Door System In Urban Rail Transit Of Long Screw Nut Pair Design Research

In this dissertation, multi-start screw-nut pair of the vehicle door system is considered as the research object. By means of the finite element technology, virtual prototype technology and orthogonal test, the steep-lead multi-start screw pair is studied in depth. And the impact of different design parameters on the performance of screw pair are compared and analyzed. The design parameters are preferred, which provide a basis for the design and optimization of the structure of screw pair.Firstly, this paper introduces the basic structure of the door system and transmission principle, and in-depth analyzes design requirements and influencing factors of the transmission mechanism in the door system. Secondly, through the establishment of the physical model, loads of lead screw and nut under different working conditions are analyzed. According to transmission efficiency formula under different working conditions, the impacts that spiral helix angle, thread angle have on the screw driving efficiency are discussed. Additionally, the design and verification of the screw pair are completed systematically.Secondly, this paper studies the nut meshing technology. And by using the HYPERWORKS software, hexahedral meshes suitable for contact analysis are obtained. By analyzing and comparing the impact that different leads and numbers of starts have on the stress distribution of screw nut through ABAQUS, the nonlinear finite element analysis software, stress distribution law is obtained. Through Orthogonal experiment method, the optimal combination of lead and number of starts is determined, and significant influential factors are analyzed. Through the equivalent model, the stress and strain of screw are analyzed, and the impact that different thread angles have on the stress and strain are compared and analyzed. In addition, how leads and starts of screw affect the natural frequency of the screw is studied.Finally, kinematics simulation of rail vehicle door system is carried out through ADAMS. The simulation results show that the movement of the steep-lead screw pair meets the requirements of door systems. Moreover, the velocity curve is improved from trapezoidal to a parabola-straight curve, so that the screw pair could work smoothly.