Method of making a heat exchanger

Abstract

A method of making a heat exchanger of the type used in vehicle radiators and having a core of spaced welded, as contrasted to lock-seam, tubes and interconnecting fins connected to spaced liquid tanks. The method, which permits machine-operated mass production of these exchangers, comprises stacking solder-coated core tubes in vertically spaced sets of a plurality of essentially horizontal tubes with serpentine fins located between each vertical pair of tube sets, arranging a top and a bottom rigid support plate against each of the topmost and bottommost tube sets, applying compression to the resulting stack through the support plates, banding the stack into an easily handled rigid assembly, applying a header plate to each essentially vertical side of the assembly with the tube ends extending through corresponding holes in the header plates, gang welding the projecting ends of the tubes to the exterior of the respective header plates by means of a movable multihead automatic welder, dipping this core assembly into a liquid soldering flux dip, blowing heated air at a temperature above the melting point of the solder over the outer surfaces of the core assembly to bond the fins to the tubes, applying a solder sealant coating over the adjacent junction areas of tubes and header plates that are opposite to the welds, the welds thereby being on the liquid side and the solder on the air side and finally removing the support plates and bands from the core and attaching the enclosing tanks to the header plates in fluid tight relation.

I 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 .Iadd.having tube ends .Iaddend.with said tube ends extending through corresponding holes in the header plates;   (f) gang welding .[.said.]. .Iadd.the .Iaddend.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.]. .Iadd.the .Iaddend.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.   
     
     
       2. The method of claim 1 wherein each .[.said.]. .Iadd.of the .Iaddend.tube receiving .[.hole.]. .Iadd.holes .Iaddend.in the header plates is defined by an outwardly projecting flange relative to said core that overlies the projecting ends of the tubes. 
     
     
       3. The method of claim 2 wherein each flange and corresponding tube end have substantially coplanar end surfaces with the welds being essentially located at the coplanar ends. 
     
     
       4. The method of claim 1 wherein said core tubes are arranged in spaced sets with the serpentine fins inserted between each adjacent pair of tube sets, said sets being generally parallel to each other and generally perpendicular to the header plates. 
     
     
       5. The method of claim 1 wherein said compression that is applied to the said stack is sufficient to retain the contacting surfaces of support plates, tubes and fins in intimate contact with each other throughout steps (a)-(j) of said making of the heat exchanger, said intimate contact being maintained by said taut tie bands. 
     
     
       6. The method of claim 1 wherein said assembly is held in position with the one ends of tubes projecting upwardly during the welding of the one set of tube ends of the header flanges and the assembly is then rotated to arrange the other ends of the tubes upwardly for the welding of these ends to their header plate. .[.7. The method of claim 1 wherein said solder 
     
     
        mixture is blown along the air side of each header..]. 8. The method of claim 1 wherein said stacking of the tubes, serpentine fin spacers and end support plates is in an assembly fixture having confronting surfaces intersected by vertically spaced grooves in which the ends of the sets of tubes are held and between whose confronting surfaces the fin spacers are 
     
     
        located. .Iadd.9.  The method of claim 1 wherein steps (a)-(l), inclusive, 
     
     
        are performed sequentially in the sequence listed. .Iaddend. .Iadd.10.  In making a weldment heat exchanger having an air side core of spaced tubes and interconntecting fins extending between liquid tanks, the method comprising: (a) stacking a plurality of solder-coated tubes in a plurality of spaced sets with fins arranged between each adjacent pair of tube sets;   (b) arranging rigid end supports against the stack;   (c) applying compression to the resulting stack through said supports, the tubes having substantially coplanar ends projecting beyond the sides of the stack;   (d) securing said stack in an easily handled rigid assembly;   (e) applying a header plate to each side of the assembly having tube ends with said tube ends extending through corresponding holes in the header plates;   (f) gang welding the projecting ends to the exterior of said header plates by relatively moving said stack and a multi-head, automatic welder;   (g) applying a soldering flux to the resulting core assembly;   (h) applying heat 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) applying solder over the adjacent junction areas of the tubes and header plates that are opposite to the location of the welds, the welds thereby being on the liquid side of the heat exchanger and the solder on the air side;   (j) heating said adjacent areas of the tubes and header plates to melt said solder 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 supports from said core; and   (l) attaching a tube enclosing liquid tank to each of said header plates in   
     
     
        fluid tight relation. .Iaddend. .Iadd.11.  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 a plurality of solder-coated tubes in a plurlity of spaced sets with fins arranged between each adjacent pair of tube sets;   (b) arranging rigid end supports against the stack;   (c) applying compression to the resulting stack through said supports, the tubes having substantially coplanar ends projecting beyond the sides of the stack;   (d) securing said stack in an easily handled rigid assembly;   (e) applying a header plate to each side of the assembly having tube ends with said tube ends extending through corresponding holes in the header plates;   (f) gang welding the projecting ends to the exterior of said header plates by relatively moving said stack and a multi-end, automatic welder;   (g) applying a soldering flux to the resulting core assembly;   (h) applying heat 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) applying a sealant over the adjacent junction areas of the tubes and header plates that are opposite to the location of the welds, the welds thereby being on the liquid side of the heat exchanger and the sealant on the air side;   (j) causing the sealant to substantially solidify to seal the air side of the welds at said adjacent areas against any leakage openings that may occur in the welds;   (k) removing said end supports from said core; and   (l) attaching a tube enclosing liquid tank to each of said header plates in   
     
