Siemens SINUMERIK 840D Programming Manual page 125

3
12.97
08.97
Inside threads
Position reached prior to cycle start:
This can be any position from which the starting
position on the center point of the thread at the
retraction plane level can be approached without
collision.
The cycle implements the following motion
sequence:
• Travel to the center point of the thread with G0 at the
retraction plane level in the applicate of the current
plane
• Infeed to the reference plane brought forward by
the safety distance with G0
• Approach with G1 and the reduced feedrate FFR
along an approach circle calculated in the cycle
• Movement to the thread diameter along a circular
path in the direction G2/G3 defined in CDIR
• Thread milling along a helical path with G2/G3
and feedrate FFR
• Travel-out movement along a circular path with the
same direction of rotation and the reduced feedrate
FFR
• Retraction to the center point of the thread with G0
• Retraction to retraction plane in the applicate with
G0.
Thread from bottom to top
For technological reasons, it may be preferable to
machine the thread from the bottom to the top. The
retraction plane RTP is then below the thread depth
DP.
This machining operation is possible, the depth data
must be programmed as absolute values and before
cycle start, the machine must be positioned on the
retraction plane or one position behind the retraction
plane.
© Siemens AG, 2002. All rights reserved
SINUMERIK 840D/840Di/810D Programming Guide Cycles (PGZ) – 11.02 Edition
3.3 Thread cutting – CYCLE90
3
Milling Cycles
3-125