Siemens SINUMERIK 840D sl Programming Manual page 320

Transformations
6.2 Three, four and five axis transformation (TRAORI)
The tool shape and dimensions are taken into account in the calculations, which are
normally performed in CAM. The fully calculated NC blocks are then read into the controller
via postprocessors.
Programming the path curvature
Surface description
The path curvature is described by surface normal vectors with the following components:
A4, B4, C4
A5, B5, C5
If a block only contains the start vector, the surface normal vector will remain constant
throughout the block. If a block only contains the end vector, interpolation will run from the
end value of the previous block via large-circle interpolation to the programmed end value.
If both start and end vectors are programmed, interpolation runs between the two directions,
also via large-circle interpolation. This allows continuously smooth paths to be created.
Regardless of the active G17 to G19 level, in the initial setting, surface normal vectors point
in the Z direction.
The length of a vector is meaningless.
Vector components that have not been programmed are set to zero.
When ORIWKS is active (see "Reference of the orientation axes (ORIWKS, ORIMKS):
(Page 321)"), the surface normal vectors refer to the active frame and are also rotated with
frame rotation.
Machine manufacturer
The surface normal vector must be perpendicular to the path tangent, within a limit value set
via machine data, otherwise an alarm will be output.
320
Start vector at block start
End vector at block end
Programming Manual, 03/2013, 6FC5398-2BP40-3BA1
Job Planning