GB2178457A - Constructional member of variable geometry - Google Patents

Abstract

A constructional member which can be used to form a non-linear frame comprises two elongate elements connected together, e.g. by a dovetail joint, so that one element can be moved longitudinally relative to the other. The elements are flexible and can be flexed into a non-linear configuration and held in that configuration for example by pins 28. Uses Exhibition stands, partitions, frameworks for transparent barriers, wind-generator blades, rotating governors, draughtsman's curves, model roads, leaf-springs. <IMAGE>

Description

SPECIFICATiON Constructional member of variable geometry This invention relates to a constructional element and more particularly a constructional member of variable geometry.

It is a common requirement in construction, particularly in the construction of partitions, exhibition stands and the like for curved, serpentine or like panels to be provided. These constructions are normally made by taking a flat panel and constraining it in the desired curved, serpentine or like configuration by a suitably shaped frame. There are a number of problems associated with this type of construction. First the frame must be purpose made to the desired configuration and that is expensive. Secondly the flat panel must be appropriately bent to fit into the frame. This can be a time consuming exercise and moreover quite difficult to accomplish where complex shapes are required.

The present invention has been made from a consideration of these points.

According to the invention there is provided a constructional member comprising two elongate elements interconnected together so that the elements can move longitudinally relative to one another but being otherwise unseparable, said elements being flexible so that the member can be flexed and held in a flexed disposition by means restraining relative movement of the elements.

By the invention, therefore, the member may be held in a curved or other than straight disposition by means such as pins which are within the member itself rather than some external constraining means. The interconnection between the elements may be continuous along their length or may be provided at one or more locations. The interconnection between the elements must prevent separation thereof except by sliding one element longitudinally with respect to the other. Any form of interconnection that meets this requirement can be used, for example, a dovetail connection.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a transverse cross-section through a member; Figure 1A is a perspective view of the member of Figure 1 in a curved condition; Figures 2 to 5 are transverse cross-sections through further embodiments of a member; Figures 2A to 5A are perspective views of the members of Figures 2 to 5 respectively; Figures 6, 6A, 7, 7A, 8 and 8A are transverse cross-section through three further modifications of the member of Figures 1 and 1 A; Figure 8A illustrates the member of Figure 8 fitted onto a panel; Figure 9 shows a panel; Figures 70 to 12 illustrate arrangements for restraining relative movement of the elements forming a member; and Figure 13 represents a curved assembly.

Referring to the drawing Figure 1 shows a simple rectangular cross-section 2 of two members 4 and 6 interlocked by means of a dovetail slot and key 8. As illustrated in principle by Figure 2, the overall crosssection 10 and form of the key 12 could be any shape.

Figure 3 illustrates a circular cross-section 14 with a circular form of key 16.

Such members may be produced in any suitable material and may be manufactured by any appropriate means. As one example, one or both elements of the members illustrated in Figures 1 or 3 could be of extruded plastics such as polycarbonate.

The interface between the two elements forming the member will normally be a principal interface, for example plane 18 in Figure 1, broken by the shape of the key 8, being extended from one element 4 beyond the plane, with a corresponding recess in the other element 6. The overall member can be flexed perpendicular to the principle interface, as shown in Figures 1A and 3A.

It is found that very little restraint is required to maintain the member curved in the desired position.

Such restraints can be restricted to each end of a member of single curvature, or at each end and at intermediate points where there is a change of curvature, for example at points of contraflexure in a member whose centre of curvature alternated from one side to the other. Any number of intermediate points or lines of restraint can be incorporated, to achieve any desired changes of curvature along the length of the member.

The member may be divided into more than two elements for particular purposes, for example with two or more principle interface planes in parallel (Figure 4), or two interface planes perpendicular to each other (Figure 5), to enable the member to be adjusted to achieve curvature in two directions as in Figure 5A, sometimes referred to as double curvature.

