HEIDENHAIN iTNC 530 HSCI - LIFTOFF Function

1098 HEIDENHAIN Technical Manual iTNC 530 HSCI
7.7.4 LIFTOFF function
General
information
During an NC stop, a lift-off movement in the direction of the tool axis is
superimposed over the deceleration along the path. This movement for
protecting the workpiece is referred to as LIFTOFF.
LIFTOFF is possible in case of:
 NC stop if this is configured in M4620. Distance by which the tool is lifted
off: 0.1 mm.
 Power failure and other error reactions by the CC intended for this purpose
if the constraints described below are maintained. The distance by which
the tool is lifted off can be configured in MP1160.
 PLC error message, for which the reaction NC-LIFTOFF is contained in the
PET table. Distance by which the tool is lifted off: 0.1 mm.
The following conditions must be met for a LIFTOFF to be performed:
 LIFTOFF is enabled by NC program via M148 = active
 Tool is enabled in the tool table via column LIFTOFF = Y
 LIFTOFF is enabled by PLC via M4620 = 1
The velocity at which the tool is lifted off depends on the retraction path. The
necessary movement is always performed in a time of 0.1 seconds.
LIFTOFF in case of
power failure
If the power fails and LIFTOFF is enabled (M148 must be active, column
LIFTOFF in the tool table = Y, PLC: M4620=1), an attempt is made to lift the
tool from the contour by the distance given in MP1160 with the help of the
remaining energy of the DC-link.
Certain conditions must be maintained before and during LIFTOFF:
 The 24 V power supply must be maintained for at least 1 second (UPS for
24 V, or buffer capacity or capacitor). HEIDENHAIN offers the PSL 13x or
CML 110 (Capacitor Module for Low Voltage) for this.
 The current and speed controllers may not be switched off (e.g. via PLC
Module 9161)
 AC-fail monitoring (MP2195 Bit 7 = 0) and/or Uz monitoring are/is active
(MP2195 Bit 9 = 0). Both monitoring functions lead to LIFTOFF if they are
activated and respond. HEIDENHAIN recommends activating both
monitoring functions to provide the quickest reaction possible in case of a
power failure or a failure of the power supply module.
 The wye-delta contactor combination may not fail, otherwise the spindle
would not be controllable during LIFTOFF.
Note
 If there is an emergency stop, no LIFTOFF is performed. The servo drives
will then be decelerated along the emergency braking ramp as quickly as
possible.