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

Abstract: A sheet metal door frame (1) comprising a substantially U-­ shaped head piece (2), whose opposite ends (4, 5) are cut out to accommodate a likewise U-shaped pair of square-cut jambs (3). The side walls (10) of the head piece and jambs are provided at their free longitudinal ends (11) with outwardly bent flanges (12) for attachment of architraves (14). The invention relates specifically to that the head piece (2) is provided at its opposite ends (4, 5) with hook-shaped end portions (20) formed in the side walls (10) and arranged to overlap the end portions (21) of the corresponding side walls (10) of the jambs (3) and to engage the outwardly bent flanges (12) of the jambs (3). The hook-shaped end portions (20) are more particularly arranged to engage substantially horizontal edge surfaces (23) of said flanges (12). The invention also provides a method for installing the door frame (1) in a doorway, wherein one of the jambs (3), preferably the one fitted with hinges (18), is initially installed and secured in the doorway, whereafter the head piece (2) is clamped to the doorway lintel (37) in such a way that the hook-shaped end portions (20) of said head piece (2) are angled into engagement with said outwardly bent flanges (12) of the jamb (3). The remaining jamb (3) is thereafter angled into engagement with the hook-shaped end portions (20) of the head piece (2). The frame (1) may thus be adjusted relative to the initially installed jamb (3) and secured in a known manner by fastening means, preferably comprising screws (6, 33). Finally the architraves (14) are attached to the outwardly bent flanges (12).

Description: Technical field The present invention relates to a sheet metal door frame of the type comprising a substantially U-shaped head piece, whose opposite ends are cut out to accommodate a likewise U-shaped pair of square-cut jambs, the side walls of the head piece and jambs being provided at their free longitudinal ends with outwardly bent flanges for attachment of architraves. Background and object of the invention Sheet metal door frames offer a simple and highly cost effective alternative to conventional wood frames, and are often installed in doorways of plasterboard walls in offices and similar environments. The state of the art in the market today, is represented by a great number of more or less complicated frame constructions, where head piece and jambs are joined together by means of a vast variety of tongue elements and slits (WO-A-8806670). The tongue elements can for instance be of the kind used in tinplate toys where the tongue is guided through the slit and bent down on the rear side of the plate. The tongue elements are normally either stamped out from the frame profile, or added by welding or other means as separate parts to the frame profiles. Other known solutions may include intricate angled joint pieces onto which the head piece and jambs are fastened. A drawback of the majority of the above-mentioned solutions is that the frames become difficult to install on-site by the craftsmen. Especially since it is highly desirable that the frame may be easily installed even by an unskilled craftsman. An additional and no less important drawback of existing frame constructions is the complicated shape of the metal profiles, resulting in high manufacturing costs, for example in terms of expensive cutting and stamping machinery, as well as an increased number of necessary work operations. Yet another problem is that the craftsmen often has to hold the head piece in position - or fasten it by screws until the jambs are fixed in their vertical positions. It is thus the object of the present invention to alleviate the above problems by providing a cheap and simple sheet metal door frame, which can easily be installed in a doorway even by unskilled craftsmen. The solution In order to achieve the above object, the present invention provides a sheet metal door frame comprising a substantially U-shaped head piece, whose opposite ends are cut out to accommodate a likewise U-shaped pair of square-cut jambs. The side walls of the head piece and jambs are hereby provided at their free longitudinal ends with outwardly bent flanges for attachment of architraves. The invention relates specifically to that the head piece is provided at its opposite ends with hook-shaped end portions formed in the side walls and arranged to overlap the end portions of the corresponding side walls of the jambs and to engage the outwardly bent flanges of the jambs. The hook-shaped end portions are favorably arranged to engage substantially horizontal edge surfaces of said flanges. In a preferred embodiment, said edge surfaces are located in a plane defined by the square-cut ends of the jambs. In another embodiment, said edge surfaces define the bottom sides of slit-shaped openings in the flanges, adjacent to the square-cut ends of the jambs. Further in the preferred embodiment, the side walls of at least the head piece are slightly inwardly inclined toward their free longitudinal ends. Hereby is created a clamping effect 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° to 6°, preferably 4°. 