Speedy spring solution to front seat manoeuvrability
When a leading European automotive OEM needed a quick yet reliable and cost effective solution to a spring-related engineering problem, it found the solution by approaching William Hughes.
An auto plant needed a short lead-time spring solution for seats being fitted into its latest two-door model. To assist a back-seat passenger climbing in and out of the vehicle, the front seat needs to slide forward and the squab (seat back) needs to fold down. The car manufacturer discovered that its existing seat mechanism was a little too heavy to operate, especially for children and elderly people. As a result, the auto giant's tier one seat supplier approached William Hughes to design, manufacture and supply a customised spring.
The challenge was far from straightforward as there were a number of stringent specifications to fulfil. For instance, the special spring had to be unseen, unheard and operate smoothly avoiding catch points. Additionally, William Hughes' engineers could only use existing holes and edges available within the seat structure mechanism. Health and safety regulations were another crucial consideration with regard to avoiding injury to assembly personnel, an area that can be a potential pitfall for less experienced spring makers.
Engineers from William Hughes arrived at the seat maker's manufacturing site in Europe to discover that the customer had already come up with a solution proposal. However, it soon became apparent that it would not overcome the problem. Even though the mechanism had been designed on the customer's CAD system, little consideration had been given to performance measures such as force and movement.
Time was now of the essence. Fortunately, William Hughes was able to quickly assess parameters such as torsion force, track length, fitting space and mounting points, offering technical advice to the client on how to produce a high quality and effective, yet economical solution. As a result, the specialist spring maker was able to modify the design and produce a set of prototype springs overnight. After in-situ testing, further modifications led to a second set of rapidly-produced prototypes that provided the perfect solution. Concurrent engineering ensured that the special tooling required to manufacture the prototype springs was delivered in a matter of days - each spring requires a total of six bends, four at one end and two at the other. The springs have since successfully completed endurance testing.
The solution devised by William Hughes takes the form of a set of springs - right and left hand versions. Once assembled, this pair of innovative bespoke springs offers an improved sliding and folding motion when the seat release lever is activated. It's a solution that enhances rather than replaces the existing mechanism, and although it introduces extra material, it proved far more economical than the customer's original proposal.
Manufactured from hard drawn spring steel, the special torsion springs have been designed to fit with minimum effort to the car seat structure without any modification to existing parts, thus ensuring continuity of production.
The project represents the latest example of how engineers at William Hughes' high-tech facility at Stalbridge in Dorset liaise closely with customers to generate innovative and cost effective bespoke spring solutions from wire diameters ranging between 0.1 and 5.0mm diameter. The combination of design effort and rapid response is a factor that helps differentiate the company in the marketplace. William Hughes only manufactures proprietary springs - compression, tension and torsion - it has no catalogue and does not make for stock.
The company can also offer an extensive range of additional services that include shot-peening (for extended fatigue life) and the application of corrosion-resistant inorganic coatings (Delta Seal). Also on offer are heat treatment services, precipitation hardening, assembly, ultrasonic cleaning and full quality control and inspection of finished parts including ultra-accurate squareness measurement if required.
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