Probing (Cycle 444); Cycle Run - HEIDENHAIN TNC 640 User Manual

Touch Probe Cycles: Special Functions | 3D PROBING (Cycle 444)
17.4 3D PROBING (Cycle 444)

Cycle run

Cycle 444 checks one specific point on the surface of a component.
This cycle is used, for example, to measure free-form surfaces of
molded parts. It can be determined whether a point on the surface
of the component lies in an undersize or oversize range compared
to a nominal coordinate. The operator can subsequently perform
further machining steps, such as reworking.
Cycle 444 probes any point in three dimensions, and determines
the deviation to a nominal coordinate. A normal vector, defined in
parameters Q581, Q582, and Q583, is used for this. The normal
vector is perpendicular to an imagined surface in which the nominal
coordinate is located. The normal vector points away from the
surface, and does not determine the probing path. It is advisable
to determine the normal vector with the help of a CAD or CAM
system. A tolerance range QS400 defines the permissible deviation
between the actual and nominal coordinate along the normal
vector. This way you define, for example, that the program is
to be interrupted if an undersize is detected. Additionally, the
TNC outputs a log and the deviations are stored in the system
parameters listed below.
Cycle run
1 Starting from the current position, the touch probe traverses
to a point on the normal vector that is at the following
distance from the nominal coordinate: Distance = ball-tip
radius + SET_UP value from the tchprobe.tp table (TNC:\table
\tchprobe.tp) + Q320. Pre-positioning takes a set-up clearance
into account. For more information on the probing logic, See
"Executing touch probe cycles", page 497
2 The touch probe then approaches the nominal coordinate. The
probing path is defined by DIST, not by the normal vector! The
normal vector is only used for the correct calculation of the
coordinates.
3 After the TNC has saved the position, the touch probe
is retracted and stopped. The TNC saves the measured
coordinates of the contact point in Q parameters.
4 Finally, the TNC moves the touch probe back by that value
against the probing direction that you defined in the parameter
MB.
HEIDENHAIN | User's manual for cycle programming | 10/2017
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