Simulation Research Of Y-Seal In Washing Mechanism Of Rock Drill Under Water Lubrication Condition

High pressure water washing system is often used in hydraulic drill to wash the broken rocks out of drilling hole,which can improve drilling efficiency significantly.Because of reciprocating-rotary movement of the drill tail and low viscosity properties of pure water,in the process of drilling,makes the seal to be failure easily.And it is difficult to replace a new seal when the old one invalid,which affects the work efficiency of drilling equipment.This has been an engineering roadblock of rock drill machine industry.In this paper,I aim at predicting the life of Y-seal working in pure water.It has been studied systematically that of the water lubrication model,contact stress distribution,water film thickness distribution.And the expected results have been achieved.In the full absorption of domestic and foreign similar research,this paper has analysed the work properties of drill tail,given a contact model of Y-seal,provided a lubrication equation based on the normal form of universal Reymolds equation,built the mixed lubrication model of Y-seal and given the water film thickness calculation formula.All of those works could lay a necessary theoretical basis for the further research.Based on ABAQUS simulation software,the three-dimensional seal contact simulation model of Y-seal was established,the distribution law of seal contact stress under the compound condition of reciprocating rotation was given,and the effects of rotation velocity,reciprocating impact velocity and friction coefficient on seal contact stress were studied.The results show that the change of rotation velocity has no obvious effect on the maximum principal stress and contact stress of the seal,while the increase of temperature will reduce both the contact stress and the maximum principal stress of the inner and outer travel of the seal ring.Changing the reciprocating impact velocity and friction coefficient will have an obvious influence on the seal contact stress,and the internal and external travel has an obviously opposite trend of change,so the influence of internal and external travel must be taken into consideration when analyzing and predicting the seal life.Using the simulation data and based on the theory of fracture mechanics,the equivalent stress was selected as the fatigue damage parameter,the strain energy release rate of internal and external travel was calculated,and the fatigue life of the Y-seal at the bottom of the u-shaped mouth,the inner lip of the seal,and the dangerous element of the outer lip of the seal was calculated through the strain energy release rate.Through calculation,it is found that the bottom of u-shaped mouth of sealing ring is most prone to fatigue failure.After the calculation of fatigue life,the influence of small fluctuation of working pressure and change of friction coefficient on the fatigue life of dangerous element at the bottom of u-shaped mouth was further studied.Using reciprocating rotation composite under the action of water sealing contact stress simulation results,combining the calculation formula of sealing contact water film thickness seal friction interface water film thickness distribution,and compares them with RMS of contact surface roughness value,determine the sealing ring in the condition of movement of the reciprocating rotation composite water lubrication state and friction and wear types,at the same time,according to the Archard friction and wear theory,calculation of reciprocating rotation of Y-seal under the condition of water seal wear quantity,andstudies the pressure fluctuation and friction coefficient on the influence of the wear life of sealing.Through the above theoretical analysis and numerical simulation,it provides reference and theoretical support for the life prediction and design optimization of the pure water seal for the high pressure water washing mechanism of drill and the design and research of the high frequency rotating axial fretting compound pure water seal.