| 摘要 |
<p>Apparatus (20) and a corresponding method for forming from a strip of sheet metal stock material (22) a length of spiral duct (26) that includes an integral diffuser (28). A perforator (30) forms perforations (52) in the strip (22) at at least selected intervals. A machine (34) forms the strip, after performation, into spiral seamed duct (26).</p> |