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 perfectly aligned with a corresponding screw hole in the overlapping side wall of the head piece. The invention also provides a method for installing in a doorway the sheet metal door frame as described hereinabove. The method relates specifically to that one of the jambs, preferably the one fitted with hinges, is initially installed and secured in the doorway, whereafter the head piece is clamped to the doorway lintel in such a way that the hook-shaped end portions of said head piece are angled into engagement with said outwardly bent flanges 12 of the jamb. The remaining jamb is thereafter angled into engagement with the hook-shaped end portions of the head piece. Thus, the frame 1 can be adjusted relative to the initially installed jamb and secured in a known manner by fastening means, preferably comprising screws. After this, the architraves are attached to the outwardly bent flanges. Brief description of the drawings The invention will hereinafter be described by way of example only with reference to the accompanying drawings, in which Fig. 1 is a view of a door frame according to the invention, installed in a doorway, the architraves being partially cut away for the sake of clarity. Fig. 2 shows a broken side view of an edge joint of the frame. Fig. 3 shows a sectional view of the head piece, illustrating the basic profile shape of the frame. Fig. 4 shows a perspective view of an edge joint according to the invention, where the head piece and jambs are cut short for the sake of clarity. Fig. 5 shows a fragmentary perspective view of an alternative embodiment of the hook-shaped end portions according to the invention. Description of preferred embodiments Referring in detail to the drawings, reference numeral 1 denotes the preferred embodiment of a sheet metal door frame according to the invention. In fig. 1, the door frame 1 is seen to include a head piece 2 extending horizontally across the top of the doorway and interconnecting at opposite ends 4 and 5 thereof with vertically extending jambs 3, the ends 7 and 8 of which are square-cut. Additionally, a treshold 13 extends in the floor level between the two jambs 3. The head piece 2 and jambs 3 are substantially U-shaped in cross section, having a centrally extending depressed portion, likewise U-shaped in cross section, forming a door stop portion 9 which is clearly shown in fig. 3. Furthermore, the head piece 2 and jambs 3 each exhibit two opposite side walls 10, provided at their free longitudinal ends 11 with outwardly bent flanges 12 for attachment of architraves 14. The architraves 14 may suitably be of simple rectangular shape having a longitudinal slit 15 corresponding to the outwardly bent flanges 12, whereby said architraves 14 are simply snapped or otherwise attached onto the flanges 12 in a well known manner. The flanges 12 of the head piece are drawn back a distance from the opposite ends 4, 5, thus allowing joining architraves to meet in either a straight or mitered joint in a well understood manner. Since the jambs exhibit square-cut ends 7, 8, and since door fittings like a striking plate 17 and hinges 18 (fig. 1) are located symmetrically relative to the longitudinal mid-section of the jambs 3, the door frame 1 is fully adaptable to any of the possible four hanging positions of the door leaf (not shown in the figure). As can be seen in fig. 2 and 4, the opposite ends 4, 5 of the head piece 2 are cut out to accommodate the jambs 3. In order for the head piece 2 to interconnect with the jambs 3, it is provided at its opposite ends 4, 5 with hook-shaped end portions 20 formed in the side walls 10. Said hook-shaped end portions 20 are arranged to overlap the end portions 21 of the corresponding side walls 10 of the jambs 3. The purpose of the hook-shaped end portions are hereby to engage the outwardly bent flanges 12 of the jambs 3. More particularly the hook-shaped end portions 20 are arranged to engage substantially horizontal edge surfaces 23 of said flanges 12. In the embodiment shown in fig. 1, 2 and 4, said edge surfaces 23 are located in a plane defined by the square-cut ends 7 of the jambs 3. In order to allow the jambs 3 to be angled into engagement with the hook-shaped end portions 20, said end portions 20 exhibit a number of angled faces 25, clearly illustrated in fig. 2. The dot-lined line 26 in fig. 2 indicates an alternative extension of such a face 25. When the head piece 2 and the joining jamb 3 are at right angles relative to each other, as shown in fig. 2 and 4, the edges 28 of the head piece 2, which follow the contour of the jamb, are in contact with the perpendicular faces of corresponding parts of the jamb 3. Further in this position, a screw hole 30 in each side wall 12 of the jamb 3, at a predetermined location relative to the square-cut ends 7, is in perfect alignment with a corresponding screw hole 31 in the overlapping side wall 12 of the head piece 2. Hence, the frame 1 can be secured in this perpendicular position with for instance screws 33 through the aligned screw holes 30 and 31 (a screw 33 is shown in fig. 2, whereas said screws have been left out in fig. 4 and 5 for the sake of clarity). Another embodiment of the invention is shown in fig. 5, where the hook-shaped end portions 20 are formed to be inserted in slit-shaped openings 35 cut out in the outwardly bent flanges 12, adjacent to the square-cut ends 7 of the jambs 3. The edge surfaces 23 with which the hook-shaped end portions 20 engage, hereby define the bottom sides of said slit-shaped openings 35. In order to greatly facilitate the installation of the door frame 1 in a doorway, the side walls 10 of the head piece 2 and jambs 3 are slightly inwardly inclined toward their free longitudinal ends 11. In this way, a clamping effect is created by means of which the craftsmen may quickly carry out a rough positioning of for instance the head piece 2 by clamping it to the door way lintel 37 (see fig. 1). The inclination angle α of the side walls 10 may favourably be within the interval 0,5° to 6°. It can easily be understood that the clamping effect is more useful on the head piece 2 than on the jambs 3, since the head piece 2 without the clamping effect would have to be held in position by hand prior to final fastening by screws and the like. Thus, the inclination angle α of the head piece 2 is preferably 4° and said inclination angle α for the jambs 3 may be about 1° or none at all. A method for installing the door frame 1 in a doorway will be described hereinbelow. Upon installing the door frame 1, one of the jambs 3, preferably the one fitted with hinges 18, is initially installed and secured in the doorway. When