
B-63662EN/01 11.CONTROL FUNCTIONS
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11.1 OPTICAL PATH LENGTH COMPENSATION
If there is a movable reflector, the propagation distance between the
oscillator and condensing lens varies as the reflector moves.
Generally, stable machining characteristics are obtained within a
limited propagation distance range. In a large machine tool in which
the reflector has to move through a long distance because of its
mechanical structure, the required propagation distance may exceed
its limit, hampering stable machining over the stroke of reflector
movement. To solve this problem, the 16i-LB is provided with an
optical path adjustment axis and an optical path length compensation
function. When a command is issued which requests that the reflector
be moved, the optical path length compensation function
automatically adjusts the optical path adjustment axis to maintain a
constant optical path length.
Optical path length compensation uses the following mechanism.
1 An axis (called the U-axis) must be available along which a
beam reflecting mirror block (shown below) moves linearly to
vary the propagation distance.
2 The U-axis should be configured to change the propagation
distance α times (1 to 511) as much as the movement of the
mirror block.
3 The maximum speed of the U-axis should be higher than or
equal to 1/α the total rapid traverse rate of the axes that can
change the optical path length.
4 All axes including the U-axis should have reference point. The
optical path length is calculated based on the reference point.
5 An interference protection provision should be installed for all
axes that may otherwise interfere with the U-axis.
Oscillator
U-axis
Mirror block
Nozzle head