Patent ID: 8037595

Claim:
In a hairpin expander machine ( 250 ) for the manufacture of tube and fin heat exchangers ( 10 ), said hairpin expander machine ( 250 ) having (a) a fixture ( 259 ) for holding a heat exchanger assembly, which includes a loose stack of fins ( 12 ′) disposed between top and bottom end plates ( 14 , 16 ) and at least one hairpin tube ( 22 ) laced through the stack of fins ( 12 ′) and the top and bottom end plates ( 14 , 16 ), (b) a first actuator ( 252 ) coupled between said fixture ( 259 ) and at least one rod ( 256 ) so as to forcefully drive said at least one rod ( 256 ) within said at least one hairpin tube ( 22 ) to enlarge the diameter of said at least one hairpin tube ( 22 ), and (c) a second actuator ( 274 ) coupled between said fixture ( 259 ) and a bolster plate ( 272 ) so as to support said at least one hairpin tube ( 22 ) at its bent end ( 23 ) during expansion, the improvement comprising: a base plate ( 165 ) having a recessed seat ( 166 ) formed therein for receiving said bottom end plate ( 16 ) of said heat exchanger assembly ( 10 ); first and second bridges ( 452 ) immovably fixed to said base plate ( 165 ) and defining first and second openings between said base plate ( 165 ) and said first and second bridges ( 452 ), respectively; and a retaining member ( 456 ) arranged to be received within said first and second openings and dimensioned so that when said bottom end plate ( 16 ) of said heat exchanger assembly ( 10 ) is seated in said recessed seat ( 166 ) of said base plate ( 165 ), said bottom end plate ( 16 ) cannot be removed from said recessed seat ( 166 ) while said retaining member ( 456 ) remains received within said first and second openings; wherein said retaining member ( 456 ) is slidingly receivable within said first and second openings.