Sheet metal door frame and a method for installing the same in a doorway

DETAILED DESCRIPTION In accordance with the present invention these and other objects have been achieved by means of a sheet metal door frame comprising a substantially horizontally arranged U-shaped head piece and a pair of substantially vertically arranged likewise U-shaped jambs, square-cut ends of which jambs extend into cut-outs at opposite ends of said head piece, said head piece and jambs presenting side walls, each of which terminates in a free longitudinal end at which an outwardly bent flange is provided for attachment of architraves, said head piece further presenting hook-shaped end portions formed in its side walls at said opposite ends, which hook-shaped end portions are arranged to overlap end portions of the corresponding side walls of the jambs so as to engage the outwardly bent flanges of the jambs.
In accordance with one embodiment of the door frame of the present invention, the hook-shaped end portions are arranged to engage substantially horizontal edge surfaces of said flanges.
In accordance with another embodiment of the present invention, the edge surfaces are located in a plane defined by the square-cut ends of the jambs.
In accordance with yet another embodiment of the present invention, the hook-shaped end portions are arranged to pass through slit-shaped openings in the flanges adjacent to the square-cut ends of the jambs.
Further in a preferred embodiment, the side walls of at least the head piece are slightly inwardly inclined toward their free longitudinal ends.
A clamping effect is hereby created, thereby facilitating the installation of the door frame in a doorway.
The angle of inclination of the side walls may favorably be within the interval 0.
5.
degree.
to 6.
degree.
, preferably 4.
degree.
.
Furthermore, in the preferred embodiment the side walls of the jambs are each provided with a screw hole at a predetermined location relative to the square-cut ends, said screw hole being aligned with a corresponding screw hole in the overlapping side wall of the head piece