DS Europe 500QD Series, Инструкция по эксплуатации

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Small measuring ranges (especially the 2-3-6Kg): it is necessary not to apply
overloads, not only during the normal load cell use but also during handling and
mechanical installation.
All these accessories have to be scaled and made by the Customer, in relation to the
applications and the standards imposed.
6) MECHANICAL INSTALLATION OF LOAD CELLS
6.1 FIXING AREA OF THE CELL (See again the paragraph 4.2.1):
The fixing area of the cell has to touch the fixing base always in all its points.
Errors, even of 20÷30% FS, may occur from separated contact points which number and
position change the axis of force in relation to the applied load.
Off centre loads produce measuring errors.
Load cells are calibrated on test benches with adapters that warrant a load cell fixation and
alignment with ±0,05mm e ±1° tolerances.
Mechanical installation is always adding some errors to that one of the load cell therefore a
machine application cannot have only the bare load cell intrinsic error.
Load cell errors are a percentage to be calculated onto their measuring ranges and not onto
the force to be measured that can be much smaller.
In case more than one load cell is used, in the same machine application, then a combined
error is to be considered too.
The main installation cares to be taken are the following:
6.1.1 Fixing base in high strength steel with thickness, at least, 1,5 times that of the cell.
6.1.2 Contact surface flat and finely machined
and clean.
6.1.4 Very important: Strong and even clamping of the screws by dynamometric wrench:
to obtain an uniform and extended contact.
Use only high strength steel socket head screws and flat washers.
Safety is usually depending on a correct fixation of screws threads: it is suggested to
use safety systems that prevents their accidental unlocking like by means of lock
nuts.
After initial screw fixing the load cell electrical signal, without load, could shift a bit:
it is necessary to perform a small mechanical cycling with a significant load
(compared to the load cell measuring range) and then adjust the screw clamping
again with the wrench.
6.1.5 For the load cells with low full scales (up to 50 Kg), during the installation, avoid
overloads and torsions that may damage the cell even if it is not electrically
connected.
6.1.6 Mechanical guiding systems, of the measured to force, along the load cell measuring
axis, are to have a low fiction.