Maximum Permissible Speed; Exceeding The Permitted Speed; Imbalance; Calculating The Required Clamping Forces - Rohm Norm RN 1391 Informaciones Y Directivas Generales Para El Empleo De Instalaciones De Sujeción Accionadas Por Fuer

1.2.2

Maximum Permissible Speed

The maximum permissible speed may only be used when the maximum actu-
ating force is applied and when the chucks are working correctly. Failure to
observe this basic principle may lead to a loss of clamping force and as a res-
ult to workpieces flying out with an associated risk of injury. At high speeds,
the clamping device may only be used below a protective hood of an ad-
equate size.
1.2.3

Exceeding the Permitted Speed

This unit is intended for circumferential use. Centrifugal forces - caused by
excessive revolutions or circumferential speeds - may cause individual parts
to become loose and represent a potential source of danger to nearby objects
and persons. In addition, with clamping devices which are only authorised for
lower speeds but which are operated at higher speeds, imbalances may occur
which have a negative effect on safety and possibly the machining result.
For the above reasons, operation at higher speeds than intended for this
equipment is not permitted. The max. speed and actuating force / pressure
are engraved on the body and must not be exceeded. This means that the
highest speed of the intended machine must therefore not be higher than that
of the clamping device and must therefore be limited.
Even if permissible values are only exceeded once, this can lead to damage
and represent a concealed source of danger even if it is not discernible at
first. In this case, the manufacturer is to be informed immediately so that a
test of functional and operational safety can be carried out. This is the only
way to ensure continued safe operation of the clamping equipment.
1.2.4

Imbalance

Additional risks may occur due to insufficient rotational balance, see § 6.2 No.
e) EN 1550. This applies in particular at high speeds, when machining asym-
metrical workpieces or when using different top jaws.
To prevent damage resulting from this, the chuck with the workpiece is to be
balanced as dynamically as possible as per DIN ISO 21940.
1.2.5

Calculating the Required Clamping Forces

The required clamping forces or the maximum permissible speed for the
chuck for a certain machining task are to be calculated in accordance with the
Directive VDI 3106 - Calculation of the permissible speed of lathe chucks (jaw
chucks). If, for design reasons, necessary special jaws are heavier or larger
than the clamping inserts assigned to the clamping device, the associated
higher centrifugal forces must be considered when calculating the required
clamping force and the permissible speed. See also Reference Speed and
Clamping Force Calculation [} 39].
RN-1391
Safety Instructions and Guidelines | 1
EN
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