US Patent 7204179 Shear assembly for a roll forming machine

A shear assembly for a roll forming machine which forms a rain gutter. A pair of coplanar blade members separated along a vertical line are caused to first move vertically downwardly, then have their lower ends pivot outwardly and, finally, have their upper ends pivot outwardly. The last motion is accomplished with enhanced mechanical advantage to cut through multiple layers of metal at the upper end of the gutter.