HEIDENHAIN TNC 430 - Circular path CTP with tangential connection; Helical interpolation

HEIDENHAIN TNC 426, TNC 430 153
6.5 Path Contours — Polar Coordinates
Circular path CTP with tangential connection
The tool moves on a circular path, starting tangentially from a
preceding contour element.
U Polar coordinates radius PR: Distance from the arc
end point to the pole CC
U Polar coordinates angle PA: Angular position of the
arc end point
Example NC blocks
Helical interpolation
A helix is a combination of a circular movement in a main plane and a
liner movement perpendicular to this plane.
A helix is programmed only in polar coordinates.
Application
n Large-diameter internal and external threads
n 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 a upward direction, you need
the following data:
12 CC X+40 Y+35
13 L X+0 Y+35 RL F250 M3
14 LP PR+25 PA+120
15 CTP PR+30 PA+30
16 L Y+0
The pole CC is not the center of the contour arc!
X
Y
40
35
CC
30°
120°
R30
R25
Thread revolutions n Thread revolutions + thread overrun at
the start and end of the thread
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)
Y
X
Z
CC