Expanding mandrel, expanding method and expanding apparatus using the expanding mandrel and heat exchanger with heat exchanging tubes expanded by the expanding method

摘要

An expanding mandrel (10) used mainly for expanding heat exchanging tubes (21) of a cross fin coil (20) of an air conditioning machine, so as to connect them to fins of the cross fin coil. The expanding mandrel has flexibilty, comprising a plurality of mandrel pieces (11) which are bandably connected in a row, with an expanding head (13) disposed at the leading end. By an expanding method and an expanding apparatus both using the mandrel (10), the mandrel (10) is wound on the winding drum (41); is fed from the winding drum (41) so as to be inserted into the heat exchanging tube (21) of the cross fin coil so as to be expanded at the time of tube expansion; and is retracted from the heat exchanging tube (21), after completion of the expanding, so as to be wound on the winding drum (41). This provides a decreased size of the apparatus and allows even an expansion of a heat exchanging tube which has been bend-processed.