Modifications During The Rotation Of Turning Tools - Siemens SINUMERIK 840D sl Function Manual
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W1: Tool offset
18.7 Cutting edge data modification for tools that can be rotated
18.7.4
Modifications during the rotation of turning tools
Tool orientation
Unlike milling tools, turning tools are not rotation-symmetric. This means that normally 3
degrees of freedom or three rotary axes are required to describe the tool orientation. The
concrete kinematics therefore, is independent of the machine only to the extent the desired
orientation can be set. If necessary, the third degree of freedom can be substituted by a rotation
of the tool coordinate system.
Note
The division of the orientation into one component created by the toolholder with orientation
capability and a second componnet achieved via a rotation of the coordinate system is the
responsibility of the application. The control does not provide any further functionality in this
regard.
Shape of cutting edge
If a turning tool turns by an angle against the machining plane (i.e. around an axis in the
machining plane, typically a C axis) that is not a multiple of 180°, then the configuration of the
(circular) tool cutting edge in the machining plane becomes an ellipse. It is assumed that the
deviations from the circular form arising on account of such rotations is so insignificant that
they can be ignored (tilt angle < 5°), i.e. the control always ignores the tool orientation and
assumes a circular cutting edge.
This also means that with reference to the active plane, the control accepts only a rotation by
180° as a setting deviating from the initial position. This limitation is valid for the shape of cutting
edge only. The tool lengths are always considered correctly in random spatial rotations.
Cutting edge position, cut direction and angle
A rotation by 180° around an axis in the machining plane means that while using the tool at
the same position, the spindle rotation direction with reference to the use of the unturned tool
must be inverted.
Cut direction and cutting edge position are also not modified like the cutting edge reference
point (see below) if the tool is rotated from the plane by +/- 90° (with a tolerance of app. 1°)
because then the configuration of the cutting edge is not defined in the current plane.
If the tool rotates in the plane (rotation around an axis vertical to the machining place or around
the Y axis for G18), the cutting edge position is determined from the resulting angle for the
clearance and holder angles. If these two angles are not specified for the tool (i.e. $TC_DP10
and $TC_DP24 are both zero), then the new cutting edge position is determined from the
turning angle alone. The cutting edge position changes only in 90° steps, i.e. the cutting edge
position remains independent of the initial state either in the value range 1 to 4 or 5 to 8. The
new cutting edge position is then determined exclusively from the angle of rotation if the
specified values for holder angle and clearance angle are not allowed (negative values,
resulting plate angle negative or more than 90°). Clearance angle and holder angle are not
modified in all these cases.
1472
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions
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