| 摘要 |
<p>The rim (1) has inner and outer rim bottom parts (2, 4) and two side piece walls (6, 8) formed from a material and forming a hollow chamber wall (10). Areas of the outer rim bottom and the side piece walls are implemented as a two-layered structure. A layer (12) made of the material is formed at an inner side of the wall. Another layer (14) e.g. self-supporting cover, is formed from another material i.e. lighter material than the former material. The hollow chamber wall has a perforation (16) in the former layer in which the former material is removed.</p> |
