Effects of tooth modifications on mesh characteristics of crossed beveloid gear pair with small shaft angle

A numerical design approach with tooth modifications to improve the mesh characteristics is presented for crossed beveloid gears. The mathematical model of the beveloid tooth surface with different modifications was developed. Considering the first principle direction (FPD) angle, the effects of tooth modifications on contact ellipse, contact path, transmission error, relative curvature were investigated by theoretical tooth contact analysis. For large FPD angle, independent helix crowning modification and flank line slope modification can increase the area of contact ellipse. But the flank line slope modification tends to increase the transmission error. Profile crowning modification has a degressive effect on the meshing. The contact ellipse and relative curvature are not sensitive to the transverse profile slope modification. For small FPD angle, flank line slope modification and helix crowning modification can improve the mesh characteristics. But the transmission error decreases firstly then increases and the area of ellipse increases with the increase of helix crowning modification. Compared to the large FPD angle situation, the mesh behaviors for small FPD angle are more sensitive to the tooth modifications. Finally, the loaded tooth contact analysis were performed and it shows a good correlation with the theoretical tooth contact analysis results. (C) 2017 Elsevier Ltd. All rights reserved.