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Contitech
Airspring Systems, a part of the giant Continental
Corporation manufacture a range of air spring
systems now available in UK for the first
time from FTL Technology of Leeds.
The Airspring elements are manufactured from a composite elastomer and synthetic fabric material in a process not unlike radial car tyre manufacture. This gives an indication of the level of toughness and service life that can be expected.
Contitech Airsprings are best visualised as a hybrid pneumatic cylinder cum spring cum vibration isolator. The range breaks down into 3 designs which have been developed to maximise the unique features of the product. They are:
For such an apparently simple design the Airspring has a number of interesting properties, which when compared with the alternative metal or elastomer spring element can be used to advantage.
The Airspring possesses a constant natural
frequency irrespective of load and height.
A “normal” compression spring
suffers a decrease in natural frequency as
the load increases and a converse increase
as the load decreases. This feature can be
of benefit in applications such as vibrating
screen graders where the load changes constantly
but the frequency determines the rate of feed
which ideally should remain constant.
Vibrating conveyors and screening equipment
would be a suitable application for capitalising
on these properties.
The Airspring generates its load capability
by means of a variable internal pressure,
(most normally air). Compared to a steel compression
spring which decreases in height as the load
increases the Airspring maintains constant
height by simply increasing the air pressure.
A constant height control mechanism can be
supplied to maintain constant height even
under fluctuating load conditions.
Machinery such as industrial weighing equipment
that can be subjected to alternating loads
caused by differing charge weights can make
full use of this feature
A normal pneumatic cylinder generates a constant force through out its stoke length. Because of the internal geometry of the Airspring the load decreases with an increase in stroke. However a rolling lobe air spring overcomes this and is able to provide constant force for most of its stroke length. This feature can be used to advantage on air suspension systems where both a raising cycle can be used prior to a constant load being applied.
Airsprings not only exhibit constant natural
frequency but it is also very low (typically
between 0.5 and 3.5Hz depending upon configuration).
This can be used to advantage on all types
of equipment to isolate inbuilt vibration.
It is possible on heavy duty machinery (above
50 tons in weight), with an excitation frequency
in the 20-30Hz spectrum, to isolate 98% of
the vibration within the air isolation system,
such as grinding mills, rotary crushers and
large ventilation fans
Elastomeric/synthetic fabric air springs are
most normally associated with compressed air
up to 8bar pressure as the working medium.
However special construction and locating
techniques allow pneumatic pressures of up
to 18-20 bar to be employed.
By altering the choice of elastomer it is
also possible to consider the use of fluids
such oil or water as the energising medium.
Temperatures up to 100°C are also possible.
The unique features of Contitech Air springs and Air Isolators are further explained in a free design guide along with an application engineering service from FTL Technology.
END
Further Information
For further information relating to any of the above products, please contact Tony Snowdon on 0113 252 1061 or e-mail tonys@ftltech.co.uk