HEIDENHAIN TNC 640 (34059x-05) ISO programming - Manual (Page 235)

Path contours – Polar coordinates 6.5
6
TNC 640 | User's ManualDIN/ISO Programming | 1/2015
235
Helix
A helix is a combination of a circular movement in a main plane and
a linear movement perpendicular to this plane. You program the
circular path in a main plane.
A helix is programmed only in polar coordinates.
Application
Large-diameter internal and external threads
Lubrication grooves
Calculating the helix
To program a helix, you must enter the total angle through which
the tool is to move on the helix in incremental dimensions, and the
total height of the helix.
Thread revolutions n:
Thread revolutions + overrun at start and
end of thread
Total height h: Thread pitch P times thread revolutions
n
Incremental total angle
G91 H:
Thread revolutions x 360° + angle for
beginning of thread + angle for thread
overrun
Starting coordinate Z: Pitch P times (thread revolutions +
thread overrun at start of thread)
Shape of the helix
The table below illustrates in which way the shape of the helix is
determined by the work direction, direction of rotation and radius
compensation.
Internal thread Work direction Direction of rotation Radius compensation
Right-hand
Left-hand
Z+
Z+
G13
G12
G41
G42
Right-hand
Left-hand
Z–
Z–
G12
G13
G42
G41
External thread
Right-hand
Left-hand
Z+
Z+
G13
G12
G42
G41
Right-hand
Left-hand
Z–
Z–
G12
G13
G41
G42