DuPont at Fakuma 2006 - Slide Element made of DuPont™ Delrin® Enables Optimal Side Support in Car Sports Seats
Oct 27, 2006
FRIEDRICHSHAFEN -- Whether a comfortable width during a relaxed cruise or a precise level of side support on fast curves - active backrest width adjustment (referred to as the ALBV system) from L&P Automotive Europe (formerly Schukra), Nuremberg, enables optimal side support whatever the situation. Integrated in the front seats of the more sporting models from BMW, the electronically-controlled system uses signals from the ESP sensors to adjust the angle between the backrest and its side cushions according to the style of motoring. During this process, a high load-bearing slide element, made of a particularly low-wear and low-resistant grade of DuPont™ Delrin® acetal resin, quietly and smoothly converts the rotation of the servomotor into linear movement. L&P Automotive Europe provides the ALBV system to Faurecia, who is the supplier of the complete seating module.
According to Veit Stobel, purchasing manager at L&P Automotive Europe: "We were already familiar with Delrin® as a material of choice for low noise and low wear drive systems, and therefore wanted to use it in our ALBV system. Preliminary trials soon showed that slide elements made of standard grades would be unable to withstand the high bending forces experienced when, for example, a heavily-built person used the backrest sides as support when getting in or out of the vehicle. Upon DuPont's advice, we used data for the specialty grade Delrin®100KM, which is reinforced with DuPont™ Kevlar®, during the concept phase. Using this material we are now able to fulfil conflictive requirements with regards to force transduction, elasticity and impact resistance with a component that is both low weight and offers excellent low wear, low friction behaviour."
The slide element is produced as a T-shaped part. A gear rack is integrated in the horizontal slide section, which enables the adjustment. The vertical support area is positively attached to the seat's side cushions. The gear rack converts the rotation of the metal sprocket on the servomotor into linear movement, which follows a circular path. The slide element is guided by a chassis made of glass-reinforced (PBT). Says Sto?el: "Due to the low amount of friction created between Delrin® 100KM and metals, as well as other engineering polymers, and thanks to the low wear resistance of the material, the adjustment, which takes less than a second to move between catches, requires no lubrication or maintenance during the lifetime of the seat."
The manufacturer worked with DuPont on the optimisation of the slide element's performance and weight. According to Roland Och, engineering & design manager at L&P Automotive Europe: "With the benefit of finite element analysis, conducted by DuPont, we were able to assess and position the reinforcements and ribbing in such a way that the part is able to absorb extremely high flexural forces despite its reduced weight." In terms of processing, the comparatively high viscosity of the melt demanded special attention. Och continues: "The amount of Kevlar® in Delrin® 100KM reduces the potential flow distance when compared to unreinforced grades. This needed to be considered when we came to designing the flow channels in the cavity and near the gate. Moreover, we optimised the number, positioning and design of the gates so that the weld lines were in uncritical areas and both warpage and required cycle times were minimised."
"Due to its system-specific benefits - particularly with regards to the greater precision in load application and seat adjustment than can be achieved compared to pneumatic systems - the ALBV system from L&P Automotive Europe is a topic of great interest among the automotive industry," says Sto?el. "We are investing heavily in the continuing development of this technology, and our positive experience with Delrin® 100KM to date means that the specialty acetal from DuPont will be a material of choice for future sliding elements."
L&P Automotive Europe,a subsidiary of Leggett and Platt, and with offices in Belgium, Wales, Austria and Germany, is a world leading manufacturer of individually adjustable lumbar support systems for all kinds of seat and backrest applications and is a supplier to a number of the most famous automotive and aerospace manufacturers.
The DuPont Engineering Polymersbusiness manufactures and sells Crastin® PBT and Rynite® PET thermoplastic polyester resins, Delrin® acetal resins, Hytrel® thermoplastic polyester elastomers, DuPont™ ETPV engineering thermoplastic vulcanizates, Minlon®mineral-reinforced nylon resins, Thermx® PCT polycyclohexylene dimethylterephthalates, Tynex® nylon filaments, Vespel® parts and shapes, Zenite® liquid crystal polymers and Zytel® nylon resins and Zytel® HTN high-performance polyamides. These products serve global markets in the aerospace, appliance, automotive, consumer, electrical, electronic, healthcare, industrial, sporting goods and many other diversified industries.
DuPont is a science company. Founded in 1802, DuPont puts science to work by creating sustainable solutions essential to a better, safer, healthier life for people everywhere. Operating in more than 70 countries, DuPont offers a wide range of innovative products and services for markets including agriculture, nutrition, electronics, communications, safety and protection, home and construction, transportation and apparel.
