User`s manual

STRAIGHTNESS WITH CENTRE OF TUBE AS REFERENCE
For complete description see also standard straightness.
Introduction
The purpose of the measurement is to align the diameter center of the
measurement object in relation to a reference line, represented by the laser
beam. The laser beam is used to project the axis of rotation of the reference
object. This method is used in applications where the reference object is
positioned away from the measurement object, e.g. having the rotary flange
on a gearbox as a reference when measuring a bearing journal on a propeller
shaft installation or an extruder barrel.
When performing the measurement the center of the fixture in which the
receiver is mounted is arranged to represent the center of the tube. The
diameter of the tube has to be the same throughout its length.
The method can either be used with or without rotating the laser transmitter
at every measurement point. When rotating the laser at every measurement
point it is not necessary to center the laser exactly to the center of the rotary
flange. When not rotating the laser transmitter at every point the laser has to
be positioned exactly in the rotational axis of the rotary flange.
In the following the measurement principle is described using an extruder
barrel as example. The procedure describes how to perform the measurement
when rotating the laser transmitter at every point. This method is based on
the principle of “coning”.
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