Siemens SINUMERIK 840D sl Function Manual page 1738

Detailed description
2.1 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".
2.1.4.3 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.
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Basic logic functions: Feeds (V1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0