GB2433088A

GB2433088A - Dovetail bar and bracket for depth adjustable frame assembly

Info

Publication number: GB2433088A
Application number: GB0525127A
Authority: GB
Inventors: Ian Douglas Law
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-12-09
Filing date: 2005-12-09
Publication date: 2007-06-13
Also published as: GB0525127D0

Abstract

An elongate bar 10 has a dovetail cross section and at least one and preferably two barbs 16, 26 which point in the direction opposite to the end of the bar 10 to which they are nearest. In use the bar 10 fits within complementary shaped dovetail channels in two frame members to be secured together. Barbs 16, 26 secure the bar 10 in place. Preferably a stop 20 is provided to prevent the bar 10 from sliding too far within the complementary frame channel. Bar 10 enables frames of varying thickness to be assembled. An L-shaped bracket (figures 10 and 11) is also provided having a first arm 32 with aperture 42 for securing it to an architrave and a second arm 34 with a dovetail section (sides 36 and base 38) for securing it within a complementary shaped channel of a frame member. Bar 10 and bracket are preferably made from pressed steel.

Description

1 2433088 Bar and Bracket for Fitting Frames to Buildings The present

application relates to a bar for use in fitting a depth- adjustable frame to a hole in a wall. The frame may be, for example, a door frame or a window frame. The S present invention also relates to a bracket for fitting architrave to that frame.

United Kingdom patent GB2385085 discloses a method of installing a door frame in a hole in a wall. Figures 1 to 7 illustrate the components used in that method. The entire disclosure of GB2385085 is incorporated herein by way of reference. That prior art method involves the use of a kit of components comprising two frame sides and a frame lintel, each of which is fbrmed of two beam elements and a door slammer, whereby the side frames and frame lintel are depth adjustable by spacing the beam elements apart by more or less amounts. The door slammer then hides the gap between them. l'hat depth adjustment is then fixed at a desired depth by using one or more locking bar at the backs of the frame sides and lintel. The locking bars each have a dovetail section that adjustably fits in corresponding dovetail sectioned slots in the backs of the beam elements. At one state of adjustment, the bar will slide in the slots, and at another state of adjustment, the bar locks in the slot. That adjustment is perfbrmed using a screw in the back of the bar, which screw can adjust the length of the short side of the dovetail, and thcrefire the angle of the dovetail.

That prior art document also discloses an L-shaped bracket, one arm of which has a dovetailed section also for fitting in the slots in the backs of the beam elements. A slot br attaching an architrave to the arm is provided on the other arm. The brackets therefore allow the architrave quickly to be fitted onto the fitted frames.

The following difficulties have been identified, however, with that prior art design. I. The screws at the backs of the bars are difficult to tighten while maintaining the two beam sections at a desired depth -there can be many bars, and twice as many screws as bars, all of which need to be tightened. 2. The screws extend out of the back of the beam elements, thereby fbuling against the perimeter of the hole in the wall. This makes the assembled frame difficult to insert into the hole. 3. in order to be strong enough, the arm of the bracket with the slot in it, which is generally made of injection molded resin filled plastic, has to he bulky. As a result, the wall has to have a portion cut out of it in order for sinking the bracket into it. Only then can the architrave lie flush against the wall.

It would therefore be desirable to provide an improved depth adjustable frame, or improved components thereof The present invention therefore provides a bar tbr a depth-adjustable frame, the bar having two ends and a dovetail shape in section, the dovetail shape having a maximum height of less than 1 5mm, two asymmetrical sides and a wall extending between the two asymmetrical sides, the bar having a maximum width of less than 30mm and a maximum length of less than 30cm, and wherein the bar comprises a barb that in use points away from the end of the bar that is nearest to the barb.

Preferably the barb is a substantially rigid barb.

Preferably there are two barbs, both, in use, pointing in opposite directions. Preferably they both point away from their nearest bar end. Both barbs will therefore point approximately along the length of the bar.

Preferably the dovetail shape does not have a solid COS5 section.

Preferably the dovetail section is formed from folded or pressed metal, the wall forming either a short side or a long side of the dovetail shape. A steel pressing provides a low cost of manufacture.

Making the bar of metal also allows the bar to be used in fire rated door sets or window frame sets (unlike thcrmoplastics, which would normally melt).

