Siemens sinumerik 840D sl Function Manual page 384

Examples
4.3 Electronic gear for gear hobbing
In this case, the workpiece table axis (C) is the following axis which is influenced by three
master drives.
The setpoint of the following axis is calculated cyclically with the following logic equation:
n = n
c
n : Rotational speed of workpiece axis (C)
c
n : Rotational speed of milling spindle (B)
b
z : Gear number of hobbing machine
0
z : Number of teeth of the workpiece
2
v : Feed velocity of axial axis (Z)
z
v : Feed velocity of tangential axis (Y)
y
u : Axial differential constant
dz
u : Tangential differential constant
dy
Quantities which influence the setpoint of workpiece axis C
The first addend of the above equation determines the speed ratio between workpiece table
and cutter, and thus the number of teeth of the workpiece.
The second addend effects the necessary additional rotation of the C axis as a function of
the axial feed motion of the cutter to produce the tooth inclination on helical teeth.
The third component also makes allowance for additional rotation of the C axis to
compensate for the tangential movement of the cutter in relation to the workpiece, thus
ensuring that the tool is equally stressed over its entire length.
164
* (z / z ) + v * (u / z
b 0 2 z dz
) + v * (u / z )
2 y dy 2
Special functions: Axis Couplings and ESR (M3)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0