Abstract: A heat transfer cell for employment in heating, ventilation and air conditioning applications, and an apparatus for producing metallic plates which can be employed in the construction of the heat transfer cell. The cell comprises a plurality of heat conductive plates stacked on each other and having upstanding fins extending substantially the length of each plate. A leading edge portion of each fin is folded laterally to thereby create a turbulent effect to air traveling linearly between adjacent fins and plates.

Abstract: Apparatus for forming fins along a web of metallic material utilizing first and second opposed endless chains, and with the first chain adapted to support the web of metallic material thereon, and comprising a plurality of spaced-apart anvil links. The upper chain includes a plurality of spaced-apart links operating in registry with the base chain and including work-engaging, fin-forming lugs which enter the gap between mutually adjacent anvil links. The apparatus further includes a chain-deflecting idler roll which deflects the base chain arcuately away from its normal plane so as to effectively reduce the spacing between adjacent anvil links and create a web back-breaking zone for achieving a firm and solid crimping of that portion of the web forced thereinto by the fin-forming lugs.