Siemens SINUMERIK 840D sl Function Manual page 1321

When the thread length l
the end of block k
● For G34 (increasing pitch):
● For G35 (decreasing pitch):
Note
If the formula results in a negative root expression, the thread cannot be machined!
In this case, the NC signals alarm 10605 or alarm 22275.
Application
The G34 and G35 functions can be used to produce self-shearing threads.
Example
Thread cutting G33 with decreasing thread pitch G35
Program code
N1608 M3 S10
N1609 G0 G64 Z40 X216
N1610 G33 Z0 K100 SF=R14
N1611 G35 Z-220 K100 F17.045455
N1612 G33 Z-240 K50
N1613 G0 X218
N1614 G0 Z40
N1616 M17
Monitoring during the block preparation
Any pitch changes that would overload the thread axis when G34 is active or would result in
an axis standstill when G35 is active, are detected in advance during block preparation. Alarm
10604 "Thread pitch increase too high" or 10605 "Thread pitch decrease too high" is signaled.
During thread cutting, certain practical applications require a correction of the spindle speed.
In this case, the operator will base his correction on the permissible velocity of the thread axis.
To do this, it is possible to suppress the output of alarms 10604 and 10605 as follows:
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
, pitch change F and initial pitch k
G
can be determined as follows by modifying the formula:
e
are known, the pitch increase at
a
Comment
; Spindle speed
; Approach starting point
; Thread with constant pitch 100 mm/rev
; Thread pitch decrease 17.045455 mm/rev2
; Thread pitch at end of block 50 mm/rev
; Traverse thread block without jerk
V1: Feedrates
17.2 Path feedrate F
1321