Thread Cutting - Siemens SINUMERIK 840D sl Operation/Programming Manual

08/2005
5

5.3.5 Thread cutting

Approach/retraction
♥ Siemens AG, 2005. All rights reserved
SINUMERIK 840D sl Operation/Programming ShopTurn (BAT) – 08/2005 Edition
The "Longitudinal thread", "Conical thread" and "Face thread"
functions are used when you want to cut external or internal threads
with constant or variable pitch.
The thread can be single or multiple.
You define a right or left-hand thread by the direction of spindle
rotation and the feed direction.
The infeed is performed automatically with constant infeed depth or
constant cutting cross-section.

With constant infeed depth, the cutting cross-section increases
from cut to cut. The final machining allowance is machined in one
cut after roughing.
A constant infeed depth can produce better cutting conditions at
small thread depths.

With constant cutting cross-section, the cutting pressure remains
constant over all roughing cuts and the infeed depth is reduced.
For metric threads (thread pitch P in mm/rev) ShopTurn assigns a
value calculated from the thread pitch to the Thread depth K
parameter. You can change this value.
The default selection must be activated via a machine data code.
Please also refer to the machine manufacturer's instructions.
The cycle requires a speed-controlled spindle with a position
measuring system.
1. The tool moves to the return plane at rapid traverse.
2. Thread with advance:
The tool moves at rapid traverse to the first starting position
displaced by the thread advance W.
Thread with run-in:
The tool moves at rapid traverse to the first starting position
displaced by the thread run-in W2.
3. The first cut is made with thread pitch P as far as the thread run-
out R.
4. Thread with advance:
The tool moves at rapid traverse to the return distance V and then
to the next starting position.
Thread with run-in:
The tool moves at rapid traverse to the return distance V and then
back to the starting position.
5. Steps 3 and 4 are repeated until the thread is finished.
ShopTurn Functions
5
5.3 Turning
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