Linear Increasing/Decreasing Thread Pitch Change With G34 And G35 - Siemens SINUMERIK 840D Function Manual

V1: Feedrates
5.2 Path feedrate F
NC stop, single block
NC stop and single block (even at the block boundary) are only active after completion of thread
chaining. All successive G33 blocks and the first following non-G33 block are traversed as a
block.
Premature abortion without destruction
Thread cutting can be aborted without destruction before the end point is reached. This can be
done by activating a retraction motion.
Thread cutting with ROT frame
With ROT frame and G33, G34, G35, alarm 10607 "Thread with frame not executable" is
activated if the rotation causes a change in the thread length and thus the pitch. Rotation
around the thread axis is permissible.
Alarm 10607 "Thread with frame not executable" can be suppressed by setting bit 12 in
machine data MD11410 $MN_SUPPRESS_ALARM_MASK, if the ROT instruction is used
intentionally in the application.
All other frames are accepted by the NC without alarm. Attention is drawn to the pitch-changing
effect of SCALE.
5.2.3.2

Linear increasing/decreasing thread pitch change with G34 and G35

Function
The thread pitch increase (G34) defines the numerical increase in the pitch value. A larger pitch
results in a larger distance between the threads on the workpieces. The velocity of the thread
axis therefore increases with assumed constant spindle speed.
The opposite therefore applies for the decrease in thread pitch (G35).
The following definitions are made for the thread pitch change:
● G34: Increase in thread pitch corresponds to progressive change
● G35: Decrease in thread pitch corresponds to degressive change
Both G34 and G35 functions imply the functionality of G33 and also provide the option of
programming an absolute pitch change value for the thread under F. If the start and end pitch
of a thread is known, the thread pitch change can be determined using the following equation:
136
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA