GB2313426A

GB2313426A - Corner joints for channel sections

Info

Publication number: GB2313426A
Application number: GB9610646A
Authority: GB
Inventors: Reginald Michael Bradbury
Original assignee: Flamgard Ltd
Current assignee: Flamgard Ltd
Priority date: 1996-05-21
Filing date: 1996-05-21
Publication date: 1997-11-26
Also published as: GB9610646D0

Abstract

A frame comprises first and second channel sections (10,11) which are joined at a corner of the frame. Each section (10, 11) has a flat bottom wall (30, 32) and perpendicular side walls (31,33)having ears (23, 27) that extend axially beyond the bottom walls (30, 32) The channel section (10) has a tab (24) which extends perpendicular to the bottom wall (30) and away from the channel thereof. The sections (10, 11) are arranged such that their ears (23, 27) overlap and the tab (24) lies against the bottom wall (32) of the second section (11). The sections(10, 11) are then joined together by spotwelding the overlapping ears (23, 27) together and by spotwelding the tab (24) to the bottom wall (32) Optionally, an aligning rod (20) may be inserted through aligned apertures (25, 28) in the overlapping ears (23, 27) prior to welding.

Description

CORNER JOINT FOR A FRAME ETC.

This invention relates to a method of joining a pair of channel-section members, for example to form a frame, bracket, chassis or the like structure.

Frames etc. are often constructed from elongate steel members, which are preferably channel-section in order to provide strength. Typically, the channel-section members are joined at the corners of the frame by a butt joint as shown in Figure 1. A disadvantage of such butt joints is that a complicated seam weld has to be formed between the two members in order to provide the required strength. Another disadvantage of butt joints is that the end of one of the channel-section members is closed by the other member, and thus a well is formed in which water etc. can collect. Further, the distortion which arises from the welding does not allow for pre-punching of holes.

Another type of known joint between channel-section members comprises a mitre joint, as shown in Figure 2. Frames formed with mitre joints do not suffer from the disadvantage that they can collect water etc. However, mitre joints are just as complicated to weld as butt joints, and furthermore the members have to be cut and aligned more precisely.

We have now devised a method of forming a corner joint between a pair of channel-section members which alleviates the above-mentioned problems.

In accordance with this invention, there is provided a method of forming a corner joint between two channel-section members, the method comprising providing first and second elongate channel-section members each having a flat bottom wall and perpendicular side walls which comprise respective ears that extend axially beyond the bottom wall at one end of the member, the first elongate channel-section member also having a transverse tab extending from the bottom wall at said end of the member away from the channel thereof, arranging the members such that the ears on one member overlap with the respective ears on the other member such that their respective channels are directed outwards, and such that the tab on the first member extends along the bottom wall of the second member, and interconnecting the tab with the bottom wall of the second member.

The joint is relatively simple and quick to form, since it merely comprises positioning the two members and then interconnecting the tab on the first member with the bottom wall of the second member.

Preferably the tab on the first member is interconnected to the bottom wall of the second member by spot welding, which is a much quicker process than seam-welding joints.

Preferably the overlapping ears of the two members frictionally interengage. However, optionally these overlapping ears may also be spot-welded together The construction of the ends of the channel-section members is more complicated than conventional corner joints.

However, preferably each channel-section member is formed by stamping and folding a flat sheet of metal. It is thus relatively quick to form the channel-section members. It will be appreciated that any increase in construction time is saved by not having to make complicated seam welds.

Preferably one of the channel-section members is stamped to form ears which lie in planes that extend parallel to, but are offset from, the planes of the respective side walls. In this manner, the ears on one of the members can fit between the ears on the other member, thereby allowing channelsection members of the same cross-section to be joined in accordance with this invention.

Preferably the end of the bottom wall of the first member is cut and then bent away from the channel thereof to form said tab.

Preferably the tab of the first member is bent through 900 from the plane of the bottom wall, the two channel-section members being arranged perpendicular to each other, so that a right-angled joint is formed.

Preferably an aperture is formed in each ear, so that the two members can be held in alignment prior to interconnection, by aligning the apertures in the respective overlapping ears and then passing an alignment member through each of the aligned apertures. In this manner any risk of misalignment of the two members is alleviated.

Preferably the two members are arranged such that the tab of the first member extends along the channel in the second member.

