| 摘要 |
PROBLEM TO BE SOLVED: To provide an expanding mandrel for integrating radiation fins with tubes and expanding the integrated tube so that the tube is bent at a small bend radius after integrating the radiation fins with the tubes in order to maintain or improve the performance of a heat exchanger and miniaturize it. SOLUTION: This expanding mandrel is the expanding mandrel provided with billets for expanding the tubes penetrated through a plurality of the stacked radiating fins and the billets are constituted of a 1st billet having an outside diameter part larger than the inside diameter of the tube and a 2nd billet having the outside diameter part larger than that of the 1st billet. The 1st billet is provided on a more front end side than the 2nd billet in order to form a prescribed part where the bending of the tube is possible.
|
