| The main task of environmental scientific drilling(ESC)is coring in the lacustrine sedimentary basin stratum which is loose soft and underconsolidated.And it requires the core to be completed,unpolluted,undisturbed and keep its original state.Therefore,designing a new coring tool which can protect the loose soft core effectively has a very important significance to the ESC.A mechanical model was established based on the force situation of the core while it getting into the core pipe at first.Then the drilling devices were compared based on the mechanical model.It showed that the powered piston combine single swiveling triple-tube coring tool had the best performance.This paper put forward a overall scheme of powered piston suction coring tool(PPSCT)based on the force analysis.It consisted of four main parts,they were:(1)power source: since the device's size was limited and its speed should be accurately adjustable,this paper chose the DC geared motor to be its power source;(2)movement mechanism: this part translated motor's movement and power into the device's upward movement.This paper put forward three schemes of movement mechanism;(3)control system: this paper used a JLLSM and DC motor speed controller to adjust the device's speed;(4)piston body: it's the main part of the coring tool,and put the other three parts in or on it.Besides,it formed a seal with core pipe by the 0-ring.Principle sample machines were made after the detailed design,and related experiments were done then.The PPSCT was tested by observing piston movement state,piston tensile test,piston movement speed test and water suction test.Finally finding out the deficiencies and make an improvement.The test result showed that the improve friction wheel scheme and pump suction scheme are both took effect to some extent.The wire rope traction piston scheme provided enough suction force and speed,it met design requirement well,and it will improve the coring drilling quality and increase efficiency when applied to the ESC. |
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