FIELD OF INVENTION

[0001] The invention pertains, generally, to door frames and window frames; more particularly, door frames and window frames that can be installed in walls of varying thicknesses. BACKGROUND

[0002] Door frames and window frames (used interchangeably herein) generally come in custom built and prefabricated types. Prefabricated door frame assemblies offer several advantages over custom built frames because they can be mass produced for cost savings, can be made from a variety of materials and finishes, and consist of" a minimum number of components, thus making them relatively easy to install. Nevertheless, they have certain disadvantages because they are not manufactured for walls of unusual thicknesses and installers must order a wide variety of frames to fit the exact dimensions of the many sized wall openings into which they designed be installed. [0003] Adjustable pre-fabricated door frame assemblies have been developed to address these shortcomings. The adjustable frames allow installers to use the same basic frame on door openings of varying and unusual widths. These adjustable prefabricated door frames often achieve variability of width through two frame halves that are attached to one another using fasteners, sleeves, clips, or some other attachment mechanism. Consequently, the addition of these fastening mechanisms increases fabrication costs because of the need for additional components and the welding often required to attach the components to the frame. Also, because these frame types consist of numerous connected components, their finish can appear unsightly compared to a single piece frame and their can be undesirable play between the frame halves. [0004] In the field of adjustable door frames, various methods for aligning and fastening the frame halves to one another have been conceived; each addressing the above concerns with varying degrees of success. Herr et al. (U.S. Pat. No. 3,884,003) patented an adjustable frame that utilized clips which attach the two frames halves to one another. This, however, requires additional parts and welding and, thus, additional fabrication costs. Other products utilize spring clips that are not welded, but rather, are attached using the force of the spring (U.S. Pat. No. 4,986,034). These too require additional parts and additional installation time because the spring clip is not integrated into the frame. All of this adds costs to the manufacture, thus making this typically low cost high volume item less desirable. [0005] Rentschler patented an adjustable frame that utilizes guide pins and sleeves to attach the two halves (U.S. Pat. No. 4,813,204). Fabricating these frames requires several additional parts and welding, again adding cost. Also, the finished product can appear unsightly and still have undesirable play between the frame halves. When there is too much play between the frame halves, in addition to structural weakness, a dangerous situation is created because, for example, children could stick their fingers in the gap between the two halves and get stuck, caught, or otherwise injured. Other designs overcome these shortcomings by adding fasteners to this design, which firmly secure the two frame halves (U.S. Pat. No. 5,233,802). Ultimately, these frames still require additional fabrication costs and will still appear unsightly once installed because of the exposed screws on the frame. While some frame designs have been developed (U.S. Pat. Nos. 5,528,869 and 6,282,851) without the use of these additional appurtenances, they nevertheless have many of the same shortcomings. For example, Beaton (U.S. Pat. No. 6,282,851) essentially discloses a door frame that can be installed with concealed side walls by permitting the side walls to be covered with a skim coat of plaster. Both patents are subject to the above shortcomings because they rely upon the door opening's strength for structural support rather than the strength of the frame itself. Also, these designs do not utilize a hairpin-shaped clamp that grips a shaft, in order to firmly clamp the frame halves. The present invention has a much deeper recess into which the rear half may be slid than can be found in any of the prior art. Unlike the prior art, the hairpin-shaped curve is angled beyond one hundred and eighty degrees and assures a positive pinch point with the rear frame half that assures a firm connection between the frame halves. [0006] Other commercially available frames also utilize a similar design to the above. These, nevertheless, are subject to the same shortcomings since they are manufactured on a press brake, which is disadvantageous because of additional manufacturing costs, and do not utilize a hairpin-shaped clamp with a flange at the end, which assures a positive pinch point with the rear frame half. [0007] Therefore, there is a need for an adjustable frame that utilizes a minimum of frame components, can be cheaply fabricated without the need for welding, can be installed without the use of fasteners between the frame halves, and achieves a secure connection between the frame halves without play or an unsightly appearance. SUMMARY OF THE INVENTION

[0008] The invention is directed to overcoming the above shortcomings of the prior art by attaching the frame halves to one another through an adjustable hairpin-shaped clamp, which provides a secure connection both during and after assembly. The invention can be installed in wood-stud walls, metal-stud walls, masonry walls, and other wall types. Inexpensive fabrication is achieved because sheet metal parts may be fabricated on a roll former rather than on a press brake. Also, because the adjustable hairpin-shaped clamp is integral to the frame halves, no additional part or welding is required during fabrication or installation. Play between the frame halves is minimized because the clamp provides a strong and secure connection between the frame halves. The hairpin-shaped clamp, being curved beyond one hundred, and eighty degrees, assures a pinch point with tiie rgajr frame, half The_ flange tip at the end of the hairpin-shaped clamp facilitates easier installation by guiding the rear frame half into the clamp and mitigating the effect of dents in the frame, which commonly occur in transit. [0009] The front frame half is divided into two surfaces, separated by a ninety degree bend. One surface is flat and serves as a side wall that lays adjacent to the wall board. The other surface is shaped to include an integrated door stop, shaped as an outward channel, and clamp beneath the channel in the shape of a hairpin. The rear frame half is more simply L-shaped with a ninety degree bend. One leg of the "L" serves as a shaft that is inserted into the clamp of the front half at the time of installation while the other leg serves as a side wall that lays adjacent to the wall board. Once installed, the female portion of the hairpin-shaped clamp is mated with the male portion of the second frame half and the compression between the two allows for a secure attachment that provides torsional and shear rigidity to the frame assembly. [0010] Other features and advantages of this invention will become apparent from the following description of one embodiment of the invention, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0011] Figure 1 is a perspective view of one embodiment of the invention in assembled form. [0012] Figure 2 is an illustration in cross sectional view of one embodiment of the invention as installed in a wood stud frame wall opening. [0013] Figure 3 is an illustration in cross sectional view of the prior art adjustable door frame mechanisms utilizing a welded clip to connect the frame halves. [0014] Figure 4 is an illustration in cross sectional view of the prior art adjustable door frames utilizing a spring clip to connect the frame halves. [0015] Figure 5 is a perspective detail of the guide pins and sleeves utilized by a prior art adjustable door frame to connect frame halves. [0016] Figure 6 is an illustration in cross sectional view of a prior art adjustable door frame that utilizes a slot and strip to attach the two frame halves. [0017] Figure 7 is a perspective detail of the frame halves according to one embodiment of the invention. DETAILED DESCRIPTION

