9.SPINDLE SPEED FUNCTION (S FUNCTION) PROGRAMMING B-63324EN/03
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- Position coder-less feed per revolution and constant surface speed control
These functions are enabled when bit 6 (FPR) of parameter No. 2405 is
set to 1.
On a machine on which no position coder is installed, feed per
revolution is enabled assuming the specified spindle speed signals
RO0s to RO15s to be the spindle speed, even if constant surface speed
control is applied
Example) A diameter is specified for the X-axis
N1 G90 X50. Z10.
N2 G96 G95 S12 : Starts constant surface speed control and
feed per revolution
N3 G01 X20. Z30. F10.
N5 G97 S200 : Cancels constant surface speed control.
N6 G90 G00 Z200.
Fig.9.2 (c) Position Coder-less Feed per Revolution
N2 of the above program specifies the constant surface speed control
command (G96), a surface speed of 12 m/min, and a feed per revolution
(G96). During positioning up to X = 20.0 in N3, the CNC changes the
command spindle speed from 76.4 min
to 191.0 min
On the other hand, the feedrate for feed per revolution conforms to the
varying command spindle speed signals to produce movement along a
feed axis. In this example, the actual speed in N3 is 764 to 1910
However, the command spindle speed is clamped with maximum
spindle speed signals MR0s to MR15s.