Analysis of noise and vibrations of helical gears finished by abrasive flow finishing

Abstract

Gear is a toothed wheel used in machinery to transmit motion and/or power to perform the intended task. Gears are the main exciter of noise and vibration in all machines wherever used. Vibrations generated due to gear motion are transmitted to surrounding structure and airborne noise is produced. The primary cause of noise and vibration in gears is force variations due to rough surface, microgeometry errors and load variation. Finishing processes play an important role in reducing surface roughness and microgeometry errors. In present research work helical gears made up of 20MnCr5 alloy steel were manufactured by hobbing process and finished by Abrasive Flow Finishing (AFF) using optimum parameters which are extrusion pressure 5Mpa, abrasive mesh size 100 with 30% volumetric concentration, abrasive particles of SiC and finishing time 25 minute. In present research work it was observed that there is reduction in surface roughness, microgeometry errors leading to reduction in noise and vibration levels of the AFF finished helical gear pair. Three parameters of roughness (i.e. average surface roughness ‘Ra’, maximum surface roughness ‘Rmax’, mean roughness depth ‘Rz’), four parameters of microgeometry (i.e. total profile error ‘Fa’, total lead error ‘Fb’, total pitch error ‘Fp’ and radial runout ‘Fr’) and RMS value of overall vibration and vibration at gear mesh frequency were measured before and after finishing of the helical gears.