| 摘要 |
<p>The apparatus is for fitting of end covers to sheet metal ducts with U shaped folds, the so-called Pittsburgh fold, to receive the folded edge of the cover. To ensure easy assembly, the gap in the folded end of the duct is enlarged by use of a special machine. The machine has two rollers (17)(20) mounted on parallel shafts (16)(19) and rotated in opposite directions by an electric motor (10). The circular duct is placed over the roller (20) and the folded end is forced over a wedge-shaped tool mounted on the support (24). As the rollers (17)(20) rotate the tool opens the gap in the folds around the entire circumference.</p> |
