Theoretical And Experimental Study On Transmission Mechanism Of Plastic Worm And Steel Helical Gear

Automobile seat is an essential part of the automobile and important safety component.Power seats used to improve comfortableness have been applied widely in the middle and top grade automobile,whose function includes the front and back adjustment of seat,the up and down adjustment of seat,backrest adjustment,etc.The horizontal transmission mechanism of seat in this thesis is specially used to the front-back adjustment of seat.The horizontal transmission mechanism consists of two parts mainly,gear transmission part and screw transmission part.This paper proposes a transmission model of plastic worm and steel helical gear to meet high load capacity,long service life,low vibration and noise of transmission mechanism,etc.The transmission of plastic worm and steel helical gear,in which plastic worm is instead of the traditional metal worm and metal helical gear is instead of the traditional metal worm wheel,is a drive mechanism for transferring power and movement.Due to the particularity of plastic materials,there aren't a unitive reference standard for design of plastic gear,and it isn't suitable to design plastic gear according to the standard of metal gear.Thus,the research on meshing characteristics,load deformation,contact status,tooth surface wear etc.of plastic worm and steel helical gear will be more useful,and also to the application in practice.The main contents of this paper include:(1)The correct meshing condition of plastic worm and helical gear is derived by legend.The equation of worm's tooth surface is built based on the processing principle of worm.Based on principle of gearing,meshing equation of plastic worm and helical gear is derived,what's more,it's turn to be point contact.(2)According to the tooth surface equation,3D model of plastic worm and steel helical gear is established by Mathematica and UG.On this basis,the method of establishing high quality finite element model of plastic worm and steel helical gear is proposed.Then,the dynamic contact FEA of the gear pairs of plastic worm and steel helical gear,and the gear pair of steel worm and helical gear is carried out in ANSYS respectively.(3)Based on the theory of tooth profile modification,the method of profile modification of plastic worm and steel helical gear is proposed.The finite element model of gear pair after modification is established,whose dynamic contact FEA is carried out.As a comparison,the influence of addendum rounding radius on performance of plastic worm and steel helical gear is study by FEM.(4)The samples are machined.Then,based on the micro-transmission test platform,the comparative performance tests of the plastic worm and steel helical gear and the steel worm and steel helical gear,such as,efficiency test,vibration test and so on,are carried on.In addition,the platform of durability test is built,and the durability test is carried out.