HEIDENHAIN TNC 640 (34059x-02) Cycle programming - Manual (Page 373)

THREAD LONGITUDINAL
(Cycle 831, DIN/ISO: G831)
13.28
13
TNC 640 | User's Manual Cycle Programming | 5/2013
373
Please note while programming:
Program a positioning block to the starting position
with radius compensation
R0 before the cycle call.
The TNC uses the set-up clearance
Q460 as
approach path. The approach path must be long
enough for the feed axes to be accelerated to the
required velocity.
The TNC uses the thread pitch as overrun path. The
overrun path must be long enough to decelerate the
feed axes.
Parameters are available for approach and overrun in
Cycle 832 THREAD EXTENDED.
When the TNC runs a thread cut, the feed-rate
override knob is disabled. The spindle speed override
knob is active only within a limited range, which is
defined by the machine tool builder (refer to your
machine manual).
With some machine types the turning tool is not
clamped in the milling spindle but in a separate
holder adjacent to the spindle. The turning tool
cannot be rotated through 180° in such cases to
machine internal and external threads with only one
tool for example. If with such a machine you wish
to use an external tool for inside machining, you can
execute machining in the negative diameter range
(-X) and reverse the direction of workpiece rotation.
Note that with pre-positioning in the negative
diameter range, the TNC reverses the effect of the
parameter G471 Thread position (external thread is
then 1 and internal thread 0).
The retraction motion is directly to the starting
position. Always position the tool so that the TNC
can approach the starting point at the end of the
cycle without collisions.