Preferably the walls or sides of the bar are approximately 1mm thick.

Preferably the wall is the long side of the dovetail shape. Preferably the or each barb is provided in that long side. The barbs might, however, be provided in the assymetrical sides of the bar -the barbs are for engaging the slot in which the bar is inserted for gripping the slot, and it does not matter which wall of that slot they engage.

The wall serves to maintain a distance between the two assymetrical sides.

Preferably a first barb is provided within 30mm of the first end of the bar and points away from that end. A second barb is then preferably spaced from that first barb at a position on the bar that is nearer the second end ot the bar than that first barb.

Preferably the second barb is provided within 30mm of that second end of the bar and, in use, points away from that end of the bar.

Additional barbs might be provided to provide additional grip against the slot.

Preferably the bar has a generally C-shaped section, the top and bottom of the C being the asymmetrical sides of the dovetail shape and the back of the C defining either the long side or the short side of the dovetail shape. Tlîe or each barb extends outwardly from the C-shaped section.

Preferably the or each barb is integrally formed with the bar. Most preferably they are pressed out of the material of the dovetail shape.

Preferably the barbs are all provided on the same side of the dovetail shape.

Preferably the bar has an end stop positioned further away from the first end of the bar than the first barb. Preferably it is positioned between the two barbs. The end stop prevents the bar from being inserted too far into a slot in a beam section, whereby it can be ensured that the bar is pushed, in use, to an adequate depth into both beam sections of the side frame or lintel of the frame for a secure connection therebetween.

Preferably the end stop is provided on the same side of the dovetail shape as the or each barb. That or those barbs then will be angled towards the end stop.

The barbs can prevent the bar from being easily removed from a slot in a beam section once the bar has been inserted into the slot up to the end stop, and the end stop can prevent the bar from being inserted any further up the slot. The bar can therefore be locked in a substantially fixed position in the beam section by virtue of the barbs and the end stop.

Preferably the end stop is integrally formed with the bar. Most preferably it is pressed out of the material of the dovetail shape.

Because of the barbs, the screw arrangement required in the prior art product is no longer required in order to lock the bar in its desired position in the hack of a beam section of the side or lintel of the frame.

Because of the end stop, the first end of the bar does not need to he locked in a desired 1 5 location before the second end is slotted into a slot in a second beam section.

Preferably only OflC end stop is provided.

Preferably the end stop is positioned between 20 and 50mm from the first end of the bar.

Most preferably the end stop is positioned about 25mm from the first end of the bar.

Preferably the bar is between 70 and 200mm long. More preferably, the bar is about 100mm long.

Preferably the angle of the dovetail is approximately 104 degrees.

Preferably the width of the bar, excluding any end stop or barb, is between 10 and 25mm, and more preferably the width of the bar is about 16mm.

Preferably the height of the bar, excluding any end stop or barb, is between 4 and 10mm and more preferably the height is about 6mm.

Preferably the bar is substantially straight from end to end. Preferably the section is substantially constant from end to end, except for the barbs and the end stop.

The present invention also provides a method of manufacturing the above described bar comprising taking a sheet of material and pressing it in a press to firm a bar having a dovetail shape in section, the dovetail shape having a maximum height of less than 1 5mm, two asymmetrical sides and a wall extending between the two asymmetrical sides, the bar having a maximum width of less than 30mm, and cutting the sheet of metal such that the bar has a length of less than 30cm, wherein the method additionally comprises the step of providing a barb for the bar.

Preferably the press forms the barb by pressing material out of the plane of the sheet of material.

Preferably the material is a metal.

Preferably the metal is steel.

Preferably the sheet material has a thickness of no more than 1mm, and more preferably of no more than half a millimetre. Most preferably the sheet material is grade 304 stainless steel.

The present invention also provides a method of' manufacturing a bracket, the bracket comprising an L-shaped member having a first arm and a second arm, the first arm having a hole or slot therein and the second arm having a generally dovetail shaped cross section with two asymmetrical sides and a side extending therebetween so as to form a generally Cshaped section for the dovetail shape, the method comprising the step of pressing the bracket from a single sheet of material in a press.

Preferably the side extending between the two asymmetrical sides is the long side of' the dovetail shape. It may, however, he the short side.

Preferably the material is a metal.

Preferably the metal is steel.

