BCobra (Mechanical) (OP)
1 Dec 11 12:46
I am fairly new to gear design so forgive me if my questions are overly simple, chances are I'm making this more complicated than it has to be.
The short story is that I am tasked with calculating new spur gear data and inspection data based on reducing the AGMA Quality Class of a set of gears from 12 to 11. I am specifically being asked to obtian new Maximum Total Composite Error (TTE) and Maximum Tooth-to-Tooth Error (TTE), Testing Radii, Dimension Across Pins (Or Measurement Over Wire, for now I'll call it MOW), and Circular Tooth Thickness.
I began by obtaining a copy of AGMA 2000-A88 and determining the new TCE and TTE using the appropriate equations for the gear in question (there are several individual gears I have to perform this on but I am only focusing on one for now).
I was told that from this data I could calculate the change in backlash that would result in increasing the TCE by assuming that 1/2 the change in TCE (delta TCE between Quality 12 and 11) is approximately equal to an equivalent change in centerline distance between gears (if I am understanding this correctly thus far). Multiplying this by 2tan(pressure angle) gives a change in backlash.
From here I am stuck on several points:
1. How do I use the change in backlash to calculate new circular tooth thicknesses?
2. Referencing Machinery's Handbook, I can't seem to figure out how to calculate new MOW for reduced tooth thickness. You use diametral pitch (Dp) and the appropriate table values to calculate the MOW but since Dp remains constant I don't see how MOW would change; any input would be greatly appreciated.
3. How does one go about calculating Test Radii? I understand what they are but referencing AGMA 2000-A88, Norton Machinery Design, Dudley Gear Design, and the Machinery Handbook, there is no mention of how to actually calculate these values.
Please let me konw if I am approaching this in the wrong way or if you need more information, thank you. Again, any input would be greatly appreciated.