Abstract: The present invention relates to an apparatus for corrugating a web of sheet material in a continuous process by means of an elongated mold movable in an endless closed path and composed of plate elements disposed in a row the one behind the other and in one straight portion together constituting a forming table having preferably diagonally extending, mutually parallel, grooves.The plate elements are by means of journals supported on and mounted in driving members disposed on either side of the path and equipped with turning wheels, the individual plate elements following the driving members with the same side facing upwards during the whole trave along the closed path.The primary field of application of the product manufactured in the apparatus are corrugated sheet pieces intended to form the fill in contact or exchanger bodies for two fluids, of which one may be a liquid, such as water, and the other a gas, such as air.