16
Keep the plugs with the transducer or as spare parts.
As the transducers take pressure forces only, they are clamped into the vibratory assembly under mechanical pre-
load, which is greater than the maximum forces produced by unbalance.
The forces are conveyed via 8-mm balls to the thrust spreading members, so that lateral movement does not
introduce forces on the piezo disc.
ATTENTION! With an already calibrated balancer, twisting the transducers can adversely effect plane separation.
3.8 TEMPERATURE SENSOR
The system has a new force guidance structure. The forces at the measuring transducers have been reduced, thus
achieving long-term stability and high measuring accuracy. Pre-tensioning of the transducers is achieved by two
leaf springs. On the vibratory system the measuring transducers are very close together so that the difference in
temperature has only a slight effect. The current vibratory sensor has a a digital temperature sensor integrated into
the optoencoder. The transducers can therefore be measured by
one
temperature sensor and taken into account
in a fraction of a second. This temperature sensor effects the transducers and is set during calibration. The signal
from temperature sensor is used to the compensate for temperature – dependant force to change conversion of the
unbalance transducers. With a defective sensor, the balancer will stay operational except for temperature correction
of the unbalance amount reading. The actual temperature reading will be substitute by temperature value determined
during calibration. Indication of current temperature is with service code C57.
The signal from temperature sensor is used to compensate for the temperature-dependant force to change conversion
of the unbalance transducers.
3.9 INCREMENTAL ENCODERS
An incremental encoder picks up the rotational travel, direction of rotation,
and absolute angular position of a rotating shaft.
One revolution is divided in increments (periods or intervals).
The output signals A and B have about the shape and relationship shown.
An intended irregularity (Nullmarke) is detected, with the main shaft
rotating at constant speed. On detection of the irregularity, the position
counter is set to zero thus providing absolute angular reference to the
shaft.
3.10 ENCODER BOARD OF THE MAIN SHAFT
The incremental encoder B8 is located between the ball bearings inside the
vibratory tube.
It consists in a plastic polygonal ring with the Printed Circuit Board (PCB) with
lens (
see picture
Y
).
The polygonal ring consists else of an annular polygon mirror at the main shaft
and the optoencoder unit (with lens) fastened with a screw M4, length 10 mm to
the slot in the vibratory tube.
ATTENTION!
To keep dust and light out of the tube, the opening for the
Optoencoder unit has to be covered with the dedicated plastic cover. In the
encoder IC on the Optoencoder unit, behind a lens there is a red, in the direction
of the main shaft, oblong Light Emitting Diode (LED). Behind a second lens, there are four light detectors on an
integrated circuit.
The light of the LED is refl ected back to the encoder by one of the 256 mirrors of
the polygon ring, focused by the lens on the four detectors. During rotation of the
main shaft, the mirrors or bars will tilt and defl ect the light across the detectors
A, A`, B and B`. With further rotation in the same direction, the light will hit the
next mirror or bar, and with a full revolution, it will be defl ected 256 times across
the detectors in the above given sequence.
The light detectors A and A` respectively B and B` are connected to one amplifi er.
The difference in brightness between the detector pairs determines the current
state of the output channels A and B. To keep the signals A and B free from
interference, an integrated circuit amplifi es the signals.
An intended irregularity in the arrangement of the mirrors is detected with the main shaft rotating at constant speed,
serving as absolute reference. On detection of the reference, the position counter is set to zero thus providing
absolute angular position of the main shaft.
Checking the incremental encoder is via service code C74.
SM HOF GEODYNA 7600 Rel.D
Summary of Contents for geodyna 7600
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Page 118: ...118 SM HOF GEODYNA 7600 Rel D ...
