| 摘要 |
PURPOSE:To form the zinc coated Al tube without seams by extruding an Al strand from an extrusion die while heating the strand with a heater provided to the front end of a continuous molding machine and thermally spraying zinc powder to the outer periphery thereof. CONSTITUTION:The die 6 for extrusion is combined with a die body 11, a die ring 12 and a backer 13 and is mounted with the heater 14 between the die body 11 and the die ring 12 to extrude the Al stock after the temp. of the die body 11 is adjusted. A gaseous nitrogen blowing pipe 25 is mounted to the die body 11 to flow gaseous nitrogen under a prescribed pressure into the die body 11 from the outside part of the die. The zinc powder is thereafter thermally sprayed onto the outer periphery of this Al tube to provide a Zn coating layer having a Zn diffused layer, by which the zinc coated Al tube for a heat exchanger is obtd. |