Such curved members may be of use independently or may form part of an assembly, such as a building partition or modular display or curved glazing bar assembly, which latter might be used, for example, in barrel vault roofs. For such applications, it can be beneficial to provide other features into the uniform cross-section, such as a channel or channels 19 to accommodate a panel or panels 21, as illustrated in Figures 6, 6A, 7 and 7A. Sealing means can be associated with such sheet materials, such as tubular seals 22 partially received in grooves 20 in the side walls of the channel as shown in Figure 8 to create a seal between the member and the sheet 21, so as to keep our rainwater or draughts, for example.For such uses, the member of the invention can be used in conjunction with other elements, for example with vertical posts 24 in a partition assembly or with supporting edge beams 26 in a barrel vault assembly, as shown in Figure 9.

Additionally, the invention allows a curved member to be produced, stored and transported in straight sections, rather than in curved sections. This can have considerable economic advantages in production, storage and transport, as well as enabling materials to be used which could otherwise not be used for such purposes, or which otherwise would have to be of significantly greater cross-section in order to be used for such purposes. For example, straight extruded polycarbonate sections can be made, stored and transported more cheaply than curved sections. The invention provides a method of manufacture that is much cheaper than, for example, casting, machining, or other means of forming a particular curved member out of polycarbonate.The cross-sectional dimensions required to restrain associated sheeting in a curved condition are less than would normally be used, as initial deflection of a preformed member does not have to be allowed for. For example, a flat sheet of polycarbonate could be curved and restrained in the desired curved position by means of the invention being attached at one or more sides, to achieve the desired shape. Polycarbonate material is only cited as an example, and similar benefits in material cost, manufacturing cost, storage, transport and assembly can be achieved with a wide range of other materials.

A further advantage is that framing members according to the invention can be made of the same material as sheet members, thus overcoming such problems as relative thermal movement that can otherwise occur in such installations, for example, within patent glazing assemblies of polycarbonate sheet material restrained in a curved condition by curved aluminium sections.

Thus the invention enables the assembly of relatively large areas of enclosure in a single material which do not require complex constructional provisions to accommodate thermal movement within them. If such assemblies are required to be waterproof or draughtproof, simple sealing provisions can be made, such as continuous tube seals or the application of silicone sealant between the members of the invention and the restrained sheeting. Such simple provisions are not found to be effective in many existing situations, for example patent glazing systems involving metal frames with sheets of other materials. Further, the construction of such sealed assemblies is facilitated by the fact that the assemblies can be prepared flat without the difficulties of bending and inserting a flat sheet within a pre-formed curved section without damaging associated seals.The overall assembly can then be curved from the flat by bending the members of the invention and applying the required restraints. An alternative method of sealing a glazing assembly is to inject sealant into the cross-sectional gap between the member and restrained sheeting.

Another advantage of the invention is that it enables a screen or barrier to be made with sheet transparent materials without the necessity for additional supporting structural frameworks which would provide obstruction to through vision. For example, such transparent barriers can be provided in sports stadiums between the playing area and the public. Polycarbonate or other plastic sheet can be extruded into long lengths. Such sheeting, by virtue of its thickness and flexibility, normally requires associated structural framing to provide a screen or barrier. However, if a long sheet of such material were suitably curved, for example in the form of a sine curve on plan, and the sheet was restrained at its base, the overall assembly can be designed to be stable against wind and certain crowd loading conditions.However, because of the tendency of the sheets to unbend at the top edge, internal stresses within such sheets, tolerances of construction and other factors, an irregular and unsightly curve would result at the top of the sheets if unrestrained. In Figure 13, a continuous member 34 of the invention along the upper edge would enable the strong pre-curved section 36 to be maintained along the length of the installation in accordance with the intended geometry, having constructional strength and visual advantages. Vertical restraining posts are not required, at least not within the ends of continuous sheets and, because the member of the invention can be relatively slender and of a transparent or transluscent colourless material, a strong and virtually obstruction free assembly is provided.

