Linear Progressive/Degressive Thread-Lead Change With G34 And G35 - Siemens SINUMERIK 828D Function Manual

V1: Feedrates
17.2 Path feedrate F
Constraints
When a block containing command DITS and/ or DITE is loaded in the interpolator, the path programmed in
DITS is transferred to setting data:
SD42010 $SC_THREAD_RAMP_DISP[0]
and the path programmed in DITE is transferred to setting data:
SD42010 $SC_THREAD_RAMP_DISP[1]
.
The programmed run-in path is handled according to the current setting (inches, metric).
If no run-in/deceleration path is programmed before or in the first thread block, the value is determined by the
current value in setting data:
SD42010 $SC_THREAD_RAMP_DISP[0,1 ]
.
In the event of RESET, the setting data:
SD42010 $SC_THREAD_RAMP_DISP[0,1]
is set to "-1".
17.2.4.3

Linear progressive/degressive thread-lead change with G34 and G35

Application G34, G35
The functions can be used to produce self­shearing threads.
Functionality
The thread lead increase (G34) defines the numerical increase in the lead value. A larger pitch results in a larger
distance between the threads on the workpieces. The velocity of the thread axis thus increases assuming that
the spindle speed is constant.
The opposite naturally applies to decreasing thread lead (G35).
The following definitions have been made for the thread-lead changes with respect to the new G codes:
• G34: Increase in thread lead corresponds to progressive change.
• G35: Decrease in thread lead corresponds to degressive change.
Both functions G34 and G35 imply the functionality of G33 and additionally provide the option of programming an
absolute lead change value for the thread under F. If the start and end lead of a thread is known, the thread-lead
change can be determined using the following equation:
The identifiers have the following meanings:
F: The thread-lead change to be programmed [mm/rev
k : Thread lead of axis target point coordinate, thread axis [mm/rev]
e
k : Initial thread lead (programmed under I, J or K) [mm/rev]
a
l : Thread length [mm]
G
1378
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Basic Functions