| 摘要 |
PURPOSE:To both improve shock energy absorbing performance of a bumper and decrease its weight, by using a foamed plastic form consisting of polystyrene and polyethylene with composition ratio in a specific range. CONSTITUTION:A shock energy absorbing bumper 1 is constituted by a reinforcing back-up beam 2, provided with a protrusive base plate 3 in its central part, thin block-shaped shock energy absorbing form 4, arranged in front of the beam 2, and synthetic resin or synthetic rubber made outer skin 5, coating the form 4 further capable to follow up deforming motion of the form 4. Further for the form 4, there is applied a foamed plastic form, consisting of polystyrene and plyethylene with composition ratio of the former to the latter in 90/10-25/75pts.wt. and virtual specific gravity of 0.02-0.10g/cm<2>, in a range of 20% compression stress of 2- 10kg/cm<2> in a shock test at speed of 5miles/hr under normal temperature (23 deg.C), energy absorption efficiency not less than 63% and load recovery rate not less than 40%, and temperature magnification not more than 2.0 in a shock test at similar speed under low temperature (-20 deg.C) and high temperature (60 deg.C). |
