Driving Characteristics Analysis Of A Flexible Screw Mechanism

This paper' main research work is focused on a new type of flexible screw drive, which is on the basis of the principle of screw. With a flexible shaft and small internal friction, this novel mechanism can achieve curvilinear motion and drive the squirm robot through the elbow of the pipeline smoothly, thus, has broad application prospects.In this paper, the driving characteristics of the novel mechanism was studied by both theoretical and experimental methods. The shape and size of the flexible shaft was optimized according to the stiffness design goal.And the critical buckling length of the shaft was deduced. By establishing the kinematics model of the roller and the flexible shaft, the pure rolling point location and the slipping condition of the roller are given in analytical form solution. And the feed speed of the flexible shaft was proved to be related to the axial load. In consideration of the internal friction and the elastic potential energy fluctuations, the transmission efficiency model of the mechanism was established. The rigid-flexible coupling model between the roller and the flexible shaft illustrates that the roller stress concentration problem is due to the big stiffness difference between the roller end and the flexible shaft. Based on this conclusion, two improvements, namely using soft base and reducing the roller helix angle,were proposed and proved to be feasible by finite element simulation.Finally, the driving characteristics of the flexible drive mechanism was evaluated by the experimental platform. The measurement data of the roller sliding rate, the transmission deficiency and the flexible shaft critical buckling length verified the theoretical proposed modeling. The research provided reference for the type selection and drive travel design of the novel mechanism.