Method of forming aluminium heat exchangers header tanks

Abstract

The invention relates to a method for producing a heat exchanger header tank comprising the steps of providing a tube having a core made from a AA3XXX-aluminium alloy; optionally pre-heating the tube; inserting the tube into a forming tool having a forming cavity with the shape of the final header tank; plugging the ends of the tube; internally pressurising the tube by the use of a gas so as to make it conform to the shape of the tool cavity, thus obtaining the final header tank; removing the header tank from the tool; and cooling the header tank. This method allows an efficient production of header tanks of irregular shapes made of AA3XXX aluminium alloy. The invention also relates to a method for producing a heat exchanger, where the header tank is connected to a plurality of tubes and corrugated fins inserted between the tubes, followed by brazing of the fins to the tubes.

1 . A method for producing a heat exchanger header tank comprising the steps of;
 a) providing a tube having a core made from a AA3XXX-aluminium alloy   b) optionally pre-heating the tube;   c) inserting the tube into a forming tool having a forming cavity with the shape of the final header tank;   d) plugging the ends of the tube;   e) heating the tube to the forming temperature if the tube has not been sufficiently pre-heated and internally pressurizing the tube by the use of a gas so as to make it conform to the shape of the tool cavity, thus obtaining the final header tank;   f) removing the header tank from the tool;   g) cooling the header tank.   
     
     
         2 . Method for producing a heat exchanger header tank according to  claim 1  in which the material used for the tube has not been homogenized. 
     
     
         3 . Method for producing a heat exchanger header tank according to  claim 1 , in which the tube has not been annealed. 
     
     
         4 . Method for producing a heat exchanger header tank according to  claim 2 , wherein the tube core has at least one cladding made from an aluminium alloy. 
     
     
         5 . Method for producing a heat exchanger header tank according to  claim 1 , where slots for tubes or connections are made in the shaped header tank, during forming, or subsequent to forming. 
     
     
         6 . Method for producing a heat exchanger header tank according to  claim 1 , wherein the gas pressure used is higher than 85 bar. 
     
     
         7 . Method for producing a heat exchanger header tank according to  claim 1 , wherein an axial pressure is applied to the tube ends during forming thereof. 
     
     
         8 . Method for producing a heat exchanger header tank according to  claim 1 , wherein threads or anchors are formed on the end of the tube during forming thereof. 
     
     
         9 . Method for producing a heat exchanger header tank according to  claim 1 , wherein a tube made from a welded blank is provided in step a). 
     
     
         10 . A heat exchanger header tank, which has been formed by the method of  claim 1 . 
     
     
         11 . A heat exchanger comprising the heat exchanger header tank of  claim 10 . 
     
     
         12 . The heat exchanger of  claim 11  being of non-rectangular shape. 
     
     
         13 . A method for producing a heat exchanger, comprising the steps of:
 producing a header tank by means of the method of  claim 1 ;   providing openings for flow tubes in the header tank,   connecting a plurality of flow tubes to the header tank at the openings;   inserting fins between the flow tubes; and   brazing the fins to the flow tubes.