     
        fluid tight relation. .Iaddend. .Iadd.12.  The method of claim 11 wherein said sealant is a solder and step (j) is performed by first melting the solder to thereby coat the adjacent areas of the tubes and header plates and thereafter allowing the solder to cool below its melting point. .Iaddend. .Iadd.13. The method of claim 11 wherein steps (a-(l), 
     
     
        inclusive, are performed sequentially. .Iaddend. .Iadd.14.  In making a vehicular radiator having an air side core of spaced tubes and interconnecting fins extending between liquid tanks, the method comprising: (a) stacking a plurality of tubes in a plurality of spaced sets with fins arranged between each adjacent pair of tube sets;   (b) arranging rigid end supports against the stack;   (c) applying compression to the resulting stack through said supports, the tubes having substantially coplanar ends projecting beyond the sides of the stack;   (d) securing said stack in an easily handled rigid assembly;   (e) applying a header plant to each side of the assembly having tube ends with said tube ends extending through corresponding holes in the header plates;   (f) fusing the projecting ends to the exterior of said header plates by heating at least the junction areas of said tubes and said header plates to form a strong tube to header joint;   (g) bonding the fins and tubes together;   (h) applying a sealant over the adjacent junction areas of the tubes and header plates that are opposite to the location of said fused ends, the fused ends thereby being on the liquid side of the radiator and the sealant on the air side;   (i) causing the sealant to substantially solidify to seal the air side of the fused ends at said adjacent areas against any leakage openings that may occur in the fused ends;   (j) removing said end supports from said core; and   (k) attaching a tube enclosing liquid tank to each of said header plates in   
     
     
        fluid tight relation. .Iaddend. .Iadd.15.  The method of claim 14 wherein step (g) is performed after step (f). .Iaddend. .Iadd.16. The method of claim 14 wherein step (i) provides a secondary, relatively weak tube to 
     
     
        header joint. .Iaddend. .Iadd.17.  In making a radiator for a vehicle having a core of spaced tubes and interconnecting fins extending between liquid tanks, the method comprising: (a) stacking a plurality of solder-coated tubes in a plurality of spaced sets with fins arranged between each adjacent pair of tube sets to provide a stack;   (b) arranging end supports against the stack;   (c) applying compression to the stack through said supports, the tubes having substantially coplanar ends projecting beyond the sides of the stack;   (d) securing said stack in an easily handled rigid assembly;   (e) spplying a header plate to each side of the assembly having tube ends with said header plate having a plurality of holes, said tube ends extending through said holes;   (f) welding said tube ends to the header plates with some or all of said welds being prone to defects to provide a core assembly;   (g) applying a soldering flux to said core assembly;   (h) applying heat 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) contacting the adjacent junction areas of the tube ends and header plates with a melted solder having excellent capillary flow properties so that the solder with its excellent capillary flow properties fills defects in the welds to provide a leak-tight structure;   (j) removing said end supports from said core; and   (k) attaching a tube enclosing liquid tank to each of said header plates in   
     
     
        fluid tight relation. .Iaddend. .Iadd.18.  The method of claim 17 wherein said radiator has an air side and a liquid side and step (i) is performed over said junction areas on the air side. .Iaddend. .Iadd.19. In making a radiator for a vehicle having a core of spaced tubes and interconnecting fins extending between liquid tanks, the method comprising: (a) stacking a plurality of tubes in a plurality of spaced sets of fins arranged between each adjacent pair of tube sets to form a stack;   (b) arranging the tube sets so that the tubes have substantially coplanar ends projecting beyond the sides of the stack;   (c) applying a header plate having a plurality of holes to each side of the assembly having tube ends so that said tube ends extend through respective ones of said holes;   (d) welding said tube ends to the header plates with some or all of said welds being prone to defects;   (e) bonding the fins and tubes together;   (f) contacting the adjacent junction areas of the tube ends and header plates with a sealant having excellent capillary flow properties so that the sealant with its excellent capillary flow properties fills defects in the welds to provide a leak-tight structure; and   (g) attaching a tube enclosing liquid tank to each of said header plates in   
     
     
        fluid tight relation. .Iaddend. .Iadd.20.  The method of clain 19 wherein said radiator has an air side and a liquid side and step (f) is performed over said adjacent junction areas on the air side. .Iaddend. .Iadd.21. The method of claim 19 wherein end supports are arranged against the stack and compression is applied to the stack through said supports prior to step (c). .Iaddend. .Iadd.22. The method of claim 19 wherein the tubes are solder-coated and a soldering flux is applied to the core prior to step (e) and heat is applied at a temperature above the melting point of the 
     
     
        solder to bond the fins and tubes together. .Iaddend. .Iadd.23.  In making a radiator for a vehicle having a core of spaced tubes and interconnecting fins extending between liquid tanks, the method comprising: a. stacking a plurality of tubes in a plurality of spaced sets with fins arranged between each adjacent pair of tube sets to form a stack;   b. arranging the tube sets so that the tube ends project beyond the sides of the stack;   c. applying a header plate having a plurality of holes to each side of the assembly having tube ends so that said tube ends extend through respective ones of said holes;   d. fusing said tube ends to the header plate with some or all of the fusions being prone to defects;   e. bonding the fins and tubes together;   f. applying a sealant having excellent capillary flow properties over the adjacent junction areas of the tube ends and header plates to seal and fill the defects in said fusions; and   g. attaching a tube enclosing liquid tank to each of said header plates and fluid type relation. .Iaddend.