SANY Heavy Industry has introduced the "Drill-Logic" adaptive torque management system for its SR285 rotary drilling rigs, targeting deep foundation drilling through interbedded rock formations-alternating layers of soft clay, weathered sandstone, and competent limestone-that present varying resistance to the drill bit. In traditional rotary drilling, the operator relies on experience to balance two competing inputs: the "Crowding Force" (downward thrust applied through the kelly bar) and the "Rotation Torque" (rotational power delivered by the rig's rotary drive). Applying too much crowding force in hard rock stalls the drill string and over-torques the kelly bar, while insufficient crowding in soft clay produces slow penetration and an oversized hole due to bit wobble.
The Drill-Logic system integrates "Magnetostrictive Torsional Strain Sensors" bonded to the kelly bar's outer box section and a "Rotation Angle Encoder" on the rotary drive's output shaft. The engineering breakthrough is the "Rock-Layer Transition Detection." As the drill bit penetrates each new rock layer, the system detects the characteristic change in the kelly bar's torsional strain signature-soft clay produces a smooth, low-amplitude strain signal, while competent limestone produces a jagged, high-amplitude signal with frequent micro-stalls. The onboard AI classifier identifies the rock layer type within 500 milliseconds of the transition.
Based on the classified layer, the system preemptively adjusts the "Optimal Drilling Parameters." In soft clay, the system increases the crowding force and reduces rotation torque, maximizing penetration rate while preventing hole deviation from bit wander. In competent limestone, the system reduces crowding force and increases rotation torque, allowing the bit's cutting teeth to fracture the rock without stalling the string. In the transition zones-where the drill bit is simultaneously engaging two rock layers with different resistances-the system applies asymmetric crowding force through the rig's leader-mast cylinders, compensating for the differential resistance to maintain the drill string's verticality. This adaptive parameter control reduces kelly-bar over-torque events by 70 percent, extends the drill bit's service life by 35 percent, and maintains hole verticality within 1 percent even through highly interbedded formations.
