Motion, Efficiency And Finite Element Analysis Of Marble-disk Loading Mechanism Of The Dry Disc Brake

Marble-disk loading mechanism is a kind of screw transmission mechanism,which is composed of rotating disc,marbles and moving disc and provides pressure for dry disk brake.Dry disk brake is mainly used in tracked armored vehicles,using full contact braking,which has large friction area and much heat generation.In recent years,tracked armored vehicles are increasingly used in plateaus,mountains and deserts.Because there are many slopes on plateaus and mountains,the speed of the vehicle is faster,the braking tasks are more frequent,the brake load is higher,and the heat generated is more.The disadvantage of overall friction is poor heat dissipation performance,which will make the brake appear higher heat accumulation and make the working conditions of the marble-disk loading mechanism more severe,or even cannot work properly.Therefore,it is of great significance to study the marble-disk loading mechanism to ensure the reliability of the dry disk brake and the safety of the vehicle.First of all,the mechanical model of marble in cylindrical spiral groove is established in this paper,and the reasons of radial slip,wedging effect and contact angle of marble in cylindrical spiral groove are analyzed,as well as the calculation method of the maximum contact Angle.By building the motion model of the marble and the moving disc,the influence of the mechanism parameters on the rolling and spinning of the marble and the movement of the moving disc are studied.This paper analyzes the reason why the marble slides in the groove after large deformation,and puts forward the condition that the marble slides or rolls in the groove.And then the mechanical models of parts in marble-disk loading mechanism are set up to deduce the force transfer function and mechanical efficiency function of marble-disk loading mechanism in the process of forward transmission and reverse return.The influence of the inclination angle and friction coefficient of the groove on the force transfer efficiency and the mechanical efficiency of the marble-disk loading mechanism is studied.These researches provide theoretical basis and suggestions for the parameter selection of the marble-disk loading mechanism.And then through the establishment of finite element analysis model of marbledisk loading mechanism,the contact characteristics of the billiard and rotation are analyzed and the stress and strain behaviors of the marble-disk loading mechanism under high load and high temperature environment are studied.And the influences of typical parameters(including friction coefficient,spiral angle,the ratio of the radius)on the stress state of each part of the marble-disk loading mechanism are analyzed.Finally,aiming at the shortcoming of small contact area and high contact stress between marble and cylindrical spiral groove,the design method of tapered roller-disk loading mechanism is proposed,and the edge effect of straight generatrix tapered roller is analyzed.The convexity design of roller can effectively eliminate the edge effect of tapered roller and make the stress distribution more uniform along the generatrix.