The Hydraulic And Control System Research Of Power Head For Rotary Drilling Rig

Rotary drilling rig is a kind machine for fast hole drilling in pile foundation construction,widely used in highways, railways, bridges, civil engineering fields. The power head systemis the most important part of the rotary drilling rig, and the drilling efficiency has importanteffects on the rig’s performance. This paper studies the hydraulic system and control methodof power head, and it has certain theoretical significance and engineering application value forimproving the drilling efficiency.This paper describes the composition of the rotary drilling rig hydraulic system, and thecharacteristics of two-point control, high-pressure automatic variable control and electricproportional control of the motor is compared. This paper designs four shifts of power mode,standard mode, high-efficiency mode and soil-rejection model. It also analysis the differencesof ordinary pressurizing loop and the loop with flow regenerative function, configuring theload sensing counterbalance valve’s parameters. It also builds power head loop andpressurized cylinder loop’s AMESim simulation model; studying the parameters’ differenceswhen working in constant load, ramp load and step load. The simulation results show that thescheme is feasible.In the power head loop, the motor’s operating pressure is detected and fed back to thecontroller, and the controller calculates the optimum current according to the preset function.The current is used to control the motor’s displacement to adapt to the load torque quickly andaccurately. The four modes are designed for different load conditions with greater adaptiveability, and the efficiency mode can improve the construction efficiency up to23%. In thepressurized cylinder loop, the cylinder can be rapid descended in no-load condition and lightload condition. It only needs50%flow rate of the original system to achieve the samedescended speed and it also can reduce the overflow losses in large-load condition.