HEIDENHAIN TNC 128 (77184x-02) - Manual (Page 407)

BACK BORING (Cycle 204) 16.7
16
TNC 128 | User's Manual HEIDENHAIN Conversational Programming | 5/2014
407
16.7 BACK BORING (Cycle 204)
Cycle run
This cycle allows holes to be bored from the underside of the
workpiece.
1 The TNC positions the tool in the tool axis at rapid traverse
FMAX to set-up clearance above the workpiece surface.
2 The TNC then orients the spindle to the 0° position with an
oriented spindle stop and displaces the tool by the off-center
distance.
3 The tool is then plunged into the already bored hole at the
feed rate for pre-positioning until the tooth has reached set-up
clearance on the underside of the workpiece.
4 The TNC then centers the tool again over the bore hole,
switches on the spindle and the coolant and moves at the feed
rate for boring to the depth of bore.
5 If a dwell time is entered, the tool will pause at the top of the
bore hole and will then be retracted from the hole again. The
TNC carries out another oriented spindle stop and the tool is
once again displaced by the off-center distance.
6 The tool then retracts to set-up clearance at the feed rate for
pre-positioning, and from there—if programmed—to the 2nd
set-up clearance at
FMAX.
Please note while programming:
Machine and TNC must be specially prepared by the
machine tool builder for use of this cycle.
This cycle is effective only for machines with servo-
controlled spindle.
Special boring bars for upward cutting are required
for this cycle.
Program a positioning block for the starting point
(hole center) in the working plane with radius
compensation
R0.
The algebraic sign for the cycle parameter depth
determines the working direction. Note: A positive
sign bores in the direction of the positive spindle
axis.
The entered tool length is the total length to the
underside of the boring bar and not just to the tooth.
When calculating the starting point for boring, the
TNC considers the tooth length of the boring bar and
the thickness of the material.