GB2086519A - Joining structural members - Google Patents

Abstract

The overlapping portions of thin, sheet metal members (3, 4) are joined by a fastener (e.g. pop rivet 8 or screw 9) extending through aligned holes 7. In order to resist shear forces on the fastener, the holes 7 are formed in nesting depressions 5, 6. The members may form a frame for a partition. <IMAGE>

Description

SPECIFICATION Joining structural members This invention relates to the joining of light-weight structural members, that is, members usually made by metal rolling from relatively thin gauge sheet metal. A good example of the kind of member with which the present invention is concerned is provided by the commonly used channel rolled from galvanised sheet steel; typical dimensions of the channel being a web width of 75 mm, a flange width of 32 mm and a metal thickness of about 1 mm.

Light-weight structural members of the kind in question are commonly used as wall or partition studs in homes, office suites and the like. They are cheap and of light-weight, and although they are not well adapted for use as sidewardly unsupported columns of torsionally stressed members they are ideal in the situations in which they are commonly employed, but notwithstanding this, there is a certain amount of difficulty in effectively joining the end of one member two the side or end of another.

Frequently, the lapping flanges of the two members to be joined are spot-welded. This is largely satisfactory but not entirely so because members of the kind under discussion are frequently used and joined in situations where spot-welding equipment is not conveniently available. Moreover, where the members are of galvanised sheet steel, spot-welding destroys the galvanised coating so increasing prospect of corrosion.

Pop riveting has been tried as a fastening for lightweight members of the kind in question. But it has proved unsatisfactory unless the rivets are used in inordinate numbers, a pop rivet necessary being a small-diameter hollow rivet only about 3 mm in outside diameter, and being particularly vulnerable to collapsing under bearing loads and loads in shear.

For these light-weight members, self-tapping or similar screws have been tried, but owing to the thinness of the metal they also are vulnerable to thread strippage under load.

Nuts and bolts have been employed as fastenings for light-weight structural members, but although they are effective against failure under bearing or shear stress, they are not always convenient because they involve spanner work on both sides of the joint and the bolt heads are necessarily protrusive on the outer side of the framework or like structure composed of the light-weight members. This can be objectionable where a framework of light-weight members is to be clad with plaster boards or the like.

The object of this invention is to provide joining means for light-weight structural members of the kind described above, by which fastenings such as pop rivets or self-tapping screws may be effectively employed as fastenings without those fastenings being subjected to either bearing or shear stresses.

The invention provides a joint for sheet metal structural members having mutually lapping portins to be connected together, comprising a depression in one of said portions, a protrusion on the other of said portions nested within said depression, registering holes in said portions respectively encircled by said depression and said protrusion, and a fastening for said portions which extends through said holes; said depression and said protrusion having mutually contacting surfaces such that each of those surfaces is the close envelope of the other, thereby to confine the stress in said fastening to tensile stress.

An example of the invention is illustrated in the drawings herewith.

Figure 1 is a perspective view showing the end of an upright channel abut to be nested between the flanges of a horizontal channel.

Figure 2 is a section taken on line 2-2 in Figure 1 but on a considerably enlarged scale and afterthe channels have been nested.

The two light-weight structural members have mutually lapping portions 3 and 4, part 3 having a depression 5 while portion 4 has a protrusion 6.

Depression 5 extends into protrusion 6, as shown, so to fit firmly therein when portions 3 and 4 are in lapping contact. Encircled by the protrusions are registering holes 7 to receive a fastening which may be a pop rivet as indicated at 8 or a self-tapping screw as indicated at 9. The important aspect of depression 5 and a protrusion 6 is that they have contacting surfaces 10 which are closely in contact, each of them being formed as the close-fitting envelope of the other. Because of this close conformity between the contacting surfaces 10, all shear stresses on the joint and all bearing stresses will be taken by the relatively large area peripherally limiting portions of the depressions and the protrusions.

Thus the only force to which the fastening is exposed is such tension as may arise in it in the direction longitudinally of its shank.

It will be appreciated that when nesting the protrusions in the depressions, relative to both flanges of a pair of light-weight channel members; the thinness of the metal permits sufficient resilient deformation of the flanges for one member two be manually nested in the other with a snap-fitting action.

1. A joint for sheet metal structural members having mutually lapping portions to be connected together, comprising a depressing in one of said portions, a protrusion on the other of said portions nested within said depression, registering holes in said portions respectively encircled by said depression and said protrusion, and a fastening for said portions which extends through said holes; said depression and said protrusion having mutually contacting surfaces such that each of those surfaces is the close envelope of the other, thereby to confine the stress in said fastening to tensile stress.

2. A joint according to claim 1 wherein the said members are channels and the depressions and protrusions are formed in the respective flanges of said members.

