Heat exchanger

A process for the manufacture of a heat exchanger unit having a stack of metallic elements such as corrugated sheets, thin interposed plates, and edging rods, these elements presenting contacting surfaces flush with their faces and in certain instances recessed surfaces, the unit being provided on its sides with connecting metal sheets, consisting essentially of

• a. forming a thin deposit of a brazing composition only on the recessed surface of said elements;
• b. stacking said elements in an appropriate fashion on a lower press plate with which removable guide members are associated, these guide members being rigid and spaced apart to constitute a guiding form inside which said elements are positioned in a manner such that their edges are supported against said guide members, the edging rods coming to rest against at least two of said guide members to ensure the lateral and longitudinal guiding of said rods,
• c. placing an upper press plate on the stack and pressing the upper and lower press plates together by means of connecting tightening columns provided with tightening means in a manner such that said upper and lower press plates can later be removed,
• d. applying a limited tightening pressure on the press plates of (c) so as to stabilize the stack,
• e. removing the said guide members, and placing the entire stack under pressure,
• f. exerting on said press plates a pressure the value of which is such that the space between the two press plates will be reduced to a given dimension,
• g. locking the tightening means, then stopping the application of pressure on said press plates so as to obtain a compact stack which can be transported held together by said press plates which have a predetermined and constant distance between them,
• h. soldering or welding on the edge of the stack connecting and aligning sheets of metal,
• i. after said welding or soldering operation of (h), placing the whole assembly into a brazing oven, under conditions suitable to bring about the brazing of the contact surfaces of the elements of the stack, and
• j. unlocking the tightening means and removing said press plates and the tightening columns.