Design And Experimental Study On Electric Piston Coring Tool

Environmental scientific drilling requires the core sample preserve in-situ structure, unpolluted and with good representativeness. Taking the core in the soft and broken loose formation proposes high demand of drilling technology and device, which are necessary to be studied further. The paper designed a new type of electric piston coring tool, and obtained the following results through the laboratory test.First, the key technology of coring in environmental scientific drilling were summarized, including the control of circulation of drilling fluid, improved design and application of clip heart body, piston corer and kinds of single swiveling double-tube, and the respective limitations were illustrated through the force analysis.A new type of electric piston coring tool applied to environmental drilling was designed. The control structure was named electric piston structure, it mainly contained (1) load transfer mechanism:worm wheel-and-worm was used to drive the electric piston structure to run to realize the piston pump alike by controlling the friction wheel. (2) piston mechanism:size and installation design of the suitable sealing material formed vacuum in the space above the core when electric piston structure ran. (3) power mechanism:design of the motor and lectotype. (4)intelligent control mechanism:displacement sensor and motor driving module were introduced,and intelligent control plans were made according to the start-up condition, which means the core enters in the core barrel, and is 5mm distance from the bottom of the electric piston structure to control the piston move up automatically to pump the core to avoid being jammed and dropping.The electric piston structure was assembled and tested. The walking speed and elevating power were measured to verify the design. Then pumping test was done, and the vacuum degree was calculated to reflect the suction force, through which the conclusions were drawn that the electric piston structure can vaccum pumping steadly, and the pump efficiency can be increased by improve the sealing property of the piston mechanism, which provid references for the improved designs.