Applied Mechanics and Materials Vol. 86

Abstract: If the contact pressure between mating flanks of a gear set is increased, the lubricant film thickness in between is reduced to a level where the asperities of the flanks start to touch. This case where the surface roughness is of similar value as the EHD film thickness is called “mixed friction”. Due to the metallic contact of the asperities and the movement of the flanks with respect to each other, the flanks are damaged. The damaged flanks appear dull or greyish, hence the name “grey-staining” (or “Graufleckigkeit” in German), see e.g. [4] or [1]. Micropitting are small cracks on the surface of the gears (as opposed to pitting, where the cracks form below the surface), which grow into the material. The size of the damages is about 10-20 mm depth, 25-100 mm length and 10-20 mm width. Micropitting is mainly observed with case carburized gears but may also be found in nitrided, induction hardened or through hardened gears. Micropitting mainly occurs in areas of negative specific sliding. Negative specific sliding is to be found along the path of contact between point A and C on the driving gear and between point C and E on the driven gear.

Abstract: The paper conducted a modal analysis of an internal helical gear based on AWE, and obtained its first 6 order natural frequency. Then the paper analyzed the influence of its parameters on the vibration characteristics of the internal helical gear, found that if the helix angle, the normal module, the number of teeth of the internal helical gear change, its vibration characteristics will change, but the change of the pressure angle doesn’t influence its vibration characteristics.

Abstract: For the sun gear shaft in wind turbine gearbox, the deformation will occur on the inner spline because of the thermal inserting of ring gear. So, the spline pair should be tooth relieved to avoid decrease of backlash and conflict of copulate parts. Based on the finite element analysis results, the deformation caused by the thermal inserting on the inner spline was calculated, and the theoretical tooth relieving curve was got. The practical thermal inserting deformation on the spline was measured. And the results indicate that the measuring deformations are in good consistency with the deformation calculated by finite element analysis method. The spline deformation and tooth relieving calculation method can provide a reference for the tooth relieving of the spline on long structure sun gear shaft in 1.5MW wind turbine gearbox.