Patent ID: 7415765
Filing Date: 2008-08-26
Classification: F16L,Y10T

Abstract:
1. A manufacturing method for a flange coupling, comprising the steps of: bending a pipe made of aluminum or aluminum alloy into an L shape with a radius of curvature that satisfies the condition of R≦1.0 D (R: radius of pipe median line, D: pipe diameter), said aluminum or aluminum alloy being at least one kind selected from a group of pure aluminum or aluminum alloy having soft properties and aluminum having elongating properties through being hard; placing the resultant L-shaped pipe in a pipe clamp mold and correcting the pipe end portion thereof to an angle of R≦0.5 D by pressing the vicinity of a pipe end portion with the use of a first molding tool which has a concave portion fitting the pipe end portion of said L-shaped pipe and has a lower end portion; fitting a pipe connection hole of a flange provided with an attaching bolt hole and the pipe connection hole, on said pipe end portion, and pressing said pipe against the inside wall of said pipe connection hole and expanding the pipe end portion projecting from said flange, with the use of a second molding tool which has a lower end portion with an outside diameter slightly larger than the inside diameter of the said pipe and has an expansion groove; and fitting said flange to the pipe end portion of the L-shaped pipe by pressing the expanded pipe end portion against said flange with the use of a third molding tool which has a molding groove and a step portion.