said jamb 3 is secured in its final vertical position, the head piece 2 is clamped to the doorway lintel 37 in such a way that the hook-shaped end portions 20 of said head piece 2 are angled into engagement with said outwardly bent flanges 12 of the jamb 3. At this stage, the head piece 2 is only roughly fitted in its horizontal position. After this, the remaining jamb 3, which in this case is the one fitted with a striking plate 17, is angled into engagement with the hook-shaped end portions 20 of the head piece 2. The initial angled position of said jamb 3 is illustrated in Fig. 2 with dot-lined lines, as the jamb 3 is angled into its vertical position in the direction of the arrow 24. When the screw-holes 30 and 31 are in perfect alignment, the head piece 2 and the joining jamb 3 are at right angles to each other. A favourable effect is achieved if the door leaf (not shown in the figures) is hung on the hinges 18 of the initially installed jamb 3. In this way, the door leaf serves as a guide for final adjustment of the head piece 2 and the remaining jamb 3, which are then finally secured in a known manner by fastening means, preferably comprising screws 6, 33. The final adjustment of the frame 1 is thus carried out relative to the initially installed jamb 3. When installing the jamb 3 fitted with the hinges 18, said jamb 3 may favourably be fitted as closely as possible to the doorway, thus providing maximum space between the opposite, remaining jamb 3 and the doorway. This is highly desirable since the striking plate 17 in fact extends to some extent inwards toward the doorway. Finally, the architraves 14 are snapped or otherwise attached to the outwardly bent flanges 12. An additional help in positioning the frame 1 in the doorway is obtained by the fitting of the treshold 13 between the two jambs 3. Another possible method for installing the door frame 1 in a doorway is to initially clamp the head piece 2 to the doorway lintel 37, whereafter the jambs 3 are angled into engagement with the hooked-shaped end portions 20 of the head piece 2. The sheet metal door frame of the present invention can now clearly be seen to achieve the object of the invention and to be well adapted to meet conditions of practical use. The invention is not limited to the embodiments described and illustrated hereinabove. Thus it is realized that different embodiments of the invention may be varied within the scope of the accompanying claims. The above-mentioned fastening means may thus for example be nails instead of screws.

Claims: A sheet metal door frame (1) comprising a substantially U-shaped head piece (2), whose opposite ends (4, 5) are cut out to accommodate a likewise U-shaped pair of square-cut jambs (3), the side walls (10) of the head piece and jambs being provided at their free longitudinal ends (11) with outwardly bent flanges (12) for attachment of architraves (14), characterized in that the head piece (2) is provided at its opposite ends (4, 5) with hook-shaped end portions (20) formed in the side walls (10) and arranged to overlap the end portions (21) of the corresponding side walls (10) of the jambs (3) and to engage the outwardly bent flanges (12) of the jambs (3). A sheet metal door frame (1) according to claim 1, characterized in that the hook-shaped end portions (20) are arranged to engage substantially horizontal edge surfaces (23) of said flanges (12). A sheet metal door frame (1) according to claim 1 and 2, characterized in that said edge surfaces (23) are located in a plane defined by the square-cut ends (7) of the jambs (3). A sheet metal door frame (1) according to claim 1 and 2, characterized in that said edge surfaces (23) define the bottom sides of slit-shaped openings (35) in the flanges (12), adjacent to the square-cut ends (7) of the jambs (3). A sheet metal door frame (1) according to any of the preceeding claims, characterized in that the side walls (10) of at least the head piece (2) are slightly inwardly inclined toward their free longitudinal ends (11), creating a clamping effect facilitating the installation of the door frame (1) in a doorway. A sheet metal door frame (1) according to claim 5, characterized in that the inclination angle (α) of the side walls (10) is within the interval 0,5° to 6°, preferably 4°. A sheet metal door frame (1) according to any of the preceeding claims, characterized in that the side walls (11) of the jambs (3) each are provided with a screw hole (30) at a predetermined location relative to the square-cut ends (7), said screw hole (30) being perfectly aligned with a corresponding screw hole (31) in the overlapping side wall (10) of the head piece (2). A method for installing in a doorway a sheet metal door frame (1), said door frame (1) comprising a substantially U-shaped head piece (2), whose opposite ends (4, 5) are cut out to accommodate a likewise U-shaped pair of square-cut jambs (3), the side walls (10) of the head piece and jambs being provided at their free longitudinal ends (11) with outwardly bent flanges (12) for attachment of architraves (14), characterized in that one of the jambs (3), preferably the one fitted with hinges (18), is initially installed and secured in the doorway, whereafter the head piece (2) is clamped to the doorway lintel (37), in such a way that hook-shaped end portions (20) of said head piece (2) are angled into engagement with said outwardly bent flanges (12) of the jamb (3), and the remaining jamb (3) is thereafter angled into engagement with the hook-shaped end portions (20) of the head piece (2), the frame (1) thus being adjusted relative to the initially installed jamb (3) and secured in a known manner by fastening means, preferably comprising screws (6, 33), whereafter the architraves (14) are attached to the outwardly bent flanges (12).

Inventors: DUBOIS STEFAN, DUBOIS, STEFAN
Applicants: LINDAB PLATISOL AB, SWEDOOR AB
Application year: 1989
Main classification: E06B3
IPC codes: E06B3, E06B1