Product category:
Springs, dampers, latches, locks and small components
News Release from: TFC | Subject: Smalley Crest-to-Crest Spirawave springs
Edited by the Engineeringtalk Editorial
Team on 29 November 2002
Spring saves space for automotive
manufacturer
TFC has developed a new pre-load flat wire spring design with shim-ends within a specialist steering column application for a major German automotive manufacturer.
TFC has developed a new pre-load flat wire spring design with shim-ends within a specialist steering column application for a major German automotive manufacturer The UK company, that manufactures the steering column for its German customer, had been using a conventional round wire helical coil spring to pre-load a narrow wall bearing but the spring design used was not performing to expectations
Among the problems encountered by design and test engineers was the fact the tolerance build up in the confined axial space of the assembly meant the spring forces generated were too high at their operating heights.
This resulted in the steering column producing torque-to-turn forces that were outside acceptable user bands.
To overcome these problems, the company needed an alternative product that could offer all the enhanced performance requirements, but operate over a wider tolerance band with a reduced spring rate.
As an added bonus, if the current use of support shims to eliminate point loading of the bearing could be avoided and, some weight savings could be achieved at the same time, this would directly affect the bottom line manufacturing costs and lead to volume cost savings.
A tall order.
Enquiries from engineers at the UK manufacturer led to TFC becoming involved in the project and suggesting a practical design solution that could offer all of the above benefits by replacing the conventional helical spring that had been used with a special pre-load spring design with flat turn shim-ends.
Brian Goode, TFC's Technical Director, says: "Having looked at the design brief from the company and at what they wanted to achieve within the steering column, we reasoned that one of our Smalley Crest-to-Crest Spirawave springs would be ideally suited for the job".
"This type of spring develops similar forces to conventional round wire or helical springs but occupies a third or less of the same space.
This not only allows it to be used in a tight axial space, but such high performance springs will also maintain the same deflection and load specifications of a conventional spring".
"Such a spring is manufactured with the benefit of an exclusive circular grain process, and drawn from a continuous coil of single filament pre-tempered round edge wire.
We reworked the design to include flat turn shim-ends and the final result is a spring that delivers everything the company needs, that weighs less and operates more effectively in the space envelope available".
"The circular grain process used also offers unrivalled production flexibility with no tooling costs, even for prototype or custom configurations.
The circumferential flow of the metal grain within the spring gives it a superior quality and performance and delivers accuracy, predictability, dependability and resistance to pitting, scratching, cracking and other imperfections".
"Typical uses for such springs, apart from steering columns, are applications requiring low to medium spring rates or large deflections with low to medium forces.
Because the springs are integrally formed, eliminating the need to keep the wave crests aligned, the wave peaks hold their configuration without needing to use a key locating device or to insert a shim between individual springs and, as in this case, form an ideal solution to an engineering problem where a normal helical spring just could not do the job". Request a free brochure from TFC ...
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