AGMA 10FTM10

The connection between transmission error and noise andvibration during operation has long been established. Calculationmethods have developed to describe the influence such that it ispossible to evaluate the relative effect of applying a specificmodification at the design stage. The calculations can allow thedesigner to minimize the excitation from the gear pair engagementat a specific load. This paper explains the theory behindtransmission error and the reasoning behind themethod of applyingthemodifications through mapping the surface profiles and deducingthe load sharing. It can be used to explain the results of laterexperimental validation on various types of tip relief in lowcontact ratio (LCR) gears, from very long to very short. The paperwill also demonstrate that though the effects of modification inany specific case can be modeled with some certainty, the samemodifying strategy can not be applied universally but must considerthe required operating conditions. It illustrates that the effectof tip relief on transmission error and load sharing is not a blackart but can be fully explained by applying existing theory.

A study of high contact ratio (HCR) gears will be presented todemonstrate why it is often necessary to apply different amountsand extents of tip relief in such designs, andhowthesemodificationsaffect load sharing and highest point of tooth loading. Specificattention will be paid to the phenomenon of extended contact, whereif no modification or insufficient tip relief is applied, contactdoes not stop at the end of active profile but continues beyondthis point as the gear rotates resulting in contact on the tip.This effectively increases contact ratio and has implications forthe tooth load and in particular how this may affect the loadingposition, highest point of single tooth contact (HPSTC), which isrelevant to both ISO and AGMA standard rating. The paper willconsider 3 methods commonly employed in the industry; asimple2Dmapping procedure carried out on graph paper, a 3Dlineartooth stiffness computationmethod, and a 3Dfinite element analysis(FEA) calculation. The paper will demonstrate that though in somecases these methods can produce similar results, albeit withvarying degrees of accuracy, further examples will be presentedwhich demonstrate behavior which can only be detected using some ofthe more complex analysis methods. The commercial viability ofimplementing a better quality models against the time constraintsin the development process will be discussed and conclusionsdrawn.

Edition:

10

Published:

10/01/2010

Number of Pages:

15

File Size:

1 file , 1.1 MB