GB2200392A

GB2200392A - Arch former

Info

Publication number: GB2200392A
Application number: GB8728321A
Authority: GB
Inventors: Ian C Christison; Stanley Sutton
Original assignee: Expanded Metal Co Ltd
Current assignee: Expanded Metal Co Ltd
Priority date: 1986-12-04
Filing date: 1987-12-03
Publication date: 1988-08-03
Anticipated expiration: 2007-12-03
Also published as: GB2200392B; GB8728321D0

Abstract

An arch former for use in dry-lining wall construction comprises a curved mesh wall section (8) to form the inner surface of the arch and a plaster bead (9) to define the line of the arch. The plaster bead has a first flange (10) connected to the curved wall section (8), and a second, slotted, flange (11) extending substantially at right angles to the first flange for attachment to the outer face of the wall lining around the arch. The bead itself includes means (14) for rigidifying the second flange to maintain the shape of the arch former. <IMAGE>

Description

ARCH FORMER The present invention relates to preforms for the construction of decorative, plastered arches in walls, and, more particularly, to preforms or "arch formers" as they are often known, for use in constructing arches in dry-lined walls.

From GB 1590298 it is known to construct an arch former to provide a key for plaster at an opening in a wall, the arch former comprising at least a pair of mesh wall sections, one for forming part of the curved surface of the arch and the other for forming the upright face of the wall around the arch. The two sections are joined together and, preferably, as described in GB-B-2015633, a plaster bead is formed at the junction between the component parts of the arch former so as to define the line of the arch and provide a smooth plaster edge in use.

It is known to construct arch formers of this general type from three elements, a pair of expanded metal wall sections, one curved and one planar, and a continuous bead section securely fixed to the wall sections and defining the arch line and a smooth plaster edge in use.

Whilst the known constructions are useful in producing arches in solid, brick or block walls which require conventional plastering, the use of such arch formers in dry-lined walls, that is walls of laminated plasterboard, or of plasterboard fixed to timber or metal stud framing or to bricks or blocks, is not very satisfactory. This is because dry-lined walls require only a very thin plaster skim feathered back for approx. 150mm, and the presence of the planar wall section of the arch former over the plasterboard requires a thicker layer of plaster to be provided, which will be unsightly, unless a very thick layer of plaster is provided and which is feathered back along the surface of the wall a long way to prevent the plaster around the arch giving an irregular, unsmooth appearance to the wall.

Furthermore, as the wall around the arch would generally be fully defined by the plasterboard, the planar mesh wall section of the arch former would represent a waste of material.

There is a need therefore for an arch former for use in dry-lined wall construction which, whilst providing a curved mesh section for plastering the internal face of the arch and a suitable plaster bead, does not suffer from the disadvantages involved in using a conventional arch former. It has been suggested to form such an arch former with merely a mesh wall (which can be bent to the required curve) and an edge bead which has a pair of right-angled flanges. One of the flanges is fixed to the mesh wall section and the other is formed with a series of slots extending from the edge of the flange towards the bead so as to allow the arch former to be bent to any required curve, the slots being opened up during the bending process to enable the slotted flange to deform as required.However, this proposal is unsatisfactory as the bead, after bending, lacks rigidity and therefore the arch former is not self shape sustaining and therefore the arch may not be accurately formed in practice. Furthermore, the arch former has to be bent to shape on site, which may be innacurate in any case and may take up valuable time.

According to the present invention therefore, there is provided an arch former for use in dry-lining wall construction, comprising a curved mesh wall section to form the inner surface of the arch and a plaster bead to define the line of the arch, the plaster bead having a first flange connected to the curved wall section, and a second, slotted, flange extending substantially at right angles to the first flange for attachment to the outer face of the wall lining around the arch, the bead itself including means for rigidifying the second flange to maintain the shape of the arch former.

The first flange may be attached to the curved wall section, for example, by spot welding, or, alternatively, the bead may be formed integrally with the curved wall section, so that the curved wall section is formed by, or is at least a continuation of, the first flange. If they are both made of the same material,- such as similarly expanded metal mesh, there may then be no tangible indication where the first flange finishes and the wall section begins.

Both flanges of the bead may be made of expanded metal mesh, in which case the central arcuate portion of the bead may either be bent from an expanded metal portion which is a continuation of the flanges, or be made of a non-expanded portion.

The means for rigidifying the second flange may comprise an elongate member, such as a bracing wire, a metal strip, or a plastics section, fixed to the second flange, and which has sufficient rigidity to maintain the widths of the slots resulting from spreading of the second flange during bending. The elongate member may be secured to the second flange by welding or crimping, but adhesive bonding, or, in the case of a thermoplastics member, thermo-fusion or -deformation, is possible, particularly if at least the bead is made of a thermoplastics material.

Alternatively, the second flange may be formed initially with a plurality of closed slits defining strands therebetween, the slits being expanded in an operation to bend the bead to the required shape and the strands, after deformation, maintaining the shape of the second flange and thus the curved shape of the arch former after bending.

A further alternative involves stamping an integral tongue in each of the sections of the second flange, whereby, after the former has been bent to shape, the tongue may be bent through substantially 1800 so that it bridges the adjacent slit and may be fixed, e.g. by spot welding, to the adjacent section. Most conveniently, each tongue is an elongate rectangular tongue formed by cutting along two longer and one shorter edges of the tongue, the tongue being positioned adjacent to the free edge of the second flange with its longer sides extending longitudinally of the second flange.

