Festo DGE ZR RF Series, Инструкции по ремонту

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6.3 Checking and setting the toothed belt pretension
Warning
Checking and setting the toothed belt pretension is only required and permissible after a new toothed belt is installed.
The pretension of the toothed belt diminishes during storage and operation.
This is a normal process and not an
indication of wear. Retensioning the toothed belt can result in premature wear.
The toothed belt pretension has a direct influence on the service life of the toothed belt and the performance of the
toothed belt axis. Extreme care must therefore be exercised when checking it.
Before the toothed belt pretension can be measured, the slide/piston must be moved back and forth a number of
times to allow the toothed belt to fully settle and differences in tension to be equalised.
6.3.1 Checking the toothed belt pretension
Note on measurement using the acoustic belt tension meter
If the toothed belt is excited by means of a force stimulus, the strand oscillates with its natural frequency; this dies down
reasonably quickly depending on the attenuation.
The frequency meter measures the natural frequency generated (transverse oscillation) using the acoustic operating
principle. In addition to the basic oscillation (natural frequency), harmonic oscillation can also occur. From experience it
is always the first harmonic oscillation. In other words, a further oscillation node is generated and therefore in addition to
the basic oscillation frequency, values that are twice the natural frequency can also be measured.
For this reason, several measurements should always be carried out to differentiate the necessary basic oscillation
(natural frequency) from the harmonic oscillation. Only this frequency can be used to extrapolate the force acting along
the strand.
• Pull the plunger upwards and then release it.
Note
The distance that the plunger has to be pulled out to generate the optimum
force stimulus depends on the size and design of the toothed belt axis and
must be established during the test.
The magnitude of the force stimulus does not influence the measured na -
tural frequency oscillation, it only changes the magnitude of the oscillation
amplitude.
Smaller toothed belt axes tend to require a smaller force stimulus.
Note
The belt must be able to oscillate freely. Push clamp pieces into the toothed
belt axis if necessary (see section
6.2 “Preparing the test equipment” ).
To assess the toothed belt pretension, several measurements should be
made to balance out any measurement tolerances.