Design Simulation And Tribological Analysis Of New Fuze Safety Mechanism

The no-return moment clock mechanism is an important component of the fuze that controls the detonation time.If the projectile collides with the bore wall,the no-return moment clock mechanism may reverse,causing the detonator seat to misalign with the detonating charge.This would result in a failure of the detonation sequence and the fuze.Poor lubrication of the mechanism can also reduce its motion accuracy and cause inaccurate timing.Eventually,this could lead to shells that do not operate within their intended time range.Therefore,designing a new fuze safety mechanism and analyzing its tribological characteristics have important engineering significance for improving the reliability of projectile action.In this paper,a new fuze safety mechanism that prevents reverse rotation of the detonator seat is proposed to solve blind fire caused by failure to align the detonation sequence.structural dynamic characteristics is analyzed to obtain working conditions of key contact areas and then analyze tribological characteristics to master lubrication conditions of key contact pairs of mechanism.This can reduce low motion accuracy caused by poor lubrication of mechanism and inaccurate timing problem.(1)To address the problem of reverse rotation of the existing no-return moment clock mechanism,its structure is improved and a new safety mechanism is designed for large caliber rotary projectiles with no-return moment.its structure’s rationality is verified by simulation analysis.(2)This study focuses on the escapement mechanism.It is obtained that the variation law of contact parameters between the clamp pendulum and escapement affected by minimum film thickness.Based on this,it is established that a new fuze safety mechanism dynamic and elastohydrodynamic analysis model that considers precise contact characteristics between clamp pendulum and escapement.(3)It is analyzed that the bearing and lubricating properties of the escapement under different projectile rotation speeds,different types of greases,and different structural parameters of the escapement.It is analyzed that the influence of different projectile rotation speeds on contact load,oil film thickness,and oil film pressure of the escapement mechanism.The results show that as projectile rotation speed increases,contact load between escapement mechanisms increases,maximum oil film pressure in contact micro-area increases,minimum oil film thickness decreases.The greater the lubrication failure efficiency of the new fuze safety mechanism,the greater the possibility of inaccurate timing.It is also studied that contact load,oil film pressure,and oil film thickness variation between escapement mechanisms under different greases.It is found that compound barium grease provides best lubrication between clamp pendulum and escapement,leading to better working performance of mechanism.It is explored that the influence mechanism of different structural parameters of the escapement mechanism on contact load,oil film thickness,and oil film pressure between escapement mechanisms.The results show that the maximum oil film pressure is small and the minimum oil film thickness is large in the contact micro-area of the escapement mechanism when the swing thickness is greater than the escapement wheel thickness.The lubrication performance of the escapement is better under these conditions.It is studied that elastohydrodynamic lubrication performance of escapement mechanism by parameterization.The results show that the thickness of oil film increases sharply with an increase in rheological index.Therefore,choosing grease with a larger rheological index is more beneficial to timing of new fuze safety mechanism.(4)Taguchi method is used to analyze the influence weights of projectile rotation speed,rheological index,and structural parameters on minimum oil film thickness of escapement mechanisms.The results show that rheological index has the most significant effect on minimum oil film thickness of escapement mechanisms,followed by projectile rotation speed and structural parameters.This analysis conclusion provides a theoretical basis for reducing lubrication failure of escapement mechanisms during working process.That is,using grease with a large rheological index,using the safety mechanism with the projectile fuze with low speed,and using swing thickness greater than escapement wheel thickness can effectively prevent lubrication failure of the escapement mechanism.