One example of an arch formed in a dry-lined wall by means of arch formers according to the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a sketch of the arch from one side; Figure 2 shows a cross-section through the arch; and, Figure 3 is a perspective view of an arch former segment of the arch shown in Figures 1 and 2.

In a dry-lining wall construction in which the surface of the wall 1 is lined with plasterboards 2, an arch can be formed by appropriate cutting of the plasterboards 2 on either side of the wall. The wall shown in Figure 2 is of conventional timber frame 3 construction on to which the plasterboards 2 have been fixed by nails 6. By means of arch formers 4 in conjunction with the shaped plaster boards 2, a decorative curved arch may be formed without the need for formation of a curved arch in the blockwork or brickwork itself. Thus the wall above the arch may be supported by a conventional lintel. On both sides of the arch (if desired) and in its centre as shown, straight segments 5 may also be provided. The sides of the arch may, conventionally, be formed from plasterboard with corner beads 5'.

In order to construct the arch, four curved arch former segments are required, one to provide each half of the curve of the arch on each side of the wall. As is most clearly seen from Figure 2, in use, each pre-formed arch former segment is nailed through the curved edge of the -plasterboard 2 into the frame 3 beneath by means of suitable nails 6' and opposed arch former segments 4 on either side of the wall are likewise fastened together by wire ties 7.

It is important that the arch formers have a consistent shape, but at the same time wastage of material is obviously to be avoided and therefore each pre-form comprises a curved mesh wall section 8 preferably formed of expanded metal mesh, but alternatively of perforated or woven metal mesh, and a bead 9 having a pair of generally right angled flanges 10, 11 joined by a nib 12. The flanges 10 are spot welded to the expanded metal mesh wall section 8 and each of the flanges 11, in the example shown, has plural slits 13 extending across the flange 11 to enable the bead to be curved in the plane of the flange 11 during manufacture.

Alternatively, the bead 9 may be formed integrally with the curved wall section 8, so that the curved wall section 8 is formed by, or is at least a continuation of, the first flange 10. If they are both made of the same material, such as similarly expanded metal mesh, there may then be no tangible indication where the first flange 10 finishes and the wall section 8 begins.

Both flanges 10, 11 of the bead may be made of expanded metal mesh, in which case the central arcuate portion of the bead may either be bent from an expanded metal portion which is a continuation of the flanges, or be made of a non-expanded portion as shown.

However, as it is important to maintain the shape of the arch former to produce a symmetrical and smoothly curved arch, after bending of the bead 9, a bracing wire 14 is spot welded to the edge of the flange 11 to maintain the slits in their opened condition and thus rigidify the flange 11, the bead 9 and the arch former as a whole.

Although the present example illustrates the use of a bracing wire 14, it is envisaged that an alternative construction may employ the use of an elongate member, such as metal strip or a plastics section, fixed to the second flange by welding, crimping, adhesive bonding, or, in the case of a thermoplastics member, thermo-fusion or -deformation, particularly if at least the bead is made of a thermoplastics member.

Alternatively, the construction may employ the use of a flange 11 having closed slits regularly separated by metal strands so that, as in a conventional expanded metal mesh forming operation, the slits can be opened up during bending of the bead, the strands between the slits thereafter maintaining the shape of the bead due to their deformation during bending.

Claims

1. An arch former for use in dry-lining wall construction, comprising a curved mesh wall section to form the inner surface of the arch and a plaster bead to define the line of the arch, the plaster bead having a first flange connected to the curved wall section, and a second, slotted, flange extending substantially at right angles to the first flange for attachment to the outer face of the wall lining around the arch, the bead itself including means for rigidifying the second flange to maintain the shape of the arch former.

2. An arch-former according to claim 1, in which the first flange is attached to the curved wall section to fix the curved wall section to the plasterbead.

3. An arch-former according to claim 2, in which the first flange is spot-welded to the curved wall section.

4. An arch-former according to claim 1, in which the plaster bead is formed integrally with the curved wall section.

5. An arch-former according to any of claims 1 to 4, in which both flanges of the bead are formed of expanded metal.

6. An arch-former according to claim 5, in which the central arcuate portion of the bead is bent from an expanded metal portion.

7. An arch-former according to any of claims 1 to 5, in which the central arcuate portion of the bead is bent from an unexpanded metal portion.

8. An arch-former according to any of claims 1 to 7, in which the means for rigidifying the second flange comprises an elongate member, such as a bracing wire, a metal strip, or a plastics section, fixed to the second flange, and which has sufficient rigidity to maintain the widths of the slots resulting from spreading of the second flange during bending.

9. An arch-former according to any of claims 1 to 7, in which the second flange is formed initially with a plurality of closed slits defining strands therebetween, the slits being expanded in an operation to bend the bead to the required shape and the strands after deformation, maintaining the shape of the second flange and thus the curved shape of the arch former after bending.

10. An arch-former according to any of claims 1 to 7, in which each section of the second flange has an integral tongue, whereby, after the former has been bent to shape, the tongue may be bent through substantially 180 so that it bridges the adjacent slit and may be fixed, e.g. by spot welding, to the adjacent section.

11. An arch-former according to claim 10, wherein each tongue is elongate and rectangular and is formed by cutting along two longer and one shorter edges of the tongue, the tongue being positioned adjacent to the free edge of the second flange with its longer sides extending longitudinally of the second flange.

12. An arch-former substantially as described with reference to the accompanying drawings.