| 摘要 |
PURPOSE:To realize a frontal wall surface, on which no flaw develops and keep stress balance against loading by a method wherein hollow tubular rear wall surfaces, which are molded by blowing, are swollen out at proper intervals so as to form trapezoidal supports, the top of each of which comes close to the inside of the frontal wall surface, and each rib is stretched between the supports so as to connect the supports integrally with each other. CONSTITUTION:In a hollow tubular body l, which is molded by blowing, a proper number of trapezoidal supports, the top of each of which is brought close to the frontal wall surface 3, are swellingly provided on the rear wall surface 2. Further, each rib 5 is stretched between the supports 4 so as to connect the supports integrally with each other Accordingly, on the frontal wall surface 3, flaw, which may develop due to the sticking of the support 4 to the frontal wall surface, does not develop, resulting in enhancing the commercial value as a bumper. Furthermore, since the frontal wall surface 3 is supported by the supports 4, which are connected integrally through the ribs 5, the bumper is strong against loading applied from the front, resulting in remarkably reducing its possibility of breakage. |
