Orientation Movements With Axis Limits - Siemens SINUMERIK 840D sl Function Manual

If the tool is de-selected, thereby canceling the definition of tool orientation, the basic
orientation programmed in machine data becomes operative.
Definition using a machine data
If the basic orientation is not defined by either of the two variants described above, it is specified
with reference to the following machine data:
$MC_TRAFO5_BASE_ORIENT_n (basic tool orientation)
This machine data must not be set to a zero vector or else an alarm will be generated during
control run-up when a transformation is active.
If a basic orientation is programmed in machine data $MC_TRAFO5_BASE_ORIENT_n when
a transformation is active and a tool is subsequently activated, the basic orientation is re-
defined by the tool.
Note
The range of settable orientations depends on the directions of the rotary axes involved and
the basic orientation. The rotary axes must be mutually perpendicular if all possible orientations
are to be used. If this condition is not met, "dead" ranges will occur.
Examples:
1. Extreme example: A machine with rotatable tool has a C axis as its first rotary axis and an
A axis as its second. If the basic orientation is defined in parallel to the A axis, the orientation
can only be changed in the X-Y plane (when the C axis is rotating), i.e. orientation with a
Z component unequal to zero is not possible in this instance. The orientation does not
change when the A axis rotates.
2. Realistic example: A machine with nutator kinematics (cardan head) with an axis inclined
at less than 45
within a semi-circle: The top semi-circle with basic orientation towards +Z and the bottom
with basic orientation towards -Z.
2.9.2

Orientation movements with axis limits

Calculate rotary axis position
If the final orientation in a 5-axis transformation is programmed indirectly in an NC block by
means of a Euler, RPY angle or direction vector, it is necessary to calculate the rotary axis
positions that produce the desired orientation. This calculation has no unique result.
There are always at least two essentially different solutions. In addition, any number of
solutions can result from a modification to the rotary axis positions by any multiple of 360
degrees.
The control system chooses the solution which represents the shortest distance from the
current starting point, allowing for the programmed interpolation type.
Special functions
Function Manual, 01/2015, 6FC5397-2BP40-5BA2
in a basic orientation parallel to the Z axis can only assume orientations
o
F2: Multi-axis transformations
2.9 Orientation
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