Today, the motor vehiclemarket is focusing on “lubed for life”differentials requiring no service for the life of the vehicle.Still, differentials are prone to develop problems of one sort oranother since they are used to transmit a heavy torque through aright angle. Oneweak point in the differential is the ring andpinion gearset. As such, a proper break–in period is essential toattain the required service life. Break–in is an attempt to smooththe contact surfaces of the gears and bearings through controlledor limited metal–to–metal contact. The roughness of the contactsurfaces is reduced during this process until a lower andrelatively stable surface roughness is reached. The lower surfaceroughness is advantageous, but irreversible metallurgical andlubricant damage occurs since break–in always results in stressraisers, metal debris and an extreme temperature spike. Break–inand its negative effects can be eliminated with chemicallyaccelerated vibratory finishing. When this method is used tosuperfinish ground (AGMA Q10) or lapped (AGMA Q8) ring and piniongearsets to less than 10 min.Ra, the life of the lubricant,bearings and gears is significantly increased. Just a few yearsago, this technology was considered impractical for high productionvolume OEM ring and pinion gearsets due to lengthy processingtimes. This superfinishing technology also had difficultiespreserving the geometry of rough lapped gears, which required morestock removal than finely ground aerospace gears (AGMA Q12+). As aresult the transmission error of these gears was increased leadingto unacceptable noise. The superfinishing technology discussed inthis paper overcomes these obstacles and meets the needs of themotor vehicle industry. Gear metrology, contact patterns,transmission error and actual performance data for superfinishedgearsets will be presented along with the superfinishingprocess.
- Edition:
- 04
- Published:
- 10/01/2004
- Number of Pages:
- 16
- File Size:
- 1 file , 4.1 MB
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