Abstract: An elongated hollow rectangular spine or backplate formed of plastic material for supporting and securing ring hardware in a loose-leaf binder has spaced, parallel, front and back walls joined at the edges and a centrally disposed strengthening rib extending between the front and back walls longitudinally for the length of the back plate. The ring hardware is secured to the backplate by inserting circumferentially grooved metal rivets through apertures in the ring hardware, pressing into the backplate rib and sonically welding the rivet therein. The circumferential grooves on the rivet shank facilitate anchoring the rivets to the backplate rib.

Abstract: An elongated hollow rectangular spine or backplate formed of plastic material for supporting and securing ring hardware in a loose-leaf binder has spaced, parallel, front and back walls joined at the edges and a centrally disposed strengthening rib extending between the front and back walls longitudinally for the length of the backplate. The ring hardware is secured to the backplate by inserting plastic rivets through apertures in the ring hardware aligned with counterbored holes in the backplate rib and sonically welding the rivet therein. The rivets and counterbored holes of the backplate rib facilitate the welding operation.