Preferably the length of the first arm is between 15 and 40mm. Most preferably it is about 25mm long.

Preferably the second arm is between 15 and 50mm long. Most preferably it is about 35mm long.

Preferably the hole or slot in the first arm is pressed out of the sheet of material.

Preferably it is positioned at a distance of' between 5 and 1 5mm from the free end of' the first arm. For an arm that is 35mm long, preferably the hole or slot's centre is a distance of 25mm from the second arm.

Preferably the asymmetrical sides of the bracket have a height of about 5mm and are angled relative to the plane of' the side extending therehetween, so as to define the dovetail shape, at an angle of about 104 degrees.

Preferably the width of' the bracket is less than 30mm, more preferably between 10 and 20mm and most preferably about 16mm.

Preferably the asymmetrical sides have a length that is shorter than the second arm, whereby they can easily be pressed from the sheet material so as to have a rectangular shape, i.e. a constant shape along their length. Preferably that length is between 10 and 35mm. For a second arm having a length of about 25mm, preferably the length of the asymmetrical sides is about 20mm.

Preferably one or more ridge is pressed into either or both of the arms so as to stiffen the bracket.

Preferably the ridge continues around the bend between the two arms, whereby the right angle between the two arms is also stiffened.

Preferably the ridge is raised from the plane of the sheet of material by no more than 1mm, whereby the bracket still Sports a narrow profile.

Preferably the raised ridge extends across about 70% of the width of its arm, although with multiple ridges, either smaller ridges will be used, or one large ridge and then smaller ridges will be used.

These and other aspects of the present invention will now he described by way of example only with reference to the accompanying drawings in which: Figures 1 to 7 show a prior art, depth-adjustable frame arrangement using a screw

adjustable bar;

Figure 8 is a section through a preferred bar of the present invention; Figure 9 is sectional view of the bar of Figure 8; Figure 10 is a front elevation of a preferred bracket of the present invention; Figure 11 is a sectional view through the bracket of Figure 10; Figure 12 is a perspective view of an end of an alternative embodiment of bar; and Figure 13 is perspective view of an end of a preferred embodiment of bar.

Referring first of all to Figures 1, 2, 3 and 4, the prior art depth-adjustable frame of GB2385085 is illustrated. It is used to fit a door frame in a hole in a wall, and then an architrave 7 can be attached thereto using the bracket 9 of Figures 6 and 7 in the manner shown in Figures 1 and 5. The present invention simply replaces the bar 4 and brackets 9 of that prior art device. Accordingly a discussion of that prior art system will he useful here.

The fitting of the frame involves, for each of the two frame uprights and the frame lintel (the elements), the adjustment of the depth of that element. For that purpose, each clement comprises two beam sections 2 and a door stopper 8. The beam sections 2 are joined to each other in a generally parallel relationship by a plurality of bars 4 (usually at least three for the uprights and at least two for the lintel, since it is shorter). A variable gap, therefore, is provided between the two beam sections 2. The door slammer 8 is used to bridge that gap, whereby the gap is hidden. The door slammer 8 is usually pre-attached to the beam section 2 that will be carrying the door.

The bars each have a dovetail shape section and they can normally slide within slots in the backs of the beam sections 2. The dovetail shape, however, includes two asymmetrical sides that can simultaneously be brought to bear against the sides of the slot. For that purpose, two screws 6 are provided for each bar 4 in the dovetail shape's short side. By screwing the screws into the bars, the angles of the asymmetrical sides can be adjusted SO as to bring those sides into tight engagement with the sides of the slot.

That adjustment jams the dovetail bar 4 within the slots so as to fix the depth of the frame.

Then the frame is fitted to the hole in the wall. The back of the frame can then be filled with expanding builders' foam. Then, the sides can he tidied by the application of architraves 7 to the frame. That is done using the L-shaped brackets 9.

The brackets 9 are made of injection moulded, resin-filled, plastic materials. They are L-shaped and have a first arm having a slot 4 in it for attaching the architrave 7 to it using, for example, double ended pins as disclosed in, fOr example, GB2385 103, the entire disclosure of which is incorporated herein by way of reference. The bracket's second arm, however, has a dovetail shaped section for fitting in the slots in the backs of the beam sections 2 with a friction fit (or with glue). The architrave can therefOre be fitted to the frame. However, in order for the architrave to fit flush against the wall, a hole first needs to be cut or scraped into the wall into which the first arm of the bracket 9 can be countersunk.

