The international calculation method for micropitting, ISO/TR15144, was recently published. It is the first officialinternational calculation method to check for the risk ofmicropitting ever published. Years ago AGMA published a method forthe calculation of the specific oil film thickness containing somecomments about micropitting, and the German FVA published acalculation method based on intensive research results. The FVA andthe AGMA are close to the ISO/TR. New is the calculation of themicropitting safety factors. The technical report presents twocalculation rules, method A and B. Method A needs as input theHertzian pressure on every point of the tooth flank, based on anaccurate calculation of the meshing of the gear pair, consideringtooth and shaft deflections to get the load distribution over theflank line in every meshing position. Method B is much simpler; theload distribution is defined for different cases as spur or helicalgears, with and without profile modifications. The risk ofmicropitting is highly influenced by profile and flank linemodifications. A new software tool can evaluate the risk ofmicropitting for gears by automatically varying differentcombinations of tip reliefs, other profile modifications and flankline modifications, in combination with different torque levels,using method A. The user can define the number of steps forvariation of the amount of modification. Then all possiblecombinations are checked combined with different (user defined)torque levels. Any modifications including flank twist, arc-likeprofile modifications, etc. can be combined. The result ispresented in a table, showing the safety factor againstmicropitting for different subsets of profile/flank modifications,depending on the torque level. Some applications from wind turbineand industrial gearboxes, known to the author, will bediscussed.
- Edition:
- 11
- Published:
- 10/01/2011
- Number of Pages:
- 15
- File Size:
- 1 file , 640 KB
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