Research On Optimization And Lubrication Of Ejection Opening Cylinder Seal Structure

Rodless open-cylinder high-pressure pneumatic ejection is a kind of device which uses high-pressure compressed gas as working fluid to drive the load for high-speed linear motion.It has the advantages of high stroke utilization rate,high ejection speed,large ejection load,low launch cost,wide-range application,no need for thermal protection and no pollution.The pressure of the working fluid in the cylinder determines the ejection performance of the open cylinder.Too low pressure will affect the completion of the ejection work and even cause the ejection failure,resulting in a safety accident.Therefore,for the open-cylinder ejection device,the sealing performance of the sealing structure becomes very important.When the open-cylinder ejection device is activated,it is often accompanied by extreme boundary conditions such as high speed and high pressure,and the sealing environment is harsh.This paper uses the internal ballistic model of the open-cylinder ejection as the theoretical support to design the seal structure and analyze the performance.First,an internal ballistic model of an open-cylinder high-pressure pneumatic ejection device considering real gas effects and adiabatic assumptions was established,and an ejection test was performed to verify the accuracy of the internal ballistic modeling and obtain the input conditions for carrying out the sealing performance analysis.Based on the internal ballistic model as the theoretical support,combined with the sealing environment characteristics of the high-pressure pneumatic ejection device of the rodless open cylinder,based on the VL seal structure suitable for high-speed operation,a VL seal structure with a retaining ring for the open cylinder was designed as the sealing method between the piston and the inner wall of the cylinder.This sealing method can effectively reduce the friction force on the seal ring when the piston is actuated.The effects of precompression rate,gas pressure,ejection speed and temperature on the sealing performance of the seal ring were analyzed through simulation.Combined with the sealing environment of the sealing steel strip and the sealing surface of the guide rail,a labyrinth seal was selected to improve the sealing performance.Based on modern optimization design theory,a design method combining an approximate model and a MIGA optimization method was used to design the dimensions of the labyrinth seal groove.Through comparative analysis It shows that the labyrinth seal has better sealing performance than the original seal structure.Set up an open-cylinder high-pressure pneumatic ejection device sealing test bench,and conducted a sealing test to verify the sealing performance of the designed sealing structure.