| The ball piston pump takes ceramic ball of high accuracy as its piston and allocates water by its shaft. With wear-resisting plastic covering on cylinder surface, it establishes seel surface by rigidity of piston and elastoplasticity of plastic, hence greatly reduces flow leakage. High-speed alternate motion leads to great friction between the contact surface of ball piston and cylinder and fatigue rupture such as material wear. Meanwhile, in the process of compression, ball piston will move to one side of cylinder due to eccentric force and poses great lateral pressure on the surface of cylinder. It’s no good for lubrication due to severe deformation.This project starts research from two aspects. For one thing, it establishes kinematic model of ball piston pump, studies the motion trail of ball piston along the stator track and works out the variation regulation of contact stress of ball piston toward stator orbit. Meanwhile, based on characteristic equation under cylindrical coordinate of homocentric ball piton pair, it works out distribution character of contact stress and strain of eccentric ball piston pair as well as its contact structure in theory.For another, it does experimental research on the theoretical analysis mentioned above to test its correctness. To establish test-bed, it designs and processes ball piston pump made of admiralty brass whose working pressure is around5Mpa as well as testing device for frictional wear of ball piston pair and flow leakage.It researches the character of stress and strain through theory modeling and numerical simulation and provides feature parameters for the research. It describes distorted pattern of ball piston pair on the basis of the establishment of elastic mechanics equation and judges the reliability of sealer indirectly through flow leakage measurement under particular working condition. All the researches mentioned above finally lead to characteristics of stress and strain of ball piston pump. |
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