Abstract: The helicoid pushing chain mechanism is a novel telescopic mechanism used to push objects from one position to another one rapidly.It occupies a minimal amount of space in the contact status. In constrained space the helicoid chain case adopted may store as many links as possible for acquiring a long telescopic distance. In order to analyze the influences of polygon effect and meshing impact on the dynamic properties and pushing stability of the unidirectional chain, the dynamics models are established for the processes of extracting the unidirectional chain from the helicoid chain case and it meshing with the sprocket. Meanwhile, the extended part is simplified as a multi-spring-damping system, and the dynamics model of pushing process is deduced. The full dynamics models is numerically simulated by using MATLAB software and Rung-Kutta method. The simulation results show that the drawing force acted on the unidirectional chain in the chaincase drops down to zero concussively over time, and the change of the thrust force transits form drastic oscillation to smooth fluctuation. Besides, the pushing velocity of the chain is nearly constant during the pushing process. Hence this mechanism has an excellent pushing stability. In addition, the established dynamics models are verified by the experimental measurement of the pushing velocity.

Key words: ordnance science and technology, pushing chain mechanism, linear telescopic mechanism, polygon effect, unidirectional chain, multi-spring-damping system