3. Ajoint according to claim 1 or claim 2 wherein said depressions and said protrusions are of circular form and said holes are disposed centrally thereof.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Joining structural members This invention relates to the joining of light-weight structural members, that is, members usually made by metal rolling from relatively thin gauge sheet metal. A good example of the kind of member with which the present invention is concerned is provided by the commonly used channel rolled from galvanised sheet steel; typical dimensions of the channel being a web width of 75 mm, a flange width of 32 mm and a metal thickness of about 1 mm. Light-weight structural members of the kind in question are commonly used as wall or partition studs in homes, office suites and the like. They are cheap and of light-weight, and although they are not well adapted for use as sidewardly unsupported columns of torsionally stressed members they are ideal in the situations in which they are commonly employed, but notwithstanding this, there is a certain amount of difficulty in effectively joining the end of one member two the side or end of another. Frequently, the lapping flanges of the two members to be joined are spot-welded. This is largely satisfactory but not entirely so because members of the kind under discussion are frequently used and joined in situations where spot-welding equipment is not conveniently available. Moreover, where the members are of galvanised sheet steel, spot-welding destroys the galvanised coating so increasing prospect of corrosion. Pop riveting has been tried as a fastening for lightweight members of the kind in question. But it has proved unsatisfactory unless the rivets are used in inordinate numbers, a pop rivet necessary being a small-diameter hollow rivet only about 3 mm in outside diameter, and being particularly vulnerable to collapsing under bearing loads and loads in shear. For these light-weight members, self-tapping or similar screws have been tried, but owing to the thinness of the metal they also are vulnerable to thread strippage under load. Nuts and bolts have been employed as fastenings for light-weight structural members, but although they are effective against failure under bearing or shear stress, they are not always convenient because they involve spanner work on both sides of the joint and the bolt heads are necessarily protrusive on the outer side of the framework or like structure composed of the light-weight members. This can be objectionable where a framework of light-weight members is to be clad with plaster boards or the like. The object of this invention is to provide joining means for light-weight structural members of the kind described above, by which fastenings such as pop rivets or self-tapping screws may be effectively employed as fastenings without those fastenings being subjected to either bearing or shear stresses. The invention provides a joint for sheet metal structural members having mutually lapping portins to be connected together, comprising a depression in one of said portions, a protrusion on the other of said portions nested within said depression, registering holes in said portions respectively encircled by said depression and said protrusion, and a fastening for said portions which extends through said holes; said depression and said protrusion having mutually contacting surfaces such that each of those surfaces is the close envelope of the other, thereby to confine the stress in said fastening to tensile stress. An example of the invention is illustrated in the drawings herewith. Figure 1 is a perspective view showing the end of an upright channel abut to be nested between the flanges of a horizontal channel. Figure 2 is a section taken on line 2-2 in Figure 1 but on a considerably enlarged scale and afterthe channels have been nested. The two light-weight structural members have mutually lapping portions 3 and 4, part 3 having a depression 5 while portion 4 has a protrusion 6. Depression 5 extends into protrusion 6, as shown, so to fit firmly therein when portions 3 and 4 are in lapping contact. Encircled by the protrusions are registering holes 7 to receive a fastening which may be a pop rivet as indicated at 8 or a self-tapping screw as indicated at 9. The important aspect of depression 5 and a protrusion 6 is that they have contacting surfaces 10 which are closely in contact, each of them being formed as the close-fitting envelope of the other. Because of this close conformity between the contacting surfaces 10, all shear stresses on the joint and all bearing stresses will be taken by the relatively large area peripherally limiting portions of the depressions and the protrusions. Thus the only force to which the fastening is exposed is such tension as may arise in it in the direction longitudinally of its shank. It will be appreciated that when nesting the protrusions in the depressions, relative to both flanges of a pair of light-weight channel members; the thinness of the metal permits sufficient resilient deformation of the flanges for one member two be manually nested in the other with a snap-fitting action. CLAIMS

1. A joint for sheet metal structural members having mutually lapping portions to be connected together, comprising a depressing in one of said portions, a protrusion on the other of said portions nested within said depression, registering holes in said portions respectively encircled by said depression and said protrusion, and a fastening for said portions which extends through said holes; said depression and said protrusion having mutually contacting surfaces such that each of those surfaces is the close envelope of the other, thereby to confine the stress in said fastening to tensile stress.

2. A joint according to claim 1 wherein the said members are channels and the depressions and protrusions are formed in the respective flanges of said members.

3. Ajoint according to claim 1 or claim 2 wherein said depressions and said protrusions are of circular form and said holes are disposed centrally thereof.

4. A joint for structural members substantially as herein described with reference to the drawings herewith.