Page 217 - Gear Technology Solutions

the face width. This is not true, because in reality there will always be some
misalignment. Besides this, the manufacturing process with a hob or grinding
wheel will round the center transition from one side of the “roof” to the other
side, such that also without misalignment a contact zone of 50% of the face
width is realistic.

Figure 4: Roof Top Spline

The relief amounts are “a” and the crowning advance for a hobbing or grinding
machine “b” are calculated as:

Relief required: a = tane• L/2
Required crowning advance: b = a/tana

Whereas:
a… face relief
b… root relief = crowning in hobbing or grinding
L… active length of spline
e… expected misalignment angle
a… spline pressure angle

It is recommended to use the face relief when turning the blanks to avoid root
interference. It is not required to eliminate the roof tip by attempting to round it.
The hobbing or grinding process will automatically round the roof tip corner.

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