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7.5 Miscellaneous Functions for Rotary
Axes
Feed rate in mm/min
on rotary axes A, B, C: M116
Standard behavior
The TNC interprets the programmed feed rate in a rotary axis in
degrees per minute. The contouring feed rate therefore depends
on the distance from the tool center to the center of the rotary axis.
The larger this distance becomes, the greater the contouring feed
rate.
Feed rate in mm/min on rotary axes with M116
The machine geometry must be entered in machine
parameters 7510 ff. by the machine tool builder.
The TNC interprets the programmed feed rate in a rotary axis in
mm/min. With this miscellaneous function, the TNC calculates the
feed rate for each block at the start of the individual block. The feed
rate is not changed during execution of the block even if the tool
moves toward the center of the rotary axis.
Effect
M116 is effective in the working plane.
You can cancel M116 with M117; at the end of the program M116 is
also reset.
M116 becomes effective at the start of block.
Shorter-path traverse of rotary axes: M126
Standard behavior
The standard behavior of the TNC while positioning rotary axes
whose display has been reduced to values less than 360° is
dependent on machine parameter 7682. In machine parameter
7682 is set whether the TNC should consider the difference
between nominal and actual position, or whether the TNC should
always (even without M126) choose the shortest path traverse to
the programmed position. The table at upper right shows
examples.
Behavior with M126
With M126, the TNC will move the axis on the shorter path of
traverse if you reduce display of a rotary axis to a value less than
360°. The table at lower right shows examples.
Effect
M126 becomes effective at the start of block. To cancel M126,
enter M127 . At the end of program, M126 is automatically canceled.
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Standard behavior of the TNC
Actual position
Nominal position Traverse
350°
10°
10°
340°
Behavior with M126
Actual position
Nominal position Traverse
350°
10°
10°
340°
7 Programming: Miscellaneous functions
–340°
+330°
+20°
–30°
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