Abstract
Background & needs of this project
The light weight of the vehicle is a global issue, which is emerging as humanity's challenges and obligations to environmental protection. Therefore, the light weight of the vehicle has been studied in various aspects. Above all efforts to replace the conventional metal or non-ferrous metals, and the development of components in composite materials is currently underway. Recently, continuous glass-fiber composites which have the good stiffness and strength for weight reduction purposes is being applied to the various structures in industry. The rear bumper back-beam also can’t be an exception. The rear bumper Back Beam has the ability to minimize the vehicle body damage during parking and low-speed collisions. 2.5 MPH bumpers low speed crash test regulations are required worldwide and RCAR (Research Council for Automobile Repairs) crash test has been required by the NCAP. In this study, Injection Back Beam was developed by inserting CFT(Continuous glass Fiber Thermoplastic).
Composition of the technique
In general, RR(rear) bumper Back beam used to be divided into the rail area and the crash boxes region. RR Back beam rail and crash boxes made one part using inserting injection mold in the project. Rail part made from CFT for bending rigidity and c/box part made from TPO(Thermoplastic Polyolefin). TPO which is injection resin also covered to Rail part. The function of TPO in Back Beam is to secure the energy efficiency performance of crash box. Injection resin molded to complex shapes and covered the surface of main rail. CFT rail is inserted in the injection mold after a low-pressure compression molding to secure the rigidity.
Results
The intrusion of RCAR 10kph full bumper barrier test had 119mm (K5 car standard). The result satisfied in intrusion spec 137mm. In RCAR 15kph angle barrier test, c/box energy efficiency resulted 67% which is similar to steel crash box, but maximum deflection of c/box is more 10mm than steel c/box. It had no problem because of enough space of c/box and also reduced impact loads less 0.8ton than steel c/box. The bumper low speed test is also satisfied. This impact performance of tehcnoloy had the enhanced result than previous tech. In comparing to previous GMT and steel c/box beam tech, the cost of this technology reduced 15%, the weight reduced 8% and the parts number reduced 73%.
Conclusions
By using both the press molding and inserting injection molding, RR back beam had a free design molding ability. The performance of back beam was enhanced in comparing with GMT rail & steel c/box. Due to simple process and part number reduction, the cost of beam reduced. Finally, by utilizing CFT insert molding method recommend to apply the other parts of the vehicle which need high stiffness and strength
Key Words : Back Beam, CFT(Continuous glass Fiber thermoplastic), Impact, Bumper, RCAR, Injection, Weight-reduction