HEIDENHAIN TNC 426 (280 476) - Manual (Page 276)

HEIDENHAIN TNC 426, TNC 430 249
8.3 Cy
cles f
o
r Dr
illing, T
a
pping and Thr
ead Milling
OUTSIDE THREAD MILLING (Cycle 267)
1 The TNC positions the tool in the tool axis at rapid traverse FMAX
to the programmed setup clearance above the workpiece surface.
Countersinking at front
2 The TNC moves on the reference axis of the working plane from
the center of the stud to the starting point for countersinking at
front. The position of the starting point is determined by the thread
radius, tool radius and pitch.
3 The tool moves at the feed rate for pre-positioning to the sinking
depth at front.
4 The TNC positions the tool without compensation from the center
on a semicircle to the offset at front, and then follows a circular
path at the feed rate for countersinking.
5 The tool then moves in a semicircle to the starting point.
Thread milling
6 The TNC positions the tool to the starting point if there has been
no previous countersinking at front. Starting point for thread milling
= starting point for countersinking at front.
7 The tool moves at the programmed feed rate for pre-positioning to
the starting plane. The starting plane is derived from the algebraic
sign of the thread pitch, the milling method (climb or up-cut milling)
and the number of threads per step.
8 The tool then approaches the thread diameter tangentially in a
helical movement.
9 Depending on the setting of the parameter for the number of
threads, the tool mills the thread in one, in several spaced or in one
continuous helical movement.
10 After this, the tool departs the contour tangentially and returns to
the starting point in the working plane.