time and have good torque transmission. Kelvin drill rods can be divided into two main categories: friction drill rods and locking drill rods. Currently, based on drill rod type, drill rods can be broadly classified into toothed wedge type, semi-toothed wedge type, and friction-type. When drilling in hard formations, toothed wedge and semi-toothed wedge drills can reliably apply pressure to the drill rod. The pressure control is also excellent in both hard and general formations.
The drill rod length should be determined based on the drilling depth. When the drilling depth range is large, two sets of drill rods should be selected: one long drill rod of no less than 60m and one short drill rod of approximately 40m. To ensure the installation of the largest diameter drill bit, the distance between the centerline of the drill rod and the mast slide surface of medium and small drilling rigs should generally be no less than 1m, and no less than 1.2m for large drilling rigs. Drill rod vibration damping is crucial. Rubber vibration damping only reduces wear at the ends of each drill rod section, ensuring its service life. Spring vibration damping and rubber-spring composite vibration damping, in addition to effectively ensuring the service life of the drill rod, can also remove clay-like debris that is difficult to remove from the drill bit through vibration, improving work efficiency. However, the spring life is shorter with spring-damped drill rods when using vibration unloading methods. Vibration amplitude and frequency should be strictly controlled, and spare springs should be available. It is recommended to use spring damping for short drill pipes and rubber damping for long drill pipes.#screw pile drilling machine#
