Product category:
Springs, dampers, latches, locks and small components
News Release from: Lee Spring | Subject: PowerSpring
Edited by the Engineeringtalk Editorial
Team on 18 November 2002
New concept in spring technology
A new and revolutionary spring with exceptional power and load characteristics offers a high-performance alternative to steel springs.
A new and revolutionary spring with exceptional power and load characteristics that offers a high performance alternative to steel springs was launched this week at TEAM 2002 Called PowerSpring, the new product is a flexible, high strength tension/extension spring manufactured from a natural rubber core enclosed in braided fibre inner and outer covers
A standard 32mm diameter PowerSpring delivers 3.5kN at 90% elongation.
Developed by Ibex, an established manufacturer of shock cord and braided rope products, PowerSprings are available in the UK through Lee Spring - Britain's No 1 stock spring supplier.
With virtually no restriction on length and terminations to suit most applications, PowerSpring opens up new design possibilities and applications where energy and propulsion, dampening, shock absorption or retainer mechanisms are required across many industries.
The spring is assembled by crimping its cord into a metal fitting.
This opens out the exposed rubber core ends, creating longitudinal spaces between the strands.
Epoxy is injected into the termination and penetrates these spaces to form a solid 'plug'.
A metal disc, fitted to cover and protect the bonded strands, completes the spring assembly.
This crimped region isolates the active cord from the bonded region, increasing fatigue life by removing the main stress raisers often present in other termination methods.
The bonding process allows the full potential of the spring to be realised.
In tests, carried out by the Institute of Spring Technology, in excess of 5 million load cycles have been achieved.
End fittings manufactured in aluminium alloy to BS6082 (HE30) or cold drawn steel to BS3602 (DIN2391) are offered as standard but custom designs in different materials, stainless steel for example, can be accommodated to meet application demands.
Polyester inner and outer braided covers provide protection to the natural rubber core.
However, other materials, such as aramid yarns and polyethylene can be employed to increase thermal resistance or reduce friction and improve resistance to chemicals.
Although normally supplied in white, coloured braiding can be introduced to identify or differentiate the product.
While a standard 32mm-diameter PowerSpring delivers 3.5kN at 90% elongation, the smallest, 12.5mm diameter product, boasts 0.5kN.
PowerSprings can be specified in a similar way to steel extension springs.
The load at any extension can be calculated as the product of the spring rate and the percentage extension plus the initial tension.
Maximum usable extension depends on service life required.
Although the British Standard states that the braid shall withstand a single extension to 105%, the recommended maximum working extension is 90%.
Service life can be greatly increased in continually oscillating situations where there are a large number of cycles if the extension is not allowed to fall below 15% during load cycles.
PowerSpring is available in six diameters from12.5 to 32mm and in any length from 100mm to 100m.
Length is subject to a tolerance of +/-1% or 5mm.
The normal operating temperature range for a PowerSpring is -10 to +75C.
However if the PowerSpring is undergoing load cycles there is little effect on performance at temperatures below -10C.
PowerSprings can be used in a variety of environments and are often tolerant of minor contamination.
The aluminium or cold drawn steel end fittings have good resistance to corrosion and many chemicals.
Where additional protection is required stainless steel can be used.
The natural rubber core has excellent resistance to water and many chemicals, although mineral oils and ozone affect it.
Where contamination is a possibility, the core must be protected.
When protection is required a sealing coat, such as latex, can be applied to the outer braid. Request a free brochure from Lee Spring ...
(This was Engineeringtalk's Top Story on 15 November 2002).
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