The prior art bracket needs to be thick (and therefore needs to be countersunk into the wall) in order for it to he strong enough to retain the architravc in position. The back of the architrave, rather than the wall, however, will not want to he cut out for the bracket because there is already a hole in the back of the bracket for the double ended pin. To cut out that back for accommodating the bracket as well (which bracket may be 5mm or more thick) would prevent a long enough double ended pin from being useable since it would extend out of the front surface of the arehitrave. Too short a double ended pin would not provide a strong enough connection of the architrave to the bracket, and making a thicker architrave is not desireable since it would give the wrong appearance to the finished frame. Finally, the screws in the back of the bar are awkward to adjust.

The bar and bracket disclosed herein, however, alleviate these difficulties. With the bracket and bar shown in Figures 8 to 13, the screws are no longer required for the bar and the hole in the wall for the bracket can either be omitted, or can be made much less deep, or can instead he pre-formed in the architrave -it is not needed to be particularly deep (1 to 2 mm at most).

Referring to Figures 8 and 9, a bar 10 of the present invention is shown, It, like the prior art's bar, has asymmetrical sides 12. Further, it has a long side 14. However, this embodiment of bar does not have a short side. *Not adding the short side reduces the material cost of the bar 10 and allows the bar to be made on a press, rather than needing a rolling machine.

In the long side 14 of the bar 10, a barb 16 is provided. The barb 16 is stamped or pressed out of that long side 14 and extends outwardly from the back of the long side 14.

The barb 16 may have either an edge or a point for bearing against the wall of the slot in the beam element 2. Preferably the edge or point is sharp.

The barb 16 is positioned near a first end 18 of the bar 10 (in the illustrated embodiment, approximately 9mm from that end).

The bar 10 also has an end stop 20, which is spaced further away from that first end 18 than the barb 1 6. In this illustrated embodiment it is spaced 25mm from that first end 18.

The end stop 20 is also stamped or pressed from the material of the long side 14 of the bar 10 and also extends outwardly from that long side 14. I-Iowever, the end stop 20 extends perpendicular to the long side 14, whereas the barb 16 is angled away from the long side 14 perhaps at an angle of about 450 The barb 16 therefbre points generally away from that first end 18, i.e. generally towards the opposite end 28 of the bar 16 and generally towards the end stop 20. With this arrangement for the barb 16 and the end stop 20, the end 18 of the bar 10 can he pushed into a dovetail sectioned slot provided in the back of a beam section of a frame, such as the ones discussed above, hut only as far as the end stop 20. Further, because of the barb 16, attempts to remove the bar 10 from that slot will be resisted by the barb 16 digging into the wall of the slot. The barb 16 therefbre provides a locking mechanism fhr the bar 10 for preventing disengagement of 1 5 the bar 10 from a slot whereas the end stop 20 restricts the depth of insertion of that end I 8 of the bar 10 into a slot.

Figure 13 shows the barb 16 and end stop 20 in perspective, whereby the pressing of them from the material of the long side of the dovetail shape can be more clearly seen.

Only that one end 18 of the bar 10 is illustrated in that Figure.

The barb 16, although shown in Figure 8 and 13 to be pressed from the material of the long side 14 of the bar 10, could alternatively he provided as a pin pushed through the long sidle 14 50 as to extend out the back of the long side 14, like in a carpet gripper strip.

Alternatively, as shown in Figure 12, the barb may be in the form of a flexible flap 46 which will pivot about a hinge point 48 adjacent the long side 14 of the bar 10. Before inserting the bar into a slot, the flap 46 must be bent so as to extend away from the first end 18 of the bar 10 (as shown in Figure 12). That flexible flap 46 will then resist removal of the bar 10 from a slot in the back of the beam section like the integral barb 16 of Figure 13. The flexible flap might be replaced with a rigid flap, however, whereby it would not need to be folded to the correct onentation before inserting the end 1 8 into the slot.

Figure 13 also shows the end stop 20 pressed out of the material of the long side 14 of the bar 10. However, much like the barb in Figure 12 (the flap 46), the end stop 50 can also be fbrmed as a separate component that is attached to the long side 14 of the bar. It, however, is preferably rigid. Such an embodiment is shown in Figure 12.

