Research On Main Driving System Of High-speed And Targe-torque Hydraulic Top Drive

The implementation of Deep Continental Scientific Drilling needs continuouscoring drilling which makes a higher requirement for drilling speed, drillingtechnology, efficiency and cost of core drilling. The traditional rotary table uses asingle drill pipe to drill, whose disadvantages lie in low efficiency, high labor intensityoperations, and more possibility of downhole drilling accident. As compared to rotarytable, top drive uses three drill pipes to drill. This way reduces auxiliary working timeof makeup and breakout, which greatly improves the drilling efficiency. It can drivethe drill string at any height and ensure continuous circulation of drilling fluid, whicheffectively prevent downhole drilling accident such as sticking and bit bouncing. Thusthe application of top drive achieves substantive leap on drilling rig safety and processautomation. The technology of foreign top drive is relatively mature. There are aseries of products of electrically driven top drive and hydraulic drive top drive. Butseldom of those top drive are used for geological drilling applications. Whileelectrically driven top drive holds leading position in the domestic top drive. Thereare less mature products of hydraulically driven top drive.This paper is based on the project of high-speed and large-torque hydraulic topdrive which is sub-project of "Special research and experiment research of deepdetection technology of state (SinoProbe-09-05)" and focuses on the main drivesystem. This paper summarizes the development situation of domestic and foreign topdrive and those main drive system and will study the main drive system from twoaspects of the structure and hydraulic system. Structure focuses on the bearingcapacity of gear box; hydraulic system focuses on the oil temperature of closed loophydraulic system.Firstly introduce the overall structure and working principle of the hydraulic top drive and focus on transmission scheme and working principle of the main drivesystem and determine the key technical parameters. Secondly build the virtualprototype model of gear box based on Romax software and analyzed in detail thevarious components. Results show that the strength and stiffness of housing and shaftand the fatigue life of bearing meet the requirements. The helical gear safetycoefficients of contact and bending strength are higher. After gear modification, thestrength is further increased, and the transmission is more stable. And then builtthermodynamics simulation model of closed loop hydraulic system based onAMESim software after study the reason of heat production of closed loop hydraulicsystem and efficiency of pump and motor. Results show that reasonable selection ondisplacement of slippage pump and well control over the temperature of the oil thatslippage pump suction can ensure oil temperature within a reasonable range. In orderto control the pump suction oil temperature, the tank cooling system is studied. Theresults show that the cooling system can decrease the temperature of oil tank. Finallythe experimental test results show that load performance and oil temperature of closedloop of the main drive system of high-speed and large-torque hydraulic top drive canmeet the requirements of the actual condition.