Design method and its misaligned contact characteristic of aviation crowned spline

In view of the imperfect design method of the crowned involute spline and the uncertainty of the range of the modification amount，a method of designing the crowned involute spline was proposed by using the allowable stress of the spline tooth surface and the interference of the inner and outer splines to determine the range of the crowned amount of the crowned spline.Taking the spline of a central transmission rod of an aero engine as an example，design of the crowned spline was carried out；and the contact characteristics of the ordinary spline were compared with those of the crowned spline under the alignment and misalignment state respectively.The research results showed that under the aligned condition，ordinary spline contact stress was concentrated on the tooth loading end，while the contact stress of the crowned spline was located in the axial tooth middle and the contact stress increased；in the misalignment state，the number of contact tooth pairs of the ordinary spline significantly reduced and the contact stress significantly increased，while the load-sharing effect of the crowned spline was significantly improved and the contact stress significantly reduced.As the misalignment increased，the ordinary spline had the risk of tooth breakage due to interference，while the crowned spline could still engage but the number of disconnected tooth pairs increased，and the contact stress also increased sharply.The determined range of the crowned spline modification amount was reasonable，and it can quantitatively couple the tooth backlash，misalignment compensation ability，and the modification amount.The research results provide an important theoretical basis for designing aero crowned splines，controlling the misalignment and improving the load-bearing capacity and the wear life.