Towards the opposite end 28 of the bar 10, an opposing barb 26 is also provided. Much like the barb 1 6 at the first end 1 8 of the bar 10, this opposing barb 26 is spaced from the end 28 of the bar 10 (as shown, it is approximately 9mm from the end). It is also fbr gripping against a slot in a back of a beam section 2. However, that slot is in a second beam section 2.

The bar 1 0 is preferably fbrrned by pressing a flat sheet of material into the finished shape. Accordingly, it is advantageous to have the barbs 16, 26 and the end stop 20 pressed directly out of the material of that fiat sheet of material, i.e. from the long side 14 of the bar 10. By using a pressing method of manufacture, and a single sheet of material ibr the entire construction, production costs of the bar can be reduced. The prior art bars had to he rolled in order to achieve the folding of the short side internally for providing a surface against which the two screws 6 could engage. Pressing machines, however, are much cheaper to operate than rolling machines. The need for screws in the prior art bars also added to the cost, both in terms of material costs and in terms of handling costs (i.e. when putting together a kit of components).

Referring now to Figures 10 and 11, an improved bracket is also disclosed. Like the pnor art bracket 9, this improved bracket 30 is L-shapecl and has two ann 32, 34.

A hole 42 is provided in the first arm 32 near its distal end 44 (the edge of the hole is shown to be spaced about 4mm from that end 44, but other distances might be used).

That hole, which may alternatively be a slot, such as in prior art brackets, e.g. GB2385085 or FP1335094, is for attaching the arm of the bracket to an architrave (or perhaps to the wall, as in EP1335094) with a nail, a screw or a double ended pin (as disclosed in, for example, GB23 85069).

The second arm 34, however, has a C-shaped section defining a dovetail shape. The dovetail shape has two asymmetrical sides 36 and a long side 38.

No short side is needed to close the top (as viewed in Figure 10) of this dovetail section.

This allows the bracket 30 to be pressed from a sheet of material without needing to use a rolling machine. However, a short side fbr the dovetail arm may be provided if desired. That would give the second arm 34 of the bracket 30 a more rigid cross-section.

Alternatively the pressed form might be manufactured with a short side for the dovetail shape and rio long side. In that design, the two asymmetric sides would depend downwardly (as viewed in Figure 10) from that short side. Further, the two asymmetric sides would diverge away from each other, rather than towards each other as in the illustrated embodiment.

The long side 14 and the first arm 32 both have a profiled cross section. That profile is defined by two co-planar end regions and an intermediate raised ridge 40. That raised ridge 40 is shown to be formed as a single rib extending across approximately 70% of the width of' both the long side 14 and the first arm 32. 1'hat profiled cross section gives the two arms a stiffened characteristic compared to flat sections. The ridge also extends around the bend between the two arms whereby the bend is also stiffened.

Instead of' the single ridge 40, multiple ridges or ribs might he provided. They would similarly give the arms (and bend) increased rigidity properties.

The bracket is made by a pressing a sheet of material, i.e. by passing a sheet of material (preferably steel) through a press to fbrm the desired final shape. The advantage of pressing the bracket from a sheet of material such as steel is that it can be produced at a low cost. Prior art brackets were moulded products, made of fibre reinforced plastic materials.

An additional benefit of metal, and in particular steel, is that metal products are allowable in fire rated applications, such as door frame sets.

Another benefit is that, because the first arm of the bracket is significantly thinner than the prior art bracket, there is a reduced or eliminated need to cut away plaster or plasterboard (or the back of an architrave) in order to accommodate the bracket.

Therefbre, the bracket can be fitted to the frame more quickly. The material used for these brackets is typically sheet steel, and may be less than 1 mm thick. Most preferably the material is about 0.5mm thick. Further, the raised ridge 40 usually will extend up from the co-planar end regions only by about 1mm. Therefore, the bracket is typically about 1. 5mm thick, including the thickness of the raised ridge 40. Total thicknesses of between I and 2mm would he equally beneficial.

The preferred material is grade 304 stainless steel.