Members of the invention are adapted to maintain their desired shape by means of individual points or lengths of restraint or by friction between the elements comprising the member cross-section or, more commonly, a combination of these features. For certain applications, one or more of the interface surfaces of the member may be suitably roughened or machined to be sufficiently rough, or ribbed, or otherwise made to cause the two elements to grip each other sufficiently to maintain a curved shape without additional points or lengths of restraint. Alternatively, a variety of different types of restraint can be incorporated internally, within the cross-section of the member, to effectively fix the relative position of the two elements at a single point or for a distance along its length.For example, a cylindrical pin 28 can be introduced parallel to or perpendicular to a principle interface plane, as illustrated in Figures 10 and 11 respectively. Alternatively, a separate element may be introduced, such as an end block 30, as illustrated in Figure 12, that is fixed to the end of the member after the number has been curved to the desired profile. The block is secured by any technique, such as a self tapping screw 32 or adhesive.

Such an end block can also form or be a part of a connection to other framing elements within a system, for example having a protruding cleat or key to connect a horizontal framing member of the invention to a vertical post, which may be in accordance with the invention or any other form of construction.

Alternatively, points of restraint may be introduced which become automatically effective after the member has been flexed to the required shape, for example spring loaded clips similar to those presently used in frame tent assemblies.

The embodiments described so far have concerned forming members according to the invention to required shapes for particular installations. A further advantage of the invention is that a single member is adjustable to a variety of curves so that the number and shape of curves can be varied between installations. Thus members can be returneu to a straight condition for transport and storage between uses.

Additionally, the members according to the Invention may be used for situations where continuously or frequently changing geometry is desirable, for example, in wind generator blades or as may be used in a rotating governor device that would not require a hinge, a member of the invention with one free end being able to vary its geometry according to the centrifugal forces imposed upon it. Members of the invention could be used to produce curves of variable shape, for example to assist the setting out of curves on a production shop floor, or of curved elements in a building such as walls curved on plan, arches, etc., and either the member could be temporary or form part of the finished installation.There is a large range of other uses for such variable geometry members, for example, in the achievement of enclosures for market gardening of varying size, depending upon specific needs at particular times.

The invention also finds application in toys, model making and various other forms of simulation. For example, it can be used as an economical modelling device to illustrate motorway or other road routes, the road cross-section markings, etc., being continuous but the alignment being variable and capable of being superimposed, for example, on suitably scaled plans.

It is not essential that members according to the invention be manufactured from straight elements that are interlocked and then curved into a required shape.

Members can be formed from curved elements which can then be altered to a different curvature. For example the invention can be used to manufacture a self-dampening leaf spring, manufactured straight or curved, although a curved shape is normally advantageous in allowing space for the required flexing, for example between a vehicle axle and body. In such installations, the interlocking arrangement of elements acts as a dampening device, through a combination of friction and secondary bending forces incurred in flexure out of the manufactured geometry.

Adhesive can also be injected inside the member between the elements to product a composite section after flexure, and to increase its bending strength about the interface plane. Alternatively composite action can be achieved by the introduction of shear studs after introducting curvature. If adhesive is unsuitable for whatever reason, then the edges of the slot and key can be ribbed and a gap created between the rib bed surfaces, which may then have a material injected within it which will cure inside the opposing rib bed surfaces and effect a shear key longitudinally, to both lock the member in its desired curved position and increase its resistance to bending about the principal plane.

Claims (9)

1. A constructional member comprising two elongate elements interconnected together so that the elements can move longitudinally relative to one another but being otherwise unseparable, said elements being flexible so that the member can be flexed and held in a flexed disposition by means restraining relative movement of the elements.

2. A constructional member as claimed in Claim 1, wherein the restraining means is located within the member.

3. A constructional member as claimed in Claim 1 or Claim 2, wherein the elongate elements are connected together by a key in one element received in a slot in the other element.

4. A constructional member as claimed in any preceding ciaim, wherein more than two elongate elements are provided.

5. A constructional member as claimed in Claim 4, wherein the elongate elements are arranged with adjacent interconnecting faces substantially parallel.

6. A constructional member as claimed in Claim 4, wherein the elongate elements are arranged with adjacent interconnecting faces substantially perpendicular to each other.

7. A frame comprising a constructional member as claimed in any preceding claim.

8. A constructional member substantially as described herein with reference to any of Figures 1 to 8 and 10 to 12 of the accompanying drawings.

9. A frame as claimed in Claim 7 substantially as described herein with reference to any of the Figures of the accompanying drawings.