D-M-E
7b-1
lGas spring systems
nPlynové pružiny
llSystemy sprężyn gazowych
nСистемы газовых пружин
1/9/2007
lDesigned with the most advanced tech-
nologies. The main components of the
cylinders, as the body, the piston rod and
the locking nut, are made of highly resis-
tant steel and undergo thermic treat-
ments and surface finishing to guarantee
elevated performances and long
endurance. The piston rod seals and
guide rings are of high quality, and are
selected after a careful evaluation of their
functional features. The internal lubrica-
tion system of each cylinder guarantees
a longer endurance of sliding parts, dras-
tically decreasing maintenance interven-
tions and increasing productivity (Each
type of cylinder has undergone testing to
garantee a very high quality product).
Operation and working conditions
Nitrogen, an inert gas, is introduced
inside until the maximum pressure of 15
MPa is reached. In rest conditions the
gas pressure acts on the piston rod sec-
tion (fig. 1), and pushes it outwards with
a resultant force equal to the cylinder
starting force (the force measured in KN
is obtained from the product of the MPa
pressure by the section of the piston rod
in cm2). During the operating cycle the
piston rod retracts inside the tube, com-
pressing and decreasing the volume of
the gas contained inside the chamber
and provoking the force increase. The
nitrogen cylinder has a behaviour similar
to that of a traditional mechanical spring,
but contrary to this one it doesn't need
any precharge. These cylinders can work
in any position without being lubricated.
Being hermetically sealed while working
they maintain inside the special lubricant
introduced during assembling. The partic-
ularity of the sliding guides and the char-
acteristics of the seals used guarantee an
elevated reliability. After a period of inac-
tivity of the system it is advisable to pre-
ventively carry out about ten complete
working cycles of the spring-cylinders
with the purpose of optimizing the seal-
ing. It is better to avoid overheating, as it
inevitably would provoke a rise in pres-
sure inside the cylinder; we advise not to
pass the 12mt/minute of linear speed of
the piston rod. This corresponds to about
1/5 of the permissable value for the seals
used. The calculation of the working rate
can be done as follows: considering that
in one single cycle the piston rod of the
gas spring performs two strokes, going
and return, the number of cycles per
minute is given by the formula:
where W is the piston rod speed
(mm/minute) and C is the stroke (mm)
EXAMPLE: If a cylinder performs a
stroke equal to 150 mm at a linear speed
Info/Инфо
of 8000 mm/minute, we will have:
The nitrogen cylinder maximum filling
pressure must be of 15 MPa; with this
value the final pressure reached in com-
pression is one of 25 MPa.
Nitrogen cylinders life
If correctly installed and in normal using
conditions nitrogen cylinders are guaran-
teed for a minimum stroke extension
equal to 75.000 meters. Such measure is
given by the sum of the piston rod feed
travel and reversal. In particularly critical
working conditions or in case of a product
malfunctioning due to external causes, a
maintenance intervention can be neces-
sary to replace the seals or the damaged
parts. The user can perform the mainte-
nance with the tools and procedures indi-
cated in this catalog. It is available to sat-
isfy the requests or the necessities of its
customers.
Working temperature
The maximum working temperature
allowed is of 70°C. Higher temperatures
can damage the characteristics of the
seals. The temperature variations inside
the nitrogen cylinders determine the load-
ing pressure variation: a temperature
increase of 1°C corresponds to the nitro-
gen pressure increase, measured in MPa
of a value equal to 0,0367.
Warnings
In order to obtain longer and better life of
nitrogen cylinders we advise the user to
observe the following precautions during
usage:
• Avoid interventions or damages on the
bodies and piston rods.
• Do not remove before use the piston rod
protection net, accidental impacts can
scratch or damage the surface.
• Cylinders are filled with nitrogen N2 gas,
absolutely do not use any other type of
gas.
• Gas loading must be performed with the
piston rod completely pulled out.
• Do not fill with pressures higher than 15
MPa
• Before proceeding with dismantling of a
cylinder make sure that it is exhausted.
The piston rod must be able to reverse
freely inside the body.
Identification
All nitrogen cylinders are clearly identified
by means of adhesive labels and a mark-
ing on the body, as provided by ISO stan-
dard.
Guarantee
The guarantee lasts 1 year beginning
from the operating date. D-M-E is respon-
sible in the case the product doesn't cor-
respond to the quality and construcion
feature guaranteed. The manufacturer is
not liable for presumed damages caused
by improper use or usage not correspon-
lFeatures and types AR, AR/C, AR/P, KC, SR llCharakterystyki typów AR, AR/C, AR/P, KC, SR
nVlastnosti typů pružin AR, AR/C, AR/P, KC, SR nХарактеристики итипы AR, AR/C, AR/P, KC, SR
lConvex head of the rod
lHole for ring extraction
lRing of arrest
lGuiding bushings
lIntegral body
lRod wiper
lO-ring
lRod seal
lCharging hole
n = 8000
150 x 2
= 27 cycles/min.
+7b-2
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