Method for fabricating a seamless H.V.A.C. trunk line adaptor

Abstract

Method for fabricating seamless adaptor for connecting trunk line HVAC duct to branch conduit including steps of positioning first segment of strip of sheet metal at first die assembly and exerting force onto first segment forming elliptical shaped segment, punching hole into central portion of elliptical segment and providing connector strip between first and trailing segment of metal strip; positioning elliptical segment at second die assembly and at same time positioning trailing segment at first die assembly and exerting force onto first and trailing segments, drawing elliptical segment at second die assembly into form having generally cylindrical shape projecting transverse to surface of the elliptical segment and positioning hole to be generally centered within end of form and forming annular rim surrounding hole and bending portion of elliptical shaped segment surrounding another end of form forming flange having a camber; positioning form at third die assembly and at same time positioning trailing segment at second die assembly and exerting force onto first and trailing segments with third and second die assemblies respectively, increasing diameter of hole at third die assembly and leaving a portion of annular rim surrounding hole positioned at end and inside of form; finally, positioning first segment at fourth die assembly and at same time positioning trailing segment at third die assembly and exerting force onto first and trailing segments with fourth and third die assemblies respectively, pushing portion of rim outwardly from inside of form to further increase diameter of hole positioned at end of form.

Dependencies are inferred from the claim text.