Posted by BillS on October 04, 2009 at 23:07:39:
In Reply to: Re: Timming relationship for tangential hobbing posted by Andy on October 04, 2009 at 11:10:07:
I don't think the differential can be used without feed motion of the cutter table, and cutting a throated worm gear won't allow feed motion of cutter table. I'm assuming there is no tangential feed option on the machine (since you are trying to create tangential feed through hob shifting).
Machines with tangential feed gear their tangential feed through the differential to synchronize the 3 motions (table feed, tangential feed, and index table rotation). Machines with tangential feed also advance table motion to sync with the axially moving cutter, but on older machines this was done witrh gearing.
When cutting helical gears using the differential, there is an offset amount used when calculating the differential ratio to account for tangential feed.
I don't see any reason that you can't do what you want to do with your PLC sync'ing cutter motion to table encoder, but if you are fly cutting a worm gear, then I don't think the differential is going to be of any use. Wouldn't it need to be locked out?