Abstract: A device for corrugating a sheet material with forming staggered cut corrtions, comprising a mechanism 1 for feeding a sheet material 2 to at least two punches 3, 4. The punches 3, 4 are mounted for reciprocating motion on both sides of the material 2 in the plane perpendicular to the plane of the material 2 and over the surface of the material 2 at right angles to the direction of its feeding. The device is provided with dies 12, 13 disposed on both sides of the punches 3, 4 in the direction of feeding the material 2, with a clearance being not less than the thickness of the material 2. The dies 12, 13 are adapted to reciprocate relative to the punches 3, 4 at right angles to the plane of the material 2 such that in the process of forming the corrugations the punches 3, 4 are forced in the material 2 between the oppositely lying dies.

Abstract: A tube-and-fin heat exchanger comprising tubes (1) for the flow of a heat carrier at some temperature, said tubes being installed in broached holes (9) provided in a stack of fins (2,3). The tubes (1) are installed so that adjacent fins (2,3) form a multiplicity of ducts for the flow of another heat carrier at a different temperature. Each fins (2,3) is provided with projections (4) and depressions (5) which form in the ducts symmetrical divergent-convergent portions for setting up turbulence in the heat carrier flow layer at the wall. The fins (2 and 3) have rectilinear portions (8) located between the divergent-convergent portions and situated opposite each other on adjacent fins (2 and 3).