Abstract: A method for safely cutting hollow bodies filled with metallic Na for disposal comprises the steps of cutting the hollow bodies with plasma jet so as to oxidize metallic Na while conveying said hollow bodies in a hermetically sealed housing, throwing the cut hollow bodies into a neutralizing aqueous solution tank, then taking out said cut hollow bodies from the tank, collecting a fume produced while cutting the hollow bodies, spraying water over the fume and recovering the fume. An apparatus for carrying out the above method is also disclosed.

Abstract: An apparatus, for forming fins for heat exchangers, comprising a pair of rolls which are provided, on the outer peripheral surfaces thereof, with grooves of a pattern corresponding to the shape of the fins to be formed therebetween and which form them by pressing the fins from opposite sides thereof with the aid of the synchronous rotation of the rolls to give smooth curved outer surfaces thereon, characterized in that the grooves on the rolls are formed so that each groove may be composed of a bottom portion having a substantially arcuate shape and a tapered portion converging from the outer peripheral surface toward the bottom portion of the roll as viewed in section, and at least one roll of the pair of rolls is provided with an urging means for pressing the aforesaid roll against the other roll at a constant pressure.