Machine With Rotary Work Table - Siemens SINUMERIK 840D sl Function Manual

W1: Tool offset
18.6 Toolholder with orientation capability
18.6.4

Machine with rotary work table

System variables
To date, the angles stored in $TC_CARR13 and $TC_CARR14 were used for the calculation
of the active tool length with TCOABS. This still applies if $TC_CARR21 and $TC_CARR22 do
not refer to rotary axes. If $TC_CARR21 or $TC_CARR22 contains a reference to a rotary axis
in the channel, the axis position of the relevant axis at the start of the current block is used as
the angle, rather than the entry in $TC_CARR13 or $TC_CARR14.
A mixed operating mode is permissible, i.e. the angles can be determined from the entry in
the system variables $TC_CARR13 or $TC_CARR14 for one axis, and from the position of a
channel axis for the other.
This makes it possible for machines, on which the axes used to set the toolholder with
orientation capability are known within the NC, to access their position directly, whereas it was
previously necessary, for example, to read system variable $AA_IM[axis] and write the result
of the read operation to $TC_CARR13/14. In particular, this removes the implicit preprocessing
stop when reading the axis positions.
MD20180
The rotary axis position is used with its programmed or calculated value, when the machine
data:
MD20180 $MC_TOCARR_ROT_ANGLE_INCR[i] = 0 (rotary axis increment of the tool carrier
that can be oriented)
If the machine data is not zero however, the position used is the nearest grid point obtained
for a suitable integer value n from the equation:
φ = $MC_TOCARR_ROT_ANGLE_OFFSET[i] + n * $MC_TOCARR_ROT_ANGLE_INCR[i]
This functionality is required if the rotary axes need to be indexed and cannot, therefore,
assume freely-defined positions (e.g. with Hirth tooth systems). System variable $P_TCANG[i]
delivers the approximated valued and system variable $P_TCDIFF[i] the difference between
the exact and the approximated value.
Frame orientation TCOFR
With TCOFR (determination of the angle from the orientation defined by an active frame), the
increments are scaled after determination of the angle from the active frame rotation. If the
requested orientation is not possible due to the machine kinematic, the machining is aborted
with an alarm. This also applies if the target orientation is very close to an achievable
orientation. In particular the alarm in such situations cannot be prevented through the angle
approximation.
TCARR frame offset
A frame offset as a result of a toolholder change becomes effective immediately on selection
of TCARR=.... A change in the tool length, on the other hand, only becomes effective
immediately if a tool is active.
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Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions