| 摘要 |
<p>A flange for ductwork is integrally formed at a distal end of a duct surface. A first flange portion is formed perpendicularly outward from the duct surface. A second flange portion is bent at a right angle from the first flange portion and substantially parallel to the duct surface. A third flange portion is bent back to be in substantial touching relationship with the second flange portion and towards the first flange portion. A fourth flange portion is bent at a right angle from the third flange portion to be in substantial touching relationship with the first flange portion. Finally, a fifth flange portion is bent at a right angle from the fourth flange portion to be in substantial touching relationship with the duct surface.</p> |
