Page 214 - Gear Technology Solutions

interference of the spline teeth. It is recommended to use the face relief “a”
when turning the blanks to avoid root interference.

Figure 2: Spherical Spline

The radius of the spline face can be calculated, such that the radius R1 at the
ends of the spline blank creates a crowning gap of “a” seen in Figure 2. In or-
der to achieve the same crowning gap “a” at the ends of the spline teeth a cer-
tain crowning advance in depth direction of the spline teeth is required. This
crowning advance is different to “a”, because while the cutting tool cuts deep-
er, the flanks are only receiving a smaller amount of relief, depending on the
pressure angle. In the following equations, the crowning advance and the
equivalent crowning radii are calculated.

Relief required: a = tane• L/2

Required face radius: R1 =[(L/2)² – a²] /(2a)

Required crowning advance: b = a/tana

Crowning radius
orthogonal to root: R2 =[(L/2)² – b²] /(2b)

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

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