Patent ID: 8127583

Claim:
A mandrel for winding sheet metal, the mandrel comprising: a generally tubular mandrel body extending along and centered on an axis and formed at one end with a plurality of radially throughgoing and angularly spaced apertures each having a pair of closed and axially confronting end faces; a spreading bar extending axially inside the body and having a respective pivot adjacent each of the apertures; respective rigid links extending through the apertures and having inner ends carried on the respective pivots and outer ends projecting outside the body; respective segments outside the body and each pivoted on the outer end of a respective one of the links; respective pressure plates operatively connected at the one end between the segments and the mandrel body; and means for shifting the bar axially and thereby moving the links between one end position forming a predetermined acute angle with the axis and with the segments in inner positions relatively closely radially spaced to the axis and an opposite end position extending at a more perpendicular angle to the axis with the links bearing axially on one of the end faces of the respective aperture and the segments spaced outward of the respective inner positions.