Patent ID: 7241473
Filing Date: 2007-07-10
Classification: D07B,E04C,Y10T

Abstract:
1. A method of forming corrosion protection double coatings on a prestressing strand, comprising: a pre-treatment process of untwisting the prestressing strand and thereby loosening surrounding wires from a core wire and performing a surface preparation of those wires; a primary painting process of tightening and retwisting the surrounding wires about the core wire, applying a synthetic resin powder paint to surface layer parts except helical groove parts due to the retwisting, heating the paint to adhere, and cooling, thereby forming a resin coating only at a surface layer; a secondary painting process of loosening the surrounding wires of the prestressing strand from the core wire, keeping the core wire and the surrounding wires under a loosened state via a core wire adjusting means, applying the synthetic resin powder paint to an outer peripheral face of each of the core wire and the surrounding wires, heating the paint to adhere evenly, and cooling, thereby forming a respectively individual state resin coating for each of the core wire and surrounding wires wherein the individual state resin coating of each of the surrounding wires includes a part constituting a double coating, said secondary painting process being performed after said primary painting process; and a finishing process of tightening and retwisting the surrounding wires about the core wire to an original state such that each of the double coating portions is located in the surface layer of the prestressing strand.