Siemens SINUMERIK 840D sl Function Manual page 96

F2: Multi-axis transformations
2.9 Orientation
Deviation from the desired orientation
During the interpolation of the block, the orientation may deviate more or less from the desired
relative orientation. The orientation achieved in the previous block is transferred to the
programmed end orientation using large circular interpolation. The resulting deviation from the
desired relative orientation has two main causes:
1. The end orientation of the previous block refers to the tangent and the normal vector at the
end of the previous block. Both can differ from this at the start of the current block. Therefore,
the start orientation in the current block does not have the same alignment with respect to
the tangent and the normal vector as at the end of the previous block.
2. Not only the tangent, but also the normal vector can change throughout the entire block.
This is the case, when circles, splines or polynomials are programmed for the geometry
axes, or when not only a start, but also an end value is programmed for the normal vector.
In this case, the tool orientation must change accordingly during the interpolation of the
block, in order to have the same reference to the path tangent and to the surface normal
vector in each path point.
Set orientation relative to the path
The following machine data is used to set in which way the orientation relative to the path is
to be interpolated.
MD21094 $MC_ORIPATH_MODE (setting for path relative orientation ORIPATH)
With ORIPATH the behavior of tool orientation interpolation relative to the path can be activated
for various functions:
Meaning of units
0: The tool orientation only has the reference to the path tangent and to the normal vector
programmed with LEAD and TILT at the end of the block, whereas, during the block, the
orientation does not follow the path tangent (previous behavior).
1: Reference of the tool orientation to the path tangent and to the surface normal vector
programmed with LEAD/TILT is maintained throughout the entire block.
Meaning of decades
0: LEAD = rotation about the direction perpendicular to the tangent and normal vector (forward
angle)
TILT = rotation of orientation around the normal vector
1: LEAD = rotation about the direction perpendicular to the tangent and normal vector (forward
angle)
TILT = rotation of orientation around the direction of path tangent (sideways angle)
Meaning of centuries
0: There is no retracting movement
There is a retracting movement in the tool coordinate system, i.e. the direction programmed
by the retracting vector is interpreted in a coordinate system, which is specified in the following
way:
96
activate proper orientation relative to the path
Interpretation of the turning angle TILT
Retracting movement with re-orientation
Function Manual, 01/2015, 6FC5397-2BP40-5BA2
Special functions