| Selecting a correct friction coefficient is the premise of the security and reliability of interference fit design. It directly affects the magnitude of the shrink range designed, so as to determine the magnitude of torque transmitted by interference fit.Based on the interference fit between input shaft and major planet carrier of Aerogenerator's accelerator of DHI-DCW Group, an orthogonal experiment is designed used to analyses the influencing factors of interference fitted friction coefficient and the contribution of each factor is calculated with the finite element software.Firstly, this paper introduces the status of the development of friction coefficient of interference fit in domestic and abroad, as well as the background and the meaning of this research.Secondly, the measurand is determined by the formula of friction coefficient of interference fit and an orthogonal experiment is designed for influencing factors. The surface roughness and surface profile are measured, and a method is proposed based on radius difference for the gross errors. a method based on adaptive cone is supplied for cone fitting. The solving algorithm of sequential quadratic programming(SQP) and an excellent initial point based on fitting step by step are provided for the optimal results. The calculation results show that the evaluation of cone error is averagely decreased 13.9%. The shafts and sleeves are regrouped to ensure the assembly dimensions in according with the level of orthogonal factor, then assembled with the swell-shrinking method.Failure torque is determined by torsion test. The test stand is calibrated with proving ring, then each couple of specimen is tested with time, torque and corner being recorded. The catastrophic value of friction torque with time is the failure torque.Finally, friction coefficients of every couple of specimen are calculated based on the revised formula of friction coefficient of interference fit. Meanwhile, the influence of influencing factors on friction is computed with finite element software and established the relation through contact pressure. Experiment results indicate that the influence of shrink range is maximal, the influence of taper takes second place, the influence of surface roughness is least. The percentage of the influence are respectively 88.6%, 9.2%, 2.2%. When shrink range of interference fit is under 0.0847mm, friction coefficient increases correspondingly with the accretion of shrink range. However, if shrink range of interference fit exceeds 0.0847mm, friction coefficient decreases with the increase of shrink range. |
