GB2068498A

GB2068498A - Mitred frame joints

Info

Publication number: GB2068498A
Application number: GB8003143A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-01-30
Filing date: 1980-01-30
Publication date: 1981-08-12
Also published as: GB2068498B

Abstract

The corners of a mitred frame are secured together by a device having two plates (1, 4) each bent into shallow V-shape. One flange (3, 7) of each plate is secured (e.g. by welding) to a respective frame member (11) so that the other flanges (2, 6) are set back slightly at their roots from the corner but converge at their free ends onto the mitre line. When these other flanges are screwed together, the mitre joint is tightened. Part (5) of one flange (6) of one plate (4) may be separated and bent about the V apex to abut and be secured to the other flange (3) of the other plate (1), to prevent the frame members mutually skewing. <IMAGE>

Description

SPECIFICATION Improvements relating to mitred frames This invention relates to mitred frames.

It is generally acknowledged that the neatest: and most satisfactory junction at the corner of a frame, particularly when the frame members are of identical section, is a mitred joint. However, there is often considerable difficulty in making such a joint tight and secure. Not only must the two angled ends be firmly abutted together but they must also not be skew to the the plane of the frame. It is the aim of this invention to provide a joint which meets these requirements, and which is particularly suitable for frames of rolled steel sections.

According to the present invention there is provided a device for securing frame members together at a mitred corner, comprising two elements respectively securable by first portions to the adjacent ends of the frame members which are to form a mitred corner, each element having a second portion extending generally in the direction of the mitre angle but not abutting face to face with the opposite second portion when said members are offered up into the desired mitred relationship, and screw means for urging said second portions together thereby to tighten the mitre joint.

The securing of the first portions is preferably by welding when the frame is of metal, and as this will be done on the reverse side of the frame it will not show. Other types of fastening would generally have to penetrate through the frame and thus to exposed.

In a preferred form, one of said elements has a third portion to be aligned with the first portion of the other said element, there being further screw means to draw these portions together.

Preferably, said other element is a V-shaped plate with each flange drilled to receive screw means, and said one element is also a generally V-shaped plate, but with one flange having a part thereof separated from the remainder of that flange and bent about the apex of the V to form the third portion, said remainder constituting the second portion.

This is an added security against the frame members becoming skew. Although there can be more than one screw means through the second portions, at least one further fastening at a well spaced point will more securely guard against the members twisting out of the plane of the frame.

For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawing in which: Figure 1 is a perspective view of a frame corner clamping device, Figure 2 is a side view of the device of Figure 1, showing frame members in outline, and Figure 3 is a view in the direction of the arrow A of Figure 2.

The device is formed from two initially flat rectangular steel plates. The first plate 1 is bent about its longitudinal centre line into a shallow V configuration, the angle for a 900 corner being slightly more than 1350, say 1380. It then has two flanges 2 and 3. The other plate 4 is also formed into the same general shape, but one of its flanges has.a central portion 5 which is divided from remaining portions 6 by slots extending from the free longitudinal edge to the-bend line or apex of the V. This central portion 5 is bent in the opposite direction to extend at right angles to the other flange 7. The portions 6 are each drilled to receive a bolt 8, which passes through registering apertures in the flange 2 of the opposite element 1.

The portion 5 is also drilled to receive a bolt 9, which passes through a slot 10 in the opposite flange 3 extending parallel to the sides of that flange.

This device is designed to be used in conjunction with frame members as shown in Figures 2 and 3. Each member 11 is of rolled or pressed steel, and is generally of shallow Usection with inturned flanges 12, side walls 13, a web 14 and a central wide rectangular rib 1 5 projecting from the web to form rebates on either side, for example for a door or window. The width of this rib is just slightly greater than that of the flange portion 5, while the clamping device as a whole is virtually the width of the channels and it is housed within those channels at their junction on the "outside" of the corner. The flange 3 is welded to the side portions of the web 14 of the upright frame member, while the flange 7 is welded to the corresponding portions of the web of the horizontal frame member.When so welded and the frame members are offered up into the correct mitred position, the free edge of the flange 2 just meets the free horizontal edges of the portions 6 on the mitre line. The bend lines, however, are set back from that line so that the flange 2 makes a slight angle, of about 60, with the portions 6. The action of tightening the nuts on the bolts 8 will therefore stress the flange 2 and portions 6, and firmly clamp the frame members together. As this proceeds, there might be a slight shift in the plane of the frame between the members, and the slot 10 is provided to allow for this before the nut on the bolt 9 is finally tightened. As mentioned above, this extra fastening is a further inhibition against the frame members skewing out of plane of the frame.

It will be understood that different frame sections may be adopted, requiring different configurations of clamping devices. The principle is not restricted to metal frames; there is no reason why a similar technique should not be adopted for wooden ones if the wood is suitably channelled or if it does not matter if a clamp projects beyond the face profile of the frame.

It will also be appreciated that it is not resricted to 900 corners, although that will be the most common need. A corresponding device can be made for attaching to the inside of a corner rather than the outside as in the drawing.

Claims

1. A device for securing frame members together at a mitred corner, comprising two elements respectively securable by first portions to the adjacent ends of frame members which are to form a mitred corner, each element having a second portion extending generally in the direction of the mitre angle but not abutting face-to-face with the opposite second portion when said members are offered up into the desired mitre relationship, and screw means for urging said portions together thereby to tighten the mitre joint.

2. A device as claimed in Claim 1, wherein the elements are formed from metal plate or sheet and are generally V-shaped.

3. A device as claimed in Claim 1 or 2, wherein one of said elements -has a third portion for cooperation with the first portion of the other said element, there being further screw means to secure these portions together.

4. A device as claimed in Claim 2 and 3, wherein part of a flange of said one element is separated from the remainder of that flange and bent about the apex of the V to form the third portion, said remainder constituting the second portion.

5. A device as claimed in any preceding claim wherein in the offered up position said second portions are spaced apart adjacent the ends of the frame members and converge to the mitre line.

6. A device for securing frame members together substantially as hereinbefore described with reference to the accompanying drawing.

7. A frame having mitred corners each secured by a device as claimed in any preceding claim.

8. A frame as claimed in Claim 7, wherein the frame members are of metal and channelled, each securing device being welded by its first portions to said members and being concealed within the channels.