Siemens SINUMERIK 840D Description Of Functions page 250

A Hydraulics
A.2 Cylinder
Quality of seals
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Piston
2 x guide ring
(PTFE)
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Seal
(FPM+PTFE)
Fig. A-21 Cylinders
Dead volume
A-250
SINUMERIK 840D/SIMODRIVE 611 digital Descr. of Functions HLA Module (FBHLA) – 04.00 Edition
In order to ensure the lowest possible frictional forces, the quality of the seals
and guides on the piston, and the piston rod itself, must be particularly high.
Transitions from static to sliding friction have a particularly adverse affect on the
quality of control accuracy. A friction compensation setting has been provided in
the HLA module (MD 5460: FRICTION_COMP_RADIENT) for the purpose of
counteracting initial friction.
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The dead volume is the volume between the cylinder and servo solenoid valve
that is not displaced by one piston stroke. It reduces the natural frequency of
the drive and should be avoided wherever possible.
Cylinder pipework should be kept as short as possible, i.e. the servo solenoid
valve should be mounted directly on the cylinder.
The dead volume is parameterized in the HLA module (MD 5135, MD 5136 and
MD 5141...5143).
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Piston rod
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2 x guide ring Stabilizing ring
(PTFE) (FPM)
2 x sealing ring
(FPM+PTFE)
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