[0018] In the following detailed description of various embodiments of the invention, numerous specific details are set forth in order to provide a thorough understanding of various aspects of one or more embodiments of the invention, however, one or more embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, procedures, and/ or components have not been described in detail so as not to unnecessarily obscure aspects of embodiments of the invention. [0019] In the following description, certain terminology is used to describe certain features of one or more embodiments of the invention. For instance a "frame" includes any arrangement of structural elements configured to mount a door or window to a wall opening. [0020] Fig. 1 is a perspective view of one embodiment of the invention in assembled form. As shown in Fig. 1, the disclosed embodiment of the door frame assembly 10 includes a header frame 14, a strike frame 18, and a hinge frame 22. A continuous hairpin-shaped clamp 26 is included along each frame portion that serves to attach the two frame halves 54 and 64 to one another. An alternate configuration of the invention includes an additional curve 59 for the installation of weather-stripping on the frame. When the door frame assembly 10 is installed in the door opening 30 in the wall 34, the header frame 14 is positioned at the top of the door opening. The strike frame 18 is positioned along one side of the door opening 30 perpendicular to the installed header frame 14. The strike frame 18 extends from one end 30 of the header frame to the floor 42. The hinge frame 22 extends from the other end 46 of the header frame 14 to the floor 42. The wall 34 is cut away to show the continuous clamp that attaches the two frame halves. [0021 ] Fig. 2 is an illustration in cross sectional view of one embodiment of the invention as installed in a wood stud frame wall opening. Fig. 2 shows a cross sectional view of the door frame assembly 10 in the wall 34 constructed with wood stud 44 and wall paneling 52 on either side. The frame assembly 10 is comprised of two halves 54 and 64. Each frame half 54 and 58 has a side wall 58 that lays adjacent to the wall paneling 52. The front half 54, includes a door stop 56 and a hairpin-shaped clamp 60, into which the shaft 64 of the rear door frame is inserted. The clamp 60 has a flange 62 at the end which directs the shaft 64 of the door frame on insertion into the clamp 60. Flange 62 is opposite a curved corner 63 at the extreme other end of the hairpin-shaped clamp 60 which coordinates with the flange 62. Prior to insertion, the flange 62 lays adjacent to underside of the door stop, because, on insertion, the clamp 60 is expanded from its natural position, it compresses onto the shaft 64 and provides torsional and shear support to the door frame assembly 10. The flange 62 and the curved corner 63 assist the user to guide the male portion of the shaft 64 into the female portion of the clamp 60 quickly and effectively. The strength of the connection provided by the clamp 60 and the shaft 64 allows enough structural rigidity to the door frame assembly 10 that it does not need to lie alongside the wall 34, but is allowed a gap 66 between the door frame assembly 10 and the wall 34. [0022] Figures 3-6 illustrate the prior art assemblies that failed to achieve the purposes of the disclosed embodiment. Fig. 3 is an illustration in cross sectional view of the prior art adjustable door frame mechanisms utilizing a welded clip to connect the frame halves. Fig. 3 shows a cross sectional view of adjustable door frame assembly 68 within a wood stud wall 72. Frame width variability is achieved through two frame halves 76 and 80. Spot welded 84 to one half is a tongue 88 that, on installation, is slid inside a clip 92 that is spot welded 96 to the second frame half 80. The friction between the tongue 88 and clip 92 attaches the two frame halves to one another. [0023] Figure 4 is an illustration in cross sectional view of the prior art adjustable door frames utilizing a spring clip to connect the frame halves. The door frame assembly 96, that utilizes a retaining clip 100 in order to attach the front 104 and rear 108 frame halves within the wood stud wall 112. Figure 5 is a perspective detail of the guide pins and sleeves utilized by a prior art adjustable door frame to connect frame halves The door frame assembly 116 that utilizes cylindrical shafts 122 inserted into sleeves 120 in order to attach the front 124 and rear 128 frame halves to one another. Figure 6 is an illustration of a cross sectional view of a prior art adjustable door frame that utilizes a slot and strip to attach the two frame halves Fig. 6 shows a door frame assembly 132 that utilizes a slot 136 and strip 140 in order to connect the door frame halves 144 and 148. The wall 152 to which the door frame assembly 132 is attached is made of wallboard 156 on either side of a wood stud structure 160. The door frame assembly 132 lies alongside the wall. [0024] Figure 7 is a perspective detail of the frame halves according to one embodiment of the present invention. Fig. 7 shows the adjustable door frame assembly 10 of the disclosed embodiment in perspective detail. The rear frame half 54 is shown outside of the clamp 60 of the front frame half 64. Also shown, is the door stop 56 and flange 62 at the end of the clamp 60. [0025] While certain exemplary embodiments of the invention have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad aspects of the invention, and that the embodiments of the invention are not to be limited to the specific constructions and arrangements shown and described, because various other modifications are possible.