sensors & systems - Industrial Technology Magazine

DESIGN COMPONENTS
Springs, Gas Springs & Dampers
Engineering
success for
‘elastic’
components
Christian Bauer disc springs
are manufactured to the
tolerances, material
specifications and performance
parameters of DIN 2093, provide
highly reliable ‘elastic’ technical
components which can form the
building block elements of spring
packs. Under applied load or
torque, the spring yields with a
defined and repeatable
deformation, while an opposing
reaction force is at the same time
stored as energy within the spring.
With their precise and
controlled characteristics they are
becoming ever more recognised as
ideal components where high
forces, are combined with limited
space, precise movement, long-
Constant force and wave
springs added to portfolio
With the latest additions to its range, the Lee Spring portfolio now
extends to over 15,000 stock spring types. Something for everyone...
New constant force and Redux
wave springs have been added
to Lee Spring’s portfolio of
products, increasing its stock spring
range to over 15,500 different types of
spring. Custom designs in both springs
are also available.
Manufactured from high yield 301
stainless steel strip, the constant force
springs exert a near constant restraining
force to resist uncoiling. This natural
inbuilt stress resists load at an even
rate and makes them suitable for
use in retractor mechanisms.
Common applications include
counterbalance springs, car seat
belts and cable retractors.
Constant force springs are
tightly coiled on a drum and either
the free end or the drum can be
attached to the load. Four life cycle
ranges are offered: 2500, 4000,
13000 and 25000 covering loads from
1.02 to 73.42N (0.23 to 15.50 lb).
Lengths vary from 356 to 1542mm,
thicknesses from 0.10 to 0.51mm and
widths span the range 6.35 to
31.75mm.
Wave springs perform a similar
function to compression springs but they
take up
approximately 50% less compressed
height space due to their sine wave
design which allows tangential contact.
These springs also offer greater control
of axial movement and consistent load
transfer.
Produced in stainless steel type 17.7
PH, Lee Spring’s Redux wave springs
offer optimum performance in static or
slightly dynamic applications where
space is critical or where radial and
axial tolerances are tight. Stock sizes
range from rod sizes of 6.35 to
25.40mm to suit hold diameters from
9.53 to 31.77mm and in spring rates
from 1.58 to 52.21N/mm (9.00 to
298 lb/in).
MORE INFORMATION:
Enter D364 on the card, or visit ‘latest issue
stories’ at www.industrialtechnology.co.uk for
further details from Lee Spring
Dampers control oil storage bunker
doors in high winds
term reliability and virtually
maintenance-free operation.
Disc springs combine the
highest forces within the smallest
height parameters compared to
other spring mechanisms and are
generally applied when high forces
are needed for compensation due
to thermal expansion or for
tolerances. Individual discs can be
combined in series, parallel or
mixed stack combinations to
provide custom designed
characteristics to the customer
requirements. General engineering
uses include slotted disc springs
used for a compressor clutch, with
a single disc spring providing
sealing pressure for a feeder valve
used with liquid plastics or resins.
MORE INFORMATION:
Enter D368 on the enquiry card, or visit
www.industrialtechnology.co.uk for
further details from Bauer Springs
Industrial Gas Springs (IGS) has
provided large size dampers to control
a set of doors on a storage bunker at
an oil refinery situated on the coast of
West Wales. Aker Kvaerner Engineering
Services approached the company in the
course of carrying out work at the site,
with a view to finding the most efficient
solution to a potential safety hazard.
“I asked IGS to recommend a
suitable gas spring/shock absorber for
two fully clad 2m wide by 4m high
doors, due to safety concerns,” explains
David Nicholetts, structural designer for
Aker Kvaerner. “The doors needed to be
able to take a wind load of 3kN when
opening/closing but the dampers were
not required to assist in opening/closing
operations or in restraining the leaves in
their open/closed positions.”
The request was then followed up by
project engineer Owen Derrick, who sent
IGS some initial drawings and
dimensions of the doors, which were to
be installed on a storage tank radiation
bunker.
“We started to look at all the
requirements for this project and
consider possible solutions,” says IGS
commercial manager Jean-
Philippe Duvillard. “All of
them were limited by the
wind pressure the doors
would be subjected to: the
force was finally specified to
be equivalent to 1500
Newton per square metre.”
Safety limits
“In order to damp the opening
of these doors, we had to use
the largest gas springs we
could manufacture,” he
continues. “It was also necessary to limit
the stroke to minimise the risk of the
dampers buckling, while keeping the
length sufficient to keep the forces
applied onto them below 11000 Newton
– which is the safety limit on our size 20
dampers. Finally, the amount of damping
was calculated so the doors would open
slowly in gusty wind conditions and the
dampers would be completely free when
the doors are being closed.
“We recommended using five-off
dampers with a size 20mm rod and
40mm body diameter for each door, fully
oil damped in compression and free in
extension. The dampers have proved a
very effective solution.”
Derrick concludes: “We are really
pleased with the final result. While it is
a somewhat slow process to open the
doors when there is no wind, there is no
need to exert any force on them – they
will not open faster and the operator
simply has to ‘walk with the door’ as it
opens.”
MORE INFORMATION:
Enter D365 on the enquiry card, or visit ‘latest issue
stories’ at www.industrialtechnology.co.uk for
further details from Industrial Gas Springs
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INDUSTRIAL TECHNOLOGY • May 2008