Research On Rotary Seawater Hydraulic Tools And Its Power System

Seawater hydraulic underwater tool system using seawater as the working fluid solves some serious problems causing by oil working fluid and owns many great advantages including simple system, reliable work, high efficiency, unrestrained working depth, lightness, good concealment, agility etc. This is the development direction of underwater tools and the best choice of underwater work.Based on the 300m Seawater Hydraulic Power System successfully developed by Huazhong University of Science and Technology, two rotary seawater hydraulic underwater tools, including hydraulic impact wrench and hydraulic abrasive disk saw are developed and the power system ,and a movable seawater hydraulic power pack driven by boat electric motor are researched.The hydraulics impact wrench adopts the structure of ball lead screw groove. The parameters of spring rigidity, hammers'mass and hammers contacting area are analyzed and designed using the collision principle and vibration theory. According to the principle of ergonomics, the structure design of the impact wrench control valve and the layout of returning water outlet are completed.Since the viscosity of seawater is much larger than that of air, viscous resistance in the water is much larger than in the air. A formula is deduced using the theory of the flat plate boundary at the situation when abrasive disk saw revolves in the seawater. Reasonable matching relation of viscous power loss in the seawater with parameters of cutting abrasive disk is confirmed.The seawater hydraulic power pack is removable, can drive rotary tools and reciprocating tools at the same time and has two pressure grades of 12MPa and 24MPa produced respectively by seawater hydraulic pump and manually-operated pump.At last, the relation of the impact torque of the seawater hydraulic impact wrench with rotary speed and impact time is studied experimentally. At the same time, the function of the viscous power loss with the rotary speed, disk's diameter, thickness and roughness when the seawater hydraulic abrasive disk saw works underwater is also obtained. Based on the test results a fitting calculation formula on the viscous power loss of the abrasive disk saw is established and compared with the theoretical formula. Test results also show that the performances of the two tools meet the design requirements.