12.4 Fundamentals Of Turning Cycles - HEIDENHAIN TNC 640 User Manual

12

12.4 Fundamentals of Turning Cycles

The pre-positioning of the tool decisively affects the workspace
of the cycle and thus the machining time. During roughing, the
starting point for cycles corresponds to the tool position when a
cycle is called. When calculating the area to be machined, the TNC
takes into account the starting point and the end point defined in
the cycle or contour defined in the cycle. If the starting point lies in
the area to be machined the TNC positions the tool beforehand in
some cycles to set-up clearance.
The turning direction with 81x cycles is longitudinal to the rotary
axis and lateral to the rotary axis with 82x cycles. The motions are
contour-parallel in cycle 815.
The cycles can be used for inside and outside machining. The
TNC takes the information for this from the position of the tool
or the definition in the cycle (See "Working with turning cycles",
page 363).
In cycles with freely defined contours (Cycles 810, 820 and 815),
the programming direction of the contour determines the direction
of machining.
In cycles for turning you can specify the machining strategies of
roughing, finishing or complete machining.
Danger of collision!
The turning cycles position the tool automatically to the starting
point during finishing. The approach strategy is influenced by the
position of the tool when the cycle is called. The decisive factor
is whether the tool is located inside or outside an envelope
contour when the cycle is called. The envelope contour is the
programmed contour, enlarged by the set-up clearance. If the
tool is within the envelope contour, the cycle positions the tool
at the defined feed rate directly to the starting position. This can
cause contour damage.
Position the tool at a sufficient distance from the starting
point to prevent the possibility of contour damage
If the tool is outside the envelope contour, positioning to the
envelope contour is performed at rapid traverse, and at the
programmed feed rate within the envelope contour.
374
NOTICE
Cycles: Turning | Fundamentals of Turning Cycles
HEIDENHAIN | User's manual for cycle programming | 10/2017