250 Programming: Programming Contours
6.5 Path contours—Polar coordinates
Helical interpolation
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.
For calculating a helix that is to be cut in an upward direction, you need
the following data:
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.
Thread revolutions n Thread revolutions + thread overrun at
thread beginning and end
Total height h Thread pitch P times thread revolutions n
Incremental total
angle IPA
Number of revolutions times 360° + angle for
beginning of thread + angle for thread
overrun
Starting coordinate Z Pitch P times (thread revolutions + thread
overrun at start of thread)
Internal thread
Work direc-
tion
Direction of
rotation
Radius com-
pensation
Right-handed
Left-handed
Z+
Z+
DR+
DR–
RL
RR
Right-handed
Left-handed
Z–
Z–
DR–
DR+
RR
RL
External thread
Right-handed
Left-handed
Z+
Z+
DR+
DR–
RR
RL
Right-handed
Left-handed
Z–
Z–
DR–
DR+
RL
RR
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