| 摘要 |
PURPOSE:To obtain an aluminum pipe having a pitting-corrosion resisting property against copper or chlorine ion, by jetting zinc powder or zinc vapor into an aluminium blank pipe during forming by an extruder, and performing a heat teatment of the extruded pipe after forming a zinc layer onto the inner surface of the pipe. CONSTITUTION:A billet 10 of aluminum alloy heated to about 450 deg.C is pressed in a container 11 by a stem 12 and is extruded from an exit of a die 1 to be formed into an aluminum blank pipe 8. During this extrusion forming, powder or vapor of zinc 3 is jetted in a form of mist 6 having a doughnut-type cross section, from a nozzle 5 attached to the male-type end part 4 of the die 1 through a die slide 13, a die ring 14, and a hole 2 bored in the die 1, to form a zinc layer on the inner surface of the pipe and further, to diffuse the zinc into the inside of the pipe by keeping the temp. of an extruded pipe at about 520 deg.C for roughly 45min. thereby obtaining an aluminum pipe endowed with a sacrificial anode characteristic having an electrode potential difference. |
