Festo DGE ZR RF Series, Инструкции по ремонту

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21 / 44 Festo 7DGE_ZR_RFb_en
If the measured natural frequency of the toothed belt is outside the specified
range, the toothed belt pretension must be set as follows:
• Adjust the toothed belt pretension by turning the socket head screws.
• Before you measure the toothed belt pretension again, the slide must be
moved back and forth a number of times so that the toothed belt can fully
settle and differences in tension are equalised.
Note
Turning the socket head screw clockwise increases the tension in the
toothed belt, and with this its oscillation frequency.
Turning the socket head screw anticlockwise decreases the tension in the
toothed belt, and with this its oscillation frequency.
• Place the cover caps in the drive covers at both ends.
4.1.3 Additional information on checking the toothed belt pretension
The correct toothed belt pretension is of critical importance for the service life of the toothed belt as well as the positioning
accuracy and performance of the toothed belt axis.
The conventional method for measuring the toothed belt pretension via the deflection force is too inaccurate and can
therefore not be used. Accurate results are achieved by measuring the oscillation frequency. The natural frequency of a
belt is based on its tension (strand force), mass and strand length.
Note
The strand length is the oscillating length of a belt.
Since the strand length cannot be determined directly at the toothed belt axis by easy means, the length L1 is used
instead for positioning the clamping body/clamp piece.
A pulse is applied to the toothed belt to start it oscillating. The natural frequency of the toothed belt generated in this
way is recorded using a meter and displayed as a frequency value in hertz.
Note
The frequency value is calculated using the specified values for strand force (pretension force), belt mass and length
of the free belt strand according to the following formula:
f Natural frequency of the freely oscillating strand [Hz]
L Strand length [m]
F
V
Pretension force [N]
m Weight per metre of the toothed belt [kg/m]