Effects of Helix Angle on Root Stresses of Thin-Rimmed Helical Gears With Various Web Arrangements

Abstract

Root stresses of thin-rimmed helical gears with symmetric and asymmetric web arrangement of helix angle β0 = 10° and 20°, which were meshed with solid helical gear, were measured from the beginning of engagement to the end of the engagement by using the strain gauge method. The changes of root stresses from the beginning of engagement to the end of engagement were examined. The effects of helix angle, rim thickness, web thickness and web structure on the root stresses, the maximum root stress and the meshing position, where the maximum root stress (worst loading position) occurs, were clarified. Furthermore, the obtained results were compared with the results of the solid helical gear. On the basis of these results, the maximum root stress of thin-rimmed helical gears with helix angle β0 = 10° occurs at the outer point of single tooth contact, and at the position of a transverse base pitch distant from the tip toward the root along the line of action for β0 = 20°. For thin-rimmed helical gears with the same rim thickness, web thickness and web structure, maximum root stress increment ratio (maximum root stress of thin-rimmed helical gear divided by maximum root stress of solid helical gear) of thin-rimmed helical gears with helix angle β0 = 10° are larger compared to the case of β0 = 20°.