Views: 0 Author: Site Editor Publish Time: 2025-10-23 Origin: Site
As the core component for transmitting torque and pressure, the performance of the rotary drilling rig drill rod directly determines the stability and engineering quality of the drilling process. In complex geological construction, the mechanical properties of materials and the structural design of the number of sections form an interrelated technical system, jointly affecting the load-bearing capacity and operational reliability of drill pipes.
Material is the foundation for ensuring drilling stability, and its mechanical properties directly determine the tolerance of drilling rods to complex stresses. The current mainstream drilling rods all use high-strength alloy steel, such as Q550XZ series low-alloy steel, which has become a benchmark material in the industry. This type of steel achieves a balance of strength and toughness through precise control of chemical composition and advanced heat treatment processes - the minimum yield strength can reach 550MPa, and can withstand the huge torque and axial pressure during drilling in hard rock formations without fracture. For different working conditions, materials are further divided into multiple grades: Q550XZC grade steel can be used for conventional geology, Q550XZD grade steel with better toughness is suitable for medium complex geology, and Q550XZE grade material with high impact resistance is required for harsh geology and cold environments. In addition to the basic mechanical properties, the weldability and dimensional accuracy of the material are equally critical: good weldability ensures that the various components of the drill rod are firmly joined, reducing stress concentration points; High precision outer diameter and wall thickness ensure smooth expansion and contraction of multiple drill rods, reducing energy loss and vibration interference during drilling.
Section design profoundly changes drilling stability by affecting the overall stiffness and force distribution of the drill rod. The number of drill pipe sections is determined by the drilling depth and is usually calculated based on the height of the mast and the effective length of a single section. It is commonly a 2-5 section telescopic structure. There is a significant correlation between the number of sections and stability: the fewer sections, the stronger the overall rigidity of the drill rod, and the better its ability to resist bending and twisting. It is less likely to cause inclined holes or rod deformation when drilling in hard rock formations; However, insufficient number of sections will limit the drilling depth and cannot meet the requirements of deep pile construction. Although increasing the number of sections can extend the depth of operation, it will bring about stiffness attenuation problems - the diameter of the inner core section drill rod decreases with the increase of sections, and the load resistance capacity significantly decreases. It is easy to crack or break during high torque construction, and safety needs to be ensured through torque and pressure limiting, resulting in reduced efficiency. To balance depth and stability, the industry has developed variable pitch technology, which can flexibly switch between 2-5 pitches by adding or removing intermediate rods, adapting to different hole depths and geological requirements. This not only avoids the cost pressure of multiple equipment backups, but also optimizes stability performance under different working conditions.
The coordinated matching of material and number of sections is the key to improving drilling stability. High strength materials provide performance support for multi section drill rods: core steel pipes with secondary strengthening heat treatment are used to compensate for the strength shortcomings caused by multi section structures, allowing 4-5 sections of drill rods to maintain reliable bearing capacity during deep hole construction; Reasonable section design can fully utilize material performance, such as increasing the guiding length of multiple drill rods when fully extended through a dual ring structure, improving coaxiality and bending resistance, and reducing material potential waste. In actual construction, this collaborative relationship is more intuitive: for deep hole operations in hard rock, Q550XZE grade material should be selected with 3-4 optimized structural drill rods, which not only use the material's high strength to resist rock impact, but also control stiffness attenuation through a limited number of sections; For soft formations, Q550XZC grade material and multi section drill pipe combination can be used to expand the depth of operation while ensuring stability.
In summary, the material of the drill pipe determines the bottom line of stability performance, while the design of the number of sections defines the applicable boundary of stability. With the iteration of high-strength alloy materials and the maturity of variable section technology, drill pipes are achieving a precise balance between "material strength and toughness" and "section adaptability", providing more reliable technical support for drilling operations at different geological and depth levels.
