Index System Construction Of Tightening Process For Solid Rocket Motor Based On Seal Mechanism

Solid rocket motor plays an important role in the strength of national defense and is the embodiment of a country's comprehensive national strength.As a booster,solid rocket motor powers missiles and spacecraft.It's the important part of missiles and spacecraft.Among the many key technologies in the production of solid rocket motor,tightening assembly process is the core technology of the solid rocket motor manufacturing process,which is related to the reliability of solid rocket motor.Tightening assembly process demands threaded to connect shell and nozzle,while the shell and the nozzle compress rubber seals to ensure that the solid rocket motor can have a good sealing performance to prevent the safety accident due to sealing ring leaks at work.The current tightening process index,is a range,is required to be 10% to 30% for the compression rate of seal ring tightened.This will increase the uncertainty of tightening process in the actual operation,and lead to use different tightening process index and get a different amount of seal compression for the same model.Meanwhile,consider the process error in tightening process.The amount of seal ring compression will be more discrete for the tightened work piece,and it deviates greatly from the actual expected value.Ultimately,the uncertainty of process index will lead to the reduction of sealing safety and reliability for solid rocket motor.In this paper,the aging characteristic of solid rocket motor in storage stage is studied.The aging model is based on the power exponential function and the Arrhenius formula is used to predict the aging reaction rate.The aging model of silicone rubber at room temperature is obtained through aging experiment and data processing,which describes the aging characteristics of solid rocket motor in storage stage.Aiming at the problem that the residual stress of seal rings can't be detected directly when the sealing ring rebounds,this paper studies the rebound characteristic of solid rocket motor in the working phase.Through mechanical analysis,the quantitative expression of relationship between the pressure difference and the draw ratio before rebound and after rebound for sealing ring is obtained and used as the springback model of the sealing ring.The correctness and applicability of the springback model were verified through experiments.In order to study the sealing characteristic of solid rocket motor,this paper presents a sealing theory based on the leakage rate.The porous media leakage model suitable for a solid rocket motor is proposed through the reasoning of leakage rate model.Conduct leakage rate test,regression analysis of experimental data to determine the relevant parameters in the leakage rate model.This article takes the storage process and work process for the tightened solid rocket motor as a sealed life cycle and its mechanism is analyzed.Taking the leakage rate as the performance index of the seal safety and the index system of tightening process was obtained based on the aging model,rebound characteristics and leakage rate model of seal ring for solid rocket motor.In this model,the quantitative relationship between the compression rate of sealing ring and the seal leakage rate is established,so that the tightening index can be changed from an interval range to a certain value.By the model validation experiments and comparative experiments,the correctness and the optimal performance of index system is proved,which is in favor of improving the consistency of the products and improving the reliability and rationality of tightening process.