An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIGURE 1 is a perspective view of a prior art butt joint at a corner between two channel-section members; FIGURE 2 is a perspective view of a prior art mitre joint at a corner between two channel-section members; FIGURE 3 is a perspective view of a joint in accordance with this invention at a corner between two channel-section members; FIGURE 4 is a plan view of the blanks of the channelsection members of Figure 3; and FIGURE 5 is an exploded perspective view of the joint of Figure 3.

Referring to Figure 3 of the drawings, there is shown a corner joint between first and second elongate, channelsection members 10, 11. Referring to Figure 4 of the drawings, the members 10, 11 are formed from respective steel strips 12, 13 which are punched at their ends to be joined, so as to form blanks 20, 21.

The first blank 20 comprises two slots 22 in one end, which extend parallel to the longitudinal side edges of the strip 12. The slots 22 are equally spaced from respective side edges of the strips, thereby defining a pair of ears 23 separated by a tab 24 which project axially of the strip 12.

Apertures 25 are punched in the ears 23.

The second blank 21 comprises a cut-out 26 in one end, which is disposed centrally between two axially projecting ears 27. Apertures 28 are punched in the ears 27. Next, the first blank 20 is stamped, such that its ears 23 are displaced upwardly along respective lines A into a position in which their respective lower surfaces lie in the same plane as the upper surface of the strip 12. The tab 24 is bent downwardly along line B until it extends perpendicular to the plane of the strip 12. Next, the longitudinal side edges of the blank 20 are folded upwardly along lines C, so as to form the first channel-section member 10, having a flat bottom wall 30 and upstanding side walls 31. ' Similarly, the longitudinal side edges of the second blank 13 are folded along the lines D, so as to form the second channel-section member 11, having a flat bottom wall 32 and upstanding side walls 33.

Referring to Figure 5 of the drawings, the ends of the channel-section members 10, 11 are engaged at right angles to each other and such that the respective channels are directed outwardly. When engaged, the ears 23 on the first member fit tightly, as a friction fit, between the ears 27 on the second member and the tab 24 on the first member 10 extends along the floor of the channel in the second member 11. In this position, the apertures 25, 28 in the respective ears 23, 27 are aligned, and the members 10, 11 can thus be held in engagement by passing a rod or bolt 29 through the apertures 25, 28, as shown in Figure 3.

Finally, the tab 24 on the first member 10 is also spot-welded to the bottom wall of the second member 11. Also, the overlapping ears 23, 27 on the respective channel-section members may be spot-welded in face-to-face contact.

It will be appreciated that corner joints in accordance with this invention are quick and simple to form, and yet are very strong. The use of the alignment rod 29 through the apertures in the ears 23, 27 enables the members 10, 11 to be aligned precisely, so that the angle between the members is accurate: the alignment rod 29 is removed after the joint has been completed.

Claims

1) A method of forming a corner joint between two channelsection members, the method comprising providing first and second elongate channel-section members each having a flat bottom wall and perpendicular side walls which comprise respective ears that extend axially beyond the bottom wall at one end of the member, the first elongate channel-section member also having a transverse tab extending from the bottom wall at said end of the member away from the channel thereof, arranging the members such that the ears on one member overlap with the respective ears on the other member such that their respective channels are directed outwards, and such that the tab on the first member extends along the bottom wall of the second member, and interconnecting the tab with the bottom wall of the second member.

2) A method as claimed in claim 1, in which the transverse tab on the first member is interconnected with the bottom wall of the second member by spot welding.

3) A method as claimed in claims 1 or 2, in which the overlapping ears of the two members are frictionally engaged.

4) A method as claimed in any preceding claim, in which the overlapping ears of the two members are spot welded together.

5) A method as claimed in any preceding claim, comprising stamping and folding a sheet of metal to form said channelsectional members.

6) A method as claimed in claim 5, comprising stamping and folding a sheet of metal to form a channel member having ears which lie in planes that extend parallel to, but are offset from, the planes of the respective side walls.

7) A method as claimed in any preceding claim, comprising cutting and bending said bottom of the first channel-section member away from the channel thereof to form said tab.

8) A method as claimed in claim 7, in which the tab is bent through 90 from the plane of the bottom wall, the two channel-section members being joined at right angles to each other.

9) A method as claimed in any preceding claim, in which an aperture is formed in each ear, an alignment member being inserted through aligned apertures in the respective ears of the channel-section members.

10) A method as claimed in any preceding claim, in which the two channel-section members are arranged such that the tab of the first member extends along the channel of the second member.

11) A method of forming a corner joint substantially as herein described with reference to Figures 3 to 5 of the accompanying drawings.