Hairpin bending of flat oval tubes - the solution for the recyclable all-aluminium heat exchanger. part II

摘要

A new bending/twisting method, which makes it possible to bend Flat Oval Tubes into hairpins, has been developed, making it possible to manufacture aluminium heat exchangers requiring only one water tank. This offers a cost-effective solution. The hairpin manufacturing method involves bending and twisting operations, which can be performed separately or in combination. A resilient and flexible mandrel material is inserted into the Flat Oval Tube to prevent collapse of the tube. Bending takes placeover a tool, which closely conforms to the outside of the Flat Oval Tube. In the twisting operation, the Flat Oval Tube is held between clamps which conform to the curvature of the final twisted tube profile. The flexible mandrel material is readilyremoved from the tube bore after the forming operation by simply pulling - and the mandrel material can then be reused.