Collapsible door-fitting frame

Claim 1

A door-fitting frame of collapsible type comprising right and left vertical frame component members of identical C-shaped convex steel consisting of flat-topped raised part formed longitudinally and centrally, a tiered flat part formed on both sides of the raised part, an inwardly extending edge formed at the outer edge of each said tiered part by bending the outer edge of said tiered part twice at right angles, a pair of opposed upturned hook or catch members provided on said raised part at a position close to the upper and lower ends of each vertical member, upper and lower horizontal component members of a shape similar to that of said vertical frame members, an indent formed at both ends of each said horizontal member by cutting off the end of its raised part, an end cover plate rigidly secured to the end surface of said indent, said cover plate carrying cut-outs to be engaged by said hook or catch members so that a rectangular frame may be fabricated by bringing both ends of each horizontal member into contact with the upper and lower ends of each vertical member and having the ends of the tiered part and bent edge of the horizontal member also in contact with the tiered parts of the vertical member, thereby causing the raised part of the vertical member to engage in the indent of the horizontal member and causing the hook means of the vertical member to engage in the cut-outs of the horizontal member, whereupon the vertical and horizontal frame members are firmly joined at their ends to form a rectangular frame.