Re: Problem with cutting Bevel Gear

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Posted by Allan Guest on March 23, 2002 at 08:15:47:

In Reply to: Re: Problem with cutting Bevel Gear posted by Allan Guest on March 22, 2002 at 12:26:47:

Gleason Road Service Bulletin No. 63
Procedure to determine cause of flats on pinion teeth on No. 16 Hypoid Generator

1/ Cut a pinion on slowest feed using highest speed
2/ Run pinion in testing m/c.If pinion runs OK the trouble will be in the cutter.Check the cutter for high blades or blades off angle.
3/ If does not run OK and shows flats it will be necessary to determine if the flats are regular or irregular.
4/ Irregular flats generally come from a cutter spindle which does not repeat.(check spindle for repeat)
If the cradle setting is such that the cradle is in balance it may cause irregular flats.
Bruise on cradle drive will cause irregular flats.
Bruises on index drive will cause irregular flats which will be in the same position on all teeth.
5/ Regular flats generaly come from machine parts such as,gear trains e.g. speed & feed.
6/ To prove whatb part of m/c train is causing the flats proceed as follows:- Cut a pion at slowest feed ,fastest speed.Leave the pinion in m/c Make a head setting change of .001-.002" in on cone.Blue vitrol all the teeth on pinion.take a cut off the tops of the hills leaving identifying marks which can be counted from toe to heel.
To determine shaft or gear is at fault jog the cutter to small end of soon as the cutter starts to cut the tooth on the flank of the toe ,place a mark on the cradle roll graduation and note setting.Cut through to the heel of the tooth.As soon as thecutter stops cutting,place a mark on the cradle roll graduation and note setting.This will be the effective cutter roll.Count the number of flats on the tooth.Check which shaft or gear makes the same number of revolutions during effective part of roll as there are flats.

Regular flats:-
If the flats check with number of turns of any part of the m/c check the following.

1/ run out of shafts
2/ run out of gears
3/ shafts loose on bearings
4/ bruises on gear
5/ tight or loose spots in a revolution of a shaft or gear.

If above items O.K. check index or cradle drive for variation in backlash in each 1/8 of a revololution.
Best of luck

Allan Guest (UK)

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