Regarding the asymmetrical sides 36 of the bracket 30, they are folded up from the end regions of the second arm 34 and are provided with a rectangular shape (as seen in Figure 11). They are shorter than the second arm 34 SO that they can be folded by the press without crinkling the sheet of material at the bend between the two arms. They are also made with a height of about 5mm and a dovetail angle of' about 104 degrees, whereby the dovetail shape will readily fit into the slots provided in prior art beam sections 2. They can, however, be made slightly bigger than the bar of the invention (or with a slightly more open dovetail angle). The bracket would then fit in the slot with a friction fit. However, if made the same size, they can be glued into the slots instead.

The present invention has been described above purely by way of example. It should be noted that modifications in detail may be made within the scope of the invention as defined in the claims appended hereto.

Claims

CLATMS

1. A bar for a (lepth-adjustahle frame, the bar having two ends and a dovetail shape in section, the dovetail shape haviiîg a maximum height of less than 15mm, two asymmetrical sides and a wall extending between the two asymmetrical sides, the bar having a maximum width of less than 30mm and a maximum length of less than 30cm.

and wherein the bar comprises a barb that in use points away from the end of the bar that is nearest to the barb.

2. The bar olclaim I, wherein the barb is a substantially rigid barb.

3. The bar of claim I or 2, wherein there are two barbs, both, in use, pointing in Opposite directions.

4. The bar of claim 1, claim 2 or claim 3, wherein the dovetail section is formed from folded or pressed metal.

5. The bar of any one of the preceding claims, wherein the wall is the long side of the dovetail shape and the or each barb is provided in that long side.

6. The bar of any one of the preceding claims, wherein the or each barb is integrally formed with the bar.

7. The bar of any one of the preceding claims, wherein the bar has an end stop positioned further away from the first end of the bar than the first barb.

8. The bar of claim 7, wherein the end stop is integrally fbrmed with the bar.

9. The bar ol claim 7 or claim 8, wherein the end stop is positioned between 20 and 50mm from the first end of the bar.

10. The bar of any one of the preceding claims, wherein the bar is about 100mm long.

11. The bar of any one of the preceding claims, wherein the maximum width of the bar, excluding any end stop or barb, is about 16mm.

12. A method of manufacturing a bar according to any one of the preceding claims, comprising: taking a sheet of material and pressing it in a press to form a bar having a dovetail shape in section, the dovetail shape having a maximum height of less than 1 5mm, two asymmetrical sides and a wall extending between the two asymmetrical sides, the bar having a maximum width of less than 30mm, and cutting the sheet of metal such that the bar has a length of less than 30cm, and wherein the method additionally comprises the step of providing a barb for the bar.

13. The method of claim 12, wherein the barb is formed by pressing material out of the plane of the sheet of material.

14. The method of claim 12 or claim 13, wherein the material is a sheet of steel having a thickness of no more than 1mm.

1 5. A method of manufacturing a bracket, the bracket comprising an L-shaped member having a first arm and a second ann, the first arm having a hole or slot therein and the second arm having a generally dovetail shaped cross section with two asymmetrical sides and a side extending therebetween so as to form a generally C-shaped section for the dovetail shape, the method comprising the step of pressing the bracket from a single sheet of material in a press.

16. The method of' claim 15, wherein the material is a sheet of steel having a thickness of no more than 1mm.

1 7. The method of claim 15 or claim I 6, wherein the side extending between the two asymmetrical sides is the long side of the dovetail shape.

18. The method of claim 15, claim 16 or claim 17, wherein the asymmetrical sides have a length that is shorter than the second arm.

19. The method of' any OflC of claims 15 to 1 8, wherein one or more ridge is pressed into either or both of the arms so as to stiffen the bracket.

20. The method of claim 19, wherein a ridge continues around the bend between the two arms.

21. The method of claim 19 or 20, wherein the ridge is raised from the plane of the sheet of material by no more than 1mm.

22. A bar substantially as hereinbefbre described with reference to Figures 8, 9 and 13.

23. A bracket substantially as hereinbefore described with reference to Figures 10 and 11.

24. A method of installing a frame in a hole in a wall substantially as hereinbefore described with reference to Figures 8 to 13.

25. A kit of parts fbr installing a frame in a hole in a wall comprising a bar substantially as hereinhefore described with reference to Figures 8, 9 and 13.

26. A kit of parts for installing a frame in a hole in a wall comprising a bracket substantially as hereinbefore described with reference to Figures 10 and 11.