| 摘要 |
A stiffener has an elongate web element and at least one elongate foot element, the web element and foot element being connected by a curved elbow, wherein the radius of the curved elbow is greater over a first portion of the stiffener than over a second portion of the stiffener. A roll forming die comprises first and second rollers, the first roller having a shaped section arranged to be located within a correspondingly shaped recess in the circumferential surface of the second roller, the first and second rollers defining a gap there between corresponding to the desired shape to be imparted on an elongate member passed between the rollers, the desired shape including a curved elbow between a web and a foot portion, wherein the shape of the recess in the second roller and the shape of the corresponding section of the first roller vary around a portion of the rollers circumference such that the radius of curvature of the gap between the rollers corresponding to the curved elbow varies between a minimum and a maximum value. The stiffener is formed by feeding an elongate member through the roll forming die and rotating the die rollers between a first and a second position as a portion of the elongate member is fed between the die rollers, whereby the radius of the curved elbow formed in the stiffener is varied. |
