| 摘要 |
<p>A flexible duct with a frame made by winding a S-profiled hoop iron (7) into clamped turns, wherein the edges of two adjacent turns overlap each other in order to form between them a helical closed gap (20) having an essentially rectangular cross-section and at least partially filled by a helically-wound strut profile (30) separate from the hoop iron (7) and resting on at least two opposite walls of the lower surface (22b) and the upper surface (22a), wherein said strut profile (30) has, in the winding radial direction, a crush resistance substantially equal to zero and, in the winding longitudinal direction, a substantial crush resistance.</p> |
