MULTI-WOUND METAL TUBE, MANUFACTURING METHOD AND APPARATUS THEREFOR

摘要

Means capable of manufacturing a high quality multiwound metal tube having satisfactory adhesion between multi-wound walls and for a seam portion at a reduced cost. Walls of the multi-wound tubular body are pressure welded with each other and then cooled, while at least the outer circumference of a brazing material between the walls of the multi-wound tubular body is kept at a flowable temperature by heating, by using at least one of a step of pressing substantially uniformly the outer circumferential surface of the tubular body in a radial direction from the outside, a step of substantially uniformly pressing the inner circumferential surface of the tubular body in the radial direction from the inside or a step of exerting a tensile force to the tubular body in the direction of the tubular axis.