W1: Tool offset
18.5 Tool radius compensation 2D (TRC)
Basic Functions
1468 Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Retraction/approach with circles
Approach/retraction with circles?DISR indicates always the radius of the tool center point path. If tool radius
compensation is activated, a circle is generated internally, the radius of which is dimensioned such that the tool
center path is derived, in this case also, from the programmed radius.
An alarm is output on approach and retraction with circles:
• If the radius of the circle generated internally is zero or negative
• If DISR is not programmed
• If the radius value ≤ 0.
DISCL
DISCLspecifies the distance from point P2 from the machining plane.
If the position of point P
2
is to be specified by an absolute reference on the axis perpendicular to the circle plane,
the value must be programmed in the form DISCL = AC( ....).
If DISCL is not programmed, points P
1
, P
2
and P
3
are identical with G340 and the approach contour is mapped
from P
1
to P
4
.
The system checks that the point defined by DISCL lies between P
1
and P
3
, i.e., in all movements, which have a
component perpendicular to the machining plane (e.g., infeed movements, approach movements from P
3
to P
4
),
this component must have the same leading sign. It is not permitted to change direction. An alarm is output if this
condition is violated.
On detection of a direction reversal, a tolerance is permitted that is defined by the machine data:
MD20204 $MC_WAB_CLEARANCE_TOLERANCE (direction reversal on SAR).
However, if P
2
is outside the range defined by P
1
and P
3
and the deviation is less than or equal to this tolerance,
it is assumed that P
2
is in the plane defined by P
1
and/or P
3
.
Example:
An approach is made with G17 starting at position Z=20 of point P
1
. The SAR plane defined by P
3
is at Z=0. The
point defined by DISCL must, therefore, lie between these two points. MD20204=0.010. If P
2
is between 20.000
and 20.010 or between 0 and -0.010, it is assumed that the value 20.0 or 0.0 is programmed. The alarm is output
if the Z position of P
2
is greater than 20.010 or less than -0.010.
Depending on the relative position of start point P
0
and end point P
4
with reference to the machining plane, the
infeed movements are performed in the negative (normal for approach) or positive (normal for retraction)
direction, i.e., with G17 it is possible for the Z component of end point P
4
to be greater than that of start point P
0
.
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