Slip-on corner protectors for picture frames and machine and method of making same

摘要

A slip-on corner protector for rectangular picture frames includes a flat cardboard pre-form which is bent into the shape of a hollow prism having right triangularly-shaped front and rear frame face cover panels joined at vertical and horizontal sides thereof by a vertical and horizontal rectangularly-shaped frame edge cover panel, respectively. Triangularly-shaped spring flaps bent inwardly from hypotenuse edges of the front and rear triangular panels are pressed against and thus grip a frame inserted between the front and rear triangular panels because of the elasticity of the cardboard pre-form. A machine and method for manufacturing corner protectors from a stack of pred-forms bends panels perpendicularly upwards from a pre-form by linear actuators, spays a hot melt adhesive blob onto an upright panel, and presses it against another upright panel to form an adhesive bond.