Method of making a heat exchanger

Claim 1

In making a weldment heat exchanger having an air side core of spaced tubes and interconnecting fins extending between liquid tanks, the method comprising: (a) stacking solder-coated welded core tubes in a plurality of spaced sets of a plurality of spaced tubes each with serpentine fins arranged between each adjacent pair of tube sets; (b) arranging end rigid support plates against each of the end tube sets to provide a stack; (c) applying compression to the resulting stack through said support plates, the tubes having substantially coplanar ends projecting beyond the sides of the stack; (d) banding said stack into an easily handled rigid assembly by applying a plurality of spaced, taut tie bands around the support plates and encircling said stack; (e) applying a header plate to each side of the assembly with said tube ends extending through corresponding holes in the header plates; (f) gang welding said projecting ends to the exterior of said header plates by means of a movable, multi-head, automatic welder; (g) dipping the resulting core assembly into a liquid soldering flux; (h) blowing heated air at a temperature above the melting point of said solder over the outer surfaces of said core assembly to bond the fins and tubes together; (i) blowing a flowing mixture of solder and flux over the adjacent junction areas of the tubes and header plates that are opposite to the location of said welds, the welds thereby being on the liquid side of the heat exchanger and the solder mixture on the air side; (j) heating said adjacent areas of the tubes and header plates to melt said solder mixture and thereby coat the said adjacent areas of the tubes and header plates with solder to seal the air side of the welds at said adjacent areas against any leakage opening that may occur in the welds; (k) removing said end support plates and spaced bands from said core; and (l) attaching a tube enclosing liquid tank to each of said header plates in fluid tight relation.