Research On The Sealing Characteristics Of Rodless Open-cylinder High-pressure Pneumatic Ejection Device

Rodless open-cylinder high-pressure pneumatic ejection device is a new principle launch vehicle,the compressed air is used as the power source to push the ejection piston to slide at high speed,and the sealing environment has the characteristics of strong impact,high pressure,fast speed and long stroke.The sealing performance of the ejection device is put forward higher,and the quality of the sealing performance directly affects the ejection quality.In this paper,the high-pressure and high-speed dynamic sealing characteristics of the ejection piston are studied for the sealing of the rodless open-cylinder high-pressure pneumatic ejection deviceFirstly,combined with the sealing environment characteristics of the rodless open-cylinder high-pressure pneumatic ejection device,the selection of the ejection piston sealing ring is carried out,and the combined sealing structure VL seal ring in the field of aviation hydraulic sealing is selected for the dynamic sealing of the ejection piston.The mechanical properties of the seal materials of VL seals were tested.The constitutive model of the seal material parameters was established.The loading method of fluid pressure osmotic load was used to simulate the influence of high pressure gas penetration on the contact surface,and the critical load of the seal contact surface was dynamically searched.Point,the more objective finite element simulation results of VL seal sealing performance are obtained.The effects of pre-compression rate and pressure change on its sealing performance and sealing performance under ejection are studied.It provides a theoretical basis for the dynamic sealing of the VL sealing ring for the piston of the rodless open-cylinder high-pressure pneumatic ejection deviceBased on the Isight optimization software platform,the approximate model is used to replace the complex simulation calculation.The multi-objective optimization algorithm NSGA-II is used to optimize the structural parameters of the VL seal ring.While ensuring good sealing performance,the lip seal is increased while sliding.Dynamic pressure lubricant film thickness improves lubrication performance,and reducing the Von Mises stress maximum of rubber O-ring can reduce fatigue damage,and finally obtain a set of VL seal ring structure parameters suitable for high-speed dynamic sealing of ejection piston and have longer The service life.According to the failure modes of the seals of the VL type seals in the high-pressure pneumatic ejection device of the open cylinder,the service life is predicted and analyzed.Thefailure mode of the PTFE V-ring is wear failure,and the V-ring passes.The method of laboratory friction and wear test is used to predict the life.The fatigue crack of the rubber O-ring under the high-pressure gas alternating stress will be predicted.The life prediction of the O-ring based on the fracture mechanics prediction method.In order to verify the feasibility of the VL seal ring for the piston dynamic sealing scheme of the sealing of the rodless open-cylinder high-pressure pneumatic ejection devicer,the good sealing performance and the accuracy of the simulation analysis,the static sealing performance verification test was carried out for the sealing effect of the VL seal ring.And ejection dynamic sealing performance verification test.