Theoretical And Experimental Research On Interference Fit Friction Coefficient

This paper studies on the "Theoretical and Experimental Research on Interference Fit Friction Coefficient", which seek proceed from the practical engineering background from DHI-DCW Group. Based on the theoretical and experimental point, the friction coefficient of the interference fit is analyzed. The result will help to obtain the performance characteristics of wind generator and lay the foundation for innovative design. This research is supported by the National High Technology Research and Development Program of China (863 program) under Grant No. 2006AA04Z101 and National Technology Suporting Program of China under Grant No. 2007BAF21B01.Interference fit friction coefficient is a friction characterization parameter expressing the surface contact condition. It needs to launch a lot of research work on its theoretical and experimental research. So this paper will firstly study the numerical analysis methods of the interference fit friction coefficient, then by the use of indirect methods, verify the fiction coefficient calculated by orthogonal experiment. Meantime, the factors which influence the friction coefficient will be discussed with the finite element analysis method. The impact size of different factors will be obtained. For the objects, this paper includes:1. Establish the two contact analysis model for interference fit and analysis the fit capacity and the maximum torque load. Based on the finite element method, the influencing factor of the friction coefficient, such as the fit capacity, taper, the surface Roughness, has been studied, and the incidence of different factors has been obtained. The specific parts of the numerical analysis include:(1) Based on the model of solving friction coefficient which is based on surface model, the analytical expression of friction coefficient is obtained;(2) Based on analysis, study the influencing factosr of the interference fit, such as fit capacity, taper, surface roughness. The incidence of different factors has been discussed; a group of the optimal results have been received;(3) Establish interference fit contact stress analysis model, with in-depth researching on the influencing factor for the interference fit friction characteristics. Based on its face - contact stress analysis method, get the interference fit contact stress, and further access to the friction and friction torque; (4) Establish theory method which can be use to describe a fit in the two parts of the size of deformation (referred to as "the volume of fit"). Based on the reconstruction contact surface mathematical theory, the volume of fit have been analyzed and calculated, which will be help to study and contact stress and the friction coefficient of interference fit.2. Design orthogonal experimental to determine the friction coefficient of interference fit, the specific contents are:(1) Design the interference fit friction coefficient test system and its orthogonal test programme table. the measured parameters have been determined. Because more factors influence on friction coefficient, the orthogonal experimental table is designed. In accordance with the orthogonal design, the details of each sample size are designed.(2) Complete the measurement, calculation and assembly of the specific samples. Surface roughness and cone profile have been measured, and the fit size has been received by tight fitting. To ensure that measurement data can reflect the true state of the surface, the error has been eliminated by using intuitive methods. Using software optimization toolbox and adaptive approach to taper cone fitting, optimal results of taper cone fitting have been achieved. The solving algorithm of sequential quadratic programming (SQP) and an adaptive initial point based on fitting step by step are provided for the optimal results. According to the results, a reduction expansion assembly way has been proposed.(3) Failure torque is determined by torsion test. The test-bed is calibrated with proving ring. Each couple of specimen is tested with time, torque and corner being recorded. The failure torque is obtained from the curve of torque and time. In order to solve issues of some samples exceeded the test-bed torque range, the large torque test-bed is designed and made specially.(4) Reconstruction surface which is based on measurements of parts has been converted into contact model with the form of nodes. By using of finite element analysis software the result of static analysis is achieved and the average friction coefficient can be implemented through accumulating the external force and force-arm.(5) Orthogonal reconstruction table is used to analyse the influence factors of the friction coefficient.After actually assembling, the levels of factor are affected.In order to satisfy the orthogonality, the orthogonal table is strongly demanded to reconstruct.The empirical formula of friction coefficient is obtained after range calculating and error rejecting. 3. Theoretical and experimental research process on the interference fit coefficient friction were analyzed and verified. On the one hand, it will improve the interference fit friction coefficient method and calculating process, on the other hand, the friction coefficient from theoretical point with the test point can be used for the wind generator and other large equipments.This paper researches on the interference fit coefficient friction. In theory, it will improve determined process of interference fit coefficient friction for the current domestic large equipments. From the test results, the paper verifies and obtains the empirical formula of interference fit friction coefficient which can be used in wind generator and other large equipments. The research results are of great value to improve the efficiency of the devices operation and operating reliability.