| The quality of auto parts is an important guarantee for the development of the automotive industry.Ball joint is an important part of the car chassis system,which determines the sensitivity,accuracy and driving stability of the car steering,and also plays a role in carrying the body weight and transmitting torque.Therefore,in order to improve the quality of the ball joint,the ball joint in-depth study is necessary.The main performance index of the ball joint is the torque,the main feature of a good ball joint product is the torque value that meets the production requirements and its discreteness is small.This require designers to make the ball joint torque controlled in the design phase.The torque mainly determines by the contact face friction between the ball pin and the ball bowl.This paper firstly studied on the friction characteristics of the friction pair.Then based on ball joint product do the orthogonal experiment and infinite analysis,and established a model of influences and the friction torque.Based on the CETR-UTM multifunctional friction and wear tester,the influence of the material,roughness,lubricant,pressure,contact area and speed on the friction force were studied by rotating motion pin-disk experiment.At the same time,the Stribeck effect of friction pair was observed according to the change of velocity.The friction hysteresis and friction lag phenomenon of the friction pair were observed by reciprocating linear motion pin-block experiment.Then,the orthogonal experiment confirmed the main influencing factors of ball joint torque are the magnitude of interference and contact area between ball pin and bowl,In order to establish the function model between the main influencing factors and torque,the paper did the finite element analyzation of the ball joint and calculated the ball joint torque.In the finite element analysis process,due to the lack of ball material AL6082 material parameters,a linear tensile test of metal material was designed to obtained parameters such as elastic modulus and Poisson's ratio.At the same time,based on the lame formula calculated the contact pressure of a hypothetical interference fit ring pair.Comparing the ring pair contact pressure of the finite element with the corresponding value of lame formula to verify the correctness of the finite element analysis progress.Then,taking the main influence factor as the independent variable and the torque as the dependent variable,a binary quadratic function was established as the torque model by the lstopt software.After that comparing the ball joint torque of the model with the corresponding torque value in the orthogonal experiment to verify the correctness of the torque model.The model can be applied in engineering practice to solve the problem that engineers design the product only base on experience.This paper studied preliminarily on ball joint friction torque and the ball joint frictional mechanism.There are many residual aspects worth to further study such as the friction mechanism of sticky slip and the interaction of ball joint influence factors. |
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