Siemens SINUMERIK 840Di Function Manual page 1621

Constraints
When a block is loaded into the interpolator with the DITS and/or DITE command, the path
programmed under DITS is written to setting data:
SD42010 THREAD_RAMP_DISP[0]
and the path programmed under DITE is written to setting data:
SD42010 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, it is
determined by the current content of setting data:
SD42010 THREAD_RAMP_DISP[0,1].
A RESET sets setting data:
SD42010 THREAD_RAMP_DISP[0,1]
to the value "-1".
2.1.4.3 Linear progressive/degressive thread-lead change with G34 and G35
Application G34, G35
The functions can be used to produce self-shearing 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.
Feeds (V1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Detailed Description
2.1 Path feedrate F
2-13