| Metal V-belt is the main components of metal pushing V-belt type CVT. The performance and life of the metal V-belt have a direct impact on the performance of CVT.The studys on these of the metal V-belt are very important. The subject comes from ChongQing Science research project:"The key technologies research for the transmission mechanism of metal pushing V-belt". (Item Number is:CSTC.2005AB6019). The main research topics are: firstly, transmission performance of the metal pushing V-belt which is the development of our college; secondly, failure diagnosis for the failure cases. The researches have had certain progress.Firstly, for the objectives of transmission performance and life test, reference to the experimental equipments structural and components what the colleges and enterprises at home and abroad use for the transmission study, a test-bed is built. My teachers help me a lot. The use of test-bed shows that it has the ability to complete the trial.Secondly, we make scientific researches on the efficiency of metal V-belt in order that get a driven thrust which corresponds to the maxium transmittable torque. This thesis analyzes the power loss of the CVT in theory. And a efficiency trial program is designed. It is experimented that the relation between slip rate and transmission efficiency. Compare and contrast our data with the data come from other's papers. We conclude that the efficiency trial program is feasible. The limit range of clamping force is gain by experiments. The research on the relation between friction factor and torque ratio is done.And we analyze the reason why the friction factor can not be used directly. The relation between efficiency and torque ratio experiments in the limit speed ratio . When the clamping force is 2.1Mpa, it is gain that the maximum transmittable torquein in the limit speed ratio. We determine the most reasonable clamping force is 2.2Mpa, which have the ability to transmit the maximum torque 128N·m.By using optical microscopy and scanning electron microscopy we analyze the fracture of the failure cases which appear in the test. According as macroscopical fracture surface analysis, we judge the first fracture mode is brittle fracture.And we find the fracture fountainhead and the fracture extended ways of the failure blocks. According as microcosmic fracture surface analysis, we confirm that the fracture appearance is intergranular. And then we analyze the stress condition in accident conditions.The stress condition of the elements in the most dangerous place is calculated. We carry on the intensity analysis to the finite element model by using software Abaqus, and we obtain the elements structural stress distributions in the condition. The results testify the conclusion of fracture surface analysis. The failure mode for this belt may be overloading (belt slip).It is summarized that the failure perform as fracture elements and rings, deformation of the rings, bonding between elements and sheave, and scratch on sheave.Life research is the basic work and a urgent need to carry out before our metal pushing V-belt is widely used. Based on the fatigue test data of the steel ring of metal V-belt, this thesis confirms that the life distribution of steel ring obeys the lognormal distribution by using the graphic and the numerical analysis. And the parameters of the distributing function are estimated. It is obtained that the reliable life expressions of the steel ring. And the life trial program is designed on the basis of the conclusions.
|
PDF Full Text Request