Analysis and comparison of noise and vibration of spur gears finished by advanced finishing processes

Abstract

Gears are essential elements of various machine and equipment which are used to transmit motion and/or power mechanically and positively with and without change in the direction and/or speed of rotation by the successive engagements of teeth on their periphery. Since gear is an essential rotating element of any machinery or equipment their gears or their assembly generally produce vibrations due to varying load on the gear teeth When these vibrations are transmitted to the other parts of the transmission system then they create unpleasant sound which is referred as noise. Noise and vibration caused by the rotation of the gears is considered a big problem. Advanced finishing processes can be used to correct manufacturing error on the tooth face and flank surfaces. Present work addresses the impact of tooth micro geometry error on the noise and vibrations. In present work noise and vibratory performance of two advanced finishing processes like Pulsed Electrochemical Honing (PECH), Abrasive Flow Finishing (AFF) and near-net shaped gear manufactured by unconventional manufacturing process (WEDM) were compared with unfinished spur gear manufactured by conventional process hobbing. Results have shown that noise and vibrations of gear depend on the quality of gear. It has been noted that gear manufactured by WEDM have very good quality and produce less noise and vibration as compare to AFF and PECH finished gear at all measured conditions. ECH is a hybrid finishing process which combine the capabilities and advantages of electrochemical finishing (ECF) with mechanical honing and simultaneously overcome their individual limitations. Present work reports on improving the surface quality of 20MnCr5 alloy steel spur gears in terms of microgeometry. Pulse-on time of 3 ms, pulse-off time of 6 ms, finishing time of 8 minutes and voltage of 16 V produced the best surface quality gear. The average percentage improvement in total profile error (PIFa), total lead error (PIFb), cumulative pitch error (PIFp) and in total runout error (PIFr) being as 18.8% (for gear-1); 33.3% (for pionion-2); 33.2% (for gear-1); and 20.2% (for pinion-1) respectively. Abrasive flow machining is an advanced abrasive finishing process. In the present work surface property of 20MnCr5 alloy steel spur gear reported in terms of microgeometry improvement. Extrusion pressure 5 MPa, finishing time of 15 minutes and SiC abrasive particle of mesh size 150 with 30 % weight concentration produced the best surface quality gear. The average percentage improvement in total profile error (PIFa), total lead error (PIFb), cumulative pitch error (PIFp) and in total runout error (PIFr) being as 17.5% (for gear-2); 41% (for pionion-3); 13.0% (for gear-2); and 3.8% (for gear-1) respectively.WEDM process is a thermo-electric erosion process in which workpiece material is removed by melting and vaporization caused due to series of electric sparks occurring between a very thin wire and electrically conductive workpiece. This work exploring the wire electric discharge machining (WEDM) process for manufacturing high quality spur gear of 20MnCr5 alloy steel. Optimized parameters in the present work for less microgeometry error were (i.e. voltage 12V, pulse-on time 1μs and pulse-off time 49.5 μs). The values of total lead error (3.8 μm), cumulative pitch error (60 μm), 2nd minimum value of total profile error (47 μm; gear-5 has minimum value of 45.6 μm), and 5th minimum value of total runout error (83.4 μm; is gear-6 has minimum value of 50.4 μm) were obtain in the present work.